Dermatology [4 ed.]
 9780702062759, 9780702063428

Table of contents :
Cover
Front Matter
Copyright
Video Table of Contents
Preface
User Guide
Volumes, Sections and Color Coding
Volume One
Volume Two
Basic Science Chapters
Therapeutic Ladders
Dermatology Website
Dedication
Figures and Tables
Section 1: Overview of Basic Science
Chapter 0: Basic Principles of Dermatology
Abstract
Keywords:
Chapter Contents
Introduction to Clinical Dermatology
Etiologic Premises
Inflammatory versus neoplastic
Morphology
Palpation and appreciation of textural changes
Color
Variation in skin color within the human population
Configuration and Distribution
Configuration
Distribution
Augmented Examination – Wood’s Lamp and Dermoscopy
Temporal Course
The Role of Dermatopathology in Clinicopathologic Correlation
The Skin Biopsy
Site selection
Biopsy techniques
Handling of the specimen after biopsy
Classification of Inflammatory Skin Diseases by Pattern Analysis
Ten patterns defined
Perivascular dermatitis
Interface dermatitis
Spongiotic dermatitis
Psoriasiform dermatitis
Vesiculobullous and pustular dermatoses
Intraepidermal (see Fig. 0.14E)
Subepidermal vesiculation (see Fig. 0.14F)
Vasculitis/pseudovasculitis
Nodular and diffuse dermatitis
Folliculitis/perifolliculitis
Fibrosing/sclerosing conditions
Panniculitis
Invisible dermatoses
Deposition of Materials Within the Skin
Histologic Stains
Immunohistochemical Testing
Introduction to the Use of Dermoscopy (Dermatoscopy)
Conclusion
References
Chapter 1: Anatomy and Physiology
Abstract
Keywords:
Introduction
Structure and Function
Conventional Concepts of the Structure of Skin
Epidermis
Dermis
Dermal–epidermal interface
Knowledge of the Function and Structure of Skin Begins With Skin Disease
The Central Role of Protecting DNA as a Function of Skin
The requirements of skin are identified in its failings
Preventing Infection: Skin as an Immunologic Organ
Failure of immunity: infection
Warts
Dermatophytosis
Opportunistic infections in the setting of human immunodeficiency virus infection
Leprosy (Hansen disease)
Faulty immunity: autoimmunity
Failure of immunity: cancer
Maintaining a Barrier: Skin as a Protective Organ
Failure of protection against toxic chemicals
Failure to protect against dehydration and infection: toxic epidermal necrolysis
Failure to protect against UV radiation: albinism
Maintaining the Integrity of Skin: Repair Mechanisms
Failure to effectively repair injury
Delayed wound healing
Keloids
Xeroderma pigmentosum
Providing Circulation: Skin as a Nutritive Organ
Failure of circulation: arteries and veins
Embolic occlusion of arteries
Vasculitis
Occlusive vasculopathy
Venous insufficiency
Failure of circulation: lymphatic blockage
Interfacing With External and Internal Environments: Skin as a Communicating Organ
Abnormality of neurologic communication: excessive sensitivity
Abnormality of neurologic communication: excessive sweating
Abnormality of neurologic communication: decreased sensitivity
Communication via hormones and cytokines
Hormones
Cytokines
Cellular communication
Failure of cytokine and cellular communication
Regulating Temperature: Skin as a Thermoregulatory Organ
Failure of thermoregulation: effects of excessive heat
Heat injury as therapy
Failure of thermoregulation: effects of excessive cold
Cold injury as therapy
Interpersonal Communication: the Skin Conveys Beauty, Attracts Attention and Contributes to Self-Identity
Failures to present an attractive appearance
Pigmentary turmoil
Inappropriate hair distribution
Undesirable fat distribution
The next steps
An Important Corollary, With an Eye to the Future
Acknowledgment
References
Chapter 2: Skin Development and Maintenance
Abstract
Keywords:
Chapter Contents
Introduction
Embryonic Origin of the Skin
Epidermal Development
Clinical Relevance
Development of Specialized Cells Within the Epidermis
Clinical Relevance
Development of the Dermis and Subcutis
Clinical Relevance
Development of the Dermal–Epidermal Junction
Clinical Relevance
Development of Skin Appendages (Adnexae)
Hair Follicle Development
Nail Development
Eccrine and Apocrine Sweat Gland Development
Clinical Relevance
Skin Stem Cells
Epidermal Stem Cells
Hair Follicle Stem Cells
Stem Cell Plasticity
Stem Cell-Based Therapy for Genetic Skin Disease
Prenatal Diagnosis of Genodermatoses
Significance of Skin Development in Postnatal Life
References
Chapter 3: Molecular Biology
Abstract
Keywords:
Introduction
Experimental Techniques
Tissue Processing
The Foundations of Molecular Techniques for Analyzing DNA, RNA, and Protein
Measuring Spatial Distribution Within Tissues
Measuring the Transcriptome and Proteome
Genetically Engineered Mouse Models
Gene-Based Therapy for Skin Diseases
Conclusions
Copyright notice
References
Chapter 4: Immunology
Abstract
Keywords:
Introduction
Innate Immune Response
Complement
Toll-Like Receptors
Inflammasomes
Antimicrobial Peptides
Cytokines
Macrophages and Neutrophils
Eosinophils
Basophils and Mast Cells
Natural Killer Cells
Adaptive Immune Response
Antigen-Presenting Cells
Langerhans cells
Morphology of Langerhans cells
Ontogeny of Langerhans cells
Other dendritic cells
Antigen presentation
Antigen presentation cells: activation and migration
Antigen presentation to T cells
T Cells
T-cell development
T-cell receptor
T-cell receptor diversity
T-cell receptor signaling
Costimulatory signals
Clonal expansion
Effector functions of T cells
T helper cells
Cytotoxic T cells
Regulatory T cells
Natural killer T cells
γ/δ T cells
Dendritic epidermal T cells
Innate lymphoid cells
Lymphocyte recruitment
B Cells
Immunoglobulins
Immunoglobulin M
Immunoglobulin G
Immunoglobulin A
Immunoglobulin E
Immunoglobulin D
B-cell activation
Allergic Contact Hypersensitivity
Induction of CHS
Elicitation of CHS
Keratinocytes as immune targets and initiators
References
Section 2: Pruritus
Chapter 5: Cutaneous Neurophysiology
Abstract
Keywords:
Chapter Contents
Introduction
Pruritus Pathways
Central Pathways to Higher Nervous System Centers
Pruritus Receptor Units
Mediators of Pruritus
Histamine
Gastrin-Releasing Peptide
B-Type Natriuretic Peptide
Proteases
Opioid Peptides
Substance P
Neurotrophins
Prostanoids
Mediators That Activate Transient Receptor Potential Receptors
Other Peripheral Mediators of Itch
Other neurotransmitters
Peptidases
Other mediators with potential roles in itch
Immune Cells as Itch Mediators and Modulators
Chronic Itch
Peripheral Sensitization in Chronic Itch
Central Sensitization in Chronic Itch
Itch Related to Impaired Skin Barrier Function
Senescent Skin and Itch
Cholestatic Pruritus
Treatment of Pruritus
Pharmacologic Treatments
Behavioral Therapy
Future Directions
References
Chapter 6: Pruritus and Dysesthesia
Abstract
Keywords:
Chapter Contents
Introduction
Epidemiology
Evaluation of the Patient
History
Examination
Laboratory Investigation
Pruritus in Dermatologic Disease
Inflammatory Dermatoses
Urticaria
Atopic dermatitis
Psoriasis
Infestations
Scabies
Pediculosis (lice)
Cutaneous T-Cell Lymphoma (CTCL)
Dermatoses Induced by Pruritus-Associated Scratching or Rubbing
Prurigo Nodularis
Lichen Simplex Chronicus
Pruritus in Specific Locations
Scalp Pruritus
Anogenital Pruritus
Pruritus ani
Pruritus vulvae and scroti
Pruritus Variants
Aquagenic Pruritus
Pruritus in Scars
Post-Thermal Burn Pruritus
Fiberglass Dermatitis
Pruritus in Systemic Disease
Renal Pruritus
Cholestatic Pruritus
Hematologic Pruritus
Iron deficiency
Polycythemia vera
Pruritus and Malignancy
Hodgkin disease
Non-Hodgkin lymphoma
Leukemia
Endocrine Pruritus
Thyroid disease
Diabetes mellitus
Pruritus in HIV Infection and AIDS
Pruritus in Pregnancy
Pharmacologic Pruritus
Psychogenic Pruritus
Neurologic Etiologies of Pruritus and Dysesthesia
Sensory (Mono)Neuropathies With Pruritus and Dysesthesia
Notalgia paresthetica
Brachioradial pruritus
Meralgia paresthetica
Cheiralgia paresthetica
Digitalgia paresthetica
Regional Dysesthesias With Burning or Pain
Burning mouth syndrome
Burning scalp syndrome
Dysesthetic anogenital pain syndromes
Trigeminal neuralgia and trigeminal trophic syndrome
Complex regional pain syndrome (reflex sympathetic dystrophy)
Congenital Insensitivity to Pain and Related Conditions
Treatment
General Measures
Topical Treatment
Systemic Treatment
Physical Treatment Modalities
Psychological Approaches
References
Chapter 7: Psychocutaneous Diseases
Abstract
Keywords:
Introduction
Overview
Primary Psychiatric Disorders With Dermatologic Manifestations
Delusions of Parasitosis
Introduction
Clinical features
Epidemiology
Differential diagnosis
Management
General Features of Obsessive–Compulsive and Related Disorders
Body Dysmorphic Disorder
Introduction
Clinical features
Epidemiology
Management
Trichotillomania
Introduction
Clinical features
Epidemiology
Diagnosis and pathology
Differential diagnosis
Management
Excoriation Disorder
Introduction
Clinical features
Epidemiology
Differential diagnosis
Management
Acne Excoriée
Clinical features and epidemiology
Management
Dermatitis Artefacta
Introduction
Clinical features
Pathology
Epidemiology
Differential diagnosis
Management
Nonsuicidal Self-Injury
Clinical features and epidemiology
Management
Excessive Tanning Behavior
Secondary Psychiatric Disorders Resulting From Dermatologic Conditions
Somatic Symptom Disorder
Illness Anxiety Disorder
Treatment
References
Section 3: Papulosquamous and Eczematous Dermatoses
Chapter 8: Psoriasis
Abstract
Keywords:
Introduction
History
Epidemiology and Genetics
Genetic Factors
HLA studies
Genome-wide association studies
Functional genomic studies
Pathogenesis
Immunopathogenesis
Role of T cells and dendritic cells
Cytokines and chemokines
Innate immunity and role of keratinocytes
Triggering Factors
External triggering factors
Systemic triggering factors
Infections
HIV
Endocrine factors
Psychogenic stress
Drugs
Alcohol consumption, smoking and obesity
Clinical Features
Chronic Plaque Psoriasis
Guttate Psoriasis
Erythrodermic Psoriasis
Pustular Variants
Generalized pustular psoriasis
Pustulosis of the palms and soles
Acrodermatitis continua of Hallopeau
Special Locations
Scalp psoriasis
Flexural psoriasis
Oral mucosa
Nail psoriasis
Psoriatic Arthritis
Disorders Related to Psoriasis
Inflammatory linear verrucous epidermal nevus (ILVEN)
Reactive arthritis (formerly Reiter disease)
Sneddon–Wilkinson disease (subcorneal pustular dermatosis)
Associations Between Psoriasis and Other Diseases
Associations with skin diseases
Infections
Cancer
Association with internal diseases (including comorbidities)
Differential Diagnosis
Pathology
Papulosquamous Lesions
Initial lesion
Active lesion
Stable lesion
Pustular Psoriasis
Treatment
Topical Treatments
Corticosteroids
Vitamin D3 analogues
Anthralin
Topical retinoids
Additional topical treatments
Photo(chemo)therapy and Systemic Medications
Photo(chemo)therapy
Methotrexate
Cyclosporine
Systemic retinoids
Targeted immunomodulators (“biologic” therapies)
Apremilast and other systemic therapies
Therapeutic Management
General considerations
Management with topical agents
Management with photo(chemo)therapy and classic systemic medications
Targeted immunomodulators (“biologic” therapies)
How to combine treatments
Beneficial combinations
Contraindicated combinations and combinations with restricted use
Management of childhood psoriasis
Management of psoriasis in patients with comorbidities
Future Developments and Treatments
References
e-References
Chapter 9: Other Papulosquamous Disorders
Abstract
Keywords:
Chapter Contents
Small Plaque Parapsoriasis
Introduction
History
Epidemiology
Pathogenesis
Clinical Features
Pathology
Differential Diagnosis
Treatment
Large Plaque Parapsoriasis
Introduction, History, and Epidemiology
Pathogenesis
Clinical Features
Pathology
Differential Diagnosis
Treatment
Pityriasis Lichenoides et Varioliformis Acuta and Pityriasis Lichenoides Chronica
Introduction
History
Epidemiology
Pathogenesis
Clinical Features
Pathology
Differential Diagnosis
Treatment
Pityriasis Rubra Pilaris
History
Epidemiology
Pathogenesis
Clinical Features
Pathology
Differential Diagnosis
Treatment
Pityriasis Rosea
Introduction
History
Epidemiology
Pathogenesis
Clinical Features
Pathology
Differential Diagnosis
Treatment
Pityriasis Rotunda
Introduction
History
Epidemiology
Pathogenesis
Clinical Features
Pathology
Differential Diagnosis
Treatment
Granular Parakeratosis
Introduction
History
Epidemiology
Pathogenesis
Clinical Features
Pathology
Differential Diagnosis
Treatment
References
Chapter 10: Erythroderma
Abstract
Keywords:
Introduction
Historical Perspective
Epidemiology
Pathogenesis
Clinical Features
Cutaneous Manifestations
Systemic Manifestations
Specific Findings of the Underlying Disease
Psoriasis
Atopic dermatitis
Drug reactions
Idiopathic erythroderma
Cutaneous T-cell lymphoma (Sézary syndrome and erythrodermic mycosis fungoides)
Pityriasis rubra pilaris
Papuloerythroderma of Ofuji
Paraneoplastic erythroderma
Bullous dermatoses
Ichthyoses
Staphylococcal scalded skin syndrome
Omenn syndrome
Pathology
Differential Diagnosis
Treatment
References
Chapter 11: Lichen Planus and Lichenoid Dermatoses
Abstract
Keywords:
Chapter Contents
Lichen Planus
Introduction
History
Epidemiology
Pathogenesis
Target antigens
Hepatitis C virus
Other viruses
Vaccines
Bacteria
Contact allergens
Drugs
Autoantigens, including tumor antigens
Effector cells
The innate immune system, regulatory T cells (Tregs), and Th17 cells
Effector T cells’ access to the epidermis
Sweating disturbance
Clinical Features
Actinic LP
Acute (exanthematous) LP
Annular LP
Atrophic LP
Bullous LP and LP pemphigoides
Hypertrophic LP
Inverse LP
LP pigmentosus
Lichen planopilaris
Linear LP
Discoid lupus erythematosus/lichen planus overlap syndrome
Nail LP
Oral LP
Ulcerative LP
Vulvovaginal LP
Lichenoid drug eruption (drug-induced LP)
Pathology
Differential Diagnosis
Treatment
Systemic therapies
Phototherapy
Lichen Striatus
Introduction
History
Epidemiology
Pathogenesis
Clinical Features
Pathology
Differential Diagnosis
Treatment
Lichen Nitidus
Introduction
History
Epidemiology
Pathogenesis
Clinical Features
Pathology
Differential Diagnosis
Treatment
Erythema Dyschromicum Perstans
Introduction
History
Epidemiology
Pathogenesis
Clinical Features
Pathology
Differential Diagnosis
Treatment
Keratosis Lichenoides Chronica
Actinic Lichen Nitidus (Summertime Actinic Lichenoid Eruption)
Annular Lichenoid Dermatitis (Of Youth)
References
Chapter 12: Atopic Dermatitis
Abstract
Keywords
Introduction
History and Definitions
Epidemiology
Pathogenesis
Genetic Factors
Epidermal Barrier Dysfunction
Filaggrin and other structural proteins
Stratum corneum lipids
Proteases and protease inhibitors
Immune Dysregulation
Thymic stromal lymphopoietin (TSLP)
IL-4 and IL-13
Other cytokines
Innate lymphoid cells
The Cutaneous Microbiome
Clinical Features
Disease Course
Regional Variants of Atopic Dermatitis
Associated Features
Pruritus
Atopic stigmata
Pityriasis alba
Complications
Infections
Ocular complications
Diagnostic Criteria
Pathology
Differential Diagnosis
Treatment
General Approach
Educational interventions
Bathing
Moisturizers
Topical Anti-Inflammatory Therapy
Topical corticosteroids
Topical calcineurin inhibitors
Crisaborole
Wet wrap therapy
Phototherapy
Systemic Anti-Inflammatory Therapy
Dupilumab
Cyclosporine
Azathioprine
Methotrexate
Mycophenolate mofetil
Systemic Corticosteroids
Adjunctive Therapy
Antimicrobials and antiseptics
Antihistamines
Omalizumab
Systemic immunotherapy
Dietary supplements
Management of Coexisting Allergic Disease
Food allergies
Aeroallergen reactivity
Allergic contact dermatitis
Complementary Therapies
Prevention
Probiotics/prebiotics
Emollient therapy as prevention
References
Chapter 13: Other Eczematous Eruptions
Abstract
Keywords:
Chapter Contents
Seborrheic Dermatitis
Introduction
History
Epidemiology
Pathogenesis
Malassezia
Malassezia and seborrheic dermatitis
Active sebaceous glands and seborrheic dermatitis
Immune responses to Malassezia in seborrheic dermatitis
Clinical Features
Infantile seborrheic dermatitis
Adult seborrheic dermatitis
Pathology
Differential Diagnosis
Treatment
Infantile seborrheic dermatitis
Adult seborrheic dermatitis
Asteatotic Eczema
Introduction
History and Epidemiology
Pathogenesis
Clinical Features
Pathology
Differential Diagnosis
Treatment
Disseminated Eczema (Autosensitization)
Introduction
History and Pathogenesis
Epidemiology
Clinical Features
Pathology
Differential Diagnosis
Treatment
Nummular Dermatitis
Introduction
Epidemiology
Pathogenesis
Clinical Features
Pathology
Differential Diagnosis
Treatment
Pityriasis Alba
HTLV-Associated Infective Dermatitis
Introduction and Pathogenesis
History and Epidemiology
Clinical Features
Differential Diagnosis
Treatment
Regional Eczematous Disorders
Stasis Dermatitis
Introduction
History
Epidemiology
Pathogenesis
Clinical features
Pathology
Differential diagnosis
Treatment
Dyshidrotic Eczema
Introduction
Pathogenesis
Clinical features
Pathology
Differential diagnosis
Treatment
Infectious Eczematous Dermatitis
Juvenile Plantar Dermatosis
Introduction
History
Epidemiology
Pathogenesis
Clinical features
Pathology
Differential diagnosis
Treatment
Diaper Dermatitis
Epidemiology
Pathogenesis
Clinical features
Differential diagnosis
Treatment
References
Chapter 14: Allergic Contact Dermatitis
Abstract
Keywords:
Introduction
History of Patch Testing
Epidemiology
Pathogenesis
Clinical Features
Pathology
Differential Diagnosis
Patch Testing
Technique
Interpreting the test
Treatment and Patient Education
Allergens
Nickel
Methylisothiazolinone (MI)
Neomycin Sulfate
Fragrance Mix
Bacitracin
Myroxylon pereirae
Cobalt
Formaldehyde
Quaternium-15
p-Phenylenediamine
Thimerosal
Gold
Corticosteroids
Textile Dermatitis
Rubber Chemicals
Systemic Contact Dermatitis
Airborne Contact Dermatitis
References
Chapter 15: Irritant Contact Dermatitis
Abstract
Keywords:
Introduction
History
Epidemiology
Pathogenesis
Clinical Features
Acute Irritant Contact Dermatitis
Acute Delayed Irritant Contact Dermatitis
Irritant Reaction Irritant Contact Dermatitis
Cumulative Irritant Contact Dermatitis
Asteatotic Dermatitis
Traumatic Irritant Contact Dermatitis
Pustular and Acneiform Irritant Contact Dermatitis
Non-erythematous Irritant Contact Dermatitis
Subjective or Sensory Irritant Contact Dermatitis
Airborne Irritant Contact Dermatitis
Frictional Irritant Contact Dermatitis
Contact Urticaria
Pathology
Classification of Irritant Chemicals
Acids
Alkalis
Metal salts
Solvents
Alcohols/glycols
Detergents and cleansers
Disinfectants
Plastics
Food and plants
Water
Bodily fluids
Differential Diagnosis
Prognosis
Treatment
References
Chapter 16: Occupational Dermatoses
Abstract
Keywords:
Introduction
History
Epidemiology
The Occupational Dermatoses
Contact Dermatitis
Introduction
History
Epidemiology
Pathogenesis
Clinical features
Allergic contact dermatitis (see Ch. 14)
Irritant contact dermatitis (see Ch. 15)
Chemical burns
Fiberglass dermatitis
Phototoxic eruptions (see Ch. 87)
Mechanical
Pathology
Differential diagnosis
Treatment
Contact Urticaria
Introduction
History
Epidemiology
Pathogenesis
Clinical features
Foods
Latex
Low-molecular-weight chemicals
Protein contact dermatitis
Pathology
Differential diagnosis
Treatment
Occupational Skin Cancer
Introduction
History
Epidemiology
Pathogenesis
Clinical features and diagnosis
Pathology and treatment
Occupational Acne
Introduction
History
Epidemiology
Pathogenesis
Clinical features
Oil acne and tar acne
Acne mechanica
Acne cosmetica
Chloracne
Acne due to halogens
Pathology
Treatment
Vibration White Finger
Introduction
History
Epidemiology
Pathogenesis
Clinical features
Pathology
Differential diagnosis
Treatment
Infections
References
Chapter 17: Dermatoses Due to Plants
Abstract
Keywords:
Chapter Contents
Introduction
Botanical Aspects
Poison ivy – just as allergenic despite a name change
Binomial nomenclature
Plant identification
Patch Testing
Immunologic Contact Urticaria
Epidemiology
Pathogenesis (see Ch. 18)
Clinical Features
Differential Diagnosis and Pathology
Treatment
Toxin-Mediated (Non-Immunologic) Contact Urticaria
History
Epidemiology
Pathogenesis (see Ch. 18)
Clinical Features
Pathology (see Ch. 18)
Differential Diagnosis (see Ch. 18)
Treatment
Mechanical Irritant Dermatitis
Epidemiology
Pathogenesis
Clinical Features
Treatment
Chemical Irritant Dermatitis
History
Epidemiology
Pathogenesis, Clinical Features and Treatment (see Ch. 15)
Phytophotodermatitis
History
Epidemiology
Apiaceae
Rutaceae
Moraceae
Other families
Pathogenesis
Clinical Features
Phytophotoallergic Contact Dermatitis
Treatment
Allergic Contact Dermatitis (See Ch. 14)
Epidemiology
Anacardiaceae and related families
Toxicodendron identification
Allergenic Anacardiaceae
Cross-reactors from other families
Asteraceae and related families
Asteraceae identification
Allergenic Asteraceae
Cross-reactors from other families
Pathogenesis
Anacardiaceae allergens
Asteraceae allergens
Clinical Features
Anacardiaceae dermatitis
Asteraceae dermatitis
Photosensitivity and Asteraceae allergy
Treatment (Anacardiaceae and Asteraceae Dermatitis)
Other Plant Families Causing Allergic Contact Dermatitis
Alliaceae
Alstroemeriaceae and Liliaceae
Myrtaceae
Botanical products
Occupational Plant Dermatoses
Bakers
Florists and Horticulturalists
Food Handlers
Outdoor Workers
Dermatoses Erroneously Ascribed to Plants
Lichen Dermatitis
Chlorella Photodermatitis
Seaweed Dermatitis
Pseudo-Phytodermatitis From Plant Hitchhikers
References
Section 4: Urticarias, Erythemas and Purpuras
Chapter 18: Urticaria and Angioedema
Abstract
Keywords:
Introduction
Definition of Urticaria
Epidemiology
Pathogenesis
The Mast Cell
Distribution and diversity
Degranulating stimuli
Proinflammatory mediators
Blood Vessels
Blood
Autoantibodies
Leukocytes
Nerves
Mechanisms of Urticaria Formation
Mast cell-dependent urticaria
Mast cell-independent urticaria
C1 esterase inhibitor (C1 inh) deficiency
Clinical Features
Clinical Diversity
Classification
Acute Versus Chronic Urticaria
Spontaneous Urticaria
Associations
Inducible Urticarias (syn. Physical Urticarias)
Urticaria due to mechanical stimuli
Dermographism (literally “skin writing”) (syn. factitious urticaria)
Immediate dermographism
Rarer forms of dermographism
Delayed pressure urticaria
Vibratory angioedema
Urticaria due to temperature changes
Heat exposure
Heat contact urticaria
Cold exposure
Primary cold contact urticaria
Secondary cold contact urticaria
Reflex cold urticaria
Familial cold urticaria
Urticaria due to sweating or stress
Cholinergic urticaria
Exercise-induced anaphylaxis (EIA)
Adrenergic urticaria
Urticaria due to other exposures
Solar urticaria
Aquagenic urticaria
Contact Urticaria (see Ch. 16)
Food contact hypersensitivity syndrome
Angioedema Without Wheals
Drug reactions
Hereditary angioedema (HAE), types I and II (inherited C1 inh deficiency)
Hereditary angioedema (HAE), type III
Distinctive Syndromes With Urticarial Lesions
Hereditary periodic fever syndromes
Cryopyrin-associated periodic syndromes (CAPS)
Other syndromes
Acquired autoinflammatory syndromes
Schnitzler syndrome
Adult-onset Still disease
Episodic angioedema with eosinophilia (Gleich syndrome)
Systemic capillary leak syndrome
Urticarial Vasculitis (see Ch. 24)
Pathology
Diagnosis and Differential Diagnosis
Diagnosis
Acute urticaria
Chronic urticaria
Physical urticarias
Urticarial vasculitis
Angioedema without wheals
Treatment
Acute Urticaria, Chronic Spontaneous and Inducible Urticarias
First-line therapies
Classic antihistamines
Second-generation antihistamines
Addition of H2 antagonists to conventional H1 antihistamines
Antihistamines in pregnancy
Second-line therapies (targeted interventions)
Drug therapies
Non-drug therapies
Third-line therapies
C1 Esterase Inhibitor (C1 inh) Deficiency
Prognosis
References
Chapter 19: Figurate Erythemas
Abstract
Keywords:
Chapter Contents
Introduction
Erythema Annulare Centrifugum
Introduction
History
Epidemiology
Pathogenesis
Clinical Features
Pathology
Differential Diagnosis
Treatment
Erythema Marginatum
Introduction
History
Epidemiology
Pathogenesis
Clinical Features
Pathology
Differential Diagnosis
Treatment
Erythema Migrans
Introduction
History
Epidemiology
Pathogenesis
Clinical Features
Pathology
Differential Diagnosis
Treatment
Erythema Gyratum Repens
Introduction
History
Epidemiology
Pathogenesis
Clinical Features
Pathology
Differential Diagnosis
Treatment
References
Chapter 20: Erythema Multiforme, Stevens–Johnson Syndrome, and Toxic Epidermal Necrolysis
Abstract
Keywords:
Chapter Contents
Erythema Multiforme
Introduction
History
Epidemiology
Pathogenesis
Herpes simplex virus and Mycoplasma pneumoniae
Clinical Features
Elementary skin lesions (Fig. 20.1)
Distribution of skin lesions (topography)
Mucosal lesions
Systemic symptoms
Natural history
Pathology
Differential Diagnosis
Treatment
Stevens–Johnson Syndrome and Toxic Epidermal Necrolysis
Introduction
History
Epidemiology
Pathogenesis
Clinical Features
Pathology
Differential Diagnosis
Treatment
References
Chapter 21: Drug Reactions
Abstract
Keywords
Introduction
Epidemiology
Pathogenesis
Immunologically Mediated Drug Reactions
Genetic factors
Non-immunologic Mechanisms (see Table 21.3)
Overdose
Pharmacologic side effects
Cumulative toxicity
Delayed toxicity
Drug–drug interactions
Alterations in metabolism
Exacerbation of disease
Idiosyncratic With a Possible Immunologic Mechanism (see Table 21.3)
Diagnostic Features
Clinical Features
Urticaria, Angioedema, and Anaphylaxis
Urticaria (see Ch. 18 for details)
Angioedema (see Ch. 18 for details)
Anaphylaxis
Exanthematous Drug Eruptions
Drug Reaction With Eosinophilia and Systemic Symptoms (DRESS)
Serum Sickness-Like Eruption
Vasculitis (see Ch. 24)
Neutrophilic Drug Eruptions
Acute generalized exanthematous pustulosis
Sweet syndrome (acute febrile neutrophilic dermatosis) (see Ch. 26)
Halogenoderma
Other Neutrophilic Eruptions
Symmetrical Drug-Related Intertriginous and Flexural Exanthema (SDRIFE)
Bullous Eruptions
Fixed drug eruption
Linear IgA bullous dermatosis
Drug-induced bullous pemphigoid
Drug-induced pemphigus
Stevens–Johnson syndrome and toxic epidermal necrolysis (see Ch. 20)
Photosensitivity (see Ch. 87)
Phototoxicity
Photoallergy
Reactions to Anti-Neoplastic Agents – Chemotherapy, Targeted Therapy and Immunotherapy
Chemotherapy
Alopecia
Stomatitis
Additional reactions
Targeted therapy
Immunotherapy
Drug-Induced Adverse Reactions Involving Hair and Mucosae
Hair
Mucosal ulcerations
Other Drug-Induced Cutaneous Reactions
Acneiform eruptions (including folliculitis)
Anticoagulant-induced skin necrosis
Granulomatous reactions
Drug reactions in HIV infection
Drug-induced lupus erythematosus (LE)
Lymphomatoid drug reaction (see Ch. 121)
Pigmentary changes
Drug-induced psoriasis
Additional uncommon drug reactions
Cutaneous Side Effects of Vaccines and Injected Medications
Vaccine-induced reactions
Localized reactions to injected medications
Treatment
References
Chapter 22: Purpura
Abstract
Keywords:
Purpura
Introduction
The Time Course of Purpura
Coagulation
Overlap of Coagulation and Inflammatory Vessel Disease
Tests for Coagulation
Antiplatelet and Anticoagulant Agents
Cutaneous Surgical Procedures in Patients Receiving Antiplatelet/Anticoagulant Agents
Selected Purpura Syndromes
Pigmented Purpuric Dermatoses
Introduction
Pathogenesis
Clinical features
Pathology
Differential diagnosis
Treatment
Hypergammaglobulinemic Purpura of Waldenström
Introduction
Pathogenesis
Clinical features
Pathology
Differential diagnosis
Treatment
Gardner–Diamond Syndrome
Introduction
Clinical features
Pathology
Differential diagnosis and treatment
Mondor Syndrome of Superficial Thrombophlebitis
Introduction
Pathogenesis
Clinical features
Pathology
Differential diagnosis
Treatment
References
Chapter 23: Cutaneous Manifestations of Microvascular Occlusion Syndromes
Abstract
Keywords:
Chapter Contents
Introduction
Disorders of Platelet-Related Thrombopathy
Heparin-Induced Thrombocytopenia Syndrome
Introduction
Epidemiology
Pathogenesis
Clinical features
Pathology
Differential diagnosis
Treatment
Myeloproliferative Neoplasms
Introduction
Pathogenesis
Epidemiology
Clinical features
Pathology
Differential diagnosis
Treatment
Paroxysmal Nocturnal Hemoglobinuria
Introduction
Pathogenesis
Clinical features
Pathology
Differential diagnosis
Treatment
Primary Thrombotic Microangiopathy
Introduction
Pathogenesis
Clinical features
Pathology
Differential diagnosis
Treatment
Disorders of Cryoprecipitation or Cryoagglutination
Introduction
Pathogenesis
Epidemiology
Clinical features
Pathology
Differential diagnosis
Treatment
Disorders of Occlusion by Opportunistic Organisms Proliferating Within Vessels
Introduction/pathogenesis
Clinical features/pathology
Differential diagnosis
Treatment
Disorders of Occlusion by Emboli
Cholesterol Embolus
Introduction
Pathogenesis
Clinical features
Pathology
Differential diagnosis
Treatment
Oxalate Embolus
Introduction
Clinical features
Pathology
Differential diagnosis
Treatment
Other Embolus-Associated Syndromes
Systemic Coagulopathies With Cutaneous Manifestations
Protein C and S Disorders, Congenital and Acquired
Introduction
Pathogenesis/clinical features
Neonatal purpura fulminans
Warfarin necrosis
Warfarin-associated venous limb gangrene
Purpura fulminans with sepsis
Purpura fulminans postinfection
Antiphospholipid Antibody/Lupus Anticoagulant Syndrome
Introduction
Epidemiology
Pathogenesis
Clinical features
Pathology and laboratory
Differential diagnosis
Treatment
Disorders of Vascular Coagulopathies With Cutaneous Manifestations
Sneddon Syndrome
Introduction
Pathogenesis
Clinical features
Pathology
Differential diagnosis
Treatment
Livedoid Vasculopathy
Introduction
Pathogenesis
Clinical features
Pathology
Differential diagnosis
Treatment
Malignant Atrophic Papulosis
Introduction
Pathogenesis
Clinical features
Pathology
Differential diagnosis
Treatment
Disorders of Cell-Related Vascular Occlusion
Red Blood Cell Occlusion
Intravascular Cellular Occlusion
Disorders of Occlusion, Miscellaneous
Cutaneous Calciphylaxis
Brown Recluse Spider (Loxosceles) Bite
Hydroxyurea-Associated Vascular Occlusion
Interferon-Associated Cutaneous Necrosis
Hematoma-Associated Retiform Purpura
References
Chapter 24: Cutaneous Vasculitis
Abstract
Keywords:
Chapter Contents
Introduction
Classification
Epidemiology
Pathogenesis
General Clinical Features
Pathology
Differential Diagnosis
Cutaneous Small Vessel Vasculitis
Introduction
Epidemiology
Pathogenesis
Clinical features
Differential diagnosis
Treatment
Henoch–Schönlein Purpura (and IgA Vasculitis in Adults)
Introduction
Epidemiology
Pathogenesis
Clinical features
Pathology
Differential diagnosis
Treatment
Acute Hemorrhagic Edema of Infancy
Introduction
Epidemiology
Pathogenesis
Clinical features
Pathology
Differential diagnosis
Treatment
Urticarial Vasculitis
Introduction
Epidemiology
Pathogenesis
Clinical features
Pathology
Differential diagnosis
Treatment
Erythema Elevatum Diutinum
Introduction
Epidemiology
Pathogenesis
Clinical features
Pathology
Differential diagnosis
Treatment
Cryoglobulinemic Vasculitis (Due to Mixed Cryoglobulinemia)
Introduction
Epidemiology
Pathogenesis
Clinical features
Pathology
Differential diagnosis
Treatment
Predominantly Small and Medium-Sized Vessel Vasculitides
ANCA-Associated Vasculitides
Introduction
Epidemiology
Pathogenesis
Natural history, clinical features, and treatment
Microscopic Polyangiitis
Introduction
Epidemiology
Pathogenesis
Clinical features
Pathology
Differential diagnosis
Treatment
Granulomatosis With Polyangiitis
Introduction
Epidemiology
Pathogenesis
Clinical features
Pathology
Differential diagnosis
Treatment
Eosinophilic Granulomatosis With Polyangiitis
Introduction
Epidemiology
Pathogenesis
Clinical features
Pathology
Differential diagnosis
Treatment
Predominantly Medium-Sized Vessel Vasculitis
Polyarteritis Nodosa
Introduction
Epidemiology
Pathogenesis
Clinical features
Pathology
Differential diagnosis
Treatment
Temporal Arteritis
Diagnostic Approach to Patients With Vasculitis
History and Physical Examination
Laboratory Evaluation
Treatment
References
e-References
Chapter 25: Eosinophil-Associated Dermatoses
Abstract
Keywords:
Chapter Contents
Eosinophil Biology
Granular Contents
Tissue Effects and Innate Immunity
Eosinophil-Associated Dermatoses
Granuloma Faciale
History
Epidemiology
Pathogenesis
Clinical Features
Pathology
Differential Diagnosis
Treatment
Papuloerythroderma of Ofuji
History
Epidemiology
Pathogenesis
Clinical Features
Pathology
Differential Diagnosis
Treatment
Wells Syndrome
Introduction
History
Epidemiology
Pathogenesis
Clinical Features
Pathology
Differential Diagnosis
Treatment
Hypereosinophilic Syndromes
Introduction
History
Epidemiology
Pathogenesis
Secondary (reactive) HES
Primary (neoplastic) HES
Clinical Features
Pathology
Differential Diagnosis
Treatment
References
Chapter 26: Neutrophilic Dermatoses
Abstract
Keywords:
Neutrophil Biology
Inflammation
Sweet Syndrome
History
Epidemiology
Pathogenesis
Clinical Features
Associated Diseases
Pathology
Differential Diagnosis
Treatment
Pyoderma Gangrenosum
Introduction
History
Epidemiology
Pathogenesis
Clinical Features
Associated Diseases
Pathology
Differential Diagnosis
Treatment
Behçet Disease
Introduction
History
Epidemiology
Pathogenesis
Clinical Features and Differential Diagnosis
Mucocutaneous involvement
Systemic involvement
Pathology
Diagnosis
Treatment
Bowel-Associated Dermatosis–Arthritis Syndrome
Introduction
History
Pathogenesis
Clinical Features
Pathology
Differential Diagnosis
Treatment
Synovitis, Acne, Pustulosis, Hyperostosis and Osteitis (SAPHO) Syndrome
Introduction
History
Epidemiology
Pathogenesis
Clinical Features
Pathology
Differential Diagnosis
Treatment
Copyright notice
References
Chapter 27: Pregnancy Dermatoses
Abstract
Keywords:
Chapter Contents
Pemphigoid Gestationis
Introduction
History
Epidemiology
Pathogenesis
Clinical Features
Pathology
Differential Diagnosis
Treatment
Polymorphic Eruption of Pregnancy
Introduction
History
Epidemiology
Pathogenesis
Clinical Features
Pathology
Differential Diagnosis
Treatment
Intrahepatic Cholestasis of Pregnancy
Introduction
History
Epidemiology
Pathogenesis
Clinical Features
Pathology
Differential Diagnosis
Treatment
Atopic Eruption of Pregnancy
Introduction
History
Epidemiology
Pathogenesis
Clinical Features
Pathology
Differential Diagnosis
Treatment
Approach to the Pregnant Woman With Pruritus
Physiologic Changes During Pregnancy
Dermatoses Influenced by Pregnancy
Autoimmune Progesterone Dermatitis
References
Section 5: Vesiculobullous Diseases
Chapter 28: The Biology of the Basement Membrane
Abstract
Keywords:
Chapter Contents
Introduction
Origin of the Epidermal Basement Membrane
Basal Keratinocytes: Hemidesmosome-Anchoring Filaments and Other Integrin Complexes
Plectin
Bullous Pemphigoid Antigen 1
Bullous Pemphigoid Antigen 2
Integrins
Hemidesmosome-associated integrin α6β4
Plasma membrane-associated integrins
Tetraspan CD151
The Lamina Densa
Laminins
Type IV Collagen
Nidogen
Heparan Sulfate Proteoglycans
Anchoring Fibrils and the Sublamina Densa Region
Type VII Collagen
Microfibrils
Microthread-Like Fibers
Basement Membrane Remodeling
The Epidermal Basement Membrane in Bullous Diseases
Autoimmune Subepidermal Blistering Diseases
Inherited Subepidermal Blistering Diseases
Summary
References
Chapter 29: Pemphigus
Abstract
Keywords:
Introduction
History
Epidemiology
Fogo Selvagem
Pathogenesis
Pathogenic Autoantibodies in Pemphigus
Desmogleins as Pemphigus Antigens
Desmoglein Compensation Theory as Explanation for Localization of Blisters
Humoral and Cellular Autoimmunity in Paraneoplastic Pemphigus
Immunologic Mechanism of Pathogenic Autoantibody Production in Pemphigus
Clinical Features
Pemphigus Vulgaris
Pemphigus Vegetans
Pemphigus Foliaceus
Pemphigus Erythematosus (Senear –Usher Syndrome)
Herpetiform Pemphigus
Drug-Induced Pemphigus
Paraneoplastic Pemphigus
IgA Pemphigus
Pathology
Pemphigus Vulgaris
Pemphigus Foliaceus
Paraneoplastic Pemphigus
IgA Pemphigus
Differential Diagnosis
Differential Diagnosis of Pemphigus Vulgaris
Differential Diagnosis of Pemphigus Foliaceus
Differential Diagnosis of Paraneoplastic Pemphigus
Differential Diagnosis of IgA Pemphigus
Treatment
Pemphigus Vulgaris
Pemphigus Foliaceus
Paraneoplastic Pemphigus
IgA Pemphigus
References
Chapter 30: Pemphigoid Group
Abstract
Keywords:
Chapter Contents
Bullous Pemphigoid
Introduction
History
Epidemiology
Pathogenesis
Humoral and cellular responses
Clinical Features
Non-bullous pemphigoid
Bullous phase
Clinical variants
Associated Diseases
Drug-induced bullous pemphigoid
Diagnosis
Light microscopy
Direct immunofluorescence (DIF) microscopy
Indirect immunofluorescence (IIF) microscopy
ELISA
Other immunopathological studies
Differential Diagnosis
Prognosis
Monitoring
Treatment
Mucous Membrane (Cicatricial) Pemphigoid
Introduction
History
Epidemiology
Pathogenesis
Clinical Features
Mucous membranes
Cutaneous lesions
Diagnosis and Differential Diagnosis
Light microscopy and electron microscopy
Direct immunofluorescence (DIF) microscopy
Immunoelectron microscopy
Indirect immunofluorescence (IIF) microscopy
Immunochemical studies, including ELISA
Differential diagnosis
Prognosis
Treatment
Epidermolysis Bullosa Acquisita
Introduction
History
Epidemiology
Pathogenesis
Clinical Features
Diagnosis and Differential Diagnosis
Light microscopy and electron microscopy
Direct immunofluorescence (DIF) microscopy
Indirect immunofluorescence (IIF) microscopy
Immunoelectron microscopy
Other immunochemical studies, including ELISA
Differential diagnosis
Treatment
References
Chapter 31: Dermatitis Herpetiformis and Linear IgA Bullous Dermatosis
Abstract
Keywords:
Chapter Contents
Dermatitis Herpetiformis
Introduction
History
Epidemiology
Pathogenesis
Genetic predisposition
Gluten-sensitive enteropathy
Circulating antibodies
Granular IgA deposition
Iodide and dapsone
Associated Disorders and Malignancies
Clinical Features
Pathology
Laboratory evaluation
Differential Diagnosis
Treatment
Patient Support
Linear IgA Bullous Dermatosis
Introduction
History
Epidemiology
Pathogenesis
Clinical Features
Pathology
Differential Diagnosis
Treatment
References
Chapter 32: Epidermolysis Bullosa
Abstract
Keywords:
Introduction
History
Epidemiology
Pathogenesis
EB Simplex
Junctional EB
Dystrophic EB
Clinical Features
Cutaneous Findings
Extracutaneous Findings
Cutaneous Malignancies
Approach to Diagnosis
Differential Diagnosis
Treatment
Kindler Syndrome
Introduction
History
Pathogenesis
Clinical Features
Pathology
Differential Diagnosis
Treatment
References
Chapter 33: Other Vesiculobullous Diseases
Abstract
Keywords:
Chapter Contents
Bullosis Diabeticorum
History
Epidemiology
Pathogenesis
Clinical Features
Pathology
Differential Diagnosis
Treatment
Coma Blisters
Introduction
History
Epidemiology
Pathogenesis
Clinical Features
Pathology
Differential Diagnosis
Treatment
Friction Blisters
Epidemiology
Pathogenesis
Clinical Features
Pathology
Differential Diagnosis
Treatment
Bullous Small Vessel Vasculitis
Bullous Drug Eruptions
Bullous Insect Bite Reactions
Introduction
Epidemiology
Pathogenesis
Clinical Features
Pathology
Differential Diagnosis
Treatment
Delayed Postburn/Postgraft Blisters
Introduction
History
Epidemiology
Pathogenesis
Clinical Features
Pathology
Differential Diagnosis
Treatment
Edema Blisters
Epidemiology
Pathogenesis
Clinical Features
Pathology
Differential Diagnosis
Treatment
Additional Vesiculobullous Disorders
References
Chapter 34: Vesiculopustular and Erosive Disorders in Newborns and Infants
Abstract
Keywords:
Common Causes
Erythema Toxicum Neonatorum
Transient Neonatal Pustular Melanosis
Sterile Transient Neonatal Pustulosis
Miliaria
Neonatal Cephalic Pustulosis
Cutaneous Candidiasis
Sucking Blisters
Exogenous Causes of Erosions
Uncommon and Rare Causes
Acropustulosis of Infancy
Eosinophilic Pustular Folliculitis of Infancy
Congenital and Neonatal Langerhans Cell Histiocytosis
Incontinentia Pigmenti
Autosomal Dominant Hyperimmunoglobulin E (Hyper-IgE) Syndrome
Very Rare Disorders
Neonatal Behçet Disease
Vesiculopustular Eruption in Transient Myeloproliferative Disorder of Down Syndrome
Congenital Erosive and Vesicular Dermatosis
Pyoderma Gangrenosum
Restrictive Dermopathy
Noma Neonatorum
Perinatal Gangrene of the Buttock
References
Section 6: Adnexal Diseases
Chapter 35: Structure and Function of Eccrine, Apocrine and Sebaceous Glands
Abstract
Keywords:
Chapter Contents
Eccrine, Apocrine, and Apoeccrine Sweat Glands
Introduction
Structure, Function and Pathophysiology
Eccrine Sweat Glands
Structure
Development
Function
Pathophysiology
Hyper- and hypohidrosis
Drug-related eccrine disorders
Disorders of sweat retention
Apocrine Sweat Glands
Structure
Development
Function
Pathophysiology
Apoeccrine Sweat Glands
Sebaceous Glands
Introduction
Structure, Function and Pathophysiology
Structure
Development
Function
Pathophysiology
References
Chapter 36: Acne Vulgaris
Abstract
Keywords:
Introduction
History
Epidemiology, Including Genetic and Dietary Factors
Genetic Factors
Dietary Factors
Pathogenesis
Follicular Hyperkeratinization
Hormonal Influences on Sebum Production and Composition
Inflammation in Acne
Propionibacterium acnes and the Innate Immune System
Clinical Features
Acne Variants
Post-adolescent acne in women
Acne fulminans
Acne conglobata and associated conditions
Solid facial edema
Neonatal acne (neonatal cephalic pustulosis)
Infantile acne
Mid-childhood acne
Preadolescent acne
Acne excoriée
Acne associated with endocrinologic abnormalities
Acne associated with genetic syndromes
Acneiform Eruptions
Drug-induced acne
Occupational acne, acne cosmetica, and pomade acne
Chloracne
Acne mechanica
Tropical acne
Radiation acne
“Pseudoacne” of the nasal crease
Idiopathic facial aseptic granuloma
Childhood flexural comedones
Pathology
Differential Diagnosis
Treatment
Topical Treatments
Topical retinoids
Benzoyl peroxide and other topical antibacterial agents
Other topical medications
Oral Treatments
Antibiotics
Hormonal therapy
Isotretinoin
Surgical Treatment
References
Chapter 37: Rosacea and Related Disorders
Abstract
Keywords:
Introduction
History
Epidemiology
Pathogenesis
Clinical Features
Pathology
Treatment
Rosacea-Like Disorders
References
Chapter 38: Folliculitis and Other Follicular Disorders
Abstract
Keywords:
Chapter Contents
Introduction
Superficial Folliculitis
Introduction
Clinical features
Pathology
Differential diagnosis
Treatment
Eosinophilic Folliculitis
Eosinophilic pustular folliculitis
Introduction
History
Epidemiology
Pathogenesis
Clinical features
Pathology
Differential diagnosis
Treatment
Immunosuppression-associated eosinophilic pustular folliculitis
Introduction and history
Epidemiology
Pathogenesis
Clinical features
Pathology
Differential diagnosis
Treatment
Eosinophilic pustular folliculitis of infancy
Introduction
History
Epidemiology
Pathogenesis
Clinical features
Pathology
Differential diagnosis
Treatment
Disseminate and Recurrent Infundibulofolliculitis
Disorders of Follicular Keratinization
Erythromelanosis Follicularis Faciei
Introduction
Epidemiology
Pathogenesis
Clinical features
Pathology
Differential diagnosis
Treatment
Keratosis Pilaris Atrophicans
Lichen Spinulosus
Introduction, history and epidemiology
Pathogenesis
Clinical features
Pathology
Differential diagnosis
Treatment
Phrynoderma
Deep Folliculitis
Pseudofolliculitis Barbae
Introduction
Epidemiology
Pathogenesis
Clinical features
Pathology
Differential diagnosis
Treatment
Acne Keloidalis
Introduction
History
Epidemiology
Pathogenesis
Clinical features
Pathology
Differential diagnosis
Treatment
Follicular Occlusion Tetrad
Hidradenitis Suppurativa
Introduction
History
Epidemiology
Pathogenesis
Clinical features
Pathology
Differential diagnosis
Treatment
Trichostasis Spinulosa
Viral-Associated Trichodysplasia
Acknowledgment
References
Chapter 39: Diseases of the Eccrine and Apocrine Sweat Glands
Abstract
Keywords:
Chapter Contents
Sweat Glands
Eccrine Sweat Glands
Apocrine Sweat Glands
Hyperhidrosis
Primary Hyperhidrosis
Secondary Hyperhidrosis
Disorders associated with cortical (emotional) hyperhidrosis
Hypothalamic (thermoregulatory) hyperhidrosis
Medullary (gustatory) hyperhidrosis
Physiologic medullary hyperhidrosis
Pathologic medullary hyperhidrosis
Spinal (cord transection) sweating
Autonomic dysreflexia
Compensatory hyperhidrosis
Non-neural hyperhidrosis
Diagnosis of Hyperhidrosis
Treatment of Hyperhidrosis
Hypohidrosis and Anhidrosis
Central and Neuropathic Hypohidrosis
Peripheral Anhidrosis
Diagnosis of Anhidrosis
Treatment of Anhidrosis
Abnormalities and Alterations of Eccrine and Apocrine Sweat Composition
Diagnostic Microscopic Changes in Eccrine Sweat Glands
Influence of Sweat on Skin Diseases
Additional Disorders of the Eccrine Sweat Gland
Miliaria
Epidemiology and pathogenesis
Clinical features
Pathology
Differential diagnosis
Treatment
Multiple Sweat Gland Abscesses
Neutrophilic Eccrine Hidradenitis
Epidemiology and pathogenesis
Clinical features
Pathology
Differential diagnosis
Treatment
Idiopathic Palmoplantar Hidradenitis
Granulosis Rubra Nasi
Keratolysis Exfoliativa
Grover Disease
Disorders of the Apocrine Sweat Gland
Fox–Fordyce Disease
Epidemiology and pathogenesis
Clinical
Pathology
Treatment
References
Section 7: Rheumatologic Dermatology
Chapter 40: Autoantibodies Encountered in Patients with Autoimmune Connective Tissue Diseases
Abstract
Keywords
Chapter Contents
Introduction
Chapter Organization
Historical Perspective
FANA: the Classic ANA Assay
Importance of Technical Aspects of the ANA Assay
“Normal” Versus “Abnormal” ANA Values
Clinical Significance of ANA
Immunofluorescence Patterns
Concept of Clinical Utility as Applied to aAb Testing
Clinical Value of aAb in Diagnosis Versus Disease Activity Monitoring
“Sontheimer’s Corollary” to Greenwald’s Law of Lupus
Phototherapy and the ANA Assay
How Does One Evaluate a Positive ANA Result in a Patient Suspected of Having SLE?
Autoantibodies Encountered in Lupus Erythematosus
Drug-Induced ANA/SLE
Induction of ANA and Anti-dsDNA Antibodies by Tumor Necrosis Factor Inhibitors
Autoantibodies Encountered in Idiopathic Inflammatory Dermatomyopathies
TIF1-γ (p155) and MDA5/CADM-140/RIG-I-like receptor IFIH1
Jo-1 and Mi-2
Autoantibodies Encountered in Systemic Sclerosis (Scleroderma) and Morphea (Localized Scleroderma)
Autoantibodies Encountered in Other Rheumatic Disorders That Can Affect the Skin
References
Chapter 41: Lupus Erythematosus
Abstract
Keywords:
Introduction
History
Epidemiology
Pathogenesis
Clinical Features
Cutaneous Lupus – Three Major Forms
Classification
Discoid lupus erythematosus
Subacute cutaneous lupus erythematosus
Acute cutaneous lupus erythematosus (ACLE)
Cutaneous Lupus – Additional Variants (See Fig. 41.2)
Lupus erythematosus tumidus
Lupus panniculitis
Chilblain lupus
Discoid lupus erythematosus/lichen planus overlap syndrome
Neonatal lupus erythematosus (NLE)
Bullous lesions
Systemic Lupus Erythematosus
Nonspecific Cutaneous Lesions
Pathology
Histopathology
Antibody Deposits in Lesional Skin
Antibody Deposits Within Normal-Appearing Skin
Differential Diagnosis
Treatment
Topical Therapy
Systemic Therapy
Adjunctive Therapy
References
Chapter 42: Dermatomyositis
Abstract
Keywords:
Introduction
History
Epidemiology
Pathogenesis
Clinical Features
Cutaneous Disease
Systemic Disease
Malignancy
Pathology
Differential Diagnosis and Evaluation
Treatment
References
Chapter 43: Systemic Sclerosis (Scleroderma) and Related Disorders
Abstract
Keywords:
Chapter Contents
Systemic Sclerosis
Introduction
History
Epidemiology
Pathogenesis
Vascular dysregulation
Immune dysregulation
Extracellular matrix dysregulation
Clinical Features
Classification and diagnostic criteria
Cutaneous features
Extracutaneous features
Autoantibodies
Pathology
Differential Diagnosis
Treatment
Raynaud phenomenon
Cutaneous ulcers
Cutaneous sclerosis
Other cutaneous complications
Internal organ involvement
Eosinophilic Fasciitis
History
Clinical Features
Pathology
Treatment
Nephrogenic Systemic Fibrosis
History
Epidemiology and Pathogenesis
Clinical Features
Pathology
Treatment
Stiff Skin Syndrome
History
Epidemiology
Pathogenesis
Clinical Features
Pathology
Treatment
Sclerodermoid Syndromes Induced by Exogenous Substances
Toxic Oil Syndrome
Eosinophilia–Myalgia Syndrome
Sclerodermoid Syndromes Induced by Drugs
Sclerodermoid Syndromes Induced by Chemicals
Silicosis
References
Chapter 44: Morphea and Lichen Sclerosus
Abstract
Keywords:
Morphea
Introduction
History
Epidemiology
Pathogenesis
Vascular Changes
Control of Fibroblast Function by T-Cell-Derived Cytokines
Animal Model and Genetics
Triggering Events
Clinical Features
Plaque-Type Morphea
Variants
Linear Morphea and Parry–Romberg Syndrome
Generalized Morphea
Morphea in Childhood
Laboratory Findings
Pathology
Morpheaform (and Sclerodermoid) Inflammatory Syndromes
Differential Diagnosis
Lichen Sclerosus
Introduction
History
Epidemiology
Pathogenesis
Clinical Features
Pathology
Differential Diagnosis
Treatment of Morphea and Lichen Sclerosus
Phototherapies
Topical Therapies
Corticosteroids
Calcineurin inhibitors and imiquimod
Vitamin derivatives
Hormones
Systemic Treatments
Immunosuppression
Penicillin and its derivatives
Vitamin derivatives
Cytokines, TNF-α inhibitors, multi-kinase inhibitors
Surgery
Physical Therapy
References
Chapter 45: Other Rheumatologic Disorders and Autoinflammatory Diseases
Abstract
Keywords:
Chapter Contents
Systemic-Onset Juvenile Idiopathic Arthritis (Still Disease)
Introduction
History
Epidemiology
Pathogenesis
Clinical Features
Pathology
Differential Diagnosis
Treatment
Adult-Onset Still Disease
Introduction
Epidemiology
Pathogenesis
Clinical Features
Pathology
Differential Diagnosis
Treatment
Relapsing Polychondritis
Introduction
History
Epidemiology
Pathogenesis
Clinical Features
Pathology
Differential Diagnosis
Treatment
Sjögren Syndrome
Introduction
History
Epidemiology
Pathogenesis
Clinical Features
Laboratory Findings
Pathology
Differential Diagnosis
Treatment
Mixed Connective Tissue Disease
Introduction
History
Epidemiology
Pathogenesis
Clinical Features
Pathology
Differential Diagnosis
Treatment
Extra-Articular Manifestations of Rheumatoid Arthritis
Introduction
Epidemiology
Pathogenesis
Clinical Features
Rheumatoid nodules
Rheumatoid vasculitis
Bywaters lesions
Felty syndrome
Neutrophilic dermatoses
Other
Pathology
Differential Diagnosis
Treatment
Autoinflammatory Diseases
Acknowledgment
References
Section 8: Metabolic and Systemic Diseases
Chapter 46: Mucinoses
Abstract
Keywords:
Introduction
Classification
Primary Degenerative–Inflammatory Mucinoses
Dermal Mucinoses
Scleromyxedema
Introduction and definition
History
Epidemiology and pathogenesis
Clinical features
Pathology
Differential diagnosis
Treatment
Lichen myxedematosus (localized variants)
Introduction
Epidemiology
Clinical features
Pathology
Differential diagnosis
Treatment
Self-healing cutaneous mucinosis
Scleredema
Introduction
History
Epidemiology and pathogenesis
Clinical features
Pathology
Differential diagnosis
Treatment
Mucinoses associated with altered thyroid function
Localized (pretibial) myxedema
Definition
Epidemiology and pathogenesis
Clinical features
Pathology
Differential diagnosis
Treatment
Generalized myxedema
Definition
Pathogenesis
Clinical features
Pathology
Diagnosis and differential diagnosis
Treatment
Reticular erythematous mucinosis
Introduction and definition
History
Epidemiology and pathogenesis
Clinical features
Pathology
Differential diagnosis
Treatment
Papulonodular mucinosis associated with autoimmune connective tissue diseases
Treatment
Cutaneous focal mucinosis
Miscellaneous mucinoses
Primary Follicular Mucinoses
Follicular mucinosis
History, epidemiology and pathogenesis
Clinical features
Pathology
Differential diagnosis
Treatment
Urticaria-like follicular mucinosis
Primary Hamartomatous–Neoplastic Mucinoses
Mucinous Nevus
Superficial (Angio)Myxoma
References
Chapter 47: Amyloidosis
Abstract
Keywords:
Chapter Contents
Introduction
History
Epidemiology
Classification
Pathogenesis
Amyloid properties
Primary (Localized) Cutaneous Amyloidosis
Clinical features
Pathology
Differential diagnosis
Treatment
Secondary Cutaneous Amyloidosis
Systemic Amyloidosis
Primary Systemic Amyloidosis
Clinical features
Pathology
Differential diagnosis
Treatment
Secondary Systemic Amyloidosis
Hemodialysis-Associated Amyloidosis
Inherited Amyloidoses
Familial amyloidosis, Finnish type
Muckle–Wells syndrome
Familial Mediterranean fever
Sipple syndrome or multiple endocrine neoplasia (MEN) type 2A
Hypotrichosis simplex of the scalp
X-Linked Reticulate Pigmentary Disorder (Partington Amyloidosis)
Appendix
References
Chapter 48: Deposition Diseases
Abstract
Keywords:
Chapter Contents
Introduction
Gout
Introduction
Epidemiology
Pathogenesis
Clinical Features
Acute gouty arthritis
Chronic tophaceous gout
Pathology
Differential Diagnosis
Treatment
Pseudogout
Lipoid Proteinosis
History
Epidemiology
Pathogenesis
Clinical Features
Pathology
Differential Diagnosis
Treatment
Colloid Milium
Introduction and Epidemiology
Pathogenesis
Clinical Features
Pathology
Differential Diagnosis
Treatment
Mucopolysaccharidoses
Clinical Features and Pathology
Treatment
References
Chapter 49: Porphyria
Abstract
Keywords:
Introduction
History
Epidemiology
Pathogenesis
Cutaneous Findings
Acute Porphyric Attack
Clinical and Laboratory Investigation
The Non-Acute Porphyrias
Porphyria Cutanea Tarda (PCT)
Erythropoietic Protoporphyria (EPP)
X-linked Dominant Protoporphyria (XLDPP)
Congenital Erythropoietic Porphyria (CEP)
Hepatoerythropoietic Porphyria (HEP)
Pseudoporphyria
Differential Diagnosis
Treatment
The Acute Porphyrias
Acute Intermittent Porphyria (AIP)
Variegate Porphyria (VP)
Hereditary Coproporphyria (HCP)
δ-Aminolevulinic Acid Dehydratase (ALA-D) Deficiency Porphyria
Differential Diagnosis
Treatment
Cutaneous symptoms
Acute porphyric attack
Appendix
References
Chapter 50: Calcifying and Ossifying Disorders of the Skin
Abstract
Keywords:
Chapter Contents
Introduction
Cutaneous Calcification
Dystrophic Calcification
Autoimmune Connective Tissue Disease
Treatment of dystrophic calcification
Panniculitis
Genetic Disorders
Infections
Neoplasms
Other
Metastatic Calcification
Renal Disease
Milk–Alkali Syndrome
Hypervitaminosis D
Mixed Calcification
Calciphylaxis
Treatment of calciphylaxis
Idiopathic Calcification
Idiopathic Calcified Nodules of the Scrotum
Subepidermal Calcified Nodule
Tumoral Calcinosis
Milia-like Calcinosis
Iatrogenic Calcification
Cutaneous Ossification (Osteoma Cutis)
“Secondary” Cutaneous Ossification
Laboratory Evaluation of Patients With Cutaneous Calcification and Ossification
References
Chapter 51: Nutritional Diseases
Abstract
Keywords:
Introduction
Epidemiology and Pathogenesis
Clinical Features
Protein–Energy Malnutrition
Essential Fatty Acid Deficiency
Vitamins and Trace Elements
Vitamins
Vitamin excess
Vitamin D
Trace elements
Zinc
Copper
Selenium
Anorexia Nervosa and Bulimia (Nervosa)
Obesity
Bariatric Surgery and Gastrointestinal Malabsorption
Pathology
Differential Diagnosis
Treatment
References
Chapter 52: Graft-versus-Host Disease
Abstract
Keywords:
Introduction
History
Epidemiology
Pathogenesis
Clinical Features
Acute GVHD
Chronic GVHD
Pathology
Differential Diagnosis
Treatment
Acute GVHD
Chronic GVHD
References
Chapter 53: Dermatologic Manifestations in Patients with Systemic Disease
Abstract
Keywords:
Chapter Contents
Cutaneous Rheumatology
Cutaneous Hematology and Oncology
Cutaneous Endocrinology and Metabolic Disease
Cutaneous Gastroenterology
Other Systemic Diseases With Cutaneous Manifestations
References
Section 9: Genodermatoses
Chapter 54: Basic Principles of Genetics
Abstract
Keywords:
Introduction
Genetic Diseases
Mendelian Patterns of Inheritance
Autosomal Dominant Inheritance
Autosomal Recessive Inheritance
X-Linked Recessive Inheritance
X-Linked Dominant Inheritance
Exceptions to Basic Mendelian Patterns of Heritance
Epigenetics and Imprinting
Chromosomal Disorders
Complex Genetic Traits
Identification of Disease Genes
Linkage Analysis and Related Approaches
Refinement of the Linkage Interval
Positional Candidate Approach
Identification and Validation of Mutations
Massively parallel (Next-Generation) Sequencing
Genome-Wide Association Studies (GWAS)
Functional Genomics
References
Chapter 55: Genetic Basis of Cutaneous Diseases
Abstract
Keywords
Introduction
Mckusick’s Mendelian Inheritance in MAN
Genotype–Phenotype Correlations
Molecular Classification of Hereditary Skin Disorders
Keratin Defects
Defects in Intercellular Junctions
Desmosomal defects
Connexin defects
Defects in Keratinocyte–Extracellular Matrix Adhesion
Transmembrane Transporter Defects
Calcium pump defects
ATP-binding cassette transporter defects
Nuclear Envelope Defects
Defects in Pyrin/NOD Family Members and Related Proteins
Defects in DNA Repair Genes, Tumor Suppressor Genes and Oncogenes
Defective DNA repair and protection of genomic integrity
Defective tumor suppressor genes
Activated oncogenes
Defects in WNT/β-Catenin Signaling
Contiguous Gene Syndromes
Cutaneous Mosaicism
Revertant Mosaicism
Chromosomal Disorders
Insight Into Acquired Skin Disorders Provided by the Study of Genodermatoses
Prenatal and Preimplantation Genetic Diagnosis
Treatment for Hereditary Skin Disorders
Gene Therapy
Cell Therapy
Therapy Targeting Affected Molecular Pathways
References
Chapter 56: Biology of Keratinocytes
Abstract
Keywords:
Chapter Contents
Introduction
The Epidermis: Structure and Function
Keratin Intermediate Filaments
Keratins and Signaling
Hair Keratins
Epidermal Differentiation
Regulatory Pathways Involved in Epidermal Development and Differentiation
Genes required for establishing and maintaining basal keratinocytes
Genes required for terminal differentiation in mature epidermis
Ca2+ in epidermal differentiation
Genes required for terminal differentiation in embryonic epidermis
Keratinocyte Adhesion
Desmosomes
What happens when desmosomes do not function properly?
Other Types of Cell Junctions
Adherens junctions
Tight junctions
Keratinocyte–Matrix Interactions
Related Diseases
Keratin Disorders
Epidermolysis bullosa simplex
Epidermolytic ichthyosis and palmoplantar keratoderma
White sponge nevus of Cannon
Gastrointestinal disorders
Filaggrin Deficiency Disorders
Mouse Models for Structural and Desmosomal Proteins
Conclusion
References
Chapter 57: Ichthyoses, Erythrokeratodermas, and Related Disorders
Abstract
Keywords
Chapter Contents
Introduction
Ichthyoses
Ichthyosis Vulgaris
History
Epidemiology
Pathogenesis
Clinical Features
Pathology
Differential Diagnosis
Treatment
Steroid Sulfatase Deficiency
History
Epidemiology
Pathogenesis
Clinical Features
Pathology
Other diagnostic tests
Differential Diagnosis
Treatment
Epidermolytic Ichthyosis
History
Epidemiology
Pathogenesis
Clinical Features
Epidermolytic epidermal nevi (mosaic epidermolytic ichthyosis)
Pathology
Other diagnostic tests
Differential Diagnosis
Treatment
Superficial Epidermolytic Ichthyosis
History
Pathogenesis
Clinical Features
Pathology
Differential Diagnosis
Treatment
Ichthyosis With Confetti
Ichthyosis Hystrix Curth–Macklin
History
Pathogenesis
Clinical Features
Pathology
Differential Diagnosis
Treatment
Ichthyosis Hystrix
Collodion Baby
Epidemiology
Pathogenesis
Clinical Features
Pathology
Differential Diagnosis
Treatment
Lamellar Ichthyosis
History
Epidemiology
Pathogenesis
Clinical Features
Pathology
Other diagnostic tests
Differential Diagnosis
Treatment
Congenital Ichthyosiform Erythroderma
Epidemiology
Pathogenesis
Clinical Features
Pathology
Other diagnostic tests
Differential Diagnosis
Treatment
Harlequin Ichthyosis
History
Epidemiology
Pathogenesis
Clinical Features
Pathology
Other diagnostic tests
Differential Diagnosis
Treatment
Netherton Syndrome
History
Epidemiology
Pathogenesis
Clinical Features
Pathology
Other diagnostic tests
Differential Diagnosis
Treatment
Sjögren–Larsson Syndrome
History
Epidemiology
Pathogenesis
Clinical Features
Pathology
Other diagnostic tests
Differential Diagnosis
Treatment
Neutral Lipid Storage Disease With Ichthyosis
History
Epidemiology
Pathogenesis
Clinical Features
Pathology
Differential Diagnosis
Treatment
Trichothiodystrophy With Ichthyosis
History
Epidemiology
Pathogenesis
Clinical Features
Pathology
Other diagnostic tests
Differential Diagnosis
Treatment
Other Ichthyoses and Related Disorders
Erythrokeratodermas
Erythrokeratodermia Variabilis
History
Epidemiology
Pathogenesis
Clinical Features
Pathology
Other diagnostic tests
Differential Diagnosis
Treatment
Progressive Symmetric Erythrokeratoderma (PSEK)
History
Epidemiology
Pathogenesis
Clinical Features
Pathology
Differential Diagnosis
Treatment
Keratitis–Ichthyosis–Deafness Syndrome
History
Epidemiology
Pathogenesis
Clinical Features
Pathology
Differential Diagnosis
Treatment
X-Linked Dominant Ichthyosiform Disorders
CHILD Syndrome
History
Epidemiology
Pathogenesis
Clinical Features
Pathology
Other diagnostic tests
Differential Diagnosis
Treatment
Conradi–Hünermann–Happle Syndrome
History
Epidemiology
Pathogenesis
Clinical Features
Pathology
Other diagnostic tests
Differential Diagnosis
Treatment
References
Chapter 58: Palmoplantar Keratodermas
Abstract
Keywords:
Introduction
Hereditary Keratodermas
Diffuse Palmoplantar Keratoderma Without Associated Features (Isolated, Non-Syndromic)
Diffuse Epidermolytic Palmoplantar Keratoderma (EPPK)
History
Epidemiology
Pathogenesis
Clinical features
Pathology
Differential diagnosis
Management
Diffuse Non-epidermolytic Palmoplantar Keratoderma (NEPPK)
Epidemiology and pathogenesis
Clinical features
Differential diagnosis
Pathology
Management
Diffuse Palmoplantar Keratodermas With Ichthyosis
Loricrin Keratoderma
Keratosis Linearis–Ichthyosis Congenita–Sclerosing Keratoderma (KLICK)
Diffuse Palmoplantar Keratodermas With Associated Features/Syndromic
Vohwinkel Syndrome
Mitochondrial Palmoplantar Keratoderma With Hearing Impairment
Huriez Syndrome
Palmoplantar Keratoderma With Sex Reversal and Squamous Cell Carcinoma
Clouston Syndrome
Odonto-onycho-dermal Dysplasia
Olmsted Syndrome
Papillon–Lefèvre and Haim–Munk Syndromes
Naxos Disease
Focal Palmoplantar Keratoderma Without Associated Features (Isolated, Non-Syndromic)
Striate/Focal Palmoplantar Keratoderma
Focal Palmoplantar Keratoderma With Associated Features/Syndromic
Pachyonychia Congenita
History, epidemiology, and pathogenesis
Clinical features
Pathology
Differential diagnosis
Treatment
Richner–Hanhart Syndrome
Howel–Evans Syndrome
Carvajal Syndrome
Punctate Palmoplantar Keratoderma Without Associated Features (Isolated, Non-Syndromic)
Punctate Palmoplantar Keratoderma, Buschke–Fischer–Brauer type
Spiny Keratoderma
Marginal Papular Keratoderma: Acrokeratoelastoidosis and Focal Acral Hyperkeratosis
Punctate Palmoplantar Keratoderma With Associated Features/Syndromic
Cole Disease
Acquired Keratodermas and Related Conditions
Keratoderma Climactericum
Keratoderma and Cancer
Other Etiologies of Acquired Keratoderma
Aquagenic Palmoplantar Keratoderma
Circumscribed Palmar or Plantar Hypokeratosis
References
Chapter 59: Darier Disease and Hailey–Hailey Disease
Abstract
Keywords:
Chapter Contents
Darier Disease
Introduction
History
Epidemiology
Pathogenesis
Clinical Features
Onset and clinical pattern
Symptoms
Modifying factors
Course of the disease
Infectious complications
Salivary glands
Neuropsychiatric disorders
Others
Clinical subtypes of Darier disease (Table 59.1)
Acral hemorrhagic type
Segmental types 1 and 2
Pathology
Differential Diagnosis
Acrokeratosis verruciformis of Hopf
Others
Treatment
General measures
Topical therapy
Systemic therapy
Surgical therapy
Hailey–Hailey Disease
Introduction
History
Epidemiology
Pathogenesis
Clinical Features
Onset and clinical pattern
Symptoms
Modifying factors
Course of the disease
Complications
Infections
Malignant transformation
Clinical subtypes of Hailey–Hailey disease
Segmental type 1
Segmental type 2
Pathology
Differential Diagnosis
Treatment
General measures
Topical and intralesional therapy
Surgical therapy
Systemic therapy
Copyright notice
References
Chapter 60: Primary Immunodeficiencies
Abstract
Keywords
Chapter Contents
Introduction
Ataxia–Telangiectasia
Introduction
Epidemiology
Pathogenesis
Clinical Features
Laboratory Findings
Differential Diagnosis
Treatment
Chronic Mucocutaneous Candidiasis
Introduction
Epidemiology
Pathogenesis
Clinical Features
Laboratory Findings
Differential Diagnosis
Treatment
Cartilage–Hair Hypoplasia Syndrome
Chédiak–Higashi Syndrome
Epidemiology
Pathogenesis
Clinical Features
Pathology
Differential Diagnosis
Treatment
Complement Disorders
Introduction
Epidemiology
Pathogenesis
Clinical Features
Pathology
Differential Diagnosis
Treatment
Chronic Granulomatous Disease
Introduction
Epidemiology
Pathogenesis
Clinical Features
Pathology
Differential Diagnosis
Treatment
Hyperimmunoglobulin E Syndromes
Introduction
Epidemiology
Pathogenesis
Clinical Features
Laboratory Findings and Pathology
Differential Diagnosis
Treatment
Immunoglobulin Deficiencies
IPEX Syndrome
Leukocyte Adhesion Deficiency
Introduction
Pathogenesis
Clinical Features
Pathology
Differential Diagnosis
Treatment
Severe Combined Immunodeficiency and Omenn Syndrome
Introduction
Epidemiology
Pathogenesis
Clinical Features
Laboratory Findings and Pathology
Differential Diagnosis
Treatment
Wiskott–Aldrich Syndrome
Introduction
Epidemiology
Pathogenesis
Clinical Features
Laboratory Findings and Pathology
Differential Diagnosis
Treatment
References
Chapter 61: Neurofibromatosis and Tuberous Sclerosis Complex
Abstract
Keywords:
Chapter Contents
Introduction
Neurofibromatosis Type 1
History
Epidemiology
Pathogenesis
Clinical Features
Oculocutaneous manifestations
Neurologic manifestations
Skeletal manifestations
Cardiovascular manifestations
Timing of onset of clinical manifestations
Pathology
Differential Diagnosis
Management
Tuberous Sclerosis Complex
Introduction
History
Epidemiology
Pathogenesis
Clinical Features
Oculocutaneous manifestations
Neurologic manifestations
Cardiovascular manifestations
Renal manifestations
Other manifestations
Pathology
Differential Diagnosis
Management
References
Chapter 62: Mosaicism and Linear Lesions
Abstract
Keywords:
Chapter Contents
Introduction and History
Patterns and Pathogenesis of Cutaneous Mosaicism
Mosaicism in X-Linked Disorders
Incontinentia Pigmenti
Introduction
History
Genetics
Pathogenesis
Clinical features
Pathology
Differential diagnosis
Treatment
Hypohidrotic Ectodermal Dysplasia With Immune Deficiency
Goltz Syndrome (Focal Dermal Hypoplasia)
Introduction
Genetics
Pathogenesis
Clinical features
Pathology
Differential diagnosis
Treatment
Conradi–Hünermann–Happle Syndrome (X-Linked Dominant Chondrodysplasia Punctata)
CHILD Syndrome (Congenital Hemidysplasia With Ichthyosiform Erythroderma [or Nevus] and Limb Defects)
MIDAS Syndrome
Oral–Facial–Digital Syndrome Type I
X-Linked Hypohidrotic Ectodermal Dysplasia (Female Patients)
Menkes Disease (Female Carriers)
X-Linked Reticulate Pigmentary Disorder
Epidermal Nevi and Related Syndromes
Verrucous Epidermal and Sebaceous Nevi
Epidermal Nevus Syndromes
Introduction
History and terminology
Genetics and pathogenesis
Clinical features
Pathology
Management
Proteus Syndrome
Introduction
History
Genetics
Pathogenesis
Clinical features
Pathology
Differential diagnosis
Treatment
Type 2 Mosaic PTEN Hamartoma Tumor Syndrome
ILVEN (Inflammatory Linear Verrucous Epidermal Nevus)
Mosaicism in Other Autosomal Dominant Disorders
Linear Darier Disease (Acantholytic Dyskeratotic Epidermal Nevus)
Linear Hailey–Hailey Disease (Relapsing Linear Acantholytic Dermatosis)
Linear Porokeratosis
Porokeratotic Adnexal Ostial Nevus (PAON)
Linear Distribution of Basal Cell Carcinomas and Basal Cell Nevi/Basaloid Follicular Hamartomas
Segmental Neurofibromatosis Type 1 and Legius Syndrome
Linear or Segmental Angiofibromas and Mosaicism in Tuberous Sclerosis Complex
Linear or Segmental Benign Tumors
Encephalocraniocutaneous Lipomatosis (Haberland Syndrome)
Vascular Malformations
Venous and Glomuvenous Malformations
Capillary Malformations (Port-Wine Stains)
Pigmented Lesions With a Mosaic Distribution Pattern
Speckled Lentiginous Nevi (SLN), Segmental Agminated Melanocytic Nevi, and Large/Giant Congenital Melanocytic Nevi
McCune–Albright Syndrome
Linear Inflammatory Disorders
Linear Psoriasis
Linear Lichen Planus
Lichen Striatus
“Blaschkitis”
Segmental Vitiligo
Other Linear Inflammatory Disorders
Pigmentary Mosaicism
Linear and Block-Like Hypo- and Hyperpigmentation
Introduction
History
Epidemiology
Genetics
Pathogenesis
Clinical features
Pathology
Differential diagnosis
Treatment
Nevus Depigmentosus
Chimerism
Block-Like Hyper- and Hypopigmentation Due to Chimerism
References
Chapter 63: Other Genodermatoses
Abstract
Keywords:
Chapter Contents
Introduction
Disorders Featuring Tumorigenesis
Multiple Endocrine Neoplasia
Cowden Syndrome
Introduction
History
Epidemiology
Pathogenesis
Clinical Features
Mucocutaneous manifestations
Extracutaneous manifestations
Pathology
Differential Diagnosis
Treatment
Gardner Syndrome
Introduction
History
Epidemiology
Pathogenesis
Clinical Features
Cutaneous and soft tissue manifestations
Other extraintestinal manifestations
Gastrointestinal manifestations
Pathology
Differential Diagnosis
Treatment
Muir–Torre Syndrome
Introduction
History
Epidemiology
Pathogenesis
Clinical Features
Pathology
Differential Diagnosis
Treatment
Enzyme Deficiency Diseases
Alkaptonuria
Biotinidase and Holocarboxylase Synthetase Deficiencies
Fabry Disease
Fucosidosis
Gaucher Disease
Hartnup Disease
Mitochondrial Disorders
Niemann–Pick Disease
Phenylketonuria
Premature Aging Syndromes and Poikilodermas
Hutchinson–Gilford Progeria Syndrome
Introduction
History
Epidemiology
Pathogenesis
Clinical Features
Pathology and Laboratory Findings
Differential Diagnosis
Treatment
Werner Syndrome
Introduction
History
Epidemiology
Pathogenesis
Clinical Features
Pathology and Laboratory Findings
Differential Diagnosis
Treatment
Ectodermal Dysplasias
Hypohidrotic Ectodermal Dysplasia
Epidemiology
Pathogenesis
Clinical Features
Pathology
Differential Diagnosis
Treatment
Hypohidrotic Ectodermal Dysplasia With Immune Deficiency
Pathogenesis
Clinical Features
Treatment
Hidrotic Ectodermal Dysplasia
Pathogenesis
Clinical Features
Pathology
Differential Diagnosis
Treatment
Witkop Tooth and Nail Syndrome
Ankyloblepharon–Ectodermal Defects–Cleft Lip/Palate Syndrome
Pathogenesis
Clinical Features
Pathology
Differential Diagnosis
Treatment
Ectodermal Dysplasia–Ectrodactyly–Clefting Syndrome
Pathogenesis
Clinical Features
Pathology
Differential Diagnosis
Treatment
References
Chapter 64: Developmental Anomalies
Abstract
Keywords:
Chapter Contents
Introduction
The Midline Lesion
Midline Lesions of the Head and Neck
Midline nasal lesions
Midline lesions of the scalp
Other developmental anomalies of the scalp
Dermoid cysts
Cephaloceles
Nasal gliomas
Heterotopic brain tissue and rudimentary meningoceles
Midline cervical clefts
Sternal clefts and supraumbilical raphae
Midline Lesions of the Spine
Aplasia Cutis Congenita
Other Developmental Anomalies
Congenital Lip Pits
Accessory Tragi
Congenital Cartilaginous Rests of the Neck
Branchial Cleft Sinuses and Fistulae
Supernumerary Nipples and Other Forms of Accessory Mammary Tissue
Absent, Hypoplastic or Anomalous Nipples
Skin Dimples
Congenital Malformations of the Dermatoglyphs
Rudimentary Polydactyly
Amniotic Band Sequence and Disorganization Syndrome
Other Developmental Anomalies Associated With Cutaneous Diseases
Section 10: Pigmentary Disorders
Chapter 65: Melanocyte Biology
Abstract
Keywords:
Introduction
Origin and Function of the Melanocyte
Formation and Function of the Melanosome
Regulation of Melanin Biosynthesis
Ultraviolet Radiation (UVR)
Chapter 66: Vitiligo and Other Disorders of Hypopigmentation
Abstract
Keywords
Chapter Contents
Introduction
Diagnosis of Leukodermas
Vitiligo
Epidemiology
Pathogenesis
Genetics of vitiligo
Pathogenic hypotheses for vitiligo
Clinical Features
Clinical variants
Clinical classification of vitiligo
Course of the disease
Vitiligo and ocular disease
Associated disorders
Childhood vitiligo
Pathology
Differential Diagnosis
Treatment
Corticosteroids
Topical calcineurin inhibitors (TCIs)
Photo(chemo)therapy
Narrowband UVB
Psoralen plus UVA
Other phototherapies
Lasers and related light devices
Excimer laser and lamp
Helium–neon laser
Surgical therapies
Combination therapy
Micropigmentation
Depigmentation
Psychological support
Additional controversial therapies
Pseudocatalase with narrowband UVB
Systemic antioxidant therapy
Potential emerging treatments
Ablative laser treatment followed by narrowband UVB plus topical 5-fluorouracil or corticosteroids
Topical prostaglandins
Afamelanotide
Janus kinase (JAK) inhibitors
Hereditary Hypomelanosis
Oculocutaneous Albinism
Epidemiology
Pathogenesis
Clinical features
Ocular manifestations
OCA1
OCA1A
OCA1B
OCA2
OCA3
OCA4
OCA5–7
Ocular albinism type 1 (OA1)
Pathology
Differential diagnosis
Treatment
Piebaldism
Epidemiology
Pathogenesis
Clinical features
Pathology
Differential diagnosis
Treatment
Waardenburg Syndrome
Epidemiology
Pathogenesis
Clinical features
Waardenburg syndrome type 1 (WS1)
Waardenburg syndrome type 2 (WS2)
Klein–Waardenburg syndrome (WS3)
Shah–Waardenburg syndrome (WS4)
Tietz syndrome
Pathology
Diagnosis
Treatment
Disorders of Melanosome Biogenesis
Hermansky–Pudlak syndrome
Pathogenesis
Clinical features
Laboratory findings and pathology
Differential diagnosis
Treatment
Cross syndrome
Chédiak–Higashi syndrome
Tricho-hepato-enteric syndrome (phenotypic diarrhea of infancy)
Disorders of Melanosome Transport and/or Transfer
Epidemiology
Pathogenesis
Clinical features
Treatment
Tuberous Sclerosis Complex
Clinical features
Pathogenesis
Diagnosis
“Pigmentary Mosaicism”: Linear Nevoid Hypopigmentation, Hypomelanosis of Ito, Segmental Pigmentation Disorder, and Nevus Depigmentosus
Clinical features
Pathology
Diagnosis
Nutritional Hypomelanosis
Hypomelanosis Secondary to Cutaneous Inflammation
Epidemiology
Pathogenesis
Clinical features
Pathology
Treatment
Pityriasis Alba
Sarcoidosis
Hypopigmented Mycosis Fungoides
Systemic Sclerosis (Scleroderma) and Lichen Sclerosus
Lupus Erythematosus
Infectious and Parasitic Hypomelanosis
Tinea (Pityriasis) Versicolor
Leprosy (Hansen Disease)
Treponematoses
Onchocerciasis
Post-Kala-Azar Dermal Leishmaniasis
Herpes Zoster
Halo Nevus and Melanoma-Associated Leukoderma
Halo Nevus
Melanoma-Associated Leukoderma
Chemical and Pharmacologic Hypomelanosis
Hypomelanosis From Physical Agents
Miscellaneous
Idiopathic Guttate Hypomelanosis
Vagabond’s Leukomelanoderma
Progressive Macular Hypomelanosis
Hair Hypomelanosis
Leukodermas Without Hypomelanosis
Woronoff’s ring
Nevus anemicus
Cutaneous edema and anemia
Angiospastic macules (Bier spots)
References
Chapter 67: Disorders of Hyperpigmentation
Abstract
Keywords:
Chapter Contents
Diffuse and Circumscribed Hyperpigmentation
Introduction
Postinflammatory Hyperpigmentation
Introduction
Epidemiology
Pathogenesis
Clinical Features
Pathology
Differential Diagnosis
Treatment
Erythema Dyschromicum Perstans
Introduction
Epidemiology
Pathogenesis
Clinical Features
Pathology
Differential Diagnosis
Treatment
Lichen Planus Pigmentosus
Melasma
Introduction and Epidemiology
Pathogenesis
Clinical Features
Pathology
Differential Diagnosis
Treatment
Additional Forms of Circumscribed Hyperpigmentation
Segmental Pigmentation Disorder
Familial Progressive Hyperpigmentation
Primary (Localized) Cutaneous Amyloidosis
Mastocytosis
Tinea (Pityriasis) Versicolor
Atrophoderma of Pasini and Pierini
Pigmented Lesions
Lentigines
Café-au-Lait Macules
Drug-Induced Hyperpigmentation or Discoloration
Additional Forms of Diffuse Hyperpigmentation
Linear Hyperpigmentation
Pigmentary Demarcation Lines
Introduction
Differential Diagnosis
Treatment
Linear Postinflammatory Hyperpigmentation
Clinical Features
Differential Diagnosis
Flagellate Pigmentation From Bleomycin
Introduction
Epidemiology
Pathogenesis
Clinical Features
Pathology
Differential Diagnosis
Treatment
Flagellate Mushroom Dermatitis
Introduction
History and Epidemiology
Pathogenesis
Clinical Features
Pathology
Treatment
Hyperpigmentation Along the Lines of Blaschko
Linear and Whorled Nevoid Hypermelanosis
Introduction
Epidemiology
Pathogenesis
Clinical features
Pathology
Differential diagnosis
Treatment
Incontinentia Pigmenti
Reticulated Hyperpigmentation
Prurigo Pigmentosa
Dyskeratosis Congenita
Introduction
Epidemiology
Pathogenesis
Clinical Features
Pathology
Differential Diagnosis
Treatment
Naegeli–Franceschetti–Jadassohn Syndrome
Introduction
History
Epidemiology
Pathogenesis
Clinical Features
Pathology
Differential Diagnosis
Treatment
Dermatopathia Pigmentosa Reticularis
Introduction and Pathogenesis
Clinical Features
Pathology
Differential Diagnosis
X-Linked Reticulate Pigmentary Disorder
Introduction and Pathogenesis
Epidemiology
Clinical Features
Pathology
Differential Diagnosis
Treatment
Dowling–Degos Disease
Introduction
Epidemiology
Pathogenesis
Clinical Features
Pathology
Differential Diagnosis
Treatment
Reticulate Acropigmentation of Kitamura
Introduction and Pathogenesis
Clinical Features
Pathology
Differential Diagnosis
Treatment
Dyschromatoses
Dyschromatosis Symmetrica Hereditaria
Introduction
Pathogenesis
Clinical Features
Pathology
Differential Diagnosis
Treatment
Dyschromatosis Universalis Hereditaria
Introduction and Pathogenesis
Clinical Features
Pathology
Differential Diagnosis
Treatment
Acquired Brachial Cutaneous Dyschromatosis
References
Section 11: Hair, Nails, and Mucous Membranes
Chapter 68: Biology of Hair and Nails
Abstract
Keywords:
Principles of Adnexal Morphogenesis
Biology of Hair
Hair Follicle Morphogenesis
Hair follicle patterning
Postnatal hair follicle development
The Mature Hair Follicle: Cycling and Anatomy
Anagen
Catagen
Telogen
Exogen
Structure of the hair fiber
Hair Keratins
Desmosomes in the Hair Follicle
Hair Follicle Stem Cells
The Hair Follicle and the Immune System
Biology of Nails
Nail Unit Anatomy
Nail Embryology
Nail Matrix
Matrix anatomy
Matrix function
Nail Stem Cells
Nail Unit Melanocytes
The Nail Immune System
Nail Keratins
Other Nail Plate Components
Nail Growth
References
Chapter 69: Alopecias
Abstract
Keywords
Chapter Contents
Introduction
Androgenetic Alopecia
Introduction
Pathogenesis
Clinical Features
Pathology
Differential Diagnosis
Treatment
Male pattern hair loss
Female pattern hair loss
Telogen Effluvium
Introduction
Pathogenesis
Clinical Features
Alopecia Areata
Introduction
Epidemiology
Pathogenesis
Clinical Features
Differential Diagnosis
Treatment
Trichotillomania
Introduction
Pathogenesis
Clinical Features
Treatment
Other Non-Cicatricial (Non-Scarring) Alopecias
Pressure-Induced Alopecia
Temporal Triangular Alopecia
Lipedematous Alopecia (Lipedematous Scalp)
Psoriasis of the Scalp and TNF-α Inhibitor-Induced Psoriasiform Alopecia
Congenital Atrichia With Papules
Cicatricial (Scarring) Alopecias
Introduction
Central Centrifugal Cicatricial Alopecia
Introduction
Epidemiology
Pathogenesis
Clinical features
Pathology
Differential diagnosis
Treatment
Lichen Planopilaris and Frontal Fibrosing Alopecia
Introduction
Clinical features
Pathology
Treatment
Discoid Lupus Erythematosus
Introduction
Clinical features
Pathology
Treatment
Acne Keloidalis
Introduction
Pathogenesis
Clinical and histopathologic features
Treatment
Dissecting Cellulitis of the Scalp
Introduction
Clinical and histopathologic features
Differential diagnosis
Treatment
Cicatricial Alopecia, Not Otherwise Classified
“Burnt-out” or “end-stage” cicatricial alopecia
Brocq’s alopecia (pseudopelade of Brocq)
“Folliculitis decalvans”
“Tufted folliculitis”
Traction Alopecia (End-Stage)
Hair Shaft Abnormalities
Introduction
Structural Hair Abnormalities Associated With Increased Hair Fragility
“Bubble hair”
Monilethrix
Pili torti
Trichorrhexis invaginata
Trichorrhexis nodosa
Trichothiodystrophy
Structural Hair Abnormalities Not Associated With Increased Hair Fragility
Acquired progressive kinking of the hair
Loose anagen hair syndrome
Pili annulati
Pili bifurcati
Pili multigemini
Spun-glass hair (uncombable hair)
Woolly hair
Alopecia of Sites Other Than the Scalp
References
Chapter 70: Hypertrichosis and Hirsutism
Abstract
Keywords
Hypertrichosis
Introduction
Clinical Features
Generalized hypertrichosis
Congenital generalized hypertrichosis
Prepubertal hypertrichosis
Acquired generalized hypertrichosis
Acquired hypertrichosis lanuginosa
Localized hypertrichosis
Congenital localized hypertrichosis
Congenital melanocytic nevi and plexiform neurofibromas
Becker melanosis (nevus)
Other hamartomas and infantile tumors
Nevoid hypertrichosis
Spinal dysraphism and the hair collar sign
Localized hypertrichosis in hereditary and acquired systemic diseases
Acquired localized hypertrichosis
Treatment
Hirsutism
Introduction
Epidemiology
Classification
Clinical Features
Constitutional (dermatologic) hirsutism
Adrenal hirsutism
Non-tumoral adrenal hirsutism – adrenal hyperplasias
Hypercortisolism (Cushing syndrome)
Tumoral adrenal hirsutism
Ovarian hirsutism
Non-tumoral ovarian hirsutism
Polycystic ovary syndrome (PCOS)
Ovarian hyperthecosis
Tumoral ovarian hirsutism
Pituitary hirsutism
Iatrogenic hirsutism
Hirsutism due to ectopic hormones
Diagnosis
Treatment
Systemic treatment
Adrenal SAHA syndrome (persistent adrenarche syndrome)
Ovarian SAHA syndrome (excess ovarian androgen release syndrome)
SAHA syndrome with hyperprolactinemia
Iatrogenic hirsutism
Topical medications
Chemical and physical methods
Surgical therapy
References
Chapter 71: Nail Disorders
Abstract
Keywords:
Chapter Contents
Anatomy
Nail Signs
Nail Signs Due to Abnormal Nail Matrix Function
Beau’s lines
Onychomadesis (nail shedding)
Pitting
Onychorrhexis
Trachyonychia (twenty-nail dystrophy, sandpapered nails)
True leukonychia
Koilonychia (spoon nails)
Nail Signs Due to Nail Bed Disorders
Onycholysis
Subungual hyperkeratosis
Apparent leukonychia
Splinter hemorrhages
Nail Signs Due to Deposition of Pigment
Longitudinal melanonychia
Green nail syndrome
Congenital and Hereditary Nail Diseases
Congenital Malalignment of the Great Toenails
Congenital Hypertrophy of the Lateral Fold of the Hallux
Racquet Thumbs (Brachyonychia)
Nail–Patella Syndrome (Onycho-Osteodysplasia; Fong Disease)
Epidermolysis Bullosa
Ectodermal Dysplasias
Pachyonychia Congenita
Darier Disease (Follicular Dyskeratosis)
The Nail in Dermatologic Diseases
Psoriasis
Treatment
Acrodermatitis Continua of Hallopeau (Hallopeau’s Acrodermatitis, Dermatitis Repens)
Treatment
Parakeratosis Pustulosa
Treatment
Lichen Planus
Treatment
Trachyonychia (Twenty-Nail Dystrophy, Sandpapered Nails)
Alopecia Areata
Eczema (Dermatitis)
The Nail in Systemic Diseases
Clubbing (Watch-Glass Nails, Hippocratic Fingers, Drumstick Fingers)
Yellow Nail Syndrome
Treatment
Apparent Leukonychia
Autoimmune Connective Tissue Disorders
HIV Infection
Drug-Induced Nail Abnormalities
Infections
Acute Paronychia
Treatment
Warts
Treatment
Onychomycosis (Tinea Unguium)
Environmental Nail Disorders
Brittle Nails (Fragility, Onychoschizia)
Treatment
Chronic Paronychia
Treatment
Idiopathic Onycholysis
Treatment
Traumatic Nail Abnormalities
Onychotillomania
Treatment
Subungual Hematoma
Treatment
Traumatic Toenail Abnormalities
Onychogryphosis
Pincer Nails (Trumpet Nails)
Treatment
Ingrown Toenails (Onychocryptosis)
Treatment
Nail Tumors
Benign Tumors and Proliferations
Pyogenic granuloma (botryomycoma)
Fibromas/fibrokeratomas
Subungual exostosis
Myxoid cyst (mucous cyst)
Treatment
Glomus tumor
Onychomatricoma
Onychopapilloma
Melanocytic nevi of the nail matrix
Treatment
Malignant Tumors
Bowen disease (squamous cell carcinoma in situ)
Keratoacanthoma
Squamous cell carcinoma
Verrucous carcinoma (carcinoma cuniculatum, epithelioma cuniculatum)
Melanoma
Chapter 72: Oral Disease
Abstract
Keywords:
Chapter Contents
Introduction
Common Benign Conditions of the Oral Cavity
Fordyce Granules
Introduction
Epidemiology
Clinical features
Pathology
Treatment
Geographic Tongue
Introduction
Epidemiology
Clinical features
Pathology
Treatment
Fissured Tongue
Introduction
Epidemiology
Clinical features
Treatment
Hairy Tongue
Introduction
Epidemiology
Clinical features
Pathology
Treatment
Central Papillary Atrophy
Introduction
Clinical features
Pathology
Treatment
Syndromes of the Head and Neck
Basal Cell Nevus Syndrome
Gardner Syndrome
Multiple Endocrine Neoplasia Syndrome Type 2B
Periodontal and Dental Disease
Necrotizing Ulcerative Gingivitis
Introduction
Epidemiology
Clinical features
Pathology
Treatment
Desquamative Gingivitis
Introduction
Epidemiology
Clinical features
Pathology
Treatment
Sequelae of Dental Caries
Introduction
Clinical features
Treatment
Physical and Chemical Injuries
Fibroma
Introduction
Epidemiology
Clinical features
Pathology
Treatment
Chemical Burn
Introduction
Clinical features
Pathology
Treatment
Morsicatio Buccarum
Introduction
Clinical features
Pathology
Treatment
Traumatic Ulcer
Introduction
Clinical features
Treatment
Drug-Related Gingival Enlargement (Hyperplasia)
Introduction
Clinical features
Pathology
Treatment
Allergic and Immunologic Diseases
Contact Stomatitis
Introduction
Epidemiology
Clinical features
Pathology
Treatment
Recurrent Aphthous Stomatitis
Introduction
Epidemiology
Clinical features
Pathology
Treatment
Behçet Disease
Eosinophilic Ulcer of the Oral Mucosa
Introduction
Epidemiology
Clinical features
Pathology
Treatment
Orofacial Granulomatosis
Introduction
Epidemiology
Clinical features
Pathology
Treatment
Granulomatosis With Polyangiitis (Formerly Wegener Granulomatosis)
Introduction/clinical features
Pathology
Treatment
Epithelial Pathology
Oral Leukoplakia/Erythroplakia
Introduction
Epidemiology
Clinical features
Pathology
Treatment
Proliferative Verrucous Leukoplakia
Introduction
Epidemiology
Clinical features
Pathology
Treatment
Nicotine Stomatitis
Introduction
Clinical features
Pathology
Treatment
Actinic Cheilitis
Introduction
Epidemiology
Clinical features
Pathology
Treatment
Oral Squamous Cell Carcinoma
Introduction
Epidemiology
Clinical features
Pathology
Treatment
Verrucous Carcinoma
Introduction
Epidemiology
Clinical features
Pathology
Treatment
Salivary Gland Diseases
Mucocele
Introduction
Epidemiology
Clinical features
Pathology
Treatment
Necrotizing Sialometaplasia
Introduction
Epidemiology
Clinical features
Pathology
Treatment
Sjögren Syndrome
Introduction/clinical features
Pathology
Treatment
Salivary Gland Tumors
Introduction/epidemiology
Clinical features/pathology
Treatment
Oral Manifestations of Hematologic/Oncologic Disease
Chemotherapy- and Radiotherapy-Induced Oral Mucositis
Introduction
Clinical features
Treatment
Leukemia
Introduction
Clinical features
Treatment
Lymphoma
Introduction/epidemiology
Clinical features
Pathology
Treatment
Melanoma
Introduction/epidemiology
Clinical features
Pathology
Treatment
Oral Manifestations of Systemic Disease
Amyloidosis
Introduction
Clinical features
Pernicious Anemia
Introduction
Epidemiology
Clinical features
Treatment
Crohn Disease
Introduction/epidemiology
Clinical features
Pathology
Treatment
Pyostomatitis Vegetans
Introduction
Epidemiology
Clinical features
Pathology
Treatment
Oral Manifestions of HIV Infection
Chapter 73: Anogenital (Non-venereal) Disease
Abstract
Keywords:
Chapter Contents
Introduction
Lichen Sclerosus
Introduction
History
Epidemiology
Etiology
Clinical features
Pathology
Differential diagnosis
Treatment
Lichen Planus
Introduction
History
Epidemiology
Etiology
Clinical features
Pathology
Differential diagnosis
Treatment
Zoon Balanitis/Vulvitis
Introduction
Epidemiology
Etiology
Clinical features
Pathology
Differential diagnosis
Treatment
Epithelial Disorders of the Anogenital Region
Dermatitis
Introduction
Pathogenesis
Clinical features
Differential diagnosis
Treatment
Contact Dermatitis
Psoriasis
Clinical features
Differential diagnosis
Treatment
Premalignant and Malignant Lesions
Intraepithelial Neoplasia (Vulvar/Vulval, Penile, Anal)
Introduction
Epidemiology
Pathogenesis
Pathology
Clinical features
Differential diagnosis
Treatment
Prevention
Pseudoepitheliomatous Keratotic and Micaceous Balanitis
Invasive Squamous Cell Carcinomas
Epidemiology
Pathogenesis
Clinical features
Differential diagnosis
Treatment
Anogenital Melanoma
Introduction
Epidemiology
Pathogenesis
Clinical features
Pathology
Differential diagnosis
Treatment
Basal Cell Carcinoma
Extramammary Paget Disease
Introduction
Epidemiology
Etiology
Clinical features
Pathology
Differential diagnosis
Treatment
Dysesthetic Genital Pain Syndromes
Localized Vulvodynia (Vestibulodynia)
Introduction
Clinical features
Differential diagnosis
Treatment
Generalized Vulvodynia/Scrotodynia (Dysesthetic Vulvodynia/Scrotodynia)
Introduction
Clinical features
Differential diagnosis
Treatment
Cyclical Vulvovaginitis
Anal Pain
Benign Lesions
Epidermoid Cysts
Vestibular Papillomatosis
The Anogenital Region and Systemic Disease
Infections
Perianal Streptococcal Disease
Recurrent Toxin-Mediated Perineal Erythema
Kawasaki Disease
Fournier Gangrene
Erythrasma
Dermatophytosis
Cutaneous Candidiasis
Introduction
Epidemiology
Etiology
Clinical features
Differential diagnosis
Treatment
Recurrent Candidiasis
Erosive Genital Disease
Acquired Autoimmune Bullous Diseases
Acquired Inflammatory Bullous Diseases
Erythema multiforme and Stevens–Johnson syndrome
Fixed drug eruption
Inherited Bullous Disease
Hailey–Hailey disease
References
Section 12: Infections, Infestations, and Bites
Chapter 74: Bacterial Diseases
Abstract
Keywords
Chapter Contents
The Cutaneous Microbiota
Gram-Positive Bacteria
Staphylococcal and Streptococcal Skin Infections
Impetigo
Introduction
Epidemiology
Pathogenesis
Clinical features
Pathology
Diagnosis and differential diagnosis
Treatment
Bacterial Folliculitis
Introduction
Epidemiology and pathogenesis
Clinical features
Diagnosis and differential diagnosis
Treatment
Abscesses, Furuncles, and Carbuncles
Introduction
Epidemiology and pathogenesis
Clinical features
Pathology
Diagnosis and differential diagnosis
Treatment
Methicillin-Resistant Staphylococcus aureus
Introduction
Clinical features
Pathogenesis
Diagnosis and treatment
Blistering Distal Dactylitis
Ecthyma
Staphylococcal Scalded Skin Syndrome
Introduction
Epidemiology
Pathogenesis
Clinical features
Pathology
Diagnosis and differential diagnosis
Treatment
Toxic Shock Syndrome
Introduction
Epidemiology and pathogenesis
Clinical features
Pathology
Diagnosis and differential diagnosis
Treatment
Scarlet Fever
Introduction
Epidemiology and pathogenesis
Clinical features
Pathology
Diagnosis and differential diagnosis
Treatment
Streptococcal Toxic Shock Syndrome
Introduction
Epidemiology and pathogenesis
Clinical features
Pathology
Diagnosis and differential diagnosis
Treatment
Erysipelas
Introduction
Epidemiology and pathogenesis
Clinical features
Pathology
Diagnosis and differential diagnosis
Treatment
Streptococcal Intertrigo
Perianal and Vulvovaginal (Perineal) Streptococcal Infection
Cellulitis
Introduction
Epidemiology and pathogenesis
Clinical features
Pathology
Diagnosis and differential diagnosis
Treatment
Pyomyositis
Botryomycosis
Introduction
Epidemiology and pathogenesis
Clinical features
Pathology
Diagnosis and differential diagnosis
Treatment
Necrotizing Fasciitis
Introduction
Epidemiology and pathogenesis
Clinical features
Pathology
Diagnosis and differential diagnosis
Treatment
Bacteremia/Septicemia
Clostridial Skin Infections
Corynebacterial Skin Infections
Erythrasma
Pitted Keratolysis
Introduction
Epidemiology and pathogenesis
Clinical features
Pathology
Diagnosis and differential diagnosis
Treatment
Trichomycosis Axillaris, Pubis, and Capitis
Cutaneous Diphtheria
Other Gram-Positive Skin Infections
Cutaneous Anthrax
Introduction and epidemiology
History
Pathogenesis
Clinical features
Pathology
Diagnosis and differential diagnosis
Treatment
Bacillus cereus Infection
Erysipeloid
Listeriosis
Gram-Negative Bacteria
Neisseria Meningitidis
Acute and Chronic Meningococcemia
Introduction
Epidemiology and pathogenesis
Clinical features
Pathology
Diagnosis and differential diagnosis
Treatment
Pseudomonas Aeruginosa
Green Nail Syndrome
Pseudomonal Pyoderma and Blastomycosis-like Pyoderma
Otitis Externa and Malignant Otitis Externa
Pseudomonal Folliculitis
Pseudomonas Hot-Foot Syndrome
Ecthyma Gangrenosum
Bartonella
Bartonellosis
Introduction
History
Epidemiology and pathogenesis
Clinical features
Pathology
Diagnosis and differential diagnosis
Treatment
Cat Scratch Disease
Introduction
Epidemiology and pathogenesis
Clinical features
Pathology
Diagnosis and differential diagnosis
Treatment
Bacillary Angiomatosis
Introduction
History
Epidemiology and pathogenesis
Clinical features
Pathology
Diagnosis and differential diagnosis
Treatment
Other Gram-Negative Skin Infections
Brucellosis
Glanders
Melioidosis
Cutaneous Malacoplakia (Malakoplakia)
Tularemia
Haemophilus influenzae Cellulitis
Rhinoscleroma
Salmonellosis
Rat-Bite Fever
Plague
Vibrio vulnificus Infection
Ehrlichiosis and Anaplasmosis
Spirochetes
Borrelia Burgdorferi
Lyme Disease
Borrelial Lymphocytoma
Acrodermatitis Chronica Atrophicans
Non-Venereal (Endemic) Treponematoses
Yaws
Pinta
Endemic Syphilis
Leptospirosis
Bacteria Previously Classified as Fungi
Actinomycosis
Introduction
Epidemiology and pathogenesis
Clinical features
Pathology
Diagnosis and differential diagnosis
Treatment
Nocardiosis
Introduction
Epidemiology and pathogenesis
Clinical features
Pathology
Diagnosis and differential diagnosis
Treatment
References
Chapter 75: Mycobacterial Infections
Abstract
Keywords:
Chapter Contents
Leprosy
Introduction
History
Epidemiology
Pathogenesis
Clinical Features
Pathology and Laboratory Evaluation
Differential Diagnosis
Treatment
Cutaneous Tuberculosis
Introduction
History
Epidemiology
Pathogenesis
Clinical Features
Cutaneous tuberculosis
Tuberculids
BCG inoculation
Diagnosis
Treatment
Non-Tuberculous Mycobacterioses
Introduction
Mycobacterium ulcerans
Introduction and history
Epidemiology
Pathogenesis
Clinical features
Pathology
Diagnosis and differential diagnosis
Treatment
Mycobacterium marinum
Introduction and history
Epidemiology and pathogenesis
Clinical features
Pathology
Diagnosis and differential diagnosis
Treatment
Mycobacterium kansasii
Introduction and history
Epidemiology and pathogenesis
Clinical features
Pathology
Diagnosis and differential diagnosis
Treatment
Mycobacterium fortuitum, Mycobacterium chelonae, and Mycobacterium abscessus
Introduction and history
Epidemiology and pathogenesis
Clinical features
Pathology
Diagnosis and differential diagnosis
Treatment
Mycobacterium avium Complex (MAC)
Introduction
Epidemiology and pathogenesis
Clinical features
Pathology
Diagnosis and differential diagnosis
Treatment
Mycobacterium haemophilum
Introduction
Epidemiology and pathogenesis
Clinical features
Pathology
Diagnosis and differential diagnosis
Treatment
Mycobacterium scrofulaceum
Introduction
Epidemiology and pathogenesis
Clinical features
Pathology
Diagnosis and differential diagnosis
Treatment
Chapter 76: Rickettsial Diseases
Abstract
Keywords:
Chapter Contents
Introduction
Spotted Fever and Typhus Group Rickettsial Infections
History
Epidemiology
Pathogenesis
Clinical Features
Clinical course and systemic features
Shared cutaneous features
Features of specific diseases
Pathology
Diagnosis and Differential Diagnosis
Treatment
Scrub Typhus
Human Ehrlichioses
Human Granulocytic Anaplasmosis
Q Fever
References
Chapter 77: Fungal Diseases
Abstract
Keywords:
Superficial Mycoses
Introduction
Non-inflammatory superficial mycoses
History
Epidemiology
Pathogenesis
Clinical features
Piedra
Tinea nigra
Tinea (pityriasis) versicolor
Malassezia (Pityrosporum) folliculitis
Pathology and fungal culture
Differential diagnosis
Treatment
Dermatophytoses
Introduction
History
Epidemiology
Pathogenesis
Clinical features
Tinea corporis
Tinea cruris
Tinea manuum
Tinea barbae
Tinea faciei
Tinea capitis
Tinea pedis
Tinea unguium (dermatophytic onychomycosis)
Pathology
Differential diagnosis
Treatment
Invasive dermatophytosis
Mucocutaneous candida infections
Chronic mucocutaneous candidiasis
Granuloma gluteale infantum/adultorum and perianal pseudoverrucous papules/nodules
Subcutaneous Mycoses
Chromoblastomycosis
Introduction
History
Epidemiology and pathogenesis
Clinical features
Pathology
Differential diagnosis
Treatment
Mycetoma
Introduction
History and epidemiology
Pathogenesis
Clinical features
Pathology
Differential diagnosis
Treatment
Sporotrichosis
Introduction
Epidemiology
Pathogenesis
Clinical features
Pathology
Differential diagnosis
Treatment
Lobomycosis
Systemic Mycoses
True Pathogens
Introduction
Histoplasmosis
Introduction
Epidemiology
Pathogenesis
Clinical features
Pathology
Differential diagnosis
Treatment
Blastomycosis
Introduction
Epidemiology
Pathogenesis
Clinical features
Pathology
Differential diagnosis
Treatment
Coccidioidomycosis
Introduction
Epidemiology
Pathogenesis
Clinical features
Pathology
Differential diagnosis
Treatment
Paracoccidioidomycosis
Introduction and epidemiology
Pathogenesis
Clinical features
Pathology
Differential diagnosis
Treatment
Opportunistic Pathogens
Introduction
History
Epidemiology
Pathogenesis
Clinical features
Pathology
Differential diagnosis
Treatment
Phaeohyphomycosis
Introduction and history
Epidemiology
Pathogenesis
Clinical features
Pathology
Differential diagnosis
Treatment
Pneumocystis
References
Chapter 78: Cutaneous Manifestations of HIV Infection
Abstract
Keywords
Introduction
History
Epidemiology
Pathogenesis
HIV-Related Infectious Skin Conditions
Viral Infections
Primary HIV exanthem (acute retroviral syndrome)
Herpes simplex virus (HSV)
Varicella–zoster virus (VZV)
Molluscum contagiosum virus
Human papillomavirus (HPV)
Epstein–Barr virus (EBV)
Cytomegalovirus (CMV)
Bacterial Infections
Staphylococcus aureus
Bacillary angiomatosis
Mycobacteria
Syphilis
Fungal and Related Infections
Candidiasis
Dermatophytoses
Systemic fungal infections
Pneumocystis jiroveci
Other fungal and related infections
Parasitic Infections
Leishmaniasis
Strongyloidiasis
Acanthamebiasis
Ectoparasitic Infestations and Insect Bites
Scabies
Demodicosis
Insect bite reactions
Non-Infectious HIV-Related Dermatoses
Papulosquamous Disorders
Seborrheic dermatitis
Psoriasis
Reactive arthritis
Other papulosquamous dermatoses
Non-Infectious Pruritic Papular Disorders
Pruritic papular eruption
Eosinophilic folliculitis
Hair and Nail Disorders
Vasculitis
Photosensitivity Reactions
UV light hypersensitivity
Porphyria cutanea tarda (PCT)
Chronic actinic dermatitis
Metabolic Changes
HIV/ART-associated lipodystrophy
Malnutrition
Miscellaneous Dermatoses
HIV-Related Cutaneous Neoplasms
Kaposi Sarcoma (KS)
Squamous and Basal Cell Carcinomas and Melanoma
Lymphomas
Other Cutaneous Neoplasms
Differential Diagnosis and Diagnosis
Differential Diagnosis of HIV-associated Skin Conditions
Diagnosis of HIV-associated Skin Conditions
Laboratory Diagnosis of HIV Infection
Antiretroviral Therapy (ART)
Antiretroviral Medications for Treatment and Prevention
Immune Reconstitution Inflammatory Syndrome (IRIS)
Drug–Drug Interactions
Drug Eruptions
Conclusions
References
Chapter 79: Human Papillomaviruses
Abstract
Keywords
Introduction
History
Epidemiology
Pathogenesis
Papillomavirus Evolution
Virology
Papillomavirus Life Cycle
Host Immune Response
Oncogenic Potential of HPV
Clinical Features
Cutaneous Infections
Mucosal Infections
Pathology
Common and Deep Palmoplantar Warts
Flat Warts
Epidermodysplasia Verruciformis
Anogenital Warts
Giant Condylomata of Buschke–Löwenstein
Squamous Intraepithelial Neoplasias
Differential Diagnosis
Common Warts
Anogenital Lesions
Oral Warts
Therapy
General Considerations
Local Destructive Therapy
Topical and Intralesional Cytotoxic Therapy
Topical Immunomodifiers
Systemic Immunomodifiers
Immunotherapy
Antiviral Agents
Retinoids
Special Considerations
HPV Vaccines
Disclaimer
References
Chapter 80: Human Herpesviruses
Abstract
Keywords:
Chapter Contents
Herpes Simplex Viruses (HSV-1 and HSV-2)
Introduction
History
Epidemiology
Pathogenesis
Clinical Features
Other Clinical Presentations of HSV Infection
Diagnosis and Pathology
Differential Diagnosis
Treatment and Prevention
Varicella–Zoster Virus (VZV; HHV-3)
Introduction
History
Epidemiology
Pathogenesis
Clinical Features
Varicella
Herpes zoster
Diagnosis and Pathology
Differential Diagnosis
Treatment and Prevention
Varicella
Herpes zoster
Epstein–Barr Virus (HHV-4)
Introduction and History
Epidemiology
Pathogenesis
Clinical Features
Diagnosis and Pathology
Differential Diagnosis
Treatment
Cytomegalovirus (HHV-5)
Introduction
History
Epidemiology
Pathogenesis
Clinical Features
Diagnosis and Pathology
Differential Diagnosis
Treatment and Prevention
Human Herpesvirus Type 6 (HHV-6)
Introduction
History
Epidemiology
Pathogenesis
Clinical Features
Diagnosis and Pathology
Differential Diagnosis
Treatment
Human Herpesvirus Type 7 (HHV-7)
Human Herpesvirus Type 8 (HHV-8)
Introduction
History
Epidemiology
Pathogenesis
Clinical Features
Diagnosis and Pathology
Treatment
Conclusion
References
Chapter 81: Other Viral Diseases
Abstract
Keywords:
Chapter Contents
Introduction
Enterovirus Infections
Introduction
Epidemiology
Pathogenesis
Clinical Features and Differential Diagnosis
Pathology
Treatment
Measles
Introduction and History
Epidemiology
Pathogenesis
Clinical Features and Differential Diagnosis
Pathology
Treatment
Rubella
Introduction and History
Epidemiology
Pathogenesis
Clinical Features and Differential Diagnosis
Pathology
Treatment
Erythema Infectiosum
Introduction and History
Epidemiology
Pathogenesis
Clinical Features and Differential Diagnosis
Pathology
Treatment
Roseola Infantum
Unilateral Laterothoracic Exanthem
Introduction and History
Epidemiology
Pathogenesis
Clinical Features and Differential Diagnosis
Pathology
Treatment
Gianotti–Crosti Syndrome
Introduction and History
Epidemiology
Pathogenesis
Clinical Features and Differential Diagnosis
Pathology
Treatment
Poxvirus Infections
Viral Hemorrhagic Fevers, Including Dengue
West Nile Virus Infection
Zika Virus Infection
Chikungunya Fever
Barmah Forest and Ross River Virus Infections
Cutaneous Manifestations of Hepatitis A, B, and C Infection
Trichodysplasia Spinulosa
Rabies
Kawasaki Disease
Introduction and History
Epidemiology
Pathogenesis
Clinical Features and Differential Diagnosis
Pathology
Treatment
References
Chapter 82: Sexually Transmitted Infections
Abstract
Keywords
Chapter Contents
Introduction
Syphilis
History
Epidemiology
Biology of T. pallidum
Pathogenesis of Untreated Syphilis
Primary stage
Secondary stage
Latency
Tertiary stage
Syphilis and HIV
Clinical Features
Primary syphilis
Secondary syphilis
Latent syphilis
Tertiary (late) syphilis
“Benign” late syphilis
Cardiovascular syphilis
Neurosyphilis
Neurosyphilis in HIV-infected individuals
Laboratory diagnosis of neurosyphilis
Congenital syphilis
Early congenital syphilis
Late congenital syphilis and stigmata
Laboratory diagnosis of congenital syphilis
Laboratory Diagnosis of Syphilis
Identification of T. pallidum
Microscopic examination
Polymerase chain reaction-based assays
Serologic tests for syphilis
Non-treponemal tests
Treponemal tests
Pathology
Differential Diagnosis
Treatment
Gonorrhea
History
Epidemiology
Transmission
Biology of N. gonorrhoeae
Pathogenesis
Clinical Features
Gonococcal infection in men
Gonococcal infection in women
Extragenital gonorrhea
Pharyngeal gonorrhea
Rectal gonorrhea
Gonococcal ophthalmia (including ophthalmia neonatorum)
Disseminated gonococcal infection
Arthritis–dermatosis syndrome (gonococcemia)
Laboratory Diagnosis
Staining methods
Non-culture techniques for gonococcal diagnosis
Nucleic acid amplification techniques (NAATs)
Non-amplified DNA hybridization
Culture techniques
Pathology
Differential Diagnosis
Treatment
Chancroid
History
Epidemiology
Transmission
Chancroid and HIV
Biology of the Organism
Pathogenesis
Clinical Features
Pathology
Diagnosis
Differential Diagnosis
Treatment
Lymphogranuloma Venereum
History
Epidemiology
Pathogenesis
Clinical Features
Pathology
Diagnosis
Differential Diagnosis
Treatment
Donovanosis (Granuloma Inguinale)
History
Epidemiology
Pathogenesis
Clinical Features
Pathology
Diagnosis
Differential Diagnosis
Treatment
References
Chapter 83: Protozoa and Worms
Abstract
Keywords
Chapter Contents
Protozoa
Leishmaniasis
Introduction
Epidemiology
Pathogenesis
Clinical Features
Cutaneous leishmaniasis
Mucocutaneous/mucosal leishmaniasis
Visceral leishmaniasis (kala-azar)
Leishmaniasis and HIV
Pathology
Diagnosis
Differential Diagnosis
Treatment
Cutaneous Diseases Caused by Amebas
Amebiasis due to Entamoeba Histolytica
Introduction
Epidemiology
Pathogenesis
Clinical features
Pathology and diagnosis
Differential diagnosis
Treatment
Balamuthia mandrillaris Infection
Introduction
Epidemiology
Pathogenesis
Clinical features
Pathology and diagnosis
Treatment
Trypanosomiasis
Chagas Disease
Epidemiology
Pathogenesis
Clinical features
Pathology
Diagnosis and differential diagnosis
Treatment
African Trypanosomiasis
Epidemiology
Pathogenesis
Clinical features
Pathology and diagnosis
Differential diagnosis
Treatment
Toxoplasmosis
Worms (Helminths)
Cutaneous Larva Migrans
Epidemiology and Pathogenesis
Clinical Features
Pathology
Differential Diagnosis
Treatment
Gnathostomiasis
Introduction
Epidemiology
Pathogenesis
Clinical Features
Pathology
Diagnosis and Differential Diagnosis
Treatment
Onchocerciasis
Introduction
Epidemiology
Pathogenesis
Clinical Features
Pathology
Diagnosis
Differential Diagnosis
Treatment
Filariasis
Introduction
Epidemiology
Pathogenesis
Clinical Features
Diagnosis
Differential Diagnosis
Treatment
Schistosomiasis and Swimmer’s Itch
Introduction
Epidemiology
Pathogenesis
Clinical Features
Pathology
Diagnosis
Differential Diagnosis
Treatment
Cysticercosis and Echinococcosis
Introduction
Epidemiology
Pathogenesis
Clinical Features
Diagnosis
Treatment
References
Chapter 84: Infestations
Abstract
Keywords:
Chapter Contents
Scabies
Introduction
History
Epidemiology
Pathogenesis
Clinical Features
Pathology
Differential Diagnosis
Treatment
Permethrin
Lindane
Crotamiton
Sulfur ointment
Ivermectin
Head Lice
Introduction
History
Epidemiology
Pathogenesis
Clinical Features
Pathology
Differential Diagnosis
Treatment
Pyrethrins
Permethrin
Lindane
Malathion
Carbaryl
Ivermectin
Benzyl alcohol
Dimethicone
Spinosad
Crab Lice
Introduction
History
Epidemiology
Pathogenesis
Clinical Features
Pathology
Differential Diagnosis
Treatment
Body Lice
Introduction
Epidemiology
Pathogenesis
Clinical Features
Pathology
Differential Diagnosis
Treatment
Tungiasis
Introduction
History
Epidemiology
Pathogenesis
Clinical Features
Pathology
Differential Diagnosis
Treatment
Cutaneous Myiasis
Introduction
History
Epidemiology
Pathogenesis
Clinical Features
Pathology
Differential Diagnosis
Treatment
Preventative Measures
References
Chapter 85: Bites and Stings
Abstract
Keywords:
Chapter Contents
Insects
Insect Bites and Stings (Class Insecta)
Introduction
Epidemiology
Pathogenesis
Clinical features
Pathology
Differential diagnosis
Treatment
Fire Ants
Introduction
Pathogenesis
Clinical features
Treatment
Bedbugs
Introduction
Pathogenesis
Clinical features
Treatment
Triatomine (Reduviid) Bug
Introduction
Clinical features
Blister Beetles
Introduction
Clinical features
Pathology
Treatment
Rove Beetles
Introduction
Clinical features
Pathology
Treatment
Fleas
Introduction
Clinical features
Treatment
Lepidopterism
Introduction
Pathogenesis
Clinical features
Arachnids
Tick Bites (Class Arachnida: Subclass Acarina)
Introduction
Clinical features
Treatment
Environmental measures
Repellents
Tick removal
Antibiotic prophylaxis after tick bites
Amblyomma Ticks
Introduction
Clinical features
Dermacentor Ticks
Introduction
Pathogenesis
Clinical features
Rhipicephalus Ticks
Introduction
Clinical features
Ixodes Ticks
Introduction
Clinical features
Mites (Class Arachnida: Subclass Acarina)
Introduction
Clinical features
Differential diagnosis
Treatment
Chiggers
Introduction
Clinical features
Treatment
Cheyletiella
Introduction
Clinical features
Treatment
Spider Bites (Class Arachnida: Order Araneae)
Widow Spiders (Latrodectus)
Introduction
Pathogenesis
Clinical features
Treatment
Loxosceles Spiders
Introduction
Pathogenesis
Clinical features
Pathology
Treatment
Funnel Web Spiders
Introduction
Pathogenesis
Clinical features
Tarantulas (Family Theraphosidae)
Introduction
Clinical features
Pathology
Scorpions (Class Arachnida: Order Scorpiones)
Introduction
Clinical features
Treatment
Centipedes (Class Chilopoda) and Millipedes (Class Diplopoda)
Introduction
Clinical features
Treatment
Snake Bites
Introduction
Clinical features
Treatment
Dog and Cat Bites
Introduction
Clinical features
Treatment
Leeches
Introduction
Pathogenesis
Clinical features
Treatment
Leech therapy
Marine Injuries
Introduction
Pathogenesis
Clinical features
Pathology
Treatment
References
Section 13: Disorders Due to Physical Agents
Chapter 86: Ultraviolet Radiation
Abstract
Keywords:
Introduction
Spectrum of UV Light and Absorption Spectra
Short-Term Effects of Ultraviolet Light: Sunburn and Tanning
Effects on the Cutaneous Immune System
Long-Term Effects of Ultraviolet Light: Photoaging and Photocarcinogenesis
Photoaging
UV-Induced Tumor Formation
UV Induction of DNA Damage
Repair of UV-Induced DNA Damage
UV-Induced Mutation Formation
Protection Against Photocarcinogenesis
References
Chapter 87: Photodermatologic Disorders
Abstract
Keywords:
Abnormal Cutaneous Effects to Light
Immunologically-Mediated Photodermatoses
Polymorphous light eruption
Introduction and history
Epidemiology
Pathogenesis
Clinical features
Pathology
Differential diagnosis
Treatment
Actinic prurigo
Introduction and history
Epidemiology
Pathogenesis
Clinical features
Pathology
Differential diagnosis
Treatment
Hydroa vacciniforme
Introduction and history
Epidemiology
Pathogenesis
Clinical features
Pathology
Differential diagnosis
Treatment
Chronic actinic dermatitis
Introduction and history
Epidemiology
Pathogenesis
Clinical features
Pathology
Differential diagnosis
Treatment
Solar urticaria
Introduction and history
Epidemiology
Pathogenesis
Clinical features
Pathology
Differential diagnosis
Treatment
Photosensitity Due to Hereditary Defects in DNA Repair
Xeroderma pigmentosum
Introduction and history
Epidemiology
Pathogenesis
Clinical features
Treatment
Cockayne syndrome
Introduction and history
Epidemiology
Pathogenesis
Clinical features
Treatment
UV-sensitive syndrome
Trichothiodystrophy
Introduction and history
Epidemiology
Pathogenesis
Clinical features
Treatment
Photosensitivity Due to Chromosomal Instability
Bloom syndrome
Introduction and history
Epidemiology
Pathogenesis
Clinical features
Treatment
Rothmund–Thomson syndrome
Introduction and history
Epidemiology
Pathogenesis
Clinical features
Differential diagnosis
Treatment
Chemical- and Drug-Induced Photosensitivity
Exogenous photosensitivity
Introduction and history
Epidemiology
Pathogenesis
Clinical features
Phototoxicity
Photoallergy
Pathology
Differential diagnosis
Treatment
Endogenous photosensitivity
Photoaggravated Dermatoses
Introduction and history
Epidemiology
Clinical features
Pathology
Differential diagnosis
Treatment
Grover Disease
Normal Cutaneous Effects of UVR Exposure
Acute and Subacute Effects
Acute inflammatory erythema (sunburn)
Pigment darkening and delayed tanning
Epidermal hyperplasia
Immunologic changes
Vitamin D3 synthesis
Other changes
Chronic Effects
Photoaging in fair-skinned patients
Photoaging in patients with darker skin phototypes
Photocarcinogenesis
References
Chapter 88: Environmental and Sports-Related Skin Diseases
Abstract
Keywords:
Chapter Contents
Injury Due to Heat Exposure
Heat-Related Illnesses and Thermal Burns
Introduction
History
Epidemiology
Pathogenesis
Clinical features
Pathology
Differential diagnosis
Treatment
Erythema Ab Igne
Introduction
History
Epidemiology
Pathogenesis
Clinical features
Pathology
Differential diagnosis
Treatment
Burns Associated With Fluoroscopy and Magnetic Resonance Imaging (MRI)
Introduction
Pathogenesis
Clinical features
Differential diagnosis
Treatment
Airbag Burns
Introduction
Pathogenesis
Clinical features
Differential diagnosis
Treatment
Injury Due to Cold Exposure
Frostbite
Introduction
History
Epidemiology
Pathogenesis
Clinical features
Pathology
Differential diagnosis
Treatment
Pernio
Introduction
History
Epidemiology
Pathogenesis
Clinical features
Pathology
Differential diagnosis
Treatment
Injury Due to Water Exposure
Immersion Foot
Introduction
History
Epidemiology
Pathogenesis
Clinical features
Pathology
Differential diagnosis
Treatment
Injury Due to Electricity
Electrical Burns
Introduction
Pathogenesis
Clinical features
Pathology
Treatment
Chemical Burns and Exposures
Injury Due to Chemical Exposure
Chemical Hair Discoloration
Introduction
History
Epidemiology
Pathogenesis
Clinical features
Pathology
Differential diagnosis
Treatment
Arsenical and Heavy Metal Dermatoses
Introduction
History
Epidemiology
Pathogenesis
Clinical features
Pathology
Differential diagnosis
Treatment
Illness due to Aquatic Toxin Ingestion
Introduction
Epidemiology
Pathogenesis
Clinical features
Treatment
Frictional and Traumatic Injury to the Skin
Corns and Calluses
Introduction
Epidemiology
Pathogenesis
Clinical features
Differential diagnosis
Treatment
Black Heel and Palm
Introduction
History
Epidemiology
Pathogenesis
Clinical features
Pathology
Differential diagnosis
Treatment
Senile Gluteal Dermatosis
Environmental Dermatoses of the External Ear
Sports-Related Dermatoses
Introduction
History
Epidemiology
Pathogenesis
Clinical features
Pathology
Treatment
Amputee-Related Dermatoses
Treatment
Musical Instrument-Related Dermatoses
Introduction
History
Epidemiology
Pathogenesis and clinical features
Pathology
Differential diagnosis
Treatment
Appendix
References
Chapter 89: Signs of Drug Abuse
Abstract
Keywords:
Introduction
Amphetamines
Benzodiazepines
Cannabis
Cocaine
Gamma-Hydroxybutyrate
Lysergic Acid Diethylamide
Opioids (Includes Opiates)
Anabolic Steroids
Pathophysiology of Addiction
Epidemiology
Clinical Features
Scars
Bacterial Infections
Fungal Infections
Granulomas
Mucous Membrane Lesions
Burns
Ulcers
Formication
Additional Cutaneous Findings
Drug-Induced Reactions
Vascular Lesions
Systemic Complications
Treatment
References
Chapter 90: Skin Signs of Abuse
Abstract
Keywords
Chapter Contents
Child Abuse
Introduction
History
Epidemiology
Clinical Features
Physical abuse
Physical neglect
Emotional deprivation
Sexual abuse
Differential Diagnosis
Evaluation and Management
Elder Abuse
Introduction
Risk Factors for Elder Abuse
Clinical Features and Assessment
Management
References
Section 14: Disorders of Langerhans Cells and Macrophages
Chapter 91: Histiocytoses
Abstract
Keywords:
Overview
Langerhans Cell Histiocytosis
Introduction
History
Epidemiology
Pathogenesis
Clinical features
Pathology
Differential diagnosis
Treatment
Non-Langerhans Cell Histiocytoses
Benign Cephalic Histiocytosis
Introduction
History
Epidemiology
Pathogenesis
Clinical features
Pathology
Differential diagnosis
Treatment
Generalized Eruptive Histiocytoma
Introduction
History
Epidemiology
Pathogenesis
Clinical features
Pathology
Differential diagnosis
Treatment
Indeterminate Cell Histiocytosis
Introduction
History
Epidemiology
Pathogenesis
Clinical features
Pathology
Differential diagnosis
Treatment
Juvenile Xanthogranuloma
Introduction
History
Epidemiology
Pathogenesis
Clinical features
Pathology
Differential diagnosis
Treatment
Necrobiotic Xanthogranuloma
Introduction
History
Epidemiology
Pathogenesis
Clinical features
Pathology
Differential diagnosis
Treatment
Reticulohistiocytosis
Introduction
History
Epidemiology
Pathogenesis
Clinical features
Pathology
Differential diagnosis
Treatment
Rosai–Dorfman Disease
Introduction
History
Epidemiology
Pathogenesis
Clinical features
Pathology
Differential diagnosis
Treatment
Xanthoma Disseminatum
Introduction
History
Epidemiology
Pathogenesis
Clinical features
Pathology
Differential diagnosis
Treatment
Malignant Histiocytic Disorders
Dermal Dendrocyte Hamartomas
References
Chapter 92: Xanthomas
Abstract
Keywords:
Introduction
Epidemiology
Pathogenesis
Clinical Features
Eruptive Xanthomas
Tuberous/Tuberoeruptive Xanthomas
Tendinous Xanthomas
Plane Xanthomas and Xanthelasma
Verruciform Xanthomas
Pathology
Differential Diagnosis
Treatment
Acknowledgment
References
Chapter 93: Non-infectious Granulomas
Abstract
Keywords:
Chapter Contents
Introduction
Sarcoidosis
History
Epidemiology
Pathogenesis
Immune mechanisms
Triggers
Genetics
Clinical Features
Pathology
Diagnosis and Differential Diagnosis
Treatment
Granuloma Annulare
History
Epidemiology
Pathogenesis
Clinical Features
Pathology
Differential Diagnosis
Treatment
Annular Elastolytic Giant Cell Granuloma
History
Epidemiology
Pathogenesis
Clinical Features
Pathology
Differential Diagnosis
Treatment
Necrobiosis Lipoidica
History
Epidemiology
Pathogenesis
Clinical Features
Pathology
Differential Diagnosis
Treatment
Cutaneous Crohn Disease
History
Epidemiology
Pathogenesis
Clinical Features
Pathology
Differential Diagnosis
Treatment
Foreign Body Granulomas (see Ch. 94)
Interstitial Granulomatous Dermatitis and Palisaded Neutrophilic and Granulomatous Dermatitis
Introduction
History
Pathogenesis
Clinical Features
Pathology
Differential Diagnosis
Treatment
References
Chapter 94: Foreign Body Reactions
Abstract
Keywords:
Chapter Contents
General Considerations
Definition
Routes of Entry
Accidental
Surgical procedures
Iatrogenic
Tattooing
Topical application
Self-inflicted
Pathogenesis
Clinical Features
Pathology
Diagnosis
Foreign Body Reactions to Inorganic and Metallic Compounds
Tattoo
Clinical features
Pathology
Diagnosis and differential diagnosis
Treatment
Paraffin
Clinical features
Pathology
Treatment
Silicone
Clinical features
Pathology
Treatment
Silica
Clinical features
Pathology
Differential diagnosis
Treatment
Talc
Clinical features
Pathology
Treatment
Zirconium
Beryllium
Aluminum
Zinc
Reactions to Organic and Biologic Products
Starch
Pathology
Cactus Spines
Pathology
Cnidaria (Coelenterata) – Jellyfish, Corals
Clinical features
Pathology
Treatment
Keratin
Pseudofolliculitis barbae and acne keloidalis nuchae
Treatment
Pilonidal sinus
Injectable Soft Tissue Fillers
Hyaluronic Acid
Bovine Collagen
Miscellaneous
Intralesional Corticosteroids
Sutures
Polyamide “Hair” Implants
Mesotherapy
References
Section 15: Atrophies and Disorders of Dermal Connective Tissues
Chapter 95: Biology of the Extracellular Matrix
Abstract
Keywords
Introduction
Structure and Function of the Extracellular Matrix
Collagens
Collagen triple helix
Biosynthesis of collagens
The collagen family of proteins
Collagens of the skin
Elastic Fibers
Elastin
Microfibrils
The Extrafibrillar Matrix
Glycosaminoglycans and proteoglycans
Laminins and Other Glycoproteins
Functions of the Extracellular Matrix
Structural role of the extracellular matrix
Regulation of cellular functions
Diseases Related to ECM Defects
Ehlers–Danlos syndrome
Collagens and tenascin-X
Post-translational modification of collagen
Proteoglycan processing
Cutis laxa
Marfan syndrome
Loeys–Dietz syndrome
Other fibrillin-associated syndromes
Pseudoxanthoma elasticum
Epidermolysis bullosa
Other hereditary matrix diseases with skin symptoms
Extracellular matrix components as autoantigens
Skin aging and other acquired ECM abnormalities
Animal Models
Potential for Biologically Valid Molecular Therapies
References
Chapter 96: Perforating Diseases
Abstract
Keywords:
Introduction
History
Epidemiology
Pathogenesis
Clinical Features
Reactive Perforating Collagenosis
Elastosis Perforans Serpiginosa
Acquired Perforating Dermatosis and Kyrle Disease
Perforating Calcific Elastosis
Pathology
Differential Diagnosis
Treatment
References
Chapter 97: Heritable Disorders of Connective Tissue
Abstract
Keywords
Chapter Contents
Introduction
Ehlers–Danlos Syndrome
History
Epidemiology
Pathogenesis
Clinical Features
Pathology and Laboratory Findings
Differential Diagnosis
Treatment
Pseudoxanthoma Elasticum
History
Epidemiology
Pathogenesis
Clinical Features
Pathology
Differential Diagnosis
Treatment
Cutis Laxa
History
Epidemiology
Pathogenesis
Clinical Features
Pathology
Differential Diagnosis
Treatment
References
Chapter 98: Dermal Hypertrophies
Abstract
Keywords:
Chapter Contents
Hypertrophic Scars and Keloids
Introduction
Epidemiology
Etiology
Pathogenesis
Clinical Features
Scar assessment
Pathology
Differential Diagnosis
Treatment
Dupuytren Disease
History
Epidemiology
Pathogenesis
Clinical Features
Pathology
Differential Diagnosis
Treatment
Cutis Verticis Gyrata
Clinical Features
Pathology
Differential Diagnosis
Treatment
Hyaline Fibromatosis Syndrome (Juvenile Hyaline Fibromatosis and Infantile Systemic Hyalinosis)
Introduction
History
Epidemiology
Pathogenesis
Clinical Features
Pathology
Differential Diagnosis
Treatment
Elastic Tissue-Related Disorders
References
Chapter 99: Atrophies of Connective Tissue
Abstract
Keywords:
Chapter Contents
Mid-Dermal Elastolysis
Introduction
History
Epidemiology
Pathogenesis
Clinical features
Pathology
Differential diagnosis
Treatment
Anetoderma
Introduction
History
Epidemiology
Pathogenesis
Clinical features
Pathology
Differential diagnosis
Treatment
Striae
Introduction
History
Epidemiology
Pathogenesis
Clinical features
Pathology
Differential diagnosis
Treatment
Atrophoderma of Pasini and Pierini
Introduction
History
Epidemiology
Pathogenesis
Clinical features
Pathology
Differential diagnosis
Treatment
Follicular Atrophoderma
Clinical features
Atrophoderma Vermiculatum
Bazex–Dupré–Christol Syndrome
Conradi–Hünermann–Happle Syndrome (X-Linked Dominant Chondrodysplasia Punctata, CDPX2)
Atrophia Maculosa Varioliformis Cutis
Piezogenic Pedal Papules (Piezogenic Papules)
Other Atrophies of the Connective Tissue
References
Section 16: Disorders of Subcutaneous Fat
Chapter 100: Panniculitis
Abstract
Keywords:
Chapter Contents
Introduction
Erythema Nodosum
Introduction
History
Epidemiology
Pathogenesis
Clinical features
Pathology
Differential diagnosis
Treatment
Subacute Nodular Migratory Panniculitis
Clinical features
Pathology
Treatment
Morphea/Scleroderma Panniculitis
Clinical features
Pathology
Differential diagnosis
Alpha-1 Antitrypsin Deficiency Panniculitis
Introduction
History
Epidemiology
Pathogenesis
Clinical features
Pathology
Differential diagnosis
Treatment
Erythema Induratum
Introduction
History
Epidemiology
Pathogenesis
Clinical features
Pathology
Differential diagnosis
Treatment
Pancreatic Panniculitis
Introduction
History
Epidemiology
Pathogenesis
Clinical features
Pathology
Differential diagnosis
Treatment
Sclerema Neonatorum, Subcutaneous Fat Necrosis of the Newborn, and Post-Steroid Panniculitis
Sclerema Neonatorum
History
Epidemiology
Pathogenesis
Clinical features
Pathology
Differential diagnosis
Treatment
Subcutaneous Fat Necrosis of the Newborn
Introduction
History
Epidemiology
Pathogenesis
Clinical features
Pathology
Differential diagnosis
Treatment
Post-Steroid Panniculitis
History
Epidemiology
Pathogenesis
Clinical features
Pathology
Differential diagnosis
Treatment
Lupus Erythematosus Panniculitis (Lupus Panniculitis)
History
Epidemiology
Pathogenesis
Clinical features
Pathology
Differential diagnosis
Treatment
Panniculitis of Dermatomyositis
Introduction
Clinical features
Pathology
Differential diagnosis
Treatment
Traumatic Panniculitis
Introduction
History
Epidemiology
Pathogenesis
Clinical features
Pathology
Differential diagnosis
Treatment
Lipodermatosclerosis
Introduction
History
Epidemiology
Pathogenesis
Clinical features
Pathology
Differential diagnosis
Treatment
Infection-Induced Panniculitis
Introduction
History
Epidemiology
Pathogenesis
Clinical features
Pathology
Differential diagnosis
Treatment
Cytophagic Histiocytic Panniculitis
Malignant Subcutaneous Infiltrates
Unusual or Newly Described Forms of Panniculitis
References
Chapter 101: Lipodystrophies
Abstract
Keywords:
Introduction
Pathogenesis
Congenital Generalized Lipodystrophy (Berardinelli–Seip Congenital Lipodystrophy, Berardinelli–Seip Syndrome)
Familial Partial Lipodystrophy
Acquired Generalized Lipodystrophy (Lawrence Syndrome)
Acquired Partial Lipodystrophy Syndrome (Barraquer–Simons Syndrome)
Localized Lipoatrophy
Clinical Features
Congenital Generalized Lipodystrophy (CGL)
Familial Partial Lipodystrophy
Autoinflammatory Syndromes (see Table 45.7)
Joint contractures, muscle atrophy, microcytic anemia, and panniculitis-induced lipodystrophy (JMP) syndrome
Chronic atypical neutrophilic dermatosis with lipodystrophy and elevated temperature (CANDLE) syndrome
Recurrent lipoatrophic panniculitis of children
Acquired Generalized Lipodystrophy
Acquired Partial Lipodystrophy
Localized Lipoatrophy
Lipohypertrophy
Pathology
Differential Diagnosis
Treatment
Acquired Partial Lipodystrophy
Insulin Lipodystrophy
HIV/ART-Associated Lipodystrophy
Pathogenesis
Clinical Features
Treatment
HIV/ART-associated lipoatrophy
HIV/ART-associated lipohypertrophy
Metabolic derangements
References
Section 17: Vascular Disorders
Chapter 102: Vascular Biology
Abstract
Keywords:
Chapter Contents
Structure and Function of Cutaneous Blood Vessels
Vascular Development
Regulation of Skin Angiogenesis
Regulation of Leukocyte–Endothelial Cell Interactions
Structure and Function of the Cutaneous Lymphatic Vascular System
Related Diseases
Current Trends in Antiangiogenesis
References
Chapter 103: Infantile Hemangiomas
Abstract
Keywords
Introduction
History
Epidemiology
Pathogenesis
Hemangioma Endothelial Cells: Origin, Signaling Pathways, and Genetics
Hypoxia and Other Extrinsic Factors
Factors Influencing Natural History
Clinical Features
Presentation
Natural History
Complications
Ulceration
Disfigurement and interference with function
Disfigurement and interference with function because of location
Extracutaneous involvement
Radiologic Features
Pathology
Differential Diagnosis
Treatment
Active Non-Intervention
Management of Ulceration
Local Medical Therapies
Topical β-blockers
Intralesional and topical corticosteroids
Systemic Therapies
Systemic β-blockers
Systemic corticosteroids
Other systemic therapies
Surgical and Laser Therapy
Rapidly Involuting and Non-Involuting Congenital Hemangiomas
References
Chapter 104: Vascular Malformations
Abstract
Keywords
Introduction
History
Epidemiology
Pathogenesis
Clinical Features
Capillary Malformations
Nevus simplex
Port-wine stain and variants
Sturge–Weber syndrome
Capillary malformations associated with overgrowth
Diffuse capillary malformation with overgrowth
Klippel–Trenaunay syndrome
Proteus syndrome
CLOVES syndrome
Megalencephaly–capillary malformation
CLAPO syndrome
Cutis marmorata telangiectatica congenita
Telangiectasias
Hereditary hemorrhagic telangiectasia
Ataxia–telangiectasia
Angiokeratomas
Venous Malformations
Cephalic venous malformation
Trunk and limb venous malformation
Sinusoidal hemangioma
Fibro-adipose vascular anomaly
Syndromes associated with venous malformations
Familial cutaneous and mucosal venous malformation (VMCM)
Blue rubber bleb nevus syndrome (BRBNS; Bean syndrome)
Maffucci syndrome
Glomuvenous malformation
Cerebral cavernous malformation and hyperkeratotic cutaneous capillary–venous malformation
Lymphatic Malformations
Primary lymphedema
Macrocystic lymphatic malformation (“cystic hygroma”)
Microcystic lymphatic malformation (“lymphangioma circumscriptum”)
Combined microcystic and macrocystic lymphatic malformation
Generalized lymphatic anomaly
Gorham–Stout disease
Kaposiform lymphangiomatosis
Arteriovenous Malformations
Syndromes associated with arteriovenous malformations
Cobb syndrome
Bonnet–Dechaume–Blanc syndrome (BDBS; Wyburn–Mason syndrome)
Parkes Weber syndrome
Capillary malformation–arteriovenous malformation (CM-AVM)
PTEN hamartoma tumor syndrome (PHTS)
Pathology
Capillary Malformations
Venous Malformations
Lymphatic Malformations
Arteriovenous Malformations
Differential Diagnosis
Treatment
Capillary Malformations
Venous Malformations
Lymphatic Malformations
Arteriovenous Malformations
Combined Malformations
Acknowledgment
References
Chapter 105: Ulcers
Abstract
Keywords:
Chapter Contents
Introduction
Venous Ulcers
Pathogenesis
Clinical Features
Laboratory Evaluation
Pathology
Differential Diagnosis
Treatment
Moisture and occlusion
Debridement
Wound dressings
Management of wound infection
Adjuncts to wound care
Compression
Manual lymph drainage
Topical negative pressure therapy
Skin substitutes
Topical and oral medications
Lymphedema
Arterial Ulcers
Pathogenesis
Clinical Manifestations
Laboratory Evaluation
Differential Diagnosis
Treatment
Diabetic (and Neuropathic) Ulcers
Pathogenesis
Clinical Features
Laboratory Evaluation
Treatment
Prevention
Ulcers Due to Physical Factors
Pathogenesis
Clinical Features
Pathology
Treatment
Other Causes of Skin Ulceration
Diffuse Dermal Angiomatosis
Hematologic Disorders
Tropical Ulcers
Additional Causes
References
Chapter 106: Other Vascular Disorders
Abstract
Keywords:
Chapter Contents
Introduction
Livedo Reticularis
Introduction
History
Pathogenesis
Clinical Features
Congenital livedo reticularis
Cutis marmorata telangiectatica congenita
Acquired livedo reticularis
Livedo reticularis without systemic associations
Physiologic livedo reticularis/cutis marmorata
Primary/idiopathic livedo reticularis
Livedo reticularis secondary to systemic disease
Livedo reticularis due to vasospasm
Livedo reticularis due to vessel wall pathology
Livedo reticularis due to intraluminal pathology
Other causes of livedo reticularis
Differential Diagnosis
Pathology
Treatment
Flushing
Introduction
Pathogenesis
Clinical Features
Differential Diagnosis
Treatment
Erythromelalgia
Introduction
History
Epidemiology
Pathogenesis
Clinical Features
Pathology
Differential Diagnosis
Treatment
Telangiectasias
Introduction
Spider Telangiectasia
Generalized Essential Telangiectasia
Cutaneous Collagenous Vasculopathy
Unilateral Nevoid Telangiectasia
Angioma Serpiginosum
Hereditary Hemorrhagic Telangiectasia
Ataxia–Telangiectasia
Venous Lakes
Nevus Anemicus
Angiospastic Macules (Bier Spots)
References
Section 18: Neoplasms of the Skin
Chapter 107: Principles of Tumor Biology and Pathogenesis of BCCs and SCCs
Abstract
Keywords:
Chapter Contents
Introduction
Carcinogenesis
The Cell Cycle
Cancer Genes – Oncogenes and Tumor Suppressor Genes
Apoptosis
Limitless Replicative Potential
Angiogenesis
Invasion/Metastasis
Structure and Function of p53
Background
Regulation of the TP53 Gene and p53 Protein
The Cellular Response to DNA Damage
Mutated TP53
Structure and Function of Patched
Background
PTCH1 Gene
PTCH1 Protein Product (Patched)
Normal Function of Patched
Regulation of Patched
PTCH1 Mutations
PTCH2 and SUFU Mutations
Pathogenesis of BCC
Tumor progression
Cancer
Metastasis
Pathogenesis of SCC
Precursors
Cancer
Summary
Related Diseases
Adnexal Tumors
Keratoacanthoma
Xeroderma Pigmentosum
Li–Fraumeni Syndrome
Basal Cell Nevus Syndrome
Bazex Syndrome
References
Chapter 108: Actinic Keratosis, Basal Cell Carcinoma, and Squamous Cell Carcinoma
Abstract
Keywords:
Chapter Contents
Introduction
History
Epidemiology
Pathogenesis
Risk Factors (Table 108.2)
Environmental Exposures
Ultraviolet radiation
Indoor tanning usage
Therapeutic UVR exposure
Ionizing radiation
Occupational risk factors
Chemical exposures
Human Papillomavirus Infection
Immunosuppression
Organ transplantation
Immunosuppressive drugs
HIV infection
Other Risk Factors, Including BRAF Inhibitors
Genetic Risk Factors
Genetic predisposition
Genetic syndromes associated with an increased risk of BCCs and/or SCCs
Xeroderma pigmentosum
Oculocutaneous albinism
Epidermodysplasia verruciformis
Dystrophic epidermolysis bullosa
Basal cell nevus syndrome (BCNS)
Bazex–Dupré–Christol syndrome and Rombo syndrome
Risk of Additional Cancers
Actinic Keratosis and Squamous Cell Carcinoma
Clinical Features
Actinic keratosis
Squamous cell carcinoma in situ
Invasive cutaneous squamous cell carcinoma
Keratoacanthoma
Verrucous carcinoma
Lymphoepithelioma-like carcinoma of the skin
In vivo Imaging Methods
Dermoscopy
Reflectance confocal microscopy (RCM)
Pathology
Actinic keratosis
Squamous cell carcinoma in situ
Invasive squamous cell carcinoma
Keratoacanthoma
Verrucous carcinoma
Histopathologic simulators of SCC
Basal Cell Carcinoma
Clinical Features
Nodular basal cell carcinoma
Superficial basal cell carcinoma
Morpheaform basal cell carcinoma
Fibroepithelial basal cell carcinoma (fibroepithelioma of Pinkus)
Additional histopathologic subtypes of BCC
Basosquamous carcinoma
Micronodular basal cell carcinoma
In vivo Imaging Methods
Dermoscopy
Reflectance confocal microscopy (RCM)
Pathology
Histopathologic simulators of BCC
Treatment
Evaluation and Risk Assessment
Surgical and Destructive Procedures
Standard excision
Curettage with electrodesiccation
Curettage alone
Mohs micrographic surgery
Radiation therapy
Cryosurgery
Photodynamic therapy
Laser
Medical Treatment
Combination therapy
Metastatic NMSC
Prophylaxis
Reduction of immunosuppression in high-risk SCC
Prevention and Early Detection
References
Chapter 109: Benign Epidermal Tumors and Proliferations
Abstract
Keywords:
Chapters Contents
Solar Lentigo
Epidemiology
Pathogenesis
Clinical Features
Associated Diseases and Special Forms
Pathology
Differential Diagnosis
Treatment
Seborrheic Keratosis
Introduction
History
Epidemiology
Pathogenesis
Clinical Features
Seborrheic Keratosis and Malignancy
Pathology
Differential Diagnosis
Treatment
Lichenoid Keratosis
History
Epidemiology
Pathogenesis
Clinical Features
Pathology
Differential Diagnosis
Treatment
Dermatosis Papulosa Nigra
Introduction
History
Epidemiology
Pathogenesis
Clinical Features
Pathology
Differential Diagnosis
Treatment
Stucco Keratosis
Introduction
History
Epidemiology
Pathogenesis
Clinical Features
Pathology
Differential Diagnosis
Treatment
Porokeratosis
Introduction
History
Epidemiology
Pathogenesis
Clinical Features
Pathology
Differential Diagnosis
Treatment
Flegel Disease
Introduction
Epidemiology
Pathogenesis
Clinical Features
Pathology
Differential Diagnosis
Treatment
Acrokeratosis Verruciformis
Clinical Features
Pathology
Differential Diagnosis
Treatment
Cutaneous Horn
Clinical Features
Pathology
Treatment
Clear Cell Acanthoma
Introduction
Epidemiology
Pathogenesis
Clinical Features
Pathology
Differential Diagnosis
Treatment
Inverted Follicular Keratosis
History
Epidemiology
Pathogenesis
Clinical Features
Pathology
Differential Diagnosis
Warty Dyskeratoma
Introduction
History
Epidemiology
Pathogenesis
Clinical Features
Pathology
Differential Diagnosis
Treatment
Acantholytic (Dyskeratotic) Acanthoma
Epidermolytic Acanthoma
Epidemiology
Pathogenesis
Clinical Features
Pathology
Differential Diagnosis
Treatment
Large Cell Acanthoma
Introduction
History
Epidemiology
Pathogenesis
Clinical Features
Pathology
Differential Diagnosis
Treatment
Epidermal Nevus
Introduction
Epidemiology
Pathogenesis
Clinical Features
Pathology
Differential Diagnosis
Treatment
Inflammatory Linear Verrucous Epidermal Nevus
Introduction
History
Pathogenesis
Clinical Features
Pathology
Differential Diagnosis
Treatment
Nevus Comedonicus
Introduction
History
Epidemiology
Pathogenesis
Clinical Features
Pathology
Differential Diagnosis
Treatment
Acanthosis Nigricans
Nevoid Hyperkeratosis of the Nipple and Areola
Confluent and Reticulated Papillomatosis
History
Epidemiology
Pathogenesis
Clinical Features
Pathology
Differential Diagnosis
Treatment
Clear Cell Papulosis
Epidemiology
Pathogenesis
Clinical Features
Pathology
Differential Diagnosis
Treatment
Acknowledgment
References
Chapter 110: Cysts
Abstract
Keywords:
Chapter Contents
Introduction
Cysts With a Lining of Stratified Squamous Epithelium
Epidermoid Cyst
Pathology
Treatment
Dilated Pore of Winer
Pathology
Differential diagnosis
Treatment
Pilar Sheath Acanthoma
Treatment
Milium
Pathology
Treatment
Tricholemmal Cyst
Pathology
Treatment
Proliferating Tricholemmal Cyst
Pathology
Treatment
Proliferating Epidermoid Cyst
Pathology
Treatment
Vellus Hair Cysts
Pathology
Treatment
Steatocystoma
Pathology
Treatment
Cutaneous Keratocyst
Pathology
Follicular Hybrid Cyst
Pigmented Follicular Cyst
Dermoid Cyst
Pathology
Treatment
Ear Pit
Pathology
Treatment
Pilonidal Cyst
Pathology
Treatment
Cysts Lined With Non-Stratified Squamous Epithelium
Hidrocystoma
Pathology
Treatment
Bronchogenic Cyst
Pathology
Treatment
Thyroglossal Duct Cyst
Pathology
Treatment
Branchial Cleft Cyst
Pathology
Treatment
Cutaneous Ciliated Cyst and Ciliated Cyst of the Vulva
Pathology
Treatment
Median Raphe Cyst
Pathology
Treatment
Omphalomesenteric Duct Cyst
Pathology
Differential diagnosis
Treatment
Urachal Cyst
Pathology
Treatment
Cysts Without an Epithelial Lining
Mucocele
Pathology
Treatment
Digital Mucous Cyst (Pseudocyst)
Pathology
Treatment
Ganglion
Pathology
Treatment
Pseudocyst of the Auricle
Pathology
Treatment
Cutaneous Metaplastic Synovial Cyst (Pseudocyst)
Pathology
Treatment
References
Chapter 111: Adnexal Neoplasms
Abstract
Keywords:
Chapter Contents
Neoplasms and Proliferations with Follicular Differentiation
Follicular and Folliculosebaceous-Apocrine Hamartomas
Hair follicle nevus
Introduction
Clinical features
Pathology
Treatment
Trichofolliculoma
Introduction
Clinical features
Pathology
Treatment
Fibrofolliculoma, perifollicular fibroma, and trichodiscoma
Introduction
Clinical features
Pathology
Treatment
Nevus sebaceus
Introduction
Clinical features
Pathology
Treatment
Mixed tumor (chondroid syringoma)
Introduction
Clinical features
Pathology
Treatment
Neoplasms and Proliferations With Follicular Germinative Differentiation
Trichoepithelioma/trichoblastoma
Introduction
Clinical features
Pathology
Treatment
Desmoplastic trichoblastoma (desmoplastic trichoepithelioma)
Introduction
Clinical features
Pathology
Treatment
Neoplasms and Proliferations With Matrical Differentiation
Pilomatricoma
Introduction
Clinical features
Pathology
Treatment
Pilomatrical carcinoma
Introduction
Clinical features
Pathology
Treatment
Neoplasms and Proliferations With Follicular Sheath (Tricholemmal) Differentiation
Tricholemmoma
Introduction
Clinical features
Pathology
Treatment
Tricholemmal (trichilemmal) carcinoma
Treatment
Neoplasms and Proliferations With Superficial Follicular (Infundibular and Isthmic) Differentiation
Tumor of follicular infundibulum (infundibuloma; isthmicoma)
Introduction
Clinical features
Pathology
Treatment
Trichoadenoma (trichoadenoma of Nikolowski)
Introduction
Clinical features
Pathology
Treatment
Proliferating pilar tumor (proliferating follicular-cystic neoplasm)
Introduction
Clinical features
Pathology
Treatment
Neoplasms and Proliferations With Sebaceous Differentiation
Sebaceous gland hyperplasia
Introduction
Clinical features
Pathology
Treatment
Sebaceous adenoma, sebaceoma, and sebaceous epithelioma
Introduction
Clinical features
Pathology
Treatment
Sebaceous carcinoma
Introduction
Clinical features
Pathology
Treatment
Neoplasms and Proliferations With Apocrine (or Eccrine) Differentiation
Benign Neoplasms and Proliferations With Apocrine (or Eccrine) Ductal and Tubular Differentiation
Syringoma
Introduction
Clinical features
Pathology
Treatment
Poroma
Introduction
Clinical features
Pathology
Treatment
Hidradenoma
Introduction
Clinical features
Pathology
Treatment
Benign Neoplasms With Apocrine Differentiation
Apocrine adenoma
Introduction
Clinical features
Pathology
Treatment
Undifferentiated Neoplasms of Apocrine Lineage
Spiradenoma
Definition
Clinical features
Pathology
Treatment
Cylindroma
Introduction
Clinical features
Pathology
Treatment
Carcinomas of apocrine lineage
Introduction
Clinical features
Pathology
Treatment
Neoplasms and Proliferations With Eccrine Differentiation
Eccrine nevus (hamartoma)
Treatment
Syringoma, poroma, hidradenoma, adnexal adenocarcinoma
Syringofibroadenoma
Papillary adenoma and adenocarcinoma
Introduction
Clinical features
Pathology
Treatment
References
Chapter 112: Benign Melanocytic Neoplasms
Abstract
Keywords:
Chapter Contents
Ephelides
Epidemiology and Pathogenesis
Clinical Features
Pathology
Differential Diagnosis
Treatment
Café-Au-Lait Macules
Epidemiology
Pathogenesis
Clinical Features
Pathology
Differential Diagnosis
Treatment
Becker Melanosis (Nevus)
Epidemiology
Pathogenesis
Clinical Features
Pathology
Differential Diagnosis
Treatment
Solar Lentigines
Lentigo Simplex and Mucosal Melanotic Lesions
Epidemiology
Pathogenesis
Clinical Features
Special forms and associated syndromes
Pathology
Differential Diagnosis
Treatment
Dermal Melanocytosis
Epidemiology
Pathogenesis
Clinical Features
Pathology
Differential Diagnosis
Treatment
Nevus of Ota and Related Conditions
Nevus of Ota
Epidemiology
Pathogenesis
Clinical features
Related conditions
Pathology
Differential diagnosis
Treatment
Melanocytic Nevi
Blue Nevus and Its Variants
Epidemiology
Pathogenesis
Clinical Features
Common blue nevi
Cellular blue nevi
Epithelioid blue nevi
Pigmented epithelioid melanocytoma
Malignant blue nevi (cutaneous melanoma arising in or having features of blue nevus)
Pathology
Differential Diagnosis
Treatment
Common Acquired Melanocytic Nevi
Epidemiology
Pathogenesis
Clinical Features
Melanocytic nevi associated with epidermolysis bullosa
Melanocytic nevi associated with lichen sclerosus
Pathology
Differential Diagnosis
Treatment
Melanocytic Nevi of Genital Skin and Other “Special Sites”
Clinical Features
Pathology
Differential Diagnosis
Melanocytic Nevus of Acral Skin
Clinical Features
Pathology
Spitz (Spindle and Epithelioid Cell) Nevus/Tumor
Epidemiology
Pathogenesis
Clinical Features
Pathology
Differential Diagnosis
Treatment
Pigmented Spindle Cell Nevus
Epidemiology
Pathogenesis
Clinical Features
Pathology
Differential Diagnosis
Treatment
Other Melanocytic Nevi With Spindle Cells
Atypical (Dysplastic) Melanocytic Nevus
History
Epidemiology
Clinical Features
Pathology
Differential Diagnosis
Treatment
Congenital Melanocytic Nevus
Introduction
Epidemiology
Pathogenesis
Clinical Features
Neurocutaneous melanosis (melanocytosis)
Melanoma
Additional associated abnormalities
Pathology
Differential Diagnosis
Treatment
Nevus Spilus
Epidemiology
Pathogenesis
Clinical Features
Pathology
Differential Diagnosis
Treatment
Halo Nevus
Epidemiology
Pathogenesis
Clinical Features
Pathology
Differential Diagnosis
Treatment
Combined Nevus
Introduction and Epidemiology
Clinical Features
Pathology
Differential Diagnosis and Treatment
Recurrent Melanocytic Nevus
Epidemiology
Pathogenesis
Clinical Features
Pathology
Differential Diagnosis
Treatment
References
Chapter 113: Melanoma
Abstract
Keywords:
Chapter Contents
Introduction
Molecular Pathogenesis
Cellular Signaling Pathways in Melanoma
MAPK signaling
PI3K signaling
WNT signaling
MC1R–MITF signaling
Host Immune Response to Melanoma
Epidemiology
Risk Factors for Cutaneous Melanoma
Genetic Risk Factors
Phenotypic Risk Factors Reflecting Gene/Environment Interactions
Common melanocytic nevi
Atypical melanocytic nevi
Ephelides and solar lentigines
Environmental Risk Factors
Ultraviolet radiation
Sun protection
Types of Primary Melanomas
Superficial Spreading Melanoma
Nodular Melanoma
Lentigo Maligna Melanoma
Acral Lentiginous Melanoma
Other Melanoma Variants
Amelanotic Melanomas
Melanoma With Features of a Spitz Nevus (“Spitzoid” Melanoma)
Desmoplastic Melanoma
Clear Cell Sarcoma: Melanoma of Soft Parts
Malignant Blue Nevus
Ocular Melanoma
Mucosal Melanoma
Melanoma and Pregnancy
Childhood Melanoma
Diagnosis
Differential Diagnosis
Dermoscopy
Photography
Reflectance Confocal Microscopy (RCM)
Histopathology
Microstaging
Immunohistopathology
Molecular Analysis
Staging
Prognosis
Evaluation of a Patient With Suspected Melanoma
Medical History
Skin Investigation and Clinical Diagnosis
Laboratory Investigations and Imaging
Management
Management of the Primary Melanoma (Stage I and II)
Local Recurrences
Management of Regional Metastatic Melanoma (Stage III)
Elective lymph node dissection and sentinel lymph node biopsy
Skin satellite and in-transit metastases
Clinically identified lymph node metastases
Adjuvant therapy
Management of Distant Metastases (Stage IV)
Surgery
Radiation therapy
Systemic therapy
Molecularly targeted therapy
Immunotherapy
Immune checkpoint blockade
Cytotoxic T lymphocyte-associated antigen-4 (CTLA-4) blockade
Blockade of programmed cell death 1 (PD-1) and its ligand (PD-L1)
High-dose interleukin-2 treatment
Cancer vaccines
Intralesional oncolytic virus therapy
Adoptive cell therapy
Chemotherapy
Melanoma Surveillance
References
Chapter 114: Vascular Neoplasms and Neoplastic-Like Proliferations
Abstract
Keywords:
Chapter Contents
Introduction
Benign Vascular Neoplasms and Reactive Hyperplasias
Intravascular Papillary Endothelial Hyperplasia (PEH)
Introduction
Epidemiology
Pathogenesis
Clinical features
Pathology
Differential diagnosis
Treatment
Reactive Angioendotheliomatosis
Introduction
Epidemiology
Pathogenesis
Clinical features
Pathology
Differential diagnosis
Treatment
Angiokeratomas
Introduction
Clinical features
Solitary or multiple angiokeratomas
Angiokeratomas of the scrotum and vulva
Angiokeratoma corporis diffusum
Angiokeratoma of Mibelli
Angiokeratoma circumscriptum
Pathology
Differential diagnosis
Treatment
Targetoid Hemosiderotic Lymphatic Malformation (Hobnail “Hemangioma”)
Introduction and history
Epidemiology
Pathogenesis
Clinical features
Pathology
Differential diagnosis
Treatment
Verrucous Venulocapillary Malformation (Verrucous “Hemangioma”)
Introduction and history
Epidemiology
Pathogenesis
Clinical features
Pathology
Differential diagnosis and treatment
Pyogenic Granuloma
Introduction and history
Epidemiology
Pathogenesis
Clinical features
Pathology
Differential diagnosis
Treatment
Cherry Angioma
Introduction and history
Epidemiology
Pathogenesis
Clinical features
Pathology
Differential diagnosis
Treatment
Tufted Angioma
Introduction
History
Epidemiology
Pathogenesis
Clinical features
Pathology
Differential diagnosis
Treatment
Glomeruloid Hemangioma
Introduction and history
Clinical features
Pathogenesis
Pathology
Differential diagnosis
Treatment
Microvenular Hemangioma
Introduction and history
Epidemiology
Pathogenesis
Clinical features
Pathology
Differential diagnosis
Treatment
Epithelioid Hemangioma
Introduction and history
Epidemiology
Pathogenesis
Clinical features
Pathology
Differential diagnosis
Treatment
Multifocal Lymphangioendotheliomatosis With Thrombocytopenia
Introduction and history
Epidemiology
Pathogenesis
Clinical features
Pathology
Differential diagnosis
Treatment
Sinusoidal Hemangioma
Introduction and history
Epidemiology
Pathogenesis
Clinical features
Pathology
Differential diagnosis
Treatment
Spindle Cell Hemangioma
Introduction and history
Epidemiology
Pathogenesis
Clinical features
Pathology
Differential diagnosis
Treatment
Borderline and Low-Grade Malignant Vascular Neoplasms
Kaposiform Hemangioendothelioma
Introduction and history
Epidemiology
Pathogenesis
Clinical features
Pathology
Differential diagnosis
Treatment
Papillary Intralymphatic Angioendothelioma (PILA)
Introduction and history
Epidemiology
Clinical features
Pathology
Differential diagnosis
Treatment
Retiform Hemangioendothelioma (RHE)
Introduction and history
Epidemiology
Pathogenesis
Clinical features
Pathology
Differential diagnosis
Treatment
Kaposi Sarcoma
Introduction and history
Epidemiology
Pathogenesis
Clinical features
Pathology
Differential diagnosis
Treatment
Malignant Vascular Neoplasms
Epithelioid Hemangioendothelioma
Introduction and history
Epidemiology
Pathogenesis
Clinical features
Pathology
Differential diagnosis
Treatment
Angiosarcoma
Introduction and history
Epidemiology
Pathogenesis
Clinical features
Pathology
Differential diagnosis
Treatment
Perivascular Neoplasms and Neoplastic-Like Proliferations
Glomus Tumors and Glomuvenous Malformations
Introduction
Epidemiology
Pathogenesis
Clinical features
Pathology
Differential diagnosis
Treatment
Infantile Hemangiopericytoma
Introduction and history
Epidemiology
Pathogenesis
Clinical features
Pathology
Differential diagnosis
Treatment
References
Chapter 115: Neural and Neuroendocrine Neoplasms (Other than Neurofibromatosis)
Abstract
Keywords:
Chapter Contents
Classification, Terminology, and Histogenesis
Neuromas
Introduction
History
Epidemiology
Pathogenesis
Clinical Features
Pathology
Differential Diagnosis
Treatment
Schwannoma
Introduction
History
Epidemiology
Pathogenesis
Clinical Features
Pathology
Differential Diagnosis
Treatment
Neurofibroma
Introduction
History
Epidemiology
Pathogenesis
Clinical Features
Pathology
Differential Diagnosis
Treatment
Nerve Sheath Myxoma and Cellular Neurothekeoma
Introduction
History
Epidemiology
Pathogenesis
Clinical Features
Pathology
Differential Diagnosis
Treatment
Granular Cell Tumor
Introduction
History
Epidemiology
Pathogenesis
Clinical Features
Pathology
Differential Diagnosis
Treatment
Perineurioma
Introduction
Malignant Peripheral Nerve Sheath Tumor
Merkel Cell Carcinoma
Introduction
History
Epidemiology
Pathogenesis
Clinical Features
Pathology
Differential Diagnosis
Treatment
Heterotopic Neural Tissue of the Skin
Heterotopic Neuroglial Tissue
History
Epidemiology
Pathogenesis
Clinical features
Pathology
Differential diagnosis
Treatment
Heterotopic Meningeal Tissue
History
Epidemiology
Pathogenesis
Clinical features
Pathology
Differential diagnosis
Treatment
Primitive Neuroectodermal Tumors
Introduction
History
Epidemiology
Pathogenesis
Clinical Features
Pathology
Differential Diagnosis
Treatment
References
Chapter 116: Fibrous and Fibrohistiocytic Proliferations of the Skin and Tendons
Abstract
Keywords:
Chapter Contents
Skin Tags
Clinical Features
Epidemiology
Pathology
Treatment
Cutaneous Angiofibroma
Clinical Features
Pathology
Dermatofibroma
Clinical Features
Pathology
Treatment
Variants of Dermatofibroma
Acral Fibrokeratoma
Clinical Features
Pathology
Superficial Acral Fibromyxoma
Clinical Features
Pathology
Treatment
Sclerotic Fibroma of the Skin
Clinical Features
Pathology
Pleomorphic Fibroma of the Skin
Clinical Features
Pathology
Multinucleate Cell Angiohistiocytoma
Clinical Features
Pathology
Treatment
Dermatomyofibroma
Clinical Features
Pathology
Treatment
Giant Cell Tumor of Tendon Sheath
Clinical Features
Pathology
Treatment
Fibroma of Tendon Sheath
Clinical Features
Pathology
Treatment
Nodular Fasciitis
Clinical Features
Pathology
Treatment
Connective Tissue Nevus
Clinical Features
Pathology
Clinicopathologic Variants
Differential Diagnosis
Infantile Digital Fibroma
Clinical Features
Pathology
Treatment
Infantile Myofibromatosis
Clinical Features
Pathology
Treatment
Cutaneous Adult Myofibroma
Clinical Features
Pathology
Treatment
Calcifying Aponeurotic Fibroma
Clinical Features
Pathology
Treatment
Fibrous Hamartoma of Infancy
Clinical Features
Pathology
Treatment
Fibromatoses
Clinical Features
Pathology
Treatment
Plexiform Fibrohistiocytic Tumor
Clinical Features
Pathology
Treatment
Atypical Fibroxanthoma
Clinical Features
Pathology
Treatment
Dermatofibrosarcoma Protuberans
Clinical Features
Pathology
Treatment
Giant Cell Fibroblastoma
Clinical Features
Pathology
Treatment
Fibrosarcoma
Clinical Features
Pathology
Treatment
Epithelioid Sarcoma
Clinical Features
Pathology
Treatment
References
E-References
Chapter 117: Smooth Muscle, Adipose and Cartilage Neoplasms
Abstract
Keywords
Chapter Contents
Introduction
Tumors of Smooth Muscle
Leiomyoma
Introduction
History
Epidemiology
Pathogenesis
Clinical features
Pathology
Differential diagnosis
Treatment
Leiomyosarcoma
Introduction
Epidemiology
Pathogenesis
Clinical features
Pathology
Differential diagnosis
Treatment
Smooth Muscle Hamartoma
Introduction
History
Epidemiology
Clinical features
Pathology
Differential diagnosis
Treatment
Tumors of Fat
Lipoma
Introduction
Epidemiology
Pathogenesis
Clinical features
Pathology
Differential diagnosis
Treatment
Angiolipoma
Introduction
Epidemiology
Pathogenesis
Clinical features
Pathology
Differential diagnosis
Treatment
Spindle Cell/Pleomorphic Lipoma
Introduction
History
Epidemiology
Pathogenesis
Clinical features
Pathology
Differential diagnosis
Treatment
Hibernoma
Introduction
History
Epidemiology
Pathogenesis
Clinical features
Pathology
Differential diagnosis
Treatment
Nevus Lipomatosus Superficialis
Introduction
History
Epidemiology
Pathogenesis
Clinical features
Pathology
Differential diagnosis
Treatment
Lipoblastoma/Lipoblastomatosis
Introduction
History
Epidemiology
Pathogenesis
Clinical features
Pathology
Differential diagnosis
Treatment
Liposarcoma/Atypical Lipomatous Tumor
Introduction
Epidemiology
Pathogenesis
Clinical features
Pathology
Differential diagnosis
Treatment
Tumors of Cartilage
Extraskeletal Chondroma
Introduction
Epidemiology
Clinical features
Pathology
Differential diagnosis
Treatment
Acknowledgment
References
Chapter 118: Mastocytosis
Abstract
Keywords:
Introduction
History
Epidemiology
Pathogenesis
Clinical Features
Signs and Symptoms
Cutaneous Lesions
Systemic Manifestations
Classification of Mastocytosis
Pathology
Direct Studies
Indirect Studies
Differential Diagnosis
Treatment
References
Chapter 119: B-Cell Lymphomas of the Skin
Abstract
Keywords:
Introduction
History
Epidemiology
Etiology and Pathogenesis
Clinical Features
Primary Cutaneous Follicle Center Lymphoma
Primary Cutaneous Marginal Zone B-Cell Lymphoma (Extranodal Marginal Zone Lymphoma of the Mucosa-Associated Lymphoid Tissue - MALT Lymphoma)
Primary Cutaneous Diffuse Large B-Cell Lymphoma, Leg Type
Intravascular Diffuse Large B-Cell Lymphoma
Precursor B Lymphoblastic Lymphoma/Leukemia
Other Cutaneous B-Cell Lymphomas
Pathology
Primary Cutaneous Follicle Center Lymphoma
Primary Cutaneous Marginal Zone B-Cell Lymphoma (Extranodal Marginal Zone Lymphoma of the Mucosa-Associated Lymphoid Tissue – MALT Lymphoma)
Primary Cutaneous Diffuse Large B-Cell Lymphoma, Leg Type
Intravascular Diffuse Large B-Cell Lymphoma
Precursor B Lymphoblastic Lymphoma/Leukemia
Other Cutaneous B-Cell Lymphomas
Differential Diagnosis
Treatment
Plasma Cell Dyscrasias, Including Multiple Myeloma
Histopathology
Differential Diagnosis
Cutaneous and Systemic Plasmacytosis
References
Chapter 120: Cutaneous T-Cell Lymphoma
Abstract
Keywords:
Chapter Contents
Introduction
History
The CTCL concept
The concept of primary cutaneous lymphomas
EORTC, WHO and WHO-EORTC classification schemes
Practical Guidelines for Diagnosis, Classification and Staging of CTCL
Diagnosis
Immunophenotyping
T-cell receptor gene rearrangement analysis
Classification
Practical guidelines
Staging
Mycosis Fungoides
Definition
Epidemiology
Pathogenesis
Genetic factors
Environmental factors
Immunologic factors
Clinical features
Pathology
Immunophenotype
Differential diagnosis
Staging systems and staging procedures
Treatment
Skin-directed therapies
Topical corticosteroids
Topical chemotherapy
Radiotherapy
Phototherapy
Systemic therapies (other than chemotherapy)
Interferons
Retinoids
Denileukin diftitox
Histone deacetylase inhibitors
Systemic chemotherapy
Prognosis
Variants of Mycosis Fungoides
Folliculotropic MF
Definition
Epidemiology
Clinical features
Pathology
Differential diagnosis
Treatment
Pagetoid Reticulosis
Definition
Epidemiology
Clinical features
Pathology
Immunophenotype
Differential diagnosis
Treatment
Granulomatous Slack Skin
Definition
Epidemiology
Clinical features
Pathology
Treatment
Sézary Syndrome
Definition
Epidemiology
Clinical features
Pathology
Pathogenesis
Differential diagnosis
Treatment
Adult T-Cell Leukemia/Lymphoma
Definition
Epidemiology
Clinical features
Pathology
Differential diagnosis
Treatment
Primary Cutaneous CD30-Positive Lymphoproliferative Disorders
Primary Cutaneous Anaplastic Large Cell Lymphoma
Definition
Epidemiology
Clinical features
Pathology
Immunophenotype
Genetic features
Treatment
Lymphomatoid Papulosis
Definition
Pathogenesis
Epidemiology
Clinical features
Pathology
Differential diagnosis
Treatment
Subcutaneous Panniculitis-Like T-Cell Lymphoma
Definition
Epidemiology
Clinical features
Pathology
Immunophenotype
Treatment
Extranodal NK/T-Cell Lymphoma, Nasal Type
Definition
Epidemiology
Clinical features
Pathology
Immunophenotype
Treatment
Primary Cutaneous CD8-Positive Aggressive Epidermotropic Cytotoxic T-Cell Lymphoma
Primary Cutaneous Gamma/Delta T-Cell Lymphoma
Primary Cutaneous CD4-Positive Small/Medium T-Cell Lymphoproliferative Disorder
Primary Cutaneous Peripheral T-Cell Lymphoma, NOS
References
Chapter 121: Other Lymphoproliferative and Myeloproliferative Diseases
Abstract
Keywords:
Chapter Contents
Benign Lymphocytic Infiltrates
Lymphocytic Infiltrate of Jessner
History
Epidemiology
Pathogenesis
Clinical features
Pathology
Differential diagnosis
Treatment
Cutaneous Lymphoid Hyperplasia (Pseudolymphoma of the Skin)
History
Epidemiology
Pathogenesis
Clinical features
Pathology
Differential diagnosis
Treatment
Extramedullary Hematopoiesis
Epidemiology
Pathogenesis
Clinical Features
Pathology
Differential Diagnosis
Treatment
Malignant Hematopoietic Infiltrates
Leukemia Cutis
Epidemiology
Pathogenesis
Clinical features
Pathology
Differential diagnosis
Treatment
Cutaneous Hodgkin Lymphoma
History
Epidemiology
Pathogenesis
Clinical features
Pathology
Differential diagnosis
Treatment
Blastic Plasmacytoid Dendritic Cell Neoplasm
History and epidemiology
Pathogenesis
Clinical features
Pathology
Differential diagnosis
Treatment
Angioimmunoblastic T-cell Lymphoma
History
Epidemiology
Pathogenesis
Clinical features
Pathology
Differential diagnosis
Treatment
Lymphomatoid Granulomatosis
History
Epidemiology
Pathogenesis
Clinical features
Pathology
Differential diagnosis
Treatment
References
Chapter 122: Cutaneous Metastases
Abstract
Keywords:
Introduction
Epidemiology
Pathogenesis
Clinical Features
Pathology
Treatment and Prognosis
References
Section 19: Medical Therapy
Chapter 123: Public Health and Dermatology
Abstract
Keywords:
Introduction
The Public Health Importance of Dermatology
Role of Epidemiology in Dermatology
Observational Studies
Descriptive Studies
Using Epidemiology to Identify the Cause of Disease
Case–control study
Cohort study
Cross-sectional study
Assessing the Efficacy of a Preventive or Therapeutic Intervention
Clinical Trials
Systematic Reviews
Genetic Epidemiology
Health Services Research
Health Policy Implications of Research
Quality-of-Life Measures
Important Concepts When Designing and Reviewing a Study
Research Question and Design
Methods
Results
Conclusions
Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) and the Consolidated Standards for Reporting Trials (CONSORT)
Opportunities for Research in Dermato-Epidemiology
Acknowledgment
References
Chapter 124: Skin Barrier and Transdermal Drug Delivery
Abstract
Keywords:
124-1 Skin Barrier
Chapter Contents
Stratum Corneum Structure and Organization
Epidermal Metabolism and the Skin Barrier
Biosynthetic Activities
Lamellar Body Secretion
Extracellular Processing
Acidification
Impaired Skin Barrier and Cutaneous Inflammation
References
124-2 Transdermal Drug Delivery
Chapter Contents
Parameters Affecting Skin Permeability
Parameters Controlling Absorption
Role of the Vehicle
Drug Concentration
Partition Coefficient
Regional Variation
Strategies to Enhance Transdermal Drug Delivery
Chemical Enhancement
Biochemical Enhancement
Physical Enhancement
References
Chapter 125: Glucocorticoids
Abstract
Keywords:
Introduction
Pharmacology and Mechanism of Action
Structure and Metabolism
Absorption and Distribution
The Hypothalamic–Pituitary–Adrenal (HPA) Axis
Molecular Mechanisms
Clinical Indications, Dosages and Contraindications
Oral Therapy
Intramuscular Therapy
Intravenous and Pulse Therapy
Topical Therapy
Intralesional Therapy
Contraindications
Major Side Effects
Osteoporosis
Osteonecrosis
Growth Retardation
Myopathy
Cataracts
Metabolic Effects
Cardiovascular Effects
Gastrointestinal Effects
Infection
Obstetric and Gynecologic Effects
Nervous System Effects
Cutaneous Effects
HPA Axis Suppression
Interactions and Dose Alterations
Acknowledgment
References
Appendix:
Chapter 126: Retinoids
Abstract
Keywords:
Introduction
Mechanism of Action
Vitamin A Metabolism
Retinoid Receptors
Retinoids in the Skin
Synthetic Retinoids
Adapalene
Tazarotene
Acitretin
Isotretinoin (13-cis-retinoic acid)
Bexarotene
Alitretinoin (9-cis-retinoic acid)
Retinoic acid metabolism blocking agents
Indications (Table 126.3)
Topical Retinoids
Acne
Psoriasis
Photoaging
Other indications
Systemic Retinoids
Psoriasis
Acne
Cutaneous T-cell lymphoma
Chronic hand eczema
Other “off-label” clinical uses
Ichthyosis
Darier disease
Pityriasis rubra pilaris
Rosacea
Premalignant and malignant skin lesions
Lupus erythematosus
Dosage
Contraindications
Topical Retinoids
Systemic Retinoids
Major Side Effects
Topical Retinoids
Systemic Retinoids
Teratogenicity
Skin and mucous membrane adverse effects
Systemic toxic effects
Bone toxicity
Muscle effects
Central nervous system and psychiatric effects
Ophthalmologic side effects
Other systemic effects
Hypothyroidism
Gastrointestinal side effects
Renal effects
Laboratory abnormalities
Dyslipidemia
Liver toxicity
Hematologic toxicities
Summary
Interactions
Use in Pregnancy and Lactation
References
Chapter 127: Antimicrobial Drugs
Abstract
Keywords:
Antibacterial Agents
Introduction
Topical Antibacterial Agents
Introduction
Topical antibacterial agents used to treat acne vulgaris and rosacea
Mechanisms of action
Indications
Dosages
Contraindications
Major side effects
Interactions
Pregnancy and lactation
Topical antibacterial agents used to treat superficial infections
Mechanisms of action
Indications
Dosages
Contraindications
Major side effects
Interactions
Pregnancy and lactation
Other topical antibacterial agents
Topical tetracyclines
Systemic Antibacterial Agents
Penicillins
Mechanism of action
Indications
Dosages
Contraindications
Major side effects
Interactions
Pregnancy and lactation
Cephalosporins
Mechanism of action
Indications
Dosages
Contraindications
Major side effects
Interactions
Pregnancy and lactation
Sulfonamides and co-trimoxazole
Mechanism of action
Indications
Dosages
Contraindications
Major side effects
Interactions
Pregnancy and lactation
Macrolides
Mechanism of action
Indications
Dosages
Contraindications
Major side effects
Interactions
Pregnancy and lactation
Tetracyclines
Mechanism of action
Indications
Dosages
Contraindications
Major side effects
Interactions
Pregnancy and lactation
Clindamycin
Mechanism of action
Indications
Dosages
Contraindications
Major side effects
Interactions
Pregnancy and lactation
Quinolones
Mechanism of action
Indications
Dosages
Contraindications
Major side effects
Interactions
Pregnancy and lactation
Metronidazole
Mechanism of action
Indications
Dosages
Contraindications
Major side effects
Interactions
Pregnancy and lactation
Other antibacterial agents used in Gram-positive skin infections
Dapsone
Antifungal Agents
Mechanisms of action
Indications
Dosages
Contraindications
Major side effects
Interactions
Pregnancy and lactation
Antiviral Agents
Mechanisms of action
Indications
Dosages
Contraindications
Major side effects
Interactions
Pregnancy and lactation
Other antiviral agents
References
Chapter 128: Systemic Immunomodulators
Abstract
Keywords
Chapter Contents
Interferons
Introduction
Pharmacology and Mechanism of Action
Indications, Off-Label Uses, and Dosages (Table 128.3)
Contraindications
Major Side Effects
Cutaneous reactions
Flu-like symptoms
Neurologic and psychiatric effects
Cardiovascular effects
Rhabdomyolysis
Gastrointestinal effects and bone marrow suppression
Other adverse effects
Interactions
Use in Pregnancy
Granulocyte–Macrophage and Granulocyte Colony-Stimulating Factors (GM-CSF and G-CSF)
Targeted Immune Modulators
Introduction
Tumor Necrosis Factor Inhibitors
Mechanism of action
Contraindications
Major side effects (Table 128.6)
Infections
Risk of malignancy
Autoimmunity
Demyelinating diseases
Congestive heart failure
Cutaneous reactions
Vaccination
Etanercept
Introduction
Indications
Dosages
Specific side effects
Interactions
Use in pregnancy
Infliximab
Introduction
Indications
Dosages
Specific side effects
Interactions
Use in pregnancy
Adalimumab
Introduction
Indications
Dosages
Side effects
Interactions
Use in pregnancy
Golimumab
Certolizumab
Interleukin-12/23 and Interleukin-23 Inhibitors
Introduction
Mechanism of action
Indications
Dosages
Contraindications
Major side effects
Interactions
Use in pregnancy
Interleukin-17 Inhibitors
Contraindications
Major side effects
Interactions
Use in pregnancy
Ixekizumab
Mechanism of action
Indications
Dosages
Secukinumab
Mechanism of action
Indications
Dosages
Brodalumab
Mechanism of action
Indications
Dosages
Additional contraindications and major side effects
Dupilumab
Introduction
Mechanism of action
Indications
Dosages
Contraindications
Major side effects
Interactions
Use in pregnancy
Interleukin-1 Inhibitors
Introduction
Contraindications
Major side effects
Interactions
Anakinra
Mechanism of action
Indications
Dosages
Additional contraindications
Additional major side effects
Use in pregnancy
Canakinumab
Mechanism of action
Indications
Dosages
Pregnancy category
Rilonacept
Mechanism of action
Indications
Dosages
Pregnancy category
Rituximab
Introduction
Mechanism of action
Indications
Dosages
Contraindications
Major side effects (see Table 128.6)
Interactions
Use in pregnancy
Omalizumab
Introduction
Mechanism of action
Indications
Dosages
Contraindications
Major side effects (see Table 128.6)
Interactions
Use in pregnancy
Janus Kinase (JAK) Inhibitors
Introduction
Mechanism of action
Dermatologic uses
Dosages
Contraindications
Major side effects
Interactions
Use in pregnancy
Targeted Immune Modulators Under Investigation and Other Targeted Therapies
Intravenous Immune Globulin (IVIg)
Introduction
Mechanism of Action
Indications
Dosages
Contraindications
Major Side Effects
Interactions
Use in Pregnancy
References
Chapter 129: Other Topical Medications
Abstract
Keywords:
Chapter Contents
Introduction
General Principles of Topical Therapy
Quantity of Application
Formulations and Vehicles
Topical Therapy During Pregnancy and Lactation
Topical Therapy in Neonates
Combination and Rotational Topical Therapy
Antipruritic Agents
Keratolytics and Humectants (See Table 129.8)
Skin-Lightening Agents
Hydroquinone
Introduction, dosages, and indications
Mechanism of action
Side effects
Use in pregnancy
Monobenzyl Ether of Hydroquinone
Mequinol
Agents That Affect Hair Growth
Minoxidil
Introduction, dosages, and indications
Mechanism of action
Side effects
Use in pregnancy
Bimatoprost
Introduction, dosages, and indications
Mechanism of action
Side effects
Use in pregnancy
Eflornithine
Immunomodulatory Agents
Imiquimod
Introduction, dosages, and indications
Mechanism of action
Side effects
Use in pregnancy
Topical Calcineurin Inhibitors (TCIs)
Introduction, dosages, and indications
Mechanism of action
Contraindications
Major side effects
Use in pregnancy
Chemotherapeutic Agents
5-Fluorouracil
Mechanism of action
Indications and dosages
Side effects
Contraindications and use in pregnancy
Mechlorethamine Hydrochloride
Introduction, dosages, and indications
Mechanism of action
Side effects
Use in pregnancy
Carmustine
Introduction, dosages, and indications
Mechanism of action
Side effects
Use in pregnancy
Vitamin D Analogues
Mechanism of action
Topical agents and their indications
Side effects
Use in pregnancy
Miscellaneous Agents
Topical Sirolimus (Rapamycin)
Introduction, dosages, and indications
Mechanism of action
Side effects
Use in pregnancy
Diclofenac Sodium
Ingenol Mebutate
Tar
Introduction and indications
Dosages
Mechanism of action
Side effects
Use in pregnancy
Anthralin
Introduction, dosages, and indications
Mechanism of action
Side effects
Use in pregnancy
Podophyllin and Podophyllotoxin
Introduction, dosages, and indications
Mechanism of action
Side effects
Use in pregnancy
Cantharidin
Introduction, dosages, and indications
Mechanism of action
Side effects
Sulfur
Introduction
Mechanism of action
Side effects
Contraindications
Use in pregnancy
Azelaic Acid
Introduction and indications
Mechanism of action
Dosages
Side effects
Use in pregnancy
Topical Immunotherapy
The Old and the New
References
Chapter 130: Other Systemic Drugs
Abstract
Keywords:
Chapter Contents
Introduction
Antimalarials
Mechanism of Action
Dosages
Major Side Effects
Indications
Contraindications
Use in Pregnancy and Lactation
Drug Interactions
Apremilast
Mechanism of Action
Dosages
Major Side Effects
Indications
Contraindications
Use in Pregnancy and Lactation
Drug Interactions
Azathioprine
Mechanism of Action
Dosages
Major Side Effects
Indications
Contraindications
Use in Pregnancy and Lactation
Drug Interactions
Bleomycin
Clofazimine
Colchicine
Cyclophosphamide
Mechanism of Action
Dosages
Major Side Effects
Indications
Contraindications
Use in Pregnancy and Lactation
Drug Interactions
Cyclosporine
Mechanism of Action
Dosages
Major Side Effects
Indications
Contraindications
Use in Pregnancy and Lactation
Drug Interactions
Dapsone
Mechanism of Action
Dosages
Major Side Effects
Indications
Contraindications
Use in Pregnancy and Lactation
Drug Interactions
Hydroxyurea
Leukotriene (LT) Inhibitors
Methotrexate
Mechanism of Action
Dosages
Major Side Effects
Drug Indications
Contraindications
Use in Pregnancy and Lactation
Drug Interactions
Mycophenolate Mofetil and Mycophenolate Sodium
Mechanism of Action
Dosages
Major Side Effects
Indications
Contraindications
Use in Pregnancy and Lactation
Drug Interactions
Saturated Solution of Potassium Iodide (SSKI)
Sirolimus (Rapamycin) and Tacrolimus
Thalidomide and Its Derivatives
Mechanism of Action
Dosages
Major Side Effects
Indications
Contraindications
Use in Pregnancy and Lactation
Drug Interactions
References
Chapter 131: Drug Interactions
Abstract
Keywords:
Chapter Contents
Introduction
Putting Interactions Into Perspective
Assessment of Risk in the Clinical Outcome of Drug Interactions
Levels of Evidence
Absorption
P-glycoprotein (PGP)
Distribution
Drug Biotransformation
Cytochrome P450 Enzymes
The Confusing World of Drug Interactions
Metabolism
Cytochrome induction
Cytochrome inhibition
How to Minimize the Risk of Drug–Drug Interactions
Allylamine Antifungals
Azole Antifungals
Azathioprine
Colchicine
Cyclosporine/Everolimus/Sirolimus/Tacrolimus
Grapefruit Juice
Herbal Remedies
HMG-CoA Reductase Inhibitors
Macrolide Antibiotics
Quinolone Antibiotics
Pimozide
Pharmacogenetics – Role of Polymorphisms
Cytochrome P450 enzymes
Other drug-metabolizing enzymes
Drug–Cytokine Interactions
Drug–HIV Interactions
Conclusion
References
Chapter 132: Sunscreens and Photoprotection
Abstract
Keywords:
Chapter Contents
Introduction and History
Sun Exposure
Sunscreens
Sunscreen Regulation
Sun Protection Factor
Testing for UVA Protection
Evolution of FDA and International Sunscreen Standards
Mechanisms of Sunscreen Action
Active Ingredients in Sunscreens
Organic (Soluble) Filters
Para-aminobenzoic acid and derivatives
Cinnamates
Salicylates
Benzophenones
Other organic filters
Inorganic (Insoluble) Filters
Other Photoprotective Agents
Sunscreen Benefits
Sunburn
Photoaging
Photoimmunologic Suppression
Keratinocyte Skin Cancer
Cutaneous Melanoma
Photosensitivity Disorders (see Ch. 87)
Sunscreen Safety
Photoprotective Clothing
Photoprotection Strategies and Sunscreen Recommendations
Special Populations
References
Chapter 133: Complementary and Alternative Medicine
Abstract
Keywords:
Chapter Contents
Introduction
Natural Products – Medical Applications
Aloe Vera
Capsaicin
Chamomile
Colloidal Oatmeal
Escharotics
Feverfew
Green Tea
Honey
Horse Chestnut Seed Extract
Indigo Naturalis
Licorice Root
Marigold
Menthol
Prebiotics and Probiotics
Tea Tree Oil
Turmeric
Vitex
Diet-Based Therapies
Traditional Chinese Medicine
Treatment of Dermatologic Diseases
Atopic dermatitis
Psoriasis
Moxibustion, Cupping and Other Treatment Modalities
Homeopathy
Aromatherapy
Mind–Body Medicine
Ayurveda
Conclusion
References
Section 20: Physical Treatment Modalities
Chapter 134: Ultraviolet Therapy
Abstract
Keywords:
Chapter Contents
Introduction
Phototherapy With UVB
Historical Aspects
Principles and Mechanisms
Action Spectrum and Radiation Sources
Treatment Protocols
Phototherapy for Psoriasis
Phototherapy for Cutaneous T-Cell Lymphoma, in Particular Mycosis Fungoides
Phototherapy for Vitiligo
Phototherapy for Atopic Dermatitis
Broadband UVB (BB-UVB) phototherapy
UVA/UVB phototherapy
Narrowband UVB (NB-UVB) phototherapy
Phototherapy for Photodermatoses
Phototherapy for Pityriasis Lichenoides and Lymphomatoid Papulosis
Phototherapy for Seborrheic Dermatitis
Phototherapy for Pruritus
Side Effects of Phototherapy With UVB
Phototherapy With the 308 nm Excimer Laser or Lamp
Phototherapy With UVA1
Side Effects of Phototherapy With UVA1
Photochemotherapy With Psoralens (PUVA)
Historical Aspects
Psoralens
Psoralen photochemistry
Action Spectrum and Light Sources
Photobiologic Effects of PUVA
Treatment Protocols
Oral PUVA
Bath PUVA
Topical PUVA
Initial Treatment (Clearing) Phase
Maintenance Phase
PUVA for Psoriasis
Combination Treatments
Topical combination
Methotrexate, cyclosporine, systemic immunomodulators (“biologics”)
Retinoids
PUVA for Cutaneous T-Cell Lymphoma, in Particular Mycosis Fungoides
PUVA for Vitiligo
Treatment protocols and results
PUVA for Atopic Dermatitis (See Ch. 12)
PUVA for Lichen Planus (See Ch. 11)
PUVA for Graft-Versus-Host Disease
PUVA for Urticaria Pigmentosa (See Ch. 118)
PUVA for Miscellaneous Dermatoses
PUVA for Photodermatoses
Side Effects and Long-Term Hazards of PUVA
Ophthalmologic effects
Laboratory data
Potential long-term risks of PUVA
UVB and PUVA in HIV-Infected Patients
Extracorporeal Photochemotherapy (Photopheresis)
Treatment Protocols
Mechanism of Action
Side Effects
Other Indications
References
Chapter 135: Photodynamic Therapy
Abstract
Keywords:
Chapter Contents
Introduction
History and Development
PDT – Photochemistry, Photobiology, and Mechanism of Action
PDT Photochemistry
Photobiologic Mechanisms of Action
PDT Selectivity
Advantages and Limitations of PDT
Components of PDT
Photosensitizers
Light Sources
Artificial light sources
Natural daylight
Light delivery
PDT Dosimetry
Dermatologic Applications
Oncologic
Actinic keratoses
Basal cell carcinomas
Squamous cell carcinomas
PDT photochemoprevention of AKs and keratinocyte carcinomas
Mycosis fungoides
Extramammary Paget disease
Cutaneous metastases
Non-Oncologic PDT Applications
Acne
Photoaging
Psoriasis
Cutaneous infections
Vascular anomalies
Hypertrophic scars and keloids
Adverse Effects and Complications of PDT
Photosensitivity
Pain
Inflammation
Photosensitizer Allergy
Rare, Unusual or Controversial Reactions
Practice and Techniques
Future Directions
References
Chapter 136: Lasers and Other Energy-Based Technologies – Principles and Skin Interactions
Abstract
Keywords:
Chapter Contents
Introduction
Lasers
Skin Optics
Thermal Interactions
Selective Photothermolysis
Photomechanical Effects
Cooling for Skin Protection
Applications of Laser Principles
Ablative (Vaporizing) Skin Resurfacing
Interactions During Treatment of Vascular Lesions
Interactions During Treatment of Pigmented Lesions and Tattoos
Interactions During Hair Removal
Non-Ablative Skin Rejuvenation
Fractional Photothermolysis
Laser-Induced Optical Breakdown (Plasma Formation)
Laser-Based Diagnostics
Principles of Laser Safety
Non-Laser Energy Sources
Flashlamps (Intense Pulsed Light)
Radiofrequency
Ultrasound
Low Level Light Therapy (LLLT)
Cryolipolysis
Future Directions
References
Chapter 137: Lasers and Other Energy-Based Therapies
Abstract
Keywords:
Chapter Contents
Types of Lasers and Intense Pulsed Light
Pulsed Dye Laser
KTP Laser (Frequency-Doubled Nd:YAG Laser)
Nd:YAG Laser
Intense Pulsed Light
Treatment of Vascular Lesions
Port-Wine Stains
Infantile Hemangiomas
Telangiectasias
Poikiloderma of Civatte
Telangiectasias and Venulectasias of the Leg (”Spider” Leg Veins)
Verrucae
Pyogenic Granulomas
Venous Lakes and Cherry Angiomas
Pain Considerations
Treatment of Tattoos
Treatment of Melanin-Containing Lesions
Ephelides and Lentigines
Benign Melanocytic Nevi
Café-au-Lait Macules and Nevus Spilus
Nevus of Ota and Nevus of Ito
Melasma
Becker Melanosis (Nevus)
Hyperpigmentation and Discoloration: Postinflammatory, Post-Sclerotherapy, and Drug-Induced
Treatment of Striae Distensae
Ablative Lasers: Carbon Dioxide and Er:YAG
Fractionated Lasers
Non-Ablative Fractional Photothermolysis
Ablative Fractional Photothermolysis
Fractionated Radiofrequency Devices
Preoperative Considerations
Anesthesia and Eye Protection
Post-Therapy Considerations, Side Effects and Complications
Other Photorejuvenation Devices
Skin Tightening – Radiofrequency and Intense Focused Ultrasound
Microwaves
Hair Removal
Home-Based Lasers
Treatment of Psoriasis and Vitiligo
Conclusions
References
Chapter 138: Cryosurgery
Abstract
Keywords
Historical Background
Principles of Cryosurgery and Cryobiology
Cryoimmunology
Instruments and Techniques
Preoperative Considerations
Cryoanesthesia
Treatment
Benign Lesions
Premalignant Lesions, Including Actinic Keratoses
Cutaneous Malignancies
Palliative Treatment
Expected Postoperative Events and Care
Complications
Future Trends (Imaging Technology for Monitoring Cryosurgical Outcome)
References
Chapter 139: Radiotherapy
Abstract
Keywords:
Chapter Contents
Basics of Radiotherapy
Indications
Mechanism of Action
Treatment Machines
Terminology
Radiotherapy Doses
Radiation Physics
Low-Energy Photons (Superficial/Orthovoltage) and Common Cutaneous Protocols
Electrons
Brachytherapy
Office-Based Radiotherapy
Advantages of Radiotherapy
Disadvantages of Radiotherapy
Radiotherapy of Benign Skin Disorders
Background
Keloids
Cutaneous Lymphoid Hyperplasia (Cutaneous Pseudolymphoma)
Radiotherapy of in Situ Cutaneous Malignancies
Squamous Cell Carcinoma in Situ (Bowen Disease)
Lentigo Maligna
Radiotherapy of Invasive Carcinomas, Sarcomas, and Lymphomas
Basal Cell Carcinoma
Definitive radiotherapy
Adjuvant (postoperative) radiotherapy
Squamous Cell Carcinoma
Definitive radiotherapy
Keratoacanthomas
Adjuvant (postoperative) radiotherapy
Special clinical situations
SCC of the lip
Lymph node metastases of SCC
Perineural invasion of SCC and BCC
Immunosuppressed hosts
Dose fractionation schedules and fields
Merkel Cell Carcinoma
Angiosarcoma
Kaposi Sarcoma
Cutaneous Lymphomas
Total skin electron beam therapy
Adnexal Carcinomas
Palliation
Locally Advanced Tumors
Metastases
Reactions and Complications
Acute Reactions
Late Reactions
Younger Patients
Cutaneous Diseases Induced by Radiation Therapy
Future Trends
References
Chapter 140: Electrosurgery
Abstract
Keywords:
Chapter Contents
Introduction and Background
Definition
Electrocautery
Historical Aspects
Electrosurgical Devices and Outputs
Terminology: Monopolar, Bipolar, Monoterminal and Biterminal
Indications/Contraindications
Preoperative History and Considerations
Description of Techniques
Electrodesiccation and Electrofulguration
Electrocoagulation
Electrosection (Cutting)
Variations/Unusual Situations
Cardiac Pacemakers and ICDs
Postoperative Care
Complications
Fire
Thermoelectric Burns
Microorganism Transmission
Surgical Smoke
Electroepilation
Electrolysis vs Thermolysis
Side Effects
Iontophoresis
Future Trends
References
Section 21: Surgery
Chapter 141: Biology of Wound Healing
Abstract
Keywords:
Chapter Contents
Introduction
Regeneration Versus Repair
Effect of Immune Response on Wound Healing
Mechanisms of Tissue Repair and Regeneration Are Evolutionarily Conserved
Amphibians
Zebrafish
Mammals
Clinical Implications
Impact of Wound Depth on Wound Healing
Primary Versus Second Intention Healing
Skin Repair – Cellular and Molecular Aspects
Three Phases of Wound Healing
Cellular Components
Keratinocytes
Endothelial cells
Leukocytes and platelets
Polymorphonuclear leukocytes and platelets
Blood monocytes and tissue macrophages
T cells
Mast cells
Fibroblasts
Stem cells
Growth Factors and Their Receptors
Extracellular Matrix
Integrins
Proteases (Proteinases)
Impaired Wound Healing – Risk Factors
Wound Healing and Aging
Therapeutic Options for Chronic Wounds
Wound Dressings
Growth Factors
Cell- and Tissue-Based Therapies
Future Directions
Stem Cells
Molecular Modeling of Growth Factors
Biomaterials and Tissue Engineering
References
Chapter 142: Surgical Anatomy of the Head and Neck
Abstract
Keywords:
Chapter Contents
Topographic Anatomy of the Head and Neck
Skin Tension Lines
Cosmetic Subunits
Free Margins
The Superficial Musculoaponeurotic System
Muscles of Facial Expression
Vascular Anatomy
The Facial Nerve
Temporal Branch
Zygomatic and Buccal Branches
Marginal Mandibular Branch
Cervical Branch
Sensory Innervation of the Head and Neck
Lymphatic Drainage of the Head and Neck
References
Chapter 143: Anesthesia
Abstract
Keywords:
Introduction
Discussion
Physiology and Structure
Pharmacology
Additions to Local Anesthetics
Epinephrine
Sodium bicarbonate
Hyaluronidase
Anesthetic Mixtures
Side Effects
Vasovagal reactions
Allergic reactions
Local side effects
Overdosage
Topical Anesthetics
Skin
Mucous membranes
Cryoanesthesia
Anesthetic Injection Techniques
Local infiltration
Field block anesthesia
Tumescent anesthesia
Nerve Block Techniques
Facial nerve blocks
Digital nerve blocks
Penile nerve block
Hand nerve block
Foot nerve block
Higher Levels of Anesthesia
References
Chapter 144: Wound Closure Materials and Instruments
Abstract
Keywords:
Introduction
Discussion
Sutures
Types of Suture Material
Absorbable Sutures
Surgical gut
Polyglycolic acid
Polyglactin 910
Polydioxanone
Polyglyconate
Poliglecaprone 25
Glycomer 631 and polyglytone 6211
Non-Absorbable Sutures
Silk
Nylon
Polypropylene
Polyester
Polybutester
Suture Selection
Complications
Needles
Instruments
Curettes
Scalpels
Needle holders
Scissors
Forceps
Hemostats
Skin hooks
Special Instruments
Antiseptics and Sterilization
References
Chapter 145: Dressings
Abstract
Keywords:
Chapter Contents
Introduction
Moist Healing Environment
Role of Debridement
History of Wound Dressings
Functions of a Wound Dressing
Traditional Wound Dressings
First and Second Intention Healing
Wound Cleansers
Topical Antimicrobials and Dressings That Contain Antimicrobial Agents
Moisture-Retentive Dressings
Films
Advantages/disadvantages
Foams
Advantages/disadvantages
Hydrogels
Advantages/disadvantages
Alginates
Advantages/disadvantages
Gelling fibers (Hydrofibers)
Hydrocolloids
Advantages/disadvantages
Composites
Dressings That Reduce Wound Protease Levels
Advanced Wound Therapies
Topical Growth Factors
Tissue-Engineered Skin Equivalents or Skin Substitutes
Epidermal grafts
Dermal replacements
Xenogeneic
Allogeneic
Composite grafts
Negative Pressure Wound Therapy (NPWT)
Hyperbaric Oxygen Therapy (HBOT)
Compression Therapy
Types of Compression
Compression stockings
Compression bandages
Short stretch (inelastic) versus long stretch (elastic) bandages
Compression devices
Future Directions
References
E-References
Chapter 146: Biopsy Techniques and Basic Excisions
Abstract
Keywords:
Chapter Contents
Introduction
Key Concepts
Site Selection
Biopsy Technique Selection
Specimen Handling
Patient Preparation
Site Preparation and Anesthesia
Hemostasis
Wound Closure
Indications/Contraindications
Preoperative History and Considerations
Techniques
Curettage
Snip or Scissors Biopsy
Shave Biopsy and Saucerization Biopsy
Punch Biopsy
Incisional Biopsy
Excisional Biopsy (Excision in toto)
Cutaneous Cone (Dog-Ear) Repair
Variations/Unusual Situations
Postoperative Care
Complications
Future Trends
References
Chapter 147: Flaps
Abstract
Keywords:
Introduction
Background
Fundamentals of Flap Design and Suturing Technique
Flap Movement Characteristics
Burow’s triangle displacement flaps
Defect reconfiguration flaps
Tissue reorientation flaps
Tissue importation flaps
Description of Technique
Burow’s Triangle Displacement Flaps
Single tangent advancement flaps (STAFs) and rotation flaps
Double tangent advancement flaps (DTAFs)
Site-Specific Variations of Burow’s Triangle Displacement Flaps
Helical advancement flaps
Dorsal nasal flap
Other Site-Specific Flaps
Alar rotation flap (ARF) and spiral rotation flap (SRF)
Wedge closure of the lip
Defect Reconfiguration (Island Pedicle) Flaps
Island pedicle flap variations: pincer island pedicle flap
Tissue Reorientation Flaps
Rhombic transposition flap
Bilobed transposition flap
Trilobed flap and rhombic flap with Z-plasty
Nasolabial transposition flap
Tissue Importation Flaps
Forehead flaps
Nasolabial interpolation flap
Retroauricular flap
Spear’s flap
Tunneled flaps
Combination Flaps
Postoperative Care
Complications
References
Chapter 148: Grafts
Abstract
Keywords:
Chapter Contents
Introduction and Background
Wound Healing Considerations
Full-Thickness Skin Grafts
Indications/Contraindications
Preoperative History and Donor Site Considerations
Description of Technique
Securing the Graft
Postoperative Care
Variations/Unusual Situations
Purse-string suture
Burow’s grafts
Deep nasal defects
Postoperative Complications
Future Directions
Split-Thickness Skin Grafts
Indications/Contraindications
Preoperative History and Donor Site Considerations
Description of Grafting Techniques
Securing the Graft
Donor Site Care
Variations/Unusual Situations
Postoperative Care
Complications
Future Directions
Composite Grafts
Indications/Contraindications
Preoperative History and Considerations
Donor Site Considerations for Composite Grafts
Description of Technique
Donor Site Closure
Variations/Unusual Situations
Postoperative Care
Complications
Free Cartilage Grafts
Indications/Contraindications
Nasal Ala
Nasal Sidewall and Tip
Ear
Preoperative History and Donor Site Considerations
Description of Technique
Nasal ala
Nasal sidewall and tip
Ear
Eyelid
Postoperative Care
Complications
Future Trends
Conclusions
References
Chapter 149: Nail Surgery
Abstract
Keywords:
Chapter Contents
Introduction
Surgical Anatomy of the Nail Unit
Basic Anatomy
Innervation
Vascular Supply
Preoperative Evaluation and Patient Preparation
Anesthesia of the Nail Unit
Instruments for Nail Surgery
Nail Plate Avulsion
Biopsy Techniques
Nail Bed Biopsy
Nail Matrix Biopsy
Lateral Longitudinal Biopsy
Proximal Nail Fold Biopsy
Surgical Procedures for Disorders of the Nail Unit
Acute Paronychia
Chronic Paronychia
Ingrown Toenail
Tumors and Cysts
Fibrokeratoma
Subungual exostosis
Glomus tumor
Onychomatricoma
Digital myxoid cyst (pseudocyst)
Squamous cell carcinoma
Melanoma
Postoperative Care
Complications of Nail Surgery
References
Chapter 150: Mohs Micrographic Surgery
Abstract
Keywords:
Chapter Contents
Introduction
History
Training in Mohs Micrographic Surgery
Indications
Appropriate Use Criteria
Cost-Effective Care
Basal Cell Carcinoma
Squamous Cell Carcinoma
Erythroplasia of Queyrat
Keratoacanthoma
Verrucous Carcinoma
Lentigo Maligna
Melanoma Other Than Lentigo Maligna
Atypical Fibroxanthoma
Dermatofibrosarcoma Protuberans
Merkel Cell Carcinoma
Microcystic Adnexal Carcinoma
Sebaceous Carcinoma
Other Adnexal Carcinomas
Other Tumors and Applications
Contraindications
Preoperative History and Considerations
Technique
Variations/Refinements/Special Situations
Single Section Method
“Slow” Mohs Staged Excision and Geometric Staged Excision (for Melanoma)
Non-Beveled 90° Incision
Wide Excision MMS
Rapid Immunohistochemical Stains
Supplementation With Permanent Sections
Bone Invasion
Challenges and Pitfalls
Reconstruction
Postoperative Care
Complications
Future Trends
References
E-References
Chapter 151: Surgical Complications and Optimizing Outcomes
Abstract
Keywords:
Introduction
Discussion
Preoperative Assessment
Potential for bleeding
Laboratory evaluation
Medications and supplements
Wound healing
Prophylactic antibiotics
Defibrillators and pacemakers
Allergies
Informed consent
Intraoperative Considerations
Contamination
Bleeding and hemostasis
Tissue injury
Tension
Necrosis
Nerve deficits
Unsatisfactory scarring
Postoperative Considerations
Bleeding/hematoma/ecchymosis
Infection
Necrosis
Dehiscence
Wound appearance
Conclusions
References
Section 22: Cosmetic Surgery
Chapter 152: Evaluation of Beauty and the Aging Face
Abstract
Keywords:
Chapter Contents
Introduction
Evaluation of Beauty
Anatomic Basis for the Aging Appearance
Photoaging
Pigmentary System
Volume Changes – The Loss of Subcutaneous Fat
Changes in Facial Musculature
Changes in Underlying Cartilage and Bone
Inherent Loss of Elasticity
Gender Differences
Ethnic Differences
Combination Therapies
References
Chapter 153: Cosmetics and Cosmeceuticals
Abstract
Keywords:
Introduction
Discussion
Skin Care Products
Cleansers
Moisturizers
Astringents
Colored Facial Cosmetics
Facial foundations
Formulation
Application and cutaneous effects
Powders
Facial blushes
Eye shadows
Mascaras
Lipsticks
Facial cosmetics for camouflaging
Hair Care Products
Hair shampoos
Hair conditioners
Safety issues
Nail Care Products
Nail polish
Nail sculptures (artificial nails)
Hydroxy Acid Cosmeceuticals
Alpha-hydroxy acids
Beta-hydroxy acid
Additional Cosmeceuticals
Future Directions
References
Chapter 154: Chemical and Mechanical Skin Resurfacing
Abstract
Keywords:
Chapter Contents
Introduction and History
Preoperative History and Considerations
Indications
Contraindications and Patient Selection
Preoperative and Intraoperative Preparations
Chemical Resurfacing Procedures
Superficial Chemical Peeling
Medium-Depth Chemical Peeling
TCA CROSS
Deep Chemical Peeling
Mechanical Resurfacing Procedures
Microdermabrasion
Manual Dermasanding
Motorized Dermabrasion
Microneedling
Postoperative Care
Complications
Conclusions and Future Trends
References
Chapter 155: Phlebology and Treatment of Leg Veins
Abstract
Keywords:
Chapter Contents
Introduction
Venous Anatomy, Physiology and Pathophysiology
Physical Examination of the Phlebology Patient
Laboratory Evaluation of the Superficial Venous System
Compression in Sclerotherapy and Venous Disease
Sclerosing Solutions
Techniques for Treating Telangiectasias and Reticular Veins
Injection Technique
Treatment Protocol
Lasers and Intense Pulsed Light Sources for Treatment of Telangiectasias
Larger Varicose Veins
Foamed Detergent Solutions
Polidocanol 1% injectable foam (Varithena®)
Spontaneous foaming with room air
Duplex Ultrasonography
Postsclerotherapy Compression
Complications
Postsclerotherapy Pigmentation
Telangiectatic Matting
Ulceration
Systemic Allergic Reaction
Arterial Injection
Miscellaneous Complications
Ambulatory Phlebectomy
Preoperative Considerations
Anesthesia and Intraoperative Materials for Ambulatory Phlebectomy
Ambulatory Phlebectomy Technique
Postoperative Considerations for Ambulatory Phlebectomy
Complications of Ambulatory Phlebectomy
Targeting the Saphenofemoral Junction
Endovenous Laser Ablation
Endovenous Radiofrequency Closure (Ablation)
Combination With Ambulatory Phlebectomy
Comparative Clinical Trials
Other Endovenous Procedures for the Treatment of Saphenofemoral Junction Incompetence
Conclusions
References
Chapter 156: Body Contouring
Abstract
Keywords:
Chapter Contents
Introduction and Background
Body Contouring Consultation
Liposuction Procedure
Indications and Contraindications
The Preoperative Visit
Description of Techniques
Tumescent anesthesia
Liposuction surgical technique
Liposuction Instrumentation
Liposuction Devices
Ultrasound-assisted
Power-assisted
Laser-assisted
Water-assisted
Manual liposuction versus device-assisted liposuction
Liposuction Variations
Non-Cosmetic Liposuction
Postoperative Care
Complications of Liposuction
Non-Invasive Body Contouring
Injection Lipolysis
Low-Level Light Therapy
High-Intensity Focused Ultrasound
Non-Thermal Focused Ultrasound
Cryolipolysis
Radiofrequency
Cellulite
Conclusion
Copyright notice
References
Chapter 157: Hair Restoration
Abstract
Keywords
Introduction
Historical Perspective
Male and Female Pattern Hair Loss (Androgenetic Alopecia)
Pathogenesis
Clinical Features
Treatment (Other Than Transplant Surgery)
Medical therapies
Low-level light therapy
Hair Transplantation
Candidate Selection
Key Concepts
Staff Training for Manual Hair Transplantation
Donor Region
Elliptical donor harvesting
Follicular grafts
Follicular unit extraction (FUE)
Advantages of FUE
Follicular unit extraction (FUE) by robotic systems
Hairline Design and Recipient Site Creation
Anesthesia and Recipient Site Creation
Graft Placement and Postoperative Course
Complications
Corrective Hair Transplant Surgery
Adding follicular unit grafts
Surgical removal of grafts
Laser-assisted removal of large grafts
Hypertrophic or broad scars in the donor region
Hair Transplantation in Scarring Alopecias
Hair Transplantation in African-Americans
Future Trends
References
Chapter 158: Injectable Soft Tissue Augmentation
Abstract
Keywords:
Chapter Contents
Historical Perspective
General Injection Technique
Injectable Soft Tissue Filler Materials
Hyaluronic Acid Derivatives
Poly-L-Lactic Acid
Calcium Hydroxylapatite
Autologous Fibroblasts
Lipotransfer
Silicone
Polymethylmethacrylate (PMMA) Microspheres
Platelet-Rich Plasma
Complications
Conclusion
Copyright notice
References
Chapter 159: Botulinum Toxin
Abstract
Keywords:
Chapter Contents
Introduction
Properties of Botulinum Toxins
Formulations
Clinical differences
Topical BoNT-A
A note about dosing
Cosmetic Use of Botulinum Toxin Type A
Glabellar Frown Lines
Crow’s Feet
Horizontal Forehead Lines
Brow Lift and Shaping
Hypertrophic Orbicularis Oculi
Midface Injections
Vertical Lip Rhytides (Perioral Lines)
Facial Asymmetry: Functional Muscle Imbalance
Mouth Frown
Melomental Folds (Marionette Lines)
Mental Crease
Peau d’Orange (Apple Dumpling) Chin
Masseteric Hypertrophy
Platysmal Bands
Adjunctive Use
Medical Uses of Botulinum Toxin Type A
Hyperhidrosis
Raynaud Phenomenon
Migraine
Depression
Complications
Safety
Future Trends
Summary

Citation preview

Dermatology Fourth Edition

Dermatology Fourth Edition

Edited by

Jean L. Bolognia MD Julie V. Schaffer MD

Lorenzo Cerroni MD

Professor of Dermatology Department of Dermatology Yale School of Medicine New Haven, CT, USA

Pediatric Dermatology Fellowship Director Pediatric and Adolescent Dermatology Division Hackensack University Medical Center Hackensack, NJ, USA

Associate Professor of Dermatology Director, Research Unit Dermatopathology Department of Dermatology Medical University of Graz Graz, Austria

Jeffrey P. Callen MD FACP

George J. Hruza MD MBA

Luis Requena MD PhD

Professor of Medicine (Dermatology) Chief, Division of Dermatology University of Louisville Louisville, KY, USA

Adjunct Professor of Dermatology Department of Dermatology St. Louis University School of Medicine St. Louis, MO, USA

Edward W. Cowen MD MHSc

Joseph L. Jorizzo MD

Chairman, Department of Dermatology Fundación Jiménez Díaz de Madrid Professor of Dermatology Universidad Autónoma de Madrid Madrid, Spain

Director, American Board of Dermatology Newton, MA, USA; Fellow, American Academy of Dermatology Schaumburg, IL, USA; Senior Clinician and Head, Dermatology Consultation Service Dermatology Branch, National Institute of Arthritis and Musculoskeletal and Skin Diseases National Institutes of Health Bethesda, MD, USA

Professor and Former (Founding) Chair Department of Dermatology Wake Forest University School of Medicine Winston-Salem, NC, USA; Professor of Clinical Dermatology Department of Dermatology Weill Cornell Medical College New York, NY, USA

Section Editors

Harvey Lui MD FRCPC Professor and Chairman Department of Dermatology and Skin Science University of British Columbia Vancouver, BC, Canada

For additional online content visit

http://expertconsult.com

Thomas Schwarz MD Professor and Chairman Department of Dermatology Christian-Albrechts-University Kiel Kiel, Germany

Antonio Torrelo MD PhD Chair, Department of Dermatology Hospital del Niño Jesús Madrid, Spain

© 2018, Elsevier Limited. All rights reserved. First edition 2003 Second edition 2007 Third edition 2012 The right of Jean L. Bolognia, Julie V. Schaffer, Lorenzo Cerroni, Jeffrey P. Callen, Edward W. Cowen, George J. Hruza, Joseph L. Jorizzo, Harvey Lui, Luis Requena, Thomas Schwarz, Antonio Torrelo to be identified as authors of this work has been asserted by them in accordance with the Copyright, Designs and Patents Act 1988. No part of this publication may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording, or any information storage and retrieval system, without permission in writing from the publisher. Details on how to seek permission, further information about the Publisher’s permissions policies and our arrangements with organizations such as the Copyright Clearance Center and the Copyright Licensing Agency, can be found at our website: www.elsevier.com/permissions. This book and the individual contributions contained in it are protected under copyright by the Publisher (other than as may be noted herein). © Chapter 3 is US Government work in the public domain and not subject to copyright. © Mayo foundation retains the copyright to their original photographs in Chapter 26. © Daniel Hohl retains copyright to his original photographs in Chapter 59. © William Coleman III retains copyright of his original photographs in Chapter 156. © Derek H. Jones retains copyright to his original photographs in Chapter 158. Disclaimer In 2015, under the Pregnancy and Lactation Labeling Rule (PLLR), the US Food and Drug Administration (FDA) abolished the letter rating system for drug safety in pregnant women and during lactation; the letters are to be replaced with narrative-based labeling. Drugs approved prior to 2015 have three years to comply with the new format while drugs approved thereafter must comply from the onset. Fed Regist 2014;79;72064-72103. Dr Cowen’s work as editor was performed outside of the scope of his employment as a US Government Employee. The views expressed are his own and do not necessarily represent the views of the National Institutes of Health or the US Government. Notices Practitioners and researchers must always rely on their own experience and knowledge in evaluating and using any information, methods, compounds or experiments described herein. Because of rapid advances in the medical sciences, in particular, independent verification of diagnoses and drug dosages should be made. To the fullest extent of the law, no responsibility is assumed by Elsevier, authors, editors or contributors for any injury and/or damage to persons or property as a matter of products liability, negligence or otherwise, or from any use or operation of any methods, products, instructions, or ideas contained in the material herein. ISBN: 978-0-7020-6275-9 E-ISBN: 978-0-7020-6342-8

The publisher’s policy is to use paper manufactured from sustainable forests

Printed in China Last digit is the print number: 9  8  7  6  5  4  3  2  1 Content Strategists: Russell Gabbedy, Charlotta Kryhl Content Development Specialists: Joanne Scott, Trinity Hutton e-products, Content Development Specialist: Kim Benson Project Manager: Joanna Souch Design: Christian Bilbow Illustration Manager: Lesley Frazier Illustrator: Antbits Ltd., Graphic World Marketing Manager: Kristin Koehler

Video Table of Contents 137.1 Fraxel Restore Dual Non-Ablative Fractionated Laser

148.12 Bolster Placement

145.1 Unna Boot Dressing

149.1 Curettage of a Lateral Nail Fold Pyogenic Granuloma

146.1 Fusiform Excision and Repair

149.2 Lateral Nail Plate Detachment

147.1 Burows Island and Bilobe Flaps

149.3 Lateral Nail Plate Avlusion

148.1 Harvesting Cartilage Graft

149.4 Phenol Matricectomy

148.2 Underming Prior to Placement of Cartilage Graft

149.5 Nail Fold/Matrix After Phenol Matricectomy

148.3 Placement of Cartilage Graft

150.1 Mohs Micrographic Surgery

148.4 Securing Cartilage Graft with Vicryl Suture

158.1 Right Face Volumizing

148.5 Harvesting Full-Thickness Skin Graft

158.2 Left Face Volumizing

148.6 Defatting Full-Thickness Skin Graft

159.1 Neuromodulator Treatment of Chin

148.7 Final Deffated Full-Thickness Skin Graft

159.2 Neuromodulator Treatment of Crow’s Feet

148.8 Placement and Sizing of Full-Thickness Skin Graft

159.3 Neuromodulator Treatment of Forehead

148.9 Suturing Full-Thickness Skin Graft in Place

159.4 Before and after Full Face Neuromodulator Treatment

148.10 Trimming Full-Thickness Skin Graft

159.5 Neuromodulator Treatment of Glabella

148.11 Placing Sutures for Tie-Over Dressing

159.6 Neuromodulator Treatment of Lips

Christopher Zachary, Kathryn Serowka Lane Afsaneh Alavi, Robert Kirsner Suzanne Olbricht

David G. Brodland

Désirée Ratner, Priya Mahindra Nayyar Désirée Ratner, Priya Mahindra Nayyar Désirée Ratner, Priya Mahindra Nayyar Désirée Ratner, Priya Mahindra Nayyar Désirée Ratner, Priya Mahindra Nayyar Désirée Ratner, Priya Mahindra Nayyar Désirée Ratner, Priya Mahindra Nayyar Désirée Ratner, Priya Mahindra Nayyar Désirée Ratner, Priya Mahindra Nayyar Désirée Ratner, Priya Mahindra Nayyar Désirée Ratner, Priya Mahindra Nayyar

x

Désirée Ratner, Priya Mahindra Nayyar Bertrand Richert, Phoebe Rich Bertrand Richert, Phoebe Rich Bertrand Richert, Phoebe Rich Bertrand Richert, Phoebe Rich Bertrand Richert, Phoebe Rich

Charlene Lam, Allison T. Vidimos

Derek H. Jones, Robert Bacigalupi, Katie Beleznay Derek H. Jones, Robert Bacigalupi, Katie Beleznay Alastair Carruthers, Jean Carruthers, Ada Trindade de Almeida Alastair Carruthers, Jean Carruthers, Ada Trindade de Almeida Alastair Carruthers, Jean Carruthers, Ada Trindade de Almeida Alastair Carruthers, Jean Carruthers, Ada Trindade de Almeida Alastair Carruthers, Jean Carruthers, Ada Trindade de Almeida Alastair Carruthers, Jean Carruthers, Ada Trindade de Almeida

Preface The practice of dermatology is based upon a visual approach to clinical disease, with the development of an appreciation of recurrent patterns and images. The entire spectrum of our discipline, from the generation of differential diagnoses to the orientation of rotational flaps, relies upon imagery. As a result, visualization also plays a critical role in how we integrate new information into pre-existing frameworks that serve as the hard drives of our medical memory. In the textbook Dermatology there is a strong emphasis on visual learning. This commitment is reflected in the use of schematic diagrams to convey the principles of skin biology as well as cutaneous surgery, in addition to the inclusion of algorithms, which provide a logical as well as practical approach to commonly encountered clinical problems. The majority of the basic science is integrated throughout the book and appears as introductory chapters to the various sections. In this edition, even more emphasis has been placed on clinicopathologic correlations, with photomicrographs demonstrating key histologic findings adjacent to clinical images of the same disorder. The chapters

also contain tables that attempt to provide weighted differential diagnoses and a “ladder” approach to therapeutic interventions. Lastly, color-coding of sections allows an easy and rapid access to required information. The ultimate goal of Dermatology is for it to never make its way to the bookshelf because it is being used on a weekly, or perhaps even daily, basis. Hopefully, this book will function as a colleague, albeit a non-verbal one, who is easily approachable and possesses the necessary expertise to provide succinct, up-to-date information that is both precise and practical. It is also our hope that the organization is intuitive and information can therefore be quickly retrieved. Realizing this goal required the time and energy of our contributors, who have unselfishly shared their knowledge and experience with literally thousands of patients from around the world, and we thank them. JB, JVS, and LC 2017

xi

User Guide VOLUMES, SECTIONS AND COLOR CODING Dermatology is divided into two volumes. The book is divided into 22 sections, which are color-coded as follows for reference:

Basic Science Chapters Basic science chapters in the book are highlighted on the upper corner of each page with the following skin biology symbol:

VOLUME ONE

Section 1 Overview of basic science Section 2 Pruritus Section 3 Papulosquamous and eczematous dermatoses

Therapeutic Ladders

Section 4 Urticarias, erythemas and purpuras Section 5 Vesiculobullous diseases Section 6 Adnexal diseases Section 7 Rheumatologic dermatology Section 8 Metabolic and systemic diseases Section 9 Genodermatoses Section 10 Pigmentary disorders Section 11 Hair, nails, and mucous membranes

Therapeutic ladders have been standardized for measuring levels of evidence. Key to evidence-based support: (1) prospective controlled trial (2) retrospective study or large case series (3) small case series or individual case reports.

Dermatology Website Additional ‘e’ references in Chapters 8, 24, 65, 116, 145 and 150 can be found in full at http://www.expertconsult.com, which includes all of the book’s content plus supplementary images and tables in a searchable format.

VOLUME TWO

Section 12 Infections, infestations, and bites

Video Icon

Section 13 Disorders due to physical agents Section 14 Disorders of Langerhans cells and macrophages Section 15 Atrophies and disorders of dermal connective tissues Section 16 Disorders of subcutaneous fat Section 17 Vascular disorders Section 18 Neoplasms of the skin Section 19 Medical therapy Section 20 Physical treatment modalities Section 21 Surgery Section 22 Cosmetic surgery xxv

Dedication Dedication

Past Editors

This book is dedicated to our families, in particular Dennis Cooper, MD, Andrew Schaffer and Ricarda Cerroni, who endured our work on this project and who unwittingly were part of the team, and to all the rest of the team at Elsevier who made it all happen.

We would like to acknowledge and offer grateful thanks for the input of all previous editions’ editors, without whom this new edition would not have been possible

Acknowledgments We are grateful to the authors for sharing their expertise and putting forth their best efforts to bring up-to-date educational material to the readers. In addition, we wish to acknowledge the invaluable contributions of Joanne Scott and Glenys Norquay, both of whom invested years of focused work into this project. The expertise of team members Trinity Hutton (development), Joanna Souch (production), Lesley Frazier (illustrations), and Susan Stuart (production) ensured a topquality textbook. We also want to thank Russell Gabbedy, who was there in the early days of the first edition and then rejoined us for the third and fourth editions.

Warren R. Heymann, 3rd edition Thomas D. Horn, 1st, 2nd editions Anthony J. Mancini, 1st, 2nd, 3rd editions José M. Mascaro, 1st edition James W. Patterson, 3rd edition Ronald P. Rapini, 1st, 2nd editions Martin Röcken, 3rd edition Stuart J. Salasche, 1st, 2nd editions Jean-Hilaire Saurat, 1st edition Georg Stingl, 1st, 2nd editions Mary S. Stone, 2nd edition

xxvi

Figures and Tables Photographs are a key component of this book and we thank Kalman Watsky, MD, M. Joyce Rico, MD, and the late Louis A. Fragola, Jr, MD, for their contributions. The following figures were sourced from the Yale Residents’ Slide Collection: Fig. 0.5, 0.7, 0.9C, 0.9F, 0.9H, 0.10, 1.11A, 1.12, 7.7C, e7.3, 8.5B, 8.7B, 8.10, 8.16, 8.17A, 8.17C, 8.18A, 8.18B, e8.5, 9.2A, 9.2B, 9.3C, 9.3D, 9.6A, 9.6D, 9.13A, e9.8, 10.1, 10.2, 10.7, e10.1, 11.5B, 11.7B, 11.8, 11.9B, 11.9C, 11.10A, 11.12, 11.13A, 11.13C, 11.15A, 11.15B, 11.15C, 11.16A, 11.17, 11.21A, 11.21B, 11.24A, 12.6B, 12.11, 12.14 (inset A), e12.5A, 13.3 (insets B & I), 14.7, 14.10, 14.19, 17.11B, 17.11C, 17.11D, 18.1A, 18.1C, 19.1A, 19.1B, 19.1C, 19.1D, 19.2A, 19.5A, 19.6, 20.1B, 20.1C, 20.1E, 20.2, 20.3A, 20.7A, 20.7B, 20.8, 20.9A, 20.11A, 20.11B, 20.14A, 20.14B, e20.3, 21.1B, 21.2, 21.3C, 21.7B, 21.8, 21.10A, 21.10B, 21.12, 21.13, 21.25A, e21.1A, e21.1B, e21.7, e21.8, 22.1C, 22.6A, 23.5B, 23.5C, 23.8B, 23.11A, 23.11B, 24.3B, 24.3C, 24.6A, 24.6B, 24.7B, 24.7C, 24.17B, 24.17C, 24.17D, 25.3A, 26.8, 26.10D, 26.10E, 26.12, e26.1, 27.4A, 27.4B, 27.4C, 27.11B, 29.8B, 30.2C, 30.6C, 30.18, e30.3, e30.7, 31.2A, 31.2B, 31.2C, 31.3A, 31.10, e31.2, e31.5, 32.2A, 32.4A, 32.4C, 32.9, 32.10A, 32.19B, 33.1, 33.10, 34.4A, 34.4B, 34.16, 36.9, 37.9C, 37.12, 37.14B, 38.3B, 38.5D, 38.15B, 38.15C, 39.8, e39.2, 41.5A, 41.5B, 41.5D, 41.5E, 41.5F, 41.5G, 41.8B, 41.9B, 41.11A, 41.12, 41.13, 41.15, 41.16, 42.2A, 42.2B, 42.6, 42.9B, 43.8, e43.1, e43.2, e43.3C, 44.5A, 44.8B, e44.5, 45.1A, 46.15C, 47.6, 47.7, 47.8B, 47.9A, e47.3, 48.1, 49.3A, 49.7, e49.2, 50.5C, 50.9C, 50.9D, e50.6, 51.8A, 51.9A, 51.12B, 51.12D, e51.2, e52.1A, 53.31, 57.10A, 57.10B, 57.12C, 57.14A, 57.14B, 57.14C, 58.3C, 58.3D, 58.8B, 58.15, e58.2B, e58.7A, e58.7B, e58.7C, e58.8, 59.2B, 59.2D, 59.12, 59.14, 59.15, 59.16, 60.4B, e61.2, e61.4, 62.6A, 62.6C, 62.7C, 62.10A, 62.12, 62.13, e62.2A, 63.2, 63.16C, 64.4, 64.19B, 64.22, 66.17, 66.19A, 66.19E, 66.19F, 66.20, 66.21, 66.22, 66.23A, 66.24, 66.28, 66.29, 66.30A, 66.30B, e66.4, e66.8, 67.4, 67.7B, 67.10, 67.10 (inset), 67.20B, e67.2A, 69.14A, 69.14D, 69.27, e69.5, 70.6, 70.7, e70.2, 71.2, 71.19A, 72.1 (inset ii), Table 72.1 (insets), e72.1, 73.13A, 73.15A, 74.7A, 74.7B, 74.11A, 74.11B, 74.11C, 74.14, 74.18, 74.21, 74.28, 74.34, e74.2A, e74.2C, e74.7, 75.13, 75.14, 75.16B, 75.17, 75.18, 75.19, 75.21A, 75.21B, 75.21C, 75.23A, 75.24, 76.5, 76.6, 77.4, 77.5B, 77.6E, 77.8, 77.12A, 77.12C, 77.12D, 77.12E, 77.12F, 77.15A, 77.15C, 77.20F, 77.24A, 77.33A, 77.33B, 77.33D, 77.33E, e77.7, 80.6A, 80.8A, 80.8B, 80.8C, 80.15A, 80.15C, 80.15E, 80.15F, e80.5, 81.10A, 81.10C, 82.5B, 82.7A, 82.7C, 82.7D, 82.7E, 82.8A, 82.8B, 82.8C, 82.9A, 82.9B, 82.9C, 82.13, 82.22A, 82.22C, 83.4B, 84.1, 84.3A, 84.3D, 84.5, 84.12,

84.15A, 85.5, 85.18, 87.24C, e87.2B, e87.7E, 88.8B, 88.17, 91.1A, 91.1D, 91.1F, 91.7B, 91.15, e91.1, 92.2, 92.3A, 92.11, 93.2A, 93.2C, 93.2D, 93.3C, 93.4, 93.8B, 93.18C, e93.4, e93.7, e93.8, e93.10, 94.1, 94.3B, 96.4A, 96.4B, 96.6, 96.8, 97.6B, e97.4, 98.1B, 98.1D, 98.9, 99.5C, e99.2, 101.9B, 103.4A, 103.9, 103.10C, e103.6B, 104.3A, 104.12A, 104.18B, 104.18E, e104.11A, 105.4, 105.5E, 105.6, 105.7A, 105.9, 105.14, 105.15B, 105.18, 105.20B, 106.13, 106.14, 106.16, 108.5C, 108.6, 108.9B, 108.9C, 108.10B, 108.16B, 109.3B, 109.8A, 109.8E, 109.11A, 110.2, 110.7, 110.13B, 110.16B, 110.26, 111.2, 111.4A, 111.6, 111.12, 111.15, 111.18A, 111.21A, 111.24A, 111.26, 111.30, 111.34, 111.36, 111.37, e111.1, e111.2, e111.3B, 112.1B, 112.5A, 112.7, 112.8A, 112.28A, 113.8, e113.5, 114.13A, 114.19, 115.17A, 116.1, 116.20, 116.22, 116.24, 117.9, e117.1, 118.6B, 118.6C, 118.8, e118.3, 121.1A, 122.2C, 122.4B, 122.4C, 127.6D, 128.2, 128.3, 128.7B, 134.6. The following figures were sourced from the NYU Slide Collection: 9.6E, 10.5, 10.8, 10.9, 11.9A, 11.13B, e11.1, 13.2B, 16.7, 18.13, 24.2B, 25.5, 29.8C, 29.8D, 30.7A, 38.8, 44.9B, e44.1, e44.3A, 48.4A, 57.11A, 57.11C, 64.18A, 67.3A, 67.5A, 67.5B, e69.2, 70.13, 72.6, 74.19C, 74.23, 74.29A, 76.8A, 76.8B, 81.9A, 81.9B, 82.11, 87.2B, 87.3B, e87.7C, 93.15A, 93.15B, 101.16B, 116.2, 116.10, 116.17, 116.32, 130.5A. The following figures were sourced from the USC Residents’ Slide Collection: e6.2A, 44.16, 46.9, e52.1B, 62.5D, 62.6D, 74.33, 75.6A, e75.3, 77.22A, 77.22B, 77.23A, 77.27A, 77.27B, 77.29A, 77.29B, 84.3B, 84.3C, e104.4C, 111.29A, 114.16, 130.2. The following figure was sourced from the SUNY Stony Brook Residents’ Slide Collection: 66.19C. The following figures and tables were sourced from the Dermatology Essentials book: 0.1, 0.9, Table 0.4, 6.2, 12.1, 12.3, 12.14, 13.3, e13.5, Table 13.3, 21.4, e21.2, e21.3, eTable 21.3, 24.16, Table 24.8, 26.1, 29.12, Table 29.8, 32.4B, 35.2, Table 35.1, Table 35.2, 36.1, Table 37.6, 38.1, 42.1, 43.2, Table 43.6, Table 43.8, Table 45.4, 51.2, 52.2, Table 53.1, 66.4, 69.1, 70.15, 70.16, 70.17, Table 70.9, e74.1, Table 74.3, Table 74.13, 75.1, Table 75.4, Table 78.3, Table 78.6, 80.14, 81.2, 87.1, 101.1, 105.8, e108.12, Table 108.9, 111.1, 112.25, 117.1.

xxvii

OVERVIEW OF BASIC SCIENCE SECTION 1

Basic Principles of Dermatology Whitney A. High, Carlo Francesco Tomasini, Giuseppe Argenziano and Iris Zalaudek

0 

Etiologic Premises

Chapter Contents Introduction to clinical dermatology . . . . . . . . . . . . . . . . . . . . 1 The role of dermatopathology in clinicopathologic correlation . . 11 Introduction to the use of dermoscopy (dermatoscopy) . . . . . . . 32

All students of dermatology, whether beginners or advanced scholars, require a basic conceptual framework upon which to organize thousands of skin diseases. A useful arrangement is one that is analogous to a tree, with a trunk, major branches, minor branches, twigs and, ultimately, leaves (Fig. 0.1). Instead of memorizing thousands of leaves, a logical, progressive movement along the limbs will allow for a more complete and sophisticated differential diagnosis.

Inflammatory versus neoplastic

INTRODUCTION TO CLINICAL DERMATOLOGY The skin represents the largest organ of the human body. The average adult has 1.75 m2 (18.5 ft2) of skin that contains a variety of complex adnexal structures, including hair follicles, nails, glands and specialized sensory structures, all of which function in protection, homeostasis, and the transmission of sensation. Dermatology is the field of medicine that deals with the macroscopic study of skin, adjacent mucosa (oral and genital) and cutaneous adnexa, while dermatopathology deals with the microscopic study of the same structures. The two fields are closely allied, as they are complementary and requisite to one another. Multiple studies have shown that a dermatologist is the most effective diagnostician with regard to skin disease1,2. This enhanced acumen reflects experience in recognizing distribution patterns and configurations as well as subtle variations in morphology and colors, in addition to appreciating associated histopathologic findings. This chapter will not only serve as an introduction to the classification schemes, descriptive terminologies and diagnostic tools utilized in dermatology, it will also highlight additional means for studying the skin, including dermoscopy (dermatoscopy) and dermatopathology, with clinicopathologic correlation between macroscopic and microscopic findings.

An early and major “branch point” in classifying skin diseases is deciding simply if a skin condition is “neoplastic” (either benign or malignant) or “inflammatory” (either infectious or non-infectious) (see Fig. 0.1). However, an experienced clinician knows that one must consider possible diagnoses along multiple limbs before narrowing the differential diagnosis, because both overlap and mimicry can occur. For example, mycosis fungoides, the most common form of cutaneous T-cell lymphoma, is a clonal lymphoproliferative disorder (a “neoplasm”), yet its clinical presentation resembles an inflammatory disorder (Fig. 0.2), especially in its early stages. Conversely, sarcoidosis is an inflammatory condition, but it may present as an isolated infiltrated plaque or nodule that may mimic a neoplasm (Fig. 0.3).

Morphology To an engineer or material scientist, the word “morphology” refers to the structure and appearance of a material without regard to function. In dermatology, this term is used analogously to refer to the general appearance of a skin lesion or lesions, irrespective of the etiology or underlying pathophysiology. For example, a small cutaneous blister is referred to as a “vesicle”, regardless of whether it is due to an infectious process, such as herpes zoster, or an autoimmune process, such as

Fig. 0.1 Classification scheme for dermatologic disorders. The “trunk” of dermatology divides into the major etiologic “branches” of inflammatory, neoplastic, and other. Branches narrow and further subdivide, e.g. inflammatory into infectious and non-infectious. Branches ultimately terminate as clustered leaves, representing specific disorders.  

CLASSIFICATION SCHEME FOR DERMATOLOGIC DISORDERS

Fungal

Malignant Protozoal

Viral

Non

Autoimmune connective tissue diseases

s

In fla

Metabolic and toxic insults/trauma

tic m

m a

ry to

Autoimmune bullous diseases

-inf ect iou

s Infectiou

Urticarias and erythemas

Neo plas

Papulosquamous and eczematous dermatoses

Benign

Bacterial

her Ot

Genodermatoses and developmental anomalies

Dermatologic disorders

1

All students of dermatology need a basic foundation and framework upon which to accumulate knowledge. In this chapter, the basic tenets of disease classification in dermatology are introduced. This includes division of disease processes into basic etiologic origins, most commonly inflammatory diseases versus neoplasms, with further subdivision of the former into infectious versus non-infectious. Further subcategorizations eventually result in an appropriate differential diagnosis. Descriptive terms are also introduced which represent the lexicon of dermatology and serve as the building blocks of a specialty-specific language. The principles of morphology, configuration, and distribution are stressed as is the utility of these concepts in the generation of a logical differential diagnosis. The importance of histopathologic examination of diseased skin, especially when an appropriate and representative biopsy specimen is obtained, is emphasized, as is clinicopathologic correlation. However, the latter may require both special stains and immunohistochemical stains. Advanced clinical examination techniques, in particular dermoscopy, are also outlined. In sum, this introductory chapter foreshadows a more detailed discussion of the myriad aspects of the clinical practice of dermatology and dermatopathology that follow in the remainder of the tome. In this regard, metaphorically, the chapter represents footings, placed into bedrock and designed to secure the “dermatologic skyscraper” that the remainder of the text represents. Dermatopathology combines two separate, although intimately related disciplines, clinical dermatology and general pathology. Both of these fields share the same root, i.e., morphology. The secret for learning dermatopathology is to adapt the same skill sets that enable you to recognize primary and secondary skin lesions clinically and apply them to the microscopic slide. The chapter starts with the basic principles of performing a skin biopsy, including proper selection of a clinical lesion, biopsy techniques and handling of specimens, emphasizing the prerequisites for maximizing the results of the procedure. It then describes an algorithmic approach to pattern recognition for the histopathologic diagnosis of inflammatory skin diseases. Ancillary techniques that may help in the pathologic diagnosis of skin diseases, particularly immunohistochemistry, are also discussed.

morphology, distribution, configuration, skin color, clinicopathologic correlation, temporal course, dermatopathology, dermoscopy, dermatoscopy, skin biopsy, special stains, immunohistochemical stains, clinicopathologic correlation, dermatology lexicon, skin biopsy, pattern analysis, immunohistochemistry, special stains, inflammatory diseases, invisible dermatoses, clinicopathologic correlation

CHAPTER

0

Basic Principles of Dermatology

ABSTRACT

non-print metadata KEYWORDS:

1.e1

SECTION

1

Fig. 0.2 Mycosis fungoides, the most common form of cutaneous T-cell lymphoma. Mycosis fungoides represents a neoplastic proliferation of monoclonal lymphocytes, but it presents clinically in a manner akin to that of inflammatory disorders.

Overview of Basic Science



Courtesy, Lorenzo Cerroni, MD.

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Fig. 0.3 Sarcoidosis. It is an inflammatory disorder of uncertain etiology, most prevalent in African-Americans from the southern United States, but sarcoidosis can present as a papulonodule or infiltrated plaque, mimicking a neoplastic disorder.

Fig. 0.4 Herpes zoster, an infectious disease, versus bullous pemphigoid, an autoimmune bullous disease. While disparate in etiology, herpes zoster (A) and bullous pemphigoid (B) result in a similar morphology – namely, cutaneous vesicles and bullae. A, Courtesy, Lorenzo Cerroni, MD.

bullous pemphigoid (Fig. 0.4). Therefore, the proper use of morphologic terms establishes a structural framework for grouping skin diseases based upon their macroscopic appearance3. In essence, morphologic terms become a “native language” by which dermatologists, and other health professionals, communicate with each other to describe skin lesions. As such, they are key elements of a lexicon. Without a basic working knowledge of morphology, it is impossible to describe cutaneous observations in a consistent manner. Therefore, one of the initial steps in studying dermatology is to learn basic morphologic definitions inherent to the specialty. There exist both primary morphologic terms (Table 0.1), which refer to the most characteristic, representative or native appearance of skin lesions (e.g. a “papule”), as well as secondary morphologic terms (Table 0.2), which can augment or even supplant primary morphologic terms. Secondary morphologic terms often reflect the effects of exogenous factors or temporal changes (e.g. “scales”, “crusts”) that evolve during the course of a skin disease. Secondary changes must be considered when performing, or examining histologically, a biopsy of a skin lesion. An astute clinician will generally attempt to biopsy a well-developed but “fresh” lesion that demonstrates the expected primary pathology, free of secondary changes such as erosions, excoriations, and lichenification. This allows the dermatopathologist to evaluate the histologic features of the lesions in their native state, without potentially confounding alterations.

Lastly, the skin is a three-dimensional structure, and like the cartographers who construct maps, there are certain descriptors used by dermatologists to describe the topography of individual skin lesions. Examples include flat-topped (lichenoid), dome-shaped, verrucous, umbilicated, filiform, and pedunculated3.



2



Palpation and appreciation of textural changes Any discussion of morphology must include textural change, and palpating a lesion often provides important diagnostic clues. In dermatology, palpation can prove useful in several ways. Firstly, it helps in making a distinction amongst primary morphologies (see Table 0.1). For example, the key difference between macules and papules, or patches versus plaques, is that macules and patches are flush with the surrounding skin and cannot be appreciated by palpation. On the other hand, papules and plaques, by definition, must be palpable (Table 0.3). Secondly, palpation may augment the examination and appreciation of a disease process for which visual changes are absent, unimpressive, or nonspecific. For example, in morphea, an autoimmune connective tissue disease that leads to sclerotic collagen within the dermis, the skin feels indurated (very firm) while only nonspecific hyperpigmentation may be evident with visual inspection. The same is true for other fibrotic disease processes, such as nephrogenic systemic fibrosis and systemic sclerosis. Likewise, atrophy, be it epidermal, dermal or subcutaneous, also serves as a diagnostic clue (Fig. 0.5).

CHAPTER

Term

Clinical features

Macule



Clinical example

Flat (non-palpable), circumscribed, differs in color from surrounding skin • 1 cm in diameter • Often hypo- or hyperpigmented, but also other colors (e.g. blue, violet)

Vitiligo Melasma • Dermal melanocytosis (Mongolian spot) • Café-au-lait macule • Nevus depigmentosus • Solar purpura



• •

Vitiligo Papule

Elevated (palpable), circumscribed • 1 cm in diameter • Elevation due to increased thickness of the epidermis and/or cells or deposits within the dermis • May have secondary changes (e.g. scale, crust) • Occasionally, a plaque is palpable but not elevated, as in morphea

Seborrheic keratosis Cherry hemangioma • Compound or intradermal melanocytic nevus • Verruca • Molluscum contagiosum • Lichen nitidus • Elevated component of viral exanthems • Small vessel vasculitis • •

Seborrheic keratosis



Psoriasis

Primarily epidermal • Psoriasis • Lichen simplex chronicus • Nummular dermatitis Dermal • Granuloma annulare • Sarcoidosis • Hypertrophic scar, keloid • Morphea • Lichen sclerosus

Sarcoidosis

Table 0.1 Primary lesions – morphological terms. Some of the photos courtesy, Jean L Bolognia, MD; Lorenzo Cerroni, MD; Louis A Fragola, Jr, MD; Julie V Schaffer, MD; Kalman Watsky, MD.  

Continued

3

SECTION

Overview of Basic Science

1

PRIMARY LESIONS – MORPHOLOGICAL TERMS

Term

Clinical features

Nodule



Clinical example

Palpable, circumscribed Larger volume than papule, usually >1 cm in diameter • Involves the dermis and/or the subcutis • Greatest portion may be beneath the skin surface or exophytic

Clinical disorders Epidermoid and tricholemmal cysts • Lipomas • Metastases • Neurofibromas • Panniculitis, e.g. erythema nodosum • Lymphoma cutis •



Epidermoid cyst Wheal

Transient elevation of the skin due to dermal edema • Often pale centrally with an erythematous rim

Urticaria





Acute annular urticaria Vesicle

Elevated, circumscribed 1 cm in diameter • Filled with fluid – clear, serous, or hemorrhagic • May become an erosion

Friction blister Bullous pemphigoid • Linear IgA bullous dermatosis • Bullous fixed drug eruption • Coma bullae • Edema bullae









Bullous pemphigoid Pustule

Elevated, circumscribed Usually other bacteria); secondary syphilis; disseminated erythema migrans Viruses e.g. exanthems due to enteroviruses, HHV-6, adenovirus (see Fig. 81.2), HIV; varicella, disseminated zoster ; Kaposi varicelliform eruption

**

**

Fungi e.g. disseminated dimorphic infection

Kawasaki disease

***

Drug reactions Morbilliform, serum sickness-like reaction, DRESS, AGEP, erythroderma

Neoplastic (e.g. lymphoma)

Inherited (e.g. periodic fever syndromes)

Erythema multiforme, SJS/TEN Primary cutaneous disorders (e.g. pustular psoriasis) Rheumatologic disorders (e.g. SLE, vasculitis, Still disease) Graft-versus-host disease

**

Protozoa e.g. Strongyloidiasis

* not a single site as in cellulitis, necrotizing fasciitis ** more likely in immunocompromised patient *** early on, more serious drug reactions, e.g. DRESS, may resemble a morbilliform eruption most diagnostic histopathology. Immature lesions may not yet manifest characteristic histopathologic changes, and older lesions may be compromised by secondary features. Of course, there are exceptions to this general principle, such as the sampling of early lesions of cutaneous small vessel vasculitis ( KRAS) (see Ch. 62). There are a number of genetic disorders that result in abnormal epidermal differentiation and barrier formation. One clinical presentation of such conditions is a “collodion baby” born encased in a taut, shiny, transparent membrane that is formed by aberrant stratum corneum. After shedding the membrane, most of these infants manifest with lamellar ichthyosis or congenital ichthyosiform erythroderma, two forms of autosomal recessive ichthyosis that exist on a spectrum4. However, following a collodion membrane, some patients develop completely normal appearing skin. The so-called “self-healing” collodion baby is an example of a dynamic epidermal phenotype that depends on environmental conditions. All of these outcomes can result from mutations in the same set of genes that encode proteins essential for formation of the epidermal barrier, including transglutaminase-1 (an enzyme that cross-links lipids to the cornified cell envelope; TGM1), lipid processing enzymes (ALOXE3, ALOX12B), and lipid transporters (ABCA12) (see Ch. 57). More deleterious mutations in ABCA12 cause harlequin ichthyosis (HI), an especially severe disorder of cornification characterized by aberrant epidermal maturation. Patients with HI are born with a tremendously thick, armor-like shell of hyperkeratosis, severe ectropion and eclabium, and underdevelopment of the nose and ears. The extreme phenotype of HI highlights the importance of lipid transport into lamellar bodies for epidermal formation and function. Abnormalities in the stratum corneum are present not only in infants with ichthyosis, but also in premature infants, especially those born before 28 weeks’ EGA. The immaturity of the stratum corneum results in impaired barrier function, which leads to an increased risk of infection, dehydration, and excessive absorption of topical medications or chemicals5. Even healthy full-term infants do not attain full skin barrier function until 3 weeks of age. The structural features of premature skin and adult skin are summarized in Table 2.1.

DEVELOPMENT OF SPECIALIZED CELLS WITHIN THE EPIDERMIS Two populations of non-keratinocyte cells – melanocytes and Langerhans cells – migrate to the epidermis during early embryonic development. Melanocytes are derived from the neural crest that forms along the dorsal neural tube. Melanocyte precursors migrate away from the neural tube within the mesenchyme beneath the primitive epidermis. They follow a characteristic trajectory, moving dorsolaterally and then ventrally around the trunk to the ventral midline, anteriorly over the scalp and face, and distally along the extremities. Cutaneous melanocytes also arise from Schwann cell/melanocyte precursor cells that migrate along nerves to the skin via a distinct ventral pathway6. Melanocytes can be identified within the epidermis at approximately 50 days’ EGA based on HMB45 immunostaining and their dendritic morphology. Epidermal melanocyte density is high early in embryonic development (~1000 cells/mm2), and it increases further (~3000 cells/ mm2) as the epidermis stratifies (80–90 days’ EGA) and the appendages begin to develop; later in gestation, the density decreases and becomes similar to that of young adults (800–1500 cells/mm2). However, epidermal melanin production does not begin until 3–4 months’ EGA, and melanosome transfer to keratinocytes is not seen until 5 months’ EGA. Even though all melanocytes are functional and in place at birth, the pigmentation of the skin increases over the first few months of life; this process is most pronounced in infants with darker skin phototypes. Active melanocytes are also present throughout the dermis during embryonic development. Eventually, most of these dermal melanocytes migrate to the epidermis or undergo apoptosis. By the time of birth, dermal melanocytes have generally disappeared, with the exception of certain anatomic sites (head and neck, dorsal aspects of the distal extremities, and sacrococcygeal area), which correspond to the most common locations for dermal melanocytoses and blue nevi (see Ch. 112). Langerhans cell precursors appear within the epidermis during the first trimester and are detectable as early as 40 days’ EGA. These cells can be distinguished by their characteristic dendritic morphology; expression of CD45, HLA-DR, and CD1c; and high levels of ATPase

COMPARATIVE FEATURES OF PREMATURE, NEWBORN, AND ADULT SKIN

Newborn

Adult

Skin thickness

0.9 mm

1.2 mm

2.1 mm

Epidermal surface

Vernix (gelatinous)

Vernix

Dry

Epidermal thickness

~20–25 microns

~40–50 microns

~50 microns

Stratum corneum thickness

4–5 microns

9–10 microns

9–15 microns

5–6 cell layers

>15 cell layers

>15 cell layers

Spinous cell glycogen content

Abundant

Little or none

Little or none

Melanocytes

High number of cells; few mature melanosomes

Similar number of cells to young adult; low melanin production

Numbers decrease with age; melanin production dependent on skin type, body area

Dermal–epidermal junction

All known adult antigens expressed; fewer and smaller desmosomes

Structural features and antigens similar to those of the adult

Well-developed adhesive structures; large number of antigens expressed

Boundary with reticular dermis

Present but not marked

Present but not marked

Marked

Size of collagen fiber bundles

Small

Small

Small

Cellular density

Abundant

Abundant

Moderately abundant

Boundary with the subcutis

Marked

Marked

Marked

Size of collagen fiber bundles

Small

Small to intermediate

Large

Papillary dermis • • •

CHAPTER

2

Skin Development and Maintenance

Premature

Reticular dermis • • •

Abundant

Moderately abundant

Sparse

Elastic fibers

Cellular density

Sparse; tiny with immature structure

Small size and immature structure; distribution similar to adult

Large in reticular dermis, small and immature in papillary dermis; form network

Hypodermis

Well-developed fatty layer

Well-developed fatty layer

Well-developed fatty layer

Table 2.1 Comparative features of premature, newborn, and adult skin. Reproduced with permission from Schachner LA, Hansen RC (eds). Pediatric Dermatology, 4th edn. London: Mosby, 2011.  

activity. CD1a, Langerin, and Birbeck granules are expressed by 13 weeks’ EGA. The density of Langerhans cells in fetal skin remains low early in gestation and increases to typical adult levels during the third trimester. Merkel cells, highly innervated neuroendocrine cells involved in mechanoreception, are initially identified within the epidermis during the first trimester. These cells are detected as early as 8–12 weeks’ EGA in palmoplantar epidermis, and slightly later in interfollicular skin. Merkel cells are identified by the presence of cytoplasmic dense core granules and the expression of cytokeratin 20 and neuropeptides. These cells are found in the basal layer of the epidermis, are often associated with appendages and nerve fibers, and are particularly dense on volar skin. The developmental origin of Merkel cells has been the subject of longstanding controversy, but genetic fate mapping studies have demonstrated that mammalian Merkel cells are derived from an epidermal rather than neural crest lineage7.

Clinical Relevance Several inherited pigmentary disorders result from genetic defects that lead to abnormal migration and proliferation of neural crest-derived melanocyte precursors (melanoblasts). Piebaldism and Waardenburg syndrome are characterized by achromic patches of skin on the central forehead, central abdomen, and extremities. This distribution pattern reflects the failure of melanocyte precursors to survive, proliferate, or travel to the distal points of their embryonic migration pathway. A number of different causative genes leading to this phenotype have been identified, including those encoding transcription factors (e.g. microphthalmia-associated transcription factor [MITF], PAX3, SOX10, SNAI2) as well as membrane receptors and their ligands (e.g. endothelin-3, endothelin B receptor, KIT receptor)8 (see Ch. 66). The endothelin B receptor is found on common melanoblast/ganglion cell precursors in the developing neural crest, explaining both the Hirschsprung disease and the pigmentary abnormalities that are associated with defects in this receptor or its ligand.

DEVELOPMENT OF THE DERMIS AND SUBCUTIS The specification of dermal mesenchymal cells is a complex process that is incompletely understood. Unlike the epidermis, which is derived exclusively from the ectoderm, the origin of the dermis varies depending on the body site. As noted above, the dermal mesenchyme of the face and anterior scalp (as well as the underlying muscle and bone) is derived from neural crest ectoderm, thereby explaining the facial dysmorphia in the neurocristopathy Waardenburg syndrome. On the other hand, the dermal mesenchyme of the back originates from the dermomyotome of the embryonic somite, and the dermal mesenchyme of the extremities and ventral trunk is thought to arise from the lateral plate mesoderm. By 6–8 weeks’ EGA, presumptive dermal fibroblasts are situated under the developing epidermis9. However, at this developmental stage, there is no distinct demarcation between the cells that will give rise to the dermis and those that will give rise to musculoskeletal components. Although embryonic dermal cells are capable of synthesizing collagens (e.g. types I, III and IV) and some microfibrillar components, these proteins are not yet assembled into complex fibers. Of note, the ratio of collagen III to collagen I is 3 : 1, the reverse of what is seen in the adult dermis. The demarcation between the dermis and underlying skeletal condensations becomes distinct at approximately 9 weeks’ EGA. By 12–15 weeks’ EGA, progressive changes in matrix organization and cell morphology distinguish the fine weave of the papillary dermis located directly beneath the epidermis from the thicker, deeper reticular dermis. At this stage, the collagen proteins produced by fibroblasts start to assemble into collagen fibers, which continue to accumulate in the reticular dermis during the second and third trimesters. Electron microscopy can first detect definitive elastic fibers at approximately 22–24 weeks’ EGA. As development progresses, the gelatinous, proteoglycan-rich, cellular dermis of the embryo is modified to the more rigid, fibrous, paucicellular dermis characteristic of adult skin. By the end of the second trimester, the dermis shifts from a non-scarring to a

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scarring form of wound repair. At birth, the dermis is still thinner and more cellular than is adult dermis. The basic pattern of the dermal vasculature is discernible by the end of the first trimester. This pattern, however, undergoes extensive remodeling in utero and is not fully mature until after birth. Numerous molecular controls are involved in the regulation of angiogenesis, including the vascular endothelial growth factor (VEGF) family as well as the tyrosine kinase receptors Tie-1 and Tie-2 and their stimulatory (Ang-1) and inhibitory (Ang-2) angiopoietin ligands (see Ch. 102). Nerve networks are formed by the mid to late first trimester but also undergo significant remodeling during later development and early postnatal life. Cutaneous nerves and vessels follow a similar pattern, with nerves dictating arterial differentiation and branching10. Accumulation of subcutaneous fat begins during the second trimester and continues through the third trimester, when distinct lobules separated by fibrous septae are formed.

Clinical Relevance Mutations in genes that encode dermal structural proteins (e.g. collagens, elastic fibers) and the enzymes that process them underlie multiple forms of Ehlers–Danlos syndrome (characterized by skin hyperextensibility and fragility with poor wound healing) and cutis laxa (featuring lax, redundant skin). Genetic defects in regulatory proteins important for extracellular matrix development can lead to abnormalities in the skin and other organs. For example, mutations in the latent transforming growth factor-β (TGF-β) binding protein-4 gene (LTBP4) underlie a form of cutis laxa associated with severe pulmonary, gastrointestinal, and genitourinary malformations. The absence of LTBP4, an extracellular matrix protein that controls the bioavailability of TGF-β, leads to defective elastic fiber assembly in many types of tissues. Another disorder characterized by abnormal dermal development is Goltz syndrome (focal dermal hypoplasia), an X-linked dominant disorder characterized by areas of dermal hypoplasia with fat herniation/ hamartomas in a distribution following the lines of Blaschko (thought to reflect pathways of epidermal development) as well as skeletal defects and mucosal papillomas. Goltz syndrome is caused by mutations in PORCN, an effector of the Wnt signaling pathway11. It is likely that epidermal PORCN regulates Wnt signaling to the developing dermis, explaining the distribution of dermal hypoplasia along the lines of Blaschko.

DEVELOPMENT OF THE DERMAL–EPIDERMAL JUNCTION The dermal–epidermal junction (DEJ) mediates adhesion between the basal keratinocytes and the dermis and provides resistance against shearing forces on the skin (see Ch. 28). The DEJ develops from a simple, generic basement membrane in the embryo to a highly complex, multilayered structure in the second-trimester fetus. The embryonic DEJ consists of a lamina densa and a lamina lucida, and it is composed of molecules that are common to all basement membranes (e.g. type IV collagen, laminin, heparan sulfate, proteoglycans)12. The DEJ becomes progressively more complex, and skinspecific components of the DEJ start to appear after the embryonic–fetal transition at 8 weeks’ EGA, coincident with the onset of epidermal stratification. By 12 weeks’ EGA, almost all of the structures characteristic of the mature DEJ are in place (see Ch. 28). Hemidesmosomes, anchoring filaments, and anchoring fibrils are synthesized by basal keratinocytes, with type VII collagen-containing anchoring fibrils localizing to the sublamina densa; laminin 332 and the bullous pemphigoid antigens are also expressed. As development progresses, the flat embryonic DEJ acquires the rete ridges and dermal papillae that characterize the adult DEJ.

Clinical Relevance

60

Epidermolysis bullosa (EB) is a heterogeneous group of genetic disorders characterized by blister formation due to mechanical fragility of the skin. EB can result from mutations in genes that encode several different components of the DEJ13. The specific protein affected, as well as the degree to which it is altered, determine disease severity, depth of bulla formation, and involvement of extracutaneous tissues (see Ch.

32). Analogously, the pathogenesis of a number of autoimmune blistering diseases involves autoantibodies targeting components of the DEJ (see Chs 29–31).

DEVELOPMENT OF SKIN APPENDAGES (ADNEXAE) Skin appendages include eccrine, apocrine, and sebaceous glands as well as the hair and nails. Normal development of these structures depends on tightly regulated interactions and signaling between the early dermis and epidermis; disruption of either component or their communications leads to aberrant development. Despite the differences in the structure and function of the various types of cutaneous appendages, the developmental processes that regulate their formation are remarkably similar14 (see Fig. 68.1).

Hair Follicle Development The genetics and complex dermal–epidermal signaling that occur in appendageal development are best understood in hair follicle induction. Follicle formation is initiated by signals from the dermis that direct the embryonic epidermis to form focal thickenings, called placodes (see Fig. 68.2)15. Placodes are first seen on the scalp and face between 10 and 11 weeks’ EGA; they subsequently develop in a caudal and then in a ventral direction. The epidermal placodes instruct the underlying dermal cells to condense and form the presumptive dermal papilla. The dermal papilla then directs the keratinocytes of the placode to proliferate and extend deeper into the dermis, thereby forming the hair germ (Fig. 2.4; see Fig. 68.2). By 12–14 weeks’ EGA, the base of the developing hair follicle surrounds the presumptive dermal papilla, forming the hair peg (see Figs 2.4 & 68.2). The superficial portion of the developing hair follicle has two distinct bulges. The more superficial bulge consists of the developing sebaceous gland, whereas the deeper bulge represents the insertion point of the future arrector pili muscle and the location of the presumptive follicular stem cells (Fig. 2.3D). Hair follicles undergo further maturation during the second trimester, forming seven concentric cell layers (from outer to inner): outer root sheath; inner root sheath, composed of Henle’s and Huxley’s layers and a cuticle; and then the hair shaft cuticle, cortex and medulla (see Fig. 68.5). The hair canal is fully formed by 18–21 weeks’ EGA, and hair shafts begin growing shortly thereafter. The hairs continue to grow until 24–28 weeks’ EGA, when they leave the active growing phase (anagen) and enter the short-lasting degenerative phase (catagen) and subsequently the resting phase (telogen). The follicles then start the second hair cycle by re-entering anagen; new hairs grow and push out the first group of telogen hairs (exogen), which are shed into the amniotic fluid (see Fig. 68.4). Hair cycling through anagen, catagen, and telogen continues throughout life, but the hair cycles for individual follicles become asynchronous after birth. The third hair cycle is initiated perinatally, leading to the shedding of the second wave of fine lanugo hair follicles. Most hairs become thicker and coarser with subsequent growth cycles, leading to vellus and then adult-like terminal hairs on the scalp and in the eyebrows. Many genes important for hair follicle development and cycling have been identified (see Ch. 68). Sonic hedgehog (SHH), a signaling molecule secreted by cells of the developing hair follicle, is required for the maturation of the dermal papilla and for the progression of the follicle placode to the peg hair stage. SHH also appears to be critical in mediating the transition from telogen to anagen during postnatal hair cycling. Members of the Wnt, bone morphogenetic protein (BMP), and fibroblast growth factor (FGF) families of signaling molecules are also important in hair follicle development and cycling. Transcription factors with roles in follicular differentiation have also been identified, including HOXC13 and FOXN1. Sebaceous gland development parallels follicular development. The presumptive sebaceous gland is first seen at around 13–16 weeks’ EGA as the most superficial bulge on the developing hair follicle. The outer proliferative layer of the sebaceous gland generates lipogenic cells that progressively accumulate lipid/sebum until they are terminally differentiated, at which time they disintegrate and release their products into the upper portion of the hair canal, contributing to the vernix caseosa.

Fig. 2.4 Fetal development of the hair follicle. The hair follicle begins as a small epithelial thickening (placode) that induces a dermal condensate. Reciprocal signaling between these two structures subsequently directs the patterning and growth of a complex, multi-cylindrical, hair-forming structure with an associated dermal papilla, sebaceous gland, and apocrine gland.  

Lanugo hair Epidermis

Sebaceous gland

Dermal condensate

Arrector pili muscle

Dermis

Isthmus

Hair bulb (=epithelium)

Bulge

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Skin Development and Maintenance

FETAL DEVELOPMENT OF THE HAIR FOLLICLE

Subcutis Dermal papilla (=mesenchyme) Apocrine gland

Both maternal hormones and androgen production from the “fetal zone” of the developing adrenal gland (which involutes postnatally) result in sebaceous gland hypertrophy and increased sebum production during the second and third trimesters.

Nail Development Fingernail development begins at 8–10 weeks’ EGA and is completed by the fifth month of intrauterine development. The flat, rectangular surface of the future nail bed on the dorsal digital tips is first demarcated by folds visible at 8–10 weeks’ EGA. The nail bed on the dorsal digit is the first skin structure to keratinize, at around 11 weeks’ EGA; keratinization begins distally and then continues toward the proximal nail fold. A wedge of ectoderm invaginates obliquely into the mesenchyme along the proximal end of the early nail field, forming the proximal nail fold by 13 weeks’ EGA. The presumptive nail matrix cells, which will later produce the differentiated nail plate, are found ventral to the proximal nail fold. A differentiated nail plate emerges from under the proximal nail fold during the fourth month of gestation and grows distally to completely cover the nail bed by the fifth month. Toenails develop by a similar process that occurs ~4 weeks later than the fingernails.

Eccrine and Apocrine Sweat Gland Development Like hair and nails, palmoplantar eccrine sweat glands begin to develop during the first trimester and are fully developed by the second trimester. Sweat gland development starts with the formation of large mesenchymal bulges or pads (analogous to the paw pads of other mammals) on the palms and soles between 55 and 65 days’ EGA. Parallel ectodermal ridges are induced in the epidermis overlying these pads between 12 and 14 weeks’ EGA. The curves and whorls formed by these ridges result in characteristic dermatoglyphics (fingerprints), which can be seen on the digit tips by the fifth month of gestation. Unlike most other mammals, the mesenchymal pads in the human fetus regress by the third trimester. Beginning between 14 and 16 weeks’ EGA, individual eccrine gland primordia bud along the ectodermal ridges at regularly spaced intervals. The buds elongate as cords of cells that enter the pad mesenchyme. By 16 weeks’ EGA, glandular structures form at the terminal portion of the buds and secretory and myoepithelial cells appear. Canalization

of the dermal component of the eccrine duct is also complete by 16 weeks’ EGA; this occurs via a loss of the desmosomal adhesions along the innermost ectodermal surfaces, with concomitant maintenance of the adhesion between duct cells and the gland walls. Canalization of the epidermal component of the duct is not complete until 22 weeks’ EGA. Interfollicular eccrine glands and apocrine glands begin to form during the fifth month of gestation. Like sebaceous glands, apocrine glands typically arise from the upper portion of a hair follicle, whereas interfollicular eccrine glands originate independently. Glandular cords of cells elongate during the ensuing weeks, and by 7 months’ EGA the clear cells and mucin-secreting dark cells characteristic of apocrine glands can be visualized. Apocrine glands function transiently during the third trimester and subsequently become quiescent in the neonate. In contrast, eccrine glands mature and begin functioning postnatally.

Clinical Relevance Ectodermal dysplasias are a large, heterogeneous group of genetic disorders characterized by developmental abnormalities in two or more major ectodermal appendages – hair, teeth, nails, and sweat glands; other ectodermal structures (e.g. sebaceous glands) can also be affected16 (see Ch. 63). Hypohidrotic ectodermal dysplasia (HED) is a relatively common type of ectodermal dysplasia that affects the sweat glands (hypohidrosis), hair (hypotrichosis), and teeth (hypodontia). HED is caused by mutations in genes encoding components of the ectodysplasin A (EDA) signaling pathway, which is critical for the initiation of sweat gland, hair follicle, and tooth morphogenesis. Underlying mutations can occur in the genes encoding the EDA ligand, EDA receptor (EDAR), or EDAR-associated death domain (an intracellular adaptor protein that functions in EDAR signaling). Mutations in EDA are responsible for the X-linked form of HED (XLHED), which leads to “full-blown” disease in affected males and areas of involved skin following the lines of Blaschko in heterozygous females. Because the underlying defect is in a soluble ligand that is only required for a brief period during the initiation of appendage formation, XLHED is a prime target for protein therapy. Encouragingly, studies in mice and dogs have demonstrated an almost complete correction of the XLHED phenotype upon prenatal or neonatal treatment with recombinant EDA protein17,18.

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Clinical trials with recombinant EDA protein for the treatment of infants with XLHED are ongoing. In addition to mutations in genes that are required for appendage development, ectodermal dysplasias can also be caused by mutations in genes that are required for epidermal development19. In these instances, abnormal appendages result from disruption of cross-talk between the developing epidermis and dermis. Mutations in TP63, a gene that is required for epidermal morphogenesis, can cause several types of ectodermal dysplasia, including the ankyloblepharon– ectodermal dysplasia–cleft lip/palate (AEC) and ectrodactyly–ectodermal dysplasia–cleft lip/palate (EEC) syndromes (see Ch. 63). The phenotypic differences between AEC and EEC are explained by underlying mutations in separate regions of TP63, which affect different functions and isotypes of the p63 protein. Genetic defects in the Wnt signaling pathway, which is critical for appendageal development, underlie conditions ranging from hereditary hypotrichosis simplex to onycho-odonto-dermal dysplasia and Schöpf– Schulz–Passarge syndrome (see Fig. 55.6)20. The basal cell nevus (Gorlin) syndrome is caused by mutations in the PTCH tumor suppressor gene that result in overactivation of the sonic hedgehog (SHH) signaling pathway (see Fig. 107.8), which has important roles in neurologic and anterior–posterior axis development as well as hair follicle formation21. This explains the broad range of developmental anomalies, including craniofacial and skeletal defects, and the propensity for medulloblastomas, odontogenic keratocysts, and multiple basal cell carcinomas (BCCs) to arise (see Ch. 108).

SKIN STEM CELLS Stem cells are present in each self-renewing tissue and are responsible for maintaining and repairing the tissue in which they reside. These

somatic stem cells have two defining properties: (1) the ability to produce daughter cells that can differentiate to renew or repair the tissue; and (2) the ability to produce a new stem cell (self-renewal). The epidermis, dermis, appendages, and melanocytes are each maintained by different lineage-specific stem cells. Stem cells often reside in a protective niche microenvironment that provides necessary signaling factors. During periods of homeostasis, stem cells generally divide very infrequently, a feature believed to protect them from acquiring mutations during cell cycle progression. After an injury, however, stem cells can divide more rapidly as part of wound healing. One distinguishing characteristic of stem cells is that they can be maintained in culture virtually indefinitely. For example, a subset of epidermal basal cells forms highly proliferative colonies that can be passaged long-term in vitro; referred to as holoclones, they presumably represent stem cells22. Holoclones can reconstitute epidermis in vitro, and they have been utilized as skin grafts for the treatment of burns and inherited skin disorders (see below). Within the skin, stem cells that maintain the epidermis and hair follicles have been most extensively studied. The properties of different cutaneous stem cells, including their molecular markers, are summarized in Table 2.2.

Epidermal Stem Cells The human epidermis renews itself every 40–56 days23. This constant turnover is mediated by epidermal stem cells, which reside in the basal layer24. Stem cells comprise a small percentage of the basal epidermis, although their precise location and number is unclear. There is conflicting evidence regarding whether palmoplantar epidermal stem cells are found at the bottom or top of rete ridges, with more protection from environmental stress in the former location. Similarly, there are two competing models – hierarchical and stochastic – to account for proliferative, undifferentiated cells in the basal epidermis (Fig. 2.5)22.

CUTANEOUS STEM CELLS

Location (niche)

Tissue regeneration in homeostasis

Tissue regeneration in injury repair

  Interfollicular epidermis

Basal layer

Interfollicular epidermis

Hair follicle Sebaceous gland Interfollicular epidermis

Delta 1, MCSP, α6* and β1 integrins, LRIG1; low levels of CD71

  Hair follicle**

Bulge†

Hair follicle

Hair follicle Sebaceous gland Interfollicular epidermis

Keratin 15, α6 and β1 integrins, CD200, PHLDA1, follistatin, frizzled homolog 1, LGR5; low levels of CD24, CD34‡, CD71, CD146, SOX9

  Sebaceous gland§

At or near the bud of the sebaceous gland

Sebaceous gland

Sebaceous gland

Blimp1

Merkel cell§

Touch domes of hairy skin

Interfollicular epidermis

Interfollicular epidermis

α6 integrin*, keratin 17, CD200, GLI1, SOX2, ATOH1

Melanocyte§

Lower bulge and sub-bulge region¶

Hair matrix and epidermal melanocytes

Hair matrix and epidermal melanocytes

Pax3, TYRP2; negative for KIT, tyrosinase, TYRP1

Eccrine gland lumen§

Suprabasilar eccrine duct

Eccrine luminal cells

Acral epidermis

Keratins 15, 18, & 19

Stem cell

Markers

Keratinocyte

*Also expressed by basal keratinocytes. **Additional stem cell populations identified within the hair follicle in mice include LGR6-positive cells in the central isthmus and LRIG1-positive cells in the upper isthmus, both of which contribute to the interfollicular epidermis and sebaceous glands during homeostasis.

†Within the outer root sheath just below the sebaceous gland, at or near the site of insertion of the arrector pili muscle. ‡Upregulated in mouse bulge cells. §Studied primarily in mice. ¶Lowest permanent portion of the hair follicle.

Table 2.2 Cutaneous stem cells. ATOH1, atonal homolog 1; CD24, glycoprotein involved in cell adhesion and signaling; CD34, marker of hematopoietic progenitor cells and endothelial cells; CD71, transferrin receptor; CD146, melanoma cell adhesion molecule/MUC18/S-Endo-1 antigen; CD200, transmembrane glycoprotein that delivers a negative immunoregulatory signal (may be involved in maintaining immune tolerance); GLI1, GLI family zinc finger 1; LGR5/6, leucine-rich repeatcontaining G protein-coupled receptor 5/6; LRIG1, leucine-rich repeats and immunoglobulin-like domains 1 (epidermal growth factor receptor antagonist and regulator of stem cell quiescence); MCSP, melanoma-associated chondroitin sulfate proteoglycan; PHLDA1, pleckstrin homology-like domain, family A, member 1; SCA1, stem cell antigen 1; SOX2/9, SRY (sex determining region Y)-box 2/9; TYRP, tyrosinase-related protein.  

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HIERARCHICAL AND STOCHASTIC MODELS OF KERATINOCYTE STEM CELLS

$ Hierarchical model

% Stochastic model

EPU

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2

No distinct EPUs

Clonal behavior in the epidermis

Skin Development and Maintenance

Cornified layer Granular layer Spinous layer Basal layer None

+

+

or

or

+

Rapid symmetrical

Cell divisions

*

Infrequent Asymmetrical

Stem cell†

Transitamplifying cell†

Progenitor cell†

+

or

or

+

+

*

Rare divisions Reserve cells

Frequent divisions Maintains tissue

Terminally differentiating cell

*† Stem cells divide more rapidly during wound repair. Restricted to the basal layer of the epidermis.

Fig. 2.5 Hierarchical and stochastic models of keratinocyte stem cells. These two models have been utilized to explain the behavior of stem cells and other proliferative cells in the basal epidermis. A In the hierarchical model, stem cells undergo infrequent asymmetric division, generating one new stem cell and one daughter transit amplifying (TA) cell. Unlike stem cells, TA cells divide frequently and symmetrically, producing two TA cells; in this model, they constitute the majority of basal keratinocytes. After a few rounds of division, TA cells withdraw from the cell cycle and move suprabasally, initiating the keratinocyte terminal differentiation program. Each epidermal stem cell and its progeny form a vertical column of progressively differentiating cells, which is known as an epidermal proliferation unit (EPU). B In the stochastic model, epidermal stem cell divisions are rare and usually asymmetrical, generating a new stem cell and a committed progenitor cell; however, random symmetric divisions resulting in either two stem cells or two progenitor cells also occasionally occur. In this model, committed progenitor cells make up the bulk of the basal layer, where they divide frequently to maintain the epidermis by producing either a new progenitor and a cell that leaves the basal layer to undergo terminal differentiation or two cells of either fate. It is possible that aspects of both stem cell models occur in the skin, depending on location or external stimuli, explaining why experimental evidence exists to support both models. Retention of a DNA label (e.g. 5-bromo-2-deoxyuridine or tritiated thymidine) is utilized as an in vivo marker of stem cells based on their slowly cycling nature.  

Hair Follicle Stem Cells The hair follicle bulge, which is located in the outer root sheath just deep to the sebaceous gland and adjacent to the arrector pili muscle attachment site, is thought to harbor hair follicle stem cells (Fig. 2.6). The bulge represents the lowest portion of the hair follicle that does not regress during the catagen phase, and it contains morphologically undifferentiated cells25. Hair follicle bulge cells are slow-cycling and have a high clonogenic potential in culture, as well as being selfrenewing and multipotent. In vivo, they typically proliferate only when the hair follicle re-enters the anagen phase, in order to regenerate the bottom two-thirds of the follicle. In addition, appendageal stem cells of the bulge and eccrine duct provide an important ectodermal reserve, allowing reconstitution of the surface epidermis after wounding. The bulb region at the base of the anagen follicle contains selfrenewing, rapidly dividing, clonogenic matrix cells that produce the hair shaft and inner root sheath. These cells have the properties of stem cells, except they regress along with the rest of the lower follicle during

catagen. Whether bulb cells are best described as transit amplifying cells or committed progenitor cells is a matter of debate.

Stem Cell Plasticity Under homeostatic conditions, epidermal and hair follicle stem cells only contribute to their respective tissues of origin. However, bulgederived keratinocytes can also contribute to the repair of the interfollicular epidermis in response to injury25. Although most bulge-derived cells survive only transiently within the healing epidermis, a subpopulation of bulge cells can transdifferentiate into long-living epidermal stem cells26. Similarly, epidermal stem cells can contribute to new hair follicle formation in the center of large wounds27. Like many organs, the skin and subcutaneous fat contain rare cells that can produce sphere-like colonies when provided with multiple growth factors in 3-dimensional culture. These sphere cells represent pluripotent stem cells that can be directed to produce many tissue types, and their use for autologous stem cell therapies is being explored.

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KERATINOCYTE AND MELANOCYTE STEM CELLS Hair shaft

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Overview of Basic Science

1

Epidermis

Dermis

PRENATAL DIAGNOSIS OF GENODERMATOSES Bulge

Epidermal stem cells Hair follicle stem cells Melanocyte stem cells (in lowest permanent portion of hair follicle)

Fig. 2.6 Keratinocyte and melanocyte stem cells. Note that the bulge is continuous with the outer root sheath.  

However, the in situ location and function of these cells in the skin remains unknown. Along the same lines, cells in adult mammals are far more “flexible” in their potential to form other cell types than previously thought. Some cell types, particularly bone marrow cells, have the potential to incorporate themselves into diverse tissues (e.g. epidermis, heart) and adopt the fates of resident cells, contributing progeny to the tissue. Induced pluripotent stem (iPS) cells are somatic cells (e.g. fibroblasts) that have been reprogrammed into an embryonic stem cell-like state28; these cells can be stimulated to differentiate into a variety of cell types, including keratinocytes. Thus, adult cells, including different skin cell types, may be capable of dedifferentiating into pluripotent stem cells.

Stem Cell-Based Therapy for Genetic Skin Disease Stem cells have been utilized in several strategies for gene therapy of heritable skin diseases (Fig. 2.7). Treatment via delivery of genecorrected stem cells has the advantage of continuous protein synthesis in the skin, but it may carry a risk of oncogenesis, especially with retroviral vectors. In a pilot study, laminin-β3-deficient skin from a man with junctional EB was corrected by transplantation of stem cellenriched epidermal grafts transduced ex vivo with a retroviral vector encoding normal LAMB3 cDNA. The treatment resulted in expression of functional laminin 332 and an absence of blistering in the corrected epidermis, both sustained over several years of follow-up. Clinical trials are also ongoing to investigate the value of bone marrow-derived stem

64

cell transplantation as a systemic treatment for the extremely severe recessive dystrophic form of EB (RDEB). In an initial report29, bone marrow transplantation after total or partial myeloablation resulted in substantial proportions of donor cells in the skin, increased collagen VII deposition at the dermal–epidermal junction, and variably decreased blistering in children with RDEB. Other investigators are studying alternative sources of stem cells for the treatment of EB, including allogeneic mesenchymal stromal/stem cells and autologous iPS cells derived from revertant keratinocytes30.

Many genodermatoses are incompatible with survival to term or are associated with significant morbidity or even mortality after birth, making prenatal diagnosis desirable. In the early 1980s, fetal skin biopsy obtained at 19–22 weeks’ EGA via ultrasound guidance became the first technique available for prenatal diagnosis of inherited skin diseases. Epidermolytic ichthyosis and generalized severe junctional EB were the first diseases diagnosed prenatally by light and/or electron microscopy of fetal skin biopsies. As the causative genes for many genodermatoses have been discovered, DNA-based testing using material obtained from chorionic villus sampling (10–12 weeks after the last menstrual period/8–10 weeks’ EGA) or amniocentesis (14–16 weeks after the last menstrual period/12– 14 weeks’ EGA) has largely replaced fetal skin biopsy, as these techniques can be performed earlier and pose less risk to the mother and fetus. With these approaches, the pathogenic mutation(s) must be identified in family members prior to prenatal testing. Preimplantation genetic diagnosis allows for prenatal diagnosis before the embryo is implanted and pregnancy begins. This technique requires the use of in vitro fertilization. One or two cells are taken from the embryo at the blastocyst (6- to 10-cell) stage. The cellular DNA is amplified using PCR and analyzed for the known family mutation(s); unaffected embryos are then selected for uterine implantation. For X-linked disorders, sex determination has been utilized both in conjunction with specific genetic analysis and to identify embryos of a particular sex for selective transfer. Preimplantation genetic diagnosis obviates the need to terminate a pregnancy with an affected fetus. However, it has several disadvantages compared to chorionic villus sampling or amniocentesis, including higher cost, technical difficulties (e.g. contamination by extraneous DNA), and a low rate of completed pregnancies.

SIGNIFICANCE OF SKIN DEVELOPMENT IN POSTNATAL LIFE Understanding skin development is essential for the appropriate diagnosis and management of congenital skin disorders. This knowledge is useful far beyond the neonatal period, however, as many of the regulatory pathways central to development are recapitulated in postnatal life. For example, hedgehog signaling through PTCH and SMO is critical for postnatal hair cycling as well as hair follicle development. In addition to the germline PTCH mutations that result in basal cell nevus syndrome, somatic PTCH mutations represent a pathogenic factor in sporadic BCCs. Knowledge of this pathway enabled the development of SMO inhibitors (e.g. vismodegib) to treat locally advanced and metastatic BCC and explains the hair loss caused by these drugs. Similarly, identifying the mechanisms controlling angiogenesis and wound healing during intrauterine development holds promise for developing new cancer treatments and wound care interventions. Furthermore, elucidating the mechanisms of cutaneous stem cell formation and maintenance will help to design potential stem cell-based therapies. Thus, advancing the understanding of skin embryology and stem cell biology may lead to life-saving or life-enhancing medical advancements.

Fig. 2.7 Strategies for stem cell therapy of genetic skin disorders. A One strategy is to isolate epidermal stem cells from a patient, correct the genetic defect in vitro (e.g. using a viral vector), and graft epithelial sheets containing the corrected stem cells back onto the patient. B Gene therapy could also potentially utilize induced pluripotent stem (iPS) cells, which are generated from somatic cells (e.g. fibroblasts). The genetic defect could be corrected via homologous recombination in these cells, which would then be differentiated into keratinocytes and grafted onto the patient. C A third strategy involves the use of hematopoietic stem cells (HSC). Upon systemic administration (following conditioning), allogeneic HSC cells have the capacity to home to the skin (e.g. to sites of injury in patients with epidermolysis bullosa) and produce differentiated progeny cells that provide the needed skin protein (e.g. collagen VII). D Finally, therapeutic genes could be directly administered to patients via a virus or another vector. To achieve permanent correction, the vector must target stem cells that could supply the protein to the skin. Courtesy, Maranke I Koster, PhD.  

% Induced pluripotent stem cells Patient somatic cells (e.g. fibroblasts) Reprogram somatic cells into iPS cells

$ Epidermal stem cells

Patient epidermal stem cells

Patient iPS cells

Transduce stem cells with virus encoding therapeutic gene ( )

Correct genetic mutation by homologous recombination ( )

Corrected epidermal stem cells

Corrected iPS cells

Expand and graft back onto patient

CHAPTER

2

Skin Development and Maintenance

STRATEGIES FOR STEM CELL THERAPY OF GENETIC SKIN DISORDERS

Differentiate corrected iPS cells into keratinocytes

& Hematopoietic stem cells

Corrected keratinocytes

Obtain hematopoietic stem cells from matched donor Expand and graft back onto patient Hematopoietic stem cells

' Direct delivery Virus or other vector encoding a therapeutic gene; for long-lasting effects, could target stem cells that would supply the skin with the required protein

Expand and deliver systemically to patient following conditioning

REFERENCES 1. Koster MI, Roop DR. Mechanisms regulating epithelial stratification. Annu Rev Cell Dev Biol 2007;23: 93–113. 2. Holbrook KA. Structure and function of the developing human skin. In: Goldsmith LA, editor. Physiology, Biochemistry, and Molecular Biology of the Skin. New York: Oxford University Press; 1991. p. 63–110. 3. Holbrook KA, Odland GF. Structure of the human fetal hair canal and initial hair eruption. J Invest Dermatol 1978;71:385–90. 4. Akiyama M, Shimizu H. An update on molecular aspects of the non-syndromic ichthyoses. Exp Dermatol 2008;17:373–82. 5. Kalia YN, Nonato LB, Lund CH, et al. Development of skin barrier function in premature infants. J Invest Dermatol 1998;111:320–6. 6. Adameyko I, Lallemend F, Aquino JB, et al. Schwann cell precursors from nerve innervation are a cellular origin of melanocytes in skin. Cell 2009;139:366–79. 7. Van Keymeulen A, Mascre G, Youseff KK, et al. Epidermal progenitors give rise to Merkel cells during embryonic development and adult homeostasis. J Cell Biol 2009;187:91–100. 8. Dessinioti C, Stratigos AJ, Rigopoulos D, et al. A review of genetic disorders of hypopigmentation: lessons learned from the biology of melanocytes. Exp Dermatol 2009;18:741–9. 9. Smith LT, Holbrook KA. Development of dermal connective tissue in human embryonic and fetal skin. Scan Electron Microsc 1982;(Pt 4):1745–51. 10. Mukouyama YS, Shin D, Britsch S, et al. Sensory nerves determine the pattern of arterial differentiation and

11.

12.

13.

14. 15. 16. 17.

18. 19.

blood vessel branching in the skin. Cell 2002;109:693–705. Wang X, Reid Sutton V, Omar Peraza-Llanes J, et al. Mutations in X-linked PORCN, a putative regulator of Wnt signaling, cause focal dermal hypoplasia. Nat Genet 2007;39:836–8. Fine JD, Smith LT, Holbrook KA, et al. The appearance of four basement membrane zone antigens in developing human fetal skin. J Invest Dermatol 1984;83:66–9. Uitto J, Richard G. Progress in epidermolysis bullosa: genetic classification and clinical implications. Am J Med Genet C Semin Med Genet 2004;131C: 61–74. Mikkola ML. Genetic basis of skin appendage development. Semin Cell Dev Biol 2007;18:225–36. Millar SE. Molecular mechanisms regulating hair follicle development. J Invest Dermatol 2002;118: 216–25. Priolo M, Lagana C. Ectodermal dysplasias: a new clinical-genetic classification. J Med Genet 2001;38:579–85. Casal ML, Lewis JR, Mauldin EA, et al. Significant correction of disease after postnatal administration of recombinant ectodysplasin A in canine X-linked ectodermal dysplasia. Am J Hum Genet 2007;81:1050–6. Gaide O, Schneider P. Permanent correction of an inherited ectodermal dysplasia with recombinant EDA. Nat Med 2003;9:614–18. Koster MI, Roop DR. p63 and epithelial appendage development. Differentiation 2004;72:364–70.

20. Shimomura Y, Agalliu D, Vonica A, et al. APCDD1 is a novel Wnt inhibitor mutated in hereditary hypotrichosis simplex. Nature 2010;464:1043–7. 21. High A, Zedan W. Basal cell nevus syndrome. Curr Opin Oncol 2005;17:160–6. 22. Alcolea MP, Jones PH. Lineage analysis of epidermal stem cells. Cold Spring Harb Perspect Med 2014;4:a015206. 23. Barrandon Y, Green H. Three clonal types of keratinocyte with different capacities for multiplication. Proc Natl Acad Sci USA 1987;84:2302–6. 24. Halprin KM. Epidermal “turnover time” – a re-examination. Br J Dermatol 1972;86:14–19. 25. Cotsarelis G. Epithelial stem cells: a folliculocentric view. J Invest Dermatol 2006;126:1459–68. 26. Brownell I, Guevara E, Bai CB, et al. Nerve-derived sonic hedgehog defines a niche for hair follicle stem cells capable of becoming epidermal stem cells. Cell Stem Cell 2011;8:552–65. 27. Ito M, Yang Z, Andl T, et al. Wnt-dependent de novo hair follicle regeneration in adult mouse skin after wounding. Nature 2007;447:316–20. 28. Zhao R, Daley GQ. From fibroblasts to iPS cells: induced pluripotency by defined factors. J Cell Biochem 2008;105:949–55. 29. Wagner JE, Ishida-Yamamoto A, McGrath JA, et al. Bone marrow transplantation for recessive dystrophic epidermolysis bullosa. N Engl J Med 2010;363:629–39. 30. Uitto J, Bruckner-Tuderman L, Christiano AM, et al. Progress toward Treatment and Cure of Epidermolysis Bullosa: Summary of the DEBRA International Research Symposium EB2015. J Invest Dermatol 2016;136:352–8.

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SECTION 1 OVERVIEW OF BASIC SCIENCE

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Molecular Biology Thomas N. Darling

INTRODUCTION Advances in molecular biology are rapidly changing our understanding of skin biology and disease. Increased knowledge is being translated into new molecular diagnostic tests that are transforming the clinical practice of dermatology. Molecular analyses are currently being employed to diagnose genodermatoses1, cutaneous infections2, melanomas3,4, lymphomas5, and inherited6 or autoimmune blistering disorders7. In order to use these tests in a prudent manner, dermatologists nowadays have an even greater need to understand basic concepts in molecular biology. This knowledge is also leading to the development of new targeted therapies, many of which require determination of the molecular basis for disease in order to appropriately implement treatment8. In addition, molecular analysis is being used to screen for drug efficacy and susceptibility to adverse reactions to certain medications9. The goal of this chapter is to outline basic concepts and methodologies of molecular biology and to give practicing dermatologists a fundamental appreciation of what their colleagues are doing in the laboratory and how their own clinical practice is changing as molecular approaches are implemented into patient care.

EXPERIMENTAL TECHNIQUES Tissue Processing Dermatologists are accustomed to placing a biopsy specimen in formalin followed by paraffin embedding and staining tissue sections with hematoxylin and eosin. However, for molecular analysis, this is just one of several possible starting points for tissue processing (Fig. 3.1). TISSUE PROCESSING

Placing the sample in formalin (for light microscopy) or glutaraldehyde (for electron microscopy) before processing and sectioning allows the sample to be analyzed histologically in a variety of ways, including by routine staining, immunohistochemistry, or in situ hybridization. The advantage of this approach is that the cells are preserved in a very stable fashion, with well-preserved architecture, for later analysis. Disadvantages are that the cells are no longer living and the fixation procedure can place limits on the methods that can be used to analyze DNA, RNA, and protein from cells of interest. Nonetheless, PCR analysis of DNA is increasingly being performed on formalin-fixed, paraffinembedded tissue, especially for infectious diseases and detection of gene rearrangements in lymphoproliferative disorders. In order to preserve molecules in a more native state, the specimen may be snap frozen. Cryosections prepared from such samples have lower quality tissue architecture than do permanent sections from formalin-fixed, paraffin-embedded tissues, but this form of tissue preservation may allow for better analysis of DNA, RNA, and protein. One may also directly process fresh or frozen tissue with buffers and reagents in order to extract DNA, RNA, and protein from the whole tissue. The advantage of performing extractions from whole tissue is that the DNA, RNA, and protein will be fresh and of high quality. The disadvantage is that the extracts will not be from a pure population of cells. Another approach is to culture cells obtained from fresh tissue. The desired lineage of cells (e.g. keratinocytes, fibroblasts, immunocytes, endothelial cells) can be propagated in vitro by employing selective culture media and isolation techniques. Culturing cells allows one to obtain more cells than in the original sample, and then the cells can be exposed to various conditions. However, the culturing process may change fundamental characteristics of the cells, so that they do not accurately represent the cells in vivo. One method for isolating a pure population of cells from a tissue section is to use laser microdissection (Fig. 3.2). A laser is used to LASER CAPTURE MICRODISSECTION

Excised tissue

Transfer cap Transfer film

Fixed

Frozen

Tissue section Glass slide

Fresh Laser beam

Electron microscopy

Tissue culture

Light microscopy

Flow cytometry and FACS

Laser microdissection

Transfer film Glass slide Extraction

Fig. 3.2 Laser capture microdissection. Laser capture microdissection is one method of microdissection used to selectively procure individual cells or clusters of cells from tissue sections. A cap coated with a thermoplastic transfer membrane is placed directly over the tissue section. The operator visually identifies the cells of interest and triggers a low-energy infrared laser to melt the transfer film onto cells of interest. The cap is then lifted from the section to separate the selected cells from the remainder of the tissue section.  

DNA

Protein

Fig. 3.1 Tissue processing. A tissue sample can be processed in various ways for the analysis of DNA, RNA, or protein. FACS, fluorescence-activated cell sorting.  

66

RNA

Advances in the methods used to analyze DNA, RNA, and proteins are transforming the practice of medicine and research. Traditional methods to assess individual genes or proteins are complemented by advanced techniques allowing genomic or proteomic analysis of populations of cells or individual cells. The functions of genes and encoded proteins are determined in vivo using animal models that allow control of when and where genes are expressed. Molecular techniques enable gene-based therapies in which genes are corrected, supplemented, or suppressed for therapeutic benefit. The future promise of precision medicine depends on our ability to use and develop these techniques for molecular analysis.

flow cytometry, polymerase chain reaction, PCR, DNA sequencing, reverse transcription PCR, RT-PCR, fluorescence in situ hybridization, FISH, nucleic acid arrays, proteome, transgenic mice, gene-based therapy

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ABSTRACT

non-print metadata KEYWORDS:

66.e1

The Foundations of Molecular Techniques for Analyzing DNA, RNA, and Protein The concepts behind molecular biology are simple and unifying. In general, they consist of extracting the molecules of interest, amplifying them to measurable amounts, and detecting them. Polymerase chain reaction (PCR) is a standard technique for amplifying DNA (Table 3.1;

POLYMERASE CHAIN REACTION

Purpose Amplify a specific piece of DNA from a complex mixture



Requirements Need to know sequence of the DNA of interest (at least of its ends)



Underlying concepts Double-stranded DNA can be melted or unwound to single strands with increased temperature (Fig. 3.4A); when cooled, the single strands come back together to form double strands (hybridize) if the nucleotide sequences are complementary* • During the hybridization process, when two complementary strands bind to each other, the A nucleotides on one strand bind to T nucleotides on the complementary strand, whereas C nucleotides of one strand bind to G nucleotides on the complementary strand, and vice versa • In PCR, short DNA strands called oligonucleotide primers are designed for hybridization to specific sequences in the template DNA •

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retrieve or cut individual cells from a section on a slide while the specimen is viewed with a microscope10. An advantage of microdissection is that a very pure population of cells is obtained that has been precisely identified under the microscope. One limitation is that the total number of cells isolated is relatively low, as each cell has to be individually captured by the laser. Consequently, the procedures to extract DNA, RNA and protein from these pure (but few) cells have to be robust. A way to isolate and analyze cells in suspension is to use flow cytometry (Fig. 3.3)11. Cells are passed individually in a stream through a set of lasers and electronic detectors capable of measuring multiple parameters for each cell. As an initial step, cells are typically incubated with fluorescent-labeled antibodies that recognize cell-surface markers so that a heterogeneous population of cells can be characterized on a cell-by-cell basis for levels of expression of each marker. Fluorescence-activated cell sorting (FACS), which utilizes an electrostatic deflection system, can also be used to obtain pure populations of cells with specific desired characteristics. Flow cytometry permits the measurement of multiple characteristics of individual cells at a rapid rate. However, with the exception of peripheral blood or bone marrow cells, a significant limitation is that it requires the cells to be in suspension. Recently, the ability to analyze 40 or more parameters for each cell has been accomplished by combining the principles of flow cytometry and elemental mass spectrometry in what is call mass cytometry11a.

Outline of method (Fig. 3.4) Oligonucleotide primers are designed to hybridize to specific sequences at each end of the DNA of interest. These primers are added to a reaction vessel mixture containing the template DNA along with a thermostable DNA polymerase, the nucleotides dATP (A), dTTP (T), dGTP (G) and dCTP (C), and buffer • The reaction vessel is placed in a thermal cycler, which controls the temperature of the reaction through many cycles • Each cycle contains the following steps: (1) denaturation; (2) primer annealing or primer hybridization; (3) primer extension; and (4) repeat of the complete cycle of PCR 30–40 times •

Benefits PCR is simple and rapid Because the PCR product is exponentially increased, it is extremely sensitive in amplifying low amounts of DNA. Each cycle increases the number of PCR products twofold. The total number of PCR products after n cycles will be 2n

• •

Limitations/errors

Positive (red) and negative (clear) cells in suspension that have been preincubated with fluorescentlabeled antibodies Direction of flow Lasers

Because of its high degree of sensitivity, laboratory contamination of a DNA sample by trace amounts of the PCR product can cause misleading results • Primers used for PCR can anneal to sequences that are similar, but not identical, to the sequence of interest. This can be countered with “hot start” techniques (DNA polymerase prevented from acting until after first denaturation step) or nested PCR (after the PCR amplification, repeat the PCR amplification using a second set of primers that hybridize to sequences inside first set of primers). In nested PCR, the second set of primers will only hybridize to correct PCR products resulting from the first PCR amplification • DNA polymerase occasionally incorporates incorrect nucleotides. For sequencing by PCR, polymerases that possess proofreading enzymatic activity can be used. This also allows the generation of even longer PCR products, up to ~50 kb long •

FLOW CYTOMETRY

Detectors

Experimental applications DNA can be amplified either for detection of a specific sequence or for cloning that sequence • PCR can be used to label DNA with fluorescent or radioactive nucleotides • PCR can be used for rapid haplotype analysis •

  

  

Electrostatic deflection system (FACS)

Modifications/alternatives Quantitative PCR – the amount (number of copies) of a specific piece of DNA can be quantified by a variety of methods utilizing PCR. A relatively simple and high-throughput method, called real-time quantitative PCR, uses a specially designed thermal cycler that measures the amount of PCR product formed after each cycle (see Fig. 3.6B). The higher the level of DNA, the earlier the product can be detected. This can be used to measure genetic changes in cancer such as gene amplification, to quantify the amount of residual cancer following treatment, or to quantify the amount of a pathogen in a sample. Modifications of this procedure can allow discrimination of gene polymorphisms • Southern blot, in situ hybridization, comparative genomic hybridization •

Sorted cells

Fig. 3.3 Flow cytometry. Cells in suspension, pre-incubated with fluorescentlabeled antibodies, flow single file in a liquid stream through lasers. Detectors measure the fluorescence intensities of each cell. In fluorescence-activated cell sorting (FACS), the single cells are divided into charged droplets that are separated into different tubes based on the marker(s) of interest as they pass through an electrostatic deflection system. Flow cytometry is commonly employed in the evaluation of patients with cutaneous B- and T-cell lymphomas.  

*Hybridization actually forms the basis of several techniques in molecular biology, as the two strands can be DNA:DNA (PCR, Southern blotting), DNA:RNA (Northern blotting, in situ hybridization), or RNA:RNA.

Table 3.1 Polymerase chain reaction.  

67

DNA SEQUENCING

POLYMERASE CHAIN REACTION

SECTION

Determine the sequence or order of nucleotides (A, G, C, T) in a stretch of DNA



Double-strand DNA

Requirements

Overview of Basic Science

1

Purpose

$

The piece of DNA to be sequenced can be either a PCR product or a cloned piece of DNA present in a plasmid, but it should be pure



Step 1 denaturation

Underlying concepts Chain termination (Sanger sequencing), or a variation thereof, is a standard method for DNA sequencing • In chain termination, the extension of a new strand of DNA is stopped by the addition of an analogue of dATP, dCTP, dGTP or dTTP (ddATP, ddCTP, ddGTP or ddTTP, respectively) to the sequencing mixture. When the DNA polymerase incorporates the analogue nucleotide instead of the correct normal nucleotide, DNA synthesis is terminated because the polymerase is no longer able to link to the next nucleotide • Gel electrophoresis is used to separate the different sizes of DNA fragments that result from chain termination synthesis. The DNA fragments are forced to travel through a gel using an electric current; the smaller molecules are less impeded by the gel and travel faster than larger molecules* •

Step 2 annealing

Step 3 extension

%

Outline of method (Fig. 3.5)

Heat

Heat

Template DNA

35 cycles 235=34 billion copies F+R primers 1st cycle dNTP 1 polymerase 2 =2 copies

An oligonucleotide primer hybridizes to the DNA to be sequenced and DNA polymerase synthesizes a second complementary strand • The synthesis of the second strand is interrupted randomly by the incorporation of the fluorescent nucleotide analogues (ddATP, ddGTP, ddCTP, ddTTP), and the DNA fragments containing this final nucleotide analogue can be identified because each of the four ddNTPs is labeled with a different color fluorochrome • The different DNA fragments are electrophoresed through a polyacrylamide gel or capillary tubes • The different-length DNA strands terminating with different fluorochrome-labeled nucleotide analogues pass a fluorescence detector and indicate the order of the DNA sequence •

Heat

2nd cycle 22=4 copies

Fig. 3.4 Polymerase chain reaction. A Each cycle contains the following steps: (1) denaturation – separate the two strands of DNA by heating to >90°C; (2) primer annealing or primer hybridization – allow the oligonucleotide primers to bind to the template DNA by cooling to 50–65°C; (3) primer extension – DNA polymerase catalyzes the addition of nucleotides (A, G, C, T) that are complementary to the DNA template, beginning with the primer and extending 3′ at the optimal temperature of 72°C; and (4) repeat the complete cycle 30–40 times. B Each cycle increases the number of PCR products twofold. The total number of PCR products after n cycles will be 2n times the original amount. F+R, forward and reverse.  

Benefits The fluorescent chain termination method is able to rapidly sequence large amounts of DNA with automated analysis of results



Limitations/errors Routinely sequence only ~500 bases per run Difficulty with G+C-rich regions • DNA must be high-quality • •

Experimental applications Determine previously unknown sequence Confirm sequence following the cloning of a DNA fragment of interest and other manipulations

• •

Modifications/alternatives Pyrosequencing Next-generation sequencing (massively parallel sequencing; see Table 54.6)



68

Fig. 3.4)12. The PCR-amplified DNA, typically 50 to 2000 base pairs in size depending on the primers designed for a particular sequence, can be detected in a gel using an intercalating dye that fluoresces with ultraviolet light. The nucleotide sequence can then be determined via automated fluorescence sequencing techniques (Table 3.2; Fig. 3.5). This simple and relatively inexpensive approach is still widely used. However, it is being supplanted by massively parallel sequencing, also known as next-generation sequencing, in which millions of fragments of DNA are sequenced in a single run (see Table 54.6)13. RNA is also easy to purify, but it is much more readily degraded than DNA. Therefore, a typical first step in the analysis of RNA is to convert it into DNA using reverse transcription (RT; Table 3.3; Fig. 3.6A). Following RT, the complementary DNA (cDNA) can be amplified by PCR, as described above. The technique of RT-PCR has also been modified to allow accurate quantitation of very low levels of mRNA14. Because the amount of PCR product is monitored throughout each cycle of amplification, this technique is referred to as “real-time” quantitative PCR (Fig. 3.6B). The amount of protein is a complex balance of synthesis and degradation controlled at multiple steps, including efficiency of protein



*Gel electrophoresis is used in many molecular biologic techniques to separate DNA, RNA or protein molecules of differing sizes.

Table 3.2 DNA sequencing.  

translation and post-translational modifications that affect protein stability. One method used to measure levels of protein is referred to as a Western blot (Table 3.4; Fig. 3.7); it is also known as an immunoblot because an antibody is employed to detect the protein of interest. In addition to measuring protein levels, Western blot analysis can determine the size of proteins and can reveal whether there are different forms of the protein15. Another method commonly used to measure protein levels is an enzyme-linked immunosorbent assay (ELISA; see Table 3.4)16. An ELISA can provide very exact quantitation of protein levels and may be less expensive and easier to perform than a Western blot.

REVERSE TRANSCRIPTION PCR

DNA SEQUENCING

Purpose To amplify mRNA by PCR, the mRNA is first converted to DNA (called complementary DNA or cDNA), followed by PCR amplification of a specific region of the cDNA to detectable levels



A

T

C

G

A reaction dATP dTTP dCTP dGTP ddATP

T reaction dATP dTTP dCTP dGTP ddTTP

C reaction dATP dTTP dCTP dGTP ddCTP

G reaction dATP dTTP dCTP dGTP ddGTP

CA CACCGAAT CACCGA CACCGAATACAT CACCGAA CACCGAATACATCT CACCGAATA CACCGAATACA

CACCG C CACCGAATACATCTG CAC CACC CACCGAATAC CACCGAATACATC

Requirements Starting material can be total cellular RNA (including ribosomal, transfer and messenger RNA [mRNA]) or purified mRNA



Underlying concept In order to facilitate studies of RNA, many techniques that study RNA first convert the RNA to cDNA with an enzyme called reverse transcriptase, an RNA-dependent DNA polymerase



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Fixed end CACCGAATACATCTG

Outline of method (Fig. 3.6a) Reverse transcriptase can convert mRNA to cDNA by three different methods, depending on the primer used for the initial RT step*. (1) Random hexamer primers contain six nucleotides (6-mer) that have all possible sequence combinations of the dA, dG, dC and dT nucleotides (46 possible combinations). These random hexamers will hybridize to the corresponding complementary sequences in the sample RNA. (2) Oligo dT primers contain only dT nucleotides and hybridize to the complementary string of dA nucleotides that are present at the end of mRNA molecules (poly A tail). (3) The third choice is a primer that will only hybridize to a specific mRNA sequence • After the mRNA has been converted to cDNA, primers that can hybridize to specific sequences are added and PCR amplification is performed as described in Table 3.1 •

3' G T C T A C A T A A G C C A 5' C

CACCGAATACATCTG CACCGAATACATCT CACCGAATACATC CACCGAATACAT CACCGAATACA CACCGAATAC CACCGAATA CACCGAAT CACCGAA CACCGA CACCG CACC CAC CA C

Sequencing gel

CACCGAATACATCTG 80

390

Automated fluorescent sequencing scan

Benefits As for PCR, RT-PCR is simple and rapid RT-PCR is extremely sensitive in detecting low levels of mRNA transcripts

• •

Fig. 3.5 DNA sequencing. An oligonucleotide primer hybridizes to the DNA to be sequenced and DNA polymerase synthesizes a second complementary strand. The synthesis of the second strand is interrupted randomly by the incorporation of fluorescent nucleotide analogues (ddATP, ddGTP, ddCTP, ddTTP). The DNA fragments containing this final nucleotide analogue can be identified because each of the four ddNTPs is labeled with a different color fluorochrome. Gel electrophoresis is used to separate the different sizes of DNA fragments. The different-length DNA strands terminating with different fluorochrome-labeled nucleotide analogues pass a fluorescence detector and indicate the order of the DNA sequence (see Table 3.2 for more details).  

Measuring Spatial Distribution Within Tissues In populations of cells, PCR, RT-PCR, and Western blots are useful for measuring DNA, RNA, and protein, respectively. However, in order to identify which cells are responsible for observed characteristics, particularly within complex tissues such as skin, tissue sections are analyzed by fluorescence in situ hybridization (FISH) for DNA or RNA and immunohistochemistry for protein. FISH is based on hybridization (as in PCR), but it relies on the use of fluorescently labeled nucleic acid probes that are complementary to the desired DNA or RNA sequences to be detected in tissue sections (Table 3.5, Fig. 3.8). The probes are hybridized to the target sequences in the tissue and then the slide is examined using fluorescence microscopy17. FISH can be used to detect DNA deletions or amplifications in cancer cells. Normally, two fluorescent signals appear in each nucleus for an autosomal gene, but in cancer cells there may be only one signal, indicating a deletion, or three or more signals if there is amplification. An alternative to FISH is microarray-based comparative genomic hybridization (array CGH) (see Fig. 113.28). Whereas FISH typically only probes up to 4 genetic regions in one tissue section, array CGH tests for copy number aberrations across the genome. A disadvantage of array CGH, relative to FISH, is that array CGH assesses a population of cells rather than individual nuclei. In other words, FISH may detect genetic abnormalities in a minority of cells that could be masked by normal surrounding cells in array CGH. Array CGH and FISH may be used to supplement routine histopathology in the analysis of ambiguous melanocytic lesions, soft tissue tumors (see Fig. 117.19), and myelogenous leukemia involving the skin3,4.

Limitations/errors If the RNA sample is contaminated with DNA (that contains the gene of interest), a PCR product may be amplified from the DNA even though the corresponding mRNA for the gene is not present. To control for this, RT-PCR of RNA samples can be done with and without reverse transcriptase • RNA is fragile and the absence of a specific mRNA transcript may result from RNA degradation during and following extraction. RNA quality can be tested by gel electrophoresis and/or by RT-PCR of housekeeping genes (genes expressed by all cells) •

Experimental applications The mRNA gene transcripts can be amplified for subsequent cloning or sequencing • The mRNA gene transcripts (instead of the gene) could be analyzed for the presence of mutations •

Modifications/alternatives Quantitative RT-PCR – by adding a reverse transcription step to quantitative PCR (see Table 3.1), the levels of mRNA transcripts from genes of interest can be quantified. • Correspondingly, samples that contain less mRNA transcripts will require more PCR cycles before the exponential phase. Therefore, different RNA samples can be precisely compared by measuring the number of PCR cycles (x axis) needed to produce a defined amount of PCR product (y axis) (Fig. 3.6B) • By carefully designing the primers, quantitative RT-PCR can be used to measure the amounts of alternatively spliced forms of a gene • Alternative methods to measure RNA levels include digital PCR, in which the sample is partitioned into individual nucleic acids, and Northern blots •

*In addition to the RNA, the reaction mixture contains the reverse transcriptase enzyme, an oligonucleotide primer, dNTPs, and buffer.

Table 3.3 Reverse transcription PCR (RT-PCR).  

69

WESTERN BLOT

REVERSE TRANSCRIPTION PCR

SECTION

$

Purpose

Reverse transcription

Western analysis can measure the size and the amount of protein present in a sample



Overview of Basic Science

1

Requirements Gene-specific priming

RNA

AAAAA(A)n

AAAAA(A)n

cDNA

Oligo d(T) priming

N6 N6 Random hexamer priming Quantitative real-time PCR

Fluorescent intensity

1

Underlying concepts Polyclonal antibodies that react to several epitopes on a protein antigen are obtained by injecting a protein into an animal and later isolating the antibodies from the serum immunoglobulin fraction • Monoclonal antibodies that react to only one epitope of a protein antigen are obtained by immunizing mice (or rats, rabbits, or chickens) with the antigen, then fusing the animal’s reactive lymphocytes with an immortal myeloma cell line to create cells that are able to provide antibodies indefinitely • A secondary antibody is used to detect the protein or the primary antibodies bound to the protein. These detection antibodies can be visualized by attaching a fluorescent probe or by attaching an enzyme that can produce either light or a color by enzymatic action on a substrate •

AAAAA(A)n

%

Western analysis requires an antibody that is specific for the protein of interest (i.e. does not cross-react with other proteins)



PCR amplification

Amplification

Outline of method (Fig. 3.7) 0

A solubilized protein mix is separated on a polyacrylamide gel and transferred electrophoretically to a membrane. The membrane is then soaked in a buffer containing the antibody. Bound antibody is detected by a chromogenic or chemiluminescent assay



–1

Benefits Western analysis is a simple and sensitive method to detect and quantify proteins present in a complex mixture • Western analysis can determine the molecular weight of a specific protein relative to standard controls •

–2 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 Cycle

Fig. 3.6 Reverse transcription PCR (RT-PCR). A Reverse transcriptase can convert mRNA to cDNA in three different ways, depending on the primer used for the initial RT step: (1) random hexamer primers; (2) oligo dT primers; and (3) gene-specific primers (see Table 3.3 for more details). After the mRNA has been converted to cDNA, primers that can hybridize to specific sequences are added and PCR amplification is performed as described in Table 3.1. B Real-time PCR is able to precisely measure the amount of PCR product continuously (y axis) after each cycle (x axis). Each plotted line represents the amount of PCR product present in a different sample. In samples that initially contain more mRNA gene transcripts, real-time PCR will demonstrate an exponential increase in PCR product earlier, after fewer PCR cycles.  

Limitations/errors Proteins are subject to degradation during extraction. The use of protease inhibitors in the extraction buffer helps to prevent degradation • To perform a Western analysis, one must possess a highly specific antibody that can recognize denatured proteins • Western blots may contain a high background of nonspecific staining. To correct this, blocking agents such as bovine serum albumin or milk protein are used • Large proteins transfer poorly from the gel to the membrane, and small proteins may transfer through the membrane without binding. Adequate transfer to the membrane can be accomplished by controlling the duration of the transfer procedure •

Experimental applications Detection, quantification, and characterization of a specific protein Identification of antibody activity to a known antigen

• •

Immunohistochemistry is used to assess the expression of proteins in tissue sections. An antibody is added to a tissue section where it binds specifically to the protein of interest. The bound antibody is usually detected based on an enzymatic reaction that generates a colored product at the site of bound antibody (see Chapter 0). Immuno­ histochemistry can be used to determine the locations and levels of expression of a protein within a tissue, including proteins that mark specific cell lineages or cell states such as differentiation, activation, proliferation, or apoptosis.

Measuring the Transcriptome and Proteome

70

There are several approaches for quantitatively analyzing the levels of expression of nearly all cellular genes. For example, RNA-seq utilizes massively parallel sequencing (see Ch. 54) to evaluate RNA samples; it can analyze levels of gene expression, gene splicing, non-coding RNA, microRNA, gene fusions, and mutations17a. Additional methods are based on the hybridization of labeled sample mRNA to known oligonucleotide or cDNA sequences (representing thousands of genes) placed on chips, beads, or glass slides (Table 3.6; Fig. 3.9)18. The level of hybridization to the nucleotide sequence of a given gene indicates how much mRNA of that gene is present. In addition to using this method to profile mRNAs (the transcriptome), modified approaches allow the measurement of differences in microRNAs or changes in genomic DNA

Modifications/alternatives Dot blot – a drop of the protein mixture is placed on a paper membrane and the protein of interest detected with antibodies, as in the Western blot. The disadvantage of this technique is that, owing to the elimination of size separation by gel electrophoresis, specific binding to the protein of correct size cannot be distinguished from nonspecific background binding to proteins • Immunoprecipitation (IP) – the specific antibody is added to the protein mixture and the resulting antibody–protein complexes are then isolated. Because proteins are not first denatured in immunoprecipitation, they can be detected in a more native configuration • IP–Western – protein–protein interactions can be studied by first immunoprecipitating the protein with one antibody, bringing down a protein complex. The protein complex is then separated on a polyacrylamide gel, followed by Western blotting to detect members of the protein complex • Enzyme-linked immunosorbent assay (ELISA) – this is a sensitive and specific method for quantifying the amount of a protein. The protein of interest is captured on a plate coated with a monoclonal antibody and other proteins are washed away. The protein is then detected using a second antibody that has been modified for detection using a colorimetric or luminescent assay • Immunohistochemistry – this is used to visualize the cellular localization of a protein. An antibody to the protein of interest is applied to a tissue section. The antibody is detected using a secondary antibody coupled to an enzyme that reacts with a substrate to produce a colored precipitate (see Ch. 0) •

Table 3.4 Western blot.  

FLUORESCENCE IN SITU HYBRIDIZATION (FISH)

WESTERN BLOT TECHNIQUE

Purpose To visualize locations and levels of specific sequences of DNA or RNA in tissue sections



Requirements Polyacrylamide gel

Gel electrophoresis

Tissue section of formalin-fixed paraffin-embedded tissue or fresh-frozen tissue • The target sequence must be known •

Underlying concepts A fluorescently labeled nucleic-acid probe hybridizes to complementary sequences in tissue sections • The signal is detected using fluorescence microscopy •

Direction of − protein transfer Polyacrylamide gel Transfer to membrane

Membrane

+ Primary antibody Secondary antibody

*

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Molecular Biology

Protein samples

Outline of method (Fig. 3.8) A probe is designed that is complementary to the target sequence and is directly or indirectly labeled with a fluorochrome • Nucleic acids in the tissue section are denatured and then the FISH probe is applied to the tissue section to hybridize to the target sequence • Unbound probe is washed away • Samples are viewed by fluorescence microscope •

Benefits Able to identify which cells exhibit a specific abnormality in DNA, such as gene deletion, amplification, or translocation • Able to determine which cells are expressing a particular gene •

Detection

Membrane

Limitations/errors Subject to interlaboratory and interobserver variability Technical issues may complicate results, such as incomplete hybridization or nonspecific binding

• •

Fig. 3.7 Western blot technique. A solubilized protein mix is separated on a polyacrylamide gel and transferred electrophoretically to a membrane. The membrane is soaked in a buffer containing antibody. The bound antibody is detected by a chromogenic or chemiluminescent assay utilizing a labeled secondary antibody (green asterisk).  

Experimental applications Identification of DNA copy number aberrations in cancer cells Determining the spatial pattern of gene expression in a tissue

• •

Modifications/alternatives Single molecule RNA FISH FISH of metaphase preparations to diagnose chromosomal abnormalities • Spectral karyotyping or multifluor FISH to detect chromosomal translocations and large deletions or duplications • PCR or RT-PCR following laser microdissection of pure cell population • Array-based comparative genomic hybridization (CGH) (see Ch. 113) • •

copy number. Changes in copy number can be determined by array CGH or single nucleotide polymorphism (SNP) arrays (see Figs 54.6 and 113.28)18a. The proteome of a cell represents all the cellular proteins that are being expressed under a particular set of conditions. Technologies that allow measurement of the proteome continue to be refined19. One technique relies on mass spectrometry, which can provide extremely accurate measurements of protein mass by ionizing the protein and measuring the “time-of-flight” through a tube to a detector on the opposite end (Table 3.7; Fig. 3.10). In most instances, the proteins are separated prior to mass spectrometry, using two-dimensional gel electrophoresis or capillary electrophoresis. This can be technically difficult and time-consuming, so mass spectrometry analysis of proteins continues to be optimized for high-throughput and quantitative analysis of proteins. Quantitation is accomplished by labeling proteins using stable isotopes to provide internal standards, or by label-free shotgun proteomic approaches that are being enhanced for greater speed and lower costs19. Another technique is the use of reverse-phase protein arrays, in which whole protein lysates are spotted onto slides and probed using antibodies to specific proteins20. The field of proteomics promises to provide a tremendous amount of information regarding cell biology and disease states.

Genetically Engineered Mouse Models Transgenic mice are commonly employed as experimental models for elucidating in vivo functions of genes21,22. The gene to be studied is microinjected into a fertilized mouse egg where it randomly integrates into the mouse genome, and is present in every cell as the egg divides

Table 3.5 Fluorescence in situ hybridization (FISH).  

and develops into a mouse (Table 3.8; Fig. 3.11). Although the gene is present in every cell, the expression of the gene can be limited or targeted to specific tissues or cell types by using a promoter/enhancer that is only expressed in a given cell. Promoters/enhancers are the portion of a gene – usually on the 5′ end of the gene or upstream of its coding region – that initiates and regulates the level of mRNA expression. For example, the promoters/enhancers that would ensure that the gene is only expressed in melanocytes would include the promoters of genes involved in melanin biosynthesis, such as tyrosinase. Although every mouse cell will contain a randomly integrated copy of this new gene, it will be expressed only in melanocytes because of the melanocyte-specific promoter/enhancer. To express a gene only in keratinocytes, a gene construct would contain a promoter/enhancer from a gene that is only expressed in keratinocytes, such as a keratin promoter21. The functional loss of a gene can also be studied by creating a “knockout” transgenic mouse (Table 3.9; Fig. 3.12)23. It is also possible to selectively knock out or delete a gene (e.g. a tumor suppressor gene) in a specific cell type or tissue as opposed to deleting the gene from all

71

Fig. 3.8 Fluorescence in situ hybridization (FISH). A tissue section on a microscope slide is fixed and permeabilized. The nucleotides on the section (yellow) and the fluorescently labeled (asterisks) probes (dark pink) are denatured; then the probes are added to the section to hybridize with complementary sequences. Unbound probe is washed away and the tissue is examined by fluorescence microscopy. Normally, two fluorescent signals appear in each nucleus for an autosomal gene, but in cancer cells there may be only one signal, indicating a deletion, or three or more signals if there is amplification. Here, a normal nucleus contains two green signals and two dark pink signals for two separate autosomal genes whereas a tissue section from an angiosarcoma that was formalinfixed and paraffin-embedded shows multiple separate signals using a MYC break-apart probe (the probe consists of two flanking sequences in which variable breakpoints have been observed) instead of only two copies of the two signals attached to one another. FFPE, formalin-fixed, paraffin-embedded.  

FLUORESCENCE IN SITU HYBRIDIZATION (FISH)

SECTION

1

Overview of Basic Science

Permeabilize and denature

Hybridize to probe

* * * * * * * *

Gene of interest

Fluorescence microscopy

Tissue section on microscope slide

Angiosarcoma − tissue section (FFPE)

Normal cell − interphase nucleus

NUCLEIC ACID ARRAYS

Purpose To profile the mRNA expression of thousands of genes in one experiment



Requirements Total RNA or mRNA from samples (larger amounts than required for RT-PCR)



Underlying concepts Hybridization to DNA – the same principle of hybridization applies as in PCR (described in Table 3.1), except that many different genes are being evaluated simultaneously. DNA is attached to beads, chemically synthesized on a surface at thousands of specific locations, or spotted onto glass slides (Fig. 3.9). If cells are expressing mRNA of the corresponding gene, labeled cRNA prepared from mRNA in those cells will hybridize and generate a signal intensity related to its level of expression



Outline of method (Fig. 3.9) RNA is reverse transcribed to generate cDNA. In vitro transcription of the cDNA in the presence of biotinylated nucleotides yields biotin-labeled cRNA. Labeled cRNA molecules are then hybridized to small DNA fragments attached to beads or on a chip. The samples are stained with streptavidin phycoerythrin, the streptavidin binding the biotin on the cRNA and the phycoerythrin generating a fluorescent signal. Usually, the patterns of gene expression of two samples are compared, such as normal versus tumor or treated versus untreated • Alternatively, oligonucleotide arrays can be used. Using this approach, the RNA is directly labeled with either fluorescent or radioactive nucleotides, and hybridized to oligonucleotides on a slide or membrane. When using radioactive probes, the samples are hybridized to separate microarrays. If the mRNA samples to be compared are labeled with differently colored fluorescent probes, the two samples can be hybridized to the same array simultaneously • A scanner measures the intensity of the signals at each spot and computer software determines those genes over- and underexpressed in one sample compared to the other •

Benefits Thousands of genes can be rapidly and quantitatively profiled in one experiment



Limitations/errors Genes expressed at low levels may not be detected For some genes, the cRNA may not hybridize under the conditions used • The RNA must be of very high quality • •

Experimental applications Microarray analysis can be used to profile changes in gene expression The patterns of gene expression can be used to group samples

• •

Modifications/alternatives RNA-seq MicroRNA arrays • Comparative genomic hybridization (CGH) to detect differences in DNA copy number • Single nucleotide polymorphism (SNP) arrays to assess markers of genetic variation (see Fig. 54.6); useful for linkage analysis, including genome-wide association studies (GWAS; see Fig. 54.7) • •

72

Table 3.6 Nucleic acid arrays.  

NUCLEIC ACID ARRAYS

$ Expression bead array

% Gene chip microarray

& Glass slide microarray: comparative hybridization

CHAPTER

Cells

Cells

mRNA

mRNA

Control cells (e.g. melanocytes)

Test cells (e.g. melanoma cells)

mRNA extraction

Cy5

Reverse transcription

cDNA

In vitro transcription

B B

Hybridization

cDNA

Biotin-labeled nucleotides B

B B

B

Biotin-labeled nucleotides B

mRNA

Labeling with fluorescent dye

Cy5-labeled cDNA

mRNA

Cy3

Molecular Biology

3

Cy3-labeled cDNA

B

Biotin-labeled cRNA Biotin-labeled cRNA Fluorescent streptavidin Fluorescent streptavidin B B

Address

B

B

Probe

Beads loaded with 50 bp gene-specific probes

Gene chip with up to 1.4x106 DNA probe sets

Slide with ~40 000 unique DNA probes

Signal detection and computer analysis

Fig. 3.9 Nucleic acid arrays. A In the expression bead array, RNA is extracted from cells and reverse transcribed to generate cDNA (see Fig. 3.6, Table 3.3). In vitro transcription of the cDNA in the presence of biotinylated nucleotides yields biotin-labeled cRNA. Labeled cRNAs bind to their respective 50-base probes that are linked to separate beads using additional nucleotides as an address to decode the gene. Fluorescent streptavidin is added which strongly binds to biotin. The fluorescent intensities on different beads are related to the amount of cRNA and the latter is a reflection of the level of expression of mRNA by specific genes. Usually, the patterns of gene expression of two samples are compared, such as normal versus tumor or treated versus untreated. B In the gene chip microarray, labeled cRNA molecules are hybridized to small DNA fragments chemically synthesized on a surface, with the surface containing thousands of specific sequences at different locations. C In a third approach using glass slides, two samples can be labeled with differently colored fluorescent probes (e.g. Cy5, Cy3) that are hybridized to an oligonucleotide array simultaneously (see Table 3.6 for more details). Arrays can also be used to analyze DNA rather than RNA; examples include single nucleotide polymorphism (SNP) arrays and array comparative genomic hybridization (CGH) (see Chs 54 & 113).  

cells in the mouse (Fig. 3.13)23. A further refinement is to trigger deletion of the gene from a specific tissue at a particular point in time, including during development24. One advantage of these inducible systems, as compared to gene deletion in all mouse cells, is that it may more faithfully mimic how gene deletion occurs in a specific tissue of a patient and thereby contributes to a phenotype such as tumors in those tissues. Another advantage is that gene deletion in all mouse cells may prevent normal mouse development, whereas selective gene deletion after development is complete will avoid this problem. Finally, selective gene deletion limited to specific target tissues provides a less complicated and cleaner animal model with fewer secondary effects resulting from gene deletion in tissues not being targeted. In addition to the use of tamoxifen for temporal control of Cre expression (see Fig. 3.13), the “Tet-On/Off” system can be used to address the problem of embryonic death when a particular gene is deleted.

Gene-Based Therapy for Skin Diseases Gene-based therapy is a therapeutic approach that holds future promise as a treatment for skin diseases25. In gene-based therapy, DNA or RNA is manipulated in order to add or correct a gene in the cells of a target tissue with the goal of achieving a therapeutic effect (Table 3.10). This

therapy may be directly administered to the patient’s skin in vivo, but there are concerns regarding safety and the potential for genetic alteration of the germline. Therefore, ex vivo techniques are being developed in which cells are grown from a skin sample, treated in vitro, and grafted back onto the patient (see Fig. 2.7). Because genetic manipulation of stem cells may result in long-term engraftment and stable benefits26, they are often preferred. However, the number of stem cells that can be obtained from adult tissues is limited, so there is considerable interest in gene therapy utilizing induced pluripotent stem (iPS) cells (see Ch. 2). Fibroblasts grown from human skin can be reprogrammed into iPS cells via exposure to transcription factors; these iPS cells are pluripotential and can be propagated in vitro indefinitely27. iPS cells from a patient may be genetically corrected and then differentiated into the desired cell type, such as keratinocytes, for grafting back to the patient (see Fig. 2.7). When pursuing gene therapy, there are several ways that the DNA can be manipulated. To compensate for loss-of-function of a gene, a new copy of the gene may be introduced into cells utilizing either nonviral or viral vectors. Sleeping Beauty is a non-viral, cut-and-paste DNA transposon that improves long-term gene expression, as compared to that obtained when only DNA from the gene of interest is used. However, the DNA transposon poses risks for insertional mutagenesis

73

PROTEOMICS WITH MASS SPECTROMETRY

PROTEOMICS WITH MASS SPECTROMETRY

Purpose SECTION

Overview of Basic Science

1

High-throughput analysis that allows investigators to rapidly and quantitatively assess the complex mixtures of proteins present in a cell at a given point in time



Requirements A mixture of cellular proteins, or peptides derived from these proteins, is purified from a defined population of cells and then separated into proteins and/or peptides prior to mass spectrometry



Laser

HPLC

+ +

Underlying concepts Mass spectrometry is able to measure very precisely the size or mass of proteins, peptides, or peptide fragments by giving these peptides a positive charge (ionization) and then measuring the time required for the positively charged peptide ions to move through a tube to a detector (time-of-flight)

Sample

+

+

+

Analyzer



2D gel separation

Digestion

Laser excitation

Ions

Mass analysis

Detector Detection

Outline of method (Fig. 3.10) The first step is to reduce the complexity of the mixture of cellular proteins or peptides to be analyzed, e.g. by utilizing two-dimensional gel electrophoresis and/or liquid chromatography columns • Mass spectrometry analysis is performed on the separated proteins/ peptides by ionizing them into positively charged ions using lasers or the processes of electrospray ionization and nanospray ionization. Based upon the time-of-flight of the charged ion, the peptide mass/ charge ratio can be measured and may allow the identification of the peptide sequence and the protein that contained this peptide • Tandem mass spectrometry [MS/MS] can “ion trap” a given peptide ion and then sequence the peptide by fragmenting it into its component amino acids. Bioinformatics software can use this sequence information to search protein databases for rapid protein identification •

Benefits Mass spectrometry is extremely sensitive and able to detect very small amounts of proteins/peptides



L

Intensity

S P

Q D L C D K

Amino acid sequence

m/z Mass spectrum

Fig. 3.10 Proteomics with mass spectrometry. The first step is to reduce the complexity of the mixture of cellular proteins or peptides to be analyzed. The two main methods to separate proteins/peptides from each other are two-dimensional (2D) gel electrophoresis and/or high-performance liquid chromatography (HPLC) columns. Mass spectrometry analysis is then performed by first ionizing the separated proteins/peptides into positively charged ions using lasers. Based on the time-of-flight of the charged ion, mass spectrometry can measure, record and print out the mass/charge ratio of every peptide along with signal intensity.  

Limitations/errors Better technology to reduce the complexity of protein/peptide mixtures and differentially separate the proteins/peptides in a high-throughput manner is being developed • Although mass spectrometry can measure the mass of proteins/ peptides very precisely, it is more difficult to measure the amount of protein/peptide quantitatively, and more robust techniques for quantification by mass spectrometry are being developed •

Experimental applications Mass spectrometry can be used to determine the complete set of proteins present in a defined population of cells • Because of the sensitivity of mass spectrometry analysis, it holds promise as a sensitive diagnostic tool •

Modifications/alternatives Isotope labeling approaches for quantitative mass spectrometry, including isotope-coded affinity tag (ICAT), stable isotope labeling by amino acids in cell culture (SILAC), tandem mass tags (TT), and isobaric tags for relative and absolute quantification (iTRAQ) • Label-free quantitative proteomics • Antibody protein arrays and reverse-phase protein arrays •

Table 3.7 Proteomics with mass spectrometry.  

74

because it may randomly insert near a proto-oncogene that then becomes activated28. Viral vectors can also be used to introduce DNA, including self-inactivating lentiviral and gamma retroviral vectors. These vectors integrate into the genome and have less risk of insertional mutagenesis compared to earlier retroviral vectors25. However, viral vectors do have disadvantages such as immunogenicity, broad tropism, and limited DNA packaging capacity29.

It may be possible to avoid the complication of insertional mutagenesis by correcting the endogenous gene rather than inserting a gene. Methods for targeted gene correction include the use of zinc finger nucleases (ZFNs), transcription activator-like effector nucleases (TALENs), and CRISPR-Cas9 (Fig. 3.14)30. These nucleases have sequence-specific DNA-binding modules that are linked to a DNA cleavage domain. Thus they can induce a double-strand DNA break at a specified site. The double-strand break increases the frequency of homology-directed repair, so that a co-delivered plasmid with extended homology arms can correct the existing gene. Correction of endogenous genes holds promise for treating genetically based diseases. Another therapeutic approach is to target specific mRNAs for degradation. Double-stranded RNAs, 21–23 nucleotides in length, are designed complementary to the mRNA of interest. These synthesized antisense oligodeoxynucleotides (AS-ODNs) are delivered to the cell, where they mediate sequence-specific mRNA degradation using an endogenous complex of proteins called the RNA-induced silencing complex (RISC). Ribozymes also target specific sequences based on short complementary oligonucleotides, but the catalyst for target degradation is provided by the RNA enzyme without the need for protein cofactors. However, AS-ODN and ribozyme techniques are being replaced by synthetic vectors that deliver short interfering RNA (siRNA) and microRNA (miRNA) (Fig. 3.15). These synthetic delivery vectors include lipid-based or polymer-based nanoparticles, as well as covalent delivery systems such as dynamic polyconjugates and GalNAc conjugates29. These approaches have been used successfully in the laboratory and are being tested in clinical trials.

TRANSGENIC MICE

Purpose

Requirements A transgene or gene of interest, whose biologic function is to be characterized in an animal model A regulatory region (promoter/enhancer) that will selectively express the transgene in a specific tissue • The facilities and technologies to create transgenic mice • •

Underlying concepts After injection of a transgene into a fertilized mouse egg or single-cell embryo, the transgene randomly integrates into the genome (Fig. 3.11). As the embryo undergoes many cell divisions and develops into a mouse, the integrated transgene will be present in every cell type, tissue, and organ in the mouse. Transgene expression only occurs in cells and tissues where the promoter/enhancer regulatory region is active. Any phenotypes that develop in mice expressing the transgene in the desired tissue can help us understand the biologic effects of the transgene



CHAPTER

3

Molecular Biology

Transgenic mouse models allow investigators to study the effects of a transgene (the gene of interest) on a cellular, tissue, and whole animal level. The transgene can be selectively expressed in a particular cell type or tissue by using a promoter/enhancer regulatory region that is specific for that cell type



Outline of method (Fig. 3.11) A transgene construct, defined as the transgene and a regulatory region (promoter/enhancer), is prepared for injection The transgene is microinjected into fertilized eggs (single-cell stage) and the transgene integrates into the genome, usually at a single site • These injected eggs are then implanted into a recipient mother, who then gives birth to a heterozygous “founder” mouse that can be either male or female. The founder mouse is referred to as a transgenic mouse because it only contains the transgene on one of the two paired chromosomes (e.g. only one copy of chromosome 7 contains the transgene, whereas the other chromosome 7 does not) • The founder mice are bred with normal non-transgenic mice of the same strain. The progeny mice will be both heterozygous transgenic and nontransgenic, according to Mendelian genetics • In order to derive homozygous transgenic mice that contain the transgene on both of the paired chromosomes (e.g. both copies of chromosome 7 contain the transgene), two heterozygous transgenic mice are mated. Homozygous transgenic mice will have a double dose of the transgene, which may lead to different phenotypes and biologic effects from those present in the heterozygous transgenic mice • •

Benefits Transgenic mouse models can help us understand the in vivo biologic effects of known and unknown genes when expressed in a specific tissue



Limitations/errors The precise regulation of the level of transgene expression as well as the timing of gene expression during development (turning the transgene on or off during development) have been relatively difficult. Advancements in transgenic design, including inducible promoters, have improved the regulation of transgene expression • When expressed in mouse tissues, a human transgene may have different biologic effects compared to its effects in human tissues • Classic transgenic mouse models do not allow investigators to study the biologic effects of gene mutations or deletions that result in loss of gene expression, because the technique of creating transgenic mice does not alter endogenous genes, it only adds a new transgene to each cell •

Experimental applications Transgenic mouse models of disease can be used to test the effectiveness of new therapeutic agents



Modifications/alternatives More precise control of transgene expression can be achieved with promoters/enhancers that are inducible and can be regulated (i.e. turned off and on at different time points) • Programmable nuclease systems for RNA-guided genome editing such as transcription activator-like effector nuclease (TALEN) and clustered regularly interspaced short palindromic repeat (CRISPR)/CRISPR-associated protein (Cas) (CRISPR-Cas9; Fig. 3.14) • “Knockout” transgenic mouse models (Table 3.9) allow investigators to understand the biologic effects of gene mutations and deletions that cause a loss of specific proteins •

Table 3.8 Transgenic mice.  

CONCLUSIONS In this chapter, we have presented a variety of techniques used in dermatology research and clinical practice. Some of these are new, whereas others are long established and still widely used. New technologies continue to appear and change the way research is done. These technologic advances allow experiments to be done faster and with less and less starting material. They allow the measurement of thousands of different genes or proteins in single experiments. They also automate experiments that used to require time-consuming step-by-step human involvement. To handle all the information currently produced by biologic research, advances in computers and bioinformatics are progressing along with the technologic advances. The outcome is that the pace of scientific inquiry proceeds at an increasing rate.

Advances in our scientific understanding translate into new developments in disease diagnosis and management. For dermatology, this provides hope that diseases can be diagnosed more rapidly and more reliably, and that individualized prognostic information can be provided. Therapies have been and will continue to be developed that specifically target the genetic abnormality causing the disease. In the future, therapies may be tailored to the individual, taking into consideration the genetic make-up of the individual and his or her disease process. These future possibilities are exciting.

Copyright notice Chapter 3 is US Government work in the public domain and not subject to copyright. For additional online figures visit www.expertconsult.com

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Online only content BIOINFORMATICS

SKIN GENE THERAPY $

Direct injection

%

Gene gun: Micro-projectiles

Molecular Biology

PubMed abstracts

3-D structure (MMDB)

Phylogeny (Taxonomy)

CHAPTER

3

Full-text journals online

Genomes

Nucleotide sequences

Protein sequences

eFig. 3.1 Bioinformatics. A goal of bioinformatics is to give users access to huge amounts of biologic information in a way that is easy to use and analyze. One example is Entrez produced by the National Center for Biotechnology Information (NCBI), available at http://www.ncbi.nlm.nih.gov. This retrieval system allows the user to search the biomedical literature (PubMed), nucleotide sequence database (GenBank), protein sequence database, three-dimensional macromolecular structures, and complete genome assemblies and organisms in GenBank (taxonomy). As indicated by arrows, users may access information from a single database and also integrated information from several NCBI databases. MMDB, molecular modeling database.  

eFig. 3.2 Skin gene therapy. In the direct in vivo approach, the desired gene is introduced directly into the skin as shown, either directly injected intradermally (A) or biolistically discharged into the epidermis and dermis (B). Both viral and non-viral vectors can be delivered to the skin using these in vivo approaches.  

SKIN GENE THERAPY

Grafting genetically modified keratinocytes

Gene introduction

Keratinocyte culture

eFig. 3.3 Skin gene therapy. In the ex vivo approach, keratinocytes are removed from the donor and, during ex vivo culture, the desired gene is efficiently introduced, usually with viral vectors. Skin equivalents or raft cultures containing these genetically modified keratinocytes (along with a dermal portion containing fibroblasts) are constructed and then grafted back onto the donor.  

75.e1

Fig. 3.11 Transgenic mice. A transgene construct, defined as the transgene and regulatory region (promoter/enhancer), is prepared for injection. The transgene is microinjected into fertilized eggs (single cell stage) and the transgene integrates into the genome, usually at a single site. These injected eggs are then implanted into a recipient mother, who then gives birth to a heterozygous “founder” mouse. The founder mice are bred with normal non-transgenic mice of the same strain, and then two heterozygous transgenic mice are mated.  

TRANSGENIC MICE SECTION

1

Overview of Basic Science

Transgene (+) 1 cell embryo

Injection pipet

Founder (+/–)

X Founder (+/–)

Normal (–/–)

(–/–)

(+/–)

(+/+)

(+/–)

(+/–)

(+/–)

(–/–)

(–/–)

KNOCKOUT TRANSGENIC MICE

Purpose Knockout transgenic mice have both alleles of a normal endogenous gene modified, mutated, or deleted in all cells (whole animal or targeted tissue) so that protein can no longer be produced by that gene. Therefore, knockout transgenic mice allow investigators to understand what happens to a cell or tissue when a particular gene can no longer be expressed



Requirements Murine embryonic stem cells (ES cells) that are totipotent and capable of forming and reconstituting all tissues and organs of a mouse A targeting construct defined as a defective gene that can hybridize to the normal endogenous gene in ES cells and modify or delete the targeted gene so that it is no longer able to express a functional protein

• •

Underlying concepts In knockout transgenic mice, all cells (whole animal or targeted tissue) lack the gene that has been “knocked out” and do not express any functional protein from that gene • Technology is available to selectively target and delete an endogenous gene in its normal chromosomal location in ES cells •

Outline of method (Fig. 3.12) A targeting vector that contains some sequences of the gene to be targeted is created and introduced into ES cells. This targeting vector is able to selectively hybridize to one of the endogenous alleles of a gene, and through a process known as homologous recombination, the targeting vector modifies or deletes the endogenous gene so that no normal protein is produced. ES cells that contain this defective endogenous gene can be selected for and isolated • The ES cells containing the “knocked out” gene are introduced into early mouse embryos, known as blastocysts, which are then implanted into recipient mothers. The progeny will be chimeric mice; all tissues and organs, including testes and ovaries, will contain a mixture of normal cells and cells that lack the “knockout” gene allele • The chimeric mice are next mated to normal mice. Depending on the degree of chimerism, a certain percentage of the offspring will be heterozygous, containing one normal allele and one allele that has been modified or deleted (knocked out). As described for the mating procedure in transgenic mice (see Table 3.8), the genotypes of all progeny will follow the rules of Mendelian genetics • To obtain completely “knocked out” mice, two heterozygous mice are mated. Approximately 25% of the offspring will lack a normal endogenous gene in every cell and tissue •

76

Table 3.9 Knockout transgenic mice.  

KNOCKOUT TRANSGENIC MICE

Benefits This approach yields mice that completely lack the gene product in all cells of the whole animal or targeted tissues



CHAPTER

Investigators have to ascertain that no normal gene product is being produced. It is possible that the homologous recombination process used to knock out a gene may result in a gene that encodes a mutant protein that still has biologic effects. This would make it difficult to understand the biologic effects of the gene



Experimental applications Unlike regular transgenic mice, knockout transgenic mice allow investigators to study the biologic effects of losing gene expression. This is particularly useful in the study of genes that may normally suppress cancer development (tumor suppressors); the tumor suppressor gene can be knocked out in all mouse cells in vivo, and the mechanisms of cancer development in different tissues can be studied



3

Molecular Biology

Limitations/errors

Modifications/alternatives In order to more accurately mimic in vivo situations, the gene of interest can be selectively deleted in only one organ or tissue. These conditional knockout mice allow investigators to study the effects of gene loss in a particular tissue without the complications of losing gene expression in all the other tissues (Fig. 3.13) • A similar technology is also available to delete a gene of interest at a particular time during development. Initially, the endogenous gene will be expressed normally in the knockout mice and then deleted at a later time, either during intrauterine development or after birth. This is advantageous if investigators want to study the effects of a gene that, if knocked out, would prevent embryo development • Targeted genome editing using CRISPR-Cas9 (Fig. 3.14) •

Table 3.9 Knockout transgenic mice. (cont’d)  

KNOCKOUT TRANSGENIC MICE

CONDITIONAL KNOCKOUT TRANSGENIC MICE

X Mutated gene P

Early mouse embryo

ES

Cre

IoxP

X

Cre gene linked to a tissue-specific promoter

Gene X IoxP

Target gene X flanked by IoxP sites

Chimeric (–/–)(+/+) P

X

IoxP

Cre Gene X IoxP

Normal (+/+)

Chimeric (–/–)(+/+)

In tissue expressing Cre (+/+)

(+/–)

(+/–)

(+/+)

(+/+)

(+/–)

(+/–)

IoxP

Gene X

Excision of DNA between loxP sites

Cleavage, exchange and ligation by Cre IoxP

(–/–)

Fig. 3.12 Knockout transgenic mice. A targeting vector that contains some sequences of the gene to be targeted is created and introduced into cells. This targeting vector is able to hybridize selectively to one of the endogenous alleles of a gene, and modifies or deletes the endogenous gene so that no normal protein is produced. The embryonic stem (ES) cells containing the “knocked out” gene are introduced into early mouse embryos, which are then implanted into recipient mothers. The progeny will be chimeric mice. These chimeric mice are then mated to normal mice. To obtain completely knocked out mice, two heterozygous mice are mated.

IoxP



Tissue-specific deletion of Gene X

Fig. 3.13 Conditional knockout transgenic mice. In the conditional knockout model using the Cre-lox system, a target gene can be selectively deleted in a particular organ or tissue. Cre is a site-specific DNA recombinase that catalyzes recombination between two loxP sites, resulting in cleavage, exchange, and ligation; this leads to excision (and subsequent degradation) of the DNA between the loxP sites. A transgenic mouse with the Cre gene linked to a tissue-specific promoter is mated to a transgenic mouse with two loxP sites flanking the target gene. Progeny inherit both of these constructs, and the target gene is knocked out only in cells that activate the tissue-specific promoter. By adding a ligand-binding domain to the Cre recombinase, such as one that binds tamoxifen, investigators can achieve temporal control of Cre expression in these cells. The target gene can be temporally deleted, inverted or translocated, depending on the orientation of the loxP sites.  

77

SKIN GENE-BASED THERAPY

Purpose SECTION

Overview of Basic Science

1

In skin gene-based therapy, genes are introduced and expressed, corrected, or knocked down in the skin for therapeutic purposes. Diseases that could be treated by this approach include both skin diseases and systemic diseases where skin is used as a vehicle for the systemic delivery of a needed factor or substance



Requirements A gene that is able to achieve the desired therapeutic effect when expressed in keratinocytes or other skin cells such as fibroblasts and melanocytes A delivery vector that can efficiently introduce the desired gene into cells. Both viral vectors and non-viral vectors can be used to deliver a desired gene to a target cell type. With viral vectors, the desired gene is incorporated into the genetic material of a modified virus that is able to efficiently infect target cells but is no longer able to cause disease and spread to other cells

• •

Underlying concepts Skin gene therapy is a promising field that has the potential to provide new treatments for both skin and systemic diseases There are two general approaches for introducing genes into the skin: a direct in vivo approach and an ex vivo approach • The viral vectors that have most often been used to deliver genes to skin cells are retroviral, lentiviral, and adenoviral vectors • Many issues need to be considered when choosing a vector and determining the best approach to deliver the desired gene to the skin. These include: (1) how many cells (what percentage) need to contain the gene in order to have a therapeutic effect; (2) how long the gene needs to be expressed in order to be therapeutic. In some situations, short-term or transient expression is sufficient; in other cases, long-term expression is preferable • •

Outline of method In the direct in vivo approach, the desired gene is introduced directly into the skin by injection or physical methods such as gene gun or electroporation In the ex vivo approach, keratinocytes are removed from the donor and, during ex vivo culture, the desired gene is efficiently introduced, usually with viral vectors. Skin equivalents or raft cultures containing these genetically modified keratinocytes (along with a dermal portion containing fibroblasts) are constructed and then grafted back onto the donor in the correct anatomic location • The principal advantage of the in vivo approaches is their simple straightforward nature. A disadvantage is that expression is usually transient and not long-term because selective targeting of keratinocyte stem cells is usually not feasible with in vivo approaches. Another disadvantage is that the percentage of cells containing the desired transgene may be lower than desired • In contrast, the ex vivo approaches are superior at achieving long-term expression of a desired gene in a high percentage of skin cells. During the ex vivo culture period, the desired gene could be targeted to keratinocyte stem cells • The disadvantage of the ex vivo approach is that it is much more complicated and technically demanding than the in vivo approaches • •

Benefits Genes are the therapeutic agent in this approach to treatment of cutaneous and systemic disease. As our understanding of the molecular basis of disease increases, genetic therapies will become more important • The effectiveness of skin gene therapy can be assessed in animal models •

Limitations/errors Successful skin gene therapy with long-term expression of a desired gene in a high percentage of cells has been difficult to achieve in animal models Skin gene therapy for recessive genetic skin diseases is problematic because of the development of an unwanted immune response against the normal protein • Risk of oncogenesis, especially with retroviral vectors • •

Experimental applications Treatment of genetic skin diseases Treatment of non-genetic skin diseases if a sufficient understanding of the molecular basis of the disease exists • Systemic delivery of cytokines, hormones, and growth factors • Genetic immunization • Suicide gene therapy • •

Modifications/alternatives Use of short (small) interfering RNA (siRNA) that specifically targets and silences expression of dominant-negative mutant genes (Fig. 3.15) Gene-based therapy utilizing induced pluripotent stem (iPS) cells (see Fig. 2.7) • Protein replacement therapies • Cellular therapies • •

Table 3.10 Skin gene-based therapy.  

78

Fig. 3.14 Genomic engineering mediated by CRISPR-Cas9 technology. A single-guide RNA (sgRNA) is engineered to target genomic DNA adjacent to a protospacer adjacent motif (PAM) utilizing a 20 nucleotide guide sequence. The hairpin structure recruits Cas9 to form a complex that binds to the target sequence. Cas9 catalyzes cleavage of both strands of DNA three nucleotides upstream of the PAM. A doublestrand break may be repaired by nonhomologous end joining (NHEJ) that leads to the formation of short insertions or deletions that disrupts gene function. In the presence of a DNA-repair template, homology-directed repair (HDR) may occur in order to introduce exogenous DNA at the site of the break.  

Engineered sgRNA



Cas9 nuclease

20 nucleotide guide sequence

5 – 3

Target DNA sequence Cas9-sgRNA complex Protospaceradjacent motif (PAM)

CHAPTER

3

Molecular Biology

GENOMIC ENGINEERING MEDIATED BY CRISPR-Cas9 TECHNOLOGY

Cas9-induced doublestranded DNA breaks 3 –

– 5

5 –

– 3 PAM Target DNA

Nonhomologous end joining (NHEJ)

Homology-directed repair (HDR) Repair of double-stranded DNA

Donor DNA

indel

New DNA

indel, short insertion or deletion that disrupts gene function

79

Fig. 3.15 Mechanisms of sequence-specific gene silencing via mRNA knockdown. A Short (small) interfering RNA (siRNA) is unwound and the “guide” antisense strand incorporated into an RNA-induced silencing complex (RISC) that degrades a specific target mRNA sequence. Processing of short hairpin RNA (shRNA;   B) and pre-microRNA (miRNA; C) by the Dicer enzyme can generate siRNA and miRNA, respectively.   C Endogenously produced miRNA regulates up to a third of human genes and tends to have less complementarity with target mRNA; it recruits RISC proteins and typically inhibits mRNA translation (rather than decreasing mRNA levels).  

MECHANISMS OF SEQUENCE-SPECIFIC GENE SILENCING VIA mRNA KNOCKDOWN A

B

C

Chemically synthesized short interfering RNA (siRNA) molecule

Short hairpin RNA (shRNA) precursor expressed from plasmid or viral vector DNA

MicroRNA (miRNA) precursor expressed from genomic DNA

SECTION

Overview of Basic Science

1

Processing and export from nucleus 5 3

5 3

shRNA

pre-miRNA Dicer

Dicer 5 3

3 siRNA

5

5 Duplex unwinding and strand selection

5

3

siRISC

3

3

5 miRNA

AAA3

5

5

mRNA cleavage

Ribosome

3

5

AAA3

miRISC

AAA mRNA degradation

Translational repression

REFERENCES 1. Schaffer JV. Molecular diagnostics in genodermatoses. Semin Cutan Med Surg 2012;31:211–20. 2. Swick BL. Polymerase chain reaction-based molecular diagnosis of cutaneous infections in dermatopathology. Semin Cutan Med Surg 2012;31:241–6. 3. Carless MA, Griffiths LR. Cytogenetics of melanoma and nonmelanoma skin cancer. Adv Exp Med Biol 2014;810:160–81. 4. Griewank KG, Scolyer RA, Thompson JF, et al. Genetic alterations and personalized medicine in melanoma: progress and future prospects. J Natl Cancer Inst 2014;106:djt435. 5. Deonizio JM, Guitart J. The role of molecular analysis in cutaneous lymphomas. Semin Cutan Med Surg 2012;31:234–40. 6. Fine JD, Bruckner-Tuderman L, Eady RA, et al. Inherited epidermolysis bullosa: updated recommendations on diagnosis and classification. J Am Acad Dermatol 2014;70:1103–26. 7. Otten JV, Hashimoto T, Hertl M, et al. Molecular diagnosis in autoimmune skin blistering conditions. Curr Mol Med 2014;14:69–95. 8. Miller DM, Flaherty KT, Tsao H. Current status and future directions of molecularly targeted therapies and immunotherapies for melanoma. Semin Cutan Med Surg 2014;33:60–7. 9. Rizzo AE, Maibach HI. Personalizing dermatology: the future of genomic expression profiling to individualize dermatologic therapy. J Dermatolog Treat 2012;23:161–7. 10. Legres LG, Janin A, Masselon C, Bertheau P. Beyond laser microdissection technology: follow the yellow brick road for cancer research. Am J Cancer Res. 2014;4:1–28.

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11. Jahan-Tigh RR, Ryan C, Obermoser G, Schwarzenberger K. Flow cytometry. J Invest Dermatol 2012;132:e1. 11a.  Spitzer MH, Nolan GP. Mass cytometry: single cells, many features. Cell 2016;165:780–91. 12. Garibyan L, Avashia N. Polymerase chain reaction. J Invest Dermatol 2013;133:e6. 13. Grada A, Weinbrecht K. Next-generation sequencing: methodology and application. J Invest Dermatol 2013;133:e11. 14. Bustin SA, Nolan T. Analysis of mRNA expression by real-time PCR. In: Saunders NA, Lee MA, editors. Real-time PCR: advanced technologies and applications. Norfolk, UK: Caister Academic Press; 2013. p. 51–88. 15. Nicholas MW, Nelson K. North, south, or east? Blotting techniques. J Invest Dermatol 2013;133:e10. 16. Gan SD, Patel KR. Enzyme immunoassay and enzyme-linked immunosorbent assay. J Invest Dermatol 2013;133:e12. 17. Chen AY, Chen A. Fluorescence in situ hybridization. J Invest Dermatol 2013;133:e8. 17a.  Whitley SK, Horne WT, Kolls JK. Research techniques made simple: methodology and clinical applications of RNA sequencing. J Invest Dermatol 2016;136:e77–82. 18. Villaseñor-Park J, Ortega-Loayza AG. Microarray technique, analysis, and applications in dermatology. J Invest Dermatol 2013;133:e7. 18a.  Szuhai K, Vermeer M. Microarray techniques to analyze copy-number alterations in genomic DNA: array comparative genomic hybridization and singlenucleotide polymorphism array. J Invest Dermatol 2015;135:e37. 19. Woods AG, Sokolowska I, Wetie AG, et al. Mass spectrometry for proteomics-based investigation. Adv Exp Med Biol 2014;806:1–32.

20. Solier C, Langen H. Antibody-based proteomics and biomarker research – current status and limitations. Proteomics 2014;14:774–83. 21. Schneider MR. Genetic mouse models for skin research: strategies and resources. Genesis 2012;50:652–64. 22. Avci P, Sadasivam M, Gupta A, et al. Animal models of skin disease for drug discovery. Expert Opin Drug Discov 2013;8:331–55. 23. Scharfenberger L, Hennerici T, Király G, et al. Transgenic mouse technology in skin biology: generation of complete or tissue-specific knockout mice. J Invest Dermatol 2014;134:e16. 24. Günschmann C, Chiticariu E, Garg B, et al. Transgenic mouse technology in skin biology: inducible gene knockout in mice. J Invest Dermatol 2014;134:  e22. 25. Abdul-Wahab A, Qasim W, McGrath JA. Gene therapies for inherited skin disorders. Semin Cutan Med Surg 2014;33:83–90. 26. Therrien JP, Pfützner W, Vogel JC. An approach to achieve long-term expression in skin gene therapy. Toxicol Pathol 2008;36:104–11. 27. Dinella J, Koster MI, Koch PJ. Use of induced pluripotent stem cells in dermatological research. J Invest Dermatol 2014;134:e23. 28. Skipper KA, Andersen PR, Sharma N, Mikkelsen JG. DNA transposon-based gene vehicles – scenes from an evolutionary drive. J Biomed Sci 2013;20:92. 29. Yin H, Kanasty RL, Eltoukhy AA, et al. Non-viral vectors for gene-based therapy. Nat Rev Genet 2014;15:  541–55. 30. Gaj T, Gersbach CA, Barbas CF 3rd. ZFN, TALEN, and CRISPR/Cas-based methods for genome engineering. Trends Biotechnol 2013;31:397–405.

OVERVIEW OF BASIC SCIENCE SECTION 1

Immunology Thomas Schwarz

Key features ■ The major purpose of the immune system is protection against harmful organisms. This is achieved by a rapid “primitive” reaction, called the innate immune response, and a more highly developed specific reaction, called the adaptive immune response ■ The characteristics of an adaptive immune response are specificity and the accumulation of memory, thus enabling improvement with each successive encounter with a particular antigen ■ The key event in an adaptive immune response is antigen presentation, yielding either a cell-mediated or a humoral response. The cellular response involves primarily T cells, whereas the humoral response involves B cells that ultimately mature into antibody-secreting plasma cells ■ Immune responses are not always protective and can even be pathogenic if the response induces severe tissue destruction or is directed against an autoantigen ■ As a barrier organ to the external environment, the skin is endowed with the capacity and the necessary cellular components to mount an immune response

INTRODUCTION The skin is in a sense a defense organ, since it represents a major barrier against the outside environment. As such, it is constantly confronted with microbial, chemical, and physical insults. Within the past four decades, there has been a greater appreciation for the fact that the skin not only functions as a mechanical barrier to the outside world, but also uses the immune system for protection. Accordingly, the skin is endowed with the capacity to generate an immune response, which gave rise to the term “skin-associated lymphoid tissues” (SALT)1. The classical immune response, also referred to as the adaptive immune response, is characterized by specificity that is due to immunologic memory (specific immunity)2. Innate immunity is a more primitive defense system that acts in a rapid but less specific manner. Both types of responses can be generated in the skin. Adaptive immune responses in the skin, however, are not always protective but can also be harmful in nature, e.g. allergic or autoimmune reactions. Numerous skin diseases are caused by T lymphocytes and are therefore immunologically mediated. Consequently, many dermatoses respond favorably to immunosuppressive therapy administered either systemically or topically.

INNATE IMMUNE RESPONSE Innate immune responses are characterized by a lack of immunologic memory. These immune reactions are less complicated than adaptive responses and developed earlier in evolution3. Nevertheless, failures in these “primitive” immune responses may be associated with severe, even fatal, health problems. Essential components of the innate response are neutrophils, eosinophils, natural killer cells, mast cells, cytokines, complement, and antimicrobial peptides. The innate response is more rapid and less controlled than the adaptive immune response.

Complement The complement system plays an important role in innate immunity. It consists of at least 20 serum glycoproteins that are activated by an

4 

enzymatic amplifying cascade (see Ch. 60)4. Three pathways can trigger this cascade. The classical pathway is stimulated by antigen–antibody complexes, the alternative pathway by polysaccharides derived from microbial cell walls, and the later identified lectin pathway by the interaction of microbial carbohydrates with mannose-binding proteins. All three pathways lead to activation of the central C3 component and, finally, the generation of a number of immunologically active substances. For example, C3b, the cleavage product of C3, binds to the surface of microbes. Since phagocytic cells express receptors for C3b, phagocytosis of the microorganisms is enhanced. In addition, complement components bind to antigen–antibody immune complexes, which help complement receptor-bearing antigen-presenting cells to target these immune complexes. C5a is a powerful attractant for neutrophils. C3a, C4a and C5a, also called anaphylatoxins, induce the release of inflammatory mediators from mast cells. This increases vascular permeability, thereby enabling proteins (e.g. antibodies) to enter the tissue. Assembly of the complement components C5b, C6, C7, C8 and C9 forms the membraneattack complex (MAC), which generates pores in cell membranes, causing death by osmotic lysis. Human cells are much less susceptible to killing by complement than are microbes, since human cells express the complement receptor type 1 (CR1, CD35), decay-accelerating factor (DAF, CD55), and membrane cofactor protein (MCP, CD46), which inhibit C3 convertase and thereby block progression of the complement cascade. CD59 is a protein that binds to C8 and inhibits insertion of C9 into the cell membrane.

Toll-Like Receptors Innate immunity serves to recognize invading microorganisms and then induce a host defense response. Several families of pattern recognition receptors (PRRs) mediate responses to pathogen-associated molecular patterns (PAMPs) that are conserved among microorganisms. Toll-like receptors (TLRs; the mammalian homologs of the Toll receptors identified in Drosophila) are one such family of PRRs. Ten TLRs have been identified to date5 (Fig. 4.1), with the following specificities: TLR2 (in association with either TLR1 or TLR6), recognition of lipoproteins and peptidoglycans; TLR4, lipopolysaccharide; TLR5, flagellin (a component of bacterial flagella); and TLR9, bacterial CpG DNA sequences. TLRs may also be involved in the recognition of viral components. The signaling pathway of TLRs is highly homologous to that of the receptor for interleukin-1 (IL-1). Upon interaction with myeloid differentiation factor 88 (MyD88), IL-1 receptor-associated kinase (IRAK) is recruited, ultimately leading to activation of the transcription factor NF-κB (see Fig. 4.1). Activation of TLRs can also result in the release of interferons (IFNs) via activation of interferon regulatory factor 3 (IRF3). Dendritic cells express several types of TLRs. Upon activation of these receptors by microbial components, the dendritic cells mature and migrate to the lymph nodes, where they present pathogen-derived antigens to naive T cells and induce an adaptive immune response. TLRs thereby bridge the gap between the innate and adaptive immune systems6. These two systems constantly interact in the skin, and the innate immune system represents a potential target for modulating adaptive immune responses7. Cutaneous dendritic cells that are stimulated by the innate immune system not only instruct T cells to respond but also tell them how and where. Different PAMPs and danger signals polarize dendritic cells, giving them the ability to produce certain cytokines and to induce T cells to differentiate into particular subtypes. Many of these danger signals are provided by keratinocytes, which also express PRRs. In addition, TLRs expressed in the skin direct control of pathogens by the epithelium.

81

The major purpose of the immune system is to provide protection against harmful agents. This is achieved by a rapid “primitive” reaction, called the innate immune response, and a more highly developed specific reaction, called the adaptive immune response. The characteristics of an adaptive immune response are specificity and the accumulation of memory, thus enabling improvement with each successive encounter with a particular antigen. The key event during an adaptive immune response is antigen presentation, yielding either a cell-mediated or a humoral response. The cellular response involves primarily T cells, whereas the humoral response involves B cells that ultimately mature into antibody-secreting plasma cells. More recently it has become clear that there is a close crosstalk between the innate and adaptive immune systems. Immune responses are not always protective and can even be pathogenic if the response induces severe tissue destruction or is directed against an autoantigen. As a barrier organ to the external environment, the skin is endowed with the capacity and the necessary cellular components to mount an immune response.

adaptive immunity, cutaneous immunology, antigen presentation, B cells, cytokines, dendritic cells, innate immunity, Langerhans cells, T cells, Th17

CHAPTER

4

Immunology

ABSTRACT

non-print metadata KEYWORDS:

81.e1

Fig. 4.1 Toll-like receptors, their ligands and signaling pathways. Toll-like receptors (TLRs) recognize pathogen-associated molecular patterns and/or synthetic compounds in a specific fashion. A TLR2/TLR1 dimer recognizes triacylated lipoproteins, and a TLR2/TRL6 dimer interacts with diacylated lipoproteins. TLR5 recognizes flagellin and TLR4 recognizes lipopolysaccharide (LPS). These TLRs are located on the cell membrane and are internalized upon ligand interaction. TLR3, TLR7, TLR8 and TLR9 are located on intracellular membranes of endosomes and lysosomes. TLR3 recognizes viral double-stranded RNA (dsRNA); TLR7 and TLR8 viral single-stranded RNA (ssRNA); and TLR9 bacterial and viral hypomethylated DNA (CpG motifs). TLR7 and TLR8 also bind to synthetic compounds (imidazoquinolones). All TLRs except TLR3 utilize myeloid differentiation factor 88 (MyD88) for signaling, while TLR2 and TLR6 also require Tollinterleukin-1 receptor domain-containing adaptor protein (TIRAP). MyD88 signaling via IL-1 receptorassociated kinase-4 (IRAK-4) and tumor necrosis factor receptor-activated factor-6 (TRAF-6) mostly results in activation of nuclear factor κB (NF-κB), ultimately inducing transcription of genes encoding immunomodulatory and proinflammatory molecules. TLR3 and TLR4 signal via TIR-domain-containing adapter-inducing interferon-β (TRIF). The TRIF pathway induces the production of interferons (IFNs) via interferon regulatory factor-3 (IRF3). Both the ligand and signaling pathway of TLR10 are still unknown. Adapted from Miller LS. Toll-like receptors in skin. Adv  

TOLL-LIKE RECEPTORS, THEIR LIGANDS AND SIGNALING PATHWAYS

SECTION

Overview of Basic Science

1

Triacylated lipoproteins

Diacylated lipoproteins

Flagellin

Imidazoquinolines ssRNA

TLR1

TLR2

TLR2

TLR6

TIRAP

MyD88

TIRAP

MyD88 MyD88 TLR7

LPS

CpG DNA

dsRNA

TLR5

TLR4

TLR8

TLR9

?

TLR3

TRIF

TLR10

MyD88 ?

MyD88 MyD88 MyD88

TRIF

Endosome

IRAK4 TRAF6

IRF3 Cytoplasm

NF-B

Immunomodulatory genes

IFN-/ Nucleus

Dermatol. 2008;24:71–87 and from McInturff JE, Modlin RL, Kim J. The role of toll-like receptors in the pathogenesis and treatment of dermatological disease. J Invest Dermatol. 2005;125:1–8.

Inflammasomes Closely related to these processes are inflammasomes, innate immune complexes which sense intracellular danger-associated molecular patterns (DAMPs) or PAMPs. Four types of inflammasomes have been identified: Aim2 (absent in melanoma 2), the pyrin domain-containing NLRP1 (nucleotide-binding domain leucine-rich repeat-containing receptor 1, also called NALP), NLRP3, and NLRC4 (Nod-like receptor CARD domain-containing 4)8. Aim2 is activated by double-stranded DNA resulting from either viral or bacterial intracellular pathogens, NLRP1 by muramyl dipeptide, and NLRC4 by flagellin. NLRP3 is triggered by numerous PAMPs and DAMPs and is thus the most important inflammasome (Fig. 4.2). The ultimate result of activation of inflammasomes is the cleavage of pro-IL-1β into active IL-1β, a highly potent inflammatory mediator. NLRPs are large backbone proteins of the complex which, upon assembly of the inflammasome complex, bind to ASC (apoptosis-associated speck-like protein containing a caspase recruitment domain [CARD]). The latter interacts with caspase-1, resulting in its activation. Active caspase-1 cleaves and activates pro-IL1β, as well as the proinflammatory cytokine pro-IL-18. Dysregulation of inflammasomes is the cause of a group of inherited autoinflammatory diseases called cryopyrin-associated periodic syndromes (CAPS) which are associated with recurrent episodes of fever, urticarial skin lesions, arthritis, and systemic inflammation (see Ch. 45). These disorders respond very well to IL-1 blocking drugs (see Fig. 4.2).

Antimicrobial Peptides

82

To cope with an environment that is full of microorganisms, plants and invertebrates produce a variety of highly effective antimicrobial proteins. Human epithelia, including the epidermis, secrete such anti­ microbial peptides as a mechanism of innate defense. The first antimicrobial peptide to be found in human skin (specifically from psoriatic scales) was human β-defensin-2 (hBD-2)9. A number of other antimicrobial peptides have subsequently been isolated (Table 4.1). In addition to antibacterial properties, some of these peptides possess antimycotic and likely antiviral activities. As demonstrated for psoriasin, which prevents Escherichia coli infection10, these peptides may protect the skin from bacterial infections. Expression of antimicrobial

peptides can be induced by bacteria, bacterial products, or proinflammatory cytokines via TLRs and other mechanisms. Enhanced and reduced production of these peptides in psoriasis and atopic dermatitis, respectively, may explain why superinfections are so rare in the former disease and common in the latter9,11. However, others have found enhanced expression of antimicrobial peptides in atopic skin, which may reflect disruption of the epidermal barrier12. Ultraviolet (UV) B radiation has been shown to induce expression of antimicrobial peptides, potentially explaining the lack of UVB-related bacterial infections despite its immunosuppressive effects (see Ch. 86)13. Beta-defensins can also attract immature dendritic cells and memory T cells via the chemokine receptor (CCR)-6, illustrating another link between innate epithelial defense and adaptive immunity14. The antimicrobial peptide LL-37 (also known as cathelicidin antimicrobial peptide [CAMP]) mediates dendritic cell activation in psoriasis by binding self-DNA and forming structures that stimulate TLR9 and thereby induce IFN production15.

Cytokines Cytokines are a large, heterogeneous family of low-molecular-weight messenger substances that play a crucial role in intercellular communication. Cytokines can be secreted by almost any cell type, and they may act in an autocrine, paracrine, or endocrine manner. Cytokines exert their biologic activities by binding to specific cell surface receptors16. Although the vast majority of cytokines occur in a soluble form, some can be membrane-bound, making the differentiation between cytokine and receptor difficult. Cytokines influence the proliferation, differentiation, and activation of cells. Each cytokine exhibits multiple activities, a fact that complicates strict categorization. Cytokines that are produced by leukocytes and exert effects preferentially on other white blood cells are called interleukins (IL). Colonystimulating factors (CSFs) are mediators that induce differentiation and proliferation of hematopoietic progenitor cells, while IFNs interfere with viral replication. Cytokines that have chemoattractant activity are termed chemokines, and they play a crucial role in leukocyte migration. The main subgroups of chemokines are differentiated according to the position of two cysteine (C) residues compared with the other amino acid residues (X), CXC (α-chemokines) and CC (β-chemokines)17.

Lipopolysaccharide T L R 4

Stimulus (e.g. bacterial RNA) PAPA syndrome

CAPS: Muckle Wells syndrome Familial cold autoinflammatory syndrome NOMID/CINCA syndrome Cryopyrin (inactive)

IL-1R

Familial Mediterranean fever

PSTPIP1 Pyrin

Domains B30.2 CARD Caspase-1 Coiled coil Leucine-rich repeats NOD

Cryopyrin (active) NF-κB

Pyrin Zinc finger NLRP3 inflammasome

Proteins ASC CARDINAL Procaspase-1

TNF-α Pro-IL-1β

IL-1R antagonist (anakinra) Pro-IL-1β Nucleus

IL-1 Lysosome

Chemokines that recruit leukocytes are termed inflammatory chemokines, whereas those that regulate trafficking within lymphoid tissues are called lymphoid chemokines. Early innate immune responses are dominated by cytokines with inflammatory (e.g. IL-1, IL-6, IL-18, tumor necrosis factor-α [TNF-α], inflammatory chemokines) and antiviral (e.g. IFN-α, IFN-β) capacities. Induction of adaptive immune responses is critically dependent on cytokines with immunomodulatory capacities (e.g. IL-2, IL-4, IL-12, IL-13, IL-17, IL-22, IL-23, IFN-γ). However, since most of these mediators exhibit multiple and sometimes overlapping activities, a strict separation into inflammatory and immunomodulatory cytokines is not possible. Due to structural similarities, some cytokines are grouped into families, e.g. the IL-6 family (IL-6, IL-11, oncostatin M, leukemia inhibitory factor [LIF]), the IL-10 family (IL-10, IL-19, IL-20, IL-22, IL-24, IL-26), and the IL-12 family (IL-12, IL-23, IL-27).

Macrophages and Neutrophils Macrophages, phagocytic cells derived from blood-borne monocytes, carry receptors for carbohydrates that are usually not expressed on vertebrate cells (e.g. mannose). Through this mechanism, macrophages can discriminate between “foreign” and “self” molecules. Furthermore,

Fig. 4.2 NLRP3 inflammasome and its relationship to several hereditary periodic fever syndromes and autoinflammatory disorders. Upon release of autoinhibition, cryopyrin interacts with apoptosis-associated speck-like protein with a CARD domain (ASC) and CARD-inhibitor of NF-κB-activating ligand (CARDINAL) within an inflammasome, leading to activation of caspase-1 and generation of mature interleukin (IL)-1β. Pyrin can competitively bind ASC and (pro)-caspase-1, thereby preventing them from being incorporated into the NLRP3 inflammasome. Proline–serine– threonine phosphatase-interacting protein 1 (PSTPIP1) binds (and perhaps inhibits) pyrin, and this interaction is strengthened by the PSTPIP1 mutations that underlie PAPA syndrome. CAPS, cryopyrin-associated periodic syndromes; CARD, caspase-recruitment domain; CINCA, chronic infantile neurologic, cutaneous and articular syndrome; IL-1R, interleukin-1 receptor; NF-κB, nuclear factor-κB; NLRP3, NOD-like receptor pyrin domain-containing protein 3; NOD, nucleotide-binding oligomerization domain; NOMID, neonatal-onset multisystem inflammatory disease; PAPA, pyogenic arthritis, pyoderma gangrenosum and acne; RIP2, receptor-interacting protein-2; TLR, Toll-like receptor; TNF, tumor necrosis factor. Courtesy, Julie V Schaffer,  

CHAPTER

4

Immunology

NLRP3 INFLAMMASOME AND ITS RELATIONSHIP TO SEVERAL HEREDITARY PERIODIC FEVER SYNDROMES AND AUTOINFLAMMATORY DISORDERS

MD.

IL-1-TRAP (rilonacept) mAb anti-IL-1β (canakinumab)

macrophages possess receptors for antibodies and complement. Hence, microorganisms that are coated with antibodies and/or complement are more readily phagocytosed18. After phagocytosis, the microorganisms are exposed to a variety of toxic intracellular molecules, including superoxide anions, hydroxyl radicals, hypochlorous acid, nitric oxide, lysozyme, and antimicrobial cationic proteins. Macrophages can also present processed antigens to T and B cells. However, their T-cell stimulatory capacity is less effective than that of dendritic cells. Activated macrophages release granulocyte colony-stimulating factor (G-CSF) and granulocyte–macrophage colony-stimulating factor (GMCSF). These two cytokines induce the division of myeloid precursors in the bone marrow, releasing millions of neutrophils into the circulation. Under normal conditions, neutrophils circulate in the bloodstream, some rolling along the vascular endothelium19. To enter the site of an infection, neutrophils utilize a complex process that involves proinflammatory mediators, adhesion molecules, chemoattractants, and chemokines (see Ch. 26). The recruited neutrophils phagocytose organisms and kill them within phagolysosomes by using oxygendependent and oxygen-independent mechanisms. The former, called the respiratory burst, involves the production of hydrogen peroxide, hydroxyl radicals, and singlet oxygen. The oxygen-independent method utilizes highly toxic cationic proteins and enzymes, such as

83

SKIN-DERIVED ANTIMICROBIAL PEPTIDES

Antimicrobial activity SECTION

Overview of Basic Science

1

Name

Size (kD)

Antileukoprotease (ALP)

Bacteria

Fungi

Inducibility (e.g. by bacteria, cytokines)

Cellular source

Gram+

Gram−

11.7

Keratinocytes Airway epithelia

++

++

++



Dermcidin (DCD)-1

4.7

Sweat glands

+++

+++

++



Human β-defensin (HBD)-2

4.3

Keratinocytes Airway epithelia Intestinal tract

(+)*

+++

++

+

HBD-3

5.2

Keratinocytes Airway epithelia

+++

+++

+++

+

HBD-4

6.0

Keratinocytes Airway epithelia (mRNA)

++

++

+

+

LL-37/cathelicidin antimicrobial peptide (CAMP)/human cationic antimicrobial peptide 18 (hCAP18)

4.5

Keratinocytes Airway epithelia Urogenital tract Granulocytes

++

++

++

+

Lysozyme

14.7

Keratinocytes Airway epithelia

++

++





Psoriasin

11.4

Keratinocytes Sebocytes

(+)*

++†

(+)*

+

RNase 7

14.5

Keratinocytes Airway epithelia

+++

+++

+++

+

*† In high concentrations.

E. coli, others in high concentrations.

Table 4.1 Skin-derived antimicrobial peptides. In the skin, antileukoprotease (ALP) is also referred to as SKALP, skin-derived ALP.  



myeloperoxidase (MPO) and lysozyme. Organisms that are coated with antibodies or complement components bind to Fc and complement receptors, respectively, on neutrophils (as well as macrophages) and are more effectively phagocytosed and killed. Ectosomes are vesicles released from the plasma membrane of neutrophils upon their stimulation (e.g. by bacteria)20. They carry membrane surface receptors (e.g. CD15, L-selectin), phosphatidylserine, and granule proteins (e.g. CD66b, CD87, MPO, elastase, proteinase 3, defensins, lactoferrin, collagenase I). Depending on the composition, ectosomes can induce a variety of responses in their target cells which include endothelial cells, platelets, natural killer cells, and dendritic cells. In addition, neutrophils can release neutrophilic extracellular traps (NETs) and thereby develop into anuclear cytoplasts20. NETs are composed of extracellular strands of DNA bound to neutrophil-derived antimicrobial peptides and proteins. Because NETs can entrap bacteria, fungi and viruses, they may offer some antimicrobial protection. On the other hand, NETs can induce autoimmunity by stimulating immune responses against the NET-associated nuclear antigens (see Fig. 41.1). Whether formation of NETs contributes to the exacerbation of autoimmune diseases by infections remains to be determined.

Eosinophils

84

The major function of eosinophils is most likely to protect the host from infections by parasites, particularly nematodes. Infections with these organisms are associated with the production of antigen-specific IgE antibodies that coat the parasite. Via their low-affinity receptors (FcεRII, CD23), eosinophils bind to IgE antibodies and become activated. In contrast to macrophages and neutrophils, eosinophils are only weakly phagocytic. They harbor large granules that contain major basic protein, eosinophilic cationic protein, eosinophil peroxidase, and eosinophil-derived neurotoxin (see Ch. 25). Upon activation, eosinophils release these toxic products, which can kill parasites, together with prostaglandins, leukotrienes, and various cytokines21. Eosinophils also play an important role in the pathogenesis of allergic reactions.

Basophils and Mast Cells Basophils (found in the blood) and mast cells (located within tissues) exhibit similar functional and morphologic characteristics22. At least two populations of mast cells exist, which can be differentiated by the enzymes they contain and by their tissue location. Mucosal mast cells contain only trypsin, while connective tissue mast cells contain both trypsin and chymotrypsin (see Ch. 118). In contrast to pulmonary, uterine and tonsillar mast cells, cutaneous mast cells express the receptor for C5a (CD88), which implies that triggering of mast cells through the anaphylatoxin C5a results in cutaneous, but not systemic, reactions23. Basophils and mast cells express high-affinity receptors for IgE (FcεRI) that avidly bind IgE (see Ch. 18). When a specific antigen binds to mast cell-bound IgE, the FcεRI becomes activated, which leads to degranulation and release of preformed mediators, including histamine and serotonin. Other mediators such as prostaglandins, leukotrienes (B4, C4, D4 and E4), and plateletactivating factor are also released, and they enhance vascular permeability, bronchoconstriction, and induction of an inflammatory response (see Ch. 18). Hence, basophils and mast cells play an important role in immediate-type allergic reactions such as urticaria and angioedema. There is also evidence that mast cells are involved in contact hypersensitivity reactions.

Natural Killer Cells The major task of natural killer (NK) cells is to eliminate virally infected or malignant cells24. NK cells can recognize their targets in two ways. Since they express Fc receptors that bind IgG (FcγRIII, CD16), NK cells can adhere to and kill target cells that are coated with IgG. This killing process is referred to as antibody-dependent cellular cytotoxicity (ADCC). The second recognition system involves killer-activating and killerinhibitory receptors. Killer-activating receptors recognize molecules that are expressed by nucleated cells. This provides a signal for the NK cell to kill the target cell by secretion of perforins, which make holes in the cell membrane through which granzymes are injected. Granzymes lyse target cells by activating the apoptotic caspase cascade. In

ADAPTIVE IMMUNE RESPONSE The characteristic features of an adaptive immune response are its specificity and enhancement with each successive antigen encounter owing to the accumulation of “memory”2,25. A crucial event during the generation of an adaptive immune response is antigen presentation.

Antigen-Presenting Cells Various cells can present antigens, depending on how and where the antigen first encounters cells of the immune system. Interdigitating dendritic cells (DCs) located in the T-cell areas of the spleen and lymph nodes are the most effective antigen-presenting cells (APCs). Within the epidermis, Langerhans cells (LCs) are key APCs. Therefore, the following section will focus primarily on LCs.

Langerhans cells In 1868, Paul Langerhans26 first described Langerhans cells as DCs located within the epidermis26. Because of their dendritic shape, Langerhans thought that these cells might be of neural origin. More than 100 years later, it was shown that LCs are derived from bone marrow27. However, in the 1990s it was observed that LCs are intimately associated with nerve fibers and that nerves, through the release of neuropeptides such as calcitonin gene-related peptide (CGRP), can modulate LC function28.

Morphology of Langerhans cells

LCs cannot be identified in routinely fixed and stained histologic sections; their recognition requires electron microscopy or histochemical analysis. Ultrastructurally, LCs have rod-shaped organelles termed Birbeck granules (see Fig. 91.5). A Ca2+-dependent lectin with mannosebinding specificity called langerin is associated with and responsible for the formation of Birbeck granules29. Birbeck granules are thought to result from the antigen-capture function of langerin, which routes antigen into these organelles and provides access to a non-classical antigen-processing pathway. However, langerin is not completely specific for LCs and can also be expressed by a certain type of dermal DC30.

Activated LCs elongate their dendrites which can penetrate keratinocyte tight junctions and survey the area just beneath the stratum corneum for antigens31. These penetrating dendrites take up antigens which co-localize with langerin/Birbeck granules. By forming new tight junctions, keratinocytes rapidly close the defects produced by the penetrating dendrites, thereby maintaining skin integrity during antigen uptake. Histochemically, human LCs can be visualized by staining for adenosine triphosphatase (ATPase), a membrane-bound, formalinresistant, sulfhydryl-dependent enzyme. In addition to langerin (CD207), antigenic moieties present on human LCs include the panhematopoietic marker CD45, MHC class II antigens (HLA-DR), CD1a, the S100 protein, and vimentin. CD1a is a useful marker for LCs, since within the epidermis (normal or inflamed) it is exclusively expressed on LCs, whereas HLA-DR antigens are expressed on keratinocytes in inflamed skin (Table 4.2). Since CD1a does not exist in the murine system, staining for MHC class II antigens is often used for detection of murine LCs in non-perturbed skin32 (Fig. 4.3). In addition, human LCs express the high-affinity IgE receptor (FcεRI)33, which was initially thought to be exclusively expressed on mast cells and basophils. The density of murine LCs is dependent on a variety of factors, including strain, age, sex, and anatomic location. LCs are almost absent in the tail region, the pouch, and the cornea. In humans, the numbers of LCs are reduced on the palms and soles, genitalia, and buccal mucosa. In addition, the density of LCs decreases with age and is reduced in chronically UV-exposed skin32.

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Immunology

addition, NK cells carry inhibitory receptors (KIR) on their surface that recognize major histocompatibility complex (MHC) class I selfmolecules. KIRs shut off the killer signal and thus prevent autolysis of the host. Tumor cells and viruses often down-regulate MHC class I molecules to escape recognition by cytotoxic T cells. Paradoxically, this mechanism renders “MHC class I-low” cells susceptible to recognition by NK cells.

Ontogeny of Langerhans cells

Bone marrow chimera experiments showed that LCs are derived and constantly replenished from the bone marrow27. However, according to a more recent hypothesis30, murine LCs are derived from radioresistant hematopoietic precursor cells that reside in the skin during embryonic development (Fig. 4.4). The formation of LCs depends on transforming growth factor-β1 (TGF-β1) and macrophage colony-stimulating factor receptor (M-CSFR) ligands (M-CSF, IL-34), which are provided in an autocrine fashion. LCs that are depleted during the steady state or after minor injuries are repopulated locally, independent of circulating precursor cells. In lethally irradiated mice reconstituted with congenic bone marrow cells, half of the LCs are eliminated in the first week after transplantation, but LCs repopulate locally within 3 weeks. After UVB irradiation, which does not affect the dermis or the hair follicle, LCs appear to repopulate from the hair follicle30. By producing different chemokines, distinct subpopulations of hair follicle keratinocytes can promote (via release of CCL2 and CCL20) or inhibit (via release of CCL8) repopulation of LCs34.

PHENOTYPIC MARKERS OF RESIDENT VERSUS MIGRATING HUMAN LANGERHANS CELLS VERSUS HUMAN LANGERIN− DERMAL DENDRITIC CELLS

Birbeck granules

Resident LC

Migrating LC

Langerin− dermal DC

++

++



Langerin (CD207)

+++

++



MHC class II

++

+++

++

CD45

+

+

+

CD1a

+++

+++

++

CD11c

+

+

+

CD11b

+/−

+/−

++

E-cadherin

++

+



Epithelial cell adhesion molecule (EpCAM)

+

+



CCR6

+





CCR7



+

+

Table 4.2 Phenotypic markers of resident versus migrating human Langerhans cells (LCs) versus human langerin− dermal dendritic cells (DCs). CCR, CC-chemokine receptor. Adapted from ref. 30.  

Fig. 4.3 Langerhans cells express MHC class II molecules. In a sheet preparation of murine epidermis, numerous Langerhans cells can be visualized by staining with an antibody against MHC class II molecules (Ia antigen). Note the dendritic shape of Langerhans cells. Courtesy, N Romani, Department of Dermatology,  

University of Innsbruck.

85

ONTOGENY AND PHENOTYPE OF ANTIGEN-PRESENTING CELLS IN MURINE SKIN

SECTION

Overview of Basic Science

1

TGF-β1

Radioresistant precursor cell

M-CSF IL-34 CCR7

LC

MHC class II+ CD11c+ CD11b+ EpCAMhigh CD103– F4/80+

Epidermis

Langerin+ DC

Migratory LC MHC class II+ CD11c+ CD11b+ EpCAMhigh CD103– F4/80+ CCR7

CCR7

Langerin – DC MHC class II+ CD11c+ CD11b low EpCAM – CD103 + F4/80 –

CCR2 E-selectin P-selectin

Macrophage MHC class II+ CD11c+ CD11b high EpCAM – CD103– F4/80+

MHC class II low CD11c – CD11b high EpCAM – CD103– F4/80+

Dermis

Blood vessel

Draining lymph node

Precursor cell

= Birbeck granule

Fig. 4.4 Ontogeny and phenotype of antigen-presenting cells in murine skin. Langerhans cells (LCs) are derived from radioresistant hematopoietic precursor cells in the skin in the presence of transforming growth factor-β1 (TGF-β1), macrophage colony-stimulating factor (M-CSF), and interleukin (IL)-34. LCs migrate to the draining lymph nodes in a CC-chemokine receptor 7 (CCR7)-dependent fashion. The dermis harbors dermal langerin+ dendritic cells (DCs), which differentiate from radiosensitive circulating precursor cells in a CCR2-, E-selectin- and P-selectin-dependent manner. LCs on the way to the lymph nodes can be distinguished from dermal langerin+ DCs by the differential expression of CD11b, epithelial cell adhesion molecule (EpCAM), and CD103. Two additional types of APCs are present in the dermis, dermal langerin− DCs and dermal macrophages, and each has a particular surface marker expression pattern. Markers in italics differ from those in LCs. Adapted from Merad M, Ginhoux F, Collin M. Origin, homeostasis and function of Langerhans cells and other langerin expressing dendritic cells. Nat Rev Immunol. 2008;8:935–47.  

As noted above, langerin is not an exclusive marker for epidermal LCs but can also be expressed by dermal DCs (see Fig. 4.4)30. Langerin+ dermal DCs differentiate from radiosensitive circulating precursor cells, independent of TGF-β1 and M-CSFR ligands but dependent on CC-chemokine receptor 2 (CCR2), E-selectin, and P-selectin. LCs that emigrate from the epidermis to the lymph nodes in a CCR7-dependent manner can also be detected in the dermis but can be distinguished from langerin+ dermal DCs by the differential expression of CD11b, epithelial-cell adhesion molecule (EpCAM), and CD103 (see Fig. 4.4). Two additional types of APCs can be found in the dermis, langerin− dermal DCs and dermal macrophages, and each has a particular surface marker expression pattern. In humans, the situation is less clear than in mice, since only studies with tissue explants are available. Subtle differences in the surface marker expression of resident LCs, migrating LCs, and langerin− dermal DCs have been described (see Table 4.2).

Other dendritic cells

86

DCs are defined as professional APCs that display an extraordinary capacity to stimulate naive T cells and initiate a primary immune response35. This capacity was initially described for the interdigitating DCs in the spleen. It has become apparent that the DC system is very complex, and many questions still remain unanswered. This complexity is based on the fact that DCs can arise from several types of progenitor cells, and a variety of functional phenotypes of DCs can also be generated from the same precursor cell36. In addition, differences exist between experimental systems used to study human and murine DCs. In the murine system, DCs are primarily obtained from

the bone marrow or spleen, while human DCs are almost exclusively generated from peripheral blood. Furthermore, many markers/antibodies exist in the human but not the murine system, and vice versa. Whether each of the different types of DCs has a distinct immune function is still a matter of debate36. Concerning DC function, there is evidence in the murine system that spleen-derived CD8α+ DCs induce T helper 1 (Th1) responses, while CD8α− DCs favor T helper 2 (Th2) responses37. In contrast, in the human system, lymphoid/plasmacytoid DCs were found to induce Th2 responses, and myeloid DCs generated Th1 reactions38. Consequently, myeloid DCs were referred to as DC1 and lymphoid/plasmacytoid DCs as DC2. Activation of TLR7 via the immunomodulator imiquimod, an imidazoquinoline (see Fig. 4.1), drives myeloid DCs to express perforin and granzyme B and plasmacytoid DCs to express TNF-related apoptosis-inducing ligand (TRAIL). This enables killing of tumor cells, indicating that both myeloid and plasmacytoid DCs are directly involved in imiquimod-induced destruction of skin cancer39. However, the type of immune response that is generated also critically depends on the state of maturation of the stimulating DC at the time of antigen presentation. For the induction of Th1 responses, the presence of IL-12 is crucial. DCs tend to produce IL-12 directly after an activating step in their maturation, driving T cells into a Th1 phenotype if they meet the DCs at this stage40. At later time points, the production of IL-12 decreases, thereby favoring the development of a Th2 response. This process is also heavily influenced by the innate immune system (e.g. stimulation by TLRs; see above). Taken together, the parameters that are responsible for the type of Th cell differentiation that is induced by DCs remain to be fully

Antigen presentation Antigen presentation cells: activation and migration

To initiate sensitization, antigens must be presented to T cells by APCs. For many years, LCs were thought to be the most important APC in the skin since contact sensitization could not be induced in sites that were naturally devoid of LCs (e.g. murine tail skin) or in which LCs had been depleted (e.g. by UV radiation)42. However, transgenic mice in which LCs are completely depleted via the diphtheria toxin receptor technique (i.e. short-term, inducible ablation) demonstrated variably diminished but not completely abrogated sensitization responses43; in one such model, the sensitization response was completely normal44. In a different knockout mouse model characterized by constitutive and durable absence of epidermal LCs45, an enhanced sensitization response was actually observed, suggesting that LCs may have regulatory functions. This “LC paradigm” proposes that LCs may be tolerogenic when they present antigens under steady-state non-inflammatory conditions, but sensitizing upon stimulation by inflammatory mediators. Which of these activities is the main function of LCs remains to be determined, and there is accumulating evidence that dermal DCs are equally if not even more important than LCs in presenting antigens. Cutaneous APCs actively take up antigens in the skin, but antigen presentation to lymphocytes takes place in the regional lymph nodes. In the presence of inflammation, the APCs become activated and leave the skin, migrating to the draining lymph nodes. During emigration, they change their phenotypic and functional behavior and develop into mature DCs. For example, molecules involved in antigen uptake and processing (Birbeck granules, Fc receptors) are down-regulated on activated LCs46. In addition, expression of E-cadherin, which mediates the attachment of LCs to neighboring keratinocytes, is reduced, thereby enabling the emigration of LCs. CD44, a hyaluronic acid receptor involved in the tissue homing of leukocytes, is upregulated on activated LCs. The splice variant CD44v6 supports binding of LCs to T-cell-rich areas of lymph nodes47. Furthermore, the integrins α6β1 and α6β4, which exhibit affinity to the basement membrane zone, are induced on the surface of emigrating LCs48.

The release of proteolytic enzymes like matrix metalloproteinase-9 (type IV collagenase) may enable their penetration through the basement membrane. Their dendricity becomes more pronounced, and surface molecules necessary for antigen presentation and T-cell priming are upregulated (e.g. MHC class I, MHC class II, CD40, CD54, CD58, CD80, CD86). At this stage, LCs emigrating from the epidermis are almost indistinguishable from DCs obtained from lymphoid organs46. The same phenotypic and functional changes may occur in other APCs of the skin that have important roles in antigen presentation.

Antigen presentation to T cells

In contrast to B cells, T cells cannot recognize soluble protein antigens per se; instead, the T-cell receptor (TCR) recognizes antigen-derived peptides bound to MHC locus-encoded molecules expressed on APCs. CD4+ T cells recognize antigens in association with MHC class II molecules, while CD8+ T cells, the majority of which become cytotoxic, recognize antigens in association with MHC class I molecules25 (Fig. 4.5). Two pathways exist by which antigens can be “loaded” onto MHC molecules. If the antigen has been produced endogenously within the cell (e.g. viral or tumor proteins), it is complexed with MHC class I molecules through intracellular processing pathways (Fig. 4.6)49. The proteasome degrades cytosolic antigens produced by the cell. The resulting peptides (which consist of 8 to 12 amino acid residues) are imported into the endoplasmic reticulum (ER) in a TAP (transporter associated with antigen processing)-dependent manner and loaded onto MHC class I molecules50. After binding to the MHC class I–β2 microglobulin complex, these peptides are transported to the cell surface via the Golgi apparatus. Alternative pathways by which exogenous proteins are phagocytosed and the phagosome fuses to the ER may also exist. The proteins would subsequently be retransported out of the ER into the cytoplasm (by an as yet unclear mechanism) and then degraded by the proteasome. The degraded peptides could then enter the pathway that is normally employed for endogenous proteins via the TAP protein. As the vast majority of nucleated cells express MHC class I molecules, many cell types can serve as APCs for MHC class I-restricted antigen presentation in a secondary immune response. In contrast, MHC class II-dependent antigen presentation is critically dependent on DCs, B cells, and monocytes/macrophages. MHC class II-associated antigen presentation targets primarily exogenous (Fig. 4.7)

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Immunology

defined. On the other hand, there is agreement that immature DCs induce tolerance due to incomplete T-cell activation, resulting in T cells of the regulatory type that suppress immune responses41.

TYPES OF ANTIGEN PRESENTATION Jα







Recombination





Recombination CD4+ T cell

CD4



α

β

C

C

J

J

CD8+ T cell

CD3

CD3

D

MHC class II

APC

β

C

C

J

J

CD8

D V

V

α

Antigenic peptide (15-22aa)

V

Antigenic peptide (8-12aa)

β2m

V

MHC class I

APC

Fig. 4.5 Types of antigen presentation. Antigens are presented by antigen-presenting cells to the T-cell receptor of CD4+ or CD8+ T cells in association with either MHC class II or MHC class I molecules. The diversity of the T-cell receptors is generated by gene rearrangement. For reasons of clarity, the simplified gene rearrangement of the α-chain is shown only in the CD4+ T cell and that of the β-chain in the CD8+ T cell. aa, amino acids; APC, antigen-presenting cell; β2m, β2-microglobulin; V, variable; D, diversity; J, joining; C, constant. Adapted from Modlin RL. Lymphocytes. In: Freedberg IM, Eisen AZ, Wolf K, et al. (eds). Fitzpatrick’s Dermatology in General Medicine,  

vol. 1. New York: McGraw-Hill, 1999;32:400–5.

87

Fig. 4.6 The pathway of endogenous antigen delivery to class I MHC molecules. Newly synthesized MHC class I molecules are stabilized by calnexin. When β2-microglobulin (β2m) binds to the complex, calnexin dissociates. This complex associates with the TAP (transporter associated with antigen processing) protein waiting for a suitable peptide. Endogenous antigens are degraded by the proteasome and transported via TAP into the endoplasmic reticulum (ER), where they bind to the MHC class I/β2m complex. Finally, the peptide/MHC complex is transported through the Golgi apparatus to the cell surface. Not pictured is a possible alternate pathway in which exogenous proteins are phagocytosed and the phagosome fuses to the ER. The proteins are then retransported out of the ER into the cytoplasm and degraded by proteasomes. The degraded peptides can now enter this pathway via the TAP protein. Adapted from Parkin J, Cohen B. An overview  

THE PATHWAY OF ENDOGENOUS ANTIGEN DELIVERY TO MHC CLASS I MOLECULES

SECTION

Overview of Basic Science

1

Cell membrane

Cytoplasm

Endoplasmic reticulum

of the immune system. Lancet. 2001;357:1777–89. With permission from Elsevier.

Calnexin

Golgi apparatus

MHCI β m 2

TAP-1 and TAP-2

Endogenous protein (viral, tumor)

Proteasome

Digested protein

β m, β -microglobulin 2

2

MHCI

Antigen

TAP, transporter associated with antigen processing

Fig. 4.7 The pathway of exogenous antigen delivery to class II MHC molecules. Exogenous antigens are taken up into the cell by endosomes. The protein is cleaved into peptides within the endosomes, which become increasingly acidic. In the endoplasmic reticulum (ER), newly synthesized MHC class II molecules bind to an invariant chain, which inhibits their disassociation while empty. During this assembly, the complex is stabilized by calnexin. The invariant chain transports the MHC class II molecule from the ER (via the Golgi apparatus) into the endosomal compartment, where the MHC class II complex meets the peptides. The invariant chain is cleaved, leaving a small fragment (CLIP) in the groove of the MHC class II molecule. Finally, CLIP is replaced by the antigenic peptide. The complex is transported to the cell membrane and expressed on the cell surface. CLIP, class II-associated invariant peptide.  

THE PATHWAY OF EXOGENOUS ANTIGEN DELIVERY TO MHC CLASS II MOLECULES Cell membrane Exogenous protein

Cytoplasm

Endosome

CLIP

Endoplasmic reticulum

Adapted from Parkin J, Cohen B. An overview of the immune system. Lancet. 2001;357:1777–89. With permission from Elsevier.

Calnexin Invariant chain MHCII

88

Peptide antigen

T Cells T-cell precursors continuously migrate from the bone marrow to the thymus, where T cells develop54. In the thymus, T cells bearing the α/β TCR are subjected to a complex selection process. In contrast to antibodies, which represent the antigen receptor on B cells and recognize antigens in their naive form, the α/β TCR recognizes only short peptide fragments that are generated during antigen processing within APCs (see above). These processed antigens are presented to the TCR by MHC molecules on the cell surface. The amino acid sequences recognized by the TCR include those from both the MHC molecule and the antigenic peptide. Consequently, the TCR recognizes a combination of “self” MHC molecules (which are highly polymorphic) and “foreign” peptides. T cells that recognize “self” MHC molecules but not “self” peptides are useful for immune defense and do not lead to undesirable autoimmunity. This requirement is achieved by a complex process that involves both positive and negative selection within the thymus.

T-cell development Developing T cells within the cortex of the thymus engage MHC complexes on thymic DCs. When the T cells are able to recognize these MHC molecules via their TCR, they receive a survival signal (positive selection). Otherwise, the T cells undergo apoptotic cell death55. At this stage, more than 95% of the developing T cells die in the thymus because they are not selected due to their uselessness (i.e. inability to recognize “self” MHC molecules)56. In addition, T cells that express a TCR with a very high affinity for the complex of a “self” peptide plus a “self” MHC molecule are eliminated by apoptosis, since they are potentially harmful. This process, called negative selection, takes place in the thymic medulla and involves DCs and macrophages that process and present a spectrum of “self” antigens. Positive and negative selection allow the survival of just those T cells that recognize foreign (but not “self”) peptides in the context of “self” MHC molecules and thus are useful for immune defense without causing auto-attack57. During thymic education, a variety of surface molecules are switched on and off. Components of the CD3/TCR complex, together with CD4 or CD8 molecules, have roles in this process. In general, CD4+ T cells function as helper T cells and recognize antigens presented by MHC

class II molecules, whereas CD8+ T cells are usually cytotoxic and recognize antigens in association with MHC class I molecules (see Fig. 4.5). During their early stage of development within the thymus, T cells express both CD4 and CD858. Upon expression of an appropriate TCR, these immature T cells exhibit the capacity to recognize antigenic peptides associated with either MHC class I or MHC class II molecules, since they still express both CD4 and CD8 (double-positive stage). In the subsequent process of maturation, one of these surface markers is lost, resulting in single-positive T cells expressing either CD4 or CD8. These cells are specialized for peptides presented only by MHC class II or MHC class I molecules, respectively.

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and less frequently endogenous antigens51. Exogenous antigens are taken up via macro- or micropinocytosis or by receptor-mediated endocytosis. One example of the latter is the DEC-205 receptor (CD205), which guides antigens into endocytic vesicles that reside deeper inside the cell and contain MHC class II molecules. As a consequence of this unique intracellular targeting, antigens endocytosed by the DEC-205 receptor stimulate respective T cells up to 500-fold greater than antigens taken up by pinocytosis or other receptors. Protein degradation eventually takes place in the endo-/lysosomes, yielding peptides with a typical length of 15 to 22 amino acid residues. These peptide fragments enter specialized endosomal compartments containing MHC class II molecules that are generated in the ER52. Newly synthesized MHC class II molecules are associated with an invariant chain, which inhibits dissociation of empty MHC class II molecules and transports the MHC class II complex from the ER to the specialized endosomal compartments where the molecules can interact with antigen peptide fragments (see Fig. 4.7). In this compartment, the invariant chain is cleaved by proteases, leaving a small fragment called CLIP (class II-associated invariant peptide) that binds to the class II molecule. Upon interaction with the antigenic peptides, the CLIP fragment is released from the complex. The MHC class II molecule with the bound antigen peptide is subsequently expressed on the cell surface, allowing antigen recognition by T cells carrying the appropriate TCR. Classically, MHC class I molecules present self- or pathogen-derived antigens that are synthesized within the cell to CD8+ T cells (see Fig. 4.6), whereas exogenous antigens derived via endocytic uptake are loaded onto MHC class II molecules for presentation to CD4+ T cells (see Fig. 4.7). However, it has become evident that some DCs are also able to process exogenous antigens into the MHC class I pathway for presentation to CD8+ T cells. This mechanism, referred to as crosspresentation53, allows DCs to induce either tolerance (to self-antigens) or immunity (to exogenous pathogens).

T-cell receptor One major feature of an adaptive immune response is the recognition of specific antigens. This is achieved either by the TCR during a T-cellmediated response or by antibodies during a B-cell response. TCRs are transmembrane molecules consisting of α/β (vast majority of T cells) or γ/δ (30 m/s

A-delta (Aδ)

Small

C

Small

+



2–30 m/s

30) lesions; patients may have a family history of the disorder but no associated internal malignancy.

Pathology Pityriasis rotunda has microscopic features of ichthyosis vulgaris. In addition to an absent or diminished granular cell layer, there is moderate hyperkeratosis without parakeratosis. Increased pigmentation of the basal cell layer may be present, and epidermal atrophy can be seen along with areas of pigment incontinence, a minimal perivascular lymphohistiocytic infiltrate, and occasional follicular plugging55. Special stains for fungi are negative.

Differential Diagnosis The differential diagnosis includes tinea corporis, tinea versicolor, leprosy, and large plaque parapsoriasis. It lacks the pruritus and inflammation of dermatitis, and there is no associated anesthesia or peripheral nerve thickening. The combination of a potassium hydroxide examination, fungal culture, and routine histology excludes major entities in the differential diagnosis. Of note, mycobacteria have never been isolated. Because of the large size of the lesions, the hypopigmented variant of pityriasis rotunda can resemble one form of progressive

Treatment Pityriasis rotunda is relatively difficult to treat. Trials with topical lactic acid, urea, tars, emollients, and corticosteroids have provided little benefit. Topical tretinoin cream 0.1% can result in modest improvement and systemic retinoids warrant consideration for patients with more extensive disease. However, reversal of any underlying disorder – in particular, malnutrition, infection, or malignancy – should be addressed first.

GRANULAR PARAKERATOSIS Synonyms:  ■ Axillary granular parakeratosis ■ Intertriginous granular parakeratosis

Key features ■ The primary lesions are brownish-red keratotic papules that can coalesce into plaques ■ The adult form occurs almost exclusively in women ■ In most adult cases, lesions are localized to the axillae, but other intertriginous sites can be affected ■ The infantile form is associated with diaper wearing and presents as bilateral plaques in the inguinal folds or erythematous geometric plaques underlying pressure points from the diaper ■ Histopathologically, there is distinct retention of basophilic keratohyaline granules within areas of parakeratosis in the stratum corneum ■ A defect in processing profilaggrin to filaggrin is a proposed mechanism

of keratohyalin granules within the stratum corneum could be due to a defect in filaggrin metabolism. In this model, there is a failure to degrade keratohyalin granules and to aggregate keratin filaments during cornification.

Clinical Features The primary lesions are keratotic, brownish-red papules that can have a conical shape. They may coalesce into larger, well-demarcated plaques with various degrees of maceration secondary to local occlusion (Fig. 9.14). Lesions can persist for months or longer and recur. Pruritus is the most common complaint, but irritation is also a problem if there are erosions or fissures. Some patients experience a flare with an increase in ambient temperature and sweating. The axillae are the most common sites of involvement, with both unilateral and bilateral lesions having been described. Additional intertriginous areas such as the groin and inframammary fold may be affected. In the infantile form, bilateral plaques in the inguinal folds or erythematous geometric plaques underlying pressure points from the diaper can be seen.

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Other Papulosquamous Disorders

macular hypomelanosis; however, the latter has no associated scale and it lacks the histologic features of ichthyosis vulgaris.

Pathology The characteristic feature is an unusual form of parakeratosis. The stratum corneum is thickened and compacted with increased eosinophilic staining (Fig. 9.15). Retained nuclei are present throughout this keratin layer, creating the parakeratosis. The most unusual feature is

Introduction Granular parakeratosis is typically a pruritic disorder, initially reported to occur only in the axillae. It is now recognized that other intertriginous sites, i.e. the groin, inframammary and abdominal folds, can also be involved61–63. An underlying disorder in keratinization has been suggested that may explain its distinct histopathologic findings64.

History Northcutt and colleagues61 first described granular parakeratosis in 1991. Mehregan and colleagues proposed renaming this condition “intertriginous granular parakeratosis” to reflect its localization to these areas.

Fig. 9.14 Granular parakeratosis involving the axilla. Coalescing brown papules with hyperkeratosis and slight maceration. Courtesy, Kalman Watsky, MD.  

Epidemiology Granular parakeratosis is observed most commonly in adult women61– 63 . It affects middle-aged or older adults, and it has been reported in both darkly pigmented and lightly pigmented individuals. Although it is an unusual condition in young adults64, there is an infantile form in which diaper-wearing plays a role65.

Pathogenesis Granular parakeratosis is thought to be an acquired keratotic dermatosis that was initially linked to the use of personal hygiene products. These included deodorants and antiperspirants in roll-on or stick form, mineral salt-containing crystals used as “natural” deodorants, and soaps used in excess and/or in a susceptible individual61–64. However, patients without a known irritant have also been reported64. In infants, occlusion from the diaper leads to a humid environment and together with mechanical and chemical irritation may contribute to proliferation and altered maturation of the epidermis; zinc oxide can also increase epidermal turnover. A disorder of keratinization characterized by a basic defect in the processing of profilaggrin to filaggrin has been proposed. Based on ultrastructural and immunohistochemical studies, Metze and Rutten64 came to the same conclusion as Northcutt et al.61 that the retention

Fig. 9.15 Axillary granular parakeratosis – histopathologic findings. Marked, compact parakeratosis with small bluish granules within the stratum corneum representing keratohyaline granules (inset). Courtesy, Lorenzo Cerroni, MD.  

173

3

the visible retention of basophilic keratohyalin granules within these areas of parakeratosis66.

Papulosquamous and Eczematous Dermatoses

SECTION

Differential Diagnosis

174

The differential diagnosis includes the most common causes of intertrigo (e.g. seborrheic dermatitis, candidiasis, inverse psoriasis, erythrasma) as well as Hailey–Hailey disease, Darier disease, and pemphigus vegetans61–64. Sometimes the papules may be confused with seborrheic keratoses and the plaques with acanthosis nigricans. Irritant or allergic contact dermatitis also needs to be considered in some patients. A biopsy will confirm the diagnosis of granular parakeratosis.

Treatment Based upon case reports and small series, therapeutic success has been reported with topical corticosteroids, vitamin D analogues, retinoids, ammonium lactate, and antifungals61–64. In addition, cryotherapy as well as oral isotretinoin and oral antifungals have been used. Spontaneous resolution has also been observed (including in infants), as have relapses. For additional online figures visit www.expertconsult.com

REFERENCES 1. Lambert WC, Everett MA. The nosology of parapsoriasis. J Am Acad Dermatol 1981;5:373–95. 1a.  Cerroni L. Skin lymphoma – The illustrated guide. 4th ed. Oxford: Wiley-Blackwell; 2014. 2. Brocq L. Les parapsoriasis. Ann Dermatol Syph 1902;3:433–68. 3. Hu C-H, Winkelmann RK. Digitate dermatosis. A new look at symmetrical, small plaque parapsoriasis. Arch Dermatol 1973;107:65–9. 4. Sánchez JL, Ackerman AB. The patch stage of mycosis fungoides. Am J Dermatopathol 1979;1:5–26. 5. Haeffner AC, Smoller BR, Zepter K, Wood GS. The differentiation and clonality of lesional lymphocytes in small plaque parapsoriasis. Arch Dermatol 1995;131:321–4. 6. Klemke CD, Dippel E, Dembinski A, et al. Clonal T cell receptor gamma-chain gene rearrangement by PCR-based GeneScan analysis in the skin and blood of patients with parapsoriasis and early-stage mycosis fungoides. J Pathol 2002;197:348–54. 7. Siddiqui J, Hardman DL, Misra M, Wood GS. Clonal dermatitis: a potential precursor of CTCL with varied clinical manifestations. J Invest Dermatol 1997;108:  584. 8. Yamanaka K, Clark R, Rich B, et al. Skin-derived interleukin-7 contributes to the proliferation of lymphocytes in cutaneous T-cell lymphoma. Blood 2006;107:2440–5. 9. Samman PD. The natural history of parapsoriasis en plaques (chronic superficial dermatitis) and prereticulotic poikiloderma. Br J Dermatol 1972;87:405–11. 10. Vakeva L, Sarna S, Vaalasti A, et al. A retrospective study of the probability of the evolution of parapsoriasis en plaques into mycosis fungoides. Acta Derm Venereol 2005;85:318–23. 11. Lindae ML, Abel EA, Hoppe RT, Wood GS. Poikilodermatous mycosis fungoides and atrophic large-plaque parapsoriasis exhibit similar abnormalities of T-cell antigen expression. Arch Dermatol 1988;124:366–72. 12. Wood GS, Tung RM, Haeffner AC, et al. Detection of clonal T-cell receptor γ gene rearrangements in early mycosis fungoides/Sézary syndrome by polymerase chain reaction and denaturing gradient gel electrophoresis (PCR/DGGE). J Invest Dermatol 1994;103:34–41. 13. Lazar AP, Caro WA, Roenigk HH, Pinski KS. Parapsoriasis and mycosis fungoides: the Northwestern University experience, 1970 to 1985. J Am Acad Dermatol 1989;21:919–23. 14. Bowers S, Warshaw EM. Pityriasis lichenoides and its subtypes. J Am Acad Dermatol 2006;55:557–72. 15. Ersoy-Evans S, Greco MF, Mancini AJ, et al. Pityriasis lichenoides in childhood: a retrospective review   of 124 patients. J Am Acad Dermatol 2007;56:  205–10. 16. Mucha V. Über einen der Parakeratosis variegata (Unna) bzw: Pityriasis lichenoides chronica (Neisser-Juliusberg) nahestehenden eigentumlichen Fall. Arch Dermatol Syph. 1916;123:586–92. 17. Habermann R. Über die akut vereaufende, Nekrotisierende unterart der Pityriasis lichenoides (pityriasis lichenoides et varioliformis acuta). Dermatol Z. 1925;45:42–8. 18. Juliusberg F. Über die Pityriasis lichenoides chronica (psoriasiform lichenoides exanthem). Arch Dermatol Syph. 1899;50:359–74. 19. Wood GS, Strickler JG, Abel EA, et al. Immunohistology of pityriasis lichenoides et varioliformis acuta and pityriasis lichenoides chronica. Evidence for their interrelationship with lymphomatoid papulosis. J Am Acad Dermatol 1987;16:559–70.

20. Muhlbauer JE, Bhan AK, Harrist TJ, et al. Immunopathology of pityriasis lichenoides acuta. J Am Acad Dermatol 1984;10:783–95. 21. Martinez-Escala ME, Sidiropoulos M, Deonizio J, et al. γδ T cell-rich variants of pityriasis lichenoides and lymphomatoid papulosis: benign cutaneous disorders to be distinguished from aggressive γδ T cell lymphomas. Br J Dermatol 2015;172:372–9. 22. Weiss LM, Wood GS, Ellisen LW, et al. Clonal T-cell populations in pityriasis lichenoides et varioliformis acuta (Mucha-Habermann disease). Am J Pathol 1987;126:417–21. 23. Shieh S, Mikkola DL, Wood GS. Differentiation and clonality of lesional lymphocytes in pityriasis lichenoides chronica. Arch Dermatol 2001;137:  305–8. 24. Dereure O, Levi E, Kadin ME. T-cell clonality in pityriasis lichenoides et varioliformis acuta: a heteroduplex analysis of 20 cases. Arch Dermatol 2000;136:1483–6. 25. Black MM. Lymphomatoid papulosis and pityriasis lichenoides: are they related? Br J Dermatol 1982;106:717–21. 26. Samman PD. Poikiloderma with pityriasis lichenoides. Trans St John’s Hosp Dermatol Soc 1971;57:143–7. 27. Rivers JK, Samman PD, Spittle MF, et al. Pityriasis lichenoides-like lesions associated with poikiloderma: a precursor of mycosis fungoides. Br J Dermatol 1986;115:17. 28. Fortson JS, Schroeter AL, Esterly NB. Cutaneous T-cell lymphoma (parapsoriasis en plaque). An association with pityriasis lichenoides et varioliformis acuta in young children. Arch Dermatol 1990;126:1449–53. 29. Panizzon RG, Speich R, Dazzi H. Atypical manifestations of pityriasis lichenoides chronica: development into paraneoplasia and non-Hodgkin lymphomas of the skin. Dermatology 1992;184:65–9. 30. Sotiriou E, Patsatsi A, Tsorova C. Febrile ulceronecrotic Mucha-Habermann disease: a case report and review of the literature. Acta Derm Venereol 2008;88:350–5. 31. Glemetti C, Rigoni C, Alessi E, et al. Pityriasis lichenoides in children: a long-term follow-up of eighty-nine cases. J Am Acad Dermatol 1990;23:473–8. 32. Devergie A. Pityriasis pilaris. Traite pratique des maladies de la peau. 2nd ed. Paris: Martinet; 1857. p. 454–64. 33. Besnier E. Du pityriasis rubra pilaire. Ann Dermatol Syphiligr (Paris) 1889;10:253–87. 34. Albert MR, Mackool BT. Pityriasis rubra pilaris. Int J Dermatol 1999;38:1–11. 35. Fuchs-Telem D, Sarig O, van Steensel MA, et al. Familial pityriasis rubra pilaris is caused by mutations in CARD14. Am J Hum Genet 2012;91:163–70. 36. Miralles ES, Nunez M, De Las Heras ME, et al. Pityriasis rubra pilaris and human immunodeficiency virus infection. Br J Dermatol 1995;133:990–3. 36a.  Plana A, Carrascosa JM, Vilavella M, Ferrandiz C. Pityriasis rubra pilaris-like reaction induced by imatinib. Clin Exp Dermatol 2013;38:520–2. 36b.  Cheung EJ, Jedrych JJ, English JC 3rd. Sofosbuvirinduced erythrodermic pityriasis rubra pilaris-like drug eruption. J Drugs Dermatol 2015;14:1161–2. 37. Griffiths WAD. Pityriasis rubra pilaris. Clin Exp Dermatol 1980;5:105–12. 38. Dicken CH. Treatment of classic pityriasis rubra pilaris. J Am Acad Dermatol 1994;31:997–9. 39. Allison DS, El-Azhary RA, Calobrisi SD, Dicken CH. Pityriasis rubra pilaris in children. J Am Acad Dermatol 2002;47:386–9. 40. Molin S, Ruzicka T. Treatment of refractory pityriasis rubra pilaris with oral alitretinoin: case report. Br J Dermatol 2010;163:221–3. 41. Muller H, Gattringer C, Zelger B, et al. Infliximab monotherapy as first-line treatment for adult-onset

42. 43. 44.

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47. 48. 49. 50. 51. 52. 53. 54. 55. 56. 57. 58. 59. 60. 61. 62. 63. 64. 65. 66.

pityriasis rubra pilaris: case report and review of the literature on biologic therapy. J Am Acad Dermatol 2008;59:S65–7. Wohlrab J, Kreft B. Treatment of pityriasis rubra   pilaris with ustekinumab. Br J Dermatol 2010;163:  655–6. Gibert CM. Traite pratique des maladies de la peau et de la syphilis. 3rd ed. Paris: H Plon; 1860. p. 402. Chuang T, IIstrup DM, Perry HO, Kurland LT. Pityriasis rosea in Rochester, Minnesota, 1969 to 1978: a 10-year epidemiologic study. J Am Acad Dermatol 1982;7:  80–9. Kempf W, Adams V, Kleinhans M, et al. Pityriasis rosea is not associated with human herpesvirus 7. Arch Dermatol 1999;135:1070–2. Drago F, Broccolo F, Rebora A. Pityriasis rosea: an update with a critical appraisal of its possible herpesviral etiology. J Am Acad Dermatol 2009;61:303–18. Hartley AH. Pityriasis rosea. Pediatr Rev 1999;20:  266–9. Allen RA, Janniger CK, Schwartz RA. Pityriasis rosea. Cutis 1995;56:198–202. Balci DD, Hakverdi S. Vesicular pityriasis rosea: an atypical presentation. Dermatol Online J 2008;14:6. Drago F, Rebora A. Treatment for pityriasis rosea. Skin Therapy Lett 2009;14:6–7. Sharma PK, Yadav TP, Gautam PK, et al. Erythromycin in pityriasis rosea: a double-blind, placebo-controlled clinical trial. J Am Acad Dermatol 2000;42:241–4. Leenutaphong V, Jiamton S. UVB phototherapy for pityriasis rosea: a bilateral comparison study. J Am Acad Dermatol 1995;33:996–9. Drago F, Vecchio F, Rebora A. Use of high-dose   acyclovir in pityriasis rosea. J Am Acad Dermatol 2006;54:82–5. Drago F, Broccolo F, Zaccaria E, et al. Pregnancy outcome in patients with pityriasis rosea. J Am Acad Dermatol 2008;58:S78–83. Pinto GM, Tapadinhas C, Moura C, Afonso A. Pityriasis rotunda. Cutis 1996;58:406–8. Swift PJ, Saxe N. Pityriasis rotunda in South Africa: a skin disease caused by undernutrition. Clin Exp Dermatol 1985;10:407–12. Grimalt R, Gelmetti C, Brusasco A. Pityriasis rotunda: report of a familial occurrence and review of the literature. J Am Acad Dermatol 1994;31:866–71. Gupta S. Pityriasis rotunda mimicking tinea cruris/ corporis and erythrasma in an Indian patient. J Dermatol 2001;28:50–3. Lodi A, Betti R, Chiarelli G, et al. Familial pityriasis rotunda. Int J Dermatol 1990;29:483–5. Yoneda K, Presland RB, Demitsu T, et al. The profilaggrin N-terminal domain is absent in pityriasis rotunda. Br J Dermatol 2012;166:227–9. Northcutt AD, Nelson DM, Tschen JA. Axillary granular parakeratosis. J Am Acad Dermatol 1991;24:541–4. Mehregan DA, Vandersteen P, Sikorski L, Mehregan DR. Axillary granular parakeratosis. J Am Acad Dermatol 1995;33:373–5. Webster CG, Resnik KS, Webster GF. Axillary granular parakeratosis: response to isotretinoin. J Am Acad Dermatol 1997;37:789–90. Metze D, Rutten A. Granular parakeratosis: a unique acquired disorder of keratinization. J Cutan Pathol 1999;26:339–52. Chang MW, Kaufmann JM, Orlow SJ, et al. Infantile granular parakeratosis: recognition of two clinical patterns. J Am Acad Dermatol 2004;50:S93–6. Scheinfeld NS, Mones J. Granular parakeratosis: pathologic and clinical correlation of 18 cases of granular parakeratosis. J Am Acad Dermatol 2005;52:863–7.

eFig. 9.2 Digitate small plaque parapsoriasis – digitate dermatosis. Elongated finger-like lesions on the flank.  

CUTANEOUS CLONAL T-CELL DISORDERS

Clonal T cells

Misc

PLC PLEVA

SPP

CHAPTER

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Other Papulosquamous Disorders

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CTCL

LyP LPP

Plaques

Papules

eFig. 9.1 Cutaneous clonal T-cell disorders. Venn diagram of the relationship between the parapsoriasis group of skin diseases and other clonal T-cell disorders. The miscellaneous group includes some cases of several inflammatory diseases, e.g. chronic dermatitis, idiopathic erythroderma, alopecia mucinosa, drug eruptions, lymphoid hyperplasia. Circles are not drawn to scale. CTCL, cutaneous T-cell lymphoma; LPP, large plaque parapsoriasis; LyP, lymphomatoid papulosis; Misc, miscellaneous; PLC, pityriasis lichenoides chronica; PLEVA, pityriasis lichenoides et varioliformis acuta; SPP, small plaque parapsoriasis.  

eFig. 9.4 Pityriasis rubra pilaris. Orange–red keratotic follicular papules.  

Courtesy, Luis Requena, MD.

eFig. 9.3 Pityriasis lichenoides. An admixture of crusted and scaly papules characteristic of PLEVA and PLC, respectively, are seen. Courtesy, Antonio Torrelo, MD.  

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eFig. 9.6 Pityriasis rubra pilaris. The orange–red color of the skin, including that of the palmar keratoderma, aids in the clinical diagnosis. Courtesy, Luis Requena,  

MD.

eFig. 9.5 Pityriasis rubra pilaris. Striking symmetric islands of sparing on the flanks. Follicular papules are present at the periphery of the diffuse erythema.  

Used with permission of the Mayo Foundation for Medical Education and Research.

eFig. 9.8 Pityriasis rosea in darkly pigmented skin. It tends to be more papular than that in lightly pigmented skin. Note the associated  

eFig. 9.7 Pityriasis rubra pilaris-like presentation in Wong variant of juvenile dermatomyositis. Courtesy, Antonio Torrelo, MD.  

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eFig. 9.10 Inverse pityriasis rosea. Oval plaques with peripheral scale on the central buttocks. Used with permission of the Mayo Foundation for Medical Education and Research.  

eFig. 9.9 Pityriasis rosea. Two herald patches are seen. Courtesy, Kalman Watsky, MD.  

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PAPULOSQUAMOUS AND ECZEMATOUS DERMATOSES SECTION 3

Erythroderma Sean Whittaker

Synonyms:  ■ Exfoliative dermatitis



Exfoliative erythroderma



Red

man syndrome

10 

erythroderma is often more liberally applied when there is >80% of BSA involvement.

EPIDEMIOLOGY Key features ■ Erythroderma is clinically defined as erythema and scaling involving >80–90% of the body surface area ■ Systemic manifestations include peripheral edema, tachycardia, loss of fluid and proteins, and disturbances in thermoregulation ■ Erythroderma has multiple etiologies; the most common causes are psoriasis, drug reactions, atopic dermatitis, and cutaneous T-cell lymphoma (CTCL) ■ Establishing the correct diagnosis requires consideration of initial sites of involvement, additional clinical findings, histologic and molecular features, and associated systemic abnormalities, as well as a complete medical history ■ Despite an intensive evaluation, the cause remains unknown (idiopathic) in 25–30% of patients; some of these patients eventually develop CTCL ■ Treatment strategies should address the dermatologic disease as well as the underlying etiology and the systemic complications of the erythroderma

INTRODUCTION Erythroderma is defined as generalized erythema and scaling involving >80–90% of the body surface area (BSA). However, it does not represent a defined entity, but rather is a striking clinical presentation that can arise from a variety of diseases. Most commonly, erythroderma is due to generalization of pre-existing dermatoses (such as psoriasis or atopic dermatitis), drug reactions, or cutaneous T-cell lymphoma (CTCL). Although up to 50% of the patients have a history of more localized skin lesions prior to the onset of the erythroderma, identification of the underlying disease process represents one of the most complex challenges in dermatology. Sustained efforts during longitudinal evaluation may lead to the precise identification of the etiology. In approximately one-quarter of the patients, no specific etiology is found, and these cases are called “idiopathic erythroderma”. Attention should also be focused on the potential systemic complications of acute erythroderma. Hypothermia, peripheral edema, and loss of fluid, electrolytes and albumin with subsequent tachycardia and cardiac failure are serious threats to the erythrodermic patient. In addition, chronic erythrodermas may be accompanied by cachexia, diffuse alopecia, palmoplantar keratoderma, nail dystrophy, and ectropion.

HISTORICAL PERSPECTIVE The term “erythroderma” was introduced in 1868 by Hebra to describe an exfoliative dermatitis involving more than 90% of the skin surface. Based upon the clinical course, erythroderma was classified into chronically relapsing (Wilson–Brocq), chronically persisting (Hebra), and selflimiting epidemic (Savill) variants. However, these subdivisions are no longer employed. Even though originally more strictly defined as erythema and scaling involving >90% of BSA, nowadays the term

No precise data exist regarding the prevalence or incidence of erythroderma as most reports are retrospective and do not address the issue of overall incidence. Large series of patients have focused on male-tofemale ratios, average age, and underlying diseases1–7. Men are more commonly affected, with the male-to-female ratio ranging from approximately 2 : 1 to 4 : 1. An even higher ratio can be found in the subset of idiopathic erythroderma, also referred to as “red man syndrome” (not to be confused with the acute cutaneous reaction to rapid infusion of vancomycin). The average age at onset of erythroderma in these series was 52 years, with an average of 48 years in those including children, and 60 years in series excluding them1,3,4,6. Of a total of 746 patients, dermatitis (24%), psoriasis (20%), drug reactions (19%), and CTCL (8%) represented the most common underlying causes of erythroderma1,3,4,6. When categories within the dermatitis group were examined, atopic dermatitis (9%) was the most common type, followed by contact dermatitis (6%), seborrheic dermatitis (4%), and chronic actinic dermatitis (3%). With regard to etiology, no specific geographic differences have been noted7,8. In adults with erythroderma, overall relapse rates at one year range from 20% to 30%. For adults, uncommon to rare causes include pityriasis rubra pilaris, ichthyoses, bullous dermatoses (usually pemphigus foliaceus), graftversus-host disease (GVHD), infestations (most often scabies), and autoimmune connective tissue diseases (acute or subacute lupus erythematosus, dermatomyositis). Table 10.1 lists additional rare causes, from paraneoplastic (e.g. lymphoma) to inflammatory (e.g. sarcoidosis) and neoplastic (e.g. mastocytosis). Despite multiple skin biopsies, an in-depth clinical investigation and a detailed medical history, the underlying cause of erythroderma is not found in at least 25% of patients. Unfortunately, cases of idiopathic erythroderma tend to be chronic and are more likely to recur after treatment7. With regard to neonates and infants, inherited ichthyoses, dermatitides, psoriasis, immunodeficiencies9 (e.g. Omenn syndrome), and consequences of infection (e.g. staphylococcal scalded skin syndrome) represent the major causes of erythroderma (Table 10.2)10. In addition, the possibility of drug-induced erythroderma should always be considered.

PATHOGENESIS The pathogenetic mechanisms of the underlying diseases will be discussed in the respective chapters. The pathways involved in the de novo genesis of erythroderma or the generalization of pre-existing skin lesions are not well understood. The number of germinative keratinocytes as well as their mitotic rate is increased in erythrodermic skin, and the transit time of cells through the epidermis is shortened. Consequently, scales consist of material normally retained by the skin (nucleic acids, amino acids, soluble protein), and the daily loss of scales increases from 500–1000 mg to 20–30 g11. In acute erythroderma, the desquamated material usually has marginal metabolic significance, but in chronic erythroderma protein loss can be significant, leading to hypoalbuminemia and contributing to anemia of chronic disease. Given that the peak age of onset is during the 6th to 7th decade of life, it is likely that age-related immune senescence is a contributory factor in the development of idiopathic erythroderma. Likewise, the striking presentation of erythroderma in children with immunodeficiencies supports a role for immune dysregulation.

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From a diagnostic and therapeutic perspective, erythroderma represents one of the most challenging entities within dermatology. This is due in part to the large number of disorders that can present as an erythroderma. Whilst in adults the commonest causes are inflammatory disorders such as atopic dermatitis and psoriasis, drug eruption should always be in the differential diagnosis. In children, a variety of rare genetic disorders also need to be considered. Careful clinicopathologic correlation is essential in order to identify specific underlying causes and extensive investigations are often required to exclude disorders such as cutaneous T-cell lymphoma. Despite a thorough evaluation, a significant minority of patients (~25%) with erythroderma may have no identifiable etiology. While treatment should be directed at the underlying cause, weekly methotrexate can be an excellent empiric therapeutic option for patients with idiopathic erythroderma.

erythroderma, exfoliative dermatitis, exfoliative erythroderma, drug eruption, drug reaction, Sézary syndrome, atopic dermatitis, psoriasis, idiopathic erythroderma, erythrodermic mycosis fungoides, pityriasis rubra pilaris

CHAPTER

10 Erythroderma

ABSTRACT

non-print metadata KEYWORDS:

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CAUSES OF ERYTHRODERMA IN ADULTS

Underlying disease

Clinical clues

Histologic clues

Additional hints

Pre-existing psoriatic plaques or lesions of pustular psoriasis • Often spares the central face • Nail changes (oil-drop, pits, onycholysis) • Subcorneal pustules • Inflammatory arthritis



Confluent or focal parakeratosis Epidermal hyperplasia with bottlenecklike rete ridges • Tortuous vessels in a slightly edematous papillary dermis • Neutrophils within epidermis; sparse lymphohistiocytic infiltrate within dermis • Often reduced or absent granular layer







Common Psoriasis (Ch. 8)



Personal or family history of psoriasis Withdrawal of corticosteroids, methotrexate, cyclosporine or targeted immune modulators (biologic agents) • Receiving medication that can exacerbate psoriasis (e.g. lithium)

Atopic dermatitis (Ch. 12)



Pre-existing lesions (flexures) Severe pruritus • Lichenification, including eyelids • Prurigo nodularis



Mild to moderate acanthosis Variable spongiosis • Dermal eosinophils • Parakeratosis • Variable lymphohistiocytic infiltrate with exocytosis of lymphocytes • Variable dermal edema









Elevated serum IgE, eosinophilia Personal or family history of atopy (e.g. asthma, allergic rhinitis, atopic dermatitis) • Cataracts/keratoconus

Drug reactions (Ch. 21)



Preceded by morbilliform or scarlatiniform exanthem • Facial edema • In dependent areas, may become purpuric



Perivascular infiltrate with eosinophils Lichenoid pattern • Lymphomatoid pattern • Spongiotic pattern • Apoptotic keratinocytes at all levels of epidermis • Vacuolar degeneration of basal layer • DRESS/DIHS – spongiotic and lichenoid patterns







Idiopathic erythroderma



Elderly men Chronic, relapsing • Severe pruritus • Palmoplantar keratoderma • Dermatopathic lymphadenopathy



Nonspecific Acute forms – parakeratosis, spongiosis, and a moderate lymphohistiocytic infiltrate • Chronic forms – hyperkeratosis, psoriasiform acanthosis, and expanded papillary dermis







Intense pruritus with excoriations; can develop lichenification or prurigo nodularis • Deep purple–red hue; pigmentary changes (melanoerythroderma) • Infiltration and/or edema; leonine facies • Painful, fissured palmoplantar keratoderma • Alopecia • Lymphadenopathy



Cerebriform pleomorphic lymphocytes Clustering of atypical cells within epidermis uncommon • Band-like and occasionally lichenoid infiltrate • Cutaneous histology is non-diagnostic in at least 30% of patients with Sézary syndrome

Peripheral blood CD4+ lymphocytosis in Sézary syndrome (elevated CD4 : CD8 ratio of ≥10 : 1 in blood) • Detection of identical clonal T-cell population in skin and lymph node/blood • In Sézary syndrome: ≥1000 Sézary cells/ mm3; ≥40% CD4+/CD7−; or ≥30% CD4+/ CD26− (blood) • Can mimic several other causes of erythroderma

Salmon-colored erythema Islands of sparing (nappes claires) • Waxy keratoderma • Perifollicular keratotic papules

Psoriasiform epidermal hyperplasia Granular layer is normal • Alternating parakeratosis and orthokeratosis, both vertically and horizontally • Follicular plugs with “shoulder parakeratosis” • No neutrophils

No history of skin diseases More acute onset • Usually resolves within 2–6 weeks after withdrawal of responsible drug; possible exception is DRESS/DIHS • More common in HIV-infected patients

Consider less commonly associated drugs (see Table 10.3) • Continue to re-evaluate for cutaneous T-cell lymphoma, including serial skin biopsies

Less common Cutaneous T-cell lymphoma (Sézary syndrome > erythrodermic mycosis fungoides; Ch. 120)



Pityriasis rubra pilaris (Ch. 9)













Dermatitis (nonatopic), including contact (Chs 14 & 15) and stasis with autosensitization (Ch. 13)



Paraneoplastic erythroderma



Pre-existing localized disease Distribution of initial lesions



Variable spongiosis





Fine scaling Melanoerythroderma • Cachexia •



Flare after sun exposure Cephalocaudal progression • Appearance of erythema gyratum-like lesions as erythroderma improves

Occupation and hobbies Patch testing • Review oral medications (systemic contact dermatitis) • •

Nonspecific changes



Lymphoproliferative disorders, including lymphomas other than Sézary syndrome, and rarely thymomas • In the case of solid-organ malignancies, usually late-stage •

Table 10.1 Causes of erythroderma in adults. DIHS, drug-induced hypersensitivity syndrome; DRESS, drug reaction with eosinophilia and systemic symptoms;.  

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Underlying disease

Clinical clues

Histologic clues

Erythroderma

CAUSES OF ERYTHRODERMA IN ADULTS

Additional hints

Bullous dermatoses (Chs 29 & 30) and inherited ichthyoses (Ch 57) Pemphigus foliaceus



Pre-existing lesions, often on upper trunk • Impetigo-like erosions and vesicles • Moist scale-crust; cornflake scale



Acantholysis within the superficial epidermis • DIF, intercellular IgG



Bullous pemphigoid



Urticarial plaques Tense bullae • Elderly patients



Subepidermal blister Eosinophils • DIF, BMZ C3 and IgG







Mucosal erosions and hemorrhagic crusts • Erythema multiforme-like lesions • Mucocutaneous lichenoid lesions



Interface dermatitis with necrotic keratinocytes • Parakeratosis • Focal acantholysis • DIF, intercellular and BMZ IgG



Paraneoplastic pemphigus



Inherited ichthyoses (Ch. 57)



Present from birth or early infancy (see Table 10.2)



Widespread, pruritic, flat-topped, red–brown papules that can become confluent • Sparing of skin folds (“deck-chair” sign) • Favors elderly men

IIF, intercellular

IIF, BMZ

IIF, intercellular and BMZ (+ IIF rat bladder)

See Table 10.2



See Table 10.2



Dense perivascular infiltrate of lymphocytes and eosinophils in the upper to mid dermis



Lichenoid infiltrate of lymphocytes and epidermal exocytosis • Acanthosis of epidermis and compact hyperkeratosis • Possible lymphocyte nuclear pleomorphism



Rare Papuloerythroderma of Ofuji



Chronic actinic dermatitis (Ch. 87)



Initial lesions in photodistribution Allergic airborne contact dermatitis to Compositae





Multiple etiologies, including CTCL > atopy, other lymphomas, drugs (e.g. DDI, aspirin), infections (e.g. HIV, hepatitis C virus), paraneoplastic phenomenon • May have peripheral eosinophilia, lymphopenia Drug history UVA, UVB and visible light phototesting • Photopatch testing •

Other rare causes Hypereosinophilic syndrome (Ch. 25) Crusted (Norwegian) scabies (Ch. 84) • Lichen planus • GVHD (Ch. 52) • Autoimmune connective tissue disease (e.g. acute or subacute cutaneous lupus erythematosus, juvenile dermatomyositis [adolescents])

Dermatophyte infection Primary immunodeficiencies (Ch. 60) • Sarcoidosis • Mastocytosis • Langerhans cell histiocytosis • Other T-cell hematologic malignancies (e.g. adult T-cell leukemia/lymphoma, angioimmunoblastic T-cell lymphoma, T-cell prolymphocytic leukemia)









Table 10.1 Causes of erythroderma in adults. (cont’d) BMZ, basement membrane zone; DDI, dideoxyinosine; DIF, direct immunofluorescence; GVHD, graft-versus-host disease; HIV, human immunodeficiency virus; IIF, indirect immunofluorescence.

CAUSES OF ERYTHRODERMA IN NEONATES AND INFANTS

Underlying disease

Clinical clues

Histologic clues

Additional findings

Inherited ichthyoses (Ch. 57)¶ Epidermolytic ichthyosis (previously referred to as bullous congenital ichthyosiform erythroderma)



Formation of superficial blisters and erosions during the first days of life • Later, corrugated hyperkeratosis in flexural areas



Congenital ichthyosiform erythroderma (previously referred to as non-bullous congenital ichthyosiform erythroderma)



Collodion baby Generalized scaling involving flexures • Cicatricial alopecia, nail dystrophy (subungual hyperkeratosis, ridging), often palmoplantar hyperkeratosis • Ectropion





Mutations in KRT1 and KRT10, which encode keratins 1 and 10

Classic epidermolytic hyperkeratosis



Non-diagnostic



Mutations in TGM1 (encodes transglutaminase 1), ALOXE3 (lipoxygenase 3), ALOX12B (12[R] lipoxygenase), NIPAL4 (ichthyin), PNPLA1*, ABCA12*, and CYP4F22*

¶Present from birth or early infancy.

*PNPLA1, ABCA12 and CYP4F22 encode patatin-like phospholipase domain containing 1, ATP-binding cassette (ABC), sub-family A, member 12 and cytochrome P450, family 4, subfamily F, polypeptide 22, respectively.

Table 10.2 Causes of erythroderma in neonates and infants.  

Continued

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CAUSES OF ERYTHRODERMA IN NEONATES AND INFANTS

Underlying disease

Clinical clues

Histologic clues

Additional findings

Atopic-like dermatitis Food allergies • Immune deficiency • Erythroderma in neonates • Erythroderma may persist or ichthyosis linearis circumflexa develops • Examine eyebrows and eyelashes as well as scalp hairs for trichorrhexis invaginata (“bamboo hair”) • Failure to thrive



Routine histology – non-diagnostic • Loss of tissue LEKTI expression



Inherited ichthyoses (Ch. 57)¶ Netherton syndrome

• •

Conradi–Hünermann–Happle syndrome (X-linked dominant chondrodysplasia punctata)

Linear and swirled pattern Skeletal (chondrodysplasia punctata) and ocular anomalies (cataracts)



Hyperkeratosis, reduced granular layer, follicular plugging

By electron microscopy: premature secretion and abnormal lamellar bodies • Elevated serum IgE levels • Mutations in SPINK5 (encodes serine peptidase inhibitor, Kazal type 5, also known as lympho-epithelial Kazal-typerelated inhibitor [LEKTI])

Mutations in EBP at Xp11 (encodes emopamil binding protein [sterol isomerase])





Apoptosis of keratinocytes Vacuolization of basal keratinocytes • Dense dermal infiltrate (predominantly T cells) • Acanthosis, parakeratosis • Degeneration of subcutaneous fat lobules



Immunodeficiencies (Ch. 60) Omenn syndrome

Other forms of SCID†, agammaglobulinemia, complement deficiencies (e.g. C3, C5), IPEX syndrome Wiskott–Aldrich syndrome

Onset in neonatal period Exfoliative erythroderma with diffuse alopecia • Lymphadenopathy and hepatosplenomegaly • Recurrent infections • Diarrhea

Leukocytosis, peripheral eosinophilia Hypogammaglobulinemia • Elevated serum IgE levels • Lymph nodes: disruption of germinal centers and abundant S100+ interdigitating reticulum cells • Classically, RAG1 or RAG2 mutations, but this phenotype can also result from mutations in other genes (see Ch. 60)













“Leiner phenotype” of exfoliative dermatitis, chronic diarrhea, and recurrent infections



Non-diagnostic





Primarily affects boys Petechiae, ecchymoses • Atopic-like dermatitis • Recurrent sinopulmonary infections





See Ch. 60 Various genetic etiologies



Non-diagnostic



Microthrombocytopenia Lymphopenia, peripheral eosinophilia • Elevated serum IgE levels • Mutations in WAS • •

Primary dermatoses Atopic dermatitis (Ch. 12)



Crusted eczematous lesions on extensor surfaces, face, scalp • Spares diaper area • Pruritus • Onset week 6–16



See Table 10.1

Seborrheic dermatitis (Ch. 13)



Greasy, scaling plaques and satellite papules on scalp and in skin folds • Diaper area involvement • Non-pruritic • Early onset (week 2–12)



Psoriasis (Ch. 8)



Silvery white scaling and sharply demarcated plaques on face, elbows, and knees • Diaper area involvement • Nail pits • Usually later onset



Temperature instability/low-grade fever Irritability • Skin-fold accentuation • Large areas of tender erythema • Superficial bulla formation followed by desquamation • Radiating perioral scale-crusts • Extracutaneous staphylococcal infections often responsible



See Table 10.1



Psoriasiform hyperplasia of the epidermis with parakeratosis • Nonspecific inflammatory infiltrate See Table 10.1

Family history of psoriasis See Table 10.1

• •

Drug reactions (Tables 10.1 & 10.3) Infections Staphylococcal scalded skin syndrome

• •

Blister roof consists of the cornified layer and parts of the granular layer • Subcorneal blisters contain sparse acantholytic keratinocytes and only a few neutrophils and lymphocytes

Positive culture for Staphylococcus aureus (conjunctivae, nares, throat, rectum) • Identification of exfoliative toxins (ET-A & ET-B) via slide latex agglutination, double immunodiffusion, or ELISA (see Ch. 74) • ET-A produced by S. aureus specifically cleaves desmoglein 1 •

†Erythroderma can also occur secondary to GVHD (see Fig. 10.12).

Table 10.2 Causes of erythroderma in neonates and infants. (cont’d) ELISA, enzyme-linked immunosorbent assay; IPEX, immune dysregulation, polyendocrinopathy, enteropathy, X-linked; MRSA, methicillin-resistant Staphylococcus aureus; SCID, severe combined immunodeficiency; TSST-1, toxic shock syndrome toxin 1.

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Underlying disease

Clinical clues

Histologic clues

Additional findings

Infections Neonatal “toxic shock-like” exanthematous disease



Generalized diffuse macular erythema or morbilliform eruption with confluence • Minimal scaling • Fever • Occurs during first week of life

Congenital cutaneous candidiasis



Maternal vaginal Candida infection with intrauterine spread • Pustules, collarettes of scale • Oral cavity spared • May have paronychia and nail dystrophy

Colonization of umbilical stump, nasopharynx or skin with TSST-1producing MRSA • Thrombocytopenia • Reported primarily in Japan •

Yeast and pseudohyphae in the stratum corneum (PAS) • Subcorneal and spongiform pustules within the epidermis •

Erythroderma

10

CAUSES OF ERYTHRODERMA IN NEONATES AND INFANTS

KOH examination, fungal culture



Others Pityriasis rubra pilaris (Ch. 9) GVHD (e.g. maternal–fetal or transfusion-related in the setting of SCID) (Ch. 52) • Diffuse cutaneous mastocytosis (Ch. 118) • Rare ichthyoses – trichothiodystrophy, keratitis–ichthyosis–deafness (KID) syndrome, Sjögren–Larsson syndrome, neutral lipid storage disease with ichthyosis (Ch. 57) • Ankyloblepharon–ectodermal dysplasia–clefting (AEC) syndrome (Ch. 63) • “Nutritional dermatitis”, including kwashiorkor (Ch. 51) • •

Table 10.2 Causes of erythroderma in neonates and infants. (cont’d)

Fig. 10.1 Erythroderma with desquamation. Obvious exfoliation of scale with underlying erythema.  

CLINICAL FEATURES Cutaneous Manifestations Erythroderma is clinically defined by the presence of erythema and scaling involving more than 80–90% of the skin surface. Based upon its clinical course, erythroderma can be classified into primary or secondary types. In the primary form, the erythema (often initially on the trunk) extends within a few days or weeks to involve the entire skin surface, and this is followed by scaling (Fig. 10.1). The secondary form of erythroderma is defined as a generalization of a preceding localized skin disease – for example, psoriasis or atopic dermatitis. With the exception of very slowly progressing secondary erythroderma, erythema precedes the development of exfoliation by 2–6 days. The associated scaling varies extensively in size and color depending upon the stage of the erythroderma and nature of the underlying disease. In more acute phases, scales are usually large and crusted, whereas in chronic states they tend to be smaller and drier. Occasionally, the cause of the erythroderma is suggested by the character of the scale – for example, fine in atopic dermatitis or dermatophytosis,

bran-like in seborrheic dermatitis, crusted in pemphigus foliaceus, and exfoliative (i.e. peeling) in drug reactions. The color of the skin can also vary, from pink–red to red–brown to deep red–purple. Despite the varied causes, erythrodermas have several common clinical features. Pruritus, the most frequent complaint, is observed in up to 90% of patients. This symptom varies according to the underlying cause, but is most severe in patients with dermatitis or Sézary syndrome12. Given the itch–scratch cycle, the skin may become thickened, and areas of lichenification are seen in one-third of cases. Patients, especially those with a chronic erythroderma, may develop dyspigmentation, with hyperpigmentation (40/90 patients, 45%) observed more frequently than hypo- or depigmentation (18/90 patients, 20%) in one series4. Palmoplantar keratoderma appears in ~30% of erythrodermic patients and is often an early sign in pityriasis rubra pilaris12. Keratoderma with scale-crust can point to crusted scabies, whereas a painful and fissured keratoderma can occur in Sézary syndrome. In cases of pre-existing dermatoses, nail changes may precede the erythroderma (e.g. pits in psoriasis or horizontal ridging in atopic dermatitis), whereas others develop subsequently. Nail changes are said to be present in ~40% of patients. Most often “shiny” nails are observed, but discoloration, brittleness, dullness, subungual hyperkeratosis, Beau lines, paronychia, and splinter hemorrhages can be seen. The nails may even be totally shed. Diffuse non-scarring alopecia of the scalp or other sites appears in 20% of patients with chronic erythroderma, including those with CTCL. Cicatricial alopecia can also develop in the setting of Sézary syndrome or erythrodermic mycosis fungoides (MF). Patients with erythroderma due to a variety of causes can begin to develop multiple seborrheic keratoses, and these papules may be pale in color compared with the background erythema. Colonization of the skin with Staphylococcus aureus is common and can lead to secondary cutaneous infections as well as bacteremia. Bilateral ectropion and purulent conjunctivitis can also develop as ocular complications (Fig. 10.2). Lastly, an exacerbation of the erythroderma may follow UV irradiation or drug ingestion; this is not necessarily restricted to patients with photosensitive eczema or drug-induced erythroderma4.

Systemic Manifestations An awareness of potential systemic complications of erythroderma is essential for proper patient management. Pedal or pretibial edema is observed in ~50% of patients (182/380)1,3–5, and it probably results from hypoalbuminemia and a shift of fluid into extracellular spaces. In patients with CTCL-associated or drug-induced erythroderma, facial

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3

Fig. 10.2 Ectropion in the setting of erythroderma.  

Fig. 10.3 Psoriatic erythroderma. There is diffuse involvement of the trunk but a clue to the diagnosis is the individual lesions on the arm. Courtesy, Luis Requena,  

edema may also develop. Because of the markedly increased blood flow through the skin and increased fluid loss by transpiration, tachycardia affects 40% of patients, and there is a risk of high-output cardiac failure, particularly in elderly persons. Furthermore, increased skin perfusion leads to thermoregulatory disturbances. Although hyperthermia is more frequently observed than hypothermia, most patients describe chilly, rigor-like sensations1,2,4,6–8. The chronic and excessive loss of heat can lead to compensatory hypermetabolism with subsequent development of cachexia. Anemia, characterized by features of both iron deficiency and anemia of chronic disease, may also be observed in patients with chronic erythroderma. The most common extracutaneous manifestation of erythroderma is peripheral lymphadenopathy, which is found in approximately half of the patients. Even in the absence of an underlying lymphoproliferative disorder, lymphadenopathy may be prominent and, if so, histologic and molecular examination of a lymph node is recommended (in particular, immunohistochemical studies and T-cell receptor gene analysis)13. A core or excisional lymph node biopsy is preferable to a fine needle aspirate as the former provides sufficient tissue for accurate assessment of nodal architecture and cellular morphology. The major differential diagnosis is between lymphomatous involvement and reactive dermatopathic lymphadenopathy. Histologic examination of an enlarged lymph node may be preceded or followed by a CT or PET-CT scan. Hepatomegaly occurs in 20% of the cases (113/578), with a slight predominance in erythroderma due to drug-induced hypersensitivity. Splenomegaly is rarely seen and occurs most often in association with lymphoma1–4,6.

Specific Findings of the Underlying Disease In addition to the general features previously discussed, clinical presentations can have additional, sometimes specific, features suggesting the underlying etiology (see Tables 10.1 & 10.2).

Psoriasis

180

Psoriasis is the most common underlying disorder in adults with erythroderma. As a rule, psoriatic erythroderma is preceded by typical psoriatic lesions (see Ch. 8). Its onset is most often due to withdrawal of potent topical or oral corticosteroids, cyclosporine or methotrexate; occasionally, widespread flares follow a systemic infection, phototoxicity, or an irritant contact dermatitis to topical medications such as tar. After generalization of the erythema, the typical features of psoriasis are lost (Fig. 10.3), and disseminated sterile subcorneal pustules may develop (see Fig. 1.6). Due to a slower turnover rate, nail changes, such as oil-drop changes, onycholysis or nail pits, may still be visible and provide valuable clues to the diagnosis of psoriatic erythroderma. Treatment of the erythroderma may result in the subsequent reappearance of characteristic psoriatic plaques.

MD.

Atopic dermatitis Although occurring at any age, erythroderma develops most frequently in patients with a history of moderate to severe atopic dermatitis (Fig. 10.4). As a result, well-established pre-existing lesions can be found, especially when the erythroderma is of recent onset. The pruritus is intense, and secondary excoriations or prurigo-like lesions are frequently observed. Lichenification is often prominent and atrophy of the skin due to topical corticosteroids may be seen. Increased serum IgE and eosinophilia may accompany other signs and symptoms of atopy.

Drug reactions The number of drugs implicated as causes of erythroderma is staggering (Table 10.3; see also Ch. 21)14. Whereas erythroderma resulting from topical medications usually begins as an irritant or allergic contact dermatitis, eruptions due to systemic drugs begin as a morbilliform or scarlatiniform exanthem. There are, however, occasional exceptions such as the chronic eczematous eruptions associated with calcium channel blockers. In areas of greatest hydrostatic pressure (distal lower extremities), the lesions may become secondarily purpuric. While druginduced erythrodermas have the shortest duration, usually resolving 2–6 weeks after withdrawal of the responsible drug, rarely the erythroderma persists despite withdrawal of the putative drug and such cases may then be designated as idiopathic. Occasionally, there is a pseudoSézary syndrome presentation15. A minority of patients with DRESS (drug reaction with eosinophilia and systemic symptoms) syndrome, also referred to as drug-induced hypersensitivity syndrome (DIHS), become erythrodermic16. In addition to fever, these patients can develop peripheral eosinophilia, hepatitis, and peripheral lymphadenopathy (see Table 21.9).

Idiopathic erythroderma In ~25% of erythrodermic patients, no underlying disease is detectable. This group consists primarily of elderly men with a chronic pruritic erythroderma in association with dermatopathic lymphadenopathy and extensive palmoplantar keratoderma (Fig. 10.5); this constellation is often referred to as “red man syndrome” or “l’homme rouge” (not to be confused with the red man syndrome that accompanies rapid intravenous infusions of vancomycin). When this group was compared with the entire group of erythrodermic patients, lymphadenopathy (68% vs 44%) and peripheral edema (54% vs 40%) were found to be more common than in other types of erythroderma, and hypothermia exceeded hyperthermia17. In one series, atopic dermatitis, drug-induced, and CTCL were the most common etiologies eventually identified in



Courtesy, Antonio Torrelo, MD

A

CHAPTER

10 Erythroderma

Fig. 10.4 Erythroderma due to atopic dermatitis. A Widespread erythema with fine white scaling and excoriations. B Fine white scaling and obvious pruritus in addition to circumoral pallor. A, Courtesy, Lorenzo Cerroni, MD; B,

B

patients with idiopathic erythroderma2. In a second series, in which detection of a clonal T-cell population in the skin was a diagnostic criterion for CTCL, the latter was the most common underlying disease18. However, it is important to note that the presence of a T-cell clone in the peripheral blood of elderly individuals is common and may reflect a diminished T-cell receptor repertoire due to immune senescence rather than CTCL. Identification of a predominant clone via high-throughput T-cell receptor sequencing may prove helpful.

Fig. 10.5 Idiopathic erythroderma. This is the type of patient who requires longitudinal evaluation to exclude the development of cutaneous T-cell lymphoma.  

Cutaneous T-cell lymphoma (Sézary syndrome and erythrodermic mycosis fungoides) CTCL can mimic other causes of erythroderma and is frequently a significant diagnostic challenge. Erythroderma due to CTCL is subdivided into Sézary syndrome and erythrodermic MF (see Ch. 120). Sézary syndrome is defined by the triad of erythroderma, peripheral blood Sézary cells, and generalized lymphadenopathy. Additional clinical features include a painful and fissured keratoderma, diffuse alopecia, edema, and leonine facies. The skin is often infiltrated or hyperpigmented (melanoerythroderma) and severe pruritus is common (Fig. 10.6). To distinguish between Sézary syndrome and erythrodermic MF, revised criteria were proposed by the International Society of Cutaneous Lymphomas and the Cutaneous Lymphoma Task Force of the EORTC for the diagnosis of Sézary syndrome, namely erythroderma and evidence of an identical T-cell clone in the blood and skin plus one of the following: (1) ≥1000 Sézary cells/mm3; (2) a CD4 : CD8 ratio of ≥10 : 1; or (3) an increased percentage of CD4+ cells with an abnormal phenotype (≥40% CD4+/CD7− or ≥30% CD4+/CD26−)19. Longitudinal evaluation, including repeated skin biopsies and peripheral blood flow cytometry, may be required to distinguish CTCL from idiopathic erythroderma. As note previously, identification of a predominant clone via high-throughput T-cell receptor sequencing may prove helpful. Rarely patients with other hematologic malignancies, in particular angioimmunoblastic T-cell lymphoma, adult T-cell leukemia/ lymphoma or T-cell prolymphocytic leukemia, can present with erythroderma due to cutaneous infiltrates of malignant lymphocytes.

Pityriasis rubra pilaris Erythrodermic pityriasis rubra pilaris (PRP) can be observed in children and adults (see Ch. 9). Usually, the lesions have a salmon to orange–red color. The degree of scaling varies, but it can be marked with large scales (Fig. 10.7). The combination of follicular keratotic papules on the knees, elbows and dorsal aspects of the fingers plus nappes claires

(islands of uninvolved skin within the erythroderma) favors the diagnosis of PRP (Fig. 10.8). When the classic histologic features are present (see below), this is also helpful in distinguishing PRP from psoriasis. Occasionally, CTCL can have an appearance similar to PRP.

Papuloerythroderma of Ofuji This represents a distinctive reaction pattern most often described in men. Pruritic, monomorphic reddish brown papules often become confluent, with sparing of skin folds (“deck-chair” sign). In one review of 170 reported cases, a causative factor was not identified in the majority of patients. Of the remaining individuals, CTCL represented the most common underlying etiology (see Table 10.1 for additional etiologies)20.

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3

Fig. 10.7 Erythroderma due to pityriasis rubra pilaris. Large thin scales are seen as well as the characteristic orange– red color.  

DRUGS ASSOCIATED WITH ERYTHRODERMA

Common Allopurinol β-lactam antibiotics • Carbamazepine/oxcarbazepine • Gold • Phenobarbital

Phenytoins Sulfasalazine • Sulfonamides * • Zalcitabine









Less common Captopril/lisinopril Carboplatin/cisplatin • Checkpoint inhibitors ** • Cytarabine • Cytokines (IL-2/GM-CSF) • Dapsone • Diflunisal • Fluindione • Hydroxychloroquine/chloroquine • Isoniazid

Isotretinoin/acitretin Lithium • Mercury compounds • Minocycline • Omeprazole/lansoprazole • Ribavirin • Telaprevir • Thalidomide • Tocilizumab • Vancomycin†









Rare‡ Abacavir Amiodarone • Aspirin (ASA) • Aztreonam • β-blockers • Chlorpromazine • Cimetidine • Ciprofloxacin • Clofazimine • Codeine • Erythropoietin • Fluorouracil • Imatinib • Indinavir • Lamotrigine • Methotrexate

Mitomycin C Nifedipine/diltiazem • Other NSAIDs • Penicillamine • Pentostatin • Pseudoephedrine • Rifampin • St John’s wort • Sulfonylureas • Tear gas (CS gas) • Terbinafine • Tobramycin • Tramadol • Vinca alkaloids • Zidovudine









*Includes furosemide. Ipilimumab, nivolumab, pembrolizumab. ** †

Not to be confused with red man syndrome due to rapid infusion of drug.

‡For additional drugs, see ref. 14.

Fig. 10.8 Erythroderma secondary to pityriasis rubra pilaris. Islands of sparing are noted on the flank and breast. Note the salmon color.

Table 10.3 Drugs associated with erythroderma.





Fig. 10.6 Sézary syndrome. Diffuse erythroderma with a red–brown color. Note the evidence of scratching on the lower back. Courtesy, Lorenzo Cerroni,  

MD.

182

Fig. 10.9 Erythroderma due to pemphigus foliaceus. Generalized erythema with widespread scale-crusts and large areas of erosion.  

Paraneoplastic erythroderma is most commonly associated with lymphoproliferative disorders, including lymphomas other than Sézary syndrome, and rarely thymomas. Of note, in these patients the skin does not contain malignant cellular infiltrates. In the case of solidorgan malignancies, the erythroderma usually appears late in the course of the disease. Fine scales and erythema can be accompanied by a brownish hue (i.e. melanoerythroderma). Additional signs of malignancy, such as cachexia or fatigue, may be seen.

with erythrodermic MF or Sézary syndrome are non-diagnostic23. Of note, epidermotropism of neoplastic lymphocytes is less commonly observed in these two disorders than in MF22. Diagnostic findings are frequently found in psoriatic erythroderma24, but less often in PRP (Fig. 10.10). It is important to remember that concurrent topical or systemic therapies as well as superimposed phenomena, e.g. atopic diathesis, contact dermatitis, impetiginization, can modify the histopathologic findings. In addition, multiple and sequential biopsies are often necessary in the evaluation of erythroderma.

CHAPTER

10 Erythroderma

Paraneoplastic erythroderma

Bullous dermatoses Among the bullous dermatoses, pemphigus foliaceus is the one most likely, albeit rarely, to present as erythroderma; erythrodermic forms of paraneoplastic pemphigus and bullous pemphigoid have also been reported (see Table 10.1; see also Chs 29 & 30). In pemphigus foliaceus, impetigo-like blisters and erosions are followed by collarettes of scale and scale-like crusts (Fig. 10.9). The erythroderma is usually preceded by localized lesions on the face and upper trunk.

Ichthyoses Erythroderma due to one of the inherited ichthyoses is usually present from birth or infancy. In neonates, one must consider congenital ichthyosiform erythroderma (CIE; previously referred to as non-bullous CIE), epidermolytic ichthyosis (previously referred to as bullous CIE), and Netherton syndrome (see Table 10.2; see also Ch. 57). As a rule, CIE presents as a collodion baby (90% of the cases)21, and within a few days after birth, an erythroderma with fine white scaling appears. Epidermolytic ichthyosis initially presents as generalized erythema with superimposed superficial blisters and erosions. This disorder may be mistakenly diagnosed as staphylococcal scalded skin syndrome or as a form of epidermolysis bullosa. Later, children develop spiny, corrugated hyperkeratoses, particularly in flexural areas, and blisters and erosions become less prevalent. Netherton syndrome manifests as an ichthyosiform erythroderma in neonates. It is associated with trichorrhexis invaginata (“bamboo hair”), elevated serum levels of IgE, and an immune defect that can result in life-threatening infections, particularly within the first years of life. Later, either the ichthyosiform erythroderma persists or ichthyosis linearis circumflexa develops, which is characterized by garland-like scaly eruptions.

Staphylococcal scalded skin syndrome Staphylococcal scalded skin syndrome (SSSS; see Ch. 74) is seen primarily in children ( T-cell infiltrate on skin biopsy Primary dermatosis e.g. atopic dermatitis, seborrheic dermatitis§, psoriasis§ (see Table 10.2)

Consider other forms of immunodeficiency (see Table 10.2 and Ch. 60)

GVHD in the setting of SCID‡

Drug eruption

“Nutritional dermatitis”§ (see Ch. 51)

during infancy; hairs should be clipped from the eyebrows as well as the scalp to maximize yield. * Often not inevident virtually all hairs in patients with trichothiodystrophy. **† Detected The differential diagnosis includes pustular psoriasis. ‡ Maternal–fetal or transfusion-related GVHD can also occur outside the setting of SCID. ¶ Progression of a morbilliform eruption to erythroderma can also characterize neonatal toxic shock-like exanthematous disease and GVHD. § Earlier onset is occasionally observed. AEC, ankyloblepharon–ectodermal dysplasia–clefting; CIE, congenital ichthyosiform erythroderma; CNS, central nervous system; EHK, epidermolytic hyperkeratosis; FTT, failure to thrive; GVHD, graft-versus-host disease; HSM, hepatosplenomegaly; KID, keratitis–ichthyosis–deafness; LAD, lymphadenopathy; PPK, palmoplantar keratoderma; SCID, severe combined immunodeficiency.

Fig. 10.12 Approach to the differential diagnosis of infantile erythroderma.  

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of protein lost through scaling in exfoliative dermatitis. Int J Dermatol 1999;38:91–5. Rothe MJ, Bernstein ML, Grant-Kels JM. Life-threatening erythroderma: diagnosing and treating the “red man”. Clin Dermatol 2005;23:206–17. Assaf C, Hummel M, Steinhoff M, et al. Early TCR-β and TCR-γ PCR detection of T-cell clonality indicates minimal tumor disease in lymph nodes of cutaneous T-cell lymphoma: diagnostic and prognostic implications. Blood 2005;105:503–10. Litt JZ, Shear NH. Litt’s Drug Eruption and Reaction Manual. 23rd ed. Boca Raton: CRC Press; 2017. Reeder M, Wood G. Drug-induced pseudo-Sézary syndrome: a case report and literature review. Am J Dermatopathol 2015;37:83–6. Walsh S, Diaz-Cano S, Higgins E, et al. Drug reaction with eosinophilia and systemic symptoms: Is cutaneous phenotype a prognostic marker for outcome? A review of clinicopathological features of 27 cases. Br J Dermatol 2013;168:391–401. Sigurdsson V, Toonstra J, van Vloten WA. Idiopathic erythroderma: a follow-up study of 28 patients. Dermatology 1997;194:98–101. Cherny S, Mraz S, Su L, et al. Heteroduplex analysis of T-cell receptor gamma gene rearrangement as an adjuvant diagnostic tool in skin biopsies for erythroderma. J Cutan Pathol 2001;28:351–5. Olsen E, Vonderheid E, Pimpinelli N, et al. Revisions to the staging and classification of mycosis fungoides and Sézary syndrome: a proposal of the International Society for Cutaneous Lymphomas (ISCL) and the

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cutaneous lymphoma task force of the European Organization of Research and Treatment of Cancer (EORTC). Blood 2007;110:1713–22. Torchia D, Miteva M, Hu S, et al. Papuloerythroderma 2009: Two new cases and systematic review of the worldwide literature 25 years after its description by Ofuji et al. Dermatology 2010;220:311–20. Judge MR, Harper JI. The ichthyoses. In: Harper JI, editor. Inherited Skin Diseases. The Genodermatoses. Oxford: Butterworth; 1996. p. 69–96. Zip C, Murray S, Walsh NMG. The specificity of histopathology in erythroderma. J Cutan Pathol 1993;20:393–8. Trotter M, Whittaker S, Orchard G, Smith N. Cutaneous histopathology of Sézary syndrome: a study of 41 cases with a proven circulating T-cell clone. J Cutan Pathol 1997;24:286–91. Tomasini C, Aloi F, Solaroli C, Pippione M. Psoriatic erythroderma: a histopathologic study of forty-five patients. Dermatology 1997;194:102–6. Kou K, Okawa T, Yamaguchi Y, et al. Periostin levels correlate with disease severity and chronicity in patients with atopic dermatitis. Br J Dermatol 2014;171:283–91. Hoeger PH, Harper JI. Neonatal erythroderma: differential diagnosis and management of the “red baby”. Arch Dis Child 1998;79:186–91. Boyd AS, Menter A. Erythrodermic psoriasis. Precipitating factors, course and prognosis in   50 patients. J Am Acad Dermatol 1989;21:  985–91.

10 Erythroderma

REFERENCES

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11 

Lichen Planus and Lichenoid Dermatoses Tetsuo Shiohara and Yoshiko Mizukawa

Chapter Contents Lichen planus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 188 Lichen striatus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 201 Lichen nitidus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 202 Erythema dyschromicum perstans . . . . . . . . . . . . . . . . . . . . 204 Keratosis lichenoides chronica . . . . . . . . . . . . . . . . . . . . . . . 205 Actinic lichen nitidus (summertime actinic lichenoid eruption) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 206 Annular lichenoid dermatitis (of youth) . . . . . . . . . . . . . . . . . 206

LICHEN PLANUS Synonym: ■ Lichen ruber planus

Key features ■ Idiopathic inflammatory disease of the skin, hair, nails and mucous membranes, seen most commonly in middle-aged adults ■ Flat-topped violaceous papules and plaques favoring the wrists, forearms, genitalia, distal lower extremities, and presacral area ■ Clinical variants include actinic, annular, atrophic, bullous, hypertrophic, inverse, linear, ulcerative, vulvovaginal–gingival, lichen planopilaris, lichen planus pigmentosus, and drug-induced ■ Some lichenoid drug eruptions have a photodistribution, while others are clinically and histologically indistinguishable from idiopathic lichen planus ■ The most commonly incriminated drugs include angiotensinconverting enzyme (ACE) inhibitors, thiazide diuretics, antimalarials, quinidine, and gold ■ Histologically, there is a dense, band-like lymphocytic infiltrate and keratinocyte apoptosis with destruction of the epidermal basal cell layer ■ In this T-cell-mediated autoimmune disorder, basal keratinocytes express altered self-antigens on their surface

Introduction

188

Lichen planus (LP), the prototype of lichenoid dermatoses, is an idiopathic inflammatory disease of the skin and mucous membranes. Classic LP is characterized by pruritic, violaceous papules that favor the extremities1. Histologically, a dense, band-like lymphocytic infiltrate is seen underlying an acanthotic epidermis with hypergranulosis, apoptosis, and destruction of the basal cell layer. The etiology and pathogenesis of LP are not fully understood, but the disorder has been associated with multiple environmental exposures, including viral infections, medications, vaccinations, and dental restorative materials. LP-like lesions that resemble idiopathic LP may also develop in chronic GVHD, where alloreactive T cells that recognize foreign major histocompatibility complex (MHC) molecules are central effectors (see Ch. 52). This lends support to the hypothesis that an autoimmune reaction against epitopes on lesional keratinocytes that have been modified by viral or drug antigens may be responsible for LP.

A number of clinically distinct inflammatory dermatoses have in common varying elements of a lichenoid tissue reaction, and they are referred to as lichenoid dermatoses (Table 11.1).

History The term lichen planus was initially introduced by Erasmus Wilson in 1869 to describe the condition that had been previously named leichen ruber by Hebra1.

Epidemiology Although its incidence varies depending upon geographic locale, cutaneous LP has been reported to affect from 0.2% to 1% of the adult population1, whereas oral lesions have been observed in up to 1–4% of the population. There is no overt racial predisposition. LP most commonly has its onset during the fifth or sixth decade, with two-thirds of patients developing the disease between the ages of 30 and 60 years. It is rare in both infants and the elderly and, typically, only 1–4% of patients are children. However, more recent studies have suggested that LP may actually be more common in children, especially in Arab populations. Oral LP is also quite uncommon in young people and it usually affects middle-aged to elderly individuals (mean age at diagnosis being 52 years). Although LP is frequently thought to have no gender predilection, some studies have found that women were affected nearly twice as often as men. Mucosal involvement, particularly oral lesions, is observed in up to 75% of patients with cutaneous LP, but the former can be the only manifestation of the disease. Only 10–20% of patients whose initial presentation is oral LP will eventually develop cutaneous LP. Although reports of familial LP are rare, it may occur more frequently than previously thought; for example, LP occurs in up to 10% of first-degree relatives of affected patients. Cases of familial LP tend to have an earlier age of onset, a higher relapse rate, and more frequent oral mucosal involvement. Of note, reports of concurrent LP in monozygotic twins who were living together suggest an environmental trigger.

Pathogenesis There is a growing body of evidence that LP represents T-cell-mediated autoimmune damage to basal keratinocytes that express altered selfantigens on their surface.

Target antigens Clinical observations and anecdotal evidence have long suggested a relationship between exposure to a number of exogenous agents (e.g. viruses, medications, contact allergens) and the development of LP (see Table 11.1). In theory, T cells that normally do not respond to skin (epidermis)-restricted antigens are primed by exogenous agents when the latter possess cross-reactive antigens that can activate autoreactive T cells via molecular mimicry. In other words, the T-cell receptors on the T cells that induce mucocutaneous LP could cross-react with exogenous antigens.

Hepatitis C virus

Of the many potential exogenous antigens, significant attention has been focused on the possible role of viruses, particularly hepatitis C virus (HCV). In several case–control studies, the prevalence of HCV (3.5–38%) was 2- to 13.5-fold higher in patients with LP than in controls. This association seems to be strongest in Japanese and Mediterranean populations, probably due to the high prevalence of HCV infection in these countries. In the US, one case–control study found that 12 (55%) of 22 patients with LP had anti-HCV antibodies, and this was significantly higher than the 25% of 40 psoriatic patients or

Lichen planus (LP) is an idiopathic inflammatory disease of the skin and mucous membranes whose primary lesion is a pruritic, violaceous papule. Histologically, a band-like lymphocytic infiltrate underlies an acanthotic epidermis with vacuolar degeneration of the basal cell layer. Several clinically distinct inflammatory dermatoses, including lichen striatus and lichen nitidus, have overlapping histologic features, and as a group they are referred to as lichenoid dermatoses. LP represents a T-cell-mediated autoimmune reaction against epitopes on lesional keratinocytes modified by viral or drug antigens. Clinical variants of LP include annular, atrophic, bullous, hypertrophic, inverse, linear, ulcerative, vulvovaginal–gingival, lichen planopilaris, and drug-induced. Lichen striatus is an asymptomatic, linear dermatosis composed of small flat-topped papules. It resolves spontaneously over months to a few years and primarily affects children. Lichen nitidus is an eruption of multiple, tiny, discrete, shiny papules (often in clusters) that favor the flexor aspects of the upper extremities, the genitalia and the anterior trunk. In erythema dyschromicum perstans, there is a slowly progressive appearance of gray or gray–brown, oval-shaped macules and patches; histologically primarily dermal melanophages are seen.

lichen planus, lichenoid dermatoses, lichenoid tissue reaction, lichen striatus, lichen nitidus, lichenoid drug eruption, erythema dyschromicum perstans, keratosis lichenoides chronica, actinic lichen nitidus, annular lichenoid dermatitis (of youth)

CHAPTER

11 Lichen Planus and Lichenoid Dermatoses

ABSTRACT

non-print metadata KEYWORDS:

188.e1

Lichenoid dermatoses

Possible target antigens

Lichen planus

V, D, C, T

Lichenoid drug eruption

D

Erythema dyschromicum perstans

V, D

Graft-versus-host disease (see Ch. 52)

Allo, V

Keratosis lichenoides chronica Pityriasis lichenoides* (see Ch. 9)

V

Lichen nitidus

V

Lichen striatus

V

Lichen sclerosus (see Ch. 44)

V, Auto

Fixed drug eruption (see Ch. 21)

D

Erythema multiforme (see Ch. 20)

V, D, C

Lupus erythematosus (see Ch. 41)

V, Auto, D

Dermatomyositis (see Ch. 42)

V, Auto, T, D

Paraneoplastic pemphigus (see Ch. 29)

T

Mycosis fungoides (see Ch. 120)

T, V

Lichenoid pigmented purpura (see Ch. 22)

D, V

Secondary syphilis (see Ch. 82)

*Acute and chronic. Table 11.1 Major lichenoid dermatoses and possible associated target antigens. The variation in clinical presentations may reflect the differences in the effector mechanisms by which epidermal cells are damaged and/or target antigens. The shaded entities are discussed in this chapter. Allo, alloantigens; Auto, autoantigens; C, contact allergens; D, drug antigens; T, tumor antigens; V, viral antigens.

the 0.17% of blood donors who tested positive2. A more recent systematic review and meta-analysis of existing epidemiologic studies demonstrated that an association between LP and HCV infection did exist in certain geographic regions (e.g. East and Southeast Asia, South America, the Middle East, Europe), but not in others (e.g. North America, South Asia, and Africa)3. Of the various types of LP, it is the oral form that is most commonly viewed as a manifestation of HCV infection. By PCR, HCV RNA was detected in 93% of oral LP lesions4, suggesting HCV replication within LP lesions. However, these PCR results were not confirmed by other studies. Of note, an increased frequency of the HLA-DR6 allele has been reported in Italian patients with HCV-associated oral LP5, raising the possibility that CD4+ T cells activated upon recognition of HCVencoded peptides bound to HLA-DR6 molecules could be directly involved in the pathogenesis of LP. In support of this possibility, HCV tetramer analysis has shown that HCV-specific CD4+ and/or CD8+ T cells are present with higher frequency in oral LP lesions compared with the circulating compartment, suggesting that they play a role in the pathogenesis of LP6. In patients receiving anti-HCV therapy, originally interferon and ribavirin and more recently protease and polymerase inhibitors, the effects on mucocutaneous LP have varied6a. Lesions have improved in some patients while others experienced a flare of disease activity.

Other viruses

With regard to the role of other viruses in LP, human herpesvirus (HHV)-6 was detected in 65–100% of oral LP lesions by in situ hybridization and immunohistochemical techniques when it was absent from normal oral tissues. In addition, a retrospective survey of 18 lesional LP tissue samples (as well as 11 non-lesional LP and 11 lesional psoriasis samples) found that 11 of the 18 lesional LP samples contained HHV-7 DNA as compared to 1 of 11 and 2 of 11 non-lesional LP and lesional psoriasis samples, respectively7. Remission of LP was associated with decreased HHV-7 protein expression, in particular within infiltrating plasmacytoid dendritic cells8.

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11 Lichen Planus and Lichenoid Dermatoses

MAJOR LICHENOID DERMATOSES AND POSSIBLE ASSOCIATED TARGET ANTIGENS

There are also sporadic case reports of LP lesions developing in areas recently affected by herpes simplex virus (HSV) or varicella–zoster virus (VZV) infections9 (see Table 80.7). Possible explanations include a nonspecific Koebner phenomenon or isotopic response or an immune reaction to the virus. In a recent immunohistochemical study involving eight patients, VZV-gE antigen was detected within the eccrine epithelia of LP lesions if they were in a dermatomal (zosteriform) pattern but not if they were in a linear array along the lines of Blaschko10. Two of the patients with the dermatomal pattern reported no preceding episode of herpes zoster, leading the authors to speculate if LP could be triggered by subclinical VZV reactivation. A link between human papillomavirus (HPV) and oral LP has also been suggested based upon the identification of a clonal expansion of HPV-16-specific CD8+ T cells within the lesions11. While measurements (via PCR) of viral genomes within lesional skin or blood have been inconclusive, as noted above, virus-specific T cells have been detected within lesions. This suggests that the pathology is a direct consequence of immune responses, perhaps to virally induced alterations in the antigenicity of epidermal cells rather than the viruses themselves. However, it is also possible that virus-specific T cells are nonspecifically trapped within sites of inflammation, having been activated systemically or locally at distant sites, and then they expand and mediate tissue damage “accidently” due to cross-reactivity with other antigens (e.g. drugs)12.

Vaccines

A number of reports have described the appearance of LP after administration of influenza vaccines and different types of HBV vaccines13. The time interval between the initial dose and the development of cutaneous or mucosal lesions has varied from a few days to 5 months. One recommendation is that patients who develop LP before completing their vaccination series should avoid further injections because of an increased risk of developing severe LP lesions, including the bullous variant.

Bacteria

Investigations regarding a relationship between bacteria and LP have been limited. In particular, a definitive etiologic role for Helicobacter pylori has not been proven.

Contact allergens

The role of contact allergy to a variety of metals in the exacerbation or induction of oral LP has been well described, based on exposure to metallic dental restorations or constructions, positive patch test results, and then regression or complete clearing after removal of the sensitizing metal and replacement with other materials. Because involved allergens are dissolved and spread via saliva, mucosal reactions may extend beyond the contact areas. The metals that aggravate oral LP include amalgam (mercury), copper, and gold. Although approximately 95% of patients had improvement after removal of the sensitizing metal, 75% of patients with negative patch test results also reported clearing of oral LP after removal of the metal and replacement with other materials. One possible explanation for this finding is that mercury served as an irritant and induced lesions via the Koebner phenomenon. Of note, the development of contact allergy to metals within dental restorations in patients with LP could be explained by easy penetration of the metal via damaged mucosa.

Drugs

Cutaneous eruptions similar or even identical to LP, both clinically and histologically, have been linked to a variety of drugs. The terms “lichen planus-like” and “lichenoid” are often used to describe this phenomenon14,14a. A wide variety of drugs have been associated with lichenoid drug eruptions and the list of such drugs steadily increases (Table 11.2). However, recurrence of the lesions subsequent to drug rechallenge has not been documented for the majority of these drugs.

Autoantigens, including tumor antigens In occasional patients, LP has been reported as a possible autoimmune reaction triggered by an underlying neoplasm. Also, a lichenoid tissue reaction is seen in patients with paraneoplastic pemphigus. The temporal relationship between LP and the underlying neoplasm in the reported patients suggests that the neoplasms may have stimulated a cell-mediated immune response against tumor antigens that led to the

189

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Papulosquamous and Eczematous Dermatoses

3

DRUGS IMPLICATED IN LICHENOID DRUG ERUPTIONS

Antimicrobials Ethambutol Griseofulvin • Isoniazid • Ketoconazole

Pyrimethamine Streptomycin • Sulfamethoxazole • Tetracyclines









Antihypertensives Captopril Enalapril • Labetalol • Methyldopa • Propranolol

Diazoxide* Doxazosin • Nifedipine • Prazosin









Antimalarials Chloroquine Hydroxychloroquine



Quinacrine





Antidepressants, anti-anxiety drugs, antipsychotics and anticonvulsants Amitriptyline Carbamazepine • Chlorpromazine • Imipramine

Levomepromazine Lorazepam • Methopromazine • Phenytoin









TNF-α inhibitors Etanercept Infliximab

Adalimumab Lenercept









Diuretics Chlorothiazide Hydrochlorothiazide

Furosemide Spironolactone









Hypoglycemic agents Chlorpropamide Glyburide

Tolazamide Tolbutamide









Metals Gold salts‡ Arsenic • Bismuth

Mercury Palladium









NSAIDs Acetylsalicylic acid Benoxaprofen • Diflunisal • Fenclofenac • Flurbiprofen

Ibuprofen Indomethacin • Naproxen • Sulindac









Miscellaneous drugs Allopurinol Amiphenazole • Anakinra • Cinnarizine • Cyanamide • Dapsone • Gemfibrozil • Hydroxyurea • Imatinib • Interferon-α • Iodides • Isotretinoin • Levamisole • Lithium • Mercapto-propionylglycine • Mesalamine

Methycran Nivolumab • Omeprazole • Orlistat • Pembrolizumab • Penicillamine • Procainamide • Propylthiouracil • Pyrithioxin • Simvastatin • Quinidine • Quinine • Rituximab • Sildenafil • Sulfasalazine • Trihexyphenidyl









*‡ Also used to treat hypoglycemia.

Including in alcoholic beverages, e.g. Goldschläger.

Table 11.2 Drugs implicated in lichenoid drug eruptions. More commonly associated drugs are in bold. NSAIDs, nonsteroidal anti-inflammatory drugs.

190

generation of autoreactive T cells that cross-reacted against antigens expressed on epidermal cells. Although numerous case reports describe patients with both LP and autoimmune diseases, studies with larger numbers of patients with LP have shown no increased incidence of autoimmune diseases. Multiple investigators have described a significant association between specific HLA antigens and LP; for example, an increased frequency of HLA-B27, HLA-B51, HLA-Bw57 (oral LP in English patients), HLA-DR1 (cutaneous and oral LP), HLA-DR9 (oral LP in Japanese and Chinese patients), and HLA-DR6 (HCV-associated oral; see above). However, a true association with a particular HLA allele has been difficult to establish because of significant geographic heterogeneity and clinical patient selection. A murine model of LP has been established by employing autoreactive T cells capable of producing interferon-γ (IFN-γ) and tumor necrosis factor-α (TNF-α) (Fig. 11.1)15. Intradermal inoculation of CD4+ autoreactive T-cell clones into the footpads of syngeneic mice can induce local histologic changes similar to LP or lichenoid skin diseases. In this model, the autoreactive T cells can respond to self MHC class II antigens constitutively expressed on macrophages and Langerhans cells, and they migrate into the epidermis, resulting in epidermal injury. These T cells, therefore, can induce LP-like lesions without any alteration in the antigenicity of the epidermis. In subsequent studies, desmoglein-specific T cells were also capable of inducing LP-like changes histologically16. Thus, LP could be induced by different types of T cells – those that specifically target antigens constitutively expressed in the epidermis but also T cells that target antigens not expressed within the epidermis. Additionally, in the natural disease process, exogenous agents (e.g. viral infections, drugs) could induce alterations in the antigenicity of epidermal cells and trigger the activation of T cells. Of note, such autoaggressive reactions could function to eliminate abnormal keratinocytes altered by these exogenous agents. However, in the situation where T cells initially responding to self-antigens modified by exogenous agents subsequently become cross-reactive with some self-epitopes, these T cells would then chronically respond to the previously ignored selfepitopes, leading to perpetuation of an autoimmune attack by such T cells15 rather than elimination of the abnormal keratinocytes.

Effector cells There are conflicting data regarding the phenotype of the inflammatory infiltrate in LP lesions. Although initial immunohistochemical studies showed that the cellular infiltrate contained an increased ratio of CD4+ : CD8+ T cells17, other investigators found a predominance of CD8+ T cells, particularly in older lesions. Evidence to support the crucial role of CD8+ T cells in autoimmune damage to basal keratinocytes has been provided by CD8+ T cells isolated from lesional skin; these T cells exhibited specific cytotoxic activity against autologous lesional and normal keratinocytes18. Basal cell damage as evidenced by apoptotic DNA fragments is greatest in the epidermis. A possible mechanism is as follows: IFN-γ produced by CD8+ T cells upregulates Fas expression by keratinocytes, rendering them susceptible to T-cell-mediated, Fas ligand-driven apoptosis. This interaction triggers a cascade of intracellular enzymatic reactions resulting in DNA fragmentation (see Ch. 107). In addition to Fas, death receptor-induced apoptosis involves signaling processes via TNF-R1, TRAIL-R1 and 2, and DR3 or DR6. Because type 1 helper T cells (Th1), such as the autoreactive CD4+ T cells in the murine model (see Fig. 11.1), can produce large amounts of IFN-γ and TNF-β upon activation and thereby induce or enhance the expression of apoptosisassociated proteins such as Fas and TRAIL, they may also play a role in extensive epidermal damage by promoting apoptotic death of keratinocytes. More recent studies have shown that granule exocytosis with release of perforin and granzyme B, rather than the Fas/Fas-ligand system, is the main pathway of cytotoxicity mediated by CD4+ and CD8+ T cells in humans19. However, a combination of the two mechanisms is most likely, with predominance depending upon the particular stage in the disease process.

The innate immune system, regulatory T cells (Tregs), and Th17 cells

Recent studies have provided evidence for the involvement of Tolllike receptor (TLR) signaling in the induction of autoimmunity. As depicted in Fig. 4.1, certain TLRs recognize viral RNA as well as

MOUSE MODEL FOR THE LICHENOID TISSUE REACTION Natural disease process

Initiating factors in genetically predisposed patient

Experimental mouse model

CD4+ autoreactive T-cell clone

PHASES OF LICHEN PLANUS Pathogen Trauma

A

B

Keratinocyte TLR activation

T-cell-mediated epidermal damage

IFN-α release

T-cell activation

Chemokine/ cytokine release Treg migration

T-cell migration

Plasmacytoid dendritic cell

Memory T cell

Treg cell

Immune surveillance T cell

IFN-α

Cytotoxic granules

Keratinocyte apoptosis

Chemokine/cytokine Chemokine/cytokine receptor

FasL

T-cell apoptosis

Fas

imidazoquinolones (e.g. imiquimod). Interestingly, topical application of imiquimod, which can lead to enhanced migration and maturation of dermal dendritic cells, followed by increased production of proinflammatory cytokines and activation of antigen-specific CD8+ T cells, may exacerbate lesions of LP. In some autoimmune diseases, T-cell differentiation may shift from Treg cells (immune suppression) to Th17 cells (see Ch. 4), but an increase in both populations has been found in LP lesions. However, the functionality of the Treg cells within these lesions has been questioned.

Effector T cells’ access to the epidermis

A critical event in the initiation of immune responses in LP lesions is for memory T cells to migrate from the circulation into a particular

CHAPTER

11 Lichen Planus and Lichenoid Dermatoses

Fig. 11.1 Mouse model for the lichenoid tissue reaction. Because in humans all the analyses are performed on existing skin lesions (after the inflammatory response is underway), it is difficult to provide insight into initiating events and to establish whether the T cells present are indeed relevant to the pathogenesis. This experimentally induced animal model has the advantage that the orchestrated series of events resulting in epidermal injury can be examined from the onset and over time. Of note, injection of suboptimal or supraoptimal doses of T cells can lead to the histologic features of fixed drug eruption or toxic epidermal necrolysis, respectively.

Fig. 11.2 Phases of lichen planus. A In the induction phase, keratinocytes and plasmacytoid dendritic cells (pDCs), upon stimulation of their Toll-like receptors (TLRs) by pathogens or endogenous ligands, can release type 1 IFNs (e.g. IFN-α); this represents an early event in the cascade leading to T-cell-mediated epidermal damage. Activated keratinocytes, via production of IL-1β and TNF-α, can induce activation and migration of DCs. Chemokines, such as IP-10/ CXCL10, released locally by pDCs, serve to attract CXCR3-expressing CD8+ or CD4+ effector memory T cells (which have differentiated from naive T cells within lymph nodes following presentation by DCs of self-peptides modified by exogenous antigens [viruses, medications and contact allergens]). Additional chemokine and chemokine receptor pairs have also been implicated in this process (see Table 11.3), and the precise mix of chemokines and cytokines released into the tissue plays an important role in determining the composition of the inflammatory infiltrates. B In the evolution phase, effector T cells (Te) that come to express skin-homing receptors (E-selectin ligands) migrate into the inflammatory site and upon recognition of antigens, are activated and release proinflammatory cytokines and cytotoxic granules, which in turn cause epidermal injury. In addition, Fas/FasL interactions can trigger cell death of both lymphocytes and keratinocytes with possible elimination of potentially harmful autoaggressive T cells. “Inflammatory” and “homeostatic” chemokines produced by keratinocytes direct the traffic of not only “pathogenic” T cells (Te) but also “immune surveillance” T cells (Ts) or regulatory T cells (Treg) into the sites; the relative balance of chemokines produced may determine the outcome of the T-cell-mediated immune responses. FasL, Fas ligand.

skin site. Release of type 1 IFNs, such as IFN-α, from activated plasmacytoid dendritic cells (pDCs) and keratinocytes may be critical in inducing skin-directed migration of effector memory T cells (Fig. 11.2A). Stimulation of TLRs expressed on pDCs and keratinocytes by pathogens or endogenous ligands (released via skin damage) represents one of the earliest events and it is sufficient to induce type 1 IFN production. Type 1 IFN signaling and type 1 IFN-inducible chemokines (e.g. IP-10/CXCL10) then serve to recruit chemokine receptor CXCR3expressing effector memory T cells (Th1 cells) into the skin via CXCR3/ IP-10 interactions (Table 11.3). A number of other molecular interactions, such as CCR4/TARC, CCR10/CTACK and LFA-1/ICAM-1 expressed on T cells and keratinocytes, respectively, have also been implicated in the recruitment of memory T cells and pDCs to the

191

SECTION

Papulosquamous and Eczematous Dermatoses

3

CHEMOKINES AND CHEMOKINE RECEPTORS INVOLVED IN T-CELL MIGRATION INTO THE SKIN

Chemokine receptors

Functional type of chemokines/T cells attracted†

RANTES (CCL5) MCP-2 (CCL8) Eotaxin-1, -2, -3 (CCL11, 24, 26)

CCR3

Inflammatory/Th2 cells

TARC (CCL17) MDC (CCL22)

CCR4

Inflammatory/Th2 cells

MIP-1α,β (CCL3, 4) RANTES (CCL5) MCP-2 (CCL8)

CCR5

Inflammatory/Th2 cells

CCL1

CCR8

Homeostatic/memory T cells

CTACK (CCL27) MEC (CCL28)

CCR10

Homeostatic/memory T cells

MIG (CXCL9) IP-10 (CXCL10) I-TAC (CXCL11)

CXCR3

Inflammatory/Th1 cells

CXCL16

CXCR6

Inflammatory/Th1 cells

Chemokines*

*Cytokines that have chemoattractant activity; two major groups are differentiated based on the position of two cysteine (C) residues compared with the other amino acid residues (X): CXC- or α-chemokines and CC- or β-chemokines. †“Inflammatory” chemokines are produced at sites of cutaneous inflammation and mediate skin-directed migration of memory T cells (Th1, Th2); “homeostatic” chemokines are constitutively produced within non-inflamed skin and mediate skin-directed migration of memory T cells with an “immune surveillance” function. Table 11.3 Chemokines and chemokine receptors involved in T-cell migration into the skin. Binding of MCP-1 (CCL2) to CCR2 on monocytes plays an important role in their recruitment to sites of cutaneous inflammation. CCR, receptor for CC chemokines; CTACK, cutaneous T-cell-attracting chemokine; CXCR, receptor for CXC chemokines; IP-10, interferon-inducible protein 10; I-TAC, interferon-inducible T cell α-chemoattractant; MCP-2, monocyte chemoattractant protein 2; MDC, macrophage-derived chemokine; MEC, mucosal-associated epithelial chemokine; MIG, monokine induced by interferon-γ; MIP-1α, macrophage inflammatory protein 1α; RANTES, regulated on activation normal T cell expressed and secreted; TARC, thymus- and activation-regulated chemokine.

192

dermal–epidermal junction20–22. Because IFN-α from pDCs induces IFN-γ production by T cells and IFN-γ also sustains IFN-α production, a positive feedback loop may be operational within LP lesions. This ordered sequence of events provides a possible explanation for why LP lesions develop within traumatized sites and virally induced lesions. Although chemokines produced at inflammatory skin sites are thought to regulate the composition of the Th1- or Th2-driven cellular infiltrates, memory T cells with a “surveillance” function can also migrate to skin sites under non-inflamed conditions (Fig. 11.2B). “Homeostatic” chemokines constitutively produced under non-inflamed conditions can mediate the skin-directed migration of these “immune surveillance” T cells (see Table 11.3), leading to clearance of invading pathogens such as viruses. In addition, Treg cells that have the capacity to suppress activated T cells are also able to enter inflamed skin sites. However, in LP lesions, there is no definitive means of distinguishing “immune surveillance” T cells or protective Treg cells from “pathogenic” T cells. Lastly, identification of the cells responsible for LP is further complicated by the presence of both skin tissue-resident memory T cells (TRM cells) and migratory central memory T cells (TCM cells) within skin lesions, with the former, whose physiologic role includes local protection against pathogens, becoming a mediator of tissue damage. Of note, while the epidermotropic migration of effector T cells leading to epidermal damage in lichenoid tissue reactions is clearly a complicated, multistep process, the latter can be bypassed (at least in part) in the case of fixed drug eruptions (FDE). This is because effector CD8+ T cells responsible for the epidermal damage persist as a stable population within previously affected sites, even when the skin becomes normal-appearing23. In particular, CD8+ TRM cells (see above) populate

PROPOSED CASCADE OF EVENTS WITHIN LESIONS OF FIXED DRUG ERUPTION Early stage

Fully evolved stage

Resting stage Keratinocyte

IFN-γ TNF-α

Further damage to keratinocytes

Intraepidermal CD8+ TRM cells Blood vessel

Resolution stage

Influx of TCM cells

= TRM cell = TCM cell

CD4+ Treg cells

= Treg cell = Mast cell

Keratinocyte apoptosis

Fig. 11.3 Proposed cascade of events within lesions of fixed drug eruption. Skin tissue-resident memory T cells (TRM cells) and migratory central memory T cells (TCM cells) both play a role in producing tissue damage. In the resting stage, a stable population of CD8+ TRM cells resides within the epidermis without exerting their cytotoxic potential (the physiologic role of these cells includes local protection against pathogens). When stimulated by crossreactive antigens such as drugs, TRM cells then display cytolytic activity towards surrounding keratinocytes. The TRM cells also release IFN-γ and TNF-α into the local environment, leading to the recruitment of CD4+ and CD8+ TCM cells from the circulation into the skin. This leads to additional tissue damage. During the resolution stage, Treg cells are recruited into the site of inflammation, in part due to the release of preformed cytokines, including IL-16, by mast cells. Although the majority of activated cell populations are removed by apoptosis (see Fig. 11.2), a proportion of TRM cells are prevented from undergoing apoptosis by IL-15 produced by surrounding keratinocytes.

the epidermis of “resting” FDE lesions and although these cells are the principal mediators of localized tissue damage, CD4+ and CD8+ TCM cells, recruited from the circulation, also contribute to the epidermal damage (Fig. 11.3).

Sweating disturbance Sweat contains interleukin (IL)-1, IL-6, IL-8, and TNF-α, proinflammatory cytokines that have been implicated in the induction of T-cell recruitment into the skin23a-23c. In theory, extravasated sweat could explain the syringotropic T-cell migration occasionally seen in the early lesions of LP. Whether leakage of sweat near the dermal–epidermal junction also represents an early event in the inflammatory cascade remains to be determined.

Clinical Features The characteristic primary lesion of LP is a small, polygonal-shaped, violaceous, flat-topped papule (Fig. 11.4); occasionally papules are umbilicated. The surface is slightly shiny or transparent, and a network of fine white lines called “Wickham striae” or small gray–white puncta are also seen. The latter correspond histologically to focal thickening of the granular layer. Wickham striae are readily apparent by dermoscopy (see Ch. 0). Postinflammatory hyperpigmentation is also a common finding (Fig. 11.5).

The most common sites of involvement are the flexor wrists and forearms, the dorsal hands, the shins, and the presacral area. Mucous membranes, especially the oral mucosa (see below), are affected in more than half of patients, and this is often the only site of disease. Lesions are also commonly seen on the glans penis (Fig. 11.7A), where they can have an annular or figurate configuration and may become erosive. Several of the distinctive clinical variants of LP are discussed separately. The duration of the disease can vary depending upon the LP variant. While the lesions of exanthematous LP typically resolve within a year, hypertrophic, oral and nail LP tend to be more persistent. In particular, ulcerative oral LP may be a lifelong affliction.

Actinic LP This variant is reported under a variety of names, including LP actinicus, LP subtropicus, LP tropicus and lichenoid melanodermatitis. Although the majority of reported patients have been from Middle Eastern countries, this variant has been observed worldwide. Most patients are young adults or children, but there is no gender predilection. Onset of this variant is typically during the spring and summer, and lesions primarily involve sun-exposed skin of the face, followed by the neck and dorsal surfaces of the hands and arms. The lesions usually

CHAPTER

11 Lichen Planus and Lichenoid Dermatoses

The papules of LP may be widely dispersed or they may cluster or coalesce into larger plaques. LP is usually pruritic. Although the Koebner phenomenon (i.e. isomorphic response) is commonly seen in LP (Fig. 11.6), excoriations and impetiginization are unusual. A linear array of lesions can be seen as a consequence of the Koebner phenomenon or an isotopic response at the site of healed herpes zoster, as well as in the linear variant of LP which follows the lines of Blaschko.

Fig. 11.6 Koebnerization of lichen planus into the site of the excision of the saphenous vein. Lesions also appeared where Steri-Strips™ had been applied.

A

B

Fig. 11.4 Lichen planus. A Violaceous papules and plaques with white scale and Wickham striae on the dorsal foot. B Note the flat-topped (lichenoid) nature of the violaceous papules on the penis. B, Courtesy, Louis A Fragola, Jr, MD.

Fig. 11.5 Lichen planus with postinflammatory hyperpigmentation. A The clinical diagnosis is based upon the presence of violaceous plaques with scale, Wickham striae (uppermost lesion), and postinflammatory hyperpigmentation. B The most notable finding is postinflammatory hyperpigmentation, but the distribution on the flexor wrists and the presence of Wickham striae in the upper lesion on the right arm point to the diagnosis. A, Courtesy, Frank Samarin, MD.

A

B

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3

Fig. 11.7 Annular lichen planus. A On the penis, the lesions have a figurate outline with a thin pale violet border and central hyperpigmentation. B On the trunk, the lesions have a thin hyperpigmented rim. A, Courtesy, Frank Samarin, MD.

A

Fig. 11.8 Exanthematous lichen planus. Papulosquamous lesions on the back.

Common sites of involvement include the intertriginous zones and the lower extremities (Fig. 11.9A). Simultaneous occurrence of LP and lichen sclerosus has been reported as has an annular atrophic variant with complete loss of elastic fibers in the center of the lesions.

Bullous LP and LP pemphigoides

B

consist of red–brown plaques with an annular configuration, but melasma-like hyperpigmented patches have been observed. In temperate climates, spontaneous improvement may occur during the winter months.

Acute (exanthematous) LP Because lesions are usually widely distributed and disseminate rapidly, this form is also known as exanthematous or eruptive LP. The commonly affected areas include the trunk (Fig. 11.8), the inner aspects of the wrists and the dorsal feet. Reports in the literature of this variant probably include lichenoid drug eruptions. The clinical course is usually self-limited, and in general lesions resolve with hyperpigmentation within 3 to 9 months.

Annular LP This form is thought to occur when papules spread peripherally and the central area resolves. The annular edge is slightly raised and typically purple to white in color, while the central portion is hyperpigmented or skin-colored (see Fig. 11.7). Lesions can resemble porokeratosis, tinea or if there is minimal scale, granuloma annulare. Annular lesions occur in ~10% of patients with LP and are usually scattered among more typical lesions, but the former may represent the predominant finding. The most common site of involvement is the axilla, followed by the penis, extremities, and groin. While some have pruritus, most patients are asymptomatic.

Atrophic LP

194

Atrophic LP may represent a resolving phase of LP, given the history of the lesions: papules coalesce to form larger plaques that over time become atrophic centrally, with residual hyperpigmentation. The clinical appearance of atrophic LP is likely a result of thinning of the epidermis rather than degeneration of elastic fibers, and the epidermal atrophy may be accentuated by the use of potent topical corticosteroids.

In bullous LP, vesicles and bullae develop within pre-existing lesions of LP as a result of intense lichenoid inflammation and significant epidermal damage (Fig. 11.9B). This leads to epidermal–dermal separation, i.e. exaggerated Max-Joseph spaces. In contrast, patients with LP pemphigoides have circulating IgG autoantibodies directed against the 180 kDa BP antigen (BP180; BPAG2), as in idiopathic BP. However, compared to BP, LP pemphigoides has a younger age of onset. In this variant, bullae can arise either within LP lesions or previously uninvolved skin (Fig. 11.9C), but the diagnosis of LP usually precedes the LP pemphigoides. These findings suggest that damage to the basal layer by a lichenoid infiltrate may expose hidden antigens to the autoreactive T cells, leading to the formation of autoantibodies and subepidermal bullae. Indeed, LP pemphigoides evolving into pemphigoid nodularis has been described. There are conflicting results regarding the autoantigen in LP pemphigoides, but one study suggested a novel epitope within the C-terminal NC16A domain of BP180 (see Fig. 31.9)24. To date, no reactivity against the 230 kDa BP antigen, type VII collagen, or the laminin-5 subunits has been detected. An additional difference between these two disorders is the finding of abundant VZV antigen-bearing monocytes and mast cells in the upper dermis of bullous LP lesions as opposed to such cells being rare in LP pemphigoides.

Hypertrophic LP This variant is also referred to as LP verrucosus (Fig. 11.10). Extremely pruritic, thick, hyperkeratotic plaques are seen primarily on the shins or dorsal aspect of the feet and may be covered by a fine adherent scale. The lesions are usually symmetric and tend to be chronic because of repetitive scratching. The average duration of hypertrophic LP in patients whose lesions had cleared was reported to be 6 years. Chronic venous stasis frequently contributes to the development of this condition. As in hypertrophic LE, squamous cell carcinoma (SCC) may arise within longstanding hypertrophic LP, and distinguishing pseudoepitheliomatous hyperplasia from SCC can be difficult. In one retrospective review, the presence of an increased number of eosinophils pointed to the diagnosis of hypertrophic LP25.

Inverse LP In this unusual variant, an inverse distribution pattern is observed. Pink to violaceous papules and plaques appear in intertriginous zones (axillae > inguinal and inframammary folds) and less often in the popliteal and antecubital fossae (Fig. 11.11). Occasionally, there are LP lesions elsewhere on the body. Hyperpigmentation is usually present as well and it may be the sole manifestation, leading to overlap with LP pigmentosus.

Fig. 11.10 Hypertrophic lichen planus. A On the shins, very thick discrete plaques with dyspigmentation are admixed with smaller linear plaques and areas of postinflammatory hyperpigmentation. B On the dorsal digits, thin violaceous plaques in addition to thick keratotic plaques that favor the knuckles. B, Courtesy, Joyce Rico, MD.

A

CHAPTER

11 Lichen Planus and Lichenoid Dermatoses

Fig. 11.9 Unusual variants of lichen planus. A Atrophic lichen planus of the lower extremities. B Bullous lichen planus on the shin. C Lichen planus pemphigoides in a patient with anti-BP180 autoantibodies.

A

B

B

Fig. 11.11 Inverse lichen planus. Oval thin violaceous plaques in the axilla. Postinflammatory hyperpigmentation is also present. Courtesy, Jeffrey P Callen, MD.

LP pigmentosus

C

LP pigmentosus typically presents as brown to gray–brown macules in sun-exposed areas of the face and neck, usually with no preceding erythema and often evolving into diffuse or reticulated pigmentation (see Ch. 67). This variant favors individuals with skin types III and IV, in particular those from South Asia, Latin America, and the Middle East. Involvement of intertriginous sites is occasionally observed (Fig. 11.12), and a linear distribution following the lines of Blaschko has also been described. In the photodistributed form, topical application of mustard oil, which contains a potential photosensitizer, has been implicated as a possible trigger. Given the similarity of histologic findings, distinction from erythema dyschromicum perstans (EDP) is based primarily upon clinical features. In EDP, there is often truncal involvement, a younger mean age of

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Papulosquamous and Eczematous Dermatoses

3

A

Fig. 11.12 Lichen planus pigmentosus – intertriginous variant. The initial clinical presentation was that of multiple hyperpigmented macules and patches within the axillary vaults.

onset, and lack of either diffuse pigmentation or coexisting LP lesions. The latter is seen in ~20% of patients with LP pigmentosus. Occasionally, small nests of keratinocytes are seen within the basal layer and these may be confused with nests of melanocytes.

Lichen planopilaris In lichen planopilaris, involvement of the hair follicle is observed, both clinically and histologically. This variant is also called follicular LP and LP acuminatus. Multiple, keratotic plugs surrounded by a narrow violaceous rim are observed primarily on the scalp, although other hairbearing areas can also be affected (Fig. 11.13). The inflammatory process may result in scarring and loss of follicular structure, i.e. a permanent alopecia. Over time, the areas of involvement often “burn out” centrally and are indistinguishable from other causes of “endstage” cicatricial alopecia (see Ch. 69). However, examination of the periphery may reveal the primary lesions. Women are more frequently affected than men, and this form may occur alone or with typical LP lesions elsewhere. A variant of lichen planopilaris known as Graham-Little–Piccardi– Lassueur syndrome is characterized by the triad of: (1) non-cicatricial loss of pubic and axillary hairs and disseminated spinous or acuminated follicular papules (see Fig. 11.13B); (2) typical cutaneous or mucosal LP; and (3) scarring alopecia of the scalp with or without atrophy (see Fig. 11.13C). These features need not be present simultaneously. Another more recently recognized variant of LP of the scalp is frontal fibrosing alopecia which occurs primarily in older women and can affect the eyebrows as well (see Ch. 69).

Linear LP Although linear lesions frequently occur in sites of scratching or trauma in patients with LP as a result of the Koebner phenomenon, the term linear LP (Fig. 11.14) is usually reserved for lesions that appear spontaneously within the lines of Blaschko (see Fig. 11.13A). This form has also been referred to as zosteriform, but with the exception of LP developing within the site of previous herpes zoster, the distribution pattern of LP is generally not dermatomal. The possibility exists that when LP has a strictly dermatomal pattern, it may have been preceded by “zoster sine herpete”. As noted previously (see Pathogenesis), in a case series, VZV antigen was detected in the zosteriform variant of LP but not in the linear variant10.

Discoid lupus erythematosus/lichen planus overlap syndrome 196

Patients whose lesions have overlapping features of both LP and lupus erythematosus (LE) have been reported. These lesions are preferentially located in acral sites. Histologic and direct immunofluorescence (DIF) microscopic findings show features of both LP and LE. Whether

B

C

Fig. 11.13 Lichen planopilaris. A Keratotic spines surrounded by a violaceous rim in the linear variant. B Multiple clusters of follicular keratotic plugs on the leg admixed with small violaceous papules, some of which are folliculocentric. C Cicatricial alopecia with “end-stage” changes centrally, but perifollicular inflammation at the margins.

systemic immunologic abnormalities such as high titers of ANA are present in these patients is controversial, but case reports suggest that some patients have disease at the chronic cutaneous LE end of the clinical spectrum while others meet the criteria for systemic LE.

Nail LP The nails are affected in ~10% of patients with LP and usually several nails are affected (see Ch. 71). The characteristic nail abnormalities include lateral thinning (Fig. 11.15A), longitudinal ridging, and fissuring (Fig. 11.15B). These changes are manifestations of matrix damage, which can lead to scarring and dorsal pterygium formation if left

Fig. 11.14 Linear lichen planus. Coalescence of violaceous lesions with Wickham striae along the lines of Blaschko on an extremity. Note the postinflammatory hyperpigmentation proximally. Courtesy, Joyce Rico, MD.

A

CHAPTER

Oral LP Oral LP can appear in at least seven forms, which occur separately or simultaneously: atrophic, bullous, erosive, papular, pigmented, plaquelike, and reticular. The most common and characteristic form of oral LP is the reticular pattern (Fig. 11.16A). It is characterized by slightly raised, whitish linear lines in a lace-like pattern or in rings with short radiating spines. This form is usually asymptomatic and the most common site of involvement is the buccal mucosa; lesions are often bilateral and symmetric. Gingival involvement is common, and oral LP affecting the gingivae exclusively is seen in ~10% of cases. It typically presents as chronic desquamative gingivitis (see Fig. 72.7). Gingivitis also occurs as a component of the “vulvovaginal–gingival syndrome” (see below). Atrophic, erosive, and bullous lesions are associated with symptoms ranging from mild discomfort to severe pain (Fig. 11.16B). There is a higher incidence of plaque-like lesions among tobacco smokers. For unknown reasons, oral LP is very uncommon in young patients, and in some studies, women have been affected about twice as often as men. Patients with oral LP should be questioned about symptoms related to esophageal involvement26 and examined for other mucosal lesions, particularly genital lesions, and vice versa, because ~70% of patients with mucosal vulvovaginal LP have clinical signs of oral LP. Esophageal LP has been increasingly recognized. It tends to be chronic and is associated with the development of dysphagia, strictures, stenosis, and even SCC. Reportedly, the erosive or ulcerative type of oral LP is less frequently associated with cutaneous LP than are all other types of oral LP. Such mucous membrane lesions are more therapy-resistant and less likely

B

11 Lichen Planus and Lichenoid Dermatoses

untreated (Fig. 11.15C). Nonspecific changes in the nail bed include yellow discoloration, onycholysis, and subungual hyperkeratosis. In some patients, twenty-nail dystrophy may represent a variant of LP. Nail LP presenting as twenty-nail dystrophy is much more common in children than in adults, although other forms of nail involvement are extremely rare in children.

C

Fig. 11.15 Nail lichen planus. A Thinning of the nail plate with lateral loss. B Longitudinal fissuring of shortened nail plates. C Violaceous discoloration of the periungual area with pterygium formation.

A

B

Fig. 11.16 Oral lichen planus. A White lacy pattern and an erosion on the buccal mucosa, the most common location for the reticular form. Note the ring configuration with short radiating spines. B Erosions on the lateral aspect of the tongue in addition to lacy white plaques and scarring. B, Courtesy, Louis A Fragola, Jr, MD.

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3

to spontaneously remit than cutaneous lesions. Malignant transformation of longstanding, non-healing oral LP has been reported, but it must be distinguished from pseudoepitheliomatous hyperplasia. The WHO has defined oral LP as a “premalignant condition” because of this risk. Several studies have reported a relationship between oral LP and chronic liver disease, particularly that due to HCV infection (see Pathogenesis)4,5. In the HCV-positive oral LP group, oral lesions were more frequently located on the tongue, labial mucosa, and gingivae27.

FEATURES FOR DISTINGUISHING LICHENOID DRUG ERUPTION FROM LICHEN PLANUS

Feature

Vulvovaginal LP LP of the vulva can present with several clinical variants, but the most common appears to be erosive disease28. Vaginal involvement occurs in up to 70% of women with erosive vulvar LP, and because there is often oral mucosal involvement as well, the term “vulvovaginal–gingival syndrome” has been introduced. The differential diagnosis of vulvovaginal LP includes lichen sclerosus and blistering diseases (see Ch. 73). Since scarring may be a sequela of vulvovaginal LP, patients should be carefully monitored for the development of SCC, including after the resolution of active disease29.

Lichenoid drug eruption (drug-induced LP) Despite the significant overlap between LP and lichenoid drug eruption (Fig. 11.17), there are both clinical and histologic clues that favor one diagnosis over the other (Table 11.4)30.

Idiopathic lichen planus

Mean age

65 years

50 years

Location

More generalized (including the trunk) and symmetric; often spares the “classic” sites of LP

Wrists, flexor forearms, presacral area, lower legs, genitalia

Morphology

More eczematous, psoriasiform or pityriasis rosea-like

Shiny, flat-topped, polygonal, violaceous papules

Wickham striae

Uncommon

Present

Hyperpigmentation

Very common, sometimes persistent

Common

Photodistribution

Frequent*

Unusual

Mucous membranes

Usually spared

Often involved

Histology

Varying degree of eosinophilic and/or plasma cell infiltrates

Eosinophils and plasma cells uncommon

Deep perivascular infiltrate may be present (1 year) have not been reported. However, given the FDA warning regarding topical calcineurin inhibitors and a possible increased risk of cutaneous carcinomas plus the increased risk of developing SCC in the setting of erosive oral and vulvar LP, continued safety monitoring is recommended. In a recent small case series, topical rapamycin (sirolimus) resulted in a complete (4/6 patients) or partial (2/6 patients) remission by 3 months in individuals with refractory erosive oral LP. The proposed mechanism of action of rapamycin is an increase in the number of Treg

cells, leading to decreased activation of T cells and B cells. In an openlabel, randomized, controlled trial, topical calcipotriene (calcipotriol) and betamethasone valerate had equal efficacy.

Systemic therapies In severe, acute LP, systemic corticosteroids remain a commonly employed intervention. Although different dosage regimens have been proposed, the minimal effective daily dose of prednisone is usually 15 to 20 mg1; treatment is continued for 2–6 weeks and then gradually tapered over several weeks. Rebound and relapses may occur, but long-term maintenance therapy with systemic corticosteroids should be avoided. One study demonstrated that the median time to clearing was 18 weeks in the corticosteroid-treated group and 29 weeks in the placebo group35. Acitretin is the only systemic retinoid that has a relatively good level of evidence regarding its efficacy in the treatment of cutaneous LP. A therapeutic regimen consisting of acitretin 30 mg/day for 8 weeks resulted in significant improvement or remission in 64% of those in the treatment group, compared with 13% in the placebo group36. Retinoids tend to be used for recalcitrant LP, and therefore relapses may occur after discontinuation of the drug; as a result, long-term maintenance therapy may be required. In case reports, alitretinoin, up to 25 mg/day for 4 weeks, was reported to clear oral, esophageal and cutaneous LP. Long-term (3 to 6 months) administration of griseofulvin was reported to result in a complete response in 86% of patients with LP1; however, the methods used in this study were not described in complete detail, so definitive conclusions cannot be made. In particular, oral erosive lesions have been reported to respond favorably to this drug. As a result, griseofulvin is often tried in such patients. A complete response or significant improvement (79%) of generalized LP (mean duration of disease, 3.5 months) was observed with metronidazole, 500 mg twice daily for 20 to 60 days37. More recently, in a retrospective study, hydroxychloroquine (200 mg twice daily) was shown to improve both lichen planopilaris and frontal fibrosing alopecia38; the latter is also treated with oral 5-α reductase inhibitors. Oral sulfasalazine administered in increasing doses from 1.5 to 3 g/day for at least 4 weeks was reported to be effective for cutaneous LP but not for mucosal LP. More recently, a randomized, double-blind, placebo-controlled trial utilizing a maximum of 2.5 g/day of sulfasalazine observed cutaneous improvement (>50%) in 82.6% vs 9.6% of patients at six weeks39. Based upon a case series, weekly low-dose methotrexate was noted to improve oral LP40. Efficacy of methotrexate for generalized LP has also been described. A complete response was achieved in 10 of 11 patients within 1 month and the medication was well tolerated without adverse effects. Based on a small case series, oral cyclosporine was reported as useful in inducing a remission in severe cases of LP resistant to systemic retinoids and corticosteroids41. Complete responses were observed with doses of cyclosporine ranging from 1 to 6 mg/ kg/day. The majority of patients did experience a relapse during follow-up periods of several months, but a rebound in disease activity can occur upon discontinuation of cyclosporine. Similar results were described in lichen planopilaris; alleviation of symptoms, resolution of clinical activity, and halting the progression of hair loss was achieved within 3 to 5 months42. However, long-term use of cyclosporine can be associated with renal toxicity, hypertension, and an increased risk of developing cutaneous SCCs (see Ch. 130). Mycophenolate mofetil, an immunosuppressive agent which specifically and reversibly inhibits the proliferation of activated T cells, was reported to be effective in the management of disseminated, erosive, hypertrophic and bullous variants of LP as well as lichen planopilaris43. It may be preferable to other immunosuppressive drugs such as cyclosporine because of its safer side-effect profile. Thalidomide has also been reported to be an effective therapy. TNF-α inhibitors (see Ch. 128) have been used in scattered patients with severe recalcitrant LP. Paradoxically, TNF-α inhibitors can induce LP-like eruptions (see above), usually within two months of initial administration44. However, resolution was observed in a few patients despite continued use of the drug. An open-label pilot study of apremilast, a novel oral phosphodiesterase IV inhibitor, in 10 patients with moderate to severe LP demonstrated statistically significant clinical improvement in all of the

Phototherapy In patients with resistant longstanding LP, significant improvement has been observed after bath or systemic PUVA. However, the risk of promoting carcinogenesis, especially in patients with skin types I and II, has to be balanced against the benefits. The usefulness of PUVA prompted evaluation of extracorporeal photopheresis (ECP) for recalcitrant LP. One case series demonstrated that erosive oral LP cleared in all seven patients after an average of 24 sessions of ECP (two consecutive days per month) and follow-up at 24 months revealed no recurrences46. The use of narrowband UVB for recalcitrant LP has also been reported. In an open prospective trial in 10 patients with recalcitrant LP, complete clearance occurred after 30 exposures (mean cumulative dose, 17.7 J/cm2) in five patients, while partial responses were observed in the remainder. The excimer laser (308 nm) was used to treat oral LP unresponsive to conventional therapies and was reported to produce excellent results47. Remission times ranged from 2 to 17 months. Of note, the only poor responder in the study had chronic active HCV infection.

LICHEN STRIATUS Key features ■ An asymptomatic, linear dermatosis that primarily affects children ■ The primary lesion is a small, flat-topped papule that ranges in color from pink to skin-colored to tan (hypopigmented) ■ Multiple lesions appear over the course of days to weeks along the lines of Blaschko and usually on an extremity ■ Spontaneously resolves over months to a few years ■ Digital involvement may result in nail dystrophy

Synonyms: ■ Linear lichenoid dermatosis ■ Blaschko linear acquired inflammatory skin eruption (BLAISE)

Introduction Lichen striatus is an asymptomatic, uncommon, self-limited, linear dermatosis of unknown etiology that generally affects children. The diagnosis is usually made clinically based upon the appearance of the primary lesions and the distinctive developmental pattern. Its distribution along the lines of Blaschko plus the age of the patient usually narrows the differential diagnosis rather quickly. Occasionally, there is overlap with linear LP and “blaschkitis” (see Ch. 62).

during spring and summer). However, to date, a viral association has not been proven via serologic testing or cultures. Concurrent familial occurrence of lichen striatus in a mother and child has been touted as evidence for a viral trigger. In theory, during early fetal development, aberrant clone(s) of epidermal cells produced by somatic mutation migrate out along the lines of Blaschko. Exposure to an infectious agent (e.g. virus, BCG vaccine) or other precipitant could then break previous tolerance to the aberrant clone by inducing a novel membrane antigen. The presence of CD8+ T cells scattered or in clusters around necrotic keratinocytes supports a cell-mediated immunologic reaction by which cytotoxic T cells would attack and eliminate the mutated or virally modified keratinocyte clones. A similar mechanism has been proposed for linear LP, and a post-transplant loss of tolerance could explain linear GVHD. Lichen striatus may represent a manifestation of an atopic diathesis with the abnormal immune responses usually associated with atopy being a predisposing factor. The timing and relative infrequency of lichen striatus suggests that an infectious agent acts as a trigger in genetically predisposed individuals. Lastly, there are scattered reports of lichen striatus occurring at sites of injury (e.g. the periphery of a burn scar49) rather than along the lines of Blaschko, but this could also be explained by a break in tolerance.

Lichen striatus is typically asymptomatic, but intense pruritus can occasionally occur. The eruption consists of a continuous or interrupted band composed of discrete or clustered pink, skin-colored or tan (hypopigmented) papules that are flat-topped, smooth or scaly, and range in size from 2 to 4 mm. Infrequently, vesicles may be present. Often, there is a single, unilateral streak on an extremity along the lines of Blaschko (Fig. 11.19); occasionally, there is a bilateral dis­ tribution pattern and/or multiple parallel bands. It is uncommon for lichen striatus to involve the trunk or head and neck region. There are reports of the eruption spreading distally from the trunk down an extremity, as well as observations of proximal extension along an extremity50. Although lichen striatus does not usually recur, relapses may occasionally occur, either in the same site or on the same side of the body48. The eruption usually appears suddenly, develops fully over days to weeks, and after several months to a year or more, undergoes spontaneous resolution. Postinflammatory hypopigmentation may be seen, particularly in those with more darkly pigmented skin. In the latter individuals, the eruption is often first noticed as linear hypopigmentation. When lesions involve the nail apparatus, onycholysis, splitting, fraying and total nail loss may result.

Pathology

Lichen striatus is seen primarily in children between the ages of 4 months and 15 years, although the disorder occasionally occurs in adults. The median age of onset is 2 to 3 years and the vast majority of cases occur in preschool-age children48. The reported female : male ratio has varied from 1.6 : 149 to 2 : 148.

Pathogenesis

Differential Diagnosis

Although the distribution of lichen striatus along the lines of Blaschko points to somatic mosaicism (see Ch. 62), neither the gene(s) involved nor the triggering factors are known. Environmental agents, particularly viruses, have been implicated, given the predominance of the disorder in young children and its seasonal variation (it appears more commonly

Although the differential diagnosis includes other inflammatory diseases that can assume a linear pattern, such as linear porokeratosis, linear psoriasis, inflammatory linear verrucous epidermal nevus, linear lichen sclerosus and linear Darier disease, the primary differential diagnosis is linear LP, blaschkitis and linear GVHD. The latter occurs

In 1898, Balzer and Mercier first described a peculiar linear papular eruption that they termed “lichenoid trophoneurosis”. Forty years later, Senear and Caro proposed the name “lichen striatus”. Ever since the condition was first described, the pathogenesis of its linearity has been the subject of debate.

Epidemiology

11

Clinical Features

The histologic features of lichen striatus are variable and depend upon the age of the lesion at the time the biopsy is performed. In addition, different sites within the same streak can have different findings. In general, there is a lichenoid tissue reaction in addition to varying degrees of involvement of the hair follicles and sweat glands and ducts (Fig. 11.20). Even though the lichenoid inflammation that may be present around hair follicles is indistinguishable from that seen in lichen planopilaris, sweat gland and hair follicle involvement can still be a helpful diagnostic feature of lichen striatus49. Exocytosis, parakeratosis, dyskeratosis, and focal or diffuse vacuolar degeneration can be seen in the epidermis overlying the lichenoid infiltrate. Occasionally, older lesions may have features similar to LP. By immunohistochemistry, CD3+ T-cell infiltrates were noted in which CD8+ T cells surrounded necrotic keratinocytes and infiltrated vesicles filled with Langerhans cells. Depending upon the age of the lesions, Langerhans cells were either decreased (earlier lesions) or increased (later phase due to an influx of precursor cells).

History

CHAPTER

Lichen Planus and Lichenoid Dermatoses

patients after 12 weeks45. In a patient with steroid-refractory oral LP, improvement was observed after 2 cycles of IVIg (0.4 g/kg/day for 5 days), in combination with oral prednisolone (20 mg/day).

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3

Papulosquamous and Eczematous Dermatoses

Fig. 11.19 Lichen striatus. A Linear streak on the leg that follows the lines of Blaschko. It is composed of numerous small, tan (hypopigmented), flat-topped papules. B Three linear streaks on the lower extremity composed of multiple pink papules, some of which are flat-topped with scale. The primary differential diagnosis would be blaschkitis. A, Courtesy, Antonio Torrello, MD.

A

Fig. 11.20 Lichen striatus – histopathologic features. In addition to hyperkeratosis with focal parakeratosis, both a lichenoid and a perivascular and periadnexal lymphocytic infiltrate extending into the deeper dermis is seen. Courtesy, Lorenzo Cerroni, MD.

LICHEN NITIDUS Key features ■ The eruption consists of multiple, tiny, discrete, shiny papules, often in clusters ■ Favored sites of involvement include the flexor aspects of the upper extremities, the genitalia, and the anterior trunk ■ Linear arrays of papules occur secondary to the Koebner phenomenon ■ The histologic correlate of the papule is a well-circumscribed infiltrate composed of lymphocytes and epithelioid cells confined to the width of two to three dermal papillae B

202

Introduction

in a specific clinical setting, while blaschkitis favors the trunk, is usually seen in adults, often consists of multiple streaks, recurs, and can have features of dermatitis. Although linear LP and lichen striatus can occasionally be indistinguishable histologically, the primary lesions usually differ in size and color, and hypopigmentation is a frequent sequela of lichen striatus, while, in general, hyperpigmentation appears in the wake of LP. In lichen nitidus, linear lesions reflect previous traumatic injury to the skin.

Lichen nitidus is an uncommon chronic eruption consisting of multiple, tiny, discrete, skin-colored papules that are often arranged in larger clusters. The papules have a distinctive histology with a dense, wellcircumscribed, lymphohistiocytic infiltrate closely apposed to the epidermis. There has been considerable debate, however, as to whether lichen nitidus represents a distinct and separate entity or should be regarded as an unusual variant of LP; their coexistence has certainly been reported and progression from lichen nitidus to LP has also been observed. It is generally accepted that lichen nitidus has no relationship to any systemic illness. Only a few authors believe that it may be a cutaneous manifestation of Crohn disease51.

Treatment

History

Treatment of lichen striatus is usually not needed because it is selflimited, usually resolving within 1 to 2 years. Topical corticosteroids under occlusion can be used to hasten spontaneous resolution. In scattered case reports, topical calcineurin inhibitors have also been reported to be effective, including for the nail dystrophy. Obviously, with any purported therapy, the natural history of lichen striatus must be kept in mind.

Epidemiology

In 1901, Pinkus first described a peculiar papular eruption he termed “lichen nitidus” and suggested that it was a distinct entity histologically.

Reliable epidemiologic data are difficult to accumulate because of the relative rarity of lichen nitidus. In a US study of 43 patients, primarily Caucasians and African-Americans, the disorder was not found to be

COMPARISON OF CLINICAL AND HISTOLOGIC FEATURES OF LICHEN NITIDUS VERSUS LICHEN PLANUS

Lichen nitidus

Lichen planus

Pinhead

Pinhead to larger plaques

Clinical Size Color

Skin-colored

Violaceous

Number

Multiple to numerous

Multiple

Distribution

Upper extremities (flexor aspects), genitalia, chest, abdomen

Wrists, flexor forearms, presacral area, dorsal hands, shins, genitalia

Oral involvement

Rare*

Common (>50%)

Nail involvement

milk, peanuts/tree nuts, (shell)fish, soy, wheat - Detection of allergen-specific IgE (via blood and skin prick tests) does not necessarily mean that allergy is triggering the patient’s AD •

*Stroking the skin leads to a white streak that reflects excessive vasoconstriction. Table 12.1 Diagnostic features and triggers of atopic dermatitis (AD). URI, upper respiratory infection. Adapted from the American Academy of Dermatology  

formerly known as intrinsic AD. However, IgE-associated/allergic “true” AD and non-IgE-associated/non-allergic dermatitis have substantial overlap and cannot be considered as two separate diseases; for example, the latter often represents an early transitional form of IgE-associated AD.

Atopic Dermatitis

and Sulzberger proposed the name “atopic dermatitis”. The list of characteristic features proposed by Hanifin and Rajka5 in 1980 helped to unify the clinical concept of AD. In 1994, Williams and co-workers6 simplified Hanifin and Rajka’s criteria to establish the UK Working Party’s Diagnostic Criteria for AD, which were validated for the purpose of clinical studies; these criteria were modified slightly by Williams in 20052. In 2003, a consensus conference spearheaded by the American Academy of Dermatology suggested revised Hanifin and Rajka criteria that are more streamlined and applicable to the full range of patient ages (Table 12.1). According to the consensus nomenclature by the World Allergy Organization (WAO)7, the term “atopy” is tightly linked to the presence of allergen-specific IgE antibodies in the serum, as documented by positive fluorescence enzyme immunoassays (previously radioallergosorbent [RAST] tests) or skin prick tests. Thus, an IgE-associated or allergic form of dermatitis, formerly known as extrinsic AD, corresponds to AD in the strict sense. The remaining 20–30% of patients with the clinical phenotype of AD who have no evidence of IgE-sensitization are categorized as having a non-IgE-associated or non-allergic form of dermatitis,



Consensus Conference on Pediatric Atopic Dermatitis (Eichenfield LF, Hanifin JM, Luger TA, et al. J Am Acad Dermatol. 2004;49:1088–95).

Genetic factors account for ~90% of susceptibility to early-onset AD9, with a significantly higher concordance rate in monozygotic twins (77%) compared to dizygotic twins (15%)10. Although the entities in the atopic triad cluster together in families, a parental history of AD is a stronger risk factor for the development of AD than either asthma or allergic rhinitis, supporting the existence of genes specific to AD susceptibility11. Genes that encode proteins important to the epidermal barrier and immunologic functions have been implicated in AD pathogenesis (Table 12.2). AD is a complex genetic disease, and both gene– gene and gene–environment interactions have important roles4.

Epidermal Barrier Dysfunction A defective epidermal permeability barrier represents a consistent feature of AD and is evident in the nonlesional as well as lesional skin of affected individuals12. A higher level of transepidermal water loss (TEWL), an indicator of barrier dysfunction, on day 2 of life predicts an increased risk of AD at 1 year of age13. In addition, the level of TEWL in the nonlesional skin of children with AD correlates with disease severity14,15. Epidermal barrier dysfunction permits an easier entry for irritants, allergens and microbes, which trigger immune responses that include the release of proinflammatory cytokines16. In infants, greater TEWL is associated with an increased likelihood of epicutaneous sensitization to aeroallergens, which could potentially play a role in the development of asthma and allergic rhinoconjunctivitis4,17,18. Factors that contribute to the impaired cutaneous barrier in AD are discussed below.

Filaggrin and other structural proteins Filaggrin is a keratin filament-aggregating protein that serves as a major structural component of the stratum corneum. Loss-of-function FLG

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ATOPIC DERMATITIS: EPIDERMAL BARRIER DYSFUNCTION, IMMUNE DYSREGULATION, AND ENVIRONMENTAL INFLUENCES

Environmental factors • ↑ Penetration across skin barrier • Damage to epidermal barrier (e.g. scratching, proteases) • Activation of immune responses

Impaired stratum corneum (SC) barrier function • ↓ Filaggrin and other genetic barrier protein deficiencies → abnormal corneocyte formation and impaired acid mantle (surface pH) • ↑ Proteases (KLK5, KLK7) → corneocyte dysadhesion • Abnormal lipids: impaired lamellar body and lipid processing → ↑ SC permeability

Altered skin microbiome ↑ S. aureus

Allergens

Irritants

↑ TEWL Keratinocyte-derived pro-Th2 and pro-innate lymphoid cell (ILC) cytokines TSLP, IL-1, IL-25, IL-33

Impairment of epidermal barrier function

Th2

Immune dysregulation

Adaptive

Innate and adaptive responses to environmental stimuli

Innate

Acute Th2 responses: IL-4, IL-5, IL-13, IL-31 IgE

Th1

Th17

Chronic Th1, Th17, Th22 responses

Th22 Includes innate lymphoid cells (ILC)

Fig. 12.2 Atopic dermatitis results from defects in epidermal barrier function, immune dysregulation, and environmental influences. SC, stratum corneum; KLK, kallikrein; TEWL, transepidermal water loss; TSLP, thymic stromal lymphopoietin. Courtesy, Harvey Lui, MD.  

210

mutations represent the strongest known genetic risk factor for AD and are also responsible for ichthyosis vulgaris19–22 (see Ch. 57), with carrier frequencies of up to 10% in European and ~3% in East Asian populations23–25. Approximately 20–50% of European and Asian children with moderate-to-severe AD have at least one FLG mutation; the penetrance of AD is ~40% for one and ~90% for two mutant alleles20. This implicates epidermal barrier dysfunction in the initiation of AD, with subsequent development of Th2-biased immune responses24. Of note, filaggrin expression is also affected by intragenic copy number variation and reduced by increased local pH, protease activity, and Th2 cytokine levels22,26. FLG mutations are associated with early-onset AD, greater disease severity, and persistence into adulthood as well as enhanced epicutan­ eous sensitization and an increased risk of irritant contact dermatitis, hand eczema, herpes simplex virus (HSV) infections, and food allergy20,25,27. FLG mutations have also been linked to an increased risk for the development of asthma and greater asthma severity; however, these effects are only seen in patients with pre-existing AD28. Since filaggrin is not found in the gastrointestinal or bronchial mucosa, the association of FLG mutations with food allergy and asthma strongly suggests that epicutaneous sensitization and/or cutaneous inflammation can contribute to the development of systemic atopic disease29.

Filaggrin breakdown products such as histidine contribute to epidermal hydration, acid mantle formation, lipid processing, and barrier function20,27. Gene expression profiling and immunohistochemical analysis of lesional and nonlesional skin from AD patients have shown broad defects in terminal differentiation, with down-regulation of other epidermal barrier proteins such as loricrin, corneodesmosin, involucrin, small prolene rich proteins 3/4 (SPRR3/4), claudin-1, and late cornified envelope protein 2B30–34.

Stratum corneum lipids The composition, organization, and biochemical processing of stratum corneum lipids are critical determinants of epidermal permeability barrier function (see Ch. 124). In AD, a filaggrin-deficient cytoskeletal scaffold contributes to abnormal loading and secretion of lamellar bodies, with subsequent defects in post-secretory lipid organization and processing35–37. Disruption of the skin’s acidic mantle leads to reduced activity of lipid-processing enzymes such as β-glucoscerebrosidase and acid sphingomyelinase38,39. Th2 cytokines also negatively affect generation of stratum corneum lipid components37,40.

Proteases and protease inhibitors Lesional AD skin demonstrates elevated levels of endogenous serine proteases, e.g. kallikrein 5 and 7 (KLK5/7), due to an imbalance in the

Candidate gene(s)

Defective protein(s)

Genes encoding epidermal proteins FLG

Filaggrin (loss-of-function variants; see text)

FLG2

Filaggrin family member 2

SPINK5

Serine protease inhibitor LETKI

KLK5/SCTE, KLK7/SCCE

Kallikrein-related peptidases 5 & 7/stratum corneum tryptic & chymotryptic enzymes

CLDN1

Claudin-1

SPRR3

Small proline-rich protein 3

TMEM79

Transmembrane protein 79 (mattrin)

Genes encoding immunologic proteins FCER1A

Fc fragment of high-affinity IgE receptor I, α chain

TLR2, 4, 6, 9

Toll-like receptor-2, -4, -6, and -9

IRF2

Interferon regulatory factor 2

IL4, 5, 12B, 13, 18, 31

Interleukin-4, -5, -12B, -13, -18, and -31

IL4RA, IL5RA, IL13RA

Interleukin-4, -5, and -13 receptors, α subunits

GM-CSF

Granulocyte–macrophage colony-stimulating factor

CD14

Monocyte differentiation antigen CD14

DEFB1

β-defensin 1

GSTP1

Glutathione S-transferase P1

CMA1

Mast cell chymase

CCL5/RANTES

Chemokine (C-C motif) ligand 5/RANTES

TSLP

Thymic stromal lymphopoietin

MIF

Macrophage migration inhibitory factor

VDR

Vitamin D receptor

CYP27A1, CYP2R1

Cytochrome p450 family members 27A1 and 2R1

Table 12.2 Selected candidate genes for atopic dermatitis. LETKI, lymphoepithelial Kazal-type-related inhibitor; RANTES, regulated on activation, normally T-cell expressed and secreted; SPINK5, serine peptidase inhibitor Kazal type 5.  

activities of these proteolytic enzymes and protease inhibitors such as the lymphoepithelial Kazal-type trypsin inhibitor (LEKTI) encoded by SPINK5. Biallelic loss-of-function SPINK5 mutations underlies Netherton syndrome, which features profoundly compromised barrier function and atopy (see Ch. 57), while SPINK5 polymorphisms have been linked to increased risk of AD in some populations41. Other factors that enhance proteolysis include increased skin surface pH and exogenous proteases from allergens (e.g. house dust mites, pollens), Staphylococcus aureus, and Malassezia42. LEKTI deficiency results in excessive degradation of the corneodesmosomal component desmoglein-1 (Dsg1), causing abnormal stratum corneum detachment and thereby disrupting the epidermal barrier43. The S. aureus extracellular V8 protease, which has a sequence similar to those of S. aureus exfoliative toxins, is also thought to degrade Dsg144. In addition, unrestrained protease activity leads to degradation of lipid-processing enzymes and antimicrobial peptides as well as activation of proinflammatory cytokines42,45.

Immune Dysregulation The innate and adaptive immune systems play dynamic interrelated roles in the pathogenesis of AD. Acute AD lesions have a predominance of Th2 cytokines, but there is subsequent evolution to a chronic phase characterized by Th1 and Th22 cytokine profiles, as well as variable levels of Th17 cytokines in both acute and chronic AD46. The acute phase features IL-4, IL-5, and IL-13; activation of eosinophils and mast cells; and production of allergen-specific IgE47,48. Keratinocyte-derived cytokines including IL-1, thymic stromal lymphopoietin (TSLP), IL-25

Thymic stromal lymphopoietin (TSLP) TSLP is an IL-7-like cytokine that is known as the “master-switch of allergic inflammation” due to its central role in evoking a Th2 response via dendritic cell activation45,52–54. Exposure to allergens, viral infections, trauma, and other cytokines (e.g. IL-1β, TNF) can trigger TSLP production by keratinocytes, fibroblasts, and mast cells55. TSLP is highly expressed in acute and chronic lesions of AD, but not in the nonlesional skin of patients with AD or in unaffected individuals56.

CHAPTER

12 Atopic Dermatitis

SELECTED CANDIDATE GENES FOR ATOPIC DERMATITIS

(IL-17E), and IL-33 promote a Th2 immune response. Th2 cytokines inhibit expression of major terminal differentiation proteins such as loricrin, filaggrin, and involucrin as well as β-defensin-2/3 antimicrobial peptides31,49–51.

IL-4 and IL-13 IL-4 has a key role in driving Th2 cell differentiation, IgE production, and eosinophil recruitment57,58. Transgenic mice overexpressing IL-4 in their epidermis develop atopic dermatitis-like lesions, pruritus, an altered microbiome, and elevated IgE levels59. The heterodimeric receptors for IL-4 and IL-13 both contain the IL-4 receptor α subunit (IL4Rα; see Fig. 128.9C) and activate signal transducer and activator of transcription 6 (STAT6), which promotes the differentiation of naive T cells into Th2 effector cells60. Although IL-4 and IL-13 share 25% sequence homology and effector functions, studies in human subjects and human keratinocyte cell lines support an independent role for IL-13 in AD pathogenesis. Anti-IL-4/13 therapy with dupilumab, a monoclonal antibody that targets the IL-4Rα, is FDA-approved for the treatment of AD61 (see Ch. 128 and below).

Other cytokines Th17 cells are important in the regulation of innate immunity, in particular neutrophil recruitment, and have also been implicated in allergic disorders62. Th17 cells are found in acute as well as chronic AD lesions63, and production of IL-17 and IL-19 is especially characteristic of new-onset pediatric AD64. IL-31 is a Th2 cytokine that is highly expressed in lesions of AD and other pruritic skin disorders such as prurigo nodularis65. Cutaneous exposure to staphylococcal superantigen rapidly induces IL-31 expression in atopic individuals, establishing a link between staphylococcal colonization of the skin and pruritus. The heterodimeric receptor for IL-31 is expressed by keratinocytes, eosinophils, activated macrophages, cutaneous C nerve fibers, and dorsal root ganglia (see Ch. 5)66,67. A randomized, placebo-controlled study showed that nemolizumab, a humanized monoclonal antibody against the IL-31 receptor A subunit, can significantly reduce pruritus in patients with moderate to severe AD68. IL-33, a member of the IL-1 cytokine family, protects against helminth infection by promoting a Th2-type immune response. IL-33 expression is increased in AD lesions compared to the skin of unaffected individuals69.

Innate lymphoid cells The innate lymphoid cell (ILC) family includes natural killer cells and three groups of non-cytotoxic ILCs that orchestrate immunity, inflammation, and homeostasis in multiple tissues70. The group 2 ILC (ILC2) population is expanded in AD lesions and stimulated by TSLP, IL-25 (IL-17E), and IL-3371–73. ILC2s interact with other immune cells (e.g. mast cells, eosinophils) in the skin to promote Th2-type inflammation in a T-cell independent manner.

The Cutaneous Microbiome The cutaneous microbiome represents a complex and highly diverse community of pathogenic and commensal bacteria, fungi, and viruses that play a critical role in epidermal homeostasis. More than 90% of patients with AD have skin colonized with S. aureus, compared to about 5% of unaffected individuals, presumably reflecting the disrupted acid mantle, decreased antimicrobial peptides (e.g. cathelicidins, defensins), and altered cytokine milieu of AD skin74. During AD flares, bacterial diversity decreases and the proportion of the microbiome accounted for by Staphylococcus spp. increases from ~35% to ~90%75. Superantigens can promote the development of a Th2 immune response, and exotoxins with superantigenic properties are produced by

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3



Infantile atopic dermatitis

Most common sites Other frequently involved sites Childhood and adolescent atopic dermatitis Head and neck dermatitis: primarily of face and neck after puberty; may be triggered by Malassezia overgrowth

Ear eczema: erythema, scaling and fissuring under earlobe and/or in retroauricular region, ± bacterial superinfection

*

Eyelid eczema : often has prominent lichenification

Nipple eczema: exacerbated by rubbing of clothing (e.g. in joggers/athletes)

Dryness (chapping) of vermilion lips, ± peeling, fissuring, angular cheilitis

Frictional lichenoid eruption: multiple, small, flattopped pink to skincolored papules on elbows > knees, classically in atopic boys in spring/summer

Erythema and scaling surrounding vermilion lips, often due to irritation from licking (lip licker’s eczema) Dyshidrotic eczema: deep-seated vesicles favoring sides of fingers and palms

Prurigo-like lesions: firm, dome-shaped papulonodules with central scale-crust, favoring extensor extremities

Juvenile plantar dermatosis: glazed erythema, scaling and fissuring of plantar forefeet

*

Atopic hand eczema : often superimposed irritant contact dermatitis Most common sites Other sites of predilection Specific variants

Nummular lesions†: coin-shaped eczematous plaques, often with oozing/crusting, favoring extremities

up to 65% of the S. aureus strains that colonize AD patients76. In addition, the S. aureus δ-toxin stimulates mast cell degranulation and Th2 inflammation77. Filaggrin deficiency also increases the susceptibility of keratinocytes to S. aureus α-toxin-induced cytotoxicity78. Alterations in the skin microbiome of AD patients related to the use of cleansers and topical immunomodulatory or antimicrobial agents may have potential effects on cutaneous inflammation and barrier function. In addition, topical administration of coagulase negative Staphylococcus strains with antimicrobial activity has been shown to markedly reduce S. aureus colonization in AD patients78a, providing the basis for bacteriotherapy as a potential AD treatment.

CLINICAL FEATURES Disease Course 212

Fig. 12.3 Distribution patterns of atopic dermatitis (AD) and regional variants. *May be the only manifestation of AD in adults. †Not to be confused with nummular eczema occurring outside the setting of AD.

DISTRIBUTION PATTERNS OF ATOPIC DERMATITIS AND REGIONAL VARIANTS

AD has a broad clinical spectrum that varies depending upon the age of the patient. It is divided into infantile, childhood, and adolescent/

adult stages (Fig. 12.3). In each stage, patients may develop acute, subacute, and chronic eczematous lesions, all of which are intensely pruritic and often excoriated. Acute lesions predominate in infantile AD and are characterized by edematous, erythematous papules and plaques that may exhibit vesiculation, oozing, and serous crusting. Subacute eczematous lesions display erythema, scaling, and variable crusting. Chronic lesions, which typify adolescent/adult AD, present as thickened plaques with lichenification as well as scale; prurigo nodulelike lesions can also develop (see below). Perifollicular accentuation and small, flat-topped papules (papular eczema) are particularly common in patients with African or Asian heritage. In any stage of AD, a generalized exfoliative erythroderma may develop in the most severely affected patients (see Ch. 10). All types of AD lesions can leave postinflammatory hyper-, hypo-, or occasionally depigmentation upon resolution (Fig. 12.4). Infantile AD (age 90% of patients with AD79. Young infants may attempt to relieve itch through rubbing movements against their bedding, whereas older infants are better able to directly scratch affected areas.

In childhood AD (age 2 to 12 years), the lesions tend to be less exudative and often become lichenified. The classic sites of predilection are the antecubital and popliteal fossae (flexural eczema) (Fig. 12.7). Other common locations include the wrists, hands, ankles, feet, neck, and eyelids, although any area can be involved (Fig. 12.8). Xerosis typically becomes pronounced and widespread. Adult/adolescent AD (age >12 years) also features subacute to chronic, lichenified lesions, and involvement of the flexural folds typically continues (Fig. 12.9). However, the clinical picture may also change. Adults with AD frequently present with chronic hand dermatitis that has both endogenous and exogenous components (Fig. 12.10), while others have primarily facial dermatitis (Fig. 12.11), often with severe eyelid involvement (see below). Patients who have suffered from continuous AD since childhood are more likely to have extensive disease that is resistant to treatment. Such individuals may also have severe excoriations and chronic papular skin lesions because of habitual scratching and rubbing (Fig. 12.12A). Senile AD (age >60 years) is characterized by marked xerosis. Most of these patients do not have the lichenified flexural lesions typical of AD in children and younger adults. AD has a profound adverse impact on the quality of life of affected children and adults, with intense pruritus and stigmatization often

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Fig. 12.8 Extensive atopic dermatitis in a child. Excoriations, crusting, and lichenification are evident.

Papulosquamous and Eczematous Dermatoses



resulting in sleep disturbances, psychological distress, social isolation, disrupted family dynamics, and impaired functioning at school or work. Children with AD experience greater impairment in their quality of life than those with diabetes mellitus or epilepsy80.

Regional Variants of Atopic Dermatitis Several regional variants of AD can occur in isolation or together with the classic age-related patterns of involvement described above (see Fig. 12.3). The face is a frequent location for site-specific manifestations. Eczema of the lips, referred to as cheilitis sicca, is common in AD patients, especially during the winter (Fig. 12.13A). It is characterized by dryness (“chapping”) of the vermilion lips, sometimes with peeling and fissuring, and may be associated with angular cheilitis. Patients try to moisten their lips by licking, which in turn may irritate the skin around the mouth, resulting in so-called lip-licker’s eczema. Another common feature of childhood AD is ear eczema, presenting as erythema, scaling, and fissures under the earlobe and in the retroauricular area, sometimes in association with bacterial superinfection. Eyelid eczema can represent the only manifestation of AD, especially in adults. In contrast to eyelid eczema due to other causes, it is characterized by lichenification of the periorbital skin. “Head and neck dermatitis” represents a variant of AD that typically occurs after puberty and primarily involves the face, scalp, and

B

A

C

Fig. 12.9 Chronic atopic dermatitis. A Lichenification, scale, and punctate excoriations in the antecubital fossae. B Coalescing papules and lichenification on the ankle due to chronic scratching and rubbing. C Thick eczematous plaques with excoriation on the dorsal hand and wrist. A, C, Courtesy, Julie V Schaffer, MD; B, Courtesy, Antonio  

Torrelo, MD.

Fig. 12.10 Atopic dermatitis with severe chronic hand involvement. Note the marked lichenification.  

Courtesy, Julie V Schaffer, MD.

214

Fig. 12.11 Severe atopic dermatitis with facial involvement in an adult.  

CHAPTER

12

Fig. 12.12 Atopic dermatitis variants. A Chronic papular lesions resulting from habitual rubbing and scratching in the setting of longstanding disease. B Prurigo lesions presenting as firm, dome-shaped papules and nodules with central hemorrhagic crust. C Nummular plaques with oozing and crusting on the legs. A,

Atopic Dermatitis



Courtesy, Thomas Bieber, MD, and Caroline Bussmann, MD; B, C, Courtesy, Antonio Torrelo, MD.

A

A

B

Fig. 12.13 Regional variants of atopic dermatitis. A Atopic cheilitis involving both the vermilion lip and surrounding skin (lip licker’s eczema). B Nipple eczema in an adolescent. Courtesy, Julie V Schaffer, MD.  

B

C

neck. When older children and teenagers present with this form of AD, it usually persists into adulthood. Malassezia yeasts, which are members of the skin microbiome in the head and neck area, may be an aggravating factor for this presentation81, and systemic antifungal treatment with itraconazole or fluconazole may be of benefit. Eczema variants also occur in acral sites. Juvenile plantar dermatosis presents with “glazed” erythema, scale, and fissuring on the balls of the feet and plantar aspect of the toes in children with AD (see Ch. 13). Atopic hand eczema (see Fig. 12.10) affects ~60% of adults with AD and may be the only manifestation of the condition. FLG mutations

are associated with increased likelihood of hand eczema in children and adults82, and frequent exposure to water and other irritants in household or occupational settings represents another risk factor. Atopic hand eczema typically involves the volar wrists and dorsum of the hands. The palms and sides of the fingers may develop the deep-seated vesicles of dyshidrotic eczema (see Ch. 13). The prurigo form of AD favors the extensor aspects of the extremities and is characterized by firm, dome-shaped papules and nodules with central scale-crust, similar to prurigo nodularis lesions in nonatopic patients (Fig. 12.12B). Nummular (discoid) lesions also tend to develop on the extremities in children and adults with AD, appearing as coin-shaped eczematous plaques, usually 1 to 3 cm in diameter and often with prominent oozing and crusting (Fig. 12.12C). They are similar in appearance to nummular dermatitis occurring outside the setting of atopy (see Ch. 13). Frictional lichenoid eruption has a predilection for atopic children and presents as multiple small, flat-topped, pink to skin-colored papules on the elbows and (less often) knees and dorsal hands. Lastly, chronic nipple eczema can develop in children and adults with AD (Fig. 12.13B).

Associated Features Pruritus Intense pruritus is a hallmark of AD. The itch is often worse in the evening and may be exacerbated by exogenous factors such as sweating or wool clothing. Rubbing and scratching in response to pruritus can initiate flares or exacerbate existing dermatitis, explaining why AD is known as the “itch that rashes”. Excoriations (linear or punctate) are frequently present, providing evidence of scratching (Fig. 12.14; see Figs 12.7–12.9). With repeated rubbing and scratching, the skin becomes

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3

Fig. 12.14 Associated features of atopic dermatitis. See Table 12.3. Inset of hand: Courtesy, Jean L Bolognia, MD.  

ASSOCIATED FEATURES OF ATOPIC DERMATITIS



Central facial pallor Dennie–Morgan folds (“atopic pleats”): lower lids Periorbital darkening: (“allergic shiners”): gray to violet–brown ± edema Keratosis pilaris: keratotic follicular papules with erythematous rim or (on cheeks) background of patchy erythema Excoriations: linear or punctate

Pityriasis alba: ill-defined hypopigmented macules ± fine scaling Anterior neck folds Postinflammatory hypo- or hyperpigmentation: at sites of previous eczematous lesions Follicular prominence: with “goose bump”-like appearance

Palmar and plantar hyperlinearity Xerosis: dry skin with fine scaling Ichthyosis vulgaris: fine whitish to polygonal brown scaling that favors the shins and spares the flexures

patches, usually 0.5 to 2 cm in diameter, with fine scaling; the lesions are typically located on the face, especially the cheeks (see Fig. 12.17), but occasionally appear on the shoulders and arms. Pityriasis alba is most obvious in individuals with darkly pigmented skin and/or following sun exposure. It is thought to result from a low-grade eczematous dermatitis that disrupts the transfer of melanosomes from melanocytes to keratinocytes. Similar hypopigmented lesions can appear upon resolution of more overtly inflamed, erythematous lesions of AD. The differential diagnosis of pityriasis alba also includes postinflammatory hypopigmentation secondary to other dermatoses such as seborrheic dermatitis or pityriasis lichenoides chronica. Pityriasis versicolor is typically more sharply demarcated, with small lesions that may coalesce centrally in involved areas, and vitiligo is also sharply demarcated and depigmented rather than hypopigmented. Hypopigmented mycosis fungoides may occasionally represent a diagnostic consideration if there is extrafacial involvement. Regular use of sunscreens and other forms of photoprotection may minimize the appearance of pityriasis alba.

Complications Fig. 12.15 Excoriations. Numerous punctate and a few linear excoriations in an area of papular eczema on the lower back. Courtesy, Antonio Torrelo, MD.  

thickened and leathery with exaggerated skin markings, referred to as lichenification (see Figs 12.9 and 12.10).

Atopic stigmata Physical findings other than dermatitis that are frequently observed in patients with AD are presented in Table 12.3 and Figs 12.15–12.17.

Pityriasis alba 216

Pityriasis alba frequently affects children and adolescents with AD. It is characterized by multiple ill-defined hypopigmented macules and

Infections Bacterial and viral infections represent the most common complications of AD. Considering that S. aureus colonizes the skin of the vast majority of patients with AD, it is not surprising that impetiginization, which can also be caused by Streptococcus pyogenes, occurs frequently (Fig. 12.18). Bacterial infections may exacerbate AD by stimulating the inflammatory cascade, e.g. via S. aureus exotoxins that act as superantigens (see above). Eczema herpeticum represents rapid dissemination of a herpes simplex viral infection over the eczematous skin of AD patients. It initially develops as an eruption of vesicles, but affected individuals more often present with numerous monomorphic, punched-out erosions with hemorrhagic crusting (Fig. 12.19). Eczema herpeticum is frequently widespread and may occur at any site, with a predilection

CHAPTER

Xerosis

Important feature that is present in most patients with AD Often most prominent on the lower legs; may be generalized • Dry skin with fine scale in areas without clinically apparent inflammation • Typically worse during the winter • Impaired epidermal barrier function from decreased water content in the stratum corneum leads to easier entry of irritants, which can promote pruritus and initiate an inflammatory response • •

Ichthyosis vulgaris



Autosomal semidominant disorder with incomplete penetrance caused by mutations in the filaggrin gene (FLG; see text and Ch. 57) • ~15% of patients with AD have moderate-to-severe ichthyosis vulgaris; conversely, >50% of patients with ichthyosis vulgaris have AD • Excessive fine, whitish to brown scaling that favors the lower legs (especially the shins) and spares the flexures

Keratosis pilaris



12 Atopic Dermatitis

ASSOCIATED FEATURES OF ATOPIC DERMATITIS (“ATOPIC STIGMATA”)

Common condition that affects >40% of patients with AD and ~75% of those with ichthyosis vulgaris Onset typically in childhood; may improve after puberty (especially facial involvement) • Affects the lateral aspect of the upper arms, thighs, and lateral cheeks (especially in children) > trunk and extensor aspects of the distal extremities • Keratotic follicular papules, often with a rim of erythema (see Fig. 12.16A) or a background of patchy erythema (especially on the cheeks) • The keratosis pilaris rubra (KPR) variant features numerous tiny, “grain-like” follicular papules superimposed on prominent confluent erythema (see Fig. 12.16B); often widespread on face & ears > trunk & proximal extremities, and tends to persist after puberty; presence of erythema rather than hyperpigmentation differentiates KPR from erythromelanosis follicularis faciei et colli, and a lack of atrophy in KPR differentiates it from keratosis pilaris atrophicans (see Ch. 38) • Keratolytic agents and topical retinoids are sometimes used to decrease the hyperkeratotic component, but the benefit is limited and these agents can be irritating, especially in AD patients; treatment with vascular lasers (e.g. pulsed dye laser) can sometimes improve associated erythema •

Palmar and plantar hyperlinearity

Increased prominence of the palmar and, less often, plantar creases Associated with ichthyosis vulgaris and FLG mutations

• •

Dennie–Morgan lines



Symmetric, prominent horizontal fold(s) (single or double) just beneath the margin of the lower lid, originating at or near the inner canthus and extending one-half to two-thirds the width of the lid

Periorbital darkening (“allergic shiners”)



Skin around the eyes appears gray to violet–brown, while the rest of the facial skin is rather pale Periorbital edema and lichenification may also be seen



Anterior neck folds



Horizontal folds across the middle of the anterior neck

Hertoghe sign



White dermographism



Absence or thinning of the lateral eyebrows

Stroking the skin leads to a white streak that reflects excessive vasoconstriction Most apparent on the forehead • Midfacial pallor and a delayed blanch response represent additional manifestations of aberrant vascular reactivity in patients with atopic dermatitis •

Follicular prominence

“Goose bump-like” appearance of the skin, most often on the trunk (see Fig. 12.6) More commonly observed in children with darkly pigmented skin

• •

Table 12.3 Associated features of atopic dermatitis (“atopic stigmata”). AD, atopic dermatitis. See Fig. 12.14.  

for the head, neck, and trunk. It is often associated with fever, malaise, and lymphadenopathy, and complications may include superinfection with S. aureus or S. pyogenes as well as herpetic keratoconjunctivitis and meningoencephalitis83. Patients with mutations in the filaggrin gene and those who have both severe AD and asthma have an increased risk for eczema herpeticum, and decreased production of antimicrobial peptides may have a pathogenic role. Patients with AD are also predisposed to the development of widespread molluscum contagiosum (see Ch. 81).

Ocular complications In addition to allergic rhinoconjunctivitis, the spectrum of atopic eye disease includes chronic manifestations such as atopic keratoconjunctivitis, which typically affects adults, and vernal keratoconjunctivitis that favors children living in warm climates. Symptoms include ocular itching, burning, tearing, and mucus discharge, often in association with conjunctival injection and blepharitis manifesting as swelling and scaling of the eyelids. Vernal keratoconjunctivitis features large, cobblestone-like papillae on the upper palpebral conjunctiva, and atopic keratoconjunctivitis is more prone to scarring. Additional infrequent ocular complications of AD include keratoconus and subcapsular cataracts, with anterior cataracts more specifically related to AD and posterior cataracts occurring more commonly84; rarely there is retinal detachment.

DIAGNOSTIC CRITERIA Several authors and groups have suggested guidelines to assist in establishing the clinical diagnosis of AD. Major features in these sets of criteria include pruritus, eczematous skin lesions in typical age-specific distribution patterns, a chronic or chronically relapsing course, early age at onset, and a personal and/or family history of atopy (see Table 12.1). Atopic stigmata, especially xerosis, are also recognized as supporting features (see Table 12.3 and Fig. 12.14). The Diepgen score represents another validated set of diagnostic criteria that are separated into objective, subjective, and laboratory features85. Validated scores to assess the severity of AD include the EASI (Eczema Area Scoring Index), SCORAD (SCORing Atopic Dermatitis), and POEM (Patient-Oriented Eczema Measure)86.

PATHOLOGY The histologic features of AD depend upon the stage of the lesion sampled. Acute, exudative eczema is characterized by marked spongiosis, with intraepidermal fluid collection leading to the formation of vesicles (micro and macro) or even bullae. Some dermal edema may also be present, together with perivascular lymphocytes that extend into the epidermis and a variable number of eosinophils (Fig. 12.20A). In subacute lesions, vesiculation is absent whereas acanthosis, hyperkeratosis,

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3

A

Fig. 12.18 Infected hand dermatitis in a patient with atopic dermatitis. There is impetigo-like crusting as well as pustules. Courtesy, Louis A Fragola, Jr, MD.  

Fig. 12.19 Eczema herpeticum. Grouped punchedout monomorphic erosions with hemorrhagic crusts on the arm (A) and posterior neck (B). Vesicles are rarely evident.  

A

B

Fig. 12.16 Keratosis pilaris. A Discrete perifollicular papules with central keratotic cores on the extensor surface of the upper arm. Each papule has a rim of erythema. B Keratosis pilaris rubra on the lateral face. This variant is characterized by tiny, “grain-like” follicular papules superimposed on confluent erythema. B, Courtesy, Angela Hernández-Martín, MD.  

Fig. 12.17 Pityriasis alba. Note the slight scale associated with the hypopigmented macules and patches on the cheeks. Courtesy, Antonio  

Torrelo, MD.

B

conspicuous, but there may be an increased number of mast cells and dermal fibrosis. These features are not specific, as similar findings are observed in other eczematous dermatoses such as allergic contact dermatitis. There are occasionally histologic clues to the etiology, such as individually necrotic keratinocytes that suggest an irritant contact dermatitis. However, a skin biopsy is usually more helpful in excluding other entities that can mimic AD clinically, such as mycosis fungoides.

218

and parakeratosis become evident (Fig. 12.20B). In chronic, lichenified AD, epidermal thickening is more pronounced in a pattern that may be either irregular or regular (psoriasiform). Changes in the granular layer vary from thickening secondary to rubbing, as seen in lichen simplex chronicus, to thinning when there is a psoriasiform pattern, seen in some nummular lesions. Spongiosis and inflammation are less

DIFFERENTIAL DIAGNOSIS The differential diagnosis of AD is broad and includes other chronic dermatoses, infections, infestations, and malignancies as well as metabolic, genetic (e.g. primary immunodeficiencies), and autoimmune disorders (Table 12.4).

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12 Atopic Dermatitis

an urticarial reaction within 30 minutes of patch testing on previously affected skin. Mycosis fungoides (MF) should be considered in adolescents and adults with chronic dermatitis poorly responsive to topical corticosteroid treatment. Because the histologic findings of early MF may be difficult to distinguish from those of AD, multiple biopsies are recommended, preferably from untreated areas of skin since corticosteroids can eliminate the epidermotropic T cells that point to the diagnosis of MF. Longitudinal evaluation of such individuals is required, especially when the clinical and/or histologic features are not classic for AD, with additional biopsies as indicated.

TREATMENT General Approach Because AD is a chronic, relapsing disease, the traditional approach was reactive management targeting acute flares with short-term treatment regimens. Based on insights into the underlying skin barrier defect and its relationship to inflammatory processes in the skin and other organs, a proactive approach that includes long-term maintenance therapy is now recommended (Fig. 12.21)87. This treatment strategy may modify the overall disease course and possibly prevent the development of atopic comorbidities. Management of AD includes education of patients/parents, gentle skin care, moisturizer use, and anti-inflammatory therapy to control subclinical inflammation as well as overt flares. Topical agents represent the mainstay of treatment. Severe disease may require phototherapy or systemic medications, usually in conjunction with continued topical therapy (Table 12.6)87. Factors that can potentially exacerbate AD should be identified and, if possible, avoided (see Table 12.1).

A

Educational interventions

B

Fig. 12.20 Histologic features of acute and subacute atopic dermatitis. A Acute lesion showing prominent spongiosis, epidermal hyperplasia, and a mild inflammatory infiltrate in the upper dermis. B Subacute lesion with parakeratosis and less spongiosis. A, Courtesy, Lorenzo Cerroni, MD.  

In infants, AD is often preceded and/or accompanied by seborrheic dermatitis, which commonly presents during the first month of life as yellowish-white, adherent scale-crusts on the scalp. In contrast to the typical distribution of infantile AD on the extensor surfaces of the extremities and cheeks as well as the scalp, infantile seborrheic dermatitis has a predilection for the skin folds, where lesions may be oozing and lack scale, and the forehead. Scabies in infants often has generalized involvement and can mimic AD; in addition to the presence of burrows or identification of the mite or eggs via dermoscopy or skin scrapings, scabies can usually be distinguished by the predominance of discrete small crusted papules, involvement of the axillae and diaper area, and the presence of acral vesiculopustules. Other less common conditions that occasionally represent a diagnostic consideration in infants, such as primary immunodeficiencies, are listed in Table 12.4. Adolescents and adults without a personal or family history of atopy who present with an eczematous eruption should have a thorough history and consideration of patch testing to assess for allergic contact dermatitis. This diagnosis should also be considered in children and adults with established AD who fail to respond as expected to treatment or who develop lesions in an atypical distribution pattern. Components of emollients or topical corticosteroid preparations represent potential allergens in these individuals. Protein contact dermatitis has a predilection for atopic individuals and can also present as a chronic eczematous dermatitis. Causes include a variety of foods and animal products (Table 12.5; see Ch. 16), and it is diagnosed by prick testing or observation of

Education of patients and families is an important aspect of atopic dermatitis management. Increased knowledge of the disease mechanisms and course, potential triggers, appropriate use of therapies, and the goals of management has been shown to increase treatment adherence and reduce fear and misconceptions88–91. Parents often seek an eradicable cause for their child’s AD and have difficulty accepting “control” rather than a “cure” for the condition. Addressing their specific concerns and acknowledging the stresses associated with this chronic disease, as well as noting the improvement in pruritus and sleep disturbances likely to result from treatment, can improve care. Online educational resources are available through organizations such as the National Eczema Association (nationaleczema.org). Psychological interventions to aid in coping with AD may have benefit, with reported approaches including biofeedback, cognitive-behavioral therapy, and stress management92.

Bathing Bathing can hydrate the skin and remove scale, crust, irritants, and allergens. Although there is a paucity of objective data on optimal bathing practices for AD, it is generally recommended that patients bathe or shower once daily for 5–10 minutes in warm (not hot) water, with use of a fragrance-free non-soap cleanser with a neutral to low pH as needed (e.g. syndets; see Ch. 153)87,93,94. Application of a moisturizer shortly after bathing is essential to maintain skin hydration95. If treatment with a topical corticosteroid or other anti-inflammatory agent is needed, it should be applied immediately after bathing, prior to the moisturizer; this has been referred to as the “soak and smear” technique93. With the exception of bleach (see below), there are no randomized controlled studies to support the use of bath oils, other bath additives, acidic spring water, or water-softening devices for AD87,96.

Moisturizers Daily use of moisturizers to counteract dry skin and reduce transepidermal water loss is a cornerstone of AD management97. Moisturizer application can reduce xerosis, pruritus, erythema, fissuring, and lichenification87, thereby decreasing the amount of anti-inflammatory medication required for disease control98. Standard moisturizers contain varying amounts of emollient agents that lubricate the skin, occlusive agents that prevent water loss, and humectants that attract water87.

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DIFFERENTIAL DIAGNOSIS OF ATOPIC DERMATITIS

Chronic dermatoses C>A

Seborrheic dermatitis

Common

B

Contact dermatitis – allergic* or irritant

Common

B

Psoriasis

Common

A>C

Nummular dermatitis

Uncommon (although nummular lesions can be seen in AD, nummular eczema outside this setting is uncommon)

A

Asteatotic eczema

Common

A>C

Lichen simplex chronicus (secondary to pruritus of variable etiology)

Common

Infections and infestations B

Scabies

Common

B

Dermatophytosis*

Common

B

HIV-associated dermatoses

Variable

C

HTLV-1-associated “infective dermatitis”

Variable

C

Chronic mucocutaneous candidiasis

Rare

C

Neonatal mucocutaneous candidiasis

Variable

B

Impetigo

Variable (nummular lesions of AD can mimic impetigo)

C

Congenital syphilis

Variable

Primary immunodeficiencies C

Wiskott–Aldrich syndrome

Rare

C

Hyperimmunoglobulin E syndromes

Rare

C

IPEX (immune dysregulation, polyendocrinopathy, enteropathy, X-linked) syndrome and IPEX-like conditions

Rare

C

Omenn syndrome

Rare

C

DiGeorge syndrome (congenital thymic aplasia)

Rare

C

Immunoglobulin deficiencies: X-linked hypogammaglobulinemia, common variable immunodeficiency, IgA deficiency

Variable

C

Ataxia telangiectasia

Rare

Malignancies A>C

Mycosis fungoides and Sézary syndrome

Uncommon

C

Langerhans cell histiocytosis

Rare

Metabolic and genetic disorders C

Netherton syndrome, generalized inflammatory peeling skin syndrome

Rare

C

Ectodermal dysplasias

Rare

C

Severe dermatitis–allergies–metabolic wasting (SAM) syndrome

Rare

B

Keratosis pilaris

Common

C

Hartnup disease

Rare

C

Phenylketonuria

Rare

C

Prolidase deficiency

Rare

B

Acrodermatitis enteropathica, glucagonoma syndrome, pellagra, riboflavin deficiency

Rare

C>A

Other causes of “nutritional dermatitis”, e.g. biotin deficiency, essential fatty acid deficiency, organic acidurias, cystic fibrosis

Rare

Autoimmune disorders A>C

Dermatitis herpetiformis

Uncommon

A>C

Pemphigus foliaceus

Uncommon

B

Dermatomyositis

Uncommon (but often misdiagnosed as AD in children)

A>C

Lupus erythematosus

Uncommon

B

Drug eruptions

Uncommon (although drug eruptions are common, those resembling atopic dermatitis are uncommon)

Other

220

A>C

Photoallergic contact dermatitis

Uncommon

A

Chronic actinic dermatitis

Uncommon

B

Graft-versus-host disease

Uncommon

*More common causes of disseminated eczema (“id reaction”), which is especially frequent in the setting of stasis dermatitis + allergic contact dermatitis. Table 12.4 Differential diagnosis of atopic dermatitis. A, adults; B, both; C, children/infants.  

There are limited data on the optimal amount and frequency of moisturizer application or comparing the effectiveness of different moisturizing products, and no particular preparation has been shown to be superior98,100. Weekly use of 150–200 g of moisturizer in young children and 250–500 g in older children/adults has been recommended, with liberal and frequent application94. Prescription emollient devices (PEDs) that aim to improve the defective skin barrier of AD include preparations that contain specific ratios of lipids (e.g. cholesterol, fatty acids, ceramides), palmitoylethanolamide, glycyrrhetinic acid, and other hydrolipids87. There is currently no evidence that these agents are superior to over-the-counter preparations.

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12 Atopic Dermatitis

Preparations should be free of dyes, fragrances, food-derived allergens such as peanut protein, and other potentially sensitizing ingredients99. Factors in selecting the formulation of the moisturizer include the degree of xerosis, the sites of application, acceptance by the patient, and the season. Ointments (e.g. petrolatum) contain higher concentrations of lipids, have occlusive properties, and are typically preservativefree; although they tend to cause less stinging when applied to inflamed skin, the greasiness of ointments is bothersome to some patients87,97. Creams may be a more acceptable option for such individuals, whereas lotions contain a higher water content and are not ideal for the xerosis of AD. Products with higher concentrations of urea or α-/β-hydroxy acids, which can decrease scaling, may also sting when used in children and on acutely inflamed or excoriated skin.

Topical Anti-Inflammatory Therapy Topical corticosteroids

CAUSES OF PROTEIN CONTACT DERMATITIS Fruits (banana, fig, kiwi, lemon, pineapple) Grains (barley, rye and wheat flours) • Latex • “Meats” (fish, seafood, beef, pork, poultry) • Mites and insects (rice flour beetle, dust mite, storage mite) • Nuts (almond, hazelnut, peanut) • Spices (caraway, curry, dill, garlic, paprika, parsley) • Vegetables (carrot, cauliflower, celery, cucumber, lettuce, mushroom, onion, parsnip, potato) • Animal dander, hair, saliva or urine (cow, deer, goat, dog, cat, rodents, hedgehog, rabbit, giraffe) • •

Table 12.5 Causes of protein contact dermatitis.  

Topical corticosteroids represent first-line pharmacologic therapy for AD. These agents have anti-inflammatory, antiproliferative, immunosuppressive, and vasoconstrictive actions, with effects on cutaneous T cells, macrophages, and dendritic cells (see Ch. 125)87,97. The efficacy of topical corticosteroids in AD has been verified in >100 randomized controlled trials101, and they have been shown to decrease the acute and chronic inflammation of AD as well as associated pruritus87. Topical corticosteroids are used to treat acute flares of AD and as maintenance therapy to prevent relapse. Factors in selecting the potency and vehicle of the topical corticosteroid include the location, type (e.g. acute versus chronic), thickness, and extent of the AD lesions; patient age and preference as well as the cost and availability of different preparations represent additional considerations. The corticosteroid should have an appropriate potency

MANAGEMENT PLAN FOR ATOPIC DERMATITIS (AD)

Treatment of active eczema Daily use of topical corticosteroid of appropriate strength until completely clear ± Antihistamine (for sedative/antipruritic effects) ± Antibiotic course (if superinfection)

*

Fig. 12.21 Management plan for atopic dermatitis. A The therapeutic regimen should include both treatment of active eczema and maintenance that includes the low-level in all and the high-level in some patients. B Intermittent courses of a systemic corticosteroid result in rebound flares and worsening of disease over time. In contrast, a proactive regimen utilizing topical corticosteroid leads to longer clear periods and milder disease over time. TCI, topical calcineurin inhibitor.  

High-level maintenance to usual “hot spots” Intermittent use of mid-potency topical corticosteroid (e.g. 2 days/week) and/or topical calcineurin inhibitor (TCI) (e.g. 3–5 days/week) Low-level maintenance (all patients) Daily use of emollient† to all skin Avoidance of triggers

*

Consider wet wraps following corticosteroid application for acute flares; if longstanding/severe AD, consider taper to every other day for a week before switching to high-level maintenance. †Emollient should be a cream or ointment

A

P P

Disease activity

P

Clear

CS

M

CS

M

CS

M

Clear

B

P = Prednisone CS = Topical corticosteroid of appropriate strength daily M = Maintenance: mid-potency CS 0–2 days/week, milder CS or TCI 0–5 days/week, emollient daily

Clearing Clear Flaring

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3

THERAPEUTIC LADDER FOR ATOPIC DERMATITIS

Evidence Moisturizers

1

Topical corticosteroids

1

Topical calcineurin inhibitors

1

Topical crisaborole

1

Topical tofacitinib (not currently FDA-approved)

1

Narrowband UVB, UVA–UVB, UVA1

1

Dupilumab

1

Cyclosporine (short/intermediate term)

1

Azathioprine

1

Mycophenolate mofetil/enteric-coated mycophenolate sodium

1*/2

Methotrexate

1*/2

Systemic corticosteroids (short term for severe acute flares; “rebound” exacerbations often occur upon discontinuation)

2

Omalizumab

2†

Nemolizumab (anti-IL-31 receptor A; not currently FDA approved)



Tofacitinib

2

Rituximab

2

Interferon-γ

**

IVIg

2†

Other – crude coal tar, hydroxychloroquine, extracorporeal photochemotherapy

2–3

Adjunctive therapies Wet wraps, open wet dressings, or soaks combined with topical corticosteroids for acute flares Dilute sodium hypochlorite (bleach) baths Treatment of associated bacterial, viral, or fungal infections Oral antihistamines for antipruritic‡ and sedative effects Leukotriene antagonists‡ Sodium cromoglycate (topical or oral)‡ Probiotics‡ (may have efficacy in primary prevention) Vitamin D supplementation‡

*In randomized controlled trials in adults with severe AD, enteric-coated mycophenolate

sodium was found to have similar efficacy to cyclosporine as maintenance therapy, and methotrexate was found to have similar efficacy to azathioprine (see text). **Although found to be effective in one randomized controlled trial, results of other studies have been inconsistent (see Ch. 128). †No significant benefit was found in a small controlled trial. ‡Inconsistent demonstration of efficacy in controlled trials. ¶Benefit for pruritus in patients with moderate to severe AD.

Table 12.6 Therapeutic ladder for atopic dermatitis (AD). Additional agents under investigation with potential benefit for AD include interleukin (IL)-13 inhibitors (e.g. lebrikizumab, tralokinumab), the thymic stromal lymphopoietin inhibitor tezepelumab, and the prostaglandin D2 receptor 2 inhibitor fevipiprant. Key to evidence-based support: (1) prospective controlled trial; (2) retrospective trial or large case series; (3) small series or individual case reports.  

222



to quickly gain control of the flare, and continuation of daily therapy until the active dermatitis is completely clear can minimize the likelihood of a rebound. Long-term daily use of an inadequately potent topical corticosteroid can result in a greater risk of side effects as well as less control of the eczema than relatively brief use of a more potent agent. Randomized controlled trials in children and adults with AD have demonstrated that the risk of relapse can be significantly reduced by proactive maintenance with twice-weekly application of a mid-potency topical corticosteroid to the usual areas of involvement when clear, with no evidence of cutaneous atrophy after up to 40 weeks of treatment87,102–104. For the face and body folds, high potency corticosteroids (especially long-term use) should be avoided if possible due to risk of cutaneous atrophy and (for the face) acneiform eruptions. However, short-term

use of a potent agent (e.g. mometasone furoate ointment) may be required to clear thick, exuberant lesions on the cheeks of infants. Potent corticosteroids (e.g. class 1–2) are often needed for lichenified plaques, nummular or prurigo-like lesions, and involvement of the palms and soles. Corticosteroid ointments (which minimize stinging) and creams are generally preferred considering the dryness of the skin in AD patients and the moisturizing effects of these vehicles. Application immediately after bathing improves cutaneous penetration and also decreases stinging. Corticosteroid solutions, foams, and oils represent options for AD on the scalp. Systematic reviews have concluded that topical corticosteroids have a favorable safety profile with short-term (up to several weeks) daily use and long-term intermittent use (see Ch. 125)105. However, “steroid phobia” is very common among AD patients and their parents, and it often leads to delayed and inadequate treatment106–108. It is essential that these fears and incorrect beliefs regarding topical corticosteroids are addressed to ensure adherence to the treatment plan. When AD does not respond as expected to topical corticosteroid therapy, adherence should be assessed, including the amount (grams/ tubes) and duration (consecutive days) of use. If possible, in-patient therapy for patients with severe AD can allow direct observation and intensive education. Potential complicating factors should be investigated, such as disease exacerbation by superinfection, irritants, or allergens. The latter can include immediate hypersensitivity reactions to foods and aeroallergens as well as delayed hypersensitivity to contact allergens, including components of moisturizers and topical mediations97.

Topical calcineurin inhibitors Two topical calcineurin inhibitors (TCIs) have been FDA-approved for the treatment of AD: (1) tacrolimus 0.03% and 0.1% ointment for moderate to severe disease; and (2) pimecrolimus 1% cream for mild to moderate disease (see Ch. 129). These agents suppress T-cell activation and modulate the secretion of cytokines and other proinflammatory mediators; they also decrease mast cell and dendritic cell activity99,109. The efficacy of TCIs in the treatment of AD has been proven in large clinical trials in adults and children ≥2 years of age and, for pimecrolimus, infants ages 3–23 months, although it is not currently approved for the latter group110. TCIs are particularly useful for AD affecting the face and intertriginous areas, sites where corticosteroid-induced skin atrophy is of increased concern and TCI therapy is especially effective97. TCIs are also beneficial in patients with frequently flaring or persistent AD that would otherwise require almost continual use of topical corticosteroids. Randomized controlled studies have shown that the proactive application of tacrolimus ointment 2–3 times weekly as maintenance can prevent flares of AD without increasing the overall amount of medication used111. The most common adverse effects with TCIs are local stinging and burning. These symptoms lessen after several applications, or if TCI use is preceded by a short topical corticosteroid course. For both topical tacrolimus and pimecrolimus, there has been no short-term or intermediate-term (>15 years) evidence of systemic immunosuppression or an increased risk for malignancy in either clinical studies or post-marketing surveillance, and long-term data collection is ongoing112. However, in 2006 the FDA introduced black box warnings for both drugs concerning a theoretical cancer risk; this was based on the occurrence of lymphomas in mice exposed to systemic levels 30–50-fold greater than the highest recorded blood levels in human patients. Pharmacokinetic studies in children and adults with AD have demonstrated minimal systemic absorption of TCIs, with transient detectable but low blood levels occasionally observed in patients with severe AD involving a large portion of the body surface area.

Crisaborole Crisaborole 2% ointment is a phosphodiesterase-4 (PDE-4) inhibitor that is FDA-approved for the treatment of mild to moderate AD in patients ≥2 years of age. In large randomized controlled trials, ~30% of such individuals achieved clear/almost clear skin with a ≥2-grade improvement after 4 weeks of twice daily treatment113. PDE-4 degrades cAMP, which leads to increased production of cytokines including IL-10 and IL-4 (see Fig. 130.3). The most common side effect is stinging or burning in the area of application.

Wet wrap therapy may be helpful in severe recalcitrant AD or during an acute flare. These moist, occlusive dressings increase skin hydration, act as a barrier to scratching, and enhance the penetration of topical corticosteroids. However, because of the latter effect, care should be exercised when using moderate and potent topical corticosteroids with wet wraps, and a possible increased risk of bacterial skin infections has been noted114. The wraps consist of application of a topical corticosteroid (sometimes diluted), followed by an inner wet layer and outer dry layer of cotton gauze or garments; they are left in place 8–24 hours per day, and the treatment duration should not exceed 2 weeks.

Phototherapy Narrowband UVB, UVA1, and UVA combined with UVB have each been shown to improve atopic dermatitis and associated pruritus115–117. The immunomodulatory effects of phototherapy occur via induction of T-cell apoptosis, reduction of dendritic cells, and decreased expression of Th2 cytokines such as IL-5, IL-13, and IL-31 (see Ch. 134). In addition, treatment with UVB has been shown to reduce S. aureus colonization of the skin in AD patients. Narrowband UVB and UVA1 can both be helpful for chronic AD lesions, and UVA1 may also be useful in the treatment of acute flares. Phototherapy can be combined with topical corticosteroids, especially in the initial phase of treatment. The side effect profile of phototherapy is favorable compared to systemic immunosuppressive agents, with potential “sunburn” and, with long-term treatment, photoaging and possibly an increased risk of skin cancer. The time required to travel several times a week to a phototherapy center may disrupt school or work for some patients, and a home UV unit may be an option for those receiving chronic treatment. In young children, phototherapy may be difficult for practical reasons, e.g. lack of cooperation.

Systemic Anti-Inflammatory Therapy Systemic anti-inflammatory medications may be employed for children and adults with moderate to severe AD that has failed to respond adequately to optimized topical treatment115. The risk–benefit profile should be carefully considered before starting an immunosuppressive agent, and patients receiving these medications require close monitoring for side effects (see Ch. 130). Combination of systemic treatment with topical corticosteroid therapy is frequently required to maximize benefit.

severe AD in children and adults, with modest benefit documented in randomized controlled trials120–122. Individuals with genetically determined low activity of the enzyme thiopurine methyltransferase (TPMT) have increased susceptibility to azathioprine-induced myelotoxicity. The risk of this complication can be decreased by determining TPMT activity and/or genotyping for TPMT polymorphisms prior to initiating therapy and adjusting the dose accordingly – 2–3.5 mg/kg/day if normal, 0.5–1 mg/kg/day if low. Azathioprine has a slow onset of action, with clinical improvement after 1–2 months and full benefit requiring 2–3 months of treatment97.

Methotrexate has anti-inflammatory effects and reduces allergenspecific T-cell activity123. It can have efficacy for refractory AD in adults and children with weekly administration of 7.5–25 mg or 0.3–0.5 mg/ kg, respectively, together with folic acid supplementation124. This regimen is well tolerated, with maximum clinical effect typically seen after 2–3 months of therapy125.

Mycophenolate mofetil Mycophenolate mofetil (MMF) inhibits the de novo pathway of purine synthesis, resulting in suppression of lymphocyte function. It may be of benefit for recalcitrant AD in adults and children, with 2–3 months of treatment typically required for maximum effect126. Dosing generally ranges from 1 to 3 g/day in adults and 30–50 mg/kg/day in children115.

Systemic Corticosteroids Continuous or chronic intermittent use of systemic corticosteroids for AD is not recommended due to a propensity for significant rebound flares upon their discontinuation and the unacceptable side effects of long-term administration (see Fig. 12.21 and Ch. 125)127. However, a short course of systemic corticosteroids may occasionally be considered for a severe, debilitating acute flare of AD while phototherapy or immunomodulatory treatment is being initiated.

Adjunctive Therapy Antimicrobials and antiseptics

Dupilumab is a human monoclonal antibody that targets the IL-4Rα subunit of heterodimeric IL-4 and IL-13 receptors (see Ch. 128 and Fig. 128.9C). It blocks signaling by these cytokines and the resulting Th2mediated inflammation. Dupilumab is FDA-approved for the treatment of adults with moderate to severe atopic dermatitis that is not adequately controlled with topical therapy. Large randomized controlled trials demonstrated a significant benefit in this group, with ~50% of patients achieving a 75% improvement in their EASI score after 16 weeks of dupilumab therapy61,118. Phase III studies in pediatric patients are in progress. Dupilumab is administered via subcutaneous injection of 600 mg initially and then 300 mg every other week, and it can be used with or without concurrent topical corticosteroid treatment. It has a favorable side effect profile, with injection site reactions and conjunctivitis each occurring in ~10% of patients.

Cyclosporine

Antihistamines

Cyclosporine is a potent inhibitor of T-cell-dependent immune responses and IL-2 production. Administration of cyclosporine typically leads to rapid improvement of AD in adults and children, and its efficacy has been established in randomized controlled trials101,119. However, because of potential side effects such as nephrotoxicity and hypertension, it is mainly used as a short-term treatment for AD, serving as a bridge between other therapies. Doses utilized for AD range from 3 to 6 mg/kg/day; treatment is often initiated at 5 mg/kg/day with subsequent tapering.

Azathioprine Azathioprine (AZA) is an inhibitor of purine synthesis that reduces leukocyte proliferation. It can be an effective treatment for moderate to

12

Methotrexate

Although skin colonization and infection with S. aureus can play a role in triggering AD flares, there is no evidence to support the use of topical antibiotics or antiseptic agents to treat AD, with the exception of “bleach baths”. In a randomized controlled study, bathing in 0.005% sodium hypochlorite (0.5 cup of household bleach [6% sodium hypochlorite] in a full 40-gallon bathtub) twice weekly together with a monthly 5-day course of intranasal topical mupirocin for 3 months led to greater improvement of moderate to severe, superinfected AD than placebo; both groups initially received a 2-week course of oral cephalexin and continued their topical anti-inflammatory regimen128. Subsequent small controlled studies evaluating “bleach baths” in AD patients without a recent superinfection have had inconsistent results regarding efficacy for eczema; no decreases in S. aureus colonization or effects on skin barrier function have been observed. Likewise, the routine use of systemic antibiotics for AD is not recommended. However, systemic antibiotics can be utilized when AD patients display clinical evidence of bacterial infection, such as pustules, a purulent exudate, or furuncles. Similarly, systemic antiviral agents should be used to treat eczema herpeticum.

Dupilumab

CHAPTER

Atopic Dermatitis

Wet wrap therapy

The role of histamine in the itch of AD is unclear94. Topical antihistamines are not effective for AD and are associated with risks of allergic contact dermatitis and systemic side effects87. Routine use of oral antihistamines to treat AD is not recommended97,129. Non-sedating antihistamines are not useful in the absence of additional conditions such as urticaria, dermographism, or allergic conjunctivitis115. Short-term use of sedating antihistamines may be employed during an acute AD flare associated with significant sleep disturbance.

Omalizumab The anti-IgE monoclonal antibody omalizumab is FDA-approved for chronic idiopathic urticaria in patients ≥12 years of age and for asthma in patients ≥6 years of age (see Ch. 128). It is administered every 2–4

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3

weeks via subcutaneous injection, and potential side effects include a risk of anaphylaxis. Although improvement of AD with omalizumab therapy has been described in uncontrolled series, a small randomized controlled trial in adults with AD did not demonstrate clinical improvement, despite reduction in IgE levels130.

Systemic immunotherapy Allergen-specific immunotherapy to abrogate allergic sensitizations has been employed to treat asthma and allergic rhinoconjunctivitis. The benefit of sublingual or subcutaneous immunotherapy for AD with allergens such as dust mites has also been investigated, but heterogeneous studies with poor methodologies make the results difficult to interpret131,132. Systemic immunotherapy for AD is not currently recommended.

Dietary supplements In atopic dermatitis, there is no evidence of a benefit from dietary lipid supplements such as fish oils, evening primrose oil, and borage oil133. Vitamin D supplementation is recommended for AD patients with 25(OH) vitamin D insufficiency or deficiency134.

Management of Coexisting Allergic Disease Food allergies Food hypersensitivity affects up to 30% of infants and young children with AD, and ~90% of reactions in this population are caused by five allergens: eggs (most often linked to AD exacerbations), milk, peanuts, soy, and wheat. Reactivity to peanuts as well as tree nuts, fish, and shellfish tends to persist, but children usually outgrow sensitivities to other foods. In infants with AD, introduction of age-appropriate peanutcontaining food as early as 4–6 months of age is recommended to reduce the risk of peanut allergy, with prior peanut-specific IgE and/or skin prick testing advised in those with severe AD135. Exposure to food allergens may exacerbate eczema in ~10–30% of infants and young children with AD, especially those with severe, recalcitrant disease136. However, food allergens more often produce an immediate/IgE-mediated reaction with urticaria, flushing, or itch within 1–2 hours of exposure. The National Institute of Allergy and Infectious Diseases (NIAID) recommends consideration of limited food allergy testing in children 95%) but low specificities and positive predictive values (40–60%)139. The clinical history and (in selected instances) provocation tests should be used to determine the relevance of positive laboratory and skin prick tests, since these allergens may not necessarily be exacerbating the patient’s AD. When relevant food allergens are identified and avoided, skin-directed AD therapy is still crucial. It is important that parents and/or patients understand that coexistent food allergies are not the “cause” of AD. Even in patients with a clinically relevant allergy, elimination diets can prevent immediate hypersensitivity but are less likely to affect the course of the AD140. The potential benefits must be balanced with the possible adverse sequelae from unnecessarily restrictive diets, and modified diets should be supervised by a pediatric dietician to assure that they are nutritionally adequate.

Aeroallergen reactivity Aeroallergen reactivity increases with age and is more prevalent in those with moderate to severe AD141. Common aeroallergens include dust mites, pollens, animal dander, and fungi. Exacerbation by aeroallergens

should be considered when AD is more severe in exposed areas, and direct skin contact with aeroallergens may trigger the development of eczematous lesions in some patients. Evaluation includes assessment of specific IgE antibodies and skin prick testing89.

Allergic contact dermatitis Patch testing to assess for contact sensitivity should be considered in AD patients with findings suggestive of ACD, a distribution pattern atypical of AD, sudden worsening, or recalcitrance to treatment. Common contact allergens in AD patients include components of topical medications and skin care products, such as fragrance, preservatives, lanolin, propylene glycol, cocamidopropyl betaine, bacitracin, neomycin, and sometimes corticosteroids142–144.

Complementary Therapies Chinese herbal therapy for AD has been evaluated in controlled trials; although benefit was reported in some studies, they had methodological issues and other investigators have not been able to replicate the results138,145. In one report, analysis of “herbal creams” noted by parents in the UK to improve their children’s AD revealed that 80% contained a corticosteroid, more than half of which represented clobetasol propionate146. Currently there is no evidence that homeopathic treatment is of benefit for AD147.

Prevention Although the therapeutic armamentarium available for AD can successfully control the disease in most patients, primary prevention of AD represents a highly desirable goal. There is no evidence that maternal food allergen avoidance during pregnancy or lactation protects against the development of AD in the child148. Recent studies have found that low maternal prenatal 25(OH) vitamin D levels may be associated with an increased risk of early-onset AD in the infant149. For infants with a family history of atopy, exclusive breastfeeding during the first 3–4 months of life or feeding with a formula containing hydrolyzed milk products may potentially decrease the risk of AD development compared to feeding with a formula containing intact cow’s milk protein150,151. However, exclusive breastfeeding for 6 months versus 3–4 months does not confer additional protection against the development of AD152.

Probiotics/prebiotics In several randomized controlled studies, administration of probiotics (e.g. Lactobacilli) or prebiotics, which represent non-digestible oligosaccharides that promote the growth of desirable bacteria, to pregnant mothers and infants was associated with significantly decreased frequencies of AD at 1 to 4 years of age153. However, multiple randomized controlled studies have failed to show benefit from probiotics as therapy for existing AD154. Further investigation is required to determine what pro/prebiotic agent should be employed and the optimal time of administration for AD prevention.

Emollient therapy as prevention Skin barrier impairment, measured by an increase in transepidermal water loss, occurs before the onset of clinical AD in children with FLG mutations155. Two randomized controlled trials in neonates with a family history of AD showed that daily use of a moisturizing cream, oil, emulsion, or ointment beginning within the first 3 weeks of life resulted in a 30–50% reduction in the likelihood of developing AD by 6–8 months of age156,157. For additional online figures visit www.expertconsult.com

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eFig. 12.1 Postinflammatory pigmentary alteration in atopic dermatitis. Postinflammatory depigmentation in a patient with widespread, severe disease and multiple lesions of prurigo nodularis.

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Courtesy, Jean L Bolognia, MD.

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C

eFig. 12.2 Infantile atopic dermatitis. Acute lesions with oozing and serous crusting are common in this age group and favor the face (A, B) and extensor extremities (C). Courtesy, Julie V Schaffer, MD.  

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eFig. 12.3 Childhood atopic dermatitis. A Extension from the antecubital fossae to the wrists and hands. Note the excoriations and lichenification. B Pink lichenified plaques with excoriation and hemorrhagic crusting as well as lichenification on the wrist. C Thick lichenified plaques on the wrist and hand. D Widespread eczematous dermatitis. A, Courtesy, Thomas Bieber, MD, and Caroline Bussmann, MD; B, C, Courtesy, Julie V Schaffer, MD; D, Courtesy, Luis Requena, MD.  

eFig. 12.4 Atopic dermatitis in childhood exacerbated by Malassezia. The patient has scaling of the scalp and confluent erythema of the upper face.  

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eFig. 12.5 Keratosis pilaris rubra. Keratosis pilaris rubra on the lateral face. This variant is characterized by tiny, “grain-like” follicular papules superimposed on confluent erythema.  

Courtesy, Julie V Schaffer, MD.

eFig. 12.6 Severe chronic hand dermatitis in an adult with atopic dermatitis.  

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randomized controlled trials. Br J Dermatol 2011;164:415–28. Hanifin J, Gupta AK, Rajagopalan R. Intermittent dosing of fluticasone propionate cream for reducing the risk of relapse in atopic dermatitis patients. Br J Dermatol 2002;147:528–37. Glazenburg EJ, Wolkerstorfer A, Gerretsen AL, et al. Efficacy and safety of fluticasone propionate 0.005% ointment in the long-term maintenance treatment of children with atopic dermatitis: differences between boys and girls? Pediatr Allergy Immunol 2009;20:59–66. Callen J, Chamlin S, Eichenfield LF, et al. A systematic review of the safety of topical therapies for atopic dermatitis. Br J Dermatol 2007;156:203–21. Charman CR, Morris AD, Williams HC. Topical corticosteroid phobia in patients with atopic eczema. Br J Dermatol 2000;142:931–6. Beattie PE, Lewis-Jones MS. Parental knowledge of topical therapies in the treatment of childhood atopic dermatitis. Clin Exp Dermatol 2003;28:549–53. Cork MJ, Britton J, Butler L, et al. Comparison of parent knowledge, therapy utilization and severity of atopic eczema before and after explanation and demonstration of topical therapies by a specialist dermatology nurse. Br J Dermatol 2003;149:582–9. Breuer K, Werfel T, Kapp A. Safety and efficacy of topical calcineurin inhibitors in the treatment of childhood atopic dermatitis. Am J Clin Dermatol 2005;6:65–77. Luger T, Boguniewicz M, Carr W, et al. Pimecrolimus in atopic dermatitis: consensus on safety and the need to allow use in infants. Pediatr Allergy Immunol 2015;26:306–15. Paller AS, Eichenfield LF, Kirsner RS, et al. Three times weekly tacrolimus ointment reduces relapse in stabilized atopic dermatitis: a new paradigm for use. Pediatrics 2008;122:e1210–18. Tennis P, Gelfand JM, Rothman KJ. Evaluation of cancer risk related to atopic dermatitis and use of topical calcineurin inhibitors. Br J Dermatol 2011;165:465–73. Paller AS, Tom WL, Lebwohl MG, et al. Efficacy and safety of crisaborole ointment, a novel, nonsteroidal phosphodiesterase 4 (PDE4) inhibitor for the topical treatment of atopic dermatitis (AD) in children and adults. J Am Acad Dermatol 2016;75:494–503.e4. González-López G, Ceballos-Rodríguez RM, GonzálezLópez JJ, et al. Efficacy and safety of wet wrap therapy for patients with atopic dermatitis: a systematic review and meta-analysis. Br J Dermatol 2016 Nov 8. doi: 10.1111/bjd.15165. [Epub ahead of print] Sidbury R, Davis DM, Cohen DE, et al. Guidelines of care for the management of atopic dermatitis: section 3. Management and treatment with phototherapy and systemic agents. J Am Acad Dermatol 2014;71:327–49. Garritsen FM, Brouwer MW, Limpens J, Spuls PI. Photo(chemo)therapy in the management of atopic dermatitis: an updated systematic review with implications for practice and research. Br J Dermatol 2014;170:501–13. Tzaneva S, Seeber A, Schwaiger M, et al. High-dose versus medium-dose UVA1 phototherapy for patients with severe, generalized atopic dermatitis. J Am Acad Dermatol 2001;45:503–7. Simpson EL, Bieber T, Guttman-Yassky E, et al. Two phase 3 trials of dupilumab versus placebo in atopic dermatitis. N Engl J Med 2016;375:2335–48. Schmitt J, Schäkel K, Schmitt N, Meurer M. Systemic treatment of severe atopic eczema: a systematic review. Acta Derm Venereol 2007;87:100–11. Meggitt SJ, Gray JC, Reynolds NJ. Azathioprine dosed by thiopurine methyltransferase activity for moderate-to-severe atopic eczema: a double-blind, randomised controlled trial. Lancet 2006;367:  839–46. Berth-Jones J, Takwale A, Tan E, et al. Azathioprine in severe adult atopic dermatitis: a double-blind, placebo-controlled, crossover trial. Br J Dermatol 2002;147:324–30. Waxweiler WT, Agans R, Morrell DS. Systemic treatment of pediatric atopic dermatitis with azathioprine and mycophenolate mofetil. Pediatr Dermatol 2011;28:689–94. Bateman EA, Ardern-Jones M, Ogg GS. Dose-related reduction in allergen-specific T cells associates with clinical response of atopic dermatitis to methotrexate. Br J Dermatol 2007;156:1376–7. Weatherhead SC, Wahie S, Reynolds NJ, Meggitt SJ. An open-label, dose-ranging study of methotrexate for

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moderate-to-severe adult atopic eczema. Br J Dermatol 2007;156:346–51. Lyakhovitsky A, Barzilai A, Heyman R, et al. Low-dose methotrexate treatment for moderate-to-severe atopic dermatitis in adults. J Eur Acad Dermatol Venereol 2010;24:43–9. Haeck IM, Knol MJ, Ten Berge O, et al. Enteric-coated mycophenolate sodium versus cyclosporin A as long-term treatment in adult patients with severe atopic dermatitis: a randomized controlled trial. J Am Acad Dermatol 2011;64:1074–84. Schmitt J, Schäkel K, Fölster-Holst R, et al. Prednisolone vs. ciclosporin for severe adult eczema. An investigator-initiated double-blind placebocontrolled multicentre trial. Br J Dermatol 2010;162:661–8. Huang JT, Abrams M, Tlougan B, et al. Treatment of Staphylococcus aureus colonization in atopic dermatitis decreases disease severity. Pediatrics 2009;123:e808–14. Diepgen TL, Early Treatment of the Atopic Child Study Group. Long-term treatment with cetirizine of infants with atopic dermatitis: a multi-country, double-blind, randomized, placebo-controlled trial (the ETAC trial) over 18 months. Pediatr Allergy Immunol 2002;13:278–86. Heil PM, Maurer D, Klein B, et al. Omalizumab therapy in atopic dermatitis: depletion of IgE does not improve the clinical course – a randomized, placebo-controlled and double blind pilot study. J Dtsch Dermatol Ges 2010;8:990–8. Compalati E, Rogkakou A, Passalacqua G, Canonica GW. Evidences of efficacy of allergen immunotherapy in atopic dermatitis: an updated review. Curr Opin Allergy Clin Immunol 2012;12:427–33. Bae JM, Choi YY, Park CO, et al. Efficacy of allergenspecific immunotherapy for atopic dermatitis: a systematic review and meta-analysis of randomized controlled trials. J Allergy Clin Immunol 2013;132:110–17. Williams HC. Evening primrose oil for atopic dermatitis. BMJ 2003;327:1358–9. van der Schaft J, Ariens LF, Bruijnzeel-Koomen CA, de Bruin-Weller MS. Serum vitamin D status in adult patients with atopic dermatitis: Recommendations for daily practice. J Am Acad Dermatol 2016;75:1257–9. Togias A, Cooper SF, Acebal ML, et al. Addendum guidelines for the prevention of peanut allergy in the United States: Report of the National Institute of Allergy and Infectious Diseases-sponsored expert panel. J Allergy Clin Immunol 2017;139:29–44. Eigenmann PA, Sicherer SH, Borkowski TA, et al. Prevalence of IgE-mediated food allergy among children with atopic dermatitis. Pediatrics 1998;101:  E8. Boyce JA, Assa’ad A, Burks AW, et al. Guidelines for the Diagnosis and Management of Food Allergy in the United States: Summary of the NIAID-Sponsored Expert Panel Report. J Allergy Clin Immunol 2010;126:1105–18. Tan HY, Zhang AL, Chen D, et al. Chinese herbal medicine for atopic dermatitis: a systematic review. J Am Acad Dermatol 2013;69:295–304. Sampson HA, Albergo R. Comparison of results of skin tests, RAST, and double-blind, placebo-controlled food challenges in children with atopic dermatitis. J Allergy Clin Immunol 1984;74:26–33. Bath-Hextall F, Delamere FM, Williams HC. Dietary exclusions for established atopic eczema. Cochrane Database Syst Rev 2008;(1):CD005203. Schäfer T, Heinrich J, Wjst M, et al. Association between severity of atopic eczema and degree of sensitization to aeroallergens in schoolchildren. J Allergy Clin Immunol 1999;104:1280–4. Fonacier LS, Aquino MR. The role of contact allergy in atopic dermatitis. Immunol Allergy Clin North Am 2010;30:337–50. Giordano-Labadie F, Rancé F, Pellegrin F, et al. Frequency of contact allergy in children with atopic dermatitis: results of a prospective study of 137 cases. Contact Dermatitis 1999;40:192–5. Jacob SE, McGowan M, Silverberg NB, et al. Pediatric contact dermatitis registry data on contact allergy in children with atopic dermatitis. JAMA Dermatol 2017;153:765–70. Gu S, Yang AW, Xue CC, et al. Chinese herbal medicine for atopic eczema. Cochrane Database Syst Rev 2013;(9):CD008642. Ramsay HM, Goddard W, Gill S, Moss C. Herbal creams used for atopic eczema in Birmingham, UK illegally

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interventions on the development of atopic disease in infants and children: the role of maternal dietary restriction, breastfeeding, timing of introduction of complementary foods, and hydrolyzed formulas. Pediatrics 2008;121:183–91. 151. von Berg A, Koletzko S, Grubl A, et al. The effect of hydrolyzed cow’s milk formula for allergy prevention in the first year of life: the German Infant Nutritional Intervention Study, a randomized double-blind trial. J Allergy Clin Immunol 2003;111:533–40. 152. Kramer MS, Kakuma R. Optimal duration of exclusive breastfeeding. Cochrane Database Syst Rev 2012;(8):CD003517. 153. Osborn DA, Sinn JK. Probiotics in infants for prevention of allergic disease and food hypersensitivity. Cochrane Database Syst Rev 2007;(4):CD006475.

154. Boyle RJ, Bath-Hextall FJ, Leonardi-Bee J, et al. Probiotics for the treatment of eczema: a systematic review. Clin Exp Allergy 2009;39:1117–27. 155. Flohr C, England K, Radulovic S, et al. Filaggrin loss-of-function mutations are associated with early-onset eczema, eczema severity and transepidermal water loss at 3 months of age. Br J Dermatol 2010;163:1333–6. 156. Horimukai K, Morita K, Narita M, et al. Application of moisturizer to neonates prevents development of atopic dermatitis. J Allergy Clin Immunol 2014;134:824–30, e6. 157. Simpson EL, Chalmers JR, Hanifin JM, et al. Emollient enhancement of the skin barrier from birth offers effective atopic dermatitis prevention. J Allergy Clin Immunol 2014;134:818–23.

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contain potent corticosteroids. Arch Dis Child 2003;88:1056–7. Ernst E. Homeopathy for eczema: a systematic review of controlled clinical trials. Br J Dermatol 2012;166:1170–2. Kramer MS, Kakuma R. Maternal dietary antigen avoidance during pregnancy or lactation, or both, for preventing or treating atopic disease in the child. Cochrane Database Syst Rev 2012;(9):CD000133. Blomberg M, Rifas-Shiman SL, Camargo CA Jr, et al. Low maternal prenatal 25-hydroxy vitamin D blood levels are associated with childhood atopic dermatitis. J Invest Dermatol 2017;137:1380–4. Greer FR, Sicherer SH, Burks AW, et al. American Academy of Pediatrics Committee on Nutrition, American Academy of Pediatrics Section on Allergy and Immunology. Effects of early nutritional

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SECTION 3 PAPULOSQUAMOUS AND ECZEMATOUS DERMATOSES

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Other Eczematous Eruptions Norbert Reider and Peter O. Fritsch

Chapter Contents Seborrheic dermatitis . . . . . . . . . . . . . . . . . . . . . . . . . . . . 228 Asteatotic eczema . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 230 Disseminated eczema (autosensitization) . . . . . . . . . . . . . . . 232 Nummular dermatitis . . . . . . . . . . . . . . . . . . . . . . . . . . . . 233 Pityriasis alba . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 234 HTLV-associated infective dermatitis . . . . . . . . . . . . . . . . . . . 234 Regional eczematous disorders . . . . . . . . . . . . . . . . . . . . . . 235

In addition to contact and atopic dermatitis, there exists a heterogeneous group of inflammatory skin diseases that obviously share the hallmarks of eczema, but display characteristic additional features. Their pathogenesis is generally less well understood, but most exhibit distinctive etiologic features.

SEBORRHEIC DERMATITIS Key features ■ Infantile and adult forms ■ Lesions favor the scalp, ears, face, central chest, and intertriginous areas ■ Etiologic links with active sebaceous glands, abnormal sebum composition, and Malassezia (Pityrosporum) spp. ■ Can be a cutaneous sign of HIV infection

Introduction

Pathogenesis Malassezia The genus Malassezia consists of lipophilic yeasts that are part of the normal resident skin flora6,7. Studies on the predominance of certain Malassezia spp. have revealed conflicting results8,9. M. furfur may behave as an opportunistic pathogen (e.g. fungemia in neonates receiving intravenous lipid emulsions) or cause or aggravate a spectrum of skin diseases: pityriasis versicolor, Malassezia (Pityrosporum) folliculitis, seborrheic dermatitis, and possibly atopic dermatitis.

Malassezia and seborrheic dermatitis M. furfur and related species can be regularly isolated from lesions of seborrheic dermatitis, including infantile seborrheic dermatitis (whereas healthy prepubertal children are not colonized to a significant degree). This coincides with the presence of enlarged sebaceous glands during the neonatal period. There is no simple quantitative relationship between yeast number and severity of seborrheic dermatitis, and unaffected skin may carry a load of organisms similar to seborrheic dermatitis lesions. Even in the scalp where M. furfur predominates amongst the resident flora, only twice as many yeasts may be recovered from areas of seborrheic dermatitis as from normal controls6. Similarly, severely immunodeficient HIV-infected patients with seborrheic dermatitis do not harbor more organisms than HIV-infected patients without seborrheic dermatitis10. Nonetheless, the number of yeasts drops in parallel with the therapeutic benefit of antimycotic agents and rises again when seborrheic dermatitis relapses.

Active sebaceous glands and seborrheic dermatitis

Seborrheic dermatitis was first described by Unna1, who also suspected Malassezia furfur (Pityrosporum ovale) as a causative factor. The nosologic position of seborrheic dermatitis was widely discussed for decades, the focus resting on dysfunction of the sebaceous glands and the high amounts of M. furfur present in scales of seborrheic dermatitis. In 1984 it was shown that seborrheic dermatitis could be suppressed by systemic ketoconazole2. This finding was corroborated by later studies3, and it became clear that seborrheic dermatitis was strongly linked to Pityrosporum yeasts. Today, it is accepted that several species of Malassezia, including M. furfur, play a direct role in seborrheic dermatitis (see Table 77.3)4.

Seborrheic dermatitis occurs predominantly in areas of the skin with active sebaceous glands and is often associated with sebum overproduction, which in turn can facilitate the growth of Malassezia. In infants, sebum is produced for a few weeks after birth, and the adult form of seborrheic dermatitis does not develop before puberty. This argues for a role for sebaceous gland activation by androgens. However, patients with seborrheic dermatitis may have normal sebum production and those with excessive sebum production are often free of seborrheic dermatitis. Thus, the amount of sebum produced alone does not appear to be the decisive risk factor. It has been proposed that the composition of the skin surface lipids is the relevant factor11. In patients with seborrheic dermatitis, triglycerides and cholesterol are elevated but squalene and free fatty acids are significantly decreased. Free fatty acids (which have a known antimicrobial effect) are formed from triglycerides by bacterial lipases, produced by the lipolytic Propionibacterium (Corynebacterium) acnes. A major constituent of the resident microbial skin flora, P. acnes has been found to be greatly reduced in seborrheic dermatitis12. Seborrheic dermatitis may thus be linked to an imbalance of the microbial flora.

Epidemiology

Immune responses to Malassezia in seborrheic dermatitis

There are infantile and adult forms, with the former being self-limited and confined to the first 3 months of life, while the latter is chronic with a peak in the fourth to sixth decades. The prevalence of seborrheic dermatitis is estimated to be 5%, but its lifetime incidence is

An etiologic role for immune mechanisms against Malassezia – particularly in view of the prominence of seborrheic dermatitis in HIV-infected individuals – has been suspected but never convincingly proven13. In addition, studies on cellular immunity have yielded contradictory

Seborrheic dermatitis is a common mild chronic eczema typically confined to skin regions with high sebum production and the large body folds. Although its pathogenesis is not fully elucidated, there is a link to sebum overproduction (seborrhea) and the commensal yeast Malassezia.

History

228

likely much higher. Men are afflicted more often than women. There is neither a genetic predisposition nor horizontal transmission. Extensive and therapy-resistant seborrheic dermatitis is an important cutaneous sign of HIV infection. It is also more commonly observed in patients with Parkinson disease, cerebrovascular accidents, and mood disorders5.

In addition to contact and atopic dermatitis, there exists a heterogeneous group of inflammatory skin diseases that obviously share the hallmarks of eczema, but also display characteristic additional features. Their pathogenesis is generally less well understood than that of contact or atopic dermatitis, but most exhibit distinctive etiologic features. There is some overlap within the entire group. The common disorders seborrheic dermatitis, asteatotic eczema and stasis dermatitis are discussed along with autosensitization (id reaction), nummular dermatitis, and dyshidrotic eczema. Two disorders which favor the pediatric age group, juvenile plantar dermatosis and diaper dermatitis, are also reviewed.

seborrheic dermatitis, asteatotic eczema, stasis dermatitis, disseminated eczema, autosensitization, id reaction, nummular dermatitis, HTLV-associated infective dermatitis, dyshidrotic eczema, infectious eczematous dermatitis, juvenile plantar dermatosis, diaper dermatitis

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13 Other Eczematous Eruptions

ABSTRACT

non-print metadata KEYWORDS:

228.e1

Clinical Features Seborrheic dermatitis is defined by clinical parameters, including: sharply demarcated patches or thin plaques that vary from pink–yellow to dull red to red–brown with bran-like to flaky “greasy” scales; vesiculation and crusting may occur but are rare and mostly due to irritation a predilection for areas rich in sebaceous glands – scalp, face, ears, presternal region – and, less often, the intertriginous areas a mild course with little or moderate discomfort. Seborrheic dermatitis is most often limited in extent, but generalized and even erythrodermic forms can occur, albeit rarely.

• • •

Infantile seborrheic dermatitis This form usually begins about one week after birth and may persist for several months. Initially, mild greasy scales adherent to the vertex and anterior fontanelle regions arise which may later extend over the entire scalp. Inflammation and oozing may finally result in a coherent scaly and crusty mass covering most of the scalp (“cradle cap”; Fig. 13.1A). Lesions of the axillae, inguinal creases, neck, and retroauricular folds are often acutely inflamed, oozing, sharply demarcated, and surrounded by satellite lesions (Fig. 13.1B). Superinfection with Candida spp. or occasionally bacteria (e.g. group A Streptococcus) can occur. A

Fig. 13.1 Infantile seborrheic dermatitis. A Involvement of the scalp with thick adherent yellow scale overlying mild inflammation is often referred to as “cradle cap”. B Glistening red plaques of the neck, axillary and inguinal folds as well as the penis and umbilicus. Note disseminated lesions   on the trunk and extremities. A, Courtesy,  

Antonio Torello, MD; B, Courtesy, Robert Hartman, MD.

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disseminated eruption of scaly papules with a psoriasiform appearance (“psoriasiform id reaction”) may develop on the trunk, proximal extremities, and face in association with exuberant or superinfected seborrheic dermatitis, especially of the diaper area.

Adult seborrheic dermatitis In adults, seborrheic dermatitis is generally found on the scalp and, usually of milder intensity, on the face; less often, lesions occur on the central upper chest and the intertriginous areas. Erythrodermic seborrheic dermatitis has been described as a rarity. Pityriasis simplex capillitii (dandruff) is defined as a diffuse, slight to moderate, fine white or greasy scaling of the scalp and terminal hairbearing areas of the face (beard area), but without significant erythema or irritation. Scales accumulate visibly on dark clothing. This common condition may be considered the mildest form of seborrheic dermatitis of the scalp. In seborrheic dermatitis of the scalp, there is inflammation and pruritus in addition to dandruff. The vertex and parietal regions are predominantly affected, but in a more diffuse pattern than the discrete plaques of psoriasis. Towards the forehead, the erythema and scaling are usually sharply demarcated from uninvolved skin, with the border either at the hairline or slightly transgressing beyond it. Pruritus is usually moderate but may be intense, particularly in patients with male pattern alopecia; folliculitis, furuncles, and meibomitis are not uncommon complications, elicited by scratching and rubbing. Seborrheic dermatitis of the facial skin is often strikingly symmetric, affecting the forehead, medial portions of the eyebrows, upper eyelids, nasolabial folds and lateral aspects of the nose, retroauricular areas, and occasionally the occiput and neck (Fig. 13.2). Lesions are yellowish-red, with a typical bran-like scale. Non-purulent otitis externa is often observed. If present, lesions of the trunk are preferentially found in the presternal and intertriginous areas; those on the central chest can have a petaloid appearance. Seborrheic dermatitis, like inverse psoriasis, is a cause of intertrigo. In patients with seborrheic dermatitis, the skin is sensitive to irritation, and exposure to sun or heat, febrile illnesses, and overly aggressive topical therapy may precipitate flares and dissemination. Irritated seborrheic dermatitis lesions can become bright red and erosive. Malassezia (Pityrosporum) folliculitis is another complication characterized by pruritic erythematous follicular papules, sometimes pustules, typically in sites rich in sebaceous glands. Adult seborrheic dermatitis has a chronic relapsing course. Patients feel well and systemic signs are absent. Extensive and severe seborrheic dermatitis, however, should raise the suspicion of underlying HIV infection. Among patients with seborrheic dermatitis tested for HIV infection, 2% were found to be positive, frequently in a late stage of their disease15. In patients with Parkinson disease, seborrheic dermatitis is a common finding, along with seborrhea. Its severity, however, is not correlated with that of the Parkinson disease16. The facial immobility of patients with Parkinson disease might result in a greater accumulation of sebum on the skin, resulting in a permissive effect on the growth of Malassezia16,17. Seborrheic dermatitis may be more common in patients with other causes of immobility such as cerebrovascular accidents. Rebound flares of seborrheic dermatitis can follow tapers of systemic corticosteroids.

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results6,7. The inflammation seen in seborrheic dermatitis may be irritant, caused by toxic metabolites, lipase, and reactive oxygen species6,13,14.

Pathology Acute seborrheic dermatitis displays spongiosis with a superficial perivascular and perifollicular lymphocytic infiltrate composed mainly of lymphocytes. Older lesions show irregular acanthosis and focal parakeratosis. The latter may appear similar to psoriasis, but exocytosis of neutrophils, Munro microabscesses, and confluent parakeratotic horny layers are absent.

Differential Diagnosis

%

Infantile seborrheic dermatitis is distinguished from atopic dermatitis by its earlier onset, different distribution pattern, and, most importantly, by the absence of pruritus, irritability and sleeplessness. In contrast to atopic dermatitis, infants with seborrheic dermatitis generally feed well and are content. Irritant diaper dermatitis is confined to the diaper area and tends to spare the skin folds (see below). Candidiasis

229

SECTION

Papulosquamous and Eczematous Dermatoses

3

Fig. 13.2 Adult seborrheic dermatitis of the face, ear and scalp. A Rather sharply demarcated pink plaque with flaky white and greasy scale. Note the fissure in the retroauricular sulcus. B Sharply demarcated pink–orange thin plaques with yellow, greasy scale, especially in the melolabial fold. When this degree of severity is seen, the possibility of underlying HIV infection needs to be considered. C Symmetric red–brown to violet plaques of the central forehead, nasal bridge and medial cheeks with an associated hypopigmented peripheral and figurate rim. Courtesy,  

Jeffrey P Callen, MD.

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% &

230

of the diaper area can result from colonization with fecal yeast and some infants have seborrheic dermatitis with a superimposed candidal infection. The differential diagnosis also includes streptococcal intertrigo (see Fig. 13.11). Infantile psoriasis may be difficult to distinguish from psoriasiform seborrheic dermatitis. Although psoriasiform diaper dermatitis can represent the initial manifestation of psoriasis, many affected infants do not subsequently develop psoriasis elsewhere. Rare conditions to be considered are Langerhans cell histiocytosis, “nutritional dermatitis” (e.g. acrodermatitis enteropathica; see Fig. 51.13), and Leiner disease. The last-mentioned is a questionable entity, once thought to be the maximal variant of infantile seborrheic dermatitis, but nowadays viewed as erythroderma in the setting of underlying immunosuppression (see Chs 10 & 60). When scalp scaling is present in prepubertal, especially black, children, the possibility of tinea capitis due to Trichophyton tonsurans should be considered. In pityriasis amiantacea, thick asbestos-like scales adhere to tufts of scalp hairs; up to a third of the affected children and adolescents eventually develop psoriasis. A number of entities are included in the differential diagnosis of adult seborrheic dermatitis. Distinction of seborrheic dermatitis of the scalp from psoriasis can be difficult, and there may be an overlap in some patients (“sebopsoriasis”). However, the plaques of psoriasis tend to be thicker, with silvery white scale, more discrete, less pruritic, and unassociated with seborrhea. In addition, features of psoriasis may be found elsewhere. Dry scaling of the scalp, along with dry brittle hair (as opposed to greasy hair), is a symptom of xerotic skin (e.g. in atopic dermatitis), frequently mistaken for (and mistreated as) seborrheic dermatitis. Mild erythema and scale of the posterior scalp, often with demonstrable hair loss, can be seen in dermatomyositis18. Seborrheic dermatitis of the face may closely resemble both early rosacea and the butterfly lesions of systemic lupus erythematosus. Lupus erythematosus rarely affects the nasolabial folds and often has a clearly demonstrable photodistribution. Notably, seborrheic dermatitis and rosacea frequently coexist. The differential diagnosis of seborrheic dermatitis of the trunk includes pityriasis rosea (but in this latter entity the lesions are ellipsoid in shape, have collarettelike scaling, and there is no predilection for the central chest) as well as superficial eruptive psoriasis and subacute cutaneous lupus erythematosus.

Seborrheic dermatitis of the intertriginous areas must be distinguished from inverse psoriasis, erythrasma, intertriginous dermatitis, candidiasis, and, rarely, Langerhans cell histiocytosis (Fig. 13.3).

Treatment Infantile seborrheic dermatitis Infantile seborrheic dermatitis usually responds satisfactorily to bathing and application of emollients. Ketoconazole cream (2%) is indicated in more extensive or persistent cases19. Short courses of low-potency topical corticosteroids may be used initially to suppress inflammation. Mild shampoos are recommended for the removal of scalp scales and crusts. Avoidance of irritation (e.g. the use of strong keratolytic shampoos or mechanical measures to remove the scales from the scalp) is important.

Adult seborrheic dermatitis The mainstay of therapy is the use of topical azoles (e.g. ketoconazole), either as shampoos (scalp) or as creams (body). The high response rate (75–90%) of this treatment has been documented in double-blind trials3. Ciclopirox olamine has antifungal and anti-inflammatory activities and has also been shown to be effective as a shampoo or cream in double-blind, randomized trials. Seborrheic dermatitis tends to relapse if a maintenance regimen is not instituted. As M. furfur has a slow proliferation rate, an interval of two to several weeks will pass until relapses appear. The intervals of topical therapy should follow this rhythm. Additional measures, particularly in the initial stages of treatment, include emollients and low-potency topical corticosteroids; the latter were found to be equally efficacious as topical azoles in a recent Cochrane analysis20. Second-line treatment options include zinc pyrithione, selenium sulfide, and tar shampoos as well as topical calcineurin inhibitors.

ASTEATOTIC ECZEMA Synonyms:  ■ Eczema craquelé ■ Winter eczema ■ Winter itch ■

Desiccation dermatitis

Common Irritant/frictional intertrigo* • Ill-defined erythema/maceration • Predisposing factors: obesity, heat & humidity, hyperhidrosis, diabetes mellitus, poor hygiene • Secondary infections common Seborrheic dermatitis** • Well-demarcated, pink to red, moist patches/plaques • Centered along inguinal creases • Involvement of scalp, face, ears Inverse psoriasis** • Well-demarcated, pink to red plaques • Shiny with little scale in folds • Centered along inguinal creases • Psoriasiform plaques elsewhere (e.g. genitals, intergluteal cleft, scalp, elbows/knees, hands/feet) • Nail psoriasis (pitting, oil spots)

Less common Candidiasis • Intense erythema with desquamation and satellite papules/pustules • Often involves scrotum as well as skin folds • Predisposing factors: occlusion, hyperhidrosis, diabetes mellitus, antibiotic or corticosteroid use, immunosuppression

Uncommon Granular parakeratosis

Systemic contact dermatitis, symmetrical drug-related intertriginous and flexural exanthema, toxic erythema of chemotherapy

Fig. 13.3 Differential diagnosis of intertriginous dermatoses in adults. Individual patients often have multiple disorders superimposed upon one another. Bullous impetigo and streptococcal intertrigo are considerably more common in children than adults. *Also referred to more nonspecifically as intertriginous dermatitis or intertrigo. **The term ‘sebopsoriasis’ may be used when features of both seborrheic dermatitis and psoriasis are present. Insets: Courtesy, Luis Requena, MD;  

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13 Other Eczematous Eruptions

DIFFERENTIAL DIAGNOSIS OF INTERTRIGINOUS DERMATOSES IN ADULTS

Eugene Mirrer, MD; Louis A Fragola, Jr, MD; David Mehregan, MD; Julie V Schaffer, MD.

Hailey−Hailey disease, Darier disease (depicted), pemphigus vegetans

Erythrasma • Pink−red to brown patches with fine scale • Coral-red fluorescence with Wood’s lamp illumination Zinc deficiency, necrolytic migratory erythema, other “nutritional dermatitis” Cutaneous Crohn disease

Dermatophytosis (tinea cruris) • Less often centered along inguinal creases • Expanding annular lesions with scaly erythematous border that may contain pustules or vesicles • Extension to inner thigh, buttock; usually spares scrotum • Coexisting tinea pedis/unguium very common

Langerhans cell histiocytosis

Extramammary Paget disease Allergic contact dermatitis • Consider if fails to respond to usual therapy

Key features ■ Dry, rough, scaly and inflamed skin with superficial cracking that resembles a “dried riverbed” ■ Sites of predilection are the shins, lower flanks, and posterior axillary line ■ Associated with aging, xerosis, low relative humidity, and frequent bathing

Introduction Dry skin (xerosis, exsiccosis, asteatosis) may result from both exogenous and endogenous causes: a dry climate or low indoor humidity; excessive exposure to water, soaps and surfactants; marasmus and malnutrition; renal insufficiency and hemodialysis; and heritable conditions such as ichthyosis vulgaris and atopic dermatitis. The most

common cause of xerosis is aging. Rarely, but especially when widespread and refractory to therapy, asteatotic eczema may be related to an underlying systemic lymphoma21.

History and Epidemiology Asteatosis as the cause of “nummular eczema” was first mentioned by Gross22 in the late 1940s. Dry skin probably occurs in everyone over the age of 60 years, but its severity is strongly linked to the exogenous factors mentioned above.

Pathogenesis Xerosis of aging skin is not caused by deficient sebum production, but by a complex dysfunction of the stratum corneum (see Ch. 124)23. There is a decrease of intercellular lipids with a deficiency of all key stratum corneum lipids24 and an altered ratio of fatty acids esterified to ceramide 125; this, plus a persistence of corneodesmosomes26 and premature expression of involucrin and formation of the cornified

231

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3

envelope27, results in corneocyte retention and marked impairment of barrier recovery24. The water-binding capacity of the stratum corneum layer is reduced owing to decreased synthesis of “natural moisturizing factor” (NMF), which contains urea and degradation products of filaggrin28. Consequently, the stratum corneum desiccates, loses its pliability and forms small cracks, which render the skin surface dull, rough and scaly. Mild xerosis is asymptomatic, but if more pronounced, the skin conveys unpleasant sensations such as itching and stinging. Inflammation is enhanced by the release of proinflammatory cytokines secondary to barrier perturbation, mechanical factors (scratching, rubbing), and the application of irritating or sensitizing substances in topical preparations and skin care products. Occasionally, eczema craquelé can appear in the setting of acute edema29, e.g. from congestive heart failure or the re-feeding of patients with anorexia nervosa. One theory is that this is related to the rate of distention of the skin.

Clinical Features Xerosis first arises on the shins. Later it may spread to the thighs, proximal extremities and trunk, but spares the face and neck as well as the palms and soles. It develops insidiously over many years, whereas asteatotic eczema often has a more subacute to acute onset. Xerotic skin is dry and dull, with fine bran-like scales that may be released as powdery clouds when patients take off their stockings. If more advanced, the skin exhibits a criss-cross pattern of superficial cracks and fissures of the horny layer (“crazy-paving”, eczema craquelé, “dried riverbed”) and appears pink to light red in color (Fig. 13.4). The

skin becomes rough, and it may develop an appearance similar to ichthyosis vulgaris (“pseudo-ichthyosis”). In more advanced stages of asteatotic eczema, there is a dull erythema as well as oozing, crusting, and abundant excoriations; disseminated nummular lesions are frequently seen. Vesiculation and lichenification are not regular features except when irritant or allergic contact dermatitis is superimposed. Hemorrhage into the fissures is occasionally observed.

Pathology Histologically, xerotic skin appears rather normal except for a compact and slightly irregular stratum corneum. Asteatotic eczema in addition exhibits mild focal spongiosis, parakeratosis, and a sparse inflammatory infiltrate in the superficial dermis.

Differential Diagnosis Conditions that need to be distinguished from asteatotic eczema include stasis dermatitis, adult atopic dermatitis (which may overlap with asteatotic eczema), allergic contact dermatitis, nummular dermatitis, and scabies.

Treatment Asteatotic eczema usually clears within a few days of the application of topical corticosteroid ointment. Proper attention must be given to the care of xerosis in order to avoid relapses: regular use of emollients, including petrolatum-, urea-, ceramide- or lactic acid-containing preparations, use of bath oils, and the elimination of factors that aggravate dry skin (see above). Topical calcineurin inhibitors have also been used. Coexisting stasis dermatitis should be treated as well (see below).

DISSEMINATED ECZEMA (AUTOSENSITIZATION) Synonyms:  ■ Autosensitization dermatitis ■ Autoeczematization ■

Generalized eczema ■ Id reaction

Key features ■ Secondary lesions of eczema distant from the primary site of exposure or involvement ■ Symmetric distribution pattern ■ Most often associated with allergic contact dermatitis and stasis dermatitis

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Introduction Dermatitis caused by exogenous agents initially arises at the site of contact. Not infrequently, additional patches of eczema develop at distant sites. This phenomenon, termed secondary dissemination, has puzzled dermatologists for decades. It is most often observed in allergic contact dermatitis, particularly if associated with stasis dermatitis (see Fig. 13.7), but may occur with uncomplicated stasis dermatitis, other forms of eczema, and, occasionally, severe tinea pedis. Disseminated eczema appears later than the primary lesions by a few days to weeks, tends to follow a strikingly symmetric distribution pattern, and shows a predilection for analogous body sites (e.g. extensor aspects of the lower and upper extremities, palms and soles). It may even arise in the absence of and without a preceding “primary” eczema, e.g. in nummular dermatitis (see below). Disseminated eczema must be distinguished from atopic dermatitis, which arises a priori in a disseminated fashion.

%

Fig. 13.4 Asteatotic eczema (eczema craquelé). A The distal lower extremity has obvious inflammation and xerosis with adherent white scales (pseudoichthyosis) as well as a criss-cross pattern of superficial cracks and fissures said to resemble a dried riverbed. B When widespread, there can be involvement of the trunk and proximal extremities. Along with the distal lower extremity, the area that surrounds the posterior axillary fold is a common site for asteatotic eczema. A, Courtesy, Louis A Fragola, Jr, MD; B, Courtesy, Thomas Schwarz, MD.  

232

History and Pathogenesis The phenomenon of secondary dissemination of eczemas was first described by Whitfield30, but its pathogenesis is still not fully elucidated. The orderly and symmetric distribution pattern may reflect systemic (hematogenous) dissemination and argues against simple

CHAPTER

13 Other Eczematous Eruptions

spread of contact irritants or allergens on the body surface. It is unclear, however, as to exactly what is disseminated via the bloodstream. It could be allergens; for example, the ingestion of allergens such as nickel has been shown to elicit disseminated eczema in sensitized individuals31,32. Hematogenous dissemination of microbial products leading to a variety of (non-infectious) manifestations distant from the site of infection, such as “tuberculids” and “bacterids”, was an accepted pathogenic model in the first half of the twentieth century and was extrapolated to the phenomenon of disseminated eczema. Dyshidrotic eczema of the soles, for example, was interpreted as an “id” reaction associated with tinea pedis, and nummular eczema as an “id” reaction caused by “focal” infections of the tonsils. Because disseminated eczema could hardly be attributed solely to infections, attention shifted to an “autosensitization” to epidermal antigens mediated by cytotoxic autoantibodies. This hypothesis, however, has never been verified. Instead, it became clear both from animal experiments33 and from routine patch testing (“excited skin syndrome”, “angry back”)34,35 that inflammatory processes of the skin, both allergic and irritant or caused by infections, lower the irritancy threshold of distant skin and thus facilitate the development of an eczematous reaction. Obviously, circulating activated memory T cells may play an additional role in disseminated eczema associated with allergic contact dermatitis, including that seen with poison ivy dermatitis following a short, rapid taper of systemic corticosteroids. It remains to be determined which factors regulate the symmetric distribution of disseminated eczema.

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Epidemiology An estimated two-thirds or more of patients with contact dermatitis associated with stasis dermatitis develop episodes of disseminated eczema. The incidence is much lower in the other types of eczema or tinea pedis.

Clinical Features Disseminated eczema associated with allergic contact dermatitis is characterized by moderately to poorly demarcated patches of eczema, most often on the extremities (Fig. 13.5A). Lesions are also found on the face, and less so on the trunk (Fig. 13.5B). The areas of involvement vary greatly in size and number and may consist of discrete papules which are often excoriated. Disseminated eczema in patients with seborrheic and asteatotic eczema differs slightly in predilection sites and morphology (see above).

Pathology In biopsy specimens of disseminated eczema, the histologic findings are those of an acute or subacute dermatitis (see section “Stasis dermatitis”).

Differential Diagnosis Conditions to be distinguished are those eczemas that can arise in a widespread or disseminated fashion: atopic dermatitis, airborne contact dermatitis, contact dermatitis caused by constituents of textiles, photoallergic dermatitis, and eczematous drug eruptions (e.g. calcium channel blockers). Other conditions to be considered are mycosis fungoides and Sézary syndrome.

Treatment Topical corticosteroids and systemic antihistamines are the mainstay of therapy. Short courses of systemic corticosteroids may be required, but identification and aggressive topical treatment of the inciting dermatosis is necessary to help prevent recurrences or a rebound flare.

NUMMULAR DERMATITIS Synonyms:  ■ Nummular eczema ■ Discoid eczema ■ Microbial eczema

%

Fig. 13.5 Id reactions in children due to allergic contact dermatitis (ACD) to nickel. A Multiple flat-topped papules, several of which have been excoriated, in addition to patches of eczema. B Square-shaped area of ACD due to nickel in a buckle with an associated id reaction. The latter consists of edematous crusted papules that are separate from the area of direct nickel contact. Courtesy,  

Julie V Schaffer, MD.

Key features ■ Coin-shaped, disseminated, eczematous lesions ■ Usually very pruritic ■ Chronic course

Introduction Nummular dermatitis is an uncommon disseminated eczema characterized by its coin-shaped lesions. Because such lesions can occur as a feature of atopic dermatitis, asteatotic eczema and stasis dermatitis, the nosologic position of nummular dermatitis as an independent clinical entity has been questioned.

Epidemiology Nummular lesions of eczema are not uncommon. However, in the literature there are widely discrepant data on the prevalence of nummular dermatitis, ranging from 0.1% to 9.1%36. Some of this variability may reflect the degree to which a distinction is made between nummular dermatitis and coin-shaped lesions observed in patients with other forms of eczema. Men are affected slightly more often and at a later age than women (>50 vs > cutaneous lupus – may have associated edema •

Exogenous

Allergens most commonly associated with ACD of the eyelids*

Allergic contact dermatitis (ACD) – occasionally airborne • Irritant contact dermatitis (ICD) – topical medications (e.g. for acne), anti-aging creams, cosmetics, occupational exposures





Fragrances, including Myroxylon pereirae (balsam of Peru) Preservatives – quaternium-15, DMDM hydantoin, methylchloroisothiazolinone, methyldibromoglutaronitrile • Topical antibiotics – neomycin • Metals – nickel, cobalt chloride, gold sodium thiosulfate • Surfactants – cocamidopropyl betaine, amidoamine •

*Adapted from North American Contact Dermatitis Group (2003–2004); Dermatitis. 2007;18:78–81. Table 14.2 Eyelid dermatitis – differential diagnosis and most commonly associated allergens. There is often a combination of endogenous plus exogenous causes. This patient had allergic contact dermatitis to neomycin.  

COMPONENTS OF THE AMERICAN CONTACT DERMATITIS SOCIETY (ACDS) SCREENING SERIES (2013), THE T.R.U.E. TEST® SERIES, THE AUSTRALIAN BASELINE SERIES, THE EUROPEAN BASELINE SERIES, AND THE NORTH AMERICAN CONTACT DERMATITIS GROUP (NACDG) 70

Allergen/hapten

Conc/vehicle

2-Bromo-2-nitropropane-1,3-diol (Bronopol®)

0.5% pet

Bacitracin

20% pet

Black rubber mix^

0.6% pet

Budesonide

0.1% pet

Carba mix

3% pet

Cobalt chloride

1% pet

Colophony (colophonium)

20% pet

Diazolidinyl urea

1% pet

Epoxy resin (bisphenol A)

1% pet

Ethylenediamine dihydrochloride

1% pet

Formaldehyde

1% aq

Fragrance mix I

8% pet

Gold sodium thiosulfate

2% pet

Hydrocortisone-17-butyrate

1% pet

Imidazolidinyl urea

2% pet

Mercapto mix

1% pet

Mercaptobenzothiazole (MBT)

1% pet

Methylchloroisothiazolinone/methylisothiazolinone

110 ppm aq

Methyldibromoglutaronitrile

0.5% pet

Myroxylon pereirae resin (balsam of Peru)

25% pet

Neomycin

20% pet

Nickel sulfate

2.5% pet

ACDS series (2013)

T.R.U.E. ® TEST

Australian baseline

European baseline

NACDG 70

0.01% pet

2% aq

2% pet

2% pet

0.01% aq

200 ppm aq

2% pet 2% pet*

5% pet

5% pet

^N-isopropyl-N′-phenyl PPD, N-cyclohexyl-N′-phenyl PPD, and N,N′-diphenyl PPD.

*Methyldibromoglutaronitrile combined with phenoxyethanol.

Table 14.3 Components of the American Contact Dermatitis Society (ACDS) Screening Series (2013), the T.R.U.E. TEST® Series, the Australian Baseline Series, the European Baseline Series, and the North American Contact Dermatitis Group (NACDG) 70. The concentrations and vehicles are used in the ACDS Series unless otherwise noted. Conc, concentration. aq, aqueous; pet, petrolatum; ppm, parts per million.  

Continued

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3

COMPONENTS OF THE AMERICAN CONTACT DERMATITIS SOCIETY (ACDS) SCREENING SERIES (2013), THE T.R.U.E. TEST® SERIES, THE AUSTRALIAN BASELINE SERIES, THE EUROPEAN BASELINE SERIES, AND THE NORTH AMERICAN CONTACT DERMATITIS GROUP (NACDG) 70

Allergen/hapten

Conc/vehicle

p-Phenylenediamine (PPD)

1% pet

p-tert-Butylphenol formaldehyde resin

1% pet

Paraben mix

12% pet

Parthenolide (sesquiterpene lactone)

0.1% pet

Potassium dicromate

0.25% pet

Quaternium-15

2% pet

Thiuram mix

1% pet

Tixocortol-21-pivalate

1% pet

Benzocaine

5% pet

T.R.U.E. ® TEST

Australian baseline

European baseline

NACDG 70

16% pet 0.5% pet 1% pet

1% pet 0.1% pet

Caine mix (benzocaine, tetracaine, dibucaine)

0.63 mg/cm2 PV

Disperse blue 106

0.05 mg/cm2 PV

Disperse blue 106/124 mix

1% pet

Quinoline mix

0.19 mg/cm2 PV

Thimerosal

0.007 mg/cm2 HPC

2-Ethylhexyl-4-methoxycinnamate

10% pet

2-Hydroxy-4-methoxybenzophenone (benzophenone-3)

10% pet

2-Hydroxy-4-methoxybenzophenone-5-sulfonic acid (benzophenone-4)

2% pet

2,6-Ditert-butyl-4-cresol (BHT)

2% pet

3-(Dimethylamino) propylamine (DMAPA)

1% aq

4-Chloro-3-cresol (PCMC)

1% pet

Amidoamine (stearamidopropyl dimethylamine)

0.1% aq

Benzalkonium chloride

0.1% pet

Benzyl alcohol

10%

Cetyl steryl alcohol

20% pet

Chlorhexidine digluconate

0.5% aq

Chloroxylenol (PCMX)

1% pet

Cinnamic aldehyde (cinnamal)

1% pet

Clobetasol-17-propionate

1% pet

Cocamide DEA (coconut diethanolamide)

0.5% pet

Cocamidopropyl betaine

1% aq

Compositae mix II

5% pet

Decyl glucoside

5% pet

Dibucaine

2.5% pet

Disperse Orange 3

1% pet

DL Alpha tocopherol

100%

DMDM hydantoin

1% pet

Ethyl acrylate

0.1% pet

Ethyl cyanoacrylate

10% pet

Ethyleneurea melamine-formaldehyde

5% pet

Fragrance mix II

14% pet

Glutaraldehyde (glutaral)

1% pet

Hydroxyethyl methacrylate

2% pet

0.01% aq 1% pet

6% pet

Table 14.3 Components of the American Contact Dermatitis Society (ACDS) Screening Series (2013), the T.R.U.E. TEST® Series, the Australian Baseline Series, the European Baseline Series, and the North American Contact Dermatitis Group (NACDG) 70. (cont’d) The concentrations and vehicles are used in the ACDS Series unless otherwise noted. Conc, concentration. aq, aqueous; HPC, hydroxypropyl cellulose; pet, petrolatum; PV, polyvidone.  

248

ACDS series (2013)

CHAPTER

ACDS series (2013)

T.R.U.E. ® TEST

Australian baseline

European baseline

NACDG 70

Allergen/hapten

Conc/vehicle

Iodopropynyl butylcarbamate

0.1% pet

0.5% pet

Jasminium officinale oil

2% pet

2% pet

Lanolin alcohol (wool alcohols; Amerchol 101)

50% pet

Lidocaine

15% pet

Methyl methacrylate

2% pet

Methylisothiazolinone

0.2% aq

Mixed dialkyl thioureas

1% pet

N,N-Diphenylguanidine

1% pet

Oleamidopropyl dimethylamine

0.1% aq

Phenoxyethanol

1% pet

Propolis

10% pet

Propylene glycol

30% aq

Sesquiterpene lactone mix

0.1% pet

Sorbic acid

2% pet

Sorbitan sesquioleate

20% pet

Tea tree oil

5% pet

Tosylamide formaldehyde resin

10% pet

Triamcinolone

1% pet

Triclosan

2% pet

Ylang ylang oil

2% pet

Basic red 46

1% pet

Betamethasone diproprionate ointment

1% pet

Betamethasone-17-valerate

1% pet

Bufexamac

5% pet

Chloroacetamide

0.2% pet

D-limonene

10% pet

Hydroxisohexyl 3-cyclohexene carboxaldehyde (Lyral®)

5% pet

Clioquinol

5% pet

N-Isopropyl-N-phenyl-4-phenylenediamine

0.1% pet

Primin (2-methoxy-6-n-pentyl-4-benzoquinone)

0.01% pet

Textile dye mix (8 disperse dyes)

6.6% pet

Carmine

2.5% pet

Shellac

20% alcohol

Majantol

5% pet

Carvone

5% pet

Mentha piperita oil (peppermint oil)

2% pet

Lavandula angustifolia oil (lavender oil)

2% pet

Desoximetasone

1% pet

Oleamidopropyl betaine

1% aq

30% pet

14 Allergic Contact Dermatitis

COMPONENTS OF THE AMERICAN CONTACT DERMATITIS SOCIETY (ACDS) SCREENING SERIES (2013), THE T.R.U.E. TEST® SERIES, THE AUSTRALIAN BASELINE SERIES, THE EUROPEAN BASELINE SERIES, AND THE NORTH AMERICAN CONTACT DERMATITIS GROUP (NACDG) 70

2% pet*

2% pet

*Methyldibromoglutaronitrile combined with phenoxyethanol.

Table 14.3 Components of the American Contact Dermatitis Society (ACDS) Screening Series (2013), the T.R.U.E. TEST® Series, the Australian Baseline Series, the European Baseline Series, and the North American Contact Dermatitis Group (NACDG) 70. (cont’d) The concentrations and vehicles are used in the ACDS Series unless otherwise noted. Conc, concentration. aq, aqueous; pet, petrolatum.  

disease control, the daily oral AM dose of corticosteroids should not exceed the equivalent of 20 mg of prednisone during testing.) Any one of these factors may decrease the individual’s ability to elicit a reaction when challenged by an allergen, resulting in a false-negative test10–12. A nurse or technician in the office can be trained to apply the patches, and this leads to improved efficiency. Either the pre-packaged allergens

are placed on the back as in the case of the T.R.U.E. TEST®, or the allergens are dispensed into chambers. There are a number of different patch test systems, including Finn Chambers® (SmartPractice, Phoenix, AZ) which are adhered to Scanpor® tape (Norgesplaster, Vennesla, Norway; available in the US from SmartPractice); allergEAZETM chambers (SmartPractice, Phoenix, AZ; Fig. 14.12); and IQ, IQ UltraTM, or

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3

Fig. 14.12 Placement of allergens to the patient’s back utilizing allergEAZETM chambers.  

IQ UltimateTM chambers (Chemotechnique Diagnostics; distributed by Dormer Laboratories, Inc.). These patches are applied to the back, reinforced with more Scanpor® tape if required, and the patient is sent home with instructions to keep the back dry and the patches secured until the second visit at 48 hours. Patients should also be told to avoid excessive sweating and to avoid heavy lifting, as the patches may come loose. Antihistamines can be prescribed, as they will not affect the outcome of the testing. A map of where the allergens were placed should be constructed for future reference. When the patient returns at 48 hours, the patches need to be examined to ensure that the testing technique was adequate. Initial inspection can determine that the patches are still in place. Confirmation comes from observing whether the chambers have adhered adequately so as to leave an impression in the skin (see Fig. 14.14G). As the patches are removed, their sites of application should be marked in order to identify the location of the particular allergens (Fig. 14.13). Two types of marking pen are recommended for this procedure: either a permanent surgical marker or a fluorescent highlighter. Highlighters are less messy and do not rub off as easily as the permanent marker. Because of the latter property, permanent markers can soil clothing and make interpretations at the second reading more difficult. Any positive reactions are scored according to the International Grading System (Table 14.4; Fig. 14.14). The patient is again asked to keep the back dry until the second reading, which can be performed from 72 hours to 1 week after the initial application of patches. When the patient returns for the second reading, the map is used to identify any positive reactions. If a fluorescent marker has been utilized, a Wood’s lamp may be needed to identify the markings. Positive

INTERNATIONAL GRADING SYSTEM FOR PATCH TESTS

Fig. 14.13 Sites of specific patch tests labelled for future reference following removal of the chambers.

+/−

Doubtful reaction, faint macular erythema

+

Weak, non-vesicular reaction with erythema, infiltration and papules

++

Strong, vesicular reaction with erythema, infiltration and papules

+++

Spreading bullous reaction



Negative reaction

IR

Irritant reaction





$

%

&

'

(

)

*

+

Fig. 14.14 Patch test reactions. A +/− to + reaction. B,C + reaction. D ++ reaction. E +++ reaction. F Erythematous papules at the edge of the Finn chamber application site (rim or edge effect). G Pustular irritant reaction at the site of the application of a metalworking fluid. The adjacent skin impression of a chamber reflects good adherence. H Three different patch test reactions: +/− to quaternium-15, + to formaldehyde, and ++ to nickel. C, F, H, Courtesy, Kalman Watsky, MD.  

250

Table 14.4 International Grading System for patch tests. See Fig. 14.14.

Interpreting the test Through the process of reviewing exposures and products, the clinical relevance of positive test results can be determined. Allergens may have past relevance. For example, a patient who presents with a known allergy to nickel and reactions to costume jewelry is found on patch testing to have a positive reaction to nickel. The nickel may have past relevance to the patient’s problem with costume jewelry but no current relevance to the chronic hand dermatitis. Relevance may also be determined to be current. For example, a positive reaction to tuliposidase A (see Ch. 17) in a florist who has hand dermatitis and contact with Alstroemeria when arranging flowers would have present relevance. In some individuals, relevance may be unknown, as in a patient with an eyelid dermatitis and a positive reaction to thimerosal but no past history of an allergy to contact lens solutions and no identifiable contact with thimerosal.

TREATMENT AND PATIENT EDUCATION Once allergens are positively identified, the patient should be given written information on all of these chemicals. The information sheets should contain data regarding the name of the chemical, possible synonyms, typical uses for the chemical, how to avoid exposure, and, when appropriate, substitutions. The sheets can be individually composed or obtained from books and copied for patient use13. In addition, the American Contact Dermatitis Society website (www.contactderm.org) is an excellent resource for allergen and product information, including patient information sheets (Table 14.5). The Contact Allergen Management Program (CAMP) is another feature of the website (available to members of the society): this allows the user to input the known allergens and the database assembles a list of products free of the allergens

entered. With this CAMP-generated list, the patients can then purchase products that lack the ingredients to which they are allergic. In addition, this website contains a Contact Dermatitis Alternatives Database which assists both patients and physicians with regard to appropriate substitutions for known allergens. The patient should also be instructed on how to read the labels of any new or old products not reviewed, in order to avoid future exposure. Each time the patient considers buying a product, he or she should utilize updated information sheets, because ingredients in a given product can change over time. In addition, ingredients in a particular product can change from location to location (e.g. between countries, or between the East and West Coast of the US) without a change in the packaging. After identifying the substances to which the patient is allergic, the most important step a physician takes is to educate the patient regarding the names of the allergens and how to avoid them. This empowers the individual and allows the physician to transfer to the patient the responsibility for avoiding said chemicals. When trying to identify allergens in the patient’s environment, one must also consider allergens transferred from other sources – so-called consort dermatitis (e.g. from spouse to spouse, such as the cologne on the husband causing a reaction on the face of his wife). Treatment of ACD primarily involves identification of the causative allergens. Once the allergens have been identified, the physician should try to clear the dermatitis with appropriate treatments, such as topical or, if necessary, systemic corticosteroids. The educated patient then needs to be diligent in avoiding the identified allergens. It may take 6 weeks or more to see complete and prolonged clearing, even when allergens are being avoided (Fig. 14.15). If the ACD is superimposed upon another dermatosis (e.g. stasis dermatitis, atopic dermatitis, ICD), then the latter will also need to be addressed via appropriate skin care including avoidance of skin irritants and moisturizing creams. If a patient is unable to undergo patch testing for some reason, or confirmation of patch test results is desired, a repeat open application test may be performed. This open use test, sometimes referred to as the “poor man’s patch test”, can prove useful. In an open use test, the patient applies the product in question to the same predetermined location (where there is no dermatitis) twice daily for 1–2 weeks; a common site is the antecubital fossa or flexor forearm. If dermatitis develops, it can be concluded that the patient is reacting to that product. Unfortunately, this type of testing does not allow the identification of individual ingredients. Avoidance of the product in question may result in clearing of the dermatitis. However, many products in the same class

CHAPTER

14 Allergic Contact Dermatitis

reactions are again graded according to the standard system (see Table 14.4). This later reading is necessary as patch test responses to some allergens such as gold, neomycin, and corticosteroids may be delayed. The actual products the patient uses in his or her work and/or home environment are examined and the ingredients compared with the positive reactions. In so doing, products can be divided into groups: those that are free of the suspected allergen(s) and are safe to use, and those that contain these chemical(s) and should be avoided. There will usually be some products with no ingredients listed, and these will have to be further investigated by the patient or physician by contacting companies and inquiring about ingredients.

Fig. 14.15 Allergic contact dermatitis to fragrance found in cologne. A Patient at the time of diagnosis. B Patient after avoidance of fragrances and his cologne.  

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3

ACDS EXPOSURE INFORMATION SHEET: BALSAM OF PERU

Other names Myroxylon pereirae, Black balsam, Toluifera pereirae balsam, Honduras balsam, China oil This complex substance contains many potential allergens: benzoic acid, benzyl acetate, benzyl benzoate, benzyl cinnamate, cinnamic acid, cinnamic alcohol, cinnamic aldehyde, cinnamyl cinnamate, eugenol, farnesol, isoeugenol, nerolidol, and vanillin

What is it? Balsam of Peru is a sweet-smelling natural substance derived from the bark of a tree native to Central America. For decades it has been added to topical preparations for its aroma and its antibacterial effect.

Where might it be found? Hemorrhoid treatment

Rectal suppository

Diaper or medicated ointment

Burn treatment or wound spray

Analgesic rub, liniment

Baby powder

Antiseptic lotion or cream

Deodorant

Feminine hygiene spray

Chinese ointment, Tiger balm

Aromatherapy product

Consecrated oil, incense

Dental cement

Hair tonic or pomade

Shampoo, conditioner

Shaving lotion, aftershave

Perfume, cologne

Cosmetic with fragrance

Sunscreen, tanning lotion

Toothpaste, mouthwash

Lip balms, chewing gum

Cough medicine, lozenges

Scabies treatment

Tincture of benzoin

Scented cleaning product

Scented candle

Air freshener, deodorizer

Scented paper product

Pet care product

Pesticide

Violin rosin

Histology slide fixative

Scented tobacco, coffee, tea

How to avoid it: Fragrances, flavorings, and natural substances are not always listed on ingredient labels. You may need to avoid using any product with a scent or fragrance. Be especially suspicious of things in your environment with a cinnamon, vanilla, or clove aroma. Choose only “fragrance-free” products,since “unscented” ones may actually contain a masking fragrance! • Read complete ingredient lists. Check the original box or package. Some products’ ingredient lists can be found on the internet at the manufacturer’s website, the store’s website, or http://householdproducts.nlm.nih.gov, http://www.cosmeticsdatabase.com, or sites like http://www.drugstore.com. • For possible workplace exposure, check the ingredient labels of all products encountered. Often commercial products contain a small amount of fragrance but do not list it. You may need to contact the manufacturer to find out. • Ask your doctor, nurse, attendant, hairdresser, masseuse, and others not to use fragranced products in your care. Be cautious of exposure from contact with a partner who uses fragranced products. If you must use fragranced products as you care for children, elders, or pets, wear protective rubber, nitrile, or vinyl gloves. • If there is a particular perfumed product you must use, ask your doctor how you can perform a repeat open application test (ROAT). • If you are not successful in clearing your skin rash by strictly avoiding contact with this allergen, your doctor may recommend you go on a special diet for one month to eliminate foods that may contain balsam of Peru in flavors and spices. •

Dietary restrictions to avoid balsam of Peru Avoid the following: citrus fruits and products that contain citrus flavor, peel, zest, or oil; tomatoes and tomato-containing products; spices such as cinnamon, cloves, vanilla, curry, nutmeg, allspice, anise and ginger as well as spicy condiments; sweet flavorings; colas, i.e. soft drinks, such as Dr Pepper, that may contain sweet flavorings and spices; and liquors such as wine, beer, gin and vermouth

Related substances You may show a cross-reaction to some closely related substances that are derived from plants. If you are not successful in clearing your skin rash by strictly avoiding sources of balsam of Peru, you may also need to avoid these: Beeswax

Benzaldehyde

Benzoic acid

Benzoin

Benzyl salicylate

Colophony

Coniferyl alcohol

Coniferyl benzoate

Coumarin

Diethylstilbestrol

Resorcin monobenzoate

Resorcinol

Propolis

Storax

Tolu balsam

Wood tars

Table 14.5 American Contact Dermatitis Society (ACDS) exposure information sheet: Balsam of Peru. Patient information sheets as well as the Contact Allergen Management Program (for members) are available at www.contactderm.org.  

use similar ingredients, and therefore the information may not be as useful as first anticipated, i.e. switching to another product may not result in continued clearance of the dermatitis.

ALLERGENS 252

The top 10 allergens, as identified by the North American Contact Dermatitis Group (NACDG) in 2013–2014, were nickel sulfate, fragrance mix I, methylisothiazolinone (MI), neomycin, bacitracin, cobalt

chloride, Myroxylon pereirae (balsam of Peru), p-phenylenediamine, formaldehyde, and methylchloroisothiazolinone/MI (Table 14.6)7. It should be noted that the list contains three preservatives, two metals, two topical antibiotics, two fragrance components, and one dye. Table 14.7 provides a list of additional important allergens (and the frequently identified routes of exposure). Of note, ACD in children is becoming increasingly recognized, and the most common allergens, as recently identified by the NACDG14 in this age group, are outlined in Table 14.8. Lastly, the modern era has brought us new products and new exposures to allergens, e.g. ACD from nickel and chromate in personal

Nickel Nickel ranks as the most common allergen tested by the NACDG, with 20.1% of patch test clinic patients reacting to it. In patch test clinics worldwide, nickel is the most common allergen, but it is often not relevant to the dermatitis in question14. However, upon questioning, past relevance may be discovered (e.g. previous mid-abdomen dermatitis). Nickel is a strong silver-colored metal that is commonly used in jewelry, buckles and snaps, as well as other metal-containing objects. It has been proposed that the high rate of nickel sensitivity, which in some patch test clinics approaches 30–40%, can be attributed in large part to ear piercing. Studies have shown that the metal posts used in ear piercing release varying amounts of nickel, allowing for direct exposure to an injured cutaneous surface16. Traditionally, the prevalence of nickel sensitivity has been higher in women; however, with newer trends toward piercing multiple body sites by both men and women, a

gender difference may become less apparent3. In Europe, there has been a significant reduction in nickel allergy as a result of legislation limiting nickel release from items in contact with the skin17. Clinically, nickel dermatitis most commonly occurs at sites of contact with earrings, necklaces, and the backs of watches (see Fig. 14.9A). Dermatitis of the mid-abdomen caused by a belt buckle or snap is common (Fig. 14.16A) and eyelid dermatitis from metal eyelash curlers or eyeglasses can also be seen. Facial dermatitis due to ACD to nickel and chromate within cellular phones has been described as has a generalized eruption caused by nickel from an iPad18. Concomitant reactions to nickel and cobalt have been reported and may be due to the frequency with which the two metals are used in combination19. Of note, sweating can increase the amount of metal leached from a product. A useful test to determine whether a particular item contains nickel is the dimethylglyoxime test (see Appendix), which identifies objects that release nickel using a pink color indicator (Fig. 14.16B). Individuals with nickel allergy should avoid costume jewelry. They can usually wear jewelry made of stainless steel, platinum or gold, but not white gold. Some clinicians advocate coating nickel-containing surfaces such as snaps on jeans with clear nail polish (e.g. Beauty Secrets Hardener) to prevent leaching by sweat onto the skin. However, the nail polish can rub off and should be reapplied if it is effective.

CHAPTER

14 Allergic Contact Dermatitis

electronic devices (Table 14.9). In addition, there is a global epidemic of ACD to methylisothiazolinone (MI) found in wet wipes and other personal care items15. The following section will briefly discuss pertinent information regarding several key allergens.

Methylisothiazolinone (MI) TOP TEN ALLERGENS AS IDENTIFIED BY THE NORTH AMERICAN CONTACT DERMATITIS GROUP

Allergic reactions (%)

Relevant reactions (%) (definite, probable, possible [combined])

Nickel sulfate

20.1

51.7

Fragrance mix I

11.9

84.4

Methylisothiazolinone

Test substance

10.9

93.1

Neomycin

8.4

24.7

Bacitracin

7.4

39.5

Cobalt chloride

7.4

42.1

Myroxylon pereirae (balsam of Peru)

7.2

87.9

p-Phenylenediamine

7.0

68.9

Formaldehyde

7.0

83.8

Methylchloroisothiazolinone/ methylisothiazolinone

6.4

92.2

Table 14.6 Table 10 allergens as identified by the North American Contact Dermatitis group. Adapted from North American Contact Dermatitis Group Patch Test Results:  

2013–2014. Dermatitis. 2017;28:33–46.

By 2014, patch test clinics around the world were reporting that MI was becoming their most common allergen20. MI was previously used in combination with methylchloroisothiazolinone (MCI) in a ratio of 3 : 1 in rinse-off products, and its concentration was lightly colored clothing

Adhesive allergens Colophony (colophonium)

Resin/adhesives, cosmetics, topical medications

Epoxy resin

Resin/adhesives

p-tert-Butylphenol formaldehyde resin

Resin/adhesives

Other Potassium dichromate

Metals, leather, cement

Sodium gold thiosulfate

Metal/jewelry, dental implants (clinical relevance can be difficult to determine)

Propylene glycol

Emulsifier/cosmetics, topical medicaments

Cinnamic aldehyde

Fragrance/flavoring

Budesonide

Corticosteroid/topical creams, ointments

Tixocortol-21-pivalate

Corticosteroid/topical creams, ointments

Ethylenediamine dihydrochloride

Antihistamine/topical creams

Lanolin (wool alcohol)

Emollient/topical creams, lotions

Benzocaine

Anesthetic/topical preparations

Cocamidopropyl betaine

Surfactant/shampoos, cosmetics

  Amidoamine

Contaminant of cocamidopropyl betaine

  Dimethylaminopropylamine

Contaminant of cocamidopropyl betaine

Oleamidopropyl dimethylamine

Emulsifier/cosmetics, shampoos, baby lotions

Hydroxyethyl methacrylate

Dental restorative materials, lacquers, artificial nails, adhesives

Shellac

Resin/varnishes, food coating, cosmetics

Propolis

Botanical/cosmetics, cosmeceutical/naturopathic/homeopathic products

Compositae mix

Includes Tanacetum vulgare (tansy) and Ambrosia spp. (ragweed)

Sesquiterpene lactone mix

Screen for Compositae allergy

DL-alpha tocopherol

Synthetic vitamin E/ointments, creams

Table 14.7 Additional important allergens. See Table 14.6 for ‘Top 10’ allergens identified by the North American Contact Dermatitis Group.  

254

CHAPTER

Metals – nickel sulfate, cobalt chloride*, potassium dichromate† Preservatives – quaternium-15, formaldehyde,methylchloroisothiazolinone/ methylisothiazolinone, 2-bromo-2-nitropropane-1,3-diol (Bronopol®) Topical antibiotics – neomycin sulfate, bacitracin Fragrances – fragrance mix I, fragrance mix II, Myroxylon pereirae (balsam of Peru) Components of rubber products – carba mix Other – lanolin alcohol, propylene glycol, p-phenylenediamine, carmine, propolis, decyl glucoside (surfactant), Compositae mix

*† Also contained in ceramics (see text). Also contained in leather. Table 14.8 Table 20 allergens in children and adolescents (20 times/day) represents one of the most important risk factors for developing irritant dermatitis20.

PATHOGENESIS Although the cellular mechanisms of ICD remain elusive, increasing evidence suggests that activated keratinocytes act as signal transducers in the control of host homeostatic responses to exogenous stimuli and they serve as key immunoregulators. An irritant chemical’s ability to induce cutaneous damage may serve to trigger pattern recognition receptors (PRR), including Toll-like receptors, providing the necessary impetus to activate the innate immune system21. While other mediators such as prostaglandins, leukotrienes, and neuropeptides may possibly play a role, cytokines carry the most interest in ICD as they are the central mediators in T-cell recruitment and inflammation. Several pathomechanisms have commonly been associated with ICD, including denaturation of epidermal keratins, disruption of the permeability barrier (see Ch. 124), damage to cell membranes, and direct cytotoxic effects, with different mechanisms at work with different irritants (Table 15.2). The mechanisms involved in the acute and chronic phases of ICD are fundamentally different. Acute reactions involve direct cytotoxic damage to keratinocytes, while repeated exposures to solvents and surfactants cause slower damage to cell membranes by removing surface lipids and water-retaining substances. The pathogenic pathway in the acute phase of ICD, common to many chemically unrelated irritants, begins with penetration of the irritant through the permeability barrier (stratum corneum), mild damage or stress to keratinocytes, and the release of mediators of

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IRRITANTS AND MECHANISMS OF TOXICITY

Irritant

Mechanisms of toxicity

Detergents

Barrier disruption, protein denaturation, membrane toxicity

Acids

Protein denaturation, cytotoxicity

Alcohols

Protein denaturation

Alkalis

Barrier lipid denaturation, cytotoxicity through cellular swelling

Oils

Disorganization of barrier lipids

Organic solvents

Solubilization of membrane lipids, membrane toxicity

Oxidants

Cytotoxicity

Reducing agents

Keratolysis

Water

If barrier is disrupted, cytotoxicity through swelling of viable epidermal cells

Table 15.2 Irritants and mechanisms of toxicity.

Irritant Reaction Irritant Contact Dermatitis Irritant reaction ICD is a type of subclinical irritant dermatitis in individuals exposed to wet chemical environments, such as hairdressers, caterers, metal workers or those with frequent exposures to soap and water. It is characterized by one or more of the following signs: scaling, redness, vesicles, pustules and erosions, often beginning under occlusive jewelry (e.g. rings) and then spreading onto the fingers and then the hands and the forearms. It may simulate dyshidrotic dermatitis and ultimately result in cumulative ICD if exposure is prolonged; however, ICD tends to resolve if exposure is discontinued.



Cumulative Irritant Contact Dermatitis inflammation with resultant T-cell activation. In this manner, once activation is initiated via epidermal cells, continuous T-cell activation independent of the exogenous agent may be maintained and barrier dysfunction perpetuated22. Tumor necrosis factor-α (TNF-α) and interleukin (IL)-1α are the major mediators, and they are capable of inducing production of other cytokines, chemokines, and adhesion molecules, leading to leukocyte recruitment to the site. Specifically, TNF-α, IL-6, and IL-1β upregulate expression of intercellular adhesion molecule-1 (ICAM-1)23. This is a predominant feature of ICD. In addition, IL-1 receptor antagonist (IL-1RA) and IL-8 increase substantially after exposure to the common irritant sodium lauryl sulfate. In the chronic phase of ICD, the role of the stratum corneum as a barrier is disrupted. Damage to the stratum corneum lipids (which mediate barrier function) is associated with loss of cohesion of corneocytes, desquamation, and an increase in transepidermal water loss. Transepidermal water loss is one of the triggering stimuli that promote lipid synthesis, keratinocyte proliferation, and transient hyperkeratosis during the restoration of the cutaneous barrier. However, damage with a solvent can disrupt this protective mechanism by occlusion and blockage of water evaporation, thus halting lipid synthesis and barrier recovery. After chronic exposure, the result is increased epidermal turnover manifested clinically by the chronic eczematoid irritant reaction24.

CLINICAL FEATURES Several different types of ICD have been described25 (see below). Consequences of the myriad forms of ICD range from postinflammatory pigmentary changes to poorly healing ulcers (Table 15.3).

Acute Irritant Contact Dermatitis Acute ICD, commonly seen with occupational accidents, develops when the skin is exposed to a potent irritant. The latter is capable of profound reactions on the skin surface: oxidation, reduction, desiccant, vesicant, or ion disruption26. The acute reaction reaches its peak quickly, usually within minutes to hours after exposure, and then starts to heal. This is termed the decrescendo phenomenon. Symptoms of acute ICD include burning, stinging, and soreness of the directly affected sites. Physical signs include erythema, edema, bullae, and possibly necrosis. These lesions are restricted to the area where the irritant or toxicant damaged the tissue, with sharply demarcated borders and asymmetry pointing to an exogenous cause. If there is no dermal injury, healing should be complete27. The potent irritants that most frequently lead to ICD are acids and alkalis, resulting in chemical burns.

Acute Delayed Irritant Contact Dermatitis 264

chloride (preservative/disinfectant), and ethylene oxide. Adverse reactions to these chemicals are considered idiosyncratic, except when they are applied to previously injured skin, e.g. sites of xerosis or atopic dermatitis27. Clinically visible inflammation is not seen until 8 to 24 hours (or more) after exposure, and thus may mimic allergic contact dermatitis; however, the associated symptom is more frequently burning rather than pruritus. Sensitivity to touch and water is elicited. This form of ICD is commonly seen during diagnostic patch testing.

Acute delayed ICD is a retarded inflammatory response characteristic of certain irritants, such as anthralin (dithranol), benzalkonium

Cumulative ICD is a consequence of multiple sub-threshold skin insults, without sufficient time between them for complete restoration of skin barrier function (see Fig. 16.4). It may be due to a variety of stimuli or frequent repetition of one factor, e.g. exposure to water both at the work place and at home. Clinical symptoms develop only after the cumulative damage exceeds an individually determined manifestation or elicitation threshold, which may decrease with progression of the disease. Weak irritants do not lead to clinical ICD if they are encountered far enough apart to allow for restoration of skin barrier function. However, if the same irritant exposures follow each other closely in time, or when the manifestation threshold is reduced (e.g. in a patient with active atopic dermatitis), cumulative ICD can develop. The properties of the irritating substance, e.g. pH, solubility, detergent action, physical state, are also important. In contrast to acute ICD, the lesions of chronic ICD are less sharply demarcated. Pruritus and pain due to fissures of hyperkeratotic skin are symptoms of chronic ICD. Signs may include xerosis, erythema and vesicles, but lichenification and hyperkeratosis predominate.

Asteatotic Dermatitis Asteatotic dermatitis, also referred to as asteatotic eczema, eczema craquelé, or exsiccation eczematid ICD, is a special variant seen primarily during dry winter months. Elderly individuals who frequently bathe without remoisturizing are at particular risk of developing asteatotic dermatitis. Intense pruritus is common, with the skin appearing dry with ichthyosiform scale and characteristic patches of superficially cracked skin (see Ch. 13).

Traumatic Irritant Contact Dermatitis Traumatic ICD may develop after acute skin trauma, such as from burns, lacerations, or acute ICD. Patients should be asked whether they have cleansed the skin with strong soaps or detergents. It is characterized by eczematous lesions, most commonly on the hands, that last for weeks to months with persistent redness, infiltration, scale, and fissuring in the affected areas.

Pustular and Acneiform Irritant   Contact Dermatitis Pustular and acneiform ICD results from exposure to certain irritants, such as metals, croton oil, mineral oils, tars, greases, cutting and metal working fluids, and naphthalenes (see Table 15.3 and Ch. 16). This syndrome should be considered in conditions in which folliculitis or acneiform lesions develop in settings outside of typical acne, particularly in patients with atopic dermatitis, seborrheic dermatitis, or prior acne vulgaris. The pustules are “sterile” and transient. Miliarial reactions, which may become pustular, can develop in response to occlusive clothing, adhesive tape, or ultraviolet and infrared radiation.

CHAPTER

Clinical feature

Possible irritant or toxin

Ulcerations

Inorganic acids (chromic, hydrofluoric, nitric, hydrochloric, phosphoric, sulfuric) Strong alkalis (calcium oxide, sodium hydroxide, potassium hydroxide, ammonium hydroxide, calcium hydroxide, sodium metasilicate, sodium silicate, potassium cyanide, trisodium phosphate, sodium carbonate, potassium carbonate) Salts (arsenic trioxide, dichromates) Solvents (acrylonitrile, carbon bisulfide) Gases (ethylene oxide, acrylonitrile)

Folliculitis

Oils and greases Tar and asphalt Chlorinated naphthalenes and polyhalogenated biphenyls Arsenic trioxide Glass fibers

Miliaria

Occlusive clothing and overheating Adhesive tape Ultraviolet and infrared radiation Aluminum chloride

15 Irritant Contact Dermatitis

CLINICAL FEATURES SUGGESTING AN IRRITANT OR TOXIC ETIOLOGY

Pigmentary changes Hyperpigmentation

Any irritant or allergen, especially phototoxic agents such as psoralens, tar, asphalt, psoralen-containing plants Metals, such as inorganic arsenic (systemically), silver, gold, bismuth, mercury Radiation: ultraviolet, infrared, microwave, ionizing



Hypopigmentation

p-Tert-amylphenol p-Tert-butylphenol Hydroquinone (HQ) Monobenzyl ether of HQ Monomethyl ether of HQ p-Tert-catechol

Alopecia

Borax Chloroprene dimers

Urticaria

Animals (arthropods, caterpillars, corals, jellyfish, moths, sea anemones) Balsam of Peru Cosmetics (e.g. sorbic acid) Drugs (alcohol [ethanol], benzocaine, camphor, capsaicin, chloroform, iodine, methyl salicylate, resorcinol, tar extracts) Foods (cayenne pepper, fish, mustard, thyme) Fragrances and flavoring agents (cinnamon oil, cinnamic acid and aldehyde, benzaldehyde) Metals (cobalt) Plants (seaweed, stinging nettles), woods Preservatives (benzoic acid) Textiles (e.g. blue dyes)



p-Cresol 3-Hydroxyanisole Butylated hydroxyanisole 1-Tert-butyl-3, 4-catechol 1-Isopropyl-3, 4-catechol 4-Hydroxypropriophenone

Table 15.3 Clinical features suggesting an irritant or toxic etiology.  

Non-erythematous Irritant Contact Dermatitis Non-erythematous ICD may be defined as a subclinical form of ICD with early stages of skin irritation seen as changes in the stratum corneum barrier function without a clinical correlate.

Subjective or Sensory Irritant Contact Dermatitis Subjective or sensory ICD is characterized by reports of a stinging or burning in the absence of visible cutaneous signs of irritation. Irritants capable of eliciting this reaction include propylene glycol, hydroxy acids, ethanol, and topical medications such as lactic acid, azelaic acid, benzoic acid, benzoyl peroxide, mequinol, and tretinoin. Sorbic acid, a preservative in concentrations of up to 0.2% in foods, cosmetics and drugs, may also produce sensory irritation in predisposed individuals. This reaction to irritants such as lactic or sorbic acid may be reliably reproduced with dose responsiveness in double-blinded exposure tests.

Airborne Irritant Contact Dermatitis Airborne ICD develops in irritant-exposed sensitive skin of the face and periorbital regions. While this often simulates photoallergic reactions, involvement of the upper eyelids, philtrum, and submental regions in patients with airborne ICD may aid in distinguishing

between these two entities. Airborne ICD results from exposure to floating dusts, fibers (particularly fiberglass), and volatile solvents and sprays28.

Frictional Irritant Contact Dermatitis Frictional ICD is a distinct ICD subtype resulting from repeated lowgrade frictional trauma. It is often acknowledged to also play an adjuvant role in allergic contact dermatitis and ICD. The frictional response includes hyperkeratosis, acanthosis, and lichenification, often progressing to hardening, thickening, and increased toughness.

Contact Urticaria Contact urticaria is divided into non-immunologic and immunologic subtypes (see Ch. 16), with the former occurring more frequently and in the absence of previous exposure. Irritants that can produce immunologic contact urticaria include parabens (preservatives), henna, ammonium persulfate (oxidizing agent), and latex. Non-immunologic contact urticaria can be caused by a number of exposures, from caterpillars and jellyfish to stinging nettles and foods (see Table 15.3)29. Risk factors include atopy, hand dermatitis, previous mucosal exposure to latex (e.g. urinary catheterization), and allergies to fruits (e.g. kiwi, avocado; see Table 16.6).

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PATHOLOGY



The histopathologic features of ICD vary according to the nature of the irritant, but often include mild spongiosis, necrosis of keratinocytes, and an inflammatory infiltrate rich in neutrophils. The combination of a neutrophil-rich superficial perivascular infiltrate plus widely scattered necrotic keratinocytes is most typical; sometimes there is even full-thickness epidermal necrosis and subepidermal clefting. Mild ICD can resemble allergic contact dermatitis. Over time, additional histologic findings include acanthosis with mild hypergranulosis and hyperkeratosis. In aggregate, these elements are not specific, and they cannot be confidently differentiated from either chronic allergic contact dermatitis or other types of chronic eczemas.

Kalman Watsky, MD.

Classification of Irritant Chemicals Acids A variety of both inorganic and organic acids can be corrosive to the skin. Acids cause epidermal damage via protein denaturation and cytotoxicity. Principally, all strong acids give the same clinical features, including erythema, vesication, and necrosis. Inorganic acids are commonly used in industry, especially hydrofluoric, sulfuric, hydrochloric, chromic, nitric, and phosphoric acids (Table 15.4). Hydrofluoric acid and sulfuric acid cause the most severe burns, even at low concentrations, and there can be significant absorption leading to systemic toxicity30. In general, the organic acids tend to be less irritating. Among the organic acids, acetic, acrylic, formic, glycolic, benzoic, and salicylic acids are the most common irritants, particularly after prolonged exposure. The uses and properties of acrylic acid and formic acid are outlined in Table 15.4. Acetic acid is a constituent of vinegar, flavoring agents, and astringent mouthwashes, whereas glycolic, benzoic, and salicylic acids are mild irritants whose properties can be harnessed for therapeutic and cosmetic purposes, when used in low concentrations.

Alkalis Alkalis or bases often cause more painful and severe damage than most acids, with the exception of hydrofluoric acid. There are generally no vesicles, but rather necrotic skin that first appears dark brown, then black, and ultimately becomes hard, dry, and cracked. Alkalis disrupt barrier lipids and denature proteins with subsequent fatty acid saponification, thus subjecting the cell to edema and resultant cytotoxicity. The emulsifying effect of soaps formed in the process facilitates the further penetration of the alkali into the deeper layers of the skin. Strong alkalis include sodium, ammonium, calcium, and potassium hydroxide; sodium and potassium carbonate; and calcium oxide, used primarily in the manufacture of bleaches, dyes, vitamins, pulp, paper, plastics, and soaps and detergents31,32. Calcium hydroxide is liberated from wet cement, which has an initial pH of 10–12 that rises to 12–14 as the cement sets (see Table 15.4).

Metal salts Metals represent an important and commonly encountered group of irritants, with irritant reactions to metal salts ranging from folliculitis and pigmentary changes to ulceration (see Table 15.4).

Solvents

266

Fig. 15.2 Bilateral irritant contact dermatitis of the palms secondary to repeated contact with paint solvents. Extensive patch testing excluded allergic contact dermatitis in this professional paint and crayon illustrator. Courtesy,

A wide variety of solvents are used daily in processes such as chemical reactions, hydraulic systems, metal refining, dry cleaning, and metal degreasing. Nearly all of them are primary irritants to varying degrees (see Table 15.4), with only a few, such as turpentine, also being able to elicit allergic sensitization. Solvents act mainly by dissolving the intercellular lipid barrier of the epidermis, thereby substantially compromising barrier function. Prolonged skin contact can result in severe dermatitis as well as symptoms and even death from systemic absorption, making early recognition of skin manifestations important in the prevention of systemic toxicity. After repeated exposure, the hands, and occasionally the hands and face, develop erythema, scaling and dryness, eventually evolving into eczema (Fig. 15.2). The irritating capacity of organic solvents, attributed mainly to their lipophilicity, follows the order: aromatic > aliphatic > chlorinated > turpentine > alcohols > esters > ketones33. In the common clinical scenario of solvent then soap and

water exposure, there is a synergistic degradation of epidermal barrier function, pointing to the importance of personal protection and hygiene34.

Alcohols/glycols Alcohols are used widely as solvents, disinfectants, preservatives in cosmetics, and penetration enhancers in drug delivery systems. Most have only mild irritating effects, with irritancy decreasing (and bactericidal activity increasing) as the molecular weight and length of the carbon side chain increases35. Alcohols are the safest known topical antiseptic compounds, providing bactericidal activity against most Gram-positive and Gram-negative bacteria as well as many fungi and viruses. Most appropriate for this use are diluted solutions of ethyl alcohol, propyl alcohol, and isopropyl alcohol, which act by means of protein denaturation. In cosmetics, alcohol is used as a preservative to prevent microbial contamination and to decrease viscosity. The principal mechanism by which alcohols enhance percutaneous absorption is hypothesized to be the extraction of intercellular lipids from the stratum corneum36,37. Glycols, or diols, such as ethylene glycol and propylene glycol, are aliphatic alcohols commonly used in cosmetic products as solvents, emulsifiers, humectants, or keratolytics. Propylene glycol can produce both allergic and irritant contact dermatitis and sources of exposure include personal care products, topical corticosteroids, and other topical medications38. Of note, propylene glycol is typically used in cosmetics in concentrations topical antibiotics (e.g. neomycin), metals (e.g. nickel; perioral > vermilion lips), propolis, topical corticosteroids

Lower >> upper vermilion lip Background of photodamage History of AKs, BCC, SCC May have diffuse hyperkeratosis and/or discrete AKs

Irritant Contact Dermatitis

15

*

DIFFERENTIAL DIAGNOSIS OF CHEILITIS

Granulomatous cheilitis Diffuse enlargement of lip Superimposed processes may lead to secondary changes May be associated with scrotal tongue, 7th nerve palsy, Crohn disease

Candidal cheilitis Predisposing factors: dentures/orthodontic appliances, inhaled/oral corticosteroids, diabetes mellitus, HIV infection, deep oral commissure grooves, drooling May have erosions Angular fissures More likely to have oral thrush

Fig. 15.5 Differential diagnosis of cheilitis. Uncommon causes include cheilitis glandularis, actinic prurigo, lichen sclerosus, and nutritional deficiencies. *Often a combination, e.g. atopic dermatitis plus irritant contact dermatitis. AKs, actinic keratoses; BCC, basal cell carcinoma; GVHD, graft-versus-host disease; SCC, squamous cell carcinoma. Courtesy, Jean L Bolognia, MD.  

CLASSIFICATION OF HAND DERMATITIS

Hand dermatitis

Infection

Endogenous

Atopic dermatitis

Psoriasis

• + PH/FH atopy • Distal fingers affected by subacute and chronic changes

• Lesions of psoriasis elsewhere, including nails • + FH • Psoriatic arthritis • Well-marginated plaques with scale and/or pustules

Other, e.g. dyshidrotic, keratotic eczema

• Clusters of vesicles on palms and especially on volar edges of fingers • Central palm

*

Exogenous

Tinea

Superimposed S. aureus

Irritant contact dermatitis

Allergic contact dermatitis

• KOH • Fungal culture

• Gram stain • Bacterial culture

• Risk factors: occupation, endogenous causes • May show acute and/or chronic changes

• Allergen identified via patch testing • Pruritus • May show acute and/or chronic changes

*Some clinicians view keratotic eczema as a form of psoriasis.

Fig. 15.6 Classification of hand dermatitis. More than one etiology may be present, e.g. atopic dermatitis plus irritant contact dermatitis. FH, family history; PH, personal history. For further details, see ref 68.  

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The establishment of appropriate educational prevention programs is essential. A project in Finland showed a significantly better outcome for employees with occupational hand dermatitis attending an “eczema school”-like clinic run by a specialized nurse compared with an unschooled control group63. Another study found that most occupational skin diseases responded to effective secondary preventive measures, combining employee medical treatment with exposure analysis-based individual and group training in preventive measures64. Education was important in making the employees aware of initial skin changes, such as slight erythema and scaling in the interdigital folds, indicating the need to optimize skin protection and care measures in order to prevent exacerbation and chronicity. The goal of treatment is to restore normal epidermal barrier function. Topical corticosteroids are frequently used, but their efficacy has been controversial, as experimental studies have provided conflicting results65. In one double-blind, vehicle-controlled study, statistically

lower values of erythema and transepidermal water loss were observed in sites irritated by sodium lauryl sulfate after 7 days of treatment with betamethasone valerate66. Systemic corticosteroids, although potentially helpful in reducing acute inflammation, are not useful in the treatment of chronic ICD unless corrective measures are taken to avoid the offending contactants. Narrowband ultraviolet B or photochemotherapy (PUVA) irradiation may be considered for chronic dermatitis that does not respond to any other form of therapy. Hyperkeratotic palmoplantar dermatitis from frictional or chronic ICD or a combination of dermatitis and psoriasis may benefit from the adjunctive use of systemic retinoids such as acitretin and alitretinoin or systemic immunomodulators such as methotrexate, cyclosporine, and possibly targeted (biologic) therapy67. For table on causes of cheilitis in patients who were referred for patch testing plus an additional online figure visit www.expertconsult .com

REFERENCES 1. Keegel T, Moyle M, Dharmage S, et al. The epidemiology of occupational contact dermatitis (1990–2007): a systematic review. Int J Dermatol 2009;48:571–8. 2. Mathias CG, Morrison JH. Occupational skin diseases, United States. Results from the Bureau of Labor Statistics Annual Survey of Occupational Injuries and Illnesses, 1973 through 1984. Arch Dermatol 1988;124:1519–24. 3. American Academy of Dermatology. National Conference on Environmental Hazards to the Skin, Comprehensive Position Statement. 1992. 4. Cohen DE. Occupational dermatoses. In: Harris RL, editor. Patty’s industrial hygiene. 5th ed. New York: John Wiley; 2000. p. 165–210. 5. Luckhaupt SE, Dahlhamer JM, Ward BW, et al. Prevalence of dermatitis in the working population, United States, 2010 National Health Interview Survey. Am J Ind Med 2013;56:625–34. 6. White RP. The dermatergoses or occupational affections of the skin. 4th ed. London: HK Lewis; 1934. 7. Clayton GD, Clayton FE, editors. Patty’s industrial hygiene and toxicology. 4th ed. New York: John Wiley; 1991. 8. Marshall EK, Lynch V, Smith HW. Variations in susceptibility of the skin with dichloroethylsulfide. J Pharmacol Exp Ther 1919;12:291–301. 9. Rietschel RL, Mathias CG, Fowler JF Jr, et al.; North American Contact Dermatitis Group. Relationship of occupation to contact dermatitis: evaluation in patients tested from 1998 to 2000. Am J Contact Dermat 2002;13:170–6. 10. Warshaw EM, Belsito DV, Taylor JS, et al. North American Contact Dermatitis Group patch test results: 2009 to 2010. Dermatitis 2013;24:50–9. 11. Bureau of Labor Statistics. Databases. Tables & Calculators by Subject. Extracted December 20, 2014. . 12. Bureau of Labor Statistics. Industry and illness data, 2009. . 13. Occupational Safety and Health Administration. Occupational Injury and Illness Recording and Reporting Requirements [Proposed Rules]. Fed Regist 2010;75:4728–41. . 14. Lushniak BD. Occupational skin diseases. Prim Care 2000;27:895–916. 15. McDonald JC, Beck MH, Chen Y, Cherry NM. Incidence by occupation and industry of work-related skin diseases in the United Kingdom, 1996–2001. Occup Med (Lond) 2006;56:398–405. 16. Fluhr JW, Bornkessel A, Akengin A, et al. Sequential application of cold and sodium lauryl sulphate decreases irritation and barrier disruption in vivo in humans. Br J Dermatol 2005;152:702–8. 17. Holst R, Moller H. One hundred twin pairs patch tested with primary irritants. Br J Dermatol 1975;93:  145–9. 18. Perry AD, Trafeli JP. Hand dermatitis: review of etiology, diagnosis, and treatment. J Am Board Fam Med 2009;22:325–30. 19. Scharschmidt TC, Man MQ, Hatano Y, et al. Filaggrin deficiency confers a paracellular barrier abnormality

20. 21. 22.

23. 24. 25. 26. 27. 28. 29.

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35.

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that reduces inflammatory thresholds to irritants and haptens. J Allergy Clin Immunol 2009;124:496–506. Behroozy A, Keegel TG. Wet-work exposure: a main risk factor for occupational hand dermatitis. Saf Health Work 2014;5:175–80. Ale I, Maibach H. Irritant contact dermatitis. Rev Environ Health 2014;29:195–206. Darlenski R, Kazandjieva J, Tsankov N, Fluhr JW. Acute irritant threshold correlates with barrier function, skin hydration and contact hypersensitivity in atopic dermatitis and rosacea. Exp Dermatol 2013;22:  752–3. Nosbaum A, Vocanson M, Rozieres A, et al. Allergic and irritant contact dermatitis. Eur J Dermatol 2009;19:325–32. Berardesca E, Distante F. Mechanisms of skin irritations. Curr Probl Dermatol 1995;23:1–8. Iliev D, Elsner P. Clinical irritant contact dermatitis syndromes. Immunol Allergy Clin North Am 1997;17:365–75. Tovar R, Leikin JB. Irritants and corrosives. Emerg Med Clin North Am 2015;33:117–31. Beltrani VS. Occupational dermatoses. Curr Opin Allergy Clin Immunol 2003;3:115–23. Lachapelle JM. Environmental airborne contact dermatoses. Rev Environ Health 2014;29:221–31. Lahti A. Non-immunologic contact urticaria. In: Kanerva L, Elsner P, Wahlberg JE, Maibach HI, editors. Handbook of occupational dermatology. Heidelberg: SpringerVerlag; 2000. p. 221–4. Wang X, Zhang Y, Ni L, et al. A review of treatment strategies for hydrofluoric acid burns: current status and future prospects. Burns 2014;40:1447–57. van der Valk PG, Maibach HI, editors. The irritant contact dermatitis syndrome. Boca Raton: CRC Press; 1995. Mehta RK, Handfield-Jones S, Bracegirdle J, Hall PN. Cement dermatitis and chemical burns. Clin Exp Dermatol 2002;27:347–8. Boman AS, Wahlberg JE. Irritants – organic solvents. In: Chew AL, Maibach HI, editors. Irritant dermatitis. Berlin: Springer-Verlag; 2006. p. 269–77. Schliemann S, Schmidt C, Elsner P. Tandem repeated application of organic solvents and sodium lauryl sulphate enhances cumulative skin irritation. Skin Pharmacol Physiol 2014;27:158–63. Sato A, Obata K, Ikeda Y, et al. Evaluation of human skin irritation by carboxylic acids, alcohols, esters and aldehydes, with nitrocellulose-replica method and closed patch testing. Contact Dermatitis 1996;34:12–16. de Haan P, Meester HM, Bruynzeel DP. Irritancy of alcohols. In: van der Valk PG, Maibach HI, editors. The irritant contact dermatitis syndrome. Boca Raton: CRC Press; 1995. p. 65–70. Brinkmann I, Muller-Goymann CC. Role of isopropyl myristate, isopropyl alcohol and a combination of both in hydrocortisone permeation across the human stratum corneum. Skin Pharmacol Appl Skin Physiol 2003;16:393–404. Warshaw EM, Botto NC, Maibach HI, et al. Positive patch-test reactions to propylene glycol: a retrospective cross-sectional analysis from the North American Contact Dermatitis Group, 1996 to 2006. Dermatitis 2009;20:14–20.

39. Johnson W Jr, Cosmetic Ingredient Review Expert Panel. Final report on the safety assessment of propylene glycol and polypropylene glycols. J Am Coll Toxicol 1994;13:437–91. 40. Effendy I, Maibach HI. Detergent and skin irritation. Clin Dermatol 1996;14:15–21. 41. Moreau L, Sasseville D. Allergic contact dermatitis from cocamidopropyl betaine, cocamidoamine, 3-(dimethylamino)propylamine, and oleamidopropyl dimethylamine: co-reactions or cross-reactions? Dermatitis 2004;15:146–9. 42. Turkoglu M, Sakr A. Evaluation of irritation potential of surfactant mixtures. Int J Cosmet Sci 1999;21:371–82. 43. Warshaw EM, Schram SE, Maibach HI, et al. Occupationrelated contact dermatitis in North American health care workers referred for patch testing: cross-sectional data, 1998 to 2004. Dermatitis 2008;19:261–74. 44. Andersen FA. Final report on the safety assessment of cocamide MEA. Int J Toxicol 1999;18:9–16. 45. Timmer C. Disinfectants. In: van der Valk PG, Maibach HI, editors. The irritant contact dermatitis syndrome. Boca Raton: CRC Press; 1995. p. 77–94. 46. Basketter DA, Marriott M, Gilmour NJ, White IR. Strong irritants masquerading as skin allergens: the case of benzalkonium chloride. Contact Dermatitis 2004;50:213–17. 47. Davis MD, Scalf LA, Yiannias JA, et al. Changing trends and allergens in the patch test standard series: a Mayo Clinic 5-year retrospective review, January 1, 2001, through December 31, 2005. Arch Dermatol 2008;144:67–72. 48. Saap L, Fahim S, Arsenault E, et al. Contact sensitivity in patients with leg ulcerations: a North American study. Arch Dermatol 2004;140:1241–6. 49. Kanerva L, Jolanki R, Alanko K, Estlander T. Patch-test reactions to plastic and glue allergens. Acta Derm Venereol 1999;79:296–300. 50. Brancaccio RR, Alvarez MS. Contact allergy to food. Dermatol Ther 2004;17:302–13. 51. Xu S, Heller M, Wu PA, Nambudiri VE. Chemical burn caused by topical application of garlic under occlusion. Dermatol Online J 2014;20:21261. 52. Tsai TF, Maibach HI. How irritant is water? An overview. Contact Dermatitis 1999;41:311–14. 53. Smith WJ, Jacob SE. The role of allergic contact dermatitis in diaper dermatitis. Pediatr Dermatol 2009;26:369–70. 54. Freeman S, Stephens R. Cheilitis: analysis of 75 cases referred to a contact dermatitis clinic. Am J Contact Dermat 1999;10:198–200. 55. Zug KA, Kornik R, Belsito DV, et al.; North American Contact Dermatitis Group. Patch-testing North American lip dermatitis patients: data from the North American Contact Dermatitis Group, 2001 to 2004. Dermatitis 2008;19:202–8. 56. Watkins SA, Maibach HI. The hardening phenomenon in irritant contact dermatitis: an interpretative update. Contact Dermatitis 2009;60:123–30. 57. Cahill J, Keegel T, Nixon R. The prognosis of occupational contact dermatitis in 2004. Contact Dermatitis 2004;51:219–26. 58. Wigger-Allberti W, Elsner P. Prevention of irritant contact dermatitis – new aspects. Immunol Allergy Clin North Am 1997;17:443–50.

Online only content

CHAPTER



CAUSES OF CHEILITIS IN PATIENTS REFERRED FOR PATCH TESTING Irritant contact dermatitis Most frequent cause: lip licking

36%

Allergic contact dermatitis Most common allergens (% of patients in a second series55): fragrance mix, 30%; Myroxilon pereirae (balsam of Peru), 23%; nickel, 22%; gold, 13%; neomycin, 12%; cobalt, 10%; propylene glycol, 8%; lanolin, 7%; cinnamic aldehyde, 7%; bacitracin, 5%; benzophenone, 5%; methyldibromoglutaronitrile/phenoxyethanol, 5%; tea tree oil, 5%; budesonide, 5%

25%

Atopic dermatitis

19%

Eczema (cause unknown)

9%

Non-eczematous causes (angioedema, photosensitivity, psoriasis, erosive candidal cheilitis, functional)

9%

Seborrheic dermatitis

1%

15 Irritant Contact Dermatitis

eFig. 15.1 Moderately severe irritant contact dermatitis of the hands due to chronic exposure to disinfecting solutions and antiseptics. The results of patch testing, latex challenge testing, and RAST testing were negative in this practicing dentist.

eTable 15.1 Causes of cheilitis in patients who were referred for patch testing (n = 75). Adapted from refs 54 and 55.  

272.e1

63. Kalimo K, Kautiainen H, Niskanen T, Niemi L. “Eczema school” to improve compliance in an occupational dermatology clinic. Contact Dermatitis 1999;41:315–19. 64. Bauer A, Kelterer D, Stadeler M, et al. The prevention of occupational hand dermatitis in bakers, confectioners and employees in the catering trades. Preliminary results of a skin prevention program. Contact Dermatitis 2001;44:85–8. 65. van der Valk PG, Maibach HI. Do topical corticosteroids modulate skin irritation in human beings? Assessment by transepidermal water loss and visual scoring. J Am Acad Dermatol 1989;21:519–22. 66. Ramsing DW, Agner T. Efficacy of topical corticosteroids on irritant skin reactions. Contact Dermatitis 1995;32:293–7.

67. Cohen DE, Heidary N. Treatment of irritant and allergic contact dermatitis. Dermatol Ther 2004;17:334–40. 68. Johansen JD, Hald M, Andersen BL, et al. Classification of hand eczema: clinical and aetiological types. Based on the guideline of the Danish Contact Dermatitis Group. Contact Dermatitis 2011;65:13–21. 69. Seidenari S, Giusti F, Pepe P, Mantovani L. Contact sensitization in 1094 children undergoing patch testing over a 7-year period. Pediatr Dermatol 2005;22:  1–5. 70. Pratt MD, Belsito DV, DeLeo VA, et al. North American Contact Dermatitis Group patch-test results, 2001–2002 study period. Dermatitis 2004;15:176–83.

CHAPTER

15 Irritant Contact Dermatitis

59. Korinth G, Geh S, Schaller KH, Drexler H. In vitro evaluation of the efficacy of skin barrier creams and protective gloves on percutaneous absorption of industrial solvents. Int Arch Occup Environ Health 2003;76:382–6. 60. Berndt U, Wigger-Alberti W, Gabard B, Elsner P. Efficacy of a barrier cream and its vehicle as protective measures against occupational irritant contact dermatitis. Contact Dermatitis 2000;42:77–80. 61. Anderson PC, Dinulos JG. Are the new moisturizers more effective? Curr Opin Pediatr 2009;21:  486–90. 62. Draelos ZD. An evaluation of prescription device moisturizers. J Cosmet Dermatol 2009;8:  40–3.

273

SECTION 3 PAPULOSQUAMOUS AND ECZEMATOUS DERMATOSES

16 

Occupational Dermatoses S. Mark Wilkinson

INTRODUCTION Given the diverse occupations that people pursue, there are thousands of chemicals and other potentially noxious insults that can impinge on the skin in many different ways1. Traditionally, the types of hazardous exposure are categorized as: mechanical – friction, pressure, vibration, mechanical disruption chemical – elements and chemical compounds (organic, inorganic, and proteins) physical – heat, cold, radiation (UV and ionizing) biological – organisms including viruses, bacteria, fungi, and parasites. The types of dermatoses induced by exposure to these noxious occupational hazards can be grouped as outlined in Table 16.1. This chapter differs from most of the others in that it deals with diverse conditions, many of which are also covered in detail in specific chapters.

• • • •

HISTORY Occupational disease has existed for thousands of years. Hippocrates (c460–377 BC) hypothesized that there were environmental causes of disease. One of the first written descriptions of occupational dermatoses was by the Italian Bernardino Ramazzini (1633–1714). He described diseases associated with a variety of occupations, including different types of ulcerations in fresh- and salt-water fishermen. During their long-distance voyages in the sixteenth century, Drake and Magellan experienced significant problems from scurvy due to the lack of vitamin C from fresh fruit and vegetables. In 1747, James Lind performed the first controlled trial demonstrating the protective effects of citrus fruits against scurvy. In 1795, the British Navy included lemon juice in ships’ stores as one of the earliest forms of prevention for an occupational skin disease.

EPIDEMIOLOGY

274

In a UK household survey, a rate of occupational dermatosis of 15/10 000 for those who had ever been employed demonstrates the high frequency of affected individuals; in comparison, a rate of 5.1/10 000 has been reported by physicians in Denmark and Finland, where occupational disease is notifiable. Of the most common physical illnesses due to occupation, skin diseases (23%) rank second, after musculoskeletal disorders (45%)2. In the US in 2010 it was estimated that for private industry, the annual cost of occupational skin disease due to lost productivity, medical care, and disability payments was US$1.2 billion3 and this accounted for 10.5% of the cost attributed to skin disorders from all causes. The average cost per claim for occupational dermatitis in the 1990s was US$3550 and the period of disability was 24 days4. More recently, the German statutory health insurance companies estimated the cost of hand eczema to be €9000 per case with an annual cost of €2,1281. Based upon classification systems such as the International Standard Classification of Occupations (ISCO), the distribution of occupational skin disease reported by industry varies with the specialty of the physician (Fig. 16.1)5. The difference in incidence of neoplasia, as reported by dermatologists compared to occupational physicians, reflects the delay between exposure and development of disease and the fact that the majority of workers have left employment when the cancer develops. Differences in reporting also reflect the distribution of occupational health departments in industry: vehicle assembly, glass and ceramic workers as well as scientific technicians are often seen by occupational physicians, whereas hairdressers, for example, are seen primarily by

dermatologists. Over the past decade, there has been a consistent decline in the reported incidence of occupational dermatoses both in the US and in Europe6.

THE OCCUPATIONAL DERMATOSES Contact Dermatitis Synonym:  ■ Contact eczema

Key features ■ The most common causes of occupational allergic contact dermatitis are (in order of decreasing frequency): rubber, nickel, epoxy and other resins, and aromatic amines ■ The most common causes of occupational irritant contact dermatitis are (in order of decreasing frequency): soaps, wet work, petroleum products, solvents, and cutting oils and coolants

Introduction Contact dermatitis accounts for the majority of occupational skin disease that predominantly affects the hands. The prevalence of hand dermatitis in the population has been estimated at approximately 0.5%, rising in some studies to 10% when an industrial workforce has been examined. While most individuals will remain at work, over half will change jobs and a large proportion will be absent from work for a month or more.

History In the first century AD, Pliny the Younger recorded dermatitis in individuals after they cut down pine trees, presumably representing allergic contact dermatitis to colophony in pine resin. Ramazzini in his 1700 treatise described irritant contact dermatitis of the hands and forearms in soap and laundry workers.

Epidemiology An age-related increase in rates of occupational dermatitis is seen in men, but in women the peak age of incidence is 16–29 years with a decline thereafter. However, a comparison of rates by age within specific occupational groups suggests that the sexes follow a similar pattern. Among chefs and cleaners of either sex, higher rates are seen in young workers, whereas rates among machine tool operators increase with age, reflecting the type of occupational exposure. Materials giving rise to contact dermatitis in the UK are shown in Figure 16.2, and the highest risk UK occupations in Figure 16.37. In contrast to the UK, in Finland and the US, the highest rate of skin disease is among agricultural workers.

Pathogenesis The initial events of both irritant and allergic contact dermatitis (see Chs 14 & 15) are similar. Depending upon the severity of the insult, the tissue response can reach a level at which it becomes clinically apparent as cutaneous inflammation (Fig. 16.4). If tissue perturbation is maintained via repeated insults, then chronic dermatitis ensues, while an early withdrawal of the insult may result in healing.

Occupational dermatoses comprise any skin disease in which occupational exposure is a major causal or contributory factor. After psychological and musculoskeletal disorders, the skin is one of the most common organ systems affected by occupational disease. Contact dermatitis is the most common occupational dermatosis and it predominantly affects exposed sites, especially the hands.

occupational dermatoses, contact dermatitis, allergic contact dermatitis, irritant contact dermatitis, contact urticarial, chloracne, occupational acne, vibration white finger

CHAPTER

16 Occupational Dermatoses

ABSTRACT

non-print metadata KEYWORDS:

274.e1

CHAPTER

CAUSES OF OCCUPATIONAL CONTACT DERMATITIS IN THE UK (%)

Contact dermatitis

Soaps and cleaners

Irritant - chemically induced - photoinduced - mechanical • Allergic •

8

Wet work

15

6

Personal protective equipment

2

Rubber 10

9

Nickel Petroleum products

Chemical burn

Solvents and alcohols

Contact urticaria

8

Cancer Sunlight/UV-induced • Ionizing radiation-induced • Chemically induced

11

Cutting oils and coolants Epoxy and other resins

5



16 Occupational Dermatoses

CLINICAL CLASSIFICATION OF OCCUPATIONAL DERMATOSES

8

Aldehydes 2

16

Non-epoxy glues and paints Other

Follicular disease Acne Folliculitis • Chloracne •

Fig. 16.2 Causes of occupational contact dermatitis in the UK (%).





Autoimmune connective tissue disease Systemic sclerosis (silica; see Ch. 43) Scleroderma-like (vinyl chloride, organic solvents; see Ch. 43) • Vibration-induced • •

Clinical features

Pigmentary disorders Hypopigmentation (see Ch. 66) • Hyperpigmentation (see Ch. 67) •

Foreign body reactions (see Ch. 94) Infection Viral Bacterial • Fungal • Parasitic • •

Table 16.1 Clinical classification of occupational dermatoses.  



RELATIVE FREQUENCY OF REPORTED OCCUPATIONAL SKIN DISEASE HIGHLIGHTING DIFFERENCES BY MEDICAL SPECIALTY Reported by dermatologists

Reported by occupational physicians 1% 8% 2% 3% 1%

2% 21%

3% 1% 1% 1% 1% 3%

71%

83%

Contact dermatitis

Contact urticaria

Folliculitis/acne

Infective

Mechanical

Nail

Neoplasia

Other dermatoses

Fig. 16.1 Relative frequency of reported occupational skin disease highlighting differences by medical specialty. Courtesy, The Health and Occupation  

Research (THOR) network of the Centre for Occupational and Environmental Health (COEH) of the University of Manchester, UK.

Contact dermatitis, both allergic and irritant, is morphologically indistinguishable from endogenous eczema (Fig. 16.5). Although most cases of dermatitis will result from direct exposure that leads to localized dermatitis, there are other routes of absorption that can lead to dermatitis. In the case of solvents, inhalation may result in widespread dermatitis, often with systemic involvement. Diagnosis of an occupational cause is dependent on a thorough dermatologic and occupational history (Table 16.2), combined with examination of the entire skin. Material safety data sheets (MSDS) provide a guide to the nature of materials handled at work. They list the chemical composition and the hazards associated with the product, e.g. irritant, corrosive, contains a sensitizer. However, total reliance should not be placed on the MSDS as they may not list all ingredients of relevance, and communication with the manufacturer may prove helpful. When occupational dermatitis is suspected but a cause cannot be established from the history, a workplace visit may prove invaluable and may also elucidate the source of an allergen previously detected via patch testing. Although the primary site is usually the hands, spread to adjacent areas of skin (even without primary contact) is relatively common. Spread to distant sites, such as the face and feet, is more frequently seen in allergic contact dermatitis than in irritant contact dermatitis. Notably, airborne allergens, e.g. from paint sprayers, can lead to a pattern of dermatitis that suggests this type of exposure. Covered areas such as the trunk and feet are unusual sites of onset of disease. Improvement of the dermatitis during periods away from work is an important clue to an occupational cause, but it should be remembered that endogenous eczema may also be exacerbated by workplace exposures. As the dermatitis becomes chronic, the relationship between work and exacer­ bations becomes less clear-cut.

Allergic contact dermatitis (see Ch. 14) Patch testing is essential for establishing the diagnosis and should be performed in any individual with a dermatitis that may be work-related or for whom a change of job is being contemplated. Testing with work materials is essential (Table 16.3) if contact allergy is not to be missed, as not all allergens are commercially available and the MSDS may not disclose all relevant ingredients. A guide to testing 4350 chemicals and an update have been published8,9. When a reaction occurs to an unknown substance, the use of a dilutional series and the testing of approximately 20 controls can confirm that the reaction is allergic rather than irritant. In an extensive surveillance report, the most common causes of occupational allergic contact dermatitis were rubber (23.4% of cases), nickel (18.2%), epoxy and other resins (15.6%), aromatic amines (8.6%), chromate (8.1%), fragrances and cosmetics (8.0%), and preservatives (7.3%)7.

275

SECTION

3

Papulosquamous and Eczematous Dermatoses

REPORTED CASES AND INCIDENCE RATES OF CONTACT DERMATITIS BY OCCUPATION

Health and social work Manufacturing Other service activities Hotels and restaurants

Estimated Actual

Construction Wholesale and retail trade Education Transport, storage and communication Agriculture, hunting, forestry and fishing Mining and quarrying 0

1000

2000

A

3000

4000

5000

6000

Number of cases Other service activities Hotels and restaurants Health and social work Manufacturing

Estimated

Agriculture, hunting, forestry and fishing Construction Mining and quarrying Wholesale and retail trade Transport, storage and communication Education 0

2

B

4

6

8

10

12

14

16

Incidence rates (per 100 000 employed)

Fig. 16.3 Reported cases and incidence rates of contact dermatitis by occupation. A Actual and estimated cases of contact dermatitis, with crude data adjusted for sampling bias. B Contact dermatitis incidence rates (per 100 000 employed); crude data were adjusted for the size of the labor force by utilizing the labor force survey data (2002–2009) as the denominator. Courtesy, The Health and Occupation Research (THOR) network of the Centre for Occupational and Environmental Health (COEH) of the University of  

Manchester, UK.

CHRONIC IRRITANT DERMATITIS AFTER REPEATED INSULTS

Dermatitis

Dermatitis present Tissue response present but no dermatitis

Threshold for appearance of dermatitis

Irritant insults

Fig. 16.4 Chronic irritant dermatitis after repeated insults. Initial subclinical response to tissue perturbation by an irritant becomes manifest as chronic irritant dermatitis after repeated insults. Each arrow represents an irritant insult of different intensity.  

276

Fig. 16.5 Hand of a builder who presented with a dyshidrotic (pompholyx) pattern of eczema. Investigation demonstrated allergic contact dermatitis to chromate found in cement and contact urticaria to latex in the gloves he was using for hand protection.  

CHAPTER

Primary (initial) site of disease • Time course

Materials handled • Labels and material safety data sheets (MSDS) • Other persons affected Protection provided



Previous skin disease or history of atopy

SUGGESTED CONCENTRATIONS FOR PATCH TESTING SELECTED WORK MATERIALS

In 90%, it is the hands Is this consistent with work exposure as a cause? Does time off result in improvement?

Sample

Dilution

Occupation(s)

Personal care products • Leave on

As is

Hairdresser/ beautician Hairdresser/ beautician

Irritant, corrosive, or sensitizing

Plants‡ Bulb, leaf, flower

Suggests an irritant contact dermatitis Is it appropriate? Is there an allergy to personal protective equipment? Is this a recurrence of a previous problem?

Known allergies

Is there unrecognized exposure?

Treatment

May cause allergic contact dermatitis

Hobbies

May be a more likely cause than occupation

Table 16.2 Points to consider when taking an occupational history.  



Irritant contact dermatitis (see Ch. 15)

Most occupational dermatitis results from repeated exposures to weak irritants which cause cumulative damage to the skin (see Fig. 16.4). On the other hand, strong irritants are usually recognized and protection provided. Employees with previous atopic dermatitis, especially with hand involvement, are particularly at risk, as are those with mutations in the filaggrin gene10. Soaps (22% of cases), wet work (20%), petroleum products (9%), solvents (8%), and cutting oils and coolants (8%) are the most frequently cited causes of occupational irritant dermatitis7.

Chemical burns

A chemical burn is an acute irritant reaction in which the injury to the skin is irreversible and cell death occurs. It can occur following a single exposure. Initial symptoms consist of burning and stinging with progressive development of erythema, blisters, erosions and ulceration. Symptoms usually develop in close association with the exposure, but some chemicals, such as phenols and weak hydrofluoric acid, can have a delayed onset. Common occupational causes include11: strong acids: e.g. sulfuric, nitric, hydrochloric, chromic. Most coagulate skin proteins and as a result form a barrier that impedes further penetration. Hydrofluoric acid differs in that it causes a liquefactive necrosis: penetration, even down to bone, can continue for several days after exposure. Pain, which can last several days, is typical of hydrofluoric acid and other fluorides. If more than 1% of the body surface area is affected, systemic toxicity can develop strong alkalis: e.g. sodium, calcium, and potassium hydroxides; wet cement (Fig. 16.6); sodium and potassium cyanides. Degradation of lipids and saponification of the resulting fatty acids form soaps which aid the penetration of alkalis deeper into the skin. As a consequence, damage is more severe than with most acids (apart from hydrofluoric acid) and pain is also a feature organic and inorganic chemicals: e.g. dichromates; arsenates; phenolic compounds. Phenols and unhardened phenolic resins easily penetrate the skin. Nerve damage may cause anesthesia, but rarely in the absence of visible skin damage. Vasoconstriction may contribute to the necrosis that develops and, following systemic absorption, shock and renal damage may ensue solvents and gases: e.g. acrylonitrile; ethylene oxide; carbon disulfide; mustine. Ethylene oxide gas is used to sterilize medical









Wash off



1–5% aqueous or open† As is

Gardener/florist Agriculture/ vegetable processing

Woods – sawdust

As is/10% petrolatum

Joiner/woodworker

Dyes (clothing) Cloth

1% petrolatum As is – moistened

Textiles



Foods§

As is

Catering/chef

Glue

10% aqueous/ petrolatum 1% petrolatum

Various

Methacrylate monomer • Acrylate monomer • Epoxy resin • Epoxy hardener •

0.1% petrolatum 1% petrolatum 0.1% petrolatum

16 Occupational Dermatoses

POINTS TO CONSIDER WHEN TAKING AN OCCUPATIONAL HISTORY

Dentist/orthopedic surgeon Painter – 2-part paints

Ink • UV cured

As is 1% petrolatum

Printing

Oil • Cutting (coolant) – water miscible • Lubricant – immiscible with water

10% aqueous or open As is

Metal machining

Paint

10% aqueous/ petrolatum

Painter/decorator

Photographic chemicals

10% aqueous

Photographer

Solvents/thinners

10% acetone

Various

Various-use machinery

†Open test: apply the substance to a 3 cm diameter area of skin and allow to dry. Read as

normal but do not occlude.

‡Do not test unless the plant has been identified and is recognized not to be irritant. There

may be a risk of sensitization.

§Prick testing is essential to exclude contact urticaria.

Table 16.3 Suggested concentrations for patch testing selected work materials. This is a guide only: the final decision must always be made in light of the information available in relation to the suspected material. Tests are usually performed on the upper back.  

instruments, textiles and plastic materials, and it can remain on these items for several days if not allowed to evaporate off prior to use. The possibility of exposure may therefore not be obvious.

Fiberglass dermatitis

Glass fibers are subdivided into various types, depending on fiber diameter, and are used for their insulating (thermal, acoustic, and electrical), strengthening, and filtering abilities. They are chemically inert and the mechanism of skin injury is via direct penetration, which is directly proportional to the diameter (>3.5 microns) of the fiber and inversely proportional to its length. Histologically, eczematous changes including spongiosis are seen. Pruritus and tingling are the usual initial symptoms of fiberglass dermatitis. Subsequently, erythematous papules develop (often with follicular accentuation), either on exposed areas when there is airborne exposure or on the forearms when there is contamination of a work surface (Fig. 16.7)12. Contamination of clothing leads to involvement

277

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3

of sites where there is close contact with the skin, particularly flexural areas. Paronychia is common, and airborne exposure may also cause burning eyes, sore throat, and cough. The diagnosis is often based on clinical findings, but can be confirmed by detecting the glass fibers either by tape stripping affected skin or by examining skin scrapings in 20% potassium hydroxide. The dermatitis resolves rapidly after cessation of exposure. In most individuals, hardening occurs and symptoms resolve over a few weeks despite continued exposure; of note, the use of resins to bind glass fibers can result in an allergic contact dermatitis.

Phototoxic eruptions (see Ch. 87)

Most occupational photosensitivity is phototoxic in nature and resolves with hyperpigmentation. The most common scenario consists of outdoor workers exposed to plant-derived psoralens. This may result from direct contact or be airborne as in “strimmer” dermatitis when plant sap splatters the body of a worker inadequately protected when cutting down plants (see Ch. 17). Coal tar and its products, including creosote, can cause a reaction known as tar/pitch smarts. A burning or stinging sensation develops after as little as 15 minutes of sun exposure.

Fig. 16.6 Cement burns. Ulcerations on the fingertips of a construction worker exposed to wet cement. Courtesy, PJ Coenraads, MD.  

Mechanical

Occupational marks are usually areas of lichenification or calluses and corns that develop at sites of friction and are specific to a particular job (Fig. 16.8). Mechanical injury to the skin is also thought to cause dermatitis analogous to irritant chemical damage. It may result in a keratotic hand dermatitis or post-traumatic eczema (Koebner phenomenon).

Pathology The histologic features of allergic contact dermatitis and irritant contact dermatitis are discussed in Chapters 14 and 15, respectively.

Differential diagnosis The etiology of occupational dermatitis is frequently multifactorial and coexisting endogenous eczema may contribute to the clinical appearance. Tinea manuum may resemble hand dermatitis, especially following treatment with topical corticosteroids, and scabies infestation of the interdigital spaces can simulate irritant dermatitis. Rarely, blistering of the dorsal hands due to porphyria cutanea tarda is misconstrued as contact dermatitis. Psoriasis frequently affects the palms, resulting in keratotic plaques, sometimes with fissures. This can be difficult to distinguish from dermatitis when there are no lesions elsewhere. Furthermore, psoriasis may be exacerbated by repeated, work-related trauma leading to Koebner

Fig. 16.7 Fiberglass dermatitis. Multiple pruritic pink papules at the site of exposure.  

Fig. 16.8 The effects of mechanical injury to the skin. Both friction and pressure lead to callus formation. Adapted from Adams RM. Occupational Skin Disease,  

THE EFFECTS OF MECHANICAL INJURY TO THE SKIN

3rd edn. Philadelphia: WB Saunders, 1999:36.

Friction Repeated rubbing or scratching

Pressure

Vibration

Pounding

Friction

Penetration

Sudden trauma

Callus

Lichenification

278

Hemorrhage Melanin

White fingers, sclerodactyly

Blister

Tattoo granulomas

Treatment

reaction ■ Protein contact dermatitis

Key features ■ Pruritus and wheal-and-flare reaction ■ Develops within 60 minutes of exposure and resolves within 24 hours ■ The protein content of latex rubber is responsible for the associated contact urticaria ■ In suspected cases of latex-induced contact urticaria, the specific IgE test may be negative, requiring prick testing with a commercial latex extract and a usage test

Introduction Contact urticaria has been reported following exposure to a wide range of substances16. With regard to occupational skin disease, plant- and animal-derived proteins are recognized causes, especially among food handlers and agricultural, animal laboratory, and veterinary workers. In extreme circumstances, systemic symptoms (i.e. rhinoconjunctivitis, bronchospasm and anaphylaxis) may be seen. With the introduction of universal precautions in the 1980s and increased use of natural rubber gloves, latex protein emerged as an important cause of contact urticaria, particularly in the healthcare setting.

GUIDELINES AIMED AT PREVENTING CONTACT DERMATITIS

Advice

Explanation

Do not wear rings



Chemicals/water accumulate underneath

Hand washing



Wear gloves



Use lukewarm water and dry thoroughly



For wet work



For as short a time period as possible • With a cotton inner liner if prolonged exposure • That are dry, clean and intact •

Use moisturizer HIERARCHY OF OCCUPATIONAL DISEASE PREVENTION Avoid disease onset • Engineering measures • Chemical substitution • Workforce education in skin care

Frequently throughout the day • To the whole hand •

Occlusion of chemicals inside gloves increases irritancy



Encourages barrier repair



Use alcohol gel



For antisepsis

Tertiary prevention

Treatment of active disease • Avoidance measures • Medical management

Follow the same advice at home





Less irritating than soaps or antiseptic detergents Domestic exposures are additive



Table 16.5 Guidelines aimed at preventing contact dermatitis. ACD, allergic contact dermatitis.  



Wet work is the major risk factor for contact dermatitis • Glove occlusion also damages the skin • Liners absorb moisture and reduce irritation

That is fragrancefree and preservative-free



Detect presymptomatic or early disease • Health surveillance

Table 16.4 Hierarchy of occupational disease prevention.

Skin damage from detergent is reduced at a low temperature • Dermatitis often begins at sites that are missed, e.g. fingerwebs

Need to include web spaces • Prevents sensitization and development of ACD to common allergens

Secondary prevention



16

Synonyms:  ■ Contact urticaria syndrome ■ Immediate contact

Occupational disease prevention is divided into primary, secondary, and tertiary measures (Table 16.4)13. During pre-employment screening, a history of severe childhood atopic dermatitis, particularly with hand involvement, indicates an individual at risk of developing dermatitis from exposure to irritants. Employment in a “dry” job should be recommended. In the workplace, the use of protective equipment and skin care preparations should be encouraged (Table 16.5). Use of protective creams prior to exposure may aid in the subsequent removal of irritants and application of emollients throughout the day may prevent the development of dermatitis. Education of the workforce in skin care has been shown to reduce the development of skin disease14. Treatment is discussed in Chapters 14 and 15. The most important aspect, however, is avoidance of the cause. Ideally, a change in the production process may avoid the need for exposure, but this may not be feasible. A practical compromise is the use of personal protective equipment and/or substitution of a particular chemical. Advice on appropriate glove type may be found on the MSDS or from glove manufacturers (e.g. www.ansellpro.com). Gloves need to be replaced regularly and each particular type of glove will have a penetration time for any given chemical. For example, acrylate glues (orthopedic surgeons, dentists), the hair dye para-phenylenediamine (hairdressers), and “acid perm” solutions containing glycerol monothioglycolate (hairdressers) rapidly penetrate latex gloves. Initial treatment of chemical burns requires irrigation with large volumes of water. When the chemical is insoluble in water, a soap solution may be used instead. High pressures should not be used, in order to avoid splashing other areas of the body or bystanders with the corrosive material. For some chemicals, specific antidotes can then be used, e.g. 2.5% calcium gluconate gel for hydrofluoric acid; reduction of pain is a sign of successful treatment. When there is a risk of toxicity from systemic absorption, as with chromic acid, early debridement of necrotic areas reduces blood levels. Several chemicals (e.g. hydrofluoric acid, phenolic compounds, chromic acid, gasoline) carry a significant risk of systemic toxicity even when the area of skin involved is small (approximately 1% of body surface area). In these instances, regular monitoring of blood, liver and kidney function plus appropriate supportive treatment (e.g. dialysis) is required. When the chemical is also a sensitizer, allergic contact dermatitis may subsequently appear on re-exposure to non-irritant concentrations, as burns and irritant dermatitis promote sensitization. Once it has developed, the outlook for occupational contact dermatitis is poor15, and patients frequently have persistent disease despite interventions. While a change of occupation is associated with a better prognosis, the possibility exists that the new workplace will have the same or similar chemical exposures. Prognosis is also worse when there is a contact allergy (delayed or immediate) to a chemical that is present in the domestic as well as the industrial environment. Some individuals (~10%) have persistent disease in the absence of any obvious cause, for which the term “persistent post-occupational dermatitis” has been coined.

Primary prevention

CHAPTER

Contact Urticaria

Occupational Dermatoses

phenomena. Nail involvement and plaques over the interphalangeal joints are helpful clues.



279

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Papulosquamous and Eczematous Dermatoses

3

History Contact urticaria was first defined as a clinical entity during the 1970s but it had long been recognized.

Epidemiology Based on official statistics, occupational causes of contact urticaria have been well classified in Finland1. The relative frequency of various urticants is shown in Figure 16.9 and reflects the high prevalence of reactions in the farming community. The reactions to cow dander are probably the result of high exposure, as cattle are kept indoors from September to May/June. The prevalence varied from 140/100 000 for bakers to 2.1/100 000 for shop assistants and was higher in women, irrespective of occupation. Relative risk by occupation is shown in Figure 16.10. The incidence of contact urticaria declines with age, and approximately 30% of individuals have coexistent contact dermatitis.

Pathogenesis Contact urticaria is classified as either irritant/nonimmune-mediated or allergic/immune-mediated. An additional category includes those cases in which the mechanism is uncertain, exemplified by ammonium persulfate in hairdressing. The mechanism of nonimmune contact urticaria is not well defined but involves the release of vasoactive mediators. It is inhibited by nonsteroidal anti-inflammatory drugs but not by antihistamines, suggesting a role for prostaglandins. Symptoms develop in the majority of those exposed and are most often due to simple chemicals, e.g. sorbic acid. Immunologic contact urticaria is mediated by allergen-specific IgE (see Ch. 18). Binding of antigen, usually protein, to mast cells in a previously sensitized individual results in degranulation and release of

OCCUPATIONAL CONTACT URTICANTS IN FINLAND

14 2 2

1

Cow dander Natural rubber latex 44

11

Flour, grain and feed Food Decorative plants Industrial enzymes Other

26

Fig. 16.9 Occupational contact urticants in Finland. Relative frequencies are represented. Reproduced from Kanerva L, Elsner P, Wahlberg JE, et al. Handbook of Occupational  

mast cell mediators, including histamine. Atopic individuals are at greater risk of this type of reaction.

Clinical features Signs and symptoms range from nonspecific, i.e. pruritus, tingling and burning, to more typical urticaria with a wheal and flare, usually noted within 30 minutes of exposure at the site of contact. Resolution occurs within hours. Individuals with immunologically mediated urticaria17 may also experience systemic symptoms with generalized urticaria, rhinoconjunctivitis, orolaryngeal and gastrointestinal symptoms, asthma, and even anaphylaxis.

Foods

One of the more common causes of contact urticaria is foodstuffs, which can provoke either orolaryngeal symptoms when ingested or hand symptoms when handled (e.g. fish processors, slaughterhouse workers, individuals in the catering industry). There is a diverse range of responsible foods, including meats, fish, eggs, fruits, vegetables and flour, as well as associated enzymes such as α-amylase (found as an additive in flour). In Scandinavia, a strong association is seen between the incidence of birch pollen allergy and contact urticaria to fruits and vegetables, due to the presence of similar peptides. Birch pollen is a common aeroallergen in Scandinavia, whereas in the UK the most common aeroallergens are the house dust mite and grass pollen; this may explain why there are fewer reports of contact urticaria in food handlers in the UK. If contact urticaria is confirmed, there are recognized cross-reactions between the various foodstuffs (Table 16.6)18.

Latex

Contact urticaria to latex was first described in 1979. The term “latex” defines an aqueous dispersion of a rubber. The rubber obtained from latex by drying or coagulation is termed “latex rubber”. Natural latex is derived from the sap of the tree Hevea brasiliensis. Natural latex contains polyisoprene (30–40%) together with a variety of other plant chemicals, including proteins (2%). After 1985, the demand for latex gloves for medical and dental use to prevent the transmission of infectious agents19 more than doubled. Paralleling this rise in usage were reports of type I allergy to latex gloves. Occupational latex contact urticaria occurs more frequently in women, atopic patients (particularly those with hand eczema), and workers frequently exposed to latex gloves (e.g. hairdressers). Rates ranging from 3% to 16% have been reported among healthcare workers. Most problems arise from items made by coating a mold with concentrated liquid latex, e.g. gloves, balloons, condoms. Nowadays, however, many gloves are manufactured by methods designed to leave lower levels of protein allergen in the final product. Latex that is allowed to dry before processing by compression molding or extrusion (e.g. syringe plungers, vial stoppers) causes fewer problems, due to degradation of the protein allergen during the manufacturing process. When

Dermatology. Berlin: Springer Verlag, 2000.

POTENTIAL CROSS-REACTIONS BETWEEN CAUSES OF CONTACT URTICARIA RELATIVE RISK OF DEVELOPING CONTACT URTICARIA BY OCCUPATION

Food/natural product

Cross-reactions

Fruit (kiwi, avocado, banana)

10

Latex

Latex

35

Fruits (e.g. kiwi, avocado, banana)

A shellfish (e.g. crab)

75

Other shellfish (e.g. prawn, lobster)

Chefs

A fish (e.g. salmon)

50

Other fish (e.g. swordfish, sole)

Other medical personnel

A grain (e.g. barley)

20

Other grains (e.g. wheat, rye)

Nurses Restaurant workers Laboratory assistants Painters

Plastics workers

A legume (e.g. peanut)

Butchers Agricultural workers Bakers 0

5

10

15

5

Other legumes (e.g. peas, beans, lentils)

Peach

55

Other Rosaceae fruit (e.g. apple, pear, cherry, plum)

Melon

90

Other fruits (e.g. watermelon, banana, avocado)

Relative risk (%)

280

Risk (%)

Table 16.6 Potential cross-reactions between causes of contact urticaria. If allergic to item in column 1, risk of cross-reacting with item in column 3.  

Fig. 16.10 Relative risk of developing contact urticaria by occupation.  

CHAPTER

APPROACH TO THE PATIENT WITH SUSPECTED TYPE I LATEX ALLERGY

Systemic symptoms

Yes

No

Specific IgE blood test

Prick test latex extract

Positive: latex allergic

Positive: latex allergic

Negative

Confirm with usage test

Look for another cause: Dermographism Irritant reaction

Low-molecular-weight chemicals

Although rare, these chemicals can be important causes of occupational contact urticaria in the industrial setting. Some are also potential causes of occupational asthma. The diagnosis may prove difficult to establish because skin testing may require conjugation of the low-molecular-weight chemical with protein to form the allergen. Chemicals (and industries) associated with contact urticaria include: antibiotics (pharmaceutical industry); ammonium persulfate and paraphenylenediamine (hairdressing); phthalic anhydrides, epoxy resin systems and polyfunctional aziridines (plastics and glue industry); and reactive dyes (textile workers).

Negative

16 Occupational Dermatoses

latex protein is absorbed onto starch particles in gloves, it can become airborne and cause conjunctivitis, rhinitis, and asthma. Ideally, powderfree gloves should be used to avoid this risk. In a subgroup of latex-sensitive patients, hypersensitivity reactions to bananas, avocados, chestnuts, kiwis and other fruits may also occur (see Table 16.6). Radioallergosorbent inhibition studies have shown that they contain a similar antigen. In some individuals, the primary sensitization is to the fruit, with latex sensitivity developing as a secondary phenomenon. Common household sources of exposure to latex are gloves, balloons, latex contraceptives, latex mattresses and pillows, rubber bands, swimming caps, and baby pacifiers. The term “hypoallergenic glove” refers to latex gloves with reduced levels of accelerators and antioxidants (causes of allergic contact dermatitis); these gloves are not suitable for individuals allergic to latex (with immediate-type hypersensitivity). Non-latex alternatives should be sought. Vinyl (PVC) gloves are suitable for home use. For those in the medical and dental professions, alternative gloves, typically nitrile (both sterile and non-sterile), are available from the major glove suppliers. Affected individuals should warn any doctor or dentist that they visit of their sensitivity so that measures can be taken to prevent a reaction. The most severe reactions have followed mucosal and parenteral exposures. Death has occurred following the use of a natural rubber latex cuff on a barium enema device and anaphylaxis after intraoperative, oral, or vaginal exposure to latex gloves. Use of a bracelet or necklace to alert medical professionals in the event of an emergency has been advocated.

Allergy to casein or accelerator

Fig. 16.11 Approach to the patient with suspected type I latex allergy. IgE-mediated immediate hypersensitivity is detected by prick tests, whereas delayed-type hypersensitivity, which manifests as allergic contact dermatitis, is detected by patch testing. In the open usage test, the patient wears the suspect glove on a moistened hand.  

Protein contact dermatitis

The term “protein contact dermatitis” was originally used to describe an eczematous reaction to protein-containing material in food handlers (see Table 12.7). The reactions were both allergic and non-allergic, although many had a positive prick test or the presence of specific IgE antibodies, implying an IgE-mediated mechanism. In some, positive patch tests pointed to the coexistence of delayed-type hypersensitivity. The clinical picture is usually that of a chronic eczema with episodic exacerbations following contact with the allergen20.

Pathology The histologic findings of contact urticaria are described in Chapter 18.

Differential diagnosis After a detailed history and clinical examination, skin testing may be performed to confirm the diagnosis of contact urticaria. When the patient has experienced anaphylactic symptoms and a specific IgE test is available, the blood test may confirm the diagnosis, avoiding the risk of anaphylaxis as a result of skin testing. Skin testing should be performed with appropriate positive and negative controls. With an unknown allergen, exposure should be graded; an initial application test (open and subsequently occluded) is followed by a prick test and, if necessary, an intradermal test. If the patient has a positive test, control individuals should be tested; a positive response in the latter group points to the presence of a nonimmune contact urticant. While commercial allergen extracts are available, it should be remembered that, unless adequately standardized, they may not contain the relevant protein allergens, resulting in a false-negative test result. The gold standard for testing is a sample of fresh material. Skin tests should only be performed where resuscitation facilities are available. In the case of latex, the specific IgE blood test is not sensitive and a negative test does not exclude the diagnosis (Fig. 16.11). While skin tests with glove extracts have been recommended, many gloves now contain low levels of latex protein and prick testing with these

Fig. 16.12 Positive prick test with a commercial latex extract (L). Histamine (H; 10 mg/ml) and saline (C) controls are appropriately positive and negative. The histamine-positive control confirms that the effects of previous medications (including antihistamines) are no longer an issue and the negative control assesses for dermographism. When a standardized allergen is available for a prick test, a small drop is placed on the skin and the skin is pierced with a special lancet with a 1 mm tip. Surplus allergen is blotted off and a fresh lancet is used for each test substance to prevent cross-contamination. Reactions develop over 15 minutes and a wheal 3 mm larger than the negative control is considered positive.  

homemade extracts frequently leads to false-negative results. Prick test solutions of latex are commercially available, some of which claim >98% sensitivity and 100% specificity (Fig. 16.12). If a particular glove type appears to elicit symptoms, a so-called “prick to prick” test can be used: the suspected item itself is pricked with the lancet, after which the patient’s skin is pricked with the antigen-“contaminated” lancet.

281

SECTION

Papulosquamous and Eczematous Dermatoses

3

The final arbiter is a usage test in which a patient wears the suspect glove on a moistened hand and is observed for any reaction. In the absence of a latex allergy, localized symptomatic dermographism is a common cause of urticaria to gloves. Lastly, a proportion of individuals who have reactions to gloves have symptoms caused by irritation.

Treatment Management consists of avoidance, as desensitization for the majority of involved allergens is not available. Avoidance may be achieved by improved occupational hygiene and the use of personal protective equipment, but in extreme circumstances may necessitate a change of occupation. Treatment of the acute episode includes the use of systemic antihistamines and epinephrine (adrenaline), depending on the severity of the attack. In the case of latex, the use of powder-free gloves containing low levels of protein has been shown to prevent the development of latex hypersensitivity by reducing the level of exposure in the at-risk population. There has also been a movement in healthcare facilities to use non-latex gloves.

Occupational Skin Cancer Key features ■ A skin cancer in which occupation has played a major etiological role ■ In the workplace, the most important exposures are UV radiation, ionizing radiation, and carcinogenic chemicals (e.g. polycyclic hydrocarbons)

Introduction Occupational skin cancers21 have been estimated to account for less than 1% of all skin cancers. In a study of workers exposed to coal and diesel combustion products, the relative risk for developing nonmelanoma skin cancer was 1.5%22. The tumor most frequently associated with occupational chemical exposure is squamous cell carcinoma (SCC).

History The first association between occupation and cancer was made in 1775. Sir Percivall Pott, a surgeon at St Bartholomew’s Hospital in London, described the occurrence of scrotal cancer in chimney sweeps. The carcinoma was often preceded by keratotic lesions known as soot warts. In 1873, von Volkmann described skin cancers from exposure to the distillation products of tar and pitch. In the early 1800s, inorganic arsenic was associated with skin cancers, especially of the scrotum in smelter workers, but also from exposure in the mining industry and in users of end products (e.g. sheep dip). In the early twentieth century, ionizing radiation was recognized as a cause of radiodermatitis followed by skin cancer, particularly of the hands of medical workers administering radiotherapy.

Epidemiology

282

As carcinogens have become recognized and limits on occupational exposure introduced, solar UV exposure has risen to account for ~95% of cases of occupational skin cancer reported in the UK. In Australia, the most common cause of compensated occupational cancer (of all types) was UV exposure (22%), followed by asbestos (21%)23. It was estimated that 34 000 cases of non-melanoma skin cancer per year and 4% of cases of cutaneous melanoma in men were attributable to occupation. Recently, in Germany, actinic keratoses (AKs) and cutaneous SCCs were recognized and compensated as occupational diseases, provided in the case of AKs they cover at least 4 cm2 or ≥5 separate AKs develop each year23a. The SCCs must arise in sun-exposed skin and the worker must have been occupationally exposed to an additional 40% more UV than that of an indoor worker, e.g. at age 50 the worker would have to have spent 15 years in an outdoor occupation. Occupations at high risk of occupational skin cancer include: outdoor workers, especially in agriculture and building industries, and welders (UV exposure). Squamous cell carcinoma occurs with



an odds ratio (OR) of 1.77 (95% confidence interval [CI] 1.40– 2.22; p B

Capsicum annuum

Hot peppers

Erythema/edema/burning

Capsaicin

Citrus latifolia

Persian lime

Phytophotodermatitis

Furocoumarins

Narcissus pseudonarcissus

Daffodils

ICD

Calcium oxalate

Opuntia spp.

Prickly pear and others

Mechanical irritant dermatitis

Glochids

Parthenium hysterophorus

Scourge of India, congress grass

ACD

Sesquiterpene lactones

Toxicodendron radicans

Poison ivy

ACD ICD (black-spot reaction)

Alkyl-catechols and resorcinols in urushiol

Toxicodendron diversilobum

Poison oak

ACD ICD (black-spot reaction)

Alkyl-catechols and resorcinols in urushiol

Tulipa spp.

Tulips

ACD ICD

Tulipalin A > B Coarse hair on bulbs

Urtica dioica

Stinging nettle

Urticaria

Histamine

X Dendranthema cultivars

Chrysanthemums

ACD

Sesquiterpene lactones

Dermatoses Due to Plants

17

MOST COMMON PLANT DERMATOSES

Table 17.1 Most common plant dermatoses. These are admittedly biased by the anecdotal and unscientific observations as well as literature reviews of the author. ACD, allergic contact dermatitis; ICD, irritant contact dermatitis.  

THE BASIC NOMENCLATURAL SCHEME FOR PLANTS, USING COMMON POISON IVY AS THE EXAMPLE

MOST COMMON RELEVANT BOTANICAL ALLERGENS AND PROPOSED BOTANICAL SCREENING TRAY

Kingdom

Plantae (Metaphyta)

Plant name

Plant family

Test solution

Division

Magnoliophyta (flowering plants) Magnoliopsida (dicotyledons)

    Subclass

Rosidae

Compositae mix 6% in petrolatum, sesquiterpene lactones (SQLs) mix, and parthenolide19

      Order

Sapindales

        Family

Anacardiaceae (sumac or cashew family)

          Genus

Toxicodendron

            Species

radicans

Achillea millefolium (yarrow) Arnica spp. Chrysanthemum cultivars Matricaria chamomilla (chamomile) Tanacetum parthenium (feverfew)

Asteraceae

  Class

              (Author’s name)

(L.) O. Ktze

Cananga odorata

Anonaceae

Cananga (ylang-ylang) oil 2% in petrolatum

Citrus aurantium var. amara

Rutaceae

Neroli oil 4% in petrolatum

Lavandula spp.

Lamiaceae

Lavender (absolute) 2% in petrolatum

Lichens (fungus–alga dual organisms)

Non-plant

Lichen acid mix 0.3% in petrolatum

Table 17.2 The basic nomenclatural scheme for plants, using common poison ivy as the example. The distinctive ending for each category is underlined. Note that the minor categories of nomenclature have no special endings.  

Patch Testing Details of patch testing are beyond the scope of this chapter (see Ch. 14). The reader is also referred to the paper by Mitchell2. The most common allergenic plants and a proposed botanical screening tray are found in Table 17.33.

IMMUNOLOGIC CONTACT URTICARIA Key features ■ Atopy and frequent contact with fresh fruits and vegetables are risk factors ■ May present as urticaria, pruritus, burning or chronic dermatitis ■ Oral allergy syndrome is mucosal contact urticaria caused by antigens similar to allergenic pollen ■ Protein contact dermatitis represents an eczematous eruption arising from repeated urticarial reactions Plant-induced urticarial reactions are divided into immune and nonimmune (toxin-mediated [see next section]). Several cutaneous reaction patterns besides wheals are possible, e.g. erythema, dermatitis.

Melaleuca alternifolia

Myrtaceae

Tea tree oil 5% in petrolatum

Mentha spp.

Lamiaceae

Spearmint oil 5% in petrolatum

Pelargonium cultivars

Geraniaceae

Geranium oil (Bourbon) 2% in petrolatum

Rosa damascena

Rosaceae

Rose oil (Bulgarian) 2% in petrolatum

Santalum album

Santalaceae

Sandalwood oil 2% in petrolatum

Taraxacum officinale

Asteraceae

Dandelion 2.5% in petrolatum

Table 17.3 Most common relevant botanical allergens and proposed botanical screening tray. This list may help to narrow down a potential botanical allergy in a patient who brings specimens into your office to examine3. Note this screening tray does not include urushiol.  

287

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Papulosquamous and Eczematous Dermatoses

3

Epidemiology Immunologic contact urticaria is rather uncommon. Approximately 95% of cases are work-related – long-time food handlers with under­ lying dermatitis are at greatest risk. However, fully half of patients with “protein contact dermatitis” (a type IV eczematous eruption arising from repeated type I urticarial reactions) are not atopic. Examples of reported urticants include common vegetables (e.g. celery, onions, potatoes, lettuce), fruits (e.g. tomatoes, bananas, lemons), herbs (e.g. parsley, dill), nuts, shrubs, algae, lichens, trees and grasses.

Pathogenesis (see Ch. 18) IgE-mediated release of vasoactive mediators from mast cells leads to local urticaria and, rarely, a “contact urticaria syndrome” that includes local wheals plus systemic symptoms involving the nose, throat, lungs, gastrointestinal tract or cardiovascular system. The main cause seems to be histamine release, but prostaglandins, kinins and leukotrienes probably augment the inflammatory response. Clinical Features Within 30 minutes of contact with certain fresh foods, affected individuals experience pruritus, erythema, urticarial swelling, and even dyshidrotic-like vesicles. Sometimes, individuals only develop symptoms of pruritus, burning or tingling without objective findings4. Theoretically, any plant can cause contact urticaria, especially with repeated exposures on the wet, macerated skin of food handlers. Cooking, processing, deep-freezing or crushing fruits and vegetables generally reduces their allergenicity. Some individuals become cross-sensitized to pollen and similar allergens in fruits or vegetables5. Upon eating a cross-reacting food, they experience sudden, IgE-mediated, oral cavity itching, stinging and pain. Edema of the lips, tongue, palate and pharynx typically ensue as the “oral allergy syndrome” (OAS) progresses. Gastrointestinal symptoms and anaphylaxis are possible if enough allergens are ingested. As an example, 70% of European patients with immediate hypersensitivity to birch pollen develop OAS while eating apples, pears, cherries, peaches, plums, apricots, almonds, celery, carrots, potatoes, kiwis, hazelnuts or mangoes. Pollen-associated foods are often, but not always, edible when heated. The term “protein contact dermatitis” is used to describe a chronic dermatitis in which patch tests are typically negative but prick tests to large protein allergens are positive6. Patients develop a chronic dermatitis that acutely urticates within minutes of contact with the offending allergen. This is one of multiple mechanisms by which plants can cause chronic hand and fingertip eczema (Fig. 17.1).

Differential Diagnosis and Pathology See Toxin-Mediated (Non-immunologic) Contact Urticaria and Chs 16 & 18.

Treatment Prevention is the preferred form of “treatment”, but oral antihistamines are sometimes helpful. Parenterally administered epinephrine (adrenaline) is required for anaphylactic reactions.

TOXIN-MEDIATED (NON-IMMUNOLOGIC) CONTACT URTICARIA

Key features ■ ■ ■ ■

288

Anyone can be affected Stinging nettles (Urtica spp.) are most common cause Reaction can be subjective only Sharp hairs on the plants can contain histamine, serotonin and acetylcholine

CAUSES AND TYPES OF CHRONIC HAND OR FINGER DERMATITIS CAUSED BY PLANTS Chronic hand and/or fingertip dermatitis – often with hyperkeratosis and fissures

Chronic phytophotodermatitis • especially limes in bartenders

Protein contact dermatitis

Chemical irritant dermatitis

Allergic contact dermatitis

More common • Daffodils • Garlic • Pineapples

Most common • Alstroemeria (both hands) – frequently florists • Primula (primarily dominant hand) (due to “dead-heading”) • Chrysanthemums (primarily dominant hand) (due to “dead-heading”) • Tulip bulbs (dominant hand) – often occupational • Garlic (non-dominant hand) – homemakers and caterers

Less common • Codiaeum variegatum Florist’s “croton” • Ricinus communis Castor bean plant See Botanical Dermatology * Database at www.botanical-dermatologydatabase.info

Less common • Other Asteraceae • Myrtaceae (Melaleuca) (paper-bark tree) • Orchidaceae • Additional species

*

Fig. 17.1 Causes and types of chronic hand or finger dermatitis caused by plants.  

History Plants causing toxin-mediated urticaria have been used since antiquity as counterirritants in folk medicine, and Native Americans used stinging nettles to treat rheumatism, stomach upset, postpartum hemorrhage, paralysis, fevers, colds and tuberculosis. Stinging nettle is used to produce homemade diuretics, and stem fibers were even used to make cloth until the early twentieth century.

Epidemiology Urticaceae family members cause the majority of plant-induced contact urticaria. Because all persons exposed to the toxins develop urticaria, toxin-mediated urticaria is far more common than immunologic urticaria. Since very few affected people seek medical attention, the true incidence of toxin-mediated urticaria is unknown. The most common culprit in the US is the stinging nettle (Urtica dioica; Fig. 17.2A)7, which is widely scattered throughout the northern hemisphere (except in lowland tropical areas), especially in moist woods, roadsides and on waste land. Other common urticating plants are listed in Table 17.4.

Pathogenesis (see Ch. 18) Inciting plants possess sharp hairs (trichomes) on leaves and stems (see Fig. 17.2A). The proximal silicaceous hair is attached to a distal calcified portion that possesses a terminal bulb. When rubbed against, the bulb dislodges to reveal a beveled, hypodermic needle-like, hollow hair (Fig. 17.2B). The latter releases an irritant chemical cocktail (histamine, acetylcholine, serotonin) that supposedly serves as a defense mechanism against herbivores. Clinical Features Wheals achieve maximal size 3 to 5 minutes after contact, and erythema, burning and pruritus last 1–2 hours. Paresthesias may last 12 hours or more. Although histamine, acetylcholine and serotonin explain the early cutaneous reaction, they do not account for the persistent paresthesias.



Botanical briefs: stinging nettle – Urtica dioica L. Cutis. 1998;62:63–4; © Quadrant Health Com Inc.

B

CHAPTER

17 Dermatoses Due to Plants

Fig. 17.2 Stinging nettle (Urtica dioica). A Note the trichomes on both the stem and the leaf surfaces.   B Broken trichome from the stinging nettle (Urtica dioica). A bubble is visible where urticating chemicals are found. B with permission from McGovern TW, Barkley TM.

A

THE MOST COMMON PLANTS CAUSING TOXIN-MEDIATED URTICARIA

Differential Diagnosis (see Ch. 18) Although the evaluation of such patients is difficult, office testing of suspected allergens or toxin-containing plants may involve one of several methods4. The most sensitive tests for immunologic contact urticaria are the prick and scratch-chamber tests. For the scratchchamber test, a 5-mm scratch is made on the back or forearm. Test material is applied and occluded with a Finn chamber for 15 minutes. The site is examined following Finn chamber removal and every 15 minutes for an hour. After reading, the chamber can be replaced for 48 hours to test for delayed hypersensitivity. The open application test provides the most reliable way to test for toxin-mediated urticaria. Samples (0.1 ml) from a series of dilutions are each spread onto discrete 3 × 3 cm areas of skin. Sites are observed every 10–15 minutes for an hour. Maximal erythema and edema typically occur 30–40 minutes after application.

Family

Genus

Species

Notes

Urticaceae (nettle family)

Urtica

dioica, urens, pilulifera

Stinging nettles – worldwide

Laportea

canadensis

“Wood nettle”, 5-foot-tall perennial herb – NE USA

Dendrocnide

gigas, moroides, photinophylla

Potentially deadly stinging trees – eastern Australian rainforests

Acidoton

urens

Tropical Americas

Treatment

Cnidosculus

stimulosus

Spurge nettle – SE USA

other species

Spurge nettles of tropical Americas

Most stings are benign, self-limited, and require no treatment. Trichomes may be removed with glue and gauze as described in the next section. Topical pramoxine or oral analgesics may provide some symptomatic relief.

caracasana, urens

Large-leafed shrubs – tropical Americas

Euphorbiaceae (spurge family)

Hydrophyllaceae (water-leaf family)

Wigandia

MECHANICAL IRRITANT DERMATITIS

Table 17.4 The most common plants causing toxin-mediated urticaria.  

Key features Reactions to stinging nettle pale in comparison to those elicited by members of the Dendrocnide genus of the Urticaceae family. These trees grow up to 40 meters tall in eastern Australian rainforests. Young shoots are covered with stiff stinging hairs. Severe urticaria from these may last for weeks, and contact with water or cold objects reactivates the urticaria. Severe, intermittent, stabbing pains may follow the course of lymphatics. Human and animal deaths due to Dendrocnide contact have been documented.

Pathology (see Ch. 18) Five minutes after contact with Urtica dioica, dermal edema and telan­ giectasias with or without mild spongiosis are seen. At 12 hours, the edema resolves but vasodilation persists. Some patients develop spongiosis in conjunction with a neutrophilic and/or lymphocytic infiltrate. Mast cells are observed within the papillary dermis at 12 hours, but not at 5 minutes.

■ Large spines (modified leaves) and thorns (modified branches) cause penetrating injuries and secondary infection ■ Small fishhook-shaped spines (glochids) can embed in the skin ■ Prickly pears are a cause of glochid dermatitis

Epidemiology Mechanical irritant dermatitis can affect anyone. Many plants, including most cacti, can inflict mechanical injury via small or large emergences. Generally, the amount of damage to the skin is inversely proportional to the size of the emergence. Many of the plant families that can cause mechanical irritant dermatitis are listed in Table 17.5.

Pathogenesis Whereas cacti possess large spines, their smaller glochids cause more notorious dermatologic problems. The glochids – tufts of hundreds of

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COMMON PLANTS KNOWN TO CAUSE MECHANICAL IRRITANT REACTIONS

Family

Genus species

Notes

Amaranthaceae

Kali tragus

Tumbleweed or Russian thistle – sharp-edged spines penetrate skin

Araliaceae

Hedera helix

Common ivy – leaf-borne stellate hairs detach as leaves age

Asteraceae

Carduus and Cirsium spp.

Thistles

Asteraceae

Lactuca serriola

Prickly lettuce

Boraginaceae

Borago officinalis

Borage – sharp, stiff leaf and stem hairs

Cactaceae

Opuntia spp.

Prickly pears; “Sabra dermatitis”

Liliaceae

Tulipa spp.

Coarse fibers on tulip bulb tunics cause irritant component of “tulip fingers”

Moraceae

Ficus spp.

Figs – abrasive bristles on leaves and fruit

Morus spp.

Mulberries – abrasive bristles on leaves and fruit

Nyctaginaceae

Bougainvillea

Sharp spines on stems and spear-shaped crystals in trichomes on leaves (Brazil native)

Poaceae

Many spp.

Grasses – fine hairs, prickly spikes, and cutting leaf edges

Proteaceae

Grevillea spp.

Terminal, sharp points on leaves – Australia

Rosaceae

Rosa spp.

Thorns can cause penetrating injuries, tenosynovitis and foreign body granulomata

Rubiaceae

Galium aparine

“Goose-grass” – hooked prickles on fruit, stems, leaves

Scrophulariaceae

Verbascum thapsus

“Mullein” or “flannel-plant” – woolly hairs on leaves used as facial rubefacient

Fremontodendron spp.

“California glory” possesses stiff, stellate hairs

Sterculiaceae

Table 17.5 Common plants known to cause mechanical irritant reactions. Although numerous plants possess irritant appendages, some of the wellknown ones are listed here.  

A

290

B

short, barbed or hooked hairs – arise from pincushion-like structures called “areoles”, from which larger spines may also arise. The minute, barbed glochids (Fig. 17.3A) often point outward and backward like a fishhook and produce considerable irritation and pruritus after penetrating the skin. For example, Opuntia microdasys (“polka dot cactus”, “bunny ears cactus”), a house and garden favorite, bears disarmingappearing “fluffy” clusters of 100–200 glochids on its pads (see Fig. 17.12).

Clinical Features One form of glochid dermatitis from prickly pears (Opuntia spp.) is “Sabra dermatitis”, a pruritic, papular eruption that occurs among prickly-pear pickers and those who unwarily stumble into burglar-proof hedges of this native Mexican plant (Fig. 17.3B). The fruit contains the highest concentration of glochids (Fig. 17.3C) and the ensuing eruption can resemble fiberglass dermatitis or scabies. Prickly pears should be picked only when wetted, and harvesting should cease when it is windy, since the glochids can become airborne. All 200 or so species of Opuntia are native to the New World, ranging from New England and British Columbia southward to the Straits of Magellan. Numerous species have become established in the Mediterranean basin, South Africa, South Asia and Australia. Spine and thorn injuries can be complicated by the inoculation of microorganisms such as Clostridium tetani and Staphylococcus aureus into the skin. Grasses, sphagnum moss and rose thorns can transmit Sporothrix schenckii. Atypical mycobacteria such as Mycobacterium kansasii (blackberries), M. marinum (cactus spines), and M. ulcerans (spiky tropical vegetation) have also added infectious insult to mechanical injury.

Treatment In a controlled study in rabbits, Opuntia glochids were most effectively removed by first detaching the larger clumps with tweezers and then applying glue and gauze to the affected area. After the glue dried, the gauze was grasped and peeled off, resulting in the removal of 95% of implanted glochids8.

CHEMICAL IRRITANT DERMATITIS Key features ■ Calcium oxalate in daffodils is a major cause of plant-related irritant dermatitis in florists and horticulturalists ■ Spurges (including poinsettias) contain irritant phorbol esters in latex ■ Capsaicin in hot peppers affects cutaneous nerves, but not the skin

C

Fig. 17.3 Prickly pears (Opuntia spp.) and their glochids. A Microscopic appearance of glochids from Opuntia microdasys. B Prickly pear (Opuntia ficus-indica) habit. C Prickly pear (Opuntia ficus-indica) fruit. Fine spines and glochids are visible. Courtesy, Dirk Elston, MD.  

Plant-derived irritant chemicals have been recognized for centuries. Native Mexican Indians once used smoke from burning peppers (Cap­ sicum [Solanaceae]) as a weapon against enemies, and latex from the manchineel tree (Hippomane mancinella [Euphorbiaceae]) was used by Caribbean people as poison for arrow tips.

Epidemiology Several major plant families found throughout the world contain chemical irritants (Table 17.6).

Pathogenesis, Clinical Features and Treatment (see Ch. 15) Calcium oxalate, one of the most common chemical irritants, is found in Dieffenbachia picta (Araceae), a plant that decorates millions of homes and public places. Upon contact with a moist surface, the leaves release water-insoluble calcium oxalate. When leaves are chewed, salivation, burning, mucosal edema, and blistering ensue. This causes hoarseness or aphonia (hence the common name “dumb cane”). Treatment includes parenteral corticosteroids, antacid mouthwashes, and analgesics; antihistamines are of no benefit. The pain and edema wane over 4–12 days. Calcium oxalate enhances the irritancy of other chemicals, including the proteolytic enzyme bromelain (bromelin) found in pineapples. Pineapple workers often develop cracks, fissures, fingerprint loss, and microhemorrhages on their hands. Calcium oxalate-induced microabrasions allow bromelain to exert its proteolytic effect on dermal blood vessels. Nitrile gloves can be worn for protection. Bulb dermatitis, though less dramatic, is more common9. Daffodil sap, found not only in bulbs but also in stems and leaves, contains calcium oxalate and causes “daffodil itch”, probably the most common dermatitis in florists. Dryness, scaling, fissures and erythema develop on the fingertips, hands and forearms. Bulbs of several other plants (e.g. tulips, hyacinths) also commonly cause dermatitis. Allergens found in garlic bulbs act as irritants at high concentrations leading to second-

and third-degree burns as well as subungual hyperkeratosis and hemorrhage that can mimic nail psoriasis. While spurges are notorious for their irritant latex, they derive their common name from the purgative properties of their seeds. The milky latex contains irritant phorbol esters, diterpenes, and daphnane esters that may cause a painful, blistering dermatitis and even temporary blindness if the latex contacts the eye. Sitting under a manchineel tree in the Caribbean during a rainstorm will lead to intense cutaneous burning, erythema and bullae, often accompanied by periocular swelling through transfer of the latex by rain. The fruit of this tree is known locally as the “apple of death”. The latex of the best-known family member, the poinsettia (Euphorbia pulcherrima), is only mildly irritating. Buttercups (Ranunculaceae) contain the glycoside ranunculin that is converted to protoanemonin after plant injury. Protoanemonin causes severe, linear vesiculation that may resemble early phytophotodermatitis, but no hyperpigmentation ensues. Because protoanemonin rapidly polymerizes to the non-irritant anemonin, only freshly damaged plants cause reactions. “Chili burns” commonly occur among those who remove skins from large batches of roasted chili peppers (Capsicum annuum). When applied to skin, the active principle, capsaicin, depolarizes nerves causing vasodilation, smooth muscle stimulation, glandular secretion, and sensory nerve activation. Because only nerves are affected, there is erythema but no vesicles or bullae. Symptoms may be delayed and last hours to days. The best home remedy for chili burns is handwashing with soap and water followed immediately by 1 hour of immersion in vegetable oil to remove the fat-soluble capsaicin. The “century plant” (Agave americana) grows in temperate, subtropical and tropical climates and forms rosettes of tough, sword-shaped leaves with spiny margins. The marked pruritus and stinging that follows within five minutes of contact with the agave leaf is thought to be caused by latex-derived calcium oxalate crystals and saponins. Purpura may appear subsequently. Soldiers have been known to try to “earn” sick leave by rubbing broken leaves on their skin to induce a severe vesiculopustular irritant dermatitis, often accompanied by systemic symptoms10.

CHAPTER

17 Dermatoses Due to Plants

History

PLANTS MOST COMMONLY IMPLICATED IN CAUSING CHEMICAL IRRITANT DERMATITIS

Family

Binomial name

Common name

Irritant chemical (location)

Agavaceae

Agave americana

Century plant

Calcium oxalate, saponins (latex throughout plant)

Alliaceae

Allium sativum

Garlic

Thiocyanates (bulbs)

Amaryllidaceae

Narcissus spp.

Daffodil, narcissus

Calcium oxalate (stems, leaves, bulbs)

Anacardiaceae

Anacardium occidentale

Cashew tree

Cashew nut shell oil (mesocarp [middle layer] of nut shell [irritant and allergenic])

Araceae

Dieffenbachia picta

Dumb cane

Calcium oxalate (leaves and fruits)

Philodendron spp.

Philodendron

Calcium oxalate (leaves) Thiocyanates (all parts)

Brassica nigra

Black mustard

Raphanus sativus

Radish

Bromeliaceae

Ananas comosus

Pineapple

Bromelain (stem > fruit) Calcium oxalate (all parts)

Euphorbiaceae

Codiaeum variegatum

Florist’s “croton”

Euphorbia esula

Leafy spurge

Hippomane mancinella

Manchineel tree

Phorbol esters (latex in stems, leaves, fruits) Standing in rain beneath manchineel tree can transfer highly irritant latex and even cause blindness

Brassicaceae

Euphorbia pulcherrima

Poinsettia

Liliaceae

Hyacinthus orientalis

Hyacinth

Calcium oxalate (bulbs)

Polygonaceae

Rheum rhaponticum

Rhubarb

Calcium oxalate (leaves)

Ranunculus spp.

Buttercups

Protoanemonin (freshly damaged plant parts)

Aquilegia spp.

Columbine

Ranunculaceae

Solanaceae

Caltha spp.

Marsh-marigold

Capsicum annuum

Hot pepper

Capsaicin (placenta of fruit [no dermatitis, only erythema, edema, burning])

Table 17.6 Plants most commonly implicated in causing chemical irritant dermatitis.  

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Papulosquamous and Eczematous Dermatoses

3

PHYTOPHOTODERMATITIS Key features ■ Non-immunologic – it can happen to anyone ■ Need UVA light plus topical or oral contact with photosensitizer ■ Furocoumarins (psoralens and angelicins) are the most common photosensitizers ■ Limes, celery and rue (herb-of-grace) are the most common causes ■ Potential photosensitizing plants of the family Apiaceae can be identified by umbel flower structure

Phytophotodermatitis connotes phototoxic reactions consisting of erythema (with or without blistering) and delayed hyperpigmentation following exposure to plants. Phototoxicity implies an inflammatory reaction caused by the combination of a topical or oral photosensitizing agent followed by exposure to the appropriate wavelength of UV radiation. Because this is not an immunologic reaction, no prior sensitization is necessary and anybody can be affected.

History As early as 2000 BC, vitiligo patients were encouraged to lie in the sun after picking Ammi majus from the Nile River valley and rubbing the juice on their skin. By 1400 BC, Indian doctors were using boiled extracts of Psoralea corylifolia (scurf-pea), from which we derive the term “psoralen”. Even nowadays in India, its seeds remain a major source of psoralens for the treatment of vitiligo. In 1897, Apiaceae-induced dermatitis was first reported, but the need for concomitant UV radiation went unnoticed. It would be another 40 years before Klaber introduced the term “phytophotodermatitis” to emphasize that a combination of plants (“phyto-“) plus light (“photo-”) is required for the reaction.

IMPORTANT MEMBERS OF THE APIACEAE FAMILY (FORMERLY UMBELLIFERAE) IMPLICATED IN PHOTOTOXIC REACTIONS

Scientific name

Common name(s)

Comments

Ammi majus

False Bishop’s weed

Historical and economic importance

Angelica archangelica

Angelica

Candied portions used in cakes; characteristic Benedictine flavor

Angelica sylvestris

Wild angelica

Anthriscus sylvestris

Cow parsley, wild chervil

“Strimmer dermatitis”*

Apium graveolens

Celery

Fungus-infected plants produce more psoralens

Ficus carica

Fig

Widespread seconddegree burns when used as tanning promoter (Turkey)

Foeniculum vulgare

Fennel

Heracleum laciniatum

Tromsø palm

Scandinavia

Heracleum lanatum

Cow parsnip

North America

Heracleum mantegazzianum

Giant Russian hogweed, wild rhubarb, hogweed tree

Giant weed naturalized and invasive across UK, Europe, Canada, US

Heracleum sphondylium

Common hogweed

Main cause of “strimmer dermatitis”*

Notobubon galbanum

Blister bush

South Africa

Pastinaca sativa

Parsnip

Furocoumarins in leaves, roots, stem, fruits

Petroselinum crispum

Parsley

Epidemiology Apiaceae (formerly Umbelliferae) and Rutaceae (citrus family) plants are the most common causes of phytophotodermatitis (Tables 17.7 & 17.8). Members of the mulberry (Moraceae) and pea (Fabaceae) families also contain furocoumarins.

Apiaceae A distinctive floral umbel makes family members easy to recognize: numerous small flowers are held in a simple umbel (a cluster of flowers on stalks of roughly equal length arising from a single point). Many small umbels can form “compound umbels” (Fig. 17.4A). Compound umbels may be umbrella-shaped or ball-shaped. The flower heads are sheathed at the base by one or more leaf-like bracts. Common hogweed (Heracleum sphondylium) and giant hogweed (H. mantegazzianum; Figs 17.4B,C) are major causes of phytophotodermatitis and grow invasively in Europe and North America. Fruits contain the highest concentrations of psoralens followed by leaves and stems. The greatest threat from hogweed occurs in the autumn, when the weather favors the development of many seeds. One severe case of occupational contact with giant hogweed during mid-summer roadside lawn mowing led to marked phytophotodermatitis-induced soft tissue necrosis of the leg and eventual below-the-knee amputation.

Rutaceae

292

The Rutaceae family includes tropical (Citrus spp.), subtropical, and temperate (Ruta spp.) plants and is the second most common family of plants (after Apiaceae) to cause phytophotodermatitis (see Table 17.8). Many Rutaceae grow as shrubs or small trees and produce fleshy fruit. The rind of the Persian lime (Citrus latifolia), which contains ten times more 5-methoxypsoralen (5-MOP) than the pulp, is a major cause of phototoxic reactions in the US, especially in Florida and the desert Southwest. Outdoor bartenders commonly develop vesicles on their index and middle fingers from squeezing limes to make cocktails. Even the sweet orange (Citrus sinensis) can cause a phototoxic cheilitis after contact with the rind.

*Strimmer = string-trimmer garden tool for cutting weeds. Table 17.7 Important members of the Apiaceae family (formerly Umbelliferae) implicated in phototoxic reactions.  

PHOTOTOXIC MEMBERS OF THE FAMILY RUTACEAE

Scientific name

Common name(s)

Citrus aurantiifolia

Key lime

Citrus latifolia

Persian lime or seedless lime

Citrus aurantium

Bitter orange

Citrus bergamia

Bergamot orange

Citrus sinensis

Sweet orange

Citrus limetta

Sweet lemon

Citrus limon

Lemon

Citrus paradisii

Grapefruit

Cneoridium dumosum

Coast spice bush, berry rue

Dictamnus albus

Burning bush, gas plant

Pelea anisata

Mokihana (berries used for lei in Hawaii)

Phebalium squamulosum

Blister bush, common in Western Australia

Ruta graveolens

Rue, herb-of-grace

Table 17.8 Phototoxic members of the family Rutaceae.  

CHAPTER

17

Simple umbel

A

Umbrella-shaped compound umbel

Dermatoses Due to Plants

APIACEAE

Compound umbel

Ball-shaped compound umbel

Fig. 17.5 Bullous phase of phytophotodermatitis. There was associated burning but no pruritus, and the linear bullae were replaced by hyperpigmentation. Courtesy, Jean L Bolognia, MD.  

Fig. 17.4 Apiaceae. A Compound umbels can be umbrella-shaped or ball-shaped. B Giant hogweed (Heracleum mantegazzianum) habit, Mackinac Island, MI, USA. C Compound umbel of giant hogweed.  

B

C

Garden rue (Ruta graveolens) is a bitter tasting and smelling subshrub native to the Mediterranean basin with a long history as a folk medicine remedy and insect repellant. It contains 5-MOP, 8-MOP and angelicins, and is probably the most common cause of phototoxicity acquired in English gardens. Dictamnus albus, the gas plant or burning bush, exudes an aromatic oil that can be ignited briefly without harming the plant. It has become a common yard plant in the US and Canada, and it grows wild in central and southern Europe, eastern Siberia and northern China. The seed pods have high concentrations of both 5-MOP and 8-MOP.

Moraceae The mulberry family includes the fig tree (Ficus carica), a Middle Eastern native that has been widely cultivated throughout warm, temperate regions of the world. Psoralens are found chiefly in the sap of leaves and shoots but not in the fruit10a.

Other families Eleven of 23 HIV-infected patients receiving systemic hypericin (from St John’s wort, Hypericum perforatum [Hypericaceae]) as a potential antiretroviral agent developed severe cutaneous phototoxicity. Eating wild spinach (Chenopodium album [Chenopodiaceae]) has repeatedly led to phototoxicity, but the sensitizing agent remains unknown.

Pathogenesis Furocoumarins possess linear (psoralens) or angular (angelicins) tricyclic structures. Bergapten (5-MOP), originally isolated from the southern European bergamot orange (Citrus bergamia), and 8-MOP (xanthotoxin), first isolated from the Nigerian prickly ash (Fagara zan­ thoxyloides), cause the most severe reactions. In the presence of UVA (peak effectiveness at 320–340 nm), psora­ lens within the skin can react with molecular oxygen and form reactive oxygen species that induce cytoplasmic vacuolization and membrane rupture of keratinocytes. Within 2 hours of UVA exposure, desmosomal plaques detach and degenerate leading to blister formation without the need for DNA damage11. UVA also excites intercalated psoralens to form covalent interstrand DNA cross-links by binding to pyrimidines (see Ch. 134). This leads to further keratinocyte cell death (apoptosis, “sunburn cells”) and stimulates hyperpigmentation via increased melanocyte mitosis and dendricity, melanocyte hypertrophy, increased tyrosinase activity, larger melanosomal size, and enhanced distribution of melanosomes throughout the epidermis. Furocoumarins appear necessary to defend plants from fungal attack. Healthy celery plants (Apium graveolens) contain 10–100 mcg/g wet weight of psoralens, but they may produce 320 mcg/g when infected with pink-rot fungus (Sclerotinia sclerotium). Disease-resistant celery unfortunately possesses high levels of furocoumarins concentrated in the leaf and stem sap.

Clinical Features Cutaneous sensitivity to UVA light peaks 30–120 minutes after contact with furocoumarins. Bizarre configurations of erythema, edema and bullae appear after 24 hours and peak at 72 hours (Fig. 17.5). These painful, non-pruritic reactions are more often seen in mid to late summer, when psoralen concentrations are highest in the offending plants and more skin is exposed to direct sunlight. To avoid misdiagnosis as poison ivy dermatitis, physicians must note that the initial erythematous and bullous reaction only occurs in sun-exposed areas. Hyperpigmentation appears 1–2 weeks later and lasts months to years (Fig. 17.6). Occasionally, low-dose UVA and/or psoralens cause

293

SECTION

Papulosquamous and Eczematous Dermatoses

3

hyperpigmentation without a preceding vesicular or erythematous eruption (see Ch. 67). Involved areas may remain hypersensitive to UV radiation for years. Wet skin, sweating and heat enhance the phototoxic response. Furocoumarin exposure occurs in many settings (Table 17.9). Modern power tools such as weed-whackers and strimmers (string trimmers) deliver a buckshot spray of weeds that may include phototoxic plants. “Strimmer dermatitis” appears 12–24 hours later as red, irregular macules and papules, not bizarre linear and angular streaks, on the chest, arms, and legs if wearing shorts. Implicated species, especially

Fig. 17.6 Phytophotodermatitis. Streaky hyperpigmentation due to contact with a psoralen-containing plant followed by exposure to sunlight.  

Courtesy, Lorenzo Cerroni, MD.

in Europe, include common hogweed (Heracleum sphondylium), giant hogweed (Heracleum mantegazzianum), and cow parsley (Anthriscus sylvestris). Berlock (or berloque, meaning trinket or charm) dermatitis is characterized by pendant-like streaks of pigmentation on the neck, face, arms or trunk after the application of colognes containing 5-MOP. Phytophotodermatitis has also been mistaken for child abuse (see Ch. 90). Parents who touch plants or fruit containing furocoumarins can transfer the latter to their children. A week or more later, these children may develop digitate hyperpigmentation in sun-exposed sites of parental hand contact. Multiple hues are not seen in the skin lesions, as would be expected in healing bruises. In addition, lime-induced phytophotodermatitis can be misdiagnosed as allergic contact dermatitis, impetigo, cellulitis, and infectious lymphangitis. Celery harvesters and canners are at high risk for developing phyto­ photodermatitis. Only 1 mcg of 8-MOP/cm2 of skin is necessary to produce blisters after 2.4 J/cm2 (less than 10 minutes) of summer sunlight in Colorado. In one study of 320 randomly selected Michigan celery workers, 163 (51%) displayed various stages of vesicular and bullous dermatitis on the fingers, hands and forearms12. In this study, the authors could not induce phytophotodermatitis except by using celery infected with pink-rot fungus. However, photo­ toxicity following the ingestion of naturally occurring psoralens is uncommon.

Phytophotoallergic Contact Dermatitis Photoallergy due to plants is rare. A 20-year review of photopatch testing results from a tertiary medical center found reactions in eight of 69 patients, with reactions in only four patients thought to be clinically relevant13.

Treatment Prevention is the best treatment for phytophotodermatitis. Known furocoumarin-containing plants should not be planted near play areas. When using weed-whackers or strimmers, operators must cover their chest and extremities. If one has been in contact with a suspected phototoxic plant, prompt washing with soap and water may prevent a reaction.

RISK ACTIVITIES FOR PHYTOPHOTODERMATITIS

294

Cosmetics

Tan promoters or perfumes containing bergamot oil (berlock dermatitis) or a fig leaf decoction

Fruit and vegetable processing

Canning celery or stocking celery in grocery stores Making lemonade or limeade, especially if selling it outside Squeezing lime juice for margaritas and other drinks or guacamole Applying wild carrot decoction to treat foot swelling (China)

Gardening

Brushing against Dictamnus spp. (“gas plant/burning bush”) (US, Europe, N China) or Ruta (UK) Cultivating celery, parsnip or parsley Clearing weeds with a “weed-whacker” (US) or “strimmer” (UK) Pruning or harvesting figs Growing Angelica for herbal medicine (Korea), cake decorating (when candied), tonic and flavoring in wines (esp. Benedictine, US)

Hiking

Through fields and riverbanks (Heracleum spp.) (Pacific NW, Europe) Hiking in southern California and Baja California (Cneoridium dumosum, coast spice bush [Rutaceae])

Ingestion

Ingestion of massive quantities of psoralens (esp. celery) before UVA tanning Eating selemez (wild spinach, Chenopodium album [Chenopodiaceae]) – native in Europe and Asia, cultivated widely; sensitizing chemical unknown

Medications

Excessive exposure to UV radiation after taking or applying psoralens for PUVA Application of rue (Ruta spp.) as an insect repellant

Play

Making peashooters with Heracleum spp. Playing among rue bushes or Apiaceae Using psoralen-containing plants as “weapons” Wearing lei of Pelea anisata (Hawaii)

Table 17.9 Risk activities for phytophotodermatitis.  

(See Ch. 14) Members of the Anacardiaceae and Asteraceae families represent the most common causes of allergic contact dermatitis due to plants.

Epidemiology

on the leaves of plants (Fig. 17.7E), and the “black-spot test” helps identify toxic Anacardiaceae, but performing it also increases one’s likelihood of contracting a nasty dermatitis! A stone is used to thoroughly crush plant contents, especially the leaf stalks, between folds of white paper. Urushiol turns dark brown within 10 minutes and black by 24 hours.

Allergenic Anacardiaceae

Anacardiaceae and related families

Key features ■ Poison ivy/poison oak plant identification Compound leaves with three leaflets Flowers or fruit arise from axillary position Black dots of urushiol often present on leaves and fruit Common poison ivy climbs as a vine with hairy aerial roots ■ Allergens are long-chain catechols and resorcinols found in the urushiol oleoresin

•• ••

Members of the Anacardiaceae family cause more allergic contact dermatitis than all other plant families combined. Most allergenic family members belong to the genus Toxicodendron (meaning “poison tree”).

Toxicodendron identification

Compound Toxicodendron leaves possess three or more odd-numbered leaflets14. Flowers and fruit arise in an axillary position in the angle between the leaf and the twig from which it arises (Fig. 17.7A,B). The leaf stalk is enlarged at its origin from the supporting twig and leaves a “U”- or “V”-shaped scar after it falls off. Green fruit turn off-white when mature. Plants cling to trees via “hairy” aerial rootlets (Fig. 17.7C,D). Toxicodendron oleoresin contains urushiol and the enzyme laccase which oxidizes urushiol to form an insoluble, black, plastic-like polymer with great tensile strength. Black spots are commonly found

As noted in Table 17.10, there are two species each of poison ivy and poison oak and one species of poison sumac that are common to the US (Fig. 17.8). Some have multiple subspecies. Poison oak and poison ivy are weeds that grow along roads, trails or streams; they possess three (or occasionally five) leaflets per leaf. Poison sumac contains 7–13 leaflets per leaf (see Fig. 17.7A). Young leaves are frequently red in color, and the mature fruit (drupes) are tan or cream-colored and hairless (young fruit has hair). Classically, poison ivy leaves have pointed tips and are ovate (widest point below the center). Poison oak leaves usually have rounded ends. Western poison oak has oval leaves, whereas Eastern poison oak has variable leaf appearances that can mimic white oak leaves. Virtually all portions of the plant can induce dermatitis, even in the winter. The “winter” shape of poison ivy on fence posts resembles “Medusa heads” that are identifiable while driving down the highway. Strongly suspect any vine climbing by hairy aerial rootlets that is connected at the bottom to a tree or log. In snow, Western poison ivy grows so low to the ground that the upward, tine-like branches may be the only clue to its identification. The cashew nut tree (Anacardium occidentale) grows in the tropics worldwide. The nuts contain an oily, brown juice between the two layers of its shell. Contact with the concentrated phenols in the nutshell and bark leads to an immediate vesicant reaction. Any part of the tree, except the nut, can cause dermatitis. Mango (Mangifera indica) is the most popular fruit tree in tropical and subtropical America, and some 35 species grow throughout Southeast Asia. The leaves, bark, stems and fruit skin contain sensitizing resorcinols. Peeling the fruit before eating it typically prevents allergic contact dermatitis, although allergy to mango pulp has been demonstrated; the pulp allergens appear to be distinct from the resorcinols.

CHAPTER

17 Dermatoses Due to Plants

ALLERGIC CONTACT DERMATITIS

IDENTIFICATION OF POISON IVY, OAK AND SUMAC

Poison ivy Western poison oak

B C

Eastern poison oak

A

Poison sumac

D

E

Fig. 17.7 Characteristic features useful for identifying poison ivy, poison oak and poison sumac. A Shapes and numbers of leaflets and appearance of fruit (drupes). B Shrub type poison ivy (T. radicans) with flowers arising from an axillary position just below point where leaf attaches to stem. Leaves possess three leaflets (“Leaves of three, let them be” or “One, two, three, don’t touch me”). C, D Climbing vine of poison ivy (T. radicans) on an oak tree demonstrating aerial roots that anchor the vine to the tree; close-up of vine anchored to tree bark by fine hair-like aerial roots (“Hairy rope, don’t be a dope”). E Shrub type poison ivy (T. radicans) with black spots on leaflets. Leaf trauma (e.g. wind, rain, trampling by animals or people) allows urushiol to reach the surface, oxidize, and turn black.  

295

SECTION

Papulosquamous and Eczematous Dermatoses

3

MOST COMMON ALLERGENIC MEMBERS OF THE ANACARDIACEAE FAMILY AND MEMBERS OF TWO OTHER PLANT FAMILIES THAT ALSO CONTAIN URUSHIOL CROSS-REACTING CHEMICALS

Binomial name

Common name

Notes

Toxicodendron radicans

Common or Eastern poison ivy

Eastern half of USA Climbs trees with aerial rootlets Some subspecies in Mexico, Japan, China

Toxicodendron rydbergii

Northern or Western poison ivy

Western half of USA (except CA) and northern border states Non-climbing shrubs

Smodingium argutum

South African poison ivy

South Africa

Toxicodendron toxicarium

Eastern poison oak

Southeast USA

Toxicodendron diversilobum

Western poison oak

Pacific Coast of USA Usually a shrub but can climb

Toxicodendron vernix

Poison sumac

Eastern third of USA Not a weed Grows in standing water

Anacardium occidentale

Cashew nut tree

Tropical Americas Highest concentration of allergen in oil in middle layer of nut shell

Mangifera indica

Mango tree

Tropics

Metopium toxiferum

Poisonwood tree

Caribbean basin

Semecarpus anacardium

Indian marking nut tree

Southeast Asia, Pacific Islands, Australia Used to mark laundry in India (“dhobie mark dermatitis”) and used topically as herbal remedy for dermatitis, tattoo removal

Toxicodendron verniciflua

Japanese lacquer tree

Japan and China Resin used to lacquer wood products

Gluta renghas

Rengas tree

Malaysia lumber source

Schinus terebinthifolius

Brazilian pepper tree or Florida holly

Native to South America, but now a problem in southern Florida, Hawaii, Central America, the Pacific Rim and Pacific Islands

Ginkgo biloba (Ginkgoaceae)

Ginkgo tree

Cultivated worldwide in temperate climates – only the seed coat is allergenic

Grevillea spp. (Proteaceae)

Spider flower, silk oak, Hawaiian tree, kahili tree

Widely cultivated Australian natives

Cross reactors

Table 17.10 Most common allergenic members of the Anacardiaceae family and members of two other plant families that also contain urushiol crossreacting chemicals.  

Hawaiian natives rarely react to mango, perhaps because early oral exposure induces immunologic tolerance. The Florida holly (Schinus terebinthifolius, Brazilian pepper tree) is probably the most common cause of allergic contact dermatitis in southern Florida. The sap and crushed berries possess a variety of sensitizing catechols and resorcinols. Although the mango, cashew and Brazilian pepper trees are incredibly common throughout Latin America, dermatitis to them there is rare, in contrast to the frequent reactions seen in US residents. The main allergens in toxicodendrons are catechols, whereas those in the listed trees are resorcinols, and catechols possess greater allergenicity than resorcinols. Early cutaneous exposure to catechols may allow crossreactions to other Anacardiaceae, whereas early oral exposure to resorcinols may induce a state of tolerance. The 15–20 meter tall Japanese lacquer tree (Toxicodendron vernici­ flua) produces a thick, self-melanizing, viscous bark sap used for varnishing wood. Because polymerized urushiol remains in the lacquer, it maintains its allergenicity for many years. Patients allergic to poison ivy usually react to Japanese lacquer tree catechols. In a survey of 232 lacquer craftsmen, 189 (81%) developed dermatitis from the lacquer, but 83% of these reactions resolved with continued lacquer exposure (natural hyposensitization)15. Other common urushiol-containing Anacardiaceae family members include Smodingium argutum (African poison ivy) in South Africa, Toxicodendron striatum (Manzanillo tree) in Colombia, and Lithraea caustica (Litre tree) in central Chile.

Cross-reactors from other families 296

The seed of the Ginkgo tree (Ginkgo biloba), the only living member of the family Ginkgoaceae, possesses the allergenic catechol ginkgolic

acid. Because of the tree’s large size, beauty and resistance to air pollution, male ginkgo trees are widely grown in suburban North America and Europe. The yellowish seeds of female trees disintegrate, forming butyric acid, which smells like rancid butter. Contact with the soft outer layer (pulp) of the seed causes the vast majority of allergic reactions. Dermatitis following contact with the seed kernel, seed shell and leaves has been reported, but these parts likely only cause irritant reactions. Handling the intact seed (without the seed pulp) (Fig. 17.9) supposedly does not cause dermatitis in sensitized individuals. The unique, fanshaped leaf makes the ginkgo easy to recognize. The genus Grevillea (Proteaceae) includes 250 plant species common to Australia that contain pentadecylresorcinol. Having no side-chain double bonds, it is less allergenic than poison ivy and poison oak allergens. The flower of the Hawaiian kahili tree (Grevillea banksii) is a significant cause of allergic contact dermatitis in Hawaii.

Asteraceae and related families

Key features ■ Asteraceae (Compositae) identification Flower head with all strap-like florets (e.g. dandelion) Flower head with small, central tubular florets and peripheral strap-like florets (e.g. daisy, sunflower) Leaf-like bracts surround undersurfaces of flowers ■ Allergens are sesquiterpene lactones (SQLs)

•• •



GEOGRAPHIC RANGE OF TOXICODENDRON SPECIES US range of T. radicans subspecies

CHAPTER

17 Dermatoses Due to Plants

Fig. 17.9 Leaves and seeds of Ginkgo biloba. Only the fresh seed covering contains the allergen, ginkgolic acid, which typically crossreacts with urushiol.

TYPICAL COMPOSITE FLOWER HEADS: FAMILY ASTERACEAE T. radicans ssp. verrucosum

T. radicans ssp. eximium

T. radicans ssp. pubens Ray (ligulate) floret

T. radicans ssp. negundo

Disc (tubular) floret

T. radicans ssp. radicans

US range of other Toxicodendron species

Receptacle

Whorl of bracts (involucre)

T. rydbergii (northern or western poison ivy)

A

B

C

D

T. diversilobum (western poison oak) T. vernix (poison sumac)

T. toxicarium (eastern poison oak)

Worldwide range of T. radicans subspecies

Fig. 17.10 Typical composite flower heads of members of the family Asteraceae (Compositae). Daisy (Leucanthemum spp.), demonstrating a composite flower head of numerous, tiny, yellow tubular florets centrally and white ray florets peripherally (A) as well as green leaf-like bracts beneath the flower head (B), both of which are characteristic of flower heads of the family Asteraceae. C A cushion chrysanthemum (X Dendranthema cvs), demonstrating all ray, or strap-like, florets. D A composite chrysanthemum (X Dendranthema cvs), demonstrating central yellow tubular florets and peripheral ray florets.  

Asteraceae identification

T. radicans ssp. Barkleyi T. radicans ssp. orientale

T. radicans ssp. divaricatum T. radicans ssp. hispidum

Fig. 17.8 Geographic range of Toxicodendron spp.  

The compound flower heads in this largest of all plant families (~24 000 species) are composed of clusters of tiny flowers (florets) subtended by a whorl of leaf-like bracts (Fig. 17.10). In some plants, an inner “disc” of short, tubular florets is surrounded by long, strap-like “ray” florets (see Fig. 17.10A). In some plants, all the florets are similar (see Fig. 17.10C).

Allergenic Asteraceae

The daisy family includes many troublesome weeds, ornamentals, herbaceous perennials, and vegetables (Table 17.11). In 1956, Parthenium hysterophorus (“congress grass”), a native of northeastern Mexico, accidentally traveled in a consignment of US wheat to India, where it found an inviting ecologic niche. It now infests

297

SECTION

Papulosquamous and Eczematous Dermatoses

3

SOME OF THE MORE THAN 200 ALLERGENIC MEMBERS OF ASTERACEAE (COMPOSITAE) FOUND THROUGHOUT TEMPERATE WORLD CLIMATES

Category

Binomial name

Common name

Notes

Wild flowers and weeds

Achillea millefolium

Yarrow, milfoil

A cause of allergic contact “strimmer” or “weed-whacker” dermatitis

Ambrosia spp.

American ragweeds

Allergic contact dermatitis throughout growing season; allergic rhinitis only during pollen season

Arnica montana

Arnica, mountain tobacco

Artemisia vulgaris

Mugwort

Helenium autumnale

Sneezeweed

Iva spp.

Marsh elder, swamp weed

Parthenium hysterophorus

Scourge of India, congress grass, wild feverfew

Tanacetum cinerarilifolium

Pyrethrum

Tanacetum vulgare

Tansy

Tanacetum parthenium

Feverfew

Perhaps the best single plant to screen for SQL allergy Airborne contact dermatitis after mowing

Ornamental flowers

In herbal medicine*

Vegetables

Grows in temperate climates worldwide

Probably most common cause of Asteraceae dermatitis worldwide; Australian and Danish “bush dermatitis”; parthenin is primary SQL

Taraxacum officinale

Dandelion

Dahlia spp.

Dahlia

X Dendranthema cultivars

Chrysanthemum

Common cause of SQL dermatitis; florists remove dead flowers (“dead-head”) to encourage more blooms

Helianthus annuus

Sunflower

Windblown trichomes can cause airborne contact dermatitis

Rudbeckia hirta

Black-eyed Susan

Calendula officinalis

Pot marigold

Chamaemelum nobile

Sweet/Roman chamomile

Inula helenium

Elecampane

Cichorium endiva

Endive

Cichorium intybus

Chicory

Cynara scolymus

Globe artichoke

Lactuca sativa

Lettuce

*Also Achillea millefolium, Arnica montana, Helianthus annuus, Tanacetum parthenium, Tanacetum vulgare, Taraxacum officinale. Table 17.11 Some of the more than 200 allergenic members of Asteraceae (Compositae) found throughout temperate world climates. SQL, sesquiterpene lactone.  

approximately two million hectares within India as well as large areas of the Americas, South Africa, Madagascar, eastern Australia, and the Pacific Islands. Unlike South American P. hysterophorus, the Indian plant contains high concentrations of SQLs and is likely the most common cause of Asteraceae dermatitis in the world.

bonds (a diolefin), only 35% respond to the C15 catechol with an unsaturated side chain (pentadecylcatechol). Therefore, pentadecylcatechol, which is easily synthesized, is an inappropriate patch test allergen for Anacardiaceae sensitivity, because the diolefin is the major component in poison ivy and poison oak urushiols.

Cross-reactors from other families

Asteraceae allergens

Allergic reactions to SQLs occur following contact with tulip poplar bark (Liriodendron tulipifera) and Magnolia trees (Magnoliaceae); liverworts (Frullania spp. [Jubulaceae]) in the Pacific Northwest; and leaves of the bay laurel tree (Laurus nobilis [Lauraceae]), a Mediterranean basin native.

Pathogenesis Anacardiaceae allergens

298

The allergenic substance urushiol derives its name from the Japanese word for the sap (kiurushi) of the Japanese lacquer tree (T. verniciflua). It contains a mixture of catechols (1,2-dihydroxybenzenes) and resorcinols (1,3-dihydroxybenzenes) that avidly binds to skin16. Catechols and their alkyl side chains are immunologically inert. However, combining them produces potent sensitizers17. The immunologic activity of alkyl side chains results from weak van der Waals forces. Longer side chains increase irritancy and allergenicity; location of the catechol ring at position 3 increases antigenicity, but placement at position 6 induces tolerance. Although virtually all individuals who are allergic to poison ivy react to the C15 catechol with two double

The major sensitizers, sesquiterpene lactones (SQLs), are found in the leaves, stems and flowers, and they are composed of a sesquiterpene (C15H24) and a lactone ring (cyclic ester). Direct plant contact, botanical extracts in skin care products and cosmetics, and dry airborne plant parts including pollen can transfer SQLs to individuals. Over 5000 SQLs have been described, of which about 4000 are potentially allergenic. The composition of SQLs produced by any species varies according to location and weather. Patch testing for SQL allergy has traditionally relied on the SQL mix consisting of three SQLs or the “Compositae mix” of non-standardized extracts from five species of Asteraceae. The SQL mix has a falsenegative rate of 65–70% in SQL-allergic patients, while the Compositae mix has a false-negative rate of 15–65%. The SQLs present in these mixtures are poorly representative of the diversity of SQL structures, and a new SQL mix II (costunolide, helenalin, arteglasin A, lactucopicrin, nobilin, and cnicin) has been formulated to take advantage of the three-dimensional variability in SQLs18. Until this new proposed mix has been verified, a combination of the original SQL mix, commercially available Compositae mix and parthenolide, which detects 96% of known SQL allergic individuals, can be utilized19. Ideally, patients who

Clinical Features Anacardiaceae dermatitis

Key features ■ Urushiol is a partially water-soluble allergen that must be washed off quickly ■ Treat for at least 2 weeks, otherwise rebound dermatitis commonly occurs ■ Eruption “progresses” to “new areas” because of variability in antigen concentration and stratum corneum thickness

Lightly brushing against uninjured leaves is innocuous, since plants must be damaged to release urushiol. However, in the late fall, plants spontaneously release urushiol (see Fig. 17.7E). In addition, contaminated clothing, pets, lacquered furniture, sawdust and smoke (potentially causing severe respiratory tract inflammation, dermatitis, and even temporary blindness) can transfer urushiol. After urushiol contact, a sensitized person typically develops an erythematous, pruritic eruption within 2 days (4–96 hours) that peaks within 1–14 days20,21. However, dermatitis may occur up to 3 weeks after primary contact or within hours of secondary contact. Streaks of erythema and edematous papules typically precede vesicles and bullae (Fig. 17.11A,B). If the antigen load is lower, only erythematous, edematous reactions may be seen (Fig. 17.11C). Although allergic contact dermatitis is the most common cause of such a streaky, vesicular dermatitis, plants may cause this picture by other means (e.g. chemical irritant dermatitis or the initial phase of phytophotodermatitis). Patch tests of bulla fluid are routinely negative. The illusion that this fluid propagates the eruption results from variations in the time it takes for a clinical reaction to occur at different sites that have received differing antigen loads and have variable stratum corneum thicknesses.

Erythema multiforme appears to be an underreported sequela of severe poison ivy reactions that may appear 2 weeks following onset of the dermatitis (Table 17.12)22. Uncommonly, nephritis or eruptions resembling measles, scarlatina or urticaria develop and are ascribed to immune complex deposition. Without treatment, poison ivy dermatitis lasts about 2–3 weeks. Prolonged postinflammatory hyperpigmentation may occur in darkly pigmented individuals. Over 70% of the US population react to poison ivy allergens after patch testing, but only 50% react to plants in nature. Interestingly, only 15% of atopic persons are sensitive, and studies suggest that sensitivity is hereditary. Urushiol-sensitive AIDS patients with CD4+ counts 40 as compared to those with neither risk factor.

Outdoor Workers Among outdoor workers, poison ivy and poison oak (Toxicodendron spp.) are the main causes of occupational contact dermatitis. Toxico­ dendron contact accounts for 10% of all lost-time injuries for the US Department of Agriculture Forest Service. Foresters, especially when fighting forest fires, have virtually no control over avoiding these plants. Up to 25% of firefighters need to leave the fire line because of severe Toxicodendron dermatitis. Forestry workers in the American and Canadian Pacific Northwest may develop “woodcutter’s eczema”, an allergic contact dermatitis caused by airborne or rainwater-dispersed SQLs from liverworts (Frul­ lania spp.) growing on trees and rocks. The dermatitis is worse in wet winter months and presents in a pseudo-photodistribution, involving the upper eyelids while sparing the submental area.

DERMATOSES ERRONEOUSLY ASCRIBED TO PLANTS Organisms that are neither animal nor plant belong to one of the following kingdoms: Monera – unicellular prokaryotes (anuclear); includes bacteria and blue-green algae (cyanobacteria) Fungi – multicellular, heterotrophic (absorb food) eukaryotes (possess nuclei); lack cilia or flagella Protista – unicellular eukaryotic protozoans and algae Reactions to these organisms can be falsely ascribed as reactions to plants.

• • •

Lichen Dermatitis45 Lichens are composite organisms consisting of a fungus and a photo­ synthetic partner, usually a green or blue-green alga. In the Pacific Northwest, the fungal component of lichens growing on trees, rocks or soil disperses usnic acid, atranorin and everinic acid onto foresters or other passersby via either direct contact or rainwater. This leads to allergic contact dermatitis in a pseudo-photodistribution. These three lichen acids are found in the common fragrance constituent oak moss absolute, and they can also cause photoallergic contact dermatitis. Oak moss absolute is one of eight ingredients in the fragrance mix I

GLOBAL PERSPECTIVE – PLANT DERMATOSES MOST COMMONLY OBSERVED BY DERMATOLOGISTS IN VARIOUS COUNTRIES

302

Country

Plants/Types of reactions

Australia

Lyngbya majuscula (seaweed dermatitis)/ICD

Dendrocnide tree/TMU

Melaleuca (tea tree oil)/ACD

Brazil

Anacardium occidentale/ACD

Mangifera indica/ACD

Schinus terebinthifolius/ACD

Canada

Lichen (woodcutter’s eczema)/ACD

Frullania (woodcutter’s eczema)/ACD

Toxicodendron spp. (poison ivy)/ACD

Chile

Lithraea caustica/ACD

Ruta graveolens/PPD

Urtica spp./TMU

China

Toxicodendron vernicifluum/ACD

Mangifera indica/ACD

Ginkgo biloba/ACD

Colombia

Toxicodendron striatum/ACD

Alstroemeria spp./ACD

India

Parthenium hysterophorus/ACD

Chrysanthemum spp./ACD

Italy

Ficus carica/ICD, MID, PPD

Japan

Toxicodendron vernicifluum/ACD

Lebanon

Chrysanthemum spp./ACD

Philippines

Lyngbya majuscula (seaweed dermatitis)/ICD

Anacardium occidentale/ACD

South Africa

Smodingium argutum/ACD

Alstroemeria spp./ACD

Chrysanthemum spp./ACD

United States

Toxicodendron spp. (poison ivy/oak)/ACD

Alstroemeria spp./ACD

Chrysanthemum spp./ACD

Uzbekistan

Ficus carica/ICD, MCD, PPD

Tomato leaves (Solanum lycopersicum)/ACD, TMU

Chelidonium majus [Papaveraceae] (Greater celandine)/ICD

Primula obconica/ACD

Table 17.13 Global perspective – plant dermatoses most commonly observed by dermatologists in various countries. Note that Lyngbya maluscula is an alga. ACD, allergic contact dermatitis; ICD, irritant contact dermatitis; MID, mechanical irritant dermatitis; PPD, phytophotodermatitis; TMU, toxin-mediated urticaria.  

Chlorella Photodermatitis Ingestion of Chlorella, a nutritional supplement grown in Taiwan and Japan, can cause photodermatitis. Chlorella is a single-celled green alga that produces pheophorbide A, a photosensitizing breakdown product of chlorophyll that has been used experimentally for photodynamic therapy.

Seaweed Dermatitis

46

While there are over 3000 species of seaweed, the unicellular blue-green alga Lyngbya majuscula is the primary species that causes a chemical irritant contact dermatitis (due to aplysiatoxin and debromoaplysiatoxin). Usually growing in fine blackish-green to olive-green strands up to 30 cm long, it looks like matted hair or felt and can get caught under bathing or wet suits. Within minutes of contact, genitalia and

buttocks develop erythema, pruritus, and edema. Pustules and several days of desquamation often follow. Seaweed dermatitis is primarily a problem during algal blooms stimulated by pollution and overfishing. In temperate and tropical oceans around the world, Lyngbya has been observed in intertidal zones up to a depth of 30 meters.

Pseudo-Phytodermatitis From Plant Hitchhikers Allergic and irritant chemical reactions may occur from insecticides and other chemicals used to prevent horticultural or agricultural damage. Contaminating arthropods such as the hay itch mite (Pyemotes spp.) found in grains can cause pruritic wheals in dock workers, farmers, packers and storers of grain (see Ch. 85). Paraphenylenediamine added to henna tattoos can induce allergic contact dermatitis. Allergic contact dermatitis due to normal plant tissue levels of nickel have been reported for Euphorbia triangularis (Euphorbiaceae) and the freshwater plant Ludwigia repens (Onagraceae).

CHAPTER

17 Dermatoses Due to Plants

and is responsible for almost 40% of positive reactions to this fragrance mix.

REFERENCES 1. McGovern TW. The language of plants. Am J Contact Dermat 1999;10:45–7. 2. Mitchell JC. Patch testing to plants. Clin Dermatol 1986;4:77–82. 3. Simpson EL, Law SV, Storrs FJ. Prevalence of botanical extract allergy in patients with contact dermatitis. Dermatitis 2004;15:67–72. 4. Lahti A. Contact urticaria to plants. Clin Dermatol 1986;4:127–36. 5. Kondo Y, Urisu A. Oral allergy syndrome. Allergol Int 2009;58:1–7. 6. Janssens V, Morren M, Dooms-Goossens A, Degreef H. Protein contact dermatitis: myth or reality? Br J Dermatol 1995;132:1–6. 7. Anderson BE, Miller CJ, Adams DR. Stinging nettle dermatitis. Am J Contact Dermat 2003;4:44–6. 8. Lindsey D, Lindsey WE. Cactus spine injuries. Am J Emerg Med 1988;6:362–9. 9. Bruynzeel DP. Bulb dermatitis: dermatological problems in the flower bulb industries. Contact Dermatitis 1997;37:70–7. 10. Brenner S, Landau M, Goldberg I. Contact dermatitis with systemic symptoms from Agave americana. Dermatology 1998;196:408–11. 10a.  Son JH, Jin H, You HS, et al. Five cases of phytophotodermatitis caused by fig leaves and relevant literature review. Ann Dermatol 2017;29:86–90. 11. De Almeida HL Jr, Sotto MN, de Castro LAS, Rocha NM. Transmission electron microscopy of the preclinical phase of experimental phytophotodermatitis. Clinics (Sao Paulo) 2008;63:371–4. 12. Birmingham DJ, Key MM, Tublich GE. Phototoxic bullae among celery harvesters. Arch Dermatol 1961;83:73–87. 13. Victor FC, Cohen DE, Soter NA. A 20-year analysis of previous and emerging allergens that elicit photo allergic contact dermatitis. J Am Acad Dermatol 2010;62:605–10. 14. Guin JD, Beaman JH. Toxicodendrons of the United States. Clin Dermatol 1986;4:137–48. 15. Kawai K, Nakagawa M, Kawaki K, et al. Hyposensitization to urushiol among Japanese lacquer craftsmen: results of patch tests on students learning the art of lacquerware. Contact Dermatitis 1991;25:290–5. 16. Mitchell J. The poisonous Anacardiaceae of the world. Adv Econ Botany 1990;8:103–29. 17. Kalish RS. Poison ivy dermatitis: pathogenesis of allergic contact dermatitis to urushiol. In: Progress in Dermatology, vol. 29. Evanston, IL: Dermatology Foundation; 1995. p. 1–12. 18. Jacob M, Brinkmann J, Schmidt TJ. Sesquiterpene lactone mix as a diagnostic tool for Asteraceae allergic

contact dermatitis: chemical explanation for its poor performance and Sesquiterpene lactone mix II as a proposed improvement. Contact Dermatitis 2012;66:233–40. 19. Paulsen E, Andersen KE. Sensitization patterns in Compositae-allergic patients with current or past   atopic dermatitis. Contact Dermatitis 2013;68:  277–85. 20. Fisher AA. Poison ivy/oak/sumac. Part II: specific features. Cutis 1996;58:22–4. 21. Williams JV, Light J, Marks JG Jr. Individual variations in allergic contact dermatitis from urushiol. Arch Dermatol 1999;135:1002–3. 22. Werchniak AE, Schwarzenberger K. Poison ivy: an underreported cause of erythema multiforme. J Am Acad Dermatol 2004;51(5 Suppl.):S159–60. 23. Smith KJ, Skelton HG, Nelson A, et al. Preservation of allergic contact dermatitis to poison ivy (urushiol) in late HIV disease. The implications and relevance to immunotherapy with contact allergens. Dermatology 1997;195:145–9. 24. Kurlan JG, Lucky AW. Black spot poison ivy: a report of 5 cases and a review of the literature. J Am Acad Dermatol 2001;45:246–9. 25. Paulsen E, Christensen LP, Andersen KE. Compositae dermatitis from airborne parthenolide. Br J Dermatol 2007;156:510–15. 26. Jacobi U, Engel K, Patzelt A, et al. Penetration of pollen proteins into the skin. Skin Pharmacol Physiol 2007;20:297–304. 27. Moller H, Spiren A, Svensson A, et al. Contact allergy to the Asteraceae plant Ambrosia artemisiifolia L. (ragweed) in sesquiterpene lactone-sensitive patients in southern Sweden. Contact Dermatitis 2002;47:157–60. 28. Handa S, De D, Mahajan R. Airborne contact dermatitis - current perspectives in etiopathogenesis and management. Indian J Dermatol 2011;56:700–6. 28a.  Paulsen E. Systemic allergic dermatitis caused by sesquiterpene lactones. Contact Dermatitis 2017;76:1–10. 29. Frain-Bell W. Photosensitivity and Compositae dermatitis. Clin Dermatol 1986;4:122–6. 30. Menage HD, Hawk JLM, White IR. Sesquiterpene lactone mix contact sensitivity and its relationship to chronic actinic dermatitis: a follow-up study. Contact Dermatitis 1998;39:119–22. 31. Fisher AA. Poison ivy/oak dermatitis. Part I: prevention – soap and water, topical barriers, hyposensitization. Cutis 1996;57:384–6. 32. Williford PM, Sheretz EF. Poison ivy dermatitis: nuances in treatment. Arch Fam Med 1994;3:184–8.

33. Davila A, Lucas J, Laurora M, et al. A new topical agent, Zanfel, ameliorates urushiol-induced Toxicodendron allergic contact dermatitis. Ann Emerg Med 2003;42(4 Suppl. 1):601. 34. Prok L, McGovern TW Poison ivy (Toxicodendron) dermatitis. . Last updated Jan 22, 2014. 35. Marks JG Jr, Fowler JF Jr, Sheretz EF, Rietschel RL. Prevention of poison ivy and poison oak allergic contact dermatitis by quaternium-18 bentonite. J Am Acad Dermatol 1995;33:212–16. 36. Burke DA, Corey G, Storrs FJ. Psoralen plus UVA protocol for Compositae photosensitivity. Am J Contact Dermat 1997;7:171–6. 37. McGovern TW. Alstroemeria L (Peruvian lily). Am J Contact Dermat 1999;10:172–6. 38. Hausen BM. Evaluation of the main contact allergens in oxidized tea tree oil. Dermatitis 2004;15:213–14. 38a.  Mortimer S, Reeder M. Botanicals in dermatology: essential oils, botanical allergens, and current regulatory practices. Dermatitis 2016;27:317–24. 38b.  Jack AR, Norris PL, Storrs FJ. Allergic contact dermatitis to plant extracts in cosmetics. Semin Cutan Med Surg 2013;32:140–6. 39. Ismail M, Maibach HI. The clinical significance of immunological contact urticaria to processed grains. Indian J Dermatol Venereol Leprol 2012;78:591–4. 40. Gimeno PM, Iglesias AM, Vega ML, et al. Occupational wheat contact dermatitis and treatment with omalizumab. J Investig Allergol Clin Immunol 2013;23:287–8. 41. Santucci B, Picardo M. Occupational contact dermatitis to plants. Clin Dermatol 1992;10:157–65. 42. Paulsen E. Occupational dermatitis in Danish gardeners and greenhouse workers (II). Etiological factors. Contact Dermatitis 1998;38:14–19. 43. Paulsen E, Sogaard J, Andersen KE. Occupational dermatitis in Danish gardeners and greenhouse workers (III). Compositae-related symptoms. Contact Dermatitis 1998;38:140–6. 44. Vester L, Thyssen JP, Menne T, Johansen JD. Consequences of occupational food-related hand dermatoses with a focus on protein contact dermatitis. Contact Dermatitis 2012;67:328–33. 45. Aalto-Korte K, Lauerma A, Alanko K. Occupational allergic contact dermatitis from lichens in present-day Finland. Contact Dermatitis 2005;52:36–8. 46. Werner KA, Marquart L, Norton SA. Lyngbya dermatitis (toxic seaweed dermatitis). Int J Dermatol 2012;51:59–62.

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Urticaria and Angioedema Clive E. H. Grattan and Sarbjit S. Saini

Synonyms:  ■ Wheals – hives, nettle rash ■ Angioedema – Quincke edema, angioneurotic edema

Key features ■ Urticaria is characterized by transient skin or mucosal swellings due to plasma leakage. Superficial dermal swellings are wheals, and deep swellings of the skin or mucosa are termed angioedema. Wheals are characteristically pruritic and pink or pale in the center, whereas angioedema is often painful, less well-defined, and shows no color change ■ There are several recognizable clinical patterns of urticaria and different causes. The latter include allergy, autoimmunity, drugs, dietary pseudoallergens, and infections. Many cases of spontaneous urticaria remain unexplained (“idiopathic”) even after an extensive evaluation. C1 esterase inhibitor deficiency needs to be considered as a cause of recurrent angioedema without wheals ■ Diagnosis is based primarily on the history and clinical examination. Determination of the etiology or triggers, as well as exclusion of other diagnoses, may require further investigations, including blood tests, physical and dietary challenges, skin tests, and skin biopsy ■ Urticaria is a common disorder that may cause considerable distress and last for years, but the symptoms can usually be alleviated by appropriate management

INTRODUCTION Urticaria is a common reason for patients to present to primary care practitioners, emergency rooms, dermatologists, and allergists. It is characterized by the rapidity of its fluctuation. As a rule, individual wheals last no more than 24 hours, but the entire affliction usually lasts much longer. With nearly all clinical patterns of urticaria, wheals may be accompanied by angioedema, but the occurrence of isolated angioedema (without wheals) is of special significance because some of these patients will have a deficiency of C1 esterase inhibitor (C1 inh). The latter is due to bradykinin formation rather than release of mast cell mediators. C1 inh deficiency is a rare disorder that is often inherited and because it can prove fatal without treatment must be considered in any patient with isolated angioedema. Urticarial vasculitis is an important disorder to exclude in patients with chronic urticaria. It is a systemic disease defined by damage to small blood vessels rather than transient vasodilation and vascular permeability (see Ch. 24). Urticarial vasculitis sometimes presents with wheals or angioedema that, without confirming a duration of more than 24 hours (by serial examination of marked lesions) and a lesional skin biopsy, are indistinguishable from other patterns of urticaria. While urticaria rarely progresses to anaphylaxis, wheals are often a feature of that condition. Good management of urticaria depends on a thorough understanding of etiologies, triggers and aggravating factors, in addition to the most appropriate drug therapies.

Definition of Urticaria 304

Urticaria is often used as a descriptive term for recurrent whealing of the skin, with angioedema being viewed as a physical sign. However, there is increasing acceptance that the term “urticaria” is more appro-

priately used to define a disease that may be acute or chronic. Thus, urticaria may present with wheals, angioedema, or both. Wheals are pruritic, pink or pale swellings of the superficial dermis that have an initial erythematous flare around them (Fig. 18.1). Lesions may be a few millimeters in diameter or as large as a hand, and the number can vary from a few to numerous. The hallmark of wheals is that individual lesions come and go rapidly, by definition, generally within 24 hours. Angioedema swellings occur deeper in the dermis and in the subcutaneous or submucosal tissue. They may also affect the oropharynx and rarely the bowel in hereditary angioedema. The areas of involvement tend to be normal or faint pink in color, painful rather than pruritic, larger and less well-defined than wheals, and they often last for 2 to 3 days (Fig. 18.2).

EPIDEMIOLOGY Depending on the age range and method of sampling, estimates of the lifetime prevalence of urticaria in the general population range from 8 to 22%1, with chronic urticaria ranging from 2 to 3% and having a point prevalence of 0.1–0.9%; the prevalence of specific subtypes of chronic urticaria, e.g. the inducible urticarias, is lower. Urticaria is a worldwide disease and may present at any age. The peak incidence depends on etiology. The proportion of cases due to different etiologic agents is likely to relate to the frequency of environmental exposures, such as infections and allergens, in different countries, but estimates of this are not available. It is also often difficult to prove a cause and effect, and so an underlying condition may be inappropriately “blamed” for causing urticaria. Overall, urticaria is more common in women, with a female : male ratio of ~2 : 1 for chronic spontaneous urticaria, but the ratio varies with the different physical urticarias. For example, women outnumber men in dermographism and cold urticaria, but more men develop delayed pressure urticaria2. Hereditary angioedema has an autosomal dominant inheritance pattern and occurs in ~1 in 50 000 individuals, with a range that varies from 1 in 20 000 to 1 in 60 000.

PATHOGENESIS The Mast Cell Distribution and diversity The mast cell is the primary effector cell of urticaria. Mast cells are widely distributed throughout the body but vary in their phenotype and response to stimulation. This may explain why systemic features, such as those seen in anaphylaxis, do not accompany the activation of cutaneous mast cells in urticaria. The majority of mast cells in the skin and intestinal submucosa contain the neutral proteases tryptase and chymase (MCTC), whereas those in the bowel mucosa, alveolar wall, and nasal mucosa contain only tryptase (MCT). Both types, however, express high-affinity IgE receptors (FcεRI) and are therefore capable of participating in IgE-dependent allergic reactions3. There is conflicting evidence on the number of cutaneous mast cells in chronic urticaria, but there is agreement that they may be more likely to degranulate in response to certain stimuli, such as intradermal codeine injection4, and in this sense may be in general more “releasable”5. Little is known about the beneficial effects of mast cells, but there is some evidence that they may be involved in the innate immune response to infection, wound healing, and the neuroendocrine system. They have also been shown to help initiate the extracellular matrix formation and angiogenesis required for neurofibroma development (see Fig. 61.2).

Urticaria is characterized by transient skin or mucosal swellings due to plasma leakage. When the swelling is superficial within the dermis, pruritic wheals appear, whereas when deep, angioedema is seen. While urticaria often develop in the setting of anaphylaxis, patients who present with wheals rarely progress to anaphylaxis. Urticaria may be spontaneous or inducible, as well as acute or chronic. Acute spontaneous urticaria can have an allergic basis, but chronic spontaneous urticaria (CSU) usually does not. Although there is circumstantial evidence for an autoimmune etiology in approximately one-third of patients with CSU, many cases remain unexplained, i.e. are idiopathic. Nonsteroidal anti-inflammatory drugs, foods, alcohol, stress, and infections may aggravate CSU, but they are rarely the cause. Although inducible urticarias are defined based upon their trigger(s), the cause is unknown, with the exception of contact urticaria. The primary effector cell of urticaria is the mast cell, and histamine from mast cells is the major mediator of pruritus and wheals. Angioedema is usually due to release of mast cell mediators, but may be mediated by bradykinin if the angioedema is not accompanied by wheals as in hereditary angioedema and angiotensin-converting enzyme (ACE) inhibitor-induced angioedema. H1 antihistamines are the primary treatment of urticaria. Oral corticosteroids should only be used when rescue therapy is required. Immunosuppressives or omalizumab (anti-IgE antibody) are third-line options for H1 antihistamine-refractory CSU.

urticaria, spontaneous urticaria, inducible urticaria, acute urticaria, chronic urticaria, autoimmune urticaria, chronic spontaneous urticaria, angioedema, hereditary angioedema, angiotensin converting enzyme (ACE) inhibitor-induced angioedema, histamine, bradykinin, H1 antihistamine, omalizumab

CHAPTER

18 Urticaria and Angioedema

ABSTRACT

non-print metadata KEYWORDS:

304.e1

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18

A

B

C

Fig. 18.1 Wheals. Wheals can be small (A) or large in size and annular (B), but they still retain the classic central pallor and erythematous flare. C Occasionally, more uniform edematous plaques are seen. A, Courtesy, Jean L Bolognia, MD.  

Fig. 18.2 Angioedema. The swelling is deeper than wheals and may affect mucosal surfaces. Note the swelling of the lips and periorbital region and the lack of erythema.  

MAST CELL DEGRANULATING STIMULI

Allergen IgE Anti-FcεRI

Substance P Stem cell factor

IgE

C5a

Anti-IgE Codeine

Fig. 18.3 Mast cell degranulating stimuli. Both immunologic and nonimmunologic stimuli can lead to release of mediators. Stem cell factor is also known as KIT ligand.  

MEDIATORS RELEASED BY HUMAN DERMAL MAST CELL DEGRANULATION

Degranulating stimuli Cross-linking of two or more adjacent FcεRI on the mast cell membrane will initiate a chain of calcium- and energy-dependent steps leading to fusion of storage granules with the cell membrane and externalization of their contents. This is known as degranulation. Classic immediate hypersensitivity reactions involve binding of receptor-bound specific IgE by allergen. There are also several recognized immunologic degranulating stimuli that act through the IgE receptor, such as anti-IgE and anti-FcεRI antibodies (Fig. 18.3). However, not all autoantibodies with these specificities are functional, i.e. capable of releasing histamine from mast cells or basophils in vitro. In addition, because functional anti-IgE and anti-FcεRI autoantibodies have been identified in patients with other diseases such as systemic lupus erythematosus6 and occasionally in healthy controls, the role of functional autoantibodies in the pathogenesis of urticaria has been debated. Non-immunologic stimuli, including opiates, C5a anaphylatoxin, stem cell factor, and some neuropeptides (e.g. substance P), can cause mast cell degranulation by binding specific receptors, independent of the FcεRI (see Fig. 18.3).

Proinflammatory mediators Mast cell granules contain preformed mediators of inflammation, the most important of which is histamine (Fig. 18.4). A wide range of cytokines has been identified in human mast cells from different tissues, including tumor necrosis factor (TNF), interleukins (IL)-3,

Release of preformed mediators

Synthesis of newly formed mediators

Proteases e.g. tryptase

Prostaglandin D2 Leukotrienes C4, D4, E4

Heparin Histamine Cytokines e.g. IL-3,-4,-5,-6,-8,-13 GM-CSF; TNF

Platelet-activating factor

Fig. 18.4 Mediators released by human dermal mast cell degranulation. Both preformed and newly synthesized proinflammatory mediators are released from mast cells.  

-5, -6, -8 and -13, and granulocyte–macrophage colony-stimulating factor (GM-CSF). Synthesis and secretion are upregulated following FcεRI stimulation. TNF is expressed constitutively in resting human cutaneous mast cells. Prostaglandins and leukotrienes are synthesized from arachidonic acid derived from cell membrane phospholipids (see

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Fig. 130.6). The most important proinflammatory eicosanoids are prostaglandin (PG) D2 and the leukotrienes (LT) C4, D4, and E4 (slow releasing substance of anaphylaxis). PGE2 has inhibitory effects on immunologic mast cell degranulation and may therefore have a protective role in urticaria. Increased levels of TNF, IL-1β, -6, -10, -12p70, -13, and B-cell activating factor (BAFF) have been detected in the sera of urticaria patients7.

Blood Vessels Histamine and other proinflammatory mediators released upon degranulation bind receptors on postcapillary venules in the skin, leading to vasodilation and increased permeability to large plasma proteins, including albumin and immunoglobulins. Furthermore, histamine, TNF, and IL-8 upregulate the expression of adhesion molecules on endothelial cells, thereby promoting the migration of circulating inflammatory cells including eosinophils, basophils, neutrophils and Th0 cells from the blood into the urticarial lesion8.

Blood Autoantibodies Based upon in vitro assays, functional IgG autoantibodies that release histamine (and other mediators) from mast cells and basophils have been detected in the serum of 30–50% of patients with chronic spontaneous urticaria (CSU)9. The majority of these autoantibodies bind the extracellular α subunit of FcεRI. Those recognizing the α2 domain compete with IgE for the binding site, whereas non-competitive autoantibodies directed against the terminal α1 domain are able to bind the receptor in the presence of IgE (Fig. 18.5). Approximately 10% of chronic urticaria sera contain functional autoantibodies directed against the Fc portion of IgE itself (see Fig. 18.3). Binding of the autoantibodies to mast cells may initiate complement activation with the generation of C5a anaphylatoxin, which in turn facilitates or augments degranulation10. Other mast cell activating factors may also exist in urticaria sera, e.g. a non-IgG “mast cell-specific factor” has been described, although its identity remains unknown11. There is currently no evidence that characterized cytokines cause mast cell degranulation in urticaria. Evidence from small series of CSU patients treated with plasmapheresis12 or cyclosporine13 indicates that functional autoantibody levels correspond to disease severity.

IgE ANTIBODY BINDING TO THE HIGH-AFFINITY IgE RECEPTOR (FCεRI)

Leukocytes The importance of peripheral blood leukocytes in the pathogenesis of urticaria is becoming clearer. Blood basophils in CSU patients are less responsive in vitro to the immunologic stimulus anti-IgE, possibly through desensitization, and these cells are reduced in number14. These patients can be further classified into responders and non-responders based upon the release of histamine by their basophils in response to anti-IgE. The functional phenotype appears to remain stable during the course of the active illness, but then, during disease remission, the basophils become more responsive to anti-IgE15. Expression of the negative regulator SHIP (src homology 2-containing inositol phosphatase) is increased in the basophils from anti-IgE non-responders16, although the significance of this to the pathogenesis of chronic urticaria is unknown. Evidence has emerged that basophils are recruited into urticarial wheals17 and may sustain the inflammatory response by releasing histamine and other mediators, analogous to the delayed phase of immediate hypersensitivity reactions. Eosinophil, neutrophil, and lymphocyte numbers are normal in the peripheral blood, but these cells are often present in biopsy specimens from spontaneous wheals. Eosinophils may contribute to the persistence of wheals by generating LTC4, LTD4, and LTE4 and by releasing toxic granule proteins, including major basic protein (MBP), which can release histamine from basophils. The function of neutrophils and lymphocytes in urticaria has not been elucidated.

Nerves Substance P and other neuropeptides release histamine from mast cells in vitro and can induce a wheal and flare reaction in human skin when injected intradermally. Vasoactive intestinal polypeptide (VIP) caused a greater wheal reaction in those with chronic urticaria than did other skin-tested neuropeptides, but the relevance of this to urticaria is still uncertain.

Mechanisms of Urticaria Formation Mast cell-dependent urticaria Potential mechanisms for mast cell-dependent urticaria are included in Table 18.1. Cross-linking of the Fab portion of specific IgE on mast cells by percutaneous or circulating allergen undoubtedly accounts for some cases of acute or episodic urticaria (see Fig. 18.3), but this is probably never the cause of adult chronic continuous urticaria. Examples of the former would be contact urticaria from natural rubber latex and acute urticaria from foods, including nuts, fish, and fruit. However, the majority of acute urticaria cases do not relate to allergen exposure. IgE has been implicated in the pathogenesis of symptomatic dermo­ graphism, cold urticaria and solar urticaria, but the mechanism by which it renders skin mast cells more sensitive to physical stimulation is not certain. It is proposed that the physical stimulus in these patients

ETIOLOGIES AND PATHOMECHANISMS OF WHEALS AND/OR ANGIOEDEMA

IgE

Idiopathic Immunologic

α2

α1

Autoimmune (autoantibodies against FcεRI or IgE) IgE-dependent (allergic) • Immune complex (vasculitic) • Kinin- and complement-dependent (C1 esterase inhibitor deficiency) •

Cell membrane



α β γ

Direct mast cell-releasing agents (e.g. opiates) Vasoactive stimuli (e.g. nettle stings) • Aspirin, other nonsteroidal anti-inflammatory drugs, dietary pseudoallergens • Angiotensin-converting enzyme inhibitors •

FCεRI

Fig. 18.5 IgE antibody binding to the extracellular α subunit of the highaffinity IgE receptor (FcεRI). Histamine-releasing autoantibodies directed against the terminal α1 domain are able to bind the receptor in the presence of IgE and are therefore non-competitive, whereas those recognizing the α2 domain compete with IgE for the binding site.  

306

γ

Non-immunologic •

Table 18.1 Etiologies and pathomechanisms of wheals and/or angioedema. It is often difficult to know the exact pathogenesis of individual cases of urticaria, and many cases remain idiopathic after evaluation. See Figs 18.3 and 18.6.  

Mast cell-independent urticaria There are several recognized circumstances where angioedema or wheals are due to mechanisms that do not involve mast cells. These need special consideration because their management and prognosis are different. For example, prostaglandins are involved in the pathogenesis of some patterns of non-immunologic contact urticaria (e.g. to benzoic acid), and the latter can be suppressed by NSAIDs25. In the cryopyrin-associated periodic syndromes (CAPS; see below), patients often develop urticarial lesions. Systemic symptoms, such as fever, help to distinguish patients with autoinflammatory syndromes from those with CSU (see Ch. 45). The significant improvement that results from the administration of anakinra, an IL-1 receptor antagonist26, rilonacept, a fusion protein that contains the extracellular domain of the IL-1 receptor and functions as an IL-1 trap27, or canakinumab, a human anti-IL-1β monoclonal antibody28, points to the role of the cryopyrin inflammasome and its production of IL-1β (see Figs 4.2 and 45.13).

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18 Urticaria and Angioedema

and while some clinical studies of dietary pseudoallergen avoidance have given encouraging results, the proportion of complete responders confirmed by rechallenge is small24. Aspirin allergy as a cause of urticaria is much less common, and the proportion of patients with urticaria due solely to pseudoallergens is probably low. Understanding “idiopathic” urticaria remains an important challenge. From a clinical perspective, it should be regarded as a multifactorial problem, and searching for aggravating factors is just as important as looking for causes.

induces a neoantigen that reacts with specific IgE antibody bound to mast cells. An additional mechanism, such as neuropeptide release, could initiate or potentiate mast cell activation. Using electron microscopy, localized platelet clumping has been demonstrated in cold urticaria, and the release of platelet mediators, including plateletactivating factor (PAF) and platelet factor 4/CXCL4, could contribute to wheal formation. Cholinergic urticaria develops in response to stimulation of cholinergic sympathetic innervation of the sweat glands. How release of acetylcholine from the nerve endings leads to mast cell activation and histamine release is unknown. An allergy to sweat has been demonstrated by one group of investigators18. It has been proposed that pressure-induced wheals may be due to a late-phase reaction, but an antigen has never been identified. In three Lebanese families with autosomal dominant vibratory urticaria, a missense gain-of-function variant was detected in ADGRE2 which encodes adhesion G proteincoupled receptor E2. This was thought to lead to destabilization of the inhibitory interaction between the alpha and beta subunits of ADGRE2, leading to sensitization of mast cells to vibration-induced degranulation18a. The initiating event for spontaneous urticaria wheals is unclear but may involve plasma leakage due to local factors such as heat or pressure, which allows the extravasation of autoantibodies or IgE-directed antigens that then activate the IgE receptor, thus leading to mast cell degranulation and a subsequent urticarial response. As functional autoantibodies cannot be detected in ~70% of chronic urticaria sera by currently available tests, other mechanisms may operate in “nonautoantibody” urticaria, which, nevertheless, has a similar clinical presentation19. Increased plasma levels of prothrombin fragment 1 + 2 (F 1 + 2) and D-dimer (a measure of fibrinolysis) have been demonstrated in CSU20 and relate to disease severity, but the contribution of coagulation abnormalities to the pathogenesis remains unclear. There are other serum factors in CSU patients that can activate mast cell lines in vitro and lead to endothelial activation, independent of IgE receptors on mast cells and the presence of IgG21. A popular hypothesis is that dietary food additives and natural salicylates as well as nonsteroidal anti-inflammatory drugs (NSAIDs) may cause urticaria via the diversion of arachidonic acid metabolism from prostaglandin to leukotriene formation. How this leads to urticaria is not clear, but it is known that intradermal injections of LTC4, LTD4, and LTE4 cause whealing by a direct action on small blood vessels. There is some evidence from studies of rat peritoneal mast cells that PGE2 can have inhibitory effects on immunologic mast cell degranulation22, so a reduction in their formation may facilitate the latter. Aspirin can aggravate urticaria in up to 30% of patients with chronic disease23,

C1 esterase inhibitor (C1 inh) deficiency

C1 inh deficiency is usually hereditary, but may be acquired. Three types of hereditary angioedema (HAE) are now recognized (see Fig. 18.19). Types I and II are caused by mutations in one allele of the structural gene for C1 inh, resulting in reduced levels of C1 inh (85% of cases; type I) or reduced C1 inh function (15% of cases; type II). Because the mutations lead to levels that are 5–30% of normal (rather than the expected 50%) in patients with type I HAE, it is thought that there is trans inhibition of the normal allele or increased catabolism of C1 inh. Deficiency of C1 inh leads to loss of inhibition of factor XII (FXII; Hageman factor), resulting in the generation of bradykinin by the action of kallikrein on high-molecular-weight kininogen (Fig. 18.6). Activation of the C1 component of complement by proteolytic enzymes, including plasmin and FXIIa, leads to low levels of C4 in the serum, which is an almost constant feature between and during attacks in untreated patients. Of note, HAE with normal C1 inh activity, also known as type III HAE29, may be due to an activating mutation in one allele of

Fig. 18.6 Pathophysiology of hereditary and drug-induced angioedema. Angiotensin-converting enzyme (ACE) inhibitor-induced urticaria is believed to result from the inhibition of endogenous kininase and a subsequent increase in bradykinin. Icatibant and ecallantide have been approved for the emergency treatment of hereditary angioedema (HAE) as alternatives to C1 inh concentrate (derived from human plasma) or recombinant C1 inh (derived from milk of transgenic rabbits). Icatibant, a decapeptide, is a specific bradykinin B2 receptor antagonist. Ecallantide, a 60-amino acid recombinant protein, selectively inhibits kallikrein. Off label, icatibant has been used to treat ACE inhibitorinduced angioedema. Two forms of C1 inh, one of which is administered intravenously and the other subcutaneously, are approved for prevention of attacks. At the time of writing, twice-monthly administration of lanadelumab, a human monoclonal antibody that inhibits plasma kallikrein, is under investigation for prevention of attacks. *The active form of factor XII (Hageman factor) is XIIa. Kallikrein is formed from prekallikrein. ** †High-molecular-weight.  

PATHOPHYSIOLOGY OF HEREDITARY AND DRUG-INDUCED ANGIOEDEMA in HAE, type III

*

Factor XII (Hageman factor)

+

+

+ Fibrin Fibrin degradation products

Plasminogen

Plasmin

C1

Intrinsic coagulation system

Ecallantide

Activated C1rs

C42

Kallikrein

− C1 esterase inhibitor in HAE, type I, II

**

Kininogen†



Bradykinin

C2 Kinin



Icatibant







− Kininase II

− ACE inhibitor

Bradykinin B2 receptor

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Urticarias, Erythemas and Purpuras

4

the gene that encodes FXII, leading to increased formation of bradykinin. One possible explanation for the preponderance of women is the enhancement of transcription of this gene by estrogens. In addition, there is a positive feedback loop between kallikrein and FXII. Acquired deficiency of C1 inh may result from activation of C1q and the complement cascade in patients with B-cell lymphoproliferative disorders and plasma cell dyscrasias, or in those with autoimmune connective tissue diseases. This leads to consumption of C1 inh plus low serum levels of C1q as well as C4 (acquired, type I) or the formation of inhibitory autoantibodies directed against the C1 inh (acquired, type II). Angiotensin-converting enzyme (ACE) inhibitor-induced urticaria is believed to result from the inhibition of endogenous kininase II (also known as ACE), which leads to increased production of bradykinin via inhibition of its metabolism (see Fig. 18.6). It usually presents with angioedema, which is usually orofacial and may be life-threatening.

CLINICAL FEATURES Clinical Diversity It is important to distinguish urticaria from urticarial dermatoses, such as urticarial drug eruptions, eosinophilic cellulitis, and the urticarial phase of pemphigoid. The individual wheals of urticaria are “here today and gone tomorrow” (i.e. they generally last extensor forearms

Ch. 41

Annular erythema of Sjögren syndrome*

Annular erythematous plaques; favors face, arms, upper trunk; most common in Asian patients; anti-Ro antibodies

Ch. 45

See text Ch. 121

Granulomatous lesions Granuloma annulare

Skin-colored to pink annular and arcuate plaques with borders composed of multiple papules; favors acral and extensor sites

Palisading granulomas with altered collagen and mucin

Ch. 93

*Considered by some authors to be a form of SCLE. Table 19.1  Differential diagnosis of figurate erythema. Key clinical features and histologic findings are provided. Disorders in italics favor children. Additional conditions that can present with figurate erythema include Kawasaki disease (may be erythema marginatum-like), hereditary periodic fever syndromes (especially TNF receptor-associated periodic syndrome [TRAPS]; see Table 45.2), relapsing polychondritis, polymorphous light eruption, inflammatory vitiligo (including a papulosquamous variant), eosinophilic vasculitis, Sweet syndrome, neutrophilic eccrine hidradenitis, pyoderma vegetans (expanding pustular lesions) and leukemia cutis. AFB, acid-fast bacilli; BMZ, basement membrane zone; FTA-ABS, fluorescent treponemal absorption; GI, gastrointestinal; LE, lupus erythematosus; RPR, rapid plasma reagin; SCLE, subacute cutaneous LE. Continued

321

SECTION

Urticarias, Erythemas and Purpuras

4

DIFFERENTIAL DIAGNOSIS OF FIGURATE ERYTHEMA

Disorders

Clinical features

Histologic findings

Cross references

Transient individual lesions (typically lasting discoid), neonatal LE, mothers of boys with chronic granulomatous disease

Photosensitivity; favors face (discoid), extensor upper extremities/upper trunk (SCLE), periorbital area (neonatal LE); anti-Ro antibodies (SCLE, neonatal LE); erythema gyratum atrophicans transiens neonatale is considered a variant of neonatal LE

Vacuolar interface dermatitis; often periadnexal lymphohistiocytic inflammation

Ch. 41

Seborrheic dermatitis

Erythematous annular plaques with scaling; favors face and central chest

Psoriasiform epithelial hyperplasia, spongiosis, perivascular lymphocytes

Ch. 13

Psoriasis

Annular scaly plaques with slow expansion

Psoriasiform epithelial hyperplasia, parakeratosis, diminished granular layer, elongated rete ridges, neutrophils migrating into epidermis

Ch. 8

Ichthyosis linearis circumflexa of Netherton syndrome

Serpiginous or circinate erythematous plaques bordered by double-edged scale; trichorrhexis invaginata; atopic diathesis, elevated serum IgE

Psoriasiform features with hyperkeratosis and a well-developed granular layer

Ch. 57

Papulosquamous lesions

See text and Ch. 53 Ch. 9

Lesions with absence or variable presence of scale

322

Annular lichenoid dermatitis of youth

Red-brown annular patches or thin plaques with central hypopigmentation; favors groin and flanks; affects children and young adults

Lichenoid infiltrate; marked keratinocyte necrosis limited to the tips of rete ridges

Erythema papulatum centrifugum

Usually a single, large annulus on the trunk whose border is 2–6 cm in width and composed of small erythematous papules, papulovesicles or crusted papules; favors Japanese men

Mononuclear infiltrate around eccrine ducts within the epidermis and dermis; spongiosis

Secondary syphilis

Annular plaques with central hyperpigmentation; favors face; flu-like symptoms; additional cutaneous manifestations; positive for RPR and FTA-ABS

Perivascular and interstitial infiltrate with plasma cells; also lichenoid or granulomatous infiltrate, exocytosis

Ch. 82

Mycosis fungoides

Annular erythematous or hypopigmented plaques, some with scale; admixed with classic lesions; often pruritic

Infiltrate of atypical lymphocytes in the papillary dermis with epidermotropism

Ch. 120

Table 19.1  Differential diagnosis of figurate erythema. (cont’d)

CHAPTER

Disorders

Clinical features

Histologic findings

Cross references

Transientwith individual lesions (typically lastingof neutrophils; linear deposits of IgG and/or C3 in BMZ

Ch. 30

Linear IgA bullous dermatosis

Annular urticarial plaques; vesicles and bullae within border (“string of pearls”); pruritus

Subepidermal bullae with neutrophils > eosinophils; linear deposits of IgA in BMZ

Ch. 31

Epidermolysis bullosa simplex (especially Dowling– Meara subtype)

“Herpetiform” blisters in figurate array; episodic flares of migratory circinate erythema and blistering; K5 or K14 mutations

Intraepidermal split; eosinophilic inclusions within the keratinocytes

Ch. 32

Annular epidermolytic ichthyosis

Migratory, annular or polycyclic, erythematous plaques with superficial blistering/peeling and scaling at the border; episodic flares; K1 or K10 mutations

Epidermolytic hyperkeratosis

Ch. 57

Purpura annularis telangiectoides

“Cayenne pepper” petechiae and telangiectasias in annular configuration; favors legs

Capillary dilation and tight perivascular infiltrate of lymphocytes; extravasated erythrocytes; siderophages

Ch. 22

Acute hemorrhagic edema of infancy

Annular or targetoid, edematous, erythematous plaques that become purpuric; favors face, ears and extremities; febrile but non-toxic-appearing child 120 bpm

1

Cancer or hematologic malignancy

1

BSA involved on day 1 >10%

1

Serum urea level (>10 mmol/l)

1

Serum bicarbonate level (14 mmol/l)

SCORTEN 0–1

20

1

Mortality rate (%) 3.2

2

12.1

3

35.8

4

58.3

≥5

90

Fig. 20.8 Cutaneous features of toxic epidermal necrolysis (TEN). Characteristic dusky red color of the early macular eruption in TEN. Lesions with this color often progress to full-blown necrolytic lesions with dermal– epidermal detachment.

Table 20.6 SCORTEN. A prognostic scoring system for patients with toxic epidermal necrolysis. The score is based upon seven prognostic factors. BSA, body surface area. Modified from ref 80.

been created by an NIH working group to help standardize the collection of patient information78a. In TEN, factors correlated with poor outcome include increasing age and extent of epidermal detachment. In addition, the number of medications, elevation of serum urea, creatinine and glucose levels, neutropenia, lymphopenia, and thrombocytopenia have been statistically linked to poor outcome. Late withdrawal of the causative drug is also associated with a less favorable outcome. It has been estimated that prompt withdrawal of the offending drug reduces the risk of death by 30% per day51. SCORTEN is a severity-of-illness score for TEN, in which seven parameters with equal weight have been integrated to predict outcome (Table 20.6)48,79,80; one recent study suggested that it may underestimate mortality risk81. On average, death occurs in every third patient with TEN, and it is mainly due to infections (S. aureus and Pseudomonas aeruginosa). Massive transepidermal fluid loss associated with electrolyte imbalance, inhibition of insulin secretion, insulin resistance, and onset of a hypercatabolic state can also be contributive factors. All these complications of TEN (that can also be observed in SJS) are best managed in intensive care units. They can unfortunately culminate in adult respiratory distress syndrome and multiple organ failure despite adequate supportive therapy. Healing of areas of detached epidermis through re-epithelialization usually starts within days, and it is complete in most cases within 3 weeks. This process results from proliferation and migration of

keratinocytes from “reservoir” sites, such as healthy epidermis surrounding denuded areas and hair follicles within the areas of detachment. Due to this conserved capacity for re-epithelialization, skin grafting is not required in SJS or TEN. Unfortunately, however, healing can be imperfect, and survivors may have both ocular (symblepharon, conjunctival synechiae, entropion, ingrowth of eyelashes) and cutaneous sequelae (scarring, irregular pigmentation, eruptive melanocytic nevi), as well as persistent erosions of the mucous membranes, urethral stenosis, phimosis, vaginal synechiae with dyspareunia or hematocolpos, nail dystrophy, and diffuse hair loss (Fig. 20.12). These can often be minimized by optimizing skin care (see below), but, in TEN, up to 35% of survivors can have ocular symptoms ranging from sicca syndrome to blindness47. Identification of the offending drug is an important and difficult task, but it should be among the first priorities. As noted previously, delayed withdrawal of the causative drug(s) is associated with increased mortality. Currently, there is no reliable in vitro test for the rapid identification of causative drugs. Patch testing shows weak sensitivity in SJS/TEN and is not appropriate for identification purposes; re-exposing the patient to the proposed causative drug is obviously not an acceptable option in severe drug reactions. The clinician, therefore, has to rely on previously reported associations and determine the probability (unlikely, possible, plausible, probable, very probable) for each medication based on the intrinsic ability of a particular drug to cause SJS/TEN (see Table 20.5 and reference therein) and extrinsic factors such as the initiation



CHAPTER

Erythema Multiforme, Stevens–Johnson Syndrome, and Toxic Epidermal Necrolysis

Fig. 20.7 Mucosal involvement in Stevens– Johnson syndrome. A Erythema and conjunctival erosions. B Erosions of the genital mucosa.



341

SECTION

Urticarias, Erythemas and Purpuras

4

SPECTRUM OF DISEASE BASED UPON SURFACE AREA OF EPIDERMAL DETACHMENT

SJS

SJS/TEN overlap

TEN

30%

$

%

&

= Surface area of epidermal detachment

= Detached epidermis

SJS = Stevens−Johnson syndrome TEN = Toxic epidermal necrolysis

Fig. 20.10 Spectrum of disease based upon surface area of epidermal detachment.  

'

Fig. 20.9 Clinical features of toxic epidermal necrolysis (TEN). A Detachment of large sheets of necrolytic epidermis (>30% body surface area), leading to extensive areas of denuded skin. A few intact bullae are still present.   B Extensive symmetric hemorrhagic crusting of the face with areas of denudation. C Epidermal detachment of palmar skin. D Note the rolled and folded sheets of detached epidermis at the edge of denuded skin in addition to widespread erythema and intact bullae. D, Courtesy, Luis Requena, MD.  

of a given medication with respect to the onset of SJS/TEN. SJS and TEN usually occur 7–21 days after initiation of the causative drug if it is the first exposure to the drug, but can occur within 2 days in the case of re-exposure to a drug that previously caused SJS or TEN. In general, the medication list of patients with SJS and TEN should be reduced to a strict minimum, appropriate substitutions made, and drugs with short half-lives favored.

Pathology 342

Histopathologic examination of lesional skin is a very useful tool for confirming the diagnosis of SJS and TEN (Fig. 20.13), as the morpho-

logic findings are distinct from those observed in SSSS (subcorneal blister with cleavage located in the granular layer of the epidermis) and acute generalized exanthematous pustulosis (AGEP; a rich neutrophilic infiltrate, superficial epidermal pustules and spongiosis, but no fullthickness epidermal necrolysis). Frequently, immediate analysis of frozen cryostat sections is sufficient for this purpose. In early lesions of SJS and TEN, apoptotic keratinocytes are observed scattered in the basal and immediate suprabasal layers of the epidermis. This is most likely the histologic correlate of the dusky to gray color that clinicians familiar with SJS/TEN consider as a warning sign of impending full-blown epidermal necrolysis and detachment. At later stages, lesional biopsy specimens show a subepidermal blister with overlying confluent necrosis of the entire epidermis and a sparse perivascular infiltrate composed primarily of lymphocytes. At an immunopathologic level, variable numbers of lymphocytes (usually CD8+) and macrophages are observed within the epidermis, whereas lymphocytes in the papillary dermis are primarily CD4+ cells66,68.

Differential Diagnosis The differential diagnosis of SJS consists primarily of EM (especially EM major), generalized fixed drug eruption, autoimmune bullous diseases, and Kawasaki disease while the differential diagnosis for both SJS and TEN includes SSSS, drug-induced linear IgA bullous dermatosis (LABD), LE, and the other entities outlined in Table 20.7. During the first 24–36 hours, SJS (as well as EM) may be diagnosed as a morbilliform drug reaction (Fig. 20.14).

Treatment Optimal medical management of SJS and TEN requires early diagnosis, immediate discontinuation of the causative drug(s), and supportive care (Fig. 20.15).

CHAPTER

$

%

$

%

&

Fig. 20.11 Stevens–Johnson syndrome (SJS)/toxic epidermal necrolysis (TEN) overlap and early TEN. A In addition to mucosal involvement and numerous dusky lesions with flaccid bullae, there are areas of coalescence and multiple sites of epidermal detachment. Because the latter involved >10% body surface area, the patient was classified as having SJS/TEN overlap. B Close-up of epidermal detachment, whose appearance has been likened to wet cigarette paper. C A child with early TEN due to diclofenac. There is coalescence of the dusky lesions as well as detached epidermis and denudation. C, Courtesy, Lisa Weibel,  

MD.

Supportive care is similar to that performed for severe thermal burns, and it is aimed at limiting associated complications, which are the main cause of mortality. These include hypovolemia, electrolyte imbalance, renal insufficiency, and sepsis. Careful daily wound care, hydration, and nutritional support are essential and, preferably, done in an intensive care unit if there is epidermal detachment involving 10–20% (or more) of BSA82. Use of a controlled pressure, thermoregulated bed, and an aluminum survival sheet, instead of a regular bed and sheets, is recommended. All patient manipulations should be performed sterilely, and venous catheters should be placed, if possible, in a region of non-involved skin. Wound care is best performed once daily with the help of, or in the presence of, a dermatologist. The patient should be manipulated as little as possible, as every movement is a potential cause of epidermal detachment. Cutaneous care should concentrate on the face, eyes, nose, mouth, ears, anogenital region, axillary folds, and interdigital spaces. Non-detached areas are kept dry and not manipulated. Detached areas, particularly on the back and pressure sites in contact with the bed, should be covered with Vaseline® gauze until re-epithelialization has occurred (see Ch. 145). For the face, serous and/or bloody crusts can be cleaned daily with isotonic sterile sodium chloride solution. An antibiotic ointment (e.g. mupirocin) or petrolatum ointment (if the patient is on systemic antibiotics) should be applied around orifices, e.g. ears, nose, mouth. Silicone dressings can be used to cover erosive denuded areas of skin. The silicone dressing does not need to be changed and can be left in place until re-epithelialization occurs, but its surface must be cleansed daily with isotonic sterile sodium chloride solution. Another option is to place a large non-adherent layered dressing (e.g. Exu-Dry™) over the patient and on the bed. For the eyes, regular examination by an ophthalmologist is recommended. Eyelids should be gently cleansed daily with isotonic sterile sodium chloride solution, and an ophthalmic antibiotic ointment applied to the eyelids. In addition, antibiotic eyedrops should be administered three times a day to the cornea to reduce bacterial colonization, which can lead to scarring. Nostrils should be cleaned daily with a sterile cotton swab, moistened with isotonic sterile sodium chloride

Erythema Multiforme, Stevens–Johnson Syndrome, and Toxic Epidermal Necrolysis

20

&

Fig. 20.12 Sequelae of toxic epidermal necrolysis. A Symblepharon, erosion of lower lateral eyelid margin and sparse eyelashes; the patient also had entropion with an ingrowth of eyelashes and pebble-like scarring of facial skin. B Larger irregular areas of hypopigmented scarring. C Nail dystrophy consisting of longitudinal ridging and fissuring, fragility, and distal notching.  

Fig. 20.13 Toxic epidermal necrolysis – histopathologic features. Apoptotic keratinocytes are present individually and in clusters within the epidermis. Subtle vacuolar changes along the basal layer are accompanied by minimal inflammation, with scattered lymphocytes within the epidermis. Courtesy, Lorenzo  

Cerroni, MD.

solution, and then the same procedure used to apply a little antibiotic (e.g. mupirocin) or petrolatum ointment. The mouth should be rinsed several times a day using a syringe with isotonic sterile sodium chloride solution, and then aspirated if the patient is unconscious. In the anogenital region and interdigital spaces, cutaneous care is performed daily

343

SECTION

Urticarias, Erythemas and Purpuras

4

DIFFERENTIAL DIAGNOSIS OF TOXIC EPIDERMAL NECROLYSIS

Disease

Clinical and histologic features

Erythema multiforme and Stevens–Johnson syndrome



Staphylococcal scalded skin syndrome (SSSS; see Chs 74 & 81)



Invasive fungal dermatitis (see Ch. 34)



Acute generalized exanthematous pustulosis (AGEP; see Ch. 21)



Children and occasionally adults Split is more superficial so base is eroded epidermis not dermis • Perioral and periorbital accentuation with radial scale-crusts; no intraoral lesions • Microscopically, subcorneal split with a normal underlying epidermis •

Very-low-birth-weight newborns Widespread erythema with erosions resembling a thermal burn • Usually due to candidal infection •

Numerous small, non-follicular pustules; can coalesce leading to large areas of exfoliation • Peripheral neutrophilia • Microscopically, subcorneal pustules; no full-thickness epidermal necrosis

$

Fig. 20.14 Early Stevens–Johnson syndrome. A In this child, there are individual erythematous lesions on the lower face, but coalescence on the cheeks. The two fresh bullae on the cheek are still intact.   B This patient was originally diagnosed as a severe morbilliform drug eruption to penicillin, but then areas of epidermal detachment due to friction developed. A,  

When there are numerous mucocutaneous lesions • Timing post drug exposure differs • Microscopically, significant overlap

Generalized fixed drug eruption (see Ch. 21)



Drug-induced linear IgA bullous dermatosis (LABD), paraneoplastic pemphigus (PNP), bullous pemphigoid (see Chs 29–31)



Lupus erythematosus (Rowell syndrome; see Ch. 41)



Severe acute GVHD (stage/grade IV; see Ch. 52)



Drug reaction with eosinophilia and systemic symptoms (DRESS; see Ch. 21)



Toxic erythema of chemotherapy (see Ch. 21)



Disseminated intravascular coagulation/purpura fulminans



Exposure to high-risk drugs, e.g. vancomycin for LABD • Findings by routine histology and especially direct and indirect (PNP) immunofluorescence microscopy allow distinction Usually resembles EM but can have TENlike presentation • Appears de novo or as therapy tapered • Microscopically, significant overlap

Courtesy, Julie V Schaffer, MD.

Recipient of allogeneic hematopoietic stem cell transplant • Uncommon due to use of prophylactic GVHD therapies • Microscopically, significant overlap In addition to widespread erythema, vesiculobullae and pustules can develop • Facial edema; peripheral eosinophilia (most patients) • Microscopically, changes are variable and sometimes non-specific; necrosis usually absent; relatively dense dermal inflammatory infiltrate, often admixed with eosinophils Exposure to particular chemotherapeutic or targeted agents • Symmetric dusky erythema, often involving skin folds, hands and feet and less often elbows and knees • Can be generalized but bullae less fragile • Microscopically, less necrosis and presence of enlarged, atypical-appearing keratinocytes (“busulfan” cells) Bullae are hemorrhagic Acral ischemia/necrosis • Microscopically, fibrin thrombi within vessels in the dermis, with hemorrhage and minimal inflammation; necrosis of the epidermis, if present, is secondary to vascular occlusion •

Table 20.7 Differential diagnosis of toxic epidermal necrolysis. Distinctive histopathologic findings are in italics.  

344

See Table 20.1

%

by short applications of silver nitrate solution (0.5%) in the case of maceration, or simply sterile sodium chloride solution if there is no maceration. To date, no specific therapies for SJS and TEN have shown efficacy in prospective, controlled clinical trials, i.e. attained evidence-based medicine standards of acceptance82a. In general, therapy for severely affected patients with SJS has mirrored therapy for TEN, while those patients with milder non-progressive forms of SJS may receive only supportive care. The low prevalence of SJS and TEN makes randomized clinical trials hard to perform. As a consequence, the literature for the most part consists of case reports and small uncontrolled series. In such studies, several treatments, including cyclophosphamide (100–300 mg/ day), plasmapheresis, N-acetylcysteine (2 g/6 h), and more recently, TNF-α inhibitors (e.g. etanercept, infliximab) showed promising results67,83–87. For example, in a consecutive series of 10 patients with TEN, a single 50 mg injection of etanercept led to a median time of healing of 8.5 days87. On the other hand, a controlled study using thalidomide was interrupted because of higher mortality in the thalidomide group compared with the placebo group88. In addition to TNF-α inhibitors, decisions regarding systemic therapies focus primarily on pulse corticosteroids, cyclosporine, and IVIg.

CHAPTER

Stevens–Johnson syndrome or toxic epidermal necrolysis

Promptly discontinue any, and all, possible offending drugs

• • • • • • • • • • •

Admit to skilled nursing care unit, e.g. ICU or burn unit Correct fluid and electrolyte imbalances Caloric replacement Protect from secondary infections with topical antibiotic ointments Ophthalmology consult and good eye care Urology consult if urethral inflammation Oral antacids and mouth care Pulmonary toilet, if respiratory syndrome Periodic cultures of mouth, eyes, skin, sputum Physical therapy to prevent contractures If extensive denuded areas, use biological dressings or skin equivalents

Consider systemic medication on a short-term basis : • IVIg (>2 g/kg total dose over 3–4 days) • Cyclosporine (3–5 mg/kg/day x 7 days) • Dexamethasone (1.5 mg/kg/day x 3 days) • TNF- inhibitor (e.g. etanercept 50 mg sc once)

*

* according to evidence from non-controlled studies performed to date (see section on therapy) Fig. 20.15 Approach to the patient with Stevens–Johnson syndrome or toxic epidermal necrolysis. ICU, intensive care unit.  

META-ANALYSIS OF THE USE OF IVIG FOR THE TREATMENT OF TOXIC EPIDERMAL NECROLYSIS

Analyzed reports

Total # of patients

17

167

Total dose of IVIg (g/kg)

Patients

Affected skin area (% BSA)

Mortality (%)

Europeans

B*5801

DRESS

Han Chinese and other Asian populations

B*1502

SJS/TEN

Northern Europeans, Japanese, Chinese, Korean

A*3101

Hypersensitivity reactions

Dapsone

Chinese

B*1301

DRESS

Feprazone (NSAID)

Scandinavians

B22

FDE

Lamotrigine

Taiwanese

B*1502

SJS/TEN

Nevirapine

French

DRB1*01:01

DRESS

Phenytoin

Southeast Asians

B*1502

SJS/TEN

Trimethoprim–sulfamethoxazole

Turkish

B55

FDE

Abacavir Allopurinol Carbamazepine

Table 21.4 Specific HLA alleles that increase the risk of cutaneous drug reactions. A number of HLA alleles also increase the risk of liver injury, including from penicillin derivatives. Highest relative risks are in bold. DRESS, drug reaction with eosinophilia and systemic symptoms; FDE, fixed drug eruption; SJS, Stevens– Johnson syndrome; TEN, toxic epidermal necrolysis.  

349

SECTION

Urticarias, Erythemas and Purpuras

4

strong associations between HLA-B*1502 and carbamazepine-triggered SJS/TEN in Asians and between HLA-B*5701 and abacavir-triggered DRESS, pretreatment genetic testing is now recommended.

Non-immunologic Mechanisms (see Table 21.3) Overdose The clinical manifestations of a drug overdose are predictable and represent an exaggeration of the medication’s pharmacologic actions. It may occur as a consequence of a prescribing error, deliberate excess by the patient, or altered absorption, metabolism or excretion. An example of the latter is methotrexate toxicity in elderly patients with reduced renal function (Fig. 21.1).

Pharmacologic side effects These reactions include undesirable or toxic effects that cannot be separated from the desired pharmacologic actions of the drug. An example would be alopecia and mucositis due to chemotherapeutic agents that target more rapidly dividing cells.

Cumulative toxicity Prolonged exposure to a medication or its metabolites may lead to cumulative toxicity. For example, methotrexate can lead to hepatic fibrosis and accumulation of minocycline or amiodarone within the skin can lead to cutaneous discoloration.

Delayed toxicity This corresponds to a toxic, dose-dependent effect that occurs months to years after the discontinuation of a medication. Examples include squamous cell carcinomas and palmoplantar keratoses following exposure to arsenic and acute leukemia due to alkylating agents.

A

B

Fig. 21.1 Methotrexate toxicity. Increased serum levels of methotrexate secondary to decreased renal excretion can lead to epidermal necrosis. A Large erosions and areas of epidermal necrosis with a shellac-like appearance in a patient with rheumatoid arthritis. B Epidermal necrosis limited to psoriatic plaques. A, Courtesy, Kalman Watsky, MD.  

350

Drug–drug interactions Interactions between two or more drugs administered simultaneously may occur at several different steps: (1) intestinal drug interactions; (2) displacement from binding proteins or receptor sites; (3) enzyme stimulation or inhibition; and (4) altered drug excretion (see Ch. 131). Examples of each include the interactions between tetracycline and calcium, methotrexate and sulfonamides, cyclosporine and azoles, and methotrexate and probenecid.

Alterations in metabolism Drugs may induce cutaneous changes by their effects on the nutritional or metabolic status of the patient. Bexarotene may induce severe hypertriglyceridemia and eruptive xanthomas, while isoniazid may be associated with pellagra-like changes.

Exacerbation of disease A variety of drugs can exacerbate pre-existing dermatologic diseases, such as androgens in patients with acne vulgaris or lithium and interferon in patients with psoriasis.

Idiosyncratic With a Possible Immunologic Mechanism (see Table 21.3) The pathophysiology of drug-induced skin reactions such as exanthematous drug eruptions, DRESS, AGEP and TEN, as well as the increased susceptibility of HIV-infected patients, may be partially explained by an interplay between immune mechanisms and genetic predisposition (e.g. slow versus rapid acetylators).

DIAGNOSTIC FEATURES Drug eruptions, both suspected and unsuspected, frequently lead to a dermatologic consultation, and it is often (although not always) possible to categorize a drug as having a high, medium or low probability of being the culprit. A logical approach begins with an accurate description of the skin lesions and their distribution, in addition to associated signs and symptoms (Table 21.5). Data regarding all the drugs taken by the patient, including prescription, non-prescription/over-the-counter and complementary or alternative treatments, as well as the dates of administration and doses need to be collected. The chronology of drug administration is of paramount importance (Table 21.6). The time between initiation of the drug and the onset of the skin eruption is a key element in identifying the offending drug, as most immunologically mediated reactions occur 8 to 21 days after initiation of a new medication. Evolution after drug withdrawal may be helpful, as the cutaneous eruption usually clears when the suspected drug is discontinued. However, this assessment may prove difficult in the case of drugs with a long half-life or “persistent” drug reactions such as lichenoid and photoallergic eruptions or drug-induced pemphigus foliaceus and subacute cutaneous lupus erythematosus. The suspect drug should be withdrawn as soon as possible. The usual practice is to discontinue all drugs that are non-essential. However, in some instances, it is necessary to weigh the risks versus the benefits of each drug and to determine if a similar-acting, but non-cross-reactive, drug is available as a substitute. In the process of identifying the responsible drug, access to drug databases is very helpful7–9. However, new or unusual drug reactions may not be identified. Moreover, the drug most frequently associated with adverse reactions may be innocent in a particular patient, and the physician dealing with a suspected drug reaction must remain open-minded. With the exception of assays for IgE antibodies, diagnostic or confirmatory assays to establish the responsible drug are not available. A number of in vitro tests have been designed, including the histamine release test, migration inhibition factor test, lymphocyte toxicity assay, lymphocyte transformation test, and basophil degranulation test10. However, their sensitivity and specificity have not been assessed in a reliable way with relevant controls. As a result, they are of limited value in the clinical setting. Results of patch testing, in which drugs (usually with petrolatum or alcohol as the vehicle) are applied to the upper back for 48 hours, vary

CHAPTER

21 Drug Reactions

LOGICAL APPROACH TO DETERMINE THE CAUSE OF A DRUG ERUPTION

Drug responsibility assessment Clinical characteristics



Type of primary lesion (e.g. urticaria, erythematous papule, pustule, purpuric papule, vesicle, or bulla) • Distribution and number of lesions • Mucous membrane involvement, facial edema • Associated signs and symptoms: fever, pruritus, lymph node enlargement, visceral involvement

Chronological factors



Search of databases



Document all drugs to which the patient has been exposed (including OTC and complementary) and the dates of administration • Date of eruption • Time interval between drug introduction (or reintroduction) and skin eruption • Response to removal of the suspected agent • Consider excipients (e.g. soybean oil) • Response to rechallenge * Bibliographic research (e.g. PubMed, Micromedex, Litt’s Drug Eruption and Reaction Database) • Drug Alert Registry or MedWatch • Data collected by pharmaceutical companies • In the case of more recently released medications, extrapolation based on the class of drug and in particular the first drug released in the class

*Often inadvertent. Table 21.5 Logical approach to determine the cause of a drug eruption. OTC, over-the-counter.  

depending upon the responsible drug and the type of eruption6,15 (Table 21.7). Prick and intradermal tests can be performed in patients with urticaria and angioedema, but are contraindicated in SJS/TEN due to the risk of relapse6. Of note, delayed reading of prick, intradermal, and patch tests is particularly important in the case of amoxicillin-induced morbilliform eruptions. Unfortunately, investigations involving series of patients with several different types of drug reactions have shown heterogeneous results. In general, these tests, when positive, may be helpful in preventing readministration of the offending drug, but with the exception of prick and intradermal tests in patients with urticaria and perhaps patch tests in a few disorders (see Table 21.7), their specificity and/or sensitivity are low. Rechallenge carries the risk of inducing a more severe reaction, thus limiting its use for both ethical and medico-legal reasons. Furthermore, the recurrence rate is not 100% with rechallenge (e.g. there are refractory periods) and a negative result may give an erroneous sense of security. Even with these limitations, in patients with fixed drug eruptions, topical provocation or rechallenge may prove helpful.

CLINICAL FEATURES Urticaria, Angioedema, and Anaphylaxis In urticaria, there is vasodilation and transient edema within the dermis whereas in angioedema, the edema is present in deep dermal, subcutaneous, and submucosal tissues. Although several different mechanisms may be responsible, dramatic outbreaks of acute urticaria usually represent an immediate hypersensitivity reaction mediated by IgE antibodies, especially when the urticaria is associated with angioedema and/or anaphylaxis. Clinically, “anaphylactoid” reactions may mimic IgE-induced histamine release, but are secondary to a nonimmunologic liberation of histamine and/or other mediators of inflammation.

Fig. 21.2 Urticaria secondary to penicillin. Several of the lesions have a figurate appearance.  

Urticaria (see Ch. 18 for details) Urticaria presents as transient, often pruritic, erythematous and edematous papules and plaques that may appear anywhere on the body, including the palms, soles, and scalp. Lesions can vary significantly in size and number and may assume a figurate configuration (Fig. 21.2). The primary effector cell is the cutaneous mast cell which releases histamine and other inflammatory mediators (see Fig. 18.4)16. Although drugs are thought to be responsible for 40

In situ patch test recommended, i.e. at the site of a previous lesion

Drug reaction with eosinophilia and systemic symptoms (DRESS)

30–60

Should be performed at least 6 months after clinical resolution Positive results primarily observed with abacavir, carbamazepine, proton pump inhibitors, and antituberculous drugs

Exanthematous (morbilliform) drug eruption

10–40

If patch test negative, prick tests can be discussed to increase positivity, depending upon disease severity

SJS/TEN

10–25

Reports of positive results with β-lactam antibiotics, carbamazepine, trimethoprim–sulfamethoxazole, and pseudoephedrine

*Range because results often depend upon particular drug. Table 21.7 Cutaneous drug eruptions – use of patch testing to identify the responsible drug. Patch tests are placed on the upper back for 48 hours and read at 3–7 days as with standard patch testing (see Ch. 14). Vehicles are usually petrolatum or alcohol and concentrations are either predetermined (commercially available products) or based upon literature review. SJS, Stevens–Johnson syndrome; TEN, toxic epidermal necrolysis.  

352

Iodinated Immediate (1 week)

Gadolinium Urticaria, erythema (rare) Anaphylactoid reactions, anaphylaxis (rare) Nephrogenic systemic fibrosis (in the setting of renal insufficiency; see Ch. 43)

Table 21.8 Adverse reactions to radiocontrast media.  

Angioedema (see Ch. 18 for details) Angioedema is a reflection of transient edema of the deep dermal, subcutaneous and submucosal tissues. It is associated with urticaria in 50% of cases and may be complicated by life-threatening anaphylaxis. Angioedema occurs in 1 to 2 per 1000 new users of angiotensinconverting enzyme (ACE) inhibitors and is due to an accumulation of bradykinin (see Fig. 18.6). The most severe cases of angioedema may start within a few minutes after drug administration. However, in the case of ACE inhibitor-induced angioedema, lesions may appear from 1 day to several years after starting the drug; most appear within the first year. African-Americans and women are at increased risk for developing ACE inhibitor-induced angioedema6. The most common clinical presentation is an acute, asymmetric, pale or pink, subcutaneous swelling involving the face. Involvement of the oropharynx, larynx, and epiglottis can lead to impaired swallowing and stridor. Occasionally, in drug-induced angioedema, there is edema of the intestinal wall with abdominal pain, nausea, vomiting, and diarrhea. The major drugs implicated in angioedema, besides penicillins and ACE inhibitors, are NSAIDs, radiographic contrast media and, more recently, monoclonal antibodies (see Ch. 128). Although angiotensin II receptor antagonists do not increase levels of bradykinin, they are also associated with angioedema, albeit less frequently. It is important to note that drug-induced angioedema may actually represent an unmasking of another cause for angioedema, e.g. acquired C1 inhibitor deficiency due to autoimmune or lymphoproliferative disorders.

Anaphylaxis Anaphylaxis consists of an acute life-threatening reaction that occurs within minutes of drug administration, usually parenteral. It occurs in about 1 per 5000 exposures to penicillin and combines skin signs (urticaria and/or angioedema) with systemic manifestations such as hypotension and tachycardia. Occasionally, there is hypotension in the absence of cutaneous lesions. In severe cases, the patient becomes unconscious as a result of cardiovascular shock and may die. Prompt discontinuation of the offending drug is mandatory, as is strict avoidance of the drug in the future. Subcutaneous epinephrine (adrenaline) and systemic corticosteroids are the primary treatments for lifethreatening angioedema and anaphylaxis, along with careful monitoring. Of note, patients taking β-blockers may have a limited response to epinephrine. The most frequently incriminated drugs are antibiotics, in particular the penicillins/aminopenicillins but also cephalosporins and quinolones; in one series, additional causes were muscle relaxants (e.g suxamethonium), acetaminophen, and gadolinium-based contrast media17. Anaphylaxis can also be seen following exposure to latex (see Ch. 16) while anaphylactoid reactions are usually seen with NSAIDs and radiocontrast media (see Table 21.8). Rarely, anaphylaxis occurs following cutaneous injections (e.g. local anesthetics) or topical applications of medications (e.g. bacitracin, chlorhexidine).

Synonyms:  ■ Morbilliform drug eruption ■ Maculopapular drug eruption ■ Urticarial drug eruption

Exanthematous or morbilliform eruptions are the most common adverse drug reactions affecting the skin. They are often referred to as maculopapular drug eruptions or, in the case of non-dermatologists, “drug rashes”. The primary underlying pathomechanisms are most likely immunologic, complex, and cell-mediated. Several mechanisms have been proposed (see above) in which the drug or drug-peptide hapten presented by dendritic cells to T lymphocytes can either bind covalently or noncovalently to MHC molecules12. CD4+ and CD8+ T cells that strongly express perforin and granzyme are then recruited and their cytotoxic activity leads to death of keratinocytes. Overall, most drug classes can induce an exanthematous eruption in ~1% of treated patients. Higher risk medications (>3% of treated patients develop an eruption) include aminopenicillins, allopurinol, sulfonamides, cephalosporins, and aromatic anticonvulsants. Certain viral infections are also known to increase the incidence of drug reactions. Depending upon the series, the frequency of aminopenicillininduced exanthematous eruptions in patients with infectious mononucleosis ranges from 33% to 100% (see Ch. 80). One theory is that reactive drug metabolites disturb the balance between cytotoxic and regulatory immune responses, leading to a cytotoxic reaction that targets virally infected keratinocytes. A morbilliform eruption classically begins 7 to 14 days after the initial drug administration, but appears earlier in the case of rechallenge. Symmetrically distributed erythematous macules, papules and/ or urticarial lesions initially appear on the trunk and upper extremities; over time they can become confluent (Fig. 21.3A). The eruption is typically more polymorphous than a viral exanthem. Sometimes, due to dependency, the lesions on the distal lower extremities become petechial or purpuric (Fig. 21.3B). Mucous membranes are usually spared but pruritus and a low-grade fever are often present. There may also be annular plaques (Fig. 21.3C) or atypical “target” lesions, leading to a misdiagnosis of erythema multiforme. Once the offending drug is discontinued, the eruption gradually resolves over one to two weeks, without complications and/or sequelae. However, for 1 to 3 days immediately following discontinuation of the responsible medication, an increase in extent and intensity may be observed. Signs and symptoms that point to the possibility of a more severe drug-induced eruption (see Table 21.1) include edema of the face, pustules, vesicles, dusky or painful lesions, skin fragility, mucous membrane involvement, and marked peripheral blood eosinophilia. Histopathologically, nonspecific findings are typically seen in morbilliform drug eruptions, i.e. a mild superficial perivascular and interstitial lymphocytic infiltrate that may contain eosinophils (up to 70% of cases) in addition to interface changes18. The major entity in the differential diagnosis of a morbilliform drug eruption is a viral exanthem (e.g. Epstein–Barr virus [EBV], enterovirus, adenovirus, early HIV infection, human herpesvirus type 6 [HHV-6]; see Fig. 81.2). Peripheral blood eosinophilia and a polymorphous appearance point to a drug eruption, and in the absence of definitive evidence, drug eruptions are favored in adults whereas viral exanthems are favored in children. Occasionally, there is a viral infection that enhances the risk of developing a drug eruption (see above)12. Toxic shock syndromes, scarlet fever, acute GVHD, Kawasaki disease, and SCARs should be excluded on the basis of associated clinical features (Fig. 21.4). Treatment is largely supportive. Topical antipruritics and corticosteroids may help to alleviate pruritus. Discontinuing the offending agent is the first therapeutic intervention. “Treating through”, i.e. continuing the drug despite the cutaneous eruption, can be considered when the suspected drug is of paramount importance for the patient and there is no satisfactory substitute drug. Usually, the eruption will disappear, but a few patients may experience progressive worsening, leading to erythroderma. Desensitization may be considered in HIV-infected patients who require sulfonamides.

CHAPTER

21 Drug Reactions

ADVERSE REACTIONS TO RADIOCONTRAST MEDIA

Exanthematous Drug Eruptions

353

SECTION

4

Urticarias, Erythemas and Purpuras

REGISCAR SCORING SYSTEM FOR DRESS

Criteria

No

Yes

Unknown/ unclassifiable

Fever (≥38.5°C)

−1

0

−1

0

1

0

Circulating atypical lymphocytes

0

1

Peripheral hypereosinophilia

0

Lymphadenopathy (≥2 sites; >1 cm)

0 0

  0.7–1.499 × 109/L - or - 10–19.9%*

1

  ≥1.5 × 109/L - or - ≥20%*

2

Skin involvement Extent of cutaneous eruption > 50% BSA

0

1

0

Cutaneous eruption suggestive of DRESS**

−1

1

0

Biopsy suggests DRESS

−1

0

0







Internal organs involved†

0

  One

1

  Two or more

2

Resolution in ≥15 days Laboratory results negative for at least three of the following (and none positive): (1) ANA; (2) blood cultures; (3) HAV/HBV/HCV serology; and (4) Chlamydia and Mycoplasma serology

A

0

−1

0

−1

0

1

0

Final score: < 2, no case; 2–3, possible case; 4–5, probable case; >5, definite case

*If leukocytes EM/SJS/TEN Secondary syphilis Kawasaki disease GVHD Acute engraftment syndrome Toxic shock syndrome Early meningococcemia Early Rickettsial infection

Fig. 21.4 Approach to the differential diagnosis of an exanthematous drug reaction. With a few exceptions (e.g., pityriasis rosea, drug-induced autoimmune bullous disorders), patients with these entities may be febrile. Entities in italics occur primarily in children. Toxic shock syndrome can be staphylococcal or streptococcal (see Ch. 74). Drug-induced autoimmune bullous disorders: bullous pemphigoid or linear IgA bullous dermatosis > drug-induced pemphigus. AGEP, acute generalized exanthematous pustulosis; CMV, cytomegalovirus; DIHS, drug-induced hypersensitivity syndrome; DRESS, drug reaction with eosinophilia and systemic symptoms; EBV, Epstein-Barr virus; EM, erythema multiforme; GVHD, graft versus host disease; SJS, StevensJohnson syndrome; TEN, toxic epidermal necrolysis.  

CHAPTER

21 Drug Reactions

APPROACH TO THE DIFFERENTIAL DIAGNOSIS OF AN EXANTHEMATOUS DRUG REACTION

+ Hypotension

Toxic shock syndrome

Pharyngitis

Scarlet fever (Group A strep) EBV > CMV infection Acute HIV syndrome Arcanobacterium haemolyticum infection

Mucosal involvement (e.g. conjunctival, oral, urethral)

Viral exanthem (conjunctival, oral) Varicella (oral [erosive]) EM/SJS/TEN (multiple [erosive]) Kawasaki disease (conjunctival injection, oral) GVHD (multiple) Toxic shock syndrome (conjunctival injection, oral) Drug-induced autoimmune bullous disorders Periodic fever syndromes (conjunctival, oral)

+

+

+ Confluent erythema

+ Facial edema

Peripheral scale, lesions follow skin cleavage lines

Scarlet fever Staphylococcal scalded skin syndrome Toxic shock syndrome DRESS/DIHS or early SJS/TEN Early AGEP or pustular psoriasis Kawasaki disease DRESS/DIHS > AGEP Staphylococcal scalded skin syndrome Acute hemorrhagic edema of infancy Dermatomyositis Still disease

+ Early pityriasis rosea

Individual lesions last drug-induced pemphigus.  

Varicella, other viral exanthems (e.g. coxsackievirus) EM/SJS/TEN Staphylococcal scalded skin syndrome Disseminated zoster or herpes simplex Insect bite reactions, including scabies DRESS/DIHS (less common finding) Drug-induced autoimmune bullous disorders Sweet syndrome PLEVA Lupus erythematosus (e.g. Rowell syndrome) Severe GVHD Langerhans cell histiocytosis

**

Viral exanthem (e.g. enterovirus, parvovirus) Meningococcemia Rocky Mountain spotted fever and other rickettsioses Viral hemorrhagic fevers Vasculitis Acute hemorrhagic edema of infancy Miliaria Grover disease Folliculitis

**

Immunocompromised host AGEP = acute generalized exanthematous pustulosis DIHS = drug-induced hypersensitivity syndrome DRESS = drug reaction with eosinophilia and systemic symptoms (additional findings include lymphadenopathy, atypical lymphocytosis, hepatitis, myocarditis and renal dysfunction as well as facial swelling > vesicles or sterile pustules) EM/SJS/TEN = erythema multiforme/Stevens–Johnson syndrome/toxic epidermal necrolysis GVHD = graft-versus-host disease PLEVA = pityriasis lichenoides et varioliformis acuta

J-SCAR DIAGNOSTIC CRITERIA FOR DIHS/DRESS 1. Maculopapular rash developing >3 weeks after starting therapy with a limited number of drugs 2. Prolonged clinical symptoms after discontinuation of the causative drug 3. Fever (>38°C) 4. Liver abnormalities (ALT >100 U/L)* 5. Leukocyte abnormalities (at least one present): (a) leukocytosis (>11 × 109/L); (b) atypical lymphocytes (>5%); and (c) eosinophilia (>1.5 × 109/L) 6. Lymphadenopathy 7. HHV-6 reactivation

*This can be replaced by other organ involvement, such as renal involvement. Table 21.10 Japanese Research Committee on Severe Cutaneous Adverse [Drug] Reactions (J-SCAR) diagnostic criteria for DIHS (drug-induced hypersensitivity syndrome)/DRESS (drug reaction with eosinophilia and systemic symptoms). Typical DIHS is defined as the presence of all 7 criteria, while atypical DIHS is defined as the presence of only the first 5 criteria.  

356

include vesicles (Fig. 21.5B), follicular or non-follicular pustules (~20% of patients), erythroderma, and purpuric lesions. The face, upper trunk, and extremities are usually the initial sites of involvement. Edema of the face is a frequent finding and is a hallmark of DRESS whereas mucosal involvement, if present, is mild. Internal manifestations include lymphadenopathy and hepatic involvement (~80% of patients); rarely, the latter may become lifethreatening (see Tables 21.9 and 21.10). Patients may develop interstitial

nephritis, myocarditis, interstitial pneumonitis, myositis, thyroiditis, and even infiltration of the brain by eosinophils. The cutaneous and visceral involvement may persist for several weeks or months after drug withdrawal, and additional sites of involvement (e.g. cardiac, thyroid) may develop weeks or months later, including following a taper of corticosteroids. Overall mortality due to DRESS ranges from 2 to 10%22. Histopathologically, various inflammatory patterns can be seen, including eczematous, interface dermatitis, AGEP-like, and erythema multiforme-like. Prominent peripheral blood eosinophilia is common and is a very characteristic feature. It is often accompanied by mononucleosis-like atypical lymphocytosis. Elevation of hepatic enzymes can be a worrisome finding and requires serial evaluation. Thyroid and cardiac dysfunction (as detected by an ECG and echocardiogram) may develop as delayed complications and patients should therefore undergo longitudinal evaluation (Table 21.11). The differential diagnosis includes other cutaneous drug eruptions, acute viral infections, hypereosinophilic syndrome, lymphoma, and pseudolymphoma30. Involvement of multiple internal organs differentiates DRESS from the more common morbilliform eruptions. In addition to the most common etiologies – the aromatic anticonvulsants (phenobarbital, carbamazepine and phenytoin), lamotrigine (especially when coadministered with valproic acid), and sulfonamides – minocycline, allopurinol, and dapsone may also induce this syndrome, as well as drugs used to treat HIV infection, e.g. abacavir (Table 21.12). Early withdrawal of the offending drug is mandatory, but this may not result in a rapid complete recovery. Although guidelines for the treatment of DRESS are still lacking, systemic corticosteroids (oral or intravenous) typically represent first-line therapy. Because relapse can

CHAPTER

Basic laboratory screening during the acute phase with recommended repetitive tests in italics^ CBC with differential, platelet count, peripheral smear for atypical lymphocytes • BUN, creatinine, urinalysis, spot urine for protein : creatinine ratio * • LFTs, creatine kinase (CK), lipase, CRP • TSH, free T4 (repeat at 3 months, 1 year, and 2 years) • Fasting glucose (in anticipation of systemic corticosteroids) •

21 Drug Reactions

ASSESSMENT AND LONGITUDINAL EVALUATION OF PATIENTS WITH DRESS (DRUG REACTION WITH EOSINOPHILIA AND SYSTEMIC SYMPTOMS)

Additional testing ECG, troponin T, baseline echocardiogram Quantitative PCR for HHV-6, HHV-7, EBV, CMV • Wright stain of urine for eosinophilia (prior to instituting corticosteroids) • ANA, blood cultures (exclusion criteria in RegiSCAR scoring system) • If hemophagocytic lymphohistiocytosis suspected (see Ch. 91) **, ferritin, triglycerides, LDH, BM examination • •

A

Fig. 21.5 Drug reaction with eosinophilia and systemic symptoms (DRESS) due to carbamazepine. A Exanthematous eruption with confluence on the thighs. B Edema and vesiculation on the forearm. Courtesy, Alicia Little,  

MD.

Further testing based upon laboratory abnormalities or signs and symptoms** Liver – PT, PTT, albumin Renal – albumin, renal ultrasound (if laboratory abnormalities) • Cardiac – ECG, troponin T, echocardiogram • Neurologic – brain MRI • Pulmonary – CXR, PFTs • Gastrointestinal – endoscopy • •

^Testing is more frequent during the acute phase (e.g. twice weekly) with frequency also a

reflection of disease severity. Longitudinal evaluation is recommended for at least one year.

*Allows for immediate assessment for proteinuria. **Including during longitudinal evaluation.

Table 21.11 Assessment and longitudinal evaluation of patients with DRESS (drug reaction with eosinophilia and systemic symptoms). BM, bone marrow; BUN, blood urea nitrogen; CBC, complete blood count; CK, creatine kinase; CRP, C-reactive protein; LDH, lactic dehydrogenase; LFTs, liver function tests; PFT, pulmonary function test; PT, prothrombin time; PTT, partial thromboplastin time; TSH, thyroid stimulating hormone.  

B

occur when the dosage is reduced, a slow taper of corticosteroids over a period of several weeks to months is often required33. In milder cases of DRESS, even in the setting of mild hepatitis, topical high-potency corticosteroids may be helpful and may lead to less viral reactivation32. In a recent trial of IVIg, there was an increased risk of complications, but little therapeutic benefit. To date, antiviral strategies have only been proposed in case reports34.

DRUGS ASSOCIATED WITH DRUG REACTION WITH EOSINOPHILIA AND SYSTEMIC SYMPTOMS SYNDROME (DRESS)

Drug category

Specific drugs

Anticonvulsants

Carbamazepine, lamotrigine*, phenobarbital, phenytoin, oxcarbazepine, zonisamide > valproic acid

Serum Sickness-Like Eruption

Antimicrobials

This syndrome is more commonly observed in children and typically includes fever, arthralgias, arthritis, rash (urticarial, morbilliform), and lymphadenopathy2. It occurs 1 to 3 weeks after drug exposure. Unlike in “true” serum sickness due to non-human proteins (e.g. antithymocyte globulin, tositumomab, infliximab; Fig. 21.6), hypocomplementemia, circulating immune complexes, vasculitis, and renal disease are absent. This reaction occurs in approximately 1 in 2000 children given cefaclor. Other drugs associated with serum sickness-like reactions are penicillins, NSAIDs, bupropion, phenytoin, sulfonamides, minocycline, and propranolol.

Ampicillin, cefotaxime, dapsone, ethambutol, isoniazid, linezolid, metronidazole, minocycline, pyrazinamide, quinine, rifampin, sulfasalazine (salazosulfapyridine), streptomycin, trimethoprim–sulfamethoxazole, teicoplanin, vancomycin

Antiretrovirals

Abacavir, nevirapine, zalcitabine

Antidepressants

Bupropion, fluoxetine

Antihypertensives

Amlodipine, captopril

NSAIDs

Celecoxib, ibuprofen

Miscellaneous

Allopurinol**, azathioprine, imatinib, mexiletine, ranitidine, ziprasidone

Vasculitis (see Ch. 24) Drug-induced cutaneous small vessel vasculitis (CSVV) accounts for ~10% of all cases of CSVV and typically involves small vessels and in some patients medium-sized vessels. Drug-induced CSVV may be either a type II (cytotoxic) or a type III (immune complex) drug reaction. Clinically, drug-induced CSVV usually presents as purpuric papules, primarily on the lower extremities. Urticaria-like lesions, hemorrhagic

*Especially when coadministered with valproic acid. **Full doses in the setting of renal dysfunction a risk factor. Table 21.12 Drugs associated with drug reaction with eosinophilia and systemic symptoms syndrome (DRESS). Most commonly associated drugs are in bold. NSAIDs, nonsteroidal anti-inflammatory drugs.  

357

SECTION

Urticarias, Erythemas and Purpuras

4

blisters, pustules, digital necrosis, and ulcers may also be seen. Systemic involvement is very unusual, but suggestive symptoms are fever, myalgias, arthralgias, and/or headache. Internal manifestations include arthritis, nephritis, peripheral neuropathy, and gastrointestinal bleeding. Histopathologic examination of early lesions should be performed and will demonstrate leukocytoclastic vasculitis. Vasculitis usually develops 7 to 21 days after drug administration and within 3 days if a rechallenge. Systemic corticosteroids may benefit patients with systemic involvement; otherwise, discontinuing the culprit drug is usually sufficient. Additional management options are discussed in Chapter 24.

The primary medications associated with drug-induced CSVV include penicillins, NSAIDs (both oral and topical), sulfonamides, and cephalosporins; additional drugs are propylthiouracil, thiazide diuretics, furosemide, allopurinol, quinolones, levamisole, bortezomib, and systemic immunomodulators (e.g. granulocyte and granulocyte–macrophage colony-stimulating factors [G-CSF, GM-CSF], interferons, TNF-α inhibitors). ANCA-positive vasculitis with anti-myeloperoxidase antibodies has been associated with several drugs, including propylthiouracil, hydralazine, levamisole and minocycline, and polyarteritis nodosa has been observed following hepatitis B vaccination35.

Neutrophilic Drug Eruptions Acute generalized exanthematous pustulosis Synonyms:  ■ Pustular drug eruption ■ Toxic pustuloderma

Fig. 21.6 Serum sickness due to antithymocyte globulin. The purpuric lesions are due to small vessel vasculitis in this patient with aplastic anemia. Courtesy,  

Jean L Bolognia, MD.

Acute generalized exanthematous pustulosis (AGEP) is an acute febrile drug eruption characterized by numerous small, primarily non-follicular, sterile pustules arising within large areas of edematous erythema. More than 90% of cases of AGEP are drug-induced, but its incidence has been underestimated, in part because the eruption may be misdiagnosed as pustular psoriasis36. Occasionally, AGEP is due to other causes, e.g. enteroviral infection, exposure to mercury. HLA-B5, -DR11 and -DQ3 have been found more frequently in patients with AGEP37, and mutations in IL36RN may be a risk factor as well38. Prior sensitization (including contact sensitization) would explain the short interval (40 GPL or MPL – or – >99th percentile as measured by a standardized ELISA] 2. Lupus anticoagulant [detected according to the guidelines of the International Society on Thrombosis and Haemostasis] 3. Anti-β2-glycoprotein I antibodies, IgG or IgM [>99th percentile as measured by a standardized ELISA]

CUTANEOUS FINDINGS IN PATIENTS WITH THE ANTIPHOSPHOLIPID ANTIBODY SYNDROME (APLS) Livedo reticularis, with or without retiform purpura Cholesterol embolus-like proximal livedo reticularis with distal retiform purpura • Acral livedo reticularis • Sneddon syndrome • Livedoid vasculopathy or Degos-like lesions • Anetoderma-like lesions with microthrombosis • Raynaud phenomenon • Vasculitis-like lesions • Behçet disease-like lesions • Pyoderma gangrenosum-like ulcers • Nail fold ulcers • Splinter hemorrhages • Widespread cutaneous necrosis, typically as part of catastrophic APLS • Pseudo-Kaposi sarcoma • Superficial thrombophlebitis migrans • •

Table 23.6 Cutaneous findings in patients with the antiphospholipid antibody syndrome (APLS).  

Fig. 23.8 Antiphospholipid antibody syndrome. A Purpura and ischemia of the distal portion of the foot. The purpuric lesions have irregular borders (marked with ink). B Purpura and milder ischemia of the distal fingers. A, Courtesy,  

*Patients who do not meet these criteria may still have antiphospholipid antibody syndrome. Table 23.5 Antiphospholipid antibody syndrome (APLS): Sapporo–Sydney criteria. The criteria allow for standardization of patients enrolled in clinical studies. GPL, IgG phospholipid units; MPL, IgM phospholipid units. Adapted from  

refs 65 & 69.

Epidemiology In a 1000-patient cohort of individuals with antiphospholipid antibody syndrome (APLS), there was a strong female predominance (82% women, 18% men) and the mean age was 42 ± 14 years at study entry. Fifty-three percent of the patients had primary APLS; secondary APLS was associated with lupus in 36%, with lupus-like syndromes in 5%, and with other diseases in the remaining 6%65. Catastrophic APLS occurred in 0.8% of the cohort. In contrast to primary cases, patients with lupus and APLS had more episodes of arthritis, livedo reticularis, thrombocytopenia, and leukopenia. Female patients had a higher frequency of arthritis, livedo reticularis and migraine, while male patients had a higher incidence of myocardial infarction, epilepsy, and arterial thrombosis in the lower legs and feet. Symptoms usually first developed in young to middle-aged individuals (2.8% before age 15 years, 12.7% after age 50 years). In a study of lupus patients, there was an association between aPL antibodies and the presence of cutaneous ulcers, livedo reticularis, and fingertip erythema66.

Jean L Bolognia, MD.

$

Pathogenesis

402

Antiphospholipid antibodies/lupus anticoagulants are a very important cause of purpuric cutaneous lesions and microvascular occlusion. Platelet activation leads to exposure of negatively charged platelet membrane phospholipids, followed by the sequential membrane-bound assembly of procoagulant enzyme–cofactor–substrate complexes, thrombin generation, and enzymatic conversion of fibrinogen to fibrin clot (see Fig. 22.4)63,67. Thrombin, which escapes downstream from clot formation, may bind to an endothelial surface protein, thrombomodulin. Thrombin–thrombomodulin binding converts thrombin activity from procoagulant to anticoagulant with high-affinity activation of protein C (see Fig. 22.4). Disturbance of the platelet or endothelial membrane may lead to exposure of neoantigens coexpressed with negatively charged phospholipids which localize to these enzyme assembly sites. It is likely that some physiologically relevant antiphospholipid or lupus anticoagulant antibodies are directed at the altered sites, and the antibodies may subsequently interfere with either: (1) normal surface protection against procoagulant enzyme assembly; or (2) the normal anticoagulant function of the thrombomodulin–protein C pathway. Evidence suggests that there are multiple mechanisms for aPL antibody-mediated thrombosis, including interference with production and release of prostacyclin by endothelial cells (leading to decreased

%

endothelial cell anticoagulant properties); interference with protein C and S pathways; activation of platelets by interaction with platelet membrane phospholipids (stimulating aggregation); interference with antithrombin III activity; interference with prekallikrein activation to kallikrein; interference with endothelial plasminogen activator release; and interference with possible protective functions of proteins such as β2-glycoprotein I or annexin V63,67.

Clinical features Cutaneous findings in patients with the APLS are listed in Table 23.6. In one large study, the incidences of cutaneous findings were: livedo reticularis, 24%; leg ulcers, 5.5%; pseudovasculitic lesions, 3.9%; digital gangrene, 3.3%; cutaneous necrosis, 2.1%; and splinter hemorrhages, 0.7%65 (Fig. 23.8). Cutaneous lesions may also develop



Pathology and laboratory Antiphospholipid antibodies and lupus anticoagulants are detected by different assays. Patients positive for one type of antibody may also be positive for another, usually because both subsets of antibodies are present rather than because of cross-reactivity between the antibodies. Detection of lupus anticoagulants remains the most specific screening test, although it is poorly predictive of thrombosis69. In vitro assays measure antibody interference with procoagulant assembly in the partial thromboplastin time, the dilute Russell viper venom time, and uncommonly, the prothrombin time. Despite prolonging coagulation assays in vitro, the lupus anticoagulant antibody usually interferes with anticoagulant activity in vivo, leading to thrombosis. Anti-cardiolipin antibodies, which are a type of aPL antibodies, are positive much more frequently than lupus anticoagulant antibodies, but their specificity for clinically significant disease is significantly lower. Clinically relevant aPL antibodies usually do not bind to phospholipid directly, but require a cofactor (usually a protein) before binding. The first recognized cofactor was β2-glycoprotein I, but other known cofactors include bound prothrombin, annexin V, and components of the thrombomodulin–protein C system. Unfortunately, cofactor-dependent anti-cardiolipin antibodies (to β2-glycoprotein I, annexin V, or other suspected targets) and lupus anticoagulants are present often enough in patients who do not develop thromboses that they are poor predictors of thrombosis risk in asymptomatic patients without previous thromboses. As mentioned previously, antiphosphatidyl serine/prothrombin antibodies may detect a subset of patients with APLS who have negative standard screening tests (see Table 23.5)67. Histologic features of early lesions typically reveal non-inflammatory thrombosis of small dermal vessels; later lesions may show inflammation following necrosis or with wound healing.

Differential diagnosis The differential diagnosis of APLS, beyond those syndromes discussed in this chapter, includes the diseases or syndromes associated with the findings in Table 23.6. In lupus patients, APLS is particularly likely to present as persistent moderate to extensive livedo reticularis or as livedoid vasculopathy (atrophie blanche; Fig. 23.9). Catastrophic APLS may mimic DIC or ADAMTS13 deficiency-mediated thrombotic microangiopathy. Vasculopathy due to levamisole-adulterated cocaine appears to be a form of drug-induced APLS. In recent years, levamisole has been detected in the majority of cocaine illicitly distributed in North America. The vasculopathy typically presents with retiform or necrotic purpura which may occur anywhere but often involves the ears, reminiscent of a cold-localized vasculopathy (see Ch. 89)70,71. Patients typically have neutropenia, aPL antibodies, and ANCAs. While both occlusion and vasculitis have been reported, biopsies of early lesions usually demonstrate fibrin clots.

Treatment APLS is treated with heparin, followed by chronic anticoagulation with oral vitamin K antagonists69,72. Aspirin therapy may be added for arterial events or stroke (after the acute event)69,72. The use of direct oral

anticoagulants is under investigation (see Table 22.8). In lupus patients with APLS, antimalarial therapy may be protective against thromboses72. Recommended treatment of catastrophic APLS includes anticoagulation and usually systemic corticosteroids; if life-threatening, plasma exchange and IVIg may be added73. Rituximab, cyclophosphamide, and eculizumab have also been used73,74.

CHAPTER

23 Cutaneous Manifestations of Microvascular Occlusion Syndromes

Fig. 23.9 Antiphospholipid antibody syndrome (APLS). Atrophie blanche-like scarring in a lupus patient with APLS. The lesions can also resemble those seen in malignant atrophic papulosis (Degos disease).

indirectly, i.e. by embolization from heart valve vegetations (see embolus section). In addition to the skin, many other organ systems may be involved, although deep vein thrombosis/pulmonary embolus and CNS disease are the most common extracutaneous manifestations. Catastrophic APLS is uncommon and precipitating factors include surgical procedures, drugs (e.g. sulfur-containing diuretics, captopril, oral contraceptives), discontinuation of anticoagulant therapy, and especially infections. These patients often present with multi-organ failure; the majority present with renal involvement as well as evidence of acute respiratory distress syndrome. Of note, an international consensus group is considering a new category of seronegative-APLS for patients with features suggestive of APLS, but who are consistently seronegative. This need is underscored by the apparent correlation of thrombosis with antiphosphatidyl serine/ prothrombin antibodies in patients who are otherwise negative for recognized laboratory markers for APLS (see Table 23.5)68.

DISORDERS OF VASCULAR COAGULOPATHIES WITH CUTANEOUS MANIFESTATIONS Sneddon Syndrome Synonym:  ■ Idiopathic livedo reticularis with cerebrovascular accidents

Key features ■ ■ ■ ■

Usually affects young women Persistent livedo reticularis or livedo racemosa Labile hypertension Recurrent neurologic symptoms due to cerebrovascular disease

Introduction This uncommon syndrome was first described in 196575. An estimated four new cases of Sneddon syndrome occur per million inhabitants per year76.

Pathogenesis Although Sneddon syndrome is often considered a manifestation of APLS, the prevalence of aPL antibodies in affected individuals varies from 0–85%77. In other patients it apparently represents a distinctive vasculopathy affecting smaller arteries and larger arterioles, especially in the skin and the brain. There is also significant clinical overlap with the autosomal recessive disorder adenosine deaminase 2 deficiency.

Clinical features Sneddon syndrome is characterized by persistent and usually widespread livedo racemosa, labile hypertension, and CNS disease (usually transient ischemic attacks, ischemic strokes or dementia). There is a female predominance, with onset in the third or fourth decade of life. A history of fetal loss and Raynaud phenomenon are other features. The livedo reticularis or racemosa may precede neurologic symptoms by several years. While a series of aPL antibody-negative patients with

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4

Sneddon syndrome were found to frequently have Libman–Sacks valvular disease, it did not explain the CNS involvement77. In one comparative study, the aPL antibody-negative group was less likely than the aPL antibody-positive group to have seizures, mitral regurgitation by echocardiography, clinically audible mitral regurgitation, and thrombocytopenia (1 cm in diameter75.

Pathology A 1–2 cm biopsy specimen from normal-appearing skin in the center of a livedo reticularis or racemosa ring (see Fig. 106.1) has been reported to have a sensitivity of 27% with one biopsy, 53% with two biopsies, and 80% with three biopsies. The characteristic, but not diagnostic, changes reported include endothelial inflammation, followed by subendothelial myointimal hyperplasia, with partial and complete occlusion of the involved arterioles78.

Livedoid Vasculopathy Synonyms:  ■ Atrophie blanche ■ Livedo reticularis with summer ulceration ■ Segmental hyalinizing vasculitis ■ Livedoid vasculitis

Key features ■ ■ ■ ■ ■

Favors the distal lower extremities, especially the ankles Female predominance Painful, punched-out ulcers White, round or stellate scars with peripheral telangiectasias Reticulated violaceous erythema may extend from ulcer

Differential diagnosis With livedo reticularis or livedo racemosa (“broken” livedo) as the characteristic cutaneous finding of this syndrome, other syndromes with persistent livedo reticularis should be considered (see Ch. 106). In a group of 32 patients with generalized broken (“racemose”) livedo and cerebrovascular accidents, 16 had an autoimmune disorder, thrombophilia, atherosclerosis, or an atrial myxoma79. Pediatric-onset livedo racemosa and stroke with or without polyarteritis nodosa should prompt consideration of adenosine deaminase 2 deficiency80 (Fig. 23.10). Screening for the presence of aPL antibodies should be part of the initial evaluation in patients with signs and symptoms of Sneddon syndrome. If, in addition to the traditional screens for aPL antibody and lupus anticoagulant activity, screening for antiprothrombin antibody is included, as many as 78% of the patients can have associated aPL antibodies81.

Treatment The primary treatment for Sneddon syndrome is warfarin, although this is not routinely effective82. Certainly, in patients with aPL antibodies or lupus anticoagulants, maintenance of anticoagulation at an INR of 2–3 seems warranted. Systemic corticosteroids or immunosuppressive agents do not appear to prevent cerebrovascular disease. In aPL antibody-negative patients, antiplatelet agents and anticoagulants appeared to be equally effective, so antiplatelet therapy (e.g. aspirin, clopidogrel) is favored77.

Fig. 23.10 Livedo racemosa of the arms in a patient with the autosomal recessive disorder adenosine deaminase 2 deficiency.  

Courtesy, Edward Cowen, MD.

Introduction This is a chronic cutaneous disease seen predominantly in young to middle-aged women. It can be divided into a primary (or idiopathic) form and a secondary form; the latter has been associated with a number of diseases, including chronic venous hypertension and varicosities as well as hypercoagulable states83. It seems reasonable to exclude cases of porcelain white scarring without antecedent punchedout ulcerations (see below).

Pathogenesis The pathogenesis of livedoid vasculopathy is unknown, but it is believed to involve an alteration in local or systemic control of coagulation with formation of fibrin thrombi focally within superficial dermal blood vessels. A number of prothrombotic factors have been associated with this syndrome, including aPL antibodies, protein C and S abnormalities, factor V Leiden mutation, prothrombin mutations, hyperhomocysteinemia, antithrombin III deficiency, and sticky platelet syndrome (see Table 105.9)84,85.

Clinical features Painful, persistent, and often punched-out ulcerations on the legs, especially over the malleoli and in women, should suggest this diagnosis (Fig. 23.11A). Some patients, particularly those with prominent livedo reticularis surrounding these ulcers, may develop retiform or stellate purpura or ulcer extension. Lesions tend to heal as white atrophic scars with peripheral telangiectasias. In ~50% of patients, an associated prothrombotic abnormality has been noted, but no studies with matched controls exist to strengthen a causative association. Lesions which mimic livedoid vasculopathy can be seen in patients with idiopathic and lupus-associated APLS86.

Pathology The characteristic histologic findings in livedoid vasculopathy are mild perivascular lymphocytic infiltrates and extravasated red cells surrounding superficial dermal vessels with hyalinized walls and luminal fibrin deposition31 (Fig. 23.11B). Immunofluorescence findings are nonspecific; in later stages, immunoglobulins (usually IgM) and C3 are deposited within vessel walls87.

Differential diagnosis The clinical presentation of this syndrome must be distinguished from other disorders that can cause inflammatory retiform purpura (see Ch. 22). Atrophie blanche-like lesions are not specific for livedoid vasculopathy; APLS, cutaneous small vessel vasculitis, sickle cell disease, and hydroxyurea-related leg ulcers can mimic this syndrome. Porcelain white scars in the setting of venous disease but without punctate ulcerations should be considered an unrelated syndrome.

Treatment 404

Anecdotally, successful treatment of this syndrome has been observed with antiplatelet, anticoagulant, and fibrinolytic therapies88. Anabolic agents such as danazol and stanozolol have been helpful in some



B, Courtesy, Lorenzo Cerroni, MD

above), lupus, and dermatomyositis94. Genetic predisposition, coagulation disorders, and autoimmunity have all been implicated95. There are two forms of idiopathic malignant atrophic papulosis – systemic and benign (skin-limited). In the systemic form, limited evidence supports a role for dysregulated interferon-α and the C5–9 membrane attack complex in the underlying endothelial injury95,96.

Clinical features Malignant atrophic papulosis is a rare vaso-occlusive disorder that predominantly affects the skin, gastrointestinal tract, and CNS92,93. Cutaneous lesions begin as crops of small (2 to 5 mm) erythematous papules on the trunk or extremities. These evolve over 2 to 4 weeks, with the development of central depression and ultimately a porcelain white scar, often with a rim of telangiectasias and an appearance similar to atrophie blanche. Cutaneous findings typically precede systemic manifestations. Gastrointestinal lesions can lead to bowel perforation, and, along with CNS manifestations (e.g. cerebrovascular accidents), are the leading causes of death. A single-center, cohort study of 39 patients found that the probability of having the benign form of disease was 70%, and after 7 years of skin-limited disease, the probability increased to 97%93.

Pathology $

Skin lesions are characterized histologically by a wedge-shaped area of ischemic dermis with a sparse perivascular lymphohistiocytic infiltrate at the edge of the ischemic area and an atrophic but slightly hyperkeratotic overlying epidermis. Edema and mucin deposition are found within the ischemic dermis, and in later stages sclerosis may be observed. The base of the lesion shows vascular damage with thrombosis, but examination of deeper tissue sections may be required for detection96,97.

CHAPTER

23 Cutaneous Manifestations of Microvascular Occlusion Syndromes

Fig. 23.11 Livedoid vasculopathy. A Punched-out ulcers are seen on the ankle as well as multiple stellate purpuric macules.   B Thrombi are seen within two dermal blood vessels in addition to a mild perivascular lymphocytic infiltrate.  

Differential diagnosis It is important to consider an underlying disease, e.g. lupus, dermatomyositis, APLS, as a possible cause of malignant atrophic papulosis-like lesions (see Fig. 23.9)92,95.

Treatment There is still no proven treatment for idiopathic malignant atrophic papulosis. Aspirin, dipyridamole, eculizumab (decreases C5–9 membrane attack complex deposition), and treprostinil have been reported as useful92,98. Mixed results have been seen with IVIg.

%

DISORDERS OF CELL-RELATED VASCULAR OCCLUSION Red Blood Cell Occlusion

instances, as has PUVA therapy89. For recalcitrant disease, prostanoids (e.g. alprostadil [PGE-1]), rivaroxaban, and IVIg have been used88,90,91. In patients with atrophie blanche-like lesions and lupus, antimalarial drugs may be helpful72. Patients on hydroxyurea with atrophie blanchelike lesions may need a trial off the drug.

Malignant Atrophic Papulosis

Red blood cells (RBCs) may foster vascular occlusion in several ways99. In high-flow conditions, RBCs push platelets to the vascular wall which encourages platelet interaction with damaged endothelium. Additionally, RBCs are the major source of membrane phosphatidyl serine which supports coagulation. Interactions via cellular adhesion molecules underlie the increased RBC adhesion in sickle cell disease and enhanced RBC–endothelial adhesion in polycythemia vera and severe malaria, usually due to Plasmodium falciparum. Patients with sickle cell disease and sickle trait may develop atrophie blanche-like lesions100.

Intravascular Cellular Occlusion Synonym:  ■ Degos disease

Introduction Malignant atrophic papulosis typically occurs between the second and fourth decades of life and has a slight female predominance. In some patients, it may be familial.

Pathogenesis Malignant atrophic papulosis is a small vessel vasculopathy92,93. Several diseases can mimic its cutaneous presentation, in particular APLS (see

Although chronic lymphocytic leukemia is the most common cause of a marked elevation of circulating atypical leukocytes, these cells are fragile and do not lead to vascular occlusion syndromes. Reduced perfusion of various organ systems may accompany high blast counts, nearly always of myelogenous origin. Cutaneous bland leukemic occlusion syndromes have not been reported, although repeated arterial occlusion from myeloblasts has been described (e.g. retinal artery, cerebral arteries)101. Leukemic vasculitis in the skin has been reported102. Intravascular lymphoma (B cell > T cell) is a very rare syndrome which is typically diagnosed post mortem, usually because of vague clinical findings. CNS involvement is often the most severe clinical manifestation. Skin lesions are commonly observed (40% of patients)

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This syndrome of progressive ischemic small vessel vasculopathy is associated with a very high mortality rate (see Chs 50 & 106)105–107. It is usually, but not always, seen in patients with advanced chronic kidney disease. Retiform purpura/necrosis is common, as is extreme pain and ulceration. Although multiple pathophysiologic abnormalities are reported, none have been proven as causative.

Brown Recluse Spider (Loxosceles) Bite Loxosceles envenomation may induce retiform purpura, ecchymoses, and ulcerations, along with a systemic coagulopathy108. There are more than 100 species worldwide; the brown recluse spider is found in North America, while most species live in South America. The cutaneous necrosis is undoubtedly multifactorial.

Hydroxyurea-Associated Vascular Occlusion

Fig. 23.12 Intravascular B-cell lymphoma. The clinical presentation in this patient was retiform purpura and necrosis with livedo reticularis. Courtesy, Lucinda  

Buescher, MD.

By unknown mechanisms, patients with myeloproliferative diseases treated with hydroxyurea may develop painful ulcers, usually in the perimalleolar region109. Some ulcers resemble those of livedoid vasculopathy, while others are larger and more shallow (see Fig. 130.5A)110. Of note, hydroxyurea-induced ulceration has triggered pyoderma gangrenosum. Histologically, vessel findings range from inflammatory (vasculitis) to thrombotic occlusion111.

but nonspecific and include erythematous, sometimes painful plaques or nodules and macular or telangiectatic lesions103. The lower extremities are the most common location (often in association with edema), followed by the trunk. Occasionally, it may present as retiform purpura (Fig. 23.12). The histopathologic finding of intraluminal occlusion by atypical lymphocytes can be missed on initial interpretation. Cutaneous intralymphatic histiocytosis is characterized by dilated lymphatic vessels filled with histiocytes, leading to overlying erythematous patches without purpura. This entity is also referred to as cutaneous intravascular histiocytosis, but in the vast majority of patients only lymphatic vessels are involved. It is often associated with chronic inflammation, rheumatoid arthritis, joint replacements or metal implants104.

Interferon-Associated Cutaneous Necrosis

DISORDERS OF OCCLUSION, MISCELLANEOUS

For additional online figures visit www.expertconsult.com

A number of cutaneous findings have been reported at interferon-β injection sites, including microvascular occlusion and evidence of cutaneous necrosis or necrotic panniculitis clinically112,113. While some blood vessels may have prominent perivascular inflammation, the thromboses are typically noted in the deep dermis or fat, often without inflammation. Systemic thrombotic microangiopathy (see above) has also been reported114.

Hematoma-Associated Retiform Purpura Retiform purpura with necrosis, best explained by compression of subcutaneous arterioles by large trauma-induced hematomas, has been observed in multiple patients, including those with hemophilia115.

Cutaneous Calciphylaxis Synonyms:  ■ Calcific arteriolopathy ■ Calcific uremic arteriolopathy

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23 Cutaneous Manifestations of Microvascular Occlusion Syndromes

25. Monti G, Saccardo F, Castelnovo L, et al. Prevalence of mixed cryoglobulinemia syndrome and circulating cryoglobulins in a population-based survey: the Origgio study. Autoimmunity Rev 2014;13:609–14. 26. Michaud M, Pourrat J. Cryofibrinogenemia. J Clin Rheumatol 2013;19:142–8. 27. Saadoun D, Elalamy I, Ghillani-Dalbin P, et al. Cryofibrinogenemia: new insights into clinical   and pathogenic features. Am J Med 2009;122:  1128–35. 28. Berenstsen S, Beiske K, Tjonnfjord GE. Primary chronic cold agglutinin disease: an update on pathogenesis, clinical features and therapy. Hematology 2007;12:361–70. 29. Jeskowiak A, Goerge T. Cutaneous necrosis associated with cold agglutinins. N Engl J Med 2013;369:e1. 30. Stone MS, Piette WW, Davey WP. Cutaneous necrosis at sites of transfusion: cold agglutinin disease. J Am Acad Dermatol 1988;19:356–7. 31. Robson K, Piette W. The presentation and differential diagnosis of cutaneous vascular occlusion syndromes. Adv Dermatol 1999;15:153–82. 32. Oh CC, Ong TH, Busmannis I, Wijaya L. An 81-year-old man with cutaneous periumbilical purpura. Chest 2012;141:818–21. 33. Weiser JA, Scully BE, Bulman WA, et al. Periumbilical parasitic thumbprint purpura: Strongyloides hyperinfection syndrome acquired from a cadaveric renal transplant. Transpl Infect Dis 2011;13:58–62. 34. Nunzie E, Ortega Cabrera LV, Macanchi Moncayo FM, et al. Lucio leprosy with Lucio’s phenomenon, digital gangrene and anticardiolipin antibodies. Lepr Rev 2014;85:194–200. 35. Kamath S, Vaccaro SA, Rea TH, Ochoa MT. Recognizing and managing the immunologic reactions in leprosy. J Am Acad Dermatol 2014;71:795–803. 36. Shadi Kourosh A, Cohen JB, Scollard DM, Nations SP. Leprosy of Lucio and Latapi with extremity livedoid vascular changes. Int J Dermatol 2013;52:1245–7. 37. Woods CR. Rocky mountain spotted fever in children. Pediatr Clin N Am 2013;60:455–70. 38. Walker DH. Ricketssia rickettsii and other spotted fever group Rickettsiae (Rocky Mountain spotted fever and other spotted fevers). In: Mandell GL, Bennett JE, Dolin R, editors. Principles and Practice of Infectious Diseases. 7th ed. Philadelphia: Churchill Livingstone/ Elsevier; 2010. p. 2499–507. 39. Alvaz O, Turegano MM, Radfar A. A purpuric patch on the flank. JAMA Dermatol 2015;151:97–8. 40. Lawson JM. Cholesterol crystal embolization: more common than we thought? Am J Gastroenterol 2001;96:3230–2. 41. Hirschmann JV, Raugi GJ. Blue (purple) toe syndrome. J Am Acad Dermatol 2009;60:1–20. 42. Mulay SR, Evan A, Anders H-J. Molecular mechanisms of crystal-related kidney inflammation and injury. Implications for cholesterol embolism, crystalline nephropathies and kidney stone disease. Nephrol Dial Transplant 2014;29:507–14. 43. Jucgla A, Moreso F, Muniesa C, et al. Cholesterol embolism. J Am Acad Dermatol 2006;55:786–93. 44. Tran BA, Egbers R, Lowe L, et al. Cholesterol embolization syndrome with an atypical proximal presentation simulating calciphylaxis. JAMA Dermatol 2014;150:903–4. 45. Blackmon JA, Jeffy BG, Malone JC, Knable AL Jr. Oxalosis involving the skin. Arch Dermatol 2011;147:1302–5. 46. Marconi V, Mofid MZ, McCall C, et al. Primary hyperoxaluria: report of a patient with livedo reticularis and digital infarcts. J Am Acad Dermatol 2002;46:S16–18. 47. Gammon B, Longmire M, DeClerck B. Intravascular crystal deposition: an early clue to the diagnosis of type 1 cryoglobulinemic vasculitis. Am J Dermatopathol 2014;36:751–3. 48. Ommen SR, Seward JB, Tajik AJ. Clinical and echocardiographic features of hypereosinophilic syndromes. Am J Cardiol 2000;86:110–13. 49. Liao Y-H, Su Y-W, Tsay W, Chiu H-C. Association of cutaneous necrotizing eosinophilic vasculitis and deep vein thrombosis in hypereosinophilic syndrome. Arch Dermatol 2005;141:1051–3. 50. Song JK, Jung SS, Kang SW. Two cases of eosinophilic vasculitis with thrombosis. Rheumatol Int 2008;28:371–4. 51. Price VE, Ledingham DL, Krumpel A, Chan AK. Diagnosis and management of neonatal purpura fulminans. Semin Fetal Neonatal Med 2011;16:  318–22.

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102. Seckin D, Senol A, Gurbuz O, Demirkesen C. Leukemic vasculitis: an unusual manifestation of leukemia cutis. J Am Acad Dermatol 2009;61:519–21. 103. Roglin J, Boer A. Skin manifestations of intravascular lymphoma mimic inflammatory diseases of the skin. Br J Dermatol 2007;157:16–25. 104. Requena L, El-Shabrawi-Caelen L, Walsh SN, et al. Intralymphatic histiocytosis. A clinicopathologic study of 16 cases. Am J Dermatopathol 2009;31:140–  51. 105. Vedvyas C, Winterfield LS, Vleugels RA. Calciphylaxis: a systematic review of existing and emerging therapies. J Am Acad Dermatol 2012;67:e253–60. 106. Nigwekar SU, Kroshinsky D, Nazarian RM, et al. Calicphylaxis: risk factors, diagnosis and treatment. Am J Kidney Dis 2015;66:133–46.

107. Zembowicz A, Navarro P, Walters S, et al. Subcutaneous thrombotic vasculopathy syndrome: an ominous condition reminiscent of caliphylaxis: calciphylaxis sine calcifications? Am J Dermatopathol 2011;33:796–802. 108. Kand JK, Bhate C, Schwartz RA. Spiders in dermatology. Semin Cutan Med Surg 2014;33:123–7. 109. Quattrone F, Dini V, Barbanera S, et al. Cutaneous ulcers associated with hydroxyurea therapy. J Tissue Viability 2013;22:112–21. 110. Matthews AG, Wylie G. Hydroxycarbamide-induced cutaneous ulceration with a difference. Br J Dermatol 2014;171:1555–608. 111. Weinlich G, Schuler G, Greil R, et al. Leg ulcers associated with long-term hydroxyurea therapy. J Am Acad Dermatol 1998;39:372–5.

112. Ohata U, Hara H, Yoshitake M, Terui T. Cutaneous reactions following subcutaneous β-interferon-1b injection. J Dermatol 2010;37:179–81. 113. Ball NJ, Cowan BJ, Hashimoto SA. Lobular panniculitis at the site of subcutaneous interferon beta injections for the treatment of multiple sclerosis can histologically mimic pancreatic panniculitis. A study of 12 cases. J Cutan Pathol 2009;36:331–7. 114. Hunt D, Kavanagh D, Drummond I, et al. Thrombotic microangiopathy associated with interferon beta. N Engl J Med 2014;370:1270–1. 115. Kaya G, Jacobs F, Prins C, et al. Deep dissecting hematoma: an emerging severe complication of dermatoporosis. Arch Dermatol 2008;144:1303–8.

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CHAPTER

eFig. 23.1 Cold agglutinin disease – histopathologic findings. Within the entire thickness of the dermis, there are dilated blood vessels with an intravascular proliferation of endothelial cells. Deposits of cold agglutinins are seen as intravascular amorphous eosinophilic material admixed with many red blood cells (inset). There is also hemorrhage within the dermis. Courtesy, Luis  

Requena, MD.

eFig. 23.2 Cutaneous emboli from an atrial myxoma. An arteriole within the deeper dermis has its lumen occluded by mucinous material. Courtesy, Luis Requena,  

MD.

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408.e1

URTICARIAS, ERYTHEMAS AND PURPURAS SECTION 4

Cutaneous Vasculitis David A. Wetter, Jan P. Dutz, Kanade Shinkai and Lindy P. Fox

Chapter Contents Classification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 409 Epidemiology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 409 Pathogenesis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 409 General clinical features . . . . . . . . . . . . . . . . . . . . . . . . . . . 409 Pathology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 410 Differential diagnosis . . . . . . . . . . . . . . . . . . . . . . . . . . . . .412 Cutaneous small vessel vasculitis . . . . . . . . . . . . . . . . . . . . . 412 Predominantly small and medium-sized vessel vasculitides . . . . 425 Predominantly medium-sized vessel vasculitis . . . . . . . . . . . . 433 Temporal arteritis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 436 Diagnostic approach to patients with vasculitis . . . . . . . . . . . 436

Key features ■ Cutaneous signs of vasculitis are a reflection of the size of the vessels involved ■ Vasculitis can be limited to the small vessels of the skin or it can be a sign of life-threatening internal organ involvement ■ The clinical diagnosis of cutaneous vasculitis requires histopathologic confirmation, and multiple biopsies may be required

24 

the clinical presentation and the corresponding histologic findings, this type of classification scheme will be employed in this chapter (see Table 24.1). Additional features that aid in classifying cutaneous vasculitis are systemic manifestations, direct immunofluorescence findings, and the presence or absence of antineutrophil cytoplasmic antibodies (ANCAs). Despite descriptions of distinct vasculitic syndromes, there are no unique diagnostic criteria, and clinicopathologic correlation is always required.

EPIDEMIOLOGY The annual, population-based incidence of biopsy-proven cutaneous LCV is ~45 per million; this figure includes various subtypes such as urticarial vasculitis, cryoglobulinemic vasculitis, and ANCA-associated vasculitis3. Cutaneous vasculitis occurs in all age groups (mean age in adults, 47 years; mean age in children, 7 years), has a slight female predominance4,5, and is much more common in adults than in children. The majority of children have Henoch–Schönlein purpura.

PATHOGENESIS CSVV is mediated by immune complexes that form in the presence of antigen excess, and after their deposition within postcapillary venules, these complexes lead to complement-mediated chemotaxis of neutrophils (Fig. 24.1A). In ANCA-associated vasculitides, vessel wall damage is directly mediated by neutrophils rather than by immune complex deposition (Fig. 24.1B), hence the term “pauci-immune” vasculitides.

GENERAL CLINICAL FEATURES INTRODUCTION Vasculitis represents a specific pattern of inflammation of the blood vessel wall and it can occur in any organ system of the body. Cutaneous vasculitis may be: (1) a skin-limited disease; (2) a primary cutaneous vasculitis with secondary systemic involvement; or (3) a cutaneous manifestation of a systemic vasculitis. Vasculitis can affect small, medium-sized, or large vessels of the arterial and/or venous systems (Table 24.1). Small vessels include arterioles, capillaries, and postcapillary venules, which are found in the superficial and mid dermis of the skin. Medium-sized vessels refer to the small arteries and veins that reside within the deep dermis or subcutis. Large vessels include the aorta and named arteries. Cutaneous involvement occurs almost exclusively with vasculitis of small and medium-sized vessels; therefore, the large vessel vasculitides are discussed briefly or mentioned in Table 24.1. In this chapter, cutaneous vasculitis refers to vasculitis with any underlying etiology and affecting any sized vessel in which the clinical manifestations include the skin. Cutaneous small vessel vasculitis (CSVV) is synonymous with cutaneous leukocytoclastic vasculitis (LCV) and refers to involvement of the postcapillary venules of the dermis by intense neutrophilic vascular inflammation.

CLASSIFICATION Two major classification schemes are the American College of Rheumatology 1990 criteria1 and the 2012 revised International Chapel Hill Consensus Conference Nomenclature system2. Because a system based upon the predominant size of the involved blood vessel helps to predict

The skin lesions of CSVV usually appear 7–10 days after the triggering event. In systemic vasculitic syndromes, signs of systemic involvement often precede the appearance of associated cutaneous lesions (average, 6 months), but the interval can be as short as days or as long as years4. As noted previously, the cutaneous findings of vasculitis depend upon the predominant size of the vessels that are involved. CSVV typically presents with palpable or macular purpura, but urticarial papules, pustules, vesicles, petechiae, or targetoid lesions can be seen (Figs 24.2 & 24.3). The lesions favor dependent sites, as well as areas under tightfitting clothing, reflecting the influence of hydrostatic pressure and stasis on the pathophysiology. In general, the lesions are asymptomatic, but they may itch, burn, or sting. In medium-sized vessel vasculitis, the affected blood vessels reside within the reticular dermis or subcutis. As a result, the latter typically presents with livedo racemosa, retiform purpura, ulcers, subcutaneous nodules, and/or digital necrosis. In general, the presence of ulcers or necrosis suggests deeper arterial involvement. The combination of palpable purpura (or other signs of CSVV) plus signs of medium-sized vessel disease points to a “mixed” pattern of vasculitis (see Table 24.1), as is seen in ANCA-associated vasculitides or autoimmune connective tissue disease-associated vasculitis. Arthralgias and arthritis as well as constitutional symptoms such as fever, weight loss, and malaise can be manifestations of vasculitis of any sized vessel5. For patients with systemic involvement, presenting symptoms and signs (e.g. abdominal pain, paresthesias, hematuria) will vary according to the affected organs. In a population-based study of 84 patients with biopsy-proven cutaneous LCV, 39 patients (46%) had systemic manifestations, with renal involvement most commonly observed (17 of 39 patients); recurrent disease (mean duration of disease activity, 2 years) was observed in 30% of patients3.

409

A diverse array of entities can present with cutaneous vasculitis, and the characteristic skin findings reflect the caliber of inflamed blood vessel – small, medium-sized, or large. While cutaneous small vessel vasculitis is often idiopathic, it may be due to an infection (e.g. hepatitis C virus), medication (e.g. penicillins), autoimmune connective tissue disease (e.g. Sjögren syndrome), or systemic vasculitis (e.g. granulomatosis with polyangiitis [Wegener granulomatosis]). As a result, after the diagnosis of cutaneous vasculitis has been established via clinicopathologic correlation, further evaluation includes a directed search for any underlying etiology and evidence of systemic involvement. Treatment of cutaneous vasculitis depends upon many factors including the underlying cause, severity, and sites of internal involvement.

ANCA-associated vasculitis, cryoglobulin, cutaneous small vessel vasculitis, cutaneous vasculitis, erythema elevatum diutinum, Henoch–Schönlein purpura, IgA vasculitis, leukocytoclastic vasculitis, purpura, urticarial vasculitis, acute hemorrhagic edema of infancy, cryoglobulinemic vasculitis, granulomatosis with polyangiitis, Wegener granulomatosis, eosinophilic granulomatosis with polyangiitis, Churg–Strauss syndrome, microscopic polyangiitis, polyarteritis nodosa, temporal arteritis

CHAPTER

24 Cutaneous Vasculitis

ABSTRACT

non-print metadata KEYWORDS:

409.e1

SECTION

Urticarias, Erythemas and Purpuras

4

CUTANEOUS VASCULITIS CLASSIFICATION SCHEME

Caliber of the predominantly affected vessel

Classification

Subclassification or etiologies

Morphology of cutaneous lesions

Small

Cutaneous small vessel vasculitis (CSVV)

Henoch–Schönlein purpura, including IgA vasculitis in adults Acute hemorrhagic edema of infancy Urticarial vasculitis Erythema elevatum diutinum Cryoglobulinemic vasculitis (types II and III) Secondary causes of CSVV (see Table 24.4): – Drug exposure – Infections – AI-CTD – Malignancies, most often hematologic

Palpable purpura (most common) Petechiae Macular purpura Urticarial papules Vesicles Pustules Targetoid papules and plaques

Small and mediumsized (“mixed”)

ANCA-associated

Microscopic polyangiitis Granulomatosis with polyangiitis (Wegener granulomatosis) Eosinophilic granulomatosis with polyangiitis (Churg–Strauss syndrome) Drug-induced

Secondary causes

Infections Inflammatory disorders (e.g. AI-CTD)

Petechiae Palpable purpura Livedo racemosa Retiform purpura Ulcers Subcutaneous nodules Digital necrosis

Medium-sized

Polyarteritis nodosa (PAN)

Classic (systemic) PAN Cutaneous PAN

Large*

Temporal arteritis

Early – erythematous or cyanotic skin, alopecia, purpura, tender nodules on frontotemporal scalp Late – ulceration and/or gangrene of frontotemporal scalp or tongue

Takayasu arteritis (disease)

Erythematous subcutaneous nodules ± ulceration, pyoderma gangrenosum-like lesions on the extremities (lower > upper) May have evidence of small and/or medium-sized vessel vasculitis

Livedo racemosa Retiform purpura Ulcers Subcutaneous nodules Digital necrosis

*Cutaneous manifestations are rare. Table 24.1 Cutaneous vasculitis classification scheme. AI-CTD, autoimmune connective tissue diseases; ANCA, antineutrophil cytoplasmic antibodies.  

PATHOLOGY

410

Timing and appropriate sampling of the most likely involved vessel increase the diagnostic yield of a skin biopsy. Ideally, lesions should be biopsied within the first 24 to 48 hours of appearance. When CSVV is suspected, a biopsy specimen for direct immunofluorescence should be obtained, as the presence of certain immunoglobulins (e.g. IgA) may suggest a particular diagnosis and influence prognosis. In general, punch biopsies are adequate for the diagnosis of CSVV while an incisional or excisional biopsy may be required to diagnose vasculitis of larger vessels. In cutaneous vasculitis, the histologic findings vary depending upon the type and age of the sampled lesion in addition to the size of the affected vessel. The classic histopathologic features of CSVV are referred to as LCV and consist of transmural infiltration of the walls of small vessels (primarily postcapillary venules) by neutrophils undergoing karyorrhexis of their nuclei, as well as fibrinoid necrosis of the damaged vessel walls (Fig. 24.4). Other findings include leukocytoclasia (degranulation and fragmentation of neutrophils, leading to the production of nuclear dust), extravasated erythrocytes, and signs of endothelial cell damage. However, lesions present for greater than 48 to 72 hours may have a predominantly mononuclear rather than neutrophilic infiltrate. Palpable purpura, the most common clinical lesion of CSVV, can be explained by the infiltrate of leukocytes (palpability) and the resulting extravasation of RBCs from the damaged blood vessel (purpura). Additional histological findings may provide clues to the underlying etiology, e.g. eosinophils in drug-induced CSVV (up to 100% of

cases)6, thrombi plus CSVV in patients exposed to levamisole-tainted cocaine, and thrombi plus dense dermal inflammation in septic vasculitis. Involvement of deeper dermal vessels alerts the clinician to look for an underlying etiology rather than presuming the CSVV is idiopathic7. Vasculitis of medium-sized blood vessels is characterized by similar changes involving the vessels (e.g. small arteries) of the deep reticular dermis and subcutaneous fat. Neovascularization of the adventitia, in the form of small capillaries, is commonly seen in older lesions of medium-sized vessel vasculitis. In ~80% of cases of CSVV, direct immunofluorescence (DIF) demonstrates deposition of C3, IgM, IgA and/or IgG (generally in that order of frequency) in a granular pattern within the vessel walls4. Immunoglobulin deposition is highest (up to 100%) in skin lesions present for ≤48 hours4. On the other hand, in 30% of samples obtained 48–72 hours after lesion onset, DIF will be negative for immunoglobulins, and only C3 will be detected in lesions present for >72 hours4. In patients with an ANCA-positive vasculitis, the DIF of lesional skin is usually negative. After controlling for duration, it is preferable to biopsy more proximal lesions for DIF in order to avoid nonspecific vascular fluorescence that can occur in sites of greatest hydrostatic pressure. As stated previously, the term CSVV is routinely equated with LCV. However, there are additional forms of cutaneous vasculitis, in particular lymphocytic (Table 24.2) and granulomatous (see below)8. Use of the term lymphocytic vasculitis often requires clarification, especially in discussions with non-dermatologists.

CHAPTER

24 Cutaneous Vasculitis

PATHOGENESIS OF CUTANEOUS VASCULITIS Immune complex-mediated

A Early

Mid

Late

Blood vessel C

C

C

C Mast cell

Circulating antigen–antibody immune complexes

Mast cell degranulation leads to increased vascular permeability

Immune complex deposition on blood vessel walls with subsequent activation of complement (C) leads to inflammatory cascades and mast cell recruitment

Antigen

Antibody

Inflammatory mediators Collagenase, elastase Complement-derived factors (C3a, C5a) lead to neutrophil chemotaxis Neutrophil degranulation results in release of inflammatory mediators, collagenase and elastase

Vessel wall necrosis, thrombosis, occlusion, hemorrhage

Erythrocyte

ANCA-mediated

B Early

Mid

Late

Neutrophil

Reactive O2 species Chemoattractants

Vessel wall damage Cytokine priming leads to: 1. ANCA antigens (PR3, MPO) becoming expressed on the neutrophil surface 2. Neutrophils and endothelial cells having increased expression of adhesion molecules

Adhesion molecule

PR3

MPO

Circulating ANCA antibodies: Activate neutrophils to release reactive oxygen species, proinflammatory mediators and chemoattractants

Leads to: 1. Vessel wall damage 2. Recruitment of more neutrophils and inflammation

ANCA antibody

Fig. 24.1 Pathogenesis of cutaneous vasculitis – immune complex- versus antineutrophil cytoplasmic antibody (ANCA)-mediated. A In immune complexmediated vasculitis, circulating antigens (e.g. infectious agents, medications, neoplasms) induce antibody formation. Binding of antibodies to circulating antigens creates immune complexes. Immune complex deposition within postcapillary venules activates complement and subsequently leads to an increase in adhesion molecule expression on the endothelium. Complement split products (C3a and C5a) induce mast cell degranulation and neutrophil chemotaxis. Mast cell degranulation leads to increased vascular dilation and permeability, enhancing immune complex deposition and leukocyte tethering to endothelium. Increased adhesion between inflammatory cells (especially neutrophils) and the endothelium is mediated by elevated expression of selectins (E-selectin, P-selectin) and members of the immunoglobulin superfamily (ICAM-1, VCAM-1, PECAM-1) on endothelial cells in concert with the upregulation of their corresponding ligands and receptors/adhesion molecules on leukocytes (e.g. P-selectin glycoprotein ligand-1, LFA-1, Mac-1) (see Ch. 102 for details). Neutrophils release proteolytic enzymes (such as collagenases and elastases) and free oxygen radicals that damage the vessel wall. In addition, formation of the membrane attack complex (C5–C9) on the endothelium leads to the activation of the clotting cascade and the release of cytokines and growth factors with ensuing thrombosis, inflammation, and angiogenesis. B In ANCA-mediated vasculitis, following primary activation by cytokines such as tumor necrosis factor (TNF)-α, intracellular proteins from neutrophils (e.g. proteinase 3 [PR3], myeloperoxidase [MPO]) become expressed on the cell surface. After formation of ANCAs that recognize these antigens, binding of the autoantibodies to neutrophils leads to increased neutrophil adhesion to vessel walls and subsequent cellular activation. Neutrophils then release reactive oxygen species and other toxic mediators that result in vessel wall damage (see A). Because the vessel damage in ANCA-positive vasculitides is directly mediated by neutrophils rather than by immune complexes, they are referred to as “pauci-immune” vasculitides. Formation of ANCAs may be related to an impairment in neutrophil apoptosis which results in a prolonged opportunity for autoantibody development.  

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SECTION

4

Fig. 24.2 Cutaneous small vessel vasculitis. A Classic presentation of purpuric macules and papules on the distal lower extremities; note the purple color. B Early lesions may be erythematous rather than purpuric. C With time, the inflammatory lesions can no longer be blanched due to hemorrhage within the dermis. D Central necrosis with formation of hemorrhagic crusts. C, Courtesy, Kalman

Urticarias, Erythemas and Purpuras



Watsky, MD; D, Courtesy, Frank Samarin, MD.

A

B

C

D

LYMPHOCYTIC VASCULITIS Defined histologically as a perivascular lymphocytic dermal infiltrate with associated damage to the walls of small blood vessels; findings may range from extravasated RBCs and swelling or hyperplasia of endothelial cells to fibrin deposition and fibrinoid necrosis of the vessel wall • Most commonly seen in: Pernio Pityriasis lichenoides et varioliformis acuta (PLEVA) Resolving leukocytoclastic vasculitis Rickettsial, viral infections Autoimmune connective tissue diseases, e.g. lupus erythematosus, relapsing polychondritis Behçet disease Hypercoagulable disorders, e.g. Sneddon syndrome Lymphocytic thrombophilic arteritis (macular arteritis) Panniculitis, including lupus •

Table 24.2 Lymphocytic vasculitis. This topic is one where there is ongoing debate. Most common entities in bold. RBC, red blood cell.  

DIFFERENTIAL DIAGNOSIS Several disorders can present with skin lesions that resemble the various cutaneous manifestations of vasculitis and they are listed in Table 24.3.

CUTANEOUS SMALL VESSEL VASCULITIS

412

Synonyms:  ■ Cutaneous leukocytoclastic vasculitis ■ Cutaneous leukocytoclastic angiitis ■ Hypersensitivity angiitis ■ Cutaneous necrotizing venulitis

Key features ■ Palpable purpura, urticarial lesions, and/or hemorrhagic macules or vesicles; occasionally, targetoid lesions, pustules, and ulcerations ■ Lesions favor the lower extremities (especially the ankles), dependent areas, or pressure points ■ Only involves small vessels, primarily postcapillary venules ■ Histopathologically, leukocytoclastic vasculitis is seen ■ Extracutaneous involvement occurs in up to 30% of patients, but it is usually mild

CHAPTER

Cutaneous Vasculitis

24

A

B E

C

D

Fig. 24.3 Clinical variants of cutaneous small vessel vasculitis. A Targetoid appearance that can resemble erythema multiforme. B Hemorrhagic vesicles in addition to palpable purpura. C Hemorrhagic crusts in an annular configuration. D Lesions limited to the upper extremities. E Purpuric macules and papules with areas of confluence that resembles purpuric morbilliform drug eruption. A, Courtesy, Kalman Watsky, MD.  

Introduction CSVV is a vasculitic process that involves primarily the dermal postcapillary venules and is characterized histologically by LCV. Although CSVV with LCV can be seen in the setting of mixed (small and medium-sized vessel) vasculitides (see Table 24.1), the term CSVV is generally reserved for small vessel vasculitis of the skin without medium-sized vessel involvement, irrespective of the clinical severity of the skin disease or the underlying etiology. CSVV is often idiopathic in nature, but may be secondary to an underlying cause such as an infection or medication (Table 24.4). Within the spectrum of CSVV are several subtypes whose rather unique epidemiologic and clinical features warrant subclassification (see Table 24.1) and separate discussion.

Epidemiology

Fig. 24.4 Cutaneous small vessel vasculitis – histopathologic features. Angiocentric segmental inflammation with endothelial swelling, a neutrophilic infiltrate with leukocytoclasia, red blood cell extravasation, and fibrinoid necrosis of blood vessel walls. The neutrophils are present around and within the walls of the small dermal blood vessels. Courtesy, David F Fiorentino, MD.  

CSVV occurs in both sexes and at all ages9, but is more common in the adult population. It is estimated that ~10% of those affected are children. The annual population-based incidence of CSVV (excluding those with a distinct clinical subtype of CSVV) is 21 cases per million3.

Pathogenesis CSVV is mediated by immune complex deposition (see Fig. 24.1A).

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CLINICAL DIFFERENTIAL DIAGNOSIS OF CUTANEOUS VASCULITIS

Clinical presentation

Differential diagnosis

Palpable purpuric papules/plaques

Arthropod bites Morbilliform drug eruptions with hemorrhage in dependent sites Erythema multiforme Pityriasis lichenoides et varioliformis acuta Infectious emboli (septic vasculitis) due to bacteria (e.g. Neisseria meningococcus [acute meningococcemia]), rickettsiae, fungi (e.g. Rhizopus) Lichenoid capillaritis (pigmented purpura) Cellulitis

Purpuric macules/patches

Hemorrhage – Trauma – Solar (actinic) purpura * – Medication-related (i.e. aspirin, topical or systemic corticosteroids) * – Thrombocytopenia and platelet dysfunction – Coagulopathies * – Viral exanthems (e.g. enterovirus, parvovirus B19) – Scurvy – Primary systemic amyloidosis Thromboses – Hypercoagulable state (e.g. antiphospholipid antibody; see Table 105.9) – Livedoid vasculopathy – Purpura fulminans (e.g. due to sepsis/DIC) – Heparin necrosis – Warfarin (Coumadin®) necrosis – Thrombotic thrombocytopenic purpura – Hemolytic uremic syndrome – Paroxysmal nocturnal hemoglobinuria Emboli – Cholesterol – Cardiac (infective endocarditis ≫ myxomatous or marantic) – Fat – Air Cold-related gelling – Cryoglobulins (primarily type I) Inflammation – Pigmented purpura (capillaritis) – Hypergammaglobulinemic purpura of Waldenström Infection – Lucio phenomenon (leprosy) – Strongyloidiasis

Urticarial lesions

Urticaria (including neutrophilic urticaria) Arthropod bites and papular urticaria Urticaria multiforme Serum sickness-like reaction Autoinflammatory diseases (e.g. periodic fevers; see Table 45.2) Still disease, including adult-onset Schnitzler syndrome Viral exanthems Kawasaki disease Sweet syndrome Urticarial phase of bullous pemphigoid

Ulcers ± atrophie blanche

Venous hypertension or peripheral arterial disease Pyoderma gangrenosum Livedoid vasculopathy Hypercoagulable state (e.g. antiphospholipid antibodies; see Table 105.9) Calciphylaxis Infections (e.g. bacterial, mycobacterial, dimorphic or opportunistic fungal, protozoal) Hemoglobinopathies Factitial Halogenodermas Degos disease See Fig. 105.1 for additional entities

Nodules

Panniculitis Superficial migratory thrombophlebitis Dermal neoplasms Infections (e.g. bacterial, mycobacterial, dimorphic or opportunistic fungal)

Livedo reticularis

See Chapter 106

*Element of trauma. 414

Table 24.3 Clinical differential diagnosis of cutaneous vasculitis. DIC, disseminated intravascular coagulation.  

CHAPTER

24

Clinical presentation

Differential diagnosis

Digital gangrene

Arterial occlusive disease, including atherosclerosis Diabetes mellitus Thromboangiitis obliterans (Buerger disease) Systemic sclerosis Emboli (e.g. cholesterol, septic) Cryoglobulinemia (type I) > cryofibrinogenemia or cold agglutinin disease Thrombosis (e.g. antiphospholipid syndrome, purpura fulminans, myeloproliferative thrombocytosis) Calciphylaxis Hypereosinophilic syndrome Paraneoplastic acral vascular syndrome (e.g. with lung or ovarian carcinoma)

Cutaneous Vasculitis

CLINICAL DIFFERENTIAL DIAGNOSIS OF CUTANEOUS VASCULITIS

Table 24.3 Clinical differential diagnosis of cutaneous vasculitis. (cont’d)  

UNDERLYING CAUSES OF SECONDARY CUTANEOUS VASCULITIS

Association

Incidence

Agent/Disease Common

Idiopathic

50%

Infection

15–20%

Uncommon

Rare

Neisseria meningococcus (in chronic meningococcemia) Mycobacterium tuberculosis Atypical mycobacteria

Mycoplasma pneumoniae Chlamydophila pneumoniae, Chlamydia trachomatis Brucella Bartonella henselae Salmonella Campylobacter Yersinia enterocolitica Treponema pallidum

Neisseria meningitidis (acute) Neisseria gonorrhea Staphylococcus aureus Rickettsiae Gram-negative rods Escherichia coli Klebsiella Pseudomonas Disseminated fungal infections (immunocompromised hosts) Candida Aspergillus Fusarium Mucor

Francisella tularensis

Upper respiratory tract infection Hepatitis C > B ≫ A, including vaccines

HIV Parvovirus B19

Cytomegalovirus Varicella zoster virus Influenza virus, including vaccine

Autoimmune connective tissue diseases – Rheumatoid arthritis ** – SLE – Sjögren syndrome

Inflammatory bowel disease Behçet disease Hypergammaglobulinemic purpura of Waldenström Seronegative spondyloarthropathies

Sarcoidosis Cystic fibrosis‡ Primary biliary cirrhosis Bowel-associated dermatosis–arthritis syndrome Gluten enteropathy

Bacterial Beta-hemolytic streptococci, especially group A Mycobacterium leprae

Septic vasculitis* Infective endocarditis

Viral

Inflammatory disorders

15–20%

*Histopathology varies and includes leukocytoclastic vasculitis, organisms within the vessel wall and non-inflammatory thrombotic purpura. Rheumatoid vasculitis typically occurs in seropositive patients with elevated inflammatory markers; cutaneous vasculitis is the most common presentation, followed by vasculitic neuropathy. ** ‡ May be associated with antineutrophil cytoplasmic antibodies (ANCAs).

Table 24.4 Underlying causes of secondary cutaneous vasculitis. HIV, human immunodeficiency virus; SLE, systemic lupus erythematosus.  

Continued

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Urticarias, Erythemas and Purpuras

4

UNDERLYING CAUSES OF SECONDARY CUTANEOUS VASCULITIS

Association

Incidence

Agent/Disease Common

Uncommon

Rare

Drug exposure†

10–15%

Antibiotics, esp. β-lactams Penicillins Cephalosporins, esp. cefaclor Sulfonamides Minocycline‡ Quinolones Macrolides Cardiovascular Thiazides Hydralazine‡ Quinidine Other Allopurinol Bortezomib D-penicillamine G-CSF NSAIDs Propylthiouracil/other antithyroid agents‡ Serum (e.g. ATG) Streptokinase

Antimicrobials Quinine Vancomycin Cardiovascular ACE inhibitors Beta-blockers Furosemide Other Cocaine adulterated with levamisole‡ COX-2 inhibitors Interferons Leukotriene inhibitors‡,§ Methotrexate Oral contraceptives Phenytoin Retinoids Sirolimus Sulfonylureas TNF-α inhibitors Warfarin

Antimicrobials Mefloquine Cardiovascular Amiodarone Neuropsychiatric Atypical antipsychotics Gabapentin Phenothiazines SSRIs Other Insulin Leflunomide Metformin Methamphetamine 3,4-methylenedioxymethamphetamine Rituximab SSKI Tocolytics (e.g. ritodrine, terbutaline) Miscellaneous Radiographic contrast media Food/drug additives Vitamins

Neoplasms

2–5%

Plasma cell dyscrasias – Monoclonal gammopathies – Multiple myeloma Myelodysplasia Myeloproliferative disorders Lymphoproliferative disorders Hairy cell leukemia

Solid organ carcinomas (IgA vasculitis in adults ≫ other forms of CSVV)

Genetic disorders

Rare

Alpha-1 antitrypsin deficiency

Immunodeficiency syndromes (see Table 60.1) Familial Mediterranean fever and other periodic fever syndromes (see Table 45.2)

†Peripheral blood eosinophilia may be present in up to 80% and 20% of patients with systemic and skin-limited diseases, respectively6. ‡May be associated with antineutrophil cytoplasmic antibodies (ANCAs). §Associated with eosinophilic granulomatosis with polyangiitis (Churg–Strauss syndrome). List of associated drugs adapted from Lotti T, et al. J Am Acad Dermatol. 1998;39: 667–87; ten Holder SM, et al. Ann Pharmacother. 2002;36:130–47; and Ortiz-Saniuan F, et al. J Rheumatol. 2014;41:2201–7.

Table 24.4 Underlying causes of secondary cutaneous vasculitis. (cont’d) ACE, angiotensin-converting enzyme; ATG, antithymocyte globulin; COX, cyclooxygenase; CSVV, cutaneous small vessel vasculitis; G-CSF, granulocyte colony-stimulating factor; NSAIDs, nonsteroidal anti-inflammatory drugs; SSKI, saturated solution of potassium iodide; SSRI, selective serotonin reuptake inhibitor; TNF, tumor necrosis factor.  

Clinical features

416

CSVV typically presents after exposure to an inciting agent with a single crop of lesions consisting of palpable purpura, erythematous papules, urticarial lesions, or hemorrhagic vesicles that range in size from 1 mm to several centimeters (see Figs 24.2 & 24.3). Lesions often begin as a purpuric macule or partially blanching urticarial papule. Occasionally, pustules, ulcerations, and targetoid lesions are seen. CSVV favors dependent areas, as well as areas affected by trauma (Koebner phenomenon) or under tight-fitting clothing. Even exercise, in particular walking or hiking in hot weather, can induce CSVV on the lower extremities. Although they are usually asymptomatic, the lesions can be associated with burning, pain, or pruritus. Residual postinflammatory hyperpigmentation may persist for months after the primary process resolves. Constitutional symptoms, such as fevers, weight loss and myalgias, may accompany flares of CSVV. Systemic symptoms develop in 5–25% of patients with CSVV, with arthralgias and arthritis occurring most commonly (15–65%), followed by genitourinary (3–7%) signs or symptoms, and gastrointestinal involvement (3–5%)10. A recent populationbased study demonstrated systemic involvement in 11 of 38 patients (29%) with CSVV3, which is a lower figure than was cited previously

because those individuals with a distinct clinical subtype of CSVV were excluded. In general, signs or symptoms of gastrointestinal, renal, or neurologic involvement should increase the clinical suspicion for a systemic vasculitis. In one study, the presence of paresthesias or fever and the absence of painful lesions were identified as risk factors for an associated systemic disease11. While the prognosis of patients with CSVV depends upon the severity of systemic involvement, approximately 90% of patients will have spontaneous resolution of cutaneous lesions within several weeks or a few months, while another 10% will have chronic or recurrent disease at intervals of months to years12. In the latter group, the average duration of disease activity was 24–28 months3,4. The presence of arthralgias or cryoglobulinemia and an absence of fever may portend chronicity11. An underlying cause for the CSVV, such as an autoimmune connective tissue disease or neoplasm, will also affect prognosis.

Differential diagnosis In addition to determining if the patient has a particular subtype of CSVV (see Table 24.1) or has CSVV as a manifestation of a systemic vasculitic syndrome, causes of secondary cutaneous vasculitis also need to be considered (see Table 24.4; Figs 24.5 & 24.6). Entities listed in

ETIOLOGIES OF CUTANEOUS SMALL VESSEL VASCULITIS

Treatment Infection (15–20%) Autoimmune connective tissue disease (15–20%) Drug (10–15%) Neoplasm (5%)

*

Idiopathic (45–55%)

Fig. 24.5 Etiologies of cutaneous small vessel vasculitis (CSVV). *CSVV was idiopathic in 76% of cases (of those not representing a distinct clinical subtype of CSVV) in a population-based study from Olmsted County, Minnesota3.  

The initial intervention in CSVV consists of supportive care and identifying possible triggers. The need for and choice of additional treatments depends on the severity of the cutaneous involvement, chronicity, and whether or not systemic involvement is present. Specific therapeutic options are outlined in Table 24.10. CSVV often resolves without any treatment other than avoidance of the inciting trigger. For mild skin-limited disease, supportive measures (e.g. leg elevation, avoiding tight clothing, rest, compression stockings) or symptomatic therapy (e.g. antihistamines, NSAIDs) may be all that is necessary. Chronic (>4 weeks’ duration) or more severe cutaneous disease may require more aggressive systemic therapy. Colchicine and dapsone may be used either alone or in combination. Oral colchicine (0.6 mg two to three times daily) is helpful for both skin and joint manifestations. However, gastrointestinal side effects are fairly common, even at low doses. Oral dapsone (50–200 mg/day) can lead to improvement of mild to moderate chronic lesions. Patients with severe, ulcerating, or progressive cutaneous disease who require rapid control of symptoms can be treated with a short course of high-dose oral corticosteroids (e.g. up to 1 mg/kg/day of prednisone). Because of the multiple adverse effects of long-term oral corticosteroids, a taper over 4 to 6 weeks should be attempted. If the patient develops recurrent CSVV as the dosage is decreased, addition of a steroid-sparing agent is warranted. Immunosuppressive agents such as azathioprine (2 mg/kg/day) and methotrexate (30 years, an underlying systemic disorder, persistent purpura >1 month, abdominal pain, hematuria, and absence of IgM on DIF36. Considerable controversy surrounds the use of corticosteroids and/or immunosuppressive medications for the treatment of severe renal disease and for preventing renal sequelae in individuals who have severe renal involvement. In one study, the use of prednisone was associated with a more rapid resolution of renal disease during the 4-week treatment period34. However, a Cochrane review of interventions for preventing and treating the renal disease of HSP found no difference in the risk of persistent kidney disease (at 6–12 months) in those children treated with prednisone (2–4 weeks) at the time of presentation as compared to placebo or supportive therapy37. This review also found no difference in the risk of persistent renal disease in patients with severe kidney disease who were treated with cyclophosphamide versus supportive care. In a recent randomized, double-blind, placebocontrolled trial involving over 300 children with HSP, early treatment with 14 days of prednisolone did not reduce the prevalence of proteinuria 12 months after disease onset38. Lastly, a meta-analysis that examined the use of systemic corticosteroids at the time of diagnosis versus supportive care found a decrease in the mean (but not the median) time to resolution of abdominal pain, while the odds of developing persistent renal disease were decreased39a. In sum, the current consensus appears to be that corticosteroids do not prevent renal disease but could be used to treat severe nephritis15.

CHAPTER

24 Cutaneous Vasculitis

In young boys, orchitis is a rare manifestation of systemic disease. The lung is also a rare site of involvement, presenting as hemoptysis and/or pulmonary infiltrates due to diffuse alveolar hemorrhage20. IgA small vessel vasculitis in adults, termed adult HSP by some authors, should be considered separately, as the clinical presentation and prognosis differ from that in children. For example, necrotic skin lesions are present in 60% of adults while cutaneous necrosis is observed in IgG†) against polyclonal IgG Polyclonal IgM† against polyclonal IgG

HCV ≫ HBV, HIV, autoimmune connective tissue diseases (e.g. rheumatoid arthritis), lymphoproliferative disorders (e.g. B-cell non-Hodgkin lymphoma, CLL)

Vasculitis

Palpable purpura, arthralgias, peripheral neuropathy, glomerulonephritis

III**

*Rarely IgA. Referred to as “mixed” cryoglobulins because either monoclonal or polyclonal immunoglobulins bind to polyclonal immunoglobulins. ** † Typically have rheumatoid factor activity (i.e. are directed against the Fc portion of IgG).

Table 24.6 Classification of cryoglobulins. See Chapter 23 for discussion of type I cryoglobulinemia. CLL, chronic lymphocytic leukemia; HBV, hepatitis B virus; HCV, hepatitis C virus; HIV, human immunodeficiency virus.  

Introduction Cryoglobulins are cold-precipitable immunoglobulins that can be divided into three subtypes, all of which have cutaneous manifestations (Table 24.6). Type I cryoglobulinemia, composed primarily of monoclonal IgM (and less frequently IgG > IgA), results in microvascular occlusion without vasculitis (see Ch. 23). In contrast, vasculitis is seen with types II and III cryoglobulins, also referred to as “mixed cryoglobulins” because they are composed of monoclonal and polyclonal components. Approximately 15% of patients with circulating mixed cryoglobulins present with symptoms due to cryoglobulinemic vasculitis12. Cryoglobulinemic vasculitis typically affects the skin, peripheral nervous system, and kidneys.

Epidemiology The frequency of mixed cryoglobulinemia varies according to geographic location, e.g. there is a higher prevalence in Southern Europe than in Northern Europe or North America60. In northwest Spain, the annual incidence was determined to be 4.8 cases per million. Geographic variations in the frequency of mixed cryoglobulinemia likely reflect differences in the prevalence of HCV infection. While 40–60% of patients with HCV infection have cryoglobulinemia, overt cryoglobulinemic vasculitis develops in approximately 5–30% of these individuals60a.

Pathogenesis 424

Mixed cryoglobulinemia occurs in the setting of specific infections, autoimmune connective tissue diseases, and hematologic malignancies61 (see Table 24.6). When the association between HCV infection and mixed cryoglobulinemia was discovered in 1989, a cause for

70–90% of “essential” cryoglobulinemia became apparent. Only 5% of cases are associated with HBV infection, and occasionally, EBV, cytomegalovirus, Leishmania, and Treponema spp. have been implicated. In a minority of patients, mixed cryoglobulinemia has been associated with autoimmune connective tissue diseases, in particular rheumatoid arthritis, followed by Sjögren syndrome and systemic sclerosis. Approximately 5% of the patients with mixed cryoglobulinemia have a lymphoproliferative disorder (e.g. B-cell non-Hodgkin lymphoma, chronic lymphocytic leukemia, macroglobulinemia). It is poorly understood why mixed cryoglobulins are produced in these clinical settings. In the case of HCV and HBV infections, their production is thought to be related, at least in some patients, to the associated liver disease, e.g. patients with end-stage liver disease are at higher risk of developing mixed cryoglobulins. A significant percentage of lymphocytes in HCV-infected individuals possess a t(14;18) translocation that results in a rearrangement of bcl-2, whose protein product has an anti-apoptotic function; this can lead to B-lymphocyte proliferation and may contribute to production of cryoglobulins. In HCV-infected patients who do not possess this bcl-2 rearrangement, B-cell activation and subsequent cryoglobulin and autoantibody production is believed to result from chronic immune stimulation (e.g. by the virus)60. Cryoglobulinemic vasculitis occurs when immune complexes form from circulating cryoglobulins and then deposit within the walls of small blood vessels. As with other forms of cutaneous vasculitis, this immune complex deposition is believed to initiate complement activation and vascular inflammation. The presence of hepatitis C virion (in association with IgM and IgG antibodies) within vessel walls raises the possibility that viral particles are a component of the cryoprecipitate61.

Pathology

Cutaneous involvement occurs in up to 90% of patients with cryoglobulinemic vasculitis, most commonly manifesting as palpable purpura of the lower extremities (Fig. 24.13). Other cutaneous findings include erythematous papules, ecchymoses, and dermal nodules; rarely, urticaria, livedo reticularis, necrosis, ulcerations, and bullae are observed. The disease usually has a chronic course12, but newer, more effective anti-hepatitis C viral therapies may have an impact (see below). Skin lesions are not typically cold-induced, in contrast to the vascular occlusive lesions seen in type I cryoglobulinemia. Common extracutaneous findings include arthritis or arthralgias (70%), peripheral (typically sensory) neuropathy (40%), gastrointestinal disease or hepatitis (30%), and membranoproliferative glomerulonephritis (25%)12. The hepatitis may reflect the underlying viral infection or an associated autoimmune hepatitis, or it may be a direct result of the cryoglobulinemia. Occasionally, patients have xerostomia or xerophthalmia and endocrinologic disorders (e.g. thyroid, gonadal). The most commonly associated infections, autoimmune connective tissue diseases, and hematologic disorders are listed in the Pathogenesis section. B-cell non-Hodgkin lymphoma is the most common associated malignancy. Rarely, solid tumors such as hepatocellular carcinoma and papillary thyroid carcinoma have been reported to have a relationship to cryoglobulinemic vasculitis. With regard to the laboratory evaluation, tests for cryoglobulins can be falsely negative and need to be assayed during clinical flares on more than one occasion. In addition, the blood sample should be kept at 37°C while being transported to the laboratory. Approximately 70% of patients have circulating rheumatoid factor activity, while 20% have antinuclear antibodies. Up to 15% of patients with mixed cryoglobulinemia have a monoclonal gammopathy as detected by serum protein electrophoresis and/or immunofixation electrophoresis12. HBV, HCV, and HIV serologies should be evaluated, followed by a determination of viral load if there is evidence of infection (see Table 128.8). Patients typically have low serum complement levels, often with low or undetectable C4 levels; however, complement levels do not necessarily correlate with the severity of the disease60.

Histopathologically, features of LCV are seen. By DIF, granular deposits consisting predominantly of IgM and C3 in a vascular pattern are observed in the papillary dermis4.

Differential diagnosis The differential diagnosis of cryoglobulinemic vasculitis includes all forms of small vessel vasculitis (see Table 24.1). Cryoglobulinemic vasculitis can be differentiated from these disorders by the detection of circulating mixed cryoglobulins. Patients with Sjögren syndrome can also have arthralgias, arthritis, xerostomia/xerophthalmia, and the presence of rheumatoid factor and/or mixed cryoglobulins; however, they are typically SSA (Ro)/SSB (La)-positive, have distinct histopathologic findings in salivary gland biopsies, and less frequently are found to have hepatitis, glomerulonephritis, or hypocomplementemia60.

CHAPTER

24 Cutaneous Vasculitis

Clinical features

Treatment The treatment of mixed cryoglobulinemia should first be directed toward any underlying disease. All patients with HCV-associated mixed cryoglobulinemia should be treated with antivirals (see Table 24.10). A regimen of interferon-α plus ribavirin has been reported to lead to resolution of the cutaneous (100% of patients), renal (50%), and neurologic (25–75%) manifestations61. Interferon-α alone may improve the cutaneous vasculitis (50–100% of patients), but is less effective in reversing the neurologic or renal involvement. In rare cases, interferon may trigger or worsen the peripheral neuropathy. While the role of newer antiviral regimens such as sofosbuvir/velpatasvir plus ribavirin or sofosbuvir/ledipasvir remains to be determined, recent data suggest such regimens are effective and well-tolerated60a. Plasma exchange, in combination with cytotoxic agents such as cyclophosphamide, is often used for severe neurologic or renal involvement60. Corticosteroids in conjunction with cytotoxic agents may be necessary to control organ-threatening disease. Rituximab has been shown to benefit patients with refractory HCV-associated cryoglobulinemic vasculitis as well as those with recalcitrant HCV-negative mixed cryoglobulinemia, and to date it has not been reported to worsen the underlying HCV infection62,63. Sequential therapy, i.e. rituximab followed by antiviral medications, has also been proposed for the treatment of cryoglobulinemic vasculitis60. Predictors of early relapse in non-infectious mixed cryoglobulinemic vasculitis include purpura, cutaneous necrosis, and articular involvement64.

PREDOMINANTLY SMALL AND MEDIUM-SIZED VESSEL VASCULITIDES ANCA-Associated Vasculitides Introduction

A

B

Fig. 24.13 Cryoglobulinemic vasculitis. A Palpable purpura of the lower extremities. B Purpuric papules and plaques with central necrosis and ulceration as well as a few vesicles in a patient with type II cryoglobulinemia in the setting of hepatitis C viral infection. The patient also had an elevated rheumatoid factor, decreased C4, and an IgM monoclonal gammopathy.  

The ANCA-associated vasculitides (AAVs) are characterized by involvement of small to medium-sized vessels, the presence of ANCAs, and an overlapping spectrum of organ involvement, but with each having distinguishing clinical and laboratory features. The three AAVs discussed here are microscopic polyangiitis (MPA), granulomatosis with polyangiitis (GPA), and eosinophilic granulomatosis with polyangiitis (EGPA) (Table 24.7). ANCAs are predominantly IgG autoantibodies directed against components of both primary granules of neutrophils and monocyte lysosomes, and they likely have an important role in the pathogenesis of AAVs65. By immunofluorescent staining, there are two vasculitisrelevant patterns: (1) cytoplasmic (c)-ANCAs – directed against the antigen proteinase 3 (PR3); and (2) perinuclear (p)-ANCAs – directed against the antigen myeloperoxidase (MPO), with other antigens (e.g. lactoferrin, cathepsin G, elastase) serving as targets in the setting of nonspecific inflammation. ANCAs are useful diagnostically and for monitoring disease activity66. However, these autoantibodies are also found in patients receiving certain medications and who have underlying chronic infections, rheumatologic or inflammatory disorders, and malignancies (see Table 40.6)66. In order to improve specificity with regard to AAVs, the indirect immunofluorescence (IIF) test should be used as a screening evaluation (detects perinuclear versus cytoplasmic staining), followed by an ELISA

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4

ANTINEUTROPHIL CYTOPLASMIC ANTIBODY (ANCA)-ASSOCIATED VASCULITIDES

Disorder [No. of diagnostic criteria required]

Cutaneous and oral findings

Extracutaneous manifestations

Histologic findings¶

Renal: glomerulonephritis Pulmonary: capillaritis/hemorrhage, no asthma • Neurologic: mononeuritis multiplex • Less often upper respiratory tract, cardiac, GI, and ocular involvement



Upper respiratory: - signs of inflammation, e.g. nasal ulcers, saddle nose, acute hearing loss, or chronic sinusitis/otitis/mastoiditis† - subglottic stenosis • Pulmonary: nodules/fixed infiltrates/cavities† • Renal: glomerulonephritis • Ocular: proptosis, scleritis • Less often neurologic, GI, and cardiac involvement



Microscopic polyangiitis (MPA) [4]



Palpable purpura Erythematous macules, urticarial or purpuric plaques • Livedo racemosa, ulcers, splinter hemorrhages







Granulomatosis with polyangiitis (GPA; formerly Wegener granulomatosis) [3; anti-PR3/cANCA]



Palpable purpura Friable, micropapular gingivae (‘strawberry gums’), oral ulcers • PNGD * • Subcutaneous nodules • Pyoderma gangrenosum-like ulcers



Eosinophilic granulomatosis with polyangiitis (EGPA; formerly Churg–Strauss syndrome‡) [4]



Palpable purpura PNGD* • Subcutaneous nodules • Urticarial plaques • Livedo racemosa, retiform purpura, ulcers







Upper respiratory: paranasal sinusitis†, allergic rhinitis§, nasal polyps§ • Pulmonary: - asthma§ - non-fixed infiltrate† • Hematologic: peripheral eosinophilia (>10%), elevated IgE • Neurologic: mono- or polyneuropathy • Cardiac: myo- or pericarditis • Less often renal, GI, and ocular involvement

Vasculitis of small (± medium-sized) vessels • No granulomas

Granulomatous inflammation • Vasculitis of small ± medium-sized vessels

Extravascular eosinophils Granulomatous inflammation • Vasculitis of small ± medium-sized vessels • •

¶May be observed in biopsies of the skin, mucosa, respiratory tract, kidney, or nerve.

*† Palisaded neutrophilic and granulomatous dermatitis, which typically presents with umbilicated, crusted papulonodules on extensor surfaces (e.g. elbows) or the face (especially in GPA). Evidence via computed tomography (CT) represents a diagnostic criterion.

‡Occasionally triggered by leukotriene inhibitors and/or rapid discontinuation of corticosteroid therapy. §Usually the initial manifestations.

Table 24.7 Antineutrophil cytoplasmic antibody (ANCA)-associated vasculitides (AAVs). See Fig. 24.14 for frequencies of specific ANCAs in each of these disorders. As in other forms of vasculitis, patients often have constitutional symptoms (e.g. fevers, malaise, weight loss), arthralgias, and arthritis. Diagnostic criteria for each disorder are in italics; those for GPA represent the European criteria (see text) while the ACR clinical criteria include oral ulcers or purulent or bloody nasal discharge. Alternative criteria that do not specify a lack of granulomatous inflammation have also been proposed for microscopic polyangiitis. GI, gastrointestinal; PR3, proteinase 3. Courtesy, Julie V Schaffer, MD.  

that specifically detects anti-PR3 and anti-MPO antibodies. However, up to 5% of serum samples are positive by ELISA only, so when there is a high index of suspicion for an AAV, an ELISA should be performed even if the IIF screening test is negative. Because neither anti-PR3 ANCA nor anti-MPO ANCA is specific for a particular AAV, clinicopathologic correlation is required when evaluating a patient with suspected cutaneous vasculitis and positive ANCAs (Fig. 24.14). Semi-quantitative analysis may allow for disease monitoring and response to treatment. Of note, the presence of ANCAs within the first year following remission has been associated with disease relapse.

for relapse, the presence of ANCAs, and an older age group are risk factors for a reduction in the survival rate. The three major AAVs are discussed in the following sections, including clinicopathologic features (see Table 24.7)69 as well as treatment options (see Table 24.10)70.

Microscopic Polyangiitis Synonyms:  ■ Microscopic polyarteritis ■ Microscopic polyarteritis nodosa

Epidemiology In a population-based study of biopsy-proven cutaneous LCV, the annual incidence of an underlying AAV was 4 cases per million3, i.e. ~10% of the patients had an AAV, emphasizing the importance of considering this group of disorders in patients with LCV.

Pathogenesis The pathogenesis is depicted in Fig. 24.1B. In addition, neutrophil extracellular traps, composed of chromatin fibers containing the targeted autoantigens PR3 and MPO, may stimulate local production of type I interferons. Promotion of an autoimmune response against neutrophil components could then result67.

426

Key features ■ Vasculitis of capillaries, venules, and medium-sized arteries ■ Palpable purpura, erythematous macules and patches, splinter hemorrhages, and ulcers ■ Constitutional symptoms, crescentic necrotizing glomerulonephritis, and alveolar hemorrhage ■ Presence of p-ANCAs ■ Absence of granuloma formation

Natural history, clinical features, and treatment

Introduction

The morbidity and mortality of AAVs are relatively high, stemming from both systemic manifestations and complications of immunosuppressive therapy68. Delay in diagnosis, renal impairment, propensity

Microscopic polyangiitis (MPA) is a systemic vasculitis that involves small and medium-sized arteries, with cutaneous, pulmonary, and renal involvement most commonly observed. Although MPA is often

MPA

Epidemiology

*

GPA

The estimated incidence of MPA is 3 to 24 cases per million. Men are more commonly affected than women and the reported mean age of onset is 57 years, with a peak incidence between the ages of 65 and 75 years. More severe renal vasculitis favors older patients72.

PR3-ANCA MPO-ANCA Range

EGPA

CHAPTER

24 Cutaneous Vasculitis

RANGE OF FREQUENCIES OF ANCA IN ANCA-ASSOCIATED VASCULITIDES

recognized as a distinct clinical entity, it can have varying presentations such that some, but not all, of the characteristic clinical and laboratory findings are present in an individual patient. For example, patients may be diagnosed as having polyarteritis nodosa (PAN) if there is no evidence of small vessel vasculitis (e.g. glomerulonephritis) or ANCAs. In an attempt to allow distinction from PAN and GPA, clinical criteria for MPA have been proposed and are undergoing validation71.

Pathogenesis

Druginduced

** 0

20

40

60

80

100

Frequency (%)

Fig. 24.14 Range of frequencies of ANCA in ANCA-associated vasculitides. Variability reflects differences in cohorts studied, disease extent and severity at time of assays, diagnostic criteria, and cutoff values of various ANCA assays. Negative ANCA testing does not exclude the presence of an ANCA-associated vasculitis, as overall frequencies for ANCA positivity are 90% (generalized GPA), 60% (limited GPA), 90% (MPA), and 50% (EGPA), respectively66a. *MPO-ANCAs are overrepresented in Chinese patients with GPA; 10% of non-Chinese patients with GPA have MPO-ANCAs66. **Examples include propylthiouracil, minocycline, hydralazine, and levamisole-tainted cocaine (see Tables 24.4 and 40.6). Note that other ANCA specificities may be detected in drug-induced vasculitis. ANCA, antineutrophil cytoplasmic antibody; EGPA, eosinophilic granulomatosis with polyangiitis; GPA, granulomatosis with polyangiitis; MPA, microscopic polyangiitis; MPO, myeloperoxidase; PR3, proteinase 3. Adapted from  

Wiik AS, Rheum Dis Clin NA. 2010;36:479–89.

The etiology of MPA is unknown. Unlike PAN, MPA is not associated with HBV infection; however, it may be associated with infectious endocarditis72. Medications or malignancy may also play a role in triggering the disease73. ANCAs are thought to play a role in the pathogenesis of MPA (see general Pathogenesis).

Clinical features Most patients with MPA initially experience constitutional symptoms, such as fever, weight loss, arthralgias and myalgias, for months to years before other symptoms occur. Depending upon the series, 20–70% of patients will have cutaneous involvement, most commonly palpable purpura (Fig. 24.15). In one study, additional skin findings, in decreasing order of frequency, were erythematous patches (50% of patients), livedo racemosa (17%), and splinter hemorrhages, urticarial plaques, and ulcers (each 6%)74. These skin lesions developed after the renal and/or pulmonary involvement in three-quarters of patients. In another series, acral erythematous macules were described as the most common cutaneous finding73. Skin manifestations are associated with an increased incidence of arthralgias, ocular disease, and mononeuritis multiplex75.

Fig. 24.15 Microscopic polyangiitis. A Petechiae and purpuric macules on the lower extremity; some of the lesions have central hemorrhagic crusts. Histologically, leukocytoclastic vasculitis was seen.   B Petechiae and multiple purpuric macules with central necrosis on the plantar surface. B, Courtesy, Cara Whitney Hannon,  

MD, and Robert Swerlick, MD.

B

A

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Urticarias, Erythemas and Purpuras

4

Renal involvement occurs in nearly all patients with MPA (>90%), and a pauci-immune, crescentic, necrotizing glomerulonephritis is the primary pathology in MPA (almost identical to that observed in GPA). Pulmonary capillaritis (with dyspnea and pulmonary infiltrates) occurs in 30–50% of patients, and it can result in diffuse alveolar hemorrhage (10%). Neurologic involvement is also common, usually presenting as a peripheral neuropathy or mononeuritis multiplex in up to a third of patients. However, upper respiratory tract involvement that resembles GPA develops at a much lower frequency than in the other ANCAassociated vasculitides. The progressive clinical course of MPA typically leads to renal failure and/or pulmonary hemorrhage. Anti-MPO antibodies are detected more often than are anti-PR3 antibodies (see Fig. 24.14). Rare patients without renal involvement are typically ANCA-negative68. Additional diagnostic testing for systemic involvement is outlined in Table 24.8 and Fig. 24.16.

Pathology The characteristic histologic findings in microscopic polyangiitis include a segmental necrotizing vasculitis of the smallest blood vessels (capillaries, venules and arterioles) and, less often, a vasculitis of small and/or medium-sized arteries. There is no evidence of granulomatous inflammation.

Differential diagnosis MPA frequently presents with palpable purpura and constitutional symptoms. If no additional internal organ involvement is evident at initial presentation, it may be difficult to distinguish MPA from CSVV. The differential diagnosis includes the entities listed in Table 24.9.

Treatment Treatment of MPA is divided into two phases: induction of remission and maintenance therapy. To induce remission, corticosteroids (e.g. 1 mg/kg/day of prednisone) are initially utilized, with addition of cyclophosphamide for patients with significant organ involvement (e.g. renal, pulmonary, neurologic) (see Table 24.10)76. Cyclophosphamide may be given for 6 months, either orally (2 mg/kg/day) or as intravenous pulses (0.5–1 g/m2/month); equally efficacious, pulse therapy reduces the total drug dose and incidence of side effects such as bladder carcinoma and infections77. Recent data suggest that corticosteroids plus rituximab is equally effective as corticosteroids plus cyclophosphamide77–81. Methotrexate, azathioprine, mycophenolate mofetil, and IVIg may be useful as corticosteroid-sparing agents, particularly in maintenance of remission82. Plasma exchange has also proved beneficial in ANCA-positive patients. Patients with MPA have a higher rate of relapse compared to patients with classic PAN (regardless of disease severity)76, but a lower rate than those with GPA. Persistence of ANCAs despite induction of a remission is associated with an increased risk of relapse.

Granulomatosis With Polyangiitis Synonym:  ■ Wegener granulomatosis (historical)

Key features ■ Necrotizing granulomatous inflammation of the upper and lower respiratory tracts ■ Pauci-immune glomerulonephritis ■ Systemic vasculitis that can involve the skin and oral mucosa

Introduction Granulomatosis with polyangiitis (GPA) is classically described as the triad of granulomatous inflammation of the upper and lower respiratory tracts, systemic necrotizing small vessel vasculitis, and pauci-immune glomerulonephritis. Patients with GPA exist along a spectrum of severity, depending upon the number of organs involved and the degree of functional impairment. Those with generalized systemic disease have a high mortality rate if left untreated, while patients with the limited form of GPA have primarily airway disease without constitutional symptoms or systemic vasculitis. The initial evaluation of patients with GPA should establish the extent of organ involvement, as evidence supports distinct treatment approaches for limited versus generalized forms of the disease65,68.

Epidemiology The incidence of GPA is estimated to be 5 to 12 cases per million, with a slight female predominance. The disease occurs most often in Caucasians, with a peak age of onset of 45–65 years. GPA is one of the more common systemic vasculitides of children, with an incidence of 0.03 to 3.2 per 100 000 children per year83.

Pathogenesis The pathophysiology of GPA is reflected in two clinicopathologic hallmarks of the disease – granuloma formation and small to medium-sized vessel vasculitis. Activity of alpha-1 antitrypsin, a proteinase inhibitor, has been found to be markedly reduced in patients with GPA84, while ANCAs, environmental factors, and genetic polymorphisms (e.g. PTPN22 620W allele) all contribute to immune dysregulation. Although the specific pathogenic roles of PR3 or anti-PR3 antibodies remain unclear, surface expression of PR3 on apoptotic and/or activated

POSSIBLE ADDITIONAL DIAGNOSTIC TESTING FOR PATIENTS WITH SUSPECTED ANCA-ASSOCIATED VASCULITIDES

Chest X-ray and/or chest CT scan

Electromyogram/ nerve conduction studies

Lung, nerve or kidney biopsy

Microscopic polyangiitis







Granulomatosis with polyangiitis





√*

Eosinophilic granulomatosis with polyangiitis







Upper respiratory tract or muscle biopsy

ECG, echocardiogram

CT scan of sinuses

√*









Serum IgE level

Consider GI and ophthalmologic examination

√ √



*Depends upon signs and symptoms. 428

Table 24.8 Possible additional diagnostic testing for patients with suspected ANCA-associated vasculitides. This is in addition to the general evaluation outlined in Fig. 24.16. ANCA, antineutrophil cytoplasmic antibody; CT, computed tomography; ECG, electrocardiogram; GI, gastrointestinal.  

Patient with suspected cutaneous vasculitis History and physical examination • Determine if drug exposure or evidence of an underlying infection; if not, consider an associated inflammatory disorder or malignancy (see Table 24.4) • Evaluate for extracutaneous signs and symptoms • Constitutional: fever, weight loss, fatigue • Musculoskeletal: arthralgias, myalgias • Renal: hematuria • Gastroenterologic: abdominal pain, bloody stools

• Neurologic: numbness, paresthesias, weakness • Cardiopulmonary: shortness of breath, chest pain, cough, hemoptysis • Ear/Nose/Throat: sinusitis

Biopsy of fresh but well-developed skin lesion(s), 24–48 hours old, to confirm the presence of vasculitis and determine the size of vessels involved: • If suspect small vessel vasculitis (e.g. if palpable purpura): punch biopsies for routine histology and direct immunofluorescence (the latter of a lesion 24 hours old) • If suspect medium-sized vessel vasculitis: deep incisional biopsy (including subcutaneous tissue) of a nodule (preferred) or retiform purpura > the edge of an ulcer* Pertinent positives on skin biopsy H&E • Granulomatous vasculitis: systemic vasculitis or systemic illness • Lymphocytic vasculitis: AI-CTD, viral infection, drug • Small- and medium-vessel involvement: ANCAs or AI-CTD • Urticarial vasculitis with dermal interstitial neutrophilic infiltrate: hypocomplementemic urticarial vasculitis (consider SLE) • HSP without eosinophils in patients 40 years old: renal involvement

Fig. 24.16 Approach to the patient with suspected cutaneous vasculitis. AI-CTD, autoimmune connective tissue disease; ANA, antinuclear antibody; ANCAs, antineutrophil cytoplasmic antibodies; BMZ, basement membrane zone; BUN, blood urea nitrogen; CBC, complete blood count; DIF, direct immunofluorescence; ELISA, enzyme-linked immunosorbent assay; ENA, extractable nuclear antigen; ESR, erythrocyte sedimentation rate; H&E, hematoxylin and eosin; HIV, human immunodeficiency virus; HSP, Henoch–Schönlein purpura; Ig, immunoglobulin; SLE, systemic lupus erythematosus. Adapted from  

CHAPTER

24 Cutaneous Vasculitis

APPROACH TO THE PATIENT WITH SUSPECTED CUTANEOUS VASCULITIS

Goeser MR, et al. Am J Clin Dermatol. 2014;15:299-306.

DIF • IgA predominant: HSP • Prominent IgM: cryoglobulin or rheumatoid vasculitis • Positive around vessels and BMZ: hypocomplementemic urticarial vasculitis (consider SLE) • Negative: pauci-immune vasculitis (i.e. ANCA-associated)

Initial basic laboratory evaluation for all patients (repeated with flares of disease activity) to assess for extracutaneous involvement: • CBC with differential, platelet count, ESR +/- C-reactive protein • Hepatic panel, BUN & creatinine, urinalysis, stool guaiac Additional evaluation for associated diseases and specific vasculitides, depending on clinical suspicion (i.e. chronic or recurrent disease, unclear cause, history and physical examination suggest underlying internal organ involvement or associated systemic disorder): Infection • Antistreptolysin O and anti-DNase B titers; hepatitis B/C and HIV serologies; throat, urine or blood culture as indicated Inflammatory • Cryoglobulins

**

• ANCAs AI-CTD • Rheumatoid factor, ANA, anti-ENA antibodies (e.g. anti-Ro) • CH50/C3/C4 if suspect urticarial vasculitis (also C1q if low C4) serum immunofixation electrophoresis, peripheral blood smear Malignancy • Serum & urine protein electrophoresis, • Age-appropriate screening +/- sign/symptom-directed evaluation for malignancies

Additional evaluation for extracutaneous involvement in systemic vasculitides: ANCA-associated vasculitis • Chest X-ray, CT of chest & sinuses • Depending on the specific condition (see Table 24.8) and clinical findings, consider: electromyogram/nerve conduction studies, echocardiogram/electrocardiogram, and biopsy of the respiratory tract (upper or lower), nerve, kidney or muscle Classic (systemic) polyarteritis nodosa • Mesenteric/renal/celiac angiogram • Consider biopsy of muscle, nerve, kidney or testicles Include peripheral rim of inflammation if present; vasculitis underlying an ulcer can occur as a secondary phenomenon and is not *diagnostic. Indirect immunofluorescence (IIF) followed by confirmation with antigen-specific ELISAs for proteinase-3 (PR3) and **myeloperoxidase (MPO).

neutrophils may stimulate dendritic cell maturation and proinflammatory cytokine release by antigen-presenting cells, thereby favoring development of Th1-mediated granuloma formation (termed “neutrophil priming”). Expression of PR3 on the cell surface of neutrophils may impede phagocytosis by macrophages, thus prolonging the opportunity for autoantibody development. In turn, ANCAs binding to PR3 on neutrophils result in vessel damage (e.g. pauci-immune or nonimmune complex-mediated vasculitis; see Fig. 24.1B)66,85. Neutrophil priming may occur as a result of certain infections, such as Staphylococcus aureus. Of note, nasal carriage of S. aureus is associated with relapse of GPA, and treatment of nasal carriage with antibiotics improves outcome.

Clinical features Several groups have defined clinical criteria for GPA, having reached some consensus83. Existing European criteria (3 of 6 required) consist of: upper respiratory tract inflammation; typical radiologic features on chest radiograph or chest CT scan; abnormal urinalysis (also common in MPA); biopsy-proven granulomatous inflammation; airway stenosis (especially in children); and serologic findings (e.g. anti-PR3 ANCAs). Mucocutaneous involvement occurs in ~40% of patients, and it can be the presenting sign in 10%12. The most common lesions are palpable purpura86, followed by oral ulcers (Fig. 24.17). The gingival tissue is often red, friable, and hyperplastic (“strawberry gums”). Painful subcutaneous nodules and ulcers that resemble pyoderma gangrenosum can

429

SECTION

Urticarias, Erythemas and Purpuras

4

KEY DISORDERS IN THE DIFFERENTIAL DIAGNOSIS OF ANCA-ASSOCIATED VASCULITIDES AND THEIR DISTINGUISHING FEATURES

ANCA-positive vasculitic syndrome Microscopic polyangiitis

Distinguishing features of the disorder in the differential diagnosis

Disorder in differential diagnosis Eosinophilic granulomatosis with polyangiitis (Churg–Strauss syndrome)



Eosinophilia Asthma and sinus disease • Increased incidence of cardiac involvement

Granulomatosis with polyangiitis (Wegener granulomatosis)



Polyarteritis nodosa





Granulomatous inflammation Increased incidence of ocular and severe upper respiratory tract involvement



Absence of glomerulonephritis Lower incidence of pulmonary involvement • Vasculitis of renal arteries rather than small vessel vasculitis • Renovascular hypertension • ANCA-negative •

Goodpasture syndrome



Kidney-bound or circulating anti-glomerular basement membrane antibodies

SLE or rheumatoid vasculitis



Distinct rheumatologic serologies In SLE, develops in individuals with longstanding disease



Granulomatosis with polyangiitis (Wegener granulomatosis)

Eosinophilic granulomatosis with polyangiitis (Churg–Strauss syndrome)



Eosinophilia Asthma • Lower incidence of severe renal disease

Microscopic polyangiitis



NK/T-cell lymphoma





Absence of granulomatous inflammation Destructive nasal midline lesion (see Table 45.3) Characteristic histology



Tuberculosis (lupus vulgaris), leprosy

Destructive nasal midline lesion Characteristic histologic features and laboratory findings

• •

Eosinophilic granulomatosis with polyangiitis (Churg–Strauss syndrome)

Cocaine-induced destructive nasal midline lesion



By ELISA, ANCAs are positive for both human neutrophil elastase and proteinase 3 • Neutropenia

Goodpasture syndrome, SLE, rheumatoid arthritis



Microscopic polyangiitis



See above

No granulomatous inflammation No history of asthma • No hypereosinophilia •

Granulomatosis with polyangiitis (Wegener granulomatosis)



Increased incidence of glomerulonephritis Lower incidence of cardiac or peripheral nerve involvement

Hypereosinophilia, secondary



Hypereosinophilic syndrome





Due to medications, parasitic infections, allergic disease, malignancy Pruritus, eczematous or urticarial eruptions, oral ulcerations, and angioedema

Table 24.9 Key disorders in the differential diagnosis of ANCA-associated vasculitides and their distinguishing features. ANCAs, antineutrophil cytoplasmic antibodies; ELISA, enzyme-linked immunosorbent assay; SLE, systemic lupus erythematosus.  

430

also be seen. Papulonecrotic lesions are common and usually occur on the extremities (particularly the elbows), but can also affect the face and scalp. In children with localized GPA, edema and infiltration of the upper eyelids can be present, resembling orbital IgG4-related disease87 (see Table 25.2). Acneiform and folliculitis-like papules may also occur in children with GPA87a. The upper or lower respiratory tracts are involved in up to 90% of patients with GPA. Nasal, sinus, tracheal, and ear involvement represent the presenting complaints in >70% of patients. Suggestive symptoms and signs include recurrent epistaxis, mucosal ulcerations, nasal septal perforation, and saddle nose deformity. Patients with pulmonary involvement typically present with dyspnea, cough, hemoptysis, or pleuritis, and chest X-rays demonstrate irregular infiltrates or nodules. Renal disease is present in only 20% of patients at presentation, but approximately 75% of patients eventually develop glomerulonephritis88. Other organ systems commonly affected by necrotizing vasculitis in GPA include musculoskeletal (70%), ocular (30–60%), neurologic (20–50%), gastrointestinal (5–10%), and cardiac (5–40%). Laboratory findings are consistent with an inflammatory process, including elevated acute phase reactants (ESR, C-reactive protein), anemia, and leukocytosis. Up to 50% of patients have a positive

rheumatoid factor. The frequencies of ANCA are depicted in Figure 24.14 and differ depending upon extent of disease. Patients with renal involvement have active urine sediments with proteinuria, hematuria, and red blood cell casts as well as progressive renal failure. Serum biomarkers that may distinguish active disease (GPA or MPA) from that in remission include matrix metalloproteinase-3 (MMP-3), tissue inhibitor of metalloproteinase-1 (TIMP-1), and CXCL1389. Additional diagnostic testing for systemic involvement is outlined in Table 24.8.

Pathology Although the majority of skin biopsy specimens show nonspecific histopathologic changes (e.g. perivascular lymphocytic infiltrates), up to 50% demonstrate LCV and/or granulomatous inflammation. Biopsies of papulonecrotic lesions show a palisading neutrophilic dermatitis with areas of granulomatous inflammation that surround foci of basophilic necrobiosis (see Ch. 93).

Differential diagnosis The primary differential diagnosis for GPA includes the other AAVs, in particular EGPA, as both diseases are characterized by necrotizing,

CHAPTER

Disorder

First-line treatment

Cutaneous small vessel vasculitis

Discontinue incriminated drugs Supportive care Treat underlying infections, neoplasms NSAIDs Antihistamines

Henoch–Schönlein purpura (including IgA vasculitis in adults)

Evidence levels

3 3

Supportive care

Acute hemorrhagic edema of infancy

Supportive care

3e28

Urticarial vasculitis

Antihistamines Indomethacin Dapsone (100–200 mg/day) ± pentoxifylline CS

3e29 3e29 245,45a,e30

Erythema elevatum diutinum

NSAIDs Intralesional CS Dapsone

Cryoglobulinemic vasculitis (+ HCV)

Peginterferon–ribavirin ± telaprevir or boceprevir; sofosbuvir/ledipasvir* CS

Second-line treatment

Evidence levels

Third-line treatment

Evidence levels

Colchicine (0.6 mg BID–TID) Dapsone (50–200 mg/ day) CS

2e1

AZA (2 mg/kg/day) MYC MTX IVIg CSA CYC Rituximab PEX

3e4 3e5 3e6 312 312 312 3e7 312

Dapsone Colchicine CS AZA ± CS CYC ± CS CSA ± CS Antihistamines

2e8 3 134,38, 239a 2e10–e12 2e10,e13,e14 3e13,e15,e16

IVIg Rituximab MYC CS + tacrolimus ACA PEX Factor XIII

3e17 3e18 3e13,e19,e20 1e21, 2e22 3e13 2e23 2e24, 3e25,e26 2e27

CS

3e28

MYC IVIg Rituximab CSA PEX Canakinumab Tocilizumab CYC

245a,e34 349,50 245a,48,e35 345 345,e36 1e37 3e37a 245a

3e2 2e3 312

Colchicine (0.6 mg BID–TID) Hydroxychloroquine (200–400 mg/day) AZA MTX

245a,e31

3 3 3

Colchicine Chloroquine Tetracyclines

3 3 3

Niacinamide PEX

3 3

160,62,e38, 260a

CS + CYC

360,e38

IVIg Rituximab (± ribavirin, IFN) PEX

3e39 263,e40,e41

245a,e29

245a,e32 245,45a,e29 245a,e33

360,e38

Cutaneous Vasculitis

24

THERAPEUTIC LADDER FOR PATIENTS WITH VASCULITIS

360,e38

Cutaneous polyarteritis nodosa

Treat underlying infections Discontinue incriminated drugs NSAIDs CS (topical, intralesional or oral)

3 2

MTX (7.5–15 mg/wk) Dapsone/sulfapyridine IVIg HCQ

3 3 3e42 3109

Pentoxifylline Colchicine AZA or MYC TNF-α inhibitors Warfarin

3 3 3 3 3e43

Classic polyarteritis nodosa (+ HBV)

CS CS + PEX + IFN/lamivudine**

276 2106,113b,e44,e45

CS + CYC

276,e45

IVIg

3

Microscopic polyangiitis

CS CS + Rituximab ± CYC

376 178,79

CS + CYC MTX

376,e46 3e46

AZA MYC IVIg Rituximab Infliximab

282,e47 3e47 3e47,e48 3e49 392

Granulomatosis with polyangiitis (Wegener granulomatosis) (to induce remission in limited disease)

CS + MTX

165,e46,e50–e52

TMP–SMX (± CS)

2e53

Granulomatosis with polyangiitis (Wegener granulomatosis) (to induce remission in generalized disease)

CS + CYC (pulse) CS + Rituximab ± CYC CS + Rituximab

165,88,e46,e51,e52 178,79, 2e54,e55 180, 281

CS + CYC + PEX (if severe renal disease, may be first line)

1e56

MYC IVIg PEX Infliximab T cell depletion Alemtuzumab

3e57,e58 3e59 3 292,e60 3 3

Granulomatosis with polyangiitis (Wegener granulomatosis) (to maintain remission)

CS + AZA CS + MTX CS + Rituximab

182,93 182,e61,e62 187, 288

CS + CYC TMP-SMX

288 1e53

MYC AZA or MTX Leflunomide

2e57,e58,e63 382,93 3e62

*Long-term control of HCV-associated mixed cryoglobulinemia can only be achieved via a treatment regimen that incorporates anti-hepatitis C viral therapy. Additional regimens for HCV infection include ritonavir-enhanced paritaprevir + ombitasvir and dasabuvir or sofosbuvir/velpatasvir + ribavirin. **Newer antiviral agents such as tenofovir, entecavir, and telbivudine are currently under investigation. Table 24.10 Therapeutic ladder for patients with vasculitis. Key to evidence-based support: (1) prospective controlled trial; (2) retrospective study or large case series; (3) small case series or individual case reports. ACA, aminocaproic acid; AZA, azathioprine; BID, two times daily; CS, corticosteroids; CYC, cyclophosphamide; CSA, cyclosporine; HBV, hepatitis B virus; HCQ, hydroxychloroquine; HCV, hepatitis C virus; IFN, interferon; IVIg, intravenous immunoglobulin; MTX, methotrexate; MYC, mycophenolate mofetil; NSAIDs, nonsteroidal anti-inflammatory drugs; PEX, plasmapheresis; TID, three times daily; TMP–SMX, trimethoprim– sulfamethoxazole; TNF, tumor necrosis factor. Key references for treatment are summarized in references 60, 62, 65, 68, 106, 113b. Additional references cited in this table (e) are available in the online content. Continued  

431

SECTION

Urticarias, Erythemas and Purpuras

4

THERAPEUTIC LADDER FOR PATIENTS WITH VASCULITIS

Disorder

First-line treatment

Evidence levels

Second-line treatment

Evidence levels

Third-line treatment

Evidence levels

Eosinophilic granulomatosis with polyangiitis (Churg–Strauss syndrome)

CS

276

CS + CYC (first line in severe disease)

376

Mepolizumab IVIg ± PEX Rituximab AZA MYC MTX IFN-α

1105a 2e64 376,108,e65,e66 239 3e67 339 3e68,e69

Table 24.10 Therapeutic ladder for patients with vasculitis. (cont’d) Key to evidence-based support: (1) prospective controlled trial; (2) retrospective study or large case series; (3) small case series or individual case reports. AZA, azathioprine; CS, corticosteroids; CYC, cyclophosphamide; IFN, interferon; IVIg, intravenous immunoglobulin; MTX, methotrexate; MYC, mycophenolate mofetil; PEX, plasmapheresis. Key references for treatment are summarized in references 60, 62, 65, 68, 106, 113b. Additional references cited in this table (e) are available in the online content.  

Fig. 24.17 Granulomatosis with polyangiitis (Wegener granulomatosis). A Ulceration on the leg, which may be misdiagnosed as pyoderma gangrenosum.   B Ulceration of the tongue. C Subungual digital infarcts. D Palpable purpura of the legs due to small vessel vasculitis (leukocytoclastic vasculitis).  

A

C

B

D

granulomatous vasculitis. Additional disorders and their distinguishing features are outlined in Table 24.9.

Treatment

432

The standard treatment for patients with generalized GPA is systemic corticosteroids (e.g. 1 mg/kg/day of prednisone) in conjunction with oral daily cyclophosphamide (see Table 24.10), resulting in a remission in up to 75% of patients and an ~90% survival rate65,88. Pulsed intravenous cyclophosphamide also induces remissions and is associated with less toxicity, but a prolonged regimen of less frequent, reduced-dose pulses may be required to prevent relapses66. Recent data suggest that corticosteroids plus rituximab is equally effective as corticosteroids plus cyclophosphamide78–81, but the effect of rituximab on granulomatous manifestations (e.g. orbital masses) is less clear90. Of note, in one study, ANCA titers and B-cell counts during the first six months of induction

therapy were poor predictors of both disease relapse and disease quiescence91. With regard to TNF-α inhibitors, a large randomized controlled trial found that etanercept was not effective for the maintenance of remission and was associated with treatment-related complications including malignancy65. In contrast, limited studies of infliximab plus conventional therapy suggested an accelerated remission and a steroid-sparing effect92. Azathioprine can maintain a remission following induction with cyclophosphamide93, but it is associated with a higher relapse rate in patients who are PR3-positive at the time of the switch to azathioprine. Patients with the limited form of GPA may be treated with trimethoprim–sulfamethoxazole (TMP–SMX), alone or in combination with corticosteroids65. Of note, TMP–SMX is a component of the treatment regimen for all patients with GPA, as relapses can be associated

Eosinophilic Granulomatosis With Polyangiitis Synonyms:  ■ Churg–Strauss syndrome ■ Churg–Strauss vasculitis ■

Allergic angiitis and granulomatosis

Key features ■ ■ ■ ■

Asthma and allergic rhinitis typically precede vasculitic phase Peak peripheral blood eosinophil count >109/l Cutaneous vasculitis in approximately half of patients Histologic features consist of eosinophils, extravascular granulomas, and vasculitis

patients. Musculoskeletal, gastrointestinal, and ocular involvement can also occur. Laboratory findings are similar to those in patients with GPA, with the additional findings of peripheral eosinophilia (>109/l) and elevated serum IgE levels. Anti-MPO antibodies are observed more frequently than anti-PR3 antibodies (see Fig. 24.14). The presence or absence of ANCAs may be clinically relevant, with creation of two subsets of patients97. ANCA positivity has been associated with a higher risk of cardiac involvement, pleural effusions, fever, and livedo reticularis, while their absence was associated with cutaneous purpura as well as renal, sinus, and neurologic complications. Histologic evidence of vasculitis was observed in 80% of ANCA-positive patients versus 40% of ANCA-negative patients, with no difference in granulomatous inflammation97.

CHAPTER

24 Cutaneous Vasculitis

with S. aureus infections and nasal carriage (see above). Methotrexate is also used to treat limited disease, typically in combination with corticosteroids, but drug–drug interactions with sulfonamides need to be considered65. Additional alternative treatment regimens are summarized in Table 24.10.

Pathology The histopathologic hallmarks are infiltrates of eosinophils, formation of extravascular granulomas, and necrotizing vasculitis of small to medium-sized vessels; both arteries and veins are affected. Biopsy specimens obtained from papulonecrotic lesions demonstrate a palisading dermatitis with eosinophil infiltration, granuloma formation, and eosinophilic necrobiosis.

Differential diagnosis Introduction Eosinophilic granulomatosis with polyangiitis (EGPA), also referred to as Churg–Strauss syndrome, is characterized by vascular and extravascular granulomas, eosinophil-rich pulmonary infiltrates, and necrotizing vasculitis that involves small to medium-sized vessels within multiple organ systems. It is distinguished by an association with asthma and eosinophilia.

Epidemiology EGPA has an incidence ranging from 0.5 to 2.7 cases per million per year94. The mean age at diagnosis is 48 years, and it has no sex predominance. The incidence of EGPA in patients with asthma ranges from 35 to 65 per million per year.

Pathogenesis The onset of symptoms has been associated with various triggering factors, including vaccination, desensitization therapy, leukotriene inhibitors, and rapid discontinuation of corticosteroids. T lymphocytes, eosinophils, and ANCAs all play a role in the pathogenesis of this syndrome. Tissue infiltration and then degranulation of eosinophils can lead to tissue injury while T cells, especially Th2 cells, are postulated to contribute to granuloma formation. ANCA-dependent activation of neutrophils results in vasculitis (see above).

Clinical features The clinical presentation can be divided into three successive phases: (1) first phase – symptoms of allergic rhinitis, nasal polyps, and asthma, which may persist for years; (2) second phase – peripheral eosinophilia, respiratory tract infections, and gastrointestinal symptoms; and (3) third phase – systemic necrotizing vasculitis with granulomatous inflammation, which can occur several years to decades after the initial symptoms. Asthma, frequently severe, affects almost all patients and often precedes the onset of additional systemic manifestations by a decade or more39. Cutaneous findings occur in 40–75% of patients, typically during the third phase of the disease, but are the presenting sign in ~15% of patients95. Palpable purpura is seen most commonly, typically on the lower extremities and often with necrosis. Subcutaneous nodules may be seen on the scalp or extremities96, and, less often, urticaria, livedo racemosa, retiform purpura, and papulonecrotic lesions are present (Fig. 24.18). In addition to the respiratory tract, patients with EGPA often have neurologic and cardiac involvement, presenting as mononeuritis multiplex and cardiomyopathy or pericarditis. The cardiac manifestations are due to granulomatous inflammation, occur in up to half of patients, and are the leading cause of death97. Necrotizing glomerulonephritis and pulmonary capillaritis resulting in diffuse alveolar hemorrhage occur less commonly than in the other AAVs, affecting ~35% of

Other AAVs can mimic EGPA (see Table 24.9). Secondary hypereosinophilia and hypereosinophilic syndrome (HES; see Ch. 25) must also be differentiated from EGPA39. Circulating levels of eotaxin-3 and interleukin-25 may be elevated in EGPA, compared to HES98.

Treatment Over 80% of patients respond to treatment with corticosteroids alone, although relapses may occur in up to a quarter of patients achieving remission99. Lower peripheral blood eosinophil counts at the time of diagnosis may be predictive of a greater risk of relapse100. Individuals with severe internal organ involvement (CNS or myocardial disease, glomerulonephritis, gastrointestinal ischemia) or who are refractory to corticosteroids are treated with concurrent cytotoxic agents. Pulsed intravenous cyclophosphamide is considered to be first-line therapy for inducing a remission, with azathioprine, IVIg, or interferon-α as alternatives (see Table 24.10)39. Rituximab has demonstrated efficacy in refractory cases94. The anti-IL-5 antibody mepolizumab, which has been used to treat HES, is being investigated95,101,102, and it shows early promise in reducing eosinophil counts and enabling corticosteroids to be tapered, but relapses frequently occur following its discontinuation103–105a. As with leukotriene inhibitors, EGPA has been noted to develop following the administration of omalizumab, an antiIgE antibody used to treat asthma and chronic idiopathic urticaria94.

PREDOMINANTLY MEDIUM-SIZED VESSEL VASCULITIS Polyarteritis Nodosa Synonyms:  ■ Periarteritis nodosa ■ Panarteritis nodosa

Key features ■ Segmental vasculitis of predominantly medium-sized arteries ■ Systemic and cutaneous variants both can present with palpable purpura, livedo racemosa, retiform purpura, ulcers, subcutaneous nodules, or peripheral gangrene ■ Extracutaneous manifestations of the systemic variant include fever, arthralgias, myalgias, paresthesias, abdominal pain, orchitis, and renovascular hypertension ■ The cutaneous variant has a chronic, more benign course; it may be accompanied by mild systemic symptoms, in particular fever, myalgias, arthralgias, and peripheral neuropathy

433

SECTION

Urticarias, Erythemas and Purpuras

4

A

C

Fig. 24.18 Eosinophilic granulomatosis with polyangiitis (Churg–Strauss syndrome). A Palpable purpura of the buttocks due to small vessel vasculitis (leukocytoclastic vasculitis). B Purpuric dermal plaques of the palm that histologically demonstrated vasculitis of a small muscular artery.   C Crusted, firm papules of the elbow. C, Courtesy, Kalman  

Watsky, MD.

B

Introduction Polyarteritis nodosa (PAN) is a multisystem vasculitis characterized by segmental necrotizing vasculitis that involves predominantly medium-sized blood vessels. Cutaneous PAN is a “skin-limited” variant, which typically follows a benign yet chronic course. Although these two entities are discussed together in this section, it is possible that cutaneous PAN represents a distinct disorder (with occasional muscle or nerve involvement) rather than a skin-restricted variant of PAN105b.

Epidemiology The incidence of classic PAN ranges from 4 to 16 cases per million, with a male : female ratio of 4 : 1. PAN can occur at any age, but typically affects middle-aged adults (40–60 years). Cutaneous PAN represents approximately 10% of all cases of PAN, and it is the most common form of PAN in children.

Pathogenesis

434

PAN has been associated with infections, inflammatory diseases, malignancies (especially hairy cell leukemia), and medications. Concurrent HBV infection is present in approximately 7% of patients with classic PAN, and this may represent a distinct clinical subtype with a higher risk of gastrointestinal, neurologic, and renal involvement, as well as a lower 1-year survival rate106. HCV infection is also associated with classic PAN. Cutaneous PAN has been associated with other infections,

including streptococcal (especially in children), parvovirus B19, and HIV, as well as administration of minocycline107. Inflammatory conditions associated with both classic and cutaneous PAN include inflammatory bowel disease, SLE, and familial Mediterranean fever.

Clinical features In a series of 348 patients with classic (systemic) PAN, approximately 50% had cutaneous involvement109. The most common findings are palpable purpura, livedo racemosa, inflammatory retiform purpura, and “punched-out” ulcers. The palpable purpura may be pustular and/or ulcerative. Painful subcutaneous nodules and digital infarcts occur less commonly in systemic PAN. In a study that compared the cutaneous manifestations of systemic PAN and MPA, palpable purpura was the most common skin finding in both diseases – 19% and 26% of patients, respectively; urticarial lesions were more frequent in PAN (6%) than in MPA (1–2%). Overall, however, the cutaneous findings alone did not allow distinction of the two entities75. As with GPA, cutaneous involvement in PAN and MPA is associated with arthralgias and ocular disease. Higher rates of relapse in classic PAN may occur in patients with cutaneous manifestations or non-HBV–related disease109. Extracutaneous disease is the rule in classic PAN, and patients present with constitutional symptoms, such as weight loss and fever, as well as multi-organ involvement. The lungs are often spared. Common symptoms include arthralgias, paresthesias (mononeuritis multiplex), myalgias (due to myopathy), abdominal pain, and shortness of breath (due to congestive heart failure). Involvement of the kidneys occurs at

P-ANCAs, including anti-lysosomal–associated membrane protein-2 (LAMP-2) antibodies112, may be present in 10–20% of patients with cutaneous PAN. This is in contrast to systemic PAN, in which ANCAs are almost never present. In patients with cutaneous PAN, elevated titers of IgG antiphospholipid antibodies, in particular anti-cardiolipin and anti-phosphatidylserine-prothrombin complex (PS/PT) antibodies, have been reported to correlate with the presence of “inflammatory plaques”, i.e. erythematous indurated plaques113.

Pathology

CHAPTER

24 Cutaneous Vasculitis

the level of the interlobar renal arteries, resulting in renovascular hypertension and renal failure, but not glomerulonephritis. In male patients, orchitis frequently occurs, especially in association with HBV infection. Cerebral infarcts are a rare complication of classic PAN and may result from thrombotic microangiopathy or vasculitic arterial occlusion. Gastrointestinal involvement, specifically mesenteric ischemia, heralds a poor prognosis, with a 1-year survival rate of 1500 eosinophils/microliter on two occasions at least one month apart and/or tissue BMZ = basement membrane zone AI–CTD = autoimmune connective tissue disease IF = immunofluorescence

hypereosinophilia § More common in children ¶ Catch-all term that includes more poorly defined entities (e.g. itchy red bump disease, urticarial dermatitis) in which the inciting factor is unknown

Fig. 25.2 Evaluation of adults with cutaneous infiltrates rich in eosinophils. These disorders are characterized histopathologically by eosinophil infiltration and/or eosinophil granule protein deposition. Peripheral blood eosinophilia occurs in some patients. Of note, systemic corticosteroids can significantly reduce the peripheral blood eosinophil count. Photomicrograph, Courtesy, Lorenzo Cerroni, MD.  

History Initially described by Wigley as “eosinophilic granuloma”19 (not related to Langerhans cell histiocytosis), Pinkus later coined “facial granuloma with eosinophilia”20. Granuloma faciale has been included by some authors in the spectrum of IgG4-related disease (IgG4-RD; see Table 25.2)21,21a.

Epidemiology Granuloma faciale occurs predominantly in middle-aged white men, but has been observed in black and Asian men as well as women.

Pathogenesis While the precise pathogenesis remains unknown, interferon-γ and increased local IL-5 production are implicated as important mediators22. Direct immunofluorescence (DIF) microscopy demonstrates granular deposition of IgG, IgA, IgM, and/or C3 in blood vessel walls, a nonspecific finding that suggests a role for immune complexes. An increased ratio of IgG4- : IgG-bearing circulating plasma cells and/or relative increases of IgG4-positive plasma cells in skin lesions has been observed, but it is unclear if this is a specific finding.

442

Clinical Features Granuloma faciale usually presents as a solitary, asymptomatic, red– brown plaque on the face, with a predilection for the forehead, cheek,

and preauricular area (Fig. 25.3A,B)23,24. Less often, multiple papules or plaques may be present (Fig. 25.3C)25; in one retrospective analysis of 66 patients, one-third had more than one lesion24. Uncommon locations for granuloma faciale include the ears, scalp, and trunk or extremities26; in the previously cited retrospective study, 7% of the patients had extrafacial involvement25. The individual lesions tend to persist and only occasionally resolve spontaneously. Granuloma faciale has not been associated with systemic disease.

Pathology In the dermis, there are perivascular and interstitial infiltrates of neutrophils, lymphocytes and plasma cells, admixed with numerous eosinophils. Characteristically, the inflammation spares the upper papillary dermis, creating a “grenz zone” (Fig. 25.4). Features of leukocytoclastic vasculitis are most prominent early on, with older lesions tending to have fewer neutrophils and more eosinophils and plasma cells as well as fibrosis. Because of the presence of eosinophils, IgG4-bearing plasma cells and lamellar fibrosis, it has been proposed that at least a proportion of cases of granuloma faciale may represent a cutaneous manifestation of IgG4-RD (see Table 25.2)21.

Differential Diagnosis The clinical appearance of granuloma faciale is distinctive, but the differential diagnosis can include lymphoma, persistent arthropod bite reactions, angiolymphoid hyperplasia with eosinophilia, tumid lupus erythematosus, and several granulomatous disorders (e.g. sarcoidosis,

CHAPTER

Diagnosis

Clinical clues

Common entities Allergic contact dermatitis (Ch. 14)

History of exposure; suggestive distribution; positive patch test

Arthropod bite/sting reactions (Ch. 85)

Primarily involves exposed skin; mosquitoes, fleas, spiders, ticks, and mites; exaggerated reactions in patients with CLL

Atopic dermatitis (Ch. 12)

History of atopy; pruritus; flexural and extremity accentuation

Drug eruptions (Ch. 21)

Drug history, especially new drugs within the previous 2 weeks or up to 6 weeks for DRESS/DIHS Histopathologically, eosinophils are present in ~50% of cutaneous drug reactions

Erythema toxicum neonatorum (Ch. 34)

Newborn with erythematous macules, papules and pustules, often with prominent erythematous flare

Parasitic infections, particularly helminths (Ch. 83)

Cysticercosis, dirofilariasis, larva migrans, onchocerciasis, schistosomiasis, and others

Scabies (Ch. 84)

Marked nocturnal pruritus; web-space, umbilical and groin involvement

Urticaria (Ch. 18)

Pruritic, migratory, transient (lasting pemphigus, linear IgA bullous dermatosis, dermatitis herpetiformis, epidermolysis bullosa acquisita

Eosinophilic dermatosis associated with hematological disorders (eosinophilic dermatosis of hematologic malignancy; Ch. 33)

Most common in patients with CLL, but reported in patients with other hematologic malignancies

Eosinophilic fasciitis (Shulman syndrome; Ch. 43)

Sudden onset of symmetrical induration of skin and subcutaneous tissues of the limbs; peripheral blood eosinophilia

Eosinophilic granulomatosis with polyangiitis (Churg–Strauss syndrome; Ch. 24)

Palpable purpura and tender papulonodules; peripheral blood eosinophilia; respiratory tract (e.g. asthma), neurologic (e.g. mononeuritis multiplex), and cardiac involvement; prominent IgG4 and IgE responses

Eosinophilic (pustular) folliculitis (Ch. 38)

Immunosuppression, including HIV infection and post-transplant^: severe pruritus and papules on the face and upper trunk Ofuji disease: typically a Japanese patient with chronic, recurrent follicular pustules in a seborrheic distribution with tendency to form circinate plaques Pediatric: follicular pustules on the scalp of an infant

Eosinophilic, polymorphic, and pruritic eruption associated with radiotherapy (EPPER)57

Local and generalized pruritus, erythematous papules and sometimes vesicles

Eosinophilic vasculitis (histopathologic reaction pattern rather than specific dermatosis)58

Pruritic urticarial and purpuric papules, angioedema; juvenile temporal arteritis (see below)

Eosinophilic ulcer of the oral mucosa (may be within spectrum of CD30+ lymphoproliferative disorders; Ch. 72)

Rapidly enlarging nodule that develops ulceration; tongue most common site

Epithelioid hemangioma (angiolymphoid hyperplasia with eosinophilia; Ch. 114)

Single or multiple nodules of the face, scalp and/or ears

Granuloma faciale

See text

Hypereosinophilic syndromes (HESs)

See text

Incontinentia pigmenti (Ch. 62)

Vesicles and bullae along the lines of Blaschko in neonate (stage I); peripheral blood eosinophilia

Juvenile temporal arteritis

Nodule in the temporal region in an older child or young adult due to eosinophilic vasculitis

Juvenile xanthogranuloma (Ch. 91)

Yellow to red–brown papules or nodules on the head and neck, upper trunk or proximal extremities; early lesions may have numerous eosinophils

Kimura disease (Ch. 114)

Subcutaneous masses and lymphadenopathy of the head and neck region; peripheral blood eosinophilia, increased serum IgE levels

Langerhans cell histiocytosis (especially eosinophilic granuloma; Ch. 91)

Disseminated pink and yellow–brown papules (often with crusts); intertriginous involvement; occasionally, nodules

Lymphoproliferative disorders of the skin, benign and malignant (Chs 119–121)

Presentation varies depending upon specific type; variable number of eosinophils seen in entire spectrum of lymphoproliferative disorders and commonly observed in LyP and cutaneous ALCL

Mastocytosis (Ch. 118)

Pink–tan to red–brown macules, papules and plaques that urticate with stroking (Darier sign)

Table 25.1 Eosinophil-associated dermatoses. It should be emphasized that variable numbers of eosinophils may be encountered in a large number of inflammatory, neoplastic and infectious skin disorders, in addition to those listed in this table. ALCL, anaplastic large cell lymphoma; CLL, chronic lymphocytic leukemia; DIHS, drug-induced hypersensitivity syndrome; DRESS, drug reaction with eosinophilia and systemic symptoms; LyP, lymphomatoid papulosis.  

Continued

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EOSINOPHIL-ASSOCIATED DERMATOSES

Diagnosis

Clinical clues

Papuloerythroderma of Ofuji

See text

Polymorphic eruption of pregnancy (PEP; also referred to as pruritic urticarial papules and plaques of pregnancy [PUPPP]; Ch. 27)

Primigravida in third trimester; urticarial papules and plaques, especially in striae

Pruritic papular eruption of HIV disease59 (Ch. 78)

Pruritic non-follicular papules in a symmetric distribution; HIV infection; may be an exaggerated reaction to arthropod antigens but without a recognized history of bites

Seabather’s eruption (e.g. larvae of Linuche unguiculata and Edwardsiella lineata; Ch. 85)

Pruritic papules of skin covered by swimsuit; occurs after ocean swimming

Small vessel vasculitis (leukocytoclastic vasculitis; Ch. 24)

Palpable purpura that favors the lower extremities; eosinophils more commonly observed in drug-induced variant

Swimmer’s itch or cercarial dermatitis (larvae of avian and mammalian schistosome species; Ch. 83)

Pruritic papules on uncovered skin; occurs after fresh-water swimming

Urticarial allergic eruption60

Annular or gyrate urticarial plaques that persist >24 hours

Wells syndrome

See text

Less well-defined entities, with overlapping features Hypereosinophilic dermatitis of Nir–Westfried61

Pruritic, papular eruption with peripheral blood eosinophilia; often dapsone-responsive

Itchy red bump disease (papular dermatitis)

Markedly pruritic pink to red papules; may be associated with eczematous patches and/ or dermographism

Oid-oid disease (exudative discoid and lichenoid chronic dermatosis of Sulzberger and Garbe)62

Middle-aged, predominantly Jewish, men; pruritic lesions commonly involving genitals; progressive stages: discoid → exudative → lichenified; peripheral blood eosinophilia

Pachydermatous eosinophilic dermatitis63

South African black teenage girls with generalized pruritic papules, hypertrophic genital lesions and peripheral blood eosinophilia; dapsone-responsive; possibly a variant of hypereosinophilic dermatitis of Nir–Westfried

Papular eruption of blacks64

Young, black men with intensely pruritic papules on the trunk and upper arms

Urticarial dermatitis

65

Very pruritic; eczematous and/or urticarial lesions involving the trunk and proximal extremities; often occurs in the elderly and may reflect immunosenescence; minimally responsive to topical corticosteroids and oral antihistamines but can improve with UVB phototherapy or dapsone

^Hematopoietic stem cell or solid-organ.

Table 25.1 Eosinophil-associated dermatoses. (cont’d)  

IgG4-RELATED DISEASE (IgG4-RD)

Characteristic findings (not present in all patients) Clinical: swelling or mass(es) in one or more organ(s)/tissue(s) Blood: increased serum IgG4 level; increased serum IgE level; eosinophilia or hypereosinophilia • Histopathology of affected organ(s)/tissue(s): - Dense infiltrates of lymphocytes and plasma cells - Fibrosis (typically storiform pattern) - IgG4+ to IgG+ plasma cells >40%; >10 IgG4+ plasma cells/hpf - Eosinophil infiltrates - Obliterative phlebitis • •

Affected organs/tissues and/or manifestations – emerging spectrum Pancreas (autoimmune pancreatitis)



Lacrimal glands (bilateral)



Sclerosing cholangitis

Retroperitoneal fibrosis (previously viewed as idiopathic)



Thyroid (Riedel thyroiditis, fibrous variant of Hashimoto thyroiditis)



Orbit (pseudotumor, proptosis)





Salivary glands (often submandibular; bilateral)

• • •

Sinonasal eosinophilic angiocentric fibrosis Aorta (aortitis, periaortitis) Lung, pleura, pericardium, kidney (tubulointerstitial nephritis), prostate, stomach (lymphoplasmacytic gastritis), breast (sclerosing mastitis, pseudotumor)



Cutaneous disorders (or subsets thereof) that may fall within this spectrum Granuloma faciale



Kimura disease



Angiolymphoid hyperplasia with eosinophilia



444

Rosai–Dorfman disease



66

Table 25.2 IgG4-related disease (IgG4-RD) . hpf, high power field.  

CHAPTER

Eosinophil-Associated Dermatoses

25

Fig. 25.3 Granuloma faciale. Single red–brown plaques on the lateral cheek (A) and nose (B). Note the prominent follicular openings and lack of secondary changes such as scale. C Less commonly, patients present with multiple plaques. C, Courtesy, Jeffrey P Callen, MD.  

IgG4-RD, additional therapies such as prednisone may be considered, although the risk–benefit ratio will need to be addressed for this localized cutaneous disease.

PAPULOERYTHRODERMA OF OFUJI Key features

Fig. 25.4 Granuloma faciale. Dense diffuse dermal inflammation with a grenz zone. Inset shows mixed infiltrate of lymphocytes, eosinophils, neutrophils and plasma cells. Courtesy, Lorenzo Cerroni, MD.  

leprosy, granulomatous rosacea). The histopathology of granuloma faciale may have features in common with rheumatoid neutrophilic dermatitis, neutrophilic dermatosis associated with lupus erythematosus, epithelioid hemangioma (angiolymphoid hyperplasia with eosinophilia), or persistent arthropod bite reactions. Granuloma faciale may also resemble erythema elevatum diutinum (EED), both clinically and histopathologically. However, EED presents as multiple red–brown papules, plaques or nodules in a symmetric distribution on the extensor aspects of the extremities, with a predilection for the skin overlying joints. Fibrosis also tends to be more pronounced and lipid-laden macrophages may be seen in EED, but not in granuloma faciale.

Treatment Because of the facial location, treatment is often desired. Unfortunately, granuloma faciale is frequently resistant to therapy. Intralesional triam­ cinolone suspension (2.5–5 mg/ml) is often a first-line therapeutic option. As with other recalcitrant dermatoses, there are many anecdotal alternatives with reported efficacy, including oral and topical dapsone (50–150 mg daily), oral clofazimine (300 mg daily), topical PUVA, and topical calcineurin inhibitors (pimecrolimus, tacrolimus). Surgical excision, cryosurgery, dermabrasion, electrosurgery, and CO2 or pulsed dye laser therapy all have been advocated, but each carries a significant risk of scarring given the depth of inflammation. In addition, recurrences after excision have been reported. Laser therapy that targets the prominent vascular component, e.g. 595 nm pulsed dye laser, 532 nm potassium titanyl phosphate laser, has led to improvement. With recognition that granuloma faciale has features in common with

■ Occurs most commonly in elderly men ■ Widespread, pruritic, red–brown papules that may evolve into a confluent erythroderma with characteristic sparing of the skin folds (“deck-chair” sign) ■ Chronic course, with periodic exacerbations ■ Histopathologically, a nonspecific pattern consisting of lymphohistiocytic inflammation with a variable number of eosinophils ■ Peripheral blood eosinophilia, lymphopenia, and increased serum IgE level in more than two-thirds of patients ■ Association with malignancy (especially T-cell lymphoma and gastric carcinoma), infections (including HIV and hepatitis C virus), and drugs ■ Often responds to oral corticosteroids or phototherapy, alone or in combination with a systemic retinoid

History Ofuji first described this disorder in 198427.

Epidemiology Approximately 100 cases of papuloerythroderma of Ofuji have been reported to date. Over two-thirds of these individuals were elderly Japanese men, with an average age of 72 years at presentation. The disorder is much less common in Caucasians. Overall, men outnumber women by a ratio of 7 : 1.

Pathogenesis The pathogenesis remains unknown but is most likely multifactorial.

Clinical Features Papuloerythroderma of Ofuji presents as a widespread pruritic eruption of flat-topped, red–brown papules that are symmetrically distributed on the trunk and extremities and tend to coalesce. There are periodic exacerbations, often resulting in an erythroderma that strikingly spares the skin folds, a pattern referred to as the “deck-chair” sign. Most patients have peripheral blood eosinophilia, lymphopenia, and an increased serum IgE level. Peripheral lymphadenopathy commonly develops as well.

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4

PAPULOERYTHRODERMA OF OFUJI – REPORTED ASSOCIATIONS

Neoplasms

Infections

Lymphomas: T-cell lymphoma (most common), Hodgkin disease, B-cell lymphoma



Leukemias: chronic lymphocytic leukemia, acute myelogenous leukemia



Solid organ malignancies: gastric (most common), lung, colon, hepatocellular, prostate, renal, laryngeal









Drugs

Viruses: hepatitis C, human immunodeficiency virus Fungi: dermatophytes Parasites: strongyloidiasis

Other

Furosemide, ranitidine, dideoxyinosine (DDI), aspirin, isoniazid



Atopic dermatitis



Table 25.3 Papuloerythroderma of Ofuji – reported associations.  

Fig. 25.5 Wells syndrome. Edematous pink nodules and  

Reported neoplastic and infectious associations are listed in Table 25.3. The most commonly associated malignancies are T-cell lymphoma and gastric carcinoma28.

Pathology Histopathologic features are nonspecific. The epidermis is usually normal in appearance, but it may have mild acanthosis with parakeratosis and mild spongiosis. A superficial and mid-dermal mixed lymphohistiocytic infiltrate with variable numbers of eosinophils and a few plasma cells is also seen. In patients with an associated T-cell lymphoma, epidermotropism of atypical lymphocytes may be present, but it is yet unclear whether such cases should be classified as papuloerythroderma of Ofuji or as mycosis fungoides.

Differential Diagnosis During an erythrodermic flare, the clinical presentation of papuloerythroderma of Ofuji can be striking. In these patients, the differential diagnosis includes other causes of erythroderma such as psoriasis, cutaneous T-cell lymphoma, atopic dermatitis, pityriasis rubra pilaris, and drug eruptions (see Ch. 10). Sparing of skin folds is considered a distinctive feature of this entity. In patients with predominantly flattopped pruritic papules, the differential diagnosis includes lichen planus, pityriasis lichenoides chronica, papular eczema, and lichenoid drug eruption.

Treatment Systemic corticosteroids usually are effective. In one review of the literature, PUVA, alone or in combination with acitretin (or etretinate), led to complete clearance in half of patients, with an additional onethird improved29. Other reportedly effective treatments include UVB phototherapy, systemic retinoids alone, cyclosporine, and azathioprine. Topical corticosteroids, however, are often ineffective as monotherapy.

WELLS SYNDROME Synonym:  ■ Eosinophilic cellulitis

Key features

446

■ The characteristic clinical presentation is recurrent, painful or pruritic, edematous (early) to indurated (late) plaques ■ Histopathologically, a diffuse dermal infiltrate composed of eosinophils and histiocytes is seen; foci of amorphous/granular material, termed “flame figures”, are also present and reflect degranulation of eosinophils

■ Flame figures represent a characteristic but nondiagnostic finding, as they can be observed in a wide range of eosinophil-associated dermatoses ■ Distinction between Wells syndrome as a specific entity and a reaction pattern occurring in the setting of another dermatosis may be difficult, with some authors simply viewing Wells syndrome as an exaggerated reaction pattern ■ Dramatic improvement after administration of systemic corticosteroids

Introduction Wells syndrome is a cutaneous disorder of unknown etiology characterized clinically by edematous (early) to indurated (late) plaques that initially resemble cellulitis. The classic histopathologic findings consist of a diffuse dermal infiltrate of eosinophils plus characteristic “flame figures”.

History Wells described the first patient in 1971 as “recurrent granulomatous dermatitis with eosinophilia”. He later renamed the disease “eosinophilic cellulitis”30. Spigel and Winkelmann31 proposed the eponym, Wells syndrome, in 1979.

Epidemiology Over 100 cases of Wells syndrome have been reported to date, ranging from newborns to patients over 70 years of age.

Pathogenesis The pathogenesis of Wells syndrome is unknown. Local hypersensitivity due to so-called “triggers” has been proposed; the latter include insect bites or stings, drugs, allergic contact dermatitis, an underlying myeloproliferative disorder, and infections (e.g. dermatophytes, viruses, Toxocara canis). Activated eosinophils clearly play a major role in Wells syndrome, and in patients with eosinophilia (including those with Wells syndrome), it is thought that IL-2 primes eosinophil degranulation32. This hypothesis is based on the following findings: (1) eosinophils from patients with eosinophilia express the α chain of the IL-2 receptor (CD25); and (2) IL-2 enhances platelet-activating factor (PAF)stimulated release of eosinophil cationic protein from CD25-expressing eosinophils. Of note, peripheral lymphocytes isolated from patients with Wells syndrome have been reported to show exaggerated responses to mosquito salivary gland extracts33.

Clinical Features In Wells syndrome, there are recurrent episodes of prodromal itching or burning, followed by markedly edematous nodules and plaques (Fig. 25.5), which may have an annular or arcuate configuration and

Pathology An interstitial dermal infiltrate of eosinophils, with an admixture of lymphocytes and histiocytes, is seen (Fig. 25.6). The infiltrate is most prominent in the mid to deep dermis, with occasional involvement of the subcutaneous fat, fascia, and skeletal muscle. The superficial dermis may have massive papillary dermal edema to the point of subepidermal bulla formation. Intraepidermal vesiculation, with eosinophilic spongiosis, may also be present. In addition to intact eosinophils, extracellular eosinophil granules are present in the dermis. The characteristic brightly eosinophilic flame figures consist of collagen fibers coated with eosinophil granule proteins35 (Fig. 25.6, inset). Utilizing indirect immunofluorescence assays, extracellular eMBP1 from eosinophil granules has been localized to flame figures36. In addition, a palisade of histiocytes and a few multinucleated giant cells partially surround flame figures. While these flame figures are considered a hallmark of Wells syndrome, they are not a specific finding37. Flame figures can also be seen in other disorders in which degranulation of eosinophils occurs including arthropod bite and sting reactions, scabies and eosinophilic ulcer of the oral mucosa and less often parasitic infections (e.g. onchocerciasis), bullous pemphigoid, pemphigus vegetans, and eosinophilic granulomatosis with polyangiitis (Churg–Strauss syndrome).

Differential Diagnosis Wells syndrome often has a striking clinicopathologic presentation38. Early on, bacterial cellulitis and erysipelas are the most common clinical mimics. The histopathologic findings of both erysipelas and bacterial cellulitis can also include significant edema, but neutrophils are the predominant inflammatory cell in these soft tissue infections. Other causes of pseudocellulitis, including exaggerated reactions to arthropod bites, are listed in Table 74.10. Reports of Wells syndrome occurring in patients with chronic lymphocytic leukemia and nonHodgkin lymphoma may represent the latter.

Toxocara canis and other parasitic infections can present with clinical and pathologic findings resembling Wells syndrome. When a parasitic infection is suspected, laboratory evaluation includes stool examinations, serum IgE levels, specific parasite serologies, and sometimes PCR of stool. Other disorders that may present with urticarial plaques due to infiltrates of eosinophils are listed in Table 25.1. Late (mature) lesions of Wells syndrome may clinically, but not histopathologically, resemble morphea. Eosinophilic annular erythema (EAE) is also in the differential diagnosis, but this entity is considered by many to be a subset of Wells syndrome. EAE is a figurate erythema that presents with annular and polycyclic skin lesions due to dermal infiltrates of eosinophils. However, flame figures are uncommon in EAE.

Treatment

CHAPTER

25 Eosinophil-Associated Dermatoses

sometimes violaceous borders34. Vesicles and bullae can also be seen. Initially, the lesions are bright red, and then they fade to a pink–brown, green, brown, or slate-gray color. The plaques may become indurated, and lesions usually resolve over 4 to 8 weeks. Less common clinical presentations include papules and hemorrhagic bullae. The extremities are most frequently affected, but involvement of the trunk also occurs. The most common systemic complaint is malaise, with fever in less than a quarter of patients. Peripheral blood eosinophilia is common. Patients have often been misdiagnosed as having erysipelas or acute cellulitis. Precipitating events, including arthropod bites and stings, have been described in a minority of patients.

Initial therapy with prednisone 10–80 mg daily results in dramatic improvement within a few days in most patients. Tapering the dose over one month is generally well tolerated. Flares may be treated with additional courses of prednisone. Other therapeutic options include minocycline, colchicine, antimalarials, dapsone, griseofulvin, interferon-α, and antihistamines. Cyclosporine (1.25–2.5 mg/kg/day) for 3–4 weeks resulted in clinical resolution in two patients, with no relapse during the following 10 months. For mild cases, potent topical corticosteroids may be sufficient.

HYPEREOSINOPHILIC SYNDROMES Key features ■ Mucocutaneous lesions occur in >50% of patients with hypereosinophilic syndromes (HESs), in particular pruritic erythematous papules or nodules, urticaria and angioedema; mucosal ulcers are associated with an aggressive clinical course ■ Classification and treatment of HESs became more precise with discovery of the FIP1L1-PDGFRA fusion gene, whose protein product is a constitutively activated tyrosine kinase; additional rarer fusion genes and rearrangements have been identified that involve PDGFRA, PDGFRB and FGFR1, which encode plateletderived growth factor receptor-α, platelet-derived growth factor receptor-β, and fibroblast growth factor receptor 1, respectively ■ Based upon recently adopted terminology and classification criteria, primary (neoplastic) and secondary (reactive) forms of HES have been more precisely defined ■ The FIP1L1-PDGFRA fusion gene and other genetic abnormalities (see above) are present in patients with primary (neoplastic) HES, which includes eosinophilic leukemia ■ The lymphocytic (lymphoid) subtype of secondary (reactive) HES is characterized by a clonal proliferation of T cells with increased production of Th2 cytokines, particularly IL-5 ■ End-organ damage may occur from sustained tissue eosinophilia, including life-threatening endomyocardial fibrosis and/or thromboses

Introduction

Fig. 25.6 Wells syndrome. Perivascular and interstitial inflammatory infiltrates that contain eosinophils. There are several flame figures at sites of degranulated eosinophils (arrowheads; inset).  

The term “hypereosinophilic syndromes” or “HESs” was coined in the late 1960s to refer to a spectrum of eosinophil-associated diseases with common clinical features, including mucocutaneous lesions in >50% of patients. In the 1990s, a subset of patients with HES was found to have a clonal proliferation of T cells, with increased production of Th2 cytokines (in particular, IL-5). Building upon clinical observations that a subgroup of patients with HES responded to hydroxyurea, interferon, and subsequently imatinib, a molecular explanation was sought. Patients with this HES variant were found to possess a FIP1L1-PDGFRA fusion gene39, whose protein product is a constitutively activated tyrosine kinase that is over 100 times more sensitive to the inhibitory effects of imatinib than is the BCR-ABL kinase present in chronic myelogenous leukemia (CML) patients (see Pathogenesis). Since then,

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DIAGNOSTIC CRITERIA AND CLASSIFICATION OF HYPEREOSINOPHILIC SYNDROMES (HESs) AND OTHER ENTITIES WITH HYPEREOSINOPHILIA (HE)

Three diagnostic criteria 1. •  Peripheral blood hypereosinophilia – defined as >1.5 eosinophils × 109/L blood [>1500/mcl]* on two examinations at an interval of one month or greater** – and/or – • Tissue hypereosinophilia defined by the following: - Percentage of eosinophils in bone marrow section exceeds 20% of all nucleated cells – and/or – - Pathologist is of the opinion that tissue infiltration by eosinophils is extensive – and/or – - Marked deposition of eosinophil granule proteins is found in the absence or presence of major tissue infiltration by eosinophils 2. Organ damage and/or dysfunction attributable to tissue hypereosinophilia 3. Exclusion of other disorders or conditions as major reason for organ damage

Variants of HES (end-organ damage attributable to hypereosinophilia) Primary (neoplastic) HES [HESN ] Underlying neoplasm of stem cells, myeloid cells or eosinophils (WHO classification) • Eosinophils are considered (or shown) to be clonal*** • Male predominance, endomyocardial disease; mucosal ulcers poor prognostic sign • Some patients have high serum tryptase and vitamin B12 levels, tissue fibrosis, splenomegaly, and bone marrow biopsies with increased numbers of CD25+ atypical spindle-shaped mast cells† •

Secondary (reactive) HES [HESR ] An underlying inflammatory, neoplastic or other disorder • Hypereosinophilia is considered to be cytokinedriven, not due to a clonal proliferation of eosinophils • In the lymphocytic (lymphoid) subtype, clonal T cells produce Th2 cytokines •

Idiopathic HES No identified reactive or neoplastic disorder that induces hypereosinophilia



Other syndromes and disorders accompanied by hypereosinophilia Specific syndromes (often with skin manifestations)

Eosinophil-associated single-organ diseases (for skin and fascia, see Table 25.1)

Episodic angioedema with eosinophilia (Gleich syndrome) Nodules, eosinophilia, rheumatism, dermatitis and swelling (NERDS) syndrome • Eosinophilic granulomatosis with polyangiitis (Churg–Strauss syndrome) • Eosinophilia myalgia syndrome and toxic oil syndrome (both historic) • Omenn syndrome • Hyper-IgE syndromes with STAT3 and DOCK8 mutations • IgG4-related disease

Eosinophilic gastrointestinal diseases – eosinophilic esophagitis, gastroenteritis, colitis, pancreatitis, and hepatitis; eosinophilic ascites • Eosinophilic pulmonary diseases – eosinophilic asthma, bronchitis, pneumonia, pleuritis, rhinosinusitis (and nasal polyposis) • Eosinophilic genitourinary diseases – nephritis, cystitis, endometritis, myometritis • Other eosinophilic diseases – mastitis, myocarditis, synovitis, ocular disorders







*Eosinophilia is defined as 0.5–1.5 eosinophils × 109/L blood. **In the case of evolving life-threatening end-organ damage, the diagnosis of HES can be made immediately to avoid delay in treatment. ***FIP1L1-PDGFRA fusion gene and other rarer fusion genes or rearrangements involving PDGFRB or FGFR1, which encode platelet-derived growth factor receptor-β and fibroblast growth factor receptor-1, respectively; includes patients with eosinophilic leukemia, who may have other cytogenetic abnormalities.

†In the WHO classification of mastocytosis, such patients (who have the FIP1L1-PDGFRA fusion gene) are designated as having systemic mastocytosis with associated clonal hematological

non-mast cell-lineage disease (AHNMD).

Table 25.4 Diagnostic criteria and classification of hypereosinophilic syndromes (HESs) and other entities with hypereosinophilia (HE). Some patients have peripheral blood and/or tissue hypereosinophilia (HE), but without organ damage/dysfunction attributable to eosinophils, and they are subclassified as HEN (overlap with HESN), HER (overlap with HESR), HE of undetermined significance (HEUS), and hereditary (familial) HE (HEFA) in which there is familial clustering but no signs or symptoms of an inherited immunodeficiency. Adapted from ref 40.  

additional genetic abnormalities have been identified6 and other HES variants have been categorized (Table 25.4)40, along with corresponding treatment recommendations (Fig. 25.7)6.

History

448

Prior to 1968, patients with marked blood eosinophilia, in the absence of helminthiasis or allergic disease, were diagnosed using various terms. In 1968, Hardy and Anderson coined the term “hypereosinophilic syndromes (HESs)”. Chusid and colleagues41 proposed diagnostic criteria in 1975, and the clinical spectrum of HESs was defined. This was followed by the description of two major variants of HES – lymphocytic and myeloproliferative. In 2011, experts from multiple disciplines came to a consensus regarding terminology and classification criteria during the Working Conference on Eosinophil Disorders and

Syndromes6,40. This included defining hypereosinophilia as >1.5 × 109 eosinophils/L blood and eosinophilia as 0.5–1.5 × 109 eosinophils/L blood, as well as delineating primary (neoplastic) versus secondary (reactive) HES and subtypes of secondary HES. Hereditary hypereosinophilia and hyper­eosinophilia of undetermined significance were also defined40.

Epidemiology HES occurs worldwide. Up to 25% of patients may have secondary (reactive) HES, which has an equal gender distribution, while primary (neoplastic) FIP1L1-PDGFRA-positive/other mutation-positive HES has a striking male predominance (>90%, with few reported female cases). HES affects all age groups, including children, but principally adults. The average age of onset for the various HES variants is unknown, in

Screen for FIP1L1-PDGFRA , (and other rarer fusion genes involving PDGFRA or rearrangements involving PDGFRB or FGFR1)¶

* **

+



Primary (neoplastic) HES

Evaluate for an abnormal peripheral blood T-cell population via: • Flow cytometry • T-cell receptor gene rearrangement analysis • IL-5 level in plasma or serum

Chronic eosinophilic leukemia¶¶ Increased blasts in the bone marrow (5–19%) or peripheral blood (>2%)

+



Secondary (reactive) HES Lymphocytic (lymphoid) subtype

Secondary (reactive) HES

Treat underlying disease

Continue to monitor for T-cell clonality and FIP1L1-PDGFRA



CHAPTER

25 Eosinophil-Associated Dermatoses

HYPEREOSINOPHILIC SYNDROMES (HES) – CLASSIFICATION AND TREATMENT ALGORITHM

Fig. 25.7 Hypereosinophilic syndromes (HES) – classification and treatment algorithm. *An 800 kb deletion on chromosome 4 produces a fusion gene composed of a portion of the PDGFRA (platelet-derived growth factor receptor α) gene that encodes its kinase domain linked to a previously uncharacterized gene that resembles Fip1, which encodes an essential component of the Saccharomyces cerevisiae polyadenylation machinery. The resultant product is a constitutively activated tyrosine kinase that is a target of the tyrosine kinase inhibitor, imatinib. Screening can be performed on a peripheral blood sample via reverse transcriptasePCR or fluorescence in situ hybridization (FISH). **Bone marrow biopsy with cytogenetic studies should be done to exclude hematologic disorders that are accompanied by eosinophilia. Increased bone marrow mast cells and increased serum tryptase may be observed. ¶ PDGFRB and FGFR1 encode platelet-derived growth factor receptor-β and fibroblast growth factor receptor-1, respectively; patients with genetic abnormalities involving PDGFRA and PDGFRB typically respond to imatinib but not those involving FGFR1. ¶¶ May have other clonal cytogenetic and molecular genetic abnormalities; in the presence of eosinophilia, considered sufficient for diagnosis even in the absence of excess blasts. § Plus systemic corticosteroids if cardiac involvement. # CD52 is expressed on the surface of normal and malignant B and T lymphocytes, NK cells, monocytes, macrophages, and eosinophils.

Systemic corticosteroids 1 mg/kg/day Treatment with imatinib mesylate (dose sufficient to eradicate FIP1L1-PDGFRA)§,¶

Other tyrosine kinase inhibitors, e.g. nilotinib, dasatinib, sorafenib; new agents under development

Consider trial of imatinib therapy (up to 50% of patients responding to imatinib do not have a FIP1L1-PDGFRA mutation)

Control of eosinophilia is important to prevent damaging sequelae from eosinophil activity including eosinophilic endomyocardial disease and thromboembolic events HES = hypereosinophilic syndrome IL = interleukin

Interferon-α 12–50 x 106 U/week or peginterferon-α 2a 40–180 mcg/week (start low and gradually increase dose) Hydroxyurea 1–2 g/day Anti-IL-5 monoclonal antibody, e.g. mepolizumab, reslizumab Alemtuzumab (anti-CD52)# Other chemotherapeutic agents, e.g. 2-chlorodeoxyadenosine, cytarabine, chlorambucil, etoposide PUVA (for skin lesions) Dapsone Allogeneic hematopoietic stem cell transplantation

part, because of delay in diagnosis. However, identifying when HES begins is becoming more precise as disease markers become available. Primary (neoplastic) HES includes patients with eosinophilic leukemia (who may have multiple cytogenetic abnormalities)6. While individuals with the FIP1L1-PDGFRA fusion gene may be regarded as having chronic eosinophilic leukemia, there are clearly some patients who develop more aggressive disease with transformation to acute leukemia6. Patients with secondary (reactive) HES are at risk of having or developing lymphoma.

Pathogenesis Eosinophils have been implicated as the cause of much of the end-organ damage in all forms of HES via elaboration of eosinophil products (see Fig. 25.1). Clinical improvement usually parallels a decrease in the eosinophil count42. While the pathogenesis of the primary and secondary forms is now better understood (see below), the etiologies of the other forms are likely varied40. Occasional patients with episodic

angioedema and eosinophilia (Gleich syndrome) as well as those with nodules, eosinophilia, rheumatism, dermatitis and swelling (NERDS) syndrome develop T-cell clones (see Table 25.4). Therefore, as outlined in Fig. 25.7, patients who have neither primary HES nor secondary lymphocytic HES should be evaluated on a long-term basis for cytogenetic abnormalities or T-cell clonality.

Secondary (reactive) HES Patients with secondary (reactive) HES have an underlying inflammatory, neoplastic, or other disease known to induce hypereosinophilia. Eosinophils are nonclonal in this variant but abnormal clonal lymphocyte populations, frequently with unique surface phenotypes such as CD3+CD4−CD8− or CD3−CD4+, may be present or develop. Upon activation, these T cells secrete Th2 cytokines (IL-5, IL-4, IL-13). IL-5 induces eosinophilopoiesis and activates eosinophils, which then release their toxic granule contents. IL-2 may also play a role by enhancing platelet-activating factor (PAF)-stimulated eosinophil granule

449

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Urticarias, Erythemas and Purpuras

4

protein release from eosinophils (see above)30. In lymphocytic HES, high serum IgE levels are often found along with eosinophilia, probably attributable to IL-4 and IL-13 production. These patients develop severe pruritus, eczema, erythroderma, and/or urticaria and angioedema. Although secondary HES appears to be a relatively benign disease and the T-cell clones can remain stable for years, CD3−CD4+ T cells and other clonal T cells may undergo progressive transformation and evolve into lymphoma. Therefore, patients with such clones should be regarded as having premalignant or malignant T-cell lymphoma and be closely observed43.

Primary (neoplastic) HES Primary (neoplastic) HES includes patients with eosinophilic leukemia as well as individuals with the FIP1L1-PDGFRA fusion gene that results from an 800-kilobase deletion on chromosome 4q12, which, when present, may be regarded as evidence of chronic eosinophilic leukemia (see Fig. 25.7). Sensitive reverse transcriptase (RT)-PCR-based assays and fluorescence in situ hybridization (FISH) probes have been developed to detect the deletion which produces this fusion gene; the latter is composed of the portion of the platelet-derived growth factor receptor-α gene (PDGFRA) that encodes its tyrosine kinase domain linked to a previously uncharacterized gene resembling Fip1, which encodes an essential component of the Saccharomyces cerevisiae polyadenylation machinery. The resultant protein product is a constitutively activated tyrosine kinase that transforms hematopoietic cells in vitro and in vivo, analogous to the BCR-ABL kinase that results from the translocation [t(9;22)] that leads to the Philadelphia chromosome in CML. This molecular discovery provided an explanation for the clinical observation that a subgroup of patients with HES responded to imatinib (Gleevec®), a tyrosine kinase inhibitor first introduced for the treatment of CML (see Treatment)44,45. Other rarer fusion genes or rearrangements that involve PDGFRA, PDGFRB (encodes platelet-derived growth factor receptor-β), and FGFR1 (encodes fibroblast growth factor receptor 1) have been described in primary HES6. Imatinib is highly effective in patients with PDGFRA and PDGFRB fusion genes, but not in neoplasms with FGFR1 fusion genes. Unfortunately, as in CML in which patients can develop new mutations in BCR-ABL (e.g. T315I) that lead to treatment resistance, a few HES patients who initially responded to imatinib later became recalcitrant, having developed T674I mutations (during blast crisis) or tandem S601P/L629P mutations (during the chronic phase)46. Some patients with HES have increased serum tryptase levels and an increased number of atypical, spindle-shaped mast cells in the bone marrow (see Table 25.4)47. These patients develop splenomegaly, endomyocardial fibrosis, cardiomyopathy, increased serum vitamin B12 levels, and, sometimes, mucosal ulcers. However, they lack the clinical manifestations of systemic mastocytosis, i.e. tissue mast cell aggregates and c-KIT mutations. Such patients have the FIP1L1-PDGFRA fusion gene, are responsive to imatinib, and are designated as systemic mastocytosis with associated clonal hematological non-mast cell-lineage disease (AHNMD) in the World Health Organization (WHO) classification of mastocytosis (see Ch. 118). An alternative view is that a more appropriate diagnosis for these patients would be an HES variant. In some patients, the FIP1L1-PDGFRA fusion gene is detected in mast cells, neutrophils and mononuclear cells, which is interesting because many HES patients also have marked peripheral neutrophilia. Presently, it is not clear whether the cell lineages mutate independently or if a common, yet unknown, precursor cell mutates.

Clinical Features

450

Diagnostic criteria for HES are listed in Table 25.4. Patients present with signs and symptoms related to the organ systems affected by eosinophilic infiltrates, and mucocutaneous lesions occur in more than half of all affected individuals. The most common findings are pruritic erythematous macules, papules, plaques or nodules on the trunk and extremities or urticaria and angioedema48,49. Mucosal ulcers of the oropharynx or anogenital region occur in primary HES and represent a poor prognostic sign, with most afflicted patients dying within 2 years of presentation unless treated50. That said, these patients are reported to be very responsive to imatinib. Other cutaneous manifestations include erythema annulare centrifugum-like lesions, retiform purpura,

livedo reticularis and superficial thrombophlebitis, with the thrombotic entities seen almost exclusively in primary HES. The lymphocytic subtype of secondary (reactive) HES is commonly associated with severe pruritus, dermatitis, erythroderma and/or urticaria and angioedema, in addition to lymphadenopathy. Patients with secondary HES rarely develop endomyocardial fibrosis. In primary (neoplastic) HES, the presenting complex includes fever, weight loss, fatigue, malaise and skin lesions, in addition to increased serum vitamin B12 levels and increased serum tryptase levels51. The heart is often involved, with thrombus formation and progression to subendocardial fibrosis and restrictive cardiomyopathy. Mitral or tricuspid valve insufficiency results from tethering of chorda tendineae. Hepatosplenomegaly is another common feature. The central and peripheral nervous systems may also be affected, in addition to the lungs and, rarely, kidneys52. Eosinophilic endomyocardial disease can develop in any patient with prolonged blood eosinophilia, and HES patients should have echocardiography performed periodically. Embolic events also occur, particularly during the thrombotic stage, and constitute a medical emergency because of their likely serious sequelae; cutaneous involvement with splinter hemorrhages and/or nail-fold infarcts may be present and can provide the initial clues to thromboembolic disease. Of note, intramural cardiac damage has been observed in patients with HES in the absence of appreciable blood eosinophilia.

Pathology The histopathology of cutaneous lesions of HES is nonspecific and varies depending upon the type of skin lesion biopsied. Urticarial lesions have findings similar to ordinary urticaria, i.e. mild perivascular, more than interstitial, infiltrates of lymphocytes, eosinophils, and occasional neutrophils. Biopsies from papules or plaques occasionally exhibit spongiosis in addition to the dermal infiltrate that usually contains at least a few eosinophils. Flame figures are occasionally present. When studied with immunohistochemical or immunofluorescence stains for specific eosinophil granule proteins, episodic angioedema with eosinophilia and HES with mucosal ulcers show extensive deposition of granule proteins in the absence of morphologically identifiable intact eosinophils. Similar findings are observed in synovial tissues in the NERDS syndrome. Thrombosis of dermal blood vessels has been observed in biopsy specimens from retiform purpura and necrotic skin lesions in HES patients.

Differential Diagnosis The clinical and histopathologic differential diagnosis of HES includes other eosinophil-associated dermatoses (see Table 25.1), along with other dermatoses in which eosinophil degranulation occurs but infiltrates of intact eosinophils are not observed. The principal means of eosinophil degranulation is via cytolysis, and eosinophils lyse within tissues during or soon after infiltration. The footprint of eosinophil participation is deposition of granular contents (e.g. eMBP1), which remain in the tissue while the cell itself is not morphologically identifiable, although parts of the eosinophil may be recognizable by electron microscopy. In contrast to Wells syndrome, patients with primary HES tend to be more systemically ill, with signs and symptoms of multi-organ involvement. Occasionally, dermal flame figures are seen in skin lesions of HES. Eosinophilic granulomatosis with polyangiitis (EGPA; Churg– Strauss syndrome) can resemble HES clinically and is considered by some authors to be an HES-associated disease. Patients with EGPA have asthma as well as prominent IgG4 and IgE responses (see Ch. 24)53. While patients with EGPA have vasculitis of small and medium-sized vessels, vasculitis is an uncommon feature of HES. However, thromboembolic phenomena may produce lesions that mimic vasculitis (see Ch. 22). Parasitic infections and infestations may closely resemble HES. A history of travel to endemic areas or a suggestive dietary history implicates helminthiasis. In such patients, serologic testing for antiStrongyloides antibodies and three stool samples for ova and parasites should be obtained. A total serum IgE level >500 IU/ml is often seen in helminth infections. Inappropriate treatment of Strongyloides stercoralis with systemic corticosteroids or other immunosuppressives may result in severe sequelae, including death. In patients with HES and isolated urticarial plaques with or without angioedema, the differential diagnosis includes ordinary urticaria. In

Treatment In light of the FIP1L1-PDGFRA fusion gene discovery, an algorithmic approach for the evaluation and treatment of HES is provided in Fig. 25.7. If FIP1L1-PDGFRA or other genetic abnormalities involving PDGFRA or PDGFRB are present, imatinib therapy is warranted. Imatinib, a 2-phenylaminopyrimidine tyrosine kinase inhibitor, exerts its effect by binding to the amino acids of the fusion tyrosine kinase’s ATP-binding site and stabilizes the inactive, non-ATP-binding form of the FIP1L1-PDFGRA fusion protein. This prevents autophosphorylation of the fusion protein and phosphorylation of other substrates, resulting in termination of the signaling cascade that induces genes related to eosinophil proliferation and activation. Patients respond to varying doses of imatinib, depending upon an individual patient’s sensitivity and ability of the given dosage to suppress the mutant clone. Imatinib doses ranging from 400 mg daily to 100 mg weekly or less have proven effective, with a hematologic and molecular remission observed in most patients with the fusion protein. However, maintenance therapy is required to avoid relapse. Because endomyocardial disease may worsen during the first several days of imatinib administration, serum levels of troponin and N-terminal pro-brain natriuretic peptide (NT-proBNP) should be monitored. Preemptive and concurrent treatment with corticosteroids is also recommended to maintain cardiac function. Secondary HES is best managed by treating the underlying disease, once determined. When the underlying disease fails to respond to firstline therapies and the patient lacks PDGFRA or PDGFRB fusion genes, then corticosteroids are begun, usually prednisone at 1 mg/kg/day; ~70% of patients will respond, with the peripheral eosinophilia returning to normal levels. As the eosinophil counts normalize, cardiac function improves. For patients who fail corticosteroid monotherapy or develop significant long-term side effects, there are several other

therapeutic options (see Fig. 25.7). For example, patients with no detectable FIP1L1-PDGFRA fusion gene have achieved partial remission from imatinib, although the mechanism of response in these patients is unclear. Perhaps some patients had diagnostically occult PDGFRA or PDGFRB rearrangements, especially individuals with the rare complete responses46. Thus, imatinib represents a reasonable therapeutic option, given its relative safety. Interferon (IFN)-α (12–50 × 106 U/week) has been beneficial in patients with both primary and secondary HES. Its mode of action is likely via myelosuppression but may include effects on Th2 helper cells by changing the cytokine milieu (including a decrease in IL-5 levels). For some patients, pegylated interferon (peginterferon-α 2a), administered weekly, is better tolerated. Following prolonged IFN-α treatment, clinical and molecular remission may occur in patients with the FIP1L1PDGFRA fusion gene, suggesting that IFN-α may modify the disease in unanticipated ways. One concern regarding the use of IFN-α, based upon the findings of an in vitro study in which IFN-α acted as a growth factor for CD3−CD4+ cells, is probably minimized by concomitant corticosteroid therapy. Two monoclonal antibodies against human IL-5 that are approved for the treatment of asthma, mepolizumab and reslizumab, have been used for HES in clinical trials. Analyses of cytokine production by lymphocytes before and after treatment with mepolizumab showed a striking reduction in Th2 cytokine production (e.g. IL-13, IL-10) in addition to the expected IL-5 reduction54. In a randomized, double-blind, placebo-controlled trial involving 85 FIP1L1-PDGFRA-negative patients who were already receiving prednisone (20–60 mg/day), administration of mepolizumab (750 mg IV every 4 weeks for 9 cycles) led to twice as many individuals (84% vs 43%) being successfully tapered to a stable prednisone dose of ≤10 mg/day55. Other kinase inhibitors (e.g. nilotinib, dasatinib, sorafenib) may also be useful in patients who do not respond to imatinib or become resistant as a consequence of mutations such as T674I in FIP1L1-PDGFRA46. The main treatment goals via single- or multiple-agent regimens are relief of symptoms and keeping the peripheral eosinophil count in the range of 1–2 × 109/L blood or less. HES patients also need to be routinely monitored and treated for organ involvement, particularly cardiac. Overall, HES has a 5-year survival rate of 80%, with congestive heart failure followed by sepsis as the leading causes of death. Patients who fail corticosteroid monotherapy have a worse prognosis.

CHAPTER

25 Eosinophil-Associated Dermatoses

such patients, demonstration of internal organ involvement favors HES. In addition, HES with episodic angioedema may resemble hereditary or acquired angioedema clinically, but complement studies help to distinguish these entities (see Fig. 18.19). Furthermore, patients with hereditary angioedema often have a family history of the disease and rarely are their peripheral blood eosinophil counts as high as in HES. Patients with secondary (reactive) HES commonly have pruritic skin lesions that become eczematous. The differential diagnosis in these patients includes atopic dermatitis, allergic contact dermatitis, drug reaction, and cutaneous T-cell lymphoma.

For table on entities in which flame figures may be seen visit www.expertconsult.com

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31. Spigel GT, Winkelmann RK. Wells’ syndrome. Recurrent granulomatous dermatitis with eosinophilia. Arch Dermatol 1979;115:611–13. 32. Simon HU, Plotz S, Simon D, et al. Interleukin-2 primes eosinophil degranulation in hypereosinophilia and Wells’ syndrome. Eur J Immunol 2003;33:834–9. 33. Koga C, Sugita K, Kabashima K, et al. High responses of peripheral lymphocytes to mosquito salivary gland extracts in patients with Wells’ syndrome. J Am Acad Dermatol 2010;63:160–1. 34. Fisher GB, Greer KE, Cooper PH. Eosinophilic cellulitis (Wells’ syndrome). Int J Dermatol 1985;24:101–7. 35. Brehmer-Andersson E, Kaaman T, Skog E, Frithz A. The histopathogenesis of the flame figure in Wells’ syndrome based on five cases. Acta Derm Venereol 1986;66:213–19. 36. Peters MS, Schroeter AL, Gleich GJ. Immunofluorescence identification of eosinophil granule major basic protein in the flame figures of Wells’ syndrome. Br J Dermatol 1983;109:141–8. 37. Leiferman KM, Peters MS. Reflections on eosinophils and flame figures: where there’s smoke there’s not necessarily Wells syndrome. Arch Dermatol 2006;142:1215–18. 38. Aberer W, Konrad K, Wolff K. Wells’ syndrome is a distinctive disease entity and not a histologic diagnosis. J Am Acad Dermatol 1988;18:105–14. 39. Gotlib J, Cools J, Malone JM III, et al. The FIP1L1– PDGFRalpha fusion tyrosine kinase in hypereosinophilic syndrome and chronic eosinophilic leukemia: implications for diagnosis, classification, and management. Blood 2004;103:2879–91. 40. Valent P, Klion AD, Horny HP, et al. Contemporary consensus proposal on criteria and classification of eosinophilic disorders and related syndromes. J Allergy Clin Immunol 2012;130:607–12.e9. 41. Chusid MJ, Dale DC, West BC, Wolff SM. The hypereosinophilic syndrome: analysis of fourteen cases with review of the literature. Medicine (Baltimore) 1975;54:1–27.

42. Gleich GJ. Mechanisms of eosinophil-associated inflammation. J Allergy Clin Immunol 2000;105:651–63. 43. Roufosse F, Weller PF. Practical approach to the patient with hypereosinophilia. J Allergy Clin Immunol 2010;126:39–44. 44. Gleich GJ, Leiferman KM, Pardanani A, et al. Treatment of hypereosinophilic syndrome with imatinib mesilate. Lancet 2002;359:1577–8. 45. Gleich GJ, Leiferman KM. The hypereosinophilic syndromes: still more heterogeneity. Curr Opin Immunol 2005;17:1–6. 46. Gotlib J. Tyrosine kinase inhibitors in the treatment of eosinophilic neoplasms and systemic mastocytosis. Hematol Oncol Clin N Am 2017;31:643–61. 47. Pardanani A, Brockman SR, Paternoster SF, et al. FIP1L1–PDGFRA fusion: prevalence and clinicopathologic correlates in 89 consecutive patients with moderate to severe eosinophilia. Blood 2004;104:3038–45. 48. Kazmierowski JA, Chusid MJ, Parrillo JE, et al. Dermatologic manifestations of the hypereosinophilic syndrome. Arch Dermatol 1978;114:531–5. 49. Leiferman KM, Gleich GJ, Peters MS. Dermatologic manifestations of the hypereosinophilic syndromes. Immunol Allergy Clin North Am 2007;27:415–41. 50. Leiferman KM, O’Duffy JD, Perry HO, et al. Recurrent incapacitating mucosal ulcerations. A prodrome of the hypereosinophilic syndrome. JAMA 1982;247:1018–20. 51. Curtis C, Ogbogu P. Hypereosinophilic syndrome. Clin Rev Allergy Immunol 2016;50:240–51. 52. Ogbogu PU, Bochner BS, Butterfield JH, et al. Hypereosinophilic syndrome: a multicenter, retrospective analysis of clinical characteristics and response to therapy. J Allergy Clin Immunol 2009;124:1319–25. 53. Vaglio A, Buzio C, Zwerina J. Eosinophilic granulomatosis with polyangiitis (Churg-Strauss): state of the art. Allergy 2013;68:261–73. 54. Plotz SG, Simon HU, Darsow U, et al. Use of an anti-interleukin-5 antibody in the hypereosinophilic

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syndrome with eosinophilic dermatitis. N Engl J Med 2003;349:2334–9. Rothenberg ME, Klion AD, Roufosse FE, et al., for the Mepolizumab HES Study Group. Treatment of patients with the hypereosinophilic syndrome with mepolizumab. N Engl J Med 2008;358:1215–28. Hebert AA, Esterly NB. Annular erythema of infancy. J Am Acad Dermatol 1986;14:339–43. Rueda RA, Valencia IC, Covelli C, et al. Eosinophilic, polymorphic, and pruritic eruption associated with radiotherapy. Arch Dermatol 1999;135:804–10. Chen KR, Pittelkow MR, Su D, et al. Recurrent cutaneous necrotizing eosinophilic vasculitis. A novel eosinophilmediated syndrome. Arch Dermatol 1994;130:  1159–66. Resneck JS Jr, Van Beek M, Furmanski L, et al. Etiology of pruritic papular eruption with HIV infection in Uganda. JAMA 2004;292:2614–21. Ackerman AB. Urticarial allergic eruption. In: Ackerman AB, editor. Histologic Diagnosis of Inflammatory Skin Diseases. 1st ed. Philadelphia: Lea & Febiger; 1978. p. 181–3. Nir MA, Westfried M. Hypereosinophilic dermatitis. A distinct manifestation of the hypereosinophilic syndrome with response to dapsone. Dermatologica 1981;162:444–50. Sulzberger MB, Garbe W. Nine cases of a distinctive exudative discoid and lichenoid chronic dermatosis. Arch Dermatol Syphilol. 1937;36:247–72. Jacyk WK, Simson IW, Slater DN, Leiferman KM. Pachydermatous eosinophilic dermatitis. Br J Dermatol 1996;134:469–74. Rosen T, Algra RJ. Papular eruption in black men. Arch Dermatol 1980;116:416–18. Kossard S, Hamann I, Wilkinson B. Defining urticarial dermatitis: a subset of dermal hypersensitivity reaction pattern. Arch Dermatol 2006;142:29–34. Stone JH, Zen Y, Deshpande V. IgG4-Related Disease. N Engl J Med 2012;366:539–51.

ENTITIES IN WHICH FLAME FIGURES MAY BE SEEN Angiolymphoid hyperplasia with eosinophilia Arthropod bite and sting reactions Parasitic infections (e.g. ascariasis, onchocerciasis, gnathostomiasis, onchocerciasis, toxocariasis) Eosinophilic granulomatosis with polyangiitis (Churg–Strauss syndrome) Eosinophilic pustular folliculitis Hypereosinophilic syndromes Autoimmune bullous diseases (e.g. pemphigoid, pemphigoid gestationis, pemphigus vegetans) Incontinentia pigmenti

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25 Eosinophil-Associated Dermatoses

Online only content

Kimura disease Mastocytoma Wells syndrome

eTable 25.1 Entities in which flame figures may be seen.  

452.e1

Neutrophilic Dermatoses Mark D. P. Davis and Samuel L. Moschella

The neutrophilic dermatoses constitute a heterogeneous but linked spectrum of diseases1, with significant overlapping histopathologic findings and similar pathogenic mechanisms and therapeutic approaches. They are often associated with underlying internal diseases, which may have significant morbidity and mortality. Histologically, these disorders are characterized by perivascular and diffuse neutrophilic infiltrates without any identifiable infectious agents (Fig. 26.1). The cutaneous manifestations vary, from urticarial plaques and vesiculopustules to nodules and ulcers. It is noteworthy that there may be several different types of lesions in the same patient. The dermatosis may be localized or more widespread, and, in an occasional patient, similar sterile neutrophilic infiltrates may occur in other organs including the eyes, joints, bones, lung and kidney. The neutrophilic infiltrate may be most prominent in the epidermis, dermis, or even the panniculus. Distinct entities have been defined by the nature of their clinical and histologic presentations as well as their associated diseases. Of note, patients with autoinflammatory disorders may develop neutrophilic dermatoses, from sterile pustules in DIRA (deficiency of IL-1 receptor antagonist) to pyoderma gangrenosum in PAPA (pyogenic [sterile] arthritis, pyoderma gangrenosum, and acne) and PASH (pyoderma gangrenosum, acne, and suppurative hidradenitis) syndromes (see Tables 45.6 and 45.7). There is also overlap between neutrophilic dermatoses and neutrophilic urticaria (see Table 45.6).

NEUTROPHIL BIOLOGY Granulocytes (neutrophils, eosinophils and basophils) are cells essential to our defense against microbes as well as other inflammatory responses. The neutrophil is a terminally differentiated, non-dividing cell which is packed with granules whose contents kill and degrade target microorganisms. Recent advances in our understanding of neutrophil biology include the molecular and cellular mechanisms responsible for their production and release from the bone marrow (e.g. chemokine CXC receptor 4 [CXCR-4]; see Ch. 60); their recruitment, priming and activation within inflamed tissues (Table 26.1); and the events resulting in their removal. Granulocytes, including neutrophils, originate in the bone marrow from pluripotent cells. In order to supply sufficient numbers of circulating cells, neutrophils are produced within the bone marrow at a prodigious baseline rate (>5–10 × 1010 neutrophils daily). The bone marrow also has the capacity to upregulate granulocyte production sharply in response to a number of stresses such as infection. Mature neutrophils circulate in the peripheral bloodstream for only 6–8 hours before migrating into tissues, where they survive for 2–3 days. Neutrophils, unlike platelets and erythrocytes, appear to be removed from the circulation in a random rather than an age-related manner. Transcriptional profiling studies suggest that granulocytes arise via the selective expression of a subset of transcription factors (e.g. STAT3), granulocyte proteins (e.g. neutrophil elastase), and receptors (e.g. N-formyl-methionyl-leucyl-phenylalanine [fMLP]). Differentiation from pluripotent stem cells requires 7–10 days, and during this period, under the influence of cytokines, neutrophils acquire their characteristic appearance and granules (primary, secondary and tertiary). The following stages of myeloid maturation are recognized: myeloblast, promyelocyte, myelocyte, metamyelocyte, band, and, finally, the segmented neutrophil. The progressive gain of differentiated characteristics is accompanied by a loss in the potential to proliferate, i.e. beyond the myelocyte stage, the cells are non-dividing. The intracellular granules acquired during maturation contain enzymes that mediate the oxidative and non-oxidative killing functions of the neutrophil2:

26 

(azurophilic) granules – acquired at the promyelocyte stage • primary and their contents include myeloperoxidase, lysozyme, neutrophil

• •

elastase, defensins, proteinase 3, and bactericidal/permeabilityincreasing protein secondary granules – acquired at the transition to the myelocyte stage and their contents include lactoferrin, neutrophil collagenase, neutrophil gelatinase-associated lipocalin, and lysozyme tertiary granules – acquired during later stages of neutrophil maturation and contain neutrophil gelatinase and leukolysin.

Inflammation A critical role of inflammation is to deliver neutrophils and other leukocytes to a site of injury and then activate these cells to perform their function of protecting the host against infection. Neutrophils are among the first cells to arrive at sites of inflammation. Reasons for this include their abundance in the bloodstream and their rapid response to chemokines. When activated, neutrophils move at speeds up to 30 microns/ min – the fastest cell in the body. The motile responses of neutrophils to microbial infection include emigration out of the vasculature and movement toward the source of the inflammatory chemoattractant. This culminates in the phagocytic ingestion of opsonized microbes. In order to arrive at the site of infection, leukocytes must migrate out of the vasculature via margination, rolling, activation, and tight adhesion (see Ch. 102). They then move toward the site of injury or infection (see Table 26.1) and eventually undergo degranulation then apoptosis. The price to be paid for the defensive potency of neutrophils for destroying microbes and necrotic tissues is that they can injure normal tissue. During activation and phagocytosis, neutrophils release products (e.g. lysosomal enzymes, reactive oxygen intermediates, products of arachidonic acid metabolism [prostaglandins and leukotrienes]) not just within the phagolysosome, but also into the extracellular space. Endothelial injury and tissue damage ensue, thus contributing to a number of acute and chronic diseases that affect the skin as well as other organs.

SWEET SYNDROME Synonym:  ■ Acute febrile neutrophilic dermatosis

Key features ■ Constitutional signs and symptoms such as fever and malaise ■ Clinically, erythematous plaques that are occasionally bullous ■ Histologically, dense perivascular neutrophilic infiltrate, edema and, infrequently, bullae; leukocytoclasia with minimal to no evidence of vasculitis ■ Associated conditions include infections, malignancies (especially acute myelogenous leukemia), inflammatory bowel disease, autoimmune disorders (e.g. systemic lupus erythematosus [SLE]), drugs, and pregnancy

History The prototype of the neutrophilic dermatoses is Sweet syndrome. In 1964, Sweet3 described eight middle-aged women who had an acute onset of fever and erythematous plaques associated with a nonspecific

453

Neutrophils are essential inflammatory cells. In response to infection they accumulate rapidly at sites of infection or injury and become activated. These cells are packed with granules whose contents kill and degrade target microorganisms following phagocytosis of opsonized microbes. Occasionally, neutrophils can suddenly accumulate and become activated in the absence of an identifiable local infection. Release of their cytoplasmic granules then leads to injury of normal tissue. Neutrophilic dermatoses, including those seen in the setting of autoinflammatory disorders, are examples of this phenomenon. Examples of neutrophilic dermatoses include Sweet syndrome, pyoderma gangrenosum (PG), and Behçet disease. Both Sweet syndrome and PG can be idiopathic in nature but a significant proportion of patients have associated underlying diseases, e.g. hematologic malignancies, inflammatory bowel disease. Occasionally, these neutrophilic disorders are triggered by medications. In addition to Sweet syndrome, PG and Behçet disease, this chapter reviews the clinical manifestations of bowel-associated dermatosis– arthritis syndrome and SAPHO (synovitis, acne, pustulosis, hyperostosis and osteitis) syndrome.

neutrophilic dermatoses, Sweet syndrome, acute neutrophilic dermatosis, pyoderma gangrenosum, Behçet disease, bowel-associated dermatosis–arthritis syndrome, autoinflammatory disorders, SAPHO (synovitis, acne, pustulosis, hyperostosis and osteitis) syndrome

CHAPTER

26 Neutrophilic Dermatoses

ABSTRACT

non-print metadata KEYWORDS:

453.e1

SECTION

Urticarias, Erythemas and Purpuras

4

NON-INFECTIOUS NEUTROPHILIC DERMATOSES Neutrophilic dermatosis (non-infectious)

Primarily dermal

Epidermal

Vasculitis





Sweet syndrome† Pyoderma gangrenosum Behçet disease‡

Pustular psoriasis Drug-induced/acute generalized exanthematous pustulosis

Bullous dermatoses Dermatitis herpetiformis

Bowel-associated dermatosis– arthritis syndrome

Linear IgA bullous dermatosis

Sneddon–Wilkinson disease

Inflammatory bowel disease‡

IgA pemphigus • Subcorneal pustular dermatosis type • Intraepidermal neutrophilic IgA dermatosis type

Bullous systemic lupus erythematosus

Neutrophilic eccrine hidradenitis

Keratoderma blennorrhagicum Drug-induced pustular dermatosis

**

Amicrobial pustulosis of the folds Infantile acropustulosis

Transient neonatal pustulosis Genodermatoses∞, including DIRA syndrome, DITRA syndrome, ADAM17 deficiency, CARD14mediated pustular psoriasis



+

Neutrophilic dermatosis of the dorsal hands

Inflammatory epidermolysis bullosa acquisita

Rheumatoid neutrophilic dermatitis Neutrophilic urticaria Still disease Schnitzler syndrome Erythema marginatum Periodic fever syndromes Genodermatoses, including PAPA syndrome††, Majeed syndrome, CANDLE syndrome

+

*

Small vessel vasculitis (leukocytoclastic vasculitis) including urticarial vasculitis Erythema elevatum diutinum Medium-sized vessel vasculitis



Minority of patients have evidence of secondary vasculitic changes ‡ Patients may have small vessel vasculitis

*Localized neutrophilic dermatosis with pustules, hemorrhagic bullae and ulcers within

erythematous nodules and plaques; dense dermal neutrophilic infiltrate > small vessel vasculitis; some authors consider it a subset of Sweet syndrome. Chronic pustular dermatosis that primarily affects intertriginous sites, the external auditory canals and the scalp of young women with an autoimmune connective tissue disease, including systemic lupus erythematosus ∞Neutrophilic infiltrate also within the dermis †† Including the variants PASH and PAPASH syndromes

**

Fig. 26.1 Non-infectious neutrophilic dermatoses. Entities in the darker box are discussed in this chapter. CANDLE, chronic atypical neutrophilic dermatosis with lipodystrophy and elevated temperature; DIRA, deficiency of the interleukin-1 receptor antagonist; DITRA, deficiency of the interleukin-36 receptor antagonist; PAPA, pyogenic arthritis, pyoderma gangrenosum, and acne; PAPASH, pyogenic arthritis, pyoderma gangrenosum, acne, and suppurative hidradenitis; PASH, pyoderma gangrenosum, acne, and suppurative hidradenitis  

infection of the respiratory tract or gastrointestinal tract. Histologically, the skin lesions were characterized by a neutrophilic infiltrate. He named this constellation of findings “acute febrile neutrophilic dermatosis”. In 1968, Whittle and colleagues reported a similar case and named it “Sweet’s syndrome”.

Epidemiology Sweet syndrome is an uncommon disease, with a worldwide distribution and no obvious racial predilection, although the disorder appears to be more frequent in Japan. The average age of onset is 30–60 years, but infants, children and the elderly may be affected; there is a female predominance of 4 to 1. At least half of patients have an identifiable associated disorder or trigger: 15–30% have an internal malignancy (hematologic ≫ solid organ), ~25% a preceding infection, and ~10% exposure to a potentially causative drug (Table 26.2)4–7. While the epidemiologic statistics in part reflect associated underlying disorders including internal malignancies, inflammatory bowel disease and autoimmune connective tissue diseases such as SLE8, they do not completely explain the female predominance.

Pathogenesis

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The pathogenesis of Sweet syndrome is unknown. The association with underlying diseases suggests a hypersensitivity reaction. One hypothesis is a local or systemic dysregulation of cytokine secretion, involving interleukin (IL)-1, granulocyte colony-stimulating factor (G-CSF), granulocyte–macrophage colony-stimulating factor (GM-CSF), and interferon-γ9. For example, increased expression of IL-1β has been noted within cutaneous lesions. Defects in transcriptional regulation of hematopoietic PTPN6, which encodes protein tyrosine phosphatase nonreceptor type 6, and formation of splice variants are also thought to be involved in the pathogenesis of Sweet syndrome10. Lastly, in some

patients, mutations have detected in the gene associated with familial Mediterranean fever, MEFV10a.

Clinical Features The initial cutaneous lesions are tender, non-pruritic, erythematous plaques or papules, which may enlarge or coalesce to form plaques with an uneven mammillated surface (Figs 26.2 & 26.3). Because of the pronounced associated edema, the lesions may have a pseudovesicular or pseudopustular appearance; however, some patients actually do develop vesiculation, bullae or pustules within their plaques. Occasionally, the plaques have a central yellowish discoloration creating a targetoid appearance. A facial erysipelas-like appearance has also been described as has a giant cellulitis-like variant. The vesiculobullous variant, which is most frequently associated with acute myelogenous leukemia, can progress to ulceration resembling superficial pyoderma gangrenosum (PG). In this form, there may be a single lesion or multiple, asymmetrically distributed lesions. The cutaneous eruption of Sweet syndrome favors the head, neck and upper extremities (including the dorsal aspect of the hands), but can occur anywhere. In true malignancy-associated cases, the lesions tend to have a more widespread distribution. Papulonodules involving the lower legs may resemble erythema nodosum and although erythema nodosum has been reported in patients with Sweet syndrome, such nodules more likely represent a neutrophilic panniculitis. When isolated, the latter is often referred to as subcutaneous Sweet syndrome. As with PG, specific lesions may be initiated by wounding injuries such as needle sticks (pathergy). Oral lesions are uncommon, except in patients with hematologic disorders; initially they appear pseudopustular, and later ulcerate and appear as aphthae. The cutaneous eruption of Sweet syndrome usually resolves spontaneously within 5–12 weeks but recurs in up to 30% of patients.

CHAPTER

Intravascular adhesion, activation and migration Neutrophils are activated by chemoattractants (bacterial-derived and host-produced), ligands of selectins, immune complexes, and activated complement components to express β2 integrins (e.g. LFA-1) that then adhere to ICAM-1 on endothelial cells (see Fig. 102.10) • Endothelial cells can be activated by thrombin, histamine, cytokines (e.g. IL-1β, TNF-α, IL-17), LPS/endotoxin, and immune complex–C1q aggregates to express adhesive molecules (e.g. P-selectin, E-selectin, ICAM-1, VCAM-1) • PSGL-1 and L-selectin on the neutrophil surface are critical for tethering of neutrophils to the vessel wall followed by rolling then firm adhesion via β2 integrins (see above) • Diapedesis represents migration of cells through inter-endothelial spaces towards a chemical concentration gradient, i.e. towards a site of infection or injury •

26 Neutrophilic Dermatoses

NEUTROPHILS – THEIR RELATIONSHIP TO SITES OF INFLAMMATION

Migration within tissue Leukocytes adhere to matrix proteins and follow chemotactic gradients In response to the binding of chemoattractants (e.g. fMLP, C5a, PAF, LTB4), neutrophils change their shape and crawl by alternating the extrusion and retraction of frontal lamellipodia, where chemokine and phagocytic receptors are concentrated

• •

Activation within tissue Upon arrival at the site of injury or infection, neutrophils become activated via several signaling pathways (e.g. MAPK/ERK, PKC, phospholipase A2, cytosolic [Ca2+]) and surface receptors are expressed (e.g. Toll-like receptors, receptors for cytokines, opsonins) • Activation results in degranulation and secretion of lysosomal enzymes, activation of the oxidative burst, production of arachidonic acid metabolites, and secretion of cytokines •

Phagocytosis Recognition and attachment of the particle to be ingested by the neutrophil is greatly enhanced by opsonization (coating by opsonins such as antibodies, complement or lectins), which targets it for phagocytosis • Binding of the particle to phagocytic neutrophil receptors initiates engulfment of the particle, which then fuses with a lysosomal granule, forming a phagolysosome •

Degranulation Microbes are killed preferentially by oxygen-dependent, rather than oxygen-independent, mechanisms with formation of reactive oxygen intermediates With discharge of the granule’s contents into the phagolysosome, the neutrophil becomes degranulated • NETosis also occurs, representing the process of setting neutrophil extracellular traps; these traps are composed of histones and antimicrobial granular and cytoplasmic proteins • Neutrophils then rapidly undergo apoptosis and are ingested by macrophages • •

Table 26.1 Neutrophils – their relationship to sites of inflammation2. fMLP, N-formyl-methionyl-leucyl-phenylalanine (bacterial-derived formylated tripeptide); ICAM, intercellular adhesion molecule; IL, interleukin; LFA, lymphocyte function-associated antigen; LPS, lipopolysaccharide; LT, leukotriene; MAPK, mitogenactivated protein kinase; PAF, platelet-activating factor; PKC, phosphokinase C; PSGL-1, P-selectin glycoprotein ligand-1; TNF, tumor necrosis factor; VCAM, vascular cell adhesion molecule.  

SWEET SYNDROME – ASSOCIATED DISORDERS AND TRIGGERS

Infections Viruses: upper respiratory tract infections, cytomegalovirus, hepatitis B virus, hepatitis C virus, HIV Bacteria: Yersinia, streptococci • Mycobacteria: atypical mycobacteria, BCG vaccination, M. tuberculosis, M. leprae • Fungi: dimorphic, including sporotrichosis and coccidiomycosis • •

Malignancies Hematologic (10–20% of cases*), in particular acute myelogenous leukemia Myelodysplasia • Solid organ, predominantly the more common primary carcinomas •



Gastrointestinal disorders Inflammatory bowel disease: Crohn disease, ulcerative colitis



Drugs Antibiotics (e.g. minocycline, trimethoprim-sulfamethoxazole), antihypertensives (e.g. furosemide, hydralazine), antineoplastics (e.g. ipilimumab, pembrolizumab, FLT3 inhibitors, vemurafenib), colony stimulating factors (e.g. G-CSF), contraceptives, immunosuppressant medications (e.g. azathioprine), NSAIDs, retinoids (e.g. all-trans-retinoic acid), bortezomid, lenalidomide



Autoimmune disorders Autoimmune connective tissue diseases (e.g. systemic lupus erythematosus [SLE]‡, rheumatoid arthritis, dermatomyositis, relapsing polychondritis, Sjögren syndrome), autoimmune thyroid disease • Sarcoidosis • Behçet disease •

*‡ Includes acute and chronic myelogenous leukemia, chronic lymphocytic leukemia, non-Hodgkin disease, Hodgkin’s disease, myeloma, other myeloproliferative disorders. Some authors use the terms non-bullous neutrophilic LE or neutrophilic dermatosis in conjunction with LE rather than Sweet syndrome associated with SLE.

Table 26.2 Sweet syndrome – associated disorders and triggers. The most common associations are in bold. G-CSF, granulocyte colony-stimulating factor; HIV, human immunodeficiency virus.  

455

SECTION

4

SYSTEMIC MANIFESTATIONS OF SWEET SYNDROME

Urticarias, Erythemas and Purpuras

Common (≥50%) Fever Leukocytosis

Less common (20–50%) Arthralgias Arthritis: asymmetric, non-erosive, sterile, favors knees and wrists Myalgias Ocular involvement: conjunctivitis, episcleritis, limbal nodules, iridocyclitis

Uncommon Neutrophilic alveolitis: cough, dyspnea and pleurisy; radiographic findings include interstitial infiltrates, nodules, pleural effusions Multifocal sterile osteomyelitis, a subtype of SAPHO (see Table 26.18) Renal involvement (e.g. mesangial glomerulonephritis): hematuria, proteinuria, renal insufficiency, acute renal failure

Unusual/rare $

Acute myositis Hepatitis, pancreatitis, ileitis, colitis Aseptic meningitis, encephalitis, bilateral sensorineural hearing loss Other: aortitis, oral aphthae, pharyngitis, pharyngeal edema

Table 26.3 Systemic manifestations of Sweet syndrome5,6. SAPHO, synovitis, acne, pustulosis, hyperostosis and osteitis.  

CRITERIA FOR DIAGNOSIS OF SWEET SYNDROME

Major criteria 1. Abrupt onset of typical cutaneous lesions 2. Histopathology consistent with Sweet syndrome

Minor criteria %

Fig. 26.2 Sweet syndrome. A Scattered edematous pink papules and plaques on the chest. B The edema can be quite marked as seen in these lesions on the upper back. B, Courtesy, Kalman Watsky, MD.  

1. Preceded by one of the associated infections or vaccinations; accompanied by one of the associated malignancies or inflammatory disorders; associated with drug exposure or pregnancy 2. Presence of fever and constitutional signs and symptoms 3. Leukocytosis 4. Excellent response to systemic corticosteroids

Table 26.4 Criteria for diagnosis of Sweet syndrome. Both of the major and two minor criteria are needed for the diagnosis. Reprinted with permission from Cutis.  

An upper respiratory tract infection or flu-like illness frequently precedes the development of the syndrome. Fever occurs in 40–80% of patients and can be intermittent. Extracutaneous involvement is also frequently seen (Fig. 26.4; Table 26.3).

Associated Diseases These are summarized in Table 26.2 and should guide the history, including all medications, physical examination, and focused laboratory evaluation4.

Pathology

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The histopathologic features are contingent upon the type of cutaneous lesion sampled. The characteristic histologic presentation is a diffuse nodular and perivascular neutrophilic infiltrate without evidence of vasculitis (Fig. 26.5), although occasionally leukocytoclastic vasculitis (LCV) can be observed. Leukocytoclasia with endothelial swelling, but without the fibrinoid necrosis that fulfills the criteria for LCV, is the usual finding. Occasionally, the dermal infiltrate may extend into the subcutis, creating a septal or, less frequently, a lobular panniculitis. Isolated neutrophilic panniculitis has been described. In general, epidermal changes are not significant. However, neutrophils occasionally invade the epidermis, producing subcorneal pustules, and they may also infiltrate the adnexa. In the setting of significant edema, there can be epidermal spongiosis and sometimes reticular degeneration as well as intraepidermal and subepidermal vesiculation. Three histologic variants of Sweet syndrome, histiocytoid, lymphocytic and eosinophilic, have been increasingly recognized. The

1986;37:167–174. ©1986, Frontline Medical Communications Inc.

histiocytoid variant is characterized by a dermal, and sometimes subcutaneous, infiltrate composed of histiocyte-like immature myeloid cells11. These cells have myeloperoxidase activity (Fig. 26.6) and must be distinguished from those of leukemia cutis. The lymphocytic variant is often associated with, and sometimes precedes, underlying myelodysplasia12,13. More recently, an eosinophilic variant has been described13a.

Differential Diagnosis Although there are no specific diagnostic findings in this disease, a peripheral leukocytosis with neutrophilia and an elevated ESR and C-reactive protein are frequently seen. In patients with an associated hematologic malignancy or myelodysplasia, there may be a high or low white cell count, lymphocytosis or lymphopenia, and thrombocytosis or thrombocytopenia. Although elevated serum levels of antineutrophil cytoplasmic antibody (ANCA) have been reported14, in particular pANCA or an atypical ANCA, there is no strong evidence that it is a serologic marker for this disease. In 1986, Su and Liu15 proposed two major and four minor criteria for the diagnosis of Sweet syndrome, which have been widely accepted and are shown with minor revisions in Table 26.4. The differential diagnosis of the syndrome depends on the nature and age of the lesions and on the associated disorder (Table 26.5; see Fig. 26.1).

CHAPTER

Neutrophilic Dermatoses

26

%

Fig. 26.3 Sweet syndrome. A The periocular lesion demonstrates how some lesions can mimic cellulitis (pseudocellulitis). This patient also had neutrophilic esophageal ulcerations and subsequently developed colon cancer. B The plaques can have a pseudomammillated appearance due to the associated edema.  

A

Fig. 26.4 Sweet syndrome – ocular involvement. Obvious erythema and hemorrhage involving the sclera and conjunctiva. Courtesy, Kalman Watsky, MD.

Fig. 26.5 Sweet syndrome – histologic features. Mild edema in the papillary dermis and a rather dense dermal infiltrate composed predominantly of neutrophils (inset). Courtesy, Lorenzo Cerroni, MD.

Patients with neutrophilic dermatosis of the dorsal hands develop tender, erythematous to violaceous plaques that may become bullous or ulcerative (Fig. 26.7)16–18. There is a spectrum of associated histologic features, from pustular vasculitis to those of PG or Sweet syndrome. Hence, some authors consider this to be a variant of Sweet syndrome. In patients with hematologic malignancies, especially acute myelo­ genous leukemia, several neutrophilic dermatoses, e.g. Sweet syndrome, atypical (bullous) pyoderma gangrenosum, and neutrophilic eccrine

hidradenitis, can occur alone or in combination. The approach to such a patient is presented in Table 26.6. In patients with rheumatoid arthritis, the possibility of rheumatoid neutrophilic dermatitis, including the uncommon annular variant, needs to be considered18a. As noted in Table 26.5, Sweet syndrome can also mimic soft tissue infections, including cellulitis and necrotizing fasciitis18b,18c. This distinction can prove challenging, especially in immunocompromised hosts.





457

SECTION

Urticarias, Erythemas and Purpuras

4

$

Fig. 26.6 Histiocytoid Sweet syndrome – histologic features. There is edema in the papillary dermis as well as a dermal infiltrate composed of histiocytoid cells admixed with neutrophils, a few eosinophils, and hemorrhage. The histiocytoid cells represent immature myeloid cells and therefore have stained positively for myeloperoxidase (inset). Courtesy, Lorenzo Cerroni, MD.  

THE DIFFERENTIAL DIAGNOSIS OF SWEET SYNDROME

Inflammatory dermatoses Pyoderma gangrenosum (bullous) Neutrophilic dermatosis of the dorsal hands* • Neutrophilic eccrine hidradenitis • Rheumatoid neutrophilic dermatitis (dermatosis) • Other neutrophilic dermatoses (see Fig. 26.1) • Neutrophilic urticaria (e.g. Schnitzler syndrome) • Autoinflammatory diseases (see Tables 45.6 & 45.7) • Periodic fever syndromes (see Table 45.2) • Erythema multiforme • Urticarial vasculitis • Cutaneous small vessel vasculitis • Erythema elevatum diutinum • Granulomatosis with polyangiitis (Wegener granulomatosis) • Behçet disease • Bowel-associated dermatosis–arthritis syndrome • Panniculitis, including erythema nodosum • Halogenoderma (iododerma or bromoderma) • Wells syndrome • Exaggerated arthropod bite reactions • Autoimmune connective tissue diseases – acute, subacute, tumid and neonatal lupus erythematosus • Granulomatous diseases – actinic granuloma, sarcoidosis, inflammatory granuloma annulare, interstitial granulomatous dermatitis • •

Infections Cellulitis, pyoderma, furunculosis Septic vasculitis • Erythema migrans, including disseminated • Cryptococcosis and dimorphic fungal infections • Mycobacterial infections (atypical and leprosy) • Leishmaniasis • •

Neoplasms Lymphoma cutis (T- and B-cell lymphomas including mycosis fungoides, cutaneous angiocentric lymphomas), leukemia cutis • Metastatic carcinoma •

*Some authors consider this a variant of Sweet syndrome. 458

Table 26.5 The differential diagnosis of Sweet syndrome5,6. Entities discussed in this chapter are in italics.  

%

Fig. 26.7 Neutrophilic dermatosis of the dorsal hands. A Clinically and histologically, there is overlap with Sweet syndrome and bullous pyoderma gangrenosum. B More extensive disease is often confused with an infectious process.  

Treatment When limited to the skin, Sweet syndrome is a benign condition which, if left untreated, may persist for weeks or months. Cutaneous lesions then involute spontaneously, rarely leaving scars. However, recurrences develop in ~30% of patients (with or without treatment) and occur even more often in those with hematologic disorders (~50%). Although the initial clinical presentation often suggests sepsis, antibiotics, in general, are ineffective. However, when the disease is associated with a recognized infection, treatment of the underlying infection may result in improvement. The most effective therapy for Sweet syndrome is oral prednisone (0.5–1.0 mg/kg/day) for 2–6 weeks. There is prompt relief of not only the cutaneous, but also the extracutaneous, manifestations. In some patients, prolonged low-dose prednisone for an additional 2–3 months may be necessary to suppress recurrences. When the lesions are few and localized, topical superpotent or intralesional corticosteroids may prove helpful. The major alternative drugs are potassium iodide (900 mg/day; see Table 100.6), dapsone (100–200 mg/day), and colchicine (1.5 mg/day). They can also be used as corticosteroid-sparing agents. Nonsteroidal anti-inflammatory drugs (e.g. indomethacin, naproxen, sulindac), cyclosporine, thalidomide, lenalidomide, anakinra, methotrexate and rituximab have also been reported to lead to improvement of Sweet syndrome. Evidence for any of these therapeutic regimens is based on case reports or small case series. Of note, while TNF inhibitors have been used to treat refractory Sweet syndrome, they can also be a cause of drug-induced Sweet syndrome.

CHAPTER

Sweet syndrome

Atypical (bullous) pyoderma gangrenosum

Painful plaques and nodules with occasional blisters and pustules within lesions

Hemorrhagic bullae and superficial ulcerations

Erythematous edematous plaques and papules which may be painful, infrequent pustules

Favors face, upper extremities and trunk

Favors face and upper extremities (especially dorsal hands)

Favors face, extremities, trunk

Can recur (30–50% of patients)

Can recur

Resolves spontaneously over ~2 weeks without scarring Can recur

Fever, arthralgia or arthritis Multiorgan involvement (Table 26.3) Neutrophilia Elevated ESR

Systemic features usually absent

Fever, neutropenia*

2. Histopathology

Papillary edema with dermal neutrophilic infiltrate Histiocytoid variant – histiocyte-like immature myeloid cells Lymphocytic variant – in the setting of myelodysplasia

Subepidermal hemorrhagic bullae Pustules with neutrophilic dermal infiltrate

Neutrophilic† infiltrate about and within eccrine apparatus, necrosis of eccrine epithelium, and eccrine squamous syringometaplasia

3. Associations

Infections, hematologic malignancies > solid tumors, IBD, autoimmune diseases, pregnancy, G-CSF, all-trans-retinoic acid (see Table 26.2)

Hematologic disorders, especially acute myelogenous leukemia and myelodysplasia, IBD, G-CSF

Leukemia with or without chemotherapy; post-chemotherapy for lymphoma and solid tumors; G-CSF; rarely infections

4. Primary treatment (in addition to treatment of underlying disease)

Systemic corticosteroids (0.5–1 mg/kg/day for 4–6 weeks), potassium iodide (900 mg/day), dapsone (100–200 mg/day), colchicine (1.5 mg/ day) (see Table 26.11)

Systemic corticosteroids (see Table 26.11)

None (spontaneous resolution)

Neutrophilic eccrine hidradenitis

1. Clinical manifestations



a. Cutaneous

b. Systemic

26 Neutrophilic Dermatoses

NEUTROPHILIC DERMATOSES ASSOCIATED WITH HEMATOLOGIC MALIGNANCIES

*† Usually in setting of chemotherapy.

May be lymphocytic in setting of chemotherapy-induced neutropenia.

Table 26.6 Neutrophilic dermatoses associated with hematologic malignancies6,19. G-CSF, granulocyte colony-stimulating factor; IBD, inflammatory bowel disease.  

PYODERMA GANGRENOSUM Key features ■ Four major clinical forms: ulcerative, bullous, pustular, and superficial granulomatous ■ Initial lesion is often a pustule on an erythematous or violaceous base, an erythematous nodule, or a bulla ■ Characteristic lesion is an ulcer with a necrotic undermined border; the base may be purulent or vegetative ■ Histologically, a sterile dermal or adnexal abscess (without a vasculopathy) is seen in active, untreated, expanding lesions ■ Associated illnesses include inflammatory bowel disease, arthritis, monoclonal gammopathies, and other hematologic disorders

Introduction Pyoderma gangrenosum (PG) is an uncommon, chronic, recurrent, cutaneous ulcerative disease with a distinctive morphologic presentation. The laboratory and histopathologic findings can vary and therefore the diagnosis requires clinicopathologic correlation. This neutrophilic dermatosis is frequently associated with systemic disease19–22.

History In 1930, Brunsting, Goeckerman and O’Leary coined the term “pyoderma gangrenosum” and advanced the theory that it had an infectious etiology (streptococci and staphylococci)20.

Epidemiology PG is a global disease. It can occur at any age but most commonly afflicts women between 20 and 50 years of age. Fifty percent of patients have an underlying systemic disease, most commonly inflammatory bowel disease, arthritis or a hematologic disorder (e.g. IgA monoclonal gammopathy, acute myelogenous leukemia, myelodysplasia). Approximately 4% of cases of PG occur in infants and children. PG is also a cutaneous manifestation of several monogenic autoinflammatory diseases (see Tables 45.6 and 45.7).

Pathogenesis Although the disease is idiopathic in 25–50% of patients, an underlying immunologic abnormality is currently favored, given its frequent association with systemic diseases that have a suspected autoimmune pathogenesis. Defects in cell-mediated immunity, neutrophil and monocyte function, and humoral immunity have been reported, but none of these findings have been demonstrated consistently and it is not clear whether they may represent epiphenomena19. Of note, enhanced activity of the IL-1 pathway is thought to play a role in PG, as it does in several autoinflammatory disorders22a. In lesional skin biopsies, overexpression of IL-1, IL-1β, and the IL-1 receptor as well as IL-8, IL-17, and TNF-α has been reported. Elevated serum levels of IL-1β have also been observed, and clinical improvement of PG following administration of the anti-IL-1β antibody canakinumab provides additional support for this proposed pathogenesis (see Ch. 45). The effectiveness of corticosteroids in PG may be related to their ability to reduce the formation of IL-1α and IL-1β. Pathergy, which is a reflection of trivial trauma, not only initiates the cutaneous lesions but also aggravates them, and is seen in 20–30% of patients with PG.

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Clinical Features Although the classic morphologic clinical presentation of PG is an ulcer, there are several variants (bullous, pustular, and superficial granulomatous/vegetative) which differ by their clinical presentation, location, and associated diseases (Table 26.7; Figs 26.8 & 26.9)19. Cutaneous lesions are painful and most frequently occur on the lower extremities in patients with typical (classic) PG, especially the pretibial area (Fig. 26.10A,B,D), but they can occur anywhere (Fig. 26.10C,E), including on mucous membranes and peristomal sites (Fig. 26.11A). The lesions of PG usually begin as a tender papulopustule (Fig. 26.12) with surrounding erythematous or violaceous induration, an erythematous nodule, or a bulla on a violaceous base; the papulopustule may be follicular. All these lesions then undergo necrosis leading to a central shallow or deep ulcer; loss of tissue can expose underlying tendons or muscles. When fully developed, the ulcer has a purulent base with an irregular, undermined and overhanging, gunmetal-colored border which extends centrifugally (see Fig. 26.10A,B). This border may have surrounding erythema. Re-epithelialization occurs from the margins and the ulcers heal with atrophic cribriform pigmented scars (Fig. 26.10F). In PG, the number of ulcers can vary from one to over a dozen, and sometimes they coalesce (Fig. 26.11B). Although the ulcers are

classically described as rapidly expanding, some are less inflammatory and expand rather slowly. The latter require less aggressive therapeutic interventions. In patients with hematologic disorders or in drug-induced cases, the clinical course is often characterized by an acute onset of hemorrhagic or purulent bullous lesions, with a more widespread distribution that can include the dorsal hands. These lesions rapidly necrose and are often associated with fever and signs of toxicity. In those patients with associated inflammatory diseases, such as inflammatory bowel disease or arthritis, the more characteristic presentation is a chronic, slowly enlarging ulcer with excessive granulation tissue in its base and sometimes with evidence of spontaneous regression.

Fig. 26.9 Variants of pyoderma gangrenosum. A Pyostomatitis vegetans in a patient with ulcerative colitis.   B Vegetative form following trauma to the skin.  

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Fig. 26.8 Bullous pyoderma gangrenosum. This patient had ulcerative colitis.

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CLINICAL VARIANTS OF PYODERMA GANGRENOSUM

Vesiculobullous (also referred to as atypical or bullous PG) Lesions favor the face and upper extremities, especially the dorsal hands Clinical appearance overlaps with the superficial bullous variant of Sweet syndrome (Fig. 26.8) • Occurs most commonly in the setting of acute myelogenous leukemia, myelodysplasia, and myeloproliferative disorders such as chronic myelogenous leukemia • •

Pustular Multiple, small, sterile pustules Lesions usually regress without scarring, but can evolve into classic PG • Most commonly observed in patients with inflammatory bowel disease • Similar eruption may be seen in patients with Behçet disease or bowel-associated dermatosis–arthritis syndrome • •

Superficial granulomatous Localized, superficial vegetative or ulcerative lesion52, which favors the trunk and usually follows trauma (e.g. surgery); may have verrucous border Histologically, a superficial granulomatous response with a less intense neutrophilic infiltrate • Responds to less aggressive anti-inflammatory therapy • Controversy as to whether it is a variant of PG, a separate disorder, or related to granulomatosis with polyangiitis (Wegener granulomatosis) • •

Pyoderma/pyostomatitis vegetans Chronic, vegetative pyoderma of the labial and buccal mucosa (Fig. 26.9A) May be associated with vegetative or ulcerative cutaneous PG (Fig. 26.9B) • Large verrucous plaques that may be studded with pustules • Seen in patients with inflammatory bowel disease • •

460

Table 26.7 Clinical variants of pyoderma gangrenosum (PG).  



CHAPTER

26 Neutrophilic Dermatoses

Fig. 26.10 Pyoderma gangrenosum (PG) – clinical presentations. A,B Typical (classic) form in which the ulcer has an undermined and overhanging violet–gray edge as well as a surrounding violaceous border. C Grouped sterile pustular nodules. D Central ulceration surrounded by inflammatory papules and pustules.   E Deeper ulcer with vegetative and pustular base. F Centrally, there is healing with cribriform (sievelike) scarring.

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Clinical variants have been described based on the clinical presentation (see Table 26.7) or the location of the lesion (e.g. genital, peristomal23) or the age of the afflicted21. While the clinical appearance of PG in children is similar to that in adults, the lesions more frequently involve the head and anogenital region24. As with Sweet syndrome, extracutaneous sterile neutrophilic infiltrates have been reported in the bones, lung, liver, pancreas, spleen, kidneys and CNS of patients with PG25.

Associated Diseases Between 50% and 70% of patients with PG have an antecedent, coincident or subsequent associated disease or condition. The most common

associations are inflammatory bowel disease (ulcerative colitis or Crohn disease, 20–30%), arthritis (seronegative arthritis, spondylitis of inflammatory bowel disease or rheumatoid arthritis, 20%), and hematologic disease (in particular, acute > chronic myelogenous leukemia, hairy cell leukemia, myelodysplasia and monoclonal gammopathy, 15–25%). A monoclonal gammopathy is seen in up to 15% of patients and is often composed of IgA. Individuals with the autoinflammatory PAPA (pyogenic [sterile] arthritis, PG and acne) syndrome have been shown to have mutations in PSTPIP1, which encodes a CD2-binding protein, presumably leading to abnormal inflammatory responses (Fig. 26.13). PG-like lesions are also seen in patients with PASH and PAPASH syndromes (see Table 45.6), as well as in primary immunodeficiencies, e.g. leukocyte adhesion deficiency-1 (see Table 60.1). Other neutrophilic

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Fig. 26.13 Pyoderma gangrenosum in a patient with PAPA syndrome. Individuals with this monogenic autoinflammatory disorder have pyogenic sterile arthritis, pyoderma gangrenosum and acne. Courtesy, Maria Chanco Turner, MD.  

Fig. 26.14 Pyoderma gangrenosum. In expanding untreated lesions, a diffuse infiltrate of neutrophils (inset) is present at the edge of an ulceration. Courtesy, Lorenzo  

Cerroni, MD.

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Fig. 26.11 Peristomal and postsurgical pyoderma gangrenosum (PG). A Several ulcers surround an ileostomy in a patient who had a total proctocolectomy performed because of refractory chronic ulcerative colitis.   B Multiple ulcerations of the breasts following breast reduction. Because the original diagnosis postoperatively was soft tissue infection, multiple debridements had been performed and systemic antibiotics administered.  

Fig. 26.12 The earliest clinical lesion in pyoderma gangrenosum is a pustule with an inflammatory base. This patient had Crohn disease.  

dermatoses that have been reported in association with PG are subcorneal pustular dermatosis, Behçet disease, and Sweet syndrome.

Pathology

462

The histopathology of PG can be nonspecific, especially when the disease is partially treated or minimally inflamed, and therefore be non-diagnostic. In early lesions, there is a neutrophilic vascular reaction, which can be folliculocentric. Neutrophilic infiltrates, often with leukocytoclasia, are seen in active, untreated, expanding lesions (Fig. 26.14). In fully developed ulcers, there is marked tissue necrosis with surrounding mononuclear cell infiltrates. In most patients with typical PG, chronic ulcers have fibrosing inflammation at the edge of the ulcer bed. In one study, up to 10% of the patients who fulfilled the

authors’ diagnostic criteria for PG, rather than other entities in the differential diagnosis of PG, had histologic features inconsistent with PG22. This most likely results from a delay in suspecting the diagnosis of PG, with resultant sampling of chronic lesions that have been partially treated.

Differential Diagnosis Since there are no specific or diagnostic laboratory tests or histopathologic features and some of the associated conditions may not have declared themselves, the physician must exclude other causes of cutaneous ulceration and search for a treatable associated disease. PG can be misdiagnosed: of 157 consecutive patients seen at one tertiary care medical center with a referral diagnosis of resistant ulcers due to PG,

CHAPTER

Major criteria 1. Rapida progression of a painfulb, necrolytic cutaneous ulcerc with an irregular, violaceous and undermined border 2. Other causes of cutaneous ulceration have been excludedd

Minor criteria 1. History suggestive of pathergye or clinical finding of cribriform scarring 2. Systemic diseases associated with pyoderma gangrenosumf 3. Histopathologic findings (sterile dermal neutrophilia, ± mixed inflammation, ± lymphocytic vasculitis) 4. Treatment response (rapid response to systemic corticosteroids)g aCharacteristic margin expansion of 1 to 2 cm per day, or a 50% increase in ulcer size

within 1 month.

bPain is usually out of proportion to the size of the ulceration. cTypically preceded by a papule, pustule or bulla. dUsually necessitates skin biopsy and additional evaluation (see Table 26.9) to exclude other

causes (see Table 26.10).

eUlcer development at sites of minor cutaneous trauma. fInflammatory bowel disease, arthritis, IgA gammopathy, or underlying malignancy. gGenerally responds to prednisone (1–2 mg/kg/day) or another corticosteroid at an

equivalent dosage, with a 50% decrease in size within 1 month.

Table 26.8 Proposed diagnostic criteria for classic ulcerative pyoderma gangrenosum. Diagnosis requires both of the major criteria and at least two minor criteria. Adapted from Su WP, Davis MD, Weenig RH, et al. Pyoderma gangrenosum:  

clinicopathologic correlation and proposed diagnostic criteria. Int J Dermatol. 2004;43:790–800.

EVALUATION OF A PATIENT WITH PRESUMED PYODERMA GANGRENOSUM 1. Thorough history and physical examination; review medications 2. Sterile skin biopsy of active skin lesion with sufficient depth (panniculus) and sufficient tissue for special stains, culture and PCR (bacterial, mycobacterial, fungal, viral, and occasionally parasitic). Possibility of future additional biopsies for immunofluorescence studies 3. Gastrointestinal tract studies – stool for occult blood and parasites, colonoscopy, biopsy, radiography, liver function tests and, if indicated, hepatitis evaluation 4. Hematologic studies – complete blood and platelet count, peripheral blood smear, and if indicated, bone marrow examination 5. Serologic studies – serum protein electrophoresis, immunofixation electrophoresis, antinuclear antibodies, antiphospholipid antibodies, ANCA antibodies, VDRL 6. Chest X-ray and urinalysis

Table 26.9 Evaluation of a patient with presumed pyoderma gangrenosum19,22. ANCA, antineutrophil cytoplasmic antibodies.  

15 (approximately 10%) were found not to have PG26. Criteria for the diagnosis of classic PG have been proposed (Table 26.8)27, but to date have not been validated. They basically serve as a guide and no one criterion can be used in isolation because each is seen in multiple disorders. The evaluation of a patient with presumed PG is summarized in Table 26.9. The differential diagnosis clearly depends on the evolutionary stage of the process – the initial inflammatory process characterized by erythematous papules, pustules, plaques and nodules versus the later characteristic vegetative or ulcerative lesions (Table 26.10).

Treatment There is neither specific nor uniformly effective therapy for PG. The nature and intensity of the therapeutic approach depend on the number, size and depth of the lesions, the rate of expansion and appearance of new lesions, the associated disorder, the medical status of the patient, and the risk and patient tolerance of prolonged therapy. The therapeutic goals are to reduce the inflammatory process of the wound in order to promote healing and reduce pain and to control the contributing underlying disease (especially leukemias and inflammatory bowel disease), while producing the least adverse side effects. The standard treatment of PG is local or combined local and systemic corticosteroid therapy,

DIFFERENTIAL DIAGNOSIS OF PYODERMA GANGRENOSUM

Early inflammatory non-ulcerative stage (papules, pustules, plaques or nodules) Follicular infections (folliculitis, furuncle, carbuncle of bacterial, fungal or viral origin) • Cellulitis or soft tissue infection (bacterial, mycobacterial or fungal origin) • Insect bite reaction • Cutaneous T- and B-cell lymphomas • Halogenoderma (iododerma or bromoderma) • Panniculitides (inflammatory, infectious, metabolic, neoplastic) • Cutaneous polyarteritis nodosa • Sweet syndrome (see Table 26.5 for additional entities) • Behçet disease • Bowel-associated dermatosis–arthritis syndrome •

26 Neutrophilic Dermatoses

PROPOSED DIAGNOSTIC CRITERIA FOR CLASSIC ULCERATIVE PYODERMA GANGRENOSUM

Later ulcerative or vegetative stage Infections – streptococcal synergistic gangrene, ecthyma gangrenosum, atypical and typical mycobacterial infections, cutaneous lesions of the deep mycoses (e.g. blastomycosis, coccidioidomycosis, paracoccidioidomycosis, chromomycosis), botryomycosis, gummatous treponemal ulcers • Parasitic infections – leishmaniasis, amebiasis, schistosomiasis • Vascular diseases – ulcerations due to venous hypertension, arterial insufficiency, non-septic emboli, hemoglobinopathies, or thrombosis (secondary to hypercoagulability; see Ch. 105) • Vasculitis – cutaneous polyarteritis nodosa, microscopic polyangiitis, granulomatous vasculitides (granulomatosis with polyangiitis [Wegener granulomatosis], Churg–Strauss syndrome, temporal arteritis), autoimmune connective tissue disease (systemic lupus erythematosus, rheumatoid arthritis), Behçet disease • Malignancy – squamous cell carcinoma, basal cell carcinoma, cutaneous T- and B-cell lymphoma • Miscellaneous – brown recluse spider bite, ulcerative necrobiosis lipoidica, pemphigus vegetans of the Hallopeau or Neumann type, blastomycosis-like pyoderma*, non-healing surgical wound, factitious ulcers, ulcers in patients with primary immunodeficiencies (e.g. leukocyte adhesion deficiency-1; see Table 60.1) •

*Growth of at least one pathogenic bacteria from culture of tissue. Table 26.10 Differential diagnosis of pyoderma gangrenosum (PG)19,22. In a series of 95 patients misdiagnosed with PG, the most common etiologies were vascular (venous or arterial; 28), vasculitis (21), malignancy (16), infection (14), and drug-induced or exogenous tissue injury (13)26.  

with or without adjunctive systemic therapy28; based upon an evidencebased review, cyclosporine is also considered first-line therapy29. Systemic corticosteroids have generally been the most predictable and effective medication when delivered in adequate dosage. Unfortunately, the more resistant lesions require more protracted therapy (>3 months) at a higher than desirable dosage, thus inviting adverse side effects. Such patients should be closely monitored and should receive supplemental calcium (1500 mg/day), vitamin D (800 IU/day) and, in most instances, bisphosphonates (see Ch. 125). Additional therapies, e.g. systemic calcineurin inhibitors, TNF-α inhibitors, are outlined in Table 26.1128,30.

BEHÇET DISEASE Key features ■ A multisystem, polysymptomatic disease ■ Diagnosis is based on International Study Group criteria of recurrent oral ulceration, recurrent genital ulceration, ocular abnormalities (e.g. uveitis, retinal vasculitis), and cutaneous lesions ■ Cutaneous findings range from sterile papulopustules and palpable purpura to erythema nodosum-like lesions ■ Histologically, a neutrophilic angiocentric infiltrate with leukocytoclastic (early) or lymphocytic (late) vasculitis is the characteristic finding

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THERAPEUTIC LADDER FOR THE TREATMENT OF PYODERMA GANGRENOSUM

Treatment

Dose

Level of evidence

Inflammatory disease Mild disease and/or adjunctive therapy Superpotent topical corticosteroids

3

Intralesional corticosteroids

2

Topical tacrolimus

2

Oral antibiotics (e.g. sulfonamides, minocycline)

2

Colchicine

0.6 mg po thrice daily

3

Dapsone

50–150 mg po daily

3

Combination colchicine/dapsone

3

Other (e.g. oral potassium iodide, intralesional cyclosporine, topical timolol, topical cromolyn sodium, nicotine patch or cream)

3

More severe disease Prednisone

0.5–1 mg/kg/day

2

Methylprednisolone

1 g daily for 3–5 days (IV pulse)*

3

Thalidomide†

50–150 mg po nightly

2

Cyclosporine

2.5–5 mg/kg po daily

2

Tacrolimus

0.1–0.2 mg/kg po daily

3

TNF-α inhibitors‡

Infliximab 5 mg/kg IV at weeks 0, 2 and 6; adalimumab 80 mg sc as initial dose then 40 mg sc weekly or every other week; etanercept 50–100 mg sc weekly (in 1 or 2 doses)

1 (infliximab§); 3 (adalimumab); 3 (etanercept)

IL-12/23 antagonists

Ustekinumab 45–90 mg sc

3

Interleukin (IL)-1, IL-1R antagonists

Anakinra, canakinumab

3

Methotrexate¶

2.5–25 mg po, sc or IM weekly

3

Azathioprine¶

50–100 mg po twice daily

3

Mycophenolate mofetil¶

1–1.5 g po twice daily

3

Cyclophosphamide

Variable oral (50–200 g daily) or IV pulse (500–1000 mg monthly) dosing

3

Chlorambucil

4–6 mg po daily

3

IVIg

2–3 g/kg IV monthly (given over 2–5 consecutive days)

3

Granulocyte apheresis, plasmapheresis

3

Total colectomy (severe chronic ulcerative colitis)

3

Non-inflammatory disease Bio-occlusive dressings Compression, limb elevation

• •

*† Followed by daily oral prednisone.

Especially in patients with Behçet disease.

‡Especially in patients with inflammatory bowel disease. §50–70% response rate. ¶Often used in combination with other agents or as maintenance therapy.

Table 26.11 Therapeutic ladder for the treatment of pyoderma gangrenosum28,30. In the future, antiinterleukin (IL)-17 and anti-IL-17R antibodies may be tried. Key to evidence-based support: (1) prospective controlled trial; (2) retrospective study or large case series; (3) small case series or individual case reports.  

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Behçet disease is a multisystem, polysymptomatic disease with unpredictable exacerbations and remissions31–34. All organs of the body can be affected concomitantly or consecutively. As a result, all subspecialties can be involved in the care of these patients.

History In the fifth century BC, Hippocrates first described the symptomatology of this disease, and in 1936, Behçet reported a patient with eye disease and orogenital ulcers.

Epidemiology Most patients are from regions along the ancient Silk Route, which stretched from the Korean peninsula and Japan to the Mediterranean Sea. Turkey has the highest prevalence, at 80 per 100 000. In Japan, it is 10 per 100 000; in the UK, 0.64 per 100 000; and in the US, 0.12 per 100 00032. In Japan and Korea, the incidence of Behçet disease is greater in women, but in Middle Eastern countries it is seen more frequently in men. The peak incidence is between 20 and 35 years of age. The familial form usually comprises 2–5% of cases, except in the Middle East, where it represents 10–15%.

Pathogenesis Epidemiologic evidence suggests that genetic and environmental factors contribute to the development of this disease. More than 80% of Asian patients have the HLA-B51 allele, but it is present in only about 15% of Caucasians from Western countries; thus, the allele appears to be an important risk factor for those who live along the Silk Route. Earlier theories of pathogenesis entertained the possibility of an infectious etiology (viral or bacterial), but subsequent evidence failed to substantiate this hypothesis. Among the infectious agents investigated were HSV, hepatitis C virus, parvovirus B19, and streptococci32. These

infections may potentially trigger an immunoregulatory defect in a genetically predisposed individual. The pathomechanisms of Behçet disease involve vascular injuries and autoimmune responses. Circulating immune complexes and neutrophils appear to be responsible for the mucocutaneous lesions that are characterized histologically by a neutrophilic vascular reaction or even leukocytoclastic vasculitis. The neutrophils of Behçet disease produce an increased amount of superoxides and an excess of lysosomal enzymes, and they have enhanced chemotaxis, all of which lead to tissue injury. The elevated circulating levels of TNF-α, IL-1β and IL-8 may result in activation of neutrophils and augmentation of cellular interactions between neutrophils and endothelial cells. Clonal expansion of autoreactive T cells that recognize a peptide derived from heat shock protein 60 has also been described. Recent genome-wide association studies found that single nucleotide polymorphisms in IL-10 and IL-23R regions were associated with the disease.

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26 Neutrophilic Dermatoses

Introduction

Clinical Features and Differential Diagnosis Mucocutaneous involvement Aphthous stomatitis, the major criterion, is frequently the first symptom of Behçet disease (65–70% of patients), and it is almost always present during the course of the disease. The aphthosis may precede the other manifestations by many years, but a dramatic increase in severity often occurs in concert with the onset of other features. Oral ulcers begin as an erythematous papule, which develops a yellowish pseudomembrane and then forms a painful usually non-scarring ulcer (Fig. 26.15A,B), which heals over a period of weeks. The ulcers are indistinguishable from those that occur with complex aphthosis or inflammatory bowel disease and they must be differentiated from other causes of oral ulcers, e.g. pemphigus vulgaris, Marshall syndrome. The latter patients also have periodic fevers, pharyngitis, and cervical adenitis35. The genital aphthae involve primarily the scrotum and penis in men and the vulva in women. Compared to oral lesions, the anogenital

Fig. 26.15 Behçet disease – mucocutaneous lesions. A, B Oral aphthosis involving the tongue and lip; the ulcerations can be deep. These ulcers may be diagnosed as infectious (e.g. due to herpes simplex virus) or neoplastic rather than inflammatory. C Aphthae of the vulva and inguinal region. D Pathergy – a papulopustule appeared at the site of insertion of an intravenous cathether.  

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aphthae tend to be larger with irregular margins, but can vary in size (Fig. 26.15C); they are more painful. Distinction of genital lesions from lesions of HSV requires viral culture, direct fluorescent antibody stain, or PCR. Among the primary cutaneous lesions are acral and facial sterile vesiculopustules as well as pustular and/or purpuric papules36. Although the papulopustular lesions are usually not folliculocentric, they have nonetheless been described as acneiform, leading to some confusion (see Pathology below). The panniculitic erythema nodosum-like lesions favor women and appear on their legs and buttocks, and less often on the face and neck; they have to be differentiated from both superficial thrombophlebitis (which occurs in 30% of patients with Behçet disease) and erythema nodosum (which can develop in patients with Behçet disease). Pathergy also occurs (Fig. 26.15D), as in pyoderma gangrenosum. Patients with features of both Behçet disease and relapsing polychondritis have been described and reported as MAGIC (mouth and genital ulcers with inflamed cartilage) syndrome (see Ch. 45)37.

Systemic involvement Systemic manifestations are summarized in Table 26.12 and distinctions between Behçet disease with bowel involvement and inflammatory bowel disease are outlined in Table 26.13.

Pathology The histopathology of the cutaneous lesions (especially the acneiform lesions) is an area of controversy, perhaps due in part to the age of the lesion sampled. The cutaneous vasculopathy of Behçet disease can involve all sizes of blood vessels, both arterial and venous, within the dermis and subcutis. It can present as a neutrophilic vascular reaction characterized by angiocentric, neutrophilic infiltrates with leukocytoclasia and erythrocyte extravasation, or as a leukocytoclastic vasculitis with or without mural thrombosis and necrosis; some authors suggest that the vasculitis may be secondary to the intense inflammation observed38. There may be a predominance of histiocytes associated with the vasculitis, which leads to the diagnosis of granulomatous vasculitis. An angiocentric lymphocytic infiltrate characterizes older lesions. With regard to the acneiform lesions, a sterile neutrophilic vasculopathy is now favored over a suppurative or mixed suppurative and granulomatous folliculitis. Vascular thrombosis is not infrequent and should prompt investigation for an underlying coagulopathy. The histologic features of the erythema nodosum-like lesions can vary from a neutrophilic lobular panniculitis to a septal and lobular panniculitis with a mixed inflammatory infiltrate, fat necrosis and evidence of lymphocytic vasculitis; the above vascular changes may also be seen.

Diagnosis Since Behçet disease has no diagnostic test and is characterized by a complex constellation of signs and symptoms, various sets of clinical criteria have been created to assist in the diagnosis. Among the reported diagnostic criteria are those of the Japanese (1974), O’Duffy (1974), Zhang (1980), James (1986), and the International Study Group (ISG; 1990)39. The latter are presented in Table 26.14. The development of the ISG criteria was based on the discriminating performance of various criteria-grouped combination sets, and the ISG criteria exhibited the highest sensitivity, specificity, and relative value. Controversy exists, however, about the failure of these criteria to require exclusion of inflammatory bowel disease.

Treatment The management of the disease is difficult because of its variable course and the lack of sufficient double-blind studies. The therapeutic approach is a symptomatic one and is dictated by the nature of the mucocutaneous and visceral involvement. Because of the frequent vital organ involvement, e.g. the eye, and the tendency for the disease to recur, early and aggressive treatment is vital. CNS and large artery and vein involvement respond less favorably to therapy. There are multiple drugs available, both topical and systemic, that can be used as monotherapy or as combination therapy (Table 26.15)40–42. Evidence for many of the therapies is based on case-series data.

BOWEL-ASSOCIATED DERMATOSIS–ARTHRITIS SYNDROME Synonyms:  ■ Bowel bypass syndrome ■ Bowel bypass syndrome

without bowel bypass ■ Intestinal bypass arthritis–dermatitis syndrome

Key features ■ Constitutional signs and symptoms are serum sickness-like ■ Cutaneous lesions include erythematous and purpuric papules and vesiculopustules as well as nodular panniculitis ■ Associated polyarthritis and tenosynovitis ■ Histopathology includes dermal perivascular nodular neutrophilic infiltrates and edema as well as a lobular neutrophilic or septal panniculitis

SYSTEMIC MANIFESTATIONS OF BEHÇET DISEASE

Ocular (leading cause of morbidity)31,33,34

Neurologic



Occurs in 90% of patients; favors men, in whom it is more severe Can be painful and may lead to blindness • Retinal vasculitis (more frequently associated with blindness) • Posterior uveitis (most characteristic ocular finding) • Anterior uveitis (Fig. 26.16), hypopyon • Secondary glaucoma, cataracts • Conjunctivitis, scleritis, keratitis, vitreous hemorrhage, optic neuritis







Joints

Vascular



Approximately 50% of patients develop arthritis In majority (~80% of patients), duration of attacks is 300 g during the pregnancy, mild to moderate CS are recommended over potent CS • If potent CS are required, the treatment period should be limited in duration • Can add to risk of developing striae

Systemic



Prednisolone is the systemic corticosteroid of choice for dermatologic indications as it is largely inactivated in the placenta (mother : fetus = 10 : 1) • During the first trimester, particularly between weeks 8 and 11, there is a possible (debated) slightly increased risk of cleft lip/cleft palate, especially if high doses prescribed and for >10 days; during this same period, a longer duration of therapy appears safe if dosages are 11 µmol/l in a pregnant woman; normal range in non-pregnant women, 0–6 µmol/l). Levels may range from 3 to 100 times normal. During pregnancy, alkaline phosphatase levels typically increase (placental origin) even in the absence of ICP, and γ-glutamyl transferase levels are usually lower than in the non-pregnant state. Serum levels of transaminases are usually elevated in those with ICP, but may be normal in 30% of patients21. In women with jaundice, conjugated (direct) bilirubin levels are increased and the prothrombin time may be prolonged. Hepatic ultrasonography generally is normal but may reveal gallstones in jaundiced patients, who are at increased risk for their development.

Atopic eruption of pregnancy (AEP) is defined as either an exacerbation or the first occurrence of eczematous and/or papular skin changes during pregnancy in atopic individuals. As the majority of patients belong to the second group, the atopic link is often overlooked, leading to a number of different diagnoses, as evidenced by the many synonyms.

Differential Diagnosis In the absence of primary lesions, the clinical differential diagnosis includes other causes of primary pruritus (see Ch. 6), including those that lead to cholestatic pruritus. Viral hepatitis is a common disorder and should be excluded by appropriate serologies. Of note, a history of hepatitis C viral infection is considered a risk factor for the development of ICP, and in one study, 20% of the women who were HCV RNA-positive developed ICP22.

Treatment Since fetal prognosis correlates with disease severity, the therapeutic goal is reduction of serum bile acid levels. This allows prolongation of the pregnancy and lessens both fetal risk and maternal symptoms. To date, the only successful agent has been oral ursodeoxycholic acid (UDCA)18,21,23,24. It is a naturally occurring, hydrophilic, non-toxic bile acid that has been used for a variety of cholestatic liver diseases. Although the exact mechanism of action in ICP is still not fully understood, there is evidence that UDCA corrects the maternal serum bile acid profile, decreases the passage of maternal bile acids to the fetoplacental unit, and improves the function of the bile acid transport system across the trophoblast. UDCA is safe for mother and fetus, with its only side effect being mild diarrhea. Use of UDCA for ICP is off-label as it is only approved for primary biliary cirrhosis. The recommended oral dose is 15 mg/kg daily or, independent of body weight, 1 g daily. It should be started as early as possible and administered until delivery. The use of S-adenosylmethionine, dexamethasone, epomediol, silymarin, phenobarbital or activated charcoal is not recommended as none have been shown to decrease fetal risk. Cholestyramine is contraindicated as it can further reduce vitamin K absorption and increase the risk of bleeding24. In jaundiced patients, the prothrombin time should be monitored, and intramuscular vitamin K administered as necessary. Close interdisciplinary collaboration with the obstetrician is essential and close monitoring of the fetus is recommended.

History In retrospect, an association with atopy dates back to the first reports. When Besnier described the disorder “prurigo gestationis” in 1904, “prurigo” was the term dermatologists used for atopic dermatitis (Besnier was the first to note the association between atopic dermatitis, allergic rhinitis, and asthma). Nurse, in 1968, described accompanying eczematous features in most of the 31 patients in his “early-onset” prurigo group. In 1983, Holmes and Black were the first to suggest that “prurigo of pregnancy” could simply result from pregnancy-related pruritus in women with an atopic diathesis rather than being a distinct entity3.

Epidemiology AEP is by far the most common pruritic disorder in pregnant women and it tends to appear earlier than the other pregnancy-related dermatoses1. Its incidence is not known but may be as high as 1 in 5 to 1 in 20.

Pathogenesis To prevent fetal rejection, a normal pregnancy is characterized by a lack of strong maternal cell-mediated immune function and reduced Th1 cytokine production (e.g. IL-12, interferon-γ) as well as a dominant humoral immune response with increased Th2 cytokine production (e.g. IL-4, IL-10). This natural switch towards a dominant Th2 response, which worsens the imbalance already present in most atopic patients, is thought to favor the development of AEP1. Fig. 27.8  Atopic eruption of pregnancy – eczematous lesions. The eczematous lesions often involve flexural areas and friction sites (A,B), as well as the breasts and abdomen (B). These changes are seen in approximately two-thirds of patients.

ATOPIC ERUPTION OF PREGNANCY A

Synonyms:  ■ Prurigo of pregnancy ■ Besnier’s “prurigo gestationis”

Nurse’s “early-onset prurigo” of pregnancy ■ Spangler’s “papular dermatitis of pregnancy” ■ Pruritic folliculitis of pregnancy ■ Eczema in pregnancy ■

Key features

478

■ Eczematous and/or papular skin lesions in a patient with an atopic diathesis in whom other specific dermatoses have been excluded ■ Most common pruritic disorder during pregnancy ■ Generally appears earlier than other pregnancy-related dermatoses (75% before the third trimester) ■ Nonspecific histology; negative direct IF; elevated serum IgE levels in up to 70% of patients ■ No maternal or fetal risks; commonly recurs in subsequent pregnancies

B

Two-thirds of patients present with eczematous lesions (Fig. 27.8), often involving “atopic sites” such as the face, neck, and flexural aspects of the extremities. One-third develop a papular eruption on the trunk and extremities, composed of either classic prurigo lesions or small erythematous papules (Fig. 27.9). Findings typically include xerosis (often marked) and other signs of the underlying atopic diathesis (see

In contrast to the other specific dermatoses of pregnancy, AEP appears earlier, often during the first trimester, with 75% of patients presenting before the third trimester. Approximately 20% of women experience an exacerbation of pre-existing atopic dermatitis, while the remaining 80% develop atopic skin changes for the first time during pregnancy.

A

CHAPTER

27 Pregnancy Dermatoses

Clinical Features

B

Fig. 27.9  Atopic eruption of pregnancy – papular eruption. Scattered small erythematous papules (A) or excoriated prurigo lesions (B) favor the abdomen and extremities. These changes are seen in approximately one-third of patients. Note the absence of striae distensae. Fig. 27.10  Approach to the pregnant woman with pruritus1. Patients with refractory pemphigoid gestationis may benefit from plasmapheresis during pregnancy. See Table 27.3 for special considerations regarding the use of corticosteroids (topical and oral) and antihistamines during pregnancy.

APPROACH TO THE PREGNANT WOMAN WITH PRURITUS Pregnant woman with pruritus



+ Primary skin lesions

Related to pregnancy

Intrahepatic cholestasis of pregnancy

+

Only secondary skin lesions due to scratching (excoriations/prurigo)

− Other primary dermatoses

DIF: nonspecific H&E: nonspecific LAB: elevated total serum bile acid levels Prematurity, fetal distress, stillbirths

Early onset (90%

Rare

None

HLA-DQ2

>90%

30%

Normal (20%)

Dapsone responsiveness

Excellent

Good, may also require systemic corticosteroids

Minimal to moderate

^Patients should be warned that arterial desaturation may be noted by pulse oximetry, even

with relatively low levels of methemoglobinemia.

*In decreasing order of frequency.

Table 31.4 Side effects of dapsone. SJS, Stevens–Johnson syndrome; TEN, toxic epidermal necrolysis.  

Table 31.3 Characteristics that differentiate dermatitis herpetiformis (DH), linear IgA bullous dermatosis (LABD), and bullous pemphigoid (BP). BMZ, basement membrane zone; IF, immunofluorescence.  

Treatment

532

The treatment of DH includes dapsone and a gluten-free diet, as well as a combination of the two therapies. The pruritus of DH is relieved within 48–72 hours of instituting dapsone (4′,4′ diamino-diphenyl sulfone). The lesions abruptly recur within 24–48 hours of discontinuation of therapy. Unfortunately, dapsone has no effect on the intestinal pathology. Dapsone is begun after screening for glucose-6-phosphate dehydrogenase (G6PD) deficiency, with initial dosages of 25–50 mg in adults and 0.5 mg/kg in children. Initiation of therapy with higher doses may precipitate severe hemolysis and cardiac decompensation in susceptible individuals. The average maintenance dose in adults on a normal diet is 100 mg daily. The half-life ranges from 12 to 24 hours, so divided doses are seldom of benefit. The daily dose can be regulated on a weekly basis to optimize control. One to two new lesions per week should be expected on the optimal dose. Higher doses simply increase toxicity with little benefit. Outbreaks of facial and scalp lesions while on otherwise adequate treatment can occur, but are not common. Facial disease may prove refractory to dapsone therapy. Breaking the vesicles followed by application of a potent corticosteroid gel may be helpful. Although there are many side effects of dapsone (Table 31.4), the drug is well tolerated for years in more than 90% of patients (see Ch. 130). Hemolysis occurs in virtually every patient on dapsone therapy, since sulfones produce an oxidant stress on aging red blood cells. In patients with G6PD deficiency, dapsone may produce severe hemolysis. Although most patients have evidence of drug-induced hemolysis, a compensated hemolytic anemia does develop. Drug-induced hemolysis can be confirmed and followed by a reticulocyte count, which should show

increased erythropoiesis. Of note, dapsone is secreted in breast milk and may cause hemolytic anemia in breastfed infants. In the setting of a persistent severe anemia, a search for contributing causes, such as iron, vitamin B12 or folate deficiencies or hereditary spherocytosis, should be performed. Methemoglobin is present in the blood of most patients taking 100 mg of dapsone daily. Although the amount of methemoglobin usually does not exceed 5%, there are patients who have maintained levels between 10% and 15%. Methemoglobinemia in the absence of cardiopulmonary symptoms does not require alteration of dapsone dose. Patients should be warned that arterial desaturation may be noted by pulse oximetry, even with relatively low levels of methemoglobinemia. Fatal agranulocytosis has developed in patients with DH treated with dapsone. This drug-induced agranulocytosis usually occurs after 2–12 weeks of continuous dapsone treatment. A hypersensitivity reaction involving the formation of leukocyte agglutinins seems to be the underlying mechanism. Re-administration of dapsone then causes leuko­ penia within hours. A simple measure is to warn the patient to discontinue the drug and report immediately if fever, a sore throat, or other signs of infection develop. Dapsone hypersensitivity syndrome (see Ch. 21) is a rare, but potentially severe, reaction, characterized by fever, a cutaneous eruption and internal organ involvement, which is usually seen 2–7 weeks after initiation of therapy. The cutaneous manifestations vary from a morbilliform eruption to exfoliative dermatitis, while the systemic manifestations include fever, pruritus, lymphadenopathy, hepatitis, an elevated ESR, leukocytosis, and, rarely, eosinophilia20. Patients should be educated about this syndrome and instructed to discontinue therapy and notify their medical provider if any signs or symptoms of the dapsone hypersensitivity syndrome develop. Peripheral neuropathy induced by dapsone may occur as early as during the first 4 months of therapy. Indeed, neuropathic signs can develop within the first few weeks of therapy. The neuropathy was initially reported as a pure motor neuropathy (involving primarily distal extremity muscles); however, pure motor, pure sensory, and combined motor and sensory neuropathies have subsequently been reported. Relatively high daily doses of dapsone (200–500 mg) and high cumulative doses in the range of 25 to 500 g have been implicated.

CHAPTER

31 Dermatitis Herpetiformis and Linear IgA Bullous Dermatosis

If patients are intolerant to dapsone, therapy with sulfapyridine should be considered. The initial dose of sulfapyridine is usually 500 mg three times a day and it can be safely increased to 2 g three times a day; however, some patients may not respond to sulfapyridine at any dose. Adequate fluid intake and alkalinization of the urine minimizes the risk of nephrolithiasis. Dapsone therapy monitoring includes a baseline complete blood count (CBC) and liver function tests, then weekly CBCs for the first month, monthly CBCs for the next 5 months, and semiannual CBCs thereafter while the patient remains on therapy. Liver function tests should be repeated at 6 months and annually thereafter. Some clinicians measure baseline G6PD activity in all patients, while others focus on those of African, Asian or southern Mediterranean ancestry. Sulfapyridine produces less hemolytic anemia, but the potential for agranulocytosis does exist. Consequently, similar monitoring is recommended for chronic sulfapyridine therapy. Patients can also be treated with a gluten-free diet (which includes corn, rice, and oats). Because several months of gluten-free diet therapy are needed for a response, concurrent suppression of symptoms with dapsone is usually necessary. Most patients with granular IgA deposits respond to a strict gluten-free diet such that they can either decrease or eliminate their need for dapsone. With a prolonged gluten-free diet, IgA in the skin decreases and eventually disappears, but with the reintroduction of gluten, IgA deposits and skin disease return. In addition, minor fluctuations in disease severity are most likely related to oral gluten intake. The gluten-free diet is inconvenient and unacceptable to some patients.

Patient Support The Gluten Intolerance Group and the Celiac Disease Foundation (www.celiac.org) offer information on acceptable foods as well as foods and additives that should be avoided. The former patient support group has a Quick Start Gluten-Free Diet Guide that may be useful for patients. Their website is www.gluten.org.

LINEAR IgA BULLOUS DERMATOSIS

Fig. 31.7 Linear IgA bullous dermatosis. Characteristic findings in this child include the annular array of bullae (inset) and involvement of the genital region. There are also tense bullae arising on normal-appearing skin with either clear or hemorrhagic fluid and annular bullae with central crusting. Courtesy,  

Antonio Torello, MD.

Synonyms:  Adults: ■ Linear IgA dermatosis (LAD) ■ Linear IgA

Fig. 31.8 Linear IgA bullous dermatosis – direct immunofluorescence. A linear pattern of IgA deposition is present within perilesional

disease of adults ■ Linear IgA disease ■ Linear IgA dermatitis herpetiformis ■ Linear dermatitis herpetiformis ■ Adult linear IgA disease ■ IgA bullous pemphigoid ■ Pemphigoid linear IgA



Children: ■ Chronic bullous disease of childhood ■ Benign chronic bullous dermatosis of childhood ■ Childhood linear IgA dermatitis herpetiformis ■ Linear IgA disease of childhood

Introduction LABD is an immune-mediated, subepidermal, vesiculobullous eruption that occurs in both adults and children. It has been defined on the basis of a unique immunopathology consisting of linear deposition of IgA along the cutaneous BMZ. In adults, the clinical findings associated with this immunopathologic pattern may resemble those of DH or bullous pemphigoid (BP) (see Table 31.3), but in children, the cutaneous features may be clinically unique. The childhood form is most frequently termed “chronic bullous disease of childhood” (CBDC). It is a subepidermal vesiculobullous disease that was initially described on the basis of its clinical findings – annular erythema and blisters (often referred to as a “crown of jewels”), which developed predominantly in flexural areas, particularly the lower trunk, thigh and groin, in preschool children (Fig. 31.7). However, it is invariably characterized by the linear deposition of IgA along the BMZ (Fig. 31.8) as well as circulating antibodies against the same BMZ antigens described in the adult form21. Based upon the site of IgA deposition as determined by immunoelectron microscopy, there are at least two distinct types of LABD: a lamina lucida type (majority) and a sublamina densa type. In adults, LABD is frequently drug-induced.

History In 1969, it was noted that patients with vesiculobullous lesions and the histologic findings of DH could have linear rather than granular deposits of IgA along the epidermal BMZ22. In 1975, Chorzelski and Jablonska23 first suggested that LABD was a separate entity based on its immunopathologic findings. Subsequently, there has been general agreement that LABD is a distinct disease entity24,25. In 1970, Jordon et al.26 first proposed the name “benign chronic bullous dermatosis of childhood”. Subsequent investigators, using

533

SECTION

Vesiculobullous Diseases

5

antisera specific for IgA, identified the characteristic linear IgA deposition along the epidermal BMZ in children with CBDC27. On a molecular basis, CBDC is the same disease as LABD in that the circulating IgA antibody found in the serum of patients with CBDC binds to the same 97 kDa proteolytic fragment of BP180 antigen described in adults with LABD21.

Epidemiology The true incidence of LABD is unknown. The annual incidence in southern England has been estimated to be 1 in 250 000. The incidence in the US has not been reported, but we have estimated the prevalence of LABD in Utah to be 0.6 per 100 000 adults. In adults, the average age of onset of LABD is over 60 years of age24. There appears to be a slight female preponderance, although this has not been observed in all series24,28. Childhood LABD occurs at a mean age of 4.5 years28–30.

Pathogenesis Both BP and the lamina lucida type of LABD have lamina lucida deposition of immunoglobulin and are associated with BMZ vesiculation. However, the antigenic specificity differs. In BP, the pathogenic IgG antibodies bind the MCW-1 region of the NC16 domain of BP antigen 2 (BPAG2; BP180), whereas the epitopes that have stimulated an IgA response in LABD are more toward the carboxy terminus of the same molecule (Fig. 31.9). In adult and childhood LABD patients, this IgA antibody was initially found, on immunoblot, to react against a 97 kDa antigen in an epidermal extract31. Subsequently, the 97 kDa antigen was found to represent a cleaved ectodomain of BPAG2, referred to as LABD97 (see Fig. 31.9). Why BP antibodies should react predominantly with antigens near the transmembrane portion of BPAG2 and LABD antibodies react with cleaved epitopes near or within the collagenous domain is unclear32. IgA class antibodies from patients with the sublamina densa type of LABD have been reported to bind to type VII collagen within anchoring fibrils33,34. However, in a series of 10 sera from such patients, this was not substantiated (authors’ observations). Currently, the antigenic specificity of these sublamina densa-binding antibodies is not known. There have been reports in the literature of the association of LABD with various disorders such as gastrointestinal diseases, autoimmune diseases, malignancies, and infections (see below). The significance of these associations has yet to be determined, but they may play a role in the initial stimulation of the IgA mucosal immune system. The incidence of gluten-sensitive enteropathy in LABD has been reported in the literature to range from 0 to 24%23,25,35. Leonard et al.35 noted that two of six patients with LABD had gluten-sensitive enteropathy, and two of six patients’ skin lesions improved on a gluten-free diet; however, none of the patients completely cleared. In contrast, Lawley et al.25 found no histologic evidence of gluten-sensitive enteropathy in the six patients they studied. LABD clearly has a much lower prevalence of small bowel histologic abnormalities than does DH.

Ulcerative colitis, Crohn disease, and gastric hypochlorhydria have also been described in association with LABD24,36. LABD associated with ulcerative colitis was reported to remit after colectomy37. Data on the association of autoimmune diseases with LABD are not sufficient to allow statistical analysis of prevalence. However, there are reports in the literature of the association of systemic lupus erythematosus and dermatomyositis with LABD, as well as thyrotoxicosis, autoimmune hemolytic anemia, rheumatoid arthritis, and one case of glomerulonephritis23,38,39. An association between LABD and malignancy has also been described. Tumors that have been reported in patients with LABD include: B-cell lymphoma, chronic lymphocytic leukemia, and carcinoma of the bladder, thyroid, colon and esophagus; single case reports of plasmacytoma, hydatiform mole, renal cell carcinoma and ocular melanoma have also been described24,40–44. In addition, LABD has been reported to be associated with several infections, including varicella zoster virus, antibiotic-treated tetanus, and upper respiratory infections. It has been postulated that the infectious agent may have triggered an immune response44–46. There are multiple reports of drug-induced LABD; the drugs associated with LABD are listed in Table 31.5, with vancomycin being the most common inducer (Fig. 31.10)47,48. It is possible that these medications may stimulate the immune system to produce an IgA class antibody in a predisposed individual. Drug-induced LABD usually remits within 2–6 weeks of cessation of the drug. However, some cases have persisted for months48.

Clinical Features Clinical manifestations in LABD are variable and patients can present with findings suggestive of DH as well as subepidermal tense bullae that are often indistinguishable from BP (Fig. 31.11). However, the vesiculobullous lesions often appear in a herpetiform arrangement on erythematous and/or normal-appearing skin (Fig. 31.12). Some patients present with expanding annular plaques (Fig. 31.13), while others have lesions that are scattered and asymmetric24. An isomorphic response, including lesions appearing at previous sites of adhesive tape, has been reported. LABD may present as a variant of mucous membrane (cicatricial) pemphigoid, with oral, nasal, pharyngeal, and esophageal lesions.

DRUG-INDUCED LINEAR IgA BULLOUS DERMATOSIS

Common Vancomycin*



Less common Penicillins Cephalosporins • Captopril > other ACE inhibitors • NSAIDs: diclofenac, naproxen, oxaprozin, piroxicam • •

Uncommon

CLEAVAGE ECTODOMAINS OF BPAG2

Phenytoin Sulfonamide antibiotics: sulfamethoxazole, sulfisoxazole

• •

NH2

TM

COOH

BP180

NC16A

49

56

MCW-1

BP NC MCW-1 LABD97

534

LABD97

bullous pemphigoid = collagenous domain non-collagenous epitope that autoantibodies bind in BP cleaved ectodomain that autoantibodies bind in linear IgA bullous dermatosis

Fig. 31.9 Cleavage ectodomains of BPAG2. COOH, carboxy terminus; NH2, amino terminus; TM, transmembrane region.  

Rare Allopurinol Amiodarone • Angiotensin receptor blockers: candesartan, eprosartan • Atorvastatin • Carbamazepine • Cyclosporine • Furosemide • Gemcitabine • Glyburide • Granulocyte colony-stimulating factor

Infliximab Influenza vaccination • Interferon-α and interferon-γ • Interleukin-2 • Lithium carbonate • PUVA • Rifampin • Somatostatin • Verapamil • Vigabatrin









*Unusual variants include toxic epidermal necrolysis-like and morbilliform. Table 31.5 Drug-induced linear IgA bullous dermatosis. ACE, angiotensinconverting enzyme; NSAIDs, nonsteroidal anti-inflammatory drugs.  

CHAPTER

Fig. 31.10 Drug-induced linear IgA bullous dermatosis. Annular vesicopustules and central crusting are seen in this patient receiving vancomycin.  

Fig. 31.12 Linear IgA bullous dermatosis. Annular and herpetiform vesicles arising on an inflammatory base. Annular pink plaques are also present. Courtesy,  

Jeffrey P Callen, MD.

Dermatitis Herpetiformis and Linear IgA Bullous Dermatosis

31

Fig. 31.11 Linear IgA bullous dermatosis. Vesicles and bullae arising within normalappearing skin as well as scattered annular lesions. The former can also be seen in bullous pemphigoid. Courtesy, Jeffrey  

P Callen, MD.

Fig. 31.13 Linear IgA bullous dermatosis. Striking annular vesiculobullous lesions on the thigh with central erosions and crusting. A figurate outline is seen in the area of  

Involvement of the tracheobronchial mucosa was reported in a severe case49. The ocular form of LABD is clinically indistinguishable from ocular mucous membrane pemphigoid50. LABD secondary to drugs, in particular vancomycin, may have a toxic epidermal necrolysis (TEN)-like or morbilliform presentation.

Pathology LABD is a subepidermal vesicular dermatosis in which neutrophils predominate. In early urticarial papules or plaques, neutrophils are aligned along the BMZ, accompanied by vacuolar change and sometimes by neutrophilic microabscesses in dermal papillae. These

papillary dermal collections, if numerous enough, can resemble the picture seen in DH24. In fully developed lesions, there are subepidermal bullae in which neutrophils are present in the underlying dermis, either alone or with eosinophils (Fig. 31.14). Eosinophils can become more numerous over time, particularly in adults, thus mimicking the histopathologic picture of bullous pemphigoid. Although in most cases distinguishing between DH and LABD is impossible by light microscopy, a linear distribution of neutrophils along the BMZ and neutrophils at the very tips of dermal papillae favor LABD51. However, the latter cannot be considered a specific finding. LABD can be subdivided on the basis of immunoelectron microscopy findings, with most patients having IgA deposits within the lamina lucida25,52. Less commonly, there is deposition of IgA in the sublamina densa, associated with anchoring fibrils25. In a few cases, deposits of IgA have been observed in both sites53. In one report, the deposition of IgA was initially in the lamina lucida, but later had a combined pattern53.

535

SECTION

5

Vesiculobullous Diseases

60–70% of patients with BP demonstrate circulating IgG class antibodies (see Table 31.3)23. Circulating IgA class anti-BMZ antibodies from the lamina lucida type of LABD have been shown to adhere to the epidermal side (roof) of salt-split skin, while patients with sublamina densa binding of IgA on direct immunoelectron microscopy have serum antibodies which bind to the dermal side of salt-split skin. Patients with both IgA and IgG at the BMZ demonstrate binding to the epidermal side of salt-split skin54. Whether or not such antibody titers correlate with disease activity has not yet been established. For the morbilliform or TEN-like presentation of LABD due to drugs, in particular vancomycin, routine microscopy plus DIF aids in the diagnosis.

Treatment

Fig. 31.14 Linear IgA bullous dermatosis – histopathologic features. Subepidermal blister filled with neutrophils. Neutrophils and a few eosinophils are also present within the underlying dermis. Courtesy, Lorenzo Cerroni, MD.  

Differential Diagnosis LABD can be difficult to diagnose clinically, especially in adults, and is often confused with DH and BP. By definition, LABD is separated from DH and BP on the basis of findings by DIF (see Table 31.3). Linear IgA deposition along the BMZ in perilesional skin is characteristic of LABD (see Fig. 31.8), in contrast to either DH, which shows granular deposition of IgA in dermal papillary tips or in a continuous pattern along the basement membrane23–25, or BP, which shows linear deposition of IgG along the epidermal BMZ. The classification of cases demonstrating both IgG and IgA along the BMZ is problematic. Some authorities include only those patients with IgA as the sole BMZ immunoglobulin under the term LABD and categorize all others as BP. Others categorize patients with both IgG and IgA along the BMZ based on the predominant immunoglobulin by DIF. Perhaps the most important point is that patients with IgA along the BMZ, alone or in combination with IgG, are more likely to respond to dapsone therapy. Distinguishing the sublamina densa form of LABD from epidermolysis bullosa acquisita is also made on the basis of the class of immunoreactant and classification can be problematic. Circulating anti-BMZ antibodies of the IgA class can be demonstrated in 60–70% of LABD sera. In contrast, patients with DH have not been shown to have circulating antibodies that bind to skin, and

The majority of patients with LABD respond to either oral dapsone or sulfapyridine therapy. These medications have been reviewed in detail in the section on the treatment of DH. Most patients with LABD have a clinical response within 48–72 hours. In occasional patients, it may be necessary to add oral prednisone in doses up to 40 mg daily to achieve complete control of the disease24,25,52,53. However, the majority of our patients have been controlled by dapsone alone. It is our observation that patients in whom both IgG and IgA deposits are present in the BMZ represent those who are likely to require additional therapy with systemic corticosteroids. The average dose of dapsone required to control LABD in adults is 100 mg daily, but doses as high as 300 mg daily may be needed. If doses >200 mg per day are necessary, close monitoring should be undertaken. Children usually respond to a dose of 1–2 mg/kg daily. Successful treatment of both adult and childhood LABD with antibiotics, including dicloxacillin, erythromycin, tetracycline (in those >9 years of age), and trimethoprim–sulfamethoxazole, has been reported. No specific microorganism was incriminated in these cases and therapeutic trials were empirical. A clinical trial of these relatively benign therapies may be undertaken, but no method of predicting a response has been identified. Mycophenolate mofetil, azathioprine, and IVIg can be used as steroid-sparing agents in patients who do not respond to a combination of prednisone and dapsone or in patients with severe disease. The natural course of the disease is characterized by persistence for several years with eventual spontaneous remission in many patients. Although a remission rate of 10–15% was originally described24,42, additional studies have reported remission rates of 30–60%. There should be repeated attempts to taper systemic medications, on the chance that a spontaneous remission has occurred. Childhood LABD remits within 2–4 years. For additional online figures visit www.expertconsult.com

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33. Gammon WR, Fine JD, Forbes M, et al. Immunofluorescence on split skin for the detection and differentiation of basement membrane zone autoantibodies. J Am Acad Dermatol 1992;27:79–87. 34. Hashimoto T, Ishiko A, Shimizu H, et al. A case of linear IgA bullous dermatosis with IgA and anti-type VII collagen autoantibodies. Br J Dermatol 1996;134:336–9. 35. Leonard JN, Griffith CEM, Powles AV, et al. Experience with a gluten free diet in the treatment of linear IgA disease. Acta Derm Venereol 1987;67:145–8. 36. Barberis C, Doutre MS, Bioulac-Sage P, et al. Dermatose bulleuse á IgA lineare associée á une maladie de Crohn. Gastroenterol Clin Biol 1988;12:76–7. 37. Egan CA, Meadows KP, Zone J. Ulcerative colitis and immunobullous disease cured by colectomy. Arch Dermatol 1999;135:214–15. 38. Barrow-Wade L, Jordan RE, Arnett FC Jr. Linear IgA bullous dermatosis associated with dermatomyositis (letter). Arch Dermatol 1992;128:413–14. 39. Davies MG, Marks R, Nuki G. Dermatitis herpetiformis: a skin manifestation of a generalized disturbance in immunity. Q J Med 1978;186:221–48. 40. Lacour JP, Vitetta A, Ortonne J-P. Linear IgA dermatosis and thyroid carcinoma. J Am Acad Dermatol 1992;26:257–9. 41. McEnvoy MT, Connolly SM. Linear IgA dermatosis: association with malignancy. J Am Acad Dermatol 1990;22:59–63. 42. Sekula SA, Tschen JA, Bean SF, Wolf JE Jr. Linear IgA bullous disease in a patient with transitional cell carcinoma of the bladder. Cutis 1986;38:354–6, 362. 43. Leonard JN, Tucker WFG, Fry JS, et al. Increased incidence of malignancy in dermatitis herpetiformis. Br Med J 1983;285:16–18. 44. Godfrey K, Wojnarowska F, Leonard J. Linear IgA disease of adults: association with lymphoproliferative malignancy and possible role of other triggering factors. Br J Dermatol 1990;123:447–52.

45. Thune P, Eeg-Larsen T, Nilsen R. Acute linear IgA dermatosis in a child following varicella. Arch Dermatol 1984;120:1237–8. 46. Blickenstaff RD, Perry HO, Peters MS. Linear IgA deposition associated with cutaneous varicella-zoster infection: a case report. J Cutan Pathol 1988;15:  49–52. 47. Carpenter S, Berg D, Sidhu-Malik N, et al. Vancomycinassociated linear IgA dermatosis. J Am Acad Dermatol 1992;26:45–8. 48. Kuechle MK, Stegemeir E, Maynard B, et al. Druginduced linear IgA bullous dermatosis: report of six cases and review of the literature. J Am Acad Dermatol 1994;30:187–92. 49. Verhelst F, Demedts M, Verschakelen J, et al. Adult linear IgA bullous dermatosis with bronchial involvement. Br J Dermatol 1987;116:587–90. 50. Kelly SE, Frith PA, Millard PR, et al. A clinicopathological study of mucosal involvement in linear IgA disease. Br J Dermatol 1988;119:161–70. 51. Smith SB, Harrist TJ, Murphy GF, et al. Linear IgA bullous dermatosis versus dermatitis herpetiformis: quantitative measurements of dermoepidermal alterations. Arch Dermatol 1984;120:324–8. 52. Yaoita H, Hertz KC, Katz SI. Dermatitis herpetiformis: immunoelectronmicroscopic and ultrastructural studies of a patient with linear deposition of IgA. J Invest Dermatol 1976;67:691–5. 53. Dabrowski J, Chorzelski TP, Jablonska S, et al. Immunoelectron microscopic studies in IgA linear dermatosis. Arch Dermatol Res 1979;265:  289–98. 54. Zone JJ, Smith EP, Powell D, et al. Antigenic specificity of antibodies from patients with linear basement membrane deposition of IgA. Dermatology 1994;189:64–6.

CHAPTER

31 Dermatitis Herpetiformis and Linear IgA Bullous Dermatosis

22. van der Meer JB. Granular deposits of immunoglobulins in the skin of patients with dermatitis herpetiformis: an immunofluorescent study. Br J Dermatol 1969;81:493–503. 23. Chorzelski TP, Jablonska S. Diagnostic significance of immunofluorescent pattern in dermatitis herpetiformis. Int J Dermatol 1975;14:429–36. 24. Mobacken H, Kastrup W, Ljundhall K, et al. Linear IgA dermatosis: a study of ten adult patients. Acta Derm Venereol 1983;63:123–8. 25. Lawley TJ, Strober W, Yaoita H, Katz SI. Small intestinal biopsies and HLA types in dermatitis herpetiformis patients with granular and linear IgA skin deposits. J Invest Dermatol 1980;74:9–12. 26. Jordon RE, Bean SF, Triftshauser CT, Winkelmann RK. Childhood bullous dermatitis herpetiformis. Arch Dermatol 1970;101:629–34. 27. Chorzelski TP, Jablonska S. IgA linear dermatosis of childhood (chronic bullous disease of childhood). Br J Dermatol 1979;101:535–42. 28. Esterly NB, Furey NL, Kirschner BS, et al. Chronic bullous dermatosis of childhood. Arch Dermatol 1977;113:42–6. 29. Provost TT, Maize JC, Ahmed AR, et al. Unusual subepidermal bullous diseases with immunologic features of bullous pemphigoid. Arch Dermatol 1979;115:156–60. 30. Wojnarowska F, Marsden RA, Bhogal B, et al. Childhood cicatricial pemphigoid with linear IgA deposits. Clin Exp Dermatol 1984;9:407–15. 31. Zone JJ, Taylor TB, Kadunce DP, Meyer LJ. Identification of the cutaneous basement membrane zone antigen and isolation of antibody in linear immunoglobulin A bullous dermatosis. J Clin Invest 1990;85:812–20. 32. Zone JJ, Taylor TB, Meyer LJ, Peterson MJ. The 97 kDa linear IgA bullous disease antigen is identical to a portion of the extracellular domain of the 180 kDa bullous pemphigoid antigen, BPAg2. J Invest Dermatol 1998;110:207–10.

537

eFig. 31.2 Linear IgA bullous dermatosis. Annular and herpetiform vesiculobullae on the face of a child.  

eFig. 31.1 Linear IgA bullous dermatosis. The circumferential and linear vesicles and bullae are typical of this disorder.  

CHAPTER

31 Dermatitis Herpetiformis and Linear IgA Bullous Dermatosis

Online only content

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eFig. 31.4 Linear IgA bullous dermatosis. A,B Annular and polycyclic plaques of the trunk in two women with the disorder.  

eFig. 31.3 Linear IgA bullous dermatosis. Annular vesiculobullous lesions on the hands with central erosions and crusting. A figurate outline is seen in the area of coalescence.  

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SECTION 5 VESICULOBULLOUS DISEASES

32 

Epidermolysis Bullosa Jo-David Fine and Jemima E. Mellerio

Synonyms:  ■ All forms of EB: EB hereditaria ■ EB simplex:

epidermolytic EB ■ Junctional EB: EB atrophicans, EB letalis ■ Dystrophic EB: EB dystrophica

Key features ■ Epidermolysis bullosa (EB) encompasses multiple clinically distinctive disorders that share three major features: genetic transmission, mechanical fragility of the skin, and blister formation ■ There are four major forms of inherited EB – EB simplex, junctional EB, dystrophic EB, and Kindler syndrome – which differ in the ultrastructural site within which cutaneous blisters form ■ EB may be diagnosed by immunofluorescence antigenic mapping, transmission electron microscopy, or genetic analysis ■ Any epithelial-lined or epithelial-covered organ is at potential risk for involvement in the more severe forms of inherited EB ■ In the absence of specific therapy, management is primarily focused on prevention of blisters, wound care, and treatment of extracutaneous complications

INTRODUCTION Inherited epidermolysis bullosa (EB), the prototypic mechanobullous disease, is characterized by the development of blisters following seemingly minor or insignificant trauma or traction to the skin1. It currently encompasses four major forms – EB simplex, junctional EB, dystrophic EB, and Kindler syndrome – and at least 40 distinctive clinical phenotypes2 (Table 32.1). Inherited EB can result from mutations within the genes for any of at least 19 structural proteins: keratins 5 and 14; the subunits of laminin 332 (formerly laminin 5); types VII and XVII collagens; plectin; α6β4 integrin; α3 integrin subunit; bullous pemphigoid antigen 1; kindlin-1 (fermitin family homolog-1); exophilin 5; transglutaminase 5; kelch-like protein 24; and the desmosomal components plakophilin-1, plakoglobin and desmoplakin. Although most of these diseases are rare, research into their underlying pathophysiologic bases has led to major advances in our understanding of the cell and molecular biology of keratins, other keratinocyte-associated structural proteins, collagens, and the cutaneous extracellular matrix (ECM). Study of EB has also helped to elucidate mechanisms of epithelial cell adhesion, migration, and differentiation and to highlight the role of the basement membrane zone in health and disease. The creation of in vitro and animal models of EB has enabled principles of gene therapy to be tested and refined, with development of novel approaches for the treatment of EB patients.

HISTORY

538

Epidermolysis bullosa was first described in 1870 by von Hebra under the name “erblichen pemphigus”3. Its current name, “epidermolysis bullosa hereditaria”, was coined by Koebner in 1886. Hallopeau recognized the distinct clinical features of simplex and dystrophic forms of EB in 1898. Junctional EB was first identified in 1935 by Herlitz and termed “EB letalis”. Precise characterization of these three major EB types via the use of transmission electron microscopy was first achieved by Pearson in 19624. In the ensuing years, additional EB phenotypes were described. Monoclonal antibody studies provided the first suggestion that specific protein defects underlie individual types and subtypes

of this disease5–8. In 1986, the National EB Registry was established in the US by the National Institutes of Health, facilitating epidemiologic, clinical, and laboratory characterization of each major EB type and subtype9,10. In 1991, Bonifas et al.11 utilized linkage analysis to demonstrate the molecular basis for EB simplex. Subsequent work by others has established the precise molecular basis for most of the EB subtypes recognized to date.

EPIDEMIOLOGY Based on National EB Registry data12, the estimated overall prevalence and incidence of EB in the US are 11.1 per 1 million population and 19.6 per 1 million live births, respectively. Carrier frequencies have also been reported13. The approximate prevalences and incidences, respectively, of the major types of EB are as follows: EB simplex, 6.0 and 7.9; junctional EB, 0.5 and 2.7; dominant dystrophic EB, 1.5 and 2.1; and recessive dystrophic EB, 1.4 and 3.0.

PATHOGENESIS EB is caused by mutations within genes that encode structural proteins that reside within the epidermis (EB simplex), dermal–epidermal junction (junctional EB), or uppermost papillary dermis (dystrophic EB). The site within which each of these proteins resides determines the ultrastructural location where the blisters arise (Table 32.1 & Fig. 32.1).

EB Simplex The most common forms of EB simplex (EBS) are transmitted in an autosomal dominant manner. There are two main subgroups of EBS, suprabasal and basal, which differ in the ultrastructural level of the intraepidermal blistering (see Table 32.1). The vast majority of EBS cases are in the basal group, most often resulting from a dominantnegative mutation (see Ch. 54) within the keratin 5 (KRT5) or 14 (KRT14) genes, expression of which is primarily within the basal layer of the epidermis14,15. The clinical severity and other phenotypic features of EBS are closely associated with the genotype. For example, mutations in the helix initiation and termination motifs of KRT5 and KRT14 (see Fig. 56.5) lead to the generalized severe subtype of EBS (EBS-gen/sev, previously known as EBS-Dowling–Meara), whereas the specific phenotype of EBS with mottled pigmentation almost always arises from a particular missense mutation in the V1 domain of KRT5. Dominant stabilizing mutations in the kelch-like protein 24 (KLHL24) ubiquitin ligase lead to EBS via increased ubiquitination and degradation of KRT1415a. An autosomal recessive form of EBS due to mutations in the gene encoding plectin is associated with muscular dystrophy, which is not surprising considering that plectin is expressed in skeletal muscle as well as in the hemidesmosomes of basilar keratinocytes. Other EBS patients with plectin or α6β4 integrin deficiency present with pyloric atresia, while rare autosomal recessive variants of basal EBS caused by mutations in the bullous pemphigoid antigen 1 or exophilin 5 genes have also been reported. In addition, suprabasal forms of EBS result from mutations in the genes encoding transglutaminase 5 and the desmosomal proteins plakophilin-1, plakoglobin, and desmoplakin (see Table 32.1 and Fig. 56.8).

Junctional EB Junctional EB (JEB) is almost always transmitted in an autosomal recessive manner (see Table 32.1). The generalized severe subtype of JEB (JEB-gen/sev, previously known as JEB-Herlitz) typically results from homozygous or compound heterozygous truncating mutations within a gene encoding one of the three subunits of laminin 332, a

Inherited epidermolysis bullosa (EB) represents a group of genetic disorders characterized by mechanically fragile skin with a propensity to develop blisters and/or erosions. EB simplex, junctional EB, dystrophic EB and Kindler syndrome represent the four major types of EB, which differ in the ultrastructural site within which cutaneous blisters form – intraepidermal, intra-lamina lucida, sublamina densa and mixed, respectively. At least 39 distinct subtypes of EB have been described. The diagnosis is based on the clinical phenotype, ultrastructural and immunohistochemical findings, and molecular genotype. Many EB subtypes are associated with substantial morbidity and even mortality related to skin and mucosal involvement, extracutaneous complications, and cutaneous malignancies (primarily SCCs). Management of EB is currently focused on the prevention of mechanical trauma, wound care, and avoidance as well as treatment of infections and extracutaneous manifestations. Advances in our knowledge of the pathogenesis of this group of diseases may lead to the development of more effective gene-, protein- and cell-based therapies.

epidermolysis bullosa simplex, junctional epidermolysis bullosa, dystrophic epidermolysis bullosa, Kindler syndrome, basement membrane, skin fragility, epidermolysis bullosa, mechanobullous disease

CHAPTER

32 Epidermolysis Bullosa

ABSTRACT

non-print metadata KEYWORDS:

538.e1

CHAPTER

Subtype

Inheritance

Defective protein(s)

Acral peeling skin syndrome

AR

Transglutaminase 5

EB superficialis

Unknown

Unknown

Acantholytic EBS

AR

Desmoplakin; plakoglobin

Desmoplakin deficiency (skin fragility–woolly hair syndrome)

AR

Desmoplakin

Plakoglobin deficiency

AR

Plakoglobin

Plakophilin deficiency (skin fragility–ectodermal dysplasia syndrome)

AR

Plakophilin 1

AD

Keratins 5 and 14

AD

Keratin 5

EBS, AR-KRT14

AR

Keratin 14

EBS due to KLHL24

AD

Kelch-like protein 24

EBS with muscular dystrophy

AR

Plectin

Suprabasal intraepidermal cleavage

Skin fragility syndromes

32 Epidermolysis Bullosa

EPIDERMOLYSIS BULLOSA: SIMPLEX, JUNCTIONAL AND DYSTROPHIC SUBTYPES AND KINDLER SYNDROME

Basal intraepidermal cleavage EBS, localized (formerly Weber–Cockayne) EBS, generalized severe (formerly Dowling–Meara) EBS, generalized intermediate EBS with mottled pigmentation EBS, migratory circinate

EBS with pyloric atresia

AR

Plectin; α6β4 integrin

EBS-Ogna

AD

Plectin

EBS, AR-BP230 deficiency

AR

Bullous pemphigoid antigen 1 (BP230)

EBS, AR-exophilin 5 deficiency

AR

Exophilin 5

JEB, generalized severe (formerly Herlitz)

AR

Laminin 332

JEB, generalized intermediate

AR*

Laminin 332; collagen XVII

JEB with pyloric atresia

AR

α6β4 integrin

JEB, late onset

AR

Collagen XVII

Intra-lamina lucida cleavage

JEB with respiratory and renal involvement

AR

α3 integrin subunit

JEB, localized

AR

Collagen XVII; α6β4 integrin

JEB, inversa

AR

Laminin 332

JEB-laryngo-onycho-cutaneous syndrome

AR

Laminin α3 chain (a isoform)

AD

Collagen VII

Sublamina densa cleavage DDEB, generalized Other DDEB variants: acral, pretibial, pruriginosa, nails only DDEB, bullous dermolysis of the newborn RDEB, generalized severe (formerly Hallopeau–Siemens)

AR

RDEB, generalized intermediate RDEB, inversa Other RDEB variants: localized, pretibial, pruriginosa, centripetalis RDEB, bullous dermolysis of the newborn Mixed cleavage planes Kindler syndrome

AR

Kindlin-1

*One case with AD inheritance has been reported. Table 32.1 Epidermolysis bullosa (EB): simplex, junctional and dystrophic subtypes and Kindler syndrome. Entities with a lighter background represent rare variants. AD, autosomal dominant; AR, autosomal recessive; EBS, epidermolysis bullosa simplex; DDEB, dominant dystrophic EB; RDEB, recessive dystrophic EB.  

key component of the lamina lucida of the dermal–epidermal junction (see Ch. 28)16. In laryngo-onycho-cutaneous syndrome, the underlying mutations affect only the a isoform of the laminin α3 subunit. The milder generalized intermediate form of JEB (JEB-gen/intermed, previously known as JEB-non-Herlitz and generalized atrophic benign EB) results from mutations within the genes for either a subunit of laminin 332 or type XVII collagen. JEB with pyloric atresia, which is more common than EBS with pyloric atresia, is also caused by mutations within either of the two genes that encode the subunits of α6β4

integrin. A newly recognized form of JEB associated with respiratory and renal involvement results from mutations in the integrin α3 chain.

Dystrophic EB Dystrophic EB (DEB) is transmitted in either an autosomal dominant or autosomal recessive manner and is caused by mutations in the type VII collagen gene. Dominant DEB (DDEB) results from dominant-negative mutations, typically a missense mutation that leads to substitution of

539

SECTION

VESICULOBULLOUS DISEASES

5

A

Ultrastructural sites of blister formation in three major subtypes of EB simplex Normal intact skin

EBS-loc and EBS-gen/intermed (lesional)

EBS-gen/sev (lesional)

Blister cavity

Blister cavity

Basal keratinocyte KRT5 and KRT14 keratin filaments Hemidesmosome attachment plate Sub-basal dense plate Anchoring filaments

Lamina lucida Lamina densa

Anchoring fibril

Papillary dermis

Collagen fiber

Clumped keratin filaments

B

Ultrastructural sites of blister formation in two major subtypes of junctional EB Normal intact skin

JEB-gen/sev (lesional)

Blister cavity

C

JEB-gen/intermed (lesional)

Small hemidesmosome

Blister cavity

Ultrastructural sites of blister formation in three major subtypes of dystrophic EB

Normal intact skin

DDEB (lesional)

Blister cavity

540

Fig. 32.1 Blister formation in epidermolysis bullosa (EB). A Ultrastructural sites of blister formation in three major subtypes of EB simplex (EBS). The ultrastructure of normal intact skin is presented for comparison. In all three major subtypes of EB simplex – localized (EBS-loc), generalized intermediate (EBS-gen/ intermed) and generalized severe (EBS-gen/sev) – blisters arise within the lowermost intracytoplasmic portion of the basilar keratinocyte. In EBS-gen/sev, keratin filaments tend to coalesce into larger electron-dense clumps, especially in lesional skin. Keratin filaments are absent or reduced in the rare autosomal recessive form of EBS, and in EBS with muscular dystrophy there is lack of integration of keratin filaments into the underlying hemidesmosome. Suprabasal forms of EBS that feature acantholysis (e.g. skin fragility syndromes) feature diminutive suprabasal desmosomes and perinuclear retraction of keratin filaments, while a higher cleavage plane between the granular and cornified cell layers is seen in EBS superficialis.   B Ultrastructural sites of blister formation in two major subtypes of junctional EB (JEB). All forms of JEB are characterized by blister formation within the lamina lucida of the dermal–epidermal junction. As such, the lamina densa remains firmly attached to the dermis which forms the base of the blister cavity. Sub-basal dense plates and anchoring filaments are absent in generalized severe JEB (JEB-gen/sev) and often attenuated in other subtypes of JEB. Hemidesmosomes are absent or extremely sparse and rudimentary in JEB-gen/sev, whereas they are normal or reduced in number and size in generalized intermediate JEB (JEB-gen/intermed).   C Ultrastructural sites of blister formation in three major subtypes of dystrophic EB (DEB). Blister formation occurs beneath the lamina densa in all forms of dystrophic EB. Anchoring fibrils appear normal in size and structure in dominant DEB (DDEB) skin, although they may be somewhat reduced in number. Consistent with the presence of sublamina densa cleavage, these anchoring fibrils remain attached to the blister roof, which is composed of intact epidermis and an attached basement membrane that includes the lamina densa. In contrast, anchoring fibrils are usually completely absent in lesional skin from patients with generalized severe recessive DEB (RDEB-gen/sev). In the generalized intermediate form of RDEB (RDEB-gen/ intermed), anchoring fibrils are reduced in number and rudimentary in appearance.  

BLISTER FORMATION IN EPIDERMOLYSIS BULLOSA

RDEB-gen/sev (lesional)

RDEB-gen/intermed (lesional)

Sparse, small, rudimentary-appearing anchoring fibril Blister cavity

Blister cavity



D

Ultrastructural sites of blister formation in bullous dermolysis of the newborn Normal intact skin

DDEB-BDN during infancy, when blistering is active

DDEB-BDN, after all blistering has ceased

CHAPTER

32 Epidermolysis Bullosa

Fig. 32.1 Blister formation in epidermolysis bullosa (EB). (cont’d) D Ultrastructural site of blister formation in the form of DDEB referred to as bullous dermolysis of the newborn (DDEB-BDN). With age, there is improvement in the transport and deposition of type VII collagen from the keratinocyte cytoplasm to the anchoring fibrils of the basement membrane.

Blister cavity

another amino acid for a glycine within the triple-helical domain of this collagen. Although the resultant protein is structurally abnormal, immunohistochemical staining of the dermal–epidermal junction is usually indistinguishable from that of normal skin. Recessive DEB (RDEB) is usually due to compound heterozygous mutations within the type VII collagen gene17–19. Premature stop codons, which result in truncated proteins, are characteristic of the generalized severe subtype (RDEB-gen/sev, previously known as RDEB-Hallopeau– Siemens). Consistent with the severity of these mutations, anchoring fibrils are undetectable or extremely sparse and poorly formed in skin biopsy specimens, and immunohistochemical staining with antibodies against the major epitopes of the type VII collagen molecule is absent or barely detectable. Milder forms of generalized RDEB are associated with less severe biallelic mutations in the type VII collagen gene. Recently, a single nucleotide polymorphism in the matrix metalloproteinase 1 gene promoter has been identified as a disease modifier in RDEB20. It is likely that additional modifying genes account for some of the inter- and intra-familial phenotypic variability observed in this and other forms of EB. There is also evidence for secondary effects from loss of protein expression in EB. For example, loss of collagen VII in RDEB fibroblasts leads to alterations in dermal matrix proteins, metalloproteinases, and transforming growth factor β (TGF-β), which are thought to further influence keratinocyte adhesion and dermal– epidermal integrity21. Some patients with RDEB retain the amino terminal non-collagenous domain (NC1) of type VII collagen, and this specific fragment may contribute to an increased susceptibility to develop squamous cell carcinomas (SCCs)22. In a Ras-driven model of tumorigenesis, RDEB keratinocytes that contained no type VII collagen did not form tumors in mice, whereas RDEB keratinocytes that produced the NC1 domain of type VII collagen were tumorigenic. Additional studies have pointed to the fibronectin-like sequences within NC1 as key to promoting tumor cell invasion. However, SCCs can also develop in RDEB patients who do not express the NC1 domain23. In a rare form of DEB referred to as bullous dermolysis of the newborn, inheritance is usually dominant and blistering is typically confined to the first 1–2 years of life24–26. Clinical expression coincides with a time during which type VII collagen is present primarily within basilar keratinocytes in these patients’ skin, rather than along the dermal–epidermal junction (see Fig. 32.1D). This suggests that there may be a temporary disruption in the transport of this protein from the keratinocyte cytoplasm to the underlying ECM.

CLINICAL FEATURES Cutaneous Findings All forms of inherited EB are characterized by mechanically fragile skin, erosions, and (with rare exceptions) macroscopic blisters (Figs 32.2 &

$

Fig. 32.2 Localized epidermolysis bullosa simplex. A, B Bullae arising on the toes and plantar surfaces at sites of lateral or rotary traction. The majority of blisters occur in acral sites. B, Courtesy,  

Julie V Schaffer, MD.

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$ $

Fig. 32.3 Generalized intermediate epidermolysis bullosa simplex. Extensive blistering on the buttocks (A) and blistering in association with focal keratoderma on the soles (B) of a 2-year-old girl. Courtesy,  

Julie V Schaffer, MD.

% %

542

32.3). Scarring is almost always atrophic and can occur in any subtype of EB (Fig. 32.4), including localized EBS. However, scarring is most frequent in the subtypes that are characterized clinically by generalized disease activity and ultrastructurally by disruption of the basement membrane, particularly the lamina densa (Fig. 32.5). Whereas scarring is estimated to occur in only 15% of patients with localized EBS, it is present in essentially every patient with RDEB27. Other cutaneous findings that have similar variations in frequency across the major types and subtypes of EB include dystrophic or absent nails (see Fig. 32.4), milia, and scarring alopecia of the scalp. Some cutaneous findings have diagnostic implications (Fig. 32.6)2. Reticulated hyperpigmented macules distinguish a rare subtype of EB simplex termed EBS with mottled pigmentation. Superficial peeling of the skin, often in the absence of overt blistering, is seen in EBS superficialis (EBSS) and acral peeling skin syndrome (Fig. 32.7)28. Grouped (“herpetiform”) blisters, often in an arcuate (Fig. 32.8) or polycyclic array, are highly characteristic of EBS-gen/sev, which is also associated with the gradual development of a diffuse palmoplantar keratoderma (Fig. 32.9). Migratory circinate erythema with vesiculation of the advancing edge has been described in patients with EBS caused by a frameshift mutation that leads to an elongated KRT5 protein. Excessive or exuberant granulation tissue, usually in a symmetric distribution involving the periorificial areas, skin folds, upper back, nape of the neck, and periungual areas, is typical of JEB-gen/sev (Fig. 32.10). Extremely pruritic papules coalescing in a linear arrangement on the lower extremities are characteristic of DEB pruriginosa (Fig. 32.11).

&

Fig. 32.4 Dominant dystrophic epidermolysis bullosa. A, B Erosions, scarring and milia on the fingers. Note the partial (A) to almost complete (B) loss of the nails. C A discrete area of scarring on the elbow with blisters, crusting and milia. B, Courtesy, Julie V Schaffer, MD.  

Extracutaneous Findings The molecular defects that affect the skin in patients with EB may also lead to manifestations in other tissues with an epithelial lining or surface30–34, including the eye, oral cavity, and gastrointestinal, genitourinary, and respiratory tracts. Major extracutaneous complications of EB are summarized in Table 32.230–32. Although exceptions exist, extracutaneous involvement occurs most frequently in RDEB and JEB,

FREQUENCY OF SELECTED CUTANEOUS FINDINGS WITHIN EACH MAJOR SUBTYPE OF INHERITED EB 100

Patients having these findings (%)

90 80 70 60 50 Scarring Milia Nail dystrophy All three findings None

40 30 20 10 0 EBS

JEB

DDEB

RDEB

Fig. 32.5 Frequency of selected cutaneous findings within each major subtype of inherited epidermolysis bullosa (EB). Note the increasing frequency from localized EB simplex (EBS) to recessive dystrophic EB (RDEB). JEB, junctional EB; DDEB, dominant dystrophic EB.  

and it can result in blisters, erosions, ulcers, and scarring. Rare subtypes of JEB and EBS present at birth with pyloric atresia as well as skin fragility and blistering34. In other forms of EB, extracutaneous disease may become apparent as early as the first few months of life. Repeated blistering of the external eye can result in neovascularization and blindness33. Chronic involvement of the esophagus leads to scarring, stricture formation and, rarely, even complete obstruction34. Involvement of the small intestine presents with chronic malabsorption, whereas disease activity within the large intestine tends to produce constipation and anal fissures or strictures. Recurrent genitourinary tract blistering may result in urethral or ureterovesical strictures; if persistent, the latter may eventuate in ureteric reflux and hydronephrosis. Tracheolaryngeal blistering and associated soft tissue edema, seen most often in infants and young children with JEB-gen/sev, may lead to potentially fatal acute airway obstruction35. JEB with respiratory and renal involvement is a rare subtype associated with severe interstitial lung disease. Dental enamel hypoplasia, which occurs in all forms of JEB36,37, is associated with pitting of the surfaces of primary and permanent teeth. If untreated, affected individuals lose teeth during childhood due to excessive caries38. Severe caries and resultant tooth loss also occur in RDEB-gen/sev, likely resulting from impaired clearance of food from the mouth and poor dental hygiene in the setting of intraoral injury and scarring, ankyloglossia, and microstomia. Pseudosyndactyly (“mitten” deformities) of the hands and feet primarily affects patients with RDEB, especially RDEB-gen/sev, although it occasionally occurs to a lesser degree in DDEB and JEB39 (Fig. 32.12). Initially presenting as proximal web formation between adjacent digits, the digits may eventually become totally fused and encased by scar tissue. Lack of mobility leads to bone resorption and muscular atrophy, and hand function is severely compromised. Osteoporosis, detectable by dual-emission X-ray absorptiometry (DEXA) scanning, is common in RDEB-gen/sev and JEB-gen/sev. Radiographs may demonstrate vertebral crush fractures in severe cases. EBS due to plectin deficiency is associated with mild to severe muscular dystrophy. Although the muscle disease presents during infancy in some patients, weakness often develops insidiously during later childhood or even early adulthood in those who are less severely affected. Chronic renal failure occasionally develops in patients with severe forms of EB, most notably RDEB-gen/sev, which is associated with a ~10% risk of death from renal failure by age 35 years40. Renal disease may result from untreated outflow obstruction, glomerulonephritis, secondary systemic amyloidosis or IgA nephropathy. Nephrotic syndrome associated with altered expression of laminin isoforms in renal basement membranes has been reported in an infant with JEB-gen/sev and it occurs congenitally as a result of integrin α3 mutations in JEB with respiratory and renal involvement. A small subset of patients with

CHAPTER

32 Epidermolysis Bullosa

Distribution of skin disease activity is also useful in the subclassification of EB27,29, although the pattern of involvement tends to be less distinctive in infants than in adults. Patients with the “inversa” subtypes of JEB and RDEB experience severe disease activity primarily in intertriginous areas such as the axillae and inguinal creases. In contrast, patients with localized JEB have involvement mainly in acral sites, and those with pretibial DEB have lesions almost exclusively on the shins. RDEB centripetalis is a rare subtype that initially features acral blistering, followed by slow progression of disease activity toward the trunk over the years.

Fig. 32.6 Helpful cutaneous findings in patients with epidermolysis bullosa (EB). DEB, dystrophic EB; EBS, EB simplex; JEB, junctional EB.  

HELPFUL CUTANEOUS FINDINGS IN PATIENTS WITH EB

Distinguishing cutaneous findings in patients with EB

Primary involvement of the palms and soles

Primary involvement of axillae and groin

Grouped or “herpetiform” blisters, sometimes in a figurate array

Reticulated hyperpigmentation

Excessive or exuberant granulation tissue, e.g. periorificial, axillae, neck, upper back

Confluent palmoplantar keratoderma

Prurigo-like nodules coalescing into linear plaques on the shins

EBS, localized

JEB, inversa subtype; recessive dystrophic EB, inversa subtype

EBS, generalized severe

EBS with mottled pigmentation

JEB, generalized severe

EBS, generalized severe

DEB, pruriginosa

543

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VESICULOBULLOUS DISEASES

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Fig. 32.7 Acral peeling skin syndrome. Superficial peeling of the skin on the ankle and dorsal aspect of the foot. Courtesy, E Sprecher, MD, PhD.  

$

%

Fig. 32.10 Generalized severe junctional epidermolysis bullosa. A Blisters on the elbow and large areas of denuded skin; note the bright red color in the axilla and groin. B Blisters and large erosions on the abdomen of an infant.  

B, Courtesy, Julie V Schaffer, MD.

Fig. 32.8 Generalized severe epidermolysis bullosa simplex. Clustered vesicles in an arcuate array on the thigh of this child. Courtesy, Julie V Schaffer, MD.  

Fig. 32.11 Dystrophic epidermolysis bullosa, pruriginosa. Prurigo-like papulonodules coalescing into linear plaques on the shin as a consequence of chronic scratching.  

544

Fig. 32.9 Generalized severe epidermolysis bullosa simplex. Diffuse palmar keratoderma in an adult.  

CHAPTER

32 Epidermolysis Bullosa

MAJOR EXTRACUTANEOUS COMPLICATIONS OF EPIDERMOLYSIS BULLOSA

EB subtype(s) most commonly affected Complication

≥50% of patients

RDEB-gen/intermed, RDEB-inv, JEB-gen/ intermed JEB-gen/sev; Kindler

Oral cavity and upper airway (excluding blisters) Microstomia

RDEB-gen/sev

JEB-gen/sev, RDEB-inv

Enamel hypoplasia

JEB (all subtypes)

Excessive caries and premature loss of teeth

RDEB gen/sev, JEB-gen/sev

Tracheolaryngeal stenosis

JEB-gen/sev

JEB-gen/intermed

Esophageal strictures

RDEB-gen/sev, RDEB-inv

RDEB-gen/intermed, Kindler > JEB-gen/sev

Pyloric atresia

JEB-PA, EBS-PA

Malnutrition/failure to thrive

RDEB-gen/sev, JEB-gen/sev

JEB-gen/intermed

Severe constipation

RDEB-gen/sev

JEB-gen/sev, EBS-gen/sev

GERD

RDEB

JEB, EBS-gen/sev

$

Gastrointestinal tract

Colitis

Kindler, RDEB-gen/ sev

Genitourinary tract Urethral meatal stenosis

RDEB-gen/sev, JEB-gen/sev, Kindler

Chronic renal failure*

RDEB-gen/sev

Hydroureter and hydronephrosis

JEB-PA, JEB-gen/sev

Nephrotic syndrome

JEB-resp/renal

%

Fig. 32.12 Generalized severe recessive dystrophic epidermolysis bullosa. A Early proximal interdigital web formation together with atrophic scarring and loss of nails in a 5-year-old girl. B Partial “mitten” deformities of the hands in an older child. A, Courtesy, Julie V Schaffer, MD.  

JEB-gen/sev

Heart RDEB-gen/sev > JEB, RDEB-gen/intermed

Dilated cardiomyopathy Musculoskeletal system Pseudosyndactyly

RDEB-gen/sev

RDEB-gen/intermed, Kindler

Osteoporosis or osteopenia

RDEB-gen/sev

RDEB-gen/sev, JEB-gen/sev

Muscular dystrophy

EBS-MD

Bone marrow Severe multifactorial anemia

RDEB-gen/sev, JEB-gen/sev

*Causes include renal amyloidosis and glomerulonephritis. Table 32.2 Major extracutaneous complications of epidermolysis bullosa (EB). EBS, EB simplex; GERD, gastroesophageal reflux disease; gen/intermed, generalized intermediate; gen/sev, generalized severe; inv, inversa; JEB, junctional EB; MD, muscular dystrophy; PA, pyloric atresia; RDEB, recessive dystrophic EB; resp/renal, respiratory and renal involvement.  

severe forms of EB, especially RDEB-gen/sev, develop potentially fatal dilated cardiomyopathy41. Although as yet unproven, selenium or carnitine deficiency may be a contributing factor. Although it was a common occurrence several decades ago, potentially lethal bacterial sepsis is now relatively rare in inherited EB42, presumably due to improved wound care and the availability and judicious use of broad-spectrum antibiotics. When sepsis does occur in EB, it tends to affect infants with generalized severe disease43. In contrast, failure to thrive is still common among infants with JEB-gen/sev and may lead to death.

Cutaneous Malignancies A major complication, usually of RDEB, is the development of multiple cutaneous SCCs44. These tumors most often arise in chronic nonhealing wounds or hyperkeratotic lesions (Fig. 32.13). Histologically, they are usually well differentiated. However, the borders of the lesions are often indistinct and they are difficult to completely excise, with a tendency to recur locally. In addition, SCCs in EB patients frequently metastasize and are strikingly unresponsive to chemotherapy or radiotherapy. Indeed, they represent the leading cause of death in EB at or after mid-adolescence, with death from an SCC of cutaneous origin occurring in most patients within 5 years of the diagnosis of their first SCC42. These tumors occur primarily in RDEB, especially RDEB-gen/

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Fig. 32.14 Large acquired melanocytic nevus at a site of blistering in a teenage girl with junctional epidermolysis bullosa. Courtesy, Julie V Schaffer, MD.  

Fig. 32.13 Squamous cell carcinoma. Large squamous cell carcinoma on the ankle of a 21-year-old man with generalized severe recessive dystrophic epidermolysis bullosa. Courtesy, Julie V Schaffer, MD.  

sev, although SCCs can also develop in adults with generalized JEB. The cumulative risk of at least one SCC in patients with RDEB-gen/ sev is 7.5% by age 20 years but rises to 68%, 80%, and 90% by ages 35, 45, and 55 years, respectively32. In contrast, the risk of SCC in other forms of RDEB is blisters favor extremities (Fig. 32.15); perioral and intertriginous fissures; focal PPK with fissures; sparse and/or woolly hair; nail dystrophy; acantholysis in skin biopsy specimens; DSP: follicular hyperkeratosis on extensor surfaces, variable cardiomyopathy and hoarseness

Acantholytic EBS

Desmoplakin/DSP or plakoglobin/JUP (AR)

Generalized erosions at birth; universal alopecia; acantholysis in skin biopsy specimens; DSP: natal teeth, anonychia and variable cardiomyopathy; JUP: onycholysis and infections

Acral peeling skin syndrome

Transglutaminase 5 (AR)

Superficial peeling and erosions on hands and feet (see Fig. 32.7)

EBS superficialis

Unknown

Superficial erosions; postinflammatory hyperpigmentation; subcorneal cleavage

32 Epidermolysis Bullosa

SUPRABASAL FORMS OF EPIDERMOLYSIS BULLOSA SIMPLEX AND ADDITIONAL GENODERMATOSES ASSOCIATED WITH BLISTERS

Additional genodermatoses associated with blistering Superficial epidermolytic ichthyosis (ichthyosis bullosa of Siemens)

Keratin 2 (AD)

Mauserung phenomenon (desquamation); superficial intraepidermal blistering in skin biopsy specimens

Epidermolytic ichthyosis

Keratins 1 and 10 (AD)

Blistering primarily in the first few years of life; later, corrugated hyperkeratosis; epidermolytic hyperkeratosis in skin biopsy specimens; keratin 1: PPK

Congenital erythropoietic porphyria (Günther disease)

Uroporphyrinogen III synthetase (AR)

Severe photosensitivity leading to blistering, deep ulcerations and facial/digital mutilation; elevated uroporphyrin I and coproporphyrin I; red urine and teeth; hemolytic anemia

Mendes da Costa syndrome

Unknown (X-linked)

Spontaneous formation of bullae (unprovoked by trauma); atrichia; acrocyanosis; dyspigmentation; microcephaly; mental retardation

AEC (ankyloblepharon–ectodermal dysplasia–clefting) syndrome

p63 (AD)

Ankyloblepharon; ectodermal dysplasia; cleft lip and palate; erythroderma; widespread erosions in neonates; chronic erosive scalp dermatitis; patchy alopecia

Table 32.3 Suprabasal forms of epidermolysis bullosa simplex (EBS) and additional genodermatoses associated with blisters. AD, autosomal dominant; AR, autosomal recessive; PPK, palmoplantar keratoderma.  

Bart syndrome, which is defined as the coexistence of any type of EB and congenital localized absence of skin (CLAS; aplasia cutis congenita; see Ch. 64), is distinguished from other causes of CLAS by the presence of blisters and mechanical fragility of the skin, as well as the typical location of EB-associated CLAS on the lower extremities rather than the scalp. Diagnostic considerations in patients with acral blistering, erosions, and ulcerations with progression to digital resorption may include congenital erythropoietic porphyria (see Table 32.3 and Ch. 49) and SAVI (STING-associated vasculopathy with onset in infancy, Fig. 32.18; see Ch. 45).



*

$

TREATMENT There are currently no specific therapies for any form of inherited EB. In the future, effective gene therapy may become a reality for at least some forms of EB48. For example, there are reports of the successful transfer of genes, such as those that encode one of the chains of laminin 33249, into keratinocytes from affected individuals; when these genetically corrected keratinocytes are transplanted onto immunodeficient mice, the resultant epithelium has no evidence of blistering. In a proof-of-principle experiment, a small portion of ex vivo-produced skin equivalent containing a corrected laminin 332 gene was transplanted onto a recipient with JEB-gen/intermed, and after several years has yet to develop blistering within its borders50. More recently, a similar ex vivo approach was used to graft autologous epidermal sheets containing a corrected type VII collagen gene onto patients with RDEB-gen/sev50a. Mutation site-specific genome editing of induced pluripotent stem cells with transcription activator-like effector nuclease (TALEN) and clustered regularly interspaced short palindromic repeats (CRISPR)/Cas9 systems may also be of utility for EB gene therapy50b (see Ch. 3). It has been shown that injection of either human type VII collagen or normal allogeneic fibroblasts into a mouse engrafted with type VII collagen-deficient RDEB skin can result in increased deposition of this protein along the dermal–epidermal junction and the cessation of blistering51,52. There are now several clinical trials in progress that are

Fig. 32.16 Ultrastructure of epidermolysis bullosa simplex (EBS), junctional epidermolysis bullosa (JEB) and recessive dystrophic epidermolysis bullosa (RDEB). A Electron microscopy (EM) of an induced blister in localized EBS demonstrates skin cleavage (asterisk) within the inferior-most portion of the basilar keratinocyte. B EM of a spontaneous blister from a patient with the severe generalized JEB reveals skin cleavage (asterisks) within the lamina lucida. Hemidesmosomes, sub-basal dense plates and anchoring filaments are all absent. In contrast, anchoring fibrils are still present in normal amounts within the underlying dermis. C EM of the roof of a spontaneous blister from a patient with generalized severe RDEB reveals cleavage (asterisks) beneath the level of the lamina densa. Anchoring fibrils are absent along the epidermal roof of the blister.

* * %

&

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Fig. 32.17 Approach to the laboratory diagnosis of epidermolysis bullosa (EB). BM, basement membrane; DDEB, dominant dystrophic EB; EBS, EB simplex; JEB, junctional EB; RDEB, recessive dystrophic EB.  

VESICULOBULLOUS DISEASES

APPROACH TO THE LABORATORY DIAGNOSIS OF EPIDERMOLYSIS BULLOSA (EB)

Approach to the laboratory diagnosis of epidermolysis bullosa (EB)

Immunofluorescence antigen mapping (IFM) &/or transmission electron microscopy (TEM) of biopsy specimen(s) from a fresh induced blister • Preferred sites: upper inner arm just above elbow or a non-acral blister-prone area • Apply firm pressure on intact skin with pencil eraser and rotate 180° in each direction 3–10+ times • Perform 3–4 mm punch biopsy at blister edge

Next-generation sequencing panel with all known EB genes (see Table 54.6)

*

IFM using anti-BM monoclonal antibodies • Place sample in Michel’s/Zeus medium

TEM • Place sample in glutaraldehyde • See Figs 32.1 & 32.16

Determine plane of cleavage • Relative to antigens identified in a primary screening antibody panel, e.g. against laminin 2 chain and collagen types IV, VII and XVII

Assess for abnormal expression or distribution of BM proteins • Targeted secondary antibody panel • Decreased antigen expression is most often seen in recessive forms of EB: Antigen Selected EB subtypes with absent/markedly reduced staining Plectin EBS with muscular dystrophy JEB with pyloric atresia 64 integrin Laminin 332 JEB-generalized severe Type XVII collagen JEB-generalized intermediate Type VII collagen RDEB-generalized severe Kindlin-1 Kindler syndrome (findings vary) • Often relatively normal staining in dominant forms of EB, e.g. keratin 5/14 in EBS and type VII collagen in DDEB • In active DDEB-bullous dermolysis of the newborn, collagen VII staining is granular within basal keratinocytes but reduced/absent within the BM Consider genetic analysis guided by results • Required for DNA-based prenatal/preimplantation testing

*May be more difficult to induce blisters in patients with localized EBS or DDEB

Fig. 32.18 SAVI (STING-associated vasculopathy with onset in infancy). This vasculopathic genetic disorder can result in digital resorption resembling that in recessive dystrophic epidermolysis bullosa.  

548

exploring the therapeutic benefit of intradermally injecting allogeneic fibroblasts into non-healing wounds in RDEB patients. Although painful to administer, many chronic wounds have responded well53. Clinical trials are also ongoing to investigate the value of bone marrowderived stem cell transplantation as a systemic treatment for RDEB54. In an initial report55, bone marrow transplantation after total or partial myeloablation resulted in substantial proportions of donor cells in the skin, increased collagen VII deposition at the dermal–epidermal junction and variably decreased blistering in children with RDEB. Other investigators are studying alternative sources, such as mesenchymal stromal cells and inducible pluripotent stem cells, for the cellular correction of this disease56. Revertant mosaicism in the skin of EB patients represents “natural gene therapy” that can restore wild-type function to a clone of cells, providing a model for potential gene manipulation strategies and possibly explaining the tendency for improvement with age in some subtypes of EB. Mitotic gene conversion, true back mutations, and second-site mutations that prevent a premature termination codon or restore the reading frame have been shown to reverse disease-causing type XVII collagen mutations in individuals with JEB-gen/intermed, leading to decreased blistering in discrete areas of skin57. Second-site nonsense mutations have also been shown to abrogate blistering by silencing a dominant-negative keratin 14 allele in those with

CHAPTER

KINDLER SYNDROME

32

Synonyms:  ■ Kindler–Weary syndrome ■ Bullous acrokeratotic poikiloderma of Kindler and Weary ■ Hereditary acrokeratotic poikiloderma

Introduction Now classified as a form of EB, Kindler syndrome is a rare autosomal recessive genodermatosis that features photosensitivity, progressive poikiloderma, cutaneous atrophy, and mucosal inflammation in addition to trauma-induced blistering2,69–71.

Epidermolysis Bullosa

EBS-gen/sev, and revertant mosacism has also been observed in RDEB patients. Furthermore, patients with JEB-gen/intermed have had successful local treatment with autologous grafts harvested from areas of revertant skin58. For now, day-to-day management of EB revolves around the prevention of mechanical trauma, wound care, and avoidance of infection. Protective bandaging, padding over bony prominences, and soft/loosefitting clothing can be helpful. Bathing or soaking with ~0.005% sodium hypochlorite (0.5 cup household bleach [6–8.25% sodium hypochlorite] in a full standard bathtub) or 0.25% acetic acid (1 part white vinegar [5% acetic acid] to 20 parts water) may help to reduce bacterial colonization. Antibiotics should be used judiciously, with avoidance of chronic treatment with topical mupirocin or oral antibiotics. Problematic plantar hyperhidrosis in EBS patients may be reduced by the topical application of aluminum chloride hexahydrate, although its effect on blistering is less certain, and injection of botulinum toxin A can decrease plantar blistering and associated pain in individuals with EBS59. A number of dressings are available for cutaneous wounds in EB patients (Table 32.4; see Ch. 145). As a general rule, only those that are non-adhesive or “low-tack” should be applied to EB skin. Soft silicone dressings, some of which incorporate an absorbent foam backing, are widely used. Silver-impregnated dressings may be helpful for heavily colonized or infected wounds, although long-term application should be avoided to minimize systemic silver absorption. Less expensive Vaseline®-impregnated gauze is another suitable dressing for noninfected wounds. Tissue culture-derived artificial skin bioequivalents are also available for use in the management of chronic, recalcitrant ulcers60. Systemic phenytoin inhibits collagenase and has been used in the past in JEB and RDEB patients61, but it was not found to be effective in a randomized controlled trial62. Other systemic drugs that may be of benefit include tetracycline or erythromycin for EBS63 and thalidomide or cyclosporine for symptomatic relief in DEB pruriginosa64,65. There are few reports on the use of systemic retinoids in any form of EB, although these drugs appear to be tolerated, at least in low dosage, in patients with RDEB66. Whether long-term treatment with low-dose systemic retinoids would help to prevent the development of SCCs in RDEB-gen/sev patients remains to be determined. Based on recent findings in animal models, a clinical trial is underway to determine whether the use of a systemic drug that modulates fibrosis may have a therapeutic role in patients with RDEB. Strategies for the medical and surgical management of long-term complications of EB are outlined in Table 32.532,67,68,68a. Multidisciplinary clinics can provide care and support for the wide range of needs that patients with EB and their families have. Families can also obtain helpful information from several support group websites, in particular www.debra.org and www.debra-international.org.

History In 1954, Theresa Kindler described a patient with acral blistering and photosensitivity during infancy, followed later in life by progressive poikiloderma and atrophy. Twenty years later, Weary reported ten members of a single family with similar findings in addition to widespread atopic dermatitis during early childhood and keratotic papules over the joints of the arms and legs that appeared in childhood and persisted indefinitely. Oral involvement and other mucosal manifestations were subsequently emphasized69–73.

Pathogenesis Kindler syndrome is characterized ultrastructurally by basement membrane reduplication and mixed planes of cleavage that can be within basal keratinocytes, through the lamina lucida, and/or below the lamina densa2,74. It results from mutations in the fermitin family homolog 1 gene (FERMT1) encoding kindlin-1, a component of focal adhesions that connect actin filaments in basal keratinocytes to the underlying ECM73–76 (see Ch. 28). Through integrin-mediated signaling, kindlin-1 affects the shape, polarity, adhesion, proliferation, and motility of keratinocytes74. There is also evidence that kindlin-1 has a role in regulating cutaneous epithelial stem cell homeostasis, with loss of kindlin-1 leading to increased risk of skin cancer as well as cutaneous atrophy due to stem cell exhaustion and premature senescence of keratinocytes77.

Clinical Features Erosions are occasionally present at birth, most often on the forearms and shins, and blistering during infancy is most prominent on the hands and feet. In contrast to other forms of EB, skin fragility in Kindler syndrome tends to decrease considerably during childhood. Photosensitivity manifesting as an increased susceptibility to sunburn also

DRESSINGS FREQUENTLY USED IN PATIENTS WITH EPIDERMOLYSIS BULLOSA

Dressing type

Use

Soft silicone dressings (“low-tack”)



Examples®,™

Suitable as primary or secondary dressings in many types of EB May have a foam backing for mechanical protection or to wick exudate away from the wound

Mepitel, Mepilex, Mepilex Transfer, Mepilex Border

Suitable for primary contact



Non-adherent lipido-colloid dressings



Urgotul

Hydrogel dressings



Provide moisture to drier wounds to facilitate healing • May provide relief from pain or itch

Flexigel, Curagel, ActiForm Cool

Foam dressings



Absorptive dressings



Silver-containing dressings



Useful to absorb moderate amounts of wound exudate

Mepilex, Allevyn

Useful to absorb heavy amounts of wound exudate

Eclypse, Sorbion Sana

Clinically infected or highly colonized wounds Avoid prolonged use due to risk of silver absorption

Urgotul SSD, Mepilex AG

Clinically infected or highly colonized wounds

PolyMem, Cutimed Sorbact, Activon Tulle, Suprasorb X + PHMB



Other antimicrobial dressings



Table 32.4 Dressings frequently used in patients with epidermolysis bullosa (EB).  

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MANAGEMENT OF LONG-TERM COMPLICATIONS OF EPIDERMOLYSIS BULLOSA

Complication

Prevention and monitoring/detection

Management

Diligent oral hygiene Antiseptic and fluoride mouthwashes • Periodic evaluation and cleaning by a dentist



Oral and gastrointestinal Excessive caries



Restorative dentistry



Microstomia

Physical therapy “Mouth expanding” devices

• •

Oral ulceration Esophageal strictures

Topical antiseptics, topical NSAIDs, barrier preparations (e.g. sucralfate suspension)



Evaluate dysphagia with contrast studies



Proton pump inhibitors, H2 blockers, prokinetic agents (e.g. metoclopramide, domperidone [not available in the US])

Gastroesophageal reflux disease

Constipation

Dietary modification (soft foods/purées, caloric supplementation) • Fluoroscopically guided balloon dilatation; repeated procedures are often required • In severe and recalcitrant cases, surgical options include colonic interposition •



Ensure adequate fluid intake and dietary fiber

Osmotic laxatives (e.g. containing polyethylene glycol), mineral oil • Avoid suppositories and enemas





Monitor height, weight and body mass index Periodically assess serum zinc, selenium, iron, vitamin D and carnitine levels (e.g. yearly) • Oral supplements to optimize intake of calories, protein, vitamins and minerals



Nutritional Growth retardation/inadequate intake to meet nutritional needs



Consider gastrostomy feedings



Hematologic Anemia due to iron deficiency and chronic inflammation

Monitor CBC and measures of iron stores



Iron supplementation (oral or IV) Consider erythropoietin or darbepoetin alpha • Consider blood transfusion if hemoglobin ≤7–8 g/dl and/or symptomatic • •

Genitourinary and renal Consider annual ultrasound of the urinary tract and urodynamic studies (especially for JEB)

Dilatation procedures as needed to treat obstruction • Avoid unnecessary instrumentation

Urinary outflow obstruction (e.g. urethral or ureteral strictures)





Renal disease (e.g. hydronephrosis, post-infectious glomerulonephritis, renal amyloidosis, IgA nephropathy)



Blood urea nitrogen & serum electrolyte levels, urinalysis and blood pressure evaluation every 6 months in RDEB patients • Adequately treat streptococcal infections



Annual DEXA scan and spinal radiographs beginning at age 5 years in RDEB and JEB patients • Calcium and vitamin D supplementation



Hemodialysis or peritoneal dialysis if renal failure develops

Musculoskeletal Consider IV bisphosphonate therapy

Osteopenia and osteoporosis



Pseudosyndactyly of hands/feet







Periodic total-body skin examinations; for RDEB patients, approximately every 3–6 months beginning at age 10 years and every 3 months after age 16 years • Biopsy or monitor non-healing ulcers (see Fig. 32.13) • Consider taking serial photographs



Periodic ophthalmologic evaluation for patients with eye involvement • Lubricating eye drops



Cushioned splints on hands/forearms and individual wrapping of fingers in RDEB patients

Surgery to release contractures and webbing

Oncologic Cutaneous squamous cell carcinoma

Excision ± skin grafting (sometimes amputation); consider MRI to assess extent of local disease • Consider staging with CT, PET-CT, sentinel lymph node biopsy

Ocular Chronic complications include corneal scarring, symblepharon, ectropion



Surgical procedures, e.g. division of symblepharon, amniotic membrane transplantation

Cardiac Dilated cardiomyopathy

Medical management Supplement selenium and carnitine if deficient

• •

Table 32.5 Management of long-term complications of epidermolysis bullosa (EB)32,67,68. CBC, complete blood count; CT, computed tomography; JEB, junctional EB; MRI, magnetic resonance imaging; NSAID, nonsteroidal anti-inflammatory drug; PET, positron emission tomography; RDEB, recessive dystrophic EB.  

550

Consider annual echocardiography beginning in late childhood for RDEB patients



CHAPTER

Complication

Prevention and monitoring/detection

Management

Psychological and psychiatric





Consider psychological counseling, support groups

Depression and suicidal ideation/ attempts





Consider family counseling, support groups

Disrupted family unit (e.g. via divorce)

Psychological/family counseling Psychiatric evaluation, antidepressant therapy

Table 32.5 Management of long-term complications of epidermolysis bullosa (EB)32,67,68. (cont’d)  

Epidermolysis Bullosa

32

MANAGEMENT OF LONG-TERM COMPLICATIONS OF EPIDERMOLYSIS BULLOSA

improves over time. Reticulated hyperpigmentation and telangiectasias begin to develop in sun-exposed areas during childhood, and after puberty these findings spread to sun-protected sites. A characteristic feature in adult patients with Kindler syndrome is poikiloderma (Fig. 32.19A), which persists throughout life. Tissue paper-like atrophy is frequently seen, particularly on the dorsal surfaces of the hands and feet (Fig. 32.19B,C), and mild webbing of the digits (see Fig. 32.19C) and palmoplantar hyperkeratosis may also be evident. Eczematous dermatitis, typically beginning during infancy and resolving by early childhood, occurs in some patients. Patients with Kindler syndrome often have erosive gingivitis and poor dentition. Mucosal involvement may result in intraoral and corneal scarring, ectropion, colitis, and strictures of the esophagus, urethra, vagina and anus. Patients have an increased risk of SCC of the lip and oral mucosa as well as acral skin73.

Pathology In older patients, skin biopsy specimens show the typical changes of poikiloderma, including epidermal atrophy, vacuolization of the basal cell layer, variable epidermal melanin content, dermal melanophages, and capillary dilation. Immunostaining of skin biopsy specimens with anti-kindlin-1 antibodies often demonstrates a marked reduction or absence of this protein74. Ultrastructural findings are noted above.

$

Differential Diagnosis The predominantly acral distribution of the blisters and associated atrophy and photosensitivity distinguish Kindler syndrome from other forms of EB, although a form of JEB characterized by progressive cutaneous atrophy similar to that in Kindler syndrome has been described78. As poikiloderma becomes apparent during early childhood, the differential diagnosis may include Rothmund–Thomson syndrome and other entities outlined in Table 63.9.

Treatment Management is akin to other forms of EB, with the addition of sun protection and assiduous oral hygiene.

%

Fig. 32.19 Kindler syndrome. A Poikiloderma of the face and neck with “skip” areas. B Erythema and atrophy on the dorsal hand. C Wrinkling due to atrophy and fusion between the fourth and fifth toes. This patient also had ectropion and urethral strictures. C,  

For additional online figures visit www.expertconsult.com

Courtesy, Jean L Bolognia MD.

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REFERENCES 1. Gedde-Dahl T Jr. Epidermolysis Bullosa. A Clinical, Genetic and Epidemiologic Study. Baltimore: Johns Hopkins University Press; 1971. p. 1–180. 2. Fine JD. Epidemiology of inherited epidermolysis bullosa based on incidence and prevalence estimates from the National Epidermolysis Bullosa Registry. JAMA Dermatol 2016;152:1231–8. 3. Fine JD, Bauer EA, Gedde-Dahl T. Inherited epidermolysis bullosa: definition and historical overview. In: Fine JD, Bauer EA, McGuire J, Moshell A, editors. Epidermolysis Bullosa: Clinical, Epidemiologic, and Laboratory Advances, and the Findings of the National Epidermolysis Bullosa Registry. Baltimore: Johns Hopkins University Press; 1999. p. 1–19. 4. Pearson RW. Studies on the pathogenesis of epidermolysis bullosa. J Invest Dermatol 1962;39:551–75. 5. Goldsmith LA, Briggaman RA. Monoclonal antibodies to anchoring fibrils for the diagnosis of epidermolysis bullosa. J Invest Dermatol 1983;81:464–6. 6. Fine JD, Breathnach SM, Hintner H, Katz SI. KF-1 monoclonal antibody defines a specific basement membrane antigenic defect in dystrophic forms of epidermolysis bullosa. J Invest Dermatol 1984;82:3  5–8. 7. Heagerty AHM, Kennedy AR, Leigh IM, et al. Identification of an epidermal basement membrane defect in recessive forms of dystrophic epidermolysis bullosa by LH 7:2 monoclonal antibody: use in diagnosis. Br J Dermatol 1986;115:125–31. 8. Heagerty AHM, Kennedy AR, Eady RAJ, et al. GB3 monoclonal antibody for diagnosis of junctional epidermolysis bullosa. Lancet 1986;1:860. 9. Fine JD, Johnson LB, Suchindran CM. The National Epidermolysis Bullosa Registry. J Invest Dermatol 1994;102:54S–6S. 10. Fine JD, Bauer EA, McGuire J, Moshell A. Epidermolysis Bullosa: Clinical, Epidemiologic, and Laboratory Advances, and the Findings of the National Epidermolysis Bullosa Registry. Baltimore: Johns Hopkins University Press; 1999. p. 520. 11. Bonifas JM, Rothman AL, Epstein E. Linkage of epidermolysis bullosa simplex to probes in the region of keratin gene clusters on chromosomes 12q and 17q. J Invest Dermatol 1991;39:503A. 12. Fine JD, Johnson LB, Suchindran C, et al. The epidemiology of inherited EB: findings within American, Canadian, and European study populations. In: Fine JD, Bauer EA, McGuire J, Moshell A, editors. Epidermolysis Bullosa: Clinical, Epidemiologic, and Laboratory Advances, and the Findings of the National Epidermolysis Bullosa Registry. Baltimore: Johns Hopkins University Press; 1999. p. 101–13. 13. Pfendner E, Uitto J, Fine JD. Epidermolysis bullosa carrier frequencies in the US population. J Invest Dermatol 2001;116:483–4. 14. Fuchs E, Coulombe P, Cheng J, et al. Genetic bases of epidermolysis bullosa simplex and epidermolytic hyperkeratosis. J Invest Dermatol 1994;103(Suppl.):25S–30S. 15. Fuchs EV. The molecular biology of epidermolysis bullosa simplex. In: Fine JD, Bauer EA, McGuire J, Moshell A, editors. Epidermolysis Bullosa: Clinical, Epidemiologic, and Laboratory Advances, and the Findings of the National Epidermolysis Bullosa Registry. Baltimore: Johns Hopkins University Press; 1999. p. 280–99. 15a.  Lin Z, Li S, Feng C, et al. Stabilizing mutations of KLHL24 ubiquitin ligase cause loss of keratin 14 and human skin fragility. Nat Genet 2016;48:1508–16. 16. Pulkkinen L, Uitto J, Christiano AM. The molecular basis of the junctional forms of epidermolysis bullosa. In: Fine JD, Bauer EA, McGuire J, Moshell A, editors. Epidermolysis Bullosa: Clinical, Epidemiologic, and Laboratory Advances, and the Findings of the National Epidermolysis Bullosa Registry. Baltimore: Johns Hopkins University Press; 1999. p. 300–25. 17. Christiano AM, Uitto J. Molecular diagnosis of inherited skin diseases: the paradigm of dystrophic epidermolysis bullosa. Adv Dermatol 1996;11:199–214. 18. Uitto J, Pulkkinen L, Christiano AM. The molecular basis of the dystrophic forms of epidermolysis bullosa. In: Fine JD, Bauer EA, McGuire J, Moshell A, editors. Epidermolysis Bullosa: Clinical, Epidemiologic, and Laboratory Advances, and the Findings of the National Epidermolysis Bullosa Registry. Baltimore: Johns Hopkins University Press; 1999. p. 326–50.

19. Uitto J, Christiano AM. Molecular basis for the dystrophic forms of epidermolysis bullosa: mutations in the type VII collagen gene. Arch Dermatol Res 1994;287:16–22. 20. Titeux M, Pendaries V, Tonasso L, et al. A frequent functional SNP in the MMP1 promoter is associated with higher disease severity in recessive dystrophic epidermolysis bullosa. Hum Mutat 2008;29:267–76. 21. Küttner V, Mack C, Rigbolt KT, et al. Global remodeling of cellular microenvironment due to loss of collagen VII. Mol Syst Biol 2013;9:657. 22. Ortiz-Urda S, Garcia J, Green CL, et al. Type VII collagen is required for Ras-driven epidermal tumorigenesis. Science 2005;307:1773–6. 23. Pourreyron C, Cox G, Mao X, et al. Patients with recessive dystrophic epidermolysis bullosa develop squamous-cell carcinoma regardless of type VII collagen expression. J Invest Dermatol 2007;127:2438–44. 24. Fine JD, Horiguchi Y, Stein DH, et al. Intraepidermal type VII collagen. Evidence for abnormal intracytoplasmic processing of a major basement protein in rare patients with dominant and possibly localized recessive forms of dystrophic epidermolysis bullosa. J Am Acad Dermatol 1990;22:188–95. 25. Christiano AM, Fine JD, Uitto J. Genetic basis of dominantly inherited transient bullous dermolysis of the newborn: a splice site mutation in the type VII collagen gene. J Invest Dermatol 1997;109:811–14. 26. Fine JD, Johnson LB, Cronce D, et al. Intracytoplasmic retention of type VII collagen and dominant dystrophic epidermolysis bullosa: reversal of defect following cessation of or marked improvement in disease activity. J Invest Dermatol 1993;101:232–6. 27. Fine JD. The classification of inherited epidermolysis bullosa: current approach, pitfalls, unanswered questions, and future directions. In: Fine JD, Bauer EA, McGuire J, Moshell A, editors. Epidermolysis Bullosa: Clinical, Epidemiologic, and Laboratory Advances, and the Findings of the National Epidermolysis Bullosa Registry. Baltimore: Johns Hopkins University Press; 1999. p. 20–47. 28. Fine JD, Johnson L, Wright T. Epidermolysis bullosa simplex superficialis: a new variant of epidermolysis bullosa characterized by subcorneal skin cleavage mimicking peeling skin syndrome. Arch Dermatol 1989;125:633–8. 29. Fine JD, Johnson LB, Suchindran C, et al. Cutaneous and skin-associated musculoskeletal manifestations of inherited EB: the National Epidermolysis Bullosa Registry experience. In: Fine JD, Bauer EA, McGuire J, Moshell A, editors. Epidermolysis Bullosa: Clinical, Epidemiologic, and Laboratory Advances, and the Findings of the National Epidermolysis Bullosa Registry. Baltimore: Johns Hopkins University Press; 1999. p. 114–46. 30. Fine JD, Johnson LB, Suchindran C, et al. Extracutaneous features of inherited EB: the National Epidermolysis Bullosa Registry experience. In: Fine JD, Bauer EA, McGuire J, Moshell A, editors. Epidermolysis Bullosa: Clinical, Epidemiologic, and Laboratory Advances, and the Findings of the National Epidermolysis Bullosa Registry. Baltimore: Johns Hopkins University Press; 1999. p. 147–74. 31. Fine JD, Johnson LB, Moshell A, Suchindran C. The risk of selected major extracutaneous outcomes in inherited epidermolysis bullosa: lifetable analyses of the National Epidermolysis Bullosa Registry study population. In: Fine JD, Bauer EA, McGuire J, Moshell A, editors. Epidermolysis Bullosa: Clinical, Epidemiologic, and Laboratory Advances, and the Findings of the National Epidermolysis Bullosa Registry. Baltimore: Johns Hopkins University Press; 1999. p. 193–205. 32. Fine JD, Mellerio J. Extracutaneous manifestations and complications of inherited epidermolysis bullosa. Parts I & II. J Am Acad Dermatol 2009;61:367–402. 33. Fine JD, Johnson LB, Weiner M, et al. Eye involvement in inherited epidermolysis bullosa (EB): experience of the National EB registry. Am J Ophthalmol 2004;138:254–62. 34. Fine JD, Johnson LB, Weiner M, Suchindran C. Gastrointestinal complications of inherited epidermolysis bullosa (EB): experience of the National EB registry. J Pediatr Gastroenterol Nutr 2008;46:147–58. 35. Fine JD, Johnson LB, Weiner M, et al. Tracheolaryngeal complications of inherited epidermolysis bullosa:

cumulative experience of the National EB Registry. Laryngoscope 2007;117:1652–60. 36. Wright JT, Fine JD, Johnson LB. Hereditary epidermolysis bullosa: oral manifestations and dental management. Pediatr Dent 1993;15:242–8. 37. Wright JT. Oral manifestations of epidermolysis bullosa. In: Fine JD, Bauer EA, McGuire J, Moshell A, editors. Epidermolysis Bullosa: Clinical, Epidemiologic, and Laboratory Advances, and the Findings of the National Epidermolysis Bullosa Registry. Baltimore: Johns Hopkins University Press; 1999. p. 236–57. 38. Wright JT, Fine JD, Johnson L. Dental caries risk in hereditary epidermolysis bullosa. Pediatr Dent 1994;16:427–32. 39. Fine JD, Johnson LB, Weiner M, et al. Pseudosyndactyly and musculoskeletal deformities in inherited epidermolysis bullosa (EB): experience of the National Epidermolysis Bullosa Registry, 1986–2002. J Hand Surg [Br] 2005;30:14–22. 40. Fine JD, Johnson LB, Weiner M, et al. Inherited epidermolysis bullosa (EB) and the risk of death from renal disease: experience of the National Epidermolysis Bullosa Registry. Am J Kidney Dis 2004;44:651–60. 41. Fine JD, Hall M, Weiner M, et al. The risk of cardiomyopathy in inherited epidermolysis bullosa. Br J Dermatol 2008;159:677–82. 42. Fine JD, Johnson LB, Suchindran C, et al. Premature death and inherited epidermolysis bullosa: contingency table and lifetable analyses of the National Epidermolysis Bullosa Registry study population. In: Fine JD, Bauer EA, McGuire J, Moshell A, editors. Epidermolysis Bullosa: Clinical, Epidemiologic, and Laboratory Advances, and the Findings of the National Epidermolysis Bullosa Registry. Baltimore: Johns Hopkins University Press; 1999. p. 206–24. 43. Fine JD, Johnson LB, Weiner M, et al. Cause-specific risks of childhood death in inherited epidermolysis bullosa. J Pediatr 2008;152:276–80. 44. Fine JD, Johnson LB, Suchindran C, et al. Cancer and inherited epidermolysis bullosa: lifetable analyses of the National Epidermolysis Bullosa Registry study population. In: Fine JD, Bauer EA, McGuire J, Moshell A, editors. Epidermolysis Bullosa: Clinical, Epidemiologic, and Laboratory Advances, and the Findings of the National Epidermolysis Bullosa Registry. Baltimore: Johns Hopkins University Press; 1999. p. 175–92. 45. Fine JD, Smith LT. Non-molecular diagnostic testing of inherited epidermolysis bullosa: current techniques, major findings, and relative sensitivity and specificity. In: Fine JD, Bauer EA, McGuire J, Moshell A, editors. Epidermolysis Bullosa: Clinical, Epidemiologic, and Laboratory Advances, and the Findings of the National Epidermolysis Bullosa Registry. Baltimore: Johns Hopkins University Press; 1999. p. 48–78. 46. Takeichi T, Liu L, Fong K, et al. Whole-exome sequencing improves mutation detection in a diagnostic epidermolysis bullosa laboratory. Br J Dermatol 2015;172:94–100. 47. Tenedini E, Artuso L, Bernardis I, et al. Amplicon-based NGS: an effective approach for the molecular diagnosis of epidermolysis bullosa. Br J Dermatol 2015;173:  731–8. 48. Fenjves ES. Gene therapy: principles and potential application in inherited epidermolysis bullosa. In: Fine JD, Bauer EA, McGuire J, Moshell A, editors. Epidermolysis Bullosa: Clinical, Epidemiologic, and Laboratory Advances, and the Findings of the National Epidermolysis Bullosa Registry. Baltimore: Johns Hopkins University Press; 1999. p. 407–19. 49. Ortiz-Urda S, Thyagarajan B, Keene DR, et al. PhiC31 integrase-mediated nonviral genetic correction of junctional epidermolysis bullosa. Hum Gene Ther 2003;14:923–8. 50. Mavilio F, Pellegrini G, Ferrari S, et al. Correction of junctional epidermolysis bullosa by transplantation of genetically modified epidermal stem cells. Nat Med 2006;12:1397–402. 50a.  Siprashvili Z, Nguyen NT, Gorrell ES, et al. Safety and wound outcomes following genetically corrected autologous epidermal grafts in patients with recessive dystrophic epidermolysis bullosa. JAMA 2016;316:1808–17. 50b.  Shinkuma S, Guo Z, Christiano AM. Site-specific genome editing for correction of induced pluripotent stem cells derived from dominant dystrophic epidermolysis bullosa. Proc Natl Acad Sci USA 2016;113:5676–81.

61. Fine JD, Johnson L. Efficacy of systemic phenytoin in the treatment of junctional epidermolysis bullosa. Arch Dermatol 1988;124:1402–6. 62. Caldwell-Brown D, Stern RS, Lin AN, Carter DM. Lack of efficacy of phenytoin in recessive dystrophic epidermolysis bullosa. N Engl J Med 1992;327:163–7. 63. Fine JD, Eady RAJ. Tetracycline and epidermolysis bullosa simplex – a new indication for one of the oldest and most widely used drugs in dermatology? Arch Dermatol 1999;135:981–2. 64. Ozanic BS, Fassihi H, Mellerio J, et al. Thalidomide in the management of epidermolysis bullosa pruriginosa. Br J Dermatol 2005;152:1332–4. 65. Yamasaki H, Tada J, Yoshioka T, Arata J. Epidermolysis bullosa pruriginosa (McGrath) successfully controlled by oral cyclosporin. Br J Dermatol 1994;130:717–25. 66. Fine JD, Weiner M, Stein A, et al. Systemic isotretinoin and recessive dystrophic epidermolysis bullosa (RDEB): results of a Phase 1 clinical trial. J Invest Dermatol 2001;117:543. 67. Fine JD, Bauer EA, McGuire J. The treatment of inherited epidermolysis bullosa: nonmolecular approaches. In: Fine JD, Bauer EA, McGuire J, Moshell A, editors. Epidermolysis Bullosa: Clinical, Epidemiologic, and Laboratory Advances, and the Findings of the National Epidermolysis Bullosa Registry. Baltimore: Johns Hopkins University Press; 1999. p. 374–406. 68. Fine JD, McGuire J. Altered nutrition and inherited epidermolysis bullosa. In: Fine JD, Bauer EA, McGuire J, Moshell A, editors. Epidermolysis Bullosa: Clinical, Epidemiologic, and Laboratory Advances, and the Findings of the National Epidermolysis Bullosa Registry. Baltimore: Johns Hopkins University Press; 1999. p. 225–35. 68a.  Mellerio JE, Robertson SJ, Bernardis C, et al. Management of cutaneous squamous cell carcinoma in patients with epidermolysis bullosa: best clinical practice guidelines. Br J Dermatol 2016;174:56–67.

69. Forman AB, Prendiville JS, Esterly NB, et al. Kindler syndrome: report of two cases and review of the literature. Pediatr Dermatol 1989;6:91–101. 70. Patrizi A, Pauluzzi P, Neri I, et al. Kindler syndrome: report of a case with ultrastructural study and review of the literature. Pediatr Dermatol 1996;13:397–402. 71. Penagos H, Jaen M, Sancho MT, et al. Kindler syndrome in native Americans from Panama: report of 26 cases. Arch Dermatol 2004;140:939–44. 72. Wiebe CB, Penagos H, Luong N, et al. Clinical and microbiologic study of periodontitis associated with Kindler syndrome. J Periodontol 2003;74:25–31. 73. Has C, Castiglia D, del Rio M, et al. Kindler syndrome: extension of FERMT1 mutational spectrum and natural history. Hum Mutat 2011;32:1204–12. 74. Lai-Cheong JE, Tanaka A, Hawche G, et al. Kindler syndrome: a focal adhesion genodermatosis. Br J Dermatol 2009;160:233–42. 75. Jobard F, Bouadjar B, Caux F, et al. Identification of mutations in a new gene encoding a FERM family protein with a pleckstrin homology domain in Kindler syndrome. Hum Mol Genet 2003;12:925–35. 76. Siegel DH, Ashton GHS, Penagos HG, et al. Loss of kindlin-1, a human homolog of the Caenorhabditis elegans actin-extracellular-matrix linker protein UNC-112, causes Kindler syndrome. Am J Hum Genet 2003;73:174–87. 77. Rognoni E, Widmaier M, Jakobson M, et al. Kindlin-1 controls Wnt and TGF-β availability to regulate cutaneous stem cell proliferation. Nat Med 2014;20:350–9. 78. Has C, Kiritsi D, Mellerio JE, et al. The missense mutation p.R1303Q in type XVII collagen underlies junctional epidermolysis bullosa resembling Kindler syndrome. J Invest Dermatol 2014;134:845–9.

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32 Epidermolysis Bullosa

51. Woodley DT, Remington J, Huang Y, et al. Intravenously injected human fibroblasts home to skin wounds, deliver type VII collagen, and promote wound healing. Mol Ther 2007;15:628–35. 52. Remington J, Wang X, Hou Y, et al. Injection of recombinant human type VII collagen corrects the disease phenotype in a murine model of dystrophic epidermolysis bullosa. Mol Ther 2009;17:26–33. 53. Petrof G, Martinez-Queipo M, Mellerio JE, et al. Fibroblast cell therapy enhances initial healing in recessive dystrophic epidermolysis bullosa wounds: results of a randomized, vehicle-controlled trial. Br J Dermatol 2013;169:1025–33. 54. Tolar J, Ishida-Yamamoto A, Riddle M, et al. Amelioration of epidermolysis bullosa by transfer of wild-type bone marrow cells. Blood 2009;29:1167–74. 55. Wagner JE, Ishida-Yamamoto A, McGrath JA, et al. Bone marrow transplantation for recessive dystrophic epidermolysis bullosa. N Engl J Med 2010;363:629–39. 56. Petrof G, Lwin SM, Martinez-Queipo M, et al. Potential of systemic allogeneic mesenchymal stromal cell therapy for children with recessive dystrophic epidermolysis bullosa. J Invest Dermatol 2015;135:2319–21. 57. Jonkman MF. Pasmooij AM. Revertant mosaicism: patchwork in the skin. N Engl J Med 2009;360:1680–2. 58. Gostyński A, Pasmooij AM, Jonkman MF. Successful therapeutic transplantation of revertant skin in epidermolysis bullosa. J Am Acad Dermatol 2014;70:98–101. 59. Swartling C, Karlqvist M, Hymnelius K, et al. Botulinum toxin in the treatment of sweat-worsened foot problems in patients with epidermolysis bullosa simplex and pachyonychia congenita. Br J Dermatol 2010;163:1072–6. 60. Fine JD. Skin bioequivalents and their role in the treatment of inherited epidermolysis bullosa [Editorial]. Arch Dermatol 2000;136:1259–60.

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eFig. 32.1 Generalized severe epidermolysis bullosa simplex. Clustered vesicles in an arcuate array on the arm of this child. Courtesy, Julie V

Epidermolysis Bullosa



Schaffer, MD.

eFig. 32.3 Palmar keratoderma in skin fragility-ectodermal dysplasia syndrome due to plakophilin 1 deficiency. Note the fissuring and accentuation in areas of friction. Courtesy, Antonia Torrelo, MD.  

eFig. 32.2 Skin fragility–ectodermal dysplasia syndrome due to plakophilin 1 deficiency. Macerated hyperkeratosis and fissures in the perineal area. Courtesy,  

Antonio Torrelo, MD.

553.e1

SECTION 5 VESICULOBULLOUS DISEASES

33 

Other Vesiculobullous Diseases José M. Mascaró Jr

Chapter Contents Bullosis diabeticorum . . . . . . . . . . . . . . . . . . . . . . . . . . . . 554 Coma blisters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 555 Friction blisters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 556 Bullous small vessel vasculitis . . . . . . . . . . . . . . . . . . . . . . . 557 Bullous drug eruptions . . . . . . . . . . . . . . . . . . . . . . . . . . . 557 Bullous insect bite reactions . . . . . . . . . . . . . . . . . . . . . . . . 557 Delayed postburn/postgraft blisters . . . . . . . . . . . . . . . . . . . 559 Edema blisters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 560 Additional vesiculobullous disorders . . . . . . . . . . . . . . . . . . 560

Vesiculobullous diseases of the skin encompass a wide range of entities, including autoimmune bullous diseases and inherited blistering disorders (see Chs 28–32). This chapter focuses on the remaining noninfectious disorders in which cutaneous bullae develop and represent the primary clinical manifestation.

BULLOSIS DIABETICORUM Synonyms:  ■ Diabetic bullae ■ Bullous eruption of diabetes mellitus

have found a reduced threshold for inducing suction blisters in these patients3,4. There is no evidence of an infectious etiology.

Clinical Features Bullosis diabeticorum is characterized by a sudden and spontaneous appearance of vesicles and bullae within normal-appearing, noninflamed skin of the distal extremities of diabetics. The most frequent locations (in decreasing order) are the feet, distal legs, hands, and forearms. Bullae are rarely seen on the trunk. The lesions are usually asymptomatic, but occasionally there is a mild burning sensation. Blisters often develop “overnight” and in the absence of known trauma. The vesicles and bullae are tense and vary in diameter from 0.5 to several centimeters (Fig. 33.1). They contain a clear, sterile fluid that can be more viscous than that found in friction blisters. Most patients have longstanding diabetes, but occasionally bullosis diabeticorum is a presenting sign of diabetes. It is associated with both insulin-dependent and non-insulin-dependent diabetes mellitus. Many patients have an associated polyneuropathy, retinopathy or nephropathy.

Pathology The histologic findings are heterogeneous. Initial reports described intraepidermal blisters, whereas recent publications have usually described subepidermal bullae. It has been suggested that the level of cleavage is subepidermal, and that intraepidermal blisters represent older lesions undergoing re-epithelialization. Direct immunofluorescence (DIF) examination is usually negative, although one report described IgM and C3 deposits within dermal blood vessel walls. By electron microscopy, subepidermal blisters with a separation at the level of the lamina lucida or below the lamina densa have been described5.

Key features

Differential Diagnosis

■ A rare condition associated with diabetes mellitus ■ Tense blisters develop on normal-appearing skin in acral sites (feet, lower legs, hands); there is often an association with peripheral neuropathy ■ Histologically, intraepidermal and/or subepidermal blisters are observed ■ Spontaneous healing usually occurs in 2 to 6 weeks

In porphyria cutanea tarda (PCT) and pseudoporphyria associated with dialysis and medications, the blisters are usually β-lactams, captopril, NSAIDs • Bullous pemphigoid: diuretics (especially furosemide), antibiotics • Pemphigus: captopril, β-lactams, penicillamine, gold NSAIDs (especially naproxen), nalidixic acid, thiazides, furosemide, tetracyclines β-lactams, macrolides, pristinamycin, terbinafine, calcium channel blockers (diltiazem), hydroxychloroquine, carbamazepine, acetaminophen, metronidazole

Tetracyclines (especially doxycycline), quinolones, psoralens, NSAIDs, diuretics



Table 33.1 Bullous drug eruptions. Occasionally, eczematous drug reactions (e.g. secondary to warfarin, calcium channel blockers) and systemic contact dermatitis can be papulovesicular; patients with drug reaction with eosinophilia and systemic symptoms (DRESS)/drug-induced hypersensitivity syndrome (DIHS) can also develop vesicles. Coma blisters and bullous small vessel vasculitis are discussed in the text. NSAIDs, nonsteroidal anti-inflammatory drugs.  

cell-mediated immunity (delayed hypersensitivity) are involved. Initial bites typically do not produce significant lesions, but sensitization occurs over a few weeks. Subsequent bites then induce a stronger reaction and even bullae formation. With time, repeated bites can result in desensitization. In the case of bullous bed bug reactions, cutaneous vasculitis may be playing a role21. In patients with NK/T-cell lymphomas, severe hypersensitivity to mosquito bites has been well documented and a possible role for the EBV-induced clonal proliferation of NK cells has been raised22. For patients with ALK-positive anaplastic large cell lymphoma, the possibility has been raised that insect bite-associated antigens lead to an influx of T lymphocytes, some of which bear t(2;5). The release of cytokines then results in activation of these cells, expression of NPM-ALK (nucleophosmin–anaplastic lymphoma kinase) fusion protein, and subsequent uncontrolled proliferation23. Malignant B cells, on the other hand, may stimulate Th2 cells to produce interleukin-5, explaining the associated tissue eosinophilia.

Clinical Features 558

Insect bites usually appear as intensely pruritic erythematous papules or nodules. They are usually grouped, and a linear arrangement is commonly seen. However, vesicular and bullous bite reactions are not uncommon, and blisters can develop centrally within papules or as

Fig. 33.7 Ofloxacin-induced linear IgA bullous dermatosis. This represents one form of bullous drug eruption. Although the initial clinical diagnosis was Stevens–Johnson syndrome or toxic epidermal necrolysis, the annular configuration and peripheral location of the bullae plus the histologic and DIF findings lead to the diagnosis of linear IgA bullous dermatosis.  

bland vesiculobullae (Fig. 33.8). Flea bites are the most likely to cause blisters, especially on the legs, and bedbug bites can also be bullous. Some insects (e.g. fire ants) can produce pustular lesions. In patients with hematologic malignancies, the exaggerated reactions consist of persistent papulonodules, vesicles, bullae, and even necrotic lesions (Fig. 33.9).

Treatment Most patients with bullous insect bites can be managed with drainage of blisters plus topical corticosteroids and systemic antihistamines to relieve pruritus. In the most severe reactions, a short course of systemic corticosteroids may be necessary. While systemic corticosteroids can lead to improvement of exaggerated reactions, lesions tend to recur when the dose is reduced. Dapsone has been suggested as a therapeutic option for these patients25. Protective clothing and insect repellants are an important intervention (see Ch. 85).

CHAPTER

33 Other Vesiculobullous Diseases

“eosinophilic dermatosis of myeloproliferative disease” is less appropriate, as CLL is not a myeloproliferative disorder nor is lymphoma.

DELAYED POSTBURN/POSTGRAFT BLISTERS Key features Fig. 33.8 Bullous insect bite reactions. The sterile blister fluid is serous and the ankle is a common site. Courtesy, Luis Requena, MD.  

Fig. 33.9 Exaggerated insect bite-like reactions in a patient with chronic lymphocytic leukemia. There are multiple vesicles and hemorrhagic crusts on an inflammatory base.

■ Delayed postburn and postgraft blisters represent an underreported condition ■ Tense blisters develop weeks to months after the initial injury has healed ■ Blistering can persist for several weeks or months



Introduction Delayed blisters have been observed weeks to months after the initial healing of second-degree thermal burns, donor sites of split-thickness skin grafts, and recipient sites of split-thickness skin grafts26,27.

History The first report of this phenomenon is attributed to Barker and Cotterill in 1980.

Epidemiology Delayed blisters have received little attention in the literature. However, it appears to occur to some degree in almost every patient with a thermal burn involving more than 30% of the body surface area27. Most descriptions refer to patients with thermal burns, where delayed blisters have been observed on the spontaneously healed skin, graft donor sites, and graft recipient sites26. They have also been seen after skin grafting for toxic epidermal necrolysis and within laser-resurfaced skin28.

Pathogenesis Pathology The typical pattern is that of a superficial and deep perivascular and periadnexal lymphocytic infiltrate with abundant eosinophils. A wedgeshaped pattern is characteristic. During the initial phase, intraepidermal spongiotic vesicles are present and they can be associated with eosinophilic spongiosis. With time, confluence of these vesicles leads to subepidermal blisters. Sometimes, epidermal necrosis develops. Flame figures (extruded eosinophilic granules aggregated onto collagen fibers that are classically associated with eosinophilic cellulitis) can be observed, particularly in the exaggerated reactions seen in patients with hematologic malignancies.

The exact pathogenesis is not known. The antigenic components of the normal dermal–epidermal junction appear sequentially during fetal life or wound healing. Therefore, it has been hypothesized that this phenomenon is due to the enhanced fragility of a newly synthesized, “immature” dermal–epidermal junction26,27.

Clinical Features Tense vesicles or blisters develop several weeks after the injured skin (burned, donor site, recipient site) has completely healed. In one study, blisters appeared between 19 and 55 days after the patients had sustained their burns, with an average of 37 days27. Blisters do not develop within uninvolved skin. Although they heal spontaneously, there is a tendency for recurrences over a period of weeks to months.

Differential Diagnosis

Pathology

The presence of intense pruritus and lesion distribution usually suggests a bullous bite reaction. However, these reactions can mimic bullous pemphigoid, linear IgA bullous dermatosis, bullous erythema multiforme, bullous impetigo, allergic contact dermatitis, or even viral infections. Of note, the exaggerated reactions described above are also referred to as “eosinophilic dermatosis associated with hematological disorders” or “eosinophilic dermatosis of hematologic malignancy”24; the term

Histologically, subepidermal blisters with a minimal inflammatory infiltrate are seen. Electron microscopy has shown that the blisters occur either in the dermis (below the dermal–epidermal junction) or intraepidermally through the basal keratinocytes. DIF studies have been negative. Immunofluorescence mapping has shown a diminished or variable expression of dermal–epidermal junction antigens, including type IV and type VII collagens, laminin, and bullous pemphigoid antigen26.

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SECTION

Vesiculobullous Diseases

5

Differential Diagnosis Blistering associated with a healed injured site can also be due to herpetic infection, ischemia (in the case of graft recipient sites), or autoimmune bullous diseases. Herpetic infection can be excluded by a negative Tzanck smear, direct fluorescent antibody test, viral culture, PCR, and/or biopsy findings; ischemia is diagnosed on the basis of clinical findings; and autoimmune blistering diseases can be excluded by histologic features and DIF/IIF examination (see Fig. 33.5).

Treatment These blisters heal spontaneously with simple care, topical antibiotics, wound dressings, and local compression.

EDEMA BLISTERS Synonyms:  ■ Edema bullae ■ Stasis blisters ■ Hydrostatic bullae

Key features ■ Edema blisters develop in patients with an acute exacerbation of chronic edema, particularly of the lower extremities, and in the setting of anasarca ■ The tense bullae are usually non-inflammatory, but are surrounded by edematous skin ■ Blisters resolve when the edema resolves

Epidemiology This phenomenon has received little attention in the literature. These blisters are not infrequent and usually develop in elderly and immobile hospitalized patients as well as in the setting of anasarca. In a study of 13 patients, the mean age was 74 years29.

Fig. 33.10 Edema bullae on the thigh of an infant. The bullae are tense and are surrounded by edematous skin. Desquamation from a ruptured bulla is also seen.  

ADDITIONAL VESICULOBULLOUS DISORDERS

Disorder

Characteristic features

Bullous dermatitis artefacta (self-inflicted injury)30,31



PUVA-induced acrobullous dermatosis



Fracture blisters



Sucking blisters



Pathogenesis The bullae usually develop on the legs in association with an acute exacerbation of chronic edema. Edema develops when the capillary filtration rate exceeds lymphatic drainage. This can be due to hypoalbuminemia, congestive heart failure, renal disease, hepatic cirrhosis, venous occlusion (thrombosis) or drugs, particularly calcium channel blockers. Cutaneous vesicles and bullae also occur with acute exacerbations of lymphedema.

Clinical Features Due to dependency, most patients develop blisters on the distal lower extremities, particularly the dorsum of the foot and ankle. With acute exacerbations of chronic edema, blisters appear and enlarge slowly to reach a diameter of up to several centimeters. The bullae are tense and asymptomatic, and the surrounding skin is edematous. The sterile blister fluid is usually clear, but it can be serous or bloody. In patients with anasarca, there is a more widespread distribution (Fig. 33.10).

Can be produced by a thermal, electrical, or chemical burn as well as application of a vesicant, coolant, or “salt and ice” (see Ch. 88) • Histologic features vary depending upon etiology, but the most common pattern is a subepidermal blister with epidermal necrosis +/− dermal damage Sudden appearance of sterile, tense blisters, usually on the distal extremities • Due to weakening of epidermal–dermal cohesion plus friction or trauma • DDx: phototoxicity (more widespread) and PUVA-induced bullous pemphigoid Tense bullae that develop within edematous skin and overlie bony fractures • Most common sites: distal tibia, ankle, foot, elbow, wrist • Thought to be due to shearing forces related to the injury plus post-traumatic edema Seen in newborns in areas accessible to the infant’s mouth, e.g. forearm • Develop in utero

Table 33.2 Additional vesiculobullous disorders. DDx, differential diagnosis.  

Pathology Marked epidermal spongiosis is observed, with dilated dermal blood vessels and a mild inflammatory infiltrate. The dermis is markedly edematous with wide separation of collagen bundles. In some cases, a subepidermal blister is observed. DIF is negative.

Differential Diagnosis

560

Blistering in the setting of acute edema is usually not difficult to diagnose. However, the possibility of bullous pemphigoid, bullosis diabeticorum, or a bullous drug eruption must also be considered. The correct diagnosis can usually be established via the clinical history and physical examination (Fig. 33.5). If needed, bullous pemphigoid can be excluded by negative DIF and IIF examinations.

Treatment These blisters resolve rapidly when the cause of the edema is successfully treated. Diuretics, discontinuation of calcium channel blockers, leg elevation, and compressive bandages (followed by maintenance compression hose) may prove helpful.

ADDITIONAL VESICULOBULLOUS DISORDERS These are summarized in Table 33.2. For additional online figures visit www.expertconsult.com

CHAPTER

1. Cantwell AR Jr, Martz W. Idiopathic bullosis in diabetics. Bullous diabeticorum. Arch Dermatol 1967;96:42–4. 2. Larsen K, Jensen T, Karlsmark T, Holstein PE. Incidence of bullosis diabeticorum – a controversial cause of chronic foot ulceration. Int Wound J 2008;5:591–6. 3. Toonstra J. Bullosis diabeticorum. Report of a case with a review of the literature. J Am Acad Dermatol 1985;13:799–805. 4. Bernstein JE, Levine LE, Medenica MM, et al. Reduced threshold to suction-induced blister formation in insulin-dependent diabetics. J Am Acad Dermatol 1983;8:790–1. 5. Lipsky BA, Baker PD, Ahroni JH. Diabetic bullae: 12 cases of a purportedly rare cutaneous disorder. Int J Dermatol 2000;39:196–200. 6. Holten C. Cutaneous phenomena in acute barbiturate poisoning. Acta Derm Venereol (Stockh) 1952;32(Suppl. 29):162–8. 7. Beveridge GW, Lawson AAH. Occurrence of bullous lesions in acute barbiturate intoxication. Br Med J 1965;5438:835–7. 8. Taniguchi Y, Wada Y, Takahashi M, et al. Multiple bullae and paresis after drug-induced coma. Acta Derm Venereol 1991;71:536–8. 9. Branco MM, Capitani EM, Cintra ML, et al. Coma blisters after poisoning caused by central nervous system depressants: case report including histopathological findings. An Bras Dermatol 2012;87:615–17. 10. Mehregan DR, Daoud M, Rogers RS III. Coma blisters in a patient with diabetic ketoacidosis. J Am Acad Dermatol 1992;27:269–70. 11. Chacon AH, Farooq U, Choudhary S, et al. Coma blisters in two postoperative patients. Am J Dermatopathol 2013;35:381–4. 12. Arndt KA, Mihm MC Jr, Parrish JA. Bullae: a cutaneous sign of a variety of neurologic diseases. J Invest Dermatol 1973;60:312–20.

13. Miyamoto T, Ikehara A, Kobayashi T, et al. Cutaneous eruptions in coma patients with nontraumatic rhabdomyolysis. Dermatology 2001;203:  233–7. 14. Brennan FH Jr, Jackson CR, Olsen C, Wilson C. Blisters on the battlefield: the prevalence of and factors associated with foot friction blisters during Operation Iraqi Freedom I. Mil Med 2012;177:157–62. 15. Knapik JJ, Reynolds KL, Duplantis KL, et al. Friction blisters. Pathophysiology, prevention, and treatment. Sports Med 1995;20:136–47. 16. Sulzberger MB, Cortese TA Jr, Fishman L, et al. Studies on blisters produced by friction. I. Results of linear rubbing and twisting technics. J Invest Dermatol 1966;47:456–65. 17. Galve J, Gual A, Guilabert A, Mascaró JM. A 32-year-old man with grouped papules and vesicles—Quiz case. Arch Dermatol 2012;148:849–54. 18. Davis MD, Perniciaro C, Dahl PR, et al. Exaggerated arthropod-bite lesions in patients with chronic lymphocytic leukemia: a clinical, histopathologic, and immunopathologic study of eight patients. J Am Acad Dermatol 1998;39:27–35. 19. Barzilai A, Shapiro D, Goldberg I, et al. Insect bite-like reaction in patients with hematologic malignant neoplasms. Arch Dermatol 1999;135:1503–7. 20. Bairey O, Goldschmidt N, Ruchlemer R, et al. Insect-bitelike reaction in patients with chronic lymphocytic leukemia: a study from the Israeli Chronic Lymphocytic Leukemia Study Group. Eur J Haematol 2012;89:  491–6. 21. deShazo RD, Feldlaufer MF, Mihm MC Jr, Goddard J. Bullous reactions to bedbug bites reflect cutaneous vasculitis. Am J Med 2012;125:688–94. 22. Tsuge I, Morishima T, Morita M, et al. Characterization of Epstein-Barr virus (EBV)-infected natural killer (NK) cell proliferation in patients with severe mosquito allergy;

23.

24. 25.

26.

27. 28. 29. 30.

31.

establishment of an IL-2-dependent NK-like cell line. Clin Exp Immunol 1999;115:385–92. Lamant L, Pileri S, Sabattini E, et al. Cutaneous presentation of ALK-positive anaplastic large cell lymphoma following insect bites: evidence for an association in five cases. Haematologica 2010;95:449–55. Farber MJ, La Forgia S, Sahu J, Lee JB. Eosinophilic dermatosis of hematologic malignancy. J Cutan Pathol 2012;39:690–5. Ulmer A, Metzler G, Schanz S, Fierlbeck G. Dapsone in the management of “insect bite-like reaction” in a patient with chronic lymphocytic leukaemia. Br J Dermatol 2007;156:172–4. Chetty BV, Boissy RE, Warden GD, et al. Basement membrane and fibroblast aberration in blisters at the donor, graft, and spontaneously healed sites in patients with burns. Arch Dermatol 1992;128:181–6. Compton CC. The delayed postburn blister. A commonplace but overlooked phenomenon. Arch Dermatol 1992;128:249–52. Alora MB, Dover JS. Spontaneous bullae over laser resurfaced skin. J Am Acad Dermatol 2000;42:  288–90. Bhushan M, Chalmers RJG, Cox NH. Acute oedema blisters: a report of 13 cases. Br J Dermatol 2001;144:580–2. Jacobi A, Bender A, Hertl M, König A. Bullous cryothermic dermatitis artefacta induced by deodorant spray abuse. J Eur Acad Dermatol Venereol 2011;25:978–82. Sokumbi O, Comfere NI, McEvoy MT, Peters MS. Bullous dermatitis artefacta. Am J Dermatopathol 2013;35:110–12.

33 Other Vesiculobullous Diseases

REFERENCES

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Online only content

CHAPTER

Other Vesiculobullous Diseases

33

eFig. 33.2 Fracture blisters. Sterile bland bullae develop in areas of edema following bone fractures. Courtesy, Ian Odell, MD, PhD.  

eFig. 33.1 Bullous bug bite reaction – histopathologic features. In addition to intense papillary dermal edema, there is a prominent perivascular mononuclear cell infiltrate in the upper and mid dermis. Note the basket-weave pattern of the stratum corneum, suggesting an acute process. Courtesy, Lorenzo Cerroni, MD.  

eFig. 33.3 Friction blisters. Tense blisters that developed on the shin of the author after continuous rubbing against a ski boot.  

eFig. 33.4 Bullous variant of cutaneous small vessel vasculitis.  

Courtesy, Jean L Bolognia, MD.

561.e1

SECTION 5 VESICULOBULLOUS DISEASES

34 

Vesiculopustular and Erosive Disorders in Newborns and Infants Renee M. Howard and Ilona J. Frieden

A wide variety of conditions can cause vesicles, pustules, bullae, erosions, and ulcerations during the newborn period and infancy. Accurate and prompt diagnosis is important because some of the underlying disorders represent potentially life-threatening infections; conversely, many are benign and self-limited. Therefore, it is essential to develop a systematic approach to the evaluation and treatment of newborns and infants with these types of skin lesions. An algorithm outlining initial and subsequent investigations is presented in Fig. 34.1. This chapter highlights many causes of vesiculopustular and erosive eruptions during the first year of life, and more exhaustive lists are provided in Tables 34.1 and 34.2. The majority of infectious etiologies are also covered in Chapters 74–82.

COMMON CAUSES Erythema Toxicum Neonatorum Synonyms:  ■ Erythema toxicum ■ Toxic erythema of the newborn

Key features ■ Vesiculopustular eruption characterized by an eosinophilic infiltrate ■ Affects nearly half of full-term neonates and resolves spontaneously over a few days ■ Often involves the trunk as well as the face, proximal limbs, and buttocks ■ Almost always spares the palms and soles ■ Small wheals, inflammatory papules, pustules, and/or vesicles surrounded by blotchy erythema Erythema toxicum neonatorum (ETN) is a very common, benign condition. Originally described by Netlinger in 1472, it was known as “toxic erythema of the newborn” and was renamed erythema toxicum neonatorum by Leiner in 19121. ETN occurs in approximately half of fullterm neonates and only rarely in premature infants or those weighing less than 2500 g2,3.

BEDSIDE TESTS FOR THE DIAGNOSIS OF VESICLES OR PUSTULES IN A NEWBORN

Vesicles or pustules in a newborn

Wright or Giemsa stain (vesicle/pustule contents)

Primarily eosinophils If widespread/ waxing & waning: Likely erythema toxicum neonatorum If linear streaks: Likely incontinentia pigmenti If mainly on scalp with pruritus: Consider eosinophilic pustular folliculitis

562

Primarily neutrophils and – Gram stain, – KOH

Other

If widespread superficial pustules present at birth: Likely transient neonatal pustular melanosis

Large histiocytes with reniform nuclei: Likely Langerhans cell histiocytosis

Skin biopsy to confirm diagnosis

If localized to hands and feet with pruritus: Consider infantile acropustulosis

Gram stain (vesicle/pustule contents)

+ Bacteria:

Immature myeloid cells, especially if high WBC and Down syndrome: Consider transient myeloproliferative disorder

*

*Typically in infants 3−4 weeks of age Fig. 34.1 Bedside tests for the diagnosis of vesicles or pustules in a newborn.  

Bacterial infection (e.g. staphylococcal)

Bacterial culture of skin and additional sites as indicated Begin empiric therapy based on Gram stain findings and clinical context

KOH prep or PAS stain (scraping from pustule roof or scale) + Pseudohyphae & budding yeast: Candidiasis, congenital or neonatal

Culture skin and other relevant sites (e.g. mouth, perianal area) If premature with birth weight vesicles, wheals

Any region, except almost always spares palms/soles

Clinical; Wright’s stain: eosinophils

Term infants >2500 g

Transient neonatal pustular melanosis (Fig. 34.4)

Birth

Pustules without erythema; collarettes of scale; hyperpigmented macules

Any region; most often forehead, neck, lower back, shins; may affect palms/soles

Clinical; Wright’s stain: neutrophils, occasional eosinophils, cellular debris

Term infants; more common in infants of African descent

Miliaria crystallina (see Ch. 39) (Fig. 34.5A)

Birth to early infancy

Fragile vesicles without erythema

Forehead, upper trunk, arms most common

Clinical

Sometimes history of overheating or fever

Miliaria rubra (see Ch. 39) (Fig. 34.5B)

Typically ≥1 week

Erythematous papules with superimposed pustules

Forehead, neck, upper trunk; occluded areas most common

Clinical; Wright’s stain: variable inflammatory cells but not prominent eosinophils

Sometimes history of overheating or fever

Neonatal cephalic pustulosis (neonatal “acne”) (Fig. 34.6)

~5 days to 3 weeks

Papules and pustules on erythematous base

Cheeks, forehead, chin, eyelids; less commonly neck, upper chest, scalp

Clinical; Giemsa stain: yeast forms, neutrophils

Otherwise well

Uncommon and rare non-infectious diseases Acropustulosis of infancy (Fig. 34.10)

Typically 3–6 months, occasionally birth to weeks

Vesicles and pustules

Hands and feet; occasionally scalp, trunk

Clinical; assess for scabies infestation; skin biopsy: intraepidermal vesicle/ pustule with neutrophils and occasionally eosinophils

Severe pruritus; lesions recur in crops; subset with prior scabies

Eosinophilic pustular folliculitis of infancy (Fig. 34.11)

Birth to 14 months, mean 6 months

Papules and pustules

Scalp > face > trunk, extremities

Skin biopsy: dense mixed infiltrate with eosinophils, often but not invariably centered on hair follicles

Pruritus; lesions recur in crops; often peripheral eosinophilia; neonatal eosinophilic pustulosis variant favors the face in premature boys

Congenital and neonatal Langerhans cell histiocytosis (see Ch. 91) (Fig. 34.12)

Birth to weeks

Vesicles, crusts, papules, nodules, petechiae

Any body region, especially flexural sites, palms/soles, scalp

Skin biopsy: S100+/ CD1a+ histiocytes with reniform nuclei, focal invasion of epidermis

Occasional mucosal or extracutaneous involvement; pure cutaneous form often resolves spontaneously, but later cutaneous and systemic relapses possible

Incontinentia pigmenti (see Ch. 62) (Fig. 34.13)

Birth to weeks

Vesicles, hyperkeratotic papules along the lines of Blaschko

Vesicular lesions most common on the extremities

Skin biopsy: eosinophilic spongiosis with necrotic keratinocytes; genetic analysis (IKBKG/NEMO)

Ocular, CNS, and dental involvement common but often not evident at birth; X-linked dominant, patients usually female

Autosomal dominant hyper-IgE syndrome (see Ch. 60)

Birth to weeks

Single and grouped vesicles or papulopustules

Face, scalp, upper trunk, axillae, diaper area

Skin biopsy: intraepidermal vesicle with eosinophils, eosinophilic folliculitis; genetic analysis (STAT3)

Eosinophilia with variably elevated IgE levels; abscesses, pneumonias, and pneumatoceles often develop after neonatal period

Table 34.1 Differential diagnosis of vesiculopustular diseases. (cont’d) CNS, central nervous system;.  

564

CHAPTER

Usual age of onset

Disease

Skin: morphology

Skin: distribution

Diagnostic studies (skin)

Comments

Uncommon and rare non-infectious diseases Vesiculopustular eruption of transient myeloproliferative disorder in Down syndrome

Days to weeks

Vesicles and pustules

Face > trunk, extremities; sites of adhesive dressings, minor trauma

Intraepidermal spongiotic vesiculopustules, infiltrate containing immature myeloid cells

Trisomy 21 or mosaicism for trisomy 21; severe leukocytosis with immature myeloid cells; increased risk of myeloid leukemia

Erosive pustular dermatosis of the scalp

Weeks to months

Pustules, erythema with scale-crust, erosions; alopecia and scarring

“Halo scalp ring” pattern, vertex of scalp

Clinical; skin biopsy: alopecia, scarring, mixed dermal infiltrate

Prolonged labor and delivery; necrotic caput succedaneum at birth

Neonatal Behçet disease (see Ch. 26)

First week

Vesiculopustular, purpuric and necrotic skin lesions; oral and genital ulcers

Lesions favor hands and feet as well as oral and genital mucosae

Clinical

Maternal history of Behçet disease; diarrhea, vasculitis

Pustular psoriasis, including deficiency of interleukin-36 receptor antagonist (DITRA; AR) and CARD14associated pustular psoriasis (CAMPS; AD) (see Chs 8 and 45)

Weeks to months or older

Pustules and pustular lakes within areas of erythema

Often generalized with erythroderma; pustules in any body region, especially the palms/ soles

Skin biopsy: spongiform pustules and microabscesses within the epidermis, parakeratosis, dilated dermal capillaries; consider genetic analysis (IL36RN, CARD14)

Occasional fever; often resistant to therapy

Deficiency of interleukin-1 receptor antagonist (DIRA; see Ch. 45)

Birth to weeks

Pustules within areas of erythema

Often generalized with erythroderma; oral lesions

Skin biopsy: neutrophilic microabscesses within acanthotic epidermis, parakeratosis, dilated dermal capillaries; genetic analysis (IL1RN)

Sterile osteolytic or hyperplastic bone lesions, neonatal distress; dramatic response to IL-1 antagonists

Perforating neutrophilic and granulomatous dermatitis associated with immunodeficiency

Birth to weeks

Papules evolve into vesicles, pustules, crusts, and ulcers

Varies: face, extremities, perineum

Skin biopsy: granulomas, neutrophilic infiltrate, transepidermal elimination of degenerated collagen and debris through hair follicles

Primary immunodeficiencies, including APLAID (autoinflammation and phospholipase C γ2-associated antibody deficiency and immune dysregulation)

Vesiculopustular and Erosive Disorders in Newborns and Infants

34

DIFFERENTIAL DIAGNOSIS OF VESICULOPUSTULAR DISEASES

Table 34.1 Differential diagnosis of vesiculopustular diseases. (cont’d) AD, autosomal dominant; AR, autosomal recessive;.  

DIFFERENTIAL DIAGNOSIS OF BULLAE, EROSIONS AND ULCERATIONS

Disease

Usual age

Skin: morphology

Skin: distribution

Staphylococcal scalded skin syndrome (see Ch. 74) (Fig. 34.17)

Few days to weeks; rarely congenital

Erythematous patches, fragile bullae, superficial erosions, peeling in sheets

Generalized with periorificial and intertriginous accentuation

Group B streptococcal infection

(see Table 34.1)

Pseudomonas aeruginosa infection

(see Table 34.1)

Diagnostic studies (skin)

Comments

Infectious diseases Biopsy: epidermal separation at granular cell layer; culture positive only at primary site(s) of infection (toxin-mediated)

Irritability, temperature instability; high risk of secondary sepsis, fluid/ electrolyte abnormalities

Table 34.2 Differential diagnosis of bullae, erosions and ulcerations. Adapted from Frieden IJ, Howard R. In: Eichenfield LF, Frieden IJ, Mathes EF, Zaenglein AL (eds). Neonatal and Infant  

Dermatology. London: Elsevier, 2015:112–115.

Continued

565

SECTION

Vesiculobullous Diseases

5

DIFFERENTIAL DIAGNOSIS OF BULLAE, EROSIONS AND ULCERATIONS

Disease

Diagnostic studies (skin)

Usual age

Skin: morphology

Skin: distribution

Comments

Congenital syphilis (see Ch. 82)

Birth to first few days

Bullae or erosions; erythema and desquamation

Any region, especially perioral, palms/soles

Darkfield examination of serous exudates, DFA; serologic studies (treponemal and non-treponemal)

Snuffles, hepatosplenomegaly, periostitis with pseudoparalysis

“Invasive fungal dermatitis” due to candidiasis > other fungi (see text and below) in very-lowbirth-weight premature newborns (Fig. 34.7)

Birth to 2 weeks

“Burn-like” erythema with desquamation and erosions; intertriginous maceration

Any region

KOH: budding yeast; fungal culture; placental/umbilical cord lesions may be present

Risk factors: birth weight 20–50% of term infants Male : female = 1 : 1

Uncommon Males > females

Proposed pathogenic factors

Inflammatory reaction to Malassezia spp.

Androgen production

Typical age of onset

~5 days to 3 weeks

~6 weeks to 1 year

Typical duration

Weeks to 3 months

6 to 18 months

Morphology of lesions

Papules and pustules on an erythematous base

Open and closed comedones, papules, pustules, occasionally nodules

Distribution

Cheeks, forehead, eyelids, chin > neck, scalp, upper trunk

Primarily cheeks

Scarring

None

Occasionally

Treatment

Not usually necessary

More often necessary

Topical imidazole or hydrocortisone

Topical retinoids, benzoyl peroxide, antibiotics; occasionally oral antibiotics or retinoids

Occasionally seborrheic dermatitis

Rarely an endocrine disorder, but need to consider when severe or other signs/symptoms (e.g. virilization, abnormal growth) Increased likelihood of severe adolescent acne

Associated disease

Table 34.3 Neonatal cephalic pustulosis versus infantile acne.  

Fig. 34.6 Neonatal cephalic pustulosis. Papulopustules on the forehead and cheeks of a 3-week-old infant. Courtesy,  

Julie V Schaffer, MD.

Fig. 34.7 Congenital candidiasis in a neonate born at 24 weeks’ gestation. Note the “burn-like” erosions and desquamation. This presentation is associated with a high risk of systemic involvement. Courtesy, Julie V Schaffer, MD.  

572

Neonatal candidiasis is common and acquired during delivery or postnatally, whereas congenital candidiasis is uncommon and acquired in utero. In addition, premature newborns with a very low birth weight (often 2–3) is also commonly observed. Symptoms of PCOS include irregular menstrual periods, hirsutism, obesity, insulin resistance, and reduced fertility (see Fig. 70.12). When levels of serum testosterone exceed 200 ng/dl, an ovarian tumor should be considered.

CAUSES OF DRUG-INDUCED ACNE

Common

Uncommon

Anabolic steroids (e.g. danazol, testosterone)

Azathioprine

Bromides*

Cyclosporine

Corticosteroids (see Fig. 36.13)

Disulfiram

Corticotropin

Ethosuximide

EGFR inhibitors (see Fig. 36.15 and Ch. 21)

Phenobarbital

Iodides†

Propylthiouracil

Isoniazid (see Fig. 36.14)

Psoralen + ultraviolet A

Lithium

Quinidine

MEK inhibitors (e.g. trametinib)

Quetiapine

Phenytoin

TNF inhibitors

Progestins (see text)

Vitamins B6 and B12

*† Found in sedatives, analgesics and cold remedies.

Found in contrast dyes, cold/asthma remedies, kelp, and combined vitamin–mineral supplements.

Table 36.1 Causes of drug-induced acne. EGFR, epidermal growth factor receptor.  

Acne associated with genetic syndromes Apert syndrome (acrocephalosyndactyly type I) is an autosomal dominant disorder that features disfiguring synostoses of the bones of the hands and feet, vertebral bodies, and cranium. Affected individuals have an increased incidence of severe, early-onset acne that tends to be nodulocystic and have a more widespread distribution than in classic acne, often involving the entire extensor aspects of the arms, buttocks and thighs46. Acne in patients with Apert syndrome is typically resistant to therapy, although isotretinoin has been reported to be beneficial. Other cutaneous findings in this disorder can include marked seborrhea, nail anomalies (e.g. a single nail for the second through fourth digits), and diffuse pigmentary dilution of the hair and skin. Of note, Apert syndrome results from activating mutations in FGFR2, which encodes fibroblast growth factor receptor 2; mosaicism for the same FGFR2 mutations has been found to underlie acneiform/comedonal nevi (see Ch. 62). FGFR2 signaling has been shown to have effects on follicular keratinocyte proliferation, sebaceous lipogenesis, and inflammatory cytokine production. Borrone dermato-cardio-skeletal syndrome, an autosomal recessive disorder caused by SH3PXD2B mutations, is characterized by dysmorphic facies, thick skin, acne conglobata, vertebral abnormalities, and mitral valve prolapse. PAPA syndrome and related conditions are discussed in the section on acne conglobata.

Acneiform Eruptions Drug-induced acne

594

Acne or acneiform eruptions (e.g. folliculitis) can be seen as a side effect of a number of medications (Table 36.1). An abrupt, monomorphous eruption of inflammatory papules and pustules is often observed in drug-induced acne (Figs 36.13 & 36.14), in contrast to the heterogeneous morphology of lesions seen in acne vulgaris. When a history of prescription medication use is not elicited, a comprehensive review of all over-the-counter medications and supplements, as well as recent medical procedures, may reveal the responsible agent (see Table 36.1). Bodybuilders and athletes should be questioned about anabolic steroid use. High-dose intravenous or oral corticosteroids commonly induce characteristic acneiform eruptions with a concentration of lesions on the chest and back (see Fig. 36.13). Steroid-induced acne (and rosacea) can also result from the inappropriate use of topical corticosteroids on the face. Inflamed papules and pustules develop on a background of erythema that favors the distribution of corticosteroid application. Lesions eventually resolve following discontinuation of the corticosteroid, although “steroid dependency” can lead to prolonged and severe flares post-withdrawal (see Ch. 37).

Fig. 36.13 Acneiform eruption secondary to high-dose dexamethasone. Abrupt eruption of monomorphous follicular papules and pustules on the chest.  

Fig. 36.14 Druginduced acne due to isoniazid. Courtesy, Kalman  

Watsky, MD.

plaque interspersed with comedones. Linear and geometrically distributed areas of involvement suggest acne mechanica. Treatment is aimed at eliminating the inciting forces.

Occupational acne, acne cosmetica, and pomade acne

Tropical acne

Exposure to insoluble, follicle-occluding substances in the workplace is responsible for occupational acne (see Ch. 16). Offending agents include cutting oils, petroleum-based products, chlorinated aromatic hydrocarbons, and coal tar derivatives. Comedones dominate the clinical picture, with varying numbers of papules, pustules and cystic lesions distributed in exposed as well as typically covered areas. Primarily comedonal facial acne, with a predominance of closed comedones, can also develop in sites chronically exposed to follicle-occluding cosmetics (acne cosmetica) or hair products. The latter, referred to as pomade acne, favors the forehead and temples.

Tropical acne is a follicular acneiform eruption that results from exposure to extreme heat. This can occur in tropical climates or secondary to scorching occupational environments, as in furnace workers. Historically, tropical acne caused significant morbidity among military troops. Markedly inflamed nodulocystic acne involving the trunk and buttocks is typically seen, and secondary staphylococcal infection is a frequent complication. Treatment is often of limited efficacy until the patient returns to a more moderate climate.

Chloracne Chloracne is due to exposure to halogenated aromatic hydrocarbons. It typically develops several weeks after systemic exposure, which can occur via percutaneous absorption, inhalation, or ingestion. The following agents, found in electrical conductors and insulators, insecticides, fungicides, herbicides and wood preservatives, have all been implicated: polychlorinated naphthalenes, biphenyls, dibenzofurans and dibenzodioxins; polybrominated naphthalenes and biphenyls; tetrachloroazobenzene; and tetrachloroazoxybenzene. Comedo-like lesions and yellowish cysts with relatively little associated inflammation most commonly affect the malar and retroauricular areas of the head and neck (see Fig. 16.13), as well as the axillae and scrotum. The extremities, buttocks, and trunk are variably involved. Cystic lesions can heal with significant scarring, and the condition may persist for several years following cessation of exposure. Additional findings may include hypertrichosis and grayish discoloration of the skin. Initial management is aimed at removal of the source of exposure. Topical or oral retinoids may be beneficial, but chloracne is often recalcitrant to therapy.

Acne mechanica Acne mechanica is due to repeated mechanical and frictional obstruction of the pilosebaceous outlet. Comedo formation is the result. Welldescribed mechanical factors include rubbing by helmets, chin straps, suspenders, and collars. Orthopedic causes include acne mechanica in the axillae due to the use of crutches and on amputee stumps due to friction from prostheses. A classic example of acne mechanica is fiddler’s neck, where repetitive trauma from violin placement on the lateral neck results in a well-defined, lichenified, hyperpigmented

CHAPTER

36 Acne Vulgaris

Epidermal growth factor receptor (EGFR) inhibitors used for the treatment of solid tumors also have a high incidence of acneiform papulopustular eruptions (Fig. 36.15; see Chapter 21).

Radiation acne Radiation acne is characterized by comedo-like papules occurring at sites of previous exposure to therapeutic ionizing radiation. The lesions begin to appear as the acute phase of radiation dermatitis starts to resolve. The ionizing rays induce epithelial metaplasia within the follicle, creating adherent hyperkeratotic plugs that are resistant to expression.

“Pseudoacne” of the nasal crease The transverse nasal crease is a horizontal anatomical demarcation line found in the lower third of the nose, which corresponds to the separation point between the alar cartilage and the triangular cartilage. Milia, cysts, and comedones can line up along this fold (Fig. 36.16A)47. These acne-like lesions are not hormonally responsive and arise during early childhood prior to the onset of puberty. Treatment consists of mechanical expression or topical therapy with a retinoid or benzoyl peroxide as needed.

Idiopathic facial aseptic granuloma This painless nodule with an acneiform appearance typically develops on the cheeks of young children (mean age, ~3.5 years)48. Multiple lesions are uncommon. Histopathologic evaluation reveals a dermal lymphohistiocytic infiltrate with foreign body-type giant cells. In general, cultures are negative and the lesions do not respond to antibiotic therapy. Eventually, after an average of one year, the lesions resolve spontaneously48. It has been suggested that idiopathic facial aseptic granuloma represents a form of childhood rosacea as >40% of patients have at least two other clinical signs of rosacea including recurrent chalazions, facial flushing, telangiectasias, or papulopustules49–51.

Childhood flexural comedones This entity is characterized by discrete, double-orifice comedones localized to the axillae and, less commonly, the groin52. The majority of patients have a single lesion and the average age at diagnosis is 6 years, with boys and girls equally affected. Occasionally it is familial. There is no association with hidradenitis suppurativa, acne vulgaris, or precocious puberty.

PATHOLOGY

Fig. 36.15 Acneiform eruptions due to epidermal growth factor receptor inhibitors. Numerous monomorphous follicular pustules on the face of an adolescent boy treated with erlotinib.  

Histopathologic examination of acne lesions demonstrates the stages of acnegenesis that parallel the clinical findings (see Fig. 36.1). In early lesions, microcomedones are seen. A mildly distended follicle with a narrowed follicular opening is impacted by shed keratinocytes. The granular layer at this stage is prominent. In closed comedones, the degree of follicular distension is increased and a compact cystic structure forms. Within the cystic space, eosinophilic keratinaceous debris, hair, and numerous bacteria are present. Open comedones have broad, expanded follicular ostia and greater overall follicular distension. The sebaceous glands are typically atrophic or absent. A mild perivascular mononuclear cell infiltrate encircles the expanding follicle. As the follicular epithelium distends, the cystic contents inevitably begin to rupture into the dermis (Fig. 36.17). The highly immunogenic cystic contents (keratin, hair and bacteria) induce a marked inflammatory response. Neutrophils first appear, creating a pustule. As the lesion matures, foreign body granulomatous inflammation engulfs the follicle and end-stage scarring can result.

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Fig. 36.16 Disorders in the differential diagnosis of acne vulgaris. A Pseudoacne of the transverse nasal crease in a young child. Note the milia and comedones located along this anatomical demarcation line. B Acneiform follicular mucinosis on the cheek of a woman. C Follicular mycosis fungoides that presented as numerous lesions with a comedonal appearance on the chest, abdomen, and back. A, C, Courtesy, Julie V Schaffer, MD; B, Courtesy, Lorenzo Cerroni, MD.  

&

Fig. 36.17 Histology of an inflamed comedo. There is disruption of the pilosebaceous unit and secondary inflammation. Courtesy, Lorenzo Cerroni, MD.  

In acne fulminans, there is massive inflammation with varying degrees of overlying necrosis. Comedones are rarely observed. Severe scarring may be seen in resolving lesions.

DIFFERENTIAL DIAGNOSIS 596

Although classic acne vulgaris is usually easily recognized clinically, the differential diagnosis of acneiform eruptions is broad and depends upon

the age of onset, lesional morphology, and location (Table 36.2; see Fig. 36.16). During the neonatal period, acne must be differentiated from other common dermatoses. Sebaceous hyperplasia occurs in the majority of healthy neonates, presenting as transient yellowish papules on the cheeks, nose and forehead. Miliaria rubra is also very common during the neonatal period, when overheating and bundling can cause temporary eccrine duct obstruction that leads to the formation of small inflammatory papulopustules. Small, white milia are often apparent on the cheeks and nose of neonates, but they generally resolve within a few months. Predominantly comedonal acne vulgaris needs to be differentiated from comedonal eruptions caused by follicular occlusion or friction, including acne mechanica, acne cosmetica, pomade acne, and occupational acne (see above); history as well as location can help to make the diagnosis of these forms of “contact acne”. Sebaceous hyperplasia, a very common finding in adults, is relatively uncommon in adolescents. These yellowish, lobulated papules arise primarily on the forehead and cheeks. A solitary enlarged comedo is better classified as a dilated pore of Winer; such lesions rarely represent a large-pore basal cell carcinoma. Multiple open comedones are clustered in the lateral malar region in Favre–Racouchot syndrome (see Ch. 87) or appear in a linear array in nevus comedonicus (see Chs 62 and 109). If multiple vellus hairs arise from a dilated follicular orifice in association with keratinous debris, trichostasis spinulosa is the likely diagnosis. The most common location is the nose. Angiofibromas and appendageal tumors of follicular origin, e.g. trichoepitheliomas, trichodiscomas and fibrofolliculomas, often present as multiple facial papules (see Ch. 111). They are typically noninflammatory, and trichoepitheliomas are concentrated in the nasolabial folds. Non-inflammatory, closed cystic papules and nodules on the central chest and back characterize steatocystoma multiplex (see

CHAPTER

Acne vulgaris – comedonal

Closed

Open

Milia • Osteoma cutis • Sebaceous hyperplasia • Pseudoacne of the nasal crease (see Fig. 36.16A) • Syringomas • Trichoepitheliomas * • Trichodiscomas, fibrofolliculomas • Eruptive vellus hair cysts†, steatocystoma multiplex† • Colloid milia • Acne exacerbated by systemic corticosteroids‡ or anabolic steroids • Contact acne (occupational, pomade, cosmetica, mechanica; chloracne) • Follicular mucinosis (see Fig. 36.16B) • Follicular mycosis fungoides (see Fig. 36.16C)





Contact acne (see Closed) Acne exacerbated by systemic corticosteroids‡ or anabolic steroids • Trichostasis spinulosa (see inset) • Favre–Racouchot syndrome • Pseudoacne of the nasal crease (see Fig. 36.16A) • Nevus comedonicus • Basaloid follicular hamartoma syndrome • Familial dyskeratotic comedones • Dowling–Degos disease • Radiation-induced comedones • Molluscum-induced comedones • Childhood flexural comedones (often a single double-orifice lesion) • Dilated pore of Winer (single lesion) • Trichofolliculoma (usually a single lesion) • Follicular spines – in settings such as trichodysplasia spinulosa§, type VI pityriasis rubra pilaris§, multiple myeloma, demodicosis§, follicular mucinosis, and drug-induced (e.g. BRAF inhibitors, cyclosporine§, acitretin) •

36 Acne Vulgaris

DIFFERENTIAL DIAGNOSIS OF ACNE

Acne vulgaris – inflammatory Rosacea Perioral/periorificial dermatitis • Demodicosis (adults > children§) • Folliculitis – culture-negative (normal flora), staphylococcal, Gram-negative, eosinophilic§, Pityrosporum • Acne/acneiform eruptions due to topical or systemic corticosteroids‡, anabolic steroids, or other medications (e.g. lithium, EGFR inhibitors; see Table 36.1) • Pseudofolliculitis barbae, acne keloidalis nuchae • Pseudoacne of the nasal crease • Furuncle/carbuncle • Idiopathic facial aseptic granuloma (in children) • Neutrophilic dermatoses and neutrophilic eccrine hidradenitis

Keratosis pilaris Trichodysplasia spinulosa (viral-associated trichodysplasia)§ • Lupus miliaris disseminatus faciei • Psychogenic (neurotic) excoriations, factitial lesions • Follicular mucinosis (see Fig. 36.16B) • Follicular mycosis fungoides (see Fig. 36.16C) • Tinea faciei • Molluscum contagiosum (especially inflamed lesions) • Angiofibromas • Dowling–Degos disease (especially the Haber syndrome variant) • Cutaneous Rosai–Dorfman disease • Granulomatosis with polyangiitis (Wegener granulomatosis) • Syndromes associated with acne, eg. PAPA, (PA)PASH, SAPHO, Apert syndrome









Neonatal acne (neonatal cephalic pustulosis) Sebaceous hyperplasia Milia • Miliaria rubra (especially pustular variant)

Candidal infection Papulopustular eruption of hyper-IgE syndrome • Vesiculopustular eruption of transient myeloproliferative disorder









Solid facial edema secondary to acne vulgaris Solid facial edema secondary to rosacea Melkersson–Rosenthal syndrome, sarcoidosis (e.g. Heerfordt syndrome), lepromatous leprosy • Lymphoma (B- or T-cell), leukemia cutis, angiosarcoma • Scleromyxedema, myxedema, self-healing (juvenile) cutaneous mucinosis • Autoimmune connective tissue disease (e.g. dermatomyositis, lupus erythematosus, Still disease) • •

Angioedema (lasts allergic) to benzoyl peroxide is also possible, and this should be suspected in patients who develop marked erythema with its use. Topical antibiotics are widely used for the treatment of acne and are available alone as well as in combination with benzoyl peroxide or a retinoid. Clindamycin and erythromycin represent the two most commonly utilized antibiotics and the formulations vary from creams and gels to solutions and pledgets (see Ch. 127); however, resistance of >50% of P. acnes strains to these macrolides has been reported in some countries56a. Azelaic acid is a naturally occurring dicarboxylic acid found in cereal grains. It is available as a topical 20% cream, which has been shown to be effective in inflammatory and comedonal acne, as well as a 15% gel marketed for rosacea. By inhibiting the growth of P. acnes, azelaic acid reduces inflammatory acne. It also reverses the altered keratinization of follicles affected by acne and thus demonstrates comedolytic properties. The activity of azelaic acid against inflammatory lesions may be greater than its activity against comedones. Azelaic acid is applied twice daily and its use is reported to have fewer local side effects than topical retinoids. In addition, it may help to lighten postinflammatory hyperpigmentation. Sodium sulfacetamide is a well-tolerated topical antibiotic that is thought to restrict the growth of P. acnes through competitive inhibition of the condensation of para-aminobenzoic acid with pteridine precursors (see Ch. 127). It is formulated in a 10% lotion, suspension, foam and cleanser, either alone or in combination with 5% sulfur. Tinted formulations are also available. Topical dapsone 5% and 7.5% gels are approved for the treatment of acne vulgaris. Of note, a temporary yellow–orange staining of the skin and hair occasionally occurs with concomitant application of topical dapsone and benzoyl peroxide.

Other topical medications Salicylic acid is a widely used comedolytic and antibacterial agent (see Ch. 153). Salicylic acid is available over the counter in concentrations

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of up to 2% in numerous delivery formulations, including gels, creams, lotions, foams, solutions, and washes. Side effects of topical salicylic acid include erythema and scaling.

Oral contraceptive®

Estrogen mcg/Progestin mcg

Oral Treatments

FDA-approved for acne vulgaris

Antibiotics

Ortho Tri-Cyclen

Ethinyl estradiol 35/norgestimate 180, 215, 250

Estrostep

Ethinyl estradiol 20, 30, 35/norethindrone 1000

Yaz, Loryna, Nikki, Beyaz*

Ethinyl estradiol 20/drospirenone 3000

Moderate to severe inflammatory acne is often treated with oral tetracycline derivatives, especially doxycycline and minocycline, and less often macrolides such as erythromycin and azithromycin. In this setting, a primary mechanism of action of these medications is suppression of the growth of P. acnes, thereby reducing bacteria-mediated inflammation. However, several of these antibiotics also possess intrinsic anti-inflammatory properties. Details regarding the mechanisms of action, recommended dosages, and side effects of tetracyclines and macrolides are reviewed in Chapter 127. Recent guidelines suggest that the duration of oral antibiotic courses for acne should be limited to 3 to 6 months52a,56a,57. Resistance of P. acnes to erythromycin and less commonly the three major tetracyclines (tetracycline and doxycycline more so than minocycline) can occur56a. Minocycline, a lipophilic derivative of tetracycline, has greater penetration into the sebaceous follicle; although this has been postulated. While doxycycline-related phototoxicity can be problematic, minocycline is associated with a higher incidence of serious adverse events, including a minocycline-induced hypersensitivity syndrome and autoimmune reactions (see Ch. 21). The latter typically develop after many months to years of therapy and can include hepatitis, a lupus erythematosus-like syndrome, and cutaneous polyarteritis nodosa that is often associated with antineutrophil cytoplasmic antibodies.

Hormonal therapy

600

COMMONLY USED COMBINED ORAL CONTRACEPTIVES

Hormonal therapy is an established second-line treatment for female patients with acne and can be very effective, irrespective of whether or not the serum androgen levels are abnormal. Although women and adolescent girls with acne may have higher serum levels of androgens than those without acne, the levels in acne patients are often within the normal range. Combined oral contraceptive pills, which block both ovarian and adrenal production of androgens, are particularly effective for inflammatory acne. A recent meta-analysis found that oral contraceptive pills are equivalent to oral antibiotics in reducing the number of acne lesions after 6 months of therapy58. Combined oral contraceptive formulations contain an estrogen plus a progestin in order to minimize the risk of endometrial cancer, which is known to occur with unopposed estrogen administration. Although progestins have intrinsic androgenic activity, second-generation progestins (e.g. ethynodiol diacetate, norethindrone, levonorgestrel) have lower androgenic potential. Newer, third-generation progestins (e.g. desogestrel, norgestimate, gestodene [Europe]) have even less androgenic activity than their predecessors, and other progestins (e.g. drospirenone, cyproterone acetate, dienogest) have antiandrogenic properties. Three oral contraceptives are currently FDA-approved for the treatment of acne, although others also have evidence of efficacy59 (Table 36.6). The first is a triphasic oral contraceptive composed of a norgestimate–ethinyl estradiol (35 mcg) combination. The second contains a graduated dose of ethinyl estradiol (20–35 mcg) in combination with norethindrone acetate, while the third contains a stable dose of ethinyl estradiol (20 mcg) plus drospirenone (3 mg) with a 24-day dosing regimen. Side effects from oral contraceptives include nausea, vomiting, abnormal menses, weight gain, and breast tenderness. Agents containing drospirenone can lead to elevations in serum potassium levels, but this is generally not clinically significant in otherwise healthy individuals. Rare but more serious complications include hypertension and thromboembolism (e.g. deep venous thrombosis, pulmonary embolism). The increase in risk of venous thromboembolism ranges from 2–4-fold with levonorgestrel or norethindrone to 3.5–7-fold with desogestrel, drospirenone and cyproterone acetate, and risk of thrombosis is greatest early on during treatment60–62. Overall the risk is highest for women over the age of 35 years, smokers, and those with other prothrombotic risk factors such as hereditary thrombophilia63. The antiandrogen cyproterone acetate is currently marketed in Europe and Canada but is not available in the US. Its anti-acne effects

Clinical data to support use Alesse

Ethinyl estradiol 20/levonorgestrel 100

Diane-35†

Ethinyl estradiol 35/cyproterone acetate 2000

Yasmin, Syeda, Yaela, Safyral*

Ethinyl estradiol 30/drospirenone 3000

Natazia

Estradiol valerate 1000, 2000, 3000/ dienogest 2000, 3000

No/insufficient clinical data Various combinations of ethinyl estradiol 10, 20, 25, 30, or 35 plus norethindrone 400, 500, 750, 800, or 1500 OR levonorgestrel 50, 75, 125, or 150 OR desogestrel 100, 125, or 150 OR norgestrel 300 OR ethynodiol diacetate 1000

*† Also contains levomefolate calcium for protection against neural tube defects. Not available in the US.

Table 36.6 Commonly used combined oral contraceptives.  

are mediated primarily through androgen receptor blockade. The standard contraceptive formulation combines cyproterone acetate (2 mg) with ethinyl estradiol (35 or 50 mcg). This preparation is widely used in Europe as the treatment of choice for sexually active women with hormonally responsive acne. Formulations of cyproterone acetate alone are also available. Approximately 75–90% of patients treated with either the standard contraceptive formulation or higher doses of 50–100 mg daily (with or without ethinyl estradiol 50 mcg) show substantial improvement64. The most frequent side effects are breast tenderness, headache, nausea, and irregular menses; hepatotoxicity and thromboembolism represent uncommon complications. Spironolactone functions as both an androgen receptor blocker and an inhibitor of 5α-reductase. In doses of 50–100 mg twice daily, it has been shown to reduce sebum production and improve acne65. Up to two-thirds of women treated with spironolactone note marked improvement or clearance of their acne66. Side effects are dose-related and include irregular menstrual periods, breast tenderness, headache, and fatigue. Hyperkalemia is rare and monitoring of potassium levels is not required in young healthy patients67. Although breast tumors have been reported in rodents given spironolactone, this drug has not been directly linked to the development of cancer in humans68. Because it is an antiandrogen, there is a risk of feminization of a male fetus if a pregnant woman takes this medication. Side effects can be minimized if therapy is initiated at a low dose (25–50 mg/day). Effective maintenance doses range from 25 to 200 mg/day. As with other hormonal therapies, a clinical response may take up to 3 months. Flutamide, a nonsteroidal androgen receptor blocker approved by the FDA for the treatment of prostate cancer, may be of benefit for acne in women at doses of 62.5–500 mg/day. In addition to side effects similar to those of other antiandrogens (e.g. menstrual irregularities, breast tenderness, risk of feminization of a male fetus), severe dose-related hepatotoxicity limits its use.

Isotretinoin Since 1971, oral isotretinoin (13-cis-retinoic acid) has been available in Europe for the treatment of acne. In the US, it was FDA-approved in 1982 for patients with severe, nodulocystic acne refractory to treatment, including oral antibiotics. Over time, other clinical forms of acne

Surgical Treatment Comedo extraction can improve the cosmetic appearance of acne and aids in therapeutic responsiveness to topical comedolytic agents. The keratinous contents of open comedones may be expressed using a comedo extractor. The Schamberg, Unna, and Saalfield types of comedo expressers are most commonly used. Nicking the surface of a closed comedo with an 18-gauge needle or a #11 blade allows easier expression. Extraction is especially beneficial for deep, inspissated, and persistent comedones. This procedure should be used in conjunction with a topical retinoid or other comedolytic treatment for maximum benefit. Comedo extraction should not be performed on inflamed comedones or pustules because of the risk of scarring. Light electrocautery and electrofulguration (see Ch. 140) have also been reported as effective treatments for comedones. Electrofulguration has the added benefit of not requiring the prior use of a topical anesthetic. In selected patients, cryotherapy represents another surgical option for the treatment of comedonal acne (see Ch. 138).

Fig. 36.18 Cutaneous complications of isotretinoin therapy. A Impetigo in a patient treated with isotretinoin. Multiple serous crusts are evident. B Pyogenic granuloma-like healing on the chest of an adolescent boy on his third month of isotretinoin therapy. This is more likely to occur when isotretinoin therapy is started at a full dose rather than a lower initial dose, especially in teenage boys.  

CHAPTER

36 Acne Vulgaris

have also been shown to benefit greatly from the use of isotretinoin69. These include significant acne that is unresponsive to therapy (including oral antibiotics) and/or results in scarring, as well as Gram-negative folliculitis, pyoderma faciale, and acne fulminans. The mechanism of action of isotretinoin, as well as dosing regimens, side effects and monitoring protocols, are discussed in detail in Chapter 126. Patients with acne are typically treated with an isotretinoin dose of 0.5–1 mg/kg/day taken with a fatty meal to increase gastrointestinal absorption, often with a lower dose during the first month of treatment to prevent an initial acne flare and allow the patient to adjust to dosedependent side effects. Reaching a cumulative dose of 120–150 mg/kg (e.g. 4–5 months of treatment with 1 mg/kg/day) has been shown to reduce the risk of relapse. However, a 6-month course of low-dose isotretinoin (e.g. 0.25–0.4 mg/kg/day, 40–70 mg/kg cumulative) can be effective in the treatment of moderate acne, with fewer side effects and improved patient satisfaction70. Subsets of patients who are less likely to respond to isotretinoin and/or more likely to require multiple or longer courses of treatment include adolescents under 16 years of age who have nodulocystic acne, individuals with endocrine abnormalities, and women with less severe acne. Scarred nodules and sinus tracts which represent sequelae from previously active cystic acne do not respond to isotretinoin but may improve with surgical modalities; the latter are generally delayed for at least 6–12 months after completing isotretinoin therapy to avoid the possible risk of atypical healing or scarring responses. The most common adverse effects of isotretinoin involve the skin and mucous membranes and are dose-dependent. These include cheilitis, dryness of the oral and nasal mucosa, generalized xerosis, and skin fragility. With the institution of isotretinoin therapy, induction of an acne fulminans-like flare, formation of excessive granulation tissue, paronychias, and cutaneous infections (in particular with Staphylococcus aureus) can also occur (Fig. 36.18). Teratogenicity is a serious potential complication (see Table 126.7), and female patients of childbearing potential must have at least one (in the US, two) negative pregnancy test(s) before starting treatment and must practice effective contraception for 1 month prior to, during, and for 1 month after completing therapy. In the US, prescription of isotretinoin requires all physicians and patients to register with a pregnancy risk management program (iPLEDGE™), which mandates monthly office visits for all patients that includes counseling not to share the medication as well as monthly pregnancy testing for female patients with childbearing potential. Isotretinoin therapy leads to elevated serum triglyceride and/or cholesterol levels in ~20–50% of patients; however, severe elevations are uncommon and typically develop within the first two months of therapy71,72. Other potential side effects involve the musculoskeletal system (e.g. myalgias, elevation of serum creatine kinase levels), eyes, liver (occasionally elevated transaminases), intestines (controversial; no link with inflammatory bowel disease found in a recent meta-analysis) and central nervous system (see Table 126.8 and Ch. 126). To date, no firmly established causal association with depression or suicide attempts has been demonstrated. A recent metaanalysis did not show an association between isotretinoin treatment and increased risk of depression; instead, acne therapy led to a decreased prevalence of depression73.

$

%

Photodynamic therapy utilizing topical 5-aminolevulinic acid together with various light sources (e.g. blue, red, intense pulsed) or lasers (e.g. pulsed dye, 635 nm red diode) as well as methyl aminolevulinate plus red light have been successfully used to treat acne (see Ch. 135). In addition, blue or intense pulsed light alone and lasers such as the pulsed dye, the 1320 nm neodymium:YAG, and especially the 1450 nm diode may be of therapeutic benefit for inflammatory acne (see Ch. 137). Intralesional injection of corticosteroid (triamcinolone acetonide 2–5 mg/ml) can quickly improve the appearance and tenderness of deep, inflamed nodules and cysts. Larger cysts may require incision and drainage prior to injection. The maximal amount of corticosteroid used per lesion should not exceed 0.1 ml. The risks of corticosteroid injections include hypopigmentation (particularly in darkly pigmented skin), atrophy, telangiectasias, and yellow–white dermal deposits of the medication. Low-concentration chemical peels are also beneficial for the reduction of comedones. The α-hydroxy acids (including glycolic acid), salicylic acid, and trichloroacetic acid are the most common peeling agents. These lipid-soluble comedolytic agents act by decreasing corneocyte cohesion at the follicular opening and assist in comedo plug extrusion. Such agents are generally well tolerated by most skin colors and types, and they can be used by the patient at home or in the dermatologist’s office. Higher-concentration glycolic acid peels (20–70%, depending on

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the patient’s skin type) and the less predictable phenol peel may also be performed in the office setting (see Ch. 154). Risks of chemical peels include irritation, pigmentary alteration, and scarring. One of the most distressing consequences of acne vulgaris is scarring. Surgical treatments should be aimed at the type of scarring present. Laser resurfacing (fractionated as well as traditional), dermabrasion, and deeper chemical peels seek to reduce the variability of the skin surface and smooth out depressed scars that improve when the skin is stretched. For discrete depressed scars, soft tissue augmentation can be

temporarily beneficial. Filler substances used include poly-L-lactic acid, calcium hydroxylapatite, and autologous fat (see Ch. 158). Surgical subcision is also used for management of acne scars and punch grafting is an option for patients with “ice-pick” scarring. For larger hypertrophic scars, aggregated pitted scars and sinus tracts, full-thickness surgical excision may result in improved scar placement and a better cosmetic appearance. For additional online figures visit www.expertconsult.com

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1. Halvorsen JA, Stern RS, Dalgard F, et al. Suicidal ideation, mental health problems, and social impairment are increased in adolescents with acne: a population-based study. J Invest Dermatol 2011;131:363–70. 1a.  Ramrakha S, Fergusson DM, Horwood LJ, et al. Cumulative mental health consequences of acne: 23-year follow-up in a general population birth cohort study. Br J Dermatol 2016;175:1079–81. 2. Goolamali SK, Andison AC. The origin and use of the word ‘acne’. Br J Dermatol 1977;96:291–4. 3. Waisman M. Concepts of acne of the British School of Dermatology prior to 1860. Int J Dermatol 1983;22:126–9. 3a.  Karimkhani C, Dellavalle RP, Coffeng LE, et al. Global skin disease morbidity and mortality: an update from the global burden of disease study 2013. JAMA Dermatol 2017;153:406–12. 4. Eichenfield LF, Krakowski AC, Piggott C, et al. Evidence-based recommendations for the diagnosis and treatment of pediatric acne. Pediatrics 2013;131(Suppl. 3):S163–86. 5. Tan JK, Bhate K. A global perspective on the epidemiology of acne. Br J Dermatol 2015;172(Suppl. 1):3–12. 6. Collier CN, Harper JC, Cafardi JA, et al. The prevalence of acne in adults 20 years and older. J Am Acad Dermatol 2008;58:56–9. 7. Ghodsi SZ, Orawa H, Zouboulis CC. Prevalence, severity, and severity risk factors of acne in high school pupils: a community-based study. J Invest Dermatol 2009;129:2136–41. 8. Suh DH, Kwon HH. Novel findings in the physiopathology of acne. Br J Dermato 2015;172(Suppl. 1):13–19. 9. Navarini AA, Simpson MA, Weale M, et al. Genome-wide association study identifies three novel susceptibility loci for severe acne vulgaris. Nat Commun 2014;5:4020. 10. Di Landro A, Cazzaniga S, Parazzini F, et al. Family history, body mass index, selected dietary factors, menstrual history, and risk of moderate to severe acne in adolescents and young adults. J Am Acad Dermatol 2012;67:1129–35. 11. Adebamowo CA, Spiegelman D, Danby FW, et al. High school dietary dairy intake and teenage acne. J Am Acad Dermatol 2005;52:207–14. 11a.  LaRosa CL, Quach KA, Koons K, et al. Consumption of dairy in teenagers with and without acne. J Am Acad Dermatol 2016;75:318–22. 12. Bowe WP, Joshi SS, Shalita AR. Diet and acne. J Am Acad Dermatol 2010;63:124–41. 13. Kwon HH, Yoon JY, Hong JS, et al. Clinical and histological effect of a low glycaemic load diet in treatment of acne vulgaris in Korean patients: a randomized, controlled trial. Acta Derm Venereol 2012;92:241–6. 14. Kang D, Shi B, Erfe MC, et al. Vitamin B12 modulates the transcriptome of the skin microbiota in acne pathogenesis. Sci Transl Med 2015;7:293ra103. 15. Jeremy AHT, Holland DB, Roberts SG, et al. Inflammatory events are involved in acne lesion initiation. J Invest Dermatol 2003;121:20–7. 16. Lucky AW, Biro FM, Huster GA, et al. Acne vulgaris in premenarchal girls. An early sign of puberty associated with rising levels of dehydroepiandrosterone. Arch Dermatol 1994;130:308–14. 17. Powell EW, Beveridge GW. Sebum excretion and sebum composition in adolescent men with and without acne vulgaris. Br J Dermatol 1970;82:243–9. 18. Pappas A, Johnsen S, Liu JC, Eisinger M. Sebum analysis of individuals with and without acne. Dermatoendocrinol 2009;1:157–61.

19. Strauss JS, Pochi PE. Effect of cyclic progestin-estrogen therapy on sebum and acne in women. JAMA 1964;190:815–19. 20. Abdel-Fattah NS, Shaheen MA, Ebrahim AA, El Okda ES. Tissue and blood superoxide dismutase activities and malondialdehyde levels in different clinical severities of acne vulgaris. Br J Dermatol 2008;159:1086–91. 21. Holland DB, Jeremy AH, Roberts SG, et al. Inflammation in acne scarring: a comparison of the responses in lesions from patients prone and not prone to scar. Br J Dermatol 2004;150:72–81. 22. Segre JA. What does it take to satisfy Koch’s postulates two centuries later? Microbial genomics and Propionibacteria acnes. J Invest Dermatol 2013;133(9):2141–2. 23. Leyden JJ, McGinley KJ, Mills OH, Kligman AM. Propionibacterium levels in patients with and without acne vulgaris. J Invest Dermatol 1975;65:382–4. 24. Fitz-Gibbon S, Tomida S, Chiu BH, et al. Propionibacterium acnes strain populations in the human skin microbiome associated with acne. J Invest Dermatol 2013;133:2152–60. 25. Sugisaki H, Yamanaka K, Kakeda M, et al. Increased interferon-gamma, interleukin-12p40 and IL-8 production in Propionibacterium acnes-treated peripheral blood mononuclear cells from patient with acne vulgaris: host response but not bacterial species is the determinant factor of the disease. J Dermatol Sci 2009;55:47–52. 25a.  Lheure C, Grange PA, Ollagnier G, et al. TLR-2 recognizes Propionibacterium acnes CAMP factor 1 from highly inflammatory strains. PLoS ONE 2016;11:e0167237. 26. Kim J, Ochoa MT, Krutzik SR, et al. Activation of toll-like receptor 2 in acne triggers inflammatory cytokine responses. J Immunol 2002;169:1535–41. 27. Jalian HR, Liu PT, Kanchanapoomi M, et al. All-trans retinoic acid shifts Propionibacterium acnes-induced matrix degradation expression profile toward matrix preservation in human monocytes. J Invest Dermatol 2008;128:2777–82. 28. Nagy I, Pivarcsi A, Koreck A, et al. Distinct strains of Propionibacterium acnes induce selective human beta-defensin-2 and interleukin-8 expression in human keratinocytes through toll-like receptors. J Invest Dermatol 2005;124:931–8. 29. Qin M, Pirouz A, Kim MH, et al. Propionibacterium acnes Induces IL-1β secretion via the NLRP3 inflammasome in human monocytes. J Invest Dermatol 2014;134:  381–8. 30. Kistowska M, Meier B, Proust T, et al. Propionibacterium acnes promotes Th17 and Th17/Th1 responses in acne patients. J Invest Dermatol 2015;135:110–18. 31. Liu PT, Phan J, Tang D, et al. CD209(+) macrophages mediate host defense against Propionibacterium acnes. J Immunol 2008;180:4919–23. 31a.  Di Landro A, Cazzaniga S, Cusano F, et al. Group for Epidemiologic Research in Dermatology Acne Study Group. Adult female acne and associated risk factors: Results of a multicenter case-control study in Italy. J Am Acad Dermatol 2016;75:1134–41. 32. Dréno B, Thiboutot D, Layton AM, et al. the Global Alliance to Improve Outcomes in Acne. Large-scale international study enhances understanding of an emerging acne population: adult females. J Eur Acad Dermatol Venereol 2015;29:1096–106. 33. Geller L, Rosen J, Frankel A, Goldenberg G. Perimenstrual flare of adult acne. J Clin Aesthet Dermatol 2014;7:30–4. 34. Capitanio B, Sinagra JL, Bordignon V, et al. Underestimated clinical features of postadolescent acne. J Am Acad Dermatol 2010;63:782–8.

34a.  Greywal T, Zaenglein AL, Baldwin HE, et al. Evidencebased recommendations for the management of acne fulminans and its variants. J Am Acad Dermatol 2017;77:109–17. 35. Jansen T, Plewig G. Acne fulminans. Int J Dermatol 1998;37:254–7. 36. Tan BB, Lear JT, Smith AG. Acne fulminans and erythema nodosum during isotretinoin therapy responding to dapsone. Clin Exp Dermatol 1997;22:26–7. 37. Wise CA, Gillum JD, Seideman CE, et al. Mutations in CD2BP1 disrupt binding to PTP PEST and are responsible for PAPA syndrome, an autoinflammatory disorder. Hum Mol Genet 2002;11:961–9. 38. Braun-Falco M, Kovnerystyy O, Lohse P, Ruzicka T. Pyoderma gangrenosum, acne, and suppurative hidradenitis (PASH) – a new autoinflammatory syndrome distinct from PAPA syndrome. J Am Acad Dermatol 2012;66:409–15. 39. Marzano AV, Trevisan V, Gattorno M, et al. Pyogenic arthritis, pyoderma gangrenosum, acne, and hidradenitis suppurativa (PAPASH): a new autoinflammatory syndrome associated with a novel mutation of the PSTPIP1 gene. JAMA Dermatol 2013;149:762–4. 40. Alhusayen RO, Juurlink DN, Mamdani MM, et al. Isotretinoin use and the risk of inflammatory bowel disease: a population-based cohort study. J Invest Dermatol 2013;133:907–12. 41. Smith LA, Cohen DE. Successful long-term use of oral isotretinoin for the management of Morbihan disease: a case series report and review of the literature. Arch Dermatol 2012;148:1395–8. 42. Jungfer B, Jansen T, Przybilla B, Plewig G. Solid persistent facial edema of acne: successful treatment with isotretinoin and ketotifen. Dermatology 1993;187:  34–7. 43. Hello M, Prey S, Léauté-Labrèze C, et al. Infantile acne: a retrospective study of 16 cases. Pediatr Dermatol 2008;25:434–8. 44. Arbegast KD, Braddock SW, Lamberty LF, Sawka AR. Treatment of infantile cystic acne with oral isotretinoin: a case report. Pediatr Dermatol 1991;8:166–8. 45. Bree AF, Siegfried EC. Acne vulgaris in preadolescent children: recommendations for evaluation. Pediatr Dermatol 2014;31:27–32. 46. Solomon LM, Fretzin D, Pruzansky S. Pilosebaceous abnormalities in Apert’s syndrome. Arch Dermatol 1970;102:381–5. 47. Risma KA, Lucky AW. Pseudoacne of the nasal crease: a new entity? Pediatr Dermatol 2004;21:427–31. 48. Boralevi F, Leaute-Labreze C, Lepreux S, et al. Idiopathic facial aseptic granuloma: a multicentre prospective study of 30 cases. Br J Dermatol 2007;156:705–8. 49. Neri I, Raone B, Dondi A, et al. Should idiopathic facial aseptic granuloma be considered granulomatous rosacea? Report of three pediatric cases. Pediatr Dermatol 2013;30:109–11. 50. Baroni A, Russo T, Faccenda F, Piccolo V. Idiopathic facial aseptic granuloma in a child: a possible expression of childhood rosacea. Pediatr Dermatol 2013;30:  394–5. 51. Prey S, Ezzedine K, Mazereeuw-Hautier J, et al.; Groupe de Recherche Clinique en Dermatologie Pédiatrique. IFAG and childhood rosacea: a possible link? Pediatr Dermatol 2013;30:429–32. 52. Larralde M, Abad M, Muñoz AS, et al. Childhood flexural comedones: a new entity. Arch Dermatol 2007;143:909–11. 52a.  Zaenglein AL, Pathy AL, Schlosser BJ, et al. Guidelines of care for the management of acne vulgaris. J Am Acad Dermatol 2016;74:945–73.

58. Koo EB, Petersen TD, Kimball AB. Meta-analysis comparing efficacy of antibiotics versus oral contraceptives in acne vulgaris. J Am Acad Dermatol 2014;71:450–9. 59. Arowojolu A, Gallo M, Lopez L, et al. Combined oral contraceptives for the treatment of acne. Cochrane Database Syst Rev 2009;(3):CD004425. 60. Lidegaard O, Lokkegaard E, Svendsen AL, et al. Hormonal contraception and risk of venous thromboembolism: national follow-up study. BMJ 2009;339:b2890. 61. van Hylckama Vlieg A, Helmerhorst FM, Vandenbroucke JP, et al. The venous thrombotic risk of oral contraceptives, effects of oestrogen dose and progestogen type: results of the MEGA case-control study. BMJ 2009;339:b2921. 62. Wu CQ, Grandi SM, Filion KB, et al. Drospirenonecontaining oral contraceptive pills and the risk of venous and arterial thrombosis: a systematic review. BJOG 2013;120:801–10. 63. Trenor CC 3rd, Chung RJ, Michelson AD, et al. Hormonal contraception and thrombotic risk: a multidisciplinary approach. Pediatrics 2011;127:347–57. 64. Carmina E, Lobo RA. A comparison of the relative efficacy of antiandrogens for the treatment of acne in hyperandrogenic women. Clin Endocrinol (Oxf ) 2002;57:231–4. 65. Goodfellow A, Alaghband-Zadeh J, Carter G, et al. Oral spironolactone improves acne vulgaris and reduces sebum excretion. Br J Dermatol 1984;111:  209–14.

66. Shaw JC. Low-dose adjunctive spironolactone in the treatment of acne in women: a retrospective analysis of 85 consecutively treated patients. J Am Acad Dermatol 2000;43:498–502. 67. Plovanich M, Weng QY, Mostaghimi A. Low usefulness of potassium monitoring among healthy young women taking spironolactone for acne. JAMA Dermatol 2015;151:941–4. 68. Barros B, Thiboutot D. Hormonal therapies for acne.   Clin Dermatol 2017;35:168–72. 69. Pochi PE, Shalita AR, Strauss JS, et al. Report of the Consensus Conference on Acne Classification. Washington, DC, March 24 and 25, 1990. J Am Acad Dermatol 1991;24:495–500. 70. Lee JW, Yoo KH, Park KY, et al. Effectiveness of conventional, low-dose and intermittent oral isotretinoin in the treatment of acne: a randomized, controlled comparative study. Br J Dermatol 2011;164:1369–75. 71. Lee YH, Scharnitz TP, Muscat J, et al. Laboratory monitoring during isotretinoin therapy for acne: a systematic review and meta-analysis. JAMA Dermatol 2016;152:35–44. 72. Hansen TJ, Lucking S, Miller JJ, et al. Standardized laboratory monitoring with use of isotretinoin in acne.   J Am Acad Dermatol 2016;75:323–8. 73. Huang YC, Cheng YC. Isotretinoin treatment for acne and risk of depression: a systematic review and meta-analysis. J Am Acad Dermatol 2017;76:1068–76.

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36 Acne Vulgaris

52b.  Coman GC, Holliday AC, Mazloom SE, et al. A randomized, split-face, controlled, double-blind, single-center clinical study: transient addition of a topical corticosteroid to a topical retinoid in acne patients to reduce initial irritation. Br J Dermatol 2017;177:567–9. 53. Johnson EM. A risk assessment of topical tretinoin as a potential human developmental toxin based on animal and comparative human data. J Am Acad Dermatol 1997;36:S86–90. 54. Navarre-Belhassen C, Blanchet P, Hillaire-Buys D, et al. Multiple congenital malformations associated with topical tretinoin [letter]. Ann Pharmacother 1998;32:505–6. 55. Buchan P, Eckhoff C, Caron D, et al. Repeated topical administration of all-trans-retinoic acid and plasma levels of retinoic acids in humans. J Am Acad Dermatol 1994;30:428–34. 56. Cunliffe WJ, Caputo R, Dreno B, et al. Clinical efficacy and safety comparison of adapalene gel and tretinoin gel in the treatment of acne vulgaris: Europe and US multicenter trials. J Am Acad Dermatol 1997;36:S126–34. 56a.  Walsh TR, Efthimiou J, Dréno B. Systematic review of antibiotic resistance in acne: an increasing topical and oral threat. Lancet Infect Dis 2016;16:e23–33. 57. Lee YH, Liu G, Thiboutot DM, et al. A retrospective analysis of the duration of oral antibiotic therapy for the treatment of acne among adolescents: investigating practice gaps and potential cost-savings. J Am Acad Dermatol 2014;71:70–6.

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eFig. 36.2 Open comedones in a patient with scarring cystic acne.  

eFig. 36.1 Infantile acne. Multiple open and closed comedones, papules and atrophic scarring. Courtesy, Holly Gunn, MD.  

A

eFig. 36.3 Acneiform eruption secondary to high-dose dexamethasone. Abrupt eruption of monomorphous follicular papules and pustules on the trunk.  

B

eFig. 36.4 Infantile acne. Presentations can range from scattered papulopustules (A) to multiple coalescing papulonodules and inflammatory cysts (B). If the latter child failed to improve with a topical retinoid plus an oral antibiotic, consideration would be given to oral isotretinoin. Courtesy, Kalman  

Watsky, MD.

eFig. 36.5 Disorders in the differential diagnosis of comedonal acne vulgaris – trichostasis spinulosa. Multiple vellus hairs and keratinous debris are found within the dilated follicular orifices. Courtesy, Judit Stenn, MD.  

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SECTION 6 ADNEXAL DISEASES

37 

Rosacea and Related Disorders Frank C. Powell and Síona Ní Raghallaigh

INTRODUCTION The term “rosacea” encompasses a constellation of clinical findings, with the key components being persistent facial erythema and inflammatory papulopustules. Additional features are facial telangiectasias, a tendency for frequent facial flushing (sometimes referred to as “prerosacea”), non-pitting facial edema with erythema, ocular inflammation, and phymatous changes. The latter predominantly affect the nose and rarely the ears, forehead, chin, or eyelids. In 2002, rosacea was classified into four clinical subtypes1: (1) erythematotelangiectatic; (2) papulopustular; (3) phymatous; and (4) ocular. There is also a granulomatous variant in which more monomorphous and persistent skin-colored to dull red–brown facial papules are seen. Some authors consider rosacea conglobata, characterized by an eruption of inflammatory cystic lesions that heal with scarring and rosacea fulminans (pyoderma faciale) to be within the rosacea spectrum. In rosacea fulminans, an explosive onset of inflammatory papules and pustules is superimposed on a background of facial erythema, usually occurring in young women and sometimes during pregnancy2.

HISTORY Robert Willan is credited with the earliest medical descriptions of “acne rosacea”, detailing what is nowadays classified as papulopustular rosacea3,4. Like acne vulgaris, rosacea was originally thought to have a “seborrheic” pathogenesis. It was Radcliff-Crocker who later postulated that repeated flushing leads to dilated leaky facial blood vessels with subsequent inflammatory skin changes.

EPIDEMIOLOGY Some publications regarding the frequency of rosacea within the general adult population may be invalid because of inadequate disease definitions5. In a 1989 study of over 800 office workers in Sweden, the prevalence of rosacea was found to be 10%6. The majority of affected individuals had facial erythema and telangiectasias without inflammatory skin lesions, presumably representing erythematotelangiectatic rosacea (ETTR); changes consistent with papulopustular rosacea (PPR) were observed in 1.8%. Utilizing a consensus definition of PPR1, a population study of 1000 individuals in Ireland detected a point prevalence of 2.7%7. A similar rosacea point prevalence rate of 2.3% was noted in a review of 90 880 German workers, although in this study clinical subtypes were not defined8. The prevalence of rosacea in patients with skin of color is not well studied but appears to be less common than in those with skin phototypes I and II9. Epidemiologic studies from countries where darkly pigmented individuals predominate population-wise suggest that the prevalence is far lower than in countries where the population is predominantly fair-skinned10. Recently, a national study of all adults in Denmark found that the risk of dementia, particularly Alzheimer disease, was increased for adults with rosacea who were >60 years of age11. A causal relationship has not been claimed and the results need to be confirmed by additional studies.

PATHOGENESIS 604

In rosacea, several different but interrelated pathomechanisms have been proposed (Fig. 37.1), with predominant pathways reflecting clinical features. Both environmental triggers and genetic predisposition play a role, with up to 20% of patients in some studies reporting a

family history of rosacea. Two of the major abnormalities are neurovascular dysregulation and an aberrant innate immune response, both of which can lead to cutaneous inflammation. Several clinical features of rosacea, including transient erythema, persistent centrofacial erythema, telangiectasias and flushing, point to the important role the vascular system plays in its pathogenesis. An increase in blood flow within skin lesions of rosacea has been demonstrated12, and patients with rosacea flush more readily in response to heat. Histopathologic studies of lesional skin found an elevated expression of vascular endothelial growth factor (VEGF), CD31, and the lymphatic endothelial marker D2-40 (podoplanin), implying increased stimulation of vascular and lymphatic endothelial cells13. In patients with rosacea, including ETTR, sensations of stinging or burning of the skin are commonly reported and affected individuals also exhibit lower heat pain thresholds, as compared to controls14. Stimulation of cutaneous nerve endings expressing transient receptor potential vanilloid (TRPV) cation channels by trigger factors (e.g. spicy food, heat, alcohol) can lead to dysesthesia, flushing, and erythema15. Heightened TRPV activity within the skin of patients with rosacea is associated with neurogenic inflammation, an inflammatory response induced by sensory nerves in which neuromediators are released at the site of inflammation. The latter can result in vasodilation, plasma extravasation of proteins, and recruitment of inflammatory cells (see Fig. 37.1). Evidence that an aberrant innate immune response also plays a role in the pathogenesis of rosacea includes upregulation of LL-37 via enhanced processing of cathelicidin by the trypsin-like serine protease kallikrein 516. When injected into mouse skin, cathelicidin peptides induced proinflammatory and angiogenic activity, leading to the proposal that dysfunction of the innate immune system could unify many of the clinical features of rosacea, especially the inflammatory lesions (see Fig. 37.1)17. In histopathologic studies of PPR, inflammatory changes were noted to be most pronounced near the bulge region of the pilosebaceous follicle18,19, the site of stem cells whose expression profile overlaps with that of the innate immune system. Based upon a higher prevalence in those with skin phototypes I and II (see above), ultraviolet light has been proposed as an additional contributing factor to the pathogenesis of rosacea. Exposure to UVB can induce angiogenesis and it increases the secretion of angiogenic factors (e.g. VEGF) from keratinocytes20. UVR also induces production of reactive oxygen species, which upregulate matrix metalloproteinases that lead to vascular and dermal matrix damage21. Although clinically ETTR can resemble telangiectatic photoaging, a case–control observational study provided evidence that they are distinct entities22; as expected, some patients have both disorders. In contrast, PPR does not appear to be significantly related to cutaneous photodamage or UV exposure7. Several clinical features of rosacea imply skin barrier dysfunction. Rosacea patients often report facial dryness, and studies have confirmed a lowered threshold for skin irritancy23. Both ETTR and PPR patients have increased transepidermal water loss, a marker of epidermal barrier dysfunction, and it has been suggested that disruption or abnormality of the stratum corneum allows penetration of sensory irritants24. In addition, patients with PPR have an abnormal skin surface fatty acid profile25 as well as reduced epidermal hydration levels; the latter were noted to improve following treatment with minocycline and resolution of inflammatory lesions26. Demodex mites (folliculorum and brevis) are normally present on the face as commensal microbes, but in rosacea, greater numbers of these mites are detected by skin surface biopsy techniques27,28. In routine histologic sections, the mites often appear prominently within pilosebaceous follicles and follicular infestation with multiple mites can be associated with an intense perifollicular infiltrate of predominantly

Rosacea is a common chronic facial dermatosis, most often affecting individuals with lighter skin phototypes and first appearing during middle age. Proposed pathomechanisms include abnormal cutaneous innate immune responses and neurovascular dysregulation. Clinical features are varied, from frequent facial flushing and telangiectasia to papules and pustules to phymatous changes and ocular inflammation. To assist in management, rosacea has been classified into four clinical subtypes: (1) erythematotelangiectatic (ETTR); (2) papulopustular; (3) phymatous; and (4) ocular. Treatment options for ETTR include vascular laser therapy and topical α-adrenoreceptor agonists. Topical and oral antibiotics, in particular low-dose doxycycline, as well as topical ivermectin are used to treat papulopustular rosacea. General skin care (e.g. sun avoidance), patient education on the need for maintenance therapy, and psychologic support are important aspects of the therapeutic approach to rosacea.

rosacea, acne rosacea, erythematotelangiectatic rosacea, papulopustular rosacea, phymatous rosacea, ocular rosacea, rhinophyma, granulomatous rosacea, lupus miliaris disseminatus faciei, flushing, perioral dermatitis, periorificial dermatitis, aberrant cutaneous innate immunity, Demodex, neurovascular dysregulation

CHAPTER

37 Rosacea and Related Disorders

ABSTRACT

non-print metadata KEYWORDS:

604.e1



MAJOR PATHOMECHANISMS IN ROSACEA



Environmental triggers (e.g. heat, alcohol)

Neurovascular dysregulation

↑ TRPV cation channels ↑ neuromediators, bradykinin, nitric oxide

Genetic predisposition

Additional pathogenic factors in rosacea (see text)

Aberrant innate immunity

• Ultraviolet radiation • Skin barrier dysfunction • Microbes (Demodex, staphylococci)

↑ Trigger recognition ↑ TLR2

Human cathelicidin

Stinging, burning (neurosensory symptoms)

Vasodilation

Flushing

from Steinhoff M, Buddenkotte J, Aubert J, et al. Clinical, cellular, and molecular aspects in the pathophysiology of rosacea. J Invest Dermatol Symp Proc. 2011;15:2–11.

↑ KLK5, a serine protease

hCAP18

↑ LL-37

Inflammation Cytokine release Plasma extravasation

Erythema, edema

Papules, pustules

37

Active antimicrobial peptide

Angiogenesis

Fibrosis, sebaceous gland and connective tissue hypertrophy

TRPV, transient receptor potential vanilloid TLR2, Toll-like receptor 2 KLK5, kallikrein 5

CHAPTER

Rosacea and Related Disorders

Fig. 37.1 Major pathomechanisms in rosacea. In genetically predisposed individuals (e.g. HLA-DRB1*03:01, HLA-DQA1*05:01, HLA-DQB1*02:01, SNP rs763035), environmental factors can trigger neurovascular dysregulation and an aberrant innate immune response, both of which can lead to cutaneous inflammation, including the clinical manifestations of rosacea. Adapted

Telangiectasia

Phymatous change

CD4 T helper cells29. Antigenic proteins from a bacterium (Bacillus oleronius) isolated from Demodex mites can stimulate inflammation in patients with PPR30. It has been suggested that Demodex mites and their associated bacteria upregulate local proteases, thereby potentiating dysregulation of the cutaneous innate immune response (see above)31. Lastly, it seems unlikely, based upon current evidence, that Helicobacter pylori infection plays an etiologic role in the pathogenesis of rosacea31a.

CLINICAL FEATURES Rosacea usually has its onset during middle age, with women often affected at a younger age than men. While rosacea is not commonly observed in children32, the rosacea-like conditions periorificial dermatitis and steroid-induced rosacea are fairly common. From a clinical perspective it is useful to classify rosacea into the following four subtypes (Table 37.1)1. However, this classification is intended as a guide given that there is some overlap amongst the subtypes and a patient can have more than one subtype. Erythematotelangiectatic rosacea (subtype 1; ETTR): Individuals have a tendency to flush combined with a background of persistent facial erythema (Fig. 37.2) and sometimes telangiectasias. These patients typically have skin phototypes I or II and it may be difficult to differentiate ETTR from telangiectatic photoaging, but there are some relative differences (see Table 37.3)22. In addition, when patients complain of significant flushing other causes of flushing should be considered as outlined in Tables 106.2 & 106.3. Papulopustular rosacea (subtype 2; PPR): Patients have a centrofacial eruption of multiple, small ( VZV)

**

Demodex spp. ,††

*

Drug-induced folliculitis Immunosuppression(or HIV-) associated eosinophilic folliculitis†,††

Rare

Less common

Common

Bacterial

* Requires skin scraping and KOH prep/microscopy for diagnosis ** Requires skin scraping for Tzanck prep/microscopy, viral culture, DFA and/or PCR for diagnosis

† Often requires biopsy for diagnosis †† Need to consider more strongly in immunosuppressed

individuals

Eosinophilic pustular folliculitis (Ofuji disease)† Eosinophilic pustular folliculitis in infancy

Fig. 38.2 Folliculitis (culture-negative). Follicular pustules with an erythematous rim are present on the back of an adolescent. The differential diagnosis is primarily folliculitis due to Staphylococcus aureus and acne. Courtesy, Julie V  

Schaffer, MD.

History

In 1965, Ise and Ofuji3 were the first to report a patient who had repeated episodes of follicular pustules on the face and back with peripheral blood eosinophilia. Five years later, Ofuji et al.4 described three additional patients and proposed the name “eosinophilic pustular folliculitis” for this new clinical entity. Of note, this is not to be confused with papuloerythroderma of Ofuji (see Ch. 25).

Epidemiology

Eosinophilic pustular folliculitis is a relatively rare entity, with most of the cases reported from Japan. The majority of patients are adults and the average age of onset is 30 years. The ratio of men to women is ~5 : 1 amongst Japanese patients. There have been occasional reports of eosinophilic pustular folliculitis in children, often with clinical features similar to the infantile form (see below).

Pathogenesis

The etiology and pathogenesis of eosinophilic pustular folliculitis is unknown. Proposed mechanisms include hypersensitivity reactions to various antigenic stimuli (e.g. infectious agents, medications) and immune dysfunction5.

Introduction

616

Eosinophilic pustular folliculitis is characterized by recurrent episodes of eruptive, intensely pruritic, follicular papulopustules. It typically affects “acne-prone” areas of the body such as the face, back, and extensor surface of the arms2. To date, this disorder has not been associated with systemic disease.

Clinical features

Recurrent crops of intensely pruritic, grouped, follicular pustules and papulopustules develop in a somewhat explosive fashion. In addition, there may be erythematous patches and plaques with superimposed coalescent pustules; central clearing and centrifugal extension produce annular and figurate lesions. Typically, areas with “sebaceous” follicles, such as the face, back, and extensor surface of the arms, are affected.

Immunosuppression-associated eosinophilic pustular folliculitis Synonyms:  ■ AIDS-associated eosinophilic folliculitis ■ HIV-associated eosinophilic folliculitis ■ Immunosuppression-associated eosinophilic folliculitis

Key features

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38 Folliculitis and Other Follicular Disorders

can be prescribed for the associated pruritus. First-line treatment for eosinophilic pustular folliculitis is oral indomethacin (50 mg/day). Second-line therapies include UVB phototherapy, oral minocycline (100 mg twice daily), oral dapsone (100 to 200 mg/day for ≥2 weeks), systemic corticosteroids, and colchicine (0.6 mg twice daily). Cyclospor­ ine may be considered in patients with refractory disease.

■ Markedly pruritic follicular papules, urticarial and/or pustular, that favor the face, scalp, and upper trunk ■ Occurs in the setting of immunosuppression, including from HIV infection and following allogeneic hematopoietic stem cell transplantation ■ In HIV-infected patients, the CD4 count is usually 1.5 cm in vertical diameter)

Excise with horizontal ellipse

Laser hair removal for permanent hair reduction

Extend excision below posterior hairline and include fascia or deep subcutaneous tissue

CHAPTER

38 Folliculitis and Other Follicular Disorders

Online only content

Allow to heal by second intention Do not inject corticosteroids into postoperative site Laser excision and cryosurgery are sometimes successful Postoperative care

Topical imiquimod daily for 6 weeks (or every other day for 8 weeks if irritation)

Maintenance

Tretinoin–corticosteroid gel mixture, intermittent intralesional corticosteroids and/or oral or topical antibiotics (when needed)

eTable 38.1 Therapeutic options for acne keloidalis.  

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ADNEXAL DISEASES SECTION 6

Diseases of the Eccrine and  Apocrine Sweat Glands

39 

Jami L. Miller

Chapter Contents Sweat glands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 633 Hyperhidrosis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 633 Hypohidrosis and anhidrosis . . . . . . . . . . . . . . . . . . . . . . . . 640 Abnormalities and alterations of eccrine and apocrine sweat composition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 642 Diagnostic microscopic changes in eccrine sweat glands . . . . . 642 Influence of sweat on skin diseases . . . . . . . . . . . . . . . . . . . 643 Additional disorders of the eccrine sweat gland . . . . . . . . . . . 643 Disorders of the apocrine sweat gland . . . . . . . . . . . . . . . . . 647

SWEAT GLANDS Eccrine Sweat Glands Key features ■ 2–5 million eccrine glands are unevenly distributed over the skin surface ■ In healthy individuals, eccrine sweat is 99% water ■ Sweating is a reflex sympathetic autonomic function mediated by cholinergic neurons

In humans, sweating is essential for thermoregulatory homeostasis. There are two main mechanisms for cooling the body: radiative cooling via cutaneous vasodilation and evaporative cooling via sweat. Sweat, primarily produced by the eccrine sweat glands, leads to dissipation of heat through evaporation. Few mammals except humans and horses produce sweat in sufficient quantities to affect thermoregulation. For the purposes of this discussion, the term “sweat” applies to eccrine glands and their secretory products unless otherwise specified. Although there are 2–5 million eccrine glands distributed within the skin, none are found on the clitoris, glans penis, labia minora, external auditory canal, or lips. Eccrine glands are separate from the apocrinepilosebaceous apparatus, and by dermoscopy, eccrine ductal orifices can be seen along the dermatoglyphic ridges of the palms and soles. The average healthy adult can produce over 0.5 liters of sweat per hour, 99% of which is water. Athletes or those acclimatized to hot environments can produce up to 3–4 liters per hour1. Physically fit or acclimatized persons initiate sweating earlier and conserve sodium, chloride, and other electrolytes more efficiently. Thermoregulatory control is similar in men and women and diminishes only slightly with age2. Sweating is a reflex function controlled primarily by the sympathetic nervous system. These nerves are anatomically sympathetic but functionally cholinergic, i.e. acetylcholine, rather than norepinephrine, is the principal terminal neurotransmitter. Neural impulses for sweating (sudomotor impulses) travel from the anterior hypothalamus via the reticulospinal tracts to the appropriate level in the spinal cord, out through the rami communicantes to autonomic ganglia, and then within sympathetic cholinergic neurons to the secretory cells of the

eccrine glands. Adrenergic innervation of eccrine glands has also been demonstrated, but is not believed to be physiologically important3. In addition, the sweat glands, via a direct effect on the secretory cells, respond to certain drugs (e.g. cholinergic agonists) as well as to the local application of heat.

Apocrine Sweat Glands In humans, apocrine sweat glands are confined to the eyelids (Moll’s glands), external auditory meatus, axillae, areola and nipple, periumbilical region, and anogenital region, in particular the mons pubis, labia minora, prepuce, scrotum, and perianal area. At five months gestation, apocrine glands are distributed all over the body, whereas in a full-term neonate they are limited to the above sites. In non-primate mammals, apocrine sweat glands are widely distributed but they also open into the pilosebaceous unit. Apocrine secretion is a slow, usually continuous process analogous to milk formation in the mammary gland. The secretory product is an oily fluid composed of lipids, proteins, and sex hormones. At or near the skin surface, it mixes with sebum derived from the sebaceous gland that empties into the same pilosebaceous unit.

HYPERHIDROSIS Key features ■ Excessive sweating ■ Primary hyperhidrosis is the most common type, typically affecting the palms, soles, and/or axillae ■ Secondary hyperhidrosis is due to an underlying condition (e.g. genetic syndrome, infection, tumor) or medication and may be localized or generalized

Hyperhidrosis is estimated to affect 3% of the US population4. The most widely used classification system divides it into primary and secondary types. Other classification systems separate hyperhidrosis into categories based on the source of the neural impulses that drive it: cortical (emotional), hypothalamic (thermoregulatory), medullary (gustatory), spinal cord, and local axon reflexes.

Primary Hyperhidrosis Synonym:  ■ Primary focal hyperhidrosis

Key features ■ Main sites are volar (palms, soles) and axillary skin; the face may also be involved ■ Hyperhidrosis arises from increased cortical stimulation and occurs only during waking hours (diurnal) ■ Patients are otherwise healthy ■ Up to 80% of affected individuals have a family history of hyperhidrosis

633

Sudoriferous glands, i.e. sweat glands, lie within the dermis and subcutaneous fat. There are two types of sweat glands: eccrine and apocrine. Eccrine sweat glands represent the vast majority of sweat glands within human skin whereas apocrine glands have a much more limited distribution. The most commonly used classification system for hyperhidrosis divides it into primary and secondary types. Other classification systems separate hyperhidrosis into categories based on the source of the neural impulses that drive it: cortical (emotional), hypothalamic (thermoregulatory), medullary (gustatory), spinal cord, and local axon reflexes. Treatment options for axillary and volar hyperhidrosis include topical aluminum chloride, oral agents (anticholinergics, α- or β-adrenergic blockers, α2-adrenergic agonists), onabotulinumtoxinA, iontophoresis, biofeedback therapy, and surgical procedures. Causes of hypo- and anhidrosis include central or neuropathic disruption of neural impulses, sweat gland abnormalities, and medications. In addition to abnormal function, specific sweat gland disorders (e.g. miliaria, neutrophilic eccrine hidradenitis) are primarily related to obstruction or inflammation.

eccrine gland, apocrine gland, sweat gland, sweat, hyperhidrosis, hypohidrosis, anhidrosis, miliaria, neutrophilic eccrine hidradenitis, Fox–Fordyce disease, chromhidrosis, bromhidrosis, granulosis rubra nasi, keratolysis exfoliative, idiopathic palmoplantar hidradenitis

CHAPTER

39 Diseases of the Eccrine and Apocrine Sweat Glands

ABSTRACT

non-print metadata KEYWORDS:

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Primary hyperhidrosis, the most common type of hyperhidrosis, is defined as excessive sweating in localized areas (usually the palms, soles, and/or axillae) and is not associated with a systemic disorder. Men and women of all races are equally affected. Table 39.1 lists the diagnostic criteria5. Between 60% and 80% of patients with primary hyperhidrosis have a family history6, with a pattern of inheritance suggesting autosomal dominant transmission with incomplete penetrance. A locus for primary palmar hyperhidrosis was mapped to chromosome 14q in three Japanese families7. Intense emotion or stress can elicit sweating in anyone. It occurs most often on the palms, soles, or axillae and can also affect the face (Fig. 39.1), especially the forehead and the cutaneous upper lip. The post-orgasmic sweating observed with sexual activity may also derive from emotional stimulation8. Clinically significant primary hyperhidrosis occurs in two major patterns: volar (palmoplantar) and axillary, which can coexist1, but usually one of the two sites predominates. The onset of volar hyperhidrosis is often during childhood, whereas axillary hyperhidrosis typically develops at or soon after puberty. Primary hyperhidrosis is seen in both cold and warm environments. A chronic and unremitting course is characteristic, with little or no variation in association with age, disease, or hormonal status. Volar hyperhidrosis is the most common form of primary hyper­ hidrosis (Fig. 39.2), affecting ~50–60% of patients3,4. The entire palm and sole, as well as the lateral aspects, tips and distal dorsal skin of the fingers, display sweating. It can clearly have an impact on quality of life. Axillary hyperhidrosis is the second most common form of primary hyperhidrosis, affecting 30–50% of patients4. The right axilla usually produces more sweat than the left (60 : 40). Exceptionally, one axilla

may be hyperhidrotic while the opposite axilla is hypohidrotic or virtually anhidrotic. Odor (axillary bromhidrosis) is usually absent; the excessive quantities of eccrine sweat presumably rinse away or dilute odorogenic apocrine sweat droplets and bacteria.

Secondary Hyperhidrosis Secondary hyperhidrosis is caused by or associated with another systemic disorder. It may be localized or generalized. There are many causes, which can be divided into categories based on the source of the neural impulse driving the response: cortical, hypothalamic, medullary, spinal cord, or local. A number of medications may also be associated with hyperhidrosis (Table 39.2).

Disorders associated with cortical (emotional) hyperhidrosis

Key features ■ Several disorders of cornification and other genodermatoses affecting palmoplantar skin are associated with volar hyperhidrosis ■ Patients with hereditary autonomic neuropathies can also exhibit cortical hyperhidrosis Isolated sweating of the palms and soles is primarily due to cortical excitation by emotional or sensory stimuli. Excessive volar sweating associated with certain inherited palmoplantar keratodermas is assumed to be cortical in nature, although the pathogenic relationship between the abnormal keratinization and hyperhidrosis has not been precisely

CRITERIA FOR THE DIAGNOSIS OF PRIMARY HYPERHIDROSIS 1. Focal, visible excess sweating 2. Present for at least 6 months 3. No apparent secondary causes 4. At least two of the following: • Bilateral and symmetric • Impairs activities of daily life • At least one episode per week • Age of onset junctional Dermatopathia pigmentosa reticularis • Dyskeratosis congenita • Pachydermoperiostosis (digital clubbing and thick, furrowed skin on the face and scalp) • Apert syndrome (craniosynostosis, digital anomalies, severe acne; FGFR2 mutations) • Nail–patella syndrome













Antidiabetic (hypoglycemic) agents Insulins



Sulfonylureas



CNS stimulants Amphetamines Caffeine



Theophylline





MAOIs† SSRIs†

Tricyclics†





Antipsychotics Antipyretics

†Hypothalamic (thermal) hyperhidrosis can also occur.

Opioids

Table 39.3 Causes of cortical (stress/emotional) hyperhidrosis. Adapted from  

Other drugs ACE inhibitors Amlodipine • Atomoxetine • Dextromethorphan ,† * • Ipecac • Pentoxifylline • •

Familial dysautonomia (Riley–Day syndrome; HSAN type III; blotchy erythema accompanies episodic hyperhidrosis of the face and trunk, decreased lacrimation, postural hypotension, and dysautonomic crises [vomiting, hypertension]) • Congenital autonomic dysfunction with universal pain loss • Congenital sensory neuropathy (HSAN type II) •

Antidepressants •

Hereditary sensory and autonomic neuropathies (HSANs)†

39 Diseases of the Eccrine and Apocrine Sweat Glands

DRUGS THAT CAN STIMULATE ECCRINE SWEATING

Moschella S, Hurley HV. Dermatology. Philadelphia: WB Saunders, 1992.

Phosphodiesterase inhibitors (e.g. sildenafil) • Sibutramine† • Sumatriptan† • Tramadol† • Yohimbine •

*Increased sweating is infrequently observed at pharmacologic doses but represents a sign of overdose.

†Combination of MAOIs (which include linezolid as well as antidepressants) with drugs such

as tricyclics, SSRIs, certain opioids and tryptophan can result in the serotonin syndrome, which is characterized by mental status changes, autonomic hyperactivity (including hyperhidrosis), and neuromuscular abnormalities.

Table 39.2 Drugs that can stimulate eccrine sweating. ACE, angiotensinconverting enzyme; CNS, central nervous system; MAOI, monoamine oxidase inhibitor; SSRI, selective serotonin reuptake inhibitor.  

delineated. Many palmoplantar keratodermas are malodorous, likely related to sweat-induced maceration of the thickened stratum corneum and bacterial degradation of keratin. Other genodermatoses affecting the volar skin, such as epidermolysis bullosa simplex, can also have associated palmoplantar hyperhidrosis. Additional causes of cortical hyperhidrosis are listed in Table 39.3.

Hypothalamic (thermoregulatory) hyperhidrosis

Key features ■ Due to elevated body temperature (e.g. acute febrile illness, lymphoma, chronic infection) or direct hypothalamic stimuli (e.g. pheochromocytoma, medications, toxins) ■ May be nocturnal (night sweats) or diurnal The hypothalamus is responsible for many autonomic activities, including thermoregulation. Elevation of the temperature of the blood by 0.5°F or more excites the hypothalamic nuclei and results in vascular dilation and generalized sweating responses aimed at dissipating body heat3. Febrile illnesses are among the most common pathologic states that cause hypothalamic sweating. At the height of the fever, notably with

temperatures of 39–40°C (102–104°F) or above, sweating is absent, the apparent result of inhibition of the hypothalamic center for sweating. With defervescence, sweating characteristically ensues. Lymphomas and chronic infections (e.g. tuberculosis) can present with episodic thermoregulatory sweating, which may be described as “night sweats” (that actually follow unperceived mild febrile pulses). Generalized sweating of hypothalamic origin can also be seen in a number of metabolic and endocrine disorders (Table 39.4). Patients with diabetes mellitus may exhibit hypohidrosis as well as various forms of hyperhidrosis. For example, hyperhidrosis is a characteristic sign of insulin-induced hypoglycemia (but not diabetic ketoacidosis), and compensatory hyperhidrosis of the trunk can develop in the setting of diabetic neuropathy affecting the extremities (see below). In addition, diabetics may exhibit gustatory hyperhidrosis, primarily of the face and neck. Troublesome sweating of the scalp can also be seen in poorly controlled diabetics, and, with regulation of the hyperglycemia, the hyperhidrosis often improves. Disorders with vasomotor instability, such as Raynaud phenomenon, autoimmune connective tissue diseases, frostbite and other cold injuries, and reflex sympathetic dystrophy, may be associated with excessive sweating because of disturbed autonomic function9. A synchronous discharge of vasoconstrictor and sudomotor impulses evokes a “cold sweat”, usually of the hands and feet, producing macerated, soggy wet, violaceous skin known as symmetrical lividity. Cerebral cortex lesions, such as a tumor, abscess or cerebrovascular accident, may be associated with a contralateral hyperhidrosis due to an impairment of the inhibitory cortical influence that normally regulates hypothalamic sudomotor activity10. Hypothalamic sweating is also observed in Parkinson disease and occurs as the “sweating sickness” following encephalitis. Harlequin syndrome, characterized by unilateral flushing and hyperhidrosis in association with contralateral anhidrosis, may be due to peripheral or central nervous system (CNS) abnormalities11. Episodic release of catecholamines from pheochromocytomas directly stimulates the hypothalamus and may elicit sweating12. Exposures to toxins and medications can also lead to hypothalamic hyperhidrosis, and a number of drugs that act on the CNS have increased sweating as a potential side effect (see Table 39.2). Additional causes of hypothalamic hyperhidrosis are presented in Table 39.4.

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CAUSES OF HYPOTHALAMIC HYPERHIDROSIS

Infection

Tumors

Acute febrile illnesses (defervescence) • Tuberculosis • Brucellosis • Malaria • Subacute bacterial endocarditis • Other





Lymphoma • Pheochromocytoma * • Carcinoid *

Endocrine/ metabolic Hyperthyroidism • Acromegaly • Hypoglycemia • Obesity • Menopause • Pregnancy • Porphyria (acute intermittent) • Phenylketonuria • Gout •

Vasomotor

Neurologic

Drugs/toxins

Miscellaneous

Congestive heart failure† • Myocardial ischemia • Raynaud phenomenon • Acrocyanosis • Cold injury • Symmetrical lividity of the palms and soles‡ • Reflex sympathetic dystrophy • Autoimmune connective tissue disease (e.g. rheumatoid arthritis, SLE)



CNS tumors • Cerebrovascular accidents • Parkinson disease • Postencephalitic • Episodic spontaneous hypothermia with hyperhidrosis§ • Cold-induced sweating syndrome∥ • Familial dysautonomia‡



Alcoholism • Alcohol or opioid withdrawal • Mercury toxicity (acrodynia) • Chronic arsenic toxicity • See Table 39.2





Compensatory hyperhidrosis (e.g. in association with miliaria, diabetic neuropathy, sympathectomy)¶ • Localized unilateral hyperhidrosis (face and neck, forearm)‡ • POEMS syndrome • Speckled lentiginous nevus syndrome • Mitochondrial disorders • Pressure and postural hyperhidrosis‡

*† Via release of catecholamines (pheochromocytoma) and serotonin (carcinoid tumors, usually metastatic; see Ch. 106). Patients have sympathetic activation, with impaired vasodilatory responses to heating but preserved sweating.

‡Also associated with cortical hyperhidrosis. §Referred to as Hines–Bannick syndrome or, when associated with agenesis of the corpus callosum, Shapiro syndrome. ∥Autosomal recessive condition caused by mutations in the genes encoding cytokine receptor-like factor-1 and cardiotrophin-like cytokine factor-1; additional features include facial dysmorphism,

flexion deformities (elbows, fingers), and scoliosis.

¶Compensatory hyperhidrosis is also a feature of Ross syndrome (segmental anhidrosis, generalized areflexia and tonic pupils).

Table 39.4 Causes of hypothalamic hyperhidrosis. SLE, systemic lupus erythematosus. Adapted from Moschella S, Hurley HV. Dermatology. Philadelphia: WB Saunders, 1992.  

Pressure and postural hyperhidrosis may be due to hypothalamic or possibly cortical stimulation. With changes in posture or the application of pressure to one side of the supine individual, a variety of sweating patterns have been described, such as lateral hyperhidrosis, horizontal hemihidrosis, and crossed hemihidrosis. Idiopathic localized unilateral hyperhidrosis of the face and neck or forearm has been reported as an episodic disorder triggered by heat, emotional, or gustatory stimuli13.

Medullary (gustatory) hyperhidrosis

Key features ■ Taste receptors in the mouth are the source of the afferent impulses that stimulate sweating ■ Physiologic medullary hyperhidrosis is most commonly triggered by spicy foods, alcohol, and citrus fruits ■ Pathologic medullary hyperhidrosis occurs when disrupted nerves for sweat aberrantly connect with nerves for salivation; this can be caused by local injury to, or disease of, the parotid gland (Frey syndrome), trauma to the sympathetic trunk, and CNS disorders (e.g. encephalitis, syringomyelia)

Physiologic medullary hyperhidrosis

636

Any food or drink that stimulates the taste buds may induce sweating in normal individuals, particularly of the face. This is thought to occur via a variant reflex arc in which afferent impulses from taste bud receptors travel via the glossopharyngeal nerve to nuclei within the medulla oblongata (hence the term “medullary” hyperhidrosis), but lead to provocation of sweating rather than (or in addition to) the usual response of salivation. A few minutes after ingestion of a stimulating food or beverage, sweating and erythema are seen most commonly on the upper cutaneous lip or cheeks. It may be unilateral or bilateral and may be brief or persist as long as the stimulating food or beverage is

ingested. Associated vasodilation localized to the areas of sweating causes the erythema, which may be faint. Spicy or sharp-tasting foods and beverages, such as citrus fruits, alcohol and condiments, may elicit the reaction. It is most common in children and young adults and in warmer environments. A familial tendency has been described14. There are no other concurrent local or systemic signs or symptoms. A variant of gustatory hyperhidrosis can occur on the face in diabetics. Unusual types of gustatory hyperhidrosis involving the scalp and the knee have also been described and support the concept of a central medullary mechanism for these sweating responses15.

Pathologic medullary hyperhidrosis

This disorder arises after disruption of nerves. During healing, nerve fibers mediating sweating aberrantly connect to nerves that mediate salivation. Impulses in parasympathetic fibers normally supplying the salivary glands are now misdirected to the sweat glands. As a result, salivary stimulation elicits sweating. Of note, thermal sweating in the areas of affected skin is reduced. The parotid form appears weeks to months following surgery, trauma, or other disorder (e.g. abscess, herpes zoster) affecting the parotid gland. These patients experience vasodilation and sweating on the cheek and adjacent neck when salivary stimulation is induced by eating, drinking, or even chewing (Fig. 39.3). Sweating most often occurs in the distribution of the auriculotemporal nerve; at times there is also unilateral localized pain16. Auriculotemporal syndrome (Frey syndrome) is common after parotid surgery, developing in 40% or more of patients, although many are not aware of it. It can also occur during infancy (frequently as a consequence of trauma to the parotid region in a forceps-assisted delivery), presenting with gustatory flushing, but usually no obvious sweating, that is often erroneously attributed to food allergy. Another variant of gustatory hyperhidrosis is the chorda tympani syndrome in which salivary stimuli to the submandibular gland induce sweating on the chin and lower jaw line. Patients with cluster headaches can have sympathetic deficits that result in impaired thermoregulatory sweating on the affected side of

Any injury or disease process that severs or interferes with the reticulospinal tracts of the cord can disrupt the sweating reflex (see Table 39.5). Lack of a sweat response to thermal stimulation usually occurs below the level of the injury. Abnormal patterns of segmental sweating may occur in conjunction with other autonomic, sensory, and motor alterations. Onset and duration are unpredictable. Sweating can be excessive, drenching the patient in the regions involved. Bouts of “mass reflex sweating” are initiated in the skin below the level of the cord interruption. It is most intense in skin segments close to the level of the transection. Mass reflex sweating does not occur in transections below T8–T10.

Autonomic dysreflexia

Key features ■ Direct stimulation (e.g. electrical, physical, or drug-induced) of a sympathetic axon can cause sweating ■ May be seen with inflammatory skin diseases

Spinal (cord transection) sweating

CHAPTER

39 Diseases of the Eccrine and Apocrine Sweat Glands

the forehead. In addition, ipsilateral hyperhidrosis and flushing may occur together with excessive lacrimation during headache attacks. This is due to misdirection of parasympathetic fibers, which normally supply the lacrimal glands, to sweat glands and blood vessels. Patients with Raeder syndrome (Horner syndrome [ptosis, meiosis ± anhidrosis] plus unilateral temporofrontal headaches and pain) may also have excessive supraorbital sweating (lacrimal sweating). Any condition that injures the vagus nerve and sympathetic trunk, as they lie close together in the thorax, may cause a pathologic medullary hyperhidrosis (Table 39.5). Cholinergic fibers from the vagus nerve sprout into the adjacent sympathetic trunk during the healing process and can result in a gustatory hyperhidrosis with sweating on the face, neck, and portions of the trunk and upper extremities. In patients with syringomyelia or encephalitis, gustatory hyperhidrosis is occasionally seen on the face and upper trunk. It involves the glossopharyngeal and vagus nerves. Disturbances in the brainstem apparently lead to transposition of the central medullary nuclei for salivation and sweating. There is no peripheral crossing of sympathetic and parasympathetic nerve fibers as is seen in other forms of pathologic gustatory hyperhidrosis.

Autonomic dysreflexia is a syndrome that may occur with spinal injuries at or above T617. Massive episodic sympathetic discharge results in sweating above the level of the transection accompanied by headache, hypertension, facial flushing, bradycardia or tachycardia, piloerection, and paresthesias. Direct stimulation of a cutaneous sympathetic axon with electrical and physical impulses or injections of drugs with nicotine-like effects on autonomic ganglia can induce sweating in an area ~4 cm in diameter3. Mediators from inflammatory skin conditions (e.g. psoriasis, dermatitis) can also elicit localized hyperhidrosis. Substance P and a number of other mediators, including kinins, dopamine, prostaglandins, angiotensin and adenine, may be involved18.

Key features ■ Spinal disorders may result in a lack of thermal sweating below the injury as well as unusual patterns of hyperhidrosis ■ Mass reflex sweating may occur around the injured level

Compensatory hyperhidrosis

Key features ■ Anhidrosis in one area may cause hyperhidrosis in another ■ Miliaria, diabetic neuropathy, and sympathectomy are well-known causes

The coordinated functioning of the body’s eccrine sweat glands is illustrated by the phenomenon of compensatory hyperhidrosis, in which the sweat glands of one area become hyperactive in an effort to compensate for hypo- or anhidrosis in another. Apparently, a threshold number of sweat glands must be non-functional in order for the compensatory response to occur. The nature or type of the underlying process that produces the anhidrosis also appears to be important. For example, compensatory hyperhidrosis does not seem to develop secondary to the anhidrosis produced by lymphomas.

Fig. 39.3 Gustatory sweating in the auriculotemporal (Frey) syndrome, as a consequence of parotid surgery. The blue–black area represents sweating (starch–iodine technique). Salivary stimulation induced this sweating response.  

Reproduced from Hurley HJ. Hyperhidrosis. Curr Opin Dermatol. 1997;4:105–14. Philadelphia: Rapid Science Publishers.

OTHER CAUSES OF SECONDARY HYPERHIDROSIS

Abnormal blood vessels or eccrine glands (non-neural)

Medullary (gustatory)

Spinal cord

Axon reflex



Physiologic gustatory sweating Frey syndrome • Chorda tympani syndrome • Cluster headaches • Sympathectomy • Sympathetic trunk and vagus nerve injury (e.g. by lung carcinoma, mesothelioma, thyroidectomy, subclavian aneurysm) • Encephalitis • Syringomyelia



Spinal injury Syringomyelia • Tabes dorsalis













Inflammatory skin diseases Drugs (see Table 39.2)

Aquagenic palmoplantar keratoderma Eccrine nevi • Eccrine angiomatous hamartoma (Fig. 39.5) • Maffucci syndrome • Arteriovenous fistula • Klippel–Trenaunay syndrome • Glomuvenous malformation • Blue rubber bleb nevus syndrome • Cold erythema • Granulosis rubra nasi • Pretibial myxedema

Table 39.5 Other causes of secondary hyperhidrosis. Gustatory lacrimation (“crocodile tears” syndrome) is due to transposition of autonomic fibers for lacrimation and salivation after facial nerve injury. Adapted from Moschella S, Hurley HV. Dermatology. Philadelphia: WB Saunders, 1992.  

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The best-known clinical forms of compensatory hyperhidrosis occur in the following three situations: Miliaria: longstanding or recurrent miliaria rubra or profunda typically results in numerous non-functional sweat glands within large areas of the trunk. This induces compensatory hyperhidrosis of the face (Fig. 39.4A), especially in response to ambient heat or exercise. In diabetes mellitus, disturbance of the autonomic nervous system due to peripheral neuropathy and microangiopathy often causes anhidrosis or hypohidrosis of the affected skin, particularly the legs. With the loss of sweating on the lower extremities, these patients may develop compensatory increases in thermal sweating on the trunk, especially the back. A second type of compensatory hyperhidrosis, gustatory in character and usually on the face and neck (Fig. 39.4B), may also be seen in diabetic patients with peripheral neuropathy of the lower extremities. Post-sympathectomy: with the loss of sweating that results from cervicothoracic sympathectomies, a thermal hyperhidrosis, usually on the trunk, is common. Sympathectomized patients may also experience gustatory hyperhidrosis.

• •



Non-neural hyperhidrosis

Key features ■ Direct stimulation of eccrine glands can cause sweating ■ Triggers include local heat, drugs, and vascular tumors Direct stimulation of eccrine sweat glands by heat or sudomimetic drugs can lead to localized sweating. Even denervated skin sweats when heat is applied3. Table 39.5 outlines additional non-neural causes of localized hyperhidrosis, including increased activity of eccrine glands overlying vascular lesions such as eccrine angiomatous hamartoma (Fig. 39.5). The rare disorder “cold erythema” affects the skin and

FACIAL COMPENSATORY HYPERHIDROSIS

Fig. 39.4 Compensatory hyperhidrosis of the face. A Outline of the sites of facial compensatory hyperhidrosis in patients with extensive miliaria. B Facial compensatory hyperhidrosis (upper lip and chin) in a patient with diabetes mellitus (starch–iodine technique). Courtesy, Harry Hurley, MD.  

gastrointestinal tract – exposure to cold produces local cutaneous erythema and intense pain along with a central area of hyperhidrosis. As with other entities in which local pain is a clinical feature (e.g. glomuvenous malformations), increased blood flow or an axon reflex (secondary to the pain) may be the casual mechanism for this sweating.

Diagnosis of Hyperhidrosis Key features ■ Differentiation between primary and secondary hyperhidrosis is important ■ Hyperhidrosis can be documented by colorimetric and gravimetric methods

The first step is to differentiate between primary and secondary hyperhidrosis. History will elicit location, duration, and specific triggers. Other medical disorders and medications (including over-the-counter products) need to be ascertained. An extensive review of systems should point to any secondary causes. Patients who do not fit the classic pattern of primary hyperhidrosis (see Table 39.1) should undergo further evaluation, focusing on possible etiologies (see Tables 39.2–39.5) during a complete history and physical examination. Laboratory testing and radiographic studies may be needed (Table 39.6). Measurement of sweat can be performed. A grading scale for volar disease lists “low” as a moist palm or sole without visible sweat droplets. “Moderate” disease is characterized by sweating toward the fingertips. “Severe” cases drip sweat. Axillary involvement can be measured by the sweat stains on clothing: 20 cm, severe. Colorimetric techniques such as the starch–iodine or quinizarin methods demonstrate the sweating pattern and reveal the location of the most active sweat glands in a given area19. In the starch–iodine technique, iodine solution (e.g. 3.5% in alcohol) is applied to clean, shaved skin and allowed to dry. Starch powder (e.g. cornstarch) is then brushed onto the area. Sites with sweating turn blue–black (Fig. 39.6). A combination of iodine and paper impregnated with starch can also be utilized (Fig. 39.7). Additional quantitative assessment methods are available. In order to document amounts of sweat produced, gravimetric (via weighing filter paper before and after application to the skin) and evaporative (via a device that assesses water vapor loss from the skin) measurements can be made in volar or axillary sites19. Infrared thermography

Fig. 39.5 Eccrine angiomatous hamartoma. Cluster of painful pink–violet papules and plaques on the thigh and knee that had been present since one year of age. There was associated hyperhidrosis, but not hypertrichosis. Histologically, an increased number of both eccrine glands and small blood vessels is seen. Courtesy, Julie V Schaffer,  

$

MD.

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CHAPTER

Laboratory test

Disease

Serum electrolytes, BUN, creatinine

Renal disease (rare)

Fasting blood glucose level and/or HbA1c

Diabetes mellitus

Thyroid function tests

Hyperthyroidism

Skin and/or blood tests for tuberculosis (e.g. PPD, QFTB-G)

Tuberculosis

Chest X-ray

Tuberculosis, neoplasm

Complete blood count

Infection

Sedimentation rate/C-reactive protein test

Infection, neoplasm, inflammatory disease

Antinuclear antibodies

Autoimmune connective tissue disease

Urinary catecholamines*

Pheochromocytoma

*If suggestive signs or symptoms (see Ch. 106). Table 39.6 Initial patient evaluation for secondary hyperhidrosis. Further evaluation depends upon results and consideration of entities in Table 39.4. BUN, blood urea nitrogen; PPD, (tuberculin) purified protein derivative; QFTB-G, QuantiFERON-TB Gold.

Fig. 39.7 Palmar hyperhidrosis as assessed by the semiquantitative starch paper–iodine technique. Sweating can also be demonstrated directly on palmar skin by the starch–iodine technique, as shown in Fig. 39.6 for axillary hyperhidrosis. Courtesy, Harry Hurley, MD.  

Diseases of the Eccrine and Apocrine Sweat Glands

39

INITIAL PATIENT EVALUATION FOR SECONDARY HYPERHIDROSIS



Fig. 39.6 Delineation of area for injections of botulinum toxin A for axillary hyperhidrosis (starch–iodine technique). The blue–black area represents foci of sweating (reflected in black dots). In the case of onabotulinumtoxinA, a total of 50–100 U is injected within this area, utilizing 10 to 15 injection sites. Courtesy,  

Alastair Carruthers, MD, and Jean Carruthers, MD.

represents another method of evaluating sweat gland function, allowing comparison between anatomic areas and even individual glands.

Treatment of Hyperhidrosis Key feature ■ Treatment options for hyperhidrosis include topical aluminum chloride, oral agents (anticholinergics, α- or β-adrenergic blockers, α2-adrenergic agonists), onabotulinumtoxinA, iontophoresis, biofeedback therapy, and surgical procedures

Treatment options available for hyperhidrosis are outlined in Table 39.7. Over-the-counter products include antiperspirants and deodorants; the latter contain antimicrobial agents while both contain odor-masking fragrances. The major active ingredient in topical antiperspirants is aluminum salts which deposit within and temporarily block the sweat

duct. In prescription antiperspirants, there are higher concentrations of these salts. They should be applied to dry surfaces at night, when sweating is diminished. Occlusion enhances penetration of the salts. Application is recommended for three to five consecutive nights, then one to two times a week as needed to control sweating. Treated skin can be washed the following morning. Burning and irritant contact dermatitis are common side effects, particularly in women who shave their axillae and with higher salt concentrations. Some patients who sweat significantly at night require a preliminary dose of an anticholinergic drug 1 hour before application for the first few applications (see below). This reduces sweating enough to prevent the topical solution from being rinsed away. Topical aldehyde agents such as formaldehyde and glutaraldehyde are effective, but allergic sensitization may develop that can result in cross-reactions with aldehydes in the environment (lotions, soaps, shoes). Tap water iontophoresis over 20 minutes two to three times a week may be helpful. The mechanism of action is unknown but is thought to lead to blockage of the sweat duct in the stratum corneum. Side effects are minimal and include tingling of the skin during treatment. Introduction of anticholinergic medications via iontophoresis is not advised due to potential systemic absorption. Oral anticholinergics will decrease sweating in most patients. The most commonly used agents are oxybutynin20 and glycopyrrolate21 (see Table 39.7 for recommended regimens). When higher doses are required to control the hyperhidrosis, unacceptable side effects can often develop, including dry eyes and mouth, insomnia, mental status changes (e.g. confusion, hallucinations), palpitations, seizures, blurred vision, bowel disturbances, urinary retention, and hypertension. Clonidine (an α2-adrenergic agonist that decreases central sympathetic outflow) and phenoxybenzamine (an α-adrenergic blocker) have been used with some success in anecdotal reports22,23. Potential side effects include hypotension, rebound hypertension, sedation, constipation, weakness, and headache. Propranolol, a β-adrenergic blocker, is commonly used for the treatment of performance anxiety and it may improve hyperhidrosis temporarily. However, long-term use may induce hyperhidrosis. OnabotulinumtoxinA (BTA) has been approved by the FDA for the treatment of severe axillary hyperhidrosis (see Fig. 39.6); it is also effective for volar disease. BTA prevents release of acetylcholine from cholinergic neurons (see Ch. 159). Injection into hyperhidrotic skin will produce near anhidrosis for 4 to 6 months. Side effects, if any, are short-lived. Muscle weakness, especially of the intrinsic muscles of the hands or feet, has been reported and resolves spontaneously over 2 to 5 weeks. Compensatory hyperhidrosis has not been observed24. Surgical treatment may be offered if other therapeutic modalities have failed. Thermolysis of the sweat glands by Nd:YAG laser24 or microwave technologies can be performed25. Surgical dissection26, curettage, or liposuction represent additional treatment options27. Excision of the sweat glands is often effective for axillary disease,

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TREATMENT OF HYPERHIDROSIS

Therapy

Frequency & recommended dose

Side effects

Duration

Comments

First-line

Topicals Aluminum chloride hexahydrate – 6.25 to 20% Aluminum chloride – 12% to 20% Aluminum zirconium salts

Use nightly for 3–5 nights, then every few days as needed

Burning Irritant contact dermatitis

Days

Blocks sweat ducts Aluminum zirconium salts may be effective in axillae, but not volar surfaces

Second-line

Acetylcholine release inhibitors, i.e. botulinum toxins

Every 4–6 months

Discomfort during injection Weakness of underlying muscles

Months

Prevents release of acetylcholine

Iontophoresis

2–3 times a week

Discomfort during procedure

Days

Blocks sweat ducts

Oral therapy*

As needed

  Oxybutynin

1.25–5 mg BID

  Glycopyrrolate

1–2 mg BID

  Clonidine

Third-line

Hours Dry mouth and urinary retention most common; also confusion and decreased mental status

Anticholinergic

0.1–0.3 mg BID

Hypotension, rebound hypertension

α2-Adrenergic agonist

  Propranolol

10–40 mg BID

Hypotension, bradycardia, hyperhidrosis with long-term use

β-Adrenergic blocker

  Clonazepam

0.25–0.5 mg BID

Sedation

Anxiolytic

Thermal ablation   Nd:YAG laser   Microwave

Multiple

Expensive

Years

Liposuction

Once to more than once**

Expensive

Semipermanent to permanent

Local excision

Once

Scarring

Permanent

Sympathectomy

Once

Compensatory hyperhidrosis Horner syndrome

Usually permanent

Anticholinergic

Last resort

*Combined with topical therapy **May need to be performed more than once to treat glands that have regenerated or were missed Table 39.7 Treatment of hyperhidrosis. Examples of commercial products are Xerac® AC, Drysol®, and Driclor® (6.45%, 20%, and 20% aluminum chloride [AlCl] hexahydrate, respectively) and Certain-Dri® (12% AlCl). BID, twice daily.  

but resection of the entire axillary skin causes significant scarring. However, compensatory hyperhidrosis is not seen with this form of local surgery. Sympathectomy is the last resort for patients with volar hyperhidrosis. Advances in endoscopic surgery have decreased the morbidity associated with this procedure. Sympathectomy at the T2–T3 level for palmar disease and the lumbar area for plantar disease is effective. Risks of the procedure include Horner syndrome, hypotension and pneumothorax. Compensatory hyperhidrosis of the trunk or gustatory facial sweating may occur24 and the hyperhidrosis may gradually recur.

HYPOHIDROSIS AND ANHIDROSIS Key features ■ An inability to sweat can be life-threatening due to the development of heat-related illnesses ■ Causes of hypo- and anhidrosis include central or neuropathic disruption of neural impulses, sweat gland abnormalities, and medications

640

Three major categories of disorders are recognized causes of anhidrosis: (1) central and neuropathic diseases or medications that disrupt neural impulses from the anterior hypothalamus to the eccrine gland; (2) peripheral (non-neural) alterations in the gland itself; and (3) idiopathic.

CAUSES OF CENTRAL AND NEUROPATHIC HYPOHIDROSIS AND ANHIDROSIS Tumors, infarctions, and other lesions of the hypothalamus, pons or medulla • Spinal cord tumors and injuries • Horner syndrome • Degenerative syndromes - Pure autonomic failure - Multiple system atrophy (Shy–Drager syndrome)* - Ross syndrome (see text) • Autoimmune autonomic neuropathy • Congenital insensitivity to pain with anhidrosis • Peripheral neuropathy due to: - Diabetes - Alcoholism - Leprosy - Amyloidosis (immunoglobulin light chain and transthyretin types) • Drugs (see Table 39.9) •

*Progressive autonomic dysfunction, parkinsonism and ataxia. Table 39.8 Causes of central and neuropathic hypohidrosis and anhidrosis.  

Central and Neuropathic Hypohidrosis Disturbance or interruption of innervation at any level, from the sweating centers in the brain down through the descending neural tracts to the sweat glands, can result in decreased or absent sweating. Causes are listed in Table 39.8. Pontine or medullary lesions lead to unilateral

Peripheral Anhidrosis Congenital and acquired alterations or disturbances of the sweat glands result in an absence or significant reduction in sweating (Table 39.10). A near absence of sweat glands is found in male patients with X-linked hypohidrotic ectodermal dysplasia, while female carriers show reduced sweating28. In patients with ichthyoses such as lamellar ichthyosis, obstruction of sweat ducts can lead to hypohidrosis. The skin of elderly individuals may show some atrophy of the sweat glands, but overall they are preserved and continue to function with advancing age. Toxic and thermal insults to the skin and a variety of

inflammatory and neoplastic disorders can destroy or produce atrophy of the sweat glands with resultant anhidrosis (see Table 39.10).

Diagnosis of Anhidrosis Heat intolerance may be due to a number of underlying disorders. New symptoms such as drowsiness, fatigue or inability to concentrate in hot environments in association with a decrease in the patient’s “normal sweating” point to acquired hypo- or anhidrosis. As with hyperhidrosis, a careful history will yield clues to the diagnosis. Special attention must be given to new medications, recent medical events (e.g. a cerebrovascular accident), the presence of diabetes or other chronic conditions, and family history (see Tables 39.8–39.10). Examination of the patient’s skin may not reveal the presence or extent of anhidrosis. A hot environment or exercise may be required, but excessive overheating must be avoided. Colorimetric or gravimetric testing (as for hyperhidrosis) will demonstrate diminished or absent sweating. Local intradermal injection of cholinergic drugs to stimulate sweating in small areas can also be utilized, but the risk of side effects generally precludes their injection into large areas. Testing for axon reflex sweating with intradermal nicotine sulfate or picrate in appropriate doses (e.g. 0.001 mg) may be performed in patients in whom peripheral neuropathies are suspected. Finally, a biopsy specimen from an affected area of skin should be obtained in virtually all patients with anhidrosis to identify sweat gland abnormalities.

CHAPTER

39 Diseases of the Eccrine and Apocrine Sweat Glands

facial anhidrosis on the ipsilateral side of the face and neck. Fiber tracts carrying sudomotor neurons to lower levels in the spinal cord are both crossed and uncrossed and the resultant anhidrosis of the skin may be ipsi- or contralateral. Both peripheral neuropathies and degenerative neurologic disorders can cause anhidrosis. Chronic orthostatic (postural) hypotension may be associated with decreased sympathetic innervation of the sweat glands, and syncopal episodes in these patients are not accompanied by sweating (in contrast to the sweating, pallor and nausea seen in common vasodepressor fainting). Ross syndrome, which consists of Adie syndrome (myotonic pupils and absent deep tendon reflexes) plus segmental anhidrosis that is typically associated with compensatory hyperhidrosis, also falls into this group. Congenital insensitivity to pain with anhidrosis (hereditary sensory and autonomic neuropathy type IV) is a rare autosomal recessive disorder which presents with recurrent fevers due to anhidrosis, selfmutilation due to insensitivity to pain, and intellectual disability. Skin biopsy specimens reveal a lack of innervation of eccrine sweat glands. Disruption of the superior cervical ganglion results in Horner syndrome, and chemical blockade of selected sympathetic ganglia will result in regional anhidrosis. Any drug that interrupts synaptic transmission in autonomic ganglia will suppress sweating (Table 39.9).

Treatment of Anhidrosis Treatment options for anhidrosis are limited. Offending medications should be discontinued. Keeping the patient in a cool environment is essential. For disorders due to clogged sweat ducts, gentle exfoliation may be helpful. Disorders of cornification (e.g. lamellar ichthyosis) associated with overheating should be treated aggressively. Use of water-containing spray bottles can prove useful.

DRUGS THAT CAUSE HYPOHIDROSIS AND ANHIDROSIS PERIPHERAL CAUSES OF HYPOHIDROSIS AND ANHIDROSIS DUE TO SWEAT GLAND ABNORMALITIES

Blockade of neurotransmission Nicotinic acetylcholine receptor antagonists (ganglion-blocking agents) - Hexamethonium - Tetraethylammonium - Mecamylamine - Trimethaphan • Muscarinic acetylcholine receptor antagonists * - Atropine - Oxybutynin - Glycopyrrolate - Scopolamine • Calcium channel blockers • α-Adrenergic blockers - Phenoxybenzamine (hypohidrosis occasionally observed) - Phentolamine† • α2-Adrenergic agonists‡ - Clonidine •

Dysfunction or destruction of the eccrine gland§ • Aldehydes (topical) • Aluminum salts (topical) • 5-Fluorouracil • Quinacrine

• Topiramate¶ • Zirconium salts (topical) • Zonisamide¶

*Antipsychotic drugs (e.g. phenothiazines), tricyclic antidepressants, and some

antihistamines can also have anticholinergic effects, especially when administered in combination and at high doses. †Thought to suppress eccrine sweating by inhibiting ganglionic transmission. ‡Decrease sympathetic outflow from the CNS. §Eccrine gland necrosis is also a feature of coma bullae, which are classically associated with barbiturate overdose but can also be observed in comas induced by other drugs (see Ch. 33); syringosquamous metaplasia may result from the toxic effects of chemotherapeutic agents (e.g. cytarabine, doxorubicin) on the eccrine glands. ¶Decreased sweating has been attributed to inhibition of carbonic anhydrase isoenzymes in the eccrine glands.

Table 39.9 Drugs that cause hypohidrosis and anhidrosis. Refers to systemic administration unless otherwise indicated.  

Genetic disorders Ectodermal dysplasias - Hypohidrotic ectodermal dysplasia - Hypohidrotic ectodermal dysplasia with immune deficiency - Rapp–Hodgkin syndrome - Naegeli–Franceschetti–Jadassohn syndrome • Incontinentia pigmenti • Bazex–Dupré–Christol syndrome • Fabry disease * •

Destruction Tumors (e.g. lymphoma) Burns • Radiation therapy • Systemic sclerosis (scleroderma) and morphea • Sjögren syndrome† • Graft-versus-host disease • Acrodermatitis chronica atrophicans • •

Obstruction Miliaria Ichthyoses (e.g. lamellar ichthyosis) • Psoriasis • Eczematous dermatoses • Bullous diseases (e.g. epidermolysis bullosa [inherited or acquired]) • Porokeratosis • •

*† Hyperhidrosis (related to autonomic dysfunction) can also occur. Hypohidrosis can also result from peripheral neuropathy.

Table 39.10 Peripheral causes of hypohidrosis and anhidrosis due to sweat gland abnormalities.  

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ABNORMALITIES AND ALTERATIONS OF ECCRINE AND APOCRINE SWEAT COMPOSITION Key features ■ Some disorders (e.g. cystic fibrosis) lead to abnormal chemical composition of sweat ■ Eccrine bromhidrosis is most commonly caused by maceration of the stratum corneum and bacterial degradation of keratin ■ Apocrine bromhidrosis is related to bacterial degradation of apocrine sweat ■ Eccrine chromhidrosis is caused by exogenous chemicals that color the sweat ■ Apocrine chromhidrosis is due to intrinsic causes

Abnormalities of eccrine sweat composition, as evidenced by altered electrolyte content or the presence of other anomalous substances, are recognized as disorders of eccrine function. Some of these glandular disturbances are not accompanied by clinically distinctive signs or symptoms, whereas others result in well-defined clinical entities. Notable among this group of disorders are those in which there is altered electrolyte concentration in sweat (Table 39.11). Cystic fibrosis, an autosomal recessive disorder caused by mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene, is an important example in which all of the exocrine glands in the body are affected, leading to dysfunction of multiple organs, including the lungs, exocrine pancreas, intestines, and liver. Cystic fibrosis patients demonstrate decreased electrolyte reabsorption by the eccrine duct, which results in increased loss of sodium, chloride, and (to a lesser extent) potassium in sweat. Increased Cl− concentration in sweat (>60 mEq/L on two separate occasions) remains the most widely used diagnostic test for this disease (the sweat chloride test). Cystic fibrosis patients still produce sweat in response to heat and most pharmacologic stimuli, but the increased loss of electrolytes poses a systemic risk for them in hot environments. An absent or markedly diminished response of the eccrine glands and other exocrine glands to β-adrenergic agonists is another marker for this disorder, since the CFTR protein is a Cl− channel activated via β-adrenergic stimulation.

Excretion of calcium in eccrine sweat has been demonstrated in patients with widespread idiopathic calcinosis cutis. In uremia, high levels of urea can produce a “uremic frost” on the skin of these seriously ill patients29. However, because dialysis is readily available, this is seen more rarely nowadays. Decreased size of the sweat glands, the significance of which is unknown, has also been described in patients with uremia30. Many drugs, including opiates, amphetamines, anticonvulsants, antimicrobials (e.g. azole antifungals, griseofulvin), and chemotherapeutic agents, as well as metals such as copper and mercury have been shown to be secreted in sweat31,32. In healthy individuals, both eccrine sweat and apocrine sweat are odorless when they are secreted. Eccrine bromhidrosis can develop secondary to maceration of the stratum corneum with bacterial degradation of keratin; the odor emanates primarily from the feet and intertriginous zones, especially the inguinal region. In apocrine bromhidrosis, the odor reflects bacterial degradation of apocrine sweat into ammonia and short-chain fatty acids. The types of bromhidrosis are listed in Table 39.12. Malodorous sweat can also be caused by abnormal secretion of amino acids and their analogues or breakdown products. This occurs in several heritable metabolic disorders33 (see Table 39.12). In addition, some foods such as garlic and asparagus can cause eccrine bromhidrosis. Colored eccrine sweating (eccrine chromhidrosis) results from contamination of colorless eccrine sweat by a chromogen such as a dye (e.g. from clothing), paint, pigment from a microorganism (e.g. Piedraia or Corynebacterium spp.), or another colored chemical on the surface of the skin. Miners or workers in the copper industry often exhibit blue or blue–green skin from external deposits of copper salts that color the sweat. The use of sunless-tanning products can result in brown sweat. Hematidrosis (bloody sweat) has not been confirmed scientifically. Red sweat has been described in patients receiving clofazimine and rifampin. In contrast, apocrine chromhidrosis is usually intrinsic in origin, resulting from the excretion in apocrine sweat of lipofuscin in large amounts or in a highly oxidized state. Chromhidrosis, primarily axillary in location and presumably of apocrine origin, can be seen in alkaptonuria and may be a presenting sign of the disease as the excreted pigment stains the undershirts of these patients.

DIAGNOSTIC MICROSCOPIC CHANGES IN ECCRINE SWEAT GLANDS A variety of disorders display diagnostic microscopic findings within the eccrine sweat glands, ranging from intracellular inclusions and degenerative alterations to changes in the size of the glands or their components. Table 39.13 summarizes these distinctive histopathologic

SYSTEMIC DISORDERS THAT AFFECT THE LEVELS OF ELECTROLYTES IN SWEAT

Increased levels of electrolytes in sweat* Cystic fibrosis Endocrine disorders - Adrenal insufficiency (e.g. due to Addison disease or congenital adrenal hyperplasia) - Myxedema - Nephrogenic diabetes insipidus • Familial intrahepatic cholestasis • Malnutrition • Metabolic disorders - Fucosidosis - Glycogen storage disease type I • Unacclimatized individuals exposed to heat • •

Decreased levels of electrolytes in sweat Endocrine disorders - Aldosteronism - Cushing syndrome - Thyrotoxicosis • Hypoproteinemic edema (e.g. due to cirrhosis or nephrotic syndrome) •

*Elevated sweat electrolytes (which may result in a false-positive chloride sweat test) can 642

also be observed in patients with skin conditions such as widespread atopic dermatitis, ichthyosiform erythroderma or ectodermal dysplasia.

Table 39.11 Systemic disorders that affect the levels of electrolytes in sweat.  

TYPES OF BROMHIDROSIS

Apocrine Axillary



Eccrine Keratinogenic - Plantar - Intertriginous • Metabolic - Phenylketonuria (musty or “mousy” odor) - Maple syrup urine disease (sweet odor) - Methionine adenosyltransferase deficiency (“boiled cabbage” odor) - Methionine malabsorption syndrome (oasthouse syndrome; "beer-like" odor) - Trimethylaminuria (“fishy” odor)* - Dimethylglycine dehydrogenase deficiency (“fishy” odor) - Isovaleric acidemia (“sweaty feet” odor) • Exogenous - Foods, e.g. garlic, asparagus, curry - Drugs, e.g. penicillins, bromides - Chemicals, e.g. dimethyl sulfoxide (DMSO) •

*Exacerbated by eating marine fish, eggs, kidney, or liver. Table 39.12 Types of bromhidrosis.  

INFLUENCE OF SWEAT ON SKIN DISEASES Key features ■ Wet skin is more permeable than dry skin ■ Wet skin is more likely to develop contact allergies than dry skin ■ Several cutaneous diseases are aggravated by sweat

That wet skin is more permeable than dry skin has been clearly established, and skin wetted by perspiration is more likely to be sensitized to contact allergens. Damp skin is also more susceptible to absorption of toxic chemicals. The macerative effect of sweat is an essential early step in the pathogenesis of sweat retention syndromes, such as miliaria. Sweat-saturated keratin, upon bacterial degradation, gives rise to plantar bromhidrosis and pitted keratolysis. Softening of the skin by sweat facilitates the entry and growth of microbes, leading to flexural candidiasis, bacterial folliculitis, bullous impetigo, superficial dermatophyte infections, tinea versicolor, verrucae, and molluscum contagiosum. Grover disease, Darier disease, and Hailey–Hailey disease are clearly aggravated by sweating. Some systemic drugs, such as antifungal agents, are excreted in eccrine sweat and diffuse from the sweat ducts to the surrounding stratum corneum, exerting inhibitory effects on microorganisms.

ADDITIONAL DISORDERS OF THE ECCRINE SWEAT GLAND Miliaria

DIAGNOSTIC MICROSCOPIC CHANGES IN ECCRINE GLANDS

CHAPTER

39 Diseases of the Eccrine and Apocrine Sweat Glands

features, which may be overlooked in the diagnostic evaluation of patients. Most of the findings listed can be visualized by light microscopy. By electron microscopy, viral particles from Ebola virus and severe acute respiratory syndrome (SARS) have been found in eccrine sweat ducts34.

Key features

Disorder

Microscopic changes

Hypothyroidism

PAS-positive, diastaseresistant granules in secretory cells

Lymphoma, multiple myeloma, heat stroke

Vacuolar degeneration of secretory cells or ducts

Neuronal ceroid lipofuscinoses

Cytoplasmic inclusions in secretory cells

Mucopolysaccharidoses (e.g. Hurler, Hunter, Sanfilippo) and mucolipidoses Acid maltase deficiency Adrenoleukodystrophy

Membrane-bound vacuoles in secretory cells

Sphingolipidoses (e.g. Fabry, Niemann–Pick, Sandhoff)

Lipid inclusions in secretory cells

Lafora disease

PAS-positive granules in outer layer of duct cells (inset)

Argyria

Granules in eccrine basement membrane (darkfield)

Trisomy 13, 18 or 21

Differences in duct : secretory coil length

Ebola hemorrhagic fever Severe acute respiratory syndrome (SARS)

Viral particles in lumen of sweat gland tubule

Coma bullae

Necrosis of secretory cells and duct cells

Uremia

Reduced size of sweat glands

Table 39.13 Diagnostic microscopic changes in eccrine glands. Inset: Lafora disease. Inset, courtesy, Harry Hurley, MD.  

■ Sweat retention can be caused by obstruction of the eccrine duct at various levels ■ Miliaria crystallina or sudamina (superficial ductal occlusion) – clear vesicles ■ Miliaria rubra or prickly heat (intermediate ductal occlusion) – erythematous papules or pustules ■ Miliaria profunda or mammillaria (deeper ductal occlusion) – white papules ■ Common in neonates (whose eccrine sweat ducts are not fully developed) and adults living in hot, humid climates ■ Resolves with relocation to a cool environment

Miliaria encompasses a family of eccrine disorders all of which feature obstruction of the eccrine sweat duct. Three types are recognized, with each reflecting obstruction of sweat ducts at a different level, from the stratum corneum to the dermal–epidermal junction (Table 39.14). Blockage results in retention of sweat within the duct, causing a sweat retention vesicle to form.

Epidemiology and pathogenesis Miliaria is most common in children, particularly neonates whose eccrine ducts are not fully developed. Congenital miliaria crystallina has even been described. Miliaria is also common in adults who live or work in very hot, humid environments. There is no racial or gender predisposition and it can occur in the elderly. Miliaria has not been associated with any specific underlying systemic disease. Excessive sweating, particularly under occlusive clothing, can lead to maceration of the stratum corneum which is sufficient to cause blockage of the eccrine duct28. Keratinous plugs form, causing obstruction.

THREE TYPES OF MILIARIA

Type

Location of obstruction

Cutaneous lesions

Patient population(s)

Most common locations

Crystallina

Stratum corneum

Non-pruritic, clear, fragile, 1 mm vesicles

Neonates C

Catalase, BPI, α-enolase, LF, CG, HMG1/2 > MPO, PR3

Colonoscopy

P>C

Actin, HMG1/2

LFTs; ANA; anti-smooth muscle Ab; antimitochondrial Ab

P>C

MPO, PR3, BPI, CG, LF, lysozyme, HMGI/2

ANA panel; RF; anti-cardiolipin Ab

Propylthiouracil (20%), minocycline > levamisole, sulfasalazine

P>C

MPO > PR3, elastase

Skin biopsy; ANA panel; LFTs; discontinue drug

Hydralazine, penicillamine > allopurinol‡

P

MPO, elastase

TNF inhibitors

P, C

MPO, PR3

High-dose intravenous immunoglobulin

C



Mixed cryoglobulinemia, Behçet disease, paraneoplastic

P>C

Variable

Henoch–Schönlein purpura, Buerger disease

P

Variable

P

MPO

UA; BUN/creatinine; ASO; renal biopsy

Respiratory tract infections (bacterial/mycobacterial/ fungal), enteritis, periodontitis, HIV, parvovirus B19, malaria, leprosy

P, C

MPO, others

Cultures; serologies; echocardiogram

Onchocerciasis

P

Defensin

Hepatitis C virus infection

P, C

CG, BPI, MPO

Subacute bacterial endocarditis, chromomycosis, invasive amebiasis

C

PR3

Cystic fibrosis (80%)

C>P

BPI

Sweat test

Hypergammaglobulinemia

P, C



Serum protein electrophoresis

Inflammatory bowel disease Ulcerative colitis (50–70%) > Crohn disease (20–40%) Autoimmune liver disease Autoimmune hepatitis (type 1; 80%), primary sclerosing cholangitis (70%) > primary biliary cirrhosis (30%) Autoimmune connective tissue disease Systemic lupus erythematosus, rheumatoid arthritis, systemic sclerosis (20–30%) > Sjögren syndrome, dermatomyositis, reactive arthritis, relapsing polychondritis, antiphospholipid syndrome Drug-induced vasculitis/lupus/hepatitis

Other cutaneous and/or systemic vasculitides§ Skin biopsy; cryoglobulins; hepatitis B, C panels; exclude malignancy

Other glomerulonephritides Anti-GBM Ab-associated (30%) > immune complex (15%) > poststreptococcal Infections

Serologies

*† C-ANCA are often atypical; in addition, immunofluorescence testing in some laboratories may not distinguish C-ANCA (atypical) from atypical ANCA.

P-ANCA often have antigen specificity other than MPO, e.g. LF, elastase, CG, lysozyme, BPI, HMG1/2, α-enolase, catalase, actin, defensin; C-ANCA (atypical) have antigen specificity other than proteinase 3, e.g. BPI, lysozyme or multiple antigens. ‡Other drugs associated with P-ANCA in scattered case reports include cimetidine, cefotaxime, phenytoin, isotretinoin, clozapine and thioridazine. §Although primarily associated with C-ANCA, 5–50% of patients with granulomatosis with polyangiitis have P-ANCA; likewise, although primarily associated with P-ANCA, 5–30% of patients with eosinophilic granulomatosis with polyangiitis and ~25–30% of those with microscopic polyangiitis have C-ANCA; ANCA have also been reported in leukocytoclastic vasculitis of unknown etiology and unclassified vasculitis.

Table 40.6 Other disorders associated with antineutrophil cytoplasmic antibodies (ANCA). Ab, antibodies; ANA, antinuclear antibodies; ASO, antistreptolysin O; BPI, bactericidal/permeability-increasing protein; C, cytoplasmic [C-ANCA or C-ANCA (atypical)]; CG, cathepsin G; GBM, glomerular basement membrane; HMG1/2, high mobility group non-histone chromosomal proteins; LF, lactoferrin; LFTs, liver function tests; MPO, myeloperoxidase; P, perinuclear (P-ANCA); RF, rheumatoid factor; UA, urinalysis. Courtesy, Julie V Schaffer, MD.  

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43.

44.

45.

single-centre cohort. Ann Rheum Dis 2014;73:  1695–9. Hamaguchi Y, Kuwana M, Hoshino K, et al. Clinical correlations with dermatomyositis-specific autoantibodies in adult Japanese patients with dermatomyositis: a multicenter cross-sectional study. Arch Dermatol 2011;147:391–8. Pinal-Fernandez I, Casciola-Rosen LA, Christopher-Stine L, et al. The prevalence of individual histopathologic features varies according to autoantibody status in muscle biopsies from patients with dermatomyositis. J Rheumatol 2015;42:1448–54. Fujimoto M, Watanabe R, Ishitsuka Y, Okiyama N. Recent advances in dermatomyositis-specific autoantibodies. Curr Opin Rheumatol 2016;28:636–44. Euwer RL, Sontheimer RD. Amyopathic dermatomyositis (dermatomyositis sine myositis). Presentation of six new cases and review of the literature. J Am Acad Dermatol 1991;24:959–66. Sontheimer RD. Would a new name hasten the acceptance of amyopathic dermatomyositis (dermatomyositis sine myositis) as a distinctive subset within the idiopathic inflammatory dermatomyopathies spectrum of clinical illness? J Am Acad Dermatol 2002;46:626–36. Targoff IN, Mamyrova G, Trieu EP, et al. A novel autoantibody to a 155-kd protein is associated with dermatomyositis. Arthritis Rheum 2006;54:3682–9. Kaji K, Fujimoto M, Hasegawa M, et al. Identification of a novel autoantibody reactive with 155 and 140 kDa nuclear proteins in patients with dermatomyositis: an association with malignancy. Rheumatology (Oxford) 2007;46:25–8. Valenzuela A, Chung L, Casciola-Rosen L, Fiorentino D. Identification of clinical features and autoantibodies associated with calcinosis in dermatomyositis. JAMA Dermatol 2014;150:724–9. Bernet LL, Lewis MA, Rieger KE, et al. Ovoid palatal patch in dermatomyositis: a novel finding associated with anti-TIF1gamma (p155) antibodies. JAMA Dermatol 2016;152:1049–51. Fiorentino DF, Kuo K, Chung L, et al. Distinctive cutaneous and systemic features associated with antitranscriptional intermediary factor-1gamma antibodies in adults with dermatomyositis. J Am Acad Dermatol 2015;72:449–55. Sato S, Hirakata M, Kuwana M, et al. Autoantibodies to a 140-kd polypeptide, CADM-140, in Japanese patients with clinically amyopathic dermatomyositis. Arthritis Rheum 2005;52:1571–6. Sato S, Hoshino K, Satoh T, et al. RNA helicase encoded by melanoma differentiation-associated gene 5 is a major autoantigen in patients with clinically amyopathic dermatomyositis: Association with rapidly progressive interstitial lung disease. Arthritis Rheum 2009;60:2193–200. Nakashima R, Imura Y, Kobayashi S, et al. The RIG-I-like receptor IFIH1/MDA5 is a dermatomyositis-specific autoantigen identified by the anti-CADM-140 antibody. Rheumatology (Oxford) 2010;49:433–40. Fiorentino D, Chung L, Zwerner J, et al. The mucocutaneous and systemic phenotype of dermatomyositis patients with antibodies to MDA5 (CADM-140): a retrospective study. J Am Acad Dermatol 2011;65:25–34.

46. Matsushita T, Mizumaki K, Kano M, et al. Anti-MDA5 antibody level is a novel tool for monitoring disease activity in rapidly progressive interstitial lung disease with dermatomyositis. Br J Dermatol 2017;176:395–402. 47. Hoshino K, Muro Y, Sugiura K, et al. Anti-MDA5 and anti-TIF1-gamma antibodies have clinical significance for patients with dermatomyositis. Rheumatology (Oxford) 2010;49:1726–33. 48. Sato S, Murakami A, Kuwajima A, et al. Clinical utility of an enzyme-linked immunosorbent assay for detecting anti-melanoma differentiation-associated gene 5 autoantibodies. PLoS ONE 2016;11:e0154285. 49. Fujimoto M, Murakami A, Kurei S, et al. Enzyme-linked immunosorbent assays for detection of antitranscriptional intermediary factor-1 gamma and anti-Mi-2 autoantibodies in dermatomyositis. J Dermatol Sci 2016;84:272–81. 50. Imbert-Masseau A, Hamidou M, Agard C, et al. Antisynthetase syndrome. Joint Bone Spine 2003;70:161–8. 51. Ang CC, Anyanwu CO, Robinson E, et al. Clinical signs associated with an increased risk of interstitial lung disease: a retrospective study of 101 patients with dermatomyositis. Br J Dermatol 2017;176:231–3. 51a.  Albayda J, Pinal-Fernandez I, Huang W, et al. Dermatomyositis patients with anti-nuclear matrix protein-2 autoantibodies have more edema, more severe muscle disease, and increased malignancy risk. Arthritis Care Res (Hoboken) 2017; doi: 10.1002/ acr.23188. 51b.  Rogers A, Chung L, Li S, et al. The cutaneous and systemic findings associated with nuclear matrix protein-2 antibodies in adult dermatomyositis patients. Arthritis Care Res (Hoboken) 2017; doi: 10.1002/ acr.23210. 52. Maddison PJ. Autoantibodies and clinical subsets: relevance to scleroderma. Wien Klin Wochenschr 2000;112:684–6. 53. Gabrielli A, Avvedimento EV, Krieg T. Scleroderma. N Engl J Med 2009;360:1989–2003. 54. Nihtyanova SI, Parker JC, Black CM, et al. A longitudinal study of anti-RNA polymerase III antibody levels in systemic sclerosis. Rheumatology (Oxford) 2009;48:1218–21. 55. van den Hoogen F, Khanna D, Fransen J, et al. 2013 classification criteria for systemic sclerosis: an American College of Rheumatology/European League against Rheumatism collaborative initiative. Arthritis Rheum 2013;65:2737–47. 56. Pope JE, Johnson SR. New classification criteria for systemic sclerosis (scleroderma). Rheum Dis Clin North Am 2015;41:383–98. 57. Shah AA, Rosen A, Hummers L, et al. Close temporal relationship between onset of cancer and scleroderma in patients with RNA polymerase I/III antibodies. Arthritis Rheum 2010;62:2787–95. 58. Joseph CG, Darrah E, Shah AA, et al. Association of the autoimmune disease scleroderma with an immunologic response to cancer. Science 2014;343:152–7. 59. Shah AA, Casciola-Rosen L. Cancer and scleroderma: a paraneoplastic disease with implications for malignancy screening. Curr Opin Rheumatol 2015;27:563–70. 60. Ward MM. Laboratory testing for systemic rheumatic diseases. Postgrad Med 1998;103:93–100.

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40 Autoantibodies Encountered in Patients with Autoimmune Connective Tissue Diseases

15. Sontheimer RD. Greenwald’s law of lupus: the Sontheimer amendment. J Rheumatol 1993;20:1258–9. 16. Black AA, McCauliffe DP, Sontheimer RD. Prevalence of acne rosacea in a rheumatic skin disease subspecialty clinic. Lupus 1992;1:229–37. 17. Honarmand AR, Balighi K, Lajevardi V, et al. Effect of narrow-band ultraviolet B phototherapy on production of antinuclear antibodies. J Dermatol 2012;39:733–4. 18. Yaniv G, Twig G, Shor DB, et al. A volcanic explosion of autoantibodies in systemic lupus erythematosus: a diversity of 180 different antibodies found in SLE patients. Autoimmun Rev 2015;14:75–9. 19. Egner W. The use of laboratory tests in the diagnosis of SLE. J Clin Pathol 2000;53:424–32. 20. Petri M, Orbai AM, Alarcon GS, et al. Derivation and validation of the Systemic Lupus International Collaborating Clinics classification criteria for systemic lupus erythematosus. Arthritis Rheum 2012;64:2677–86. 21. Agmon-Levin N, Damoiseaux J, Kallenberg C, et al. International recommendations for the assessment of autoantibodies to cellular antigens referred to as anti-nuclear antibodies. Ann Rheum Dis 2014;73:17–23. 22. Pisetsky DS. Anti-DNA antibodies–quintessential biomarkers of SLE. Nat Rev Rheumatol 2016;12:102–10. 23. Lee LA, Roberts CM, Frank MB, et al. The autoantibody response to Ro/SSA in cutaneous lupus erythematosus. Arch Dermatol 1994;130:1262–8. 24. Rubin R. Drug-induced lupus. In: Wallace DJ, Hahn BH, editors. Dubois’ Lupus Erythematosus. Philadelphia: Lippincott Williams & Wilkins; 2007. p. 870–900. 25. Laurinaviciene R, Sandholdt LH, Bygum A. Druginduced cutaneous lupus erythematosus: 88 new cases. Eur J Dermatol 2017;27:28–33. 25a.  Bardazzi F, Odorici G, Virdi A, et al. Autoantibodies in psoriatic patients treated with anti-TNF-α therapy. J Dtsch Dermatol Ges 2014;12:401–6. 26. De Rycke L, Baeten D, Kruithof E, et al. Infliximab, but not etanercept, induces IgM anti-double-stranded DNA autoantibodies as main antinuclear reactivity: biologic and clinical implications in autoimmune arthritis. Arthritis Rheum 2005;52:2192–201. 27. De Bandt M, Sibilia J, Le Loet X, et al. Systemic lupus erythematosus induced by anti-tumour necrosis factor alpha therapy: a French national survey. Arthritis Res Ther 2005;7:R545–51. 28. Wetter DA, Davis MD. Lupus-like syndrome attributable to anti-tumor necrosis factor alpha therapy in 14 patients during an 8-year period at Mayo Clinic. Mayo Clin Proc 2009;84:979–84. 29. Moulis G, Sommet A, Lapeyre-Mestre M, Montastruc JL. Is the risk of tumour necrosis factor inhibitor-induced lupus or lupus-like syndrome the same with monoclonal antibodies and soluble receptor? A case/ non-case study in a nationwide pharmacovigilance database. Rheumatology (Oxford) 2014;53:1864–71. 30. Ishikawa Y, Fujii T, Ishikawa SK, et al. Immunogenicity and lupus-like autoantibody production can be linked to each other along with type i interferon production in patients with rheumatoid arthritis treated with infliximab: a retrospective study of a single center cohort. PLoS ONE 2016;11:e0162896. 31. Takase K, Horton SC, Ganesha A, et al. What is the utility of routine ANA testing in predicting development of biological DMARD-induced lupus and vasculitis in patients with rheumatoid arthritis? Data from a

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41 

Lupus Erythematosus Lela A. Lee and Victoria P. Werth

Synonyms/variants:  ■ Discoid lupus erythematosus: a subset of

chronic cutaneous lupus erythematosus ■ Lupus profundus: a variant of lupus panniculitis ■ Lupus erythematosus tumidus: tumid lupus

Key features

EPIDEMIOLOGY

Lupus erythematosus is a multisystem disorder that often affects the skin. Cutaneous lesions can be a source of disability and, on many occasions, an indicator of internal disease.

Systemic lupus erythematosus (SLE) is a common disease with significant morbidity and mortality. The strongest factor affecting risk for lupus is gender: women with SLE outnumber men by at least 6 : 19. Since SLE occurs most commonly in women during their childbearing years, it is likely that hormonal factors influence susceptibility. Consistent with the importance of sex steroids in the expression of disease, lupus is rare in prepubertal children. With regard to patients who have only cutaneous lesions, there appears to be a somewhat lower femaleto-male ratio (perhaps 3 : 1), but there is still a female predominance. Ethnicity is also a major risk factor, and its effect in some populations is almost as strong as that of gender. The prevalence of SLE is fourfold higher in African-American women as compared to Caucasian American women (4 in 1000 vs 1 in 1000)9. In addition, African-Americans tend to develop disease at an earlier age and have a higher mortality rate. A long-term study of a multi-ethnic cohort of 587 SLE patients from Texas, Alabama and Puerto Rico found that African-Americans and Hispanics from Texas had more severe disease than Caucasian Americans or Hispanics from Puerto Rico10. It is likely that Caucasian populations in Europe have a similar prevalence of lupus as do Caucasians living in the US. It also appears that the prevalence of lupus among both Asians and Latin Americans is similar to that of Caucasian Americans. Highlighting the importance of skin disease in LE, population-based studies indicate that there are approximately as many patients who have cutaneous LE without concurrent SLE as there are patients who have SLE11,12.

HISTORY

PATHOGENESIS

The term “lupus erythemateaux” was first used by Cazenave in the mid-1800s1. Cazenave and others helped to articulate the difference between lupus erythematosus (LE) and lupus vulgaris, a clinical variant of cutaneous tuberculosis. Due in part to observations of Hutchinson, Osler and Jadassohn, it was recognized that cutaneous lesions of LE may be associated with significant internal abnormalities, including arthritis, nephritis, serositis, cytopenias and neurologic disease. In 1964 and during the following years, Dubois developed the concept of lupus as a spectrum of disease, ranging from isolated cutaneous lesions to life-threatening, multi-organ disease. Gilliam also developed the concept of a spectrum of cutaneous disease, and, in 1979, along with Sontheimer and Thomas, clearly separated and named the entity now known as subacute cutaneous lupus erythematosus (SCLE)2. The description was virtually identical to that of “ANA-negative” lupus (see Ch. 40), reported by Maddison, Provost and Reichlin in 19813. Important diagnostic advances included discovery of the LE cell phenomenon by Hargraves, Richmond and Morton in 1948; identification of ANA by Friou in 1957; description of the lupus band test by Burnham, Neblett and Fine in 1963; and the association of specific clinical manifestations of lupus with specific autoantibodies by a variety of investigators4–6. With regard to skin disease, the associations of anti-Ro (also known as anti-SSA) autoantibodies with neonatal lupus by Weston et al.7 in 1981 and with subacute cutaneous lupus (SCLE) by Sontheimer et al.8 in 1982 are noteworthy milestones.

The pathogenesis of cutaneous LE is complex, and it involves an interaction between genetic and environmental factors. The latter include ultraviolet radiation (UVR), medications, cigarette smoking, and possibly viruses. This interplay triggers a complex inflammatory cascade of cytokine, chemokine and inflammatory cell responses that include cells residing within as well as recruited to the skin. Overall, the lichenoid tissue reaction, defined as epidermal basal cell damage and a bandlike lymphocytic infiltrate in the upper dermis, characterizes most subsets of cutaneous LE. It involves activation of keratinocytes, endothelial cells, and skin dendritic cells plus the production of type I interferons (IFNs), followed by the recruitment and activation of CD4+ and CD8+ cytotoxic T cells. The end result is cytotoxic keratinocyte damage. Genes that can affect overall immunoreactivity include those whose protein products are involved in B- and T-cell function, innate immunity, immune complex clearance, apoptosis, ubiquitination, DNA methylation or cellular adhesion13. Examples from all these gene classes, in addition to genes with unknown function, have been implicated in some way in human or animal models of SLE (Table 41.1; see Ch. 4). Both genetic background based upon ancestry and mutations in specific genes contribute to the clinical heterogeneity in cutaneous LE. For example, the incidences of photosensitivity and discoid LE (DLE) differ in those of northern versus southern European ancestry14, and SCLE is associated with the HLA-B8-DR3 extended haplotype (including

■ There are several variants of cutaneous lupus, defined in part by the location and depth of the inflammatory infiltrate ■ Acute cutaneous lupus involves primarily the epidermis and upper dermis and is usually associated with active systemic disease ■ Subacute cutaneous lupus involves primarily the epidermis and upper dermis and most patients have photosensitivity and anti-SSA/Ro autoantibodies during the course of their disease; the majority do not have significant systemic involvement (renal, CNS or cardiopulmonary) ■ Discoid lesions of lupus involve the epidermis, upper and lower dermis, and adnexal structures, and they can scar; the majority of patients do not have clinically significant systemic disease ■ Lupus erythematosus tumidus involves the dermis but there is no prominent epidermal involvement and lesions do not scar ■ Lupus panniculitis involves the subcutaneous tissue and may result in disfiguring depressed scars due to lipoatrophy

INTRODUCTION

662

Antimalarial therapy in the form of quinine was used for cutaneous lupus by Payne in 1894. By the late 1950s, synthetic antimalarials had become a mainstay of therapy. Systemic corticosteroids and other immunosuppressive agents came into use during the mid twentieth century.

Lupus erythematosus is a multisystem disorder that prominently affects the skin. The most common types of cutaneous lupus are acute cutaneous lupus (ACLE), subacute cutaneous lupus (SCLE), and discoid lupus (DLE). ACLE is typified by malar erythema and occurs primarily in patients who have systemic disease. SCLE is a photosensitive eruption that is frequently, but not universally, associated with anti-SSA/Ro autoantibodies and is drug-induced or drug-exacerbated in ~25% of cases; this form is usually not associated with significant renal, CNS or cardiovascular involvement. Patients with DLE may or may not report photosensitivity, but lesions are frequently photodistributed and have a propensity to have secondary atrophy or scarring. Most patients with DLE do not have significant systemic disease. Histologically, ACLE, SCLE, and DLE are distinguishable in part by the location and intensity of the inflammatory infiltrate and the presence or absence of adnexal involvement. More rare forms of cutaneous LE include LE tumidus, lupus panniculitis, bullous SLE, and chilblain lupus. Nonspecific skin findings, e.g. livedo reticularis, Degos disease-like lesions, purpura or urticaria due to small vessel vasculitis, are more frequently seen in patients with systemic disease.

cutaneous lupus erythematosus, systemic lupus erythematosus, SLE, acute cutaneous lupus erythematosus, ACLE, subacute cutaneous lupus erythematosus, SCLE, discoid lupus erythematosus, DLE, chronic cutaneous lupus erythematosus, tumid lupus erythematosus, lupus erythematosus tumidus, lupus panniculitis, chilblain lupus, neonatal lupus erythematosus, bullous systemic lupus erythematosus, bullous eruption of systemic lupus erythematosus, drug-induced systemic lupus erythematosus, drug-induced subacute cutaneous lupus erythematosus, antimalarials

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41 Lupus Erythematosus

ABSTRACT

non-print metadata KEYWORDS:

662.e1



GENES ASSOCIATED WITH SYSTEMIC LUPUS ERYTHEMATOSUS B- and T-cell function

HLA-DR – major histocompatibility complex, class II BLK – B lymphoid tyrosine kinase BANK1 – B-cell scaffold protein (with ankyrin repeats) 1

et al. Recent insights into the genetic basis of systemic lupus erythematosus. Genes Immun. 2009;10:373–9.

CTLA4 – cytotoxic T lymphocyte antigen 4 FCGR2B – Fc fragment of IgG, low affinity IIb, receptor (CD32) LYN v-yes-1 – Yamaguchi sarcoma viral related oncogene homolog

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41 Lupus Erythematosus

Table 41.1 Genes associated with systemic lupus erythematosus. For detailed information on the function of these protein products, see www.genecards.org. The most strongly associated genes are in bold. Adapted from Moser KL, Kelly JA, Lessard CJ,

IKZF1 – Ikaros PTPN22 – protein tyrosine phosphatase, non-receptor type 22 (lymphoid) STAT4 – signal transducer and activator of transcription 4 PDCD1 – programmed cell death 1 IRAK1 – interleukin-1 receptor-associated kinase 1 ETS1 – v-ets erythroblastosis virus E26 oncogene homolog 1 TNFSF4 – tumor necrosis factor (ligand) superfamily, member 4 IL21 – interleukin 21 Innate immunity

IRF5 – interferon regulatory factor 5 TNFAIP3 – tumor necrosis factor, alpha-induced protein 3 SPP1 – secreted phosphoprotein 1 (osteopontin) TREX1 – three prime repair exonuclease 1 (see text) TYK2 – tyrosine kinase 2 IRAK1 – see above STAT4 – see above RASGRP3 – RAS guanyl releasing protein SLC15A4 – solute carrier family 15 member 4

Immune complex clearance

FCGR3A – Fc fragment of IgG, low affinity IIIa, receptor (CD16a) FCGR3B – Fc fragment of IgG, low affinity IIIb, receptor (CD16b) CRP – C-reactive protein, pentraxin-related ITGAM – integrin, alpha M (complement component 3 receptor 3 subunit; CD11b) C4A – complement component 4A C4B – complement component 4B C2 – complement component 2 C1Q – complement component 1, q subcomponent

Apoptosis

ATG5 – autophagy related 5 homolog STAT4 – see above

Ubiquitination

UBE2L3 – ubiquitin-conjugating enzyme E2L 3 TNFAIP3 – tumor necrosis factor, alpha-induced protein 3 TNIP1 – TNFAIP3 interacting protein 1

DNA methylation

MECP2 – methyl CpG binding protein 2 (Rett syndrome)

Cellular adhesion

ITGAM – see above

Other/unknown

PXK – PX domain containing serine/threonine kinase ICA1 – islet cell autoantigen 1 SCUBE1 – signal peptide, CUB domain, EGF-like 1 NMNAT2 – nicotinamide nucleotide adenylyltransferase 2 XKR6 – XK, Kell blood group complex subunit-related family, member 6 KIAA1542

TNF2), as well as C2 and C4 deficiencies15. Genes previously associated with SLE, e.g. TYK2, IRF5 and CTLA4, also confer an increased risk for developing DLE and SCLE16, while mutations in TREX1, which encodes a DNA exonuclease, are associated with familial chilblain lupus17. In the latter patients, dysfunction of the exonuclease leads to an accumulation of IFN-stimulatory nucleic acids. Autoantibodies clearly play a role in SCLE and neonatal lupus, where anti-SSA/Ro (more specifically, anti-SSA/Ro60 and anti-SSA/Ro52) and

anti-La autoantibodies are frequently observed (see Ch. 40); in the case of neonatal lupus, these antibodies are transmitted transplacentally. Blocking the function of either SSA/Ro60 or SSA/Ro52 presumably predisposes one to these diseases. Of note, SSA/Ro60 plays an important role in cell survival following UVR, possibly via binding to misfolded non-coding RNAs and targeting them for degradation, and mice which lack SSA/Ro60 develop a lupus-like syndrome18. SSA/ Ro52 has a known regulatory role in inflammation, targeting both

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41.1)27,28. Following UV irradiation of keratinocytes, a complex array of chemokines, including chemokine (C-C motif) ligand 5 (CCL5), CCL20, CCL22, and chemokine (C-X-C motif) ligand 8 (CXCL8), is produced. Of note, there is an increase in these chemokines within lesions of cutaneous LE, likely leading to leukocyte recruitment to the skin29. These effects require adhesion molecules, with activation of endothelial cells (increased expression of ICAM-1, VCAM-1 and E-selectin) and induction of ICAM-1 on basal keratinocytes30,31. IFN is another cytokine that plays a role in the pathogenesis of cutaneous LE. Increased secretion of IFN can result from: binding of apoptotic cells to Fcγ receptors on macrophages; binding of viral pathogens, DNA, RNA or immune complexes to Toll-like receptors on plasmacytoid dendritic cells; and single nucleotide polymorphisms (SNPs) in genes that encode proteins in the IFN pathway32. Notably, an increase in proteins upregulated by IFN, including the chemokines CXCL9 and CXCL10, has been observed in the skin of patients with cutaneous LE (see Fig. 41.1)29,33. IFN-α further drives the differentiation of

interferon regulatory factor 3 (IRF3) and IRF8 for degradation19; thus, antibodies to SSA/Ro52 may be proinflammatory. Alternatively, or in addition, these autoantibodies could lead to disease via activation of proteins and cells of the immune system, following immune complex formation. Both ultraviolet B (UVB) and ultraviolet A radiation have been implicated in exacerbation of cutaneous LE, although UVB is a more efficient cause of photo-induced changes in the skin20. UVR induces apoptosis, which leads to translocation of cellular and nuclear antigens21, and there may also be a reduction in the clearance of apoptotic cells22. In addition, UVR increases keratinocyte production of SSA/Ro5223. A number of proinflammatory cytokines, including tumor necrosis factor (TNF)-α, interleukin (IL)-1, IFN-γ, HMGB1 (high-mobility group box 1), and IL-18 are induced by UVR24–26. There is also upregulation of antimicrobial peptides within the skin as well as a release of extracellular traps (ETs) by dying neutrophils (NETosis); these traps are composed of a lattice of DNA, histones, and cytoplasmic proteins (Fig.

PATHOGENESIS OF LUPUS ERYTHEMATOSUS

UV La Fas

IL-18R

CD1d

Sm

Keratinocytes

MMPs

TNF-

B cell DNA

IFN-

TLR7

DNA

TLR7 TLR9

LL37

TLR9

Adhesion molecules

Adhesion molecules

CXCL9

IL-6

Apoptotic bodies

DNA

HMGB1

IL-1

RNP

Ro

TRAIL-R1

IFN-

CXCL10

IFN-

GAGs

GBP1 Endothelial cells

iNKT

IFN-

Th17

IL-17

Th1

IFN-

Extracellular traps from dying neutrophils (NETosis)

Plasmacytoid dendritic cell

Neutrophil

Keratinocyte apoptosis

Autoantibodies

Macrophage

Cytokines

Myeloid dendritic cell

Chemokines

CTL

GrB

Fig. 41.1 Pathogenesis of lupus erythematosus. In photosensitive cutaneous LE, ultraviolet radiation triggers cytokine and chemokine production, innate immune proteins, NETosis of neutrophils, and apoptosis of cells leading to release of DNA. A lichenoid tissue reaction is the endpoint of a complex cascade that includes activation of dendritic cells, release of interferon (IFN), production of chemokines, and activation of T cells. CTL, cytotoxic T lymphocyte; CXCL, chemokine (C-X-C motif ) ligand; GAGs, glycosaminoglycans; GBP1, guanylate binding protein-1; GrB, granzyme B; HMGB1, high-mobility group box 1; IL, interleukin; iNKT cells, invariant natural killer T cells; LL-37, cathelicidin; mDC, myeloid dendritic cell; MMPs, matrix metalloproteinases; pDC, plasmacytoid dendritic cell; RNP, ribonucleoprotein; Th, T helper cell; TLR, Toll-like receptor; TNF, tumor necrosis factor, TRAIL-R1, tumor necrosis factor-related apoptosis-inducing ligand-receptor 1.  

664

T cell

Adapted from Achtman JC, Werth VP. Pathophysiology of cutaneous lupus erythematosus. Arthritis Res Ther 2015;17:182.

histopathology demonstrated an interface dermatitis or not, respectively. Within the category of specific cutaneous lesions, he subdivided these into acute cutaneous LE, subacute cutaneous LE, and chronic cutaneous LE (Fig. 41.2). This choice of terms was based upon the observation that three distinct types of cutaneous LE are commonly seen: the often transient lesions of acute cutaneous LE (ACLE) typified by malar erythema; the frequently long-lived, intensely inflammatory discoid LE (DLE) lesions which can lead to permanent disfiguring scars; and a photosensitive eruption characteristically more long-lasting than ACLE but without the potential for atrophy or scarring, for which the term subacute cutaneous LE (SCLE) was coined. Typically grouped within the chronic cutaneous LE category are the less common disorders LE tumidus, lupus panniculitis, and chilblain lupus (see Fig. 41.2), despite the observation that characteristic lesions frequently lack an interface dermatitis, especially LE tumidus. Formal studies have not been done comparing duration of disease activity for the various types of cutaneous LE, and there is a considerable range in the duration of activity within each subtype. Patients with SCLE lesions may have a chronic, relapsing course, while DLE or LE tumidus lesions may have a relatively short duration due to resolution or effective disease control. In fact, some authorities have proposed that LE tumidus should be removed from the chronic category and be given its own category, intermittent cutaneous LE42. These controversies aside, Gilliam’s classification schema has proven utility in the organization of the various types of cutaneous LE and it is the basis for the classification herein, accompanied by a focus on the morphology and histopathology of lesions (Fig. 41.3). The three major forms of cutaneous LE will be discussed first, followed by the remaining entities outlined in Fig. 41.2.

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41 Lupus Erythematosus

monocytes to plasmacytoid dendritic cells, which are potent producers of IFN-α/β, thus forming an amplification loop34. Increased numbers of plasmacytoid (CD123+) and myeloid dendritic cells have been found within cutaneous LE lesions33,35. Epidermal and dermal dendritic cells can acquire keratinocyte-derived antigens and prime CD8+ T cells to these antigens within the skin-draining lymph nodes36. Corroborating evidence for the role of IFN-α is provided by the induction of cutaneous LE in patients receiving IFN-α for other medical conditions. The increased IFN signature seen in SLE has also been detected in peripheral blood mononuclear cells from patients with DLE and SCLE, but not those with LE tumidus37. The IFN-upregulated chemokines can recruit CXCR3-positive CD4+ and CD8+ T cells to the skin, as well as immature plasmacytoid dendritic cells, contributing to the characteristic interface infiltrate of cutaneous LE29,38. In addition, via the production of IFN-α, plasmacytoid dendritic cells drive the activation and expansion of T cells. There is also evidence for the presence of granzyme B and TIA1 (poly(A)-binding protein), two cytotoxic granule-associated proteins involved in apoptosis, in the skin of all subsets of cutaneous LE, although somewhat less so in SCLE, suggesting that there are fewer CD8+ T cells in SCLE38. In patients with disseminated, scarring DLE, high numbers of circulating CCR4+ cytotoxic T cells were detected39. One study found decreased numbers of Foxp3+CD4+CD25+ T regulatory cells in the skin, but not the blood, of cutaneous LE patients, and Treg cells are known to downregulate the immune response40. A scenario that integrates current theories regarding the pathogenesis of several subsets of cutaneous LE is shown in Fig. 41.1. In the proposed model, a response to UVR triggers cytokine, chemokine, and antimicrobial peptide production by keratinocytes as well as endothelial cell activation, thereby initiating the immune response. In the context of genetic and environmental risk factors, a complex cascade ensues that includes activation of dendritic cells, release of IFN, activation of T cells, and production of chemokines; a positive feedback loop ultimately results in a lichenoid tissue reaction.

Discoid lupus erythematosus Discoid lesions represent one of the most common skin manifestations of lupus and they are most frequently found on the face, scalp and ears (Fig. 41.4), but may be present in a more widespread distribution (Fig. 41.5). It is unusual for discoid lesions to be present below the neck without lesions also being present above the neck. Occasionally, discoid lesions develop on mucosal surfaces, including the lips, nasal mucosa, conjunctivae, and genital mucosa. Some patients with discoid lesions exhibit a photodistribution, and sun exposure appears to have a role in lesional development. However, many patients have discoid lesions on sun-protected skin, and there is no clear association between sun exposure and their development.

CLINICAL FEATURES Cutaneous Lupus – Three Major Forms Classification The most commonly used classification of cutaneous lesions in LE is that of Dr. James Gilliam41. He segregated skin lesions into those that are specific and those that are not specific based upon whether the

Fig. 41.2 Classification of cutaneous lupus erythematosus (LE). Based upon the classification system originally proposed by Gilliam and Sontheimer41.  

CLASSIFICATION OF CUTANEOUS LUPUS ERYTHEMATOSUS

Specific cutaneous lesions

Nonspecific cutaneous lesions

Vasculopathic lesions Non-scarring alopecia Other (see text and Table 41.6)

Acute cutaneous LE (ACLE)

Subacute cutaneous LE (SCLE)

Chronic cutaneous LE (CCLE)

Other

Malar erythema Photodistributed Can be widespread

Annular Papulosquamous Neonatal

Discoid lupus (DLE) Localized Widespread Hypertrophic LE tumidus

Bullous lesions of SLE Rowell syndrome

*

Relatively higher risk for systemic disease Relatively lower risk for systemic disease

Lupus panniculitis Chilblain lupus

*In adult patients, drug-induced SCLE should be considered.

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PREDOMINANT LOCATIONS OF INFLAMMATORY INFILTRATES IN SUBSETS OF CUTANEOUS LUPUS ERYTHEMATOSUS

ACLE

SCLE

DLE

LET

LEP

Fig. 41.3 Predominant locations of inflammatory infiltrates in subsets of cutaneous lupus erythematosus. The types of cutaneous lupus erythematosus are: acute cutaneous lupus erythematosus (ACLE), subacute cutaneous lupus erythematosus (SCLE), discoid lupus erythematosus (DLE), lupus erythematosus tumidus (LET) and lupus panniculitis (LEP); the latter three are forms of chronic cutaneous lupus erythematosus (see Fig. 41.2). The primary locations of the infiltrates are as follows: superficial dermis, ACLE and SCLE; superficial plus deep dermis and periadnexal, DLE; superficial and deep dermis, LET; and subcutaneous fat, LEP. The final diagnosis requires clinicopathologic correlation.  

CHARACTERISTIC SITES OF INVOLVEMENT FOR THE THREE MAJOR SUBTYPES OF CUTANEOUS LUPUS ERYTHEMATOSUS

Acute cutaneous LE

Subacute cutaneous LE

"Butterfly" rash

Chronic cutaneous LE Alopecia within lesions

LE tumidus

Lupus panniculitis Discoid LE

Chilblain lupus

Fig. 41.4 Characteristic sites of involvement for the three major forms of cutaneous lupus erythematosus (LE).  

666

Discoid lesions have the potential for scarring, and, over time, a substantial proportion of patients develop disfiguring scarring. Active lesions are intensely inflammatory, with a pronounced superficial and deep dermal inflammatory infiltrate. As a result, on palpation, active lesions typically feel thicker and firmer than surrounding uninvolved skin. The adnexa are prominently involved, with follicular plugging and scarring alopecia commonly observed. Dyspigmentation is a common sequela noted in longstanding lesions, typically with hypopigmentation in the central area and hyperpigmentation at the periphery (Fig. 41.6), but sometimes with vitiligo-like depigmentation. Rarely, squamous cell carcinoma develops in a longstanding discoid lesion. Patients who present with discoid lesions may have associated arthralgias, but, over time, only ~10–20% of these patients eventually meet the classification criteria for SLE (see below)12,43–46. Many of these patients meet criteria based primarily upon mucocutaneous disease rather than serious internal disease46, and the majority of those who progress do so within five years. The risk may be higher in patients with widespread (disseminated) discoid lesions44,45.

An unusual variant of DLE is hypertrophic DLE, characterized by thick scaling overlying the discoid lesion or occurring at the periphery of the discoid lesion. The intensely hyperkeratotic lesions are often prominent on the extensor arms (see Fig. 41.5H), but the face and upper trunk may also be involved. Frequently, there are typical discoid lesions present in other locations.

Subacute cutaneous lupus erythematosus Patients with SCLE typically note photosensitivity. Their lesions most frequently occur on sun-exposed skin. It is notable that the midfacial skin is usually spared, while the sides of the face, upper trunk and extensor aspects of the upper extremities are commonly involved (Fig. 41.7; see Fig. 41.4)47. In some patients, the disease may be mild, with only a few small scaly patches appearing after sun exposure. Lesions of SCLE may have an annular configuration, with raised pink–red borders and central clearing (Fig. 41.8), or a papulosquamous presentation with a chronic psoriasiform or eczematous appearance. SCLE lesions characteristically have a relatively sparse, superficial

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Lupus Erythematosus

41

A

B

D

E

C

F

Fig. 41.5 Various presentations of discoid lesions of lupus erythematosus. A,B,C Lesions, which favor the head and neck region, may show erythema, scaling, atrophy and dyspigmentation   in addition to scarring (and alopecia).   D Note the patulous follicular openings in addition to hyperpigmentation and scale. E The scarring process may be destructive. F,G Less common sites include the palms and soles, where lesions can be keratotic or ulcerative as in lichen planus. The patients with plantar involvement had systemic lupus erythematosus and responded well to isotretinoin. H Occasionally, hypertrophic lesions develop with significant hyperkeratosis. C, Courtesy,  

H

Kalman Watsky, MD. H, Courtesy, Julie V Schaffer, MD.

G

inflammatory infiltrate, and, consequently, they are minimally palpable. Lesions often result in dyspigmentation, particularly hypopigmentation or even depigmentation, but develop neither scarring nor dermal atrophy as sequelae. In ~20–30% of patients with SCLE, the disease is linked to medications (Table 41.2). The first drug associated with the development of SCLE was hydrochlorothiazide, but at least 100 agents have been

reported subsequently to induce or exacerbate SCLE48. A populationbased study from Sweden identified (in decreasing order) terbinafine, TNF inhibitors, anti-epileptics, and proton pump inhibitors as the most frequently associated medications49. The cutaneous lesions may or may not clear once the medication is discontinued. Approximately one-third to one-half of patients presenting with SCLE fulfill 4 or more classification criteria for SLE43. An occasional

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Fig. 41.6 Discoid lupus erythematosus (DLE) lesions with dyspigmentation and scarring alopecia. Hypopigmentation often develops centrally with areas of hyperpigmentation at the periphery. Note the plugging of follicular openings at 12 o’clock. By trichoscopy, follicular red dots can be seen in addition to follicular keratotic plugs (see Ch. 69). Courtesy, Kalman Watsky, MD.  

A

Fig. 41.7 Subacute cutaneous lupus erythematosus (SCLE). Numerous erythematous annular plaques on the back, some of which have associated white scale. Note the photodistribution. Courtesy, Kathryn Schwarzenberger, MD.  

B

Fig. 41.8 Subacute cutaneous lupus erythematosus (SCLE). Lesions are most commonly seen on the upper trunk and sun-exposed aspects of the upper extremities. The margins of the annular lesions may have scale-crust (A) or be composed of multiple papules (B). C Note the peripheral scale and relative sparing of the proximal interphalangeal joints. C, Courtesy, Lorenzo Cerroni, MD.  

668

C

CHAPTER

A

Lupus Erythematosus

41

C

B

Fig. 41.9 Acute cutaneous lupus erythematosus (ACLE). The facial erythema, often referred to as a “butterfly rash” may be variable (A), edematous (B) or have associated scale (C). The presence of small erosions can aid in the clinical differential diagnosis. A, Courtesy, Kalman Watsky, MD.  

Fig. 41.10 Acute cutaneous lupus erythematosus (ACLE). This patient had ACLE lesions on the arms as well as the face.  

MEDICATIONS ASSOCIATED WITH DRUG-INDUCED SUBACUTE CUTANEOUS LUPUS ERYTHEMATOSUS More common/higher risk* Terbinafine Thiazide diuretics (e.g. hydrochlorothiazide) TNF-α inhibitors Proton pump inhibitors (e.g. lansoprazole, pantoprazole, omeprazole) Calcium channel blockers (e.g. diltiazem, nifedipine, verapamil) Anti-epileptics (e.g. carbamazepine) Taxanes (e.g. docetaxel, paclitaxel) Thrombocyte inhibitors (e.g. ticlopidine) Less common* ACE inhibitors (e.g. enalapril, lisinopril) β-blockers Doxorubicin Interferon-α and -β Leflunomide Ranitidine HMG-CoA reductase inhibitors ("statins")

*Medications are classified as being more common or having a higher risk if there were >10 cases reported in the literature as of 2016 or the relative risk in reference 49 was ≥2.0. Medications are classified as being less common if there have been 3–10 cases reported and the relative risk was knees, wrists, ankles; erosive arthritis (15%) • RF-negative; ANA-negative •

10–16 years of age ≥5 joints in the first 6 months • Small joints of the hands & feet > knees, wrists, ankles; erosive arthritis (>50%) • Rheumatoid nodules, low-grade fever, mild anemia, weight loss • RF-positive (100%): ≥2 tests at least 3 months apart during first 6 months; ANA-positive (70%) •

≤4 joints in the first 6 months† Knees > ankles, wrists; often asymmetric • Type I: 1–8 years of age; uveitis 30–50%; ANA-positive 60%; RF-negative • Type II: 9–16 years of age; HLA-B27; RF-negative; ANA-negative •

45 Other Rheumatologic Disorders and Autoinflammatory Diseases

CLASSIFICATION OF JUVENILE IDIOPATHIC ARTHRITIS

Arthritis and enthesitis - or • Arthritis or enthesitis plus ≥2 of the following: sacroiliac joint tenderness/inflammatory lumbosacral pain, HLA-B27, family history of HLA-B27-associated disease in first- or second-degree relative, acute anterior uveitis, onset of arthritis in a boy after age 6 years

Children with arthritis of unknown cause persisting ≥6 weeks that does not fulfill criteria for any other categories or fulfills criteria for more than one category

*† Onset may be delayed for months to years.

The persistent oligoarticular arthritis subtype never affects more than 4 joints, whereas the extended oligoarticular arthritis subtype affects a cumulative total of ≥5 joints after the first 6 months of disease.

Table 45.1 Classification of juvenile idiopathic arthritis. The previous term was juvenile rheumatoid arthritis. Enthesitis is inflammation at the site of insertion of muscles. For all the types, diagnosis requires onset before 16 years of age and duration of arthritis for ≥6 weeks in at least one joint. ANA, antinuclear antibody; ESR, erythrocyte sedimentation rate; RF, rheumatoid factor.  

An exanthem is present in up to 90% of patients with the acute febrile presentation of sJIA, and it is often preceded by or accompanied by arthralgias. Although arthritis usually develops during the first few months of the disease course, in approximately one-quarter of patients the exanthem begins prior to the onset of arthritis, occasionally predating joint involvement by several years. The eruption is typically transient, non-pruritic and erythematous, and it coincides with fevers (Fig. 45.1A). There is a predilection for the axillae and waist, and linear lesions secondary to the Koebner phenomenon are often observed. Other less common cutaneous features include persistent plaques, which also may be linear (Fig. 45.1B), and periorbital edema and erythema8. Rheumatoid nodule-like lesions that favor extensor surfaces have been described in the setting of methotrexate therapy for sJIA9. Additional systemic features are outlined in Table 45.1. Although there are no laboratory findings specific for sJIA, leukocytosis, granulocytosis, thrombocytosis, elevated hepatic enzymes, an elevated ESR, and a polyclonal gammopathy are commonly observed; ANA and RF are rarely present. Serum ferritin levels are elevated and typically become even higher in the setting of macrophage activation syndrome (see below). Up to 10% of children may develop a serious and potentially lethal complication, the macrophage activation syndrome (MAS), characterized by fever, cytopenias, liver dysfunction, coagulopathy, hypofibrinogenemia, hypertriglyceridemia, and very high serum levels of ferritin (see Table 91.1). Increased serum IL-18 levels and depressed NK cell cytolytic function are also observed in patients with sJIA who develop MAS.

Pathology The evanescent exanthem is characterized by a perivascular and interstitial neutrophil-dominant mixed infiltrate, a reaction pattern also seen in autoinflammatory diseases (see below) and referred to as a “neutrophilic urticarial dermatosis”10. A variable number of dyskeratotic keratinocytes, located primarily in the upper epidermal layers, is also a typical finding.

Differential Diagnosis The differential diagnosis of a transient exanthem associated with fever and arthritis includes rheumatic fever, urticarial vasculitis, serum sickness-like reaction, and hereditary periodic fever syndromes (Table 45.2). The characteristic cutaneous findings in rheumatic fever are erythema marginatum (see Ch. 19) and urticarial lesions; rheumatic fever nodules are unusual. Patients with urticarial vasculitis may have arthralgias and fever; however, the urticarial lesions persist for greater than 24 hours, and they often resolve with purpura or postinflammatory hyperpigmentation. Histologic examination of recent-onset lesions demonstrates leukocytoclastic vasculitis. Additional disorders to consider include other autoimmune connective tissue diseases; leukemia (which may present with fevers and musculoskeletal complaints prior to the development of diagnostic abnormalities in the peripheral blood) as well as other malignancies

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Fig. 45.1 Systemic-onset juvenile idiopathic arthritis (Still disease). A Evanescent pink papules and figurate plaques in a child. B Persistent linear pink-brown plaques on the upper back. B, Courtesy,  

Julie V Schaffer, MD.

A

B

(e.g. lymphoma); and infections such as parvovirus B19, malaria, and rat bite fever.

Treatment The course and prognosis of sJIA is variable. In ~40–50% of patients, the arthritis resolves completely. However, approximately one-half of the children may have a chronic course that includes persistent arthritis and systemic complications such as macrophage activation syndrome (see above), hepatitis, pericarditis, and rarely amyloidosis (see Table 45.1). Patients with symptoms that persist for longer than 6 months carry a worse prognosis. Mild articular or extra-articular disease can be treated with nonsteroidal anti-inflammatory drugs (NSAIDs). Moderate or severe disease often requires the use of systemic corticosteroids with or without adjuvant drugs such as methotrexate. Inhibitors of TNF-α have been increasingly used as adjuvant or monotherapy; however, these agents are less effective in patients with sJIA than in those with other types of JIA11. Potent corticosteroid-sparing or immunomodulating agents, such as abatacept, azathioprine and leflunomide, are required infrequently11. Thalidomide is also a therapeutic option for children with sJIA. It suppresses the activity of cytokines (e.g. TNF-α and IL-6) that have been shown to play a role in the fever and malaise associated with sJIA. In clinical trials, antagonists of the IL-1 receptor (e.g. anakinra, rilonacept, canakinumab) and antagonists of the IL-6 receptor (e.g. tocilizumab) have demonstrated efficacy in sJIA11–15; as a result, they may become first-line therapies. Hematopoietic stem cell transplantation has been successfully performed in children who have failed to respond to combinations of medications11.

HEREDITARY PERIODIC FEVER SYNDROMES

Cryopyrin-associated periodic syndromes (CAPS) FMF

HIDS

TRAPS*

MWS

FCAS† (1 and 2)

NOMID (CINCA)

Ethnicity

Sephardic Jewish, Arab, Turkish, Italian, Armenian

Predominantly Dutch, northern European

Any ethnic group

Any ethnic group

Any ethnic group

Any ethnic group

Inheritance

AR

AR

AD

AD

AD

AD

MEFV

MVK‡

TNFRSF1A

NLRP3 (CIAS1)

NLRP3 (CIAS1); NLRP12

NLRP3 (CIAS1)

Gene Chromosome

16p13.3

12q24

12p13

1q44

1q44

1q44

Protein

Pyrin

Mevalonate kinase

TNF receptor-1A

Cryopyrin

Cryopyrin; monarch-1

Cryopyrin

Attack length

1–3 days

3–7 days

Often >7 days

1–2 days

Minutes–3 days

Continuous + flares

Mucocutaneous lesions

Erysipeloid erythema and edema

Erythematous macules and edematous papules, which may become purpuric; occasional oral and vaginal ulcers

Erythematous patches and edematous plaques (often annular or serpiginous); later ecchymotic in appearance; rarely oral ulcers

Urticarial papules and plaques

Cold-induced urticarial papules and plaques

Urticarial papules and plaques; occasional oral ulcers

Distribution of skin lesions

Favor lower leg, foot

Widespread on face, trunk and extremities

Migrate distally on an extremity with underlying myalgia; may be more widespread

Widespread on face, trunk and extremities

Extremities > trunk, face

Widespread on face, trunk and extremities

Abdominal pain and serositis

Peritonitis > pleuritis > pericarditis

Abdominal pain, but rarely serositis

Peritonitis > pleuritis, pericarditis

Abdominal pain, but rarely serositis

Rare

Rare

*† Includes familial Hibernian fever.

Also referred to as familial cold urticaria.

‡Allelic with mevalonic aciduria, which is characterized by dysmorphology, psychomotor retardation and progressive cerebellar ataxia as well as periodic fevers and other features of HIDS.

Table 45.2 Hereditary periodic fever syndromes. AD, autosomal dominant; AR, autosomal recessive; CINCA, chronic infantile neurologic, cutaneous and articular syndrome; FCAS, familial cold autoinflammatory syndrome; FMF, familial Mediterranean fever; HIDS, hyperimmunoglobulinemia D with periodic fever syndrome; MWS, Muckle–Wells syndrome; NOMID, neonatal-onset multisystem inflammatory disease; TNF, tumor necrosis factor; TRAPS, TNF receptor-associated periodic syndrome.  

724

Courtesy, Julie V Schaffer, MD.

CHAPTER

Cryopyrin-associated periodic syndromes (CAPS) FMF

HIDS

TRAPS*

MWS

FCAS† (1 and 2)

NOMID (CINCA)

Musculoskeletal findings

Monoarthritis > exercise-induced myalgia

Arthralgia > oligoarticular arthritis > myalgia

Migratory myalgia > arthralgia > monoarthritis

Myalgia (“lancinating limb pain”), arthralgia > large-joint oligoarticular arthritis

Arthralgia > myalgia

Epiphyseal and patellar overgrowth, arthritis, deforming arthropathy

Ocular findings

Uncommon

Uncommon

Periorbital edema, conjunctivitis, rarely uveitis

Conjunctivitis, episcleritis, optic disc edema

Conjunctivitis

Conjunctivitis, uveitis, optic disc edema, blindness

Neurologic findings

Rarely aseptic meningitis

Headache

Headache

Sensorineural hearing loss; headache

Headache

Sensorineural hearing loss; aseptic meningitis, seizures

Other clinical findings

Acute scrotal swelling; splenomegaly

Cervical LAN, HSM

Scrotal pain; splenomegaly, occasional LAN

Amyloidosis

Most common in M694V homozygotes

Rare

~15% of cases

~25% of cases

Uncommon

Late complication

Dermal infiltrate in typical skin lesions

Neutrophils

Neutrophils and/or lymphocytes; mild vasculitis common

Lymphocytes, monocytes and a few neutrophils

Neutrophils and/or lymphocytes (sparse)

Neutrophils (perivascular)

Neutrophils (perivascular + periadnexal)

Cutaneous vasculitis

LCV/HSP (5–10%), PAN (~1%)

LCV/HSP

Lymphocytic small vessel (rare)

Laboratory abnormalities§

Low C5a inhibitor in serosal fluids

High serum IgD‖ (>100 IU/ml) and IgA1; mevalonate in urine during attacks; low lymphocyte mevalonate kinase

Low serum soluble TNF receptor-1 (4000 mg/ml, and ferritin levels may correlate with disease activity16; a low circulating level of glycosylated ferritin (fraction 101°F [38.3°C] on several occasions over a period of at least 3 weeks or uncertain diagnosis after 1 week of hospitalization). The differential diagnosis is similar to that of sJIA (see above). Additionally, Schnitzler syndrome should be considered in an adult patient with recurrent fevers, arthralgia, and an urticarial eruption (see Ch. 18). In addition to non-pruritic urticaria, patients have recurrent fevers, bone pain (lower extremity, iliac and vertebral due to hyperostosis), and a monoclonal IgM gammopathy. Angioedema is observed in about 15% of patients with Schnitzler syndrome, and lymphoplasmacytic malignancies in 10–15%19. Histologic features are similar to those of adult-onset Still disease, i.e. a neutrophilic urticarial dermatosis10, but the neutrophilic infiltrate may be more dense.

Treatment Although some patients respond to high-dose aspirin or NSAIDs, the majority require oral corticosteroids (e.g. 40–60 mg prednisone daily) to control acute systemic features. When corticosteroids cannot be tapered, methotrexate is the most commonly employed second-line therapy. As in sJIA, biologic agents that inhibit the IL-1 receptor or IL-6 receptor (e.g. tocilizumab) appear to be promising20, 21. A therapeutic response to TNF-α inhibitors has also been reported, especially in those patients with severe chronic polyarticular disease. In addition, there have been reports of rituximab leading to improvement of refractory disease21a.

RELAPSING POLYCHONDRITIS A

Synonyms:  ■ Atrophic polychondritis ■ Systemic chondromalacia Fig. 45.2 Adult-onset Still disease. A Multiple pink macules and urticarial papules that were accompanied by a fever spike. The patient also had markedly elevated serum ferritin levels. B Histologic features of a mixed perivascular and interstitial infiltrate composed of neutrophils and lymphocytes.  

726

B

A, Courtesy, Diane Davidson, MD. B, Courtesy, Lorenzo Cerroni, MD.

Key features ■ A prominent clinical feature is erythema, swelling and pain of the cartilaginous portion of the ear, followed by destruction of the cartilage ■ Additional findings include nasal chondritis, which may result in a saddle nose deformity, as well as arthritis of the joints of the central chest ■ The most serious complications result from ocular, renal, and respiratory tract involvement; some of the patients develop a myelodysplastic syndrome

Fig. 45.3 Relapsing polychondritis. Erythema and swelling of the ear with sparing of the earlobe. Courtesy,  

Relapsing polychondritis is an uncommon inflammatory disorder with a suspected autoimmune origin that primarily affects cartilaginous structures. The diagnosis is usually established based upon the presence of: (1) histologically confirmed chondritis in two of the following three sites: auricular, nasal, or laryngotracheal cartilage; or (2) chondritis in one of the aforementioned sites plus at least two other features, including: ocular inflammation, vestibular dysfunction, hearing loss, and seronegative inflammatory arthritis. Relapsing polychondritis has been associated with other autoimmune disorders (25–30% of patients) and with myelodysplastic syndromes. Dermatologic manifestations may be the initial presenting sign and early diagnosis and treatment can prevent later complications, e.g. ascending aortitis, glomerulonephritis.

Kalman Watsky, MD.

History The disease was first described in 1923 by Jaksch-Wartenhorst and was called “polychondropathia”. It was later renamed “relapsing polychondritis” due to its episodic nature.

Epidemiology Relapsing polychondritis is most common in Caucasians, but has been reported in other races. In 80% of cases, the onset is between the ages of 20 and 60 years. Men and women are equally affected.

CHAPTER

45 Other Rheumatologic Disorders and Autoinflammatory Diseases

Introduction

Pathogenesis Although the etiology of relapsing polychondritis is unknown, the pathogenesis seems to involve an immunologic reaction against type II collagen22. However, circulating antibodies against type II collagen are present in fewer than half of affected individuals, and antibodies against types IX and XI collagen have also been described22. The clinical usefulness of these antibodies in the diagnosis, prognosis or monitoring of disease activity or the response to therapy is unclear. That said, transmission of relapsing polychondritis to a neonate from an affected mother has been reported (with subsequent recovery of the infant), lending support to an antibody-mediated pathogenesis. Antibodies to matrilin-1, an extracellular matrix protein located in auricular, septal, tracheal and sternal cartilage, may also play a role in the immune response seen in this disease22. Additionally, there is a positive association with HLA-DR4, while the extent of organ involvement has been negatively associated with HLA-DR6.

Clinical Features The most prominent clinical feature is erythema, swelling and pain of the cartilaginous portion of the auricle, sparing the earlobe (Fig. 45.3). Symptoms can persist for several days to weeks and may encroach on the external auditory meatus, compromising hearing. Chronic inflammation leads to destruction of the cartilage, leaving the ear unsupported and scarred. During the course of their disease, 90% of patients will develop auricular involvement, and in at least 25% it is a presenting sign. Nasal chondritis eventually develops in up to 70% of patients and may result in a saddle nose deformity. Symptoms include pain, stuffiness, crusting, rhinorrhea, epistaxis and compromise of olfaction. Nasal chondritis is typically less recurrent than the auricular chondritis, and the saddle nose deformity is more common in men23. Involvement of the cartilage of the respiratory tract (larynx, trachea, bronchi) and/or costochondral joints occurs in ~50% of patients and can be the most serious complication. Signs and symptoms include cough, hoarseness, choking, dyspnea, wheezing, or tenderness to palpation of the anterior neck in sites overlying the larynx or trachea. Complications include airway obstruction or collapse, flail chest, and secondary pulmonary infections. Arthritis is common (50–80% of patients) and it is the presenting symptom in one-third of patients. An episodic, migratory, asymmetric, non-erosive oligo- or polyarticular arthritis can affect any joint, although the knees and MCP and proximal interphalangeal joints are those most commonly affected. There may also be involvement of the sternoclavicular and sternomanubrial joints.

Ocular inflammation develops in ~65% of patients. It can involve virtually any component of the eye, leading to conjunctivitis, scleritis, corneal ulcerations, uveitis, or optic neuritis23. A variety of reactive cutaneous lesions are seen in patients with relapsing polychondritis24, including aphthae, small vessel vasculitis, annular urticarial plaques, livedo reticularis, (lymphocytic) Sweet syndrome, erythema elevatum diutinum, and erythema nodosum. None is pathognomonic and some may be coincidental or due to a coexisting disease. The presence of cutaneous small vessel vasculitis and/or aphthae is reported to increase the likelihood of an associated myelodysplastic syndrome (see Ch. 24). In addition, an overlap between relapsing polychondritis and Behçet disease, termed mouth and genital ulcers and inflamed cartilage (MAGIC) syndrome, has been reported25. Less common systemic features include audiovestibular damage, cardiovascular disease (aortitis, valvular dysfunction, pericarditis, conduction system abnormalities, myocarditis), renal dysfunction (glomerulonephritis, glomerulosclerosis, tubulointerstitial disease), and neurologic sequelae (cranial nerve palsies, vasculitis of the central or peripheral nervous system).

Pathology Histopathologically, there is breakdown of the normal lacunar structure of the cartilage, with neutrophilic infiltrates initially, followed by lymphoplasmacytic infiltrates. In late stages there is replacement of cartilage by granulation tissue and fibrosis.

Differential Diagnosis In the early inflammatory phase, the erythema and pain may be misdiagnosed as erysipelas or cellulitis. Infectious chondritis, traumatic chondritis, granulomatosis with polyangiitis (Wegener granulomatosis), small vessel vasculitis, and congenital syphilis may mimic the cartilage destruction seen in relapsing polychondritis (Table 45.3).

Treatment Although relapsing polychondritis has traditionally been associated with significant morbidity and mortality, it is a treatable disease, with survival rates of ~95% at 8 years. A comprehensive evaluation for systemic involvement, including a PET scan, should be performed prior to initiation of therapy, as systemic disease requires more aggressive

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DIFFERENTIAL DIAGNOSIS OF NASAL DEFORMITY OR DESTRUCTION

Neoplastic disorders Nasal natural killer/T-cell lymphoma* Squamous cell and basal cell carcinomas Olfactory neuroblastoma, salivary gland tumors Rhabdomyosarcoma, chondrosarcoma, other sarcomas

Inflammatory disorders Relapsing polychondritis Granulomatosis with polyangiitis (Wegener granulomatosis) Sarcoidosis SAVI (STING [stimulator of interferon genes]-associated vasculopathy with onset in infancy) (see Table 45.7) PLAID (PLCG2-associated antibody deficiency and immune dysregulation) (see Table 45.7)

Infectious disorders Bacterial Rhinoscleroma Glanders Noma Syphilis (late congenital and tertiary) Yaws (gangosa) Mycobacterial Leprosy Tuberculosis (lupus vulgaris) Fungal Paracoccidioidomycosis > other dimorphic fungal infections Zygomycosis (mucormycosis and entomophthoramycosis) Aspergillosis Parasitic Mucocutaneous leishmaniasis (espundia) Amebiasis due to free-living organisms† Rhinosporidiosis‡

Other etiologies Substance abuse (e.g. cocaine) Nasal myiasis Factitious/traumatic, including trigeminal trophic syndrome

*† Previously referred to as angiocentric T-cell lymphoma and lethal midline granuloma.

Include Acanthamoeba spp. and Balamuthia mandrillaris; granulomatous centrofacial skin lesions may lead to fatal amebic encephalitis. ‡Characterized by nasal polyps; recent molecular studies have classified the causative organism, Rhinosporidium seeberi, as an aquatic protistan parasite, phylogenetically at the animal–fungus boundary.

Table 45.3 Differential diagnosis of nasal deformity or destruction.  

treatment. The most common causes of death are pneumonia, systemic vasculitis, airway collapse and renal failure23. The initial treatment is with prednisone (0.5–1 mg/kg/day; higher range doses are given if there is visceral involvement), which improves acute flares and decreases the number and severity of recurrences. NSAIDs and colchicine may be employed to decrease fever, auricular chondritis and arthralgias; dapsone (50–150 mg/day) can also be used. Hydroxychloroquine and immunosuppressive agents (e.g. methotrexate, cyclosporine, azathioprine, cyclophosphamide, mycophenolate mofetil) have been tried alone or in conjunction with corticosteroids, with variable responses. More recently, successful results with infliximab and the IL-1 receptor antagonist anakinra have been reported. Tocilizumab, an IL-6 receptor antagonist, can be beneficial in patients with aortic involvement26,26a. Surgery is sometimes performed to repair damage to cartilaginous structures after the inflammation has been controlled.

SJÖGREN SYNDROME 728

Synonym:  ■ Sicca syndrome

Key features ■ This autoimmune disorder primarily affects secretory glands ■ The most common features are xerostomia, xerophthalmia, and arthritis ■ Cutaneous manifestations include xerosis, petechiae, purpura (palpable and non-palpable), urticarial vasculitis, and annular erythema ■ Serious complications include B-cell lymphomas, in particular extranodal marginal zone lymphomas of the MALT (mucosaassociated lymphoid tissue) type, peripheral neuropathy, interstitial pulmonary fibrosis, and systemic vasculitis ■ Patients often have an additional autoimmune disorder, in particular rheumatoid arthritis and lupus erythematosus ■ Factors associated with a poorer prognosis include vasculitis, hypocomplementemia, cryoglobulinemia, and/or parotid enlargement

Introduction Sjögren syndrome (SjS) is an autoimmune disorder that affects secretory glands, in particular the lacrimal and salivary glands. In addition to exocrine gland dysfunction, patients may develop a range of systemic manifestations due to autoimmune-mediated insults to multiple organ systems. This disease can be difficult to diagnose due to its insidious onset and initially nonspecific symptomatology. Mucocutaneous manifestations are prominent and may be the initial presenting signs. SjS may exist as a primary disorder or in association with other autoimmune diseases (secondary SjS), including rheumatoid arthritis, systemic lupus erythematosus (LE), and scleroderma.

History The first description of SjS was by Hadden in 1888. However, it was not until 1933 that Henrik Sjögren described the triad of keratoconjunctivitis sicca, xerostomia, and arthritis. Over the past several decades, the diagnostic criteria for SjS have been debated and revised, and currently the American College of Rheumatology 2016 Classification Criteria for Sjögren’s Syndrome are most commonly employed (Table 45.4)27.

Epidemiology Although SjS most commonly presents during the fourth and fifth decades, pediatric cases have been reported. The female : male ratio is 9 : 1 and men with this syndrome tend to have a less aggressive disease course with fewer extraglandular manifestations. SjS is one of the most common autoimmune disorders, affecting approximately 0.3–0.6% of the total population28. The overall mortality rate in primary SjS is comparable to that in the normal population28.

Pathogenesis As in other autoimmune diseases, environmental factors likely trigger inflammatory events in a genetically susceptible host, resulting in the autoimmune phenomena characteristic of the disease. In SjS, it has been proposed that abnormalities intrinsic to glandular epithelial, dendritic, and/or stromal cells may initiate the lymphocytic infiltration and aberrant signaling. Viral infection of the glands may stimulate the innate immune system via Toll-like receptors, leading to autoimmune destruction of glandular cells due to molecular mimicry29. While no single virus has been consistently or reproducibly demonstrated as a predominant trigger, EBV, coxsackievirus, human T-cell lymphotropic virus-1 (HTLV-1), and hepatitis C virus have all been implicated in various populations28, 30. There is upregulation of type I and II interferon gene expression, possibly related to viral infection and perpetuated by immune complexes such as anti-SSA/Ro or anti-SSB/La antibodies complexed with hYRNA. Activation of the Th17/IL-23 system has also been described in SjS patients31.

CHAPTER

The classification of primary SjS applies to any individual who meets the inclusion criteria*, does not have any of the conditions listed as exclusion criteria^, and has a score of ≥4 when the weights from the five criteria items below are summed

Criterion

Weight/score

Labial salivary gland with focal lymphocytic sialadenitis and focus score of ≥1 foci/4 mm2**

3

Anti-SSA/Ro-positive

3

Ocular staining score ≥5 (or van Bijsterveld score ≥4) in at least one eye^^,§

1

Schirmer’s test ≤5 mm/5 min in at least one eye^^

1

Unstimulated whole saliva flow rate ≤0.1 mL/min^^,§§

1

*Inclusion criteria apply to any patient with at least one symptom of ocular or oral dryness, defined as a positive response to at least 1 of the following questions: (1) Have you had daily, persistent, troublesome dry eyes for more than 3 months? (2) Do you have a recurrent sensation of sand or gravel in the eyes? (3) Do you use tear substitutes more than 3 times a day? (4) Have you had a daily feeling of dry mouth for more than 3 months? (5) Do you frequently drink liquids to aid in swallowing dry food? or in whom there is suspicion of SjS from the ELAR SjS Disease Activity Questionnaire (at least 1 domain with a positive item). ^Exclusion criteria include prior diagnosis of any of the following conditions: (1) history of head and neck radiation treatment; (2) active hepatitis C infection (with confirmation by PCR); (3) AIDS; (4) sarcoidosis; (5) amyloidosis; (6) GVHD; (7) IgG4-related disease. Per Daniels et al. protocol27a and performed by an experienced pathologist. ** ^^Patients taking anticholinergic drugs should be evaluated after a sufficient interval without these medications for tests to be valid. §Per Witcher et al. scoring system27b and van Bijsterveld scoring system27c. §§Per Navazesh and Kumar protocol27d. Table 45.4 American College of Rheumatology (ACR)/European League Against Rheumatism (ELAR) 2016 classification criteria for primary Sjögren’s syndrome. GVHD, graft-versus-host disease. From reference 27.  



Serum levels of B-cell activating factor (BAFF) are elevated in patients with SjS. It is possible that this protein allows autoreactive B cells to escape apoptosis and have autoimmune potential. Patients with SjS frequently have hypergammaglobulinemia and autoantibodies that recognize SSA/Ro and/or SSB/La; presence of these autoantibodies increases the risk of developing subacute cutaneous lupus-like drug reactions and cutaneous small vessel vasculitis, both in patients with SjS and in those with systemic LE. In lymphocytes infiltrating the salivary glands, increased levels of costimulatory molecules CD40 and CD40 ligand (CD154) have been noted, as has increased expression of the genes that encode the anti-apoptotic proteins bcl-2 and bcl-x. This could play a role in the development of marginal zone B-cell lymphoma in the salivary gland.

Clinical Features The most prominent feature of SjS is xerosis of the mucous membranes, particularly of the eyes, mouth, and vagina. Keratoconjunctivitis sicca occurs as a result of destruction of the lacrimal gland, and patients may experience ocular dryness, a foreign body sensation, pain or photophobia. Objective tests to verify decreased tear production (e.g. Schirmer test) and to assess the integrity of the corneal surface (e.g. lissamine green stain, fluorescein stain, Rose Bengal dye) should be performed by an ophthalmologist (see Table 45.4)29. In the Schirmer test, a piece of Whatman paper wick is folded over the lower eyelid for 5 minutes, and if the aqueous component of the tear film migrates ≤5 mm, there is lacrimal gland dysfunction. Complications of xerophthalmia include keratitis, corneal thinning and ulceration, and recurrent infections29. Xerostomia due to destruction of the major and minor salivary glands may present as dryness, soreness, or burning of the mouth and lips. Patients may have difficulty swallowing or require frequent ingestion of fluids during conversations. On examination, the infralingual salivary pool may be absent and the saliva cloudy and stringy. Although the major salivary glands (parotid and submandibular) may become

Fig. 45.4 Hypergammaglobulinemic purpura in a patient with Sjögren syndrome. Purpuric macules and thin papules are admixed with hemosiderin deposition at previous sites of involvement. Courtesy, Julie V Schaffer, MD.  

transiently enlarged (~20% of patients), persistent swelling of these salivary glands or lymphadenopathy should prompt an evaluation for lymphoma. Of note, patients with SjS have an incidence rate of lymphoma that is nearly 20× that of the general population32; these B-cell lymphomas are often extranodal and can originate in salivary as well as lacrimal glands. Xerostomia may be assessed functionally by salivary gland scintigraphy, sialometry or parotid sialography, but these tests are not commonly employed. On the other hand, salivary gland biopsy is a readily available procedure and represents an important component of the diagnosis of SjS (see Table 45.4). Perlèche or thrush can result from candidal overgrowth, and should be suspected when patients report a sudden increase in pain. Dental caries are a common problem, particularly along the gingival margin, and scrupulous dental hygiene with frequent dental examinations is crucial. Because saliva has an elevated pH that neutralizes gastric acid, patients with SjS may experience more severe gastroesophageal reflux disease or gastrotracheal reflux (which can mimic upper respiratory tract infections), and aggressive reflux treatment is warranted29. Vaginal xerosis is common, and since many patients are perimenopausal or postmenopausal, it may be multifactorial. Symptoms include dryness, burning, and/or dyspareunia. Candidal and bacterial overgrowth are common complications. The most common skin finding is xerosis, usually presenting as pruritus. Other cutaneous manifestations include palpable and nonpalpable purpura (Fig. 45.4), urticarial vasculitis, erythema nodosum, nodular amyloidosis, and Sweet syndrome. Lesions of annular erythema, clinically reminiscent of subacute cutaneous LE or LE tumidus, have been reported primarily in Japanese patients with SjS. Whether or not these patients have an LE/SjS overlap is a matter of debate. Raynaud phenomenon has been reported in 30% of patients with primary SjS and it can precede sicca symptoms by years. Vasculitis is the most important cutaneous finding in SjS, as it is associated with an increased risk of morbidity and mortality33. Patients with cutaneous small vessel vasculitis may present with palpable purpura or with urticarial lesions and may have hypo- or normocomplementemia (see Ch. 24). Some patients develop lesions of pigmented purpura (capillaritis) or macular hemorrhage which can be identical to the lesions seen in patients with hypergammaglobulinemic purpura of Waldenström (see Ch. 22). Of note, many of the patients with the latter disorder have evidence of an autoimmune connective tissue disease, including SjS. The presence of purpura should prompt an evaluation for cryoglobulinemia. Patients found to have vasculitis, cryoglobulinemia, and/or hypocomplementemia have an increased mortality rate and an increased risk of developing B-cell lymphomas32. Extraglandular and extracutaneous involvement may present with a diverse array of symptoms due to involvement of a variety of tissues including the lungs (interstitial pneumonitis, often subclinical), kidneys (interstitial nephritis, tubular dysfunction), bone marrow, and peripheral and central nervous systems (peripheral neuropathy,

Other Rheumatologic Disorders and Autoinflammatory Diseases

45

AMERICAN COLLEGE OF RHEUMATOLOGY (ACR)/EUROPEAN LEAGUE AGAINST RHEUMATISM (ELAR) 2106 CLASSIFICATION CRITERIA FOR PRIMARY SJÖGREN’S SYNDROME (SjS)

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Rheumatologic Dermatology

7

short-term memory loss, depression, immune-mediated hearing loss, multiple sclerosis-like presentation)29. Arthritis is a common finding; it is usually polyarticular, non-erosive, chronic and progressive, and it can be asymmetric. The most frequently involved joints are the knees and ankles. As discussed above, the risk of developing B-cell lymphomas is increased in patients with SjS32. The lymphomas are often extranodal in origin (e.g. salivary glands, lacrimal glands) and usually marginal zone lymphomas of the MALT type34.

mycophenolate mofetil) are used in patients with serious internal manifestations. Overall, therapy with TNF-α inhibitors has not proven to be very useful29. B-cell depletion with the anti-CD20 antibody rituximab has led to conflicting results35,36. Sequential treatment with belimumab (anti-BAFF antibody) followed by rituximab led to improvement in one patient with low-grade lymphoma, cutaneous ulceration, cryoglobulinemia, and overexpression of BAFF37; this regimen deserves investigation.

Laboratory Findings

MIXED CONNECTIVE TISSUE DISEASE

Primary SjS is associated with anti-SSA/Ro (~60–80%), and anti-SSB/ La (~40–60%) autoantibodies. Patients with secondary SjS may have additional autoantibodies, depending upon the specific autoimmune connective tissue disease (see Ch. 40). Other laboratory abnormalities often observed in patients with SjS include an elevated ESR, hypergammaglobulinemia, and a positive RF.

Synonyms:  ■ Undifferentiated connective tissue disease ■ Sharp syndrome

Pathology

Key features

In order to establish the diagnosis of SjS, a biopsy of the minor salivary glands is often performed. The presence of one or more foci of inflammatory cells (50 or more lymphocytes) in 4 mm2 of salivary gland tissue fulfills one of the classification criteria for SjS (see Table 45.4). A mixture of B and T cells (with a normal CD4 : CD8 ratio) is usually seen. The typical histopathologic features of pigmented purpuric eruptions, cutaneous small vessel vasculitis, cryoglobulinemic vasculitis, and urticarial vasculitis are seen in the vasculopathies associated with SjS; however, none of the histologic findings is specific for SjS.

■ The existence of mixed connective tissue disease (MCTD) as a distinct entity is controversial, as patients often have overlapping clinical and serologic features of various combinations of systemic sclerosis, polymyositis, rheumatoid arthritis, and systemic LE ■ Major disease features include: high-titer IgG anti-U1 ribonuclear protein (U1RNP) antibodies, Raynaud phenomenon, swollen hands or sclerodactyly, myositis, esophageal dysmotility, and arthritis ■ Compared with systemic LE, there is a lower incidence of renal disease and a higher incidence of pulmonary disease ■ Pulmonary hypertension is the most serious complication

Differential Diagnosis Sicca symptoms are common in the elderly in part due to age-related atrophy of secretory glands. Xerostomia is a common side effect of drugs with anticholinergic properties and it may also result from previous irradiation, salivary gland stones, and chronic viral infections. Xerophthalmia can be a symptom of ocular rosacea (see Ch. 37), infiltration of the lacrimal glands (e.g. sarcoidosis, amyloidosis), irradiation, estrogen deficiency, and hypovitaminosis A. It may reflect impaired blinking (e.g. Parkinson disease) or herald the onset of mucous membrane (cicatricial) pemphigoid. In addition, patients with chronic GVHD can have both xerophthalmia and xerostomia. Early in the disease course, it may be difficult to distinguish SjS from other autoimmune connective tissue diseases. Complaints such as arthralgias and myalgias are often nonspecific. Because 50% of the salivary glands must be destroyed before symptoms arise, sicca symptoms may not be a prominent complaint initially. Patients with SjS/LE overlap can pose a diagnostic challenge. They are often anti-Ro-positive and may have prominent cutaneous disease or they may be asymptomatic but give birth to a child with neonatal LE (anti-Ro antibodies are associated with subacute cutaneous LE as well as with neonatal LE; see Ch. 41).

Treatment

730

Therapy for most manifestations of SjS is symptomatic. Xerophthalmia may be treated with preservative-free artificial tears and lubricating ointments. The placement of punctual plugs that occlude the nasolacrimal ducts may increase accumulation of tear film. Home humidifiers may help relieve symptoms of xerophthalmia. Cyclosporine (0.05%) eye drops may prove helpful, but it can take several months to achieve a therapeutic effect. Treatment of xerostomia is outlined in Table 45.5. Dryness of the skin can be treated with emollients. Vaginal dryness may be improved with artificial lubricants. Frequent monitoring for and treatment of candidal and bacterial overgrowth is recommended; prophylactic use of vaginal antifungal agents is an option. In postmenopausal women, intravaginal or systemic estrogen replacement therapy can reduce compounding of symptoms. In general, immunosuppressive agents should be reserved for patients with cutaneous vasculitis or involvement of the nervous system and internal organs. Systemic corticosteroids, hydroxychloroquine, and steroid-sparing immunosuppressants (e.g. methotrexate, azathioprine,

Introduction The designation of mixed connective tissue disease (MCTD) as a distinct disease entity continues to be debated. However, there is little argument that there exists a group of patients with a constellation of serologic and clinical manifestations for whom MCTD is a useful label. These patients have high titers of antibodies to U1RNP and certain clinical features observed in other autoimmune connective tissue diseases, including arthritis, pulmonary hypertension, esophageal dysmotility, myopathy, digital swelling, and constitutional symptoms. Over time, some patients with MCTD develop manifestations more consistent with the diagnosis of systemic LE or systemic sclerosis.

History MCTD was first described by Sharp et al.38 in 1972, including its clinical features and the presence of an antibody to an extractable nuclear antigen.

Epidemiology MCTD is much more common in women than in men (9 : 1), with most patients presenting during the second or third decade of life. The exact incidence of MCTD is unclear, especially since some authors do not consider it to be a separate entity. It is believed that “classic” MCTD is the least common of the autoimmune connective tissue diseases. In the past, the prognosis of MCTD was thought to be better than that of systemic LE; however, long-term evaluation of patients with MCTD has found their prognosis to be poorer than that expected in patients with systemic LE. The majority of deaths in MCTD have been attributable to pulmonary hypertension39,40.

Pathogenesis Although the pathogenesis is not clear, there appears to be an immune response to U1RNP41. U1RNP plays an essential role in the splicing of pre-mRNA into mRNA. The U1RNP molecule consists of three polypeptides (U1-A, U1-C, U1-70 kDa) that associate with U1RNA as well as a series of proteins that are common to multiple RNA-splicing molecules, including U1 spliceosomal RNA, Smith (Sm), and splicing factors (SR proteins). Although anti-U1RNP IgG antibodies may be seen in LE, systemic sclerosis and polymyositis, titers of anti-U1RNP

CHAPTER

General measures Avoid smoking cigarettes, cigars



Reduce intake of salty, spicy and acidic foods



Smoking exacerbates dryness

Limit carbohydrate intake, including sugars



Avoid acidic (low pH) drinks



Reduce alcohol and caffeine consumption



Avoid excessive sipping



Avoid OTC antihistamines and decongestants



Use sodium bicarbonate mouth rinse* twice daily



Use a humidifier in bedroom overnight



These foods can exacerbate dryness and cause irritation These foods or drinks increase risk of dental caries

Examples: cola (pH 2.6), herbal tea (pH varies, but can be as low as 2.5–3), coffee (pH 5) • Acceptable drinks: black tea (pH 5.7–7), tap water (pH 7) They can worsen dryness Can reduce mucous film Further decrease saliva production

Analgesic effects via its buffer action May improve taste disturbance • Can reduce tendency for oral candidiasis •

Adds moisture to the ambient air

Saliva substitutes (oral moisturizers) Contain various combinations of xylitol, hydroxyethyl cellulose, glycerin and sorbitol; should be alcohol-free and contain fluoride or calcium phosphate Try different products as they vary in taste, viscosity, feel of lubrication, duration of efficacy; choice based upon patient preference

• •

Spray, e.g. Biotene® Moisturizing Mouth Spray, Oasis® Dry Mouth Moisturizing Spray

Use prior to speaking and during the day to assist in talking



Solution, e.g. Salivart® Oral Moisturizer, Saliva Substitute™ (Roxane)



Gel, e.g. Biotene® Oral Balance Gel



Lozenges, e.g.

Xylimelts®,

ACT®

Dry Mouth Lozenges

45 Other Rheumatologic Disorders and Autoinflammatory Diseases

XEROSTOMIA – PATIENT INSTRUCTIONS

Use prior to eating to assist in swallowing and to form food bolus At bedtime Use overnight



Saliva stimulants – sialagogues Local Sugar-free**, acid-free gum or candy that contains xylitol



Dried fruit slices



Should not contain lemon, orange or citric acid Acceptable examples: Biotene® Dry Mouth Gum • Recaldent®-containing gum may also enhance remineralization, e.g. Trident Xtra Care® •

Example: dried peaches

Systemic† Approximately 50% of patients respond Judge response at 8–12 weeks; at that time point, dosage can be increased • Contraindicated in patients with pulmonary disease (e.g. asthma, bronchiolitis obliterans due to GVHD), narrow angle glaucoma • •

Pilocarpine (Salagen®) Cimevuline

(Evoxac®)

5 mg three times daily



30 mg three times daily



Dental care Avoid toothpastes that contain detergent (e.g. SLS), whiteners, or flavorings if this causes burning



Whitening toothpastes have abrasives that can be irritating Acceptable toothpastes: Biotene® PBF Dry Mouth Fluoride Toothpaste

Avoid commercial mouthwashes that contain alcohol or peroxide



Avoid anti-bacterial mouthwashes that contain alcohol or phenol



Professional dental cleaning



Topical fluorides





Acceptable mouthwashes: Biotene® Dry Mouth Oral Rinse; supersaturated calcium phosphate rinses, e.g. NeutraSal®, Caphosol® Acceptable anti-bacterial mouthwashes: alcohol-free chlorhexidine gluconate mouth rinse USP 0.12% (GUM®) 3 to 4 times per year Fluoride rinses, e.g. ACT® Total Care Dry Mouth Rinse Brush-on fluoride gel (can also be applied in mouth tray 5 minutes/day), e.g. PreviDent® 5000



Remineralizing agents, e.g. Seal-Rite™

Can be applied by dentist



*Half teaspoon of sodium bicarbonate in glass of tap water. Not sugarless, as these products may contain fructose. ** †Also helpful for xerophthalmia. Table 45.5 Xerostomia – patient instructions. GVHD, graft versus host disease; OTC, over-the-counter; SLS, sodium lauryl sulfate. Courtesy, Alison Bruce, MD.  

tend to be higher in MCTD. Another distinct autoantigen often recognized by MCTD sera is hnRNP-A2, which is another spliceosome component. Of note, antibodies to EBV and cytomegalovirus cross-react with components of U1RNP, suggesting that molecular mimicry related to prior exposure to these viruses may be involved in the development of anti-U1RNP autoimmunity. Genetic studies have demonstrated an

association of HLA-DR4, -DR1 and -DR2 and MHC class I polypeptiderelated sequence A (MICA) in patients with MCTD42.

Clinical Features MCTD often presents with prominent cutaneous symptoms, including Raynaud phenomenon and edematous erythematous digits. Raynaud

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Rheumatologic Dermatology

7

phenomenon is often an early manifestation, and it eventually develops in almost all patients; “ice-pick” digital infarcts or even gangrenous digits can be observed. The patients often have periungual telangiectasias with dropout areas, and the hands and fingers may feel sclerodermatous and tight due to increased dermal collagen deposition as well as edema. Calcinosis cutis can also occur. Poikilodermatous areas on the upper trunk and proximal extremities are common, in addition to the sclerodermoid changes of the distal extremities. However, the diffuse involvement of the face, upper trunk or extremities observed in patients with systemic sclerosis is usually not seen. Photosensitivity and lesions indistinguishable clinically and histopathologically from acute systemic LE (e.g. malar rash) or subacute cutaneous LE may also occur. Cutaneous small vessel vasculitis and livedoid vasculopathy may develop as well43. Cutaneous mucinosis, rheumatoid nodules, and orogenital mucosal lesions such as buccal ulcers and nasal septal perforation have been described43. An inflammatory myopathy is common in patients with MCTD. However, dermatomyositis-specific findings such as Gottron papules, a periorbital heliotrope rash, and erythema and scaling of the scalp are not usually seen. Arthralgias or polyarticular arthritis occur in 50–70% of patients with MCTD, often early in the disease course43. The arthritis ranges from mild to erosive. Pulmonary hypertension is the most serious complication of MCTD (occurring in up to 25% of patients), and it may be associated with the presence of antiphospholipid antibodies and elevated serum levels of NT-proBNP (N-terminal pro-brain natriuretic peptide)44. Pulmonary fibrosis, often mild, may also occur, and, like pulmonary hypertension, is frequently asymptomatic early during its course. Pleurisy and pericarditis occur in ~60% of patients45. Periodic pulmonary examinations, chest radiographs, high-resolution CT scans, echocardiography, and pulmonary function tests are warranted. Esophageal dysmotility is common, occurring in up to 85% of patients; it can be asymptomatic, but most commonly manifests as reflux esophagitis and dysphagia.

Pathology There are no histopathologic features pathognomonic for MCTD. The histologic findings vary depending upon the type of skin lesion examined. In general, cutaneous manifestations clinically resembling acute or subacute cutaneous LE, leukocytoclastic vasculitis or livedoid vasculopathy will have the histologic features characteristic of these entities.

Differential Diagnosis The differential diagnosis of MCTD consists primarily of systemic sclerosis, systemic LE, dermatomyositis/polymyositis, and overlap syndromes. Some patients initially diagnosed with MCTD may over time develop a preponderance of clinical and serologic features of one of these diseases, requiring a change in diagnosis. The absence of hypocomplementemia or anti-dsDNA and anti-Sm antibodies helps to distinguish MCTD from systemic LE, while the more severe arthritis and the myositis help distinguish MCTD from systemic sclerosis. The inflammatory myopathies usually manifest with more severe myositis than is encountered in MCTD, and the former do not usually feature the lower esophageal dysmotility common in MCTD.

Treatment

732

The goal of therapy in MCTD is to control symptoms and maintain function. Therapy should be tailored to the specific organ involvement and disease severity. Patients with pulmonary hypertension require longitudinal care with a pulmonologist or rheumatologist experienced in managing pulmonary complications. In general, manifestations of MCTD that often overlap with LE or polymyositis, such as serositis, cutaneous lesions, arthritis and myositis, usually respond to corticosteroids, while scleroderma-like features such as Raynaud phenomenon and pulmonary hypertension generally do not46. Topical corticosteroids and systemic antimalarials are often helpful for LE-like dermatoses. Raynaud phenomenon can be treated with vasodilators in addition to non-pharmacologic measures (avoidance of cold, gloves; see Ch. 43). For severe systemic disease, a variety of therapies have been evaluated, including immunosuppressive agents (e.g. methotrexate, cyclosporine, azathioprine, mycophenolate mofetil,

cyclophosphamide), plasmapheresis, and autologous hematopoietic stem cell transplantation. It is difficult to evaluate the efficacy of these treatments since there are no prospective large-scale studies, and most are based on single cases or small case series.

EXTRA-ARTICULAR MANIFESTATIONS OF RHEUMATOID ARTHRITIS Key features ■ In addition to deforming arthritis, patients can develop rheumatoid nodules, pyoderma gangrenosum, and small and medium-sized vessel vasculitis ■ Other cutaneous manifestations include rheumatoid neutrophilic dermatitis and palisaded neutrophilic and granulomatous dermatitis

Introduction Rheumatoid arthritis (RA) is a systemic disease in which the primary manifestation is inflammatory arthritis, but there can be a variety of cutaneous manifestations (see Table 53.1). Several of these can serve as helpful diagnostic clues or, in the case of rheumatoid vasculitis, point to serious illness.

Epidemiology RA is common, affecting 1–3% of the adult population in the US. Women are affected two to three times more often than men, and although it may develop in any age group, the peak onset is between 30 and 55 years of age.

Pathogenesis As with other autoimmune diseases, a complex interplay between innate and acquired immune responses appears to be involved. One hypothesis is that the preclinical stage, i.e. before joint symptoms develop, involves mucosal inflammation47. Initiating events in the joints include the binding of extracellular matrix constituents in the synovium to Toll-like receptors, leading to the subsequent induction of inflammatory responses (increased TNF-α, IL-6, chemokines and angiogenic factors) and maturation of antigen-presenting cells. A gainof-function polymorphism in the PTPN22 gene, which encodes a lymphoid-specific protein tyrosine phosphatase that serves as a negative regulator of T-cell activation, confers susceptibility to RA and JIA, as well as other autoimmune disorders such as systemic LE, Graves disease, and type 1 diabetes mellitus (perhaps by impairing thymic negative selection or regulatory T cells). Of note, there is a reduction in the number of regulatory T cells in RA; Th17 lymphocytes are also thought to play a pathogenic role48. RA is also associated with HLA-DR1 and -DR4. The HLA-DRB1 shared epitope allele, a highly significant genetic risk factor for RA, contributes to its pathogenesis primarily by increasing the propensity to develop antibodies that target citrullinated proteins (which are found in the skin and joints). Such antibodies represent specific and predictive serologic markers for RA, and they have been shown to bind the synovium and enhance tissue injury in animal models of autoimmune arthritis. A variety of infectious agents, including particular proteins produced by EBV and Escherichia coli, have been thought to play a role due to molecular mimicry of the hypervariable domain of HLADRB1*0401 or induction of anti-citrullinated protein antibody production (detected by anti-cyclic citrullinated peptide [anti-CCP] antibody assays).

Clinical Features Rheumatoid nodules Rheumatoid nodules are present in 20% of patients with RA, and they occur in patients with moderate to high titers of RF (IgG, IgM or IgA). Most, if not all, of the cases of seronegative RA with “rheumatoid



CHAPTER

EVALUATION OF A PATIENT WITH SUSPECTED RHEUMATOID (MEDIUM-VESSEL) VASCULITIS AND NEGATIVE/INCONCLUSIVE CUTANEOUS HISTOLOGIC FINDINGS

Nerve conduction studies/electromyography

Kalman Watsky, MD.

Including mononeuritis multiplex

+



Sural nerve biopsy Muscle biopsy

+ Rheumatoid vasculitis

− Angiogram, if strong suspicion

Fig. 45.7 Evaluation of a patient with suspected rheumatoid vasculitis (involving medium-sized vessels) in whom cutaneous histologic findings are negative or inconclusive.  

Fig. 45.6 Methotrexate-induced nodulosis in a patient with rheumatoid arthritis. Courtesy, Jean L  

Bolognia, MD.

45 Other Rheumatologic Disorders and Autoinflammatory Diseases

Fig. 45.5 Rheumatoid arthritis and rheumatoid nodules. Note the periarticular location of the skincolored nodules. Courtesy,

vasculitis typically occurs in the context of high-titer RF, rheumatoid nodules, and a history of severe erosive arthritis. The vasculitis may affect vessels of any size, and the clinical presentations reflect this, with palpable and non-palpable purpura in small vessel disease versus nodules, ulcerations, necrotizing livedo reticularis, and/or digital infarcts in medium-sized vessel disease50. Systemic manifestations of rheumatoid vasculitis can include neuropathies, cerebral infarction, scleritis, alveolitis, carditis, intestinal ulcers, and proteinuria. Clinicopathologic correlation and serologic assessment should be performed when rheumatoid vasculitis is suspected. For example, if an ulcer is biopsied, a wedge perpendicular to the edge of the ulcer which includes both surrounding non-ulcerated skin as well as the ulcer base should be obtained. In up to 40% of patients with RA and mediumsized vessel vasculitis, there is evidence of a peripheral neuropathy (subclinical or clinical) that often presents as mononeuritis multiplex. This incidence seems to be even higher in patients with extensive cutaneous disease. Therefore, if vasculitis cannot be identified after multiple deep skin biopsies but the diagnosis is still suspected, nerve conduction studies followed by sural nerve biopsy (or a muscle biopsy) can be performed (Fig. 45.7). Mortality may be as high as 40%51, and, therefore, aggressive intervention is warranted.

Bywaters lesions nodule”-like lesions were proven to be subcutaneous granuloma annulare or other entities with palisading granulomas histologically (see Ch. 93). Rheumatoid nodules are firm, semi-mobile papulonodules that occur most commonly in periarticular locations over extensor surfaces (Fig. 45.5), and in areas subject to pressure or trauma. They range from several millimeters to as large as 5 cm in diameter and are typically asymptomatic. Occasionally the nodules are tender or painful, especially if there is associated trauma or ulceration. Rheumatoid nodules may also occur in visceral organs. Accelerated rheumatoid nodulosis is characterized by the sudden appearance of multiple rheumatoid nodules (Fig. 45.6). Lesions usually appear following the initiation of methotrexate therapy, but can also be seen after the initial administration of TNF-α inhibitors. In some of these patients, there had also been a tapering of systemic corticosteroids. Methotrexate can also induce a papular eruption whose histologic features overlap with those of interstitial granuloma annulare and interstitial granulomatous dermatitis (see Ch. 93)49.

Rheumatoid vasculitis Rheumatoid vasculitis is a rare and typically late complication of RA. It is thought to occur in only 2–5% of those with RA, but, at autopsy, vasculitis has been found in up to a third of patients. Rheumatoid

Bywaters lesions include nailfold thromboses and purpuric papules on the distal digits, especially the digital pulp (see Fig. 53.4). Histologically, there is a small vessel leukocytoclastic vasculitis. Typically these lesions are not associated with systemic vasculitis.

Felty syndrome Felty syndrome represents an uncommon but severe subset of seropositive RA that is characterized by granulocytopenia, splenomegaly, and therapy-resistant leg ulcers (often pretibial). These patients are predisposed to cutaneous and systemic infections that can be refractory to standard treatment, and they are at increased risk of lymphomas and leukemias. The ulcers are likely multifactorial and may be secondary to pyoderma gangrenosum, medium-sized vessel vasculitis (although vasculitis is often not confirmed histologically), venous hypertension, neuropathy, or perhaps an ulcerating form of palisaded neutrophilic and granulomatous dermatitis (PNGD)52.

Neutrophilic dermatoses Sterile infiltration of the skin by neutrophils can occur in patients with RA. The primary disorders are pyoderma gangrenosum (PG), Sweet syndrome, and rheumatoid neutrophilic dermatitis (see Chs 26 & 53), but there may be overlap and the term “neutrophilic dermatosis” is often used. Pyoderma gangrenosum occurs at a higher frequency in

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7

Fig. 45.8 Pyoderma gangrenosum in a patient with rheumatoid arthritis. The chronic relapsing ulcerations involved the lower extremities. Courtesy, Carlos

Rheumatologic Dermatology



H Nousari, MD.

A

patients with RA than in the general population. Lesions can develop on the lower extremities (Fig. 45.8), as well as less common locations such as the abdomen and face. Rheumatoid neutrophilic dermatitis (also referred to as rheumatoid neutrophilic dermatosis) resembles Sweet syndrome, both clinically and histologically. It occurs in patients with severe and usually seropositive RA, and it is characterized by erythematous urticarial papules and plaques that are persistent and asymptomatic, but occasionally ulcerate. Lesions are symmetrically distributed, most commonly on the extensor forearms and hands, but they can occur elsewhere.

Other Patients with RA may also develop erythema elevatum diutinum (see Ch. 24) and PNGD (see Ch. 93) as well as a number of cutaneous side effects from medications used to treat the arthritis (see Table 53.1). In RA patients receiving methotrexate, EBV-associated lymphoproliferative disease may involve the skin.

Pathology Rheumatoid nodules are typically located in the deep dermis or subcutis and are composed of a central zone of brightly eosinophilic fibrin surrounded by a palisaded layer of histiocytes and granulation tissue (Fig. 45.9). Acute or early lesions may show leukocytoclastic vasculitis and/ or an interstitial neutrophilic infiltrate. The histologic findings of PG, Sweet syndrome, and small, mediumsized and large vessel vasculitis are discussed in Chapters 24 and 26. When rheumatoid vasculitis affects medium-sized vessels, it can be histologically indistinguishable from polyarteritis nodosa. Direct immunofluorescence in rheumatoid vasculitis shows prominent deposition of IgM as well as C3 in small and medium-sized vessels, whereas in polyarteritis nodosa the IgM and C3 vascular deposits are weaker and sparse and limited to medium-sized vessels.

Differential Diagnosis

734

Although rheumatoid nodules share several histologic features with PNGD, in the latter the clinical lesions are more polymorphous, with papules and plaques rather than periarticular skin-colored nodules. Because both the clinical and histologic findings can be similar, subcutaneous granuloma annulare may be misdiagnosed as rheumatoid nodules. However, individuals with subcutaneous granuloma annulare are otherwise healthy and are usually children. Occasionally, gouty tophi may be mistaken clinically for rheumatoid nodules. The differential diagnosis of cutaneous vasculitis is discussed in detail in Chapter 24. Specifically, rheumatoid vasculitis may be confused with mixed cryoglobulinemia given the presence of arthritis, RF, and complement activation in both entities. However, in the former the titer of RF is significantly higher and levels of both C3 and C4 are decreased, whereas in cryoglobulinemia C4 levels are low with relatively normal levels of C3. Bywaters lesions may resemble septic emboli, traumatic lesions and, less often, pernio.

B

Fig. 45.9 Rheumatoid nodule – histiologic features. A Large, irregular area of necrobiosis surrounded by a palisade of histiocytes. B Details of necrobiosis and palisade of histiocytes with elongated nuclei. Courtesy, Lorenzo Cerroni, MD.  

As previously mentioned, rheumatoid neutrophilic dermatitis strongly resembles Sweet syndrome, but could also be mistaken for urticaria or urticarial vasculitis. Ulcerations in RA and Felty syndrome may have a variety of causes, including PG, rheumatoid vasculitis, superficial ulcerating rheumatoid necrobiosis (see Ch. 53) and secondary antiphospholipid syndrome, as well as infections (especially in patients receiving immunosuppressives), lymphoma (particularly angiocentric variants), and thromboembolic disorders. The evaluation of a patient with the histologic finding of palisaded necrotizing granulomas and a suspected rheumatologic disorder is outlined in Fig. 45.10.

Treatment RA therapy is aimed at improving symptoms and preventing end-organ damage. Some of the cutaneous manifestations may improve with treatment of the joint disease, while others (e.g. rheumatoid nodules) often persist. Rheumatoid nodules can be excised, but recurrence is common. Intralesional corticosteroid injections may decrease the size of the nodules, but do not lead to complete resolution. Rheumatoid neutrophilic dermatitis is treated with oral corticosteroids or antineutrophilic agents such as dapsone or colchicine, while Felty syndrome may be treated with recombinant granulocyte colony-stimulating factor (G-CSF) and/or splenectomy.

EVALUATION OF A PATIENT WITH PALISADED NECROTIZING GRANULOMA AND SUSPECTED RHEUMATOLOGIC DISORDER

Key features

Ulcers, nodules, plaques, papules

■ Monogenic diseases related to aberrant activation of the innate immune system that are characterized by recurrent fevers and flares of multi-organ inflammation; the skin is frequently involved as are the joints, eyes and serosae ■ This group includes the hereditary periodic fever syndromes, deficiency of the interleukin (IL)-1 receptor antagonist (DIRA), pustular psoriasis due to abnormal IL-36 or CARD14 signaling, and interferonopathies ■ The cutaneous lesions vary from evanescent urticarial papules and sterile pustules to pyoderma gangrenosum and pernio-like lesions ■ Increased production of IL-1 via inflammasomes can be seen and several of these entities respond to IL-1 antagonists, e.g. anakinra, rilonacept, canakinumab ■ Complex disorders such as Schnitzler syndrome, systemic-onset juvenile idiopathic arthritis (Still disease), and lupus erythematosus share mechanistic and clinical features

Skin biopsy

Palisaded necrotizing granuloma

Basophilic collagen degeneration

Neutrophildominant

ANCA

Eosinophildominant

Eosinophilic collagen degeneration

Eosinophildominant

Consider eosinophilic granulomatosis with polyangiitis

Neutrophildominant

Rheumatoid factor

+ + c-ANCA

Most likely granulomatosis with polyangiitis

+ P-ANCA or negative

Rheumatoid nodule

Consider palisaded neutrophilic and granulomatous dermatitis in association with AI-CTD (e.g. rheumatoid arthritis) or vasculitis

− Jones criteria

+ Rheumatic fever nodule

Fig. 45.10 Evaluation of a patient with palisaded necrotizing granuloma and suspected rheumatologic disorder. Jones criteria for rheumatic fever are reviewed in Chapter 19. AI-CTD, autoimmune connective tissue disease.  

Rheumatoid vasculitis involving medium-sized and large vessels requires aggressive treatment as it can be rapidly progressive and lifethreatening. Intravenous methylprednisolone (500–1500 mg/day for 3 days) followed by prednisone (1 mg/kg/day) plus cyclophosphamide (daily or monthly) and plasmapheresis should be considered. In less severe cases, including the small vessel variant of rheumatoid vasculitis, azathioprine and mycophenolate mofetil may be considered; methotrexate does not have a consistent effect in this complication of RA. Although there are reports of vasculitis developing in patients with RA after the initiation of TNF-α inhibitors, there are also multiple reports documenting the beneficial effects of this class of drugs in the treatment of rheumatoid vasculitis50,52. Several reports have also documented improvement in rheumatoid vasculitis after rituximab therapy50,52. Recurrences of rheumatoid vasculitis are less likely to occur when a stable, long-term regimen re-establishes control of the underlying RA. For the treatment of RA-associated PG, systemic corticosteroids and cyclosporine are highly effective. Excellent results have also been reported with TNF-α inhibitors. Additional treatments are reviewed in Chapter 26. Treatment of the inflammatory arthritis consists of NSAIDs, lowdose systemic corticosteroids, disease-modifying antirheumatic drugs (e.g. hydroxychloroquine, leflunomide, methotrexate, sulfasalazine), and biologic immunomodulators (e.g. TNF inhibitors, abatacept, tocilizumab).

Autoinflammatory diseases encompass the monogenic inflammatory diseases that reflect aberrant activation of the innate immune system53, in contrast to autoimmune diseases where there is dysregulation of the adaptive immune system with formation of autoantibodies and T-cellmediated tissue damage. That said, some degree of autoimmunity or immune deficiency can be seen in autoinflammatory diseases54. As a group, autoinflammatory diseases are characterized by recurrent fevers and flares of multi-organ inflammation. These episodes are seemingly unprovoked and frequently involve the skin as well as the joints, eyes and serosae. Oftentimes, these tissues contain sterile infiltrates of neutrophils. The cutaneous findings vary and include sterile pustules, transient urticarial papules, ulcerations, livedo reticularis, and pernio-like lesions (Table 45.6; see Table 45.2)53. It is important to appreciate the significant overlap these rare disorders have with more common polygenic disorders such as pustular psoriasis and chilblains. Their inclusion in the differential diagnosis, especially in early-onset or treatment-resistant disease, often allows for more specific therapy to be instituted. Table 45.7 outlines the key features, in particular dermatologic, of several monogenic autoinflammatory diseases. The genetic basis of a number of these entities has only been described in the past few years so these diseases may not yet be that familiar to dermatologists. Of note, the pathophysiology of a significant percentage of the disorders in Table 45.6, as well as the cryopyrin-associated periodic syndromes (CAPS; see Table 45.2), involves interleukin (IL)-1 overactivity. There can be excessive production (e.g. CAPS) or defective inhibition (e.g. DIRA) of IL-1 (Fig. 45.12). This provides an explanation for the therapeutic efficacy of IL-1 antagonists, including anakinra, rilonacept, and canakinumab (Fig. 45.13). Histologically, the cutaneous infiltrates in patients can vary from granulomas within the dermis (Blau syndrome) to pustules within the epidermis (DIRA, CARD14-induced pustular psoriasis). A characteristic finding in patients with the hereditary periodic fever syndromes (see Table 45.2) has been termed “neutrophilic urticarial dermatosis”; biopsy specimens of transient urticarial papules demonstrate perivascular and interstitial infiltrates of neutrophils within the dermis10. Leukocytoclasia can be present, but not fibrinoid degeneration of vessel walls. As outlined in Table 45.6, neutrophilic urticarial dermatosis is also observed in patients with complex disorders such as Schnitzler syndrome (see Ch. 18), sJIA or adult-onset Still disease (see above), as well as some patients with SLE55,56. The group of autoinflammatory diseases continues to expand and some of the disorders classically categorized as neutrophilic dermatoses, e.g. Behçet disease, are beginning to be viewed as having a similar pathophysiology.

CHAPTER

45 Other Rheumatologic Disorders and Autoinflammatory Diseases

AUTOINFLAMMATORY DISEASES

Acknowledgment The authors would like to acknowledge Jennie T. Clarke, MD, for her contribution to the previous editions of this chapter.

735

SECTION

Rheumatologic Dermatology

7

RANGE OF CUTANEOUS FINDINGS IN INHERITED AUTOINFLAMMATORY DISEASES

Sporadic or complex disorders with similar findings

Cutaneous and histologic features

Inherited autoinflammatory disease(s)

Evanescent maculopapular/urticarial eruption, often with a neutrophilic infiltrate within the dermis (neutrophilic urticarial dermatosis)

CAPS

Ulcerations, with a sterile neutrophilic infiltrate within the dermis* (pyoderma gangrenosum)

PAPA syndrome**

Pyoderma gangrenosum – idiopathic and in the setting of associated disorders (e.g. ulcerative colitis) (Ch. 26)

Pustules (sterile)

DIRA DITRA PAPA syndrome** CAMPS

Generalized pustular psoriasis Impetigo herpetiformis SAPHO syndrome (Ch. 26) Acne fulminans

Edematous plaques, with a neutrophilic infiltrate within the dermis

Majeed syndrome

Sweet syndrome – idiopathic or occurring in the setting of associated disorders (e.g. acute myelogenous leukemia) (Ch. 26)

Livedo racemosa with nodules

ADA2 deficiency

Sneddon syndrome Sporadic polyarteritis nodosa

Violaceous plaques that resemble pernio, cutaneous lupus erythematosus or dermatomyositis; periorbital edema & erythema

Proteasome-associated autoinflammatory syndrome/CANDLE syndrome/Nakajo– Nishimura syndrome

Lupus erythematosus Dermatomyositis

Schnitzler syndrome (Ch. 18) Adult-onset Still disease • Systemic-onset juvenile idiopathic arthritis (sJIA; Still disease) • •

*Untreated lesion. **PASH (pyoderma gangrenosum, acne, and suppurative hidradenitis) and PAPASH (pyogenic arthritis, pyoderma gangrenosum, acne, and suppurative hidradenitis) syndromes are considered variants of PAPA syndrome; a monogenic basis for PASH and PAPASH syndromes has not been clearly established at the time of writing.

Table 45.6 Range of cutaneous findings in inherited autoinflammatory diseases. Disorders discussed in this chapter are in italics. See Tables 45.2 and 45.7 for details of inherited autoinflammatory diseases. ADA, adenosine deaminase; CAMPS, CARD-14-mediated pustular psoriasis; CANDLE, chronic atypical neutrophilic dermatosis with lipodystrophy and elevated temperature; CAPS, cryopyrin-associated periodic syndrome; DIRA, deficiency of interleukin-1 receptor antagonist; DITRA, deficiency of interleukin-36 receptor antagonist; PAPA, pyogenic arthritis, pyoderma gangrenosum, and acne; SAPHO, synovitis, acne, pustulosis, hyperostosis, osteitis.  

EXAMPLES OF INHERITED AUTOINFLAMMATORY DISEASES WITH CUTANEOUS MANIFESTATIONS

Disease

Protein product of mutated gene (gene)

DIRA (deficiency of interleukin-1 receptor antagonist)

Mode of inheritance

Predominant ethnic group(s)

Age of onset

Clinical features

Treatment

Interleukin [IL]-1 receptor antagonist (IL1RN)

AR

Puerto Rican, Brazilian, Lebanese, Newfoundlanders, Dutch

Neonatal

Pustules within areas of erythema – appearance similar to pustular psoriasis (Fig. 45.11A) Sterile osteolytic bone lesions Neonatal distress

IL-1 antagonists, e.g. anakinra, rilonacept, canakinumab – often dramatic response

DITRA (deficiency of IL-36 receptor antagonist)*

Interleukin [IL]-36 receptor antagonist (IL36RN)

AR

Tunisian, Lebanese

Childhood to adulthood; can flare with pregnancy

Pustules within areas of erythema – resembles generalized pustular psoriasis (Fig. 45.11B)

Retinoids IL-1 antagonists – pustules may respond better than papulosquamous lesions Secukinumab

CAMPS (CARD14mediated pustular psoriasis)*

Caspase-recruitment domain-containing [CARD], member 14 (CARD14)

AD

Caucasian

Early childhood

Generalized pustular psoriasis CARD14 mutations also occur in familial (AD) pityriasis rubra pilaris CARD14 is a psoriasis susceptibility gene (PSORS2)

Not known

*Other monogenic autoinflammatory variants of pustular psoriasis have been reported, related to mutations in AP1S3. 736

Table 45.7 Examples of inherited autoinflammatory diseases with cutaneous manifestations. The classic hereditary periodic fever syndromes are outlined in Table 45.2. Most of these disorders are also characterized by recurrent fevers and elevations in acute phase reactants.  

CHAPTER

Disease

Protein product of mutated gene (gene)

ADAM17 deletion/ neonatal-onset inflammatory skin and bowel disease

Mode of inheritance

Predominant ethnic group(s)

Age of onset

Clinical features

Treatment

ADAM metallopeptidase domain 17 (ADAM17)

AR

Not known

Neonatal

Psoriasiform erythroderma and widespread pustules Short hair, wiry eyelashes & eyebrows Onychauxis, paronychia Diarrhea, often bloody; malabsorption

Not known

PAPA (pyogenic arthritis, pyoderma gangrenosum, and acne) syndrome

Proline-serinethreonine phosphataseinteracting protein-1 (PSTPIP1)

AD

Northern European

Childhood

Pyoderma gangrenosum (see Fig. 26.13) Pathergy Severe acne Recurrent, painful, sterile arthritis during early childhood

TNF inhibitors IL-1 antagonists Corticosteroids

IL-10/IL-10R deficiency

Interleukin [IL]-10 (IL10) Interleukin [IL]-10 receptor α & β (IL10RA, IL10RB)

AR

Turkish, Lebanese

Neonatal

Folliculitis, primarily with IL-10R deficiency Severe infantile (very early-onset) enterocolitis

Allogeneic HSCT (case reports)

Blau syndrome (familial juvenile systemic granulomatosis)

Nucleotide-binding oligomerization domain [NOD] containing 2/ Caspase recruitment domain family [CARD], member 15 (NOD2/CARD15)

AD

Not known

Childhood

Numerous tiny papules (Fig. 45.11C) Granulomatous infiltrate in dermis Uveitis Early-onset, symmetric, granulomatous polyarticular arthritis

Corticosteroids TNF inhibitors (e.g. infliximab) MTX, CSA IL-1 antagonists

PLAID (PLCG2associated antibody deficiency and immune dysregulation)

Phospholipase C, γ2 (PLCG2)

AD

Ethnically diverse

Infancy to early childhood

Familial cold autoinflammatory syndrome (FCAS)-3 Cold air-induced/ evaporative cooling-induced urticaria and angioedema Noninfectious cutaneous granulomas in a subset of patients Recurrent infections, antibody deficiency, autoimmunity

Not known

APLAID (Autoinflammation and PLCG2associated antibody deficiency and immune dysregulation)

Phospholipase C, γ2 (PLCG2)

AD

One family to date

Early childhood

Variable presentation, from vesicles that resemble epidermolysis bullosa to erythematous plaques that resemble cellulitis Ocular inflammation Interstitial pneumonitis Enterocolitis Mild immunodeficiency

Difficult to treat

Other Rheumatologic Disorders and Autoinflammatory Diseases

45

EXAMPLES OF INHERITED AUTOINFLAMMATORY DISEASES WITH CUTANEOUS MANIFESTATIONS

Table 45.7 Examples of inherited autoinflammatory diseases with cutaneous manifestations. (cont’d) The classic hereditary periodic fever syndromes are outlined in Table 45.2. Most of these disorders are also characterized by recurrent fevers and elevations in acute phase reactants. CSA, cyclosporine; HSCT, hematopoietic stem cell transplant; MTX, methotrexate. Continued  

737

SECTION

Rheumatologic Dermatology

7

EXAMPLES OF INHERITED AUTOINFLAMMATORY DISEASES WITH CUTANEOUS MANIFESTATIONS

Protein product of mutated gene (gene)

Mode of inheritance

Predominant ethnic group(s)

Age of onset

Clinical features

Treatment

Adenosine deaminase 2 (CECR1)

AR

Georgian Jewish, German, Turkish, Caucasian

Infancy to adulthood

Childhood-onset polyarteritis nodosa Livedo racemosa (Fig. 45.11D) Early-onset strokes Hepatosplenomegaly Hypogammaglobulinemia, lymphopenia

TNF inhibitors Allogeneic HSCT

SAVI (STING [stimulator of interferon genes]associated vasculopathy with onset in infancy)

Transmembrane protein 173 (TMEM173)

AD

European, Turkish

Early infancy

Acral (digits, ears, nose) infarcts, ulcerations, and gangrene Bone resorption with loss of digits, including nails (Fig. 45.11E) Acral violaceous plaques Nasal septum perforation Interstitial lung disease Increased IFN signaling

Minimal or no response to corticosteroids, DMARDs JAK inhibitors

Aicardi–Goutières syndrome (AGS)**/ familial chilblain lupus (FCL)

3’ repair exonuclease 1 (TREX1), SAM- and HD-domaincontaining protein 1 (SAMHD1) for AGS or FCL; adenosine deaminase, RNAspecific (ADAR1), interferon induced with helicase C domain 1 (IFIH1), and ribonuclease H2, subunits A, B or C (RNASEH2A/B/C) for AGS

AR >> AD (AGS) AD (FCL)

Ethnically diverse

Neonatal or infancy (AGS) to childhood (FCL)

Pernio-like lesions on hands, feet and ears (Fig. 45.11F) Arthritis (FCL) Encephalopathy with white matter changes and progressive developmental delay (AGS) Increased IFN signaling

Difficult to treat

Proteosomeassociated autoinflammatory syndrome/CANDLE (chronic atypical neutrophilic dermatosis with lipodystrophy and elevated temperature) syndrome/Nakajo– Nishimura syndrome

Proteasome subunit, beta type, 8 (PSMB8)

AR

Japanese, Spanish, Ashkenazi Jewish, Caucasian

Infancy

Violaceous plaques that can be annular, pernio-like lesions, eyelid edema and erythema Myeloid infiltrate in dermis – varies from immature to mature cells Partial lipomuscular atrophy, joint contractures Basal ganglia calcification (Fig. 45.11G)

No proven effective treatment JAK inhibitors

Disease ADA2 deficiency

Type I interferonopathies

**Also due to mutations in other genes, including ribonuclease H2, subunits A–C (RNASEH2A–C); adenosine deaminase, RNA-specific (ADAR); and interferon-induced with helicase C domain 1 (IFIH1).

Table 45.7 Examples of inherited autoinflammatory diseases with cutaneous manifestations. (cont’d) The classic hereditary periodic fever syndromes are outlined in Table 45.2. Most of these disorders are also characterized by recurrent fevers and elevations in acute phase reactants. DMARDS, disease-modifying antirheumatic drugs; HSCT, hematopoietic stem cell transplant; IFN, interferon; JAK, Janus kinase.  

738

CHAPTER

A

E

D

Fig. 45.11 Cutaneous manifestations of inherited autoinflammatory disorders. A Annular erythematous plaques studded with pustules in an infant with deficiency of the interleukin-1 receptor antagonist (DIRA); note the similarity to pustular psoriasis. B Child with deficiency of interleukin-36 receptor antagonist (DITRA) – widespread psoriasiform plaques whose edges contain pustules. C Blau syndrome with numerous, small, pink-tan, flat papules in a generalized distribution in a 1-year-old boy; histologically, a granulomatous infiltrate is seen. D Livedo racemosa in a patient with adenosine deaminase 2 (ADA2) deficiency. E STING (stimulator of interferon genes)-associated vasculopathy with onset in infancy (SAVI) is characterized by acral violaceous plaques and resorption of digits and loss of nails; patients may be diagnosed as having Aicardi–Goutières syndrome, antiphospholipid antibody syndrome, or vasculitis. F Aicardi– Goutières syndrome with pernio-like lesions. G Chronic atypical neutrophilic dermatosis with lipodystrophy and elevated temperature (CANDLE) syndrome with deforming arthritis (e.g. swan neck deformity) and thin pink plaques overlying the metacarpophalangeal joints that resemble  

B

F

C

G

Other Rheumatologic Disorders and Autoinflammatory Diseases

45

739

SECTION

Rheumatologic Dermatology

7

THE PATHOGENESIS OF DIRA AND DITRA

Deficiency of the interleukin-1 receptor antagonist (DIRA)

A

IL-1R antagonist

Deficiency of the interleukin-36 receptor antagonist (DITRA)

B

IL-36R antagonist

IL-1R1

IL-36R IL-36 IL-36 IL-36

IL-1 IL-1

Signals increased

Signals increased

Fig. 45.12 The pathogenesis of DIRA (deficiency of interleukin-1 receptor [IL-1R] antagonist) and DITRA (deficiency of interleukin-36 receptor [IL-36R] antagonist). A Loss of the IL-1R antagonist leads to unopposed proinflammatory signaling by IL-1α and IL-1β in patients with DIRA. B In DITRA, loss of the IL-36R antagonist results in analogous unchecked signaling by IL-36α, IL-36β, and IL-36γ at the IL-36R. Reproduced from Cowen EW, Goldbach-Mansky R. DIRA, DITRA, and new insights into  

pathways of skin inflammation. What’s in a name? Arch Dermatol. 2012;148:381–4.

INTERLEUKIN (IL)-1 AND IL-1 RECEPTOR ANTAGONISTS – ANAKINRA, RILONACEPT, AND CANAKINUMAB Canakinumab

Anakinra

Fig. 45.13 Interleukin (IL)-1β and IL-1 receptor antagonists – anakinra, rilonacept, and canakinumab. Anakinra is an antagonist of the IL-1 receptor (IL-1R). Rilonacept is an IL-1 Trap. Canakinumab is an anti-IL-1β monoclonal antibody. See Fig. 4.2 for details of NLRP3 inflammasome. NLRP3, NOD-like receptor pyrin domain-containing protein 3.  

IL-1

Rilonacept

IL-1R

NLRP3 inflammasome activation

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41. Tani C, Carli L, Vagnani S, et al. The diagnosis and classification of mixed connective tissue disease. J Autoimmun 2014;48–49:46–9. 42. Yoshida K, Inoue H, Komai K, et al. Mixed connective tissue disease is distinct from systemic lupus erythematosus: study of major histocompatibility complex class I polypeptide-related sequence A and HLA gene polymorphisms. Tissue Antigens 2013;81:44–5. 43. Pope JE. Other manifestations of mixed connective tissue disease. Rheum Dis Clin North Am 2005;31:519–33. 44. Gunnarsson R, Andreassen AK, Molberg Ø, et al. Prevalence of pulmonary hypertension in an unselected, mixed connective tissue disease   cohort: results of a nationwide, Norwegian crosssectional multicentre study and review of current literature. Rheumatology (Oxford) 2013;52:  1208–13. 45. Ungprasert P, Wannarong T, Panichsillapakit T, et al. Cardiac involvement in mixed connective tissue disease: a systematic review. Int J Cardiol 2014;171:326–30. 46. Ortega-Hernandez O-D, Shoenfeld Y. Mixed connective tissue disease: an overview of clinical manifestations, diagnosis and treatment. Best Pract Res Clin Rheumatol 2012;26:61–72. 47. Demoruelle MK, Deane KD, Holers VM. When and where does inflammation begin in rheumatoid arthritis? Curr Opin Rheumatol 2014;26:64–7. 48. Furst DE, Emery P. Rheumatoid arthritis pathophysiology: update on emerging cytokine and cytokine-associated cell targets. Rheumatology (Oxford) 2014;53:1560–9. 49. Goerttler E, Kutzner H, Peter HH, Requena L. Methotrexate-induced papular eruption in patients with rheumatic diseases: a distinctive adverse cutaneous reaction produced by methotrexate in patients with collagen vascular diseases. J Am Acad Dermatol 1999;40:702–7. 50. Radic M, Martinovic Kaliterna D, Radic J. Overview of vasculitis and vasculopathy in rheumatoid arthritis– something to think about. Clin Rheumatol 2013;32:937–42. 51. Sayah A, English JCIII. Rheumatoid arthritis: a review of the cutaneous manifestations. J Am Acad Dermatol 2005;53:191–209. 52. Turesson C, Matteson EL. Vasculitis in rheumatoid arthritis. Curr Opin Rheumatol 2009;21:35–40. 53. Shwin KW, Lee CR, Goldbach-Mansky R. Dermatologic manifestations of monogenic autoinflammatory diseases. Dermatol Clin 2017;35:21–38. 54. Almeida de Jesus A, Goldbach-Mansky R. Monogenic autoinflammatory diseases: concept and clinical manifestations. Clin Immunol 2013;147:155–74. 55. Gusdorf L, Bessis D, Lipsker D. Lupus erythematosus and neutrophilic urticarial dermatosis: a retrospective study of 7 patients. Medicine (Baltimore) 2014;  93:e351. 56. Lipsker D, Saurat J-H. Neutrophilic cutaneous lupus erythematosus. At the edge between innate and acquired immunity? Dermatology 2008;216:  283–6.

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45 Other Rheumatologic Disorders and Autoinflammatory Diseases

receptor antagonist in steroid-naive patients with new-onset systemic juvenile idiopathic arthritis: results of a prospective cohort study. Arthritis Rheumatol 2014;66:1034–43. 14. Ruperto N, Brunner HI, Quartier P, et al. Two randomized trials of canakinumab in systemic juvenile idiopathic arthritis. N Engl J Med 2012;367:2396–406. 15. De Benedetti F, Brunner HI, Ruperto N, et al. Randomized trial of tocilizumab in systemic juvenile idiopathic arthritis. N Engl J Med 2012;367:2385–95. 16. Efthimiou P, Georgy S. Pathogenesis and management of adult-onset Still’s disease. Semin Arthritis Rheum 2006;36:144–52. 17. Lee JY, Yang CC, Hsu MM. Histopathology of persistent papules and plaques in adult-onset Still’s disease. J Am Acad Dermatol 2005;52:1003–8. 18. Ciliberto H, Kumar MG, Musiek A. Flagellate erythema in a patient with fever. JAMA Dermatol 2013;149:1425–6. 19. Lipsker D. The Schnitzler syndrome. Orphanet J Rare Dis 2010;5:38. 20. Giampietro C, Ridene M, Lequerre T, et al. Anakinra in adult-onset Still’s disease: long-term treatment in patients resistant to conventional therapy. Arthritis Care Res (Hoboken) 2013;65:822–6. 21. Ortiz-Sanjuán F, Blanco R, Calvo-Rio V, et al. Efficacy of tocilizumab in conventional treatment-refractory adult-onset Still’s disease: multicenter retrospective open-label study of thirty-four patients. Arthritis Rheumatol 2014;66:1659–65. 21a.  Belfeki N, Smiti Khanfir M, Said F, et al. Successful treatment of refractory adult onset Still’s disease with rituximab. Reumatismo 2016;68:159–62. 22. Arnaud L, Mathian A, Haroche J, et al. Pathogenesis of relapsing polychondritis: a 2013 update. Autoimmun Rev 2014;13:90–5. 23. Letko E, Zafirakis P, Baltatzis A, et al. Relapsing polychondritis: a clinical review. Semin Arthritis Rheum 2002;31:384–95. 24. Frances C, el Rassi R, Laporte JL, et al. Dermatologic manifestations of relapsing polychondritis. A study of 200 cases at a single center. Medicine (Baltimore) 2001;80:173–9. 25. Firestein GS, Gruber HE, Weisman MH, et al. Mouth and genital ulcers with inflamed cartilage: MAGIC syndrome. Am J Med 1985;79:65–72. 26. Stael R, Smith V, Wittoek R, et al. Sustained response to tocilizumab in a patient with relapsing polychondritis with aortic involvement: a case based review. Clin Rheumatol 2015;34:189–93. 26a.  Mathian A, Miyara M, Cohen-Aubart F, et al. Relapsing polychondritis: A 2016 update on clinical features, diagnostic tools, treatment and biological drug   use. Best Pract Res Clin Rheumatol 2016;30:  316–33. 27. Shiboski CH, Shiboski SC, Seror R, et al; International Sjögren’s Syndrome Criteria Working Group. 2016 American College of Rheumatology/European League Against Rheumatism classification criteria for primary Sjögren’s syndrome: A consensus and data-driven methodology involving three international patient cohorts. Ann Rheum Dis 2017;76:9–16. 27a.  Daniels TE, Cox D, Shiboski CH, et al. Associations between salivary gland histopathologic diagnoses and

741

SECTION 8 METABOLIC AND SYSTEMIC DISEASES

46 

Mucinoses Franco Rongioletti

Key features ■ The cutaneous mucinoses are a heterogeneous group of disorders in which an abnormal amount of mucin accumulates in the skin ■ The etiopathogenesis of cutaneous mucinoses is unknown ■ The cutaneous mucinoses are divided into two groups: (1) primary cutaneous mucinoses, in which the mucin deposition leads to clinically distinctive lesions and is the major histologic feature; and (2) secondary mucinoses, in which the mucin deposition is simply an associated finding ■ Primary cutaneous mucinoses are further divided into degenerative–inflammatory forms (which may be dermal or follicular) and hamartomatous–neoplastic forms ■ Associated disorders include paraproteinemia (scleromyxedema, scleredema), diabetes mellitus (scleredema), thyroid disease (pretibial myxedema, myxedema) and autoimmune connective tissue disease (lupus erythematosus, dermatomyositis)

STAINING CHARACTERISTICS OF ACID GLYCOSAMINOGLYCANS (MUCOPOLYSACCHARIDES)

Histologic stain

Acid glycosaminoglycans (mucopolysaccharides) Non-sulfated (hyaluronic acid*)

Colloidal iron



Alcian blue pH 2.5 pH 0.5

⊕ ⊖

⊕ ⊕

⊕ ⊖ ⊖ ⊕

⊕ ⊕ ⊖ ⊖

Metachromasia with toluidine blue pH 4.0 pH 85% of disease-causing mutations59. In both recessive and dominantly inherited conditions, WES followed by bioinformatics analysis has emerged as a more efficient and cost-effective approach than WGS for identifying disease-causing mutations60. For traits with known linkage information and/or candidate genes, massively parallel sequencing can also be used to find variants in the candidate region/genes61,62. Strategies for the utilization of massively parallel sequencing to identify pathogenic mutations in Mendelian and complex genetic disorders are outlined in Table 54.6. Analytical tools have been developed to systematically integrate information from WES/WGS with data on copy number variation and LOH, enabling a robust survey of the genetic landscape. These new sequencing and analytic tools are helping to provide a comprehensive catalog of clinically relevant genes and pathways and their disruption in genetic diseases. Single-cell analysis via WGS/WES is increasingly being used to obtain insights into cellular heterogeneity, signaling events, and stochastic gene expression variability within an individual. Whole-genome amplification methods have recently been developed to optimize single-cell analysis, and studies have begun to integrate sequence results (e.g. single nucleotide and copy number variations) and expression-based data (e.g. RNA sequencing) from a single cell63–68.

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54 Basic Principles of Genetics

subset of patients is helpful, but such additional information is usually not available. For most genetic diseases, narrowing the linkage interval requires increasing the number of individuals, recombination events, and/or markers studied. When several close markers are analyzed, the disease gene is then linked to a certain haplotype rather than a single marker. The goal is to identify the boundaries of the smallest possible interval, defined by the closest markers that show recombination with the disease phenotype. Recombination events can “break” the shared haplotype in different members/generations of the pedigree. Identification of an individual in whom recombination has occurred inside the disease-associated haplotype, known as a key recombination event, reduces the region where the disease gene is presumed to be located (Fig. 54.6B). By identifying different key recombination events, the linkage interval can be progressively narrowed. A linkage interval that cannot be further reduced is considered to be the candidate region that co-segregates with the disease phenotype and contains the actual disease gene. Sequencing and genotyping-based methods can be used in conjunction with haplotype analysis to identify potentially pathogenic genetic variants within the candidate region. In the case of autosomal recessive traits caused by rare alleles, homozygosity or autozygosity mapping using SNPs as markers can be used to define regions of homozygosity. Overlaying these identical-by-descent regions with linkage peaks can help to identify candidate genes.

Genome-Wide Association Studies (GWAS) The goal in the study of complex traits is the identification of DNA variants in multiple different genes, each with a contribution to the final phenotype and conferring a degree of susceptibility to the carrier. Until recently, the identification of genetic variants contributing to complex traits was slow and challenging. However, the characterization of normal human genome variation and development of microarraybased technologies now enable genome-wide association studies (GWAS) in which several hundred thousand SNPs can be analyzed in thousands of individuals to determine the genetic architecture of complex diseases. The steps involved in GWAS are depicted in Fig. 54.769.

855

GENOME-WIDE ASSOCIATION STUDY

SECTION

B SNP1

Chromosome 9

SNP2 Person 1

Genodermatoses

9

A

Control DNA

Person 2

Patient DNA

Person 3

Compare

G-C → T-A Disease associated SNPs

A-T→ G-C

Non-disease associated SNPs

C

SNP1 Initial discovery study P=1x10-12

Cases

Common homozygote

Heterozygote

Controls

SNP2 Initial discovery study P=1x10-8

Cases

Controls

Variant homozygote

14

14

12

12

10

10

-Log10 P Value

-Log10 P Value

D

8 6

SNP1

SNP2

8 6

4

4

2

2 0

0 0

1

2

3

4

5

6

7 8 9 10 11 12 13 14 15 17 19 21 X Chromosome 16 18 20 22

Position of chromosome 9

Fig. 54.7 Genome-wide association study (GWAS). A In a GWAS with a case–control design, single nucleotide polymorphisms (SNPs; markers of genetic variation) across the human genome are genotyped using DNA microarrays in a large group of individuals with a certain disease and compared to controls from the general population. B A small locus on chromosome 9 (representing a tiny fragment of the genome) containing two SNPs is depicted as an example. C The strength of the association between each SNP and the disease is calculated based on that SNP’s prevalence in cases versus controls. Because of the large number of statistical tests that are performed and the resulting high false-positive rate, statistical significance is typically set a P value of 10−8. In this example, SNPs 1 and 2 on chromosome 9 are associated with the disease, with P values of 10−12 and 10−8, respectively. D For all genotyped SNPs that have survived a quality-control screen, the chromosomal location is plotted on the x-axis and the negative logarithm of the P value on the y-axis (a Manhattan plot). Each chromosome is shown in a different color. The results implicate a locus on chromosome 9, marked by SNPs 1 and 2, which are adjacent to each other (graph at right), and other neighboring SNPs.  

Adapted with permission from Manolio TA. Genomewide association studies and assessment of the risk of disease. N Engl J Med. 2010;363:166–76.

856

Although useful and extremely popular, GWAS pose significant challenges, primarily related to selecting a disease suitable for analysis and obtaining a large sample size of both cases and controls. A successful investigation requires that the phenotype of interest can be sensitively and specifically diagnosed or measured. Furthermore, extremely large

collections of patients need to be studied to identify a statistically significant contribution for a given genetic factor. The rationale for GWAS is that common diseases are attributable to common allelic variants present in more than 1–5% of the population70. With a few exceptions (e.g. age-related macular degeneration) in

syndrome, an autosomal recessive ichthyosiform disorder with atopic manifestations83. A significant association has been observed between a particular SPINK5 variant (Glu420Lys) and atopic dermatitis83, providing additional insights into the pathogenesis of this complex disorder. Many genomic regions strongly associated with complex traits such as autoimmune diseases lie outside of genes (intergenic), presumably within regulatory regions84,85. After demonstrating an association, the next step is to determine what genetic variants are in linkage disequilibrium (i.e. have a non-random association) with the tagged SNP. Targeted deep sequencing can be utilized to identify rare and common variants within a particular region of genetic association, e.g. based on linkage disequilibrium peaks. To prioritize biologically relevant loci for targeted deep sequencing, data obtained from other investigations can be utilized. These sources include family-based studies (e.g. linkage, whole-exome, CNV analysis), gene expression studies (e.g. microarrays, RNA sequencing), and mouse models of the disease phenotype. Allele frequencies for genetic variants in affected individuals can be compared to healthy cohorts as well as to the general population using public genome databases.

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54 Basic Principles of Genetics

which heritability is explained by a small number of common variants with a large effect, the proportion of heritability explained by the identified variants is typically relatively small (e.g. 20%)70. The “missing heritability” is thought to be explained by large numbers of variants with small effects, rare variants, structural variants such as copy number alterations, gene–gene interactions, and the role of the shared environment among relatives. Examples of GWAS of dermatologic conditions include those investigating susceptibility to psoriasis, atopic dermatitis, vitiligo, alopecia areata, melanocytic nevi, melanoma, and basal cell carcinoma as well as physiologic variation in pigmentation of the skin and hair71–79. Studies of psoriasis have revealed several susceptibility loci, including major histocompatibility complex (MHC) and late cornified envelope gene clusters as well as genes involved in interleukin, tumor necrosis factor, and nuclear factor-κB signaling (see Ch. 8)77,78. GWAS in patients with alopecia areata have implicated genes involved in innate and adaptive immunity such as those controlling activation of cytotoxic and regulatory T cells, as well as genes expressed specifically in the hair follicle79. These results were validated in subsequent functional studies and mouse models, which led to the development of targeted therapeutic interventions via inhibition of Janus kinase (JAK) signaling downstream of interferon-γ receptors80. Skin and hair pigmentation have been linked to variants in the melanocortin 1 receptor (MC1R), tyrosinase (TYR), two-pore segment channel 2 (TPCN2), solute carrier family 24 member 4 (SLC24A4), agouti signaling protein (ASIP), and Kit ligand (KITLG)72. Several of these loci (e.g. MC1R, TYR, ASIP) have also been associated with melanoma susceptibility73,75. In addition to GWAS, the knowledge gathered from Mendelian disorders has provided important clues to the etiology of more common related complex traits. As an example, loss-of-function mutations in the filaggrin gene (FLG) were first identified in patients with ichthyosis vulgaris, who also have a high incidence of atopic dermatitis81,82. The same loss-of-function alleles in FLG were subsequently found to represent a strong predisposing factor for atopic dermatitis, with at least one allele present in 20–50% of affected children and adults in European and Asian populations81. Another gene associated with atopic dermatitis is SPINK5; loss-of-function mutations cause Netherton

Functional Genomics Functional genomics can be utilized to clarify the relationships between genotype and phenotype by integrating genetic/mutational analyses with functional and regulatory information on gene transcription, translation, and protein–protein interactions. Multiple variants and their interactions can be studied simultaneously in a high-throughput manner rather than via a candidate-by-candidate approach. WGS and targeted deep sequencing provide comprehensive polymorphism and mutation discovery in human genomes, while transcriptome sequencing provides information on gene expression, splicing, and somatic mutations86. Genome-wide mapping of protein–DNA interactions can be achieved using chromatin immunoprecipitation sequencing (ChIPseq), and sequencing of bisulfite-treated DNA can be utilized to study methylation patterns at a given disease locus87. Bioinformatics analysis coupled with computational biology tools can be used to integrate this information and enable downstream analysis.

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33. SECTION

Genodermatoses

9

34. 35.

36.

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48. 49.

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50. Frazer KA, Ballinger DG, Cox DR, et al. A second generation human haplotype map of over 3.1 million SNPs. Nature 2007;449:851–61. 51. Lander ES, Linton LM, Birren B, et al. Initial sequencing and analysis of the human genome. Nature 2001;409:860–921. 52. Bashir R, Munro CS, Mason S, et al. Localisation of a gene for Darier’s disease. Hum Mol Genet 1993;2:1937–9. 53. Craddock N, Dawson E, Burge S, et al. The gene for Darier’s disease maps to chromosome 12q23-q24.1. Hum Mol Genet 1993;2:1941–3. 54. Ikeda S, Welsh EA, Peluso AM, et al. Localization of the gene whose mutations underlie Hailey-Hailey disease to chromosome 3q. Hum Mol Genet 1994;3:1147–50. 55. Hu Z, Bonifas JM, Beech J, et al. Mutations in ATP2C1, encoding a calcium pump, cause Hailey-Hailey disease. Nat Genet 2000;24:61–5. 56. Liu L, Li Y, Li S, et al. Comparison of next-generation sequencing systems. J Biomed Biotechnol 2012;2012:251364. 57. Metzker ML. Sequencing technologies – the next generation. Nat Rev Genet 2010;11:31–46. 58. Wei X, Walia V, Lin JC, et al. Exome sequencing identifies GRIN2A as frequently mutated in melanoma. Nat Genet 2011;43:442–6. 59. Gilissen C, Hoischen A, Brunner HG, Veltman JA. Disease gene identification strategies for exome sequencing. Eur J Hum Genet 2012;20:490–7. 60. Lelieveld SH, Veltman JA, Gilissen C. Novel bioinformatic developments for exome sequencing. Hum Genet 2016;135:603–14. 61. Cirulli ET, Goldstein DB. Uncovering the roles of rare variants in common disease through whole-genome sequencing. Nat Rev Genet 2010;11:415–25. 62. Lai-Cheong JE, McGrath JA. Next-generation diagnostics for inherited skin disorders. J Invest Dermatol 2010;131:1971–3. 63. Baslan T, Hicks J. Single cell sequencing approaches for complex biological systems. Curr Opin Genet Dev 2014;26:59–65. 64. Navin N, Kendall J, Troge J, et al. Tumour evolution inferred by single-cell sequencing. Nature 2011;472:90–4. 65. Junker JP, van Oudenaarden A. Every cell is special: genome-wide studies add a new dimension to single-cell biology. Cell 2014;157:8–11. 66. Trombetta JJ, Gennert D, Lu D, et al. Preparation of Single-Cell RNA-Seq Libraries for Next Generation Sequencing. Curr Protoc Mol Biol 2014;107:4.22.1–17. 67. Zong C, Lu S, Chapman AR, Xie XS. Genome-wide detection of single-nucleotide and copy-number variations of a single human cell. Science 2012;338:1622–6. 68. Borgström E, Paterlini M, Mold JE, et al. Comparison of whole genome amplification techniques for human single cell exome sequencing. PLoS ONE 2017;12:e0171566. 69. Hardy J, Singleton A. Genomewide association studies and human disease. N Engl J Med 2009;360:1759–68. 70. Manolio TA, Collins FS, Cox NJ, et al. Finding the missing heritability of complex diseases. Nature 2009;461:747–53. 71. Birlea SA, Gowan K, Fain PR, et al. Genome-wide association study of generalized vitiligo in an isolated European founder population identifies SMOC2, in

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GENODERMATOSES SECTION 9

Genetic Basis of Cutaneous Diseases Vered Molho-Pessach and Julie V. Schaffer

Key features ■ Advances in molecular technology have led to elucidation of the genetic bases of many single-gene inherited and mosaic skin disorders, greatly improving our understanding of these conditions ■ McKusick’s Online Mendelian Inheritance in Man (OMIM) database provides easily accessible, up-to-date information on human genes and genetic diseases; each gene or phenotype entry is assigned a specific six-digit MIM number ■ Genotype–phenotype correlations in genodermatoses are often complex, with multiple examples of allelic heterogeneity (mutations in a single gene causing more than one disorder) and locus heterogeneity (mutations in different genes causing the same disorder) ■ Molecular classification of genodermatoses into categories such as keratin defects and RASopathies complements traditional morphologic classification, highlighting pathomechanisms and relationships between conditions ■ Certain syndromic associations actually represent contiguous gene syndromes caused by large deletions that affect two or more neighboring genes ■ Types 1 and 2 mosaicism in autosomal dominant disorders have been confirmed on a molecular level, and functional X-chromosome mosaicism can lead to a mosaic distribution of skin lesions in female patients heterozygous for X-linked disorders ■ Determining the molecular basis of monogenic skin disorders can enable the development of targeted therapies and provide insights into the pathogenesis of acquired skin disease ■ Molecular research has begun to pave the way to the ultimate goal of gene therapy for severe inherited skin disorders such as epidermolysis bullosa

Abbreviations:  AD, autosomal dominant; AR, autosomal recessive; XD, X-linked dominant; XR, X-linked recessive.

INTRODUCTION In 1987, deletions in the steroid sulfatase gene were found to underlie X-linked recessive ichthyosis1. This heralded an era of tremendous progress in the elucidation of the genetic bases of inherited skin disorders, made possible by rapid advances in molecular technology (including the development of next-generation massively parallel sequencing), discovery of candidate genes, utilization of animal models, and sequencing of the human genome, including single nucleotide polymorphisms (SNPs) useful for linkage analysis and homozygosity mapping (see Ch. 54)2–4. Better understanding of signaling pathways, molecules involved in cell–cell communication and adhesion, and mechanisms of cutaneous differentiation have also contributed to the momentum. As a result of this explosion in research, more than 1000 genes were recognized to be responsible for a particular human phenotype by the year 2000, with approximately 300 of these conditions including cutaneous abnormalities5; by 2017, these numbers had increased to nearly 3800 and 1400, respectively6–8. Currently, the molecular genetic bases

55 

of the majority of single-gene inherited skin disorders have been established9,10. The emergence of new genomic and proteomic databases has transformed laborious positional cloning approaches and traditional functional studies, circumventing previous obstacles to the study of rare conditions and facilitating identification of candidate genes. For example, microarray (see Ch. 3)-based SNP genotyping enabled the identification of ABCA12 mutations as the cause of harlequin ichthyosis; although classic linkage analysis was not possible due to the limited size of the pedigrees, homozygosity mapping (utilizing the aforementioned technology) linked this autosomal recessive condition to a region of homozygosity shared by affected individuals from diverse ethnic backgrounds11. With whole-exome (the transcribed portion of the genome) and whole-genome sequencing now feasible and relatively affordable, disease-causing genes can potentially be identified without genetic mapping10. In the past, diagnosis of genodermatoses was complicated by the existence of multiple complex classification systems based on various combinations of clinical, histologic, radiographic, and biochemical criteria. Inconsistent nomenclature laden with descriptive terms, eponyms, and synonyms added to the confusion and potential for misdiagnosis12. As the genetic bases of genodermatoses have been determined, integration of molecular and clinical data has helped to simplify disease categorization and eliminate redundant terminology. This has been successfully accomplished for disorders such as epidermolysis bullosa (EB) and ichthyoses, but it represents a work in progress, to be continually refined as additional genotype–phenotype correlations are established13,14. In addition, grouping hereditary skin disorders according to their molecular bases (Table 55.1) can supplement traditional morphologic classification, clarifying pathomechanisms and the relationships between conditions. As the “morbid anatomy of the dermatologic genome” continues to be established, new challenges will arise and additional questions will be answered15. Because of the rarity of many genodermatoses, their full clinical spectra have yet to be elucidated. However, with the increasing availability of genetic and biochemical testing (www.genetests.org), dermatologists can establish the diagnosis in patients with mild or atypical presentations, thereby expanding the range of phenotypes. Continuing to decipher heritable skin disorders will require close interactions between basic scientists and clinicians15a. Hopefully, such translational research will continue to lead to better understanding of cutaneous structure and function; insights into the pathogenesis of common multifactorial disorders; and effective therapies as well as diagnostic and prognostic information, improved genetic counseling and DNA-based prenatal/preimplantation testing for patients with genodermatoses. In this chapter, Tables 55.3 to 55.8 divide selected monogenic skin disorders with a known genetic basis into categories according to their primary clinical features. Groups of monogenic conditions similarly listed in tables elsewhere in the book are noted in Table 55.2.

MCKUSICK’S MENDELIAN INHERITANCE IN MAN McKusick’s Mendelian Inheritance in Man (MIM) database was first published in 1966 as “Catalogs of Autosomal Dominant, Autosomal Recessive and X-linked Phenotypes”. In the 1994 edition, the subtitle was changed to “A Catalog of Human Genes and Genetic Disorders”, reflecting the progress that had been made in the field. Online MIM (OMIM; https://omim.org/) has been widely available on the Internet for over 30 years, providing immediate access to current information on human genes and genetic diseases6,7. This database is updated continuously and can be searched by entering a constellation of clinical features as well as the name of a gene or syndrome.

859

Advances in molecular technology have led to elucidation of the genetic bases of many single-gene inherited and mosaic skin disorders, greatly improving our understanding of these conditions. Genotype–phenotype correlations in genodermatoses are often complex, with multiple examples of allelic and locus heterogeneity. Molecular classification of genodermatoses into categories such as keratin defects and RASopathies complements traditional morphologic classification, highlighting pathomechanisms and relationships between conditions. Determining the molecular basis of monogenic skin disorders can enable the development of targeted therapies and provide insights into the pathogenesis of acquired skin diseases.

genodermatoses, genotype, phenotype, molecular classification, contiguous gene syndromes, mosaicism, revertant mosaicism, chromosomal disorders, prenatal diagnosis

CHAPTER

55 Genetic Basis of Cutaneous Diseases

ABSTRACT

non-print metadata KEYWORDS

859.e1

MOLECULAR CLASSIFICATION OF GENETIC SKIN DISORDERS

SECTION

Genodermatoses

9

Molecular defect

Examples of skin disorders that result

Keratin defects

See Table 56.4 and Fig. 56.5

Defects in structural proteins of the cornified cell envelope

Ichthyosis vulgaris, loricrin keratoderma (variant Vohwinkel syndrome)

Lipid metabolism defects

Various ichthyoses, including CHILD syndrome, Conradi–Hünermann–Happle syndrome, neutral lipid storage disease, lamellar ichthyosis/congenital ichthyosiform erythroderma spectrum (e.g. defective lipoxygenase 3 or 12R, cytochrome p450 4F22), self-healing collodion baby (defective lipoxygenase 3 or 12R), late-onset autosomal recessive congenital ichthyosis, Refsum disease, rhizomelic chondrodysplasia punctata, Sjögren–Larsson syndrome, X-linked recessive ichthyosis and ichthyosis, intellectual disability and spastic quadriplegia; various hyperlipidemias; Farber lipogranulomatosis, Gaucher disease type 2, hyperimmunoglobulinemia D syndrome, localized autosomal recessive hypotrichosis II/autosomal recessive woolly hair, Niemann–Pick disease, psoriasiform dermatitis–microcephaly– developmental delay syndrome

Transglutaminase defects

Lamellar ichthyosis/congenital ichthyosiform erythroderma spectrum (defective transglutaminase 1), acral peeling skin syndrome

Protease/proteasome defects

Dermatosparaxis, familial hidradenitis suppurativa, hereditary angioedema (type III), Howel-Evans syndrome, ichthyosis– hypotrichosis syndrome, IFAP (ichthyosis follicularis–atrichia–photophobia) syndrome, KLICK (keratosis linearis– ichthyosis congenita–sclerosing keratoderma) syndrome, Olmsted syndrome, Papillon–Lefèvre and Haim–Munk syndromes, prolidase deficiency, restrictive dermopathy (defective zinc metallopeptidase), hereditary thrombotic thrombocytopenic purpura, MONA (multicentric osteolysis, nodulosis, and arthropathy), proteasome-associated autoinflammatory/CANDLE/Nakajo-Nishimura syndrome)

Protease inhibitor defects

Antithrombin III deficiency, autosomal recessive exfoliative ichthyosis, hereditary angioedema (types I & II), Netherton syndrome

Desmosomal defects (see Table 56.5 and Fig. 56.8)

Acantholytic epidermolysis bullosa simplex, arrhythmogenic right ventricular dysplasia/cardiomyopathy + palmoplantar keratoderma + woolly hair; Carvajal syndrome, erythrokeratodermia-cardiomyopathy syndrome, generalized inflammatory peeling skin syndrome, hypotrichosis and skin lesions, hypotrichosis simplex of the scalp, localized autosomal recessive hypotrichosis, monilethrix (autosomal recessive), Naxos disease, SAM (severe dermatitis, allergies, and metabolic wasting), skin fragility-ectodermal dysplasia syndrome, skin fragility/woolly hair syndrome, striate palmoplantar keratoderma

Connexin defects (see Table 58.5)

Bart–Pumphrey syndrome, Clouston syndrome, erythrokeratodermia variabilis, hereditary lymphedema type IC, ILVEN, keratoderma-hypotrichosis-leukonychia totalis, KID (keratitis–ichthyosis–deafness) syndrome, oculodentodigital dysplasia, palmoplantar keratoderma with deafness, porokeratotic adnexal ostial nevus, Vohwinkel syndrome (classic)

Other defects in cell-to-cell adhesion

Ichthyosis–hypotrichosis–sclerosing cholangitis syndrome, cleft lip/palate–ectodermal dysplasia syndrome, ectodermal dysplasia–syndactyly syndrome, ectodermal dysplasia–ectrodactyly–macular dystrophy, hypotrichosis with juvenile macular dystrophy, leukocyte adhesion deficiency type I

Defects in keratinocyte– extracellular matrix (ECM) adhesion

Various forms of epidermolysis bullosa (EB) simplex, junctional EB, and dystrophic EB (keratin–ECM linkage); Kindler syndrome (actin–ECM linkage)

ATP-binding cassette (ABC) transporter defects

Harlequin ichthyosis, lamellar ichthyosis/congenital ichthyosiform erythroderma spectrum (defective ABCA12), pseudoxanthoma elasticum, sitosterolemia, Tangier disease/familial hypoalphaproteinemia

Calcium pump defects

Darier disease, Hailey–Hailey disease

Copper transporter defects

Menkes disease, occipital horn syndrome, Wilson disease

Defects in other transporters

Acrodermatitis enteropathica (zinc transporter), arterial tortuosity syndrome (glucose transporter), autosomal dominant hemochromatosis (iron-regulated transporter), spondylodysplastic Ehlers–Danlos syndrome (zinc transporter), H syndrome (nucleoside transporter), Hartnup disease (neutral amino acid transporter), ichthyosis–prematurity syndrome (fatty acid transporter), oculocutaneous albinism (transporters on lysosome-related organelles)

Collagen defects

Various types of dystrophic EB, various types of Ehlers–Danlos syndrome, Ullrich muscular dystrophy, lysyl hydroxylase 3 deficiency

Defects in other ECM proteins

Autosomal dominant cutis laxa, autosomal recessive cutis laxa type I, cutis laxa with severe pulmonary/gastrointestinal/ urinary abnormalities, classic-like and hypermobile Ehlers–Danlos syndrome, juvenile hyaline fibromatosis/infantile systemic hyalinosis, lipoid proteinosis, Marfan syndrome, stiff skin syndrome

Nuclear membrane defects (see Table 63.10)

Buschke–Ollendorff syndrome/melorheostosis, Néstor–Guillermo progeria syndrome, Hutchinson–Gilford progeria syndrome, mandibuloacral dysplasia, partial > generalized lipodystrophy (familial and “acquired” forms), restrictive dermopathy

Defects in pyrin/NOD-family members and related proteins (see Fig. 4.2)

Blau syndrome, NOMID syndrome, familial cold autoinflammatory syndrome, familial Mediterranean fever, Muckle–Wells syndrome, PAPA syndrome

Interferonopathies (see Ch. 45)

Aicardi-Goutières syndrome, familial chilblain lupus, proteasome-associated autoinflammatory/CANDLE/Nakajo-Nishimura syndrome, SAVI (STING-associated vasculopathy with onset in infancy), X-linked reticulate pigmentary disorder

RecQ DNA helicase defects

Bloom syndrome, Rothmund–Thomson syndrome, Werner syndrome

Classic DNA repair defects

Various subtypes of xeroderma pigmentosum, trichothiodystrophy and Cockayne syndrome; Muir–Torre syndrome, constitutional mismatch repair deficiency syndrome

Table 55.1 Molecular classification of genetic skin disorders. cAMP, cyclic adenosine monophosphate; CANDLE, chronic atypical neutrophilic dermatosis with lipodystrophy and elevated temperature; CHILD, congenital hemidysplasia with ichthyosiform nevus and limb defects; JAK, Janus kinase; MAPK, mitogen-activated protein kinase; NF-κB, nuclear factor-κB; NOD, nucleotide-binding oligomerization domain; NOMID, neonatal-onset multisystem inflammatory disease; PAPA, pyogenic arthritis, pyoderma gangrenosum, and acne; SCC, squamous cell carcinoma; STAT, signal transduction and activation of transcription; STING, stimulator of interferon genes; WNT, wingless-type integration site.  

860

MOLECULAR CLASSIFICATION OF GENETIC SKIN DISORDERS

Examples of skin disorders that result

Cell cycle checkpoint defects

Ataxia telangiectasia, familial atypical mole and melanoma (FAMM) syndrome, multiple endocrine neoplasia (MEN) 4

Defects in telomere maintenance

Dyskeratosis congenita (see Table 67.8; 11 genes implicated to date)

RAS–MAPK pathway activation (RASopathies; see Fig. 55.4)

Capillary malformation–arteriovenous malformation, cerebral capillary malformations (familial), cardio-facio-cutaneous syndrome, congenital melanocytic nevi, Costello syndrome, Legius syndrome, neurofibromatosis type 1, Noonan syndrome (with multiple lentigines), Noonan-like disorder with loose anagen hair, verrucous epidermal nevi, nevus sebaceus, woolly hair nevi

Phosphatidylinositol 3-kinase (PI3K)/AKT pathway activation

Epidermal nevi, lymphatic malformations, PIK3CA-related overgrowth spectrum (see Table 104.5), Proteus syndrome, PTEN-hamartoma tumor syndrome, tuberous sclerosis complex, venous malformations

G protein activation

Diffuse capillary malformation with overgrowth (some patients), extensive dermal melanocytosis, McCune-Albright syndrome (versus loss-of-function in Albright hereditary osteodystrophy), phakomatosis pigmentovascularis, port-wine stains, Sturge-Weber syndrome

cAMP and AMP-activated protein kinase pathway defects (see Fig. 55.3)

Albright hereditary osteodystrophy, Carney complex, McCune–Albright syndrome, Peutz–Jeghers syndrome, tuberous sclerosis complex

Defects in WNT/β-catenin signaling (see Fig. 55.6)

Anonychia congenita, ectodermal dysplasia–neoplastic syndrome, Gardner syndrome, Goltz syndrome (focal dermal hypoplasia), hereditary hypotrichosis simplex, palmoplantar keratoderma with cutaneous SCC and sex reversal, WNT10A-related ectodermal dysplasias (including odonto-onycho-dermal dysplasia and Schöpf–Schulz–Passarge syndrome)

Defects in transforming growth factor (TGF)-β signaling

Buschke–Ollendorff syndrome/melorheostosis, Ferguson–Smith multiple self-healing squamous epitheliomas, hereditary hemorrhagic telangiectasia, Loeys–Dietz syndrome, Marfan syndrome, stiff skin syndrome

Defective vesicle assembly/ protein sorting to vesicles

ARC (arthrogryposis–renal dysfunction–cholestasis) syndrome, Hermansky–Pudlak syndrome, MEDNIK (mental retardation, enteropathy, deafness, neuropathy, ichthyosis, keratodermia) syndrome

Defective vesicle trafficking or transport

Autosomal recessive cutis laxa type IIA, CEDNIK (cerebral dysgenesis, neuropathy, ichthyosis and keratoderma) syndrome, Chédiak–Higashi syndrome, gerodermia osteodysplastica, Griscelli syndrome, ocular albinism type 1, wrinkly skin syndrome, MACS (macrocephaly, alopecia, cutis laxa and scoliosis) syndrome

CHAPTER

55 Genetic Basis of Cutaneous Diseases

Molecular defect

Table 55.1 Molecular classification of genetic skin disorders. (cont’d) cAMP, cyclic adenosine monophosphate; MAPK, mitogen-activated protein kinase; SCC, squamous cell carcinoma; WNT, wingless-type integration site.  

A particular six-digit number (MIM number) is assigned to each OMIM entry. The first digit of the MIM number indicates the mode of inheritance of the corresponding genetic defect: 1 for autosomal dominant (entries before May 1994); 2 for autosomal recessive (entries before May 1994); 3 for X-linked; 4 for Y-linked; 5 for mitochondrial; and 6 for autosomal dominant or recessive (entries after May 1994). Phenotype entries describe the clinical and biochemical features, inheritance, mapping, and molecular genetics of a given disease or trait; a “#” is used to designate those for which the molecular basis is known. Gene entries are marked by a “*”, while gene plus phenotype entries are indicated with a “+”; both are appended with important diseasecausing allelic variants (each of which is given a four-digit extension, beginning with .0001).

GENOTYPE–PHENOTYPE CORRELATIONS Genotype–phenotype correlations in genodermatoses are often complex. Mutations in a single gene can cause more than one clinical disorder, a phenomenon referred to as allelic or clinical heterogeneity (see Table 54.2). This can result either from the same mutation occurring in patients with different genetic backgrounds or ages at presentation (e.g. identical PTEN mutations leading to Cowden syndrome and Bannayan–Riley–Ruvalcaba syndrome) or from different mutations (e.g. distinct mutations in the gene encoding lamin A/C leading to Hutchinson–Gilford progeria and familial partial lipodystrophy). Mutations that affect different domains of a protein can produce divergent phenotypes; for example, mutations in the sterile alpha motif (SAM) domain of the p63 protein typically cause AEC (ankyloblepharon, ectodermal dysplasia and cleft lip/palate) syndrome, while those in the DNA-binding domain give rise to EEC (ectrodactyly, ectodermal dysplasia and cleft lip/palate) syndrome. Various mutations in a particular gene can even lead to disorders with different modes of inheritance, such as X-linked dominant incontinentia pigmenti (a male-lethal condition due to a genomic rearrangement resulting in a partial deletion of

the nuclear factor-κB essential modulator [NEMO] gene) and X-linked recessive hypohidrotic ectodermal dysplasia with immunodeficiency (due to milder, “hypomorphic” mutations in the NEMO gene). Conditions found to represent unexpected examples of allelic heterogeneity in the transforming growth factor-β (TGF-β) signaling pathway include mutations in the TGF-β receptor 1 gene (TGFBR1) in Ferguson– Smith multiple self-healing squamous epithelioma (loss-of-function) as well as Loeys–Dietz syndrome (gain-of-function), and fibrillin 1 gene (FBN1) mutations in generalized stiff skin syndrome as well as Marfan syndrome. The type of mutation can also affect the severity of a genodermatosis. The potentially lethal generalized severe form of junctional EB (JEB, an autosomal recessive disorder) is typically caused by mutations in the LAMB3 gene that lead to a premature termination codon (resulting in a complete absence of the LAMB3 protein), whereas milder forms of JEB are produced by missense or splice-site mutations in the same gene (resulting in a LAMB3 protein with decreased function). In contrast, in autosomal dominant conditions where there is dimerization of the mutated protein product (e.g. the KIT tyrosine kinase receptor that is defective in piebaldism), dominant negative missense mutations often result in more severe disease (via abnormal proteins binding to and disrupting normal proteins) than do mutations that lead to premature termination codons and thereby result in haploinsufficiency (complete loss of half of the proteins). In other instances, mutations in different genes produce the same clinical disorder; this is referred to as locus or genetic heterogeneity. Locus heterogeneity can occur when mutated proteins serve a similar function (e.g. components of various biogenesis of lysosome-related organelle complexes [BLOCs] in Hermansky–Pudlak syndrome) or interact with one another in a complex (e.g. hamartin and tuberin in tuberous sclerosis), as a ligand and receptor (e.g. endothelin-3 and the endothelin-B receptor in type 4 Waardenburg syndrome), or in a signaling pathway (e.g. various RAS–mitogen-activated protein kinase [MAPK] pathway proteins in cardio-facio-cutaneous syndrome; see below). However, phenotypic differences can arise when these proteins also

861

GROUPS OF MONOGENIC SKIN DISORDERS LISTED IN TABLES ELSEWHERE IN THE BOOK SECTION

Genodermatoses

9

Category

Table(s)

Congenital insensitivity to pain and related neuropathies Epidermolysis bullosa and other blistering disorders

6.10

Sclerodermoid disorders

43.7

Autoinflammatory diseases

45.2 & 45.7

Porphyrias

49.3

Keratinopathies and desmosomal disorders

56.4; Figs 56.5 & 56.8

Ichthyoses

57.1 & 57.4

Connexin disorders and keratodermas

58.5 & 58.6

Primary immunodeficiencies

60.4, 60.6, 60.8, 60.10, 60.13, 60.15, & 60.16

Disorders associated with multiple café-au-lait macules

61.4

Epidermal nevi and other mosaic disorders

62.4 & 62.7

Progeroid syndromes/inherited poikilodermas and nuclear membrane disorders

63.9 & 63.10

Ectodermal dysplasias

63.11–63.13

Aplasia cutis congenita, cleft lip/palate, and digital anomalies

64.3–64.6

Disorders of hypopigmentation (diffuse or circumscribed)

65.1, 66.4

Keratin Defects

Disorders with reticulated hyperpigmentation, dyskeratosis congenita, and dyschromatoses

67.7, 67.8, & 67.10

Hypotrichosis, hair shaft disorders, and hypertrichosis

69.8; 70.1 & 70.2

Xeroderma pigmentosa and other photosensitivity disorders

86.2, 87.4

Hyperlipidemias

92.2

Ehlers–Danlos syndrome, cutis laxa, and other extracellular matrix disorders

95.5; 97.1, 97.2, & 97.6

Lipodystrophy syndromes

101.1

Vascular anomalies and overgrowth syndromes

104.2 & 104.5

Disorders with multiple lentigines

112.2

In 1991, EB simplex (EBS) became the first human disease shown to be caused by intermediate filament mutations. Since that time, molecular defects in keratins have been identified in a diverse group of hereditary disorders affecting the skin, leading to mechanical fragility and/or abnormal keratinization, depending on the layer of the epidermis in which the defective protein is expressed; the hair, nails, and oral mucosa may also be involved (see Table 55.2)16. Dowling–Degos disease and Naegeli–Franceschetti–Jadassohn (NFJ) syndrome, which are characterized by reticulated pigmentation and (for NFJ) ectodermal dysplasia, represent entities more recently recognized as belonging to the keratin disorder category. Keratin intermediate filaments, which are expressed in a tissue- and differentiation-specific fashion, are composed of heterodimeric subunits formed by the specific pairing of a type I (acidic; KRT9–20, 25–28 [inner root sheath], 31–40 [hair]) and type II (basic–neutral; KRT1–8, 71–75 [inner root sheath], 81–86 [hair]) keratin (see Ch. 56). Keratin genes are clustered at two loci in the human genome, 17q21 (type I keratins) and 12q13 (type II keratins). Many keratin disorders can be caused by mutations (often dominant negative) in either the type I or type II component of a particular keratin pair, thus exhibiting locus heterogeneity (e.g. KRT10 or KRT1 for epidermolytic ichthyosis; KRT14 or KRT5 for EBS). Allelic heterogeneity is also observed, with mutations in the highly conserved helix initiation and termination motifs leading to more severe phenotypes than those in other regions (e.g. the generalized severe form of EBS versus localized EBS) (see Fig. 56.5).

32.1 & 32.3

Table 55.2 Groups of monogenic skin disorders listed in tables elsewhere in the book. In addition, other chapters (especially in the genodermatosis section) have tables that present more detailed information on monogenic skin disorders.  

have distinct functions and/or tissue distributions; for example, the neurologic abnormalities in Griscelli syndrome 1 result from myosin Va expression in neurons, and the immunodeficiency and hemophagocytic syndrome that characterize Griscelli syndrome 2 reflect RAB27A expression in hematopoietic cells.

MOLECULAR CLASSIFICATION OF HEREDITARY SKIN DISORDERS

862

Molecular classification (see Table 55.1) represents a useful approach to the categorization of genodermatoses. Based on the pathogenetic defect rather than the clinical presentation, it can highlight similarities between conditions with seemingly disparate phenotypes (e.g. classic ichthyoses and metabolic disorders such as Gaucher disease, both caused by defects in lipid metabolism) and facilitate better understanding of important cellular pathways (e.g. RAS signaling) and responses to external stimuli (e.g. pyrin/NOD family members that function in innate immunity). Several groups of genodermatoses for which molecular classification has been instructive are discussed below.

Fig. 55.1 Autosomal recessive monilethrix due to desmoglein 4 mutations. Sparse short hairs, stubble and follicular papules on the scalp. Inset: Trichogram showing alternating elliptical nodes and constrictions.  

Defects in Intercellular Junctions Mutations in genes encoding components of desmosomes and gap junctions underlie a variety of genodermatoses, several of which have prominent extracutaneous manifestations.

Desmosomal defects Desmosomes are intercellular junctions that provide mechanical integrity to tissues by anchoring intermediate filaments to the cell surface and mediating strong cell–cell adhesion (see Ch. 56). They are particularly important in stratified squamous epithelia and the myocardium, tissues that are subjected to substantial mechanical stress17. It is therefore not surprising that impaired keratinization (especially palmoplantar keratoderma), skin fragility, and cardiomyopathy represent features of disorders caused by defects in desmosomal proteins such as desmoplakin, plakoglobin and plakophilin 1 (see Fig. 56.8 and Table 56.5).

SELECTED HEREDITARY DISORDERS OF THE NAILS

Mode of inheritance

Gene or gene product

Gene symbol

Anonychia congenita

AR

R-spondin family, member 4

RSPO4

Isolated AR nail dysplasia

AR

Frizzled 6

FZD6

Isolated congenital nail clubbing

AR

Hydroxyprostaglandin dehydrogenase 15-(NAD)

HPGD

Isolated toenail dystrophy

AD

Collagen VII, α1 chain

COL7A1

Leukonychia totalis

AD, AR

Phospholipase C delta 1

PLCD1

Nail–patella syndrome

AD

LIM homeobox transcription factor 1β

LMX1B

Pachyonychia congenita-6a

AD

Keratin 6a

KRT6A

Pachyonychia congenita-16

AD

Keratin 16

KRT 16

Pachyonychia congenita-6b

AD

Keratin 6b

KRT6B

Pachonychia congenita-17

AD

Keratin 17

KRT17

Tricho-rhino-phalangeal syndrome 1

AD

TRPS1 (zinc finger protein)

TRPS1

Table 55.3 Selected hereditary disorders of the nails. Nail abnormalities can also be observed in patients with disorders of keratinization and ectodermal dysplasias. Pachydermoperiostosis is included in Table 55.8.  

CHAPTER

55 Genetic Basis of Cutaneous Diseases

Disorder

SELECTED HEREDITARY METABOLIC SKIN DISORDERS

Disorder

Mode of inheritance

Gene or gene product

Gene symbol

Disorders due to enzyme deficiencies (see Ch. 63) Alkaptonuria

AR

Homogentisate 1,2-dioxygenase (homogentisate oxidase)

HGD

Biotinidase deficiency

AR

Biotinidase

BTD

Holocarboxylase synthetase deficiency

AR

Holocarboxylase synthetase

HLCS

Fabry disease*

XR

α-Galactosidase A

GLA

Fucosidosis*

AR

α-L-Fucosidase

FUCA1

Farber lipogranulomatosis

AR

Acid ceramidase

ASAH

Gaucher disease types I–III

AR

Acid β-glucosidase (glucocerebrosidase)

GBA

Types I & II

AD

Serpin peptidase inhibitor, clade G, member 1 (C1 esterase inhibitor)

SERPING1

Type III

AD (only females affected)

Factor XII (Hageman factor)

F12 CBS

Hereditary angioedema

Homocystinuria

AR

Cystathionine β-synthase†

Niemann–Pick disease type A

AR

Acid sphingomyelinase

SMPD1

Phenylketonuria

AR

Phenylalanine hydroxylase

PAH

AR

Quinoid dihydropteridine reductase

QDPR

AR

6-Pyruvoyltetrahydropterin synthase

PTS

AR

Prolidase (peptidase D)

PEPD

Prolidase deficiency

Disorders due to defective transporters/related proteins Acrodermatitis enteropathica

AR

Solute carrier family 39, member 4 (zinc transporter)

SLC39A4

H syndrome‡

AR

Solute carrier family 29, member 3 (nucleoside transporter)

SLC29A3

Hartnup disease

AR

Solute carrier family 6, member 19 (neutral amino acid transporter)

SLC6A19

Hemochromatosis

AR

Hemochromatosis

HFE

AR

Transferrin receptor 2

TFR2

AD

Solute carrier family 40, member 1 (ferroportin)

SLC40A1

AR

Hepcidin antimicrobial peptide

HAMP

AR

Hemojuvelin

HFE2

Hemochromatosis, juvenile Wilson disease

AR

2+

Cu -transporting P-type ATPase 7B

*† Additional metabolic disorders that can present with angiokeratoma corporis diffusum are presented in Table 63.7. Defects in this gene represent the most common cause of homocystinuria. ‡Including cases reported as pigmented hypertrichotic insulin-dependent diabetes mellitus syndrome and familial histiocytosis syndrome. Table 55.4 Selected hereditary metabolic skin disorders.  

ATP7B

863

SELECTED HEREDITARY DISORDERS CHARACTERIZED BY BENIGN SKIN TUMORS

SECTION

Genodermatoses

9

Disorder

Mode of inheritance

Gene or gene product

Gene symbol

Familial cylindromatosis; Brooke–Spiegler syndrome; multiple familial trichoepitheliomas

AD

CYLD (deubiquitinating enzyme)

CYLD

Familial mastocytosis ± gastrointestinal stromal tumors*

AD

KIT proto-oncogene (stem cell factor receptor)

KIT

Leiomyomatosis, cutaneous and uterine (Reed syndrome)†

AD

Fumarate hydratase

FH

Lipomatosis, familial multiple

AD

Lipomatosis, benign symmetric (Madelung disease)‡

mt

Mitochondrial tRNA-lysine

MT-TK

AR

Mitofusin 2

MFN2

AR

Lipase E, hormone sensitive

LIPE

Ferguson–Smith multiple self-healing squamous epitheliomas

AD

Transforming growth factor-β receptor 1 (loss-of-function mutations)

TGFBR1

Neurofibromatosis type 1

AD

Neurofibromin 1 (GTPase activating protein)

NF1

Neurofibromatosis type 2

AD

Neurofibromin 2 (merlin)

NF2

Tuberous sclerosis complex

AD

Hamartin

TSC1

AD

Tuberin

TSC2

*† Occasionally malignant.

Also associated with renal cell carcinoma.

‡Associated with myoclonic epilepsy with ragged red fibers (MT-TK mutations), neuropathy (MFN2 mutations), or partial lipodystrophy and myopathy (LIPE mutations).

Table 55.5 Selected hereditary skin disorders characterized by benign skin tumors. These conditions are discussed in Chapters 61, 62, 104, 117, and 118). GTP, guanine triphosphate; mt, mitochondrial inheritance; TGF, transforming growth factor.  

SELECTED HEREDITARY DISORDERS ASSOCIATED WITH SKIN CANCER

Disorder

Mode of inheritance

Gene or gene product

Gene symbol

Bazex–Dupré–Christol syndrome

XD

Actin-related protein T1

ACTRT1

Epidermodysplasia verruciformis

AR

Transmembrane channel-like 6

TMC6

AR

Transmembrane channel-like 8

TMC8

BAP1 tumor predisposition syndrome*

AD

BRCA-associated protein 1

BAP1

Familial atypical mole and melanoma (FAMM) syndrome*

AD

Cyclin-dependent kinase inhibitor 2A**

CDKN2A

AD

Cyclin-dependent kinase 4

CDK4

AD

Patched 1

PTCH1

AD

Patched 2

PTCH2

AD

Suppressor of fused homolog (Drosophila)

SUFU

Basal cell nevus syndrome

Huriez syndrome (sclerotylosis)

AD

Palmoplantar keratoderma with cutaneous SCC and sex reversal

AR

R-spondin 1

RSPO1

Pigmentation defects, palmoplantar keratoderma, and cutaneous SCC

AR

SAM and SH3 domain-containing 1

SASH1

Xeroderma pigmentosum (see Table 86.2)

*Also associated with melanocytic nevi. **Also associated with increased risk of developing pancreatic cancer. Table 55.6 Selected hereditary disorders associated with skin cancer. These conditions are discussed in Chapters 79, 87, 99, 108 and 112. SCC, squamous cell carcinoma.  

Abnormal hair (oftentimes woolly in nature) can also result from abnormalities in these proteins, and defects in other desmosomal components such as desmoglein 4 and corneodesmosin (which are highly expressed within the hair follicle) can lead to hypotrichosis and (for desmoglein 4) an autosomal recessive form of monilethrix (Fig. 55.1). Additional consequences of desmosomal defects include inflammatory peeling skin (corneodesmosin) and severe dermatitis, allergies, and metabolic wasting (SAM; desmoglein 1, desmoplakin).

Connexin defects 864

Gap junctions are intercellular channels that connect the cytoplasm of neighboring cells, facilitating communication that coordinates cellular

growth, differentiation and responses to stimuli as well as tissue morphogenesis and homeostasis (see Ch. 58). Transmembrane connexin proteins undergo oligomerization to form the connexons that compose gap junctions. Connexin proteins such as Cx26, Cx30, Cx31, and Cx43 are preferentially expressed in ectoderm-derived epithelia of the inner ear and cornea as well as in the epidermis and its appendages18. This accounts for the sensorineural deafness, keratitis, and cutaneous abnormalities ranging from keratoderma to erythrokeratoderma to ectodermal dysplasias affecting the hair and nails that are observed in various connexin disorders (see Table 55.1). Several connexins are expressed in lymphatic cells, and mutations in the gene encoding Cx47 cause a hereditary type of lymphedema19.

SELECTED HEREDITARY SKIN DISORDERS ASSOCIATED WITH EXTRACUTANEOUS CANCER

Mode of inheritance

Gene or gene product

Gene symbol

Ataxia–telangiectasia

AR

Ataxia–telangiectasia mutated (phosphatidylinositol 3-kinase-like serine/threonine protein kinase)

ATM

Birt–Hogg–Dubé syndrome

AD

Folliculin

FLCN

Bloom syndrome

AR

RecQ protein-like 3 (DNA helicase)

BLM (RECQL3)

Costello syndrome (see text)

AD

v-Ha-ras Harvey rat sarcoma viral oncogene homolog

HRAS

AD

v-Ki-ras2 Kirsten rat sarcoma viral oncogene homolog

KRAS

AD

Succinate dehydrogenase complex, subunit B, iron sulfur

SDHB

AD

Succinate dehydrogenase complex, subunit D, integral membrane protein

SDHD

AD

Axis inhibitor 2

AXIN2

Cowden-like syndrome

Dyskeratosis congenita (see Table 67.8) Ectodermal dysplasia–neoplastic syndrome Gardner syndrome

AD

Adenomatous polyposis coli

APC

Howel–Evans syndrome (tylosis–esophageal carcinoma)

AD

Rhomboid 5 homologue 2

RHBDF2

Muir–Torre syndrome

AD

MutS homolog 2 (mismatch repair enzyme)

MSH2

AD

MutS homolog 6 (mismatch repair enzyme)

MSH6

AD

MutL homolog 1 (mismatch repair enzyme)

MLH1

MUTYH-associated polyposis

AR

MutY homolog

MUTYH

Constitutional mismatch repair deficiency syndrome (childhood tumor syndrome with neurofibromatosis type 1 phenotype)

AR

MutS homolog 2 (mismatch repair enzyme)

MSH2

AR

MutS homolog 6 (mismatch repair enzyme)

MSH6

AR

MutL homolog 1 (mismatch repair enzyme)

MLH1

AR

Postmeiotic segregation increased 2 (mismatch repair enzyme)

PMS2

Multiple endocrine neoplasia (MEN)

MEN 1

AD

Menin

MEN1

MEN 2A

AD

Ret proto-oncogene (cysteine-rich extracellular domain)

RET

MEN 2B

AD

Ret proto-oncogene (particularly Met918Thr in substrate recognition pocket)

RET

MEN 4

AD

Cyclin-dependent kinase inhibitor 1B (p27, Kip1)

CDKN1B

PTEN hamartoma tumor syndrome (including Cowden and Bannayan–Riley–Ruvalcaba syndromes)

AD

Phosphatase and tensin homolog

PTEN

Rothmund–Thomson syndrome

AR

RecQ protein-like 4 (DNA helicase)

RECQ4

CHAPTER

55 Genetic Basis of Cutaneous Diseases

Disorder

Table 55.7 Selected hereditary skin disorders associated with extracutaneous cancer. These conditions are discussed in Chapters 60, 63, 67, and 87. CNS, central system.  

Defects in Keratinocyte–Extracellular Matrix Adhesion The hemidesmosome links keratin intermediate filaments (KRT5, KRT14) within basal keratinocytes to proteins within the lamina densa (basement membrane proper) and sublamina densa regions of the epidermal basement membrane zone (see Ch. 28). Defects in protein components of these structures lead to various forms of EB (simplex, junctional and dystrophic; see Ch. 32)20. The basement membranes of epithelia in other sites such as the eye, oral cavity, gastrointestinal tract, and genitourinary tract may also be affected in patients with EB. Additional clinical manifestations can result when the abnormal protein has important functions in extraepithelial tissues, such as the skeletal muscle for plectin (leading to EBS with muscular dystrophy). Focal adhesions are structurally defined sites of linkage between the intracellular actin cytoskeleton and the extracellular matrix (ECM; see Fig. 28.3B). Mutations in the gene encoding the focal adhesion protein kindlin-1 cause Kindler syndrome, an autosomal recessive disorder characterized by acral blistering and photosensitivity early in life, progressive poikiloderma and erosive periodontal disease (see Ch. 63).

Kindlin-1 is found within basal keratinocytes along the cell surface that faces the basement membrane, and it has roles in keratinocyte adhesion, polarity, proliferation and motility. To date, Kindler syndrome represents the only skin fragility disorder known to be caused by disruption of linkage between actin microfilaments (rather than keratin intermediate filaments) and the ECM20.

Transmembrane Transporter Defects Abnormalities in transmembrane transporters underlie a variety of genodermatoses, ranging from occipital horn syndrome and Menkes disease (both due to mutations in the gene encoding the ATP7A copper transporter) to oculocutaneous albinism types 2 and 4 (due to defective transporters on lysosome-related organelles) to metabolic disorders such as acrodermatitis enteropathica, Hartnup disease, and hemochromatosis. This list also includes defects in a fatty acid transporter in ichthyosis prematurity syndrome21 and an intracellular nucleoside transporter in H syndrome (Fig. 55.2)22. Disorders of calcium pumps and ATP-binding cassette (ABC) transporters, which underscore the important roles of transmembrane transporters in cutaneous homeostasis, are discussed below.

865

OTHER SELECTED INHERITED SKIN DISORDERS

Disorder SECTION

Genodermatoses

9

Mode of inheritance

Gene or gene product

Gene symbol

Disorders characterized by excessive extracellular matrix protein deposition (also see Table 43.7) Inherited systemic hyalinosis (juvenile hyaline fibromatosis, infantile systemic hyalinosis)

AR

Anthrax toxin receptor 2 (capillary morphogenesis protein 2)

ANTXR2

Lipoid proteinosis

AR

Extracellular matrix protein 1

ECM1

Psoriasiform conditions (also see Table 45.7 for pustular psoriasis variants) Psoriasiform dermatitis–microcephaly–developmental delay

AR

Sterol-C4-methyl oxidase-like

SC4MOL

Seborrhea-like dermatitis with psoriasiform elements

AD

Zinc finger protein 750

ZNF750

Familial pityriasis rubra pilaris or (pustular) psoriasis

AD

Caspase recruitment domain family member 14

CARD14

Apert syndrome

AD

Fibroblast growth factor receptor 2

FGFR2

Beare–Stevenson cutis gyrata syndrome

AD

Fibroblast growth factor receptor 2

FGFR2

Crouzon syndrome with acanthosis nigricans; SADDAN; thanatophoric dysplasia

AD

Fibroblast growth factor receptor 3*

FGFR3

Oral–facial–digital syndrome

XD

Oral–facial–digital syndrome 1

OFD1

Craniosynostosis/skeletal dysplasia syndromes

Disorders with prominent neurologic abnormalities (also see Table 6.10) Cockayne syndrome†

CSA

AR

ERCC8 (transcription-coupled repair protein)

ERCC8

CSB

AR

ERCC6 (transcription-coupled repair protein)

ERCC6

AR

Cytokine receptor-like factor 1

CRLF1

Cold-induced sweating syndrome

AR

Cardiotrophin-like cytokine factor 1

CLCF1

Primary erythromelalgia

AD

Sodium channel, voltage-gated, type IX, α-subunit

SCN9A

Familial primary localized cutaneous amyloidosis

AD

Oncostatin M receptor

OSMR

Interleukin-31 receptor A

IL31RA

Defects in coagulation or platelet plugging (see Ch. 23, Table 105.9) Activated protein C resistance (factor V Leiden)

AD

Factor V

F5

Protein C deficiency

AD

Protein C

PROC

Protein S deficiency

AD

Protein S

PROS1

Antithrombin III deficiency

AD

Serpin peptidase inhibitor C1 (antithrombin III)

SERPINO

Hyperprothrombinemia

AD

Prothrombin, G20210A polymorphism

F2

ADAMTS13 deficiency-mediated thrombotic microangiopathy (thrombotic thrombocytopenic purpura)

AR

ADAM metallopeptidase with thrombospondin type 1 motif, 13 (von Willebrand factor-cleaving protease)

ADAMTS13

Disorders with cutaneous calcification or ossification (see Ch. 50) Albright hereditary osteodystrophy

AD

Stimulatory G protein, α-subunit (Gsα; inactivating mutations)

GNAS

Progressive osseous heteroplasia

AD

Stimulatory G protein, α-subunit (Gsα; inactivating mutations)

GNAS

Fibrodysplasia ossificans progressiva

AD

Activin A receptor, type 1

ACVR1

Hyperphosphatemic familial tumoral calcinosis

AR

UDP-N-acetyl-αD-galactosamine:polypeptide N-acetylgalactosaminyltransferase 3

GALNT3

AR

Fibroblast growth factor 23

FGF23

AR

Klotho

KL

Normophosphatemic familial tumoral calcinosis

AR

Sterile alpha motif domain-containing 9

SAMD9

Pachydermoperiostosis

AR

15-hydroxyprostaglandin dehydrogenase

HPGD

AR

Solute carrier organic anion transporter, member 2A1

SLCO2A1

*† Somatic FGFR3 mutations have been found to underlie a subset of epidermal nevi.

Patients with mutations in ERCC3 (XPB), ERCC2 (XPD) and ERCC5 (XPG) may have phenotypes with features of both xeroderma pigmentosum and Cockayne syndrome (XP/CS).

Table 55.8 Other selected inherited skin disorders. ERCC, excision repair cross-complementing; SADDAN, severe achondroplasia with developmental delay and acanthosis nigricans; LAMB, lentigines, atrial myxomas, mucocutaneous myxomas, blue nevi; LEOPARD, lentigines, ECG changes, ocular hypertelorism, pulmonary stenosis, abnormal genitalia, retardation of growth, deafness; NAME, nevi, atrial myxomas, myxoid neurofibromas, ephelides.  

866



A

ATP-binding cassette transporter defects Members of the ABC transporter superfamily bind and hydrolyze adenosine triphosphate (ATP) in order to transport various molecules across a cell membrane or into a vesicle. Well-known examples include the cystic fibrosis transmembrane conductance regulator (CFTR, ABCC7; the chloride ion channel that is defective in patients with cystic fibrosis) and the P glycoprotein (ABCB1; an important cellular mechanism of multidrug resistance). Several phenotypically diverse genodermatoses are also caused by mutations in ABC transporters (see Table 55.1)24. Because fragmentation and calcification of elastic fibers in the skin, eyes, and cardiovascular system are major features of pseudoxanthoma elasticum (PXE), the latter was initially thought to represent a heritable connective tissue disorder that (presumably) resulted from mutations in a gene encoding an extracellular matrix protein. Surprisingly, PXE was instead found to be caused by mutations in the ABCC6 gene, which encodes an organic acid transporter (based on in vitro studies) that is expressed almost exclusively in the liver and kidneys. Together with evidence that metabolites present in the sera of PXE patients interfere with the normal assembly of elastic fibers in vitro, this suggests that PXE is actually better characterized as a metabolic disorder with secondary connective tissue manifestations. Biallelic mutations in ABCA12, which encodes a transporter that secretes lipids into lamellar granules, cause both harlequin ichthyosis and a form of lamellar ichthyosis25 (see Fig. 56.2). Patients with harlequin ichthyosis tend to have nonsense mutations, whereas those with lamellar ichthyosis typically have missense mutations. This represents one of the most clearcut genotype–phenotype correlations observed to date for non-syndromic autosomal recessive ichthyoses. Defective formation of intercellular lipid layers, which are essential for epidermal barrier function, due to genetic defects in lipid metabolism also represents the pathomechanism of an expanding list of other ichthyosiform disorders (see Table 55.1 and Fig. 56.2)25.

CHAPTER

55 Genetic Basis of Cutaneous Diseases

Fig. 55.2 H syndrome. This autosomal recessive disorder due to mutations in the SLC29A3 gene (which encodes a nucleoside transporter) presents with hyperpigmentation, hypertrichosis, induration and varicose veins in a characteristic distribution pattern on the thighs with sparing of the knees (A). Additional features include hallux valgus and flexion contractures of the toes (B), hepatosplenomegaly, heart anomalies, hearing loss, hypogonadism, low height and hyperglycemia/diabetes mellitus.

Nuclear Envelope Defects

B

Calcium pump defects Darier disease and Hailey–Hailey disease are distinct autosomal dominant disorders that share the histologic feature of epidermal acantholysis leading to suprabasal cleft formation; on an ultrastructural level, this corresponds to disruption of the desmosome–keratin intermediate filament complex. The two conditions also have some clinical similarities, including intertriginous involvement, vesiculobullous lesions (relatively uncommon in Darier disease), nail changes, exacerbation with heat, and frequent superinfections. As a result of these overlapping features, it was initially postulated that Darier disease and Hailey– Hailey disease were allelic disorders caused by defects in a gene encoding a structural component of the epidermis. However, linkage studies mapped Darier disease to chromosome 12 and Hailey–Hailey disease to chromosome 3, and no candidate structural genes were found in these regions. In 1999, pathogenetic mutations in the ATP2A2 gene, which encodes a sarcoplasmic/endoplasmic reticulum Ca2+ ATPase, were identified in patients with Darier disease. Subsequently, mutations in the ATP2C1 gene on chromosome 3, which encodes a Ca2+ ATPase localized to the Golgi apparatus, were shown to cause Hailey–Hailey disease. Determining the molecular bases of these genodermatoses thus demonstrated the pivotal role of calcium homeostasis in epidermal differentiation and cell–cell adhesion23.

“Nuclear envelopathies” represent a clinically heterogeneous group of inherited disorders caused by defects in structural components of the nuclear envelope (see Table 63.10). In addition to a variety of extracutaneous findings – e.g. skeletal dysplasia, muscular dystrophy, cardiomyopathy and neuropathy – dermatologic manifestations include: premature aging of the skin, e.g. in progeria and “atypical Werner syndrome” due to LMNA mutations; cutaneous fibrosis, e.g. in restrictive dermopathy and Buschke–Ollendorff syndrome/melorheostosis due to LMNA and LEMD3 mutations, respectively; and partial lipodystrophy, e.g. familial Dunnigan and “acquired” Barraquer–Simons types due to LMNA and LMNB2 mutations, respectively. “Laminopathies” represent the largest subgroup of envelopathies and result from mutations in the genes that encode the lamin A/C and lamin B2 proteins of the nuclear membrane lamina, which lies just inside the inner nuclear membrane26. The LEMD3 gene encodes MAN1, an inner nuclear membrane protein that associates with lamin A. In addition to “true” envelopathies, mutations in the ZMPSTE24 gene, which encodes a zinc metallopeptidase involved in the processing of prelamin A into mature lamin A, can result in restrictive dermopathy and mandibuloacral dysplasia characterized by lipodystrophy, premature aging and skeletal defects. The study of patients with envelopathies has provided insight into the importance of lamins and other nuclear envelope proteins to the structural integrity of the nucleus, chromatin organization, transcriptional regulation, control of differentiation, and mechanisms of aging26.

Defects in Pyrin/NOD Family Members and Related Proteins The molecular bases of several hereditary periodic fever syndromes and other autoinflammatory disorders have been found to be due to defects in proteins containing nucleotide-binding oligomerization domains (NODs) and/or pyrin domains (see Table 45.2)27. This has drawn attention to the NOD and pyrin families and related proteins (see Fig. 4.2), helping to uncover their importance in innate immune responses and acquired inflammatory disorders. Defects in such proteins lead to diverse cutaneous phenotypes, ranging from urticarial papules in

867

SECTION

Genodermatoses

9

cryopyrin-related disorders and erysipeloid erythema in familial Mediterranean fever to nodulocystic acne and pyoderma gangrenosum in PAPA syndrome to granulomatous dermatitis (together with arthritis and uveitis) in Blau syndrome (see Fig. 45.11C). Upon uncovering NOD2 mutations as the defect in Blau syndrome, it was also established that this autosomal dominant disorder and “early-onset sarcoidosis” are identical on a genetic as well as phenotypic level (with the latter resulting from de novo NOD2 mutations), thus representing a single disease entity. However, different NOD2 variants have been implicated in Crohn disease and susceptibility to leprosy.

Defects in DNA Repair Genes, Tumor Suppressor Genes and Oncogenes Hereditary cancer syndromes that affect the skin can be divided into groups based upon whether the associated malignancies are primarily cutaneous (e.g. basal cell nevus syndrome; see Table 55.6) or extracutaneous (see Table 55.7); individuals in the latter group may have either benign cutaneous neoplasms (e.g. Cowden syndrome) or non-neoplastic skin lesions (e.g. ataxia–telangiectasia)28. To complement this clinical approach, molecular classification of such syndromes can help to explain relationships among disorders, understand the disrupted pathway or process, and suggest candidate genes for patients with similar phenotypes for which the underlying molecular defect has not yet been identified. In addition to characterization based on the specific pathomechanism (e.g. RAS–MAPK pathway activation29; see below), hereditary cancer syndromes can be separated into three general categories: (1) defective DNA repair and protection of genomic integrity (“caretaker” genes); (2) defective tumor suppressor (“gatekeeper”) genes; and (3) activated oncogenes.

Defective DNA repair and protection of genomic integrity Inactivation of caretaker genes causes an increased mutation rate in all genes, including gatekeeper genes with critical roles in controlling tumor growth (see below). Classic examples of caretaker dysfunction include defects in various nucleotide excision repair proteins (required for correction of UV-induced DNA damage) in xeroderma pigmentosum and abnormal mismatch repair in Muir–Torre syndrome (a subtype of the hereditary non-polyposis colorectal cancer syndrome). Defects in RecQ helicases, which function in DNA replication, recombination and repair, underlie Bloom, Rothmund–Thomson, and Werner syndromes. This leads to genomic instability, as evidenced by findings such as accumulation of chromosomal aberrations, increased sister chromatid exchange (Bloom syndrome), and shortened telomeres (Werner syndrome). The compromised telomere maintenance observed in dyskeratosis congenita can result from defects in telomerase subunits (RNA and reverse transcriptase) or associated proteins (e.g. dyskerin, a Cajal body protein, ribonucleoprotein homologs, shelterin complex components; see Table 67.8).

Defective tumor suppressor genes In hereditary cancer syndromes caused by a defective tumor suppressor gene, there is classically a heterozygous germline loss-of-function mutation followed by a somatic “second hit” that leads to loss of heterozygosity and abrogation of protein function in affected tissues. Examples include PTCH (encoding patched) in basal cell nevus syndrome (see Ch. 107), CDKN2A (encoding p16INK4a and p14ARF, which maintain activity of the retinoblastoma [Rb] and p53 tumor suppressor proteins, respectively) in the familial atypical mole and melanoma syndrome (see Ch. 113), and PTEN in the PTEN hamartoma tumor syndrome (see Ch. 63). The PTEN protein negatively regulates the phosphatidylinositol 3-kinase (PI3K)/AKT cascade, the same pathway that is positively regulated by the RET oncogene (Fig. 55.3; see below). The PIK3CA-related overgrowth spectrum and Proteus syndrome are caused by mosaicism for an activating mutation in PIK3CA and AKT1 oncogenes, respectively, explaining their clinical similarity to type 2 mosaic PTEN hamartoma tumor syndrome (see Table 104.5 and below).

Activated oncogenes 868

Germline gain-of-function mutations in oncogenes have been identified in some autosomal dominant hereditary tumor syndromes, including RET in multiple endocrine neoplasia (MEN) 2A/2B (see Fig. 55.3), KIT in familial mastocytosis plus gastrointestinal stromal tumors, and those

encoding RAS–MAPK pathway components in some “RASopathies” (Fig. 55.4). The latter include Costello (Fig. 55.5), Noonan, and cardiofacio-cutaneous (CFC) syndromes as well as Noonan with multiple lentigines (LEOPARD) syndrome29,29a. In addition, neurofibromatosis type 1 (NF1), Legius syndrome (previously referred to as NF1-like syndrome), and capillary malformation-arteriovenous malformation (CM-AVM) represent RASopathies due to germline loss-of-function mutations in tumor suppressor genes that normally down-regulate RAS–MAPK signaling29. RASopathies share extracutaneous features such as ocular hypertelorism, macrocephaly, cardiac defects (especially pulmonary stenosis) and developmental delay, as well as a spectrum of skin findings that includes hair abnormalities (e.g. curly, woolly, loose anagen), pigmented lesions (e.g. lentigines, melanocytic nevi, café-au-lait macules)31, keratosis pilaris, acanthosis nigricans and distal phalangeal transverse creases (see Fig. 55.5B&C). Some RASopathies also have more specific cutaneous manifestations, such as neurofibromas in NF1, lax acral skin in Costello syndrome (see Fig. 55.5B), and capillary and arteriovenous malformations in CM-AVM. Different RASopathies are associated with variably increased risks for the development of benign (e.g. neurofibromas in NF1, infantile hemangiomas in CFC syndrome) and malignant (e.g. rhabdomyosarcoma in Costello syndrome) tumors. Targeted drugs aimed at proteins in the RAS–MAPK pathway hold promise for the treatment of sporadic cancers (e.g. BRAF inhibitors for melanoma) as well as RASopathies themselves30.

Defects in WNT/β-Catenin Signaling WNT (wingless-type integration site) family members are lipidmodified, secreted signaling proteins that play important roles in numerous physiologic and pathologic processes, ranging from stem cell differentiation, cell polarity/adhesion and tissue morphogenesis/ maintenance (including hair follicle development) to wound repair, inflammation, oncogenesis and aging. WNT signaling can be divided into canonical (β-catenin-dependent) and non-canonical (β-cateninindependent) pathways. Several genodermatoses result from defects in proteins that function in the WNT/β-catenin pathway (Fig. 55.6). Goltz syndrome (focal dermal hypoplasia; see Ch. 62) (Fig. 55.7) is caused by mutations in the PORCN gene, which encodes an O-acyltransferase in the endoplasmic reticulum that palmitoylates and thereby facilitates secretion of WNT proteins. Mutations in the WNT10A gene produce several relatively common forms of ectodermal dysplasia as well as Schöpf–Schulz–Passarge syndrome (featuring hidrocystomas and palmoplantar keratoderma with eccrine syringofibroadenomatosis). Gardner syndrome (a variant of adenomatous polyposis coli) is due to mutations in the APC tumor suppressor gene that encodes an inhibitor of WNT/β-catenin signaling32, and mutations in the APC downregulated 1 gene (APCDD1) were recently found to underlie hereditary hypotrichosis simplex. Lastly, anonychia congenita and “palmoplantar keratoderma with cutaneous SCC and sex reversal” are caused by mutations in genes encoding R-spondins that activate WNT/β-catenin signaling.

CONTIGUOUS GENE SYNDROMES Certain syndromic associations actually represent contiguous gene syndromes caused by large deletions that affect two or more neighboring genes. For example, deletions in the Xp22.3 region can give rise to X-linked recessive ichthyosis, X-linked recessive chondrodysplasia punctata, Kallmann syndrome (hypogonadotrophic hypogonadism with anosmia), ocular albinism type 1, short stature, and intellectual disability. Of note, more than 90% of patients with X-linked recessive ichthyosis have complete deletion of the STS gene and flanking sequences, which represents one of the highest incidences of chromosomal deletions among all genetic disorders. Additional genodermatoses that can present as contiguous gene syndromes include Ehlers–Danlos syndrome (due to tenascin-X deficiency) plus congenital adrenal hyperplasia (due to 21-hydroxylase deficiency), tricho-rhino-phalangeal syndrome plus multiple cartilaginous exostoses (together referred to as Langer–Giedion syndrome), and MIDAS (microphthalmia, dermal aplasia and sclerocornea) syndrome plus Aicardi syndrome (agenesis of the corpus callosum with a chorioretinal abnormality).

PHOSPHATIDYLINOSITOL 3-KINASE (PI3K)/AKT, AMP-ACTIVATED PROTEIN KINASE (AMPK), AND CYCLIC AMP SIGNALING PATHWAY DEFECTS IN GENODERMATOSES CHAPTER

MEN2A & B McCune−Albright syndrome

PIK3CArelated segmental overgrowth

P

Receptor P tyrosine kinase, e.g. RET

P

Adenylate cyclase

Tuberous sclerosis

*

55

Albright hereditary Growth factor osteodystrophy

G protein-coupled receptor

α

Proteus syndrome

PI3K

Hamartin

*

PIP2

PIP3

AKT

AMP

PTEN Rheb GTP PTEN hamartoma tumor syndrome (including Cowden and BRR syndromes)

AMP

RAPAMYCIN

mTOR Protein synthesis, cell survival/ growth

*

cAMP

ATP

Rheb GDP

PPKAR1A AMPK

PKA PKA

STK11 Peutz−Jeghers syndrome

in low-energy cell CREB

ATP

α

Carney complex

Tuberin

Genetic Basis of Cutaneous Diseases

Growth factors

Nucleus

in high-energy cell

G stimulatory protein

Gene expression leading to cell proliferation (increasing melanocyte and endocrine gland activity)

Fig. 55.3 Phosphatidylinositol 3-kinase (PI3K)/AKT, AMP-activated protein kinase (AMPK), and cyclic AMP signaling pathway defects in genodermatoses. The PI3K/AKT pathway is negatively regulated by the PTEN tumor suppressor protein and can be stimulated by a variety of receptor tyrosine kinases as well as by RAS (via cross-talk with the RAS–ERK pathway; see Fig. 55.4). AKT (protein kinase B) inhibits the GTPase activating-protein tuberin, which leads to increased mammalian target of rapamycin (mTOR) activity and resultant cell growth. During periods of nutrient depletion (high AMP/low ATP), serine–threonine kinase 11 (STK11) promotes AMPK-mediated activation of tuberin, which results in decreased mTOR activity and less protein synthesis. Ligand binding to G protein-coupled receptors activates adenylate cyclase, producing increased intracellular cAMP and activation of protein kinase A catalytic subunits (PKA; via release from protein kinase A regulatory subunit 1α [PRKAR1A]); this leads to transcription of cAMP response element binding protein (CREB)-controlled genes as well as inhibition of AMPK (which is also negatively regulated by AKT). *Other effector pathways include activation of RAS–ERK (see Fig. 55.4). AMP, adenosine monophosphate; ATP, adenosine triphosphate; BRR, Bannayan–Riley–Ruvalcaba; ERK, extracellular signal-regulated kinase; GDP, guanosine diphosphate; GTP, guanosine triphosphate; PIP2, phosphatidylinositol diphosphate; PIP3, phosphatidylinositol triphosphate; PTEN, phosphatase and tensin homolog deleted on chromosome 10.  

CUTANEOUS MOSAICISM A mosaic is defined as an organism composed of at least two genetically different populations of cells that originate from a genetically homogeneous zygote (see Ch. 62). As a uniquely accessible organ, the skin provides an excellent opportunity to visualize and study mosaicism32a, which can present with skin lesions that follow the lines of Blaschko or have a block-like, phylloid (see below), patchy, or lateralized pattern of distribution. Mosaicism for activating mutations affecting RASMAPK signaling or G protein α-subunits have been found to underlie a variety of birthmarks, including congenital melanocytic, epidermal, and sebaceous nevi as well as port-wine stains and dermal melanocytosis. A single heterozygous mutation in a multipotent progenitor cell can lead to multiple types of birthmarks involving different skin lineages, such as speckled lentiginous (melanocytic) plus sebaceous (adnexal) nevi in phakomatosis pigmentokeratotica (HRAS) or port-wine stains (vascular) plus dermal melanocytosis in phakomatosis pigmentovascularis (GNAQ or GNA11)32b,32c; extracutaneous manifestations may occur if the mutation involves other organs such as the brain, eye, or bones. Mosaic forms of autosomal dominant genodermatoses include: (1) a heterozygous postzygotic mutation occurring on a wild-type (“normal”)

background (type 1); and (2) a postzygotic “second hit” leading to lossof-heterozygosity in the setting of a heterozygous constitutional mutation (type 2). The latter manifests clinically as a localized area or streaks of more severe disease on a background of milder disease (e.g. linear porokeratosis in a patient with disseminated superficial actinic porokeratosis). Examples of type 1 mosaicism that have been confirmed on a molecular level include linear Darier disease (ATP2A2 mutations), epidermolytic epidermal nevi (K1 or K10 mutations), and nonepidermolytic epidermal nevi (fibroblast growth factor receptor 3 [FGFR3] mutations); constitutional mutations in the latter gene produce craniosynostosis syndromes associated with severe acanthosis nigricans (Fig. 55.8). On a molecular level, type 2 mosaicism has been documented for Hailey–Hailey disease (ATP2C1 mutations) (Fig. 55.9), Darier disease (ATP2A2), glomuvenous malformations (GLMN mutations), and PTEN hamartoma tumor syndrome (referred to as “SOLAMEN” – segmental overgrowth, lipomatosis, arteriovenous malformation and epidermal nevus). All women and girls are functional mosaics due to the random, irreversible, stably inherited inactivation of one of the two X chromosomes that occurs in each cell during early embryonic development (lyonization). However, 15% of genes on the human X chromosome escape lyonization and 10% are variably inactivated. In women heterozygous

869

Fig. 55.5 Costello syndrome due to a heterozygous activating HRAS mutation in a 3-yearold girl. A Verrucous periorificial (periocular, perinasal) plaques. B Loose acral skin with deep palmoplantar creases. Note the distal phalangeal transverse crease on the thumb. C Acanthosis nigricans.  

RAS−MITOGEN-ACTIVATED PROTEIN KINASE SIGNALING PATHWAY ABNORMALITIES IN GENODERMATOSES SECTION

Genodermatoses

9

Growth factor

P Receptor tyrosine kinase

RAS GDP

P SHP2

SOS1

Neurofibromin

*

LEOPARD syndrome (RAF1)

Noonan syndrome (RAF1>KRAS)

RAS GTP

Costello syndrome (HRAS) SPRED1

RAF Other effector pathways, e.g. PI3K/AKT (see Fig. 55.3)

Neurofibromatosis type 1

Legius syndrome

A

Cardio-facio-cutaneous syndrome (BRAF>>KRAS)

MEK

ERK Nucleus SHC Gab GRB2

Gene expression leading to cell proliferation

Fig. 55.4 RAS–mitogen-activated protein kinase (MAPK) signaling pathway abnormalities in genodermatoses. The phenotypic overlap among neurofibromatosis type 1 and Legius, Noonan, cardio-facio-cutaneous, Costello and LEOPARD (Noonan syndrome with multiple lentigines) syndromes is explained by underlying germline mutations in different components of the RAS–MAPK pathway that lead to activation of this signaling cascade. Of note, similar somatic activating mutations are found in a variety of benign and malignant tumors (e.g. BRAF or NRAS mutations in the majority of melanocytic nevi and melanomas; see Ch. 113) as well as epidermal/sebaceous nevi (see Ch. 62). Growth factor binding to receptor tyrosine kinases results in activated receptor complexes containing adapters such as Src homology 2 domaincontaining (SHC), growth factor receptor-bound 2 (GRB2), and GRB2-associated binding (Gab) proteins as well as SH2 domain-containing protein tyrosine phosphatase 2 (SHP2; encoded by PTPN11), which relays signals from activated receptors to RAS and deactivates negative regulators of RAS (e.g. Sprouty). The activated receptor complex recruits son of sevenless homolog 1 (SOS1), a guanine nucleotide exchange factor that increases levels of active RAS– guanosine triphosphate (GTP). In contrast, neurofibromin is a GTPase activating protein that promotes hydrolysis of RAS–GTP to RAS–guanosine diphosphate (GDP), which terminates signaling. *In vitro studies suggest a dominant negative effect, but the consequences could vary depending on the substrate, cell type, or developmental stage.

B



870

for X-linked disorders, functional mosaicism can result in skin lesions that follow the lines of Blaschko or have other mosaic distribution patterns. This occurs in female patients with X-linked dominant, malelethal disorders such as incontinentia pigmenti (NEMO mutations), CHILD (congenital hemidysplasia with ichthyosiform nevus and limb defects) syndrome (NSDHL mutations), Conradi–Hünermann–Happle syndrome (EBP mutations), and Goltz syndrome (PORCN mutations; see Fig. 55.7) as well as in female “carriers” of X-linked dermatoses such as hypohidrotic ectodermal dysplasia (EDA mutations; Fig. 55.10) and ichthyosis follicularis–atrichia–photophobia (IFAP) syndrome (MBTPS2; Fig. 55.11). The gene encoding steroid sulfatase escapes lyonization, explaining why skin lesions in a mosaic pattern are not observed in female carriers of X-linked recessive ichthyosis.

C

REVERTANT MOSAICISM Revertant mosaicism is a means of “natural gene therapy” in which a spontaneous secondary genetic phenomenon leads to rescue of a disease-causing mutation, allowing a mosaic clone of heterozygous cells to regain wild-type (“normal”) function33. It has been described most often in patients with EB (see Ch. 32), potentially explaining the tendency of some forms of this condition to improve with age. A growth advantage and selective pressures (e.g. blistering) may help to increase the number of revertant cells over time. Revertant mosaicism via mitotic recombination accounts for the numerous small “islands” of normal skin in a background of ichthyosiform erythroderma that characterize ichthyosis en confetti34. Affected individuals have specific

Fig. 55.7 Goltz syndrome (focal dermal hypoplasia). A Hyperpigmented macules and dermal atrophy with fat “herniation” on the posterior thigh. B Raspberry-like papillomas on the lower lip. C Ectrodactyly.  

Hypotrichosis simplex

WNT10A-related EDs (ODDD, SSP)

Anonychia congenita PPK with SCC & sex reversal

APCDD1

R-spondin

Frizzled DSH

Gardner syndrome

Isolated AR nail dysplasia

APC

CHAPTER

55 Genetic Basis of Cutaneous Diseases

WNT/β-CATENIN SIGNALING PATHWAY DEFECTS IN GENODERMATOSES

β-Catenin PORCN

Goltz syndrome Target genes

A ER

WNT

Gene expression leading to cell proliferation, differentiation, migration and adhesion Nucleus

Fig. 55.6 WNT/β-catenin signaling pathway defects in genodermatoses. The porcupine homolog (PORCN) O-acyltransferase in the endoplasmic reticulum (ER) palmitoylates WNT proteins, facilitating their secretion. Extracellular WNT binds to the frizzled transmembrane receptor, which activates dishevelled (DSH), a cytosolic protein that inhibits the “destruction complex” (containing the adenomatous polyposis coli [APC] tumor suppressor protein) that mediates proteasomal degradation of β-catenin. As a result, β-catenin accumulates and is translocated to the nucleus, where it induces the transcription of genes that lead to cell proliferation, differentiation, migration and adhesion. APC downregulated 1 (APCDD1) can inhibit WNT signaling. R-spondins are other secreted proteins that bind to frizzled and activate the WNT/β-catenin pathway. AR, autosomal recessive; EDs, ectodermal dysplasias; ODDD, odonto-onychodermal dysplasia; PPK, palmoplantar keratoderma; SCC, squamous cell carcinoma; SSP, Schöpf–Schulz–Passarge syndrome.  

frameshift mutations in the KRT10 gene, which produce mutant proteins with an arginine-rich C-terminus that redirects them to the nucleolus; this mislocalization may have a role in promoting the reversion.

B

CHROMOSOMAL DISORDERS Chromosomal disorders represent abnormalities in the number or structure of chromosomes. Aneuploidy refers to having an additional or missing chromosome; examples that are compatible with postnatal survival include complete trisomies for chromosomes 21 (Down syndrome; Fig. 55.12), 18 (Edwards syndrome) and 13 (Patau syndrome) as well as monosomy for the X chromosome (Turner syndrome) and XXY (Klinefelter syndrome) or XYY karyotypes. Mosaic aneuploidies or partial trisomies and monosomies due to duplications, deletions or translocations of portions of chromosomes can also occur. The cutaneous and extracutaneous features of several relatively common chromosomal disorders are presented in Table 55.9. Phylloid hypomelanosis, characterized by leaf-like hypopigmented patches (Fig. 55.13), usually results from mosaic trisomy 13. In contrast, hypo- or hypermelanotic streaks and swirls that follow the lines of Blaschko, occasionally with associated extracutaneous findings (e.g. “hypomelanosis of Ito”), can be caused by mosaicism for a wide variety of chromosomal aberrations (see Ch. 62).

C

INSIGHT INTO ACQUIRED SKIN DISORDERS PROVIDED BY THE STUDY OF GENODERMATOSES Inherited monogenic skin disorders can serve as models to improve our understanding of the pathogenesis of more common acquired skin diseases. For example, basement membrane proteins that are defective

871

Fig. 55.8 Skin disease due to fibroblast growth factor receptor 3 (FGFR3) defects. A Severe acanthosis nigricans in a patient with the Crouzon craniosynostosis syndrome. B Systematized epidermal nevus in a young boy who had developmental delay. These conditions can be caused by germline and mosaic FGFR3 mutations, respectively. A, Courtesy,

Fig. 55.10 Female “carriers” of X-linked hypohidrotic ectodermal dysplasia. A The skin within hyperpigmented streaks and swirls following the lines of Blaschko is slightly depressed and very smooth, in contrast to follicular prominence in the surrounding areas. Starch-iodine testing on the back disclosed a patchy distribution of active sweat glands. This 2-year-old girl also had whorled areas of sparse hair on the posterior scalp and several cone-shaped teeth. B A color thermogram demonstrates an asymmetric distribution of skin temperature on the anterior trunk. B, From



SECTION

Genodermatoses

9



Seth J Orlow, MD, PhD.

A

A

Clark RP, Goff MR, MacDermot KD. Identification of functioning sweat pores and visualization of skin temperature patterns in X-linked hypohidrotic ectodermal dysplasia by whole body thermography. Hum Genet. 1990;86:7–13.

B

B

Fig. 55.9 Type 2 segmental Hailey–Hailey disease. This 7-year-old girl had a history of recurrent blistering on the right abdomen, groin and thigh since infancy.  

872

in JEB (e.g. type XVII collagen [bullous pemphigoid antigen 2], laminin 332 subunits) and dystrophic EB (type VII collagen) are also targeted in autoimmune blistering diseases such as bullous pemphigoid, mucous membrane (cicatricial) pemphigoid, and EB acquisita (see Ch. 28). The excessive granulation tissue that develops due to a truncated laminin α3 subunit in patients with laryngo-onycho-cutaneous syndrome has also provided clues to the role of this protein in regulating angiogenesis and granulation tissue formation during normal wound healing. Likewise, observation of similar dermal hyalinization in the rare genodermatosis lipoid proteinosis and lichen sclerosus led to the discovery of autoantibodies against extracellular matrix protein 1, the protein that is defective in the former disorder, in the majority of patients with lichen sclerosus35. In addition, investigation of monogenic type I interferonopathies such as Aicardi-Goutières syndrome, familial chilblain lupus, and STING-associated vasculopathy with onset in infancy (SAVI; see Ch. 45) that are caused by abnormal processing of and immune responses to nucleic acids has provided pathogenic insights and potential targeted therapeutic approaches for lupus erythematosus and dermatomyositis35a,35b. Loss-of-function variants in the gene that encodes filaggrin, the protein that aggregates keratin filaments during keratinocyte terminal

Fig. 55.13 Phylloid hypomelanosis due to mosaic trisomy 13. This condition is characterized by leaf-like and oblong patches of hypopigmentation in a pattern reminiscent of a floral ornament. Courtesy,  

55 Genetic Basis of Cutaneous Diseases

Arne König, MD, and Rudolf Happle, MD.

CHAPTER

Fig. 55.11 Ichthyosis follicularis with atrichia and photophobia (IFAP) syndrome. Note the confluent psoriasiform plaques on the scalp.  

Fig. 55.12 Cutaneous manifestations of Down syndrome (trisomy 21). A Full lips with cheilitis and a protruding, fissured tongue. B Multiple facial syringomas.  

differentiation (see Ch. 56), not only cause ichthyosis vulgaris but also represent a major predisposing factor for atopic dermatitis, with a significantly higher prevalence (20–50%) in individuals with atopic dermatitis compared to the general population (80% of the mass of the CE) and small proline-rich proteins (SPRRs) (3). Complexes of keratin and filaggrin also become cross-linked to the CE. In addition, proteases play important roles in processing of CE proteins and the proteolysis of corneodesmosomes that is required for desquamation. A mature, terminally differentiated cornified cell thus consists of keratin filaments covalently attached to the CE, which is composed of protein and lipid envelope components and imbedded in extracellular lipid lamellae. Defects in transglutaminases, lipid metabolism, CE structural proteins and proteases lead to a variety of diseases characterized by ichthyosis and/or keratoderma (1–3). CHILD, congenital hemidysplasia with ichthyosiform erythroderma and limb defects; LI, lamellar ichthyosis; CIE, congenital ichthyosiform erythroderma. Courtesy, Julie V Schaffer, MD.  

1 Initiation (spinous layer) Cell membrane Ca++

1

5

Ca++

LI/CIE

Acral peeling skin syndrome 2 Lamellar granule extrusion (granular layer)

1 Harlequin ichthyosis LI/CIE Defects of lipid metabolism X-linked ichthyosis (steroid sulfatase) LI/CIE (e.g. lipoxygenase-3 or -12R) Neutral lipid storage disease (ABHD5) Sjögren−Larsson syndrome (fatty aldehyde dehydrogenase) Refsum disease (phytanoyl-CoA hydroxylase) CHILD syndrome (3β-hydroxysteroid dehydrogenase) Conradi−Hünermann−Happle syndrome (3β-hydroxysteroid ∆8, ∆7 isomerase)

CHAPTER

56 Biology of Keratinocytes

FORMATION OF THE CORNIFIED CELL ENVELOPE (CE)

3 Reinforcement and lipid envelope formation (upper granular layer/interface with cornified layer)

1 5

Ichthyosis vulgaris

3

Vohwinkel syndrome Progressive symmetric erythrokeratoderma

Protease-related defects Netherton syndrome (serine protease inhibitor LEKT 1) Papillon−Lefèvre syndrome (cathepsin C)

Loricrin

Desmosome

Involucrin

Fatty acids, cholesterol

Keratin 1, 2, 10

Cross-link

Filaggrin

Periplakin

Transglutaminases

ABCA 12 lipid transporter

ω-OH-ceramide

Small proline-rich proteins (SPRRs)

Envoplakin

1

3

5

involucrin, small proline-rich proteins (SPRR), XP-5/late envelope proteins (LEP), loricrin, cystatin, envoplakin, periplakin, elafin, repetin, filaggrin, S100 proteins, keratins, and desmosomal proteins. Note that mutations in some of the genes that encode these proteins can lead to skin disorders (see below). The extracellular surface of the CE is covered by lipids, which form the cornified lipid envelope (CLE) (see Ch. 124). Keratinocytes that have assembled the CE/CLE and lost their nucleus and cytoplasmic organelles are termed corneocytes. These cell remnants constitute the stratum corneum, which serves to cover the body

surface of terrestrial mammals. The CE and CLE are major contributors to the cutaneous water barrier. Failure or impairment of the water barrier leads to increased transcutaneous water loss and an increased susceptibility to infections, a major problem in premature infants and in disorders such as Netherton syndrome. CE assembly begins within the upper spinous and granular cell layers, where proteins are chemically cross-linked, primarily by ε-(γ-glutamyl) lysine isopeptide bonds (Fig. 56.3). This reaction is catalyzed by a class of enzymes termed transglutaminases (TGases). Loss-of-function mutations in the gene that encodes TGase 1 lead to lamellar ichthyosis

877

Fig. 56.3 Transglutaminase catalysis of isopeptide bond formation between proteins. Transglutaminases (TGs) are calcium-dependent enzymes that catalyze the formation of γ-glutamyl lysine isopeptide bonds between proteins. TGs also have a role in the creation of ester bonds between proteins and ω-hydroxyceramides. Such cross-linking is essential for assembly of the CE. Four TGs are expressed in the epidermis: TG1 (keratinocyte TG; membrane-bound), TG2 (tissue TG; basal layer), TG3 (epidermal TG; hair follicle and terminally differentiating keratinocytes) and TG5 (upper epidermis). Courtesy, Julie V Schaffer, MD.  

TRANSGLUTAMINASE CATALYSIS OF ISOPEPTIDE BAND FORMATION BETWEEN PROTEINS

SECTION

9

Genodermatoses

Protein 1

Protein 1

(CH2)2

Glutamine residue

C=O

+

(CH2)2 TG

C=O

+Ca2+

NH2

NH2

(CH2)4

NH

Lysine residue

NH3

Isopeptide bond

(CH2)4 Protein 2

Protein 2

TYPES OF INTERMEDIATE FILAMENTS

Type I

Type II

Type III

Type IV

Type V

Others

Keratins (acidic)

Keratins (basic)

Vimentin Desmin GFAP Peripherin

Neurofilament-L Neurofilament-M Neurofilament-H α-Internexin Syncoilin Nestin Synemin

Lamin A/C Lamin B1 Lamin B2

Filensin Phakinin

Table 56.1 Types of intermediate filaments. GFAP, glial fibrillary acidic protein; L, M and H, low-, medium- and high-molecular-weight.  

PREVIOUS AND CURRENT HUMAN KERATIN NOMENCLATURE

Type I

Type II

Previous name

Current name

Previous name

Current name

Previous name

Current name

Previous name

Current name

KRT9

KRT9

KRT25irs1

KRT25

KRT1

KRT1

KRT6hf

KRT75

KRT10

KRT10

KRT25irs2

KRT26

KRT2e

KRT2

KRT2p

KRT76

KRT12

KRT12

KRT25irs3

KRT27

KRT3

KRT3

KRT1b

KRT77

KRT13

KRT13

KRT25irs4

KRT28

KRT4

KRT4

KRT5b

KRT78

KRT14

KRT14

Ha1

KRT31

KRT5

KRT5

KRT6I

KRT79

KRT15

KRT15

Ha2

KRT32

KRT6a

KRT6a

KRTb20

KRT80

KRT16

KRT16

Ha3-I

KRT33a

KRT6b

KRT6b

Hb1

KRT81

KRT17

KRT17

Ha3-II

KRT33b

KRT6e/h

KRT6c

Hb2

KRT82

KRT18

KRT18

Ha4

KRT34

KRT7

KRT7

Hb3

KRT83

KRT19

KRT19

Ha5

KRT35

KRT8

KRT8

Hb4

KRT84

KRT20

KRT20

Ha6

KRT36

KRT6irs1

KRT71

Hb5

KRT85

KRT23

KRT23

Ha7

KRT37

KRT6irs2

KRT72

Hb6

KRT86

KRT24

KRT24

Ha8

KRT38

KRT6irs3

KRT73









KRTa35

KRT39

KRT6irs4

KRT74









KRTa36

KRT40









Table 56.2 Previous and current human keratin nomenclature. Darker shading indicates keratins with names that were changed. irs, inner root sheath; Ha, type I hair keratins; Hb, type II hair keratins. From Schweizer J, Bowden PE, Coulombe PA, et al. J Cell Biol. 2006;174:169–74.  

878

and congenital ichthyosiform erythroderma, generalized skin disorders resulting from a failure to form proper CEs. Because the CE is highly resistant to chemical attack, very harsh conditions (e.g. boiling the epidermal cells in buffers containing high concentrations of detergents) are required to isolate and purify CE proteins. One surprising finding is that a loss of individual CE components in knockout mice does not necessarily have a major impact on barrier function. One possible explanation for this unexpected result is the presence of compensatory gene regulatory pathways that maintain barrier function even in the absence of major CE components3. Better

characterization of these regulatory pathways will provide insights into how the barrier is established and maintained, hopefully leading to the development of new strategies for the treatment of diseases caused by impaired barrier function.

KERATIN INTERMEDIATE FILAMENTS Keratin intermediate filaments provide resilience to keratinocytes, the most abundant cell type in the epidermis. Keratins represent

Keratins and Signaling Keratins are markers for keratinocyte differentiation and are required to maintain epidermal integrity. However, intermediate filaments may also influence other basic cell functions, such as cell cycle progression, metabolic activity, apoptosis, and migration. The mechanisms by which keratins regulate these processes are not well understood. However, accumulating evidence suggests that intermediate filaments directly interact with and regulate several key cell signaling pathways, including TNF receptor 2-induced apoptosis, Src-mediated migration, and Akt/mTOR-related growth6. Interestingly, deletion of the entire murine type II keratin gene cluster, which completely prevented the assembly of keratin intermediate filaments, resulted in an early embryonic lethal phenotype associated with growth retardation and defects in yolk sac hematopoiesis and vasculogenesis7. This underscores the importance of keratins to cellular signaling and differentiation of a non-epithelial cell lineage.

CHAPTER

56 Biology of Keratinocytes

the largest group of intermediate filament proteins (Table 56.1). The current classification system includes 54 human keratin genes (Table 56.2), which can be divided into three categories: (1) epithelial keratin genes; (2) hair keratin genes; and (3) keratin pseudogenes4. Based upon their biochemical properties (e.g. isoelectric point, molecular weight), keratins are also classified as either type I (KRT9– KRT28, KRT31–KRT40) or type II (KRT1–KRT8, KRT71–KRT86) (see Table 56.2). Type I and type II keratins form obligatory heteropolymers (i.e. pairs composed of one keratin from each group) that become the basic building blocks of epithelial intermediate filaments (Fig. 56.4). Keratins have a common domain structure that they share with other intermediate filament proteins5. The central α-helical rod domain consists of 310 amino acid residues and is divided into four segments (1A, 1B, 2A, 2B), which are interrupted by three non-helical segments of variable lengths, termed linkers (Fig. 56.5). The rod domain is composed of seven-residue amino acid sequence repeats (a-b-c-d-e-f-g)n termed “heptad repeats”, where positions “a” and “d” represent hydrophobic residues that are considered crucial for stabilization of the heterodimer. In the middle of the 2B domain, the heptad pattern is interrupted, giving rise to the “stutter”. This helical segment is highly conserved among intermediate filaments and does not participate in the formation of the coiled-coil dimer that forms the basic building block of intermediate filaments (see Fig. 56.4). The beginning and end of the α-helical rod domain, referred to as the helix initiation and helix termination motifs, are highly conserved among the different keratins and play a pivotal role in keratin intermediate filament assembly (e.g. filament elongation). These helix boundary peptides represent genetic “hot spots” for mutations in many of the hereditary keratin disorders (see Fig. 56.5). The severity and other phenotypic features of genodermatoses caused by keratin defects often correlate with the position of the underlying mutation, with more severe disease resulting from mutations in the helix initiation and termination motifs (see Table 56.4).The head and tail regions that flank the rod domain are subdivided into extreme end (E), variable (V), and (in type II keratins) homologous (H) domains. Whereas epithelial keratins possess glycine- and serine-rich head and tail domains, these regions have a high content of cysteine and proline in hair keratins. Variations in the head and tail domains account for much of the diversity among different keratin proteins, which suggests that these domains play an important role in cell type-specific functions.

Hair Keratins The mature hair is the differentiation product of trichocytes and is found within the central core of the hair follicle. The anagen (growing) follicle is a complex structure consisting of eight distinct, concentrically arranged cell layers (see Ch. 68). The innermost compartment is the hair shaft, which is composed of a medulla, cortex, and one-layered cuticle; the latter serves as a protective coat for the hair shaft. The innermost living cell layer of the hair follicle is the inner root sheath (IRS); it surrounds the growing hair shaft and consists of the IRS cuticle as well as Huxley and Henle layers. The outermost compartment is the outer root sheath (ORS), which is continuous with the interfollicular epidermis. The companion layer is located between the IRS and the ORS. The medulla contains a mixture of epithelial keratins (KRT17, KRT75) and hair keratins (KRT33, KRT34, KRT36, KRT37, KRT81), whereas the cortex contains type I hair keratins (KRT31–KRT38) and type II hair keratins (KRT81, KRT83, KRT85 and KRT86) (Fig. 56.6). Hair keratins KRT32 and KRT35 and their partners KRT82 and KRT85 are found in the cuticle, and the three IRS layers can be detected with antibodies against KRT71, KRT74, and KRT73. The epithelial keratins KRT5 and KRT14 are found throughout the full thickness of the ORS, while expression of KRT6, KRT16, and KRT17 is limited to the isthmus and the lower ORS. Additional keratins expressed in the ORS are KRT15 and KRT19. Fig. 56.4 Alignment and assembly of keratin molecules and keratin filament packing. Intermediate filament assembly takes place in several stages and begins with the heterodimerization of one type I and one type II keratin protein in a coiled-coil fashion. Two heterodimers then associate to form a tetramer. Lateral aggregation of tetramers yields higher-order polymers which eventually make up the filament network of the keratinocyte. Courtesy,  

ALIGNMENT AND ASSEMBLY OF KERATIN MOLECULES AND KERATIN FILAMENT PACKING

NH2

COOH

NH2

COOH

NH2 NH2

COOH COOH Head

COOH COOH COOH COOH

Rod

α-Helix, type I, acidic (K9−K20) α-Helix, type II, basic (K1−K8) Parallel dimer

Julie V Schaffer, MD.

Tail NH2 NH2

Antiparallel NH2 tetramer NH2

Keratin filament packing

K used in place of KRT for simplicity

879

Fig. 56.5 Primary sites of keratin mutations and associated skin diseases. Over 90% of pathogenic alterations in keratins are missense mutations. Genotype-phenotype correlations are particularly well established for EBS. In the generalized severe form of EBS, many patients have a “hot spot” mutation in a highly conserved arginine (Arg125) located within the helix initiation motif of KRT14. The corresponding arginine (Arg156) in KRT10 is also a mutational “hot spot” in epidermolytic ichthyosis. In the generalized intermediate EBS subtype, mutations are more centrally located in the rod domains of KRT5 and KRT14. In contrast, mutations in the localized form of EBS are often outside the rod domain, e.g. in the L12 linker motifs of KRT5 and KRT14 or the H1 homologous subdomain of KRT5. Mutations in the variable head (V1) and tail (V2) domains of KRT1 can lead to non-epidermolytic PPK and ichthyosis hystrix Curth–Macklin. Rather than interfering with keratin intermediate filament assembly, mutations in these domains may cause intracellular maldistribution of loricrin. K or KRT, keratin; PPK, palmoplantar keratoderma. Courtesy, Julie V  

PRIMARY SITES OF KERATIN MUTATIONS AND ASSOCIATED SKIN DISEASES

SECTION

Genodermatoses

9

K used in place of KRT for simplicity

K1, K10 K2

epidermolytic ichthyosis superficial epidermolytic ichthyosis K5, K14 epidermolysis bullosa simplex (EBS) K6a, K16 pachyonychia congenita K6c non-epidermolytic PPK, pachyonychia congenita

**

K4, K13 white sponge nevus K9 epidermolytic PPK K17 pachyonychia congenita

K1 epidermolytic PPK

H1

V1

1A

1B

K1, K10 annular epidermolytic ichthyosis

2A

L1

K6b pachyonychia congenita

2B

L12

H2

V2

L2 K1

K5, K14 EBS, localized

ichthyosis hystrix of Curth−Macklin Striate PPK K10>1 ichthyosis with confetti K5 EBS, migratory circinate

variable head (V1) and tail (V2) domains homologous subdomains (type II keratins only) helix initiation and termination motifs

α-helical rod domains linker segments (non-helical) stutter sequence (reversal of helix polarity)

K1 non-epidermolytic PPK K5 EBS with mottled pigmentation Dowling−Degos disease K14 Naegeli−Franceschetti− Jadassohn (NFJ) syndrome

*

Schaffer, MD.

***

*

* Mutations lead to a premature termination codon; K14 mutations can also result in dermatopathia pigmentosa reticularis (related to NFJ) ** Especially in the generalized severe form *** Frameshift mutations result in an arginine-rich tail, which leads to nuclear mislocalization and revertant mosaicism due to mitotic recombination

Fig. 56.6 Complex pattern of hair keratin expression in the human anagen hair shaft. Major type I hair keratins are in blue, and major type II hair keratins are in green. Minor hair keratins are in pink. a This protein is weakly expressed at this site. bTo date, expression of this protein has only been detected in single cortex cells. cTo date, this protein has only been detected in vellus hairs. Autosomal dominant monilethrix is caused by mutations in KRT81, KRT83, and KRT86. Redrawn from Langbein L, et al. The catalog of human  

COMPLEX PATTERN OF HAIR KERATIN EXPRESSION IN THE HUMAN ANAGEN HAIR SHAFT Type I

Type II

Cuticle

Matrix / Cortex

Cuticle

Cuticle

Cortex 7

K34

hair keratins. J Biol Chem. 2001;276:35123–32.

880

1

K31

K82

K32

K used in place of KRT for simplicity

Zones of mRNA synthesis

K85

K85

K35

2 K35

K32a

3

K85

K85

K35 K32

K31

K35 K32

K82

K38b

K38

4

Sequential expression of human hair keratins

5

K37

K86 K83 K81

K81 K83 K86

6

K33a K33b K36

K36 K33a K33b K37c

Start of mRNA synthesis

Sequential expression of human hair keratins

K34

Epidermal differentiation is a tightly regulated process that involves the transformation of proliferating cells in the basal layer into the dead corneocytes of the stratum corneum. During this process, the keratins that are expressed are highly specific for the state of differentiation (Fig. 56.7). The mitotically active keratinocytes in the basal compartment of the epidermis primarily express the keratin pair KRT5 and KRT14, with less abundant expression of KRT15. In the absence of KRT14, KRT15 can assemble with KRT5, thereby providing mechanical stability to the keratinocyte. As keratinocytes move suprabasally to the spinous layer, they withdraw from the cell cycle. This process is associated with a down-regulation of KRT5 and KRT14 and an induction of the differentiation-specific keratins, KRT1 and KRT10. Further maturation of spinous keratinocytes into granular keratinocytes results in expression of KRT2, a reinforcement keratin. With further maturation, filaments containing the suprabasal keratins are bundled parallel to the surface and, eventually, keratinocytes lose their cytoplasmic organelles and differentiate into lifeless corneocytes that are shed into the environment. Interestingly, a number of epidermal keratins have a more restricted anatomic distribution pattern. For example, KRT9 is specifically expressed in the suprabasal cells of palmoplantar skin. KRT6, KRT16, and KRT17 are expressed not only in the palmoplantar epidermis, but also in keratinocytes of the nail bed, hair follicle, and sebaceous and sweat glands. In addition, this group of keratins is rapidly induced by injury and ultraviolet radiation, as well as in hyperproliferative conditions8.

Regulatory Pathways Involved in Epidermal Development and Differentiation The regulatory pathways necessary for normal keratinocyte differentiation include those that: (1) establish and maintain basal keratinocytes; (2) initiate and execute terminal differentiation; and (3) form the stratum corneum. Examples of these pathways are discussed in more detail below.

Genes required for establishing and maintaining basal keratinocytes The importance of the TP63 gene in epidermal development and differentiation became apparent following the generation of a knockout CYTOKERATIN EXPRESSION Suprabasal cells of stratified epithelia

K3

K12

Cornea

K4

K13

Non-cornified mucosa

K76

K12

Cornified mucosa K9

K2 K1 Basal cells of stratified epithelia

*

K10

**

K6a

K16

K6b

K17

Interfollicular epidermis

K15 K5

Fast turnover

K14 K19

Simple epithelia K8 K7

* **

K18 K20

only palmoplantar epidermis also palmoplantar epidermis and appendages

K used in place of KRT for simplicity

Fig. 56.7 Cytokeratin expression. Type II (basic) keratins are in yellow (KRT1–KRT8; KRT76) and type I (acidic) keratins are in blue (KRT9–KRT20). Keratin disorders are presented in Fig. 56.5 and Tables 56.3 & 56.5.  

**

mouse model9. The p63 protein encoded by this gene has at least six different isoforms that activate or repress transcription. Strikingly, p63null mice fail to initiate epidermal morphogenesis and are born with a single-layered epithelium covering their bodies rather than a stratified epidermis. After birth, exposure of these mice to the environment leads to a rapid death due to dehydration. The failure of p63-deficient epithelial cells to adopt an epidermal fate highlights the critical role of p63 in specifying epidermal lineage. The p63 protein regulates the transcription of multiple genes in basal keratinocytes. For example, p63 induces expression of epidermal keratins KRT5 and KRT14 while simultaneously repressing expression of KRT18, a keratin expressed in single-layered epithelia. Another key function of p63 is to help maintain the proliferative state of basal keratinocytes by repressing the expression of cell cycle inhibitors.

Genes required for terminal differentiation in mature epidermis

CHAPTER

56 Biology of Keratinocytes

EPIDERMAL DIFFERENTIATION

After basal keratinocytes have undergone a few rounds of cell division, they irreversibly withdraw from the cell cycle, move suprabasally, and become spinous keratinocytes. This process is also regulated by p63, in particular its ΔNp63α isoform9. In this context, p63 synergizes with Notch signaling to induce expression of KRT1. Simultaneously, p63 mediates the cell cycle exit that is necessary for keratinocyte differentiation. The importance of p63 for normal epidermal development and differentiation is further underscored by the finding that p63 mutations underlie a subset of ectodermal dysplasias, which are characterized by abnormalities in the skin and skin appendages (see Ch. 63). The Notch signaling pathway is also required for the formation of the spinous layer10. In mouse models, ablation of Notch signaling resulted in the development of an extremely thin spinous layer, whereas constitutively active Notch signaling resulted in an expansion of the spinous layer. Notch activity promotes terminal differentiation by inducing KRT1 expression and mediating cell cycle withdrawal.

Ca2+ in epidermal differentiation

In addition to signaling via p63 and Notch, an important trigger of keratinocyte differentiation is an increase in extracellular Ca2+ concentration11. In mature epidermis, there is a gradient of increasing extracellular Ca2+ concentration from the basal layer to the cornified layer. Increasing the Ca2+ concentration in the media of cultured keratinocytes can induce a differentiation program indistinguishable from that of keratinocytes in vivo, with successive expression of markers of keratinocyte terminal differentiation12. Several Ca2+-responsive proteins in the epidermis have key roles in the formation of the granular cell layer13. For example, the protein kinase C (PKC) family of proteins is activated by Ca2+ signaling and functions specifically in the transition from spinous to granular cells. PKC proteins have a dual role, contributing to the down-regulation of KRT1 and KRT10 expression as well as the induction of markers of granular keratinocytes such as loricrin, filaggrin, and transglutaminases. In addition to the PKC family, other proteins that undergo conformational changes upon binding to Ca2+ are expressed in mouse and human epidermis. Of these, the calcium-sensing receptor is specifically expressed in granular keratinocytes. Mice lacking the full-length form of the calcium-sensing receptor fail to properly form a granular layer, while overexpression of the calcium-sensing receptor in basal keratinocytes causes expanded spinous and granular cell layers14.

Genes required for terminal differentiation in embryonic epidermis Whereas the signaling pathways discussed above are critical for the formation of the spinous layer in postnatal skin, the molecular mechanisms that underlie the development of a spinous layer during epidermal morphogenesis appear to be different15. One reason for this distinction is that during epidermal morphogenesis, basal keratinocytes do not directly differentiate into spinous keratinocytes. Instead, basal keratinocytes initially differentiate into intermediate keratinocytes that, like spinous cells, express KRT1. However, unlike spinous keratinocytes, intermediate keratinocytes still undergo proliferation. The intermediate cell layer exists only transiently during epidermal morphogenesis, and intermediate keratinocytes ultimately differentiate into

881

SECTION

Genodermatoses

9

spinous and granular keratinocytes, which then undergo further terminal differentiation. The importance of the intermediate cell layer for normal epidermal development has been demonstrated by mouse models in which intermediate cells fail to mature into spinous and granular cells. Such a block in differentiation occurs in mice lacking expression of inhibitor of κB kinase-α (IKKα), interferon regulatory factor 6 (IRF6), or ovo-like 1 (Ovol1), as well as in mice expressing a mutant form of the 14–3–3σ protein15. In all instances, an expanded intermediate cell layer develops, further terminal differentiation is disrupted, and the consequent failure to establish barrier function results in neonatal lethality.

KERATINOCYTE ADHESION Desmosomes Desmosomes are multi-protein complexes that function as cell–cell adhesion structures (junctions) in epidermal cells16 (Fig. 56.8). They also provide attachment sites for the keratin intermediate filament cytoskeleton of keratinocytes. Consequently, these junctions are critical components of a supracellular filament network that traverses the interfollicular epidermis and the epithelia of skin appendages, such as hair follicles17. Although the biochemical composition of desmosomes varies from tissue to tissue, the core of the desmosome is formed mainly by transmembrane glycoproteins that belong to the desmoglein (Dsg) and desmocollin (Dsc) subfamilies of Ca2+-dependent cell adhesion proteins (cadherins). Heterophilic and homophilic interactions between Dsg and Dsc proteins are thought to be required to establish cell–cell coupling (see Ch. 29)18,19. Another protein, termed “Perp”, is also crucial for this process20. The transmembrane proteins are linked to the keratin intermediate filament network via a complex of several proteins, including desmoplakin, plakoglobin, one of several plakophilin (Pkp) isoforms, and often additional accessory proteins21,22. To complicate matters, several desmosomal components are encoded by multigene families. In humans, for example, there are four DSG

genes, three DSC genes, and three PKP genes. In the epidermis, several Dsg and Dsc isoforms can be present in the same cell and even in the same desmosome. It is assumed that the specific composition of the desmosome affects its adhesive properties. Regulating adhesiveness of junctions via changes in the protein composition or through protein modifications is considered to be a crucial prerequisite for regulating cell migration, cell sorting, and the formation of the proper tissue histoarchitecture during embryonic development. One example of differential regulation of desmosomes within the context of tissue/organ development is the formation of skin appendages, such as hair follicles and mammary glands. Regardless of the type of appendage that is being formed, the initial steps are very similar. First, keratinocytes from the basal cell layer change their polarity and down-regulate desmosomal proteins23. Next, these cells break through the basement membrane and invade the underlying dermal tissue. Eventually, the cells begin to differentiate in order to form the various cell layers and tissues that constitute the new appendage. During this process, desmosomal adhesion is re-established. The molecular pathways that control differential expression of desmosomal genes during such developmental processes are not well understood. However, based on work focusing on the regulation of classical cadherins (e.g. E-cadherin), it is likely that major epidermal signaling pathways, such as the Wnt and NF-κB cascades, are involved (see Figs 55.6 and 62.4). Of note, the phenomenon of local proliferation of keratinocytes followed by invasion into dermal tissue also occurs in cutaneous wound healing and the initial stages of cancer progression. It is therefore likely that the same gene regulatory pathways that govern adnexal development also control these biological processes.

What happens when desmosomes do not function properly? Tissues that are exposed to a significant amount of mechanical stress, such as the skin and its appendages, mucous membranes (e.g. in the oral cavity) and the heart, are often affected by desmosomal defects. The clinical symptoms of desmosomal diseases typically reflect tissue

Fig. 56.8 Molecular organization of the desmosome and associated genodermatoses. Type 1 transmembrane glycoproteins from the cadherin family (desmogleins and desmocollins) are linked to intermediate filaments via a complex that contains catenins (plakoglobin, plakophilins) and plakin proteins (desmoplakin). Both homophilic and heterophilic interactions have been postulated to participate in establishing desmosomal adhesion. Examples of inherited skin diseases affecting the components of desmosomes are shown. AR, autosomal recessive; PPK, palmoplantar keratoderma.  

MOLECULAR ORGANIZATION OF THE DESMOSOME AND ASSOCIATED GENODERMATOSES

Dsg1: Striate PPK Severe dermatitis, allergies & metabolic wasting (SAM) Dsg4: Localized AR hypotrichosis AR monilethrix

Striate PPK Carvajal syndrome Skin fragility/woolly hair syndrome Acantholytic EBS SAM

*

**

Intercellular space

Hypotrichosis simplex of the scalp Inflammatory peeling skin syndrome

N N N N N N N N

Keratin Dsg Dsc

C C

CD

JUP DP

PKP1: Skin fragility− ectodermal dysplasia syndrome

PKP Dsg Dsc

C C

**

DP JUP

Dsc2: PPK, woolly hair & cardiomyopathy Dsc3: Hypotrichosis & skin lesions

Desmoglein (Dsg) Desmocollin (Dsc) Plakoglobin (JUP) Plakophilin (PKP) Desmoplakin (DP) Corneodesmosin (CD)

882

*

Naxos disease Cardiomyopathy with alopecia & PPK Acantholytic EBS

* Features triad of PPK, woolly hair and cardiomyopathy fragility syndrome classified as a form of ** Skin epidermolysis bullosa simplex (EBS)

fragility, with mucocutaneous blistering and cardiomyopathy representing major manifestations16,24. In fact, skin and/or heart diseases have been linked to dysfunction of at least 12 desmosomal proteins, including Dsc1–3, Dsg1–4, desmoplakin, plakoglobin, plakophilin 1–2, and corneodesmosin (see Fig. 56.8). These disorders include genodermatoses, autoantibody-mediated diseases such as pemphigus vulgaris (PV) and pemphigus foliaceus (PF), and bacterial toxin-induced staphylococcal scalded skin syndrome25. The first mucocutaneous disorders linked to a desmosomal defect were PV and PF (see Ch. 29). In these diseases, autoantibodies bind to Dsg and induce epidermal and/or mucous membrane blistering via acantholysis, a process thought to be caused by loss of Dsg. In contrast to the blisters observed in patients with epidermolysis bullosa simplex due to keratin mutations, PV and PF blisters are caused by cell–cell separation, not cytolysis. Nevertheless, both groups of diseases illustrate the point that desmosomes and the associated keratin intermediate filaments must function properly in order to maintain tissue integrity. Besides their ability to stabilize tissues, desmosomes also function as signaling centers, for example, by controlling the cytoplasmic pool of signaling molecules. In fact, certain features of pemphigus are caused by abnormal signaling through the desmosomes that are targeted by autoantibodies16. Diminished function of desmosomal proteins may also lead to abnormal distribution of gap junction proteins, thus contributing to the development of cardiomyopathy in patients with mutations in desmosomal genes26. These findings support the emerging picture that desmosomes are highly dynamic structures that actively participate in signal transduction. Plakoglobin (also known as junction plakoglobin) is a core component of desmosomes that is involved in relaying signals to the nucleus. This protein belongs to the armadillo protein family, the prototype of which is β-catenin. Plakoglobin binds desmosomal cadherins (Dsg, Dsc) at the plasma membrane (see Fig. 56.8). However, it can also form complexes with Tcf/Lef transcription factors and thus control gene expression within the nucleus. Furthermore, plakoglobin can influence other cell properties, such as proliferation, migration, and apoptosis16. Plakophilins can also affect cytoplasmic signaling pathways, and at least two isoforms (Pkp1, Pkp2) have nuclear functions21.

pathway, plakoglobin appears to be able to signal either via Wnt components or independently. Interestingly plakoglobin counteracts classical Wnt signaling in at least two cell types28.

Other Types of Cell Junctions

Keratin Disorders

In addition to desmosomes, several other morphologically and biochemically defined cell junctions are found in keratinocytes, including adherens junctions and tight junctions17.

Mutations in keratin genes cause a variety of disorders of the skin and other epithelia, usually with an autosomal dominant pattern of inheritance. The underlying mutations typically act in a dominant-negative fashion, interfering with normal intermediate filament assembly. This causes aggregation of disorganized keratin bundles, which often leads to clinically evident cell fragility. As noted above, mutations in the helix

Adherens junctions Adherens junctions consist of classical cadherins, in particular E- and P-cadherin, as well as a complex of cytoplasmic plaque proteins (α-catenin, β-catenin, γ-catenin [also known as plakoglobin]) that connect the transmembrane proteins to the actin microfilament cytoskeleton (see Fig. 29.3A). Note that the armadillo protein plakoglobin can bind to both desmosomal and classical cadherins (see above). P-cadherin is expressed primarily in the basal layer of mouse epidermis, whereas E-cadherin is expressed throughout the interfollicular epidermis. A genetically engineered loss of P-cadherin in mice has little effect on the interfollicular epidermis, although it does affect the mammary gland. On the other hand, loss of E-cadherin in epidermisspecific (conditional) null mice can lead to severe defects in the homeostasis and function of the epidermis. Interestingly, it appears that loss of E-cadherin can affect tight junctions (see below) and thus the skin barrier function of the epidermis. Based on an analysis of genetically engineered mice, it has become evident that normal expression of the plaque proteins α-catenin, β-catenin, and plakoglobin is also required for normal epidermal function. Similar to desmosomal cadherins, classical cadherins are differentially regulated during development of skin appendages27. For example, E-cadherin is down-regulated in keratinocytes that invade the underlying dermis. A failure to down-regulate cadherin-based adhesion appears to suppress invasive growth of keratinocytes and thus appendage formation. As indicated above, armadillo proteins (e.g. β-catenin, plakoglobin) are involved in signaling from cell junctions to the nucleus. While β-catenin is a downstream effector of the classical (canonical) Wnt

Tight junctions

CHAPTER

KERATINOCYTE–MATRIX INTERACTIONS

56 Biology of Keratinocytes

Together, tight junctions (zonula occludens), adherens junctions, and desmosomes form the apical junctional complex in polarized epithelial cells. Tight junctions are thought to “seal” the intercellular space, thus preventing the free diffusion of macromolecules. Consequently, these junctions are crucial for maintaining a barrier between two compartments. Tight junctions in the granular layer form a seal that is required for maintaining the water barrier function of the epidermis (see Fig. 124.1)29.

The epidermis is separated from the underlying dermis by a basement membrane (see Ch. 28), which consists of proteins secreted by epidermal keratinocytes and dermal fibroblasts30. The main components of the skin basement membrane are glycoproteins, including laminins, collagens, proteoglycans, and fibronectin. Keratinocytes are anchored to the basement membrane through integrins, transmembrane receptors for extracellular matrix proteins (Table 56.3). In addition to their structural role, integrins function by transducing signals from the extracellular matrix to the epidermal keratinocytes. Another family of proteins that is required for basement membrane integrity during embryogenesis consists of Fras1, Frem1 and Frem2, three proteins that form a complex within the basement membrane. Loss-of-function mutations in any of these three genes result in a destabilization of the protein complex, causing aberrant basement membrane formation and consequent skin blistering in mouse models. In humans, loss-of-function mutations in the FRAS1 or FREM2 genes underlie Fraser syndrome, a multisystem autosomal recessive disorder characterized by embryonic (but not postnatal) blistering of the skin, cutaneous syndactyly, cryptophthalmos, and renal defects31.

RELATED DISEASES

KERATINOCYTE INTEGRIN RECEPTORS

Integrin

Ligand

β1 family α1β1

Fibrillar collagen, laminin

α2β1

Fibrillar collagen, laminin

α3β1

Fibronectin, laminin 332 (formerly laminin 5), denatured collagen

α5β1

Fibronectin

α6β1

Laminin

β4 family α6β4

Laminin 332

αv family αvβ1

Fibronectin, vitronectin

αvβ3

Vitronectin, fibronectin, fibrinogen, denatured collagen

αvβ5

Vitronectin

αvβ6

Fibronectin, tenascin

Table 56.3 Keratinocyte integrin receptors. Courtesy, Irene M Leigh, MD.  

883

SECTION

Genodermatoses

9

initiation and termination motifs are generally associated with relatively severe disease phenotypes, whereas mutations affecting other keratin domains usually cause milder disease (see Fig. 56.5). The location of mutations and genetic “hot spots” in skin disorders caused by mutations in keratin genes are presented in Table 56.4.

Epidermolysis bullosa simplex Epidermolysis bullosa (EB) comprises a group of heritable skin fragility disorders characterized by skin blistering following minor mechanical trauma (see Ch. 32). In the simplex form of EB (EBS), tissue separation is within the epidermis. According to a revised classification, EBS is divided into two major subtypes: (1) suprabasal, which can be caused by mutations in genes encoding desmosomal components (see above and Fig. 56.8) and often features acantholysis histologically; and (2) basal, where the cleavage plane is within basal keratinocytes32. Genotype–phenotype correlations are well established for basal EBS due to KRT5 and KRT14 mutations (see Table 56.4 and Fig. 56.5). The clinical severity is related to the location of the mutations and the degree to which they perturb keratin structure33. Interestingly, hyperpigmentation is a major feature of Dowling–Degos disease, Naegeli– Franceschetti–Jadassohn syndrome, and dermatopathia pigmentosa reticularis (disorders which do not feature prominent blistering; see Ch. 67) as well as EBS with mottled pigmentation, demonstrating that

mutations in keratin genes expressed in the basal epidermis can lead to pigmentary changes in addition to skin fragility.

Epidermolytic ichthyosis and palmoplantar keratoderma Epidermolytic ichthyosis (formerly bullous congenital ichthyosiform erythroderma) is a disorder of keratinization caused by mutations in KRT1 or KRT1034 (see Ch. 57). It is usually inherited in an autosomal dominant fashion due to heterozygous missense mutations (typically involving the helix initiation and termination motifs) that lead to clumping of keratin filaments in the suprabasal layers of the epidermis and subsequent cytolysis. A form of epidermolytic ichthyosis associated with PPK (mainly due to KRT1 mutations) can be distinguished from a form where palmoplantar involvement is absent (mainly due to KRT10 mutations). KRT1 mutations (outside of the critical helix initiation and termination regions) have also been identified in nonepidermolytic and epidermolytic variants of isolated PPK, which is more commonly caused by mutations in KRT935. A recessive form of epidermolytic ichthyosis characterized by a complete absence of the KRT10 protein in the epidermis has also been described in several families. Mutations in KRT1 or KRT10 that occur during embryogenesis can cause a mosaic form of epidermolytic ichthyosis, which presents as an epidermolytic epidermal nevus (see Ch. 62). Vertical transmission of the mutation is possible if the gonads are involved, causing

TYPES OF KERATIN MUTATIONS IN MUCOCUTANEOUS DISORDERS

Disorder

Inheritance

Gene(s)

Type/location of mutation(s)

EBS, localized

AD

KRT5, KRT14

L12; H1 of KRT5

EBS, generalized intermediate

AD

L12, L2; central portions of 1A & 2B

EBS, generalized severe

AD

Helix initiation & termination motifs; “hot spot” Arg125Cys/ His in KRT14

EBS, AR-KRT14

AR

Truncating or splice-site mutations

EBS with mottled pigmentation

AD

KRT5 ≫ KRT14

Pro25Leu in V1 of KRT5

EBS, migratory circinate

AD

KRT5

Frameshift mutation leading to extended V2 region

Dowling–Degos disease

AD

Naegeli–Franceschetti–Jadassohn syndrome & dermatopathia pigmentosa reticularis

AD

KRT14

V1 – truncating (leading to haploinsufficiency)

Epidermolytic ichthyosis

AD

KRT1, KRT10

Helix initiation & termination motifs; “hot spot” Arg156 in KRT10

AR

KRT10

2B – truncating

Annular/cyclic epidermolytic ichthyosis

AD

KRT1, KRT10

2B

Ichthyosis hystrix Curth–Macklin

AD

KRT1

V2 – truncated tail

Ichthyosis with confetti

AD

KRT10 ≫ KRT1

Frameshift mutations leading to arginine-rich tail; revertant clones via mitotic recombination

Superficial epidermolytic ichthyosis

AD

KRT2

Helix termination > initiation motifs

Epidermolytic PPK

AD

KRT1

1B (diffuse with “tonotubular” keratin), 2B (mild diffuse/ focal)

KRT9

Helix initiation > termination motifs, with “hot spot” Arg163

Non-epidermolytic PPK

AD

KRT1

V1 (diffuse), V2 (striate)

Pachyonychia congenita-6a & 16

AD

KRT6A, KRT16

Helix initiation > termination motifs

Pachyonychia congenita-6b & 16

AD

KRT6B, KRT17

Helix termination motif of KRT6B; helix initiation motif with “hot spots” Asn92 & Arg94 in KRT17

Pachyonychia congenita-6c & non-epidermolytic PPK (focal > diffuse)

AD

KRT6C

Helix termination > initiation motifs

Pseudofolliculitis barbae

Risk factor

KRT75

1A

Monilethrix

AD

KRT81, KRT83, KRT86

Helix termination (KRT86 > KRT81 > KRT83) & initiation (KRT86) motifs

“Pure” hair–nail type ectodermal dysplasia

AR

KRT85

V1 (more severe phenotype), V2

White sponge nevus

AD

KRT4, KRT13

Helix initiation > termination motifs

Table 56.4 Types of keratin mutations in mucocutaneous disorders. Also see Fig. 56.5. AD, autosomal dominant; AR, autosomal recessive; EBS, epidermolysis bullosa simplex; H1, homologous subdomain 1; KRT, keratin; L12/L2, linker segments (non-helical); PPK, palmoplantar keratoderma; V1, variable head domain; V2, variable tail domain; 1A/1B/2A/2B, α-helical rod domain segments.  

884

V1 – truncating (leading to haploinsufficiency)

Fig. 56.9 Filaggrin loss-of-function variants in ichthyosis vulgaris and atopic dermatitis. The filaggrin protein consists of several domains: an S100 Ca2+-binding domain (yellow oval), a B-domain (beige octagon), two imperfect filaggrin repeats (green rectangles), 10 filaggrin repeats (blue numbered rectangles; some individuals have two copies of repeat 8 and/or 10), and a C-terminal domain (yellow hexagon). Mutations in filaggrin that have been identified in patients with ichthyosis vulgaris and atopic dermatitis are indicated.  

3321delA

R501X

S2889X

S3296X

R2447X 2282del4

3702delG

S3247X Q2417X

1

2

3

4

5

6

R4307X

S2554X

7

8

9

10

European patients

CHAPTER

56 Biology of Keratinocytes

FILAGGRIN LOSS-OF-FUNCTION VARIANTS IN ICHTHYOSIS VULGARIS AND ATOPIC DERMATITIS

Japanese patients Chinese patients

generalized disease in affected offspring. The types of mutations in keratin disorders are outlined in Table 56.4.

White sponge nevus of Cannon White sponge nevus is characterized by white plaques involving the oral mucosa, with occasional involvement of other mucosal surfaces such as the esophagus, vagina, rectum, and nasal cavity. The plaques may wax and wane over time, and suprabasal cytolysis and keratin clumping are observed histologically. Mutations in the genes encoding KRT4 and KRT13, which are specifically expressed in mucosal keratinocytes, cause this condition.

Gastrointestinal disorders KRT8 and KRT18 are the major keratins that are expressed in gastrointestinal epithelia, including the liver, pancreas, and gut. Mutations in these simple keratins are typically located within the head and tail domains and do not involve the highly conserved helix boundary regions. KRT8 and KRT18 mutations are considered as risk factors for developing liver and gastrointestinal disorders (e.g. cirrhosis, inflammatory bowel disease), with additional genetic and environmental alterations likely required for disease development36. The mutationassociated predisposition to tissue injury is likely related to mechanical and non-mechanical keratin functions, including maintenance of cell integrity and protection from oxidative injury and apoptosis.

Filaggrin Deficiency Disorders Filaggrin is a component of the cornified cell envelope and is responsible for aggregating keratins. It represents the processed product of profilaggrin, which is cleaved into individual filaggrin polypeptides by caspase 14. Loss-of-function mutations in filaggrin underlie ichthyosis vulgaris (Fig. 56.9), a semidominant condition with incomplete penetrance (~90% in homozygotes and ~60% in heterozygotes)37 (see Ch. 57). Whereas patients with a heterozygous filaggrin mutation display mild scaling or no phenotype, those with homozygous or compound heterozygous mutations have more severe ichthyosis vulgaris with dry, scaly skin and a substantially altered cutaneous barrier.

In addition to ichthyosis vulgaris, loss-of-function mutations in filaggrin are also a major predisposing factor for atopic dermatitis. Approximately 20–50% of patients with atopic dermatitis have at least one filaggrin null allele. Furthermore, individuals who carry filaggrin mutations and develop atopic dermatitis are also predisposed to the subsequent onset of asthma. This suggests that epicutaneous sensitization and inflammation of the skin in the context of an abnormal epidermal barrier may play a role in later development of airway hyperreactivity (see Ch. 12).

Mouse Models for Structural and Desmosomal Proteins The generation of mouse models has significantly increased our understanding of skin biology and the pathophysiology of genodermatoses. Animals harboring mutational “hot spots” that have been identified in humans are also useful for testing novel disease-targeted treatments38 (Table 56.5). In the case of dominant-negative mutations, the mutant allele can potentially be silenced using short interfering RNA (siRNA) technology. Promising results were obtained in a reporter mouse model where non-invasive, pain-free administration of siRNAs into the skin was achieved via topical administration39. Such investigation in mouse models can help to bring new technologies closer to clinical use.

CONCLUSION We have made great progress towards understanding the structure and function of the epidermis. The challenge is now to better elucidate the gene regulatory mechanisms and cell signaling pathways that are required for the development and maintenance of this organ. The identification of epigenetic factors and modifier genes will help to explain phenotypic variations and establish more precise genotype– phenotype correlations. This knowledge will also form the foundation for the development of new therapeutic strategies for the treatment of acquired and inherited diseases of the skin.

885

MOUSE MODELS FOR HUMAN SKIN DISEASES DUE TO ABNORMALITIES IN STRUCTURAL AND DESMOSOMAL PROTEINS

Gene/protein SECTION

Genodermatoses

9

Human diseases

Genotype and phenotype of mouse models

Keratin 14

Epidermolysis bullosa simplex (EBS)

R125C: blistering due to collapse of keratin network in basal keratinocytes

Keratin 1

Epidermolytic ichthyosis (See also Fig. 56.5)

KO: perinatal lethality

Keratin 10

Epidermolytic ichthyosis (See also Fig. 56.5)

R156C: blistering at birth, hyperkeratosis later in life KO: severe blistering and hyperkeratosis

Keratin 2

Superficial epidermolytic ichthyosis

KO: localized hyperkeratosis (ear, tail)

Keratin 9

Epidermolytic PPK

KO: footpad calluses

Keratin 6a

Pachyonychia congenita-6a

KO: delayed wound healing N172del: nail dystrophy

Keratin 6b

Pachyonychia congenita-6b

KO: starvation due to upper GI constriction

Keratin 16

Pachyonychia congenita-16

KO: oral leukokeratosis, footpad calluses

Keratin 17

Pachyonychia congenita-17 Steatocystoma multiplex

KO: alopecia

Loricrin

Vohwinkel syndrome Progressive symmetric erythrokeratoderma

KO: transient neonatal erythroderma 372insC: neonatal erythrokeratoderma, tail constriction bands, footpad hyperkeratosis

Filaggrin

Ichthyosis vulgaris Atopic dermatitis

KO**: impaired epidermal barrier, enhanced contact hypersensitivity

Structural proteins

Desmosomal proteins Desmocollin 1

Subcorneal pustular dermatosis

KO: skin fragility with acantholysis, localized hair loss

Desmocollin 3

Hypotrichosis and skin lesions*

Conditional KO: skin blistering with acantholysis, telogen hair loss

Desmoglein 3

Pemphigus vulgaris (PV)

KO or PV model (anti-Dsg3 Ab in Rag2 KO): mucous membrane blistering and hair loss

Desmoglein 4

Localized autosomal recessive hypotrichosis Autosomal recessive monilethrix

Y196S (biallelic): hair defects (“lanceolate hair”)

Desmoplakin

Striate PPK Carvajal syndrome Skin fragility/woolly hair syndrome Acantholytic EBS

KO: embryonic lethality; heart defects in tetraploid rescued mice

Plakoglobin

Naxos disease Cardiomyopathy with alopecia & PPK Acantholytic EBS

KO: embryonic lethality, heart defects

Corneodesmosin

Hypotrichosis simplex of the scalp Inflammatory peeling skin syndrome

Conditional KO: loss of adhesion between granular and cornified cell layers, skin water barrier defects, hair loss

*To date, reported in a single family. **Similar findings in the “flaky tail” mouse with a biallelic single nucleotide deletion (5303delA) that results in a frameshift mutation and truncated protein. Table 56.5 Mouse models for human skin diseases due to abnormalities in structural and desmosomal proteins. Ab, antibodies; KO, knockout; PPK, palmoplantar keratoderma.  

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in epidermolysis bullosa simplex: implications for disease phenotype and keratin filament assembly. Hum Mutat 2006;27:719–20. Oji V, Tadini G, Akiyama M. Revised nomenclature and classification of inherited ichthyoses: Results of the First Ichthyosis Consensus Conference in Sorèze 2009. J Am Acad Dermatol 2010;63:607–41. Smith F. The molecular genetics of keratin disorders. Am J Clin Dermatol 2003;4:347–64. Omary MB, Ku NO, Strnad P, et al. Toward unraveling the complexity of simple epithelial keratins in human disease. J Clin Invest 2009;119:1794–805. McGrath JA, Uitto J. The filaggrin story: novel insights into skin-barrier function and disease. Trends Mol Med 2008;14:20–7. Chen J, Roop DR. Genetically engineered mouse models for skin research: taking the next step. J Dermatol Sci 2008;52:1–12. Hegde V, Hickerson RP, Nainamalai S, et al. In vivo gene silencing following non-invasive siRNA delivery into the skin using a novel topical formulation. J Control Release 2014;196:355–62.

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887

SECTION 9 GENODERMATOSES

57 

Ichthyoses, Erythrokeratodermas, and Related Disorders Gabriele Richard and Franziska Ringpfeil

Chapter Contents Ichthyoses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 892 Ichthyosis vulgaris . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 892 Steroid sulfatase deficiency . . . . . . . . . . . . . . . . . . . . . . . 894 Epidermolytic ichthyosis . . . . . . . . . . . . . . . . . . . . . . . . . 897 Superficial epidermolytic ichthyosis . . . . . . . . . . . . . . . . . 898 Ichthyosis with confetti . . . . . . . . . . . . . . . . . . . . . . . . . . 899 Ichthyosis hystrix Curth–Macklin . . . . . . . . . . . . . . . . . . . . 900 Ichthyosis hystrix . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 900 Collodion baby . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 900 Lamellar ichthyosis . . . . . . . . . . . . . . . . . . . . . . . . . . . . 902 Congenital ichthyosiform erythroderma . . . . . . . . . . . . . . . 903 Harlequin ichthyosis . . . . . . . . . . . . . . . . . . . . . . . . . . . . 904 Netherton syndrome . . . . . . . . . . . . . . . . . . . . . . . . . . . 906 Sjögren–Larsson syndrome . . . . . . . . . . . . . . . . . . . . . . . 908 Neutral lipid storage disease with ichthyosis . . . . . . . . . . . . 909 Trichothiodystrophy with ichthyosis . . . . . . . . . . . . . . . . . 910 Other ichthyoses and related disorders . . . . . . . . . . . . . . . 910 Erythrokeratodermas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 912 Erythrokeratodermia variabilis . . . . . . . . . . . . . . . . . . . . . 912 Progressive symmetric erythrokeratoderma (PSEK) . . . . . . . . 916 Keratitis–ichthyosis–deafness syndrome . . . . . . . . . . . . . . . 916 X-linked dominant ichthyosiform disorders . . . . . . . . . . . . . . 918 CHILD syndrome . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 918 Conradi–Hünermann–Happle syndrome . . . . . . . . . . . . . . 919

Key features

888

■ Ichthyoses and erythrokeratodermas are heterogeneous groups of disorders of cornification ■ Ichthyoses are characterized by scaling of the skin in a widespread distribution ■ Erythrokeratodermas feature discrete areas of erythema and hyperkeratosis, usually without substantial scale ■ Most inherited ichthyoses and erythrokeratodermas are evident at birth or manifest in infancy ■ Clinical features and pattern of inheritance as well as the underlying structural, biochemical, and molecular abnormalities help to differentiate these disorders ■ Therapy is symptomatic and primarily aimed at reducing hyperkeratosis. Topical management consists of emollients, keratolytics, and retinoids ■ Many, but not all, disorders respond well to oral retinoids. Treatment is initiated at low doses and titrated to response. Benefits and side effects must be carefully considered because of the chronic nature of these conditions

INTRODUCTION Ichthyoses and erythrokeratodermas are disorders of cornification in which abnormal differentiation and desquamation of the epidermis result in a defective cutaneous barrier. Ichthyoses represent a large clinically and etiologically heterogeneous group of conditions that feature generalized scaling of the skin (Table 57.1). Erythrokeratodermas are characterized by circumscribed areas of erythema and hyperkeratosis without obvious scaling. Willan introduced the term “ichthyosis”, derived from the Greek root “ichthy” meaning fish, in his textbook of dermatology in 18081. Since then, nomenclature and nosology of ichthyoses have continuously evolved, including a variety of descriptive names, eponyms, and synonyms. Milestones in recognizing distinct entities include the description of harlequin ichthyosis in the nineteenth century, separation of the bullous and non-bullous types of ichthyosis by Brocq (who also coined the name “congenital ichthyosiform erythroderma”) in the early 20th century2, and differentiation between autosomal dominant “epidermolytic hyperkeratosis” and autosomal recessive “lamellar ichthyosis” by Frost and Van Scott in 19663. Alibert mentioned the autosomal dominant inheritance of ichthyosis vulgaris as early as 18064. X-linked ichthyosis, despite several earlier reports, was only fully recognized in Wells and Kerr’s study in 19665, followed by the identification of steroid sulfatase deficiency in the 1970s6. Advances in the molecular etiology and biology of ichthyoses and erythrokeratodermas have provided tools to categorize these disorders of cornification, at least in part, based on their underlying genetic defects. In 2009, an international group of clinical and research experts developed a revised nomenclature and classification system for ichthyoses and other disorders of cornification, incorporating molecular causes as well as functional aspects of disease pathogenesis7. Establishing the correct diagnosis in a patient with ichthyosis is a prerequisite for making prognostic predictions, planning therapy, and offering genetic counseling. This may pose a considerable challenge, as these disorders are uncommon and have overlapping clinical spectra. However, a systematic approach utilizing clinical and laboratory-based clues can aid in making the diagnosis (Fig. 57.1). In general, it is helpful to determine whether an ichthyosis presented at birth (e.g. as a collodion baby) or later in life and whether manifestations are limited to the skin or are part of a multisystem disorder. The quality and distribution of the scale as well as the presence or absence of erythroderma, blistering, and abnormalities of cutaneous adnexa are other useful clinical features. A thorough family history is essential for recognizing the inheritance pattern, and examination of both parents (even in a seemingly sporadic case) may reveal valuable diagnostic hints such as an epidermal nevus representing a mosaic presentation of epidermolytic ichthyosis. Patients whose parents are clinically unaffected may have: (1) a recessive ichthyosis, especially in the setting of consanguinity and/or affected siblings; (2) a dominant ichthyosis due to a “new” mutation; or (3) for a male patient, an X-linked recessive ichthyosis where the mother may be an asymptomatic carrier but her male relatives could potentially be affected. A few disorders can be recognized based on characteristic histopathologic and ultrastructural features, such as epidermolytic ichthyosis and ichthyosis hystrix Curth–Macklin. Laboratory studies suggest the diagnosis in other conditions, including enzyme analysis in steroid sulfatase deficiency and observation of lipid vacuoles in circulating leukocytes in neutral lipid storage disease (see Fig. 57.1). This strategy allows the clinician to identify many ichthyoses based on their key features. For most conditions, the molecular etiology

This chapter describes the clinical features, etiologies, evaluation, and management of ichthyoses and erythrokeratodermas. Both groups represent disorders of cornification in which abnormal differentiation and desquamation of the epidermis results in a defective cutaneous barrier. Ichthyoses are characterized by generalized scaling of the skin with or without an erythematous component, while the hallmark of erythrokeratoderma is circumscribed areas of erythema and hyperkeratosis, usually without substantial scale. Entities that are discussed include the most common disorders, ichthyosis vulgaris due to filaggrin deficiency and X-linked recessive ichthyosis due to steroid sulfatase deficiency; nonsyndromic conditions such as keratinopathic ichthyoses and autosomal recessive congenital ichthyoses (ARCI) due to defective epidermal lipid metabolism and transport; various syndromic ichthyoses; and disorders of cornification due to connexin defects or abnormal cholesterol metabolism. The underlying genetic defects and pathomechanisms are highlighted, as this provides a basis for the development of targeted treatments.

ichthyosis erythrokeratoderma disorder of cornification ichthyosis vulgaris steroid sulfatase deficiency epidermolytic ichthyosis ichthyosis with confetti ichthyosis hystrix Curth–Macklin ichthyosis hystrix collodion baby self-improving collodion ichthyosis autosomal recessive congenital ichthyosis lamellar ichthyosis congenital ichthyosiform erythroderma Netherton syndrome Sjögren–Larsson syndrome neutral lipid storage disease trichothiodystrophy erythrokeratodermia variabilis progressive symmetric erythrokeratoderma keratitis– ichthyosis–deafness syndrome CHILD syndrome Conradi–Hünermann–Happle syndrome Harlequin ichthyosis

CHAPTER

57 Ichthyoses, Erythrokeratodermas, and Related Disorders

ABSTRACT

non-print metadata KEYWORDS

888.e1

CHAPTER

Diagnosis

Gene

Mode of inheritance

Incidence

Onset

Primary cutaneous features

Associated features

Diagnosis (in addition to molecular testing*)

Common ichthyoses Ichthyosis vulgaris

FLG

Autosomal semidominant

1 : 100–1 : 250

Infancy/ childhood

Fine, adherent scales on extremities and trunk with sparing of flexures; larger scales on lower legs; hyperlinear palms/soles, furrowed heels

Keratosis pilaris; atopic dermatitis

Clinical; diminished/ absent stratum granulosum; absent/ reduced filaggrin immunostaining

Steroid sulfatase deficiency (X-linked recessive ichthyosis)

STS (deleted in ~90% of patients)

X-linked recessive

1 : 2000–1 : 9500 boys/men

Infancy

Fine to large, dark, adherent scales on extremities, trunk, neck, and lateral face; sparing of skin folds

Corneal; opacities; cryptorchidism Female carriers: corneal opacities; prolonged labor with affected child

FISH or targeted/ whole genome microarray to identify the gene deletion; increased plasma (hydroxy) cholesterol sulfate; lipoprotein electrophoresis (increased mobility of β-fraction); decreased steroid sulfatase activity in leukocytes

Ichthyoses, Erythrokeratodermas, and Related Disorders

57

FEATURES OF SELECTED ICHTHYOSES AND ERYTHROKERATODERMAS

Nonsyndromic autosomal recessive congenital ichthyoses Lamellar ichthyosis (LI), congenital ichthyosiform erythroderma (CIE)

LI > intermediate/CIE: TGM1 ABCA12 CYP4F22 SDR9C7 SULT2B1** CIE > intermediate/LI: ALOX12B ALOXE3 NIPAL4/ICHTHYIN PNPLA1 CERS3 Childhood-onset intermediate: LIPN

Autosomal recessive†

LI: 1 : 200 000–1 : 300 000 CIE: 1 : 100 000–1 : 200 000

Birth

Frequently collodion membrane at birth, then a generalized distribution; variable palm/sole involvement LI: large, thick, plate-like brown scales; absent or mild erythroderma CIE: fine, white scales; erythroderma

Heat intolerance; frequent (LI) or variable (CIE) scarring alopecia and ectropion > eclabium

Clinical; transglutaminase-1 immunostaining or in situ assay in skin biopsy specimen

Harlequin ichthyosis

ABCA12 (KDSR)

Autosomal recessive

Rare

Birth

Very thick, yellow– brown plates of scale that tightly encase the neonate; large, deep, bright red fissures; survivors develop severe CIE-like phenotype

Premature delivery; often neonatal death due to sepsis or respiratory insufficiency; extreme ectropion, eclabium, and ear deformities

Clinical

*Genetic testing is available for all types of ichthyosis with a known molecular basis through clinical or research laboratories; multigene panels are preferable over single gene testing if the diagnosis is not evident based on clinical and laboratory findings. **Distribution similar to that of steroid sulfatase deficiency, with sparing of the central face and skin folds. †There are also rare reports of autosomal dominant inheritance of LI or CIE phenotypes (occasionally with a collodion membrane at birth) with unknown genetic bases. Biallelic small deletions in the caspase 14 gene (CASP14) were recently identified in patients from two Algerian families who presented with generalized fine whitish scales with no erythema and no collodion membrane.

Table 57.1 Features of selected ichthyoses and erythrokeratodermas. The lamellar ichthyosis (LI)–congenital ichthyosiform erythroderma (CIE) spectrum currently includes 11 genes/proteins. Those favoring an LI phenotype are: TGM1 – transglutaminase-1, ABCA12 – ABC lipid transporter (also underlies Harlequin ichthyosis), CYP4F22 – cytochrome P450 enzyme that forms acylceramides, SDR9C7 – short chain dehydrogenase/reductase, and SULT2B1 – cholesterol sulfotransferase. Those favoring a CIE phenotype are: ALOX12B and ALOXE3 – lipoxygenases, NIPAL4 (ICHTHYIN) – involved in lipid processing, PNPLA1 – patatin-like phospholipase, and CERS3 – ceramide synthase. Childhood-onset ichthyosis with fine scaling/minimal erythema results from LIPN – lipase N. FISH, fluorescence in situ hybridization.  

Continued

889

SECTION

Genodermatoses

9

FEATURES OF SELECTED ICHTHYOSES AND ERYTHROKERATODERMAS

Diagnosis

Gene

Mode of inheritance

Incidence

Onset

Primary cutaneous features

Associated features

Diagnosis (in addition to molecular testing*)

Keratinopathic ichthyoses (also includes ichthyosis with confetti – see text) Epidermolytic ichthyosis

KRT1 KRT10

Autosomal dominant (very rarely autosomal recessive)

1 : 200 000–1 : 350 000

Birth

At birth: erythroderma, blistering, erosions Later: hyperkeratosis with cobblestone pattern (most prominent over joints), ridging of the flexures; generalized or localized; variable degree of palmoplantar involvement and blistering

Superficial epidermolytic ichthyosis

KRT2

Autosomal dominant

Rare

Birth

Erythroderma and blistering at birth; later, hyperkeratosis with flexural accentuation, “molting” of the skin; palms and soles spared

Ichthyosis hystrix Curth–Macklin

KRT1

Autosomal dominant

Rare

Birth

Mild to severe, mutilating palmoplantar keratoderma; hyperkeratosis with verrucous, cobblestone, or hystrix-like pattern on extremities and trunk

Pseudoainhum; digital contractures

Clinical; electron microscopy

Netherton syndrome

SPINK5

Autosomal recessive

1 : 50 000

Birth/ infancy

Congenital erythroderma and peeling; two principal phenotypes: ichthyosis linearis circumflexa and CIE-like; pruritus and eczematous plaques

Trichorrhexis invaginata and other hair shaft abnormalities; highly elevated serum IgE; neonatal temperature instability, electrolyte imbalance, failure to thrive; recurrent infections; food and other allergies; nonspecific aminoaciduria

Clinical; psoriasiform histopathology; trichoscopy, light microscopic hair shaft analysis; serum IgE measurement

Sjögren–Larsson syndrome

ALDH3A2

Autosomal recessive

10 000 IU/ml. Eosinophilia and allergic reactions to foods and other antigens are common, with clinical manifestations ranging from urticaria and angioedema to anaphylactic shock. Increased interleukin-17 (IL-17) signaling has also

Epidemiology Netherton syndrome (NTS) is an autosomal recessive disorder that occurs worldwide, with a higher prevalence in inbred populations. Considering the phenotypic variability and clinical overlap with atopic dermatitis as well as other forms of ichthyosis, it has been estimated that the incidence of NTS might be as high as 1 in 50 00069. In one series, 18% of patients who presented with erythroderma during the neonatal period had NTS70.

Pathogenesis NTS is caused by biallelic mutations in the serine protease inhibitor Kazal type 5 gene (SPINK5)71,72. More than 70 SPINK5 mutations have been identified, with functional null alleles in ~65% of cases and missense mutations that compromise enzyme function in the remainder. SPINK5 encodes the multi-domain serine protease inhibitor LEKTI, which is predominantly expressed in the lamellar granules of epithelia and lymphoid tissues. A lack of functional LEKTI leads to uncontrolled activity of serine proteases, and NTS patients have an up to five-fold increase of trypsin-like proteolytic activity in their stratum corneum73. This disturbs the regulation of lipid-processing enzymes, which are critical to proper formation of the lamellar lipid bilayer system in the stratum corneum. Hastened degradation of desmoglein 1 results in disintegration and shedding of horny cells, ultimately producing superficial clefts within the stratum corneum and severely disrupted skin barrier function74. In addition, LEKTI deficiency leads to a loss of crucial anti-inflammatory and antimicrobial mechanisms in the skin. Histochemical analysis of hair shafts in NTS demonstrates a reduced number of disulfide bonds, which is suggestive of diminished crosslinkage of hair keratin structures and a weaker coherence of cortical cells. Such focal softening of the hair shaft may allow intussusception of the distal shaft into the dilated proximal cup.

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Fig. 57.14 Netherton syndrome. A Generalized involvement with features of congenital ichthyosiform erythroderma. B Close-up showing “peeling” quality of the scale. C Short, thin hair on the scalp, sparse eyebrows and a lack of  

Clinical Features

906

NTS presents in most (but not all) patients at or soon after birth with CIE-like generalized erythroderma and scaling or with continuous peeling of the skin. A collodion membrane is not a feature of NTS. Approximately 20% of neonates develop potentially fatal complications such as hypernatremic dehydration, electrolyte imbalances, perturbed thermoregulation, failure to thrive, pneumonia, and sepsis. In patients with severe disease, generalized ichthyosis and erythroderma persist throughout life (Fig. 57.14). In the majority of patients, the ichthyosis gradually evolves into serpiginous or circinate scaling and erythematous plaques, which are bordered by a peculiar double-edged scale and descriptively named “ichthyosis linearis circumflexa” (Fig. 57.15). The plaques are usually distributed on the trunk and extremities and change over time in size, shape and location, reflecting the undulating course of NTS. The lesions are pruritic, and many patients develop eczematous plaques and/or lichenification in flexural sites, especially the wrists and antecubital and popliteal fossae. Scalp involvement with thick scale is common. Hair shaft abnormalities usually develop during infancy and early childhood and improve with age, but they vary tremendously in the age

%

&

Other diagnostic tests Molecular testing of SPINK5 can facilitate diagnosis of NTS. Prenatal diagnosis may be performed in families with known SPINK5 mutations using CVS or amniocentesis material72. In addition, immunostaining of skin biopsy specimens with anti-LEKTI antibodies can be used to determine absence or aberrant distribution of LEKTI protein in the epidermis81.

Differential Diagnosis Fig. 57.15 Ichthyosis linearis circumflexa. Note the double-edged scale.  

Courtesy, Antonio Torrelo, MD.

Fig. 57.16 Abnormal hair shaft in Netherton syndrome. Trichorrhexis invaginata with its ball-and-socket appearance (left arrow) and twist in the hair shaft (right arrow).  

been described in NTS and other ichthyoses (e.g. EI, LI, CIE), and clinical studies of IL-17 inhibitors (e.g. secukinumab) are underway75a. Patients develop recurrent respiratory tract and staphylococcal skin infections, and they are at increased risk of sepsis76. Human papilloma virus (HPV) infections are frequent and can result from epidermodysplasia verruciformis-associated HPV types. HPV infections may increase the incidence of SCC of the anogenital area or other cutaneous sites in these patients. Development of multiple SCCs and BCCs in the third decade of life has been described77. During infancy and early childhood, patients with generalized skin involvement often continue to experience failure to thrive, which may be related to an enteropathy with villus atrophy as well as the increased caloric needs associated with erythroderma; this often results in short stature78. Intermittent aminoaciduria can occur, and a few patients with substantial developmental delay have been reported79.

Pathology On light microscopic examination, the epidermis shows pronounced parakeratotic hyperkeratosis with a diminished or absent granular layer, acanthosis, and papillomatosis. There are often dense, almost bandlike, lymphohistiocytic perivascular infiltrates in the papillary dermis. Subcorneal clefting, spongiosis, exocytosis, and Munro microabscesses can occur. The stratum corneum may be strongly eosinophilic on PAS stain. Trichorrhexis invaginata, in which the distal hair shaft is telescoped into the proximal segment, is a highly characteristic light microscopic finding in clipped hairs; other hair shaft abnormalities may also be evident (see above). Trichoscopy of eyelashes and eyebrow hair may also reveal a “matchstick” or “golf tee” appearance. Ultrastructural abnormalities in the epidermal lipid system that are not present in other erythrodermic disorders have historically assisted in differentiating NTS from CIE and erythrodermic psoriasis. In

During infancy, NTS often presents a diagnostic challenge due to its clinical overlap with CIE, erythrodermic psoriasis, and other primary immunodeficiencies. Although the presence of trichorrhexis invaginata and other hair shaft abnormalities can distinguish NTS from these conditions, characteristic hair shaft abnormalities may not be present at birth or in early infancy, and their detection requires repeated analysis of many hairs from different locations (e.g. scalp, eyebrows). Elevated serum IgE levels can also help to differentiate NTS from CIE and psoriasis. Autosomal dominant hyper-IgE syndrome (AD-HIES) also features elevated serum IgE levels in association with atopic-like dermatitis and recurrent skin and respiratory tract infections; however, AD-HIES presents with a neonatal papulopustular eruption rather than erythroderma, and eventually characteristic facial, dental, and skeletal anomalies that are not seen in NTS develop. Other primary immunodeficiencies characterized by erythematous, scaly skin and elevated IgE levels include Wiskott–Aldrich, Omenn, and IPEX (immune dysregulation, polyendocrinopathy, enteropathy, X-linked) syndromes (see Ch. 60). Infants with failure to thrive and generalized eczematous or scaling skin require a comprehensive immunologic evaluation. In acrodermatitis enteropathica (see Ch. 51), erythematous, sometimes figurate plaques with scale-crust are usually restricted to periorificial areas and the distal extremities. If zinc deficiency cannot be excluded with certainty, an empirical trial of zinc treatment is indicated. The migratory, serpiginous plaques of ichthyosis linearis circumflexa can also resemble those seen in erythrokeratodermia variabilis. Prominent borders with a double-edged scale and associated hair shaft abnormalities are specific for NTS, while transient, variable erythematous patches are characteristic of erythrokeratodermia variabilis. Peeling skin syndromes (PSSs) are clinically and genetically heterogeneous disorders characterized by perpetual peeling and desquamation of the skin with variable associated erythema. They share many features with NTS, including congenital erythroderma in the generalized inflammatory subtype of PSS, pruritus, and histologic and ultrastructural abnormalities. Although mutations in the corneodesmosin gene (CDSN) cause generalized inflammatory PSS82, SPINK5 mutations have been identified in some patients with erythroderma and generalized skin peeling79.

CHAPTER

57 Ichthyoses, Erythrokeratodermas, and Related Disorders

particular, premature secretion of lamellar body contents in the upper epidermis as well as the presence of intercellular electron-dense accumulations and abnormal splitting in the superficial stratum corneum seem specific for NTS74,80. Other variable ultrastructural abnormalities include round cytoplasmic inclusion bodies in the upper cell layers (potentially representing lysosomes), a decreased tonofilament– desmosome system, and a lack of lamellar bodies. Transmission electron microscopy of hair shafts reveals faulty keratinization, cleavage, and electron-dense depositions in the cortex.

Treatment Treatment is symptomatic and should be adjusted to the patient’s specific needs. Neonates with exfoliative erythroderma and severe impairment of skin barrier function often require management in an intensive care nursery. Patients who develop failure to thrive and enteropathy need nutritional support to ensure sufficient intake of calories and protein. Topical emollients, keratolytics, tretinoin, calcipotriene (calcipotriol), and corticosteroids alone or in combination are variably effective. Although the skin lesions of NTS may respond to topical tacrolimus, dramatically increased percutaneous absorption of this medication has been described in NTS patients, due to their severe skin barrier dysfunction83. Use of topical tacrolimus therefore requires monitoring of plasma drug levels. Topical pimecrolimus has also been successfully

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9

used, with considerably less systemic absorption84. Topical or systemic antimicrobial agents are often required to treat bacterial and fungal skin infections, but continuous preventive antibiotic therapy (oral or topical) should be avoided because of the risk of developing antibiotic resistance. Fewer infections, reduced skin inflammation, growth and weight gain, and increased natural killer cell cytotoxicity have been observed in NTS patients receiving intravenous immunoglobulin (IVIg) therapy76. Oral antihistamines may be helpful in controlling pruritus. Systemic retinoids have variable efficacy, leading to dramatic improvement in some patients and exacerbation in others. Benefit from treatment with narrowband UVB, psoralen plus UVA (PUVA), UVA1, and balneophototherapy (broadband UVB plus saltwater baths) has been reported.

fundus, which represents a form of juvenile macular dystrophy (Fig. 57.18)90. These dots can be detected in many, but not all, patients during the first year of life, and they increase in number over time. Involvement of the CNS usually manifests at the end of the first year of life with delayed motor development, an abnormal gait, pyramidal signs, spasticity, and contractures. The lower extremities are usually more severely affected than the arms. The di- or tetraplegia is gradually progressive and accompanied by speech defects and intellectual disability. Seizures are present in almost 40% of affected individuals, and MRI of the brain shows white matter disease in most patients. Other variable clinical features of SLS include superficial corneal defects and photophobia, dental and/or osseous dysplasia, and hypertelorism.

SJÖGREN–LARSSON SYNDROME

Pathology

History In 1957, Sjögren and Larsson85 defined the clinical triad of congenital ichthyosis, gradually developing di- or tetraplegia, and mental retardation as a distinct disorder in 28 Swedish patients. In 1988, Rizzo et al.86 discovered an underlying deficiency in the oxidation of long-chain fatty acids due to malfunction of the fatty alcohol dehydrogenase : fatty aldehyde dehydrogenase enzyme complex. Subsequently, De Laurenzi et al.87 identified the underlying defect in the fatty aldehyde dehydrogenase gene (ALDH3A2/FALDH).

Epidemiology Sjögren–Larsson syndrome (SLS) is an autosomal recessive neurocutaneous disorder. It occurs worldwide with an estimated prevalence of 90% of reported cases have been sporadic.

Pathogenesis The vast majority of KID syndrome patients harbor mutations in GJB2, which encodes connexin 26 (Cx26), a β-type gap junction protein118,119. In a single patient with features of KID syndrome and congenital atrichia, a causative mutation was identified in GJB6 (encodes connexin 30)120. All pathogenic mutations identified to date have been heterozygous missense mutations. The GJB2 mutation D50N is particularly common and is detected in almost 80% of KID patients118,119; this mutation can also underlie KID syndrome associated with the follicular occlusion triad and the hystrix-like-ichthyosis–deafness (HID) syndrome25. Other GJB2 mutations affecting the amino terminus or transmembrane domains of Cx26 have been associated with atypical clinical features such as lack of palmoplantar keratoderma or corneal involvement, generalized spiny or verrucous keratoses, mucosal involvement, and the follicular occlusion triad. Two GJB2 mutations, G45E and A88V, cause a very severe neonatal form of KID syndrome that is typically fatal during infancy or early childhood121. In vivo and in vitro functional studies have shown that GJB2 mutations increase connexin hemichannel permeability, leading to ATP release and Ca2+ overload. Mutations altering the Cx26 amino terminus may also allow the formation of constitutively active heteromeric Cx43/Cx26 hemichannels, while gap junction channels are not functional122. Cx26 hemichannels containing the mutation A88V were shown to be CO2-insensitive, providing a possible explanation for breathing abnormalities in patients with fatal KID syndrome123.

Clinical Features There is considerable variability in the type, extent, and severity of cutaneous features in patients with KID syndrome (Table 57.6). The first manifestation is often transient erythroderma at birth or during infancy. Later, most patients develop symmetrically distributed, welldemarcated, hyperkeratotic plaques with an erythematous base and a rough, ridged, or verrucous surface (i.e. erythrokeratoderma); psoriasiform plaques have also been described. The plaques favor the knees, elbows, and face, often with radial furrows around the mouth (Fig. 57.22A&B); the helices, scalp, groin, other skin folds, extremities, and, less often, trunk may also be affected. A plaque-like or diffuse palmoplantar keratoderma with a grainy, reticulated, or stippled surface (reminiscent of Vohwinkel syndrome) is almost always present (Fig. 57.22C&D). Prominent follicular keratoses and cheilitis (especially perlèche) are common. Some patients develop diffuse thickening of the skin with a coarse, grainy appearance, which may also lead to deep facial furrows (see Fig. 57.22A). Nails may be dystrophic and show leukonychia. Although most patients have normal hair, some affected individuals have lusterless hair or alopecia of the scalp, eyelashes, and eyebrows. Heat intolerance occasionally occurs. The spectrum of cutaneous lesions in KID syndrome also includes folliculitis, the follicular occlusion triad, cysts, and proliferating pilar tumors, with rare reports of malignant lesions (see Table 57.6). Another serious complication is the development of SCC of the skin and oral mucosa, which occurs in 10–20% of patients at a median age of 25

ADDITIONAL MUCOCUTANEOUS MANIFESTATIONS OF KID (KERATITIS–ICHTHYOSIS–DEAFNESS) SYNDROME

Inflammatory Follicular occlusion triad (onset usually at puberty): acne conglobata, dissecting cellulitis of the scalp, hidradenitis suppurativa • Folliculitis • Cheilitis with red, “chapped”, fissured lips (especially at the angles of the mouth*) • Stomatitis with erythematous patches, adherent white plaques, and erosions* •

Infectious Recurrent or chronic mucocutaneous bacterial (e.g. Staphylococcus aureus), fungal (e.g. Candida spp.), and viral infections • Sepsis in the neonatal period (may be fatal) •

Neoplastic Cutaneous and oral squamous cell carcinoma (10–20% of patients; median age 25 years) • Epidermoid and pilar cysts • Proliferating pilar tumors, benign or malignant (the latter aggressive/ metastasizing) •

57 Ichthyoses, Erythrokeratodermas, and Related Disorders

History

*May have candidal superinfection. Table 57.6 Additional mucocutaneous manifestations of KID (keratitis– ichthyosis–deafness) syndrome. The spectrum of hyperkeratotic manifestations is described in the text.  

years, but as early as the first decade of life117. KID syndrome is also associated with increased susceptibility to mucocutaneous bacterial, viral, and fungal infections, in particular with Candida albicans. All KID patients have congenital sensorineural hearing impairment that (in contrast to the keratitis) is not progressive. Hearing loss is generally severe and bilateral, although unilateral or moderate hearing impairment has been observed. Approximately 95% of patients have ocular involvement, which typically presents at birth, during infancy, or in early childhood with photophobia and blepharitis. Vascularizing keratitis and conjunctivitis develop and worsen with age. Scarring and neovascularization often cause a progressive decline in visual acuity and may eventuate in blindness. Dental abnormalities such as small or absent teeth, delayed eruption, or excessive caries have been described in patients with KID syndrome. The Dandy–Walker malformation of the cerebellar vermis and fourth ventricle, short heel cords, facial dysmorphism, and other developmental abnormalities have also been reported. A rare severe form of KID syndrome with a fatal outcome during infancy or early childhood presents with erythroderma and areas of massive, fissured hyperkeratosis on the scalp, periorificial skin, and extremities121. These patients also have a grainy palmoplantar keratoderma, atrichia, and nail dystrophy121. Other less common features include facial dysmorphism, congenital absence of the foreskin, edema and dyskeratosis of the laryngeal mucosa, and hydrocephalus. Complications include apnea and other breathing problems requiring mechanical ventilation, severe failure to thrive, and recalcitrant bacterial and fungal infections leading to enterocolitis and sepsis.

Pathology Histology is not specific. Acanthosis and papillomatosis of the epidermis with basket-weave hyperkeratosis and follicular plugging are the most frequent features. Vacuolization of the cells in the granular layer has also been described. The corneal epithelium may be dyskeratotic, atrophic, or absent centrally, and Bowman’s membrane may be absent. The eccrine glands may be diminished in number and atrophic. In the inner ear, the organ of Corti is immature or atrophic.

Differential Diagnosis There have been a few reports of Desmons (Senter) syndrome, an autosomal recessive metabolic disorder characterized by skin changes similar to KID syndrome and hearing impairment (but no keratitis) together with glycogen deposition leading to hepatomegaly, cirrhosis,

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A

B

Fig. 57.22 KID syndrome. A Diffusely thickened, hyperkeratotic skin with a coarsegrained texture and an erythematous component; note the characteristic radial furrows around the mouth. B Bright pink, keratotic periorificial plaques with crusting. Palmar (C) and plantar (D) keratoderma with a grainy surface. A, C, Courtesy, Julie V Schaffer, MD; B,  

Courtesy, J Tercedor, MD; D, Courtesy, Richard Antaya, MD.

C

D

growth failure, and intellectual disability. Other erythrokeratodermas, such as EKV and PSEK, are not associated with impaired hearing and keratitis. Ichthyosis follicularis with atrichia and photophobia (IFAP) syndrome (X-linked due to MBTPS2 mutations; see Table 57.5) and hereditary mucoepithelial dysplasia (autosomal dominant) are both characterized by follicular keratoses, psoriasiform plaques, alopecia, keratitis, and susceptibility to mucocutaneous infections, but not hearing impairment; in the latter disorder, the plaques favor the perineal area and fiery red oral mucosal patches are present. Keratosis follicularis spinulosa decalvans (allelic to IFAP; see Ch. 38) also features follicular keratoses and keratitis, but it progresses to scarring alopecia and does not manifest with hyperkeratotic plaques, palmoplantar keratoderma, or hearing impairment. Hystrix-like-ichthyosis–deafness (HID) syndrome (ichthyosis hystrix type Rheydt) is a clinical variant of KID syndrome that is also caused by GJB2 mutations25. Skin involvement is more severe and keratitis is milder in HID syndrome.

Treatment

918

Skin treatment includes use of emollients and keratolytics; topical retinoids may be beneficial. Oral retinoid therapy (e.g. acitretin) yields mixed results: the hyperkeratosis may or may not respond, the palmoplantar keratoderma is recalcitrant, and ocular side effects may aggravate the keratitis and neovascularization. Successful use of oral alitretinoin (not available in the US; see Ch. 126) for patients with recalcitrant disease has also been described124. Corneal transplants, although often the only possibility for improving vision, have limited efficacy because of revascularization117. Hearing aids and cochlear implants have been used successfully. Mucocutaneous infections often require systemic therapy. Surveillance for the development of SCC and other tumors via periodic examination of the mucous membranes as well as the skin (including the scalp) is required.

X-LINKED DOMINANT ICHTHYOSIFORM DISORDERS CHILD SYNDROME Synonyms:  ■ Congenital hemidysplasia with ichthyosiform erythroderma (or nevus) and limb defects ■ CHILD nevus

History The first description of this condition in 1948 was followed by 17 case reports before Happle delineated the key features and proposed the acronym CHILD syndrome in 1980125.

Epidemiology This is a rare X-linked dominant disorder that occurs primarily in girls and women, as it is generally lethal in affected male embryos. However, a few affected boys have been reported, one of whom had a normal karyotype and presumably a mosaic NSDHL mutation126.

Pathogenesis CHILD syndrome is a disorder of lipid metabolism that results in disturbed cholesterol biosynthesis. Inactivating mutations in NSDHL, which encodes the enzyme 3β-hydroxysteroid-dehydrogenase, were initially identified in five families with right-sided skin and skeletal involvement127; such mutations were subsequently described in additional patients with left-sided involvement. The striking hemilateral phenotype has been postulated to result from skewed X-inactivation



Clinical Features CHILD syndrome classically presents at birth or in the neonatal period with a striking unilateral distribution of erythema and thickened skin with a waxy surface or yellowish adherent scale (Fig. 57.23A). The erythema most often involves the right side of the body and is sharply demarcated at the anterior and posterior midline of the trunk. The face is typically spared. Occasionally, there is partial spontaneous resolution or periodic exacerbation of the cutaneous inflammation125. During infancy, the erythema lessens, while hyperkeratotic plaques or bands with a verrucous surface prevail and often become more pronounced. They may follow the lines of Blaschko or uniformly affect large areas on half of the body, with affinity for the skin folds (ptychotropism). Because of the clinical resemblance to inflammatory linear verrucous epidermal nevus (ILVEN), the terms “CHILD nevus” and “psoriasiform epidermal nevus” have been used. The contralateral side of the body may have mild skin involvement in a mosaic pattern, but symmetric distribution is extremely rare. Ipsilateral linear alopecia and claw-like nail dystrophy or onychorrhexis are common. Ipsilateral skeletal abnormalities range from hypoplasia of digits or ribs to complete amelia; congenital or secondary scoliosis may also occur. Stippled epiphyses can be identified on radiologic examination in early infancy but tend to resolve during childhood. The teeth are typically normal. Asymmetric organ hypoplasia commonly affects the brain, kidneys, heart, and lungs on the affected side of the body. Mild hearing loss and cleft palate may be present. Milder organ anomalies may be observed on the contralateral side.

A

Happle, MD, from Happle R, Mittag H, Kuster W. Dermatology. 1995;191:210–6, with permission; B, Courtesy, Luis Requena, MD.

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57 Ichthyoses, Erythrokeratodermas, and Related Disorders

Fig. 57.23 CHILD syndrome. A Note the sharp midline demarcation on the trunk. B Histologic features include an acanthotic and papillomatous epidermis with marked parakeratosis and vacuoles within the lower stratum corneum. Note the foamy histiocytes in the dermal papillae (inset). The findings can mimic those of a verruciform xanthoma. A, Courtesy, R

and deficient sonic hedgehog signaling in the cells expressing the X-chromosome with a NSDHL mutation, resulting in selection against these cells on one side of the body. This hypothesis reflects the role hedgehog signaling is known to play in conferring left–right asymmetry during embryogenesis. Cholesterol has critical functions during mammalian development, including hedgehog signaling, and inborn errors in cholesterol biosynthesis cause several other malformation syndromes.

Pathology Histopathologic changes include an acanthotic and papillomatous epidermis with marked ortho- and parakeratosis, overlying a mild superficial perivascular infiltrate. Parakeratotic nuclei characteristically retain a round shape128, and numerous vacuoles are present within the cells of the lower stratum corneum. Multiple layers of granular cells surround the sweat ducts, while the granular zone in the surrounding epidermis may be absent, normal, or thickened126. Over time, foamy histiocytes accumulate within the dermal papillae, giving the appearance of a verruciform xanthoma (Fig. 57.23B). Ultrastructural abnormalities include abundant pale-staining mitochondria, cytoplasmic glycogen, lipid retention in the stratum corneum, and altered lamellar granular content, both intracellularly and intercellularly.

Other diagnostic tests Molecular analysis of the NSDHL gene is available. Plasma cholesterol is normal despite defective cholesterol biosynthesis.

B

application of a 2% lovastatin or simvastatin/2% cholesterol lotion or ointment, which targets the underlying cholesterol pathway defect129. A single report noted improvement with topical ketoconazole, possibly due to inhibition of the sterol 14α-demethylase (CYP51)130. Cosmetically and functionally satisfactory results from dermabrasion of affected skin followed by placement of split-thickness skin grafts obtained from the clinically normal contralateral side of the body have also been described131. Requirements for multidisciplinary care depend on the extent of associated organ involvement.

CONRADI–HÜNERMANN–HAPPLE SYNDROME

Differential Diagnosis Sebaceous nevus syndrome may resemble CHILD syndrome but can be clinically differentiated by its distribution pattern and the lack of erythema and scaling. ILVEN is a less extensive condition that is not associated with visceral abnormalities. Punctate epiphyseal calcifications and asymmetric limb shortening together with CIE in a distribution following the lines of Blaschko may be seen in X-linked dominant chondrodysplasia punctata (see below). However, the skin manifestations are not unilateral and are replaced by atrophoderma by 2 years of age; in addition, skeletal defects are usually less severe than in CHILD syndrome127.

Treatment Case reports have noted variable improvement of skin lesions with topical tretinoin or systemic retinoid therapy, but emollients and corticosteroids are ineffective. Substantial benefit has been described with topical

Synonyms:  ■ X-linked dominant chondrodysplasia punctata

Chondrodysplasia punctata type 2 (CDPX2) ■ Conradi–Hünermann syndrome ■ Happle syndrome ■

History In 1971, the dominant Conradi–Hünermann type of chondrodysplasia was differentiated from the autosomal recessive rhizomelic form. Happle subsequently reviewed the literature and established that the Conradi– Hünermann type has an X-linked dominant mode of inheritance132.

Epidemiology Conradi–Hünermann–Happle (CHH) syndrome is a rare X-linked dominant disorder that occurs primarily in girls and women. It is lethal in

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Fig. 57.24 Conradi– Hünermann–Happle syndrome. A Erythroderma and linear streaks and whorls of hyperkeratosis. B Epiphyseal stippling at the knee. A, Courtesy, R

male embryos outside the setting of an XXY karyotype or mosaicism due to a postzygotic mutation in EBP. However, an X-linked recessive multiple congenital anomaly syndrome in which male patients die by early childhood and female carriers are unaffected has been described with a less severe germline mutation in EBP133.



Pathogenesis Conradi–Hünermann–Happle syndrome is due to a defect in cholesterol biosynthesis that is caused by mutations in EBP, which encodes emopamil-binding protein (EBP)134,135. The resulting deficiency of EBP, a widely expressed integral membrane protein with Δ8-Δ7-sterol isomerase activity, leads to accumulation of 8-dehydrocholesterol and 8(9) cholesterol135, which can be detected in plasma and cultured fibroblasts. However, levels of the end product cholesterol sulfate are normal in plasma and fibroblasts because of X-inactivation134,135. Impaired cholesterol synthesis during a critical period of mammalian development is thought to be responsible for the phenotype. A particular hemizygous missense mutation affecting the first transmembrane domain of EBP, presumably with less deleterious effects on enzyme function, has been identified in boys with an allelic multiple congenital anomaly syndrome133.

Happle, MD; B, Courtesy, Jean L Bolognia, MD.

A

Clinical Features At birth, most CHH syndrome patients have generalized erythema with thick, adherent, feathery scale; streaks and whorls of hyperkeratosis following the lines of Blaschko are often observed (Fig. 57.24A). The erythroderma resolves substantially, if not completely, within the first weeks or months of life. In older children, hyperkeratosis is largely replaced by linear or patchy follicular atrophoderma with dilated follicular openings, ice-pick-like scars, and mild residual scaling. The atrophoderma is most pronounced on the forearms and dorsal hands, whereas the palms and soles are usually spared. Hyper- or hypopigmentation along the lines of Blaschko may coexist separately from atrophodermic areas132. Scalp involvement results in patchy scarring alopecia. In addition, hair may be sparse, coarse, or lusterless. Nail changes include onychoschizia and flattening of the nail plate, while the teeth are normal. Skeletal anomalies are usually asymmetric. They include frontal bossing, malar hypoplasia, a flat nasal bridge, a short neck, rhizomelic shortening of the limbs, and scoliosis. Widespread premature calcifications manifest as stippling (chondrodysplasia punctata) of the long bone epiphyses, tracheal cartilage, and vertebrae. These can be detected on radiographs during infancy (Fig. 57.24B), but they are not apparent once bone maturation progresses. Unilateral cataracts, which are present at birth or develop within the first months of life, are the most common ocular abnormality and may be accompanied by microphthalmia or microcornea. Occasionally, other features may be associated and include congenital heart defects, sensorineural deafness, CNS malformations, and congenital renal anomalies. Intellect is usually not impaired and life expectancy is normal. Boys with the allelic X-linked recessive syndrome have a collodionlike presentation at birth and evolution to a variable ichthyosis phenotype133. Additional features include cardiovascular, craniofacial, and skeletal anomalies as well as the Dandy–Walker malformation, hydrocephalus, cataracts, and cryptorchidism.

Pathology Hyperkeratosis with focal parakeratosis is common and most prominent in follicular ostia, where dystrophic calcification may be observed within keratotic plugs. The granular layer is diminished and keratinocytes contain small vacuoles with needle-like calcium inclusions on electron microscopy.

Other diagnostic tests Radiographs reveal premature calcifications in the cartilage of the trachea, spine, and long bones during the first year of life (Fig. 57.24B). Accumulation of 8(9)cholesterol in plasma can be detected by gas chromatography–mass spectrophotometry in order to confirm the diagnosis. Molecular analysis of EBP is available.

920

B

Differential Diagnosis Stippled epiphyses during infancy and asymmetric limb shortening are also seen in girls with CHILD syndrome, but the skin involvement usually shows striking lateralization and does not fade completely. However, some overlap in the clinical findings of CHILD and CHH syndromes is not surprising, since both represent disorders of cholesterol biosynthesis. Ichthyosis linearis circumflexa in Netherton syndrome is readily distinguished by its double-edged scale, and the lesions do not follow the lines of Blaschko. Cutaneous manifestations in CIE are more generalized. Hyper- and hypopigmentation in “pigmentary mosaicism”, incontinentia pigmenti, and epidermal nevi (including epidermolytic variants) follow the lines of Blaschko but lack follicular atrophoderma.

Treatment Although the erythema gradually resolves, residual mild scaling may benefit from application of emollients and products containing urea or a keratolytic agent. Orthopedic and ophthalmologic care are essential. For additional online figures visit www.expertconsult.com

CHAPTER

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57 Ichthyoses, Erythrokeratodermas, and Related Disorders

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143. Feldmeyer L, Huber M, Fellmann F, et al. Confirmation of the origin of NISCH syndrome. Hum Mutat 2006;27:408–10. 144. Basel-Vanagaite L, Attia R, Ishida-Yamamoto A, et al. Autosomal recessive ichthyosis with hypotrichosis caused by a mutation in ST14, encoding type II transmembrane serine protease matriptase. Am J Hum Genet 2007;80:467–77. 145. Alef T, Torres S, Hausser I, et al. Ichthyosis, follicular atrophoderma, and hypotrichosis caused by mutations in ST14 is associated with impaired profilaggrin processing. J Invest Dermatol 2009;129:862–9. 146. Dierks T, Schmidt B, Borissenko LV, et al. Multiple sulfatase deficiency is caused by mutations in the gene encoding the human C(alpha)-formylglycine generating enzyme. Cell 2003;113:435–44. 147. Braverman N, Steel G, Obie C, et al. Human PEX7 encodes the peroxisomal PTS2 receptor and is responsible for rhizomelic chondrodysplasia punctata. Nat Genet 1997;15:369–76. 148. Rizzo WB, Jenkens SM, Boucher P. Recognition and Diagnosis of Neuro-Ichthyotic Syndromes. Semin Neurol 2012;32:75–84. 149. Weinstein R. Phytanic acid storage disease (Refsum’s disease): clinical characteristics, pathophysiology and the role of therapeutic apheresis in its management. J Clin Apher 1999;14:181–4. 150. Straube R, Gackler D, Thiele A, et al. Membrane differential filtration is safe and effective for the long-term treatment of Refsum syndrome – an update of treatment modalities and pathophysiological cognition. Transfus Apher Sci 2003;29:85–91. 151. Perera NJ, Lewis B, Tran H, et al. Refsum’s disease – use of the intestinal lipase inhibitor, orlistat, as a novel therapeutic approach to a complex disorder. J Obes 2011;2011:482021. 152. Lovric S, Goncalves S, Gee HY, et al. Mutations in sphingosine-1-phosphate lyase cause nephrosis with

ichthyosis and adrenal insufficiency. J Clin Invest 2017;127:912–28. 153. Vera-Casano A, Weirich C, Grzeschik KH. IFAP syndrome is caused by deficiency in MBTPS2, an intramembrane zinc metalloprotease essential for cholesterol homeostasis and ER stress response. Am J Hum Genet 2009;84:459–67. 154. Montpetit A, Côté S, Brustein E, et al. Disruption of AP1S1, causing a novel neurocutaneous syndrome, perturbs development of the skin and spinal cord. PLoS Genet 2008;4:e1000296. 155. Cadieux-Dion M, Turcotte-Gauthier M, Noreau A, et al. Expanding the clinical phenotype associated with ELOVL4 mutation: study of a large French-Canadian family with autosomal dominant spinocerebellar ataxia and erythrokeratodermia. JAMA Neurol 2014;71:470–5. 155a.  Boyden LM, Kam CY, Hernández-Martín A, et al. Dominant de novo DSP mutations cause erythrokeratodermia-cardiomyopathy syndrome. Hum Mol Genet 2016;25:348–57. 156. Dahlqvist J, Klar J, Tiwari N, et al. A single-nucleotide deletion in the POMP 5’ UTR causes a transcriptional switch and altered epidermal proteasome distribution in KLICK genodermatosis. Am J Hum Genet 2010;86:596–603. 157. Blaydon DC, Nitoiu D, Eckl KM, et al. Mutations in CSTA, encoding Cystatin A, underlie exfoliative ichthyosis and reveal a role for this protease inhibitor in cell-cell adhesion. Am J Hum Genet 2011;89:564–71. 158. Cabral RM, Kurban M, Wajid M, et al. Whole-exome sequencing in a single proband reveals a mutation in the CHST8 gene in autosomal recessive peeling skin syndrome. Genomics 2012;99:202–8. 159. Findlay GH, Nurse GT, Heyl T, et al. Keratolytic winter erythema or ‘Oudtshoorn skin’: a newly recognized inherited dermatosis prevalent in South Africa. S Afr Med J 1977;52:871–4.

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134.

associated with an EBP mutation. Am J Med Genet A 2010;152A:2838–44. Braverman N, Lin P, Moebius FF, et al. Mutations in the gene encoding 3 beta-hydroxysteroid-delta 8, delta 7-isomerase cause X-linked dominant ConradiHunermann syndrome. Nat Genet 1999;22:291–4. Derry JM, Gormally E, Means GD, et al. Mutations in a delta 8-delta 7 sterol isomerase in the tattered mouse and X-linked dominant chondrodysplasia punctata. Nat Genet 1999;22:286–90. Khnykin D, Rønnevig J, Johnsson M, et al. Ichthyosis prematurity syndrome: clinical evaluation of 17 families with a rare disorder of lipid metabolism. J Am Acad Dermatol 2012;66:606–16. Klar J, Schweiger M, Zimmerman R, et al. Mutations in the fatty acid transport protein 4 gene cause the ichthyosis prematurity syndrome. Am J Hum Genet 2009;85:248–53. Gissen P, Tee L, Johnson CA, et al. Clinical and molecular genetic features of ARC syndrome. Hum Genet 2006;120:396–409. Sprecher E, Ishida-Yamamoto A, Mizrahi-Koren M, et al. A mutation in SNAP29, coding for a SNARE protein involved in intracellular trafficking, causes a novel neurocutaneous syndrome characterized by cerebral dysgenesis, neuropathy, ichthyosis, and palmoplantar keratoderma. Am J Hum Genet 2005;77:242–51. Aldahmesh MA, Mohamed JY, Alkuraya HS, et al. Recessive mutations in ELOVL4 cause ichthyosis, intellectual disability, and spastic quadriplegia. Am J Hum Genet 2011;89:745–50. Kranz C, Jungeblut C, Denecke J, et al. A defect in dolichol phosphate biosynthesis causes a new inherited disorder with death in early infancy. Am J Hum Genet 2007;80:433–40. Morava E, Wevers RA, Cantagrel V, et al. A novel cerebello-ocular syndrome with abnormal glycosylation due to abnormalities in dolichol metabolism. Brain 2010;133:3210–20.

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eFig. 57.2 Epidermolytic ichthyosis. A Erythroderma with widespread peeling and erosions during the neonatal period.   B Hyperkeratosis with focal erosions.   C Corrugated hyperkeratosis on the neck. A, B, Courtesy, Gene  

Mirrer, MD; C, Courtesy, Julie V Schaffer, MD.

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eFig. 57.1 Ichthyosis vulgaris. A Fine, white scales on the leg. B Histologically, orthokeratotic hyperkeratosis and a diminished granular layer are evident. A,  

Courtesy, Julie V Schaffer, MD; B, Courtesy, Lorenzo Cerroni, MD.

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eFig. 57.6 Progressive symmetric erythrokeratoderma. A, B Well-demarcated, symmetrically distributed hyperkeratotic plaques with underlying erythema and fine, white scale. The patients also had a plantar keratoderma. B, Courtesy,

Genodermatoses



Antonio Torrelo, MD.

eFig. 57.3 Ichthyosis with confetti. Numerous small, confetti-like “islands” in the background of ichthyosiform erythroderma reflect revertant mosaicism.  

Courtesy, Antonio Torrelo, MD.

A

eFig. 57.4 Ichthyosis linearis circumflexa. Note the double-edged scale.  

B

eFig. 57.5 Sjögren–Larsson syndrome. Yellowish-brown hyperkeratosis, accentuated skin markings and areas of scaling on the lower back and buttocks. Courtesy, Julie V Schaffer, MD.  

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eFig. 57.7 KID syndrome. In addition to the erythematous plaques, characteristic radial furrows are seen. Courtesy, L Russell, MD, and SJ Bale, PhD.  

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eFig. 57.8 KID syndrome. Palmar keratoderma with a grainy  

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58 

Palmoplantar Keratodermas Dieter Metze and Vinzenz Oji

Key features ■ Palmoplantar keratodermas can be inherited or acquired ■ The three major patterns of involvement are diffuse, focal, and punctate ■ The clinical presentation may be different on the hands and feet, e.g. diffuse on the soles and focal on the palms ■ Additional distinguishing features include an erythematous border, transmigration to areas beyond the palmoplantar skin, and digital constrictions (pseudoainhum) ■ Patients may also suffer from hyperhidrosis, maceration, blistering, fungal infections, malodor, and pain ■ It is important to determine whether other features are present, e.g. nail dystrophy, hypotrichosis, oral lesions, hyperkeratosis of non-volar skin, impaired hearing, ocular findings, cardiomyopathy (in patients with woolly hair) ■ Histologic examination sometimes shows specific findings, such as epidermolytic hyperkeratosis

Further clinical classification depends upon whether there are associated cutaneous and extracutaneous features (see Table 58.1). Many PPKs show transgrediens, which refers to extension of the hyperkeratosis onto the dorsal aspects of the fingers, toes, hands, and feet as well as the flexor aspects of the wrists and heels, either diffusely or as callosities on pressure points (e.g. the knuckles). Confluent hyperkeratosis may also extend circumferentially around entire digits. In scarring PPKs, keratotic constriction bands (pseudoainhum) can develop around digits and may lead to autoamputation (Table 58.3). Additional associated findings include hyperhidrosis, maceration, blistering, malodor, pain, and fungal infections. When evaluating a patient with a PPK, a thorough family history should be obtained and the entire skin surface examined as well as the mucous membranes, nails, and hair. Hearing and the ability to sweat should also be assessed. Exclusion of extracutaneous manifestations

INTRODUCTION Palmoplantar keratodermas (PPKs) represent a heterogeneous group of hereditary and acquired disorders of cornification characterized by prominent hyperkeratosis of the skin on the palms and soles. Inherited PPK sometimes represents a component of a syndromic phenotype with extracutaneous manifestations such as cardiomyopathy or deafness. Likewise, acquired PPK can be drug-induced or associated with cancer. Determination of the specific subtype of PPK and recognition of associated features are therefore important1,2 (Table 58.1). Several classification systems for PPKs have been proposed, but none of these satisfactorily incorporates clinical presentation, pathology, and molecular pathogenesis. Current nomenclature is non-uniform and includes many eponyms2. In addition, PPK may represent a component of other genodermatoses such as ichthyoses, erythrokeratodermas, epidermolysis bullosa, and ectodermal dysplasias3 (Table 58.2). A simple working classification divides PPKs into three major types based on the clinical pattern of involvement4: diffuse PPK – involvement of the entire palmoplantar surface, usually but not always including the central palmar skin and instep (Fig. 58.1) focal PPK – localized areas of hyperkeratosis, with two major patterns: (1) the areata/nummular type – oval lesions, located mainly over pressure points; and (2) the striate type – linear hyperkeratotic lesions, most commonly extending from the palms to the volar surface of the fingers, overlaying flexor tendons (Fig. 58.2; see Fig. 58.14A) punctate PPK – multiple small keratotic papules or pits (usually from removal of a keratotic plug) that are scattered or aggregated on the palms and soles (Fig. 58.3). Many hereditary forms of PPK do not develop until the first months or years of life. The onset and severity of disease expression depend in part on mechanical stress, e.g. exposure of the feet to friction and pressure. Focal involvement may evolve into a diffuse PPK over time, e.g. from infancy to adulthood. Some types of PPK don’t even manifest until adulthood, while others have spontaneous improvement and recurrences over time. In addition, substantial variability can often be observed within the same family.

A

Fig. 58.1 Diffuse palmoplantar keratoderma. Hyperkeratosis of the entire palmar (A) and plantar (B) surface with sharp demarcation.    

• •

A, Courtesy, Julie V Schaffer, MD; B, Courtesy, Alfons Krol, MD, and Dawn Siegel, MD.



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B

Palmoplantar keratoderma (PPK) represents a heterogeneous group of hereditary and acquired disorders of cornification characterized by hyperkeratosis of the skin on the palms and soles. Inherited PPK may occur as an isolated condition, a component of another genodermatosis (e.g. ichthyosis, epidermolysis bullosa, ectodermal dysplasia), or a part of a multisystem syndrome (e.g. with deafness or cardiomyopathy). Acquired forms can be drug-induced or paraneoplastic. PPKs have three major patterns of palmoplantar involvement: diffuse, focal (areata or striate), and punctate. Some PPKs demonstrate transgrediens, i.e. extension beyond volar skin. Patients may suffer from hyperhidrosis, maceration, blisters, fungal infections, malodor, constricting keratotic bands (pseudoainhum), and severe pain. A skin biopsy can sometimes provide clues to the specific diagnosis. The underlying molecular defect may involve epidermal proteases as well as proteins of the keratinocyte cytoskeleton, cornified envelope, desmosome, or gap junction.

palmoplantar keratoderma (PPK), punctate PPK, focal PPK, diffuse PPK, hereditary PPK, syndromic PPK, acquired PPK, epidermolytic PPK, non-epidermolytic PPK, mutilating PPK, Vohwinkel syndrome, Huriez syndrome, Clouston syndrome, Olmsted syndrome, Papillon–Lefèvre syndrome, Naxos disease, Carvajal syndrome, pachyonychia congenita, spiny keratoderma, marginal papular keratoderma, acrokeratoelastoidosis, focal acral hyperkeratosis, keratoderma climactericum, aquagenic PPK

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58 Palmoplantar Keratodermas

ABSTRACT

non-print metadata KEYWORDS:

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cytoskeleton, cornified envelope, desmosome (see Fig. 56.8), or gap junction (Fig. 58.4, Table 58.5); the known underlying genetic mutations are summarized in Table 58.65,6. Genetic analysis is sometimes helpful to establish the specific diagnosis, facilitate identification of affected family members, and enable prenatal diagnosis.

PRIMARY PALMOPLANTAR KERATODERMAS (PPKS)

Disorder

Additional features

Hereditary PPKs

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58 Palmoplantar Keratodermas

may require referral for cardiac, audiologic, ophthalmologic, or dental evaluation. A skin biopsy for histologic examination may provide additional diagnostic clues (Table 58.4). The molecular defect underlying PPKs may involve epidermal proteases as well as proteins of the keratinocyte

Diffuse PPK, isolated Vörner–Unna–Thost

Epidermolytic

Nagashima, Kimonis

Non-epidermolytic

Bothnia

White/spongy upon water exposure; non-epidermolytic

“Greither”

Transgrediens & progrediens; variable pathology

Mal de Meleda (including Gamborg Nielsen)

Mutilating, frequent superinfections; non-epidermolytic

Diffuse PPK with associated features Hearing impairment: Vohwinkel syndrome

Mutilating, “honeycomb” PPK; starfish keratoses on knuckles

Bart–Pumphrey syndrome

Knuckle pads, leukonychia

PPK due to connexin 26 defect

“Honeycomb” PPK

Mitochondrial PPK High risk of acral SCC*: Huriez syndrome

Scleroatrophy

PPK with sex reversal

Female-to-male sex reversal

Hypotrichosis & nail dystrophy: Clouston syndrome

Pebbled/grid-like acral papules

Odonto-onycho-dermal dysplasia

Hypodontia, facial telangiectasias/erythema

Schöpf–Schulz–Passarge syndrome

Hidrocystomas, other adnexal neoplasms, hypodontia

Keratoderma–hypotrichosis–leukonychia totalis

Total leukonychia

Mutilating*: Olmsted syndrome

Periorificial/intertriginous keratotic plaques

Papillon–Lefèvre syndrome**

Periodontitis, pyogenic infections, psoriasiform plaques

Loricrin keratoderma

Mild generalized ichthyosis, “honeycomb” PPK

KLICK

Keratosis linearis, ichthyosis congenita, sclerosing keratoderma

Vohwinkel syndrome (see above) Mal de Meleda (see above) Cardiomyopathy: Naxos disease***

Woolly hair, arrhythmias in adolescence

Focal PPK, isolated Brünauer–Fuhs–Siemens, Wachters

Striate on palms, nummular on soles; see Table 58.6 for genetic subtypes

Focal PPK with associated features Pachyonychia congenita

Painful soles, dystrophic nails, oral leukokeratosis, steatocystomas/other cysts

Focal palmoplantar and gingival keratosis

Painful soles, gingival leukokeratosis; epidermolytic

Howel–Evans syndrome

Esophageal carcinoma

Richner–Hanhart syndrome (oculocutaneous tyrosinemia)

Dendritic keratitis, corneal ulcers, intellectual disability, painful keratosis

Carvajal syndrome***

Striate on palms; woolly hair, dilated cardiomyopathy; occasionally skin fragility, nail dystrophy, and hypodontia

PPK and woolly hair

Striate on palms; woolly hair, hypotrichosis, leukonychia

*Acral SCC can also develop in patients with mutilating PPK. **Haim–Munk syndrome is an allelic disorder that also features arachnodactyly, atrophic nail changes, and acro-osteolysis. ***The PPK in Naxos disease is occasionally focal/striate, overlapping with Carvajal syndrome. Table 58.1 Primary palmoplantar keratodermas (PPKs). More common disorders are in bold font. Other genodermatoses that feature PPK are listed in Table 58.2. Of note, the pattern can be different on the hands and feet, e.g. diffuse on the feet and focal on the hands. Progrediens means progressive, referring to the tendency to involve additional sites (e.g. the elbows and knees) over time. Mutilating refers to the development of digital constrictions and possible autoamputation (pseudoainhum; see Table 58.3). SCC, squamous cell carcinoma. Continued  

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PRIMARY PALMOPLANTAR KERATODERMAS (PPKS)

Disorder

Additional features

Punctate PPK, isolated Buschke–Fischer–Brauer (type 1 punctate PPK) Spiny keratoderma (type 2 punctate PPK) Marginal papular keratoderma: acrokeratoelastoidosis, focal acral hyperkeratosis (type 3 punctate PPK) Punctate keratoses of the palmar creases Porokeratosis punctata palmaris et plantaris Punctate PPK with associated features Cole disease

Guttate hypopigmentation, calcinosis cutis

PLACK syndrome

Peeling skin, leukonychia, cheilitis, knuckle pads

Acquired PPKs Keratoderma climactericum Aquagenic PPK Pityriasis rubra pilaris Associated with hypothyroidism/myxedema Associated with cancer Associated with lymphedema Arsenical keratoses Drug-induced keratoderma (e.g. lithium, verapamil, venlafaxine, glucan, tegafur, capecitabine, imatinib, sorafenib, sunitinib) Induced by dioxin or halogenated herbicides Associated with dermatomyositis: pityriasis rubra pilaris-like (Wong) type, “mechanic’s hands” in antisynthetase syndrome

Table 58.1 Primary palmoplantar keratodermas (PPKs). (cont’d)  

Fig. 58.2 Focal palmoplantar keratoderma. A Striate type with linear hyperkeratosis on the palm overlaying flexor tendons. B Areata type on the soles. B, Courtesy, Alfons Krol,  

MD, and Dawn Siegel, MD.

A

B

HEREDITARY KERATODERMAS DIFFUSE PALMOPLANTAR KERATODERMA WITHOUT ASSOCIATED FEATURES (ISOLATED, NON-SYNDROMIC) Diffuse Epidermolytic Palmoplantar Keratoderma (EPPK) Synonyms:  ■ Unna–Thost disease ■ Vörner disease ■ Vörner–Unna–

Thost type PPK ■ Keratosis palmoplantaris diffusa Vörner–Unna–Thost

History 926

In 1880, Thost described a family with diffuse non-transgrediens PPK. This was followed by Unna’s description of a clinically identical,

autosomal dominant PPK in two families. Although “Unna–Thost type” has been used to designate non-epidermolytic PPK (NEPPK), in 1992, Küster et al.7 reviewed the family described by Thost and found the histologic features of epidermolytic hyperkeratosis, which characterize the “Vörner type” of PPK. Subsequently, after keratin mutations were reported in epidermolytic PPK (EPPK), identical mutations were found in the descendants of the family studied by Thost8. This confusion underscores the need for careful histologic examination and sometimes multiple biopsy specimens to identify epidermolytic hyperkeratosis.

Epidemiology EPPK is likely the most common form of diffuse keratoderma, with an estimated incidence of ≥4.4 per 100 000 in Northern Ireland9.

Pathogenesis Mutations in KRT1 and KRT9 underlie diffuse EPPK. The expression of keratin 9 is limited to the suprabasal cell layers of palmar and plantar skin. In patients with diffuse EPPK, the majority of keratin 9

CHAPTER

GENODERMATOSES ASSOCIATED WITH DIGITAL CONSTRICTION BANDS (PSEUDOAINHUM)

Erythrokeratodermas (see Ch. 57)

Palmoplantar keratodermas (PPKs)

Keratitis–ichthyosis–deafness (KID) syndrome* Erythrokeratodermia variabilis* Progressive symmetric erythrokeratoderma* KDSR-related erythrokeratoderma* Erythrokeratodermia–cardiomyopathy syndrome*

Mal de Meleda* Vohwinkel syndrome* Loricrin keratoderma* KLICK (keratosis linearis with ichthyosis congenita and sclerosing keratoderma)* Olmsted syndrome* Papillon–Lefèvre syndrome* Clouston syndrome Pachyonychia congenita Diffuse epidermolytic PPK

Other ichthyoses (see Ch. 57) Epidermolytic ichthyosis (due to keratin 1 mutations)* Ichthyosis hystrix Curth–Macklin* Nonsyndromic autosomal recessive congenital ichthyoses** Sjögren–Larsson syndrome* Refsum syndrome CEDNIK (cerebral dysgenesis, neuropathy, ichthyosis and keratoderma) syndrome* MEDNIK (mental retardation, enteropathy, deafness, neuropathy, ichthyosis and keratoderma) syndrome* Autosomal recessive exfoliative ichthyosis (cystatin A deficiency)

Other disorders of cornification Epidermolytic ichthyosis Autosomal recessive congenital ichthyoses, including Harlequin and lamellar ichthyosis Erythrokeratodermia variabilis Progressive symmetric erythrokeratoderma

Other ectodermal dysplasias (see Chs 63 and 67)

Other genodermatoses

Ectodermal dysplasia–ectrodactyly–clefting (EEC) syndrome Cleft lip/palate ectodermal dysplasia Oculo-dento-digital dysplasia Naegeli–Franceschetti–Jadassohn syndrome, dermatopathia pigmentosa reticularis Autosomal recessive ectodermal dysplasia due to grainyhead-like 2 (GRHL2) mutations*,***

Epidermolysis bullosa Kindler syndrome Tuberous sclerosis Erythropoietic protoporphyria

Epidermolysis bullosa (EB; see Ch. 32) Skin fragility syndromes*: skin fragility–woolly hair, skin fragility– ectodermal dysplasia, plakoglobin deficiency EB simplex, basal: generalized severe*, with mottled pigmentation ≫ localized Junctional EB: generalized intermediate, with pyloric atresia Kindler syndrome

Other SAM (severe dermatitis–multiple allergies–metabolic wasting) syndrome Erythropoietic protoporphyria Rothmund–Thomson syndrome Poikiloderma with neutropenia, Clericuzio-type Familial pityriasis rubra pilaris* Dyskeratosis congenita Darier disease (usually punctate) Cowden syndrome (punctate) Linear PPK associated with epidermal nevus* Porokeratotic adnexal ostial nevus (PAON; encompasses porokeratotic eccrine ostial and dermal duct nevus [PEODDN])* Cardio-facio-cutaneous syndrome HOPP (hypotrichosis, acro-osteolysis/onychogryphosis, palmoplantar keratoderma, and periodontitis) syndrome* Cantu syndrome*: hyperkeratosis–hyperpigmentation syndrome Pigmentation defects, PPK, and cutaneous SCC (see Table 67.10)

*PPK is a major feature of the disorder. **Include congenital ichthyosiform erythroderma, lamellar ichthyosis, and harlequin ichthyosis. ***Features include nail dystrophy/loss, marginal PPK, hypodontia, enamel hypoplasia, oral hyperpigmentation, dysphagia, and deafness.

Table 58.2 Other genodermatoses that feature palmoplantar keratoderma (PPK).  

mutations are localized to a very small area within this gene that encodes the helix initiation motif in the 1A domain (see Ch. 56). Such mutations are highly disruptive to keratin filament assembly, causing tonofilament clumping and cytolysis that result in blistering as well as hyperkeratosis. Within palmoplantar skin, keratin 9 is thought to partner with keratin 1. Of note, mutations in keratin 1 and 10 are associated with epidermolytic ichthyosis (EI; formerly bullous congenital ichthyosiform erythroderma), in which epidermolytic hyperkeratosis is seen histologically (see Ch. 57). PPK in EI is predictive of a mutation in keratin 1, which is the only type II keratin expressed in palmoplantar skin. In contrast, EI due to keratin 10 mutations rarely has involvement of

58 Palmoplantar Keratodermas

OTHER GENODERMATOSES THAT FEATURE PALMOPLANTAR KERATODERMA (PPK)

*Digital constriction bands represent a common feature. Table 58.3 Genodermatoses associated with digital constriction bands (pseudoainhum). This is referred to as “mutilating” keratoderma. Congenital digital constriction bands can occur in the amniotic band sequence.  

palmoplantar skin, likely reflecting compensation by keratin 9, which is also a type I keratin. The majority of mutations in EI patients are in the critical 1A and 2B domains of the keratin molecule10. However, when keratin 1 defects underlie diffuse EPPK alone, including the “tonotubular“ subtype, the mutations are typically in the beginning of the 1B domain11. Although keratin 1 mutations have been reported in some families with the Greither type of EPPK, other Greither variants with NEPPK not associated with keratin 1 mutations have also been described. Of note, keratin 1 mutations have also been identified in patients with focal PPK (see below).

Clinical features The palmoplantar skin is initially red, followed by the appearance of thick, yellow hyperkeratosis by 3–4 years of age. In adults, there is confluent hyperkeratosis with a smooth, waxy surface and sharply demarcated erythematous border, sparing the dorsal aspects of the palms and soles (Fig. 58.5). Blistering and fissuring are not common but may occur during childhood or during oral retinoid therapy. Knuckle pads and thickened nails are occasionally present2,12. Disabling pain, especially of the palms, can occur in the “tonotubular” EPPK subtype11. The Greither type (PPK transgrediens and progrediens) presents with limited transgredient lesions, e.g. overlying the Achilles tendon, elbows, and knees.

Pathology EPPK shows the typical pattern of epidermolytic hyperkeratosis, which is characterized by vacuolated suprabasal keratinocytes with round or ovoid eosinophilic inclusions that represent large tonofilament aggregates at an ultrastructural level13. In the “tonotubular” subtype, electron microscopy shows whorls of keratin containing tubular structures11. Histologic findings also include coarse keratohyalin granules, acanthosis, and marked orthohyperkeratosis. Intraepidermal blistering and a mild superficial dermal inflammatory infiltrate may result from keratinocyte cytolysis (Fig. 58.6A). The findings of epidermolytic hyperkeratosis are often subtle and patchy, requiring a careful search and often multiple biopsy specimens to enable their identification.

Differential diagnosis EI can be distinguished clinically by the cutaneous involvement beyond the palms and soles. EPPK and NEPPK can be differentiated

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Fig. 58.3 Punctate palmoplantar keratoderma. Keratotic papules, some coalescing to form plaques, on the palms (A–C) and soles (D, E). C, Courtesy, Kalman Watsky, MD.

Genodermatoses



B

A

D

E

C

Fig. 58.4 Connexin channels and the gap junction plaque. Gap junctions are specialized transmembrane channels that connect the cytoplasm of neighboring cells, facilitating cell-to-cell communication. The status of the channels (i.e. open or closed) is controlled by mechanisms, including voltage, calcium concentration, pH, and phosphorylation. Each gap junction channel is composed of integral membrane proteins called connexins. The half-life of each connexin is short (i.e. hours), which results in a constant state of assembly and degradation of channels. Different connexins are expressed in a tissue- and differentiation-specific manner as well as in response to stimuli. Six connexin molecules oligomerize to form a connexon hemichannel with a central pore that has a maximum diameter of 2 nm. Connexons may be homomeric if all the participating molecules are of the same connexin species, or heteromeric if they differ. Connexons of adjacent cells dock in the intercellular gap to form a complete gap junction intercellular channel. Redrawn with permission from Richard G, Smith LE, Bailey  

CONNEXIN CHANNELS AND GAP JUNCTION PLAQUE Connexin

Connexon

Gap junction channels

Gap junction plaque

Intercellular

Homotypic

channel Homomeric Heterotypic Heteromeric Heteromeric

RA, et al. Mutations in the human connexin gene GJB3 cause erythrokeratoderma variabilis. Nat Genet. 1998;20:366–9.

Homomeric Homotypic

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Cell 1

Cell 2 Intercellular gap

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58 Palmoplantar Keratodermas

HISTOLOGIC PATTERNS IN SELECTED HEREDITARY PALMOPLANTAR KERATODERMAS (PPKS) Epidermolytic hyperkeratosis* Diffuse epidermolytic PPK: Vörner–Unna–Thost, “Greither” (epidermolytic variant) Focal palmoplantar and gingival keratosis

Orthohyperkeratosis, acanthosis, and papillomatosis Diffuse non-epidermolytic PPK: Bothnia, Nagashima, Kimonis, “Greither” (non-epidermolytic variant) Mal de Meleda (including Gamborg Nielsen type) Huriez, Howel–Evans, Papillon–Lefèvre, and Vohwinkel syndromes

Orthohyperkeratosis with focal parakeratosis, acanthosis, and papillomatosis

A

KLICK (keratosis linearis with ichthyosis congenita and sclerosing keratoderma) Erythrokeratodermia variabilis KID (keratitis–ichthyosis–deafness) syndrome

Orthohyperkeratosis with parakeratosis and hypergranulosis with transitional cells Loricrin keratoderma

Widening of intercellular spaces and partial dehiscence of keratinocytes Striate PPK types 1 and 2 Diffuse PPK due to a DSG1 mutation Carvajal syndrome Suprabasal epidermolysis bullosa simplex (EBS): acantholytic EBS, skin fragility syndromes

Epithelia with pale cytoplasm and eosinophilic inclusions Pachyonychia congenita Richner–Hanhart syndrome

Orthohyperkeratotic, focally parakeratotic column overlying depressed epidermis Punctate PPK, Buschke–Fischer–Brauer type Punctate keratoses of the palmar creases Focal acral hyperkeratosis

Orthohyperkeratotic, focally parakeratotic column overlying depressed epidermis with fragmentation and loss of elastic fibers Acrokeratoelastoidosis

Parakeratotic column overlaying depressed epidermis devoid of vacuolization and dyskeratosis

B

Spiny keratoderma

Parakeratotic column overlaying depressed epidermis with vacuolization and dyskeratosis Porokeratosis

*When epidermolytic hyperkeratosis is present, oral retinoid therapy can exacerbate skin fragility and should be avoided.

Table 58.4 Histologic patterns in selected hereditary palmoplantar keratodermas (PPKs).  

histologically by the absence of epidermolytic hyperkeratosis in the latter; they are not distinguishable clinically, although the erythematous border of EPPK tends to be more pronounced.

Management Factors to consider when selecting treatment for diffuse PPK include the severity of symptoms, degree of hyperkeratosis, and age of the patient. Mechanical debridement with a blade or dental drill is useful for troublesome areas, followed by application of a keratolytic agent to help avoid fissure formation. Options for keratolytic therapy include 50% propylene glycol in water under plastic occlusion several nights per week, lactic acid- and urea-containing creams and lotions, and salicylic acid 4–6% in petrolatum; the latter should not be applied to large areas in young children to avoid salicylism from systemic absorption (see Ch. 129).

C

Fig. 58.5 Diffuse epidermolytic palmoplantar keratoderma (Vörner–Unna– Thost). Diffuse, hyperkeratosis with waxy surface on the palm (A) and soles (B, C), with sharp demarcation. Note the red borders (A, C). C, Courtesy, Alfons Krol, MD,  

and Dawn Siegel, MD.

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Oral retinoids may improve the hyperkeratosis, but even low doses can lead to excessive peeling and increased fragility of volar skin in EPPK14. Topical calcipotriene (calcipotriol) has reportedly been helpful15.

Diffuse Non-epidermolytic Palmoplantar Keratoderma (NEPPK) Diffuse NEPPK represents a heterogeneous group of non-syndromic forms of PPK that do not show epidermolytic hyperkeratosis histologically. This category includes Bothnia16, Kimonis17, and Nagashima18 types of PPK as well as Mal de Meleda19. The Greither type (PPK transgrediens and progrediens) lacks a clear definition and is heterogeneous, with both epidermolytic and non-epidermolytic variants (see EPPK above)20–22. The Gamborg Nielsen (Norrbotten) type23 is currently regarded as a variant of Mal de Meleda24.

Epidemiology and pathogenesis A

B

Fig. 58.6 Histologic features of palmoplantar keratoderma. A In epidermolytic hyperkeratosis, suprabasal keratinocytes show vacuolated cytoplasm, intracytoplasmic eosinophilic granules, and coarse keratohyalin granules. B In non-epidermolytic keratoderma, an extremely thick orthohyperkeratotic horny layer and acanthotic epidermis are seen. Courtesy,  

Luis Requena, MD.

An autosomal dominant form of NEPPK described in a family from Bothnia in Northern Sweden and three English pedigrees is due to heterozygous missense mutations in AQP5, which encodes aquaporin 5. Aquaporins are transmembrane proteins that allow the osmotic movement of water across the cell membrane. Aquaporin 5 is expressed by keratinocytes in the granular layer, and the gain-of-function mutations that cause Bothnia-type NEPPK lead to increased keratinocyte water uptake rather than transepidermal water loss16.

HUMAN CONNEXIN DISORDERS

Disorder

Inheritance

Connexin

Gene

Major organ distribution Ubiquitous, including liver, cochlea, mammary gland, skin and appendages, mucous membranes, pancreas, kidney, intestine, lung

Non-syndromic hearing impairment (DFNB1)

AR

Cx26

GJB2

Non-syndromic hearing impairment (DFNA3)

AD

Cx26

GJB2

Palmoplantar keratoderma and hearing impairment, including Vohwinkel syndrome

AD

Cx26

GJB2

Bart–Pumphrey syndrome

AD

Cx26

GJB2

Keratitis–ichthyosis–deafness (KID) syndrome & hystrix-like– ichthyosis–deafness (HID) syndrome

AD

Cx26 (Cx30)*

GJB2 (GJB6)*

Porokeratotic adnexal ostial nevus (PAON)

Mosaic

Cx26

GJB2

Non-syndromic hearing impairment (DFNA3)

AD

Cx30

GJB6

Brain, cochlea, skin

Clouston syndrome

AD

Cx30

GJB6

Erythrokeratodermia variabilis

AD≫AR

Cx30.3

GJB4

Skin, kidney

Erythrokeratodermia variabilis

AD≫AR

Cx31

GJB3

Skin, eye, placenta, kidney, testes, cochlea, Schwann cells

Non-syndromic hearing impairment

AR≫AD

Cx31

GJB3

Peripheral sensory neuropathy and hearing impairment

AD

Cx31

GJB3

Charcot–Marie–Tooth disease

X-linked dominant

Cx32

GJB1

Brain, Schwann cells, liver, thyroid, kidney, pancreas, uterus

Cx37

GJA4

Gonads, lung, endothelium, heart, skin

AD

Cx43

GJA1

Ubiquitous, including eyes, teeth, musculoskeletal, brain, heart, skin

Polymorphism may be a marker for atherosclerotic plaque development Oculo-dento-digital dysplasia Erythrokeratodermia variabilis et progressiva

AD

Cx43

GJA1

Keratoderma-hypotrichosis-leukonychia totalis

AD

Cx43

GJA1

ILVEN

Mosaic

Cx43*

GJA1*

Syndactyly, type III

AD

Cx43

GJA1

Hypoplastic left heart syndrome

Oligogenic

Cx43

GJA1

Cataract, zonular pulverulent-3

AD

Cx46

GJA3

Lens, heart, kidney, peripheral nervous system

Atrial fibrillation, familial 11

AD

Cx40

GJA5

Heart

Hereditary lymphedema

AD

Cx47

GJC2

Lymphatic vessels, CNS

Hypomyelinating leukodystrophy

AR

Cx47

GJC2

Cataract, zonular pulverulent-1

AD

Cx50

GJA8

Lens, cornea, heart

*Reported in a single patient to date. 930

Table 58.5 Human connexin disorders. Disorders in bold feature palmoplantar keratoderma. AD, autosomal dominant; AR, autosomal recessive; CNS, central nervous system; GJ, gap junction. Adapted with permission from Richard G. Connexin disorders of the skin. Adv Dermatol. 2001;17:243–77.  

CHAPTER

Disorder

Inheritance

Mutated genes

Protein products

Vörner–Unna–Thost EPPK

AD

KRT9 > KRT1

Keratin 9 Keratin 1 (1B domain)

Kimonis NEPPK

AD

KRT1

Keratin 1 (V1 domain)

Bothnia NEPPK

AD

AQP5

Aquaporin 5

Nagashima NEPPK

AR

SERPINB7

Serpin family B member 7

Mal de Meleda

AR

SLURP1

Secreted Ly6/PLAUR-domain containing 1

Loricrin keratoderma

AD

LOR

Loricrin

KLICK

AR

POMP

Proteasome maturation protein

Vohwinkel syndrome, Bart–Pumphrey syndrome, PPK with deafness

AD

GJB2

Connexin 26

Mitochondrial PPK with deafness

Mt

MT-TS1

Mt tRNA serine 1

Diffuse without associated features

58 Palmoplantar Keratodermas

PALMOPLANTAR KERATODERMAS (PPKS) – UNDERLYING GENETIC MUTATIONS

Diffuse with associated features

PPK with sex reversal & SCC

AR

RSPO1

R-spondin 1

Clouston syndrome

AD

GJB6

Connexin 30

Keratoderma–hypotrichosis–leukonychia totalis

AD

GJA1

Connexin 43

OODD, SSP syndrome

AR

WNT10A

Wnt 10A

Olmsted syndrome

AD > AR

TRPV3

Transient receptor potential vanilloid 3

XR

MBTPS2

Membrane-bound transcription factor peptidase, site 2

Papillon–Lefèvre syndrome, Haim–Munk syndrome

AR

CTSC

Cathepsin C

Naxos disease

AR

JUP

Junction plakoglobin

Striate PPK type 1

AD

DSG1

Desmoglein 1

Striate PPK type 2

AD

DSP

Desmoplakin

Striate PPK type 3

AD

KRT1

Keratin 1 (V2 tail)

Focal PPK

AD

KRT6C KRT16

Keratins 6C and 16

Pachyonychia congenita

AD

KRT6A KRT6B KRT6C KRT16 KRT17

Keratins 6A, 6B, 6C, 16, and 17

Richner–Hanhart syndrome

AR

TAT

Tyrosine aminotransferase

Howel–Evans syndrome

AD

RHBDF2

Rhomboid 5 homolog 2

Carvajal syndrome

AR > AD

DSP

Desmoplakin

PPK and woolly hair

AR

KANK2

KN motif and ankyrin repeat domains 2

AD

AAGAB

α- and γ-adaptin-binding protein p34

Cole disease

AD

ENPP1

Ectonucleotide pyrophosphate/phosphodiesterase 1

PLACK syndrome

AR

CAST

Calpastatin

Focal without associated features

Focal with associated features

Punctate without associated features Buschke–Fischer–Brauer (type 1)* Punctate with associated features

*A second locus for punctate PPK on 8q was found to be potentially associated with a heterozygous missense mutation in the collagen type XIV α1 chain gene (COL14A1) in a single Chinese family. Table 58.6 Palmoplantar keratodermas (PPKs) – underlying genetic mutations. The protein products represent epidermal proteases/related proteins/enzymes (gray) or components of the keratinocyte cytoskeleton (pink), cornified envelope (yellow), desmosome (blue), gap junction/other transmembrane channels (green). AD, autosomal dominant; AR, autosomal recessive; GJA1, gap junction α1; GJB2/6, gap junction β2/6; KLICK, keratosis linearis–ichthyosis congenital–sclerosing keratoderma; Mt, mitochondrial; OODD, odonto-onycho-dermal dysplasia; PLACK, peeling skin, leukonychia, acral punctate keratoses, cheilitis, knuckle pads; SCC, squamous cell carcinoma; SSP, Schöpf–Schulz–Passarge; tRNA, transfer RNA.  

The form of NEPPK described by Kimonis is caused by a heterozygous mutation in a highly conserved lysine residue in the V1 domain of keratin 1 that does not result in epidermolytic hyperkeratosis17. Nagashima-type NEPPK, an autosomal recessive disorder almost exclusively observed in Asia, is caused by biallelic nonsense mutations

in SERPINB7. This gene encodes the serine protease inhibitor family B member 7, which has an unknown protease target in the skin25. Mal de Meleda is an autosomal recessive condition that was first described in inhabitants of the island of Mljet (Meleda) off the Dalmatian coast. It is caused by biallelic mutations in SLURP1 (secreted

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Excision of hyperkeratotic skin with split-thickness skin grafting represents an option to relieve functional impairment32.

DIFFUSE PALMOPLANTAR KERATODERMAS WITH ICHTHYOSIS Loricrin keratoderma and keratosis linearis–ichthyosis congenita– sclerosing keratoderma (KLICK) have distinctive skin findings beyond the palms and soles. PPK is also a component of other ichthyoses that are discussed in Chapter 57 (see Table 58.2).

Loricrin Keratoderma Synonyms:  ■ Camisa variant of Vohwinkel syndrome ■ Mutilating keratoderma with ichthyosis ■ Variant Vohwinkel syndrome ■ Vohwinkel syndrome with ichthyosis

Fig. 58.7 Mal de Meleda. Diffuse, yellow hyperkeratosis characterized by maceration, erythema in areas with reduced hyperkeratosis, progression beyond the palmar area (transgrediens), and a well-defined red border.  

leukocyte antigen-6/urokinase-type plasminogen activator related protein 1), which is expressed in the granular layer of the epidermis26. SLURP1 acts as a ligand of the α7-nicotinic acetylcholine receptor and plays a role in epidermal differentiation. Heterozygous female carriers may have a mild clinical phenotype.

Clinical features The clinical findings and time course of the different types of NEPPK are overall similar to those of EPPK (see above). The hyperkeratosis is variably thick and hyperhidrosis is common, with frequent dermatophyte infections and pitted keratolysis. The Bothnia type features a characteristic white spongy appearance upon exposure to water16. In Mal de Meleda, progressive transgredient hyperkeratosis begins during early infancy and becomes severe, impairing the mobility of hands and resulting in hyperhidrotic maceration, severe malodor, and fissures (Fig. 58.7). Fungal superinfection is common, and hyperkeratosis of the fingers may lead to sclerodactyly and digital constrictions (pseudoainhum). The elbows, knees, wrists, and ankles as well as the dorsal surfaces of the hands and feet can be involved, and the nails show thickening, koilonychia, and subungual hyperkeratosis. Angular cheilitis and involvement of the lips and perioral skin may be observed19,27. Hyperpigmented macules, melanoma, and Bowen disease within the keratotic areas have been reported28,29.

Differential diagnosis In addition to diffuse EPPK, exfoliative ichthyosis and aquagenic palmoplantar keratoderma may be diagnostic considerations.

Pathology Histologically, palmoplantar skin shows orthohyperkeratosis, hypergranulosis or normogranulosis, and acanthosis (Fig. 58.6B). A moderate perivascular lymphocytic infiltrate may be present. In Mal de Meleda, papillomatosis is a characteristic finding. PAS staining should be performed to exclude infection by dermatophytes.

Management

932

Stronger keratolytic therapy may be helpful, such as 5–10% salicylic acid in white soft paraffin, or 5–6% salicylic acid in 70% propylene glycol gel; occlusion for a few nights per week enhances efficacy, and mechanical debridement can also be performed. Low-dose acitretin (0.2–0.5 mg/ kg daily) may be considered, especially for patients with functional impairment. Fungal superinfection and bacterial overgrowth should be treated. Responses to oral erythromycin and topical tacrolimus have been described in the Bothnia and Nagashima types, respectively30,31.

This disorder is caused by mutations in the gene encoding loricrin, a glycine-rich cornified envelope protein33–35 (see Ch. 56). Mutant loricrin is transported to the nucleus, where it is thought to interfere with regulation of cornification36,37. Generalized desquamation or features of a collodion baby may be evident at birth, with subsequent evolution to a mild generalized ichthyosis. During childhood, diffuse NEPPK develops, with a “honeycomb” pattern and associated findings that overlap with those of Vohwinkel syndrome, including keratotic digital constrictions (pseudoainhum), knuckle pads, and warty keratoses on extensor surfaces38. However, the absence of deafness as well as the presence of ichthyosis distinguish loricrin keratoderma from Vohwinkel syndrome39. The differential diagnosis may also include ichthyosis hystrix Curth–Macklin due to mutations in the variable tail region of keratin 1 (see Ch. 57). Histologic features of loricrin keratoderma include hyperkeratosis with parakeratotic cells, scattered transitional cells, and a broad stratum granulosum with focal perinuclear vacuolization38,39. Keratinocyte nuclei demonstrate distinctive immunoreactivity for loricrin36. Isotretinoin therapy has been reported to be effective38.

Keratosis Linearis–Ichthyosis Congenita– Sclerosing Keratoderma (KLICK) Synonym:  ■ KLICK syndrome KLICK is an autosomal recessive disorder caused by mutations in POMP, which encodes proteasome maturation protein40. The resulting proteasome insufficiency disturbs terminal epidermal differentiation and interferes with processing of profilaggrin. Patients present with mild congenital ichthyosis and diffuse, transgredient PPK with development of digital constriction bands41,42. Other features include flexion deformity of the fingers with associated sclerosis and parallel linear arrays of keratotic papules in the flexural areas of the extremities. Development of aggressive squamous cell carcinoma (SCC) in affected skin has been described43. Histologic evaluation shows orthohyperkeratosis, focal parakeratosis, acanthosis, and hypergranulosis with characteristic irregular keratohyalin granules. Immunostaining for filaggrin is positive in the cornified layer rather than the granular layer.

DIFFUSE PALMOPLANTAR KERATODERMAS WITH ASSOCIATED FEATURES/SYNDROMIC Vohwinkel Syndrome Synonyms:  ■ Keratoderma hereditaria mutilans ■ Cicatrizing keratoderma with hearing impairment ■ Keratoderma with sensorineural deafness ■ Vohwinkel syndrome with deafness



Krol, MD, and Dawn Siegel, MD.

Histologic findings are nonspecific, with papillomatosis and prominent orthohyperkeratosis. Treatment with oral retinoids can improve the PPK56, while the cicatricial bands require surgical intervention57. Cochlear implantation may be performed for the hearing loss58.

Mitochondrial Palmoplantar Keratoderma With Hearing Impairment This PPK has a honeycomb appearance and may be either focal or diffuse, often with calluses on the heels and toes. Sensorineural hearing loss typically develops during childhood59,60. The causative mutation in mitochondrial DNA (mtDNA) affects a serine transfer RNA (tRNA)61,62.

A

CHAPTER

58 Palmoplantar Keratodermas

Fig. 58.8 Mutilating palmoplantar keratoderma in Vohwinkel syndrome. A Diffuse honeycombed keratoderma of the sole. B Pseudoainhum formation. A, Courtesy, Alfons

Huriez Syndrome Synonyms:  ■ Palmoplantar keratoderma with scleroatrophy ■

Sclerotylosis

This rare autosomal dominant disease is characterized by an onset during infancy of diffuse scleroatrophy of the hands, with the eventual development of sclerodactyly and absent dermatoglyphs. The mild PPK presents as diffuse parchment-like skin on the palms and, to a lesser degree, the soles; circumscribed hyperkeratosis over pressure points may develop during adulthood. Hypoplastic nail changes (e.g. thinning, longitudinal ridging, fissuring) are also seen63. The risk of developing SCC in areas of atrophic skin is increased by ≥100-fold64,65. The differential diagnosis may include Kindler syndrome, dyskeratosis congenita, and PPK with sex reversal and SCC. Histologic features of the keratoderma include orthohyperkeratosis, acanthosis, and hypergranulosis. A characteristic finding is almost complete absence of Langerhans cells in the affected skin. The gene responsible for Huriez syndrome has been mapped to 4q23.

B

Fig. 58.9 Bart– Pumphrey syndrome. Leukonychia and knuckle pads in a patient with sensorineural deafness.  

Courtesy, Alfons Krol, MD, and Dawn Siegel, MD.

Palmoplantar Keratoderma With Sex Reversal and Squamous Cell Carcinoma This rare autosomal recessive syndrome, thus far described in several consanguineous Italian kindreds66, is due to mutations in the R-spondin 1 gene (RSPO1), which encodes a protein that activates β-catenin signaling and has an important role in gonadal development66–68. In addition to a diffuse NEPPK that develops during infancy, there is a marked predisposition to the development of acral SCC. Affected individuals with an XX genotype have either: (1) a male phenotype (i.e. female-tomale sex reversal), often associated with hypospadias and hypogonadism; or (2) ambiguous genitalia, sometimes with hermaphroditism (existence of both male and female gonadal structures). Other manifestations include sclerodactyly with variable cutaneous atrophy resembling Huriez syndrome67, nail dystrophy (e.g. hypoplasia, longitudinal ridging, skin growth over the nail plate), and periodontitis leading to early loss of teeth.

Clouston Syndrome Vohwinkel syndrome is autosomal dominantly inherited and caused by mutations in the gap junction β2 gene (GJB2) encoding connexin 2644–46. This gene is also implicated in Bart–Pumphrey and keratitis– ichthyosis–deafness (KID) syndromes47,48 (see Table 58.5). Connexin 26 is expressed in the palmoplantar epidermis, sweat glands, and cochlea of the inner ear. As a major gap junction protein, it is crucial for signal transduction involved in epithelial differentiation and sensorineural functions49,50. Vohwinkel syndrome is characterized by pitted and stippled, honeycomb-like diffuse PPK and characteristic stellate (“starfish”) keratoses on the knuckles (Fig. 58.8A). Digital constriction bands may lead to autoamputation (pseudoainhum) (Fig. 58.8B)51,52. Patients have nonprogressive high-tone sensorineural hearing loss, which may be overlooked during infancy53. Bart–Pumphrey syndrome is characterized by keratoses over the interphalangeal and metacarpophalangeal joints (“knuckle pads”) and leukonychia (Fig. 58.9), which may improve with age, as well as a honeycomb-like PPK and hearing loss as in Vohwinkel syndrome54,55.

Synonym:  ■ Hidrotic ectodermal dysplasia 2 Clouston syndrome is an autosomal dominant disorder caused by missense mutations in the gap junction β6 gene (GJB6), which encodes connexin 3069. The dysfunctional connexin 30 disturbs cell–cell communication in epithelial cells. Although first reported in a large FrenchCanadian kindred, Clouston syndrome has also been described in a variety of other ethnic groups. This condition features diffuse PPK in conjunction with hypotrichosis and nail dystrophy70, thereby qualifying as an ectodermal dysplasia (see Ch. 63). The PPK initially develops over pressure points and then becomes diffuse, increasing in severity with age. In addition, thickened skin with a “pebbled” appearance is often evident on the dorsal aspects of the digits, knees, and elbows (Fig. 58.10). Small papules in a grid-like array that corresponds to eccrine acrosyringia may be seen, especially on the distal digits where the dermatoglyphs are most prominent.

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9

Fig. 58.10 Clouston syndrome. Note the “pebbled” skin on the dorsal aspect of the toes as well as the dystrophic nail plates. Courtesy, D Sasseville, MD, and R Wilkinson,  

MD.

Progressive hypotrichosis that can eventuate in complete alopecia affects the scalp, eyebrows, eyelashes, and axillary and genital regions; the hair is typically wiry, brittle, and pale. The nails, which may be normal or milky white at birth, gradually become thickened and dystrophic, displaying short nail plates that are easily shed (see Fig. 58.10). The nail abnormalities may mimic those of pachyonychia congenita or other syndromes of “hair–nail hypoplasia”71. Histologic evaluation of thickened palms and soles shows orthohyperkeratosis with a normal granular layer. Papular lesions may demonstrate proliferation of ductal structures within a fibrovascular stroma. Ultrastructural examination of the hair shows disorganization of the hair fibers, with a loss of the hair shaft cuticle.

Odonto-onycho-dermal Dysplasia Synonyms:  ■ Tricho-odonto-onycho-dermal dysplasia ■ Schöpf–

Schulz–Passarge syndrome ■ PPK with cystic eyelids, hypodontia, and hypotrichosis ■ Eccrine tumors with ectodermal dysplasia Odonto-onycho-dermal dysplasia encompasses a diverse group of autosomal recessive disorders caused by mutations in WNT10A, which encodes a signaling molecule with a critical role in the development of ectodermal appendages72 (see Fig. 55.6). The clinical features include various combinations of diffuse PPK, facial telangiectasias or reticulate erythema, dental anomalies (e.g. hypodontia, small teeth), nail dystrophy, and hypotrichosis (see Table 63.13)73. Patients with Schöpf– Schulz–Passarge syndrome also develop hidrocystomas of the eyelids and other adnexal tumors (e.g. poromas, tumors of the follicular infundibulum) during adulthood74. Histologic examination of the PPK demonstrates eccrine syringofibroadenomas75.

Olmsted Syndrome Synonym:  ■ Mutilating PPK with periorificial keratotic plaques

934

Autosomal dominant and the less common autosomal recessive variants of Olmsted syndrome are caused by different gain-of-function mutations in the transient receptor potential vanilloid 3 gene (TRPV3)76,77. TRP cation-selective ion channels are involved in epidermal differentiation, hair growth, and the modulation of inflammation, pain, and pruritus78. The X-linked recessive variant of Olmsted syndrome, which presents with total alopecia and severe nail dystrophy, results from specific mutations in the membrane-bound transcription factor peptidase site 2 gene (MBTPS2). The zinc metalloprotease encoded by this gene is essential for cholesterol homeostasis and

endoplasmatic reticulum stress response79. Interestingly, MBTPS2 mutations also underlie IFAP syndrome (ichthyosis follicularis with atrichia and photophobia) and KFSD (keratosis follicularis spinulosa decalvans) (see Chs 38 and 57). Olmsted syndrome features a sharply defined, diffuse PPK with an erythematous border, and progression over time leads to flexion contractures and digital constriction or autoamputation. Erythema and warty hyperkeratosis develop in the perioral and perianal regions as well as in other intertriginous sites80, resulting in pain and pruritus81. Keratoses in linear streaks and with a perifollicular distribution also appear in the flexures of the extremities82,83. Additional findings may include alopecia, nail dystrophy, oral involvement (e.g. keratotic plaques, perio­dontal disease), corneal dysplasia, erythromelalgia, deafness, and joint laxity8. Recurrent skin infections are common, and the development of SCC and melanoma within areas of keratoderma has been reported84,85. The differential diagnosis may include Mal de Meleda, Vohwinkel syndrome, KDSR (3-ketodihydrosphingosine reductase)-related erythrokeratoderma, pachyonychia congenita, acrodermatitis enteropathica, mucocutaneous candidiasis, and psoriasis. Histology of affected skin demonstrates acanthosis with orthohyperkeratosis and parakeratosis, papillomatosis, and a perivascular inflammatory infiltrate; an increased number of mast cells has also been observed86. Oral retinoid therapy often produces some improvement87. There are reports of benefit from excision of hyperkeratotic areas with skin grafting and administration of the epidermal growth factor receptor (EGFR) inhibitor erlotinib88,89.

Papillon–Lefèvre and Haim–Munk Syndromes Papillon–Lefèvre syndrome is an autosomal recessive condition caused by mutations in CTSC which encodes cathepsin C, a lysosomal cysteine protease that activates serine proteases found in inflammatory cells as well as the skin90,91. This disorder is characterized by a diffuse, transgredient PPK with associated erythema. Pseudoainhum and hyperkeratotic psoriasiform plaques on the elbows and knees often develop. An additional feature is periodontitis with onset during childhood, which leads to premature loss of teeth. There is a predisposition to pyogenic infections of the skin and internal organs, including hepatic abscesses92. Haim–Munk syndrome is an allelic condition that also features onychogryphosis, arachnodactyly, and acro-osteolysis93,94. Acral melanoma and SCC have been reported in patients with Papillon–Lefèvre syndrome95–97. Oral retinoid therapy not only lessens the hyperkeratosis but also decreases the risk of periodontal and infectious complications98,99.

Naxos Disease Synonym:  ■ Diffuse NEPPK with woolly hair and arrhythmogenic cardiomyopathy

This autosomal recessive disorder described in families from the Greek island of Naxos is defined by keratoderma, woolly hair, and a lifethreatening cardiomyopathy100,101. Naxos disease results from a homozygous truncating mutation in the gene encoding plakoglobin (JUP), a component of both desmosomes and adherens junctions in the epidermis, hair follicle, and cardiac muscle102. A member of the armadillo protein family, plakoglobin links the inner and outer portions of the desmosomal plaque by binding to the cytoplasmic domain of cadherins (e.g. desmoglein, desmocollin) (see Ch. 56). Other biallelic mutations in JUP can result in alopecia (rather than woolly hair) together with focal PPK and cardiomyopathy, as well as acantholytic epidermolysis bullosa simplex (EBS) and EBS skin fragility syndrome (see Ch. 32), neither of which is associated with cardiac abnormalities. Naxos disease classically presents during the first year of life with a diffuse NEPPK, but some patients have focal (striate/areata) involvement103. Woolly scalp hair is usually evident at birth. The right ventricular cardiomyopathy has virtually 100% penetrance, typically manifesting with arrhythmias, heart failure, and/or sudden death during adolescence. Therefore, cardiac evaluation is mandatory for any patient with a PPK plus woolly hair (or alopecia) and their potentially affected family members. Treatment with an automatic

FOCAL PALMOPLANTAR KERATODERMA WITHOUT ASSOCIATED FEATURES (ISOLATED, NON-SYNDROMIC) Striate/Focal Palmoplantar Keratoderma Synonyms:  ■ Brünauer–Fuhs–Siemens PPK ■ Keratosis

palmoplantaris areata et striata ■ Keratosis palmoplantaris varians Wachters ■ Keratosis palmoplantaris nummularis ■ Hereditary painful callosities (historical) Striate palmoplantar keratoderma (SPPK) is an autosomal semidominant condition caused by mutations in at least three different genes that encode proteins with roles in desmosomal function (see Fig. 56.8)105: (1) type 1 – desmoglein 1 (DSG1)106; (2) type 2 – desmoplakin (DSP)107; and (3) type 3 – keratin 1 (KRT1), V2 tail domain108. In addition, heterozygous mutations in DSG1 sometimes produce diffuse PPK109,110. Interestingly, SAM syndrome – severe dermatitis, multiple allergies, and metabolic wasting – features focal PPK and can result from biallelic DSG1 mutations; affected individuals’ parents with heterozygous DSG1 mutations have milder focal PPK alone111. SAM syndrome can also be caused by a heterozygous DSP mutation. Focal areata NEPPK with absent or very mild associated nail dystrophy is occasionally due to mutations in keratin 6c or 16 (see Pachyonychia congenita below). The characteristic clinical features of all three types of SPPK are linear keratotic bands on the palms and flexor aspects of the fingers and island-like areas of hyperkeratosis over pressure points on the soles (see Fig. 58.2). Lesions usually develop in adolescence or early adulthood and are exacerbated by mechanical stress (e.g. from manual labor)112. Larger plantar keratoses are often painful. In addition to orthohyperkeratosis, widening of the intercellular spaces and partial dehiscence of the suprabasal keratinocytes represent characteristic findings shared by SPPK types 1 and 2, diffuse PPK due to a DSG1 mutation, Carvajal syndrome, and suprabasal forms of EBS (EBS with acantholysis, skin fragility syndromes; see Ch. 32)113. At the ultrastructural level, the size of the desmosomes is reduced in type 1 SPPK, while marked perinuclear aggregation of keratin filaments is seen in type 2 SPPK114. There is often a good response to oral acitretin and/or application of keratolytic agents112.

FOCAL PALMOPLANTAR KERATODERMA WITH ASSOCIATED FEATURES/SYNDROMIC Pachyonychia Congenita Synonyms:  ■ Pachyonychia congenita type 1 (Jadassohn–

Lewandowsky; historic) ■ Pachyonychia congenita type 2 (Jackson– Lawler; historic)

History, epidemiology, and pathogenesis Pachyonychia congenita (PC) is a group of autosomal dominant genodermatoses caused by mutations in keratins 6A, 6B, 6C, 16, and 17; ectodermal structures that are affected include the nail bed,

palmoplantar skin, pilosebaceous unit, oral mucosa, and teeth115,116. Historically, PC was classified as type 1 (Jadassohn–Lewandowsky) due to keratin 6a/16 defects, featuring more severe PPK and oral leukokeratosis, and type 2 (Jackson–Lawler) due to 6b/17 defects, featuring pilosebaceous cysts and neonatal teeth. However, extensive genotype– phenotype ana­lysis led to recognition of the considerable overlap between these groups, and the current classification system is based on the affected keratin: PC-6a (~40% of PC patients), PC-6b (~5–10%), PC6c (90% of PC patients, regardless of which keratin is affected: toenail dystrophy, focal keratoderma, and plantar pain (Fig. 58.11A–D)116,123. Wedge-shaped subungual hyperkeratosis leads to elevation, thickening, and darkening of the nail plate, which may assume an “omega” shape with more prominent involvement distally than proximally. There may or may not be involvement of all of the digits, but the toes, thumbs, and index fingers tend to have more severely affected nails. In infants, erythema of the nail bed can precede the appearance of dystrophic changes. Thick yellow plantar keratoses develop in sites of pressure, with the formation of calluses, fissures, and blisters in areas of friction, particularly during the summer; spread to the dorsal feet occasionally occurs in association with trauma or infection. Severe pain often makes it difficult for patients to walk, and palmoplantar hyperhidrosis and paronychia are common findings. Other variable features include follicular keratoses on the knees and elbows, angular cheilitis, oral leukokeratosis (Fig. 58.11E), natal teeth (primarily in PC-17), and less often pili torti or other hair abnormalities123,124. Steatocystomas, vellus hair cysts, and other pilosebaceous cysts (e.g. epidermoid) develop in approximately half of patients overall and >90% of those with PC-17123 (Fig. 58.11F). Laryngeal involvement can result in hoarseness and occasionally respiratory tract obstruction125.

Pathology In hyperkeratotic skin and oral plaques, the keratinocytes in the superficial epidermis and mucosal epithelium have a characteristic pale cytoplasm and eosinophilic inclusions. At the ultrastructural level, these findings correlate with perinuclear condensation of mutated keratin filaments and vacuolization of the peripheral cytoplasm124. Similar histologic findings are seen in white sponge nevus, which is caused by keratin 4 and 13 mutations.

Differential diagnosis The differential diagnosis for PC-like nail changes includes Clouston syndrome, which is distinguished by diffuse (rather than focal) PPK and more prominent alopecia, and isolated autosomal recessive nail dysplasia due to mutations in the frizzled 6 gene (FZD6)126,127.

Treatment Symptomatic treatment for the hyperkeratotic skin and dystrophic nails includes mechanical modalities (e.g. cutting, filing, grinding) following softening via soaking, as well as application of emollients and keratolytics128. Surgical removal of nails with attempts at matrix ablation is usually not effective, as the keratins involved in PC are expressed in the nail bed. Use of orthotics and treatment of hyperhidrosis with botulinum toxin type A injections may reduce blistering and pain. Oral retinoids can reduce hyperkeratosis but may increase tenderness128. Treatment with small interfering RNAs (siRNAs) that specifically target and silence expression of dominant-negative mutant K6a has been investigated, with the pain of intradermal injection representing a limiting factor. Use of topical sirolimus or oral simvastatin to downregulate K6a promoter activity in patients with K6a defects is under investigation129,130.

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A

B

C

F

E

Fig. 58.11 Pachyonychia congenita. A–C Plantar hyperkeratosis accentuated over pressure points and hypertrophic nail dystrophy with wedge-shaped subungual hyperkeratosis. D Painful focal plantar keratoderma with associated erythema and blistering. E Oral leukokeratosis. F Steatocystomas in the axilla. A,B,E, Courtesy,  

D

Julie V Schaffer, MD; D, Courtesy, Alfons Krol, MD, and Dawn Siegel, MD; F, Courtesy, Dr J Valverde.

Richner–Hanhart Syndrome Synonyms:  ■ Tyrosinemia type II ■ Tyrosine aminotransferase

deficiency ■ Tyrosine transaminase deficiency ■ Oculocutaneous tyrosinemia

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This is a rare autosomal recessive disorder of tyrosine metabolism caused by mutations in the gene that encodes hepatic tyrosine aminotransferase (TAT)131–133. Photophobia and dendritic keratitis with corneal ulcerations often appear in the first year of life. Tyrosine crystal

deposition is seen on slit-lamp examination, and serum and urinary tyrosine levels are elevated. Painful, focal hyperkeratotic plaques on the palms and soles represent the characteristic cutaneous finding (Fig. 58.12). The skin changes can appear during early childhood or be delayed until adolescence; blistering and hyperhidrosis may be seen. Progressive intellectual disability occurs if the patient is not treated with a restrictive diet. The histologic findings of pale epithelia with eosinophilic inclusions resembles that of pachyonychia congenita. Electron microscopy reveals clumped tonofilaments with adherent globoid keratohyalin granules and needle-shaped tyrosine crystalline inclusions within keratinocytes132.

CHAPTER

Palmoplantar Keratodermas

58

Fig. 58.12 Richner–Hanhart syndrome (tyrosinemia II). Focal painful keratoses on the plantar surface in a patient with corneal ulcers and mental retardation.  

Courtesy, Jean L Bolognia, MD.

A diet in which tyrosine and phenylalanine are restricted will clear the keratitis and keratoderma, and it may delay or prevent cognitive impairment134.

Fig. 58.13 Howel–Evans syndrome. Focal palmoplantar keratoderma in association with carcinoma of the esophagus. Courtesy, Alfons Krol, MD, and Dawn Siegel, MD.  

Howel–Evans Syndrome

Fig. 58.14 Carvajal syndrome. A Focal plaque-like hyperkeratosis over pressure points on the soles. B Woolly hair.  

Synonyms:  ■ Focal non-epidermolytic PPK with carcinoma of the esophagus ■ Tylosis–esophageal carcinoma ■ Tylosis type A

This autosomal dominant disorder, which has been reported in several families over many generations, is caused by missense mutations in the rhomboid 5 homolog 2 gene (RHBDF2) encoding an intramembrane protease135. Functional data suggest that mutant RHBDF2 increases signaling through the epidermal growth factor receptor (EGFR), which promotes epithelial hyperproliferation and dysregulation of wound repair135. Affected individuals develop focal PPK by 5–15 years of age, often limited to the pressure areas of the balls of the feet, with milder involvement of the palms (Fig. 58.13). Keratosis pilaris, dry rough skin, and oral leukokeratosis are often present. Affected individuals have an extremely high risk of esophageal carcinoma, which developed during the fifth decade of life in ~40% of affected members of the originally reported family136.

Carvajal Syndrome Synonyms:  ■ Carvajal-Huerta syndrome ■ Striate PPK with woolly

A

hair and dilated cardiomyopathy

This condition, first described in families from Ecuador, is characterized by PPK of the areata and striate type together with woolly hair and cardiomyopathy (Fig. 58.14)137. It can be caused by either biallelic or heterozygous mutations in the desmoplakin gene (DSP), a major constituent of desmosomes and critical to providing strength to the epidermis and cardiac tissue138,139. The mutations typically affect the protein’s carboxy-terminal tail, which binds to intermediate filaments and is important in cardiac myocytes. The PPK usually develops during infancy, and the woolly hair is generally present at birth. Additional skin findings may include scaly plaques and keratoses on the elbows and knees or in flexural sites. Although the cardiac ventricular involvement was predominantly leftsided in the original kindred, the right or both ventricles can be affected. The onset of cardiac disease ranges from early childhood to adolescence, and it typically leads to heart failure with cardiac enlargement138. Patients with an autosomal dominant form of Carvajal syndrome may

B

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also have leukonychia and oligodontia, and a variant autosomal recessive form features skin fragility with acantholysis, nail dystrophy, and dental enamel defects. Histologic findings include widening of the intercellular spaces and partial dehiscence of suprabasal keratinocytes, which have dense eosinophilic cytoplasm surrounding a pyknotic nucleus. Immunohistochemistry demonstrates perinuclear localization of keratin in these keratinocytes, suggesting a collapsed intermediate filament network. Early cardiac diagnosis and intervention is essential for survival of affected individuals139. The differential diagnosis of the triad of PPK, woolly hair, and cardiomyopathy includes Naxos disease, which more often presents with a diffuse PPK (see above), and desmocollin 2 defects. Other phenotypes due to genetic defects in desmoplakin include: isolated striate PPK or cardiac anomalies; suprabasal forms of EBS, including skin fragility– woolly hair syndrome and acantholytic EBS (see Ch. 32); erythrokeratodermia–cardiomyopathy syndrome (see Ch. 57); and SAM syndrome (see Striate PPK above)140–142.

PUNCTATE PALMOPLANTAR KERATODERMA WITHOUT ASSOCIATED FEATURES (ISOLATED, NON-SYNDROMIC)

Fig. 58.15 Punctate keratoses of the palmar creases. Keratotic papules lined along a crease in an African American.  

Punctate Palmoplantar Keratoderma, Buschke– Fischer–Brauer type Synonyms:  ■ Punctate palmoplantar keratoderma type 1

Hereditary disorders



Basal cell nevus syndrome Basaloid follicular hamartoma syndrome Darier disease Reticulate acropigmentation of Kitamura Punctate PPK (including punctate keratoses of the palmar creases)* Cowden syndrome* Porokeratotic adnexal ostial nevus (PAON; encompasses porokeratotic eccrine ostial and dermal duct nevus [PEODDN])*

Palmoplantar keratoderma punctata type 1 ■ Keratosis punctata palmoplantaris type Buschke–Fischer–Brauer ■ Keratoma dissipatum ■ Disseminated clavus

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DIFFERENTIAL DIAGNOSIS OF PALMOPLANTAR PITS

Punctate PPK is an autosomal dominant condition that can be caused by heterozygous mutations in AAGAB, which encodes the α- and γadaptin-binding protein p34. This protein is involved in the intracellular trafficking of clathrin-coated vesicles143. Accordingly, a large number of small vesicles and a dilated Golgi apparatus can be visualized via electron microscopy of affected skin. The AAGAB defect results in impaired endocytic recycling of receptor tyrosine kinases such as EGFR and Axl, leading to increased signaling and cellular proliferation143. A second locus for punctate PPK on 8q was found to be associated with a heterozygous missense mutation in the collagen type XIV α1 chain gene (COL14A1) in a Chinese family144. Multiple small keratotic papules usually begin to appear on the palmoplantar surfaces during adolescence or early adulthood, although onset can be in childhood or as late as the sixth decade of life145. The central keratotic core is initially translucent but may become opaque or verrucous over time, and a depression remains upon its removal (see Fig. 58.3). The papules can be painful or tender, and they may enlarge and aggregate to form plaques over pressure points. Enviromental factors can affect the degree of hyperkeratosis. Although some older studies suggested a possible association between punctate PPK and the development of breast and colon carcinomas, it is not clear whether there is truly an excess of malignancies in affected individuals143,146. Histopathologically, there is a slight epidermal depression with an overlying column of compact orthohyperkeratosis. Focal hypogranulosis with parakeratosis and elongated, curved rete ridges may be evident. Cytologic features of HPV infection are lacking. Punctate keratoses frequently develop in the palmar creases of adults with African ancestry (Fig. 58.15); the creases of the digits and soles may also be involved, and the lesions are worsened by mechanical stress. The relationship of this variant to other forms of punctate PPK remains to be determined147. The differential diagnosis of punctate PPK often includes verrucae, which are distinguished by multiple bleeding points upon paring, and punctate porokeratoses, which demonstrate a cornoid lamella rather than a column of orthohyperkeratosis histologically. Keratotic papules on palms and soles can also occur after exposure to arsenic or dioxin and in patients with Darier disease and Cowden syndrome. Conditions that present with palmoplantar pits, which may be confused with punctate PPK, are listed in Table 58.7.

Acquired disorders Pitted keratolysis Associated with Dupuytren contracture Punctate porokeratoses*

*Characterized primarily by keratoses, which may leave a pit upon removal of the keratotic plug.

Table 58.7 Differential diagnosis of palmoplantar pits. They are rarely seen in alkaptonuria, epidermodysplasia verruciformis, Blau syndrome, and lesions of lichen nitidus, lichen planus or psoriasis. Occasionally, lesions of circumscribed palmar or plantar hypokeratosis can be multiple and 45 years of age was first described by Haxthausen in 1934157. It is often associated with obesity, cold dry climates, and wearing backless shoes (e.g. sandals). Hyperkeratosis begins over pressure points on the heels, and the formation of fissures makes walking painful. If present, involvement of the hands is much milder. Endocrine dysfunction, vitamin A deficiency, contact dermatitis, and fungal infection were excluded in reported patients158. Treatment with a low-dose oral retinoid, topical estradiol 0.05% ointment, or keratolytic preparations containing 25–40% urea may be helpful159. Similar changes described in young women following bilateral oophorectomy responded to estrogen replacement therapy160.

Keratoderma and Cancer Acquired diffuse PPK has been observed in association with bronchial carcinoma161, and filiform PPK has been reported in patients with

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cancer of the breast, colon, and kidney162. “Tripe palms” refers to velvety, thickened palmar skin with exaggerated ridges. It is often associated with acanthosis nigricans and may herald malignancies of the lung, stomach, or genitourinary tract163. Bazex syndrome (acrokeratosis paraneoplastica) is discussed in Chapter 53. Esophageal carcinoma in association with focal PPK (Howel–Evans syndrome) as well as the increased risk of acral SCC in patients with Huriez syndrome and PPK with sex reversal are discussed above. Acral melanoma and the epithelioma cuniculatum variant of SCC have also been reported in individuals with mutilating forms of PPK, and an autosomal recessive syndrome featuring pigmentation defects, PPK, and cutaneous SCC can result from mutations in SASH1 (SAM and SH3 domain-containing 1; see Table 67.10). Mycosis fungoides represents another diagnostic consideration in patients with acquired PPK164. Arsenical keratoses present as small, corn-like areas of hyperkeratosis on the palms and soles (see Fig. 88.8). Over time, the lesions enlarge, thicken, and increase in number, spreading to the dorsal surfaces of the hands and feet. Ulceration often occurs when SCC develops. On histologic examination, epidermal changes vary from benign hyperplasia to moderate atypia or frank SCC. The latent period between ingestion of inorganic arsenic and onset of keratoses is 10 to 30 years or longer165. Visceral malignancies, particularly of the lung and genitourinary tract, usually develop after the onset of skin tumors.

Fig. 58.18 Aquagenic keratoderma. White “pebbly” changes on the palm following immersion in water. Courtesy, Julie V Schaffer, MD.  

Other Etiologies of Acquired Keratoderma Diffuse or focal palmoplantar hyperkeratosis can develop in association with hypothyroidism, often in the setting of myxedema. The PPK improves or resolves with thyroid replacement therapy166. With the increasing use of targeted therapies for the treatment of malignancies, in particular tyrosine kinase inhibitors, drug-induced palmoplantar hyperkeratosis also needs to be considered (see Table 21.16). Other conditions that have been associated with keratoderma are listed in Table 58.1167–169.

Aquagenic Palmoplantar Keratoderma Synonyms:  ■ Transient reactive papulotranslucent acrokeratoderma Aquagenic syringeal acrokeratoderma ■ Acquired aquagenic palmoplantar keratoderma ■ Aquagenic wrinkling of the palms and soles ■ Transient aquagenic keratoderma ■

Patients with aquagenic PPK develop thickening and white to translucent, “pebbly” changes on their palms shortly after immersion in water (e.g. within 3 minutes) (Fig. 58.18). Often, there is associated edema and burning pain170,171. Plantar involvement is less frequently observed. These findings disappear shortly after drying the hands. Onset is typically during the second decade of life, with a predilection for girls and women. By dermoscopy, the papular lesions are at sites of dilated acrosyringeal ostia172. Histologically, normal skin or dilated eccrine ostia and a mildly hyperkeratotic stratum corneum may be seen. Autosomal recessive or dominant inheritance of aquagenic PPK has been described, and an onset associated with the use of cyclooxygenase-2 inhibitors was reported173. Aquagenic wrinkling of the palms can be observed in ~50% of patients with cystic fibrosis and ~10–25% of heterozygous carriers of CFTR mutations174,175. Aquagenic PPK should be differentiated from hereditary papulotranslucent acrokeratoderma, in which lesions are persistent once they appear176, and other forms of PPK that are accentuated upon exposure to water, e.g. the Bothnia type of diffuse NEPPK (see above). Improvement can result from botulinum toxin injections or application of 20% aluminium chloride hexahydrate followed by urea cream177.

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Fig. 58.19 Circumscribed palmar hypokeratosis. A sharp drop-off is seen between the lesional epidermis, which has a very thin stratum corneum, and the surrounding skin. Clinically, a well-circumscribed pink depression is seen (see inset). Courtesy, Luis Requena, MD.  

Circumscribed Palmar or Plantar Hypokeratosis This entity, which was first described in 2002, presents as a wellcircumscribed, mildly erythematous, circular depression on the thenar or hypothenar region of the palm or less often the medial sole (Fig. 58.19). Lesions are solitary, or rarely few in number, and have a maximum diameter of 3 cm. They typically develop in women 40–85 years of age178, although congenital lesions have been described. Sometimes there is a history of prior trauma or a burn at the site. The clinical differential diagnosis may include Bowen disease or porokeratosis. Histologically, abrupt thinning of the stratum corneum over a diminished granular layer forms a sharp drop-off between normal and involved skin (see Fig. 58.19). To date, malignant transformation has not been reported. The etiology remains unknown, with postulated roles for trauma and loss of the keratinocytes’ ability to undergo palmoplantar differentiation. The latter is supported by the observation of diminished keratin 9 expression179. Molecular studies have failed to detect human papillomavirus (HPV) apart from a single report of HPV type 4 DNA180. Treatment with topical calcipotriene or 5-fluorouracil, cryotherapy, photodynamic therapy, and excision have been described. For additional online figures visit www.expertconsult.com

CHAPTER

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156. Eytan O, Morice-Picard F, Sarig O, et al. Cole disease results from mutations in ENPP1. Am J Hum Genet 2013;93:752–7. 157. Haxthausen H. Keratoderma climactericum. Br J Dermatol 1934;46:161–7. 158. Deschamps P, Leroy D, Pedailles S, et al. Keratoderma climactericum (Haxthausen’s disease): clinical signs, laboratory findings and etretinate treatment in 10 patients. Dermatologica 1986;172:258–62. 159. Zultak M, Bedeaux C, Blanc D. Keratoderma climacterium treatment with topical estrogen. Dermatologica 1988;176:151–2. 160. Wachtel TJ. Plantar and palmar hyperkeratosis in young castrated women. Int J Dermatol 1981;20:270–1. 161. Khanna SK, Agnone FA, Leibowitz AI, et al. Nonfamilial diffuse palmoplantar keratoderma associated with bronchial carcinoma. J Am Acad Dermatol 1993;28:295–7. 162. Hillion B, Le Bozec P, Moulonguet-Michaut I, et al. Hyperkeratose palmo-plantaire filiforme et cancer du sein. Ann Dermatol Venereol 1990;117:834–6. 163. Mullans EA, Cohen PR. Tripe palms: a cutaneous paraneoplastic syndrome. South Med J 1996;89:626–7. 164. Kim J, Foster R, Lam M, et al. Mycosis fungoides: an important differential diagnosis for acquired palmoplantar keratoderma. Australas J Dermatol 2015;56:49–51. 165. Wong SS, Kong CT, Chee LG. Cutaneous manifestations of chronic arsenicism: review of seventeen cases. J Am Acad Dermatol 1998;38:179–85. 166. Bouras M, Hali F, Khadir K, et al. Palmoplantar keratoderma: a rare manifestation of myxoedema. Ann Dermatol Venereol 2014;141:39–42. 167. Duvic M, Reisman M, Finley V, et al. Glucan-induced keratoderma in acquired immunodeficiency syndrome. Arch Dermatol 1987;123:751–6. 168. Geusau A, Jurecka W, Nahavandi H, et al. Punctate keratoderma-like lesions on the palms and soles in a patient with chloracne: a new clinical manifestation of dioxin intoxication? Br J Dermatol 2000;143:1067–71.

169. Do JE, Kim YC. Capecitabine-induced diffuse palmoplantar keratoderma: is it a sequential event of hand–foot syndrome? Clin Exp Dermatol 2007;32:519–21. 170. English JC, McCollough ML. Transient reactive papulotranslucent acrokeratoderma. J Am Acad Dermatol 1996;34:686–7. 171. Yan AC, Aasi SZ, Alms WJ, et al. Aquagenic palmoplantar keratoderma. J Am Acad Dermatol 2001;44:696–9. 172. Sezer E, Erkek E, Duman D, et al. Dermatoscopy as an adjunctive diagnostic tool in aquagenic syringeal acrokeratoderma. Dermatology 2012;225:97–9. 173. Carder KR, Weston WL. Rofecoxib-induced instant aquagenic wrinkling of the palms. Pediatr Dermatol 2002;19:353–5. 174. Berk DR, Ciliberto HM, Sweet SC, et al. Aquagenic wrinkling of the palms in cystic fibrosis: comparison with controls and genotype-phenotype correlations. Arch Dermatol 2009;145:1296–9. 175. Grasemann H, Ratjen F, Solomon M. Aquagenic wrinkling of the palms in a patient with cystic fibrosis. N Engl J Med 2013;369:2362–3. 176. Sracic JK, Krishnan RS, Nunez-Gussman JK, et al. Hereditary papulotranslucent acrokeratoderma: a case report and literature review. Dermatol Online J 2005;11:17. 177. Diba VC, Cormack GC, Burrows NP. Botulinum toxin is helpful in aquagenic palmoplantar keratoderma. Br J Dermatol 2005;152:394–5. 178. Pérez A, Rütten A, Gold R, et al. Circumscribed palmar or plantar hypokeratosis: a distinctive epidermal malformation of the palms or soles. J Am Acad Dermatol 2002;47:21–7. 179. Resnik KS, DiLeonardo M. Circumscribed palmar hypokeratosis: new observations. Am J Dermatopathol 2006;28:112–16. 180. Böer A, Falk TM. Circumscribed palmar hypokeratosis induced by papilloma virus type 4. J Am Acad Dermatol 2006;54:908–9.

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144. Guo BR, Zhang X, Chen G, et al. Exome sequencing identifies a COL14A1 mutation in a large Chinese pedigree with punctate palmoplantar keratoderma. J Med Genet 2012;49:563–8. 145. Emmert S, Kuster W, Hennies HC, et al. 47 patients in 14 families with the rare genodermatosis keratosis punctata palmoplantaris Buschke-Fischer-Brauer. Eur J Dermatol 2003;13:16–20. 146. Stevens HP, Kelsall DP, Leigh IM, et al. Punctate palmoplantar keratoderma and malignancy in a four generation family. Br J Dermatol 1996;134:720–6. 147. Bourrat E, Cabotin PP, Baccard M, et al. Palmoplantar keratodermas in black patients (Fitzpatrick skin phototype 5-6) of African descent: a multicenter comparative and descriptive series. Br J Dermatol 2011;165:219–21. 148. Postel-Vinay S, Ashworth A. AXL and acquired resistance to EGFR inhibitors. Nat Genet 2012;44:835–6. 149. Grillo E, Pérez-García B, González-García C, et al. Spiky keratotic projections on the palms and fingers. Spiny keratoderma. Dermatol Online J 2012;18:8. 150. Chambers CJ, Konia T, Burrall B, et al. Unilateral prickly palmar papules. Punctate porokeratotic keratoderma (PPK). Arch Dermatol 2011;147:609–14. 151. Caccetta TP, Dessauvagie B, McCallum D, et al. Multiple minute digitate hyperkeratosis: a proposed algorithm for the digitate keratoses. J Am Acad Dermatol 2012;67:e49–55. 152. Rongioletti F, Betti R, Crosti C, et al. Marginal papular acrokeratodermas: a unified nosography for focal acral hyperkeratosis, acrokeratoelastoidosis and related disorders. Dermatology 1994;188:28–31. 153. Jacyk WK, Smith A. Mosaic acral keratosis. Clin Exp Dermatol 1990;15:361–2. 154. Mengesha YM, Kayal JD, Swerlick RA. Keratoelastoidosis marginalis. J Cutan Med Surg 2002;6:23–5. 155. Cole LA. Hypopigmentation with punctate keratosis of the palms and soles. Arch Dermatol 1976;112:998–1000.

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eFig. 58.1 Diffuse palmoplantar keratoderma. Hyperkeratosis of the entire palmar surface.

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eFig. 58.2 Focal palmoplantar keratoderma. A, B Striate type on the palm. C Areata type on the soles; this patient has an incidental digital anomaly.  

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eFig. 58.4 Diffuse epidermolytic palmoplantar keratoderma. A Diffuse hyperkeratosis on the soles. B Erythema is present at the border on the flexor wrist as well as in areas where there is reduced hyperkeratosis.

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Courtesy, Alfons Krol, MD, and Dawn Siegel, MD.

A

A

B

B

eFig. 58.3 Punctate palmoplantar keratoderma. A Lesions can coalesce over pressure points on the sole. B Close-up view of coalescing small keratotic papules on the palm.  

eFig. 58.5 KLICK syndrome. Diffuse keratoderma and hyperkeratotic papules in parallel lines around the wrist.  

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eFig. 58.6 Huriez syndrome. A Mild palmar hyperkeratosis.   B Hypoplastic nail changes and scleroatrophic skin.

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Palmoplantar Keratodermas



A

B

B

eFig. 58.7 Pachyonychia congenita. A Hypertrophic nail dystrophy with wedge-shaped subungual hyperkeratosis. B Focal hyperkeratosis over pressure points on the sole. C Characteristic histologic finding of pale keratinocytes with eosinophilic inclusions.  

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eFig. 58.9 Marginal papular keratoderma. Multiple skin-colored papules at the margin of the palmar skin.  

eFig. 58.8 Richner–Hanhart syndrome (tyrosinemia II). Dendritic keratitis detected by slit-lamp examination. Courtesy, Jean L Bolognia, MD.  

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Darier Disease and Hailey–Hailey Disease Daniel Hohl

Chapter Contents Darier disease . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 944 Hailey–Hailey disease . . . . . . . . . . . . . . . . . . . . . . . . . . . . 950

DARIER DISEASE Synonyms:  ■ Darier–White disease ■ Keratosis follicularis

Pathogenesis



Mutations in the ATP2A2 gene which encodes an endoplasmic reticulum (ER) Ca2+ ATPase pump, SERCA2, leads to both acantholysis and apoptosis, accounting for the characteristic histologic finding of acantholytic dyskeratosis. SERCA2 haploinsufficiency has been hypothesized to underlie the condition’s dominant inheritance pattern8, but a more recent study found that aggregates of mutant SERCA2 may exert a dominant negative effect by inducing ER stress and keratinocyte apoptosis9. Although both SERCA2a and SERCA2b isoforms are found within the epidermis, SERCA2b is the major protein product and its dysfunction alone can produce Darier disease10. While SERCA2 is ubiquitously expressed, a lack of compensatory SERCA3 expression in keratinocytes may explain the particular vulnerability of these cells to SERCA2 deficiency. More than 240 pathogenic ATP2A2 mutations have been identified, primarily missense and frameshift alterations. In general, there is no clear genotype–phenotype correlation11. Possible exceptions include particular ATP2A2 mutations associated with acrokeratosis verruciformis of Hopf12 and the acral hemorrhagic subtype of Darier disease13,14. Several pathogenic mechanisms have been proposed for the acantholytic dyskeratosis of Darier disease. ATP2A2 mutations result in chronically low Ca2+ stores within the ER (Fig. 59.1)15, which is aggravated by cellular stress. This Ca2+ depletion leads to acantholysis via impaired processing, folding and trafficking of junctional proteins such as desmoplakin16 and E-cadherin17. Impaired membrane translocation of protein kinase C α, an important Ca2+-dependent regulatory enzyme that interacts with membrane phospholipids, is thought to mediate the disruption of desmosome assembly18. Recent studies have also shown that SERCA2 inhibition in keratinocytes causes increased levels of sphingosine, which inhibits protein kinase C α17,19. ER stress due to depleted Ca2+ stores and accumulation of unfolded proteins produces the “unfolded protein response”, which can induce apoptosis19,20. ATP receptors, which are thought to have roles in apoptosis and calcium signaling, were reported to localize abnormally in lesional Darier disease epidermis, with decreased P2Y2 (a G proteincoupled receptor) but increased P2X7 (a death receptor) in the plasma membrane of acantholytic cells21.

Dyskeratosis follicularis

Key features ■ Autosomal dominant disorder in which mutations in the ATP2A2 gene result in dysfunction of an endoplasmic reticulum Ca2+ ATPase (SERCA2), thus interfering with intracellular Ca2+ signaling ■ Keratotic and crusted papules and plaques favor seborrheic areas; additional features include palmoplantar papules, variable nail changes, and whitish oral mucosal papules ■ Clinical subtypes include an acral hemorrhagic variant and segmental forms due to type 1 and type 2 mosaicism ■ Characterized histologically by acantholytic dyskeratosis with suprabasilar clefting, “corps ronds” and “grains”

Introduction Darier disease is an autosomal dominant genodermatosis with characteristic mucocutaneous findings such as keratotic papules on the upper trunk and longitudinal erythronychia. Insufficient function of the 2b isoform of the sarco/endoplasmic reticulum Ca2+ ATPase (SERCA2b) leads to abnormal intracellular Ca2+ signaling, notably involving the endoplasmic reticulum. The result is a loss of suprabasilar cell adhesion (acantholysis) and an induction of apoptosis (dyskeratosis).

History In 1889, the French dermatologist Jean Darier1, at the Hôpital SaintLouis in Paris, and James C White2, Professor of Dermatology at Harvard University, independently reported a skin disease characterized by brown, crusted, malodorous lesions with a follicular distribution. Darier called the disease “psorospermose folliculaire végétante” because of his histopathologic studies, where throughout the malpighian layer he saw a large number of round bodies surrounded by a double-layered membrane. He and others thought that these bodies represented psorosperms, a type of parasitic protozoa now referred to as coccidia, which they postulated were the causative agents for the disease. However, attempts to culture or inoculate the supposed parasites failed, and the histologic changes were subsequently recognized as sequelae of abnormal keratinization3. The supposed follicular origin of the disease could not be confirmed either, as lesions were noted to occur outside the pilosebaceous unit4. It was White who first suggested the hereditary character of the disorder, when the daughter of his initially described patient developed similar skin lesions5.

Epidemiology 944

per million per 10 years6. Men and women are equally affected. Darier disease has an autosomal dominant mode of inheritance with complete penetrance and variable expressivity. For example, in a series of 42 patients with Darier disease, 7 of 18 affected individuals who recalled no family history were found to be members of known Darier kindreds with mildly affected parents7. The clinical severity varies among different families carrying identical mutations and among members of the same family. Indeed, subtle changes of the skin or nails may remain unnoticed by affected persons.

The prevalence of Darier disease has ranged from 1 in 100 000 in Denmark to 1 in 30 000 in Scotland, and the estimated incidence is 4

Clinical Features Onset and clinical pattern In approximately 70% of patients, the disease begins between the ages of 6 and 20 years, with a peak onset during puberty (ages 11–15 years)22. The primary lesions are keratotic, sometimes crusted, red to brown papules, which develop preferentially in a “seborrheic” distribution involving the trunk (Fig. 59.2), scalp (especially its margins; Fig. 59.3), face, and lateral aspects of the neck (Fig. 59.4). Despite its initial description as follicular dyskeratosis, the papules are not limited to a perifollicular location. The lesions tend to become confluent and may form papillomatous masses (Fig. 59.2B,D). Small (2–3 mm) hypomelanotic macules may be admixed with the keratotic papules and

Darier disease and Hailey–Hailey disease are autosomal dominant genodermatoses caused by mutations in genes encoding Ca2+ ATPase pumps in the endoplasmic reticulum (SERCA2) and Golgi apparatus (hSPCA1), respectively. As a consequence, abnormal intracellular Ca2+ signaling leads to impaired processing of junctional proteins, resulting in acantholysis due to disrupted epidermal adhesion in both disorders and dyskeratosis due to increased apoptosis in Darier disease. Onset of clinical manifestations is often in the second decade of life or later. Darier disease presents with keratotic papules in a seborrheic and acral distribution, whereas Hailey–Hailey disease features blistering and erosions in intertriginous sites. Both disorders are frequently complicated by secondary infections that produce malodor and promote vegetating plaques. Treatment is primarily directed against hyperkeratosis, inflammation, infection and sweating.

Darier disease, Hailey–Hailey disease, acrokeratosis verruciformis of Hopf, acantholysis, dyskeratosis

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ABSTRACT

non-print metadata KEYWORDS:

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CELLULAR SITES OF CALCIUM PUMPS SERCA2 AND hSPCA1 Hormone

PIP2

DAG

Ca2+ Cell membrane

Receptor

IP3

Na+ Ca2+ hSPCA1 (ATP2C1)

PMCA1-4 (ATP2B1-4)

PLC

G protein

PKC

Ca2+

Ca2+ SERCA1-3 (ATP2A1-3)

Mitogenic signal

Ca2+

Ca2+ channel responsive to IP3

Ca2+

Endoplasmic reticulum

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Fig. 59.1 Cellular sites of calcium pumps SERCA2 and hSPCA1. Darier disease is due to mutations in ATP2A2 which encodes SERCA2. PIP2, phosphoinositol diphosphate; IP3, inositol triphosphate; PLC, phospholipase C; DAG, diacylglycerol; PKC, protein kinase C.

Golgi apparatus Hailey–Hailey disease Darier disease Calcium pump

A

Nucleus

C

Fig. 59.2 Darier disease. Truncal involvement with a predilection for seborrheic areas. Keratotic papules can vary from red (A, B) to brown (C, D) in color and may become confluent. A &  

C, Courtesy, Julie V Schaffer, MD.

B D

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Fig. 59.3 Darier disease. A Crusted papules at the hairline on the face and in the posterior auricular area. B Extensive facial involvement leading to ectropion.

Genodermatoses



of involvement, followed by the gingiva, buccal mucosa, and tongue (Fig. 59.10)22.

Symptoms Most patients complain of moderate itching. Equally distressing are the appearance and the odor, which can lead to social isolation.

Modifying factors This condition frequently worsens during the summer. In patients with Darier disease, characteristic lesions can be experimentally induced in clinically uninvolved skin by UV irradiation, and UVB irradiation has been shown to suppress ATP2A2 expression in keratinocytes26. Sweating, heat, and occlusion represent additional factors that trigger exacerbations primarily in covered and intertriginous areas (e.g. after a long airplane flight), and this predisposes patients to infections (see below). Lithium carbonate, which is commonly used to treat bipolar disorder27, can provoke flares of Darier disease.

Course of the disease Darier disease follows a chronic course with fluctuations in disease severity. While some patients report improvement over time, others experience a worsening22. A

B

Infectious complications Areas of skin affected by Darier disease are prone to secondary infections with bacteria, yeast, and dermatophytes22, often leading to malodor and vegetating plaques. A study of 75 adult patients found a high prevalence of Staphylococcus aureus colonization in lesional skin (~70%) and the nares (~50%), which correlated with a more severe phenotype28. Affected individuals are also susceptible to the development of widespread cutaneous infections with human papillomaviruses (HPV) and herpes simplex virus (HSV). When there is a sudden onset and rapid spread of vesicular and crusted lesions, often accompanied by fever and malaise, the clinician should have a high index of suspicion for the development of Kaposi varicelliform eruption (Fig. 59.11)24. The latter requires systemic antiviral therapy (e.g. acyclovir, valacyclovir). Generalized cowpox infection has also been reported. Disruption of the epidermal barrier likely plays an important role in the increased frequency and severity of skin infections in patients with Darier disease. Immunologic studies have shown no consistent systemic abnormalities29. However, a immunohistochemical analysis found evidence for an impaired local immune response, with a decrease in Langerhans cells and plasmacytoid dendritic cells30.

Salivary glands

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occasionally are the predominant feature (Fig. 59.5). Rarely, sterile vesicles or bullae are prominent, and, in these cases, herpetic infection (Kaposi varicelliform eruption) must be excluded23,24. Most patients have lesions in the axillae, groin, and/or inframammary area (Fig. 59.6). Although these intertriginous lesions are usually mild, they are occasionally the predominant finding and may result in the misdiagnosis of Hailey–Hailey disease (HHD)25. Occasionally, macerated, fungating masses are seen in the axillae or groin. Malodor is a frequent and distressing feature of Darier disease. In ~50% of patients, 2–4 mm, skin-colored or brownish, flat-topped papules, reminiscent of flat warts, are found on the dorsal aspects of the hands and feet, and less often, on the forearms and legs (Fig. 59.7). Rarely, acral hemorrhagic vesicles may also be seen. Palmoplantar papules, many of which are keratotic, and keratin-filled depressions are almost invariably present (Fig. 59.8). Subtle changes can be detected by obtaining finger or palm prints, which show interruption of the dermatoglyphic pattern. Nail changes include longitudinal red and/or white lines, longitudinal ridging and fissuring, and wedge-shaped subungual hyperkeratosis (Fig. 59.9). The nails are brittle and tend to break distally, forming V-shaped notches25. Painless whitish papules or rugose plaques are noted in 15–50% of patients with Darier disease. The hard palate is the most common site

In some patients, obstruction of salivary gland ducts can lead to painful glandular swelling. Darier-like histologic changes within the ducts are thought to be responsible for the obstruction31.

Neuropsychiatric disorders Various neuropsychiatric conditions such as epilepsy, intellectual impairment, and mood disorders have been reported in association with Darier disease, but the strength and nature of these relationships remain to be determined22,32. Neuropsychiatric assessment of 100 Darier disease patients from the UK revealed higher lifetime rates of major depression (30%), suicide attempts (13%), bipolar disorder (4%), and epilepsy (3%) than in the general population33. In a recent study based on the Swedish national registry, Darier disease patients (n=770) were more likely to be diagnosed with intellectual disability (6.2-fold), bipolar disorder (4.3-fold), and schizophrenia (2.3-fold) than matched individuals from the general population34,35. There are no known direct neuropsychiatric effects of ATP2A2 mutations13, although an accumulation of insoluble SERCA2 aggregates within neurons has been hypothesized9. It is also possible that there may be a closely linked susceptibility gene for bipolar disorder36. In addition, the disfigurement and isolation associated with severe skin diseases often contribute to psychiatric and social morbidity. Therefore, depression and increased suicidal ideation in patients with Darier disease may be explained, at least in part, by non-genetic factors25.

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A

B

Darier disease

C

Hailey–Hailey disease

Most common sites Acral papules Intertriginous lesions

Darier Disease and Hailey–Hailey Disease

DISTRIBUTION PATTERNS FOR DARIER, HAILEY–HAILEY AND GROVER DISEASE

Most common sites Less common

Grover disease Most common sites Less common

Fig. 59.4 Distribution patterns for Darier, Hailey–Hailey and Grover disease.  

Fig. 59.6 Darier disease. Severe involvement in intertriginous zones, including the abdominal fold and groin.  

Fig. 59.5 Darier disease. Observed most commonly in individuals with darkly pigmented skin, a guttate leukoderma may be seen in patients with Darier disease, including the segmental form. Courtesy, Julie V Schaffer, MD.  

Others Ocular complications, e.g. corneal ulcerations or staphylococcal endophthalmitis, occur very rarely. There have been a few reports of squamous cell carcinomas arising in cutaneous or mucosal sites chronically affected by Darier disease37. Malignant transformation is a rare event and may be related to infection with oncogenic types of HPV or changes in keratinocyte adhesion and proliferation secondary to SERCA2 haploinsufficiency, which has been associated with squamous cell carcinomas of the skin and upper gastrointestinal tract in mice. Observations of bone cysts, renal agenesis, and autoimmune thyroiditis in patients with Darier disease are thought to represent chance associations.

Clinical subtypes of Darier disease (Table 59.1) Acral hemorrhagic type

In addition to classic clinical features, a small subset of patients develop sharply demarcated, red to blue–black macules on the palms and soles

as well as the dorsal aspects of the hands22. These irregularly shaped lesions represent hemorrhage into acantholytic vesicles. A particular ATP2A2 missense mutation (N767S) has been identified in several non-related families with the acral hemorrhagic type of Darier disease13,14, as well as a few individuals with a classic Darier disease phenotype11.

Segmental types 1 and 2

Two types of segmental Darier disease have been described, both with a distribution of lesions along the lines of Blaschko (see Ch. 62). With the more common type 1 mosaicism (Fig. 59.12), the age of onset, severity, and histologic findings within the streaks are similar to those of generalized Darier disease. Type 1 segmental Darier disease results from a postzygotic mutation in the ATP2A2 gene during embryogenesis, which leads to a mosaic pattern of skin involvement. Heterozygous ATP2A2 mutations in affected, but not background, skin have been documented in patients with this form of segmental Darier disease38. If there are mutant cells in the gonads, a patient with type 1

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Fig. 59.7 Darier disease. Multiple flat-topped papules on the dorsal aspect of the hand.  

Fig. 59.9 Darier disease. Alternating longitudinal red and white streaks as well as notching of the free edge of the nail plate. Courtesy, Antonella Tosti, MD.  

A

Fig. 59.10 Oral mucosal Darier disease. Whitish papules on the palate.  

B

Fig. 59.8 Palmar involvement in Darier disease. A Both keratotic papules and keratin-filled depressions are seen. B Less commonly, a thick, spiked focal keratoderma is observed. A, Courtesy, Kalman Watsky, MD. B, Courtesy, Julie V Schaffer, MD.  

Fig. 59.11 Darier disease with superimposed HSV infection (Kaposi varicelliform eruption). Multiple hemorrhagic crusts of a similar size are seen.  

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segmental manifestations may have offspring with generalized Darier disease. Patients with type 2 mosaicism have generalized Darier disease plus linear streak(s) with increased severity39. Type 2 segmental manifestations of autosomal dominant disorders occur when patients with a heterozygous germline mutation also have a postzygotic inactivating

mutation in the other allele of the same gene (i.e. a “second hit” causing loss of heterozygosity), which leads to more severe manifestations in a mosaic distribution (see Fig. 62.2). Of note, a second hit in the ATP2A2 gene was identified in skin from erosive patches following the lines of Blaschko in a 1-year-old boy with a family history of Darier disease40.

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LESS COMMON PRESENTATIONS OF DARIER DISEASE

Darier Disease and Hailey–Hailey Disease

Morphologic variants Guttate hypopigmentation (see Fig. 59.5) > hyperpigmented flat-topped papules and macules (“freckle-like”)* • Vesiculobullous lesions • Acral hemorrhagic lesions • Keratoderma (spiked; see Fig. 59.8B) • “Cornifying” (e.g. with cutaneous horns) • Comedones†, facial cysts, acne conglobata • Periocular nodulocystic lesions • Alopecia, cutis verticis gyrata •

Distribution patterns Predominantly involving intertriginous areas, sun-exposed skin, the extremities, acral sites, or the scalp (pityriasis amiantacea-like) • Segmental (type 1 > 2) (see Fig. 59.12) •

Extracutaneous Oral mucosal erosions Corneal opacities or ulcers • Salivary gland obstruction • Laryngeal involvement • •

Fig. 59.13 Histopathology of Darier disease. Hyperkeratosis, grains and corp ronds (inset) are seen in addition to acantholysis leading to suprabasilar clefting. Courtesy, Lorenzo Cerroni, MD.  

*A persistent acantholytic dermatosis and extensive lentiginous “freckling” without an underlying ATP2A2 mutation has also been described.

†The differential diagnosis may include familial dyskeratotic comedones.

– small, oval cells in the stratum corneum characterized • “Grains” by an intensely eosinophilic cytoplasm composed of collapsed

Table 59.1 Less common presentations of Darier disease.

Fig. 59.12 Type 1 segmental Darier disease. Note the distribution of the papules along the lines of Blaschko.  

keratin bundles containing shrunken parakeratotic nuclear remnants. “Grains” are likely derived from “corps ronds”, but formal proof that they indeed represent different stages of the same pathologic process has not been provided. The epidermis overlying acantholytic and dyskeratotic foci is thickened and shows papillomatosis and hyperkeratosis. In the superficial dermis, there is a mild to moderate perivascular inflammatory infiltrate. Diagnostic histologic changes are often focal, necessitating a careful search. Similar histologic features may be observed in Grover disease, but in the latter there tends to be more acantholysis, less dyskeratosis, and fewer “corps ronds” or “grains”. The two conditions can be histologically indistinguishable, but the findings are typically more pronounced, widespread, and follicle-based in Darier disease.

Differential Diagnosis Acrokeratosis verruciformis of Hopf

Pathology There are two prominent histologic features in Darier disease, acantholysis and dyskeratosis (Fig. 59.13). Acantholysis is due to a disturbance in cell adhesion that leads to suprabasilar cleft formation. At the ultrastructural level, this corresponds to a loss of desmosomes and detachment of keratin filaments from the desmosomes41. Dyskeratosis is due to apoptosis of keratinocytes and is characterized by nuclear condensation and perinuclear keratin clumping. Two types of dyskeratotic cells are observed in Darier disease42: “Corps ronds” – acantholytic enlarged keratinocytes in the malpighian layer with darkly staining and partially fragmented nuclei surrounded by a clear cytoplasm and encircled by a bright ring of collapsed keratin bundles.



Flat-topped, wart-like papules on the dorsal aspects of the extremities are a common manifestation of Darier disease. They are clinically indistinguishable from the lesions that characterize the autosomal dominant disorder described by Hopf as “acrokeratosis verruciformis” (Fig. 59.14)43. There has been debate as to whether acrokeratosis verruciformis is a separate entity or an allelic forme fruste of Darier disease, and reports of an underlying ATP2A2 mutation in some, but not all, patients with acrokeratosis verruciformis suggest genetic heterogeneity12,44. Acrokeratosis verruciformis and Darier disease have traditionally been separated on the basis of their histologic features, with the former lacking acantholysis and dyskeratosis. However, serial sectioning is often required to find foci of acantholysis and dyskeratosis in acral skin biopsy specimens from patients with Darier disease45. Hopf actually described nail changes and palmoplantar keratotic papules in his initial report of acrokeratosis verruciformis43, and there have been subsequent observations of families where some members had only acrokeratosis verruciformis while others exhibited the classic skin findings of Darier disease46. Because patients with Darier disease often develop warty lesions on the extremities before keratotic papules appear in a seborrheic distribution, some individuals who present with acrokeratosis verruciformis may later be diagnosed as actually having Darier disease7. Particular ATP2A2 mutations (e.g. P602L, A698V) have been identified in patients with isolated acrokeratosis verruciformis as well as those with acral warty lesions followed by the onset of Darier disease after intense sun exposure12,47.

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liberal use of emollients49,53, and combination therapy with midpotency topical corticosteroids49,53. Improvement following treatment with topical calcineurin inhibitors has also been reported54. Intermittent use of topical antibiotics and antifungal agents is helpful in reducing malodor due to microbial colonization and mild secondary infections. Several case reports have suggested that topical 5-fluorouracil (1% or 5%) may be efficacious55. Benefit from topical application of diclofenac sodium 3% gel has also been described56, and cyclooxygenase-2 (COX-2) inhibition has been shown to rescue keratinocytes from UVB-induced downregulation of ATP2A2 expression57.

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Systemic therapy

Fig. 59.14 Acrokeratosis verruciformis of Hopf. Involvement of the dorsal aspect of the foot with flat-topped papules.  

Others Although the clinical differential diagnosis may include severe seborrheic dermatitis and Grover disease (transient acantholytic dermatosis; see Fig. 59.4 and Ch. 87), Darier disease is readily distinguished by involvement of acral skin, the nails and the oral mucosa. A family history may also be a clue to the diagnosis of Darier disease, and histologic findings differentiate it from seborrheic dermatitis. In Grover disease, the pruritic crusted papules are not confluent, and they typically develop after occlusion and/or sweating. However, in a persistent form of acantholytic dermatosis that affects patients with significant actinic damage, the papules are scalier and the histologic features closely resemble those of Darier disease48. In patients with predominantly flexural involvement, pemphigus vegetans (Hallopeau type), pemphigoid vegetans, blastomycosis-like pyoderma (pyoderma vegetans), and HHD may represent diagnostic considerations. Pemphigus vegetans usually develops at an older age and is characterized histologically by exocytosis of eosinophils as well as acantholysis; direct immunofluorescence (DIF) shows the intercellular pattern of the pemphigus group, and anti-desmoglein antibodies can be detected by ELISA. Pyoderma vegetans features a neutrophilic infiltrate, and acantholysis is not observed. HHD is sometimes difficult to separate clinically from primarily intertriginous Darier disease. The presence of palmoplantar papules, longitudinal erythronychia, distal notching of the nails, mucosal lesions, and prominent dyskeratosis as well as acantholysis histologically can serve as clues to the diagnosis of Darier disease. Occasionally, a sporadic disorder referred to as “papular acantholytic dyskeratosis” may be localized to the vulvocrural area.

Treatment General measures Therapies directed against hyperkeratosis, inflammation, and infection are employed as needed. Lightweight clothes and sun protection help prevent aggravation due to heat, sweating, and exposure to UV radiation. Daily skin care includes the use of antimicrobial cleansers to prevent malodorous bacterial colonization and keratolytic emollients to reduce scaling and irritation.

Topical therapy 950

Topical retinoids are more effective as monotherapy49,50 than topical vitamin D analogues51, which had no benefit in a small randomized controlled study52, or corticosteroids. However, retinoid-associated irritation is common and can be reduced by alternate-day application,

Isotretinoin, acitretin, and alitretinoin represent effective treatments for Darier disease, producing significant improvement in approximately 90% of patients25,58. However, the use of these agents is limited by their side effects, and relapse occurs after cessation of therapy. Thus, it is generally recommended that systemic retinoids be reserved for patients with severe disease unresponsive to topical treatment. Because of the teratogenic potential of systemic retinoids, contraception is mandatory for women of childbearing potential (see Ch. 126). Individual dose titration is important to optimize the benefit–risk balance and avoid excessive dose-related side effects, such as mucocutaneous dryness and elevation of serum lipids and liver enzymes. Intermittent therapy to prevent exacerbations during the summer months is a useful approach. In patients with predominantly bullous or intertriginous lesions, oral retinoids may aggravate the disease and are not recommended59. Oral contraceptives may mitigate symptoms in women with premenstrual exacerbations60. Cyclosporine also represents an option for patients with severe Darier disease who cannot tolerate or do not respond to oral retinoids61.

Surgical therapy Surgical therapy may be an effective alternative for focal recalcitrant lesions, particularly in the flexural and gluteal areas. Excision followed by split-thickness grafting, dermabrasion, or laser removal (CO2 or erbium:YAG) may yield a long-term remission62. Destructive treatment must include the follicular infundibulum in order to prevent recurrences. Experience is necessary to avoid scarring, particularly in body areas at risk for hypertrophic scar or keloid formation. From this standpoint, the erbium:YAG laser might have an advantage over the CO2 laser63. In small case series, improvement has been observed following pulsed dye laser and photodynamic therapy64.

HAILEY–HAILEY DISEASE Synonym:  ■ Familial benign chronic pemphigus

Key features ■ An uncommon autosomal dominant disorder in which mutations in the ATP2C1 gene result in dysfunction of a Golgi-associated Ca2+ ATPase, thus interfering with intracellular Ca2+ signaling ■ Clinically, flaccid blisters and erosions are seen in intertriginous areas, especially the axillae and groin; moist, malodorous vegetations and fissures can develop ■ Segmental variants (types 1 and 2 mosaicism) can occur ■ The major histologic finding is acantholysis throughout the spinous layer, sometimes referred to as a “dilapidated brick wall”

Introduction HHD is an autosomal dominant genodermatosis characterized by vesicular and erosive lesions that favor the intertriginous areas, especially the axillae and groin. Mutations in the ATP2C1 gene that encodes the Golgi-associated Ca2+ ATPase hSPCA1 lead to abnormal intracellular Ca2+ signaling, resulting primarily in a loss of cellular adhesion (acantholysis) in the stratum spinosum.

CHAPTER

History

59 Darier Disease and Hailey–Hailey Disease

In 1939, Howard and Hugh Hailey, brothers working in the Department of Dermatology at Emory University School of Medicine in Atlanta, Georgia, described a chronic dermatosis in two sets of brothers. The disorder was characterized by recurrent blisters and erosive, crusted lesions on the neck (in one pair of brothers) and in the axillae and groin (in the second pair)65. Histologic sections from all four patients showed similar features – intraepidermal vesicles, mild dyskeratosis, hyperkeratosis, and a moderate dermal lymphocytic infiltrate. Different dermatopathologists interpreted these findings variably as pemphigus, pemphigus-like, or Darier disease. The authors themselves rightly believed that they were dealing with a novel entity unrelated to Darier disease and coined the name “familial benign chronic pemphigus”. A disease called “pemphigus congénital familiale héréditaire” had been described 6 years prior to the report by the Hailey brothers. Therefore, some believe that HHD should also bear the name of the French dermatologists Gougerot and Allée. However, they did not perform a biopsy, and the early onset and initial localization on pressure points suggest that their patients may have actually suffered from epidermolysis bullosa simplex66. The subsequent controversy as to whether “familial benign chronic pemphigus” was a unique disease or a phenotypic variant of Darier disease was eventually solved by our understanding of the molecular genetics of both disorders.

Epidemiology There are no data regarding the exact prevalence of HHD. Based upon clinical experience, HHD is seen nearly as often as Darier disease. The mode of inheritance is autosomal dominant with complete penetrance, but the age of onset and expressivity varies markedly amongst affected family members67,68. Particular mutations may be associated with primarily genitoperineal involvement69 or milder phenotypes70.

Fig. 59.15 Hailey–Hailey disease. Erythematous, eroded plaque in the axilla. Note the intact flaccid vesicles at 2 and 7 o’clock.  

Pathogenesis HHD is caused by mutations in the ATP2C1 gene71, 72, which encodes a Ca2+ ATPase, hSPCA1, that is localized to the Golgi apparatus73,74 (see Fig. 59.1). hSPCA1 transports Ca2+ and Mn2+, and it sequesters Ca2+ within the Golgi lumen. HHD is likely caused by haploinsufficiency and most ATP2C1 mutations encode premature termination codons75,76. Acantholysis due to ATP2C1 mutations appears to be mediated via impaired Ca2+ sequestration, resulting in depletion of Ca2+ within the Golgi lumen73. Normal Golgi Ca2+ levels are required for proper protein processing77, and Golgi Ca2+ depletion in HHD keratinocytes impairs the processing and translocation of junctional proteins that function in cell–cell adhesion. Lesional skin from HHD patients shows decreased staining for extracellular desmosomal components78, and altered synthesis of tight junction proteins has been observed in hSPCA1-deficient keratinocytes79. Reduced ATP levels in HHD keratinocytes have also been associated with impaired actin reorganization, which may affect adherens junction formation80. Lastly, decreased calcium levels in basal keratinocytes of lesional HHD epidermis may be linked to abnormal localization of ATP receptors and aberrant expression of keratins 10 and 1421.

Clinical Features Onset and clinical pattern The initial lesions and associated symptoms usually develop during the second or third decade of life but may be delayed until the fourth or fifth decade67. HHD has a predilection for intertriginous sites, such as the axillae, groin, lateral aspects of the neck, and perianal region (Fig. 59.15; see Fig. 59.4). The scalp, antecubital and popliteal fossae, and trunk are less frequently involved81. Inframammary and vulvar lesions are common in women (Fig. 59.16), and female patients occasionally present with isolated vulvar disease82. The primary lesion is a flaccid vesicle on erythematous or normalappearing skin, which ruptures easily and therefore is often overlooked (see Fig. 59.15). The blisters give rise to macerated or crusted erosions (see Fig. 59.16), which tend to spread peripherally, producing a circinate border with crusts and small vesicles when examined carefully (Fig. 59.17). Development of chronic, moist, malodorous vegetations and painful fissures is common. Healing occurs without scarring, leaving postinflammatory hyperpigmentation.

Fig. 59.16 Hailey–Hailey disease. Chronic submammary lesion with erosions in a worm-eaten pattern.  

Longitudinal leukonychia of the fingernails may serve as a subtle diagnostic clue in patients with limited or atypical disease83. Involvement of the buccal, vaginal or conjunctival mucosae is rare84–86.

Symptoms Painful intertriginous erosions and crusting may interfere with activities of daily living. Fetid odor and pruritus add to the psychosocial distress experienced by HHD patients.

Modifying factors Given the abnormal cell–cell adhesion within the epidermis, friction can induce new lesions. Heat and sweating can also exacerbate HHD, and patients often note worsening during the summer months. UV irradiation does not appear to influence the course of the disease67. Although ATP2C1 mRNA expression in keratinocytes can be suppressed by UVB irradiation26, successful treatment of HHD with a combination of narrowband UVB phototherapy and an oral retinoid has been described87. Microbial colonization and secondary infections are important modifying factors, as discussed below. In particular,

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Fig. 59.17 Hailey–Hailey disease. Circinate plaques on the back with erosions and crusting in the active borders.

Genodermatoses



Courtesy, Louis A Fragola, Jr, MD.

Fig. 59.18 Histopathology of Hailey–Hailey disease. Focal crusting and acantholysis beginning in the suprabasilar area and extending throughout the epidermis. The latter has been likened to a “dilapidated brick wall”. Courtesy,  

Lorenzo Cerroni, MD.

staphylococcal infection potentiates acantholysis and may lead to severe and widespread blistering88.

Course of the disease Complete remissions as well as flares are common, and the clinical course in an individual patient is difficult to predict. Some patients report attenuation of the disease at an older age, whereas others experience no change or worsening with aging81. Life expectancy is not altered.

Complications Infections

As in Darier disease, colonization and secondary bacterial, fungal, and viral infections play an important role in disease exacerbation and persistence89,90. Vegetating lesions and malodor suggest bacterial and/ or fungal overgrowth. Topical and/or systemic antimicrobial agents may be required to induce a clinical remission. Recalcitrant intertriginous lesions have been described in association with HSV infections89. Direct fluorescent antibody assays, viral cultures, or PCR-based testing of infected keratinocytes can confirm this diagnosis; occasionally, a skin biopsy is required. Kaposi varicelliform eruption due to HSV is a rare complication of HHD91. It is characterized by fever and a rapidly spreading vesicular eruption, and should be promptly treated with an oral antiviral medication (e.g. acyclovir, valacyclovir).

Malignant transformation

There are a few case reports of cutaneous squamous cell carcinoma developing within chronic lesions of HHD in the anogenital region92. It is possible that impairment of the structural integrity of the epidermis may predispose patients to infection with oncogenic strains of HPV (see Ch. 79).

Clinical subtypes of Hailey–Hailey disease Segmental type 1

Segmental type 1 HHD is caused by a heterozygous postzygotic mutation in an otherwise normal embryo, resulting in a mosaic distribution of disease with age of onset and severity similar to the non-mosaic phenotype. Only a few cases of segmental type 1 involvement in HHD have been reported.

Segmental type 2

952

There are rare patients with generalized HHD who also have a segmental area of more pronounced involvement with earlier onset (analogous to type 2 segmental lesions described previously for Darier disease). This results from postzygotic inactivation of the normal ATP2C1 allele (loss of heterozygosity), which leads to more severe disease in a mosaic pattern93. Unlike HHD due to a heterozygous mutation, the affected segments display acantholysis within adnexal structures, which might

make it impossible to eradicate foci of blistering using superficial ablative methods (see below).

Pathology Whereas acantholysis in Darier disease occurs primarily within discrete foci, the loss of intercellular bridges in HHD is generally more widespread within the epidermis. Thus, larger areas of dyscohesion with single or groups of acantholytic cells are seen, which have been likened to a “dilapidated brick wall”. Dermal papillae, lined by a single layer of basal cells, protrude into the blister cavities and are referred to as “villi” (Fig. 59.18). In contrast to Darier disease, necrotic keratinocytes are uncommon, and only rare acantholytic dyskeratotic cells (e.g. “corps ronds”) may be observed. In more chronic lesions, epidermal hyperplasia, parakeratosis, and focal crusts are found. A moderate perivascular lymphocytic infiltrate is observed in the superficial dermis. Histologically, Grover disease may be indistinguishable from HHD, but these two entities are readily distinguished on the basis of clinical features. DIF is negative, thus excluding pemphigus vulgaris.

Differential Diagnosis The blisters in HHD are typically fragile and rupture easily. Therefore, clinical experience and a high index of suspicion may be necessary to diagnose HHD, especially in patients with limited disease. Lesions confined to the axillae or groin may be mistaken for intertrigo or candidiasis. Isolated perianal maceration is easily misdiagnosed as irritant dermatitis, and vulvar involvement may resemble lichen simplex chronicus82. Histologic examination of affected skin is often the key to the diagnosis. The lesions of inverse psoriasis have sharper borders, fewer erosions, and less crusting. A total skin examination, looking for additional sites of involvement and associated signs, e.g. nail pitting, will aid in the diagnosis. Vegetating intertriginous lesions in HHD may be identical to those of pemphigus vegetans (Hallopeau type) or pemphigoid vegetans, but the latter can be differentiated by positive DIF of perilesional skin. The cutaneous features of HHD and Darier disease may overlap. Older reports described patients with characteristic skin findings of both genodermatoses who therefore carried two diagnoses94, but genetic analysis can now establish a single diagnosis in such individuals. In general, the two disorders have different patterns of distribution that are fairly easily distinguished (see Fig. 59.4). Moreover, a predominantly vesicular eruption in patients with Darier disease is rare23. Additional features such as V-shaped notches in the distal free edge of the nail plate, longitudinal erythronychia, and oral papules point to the diagnosis of Darier disease.

CHAPTER

Surgical therapy

General measures

Surgical therapy should be considered for disease unresponsive to general measures and topical treatments. While wide excision followed by grafting has been reported to be successful101, this aggressive approach has been replaced by more superficial ablative techniques. The most well-documented method is dermabrasion102, but laser vaporization of the epidermis (scanned CO2 or erbium:YAG)63 and photodynamic therapy103 seem to be equally effective. Removal of the diseased epidermis plus its dermal niche of fibroblasts, which can extend to the level of the mid dermis, is recommended. Re-epithelialization from the spared adnexal structures normally occurs within 7–14 days.

There is no specific therapy for the acantholysis. Wearing lightweight clothes is recommended to avoid friction and sweating, and adhesive dressings should be avoided. Colonization and secondary bacterial, fungal, and viral infections are addressed via antimicrobial cleansers and appropriate topical and/or systemic antimicrobial agents, respectively.

Topical and intralesional therapy Topical corticosteroids often help to reduce inflammation and can be combined with topical antimicrobials and cleansers. Early application of corticosteroids may ameliorate developing lesions67. When the disease is refractory to topical preparations, injections of intralesional corticosteroids can be tried. In order to minimize the potential side effects of topical corticosteroids in intertriginous zones (e.g. atrophy, striae, telangiectasias), the lowest potency that is effective should be used and they should be applied intermittently. Both improvement and worsening following treatment with topical calcineurin inhibitors has been described95,96. In case reports, improvement has been observed with topical application of 5-fluorouracil97 and vitamin D analogues98. Of note, there are multiple reports of substantial improvement of HHD in the axillae, inframammary area, and groin after chemodenervation of sweat glands with botulinum toxin injections99,100. Application of zinc oxide paste in skin folds to protect against friction and moisture may also be helpful95.

Systemic therapy With the exception of antimicrobial agents for secondary infections, there is no strong evidence to support the use of any additional systemic therapies in HHD. A recent case series described improvement with long-term continuous or intermittent doxycycline administration in 6 patients with HHD104, but this treatment regimen may not be beneficial in all patients (author’s personal observations). Oral acitretin and isotretinoin have variable efficacy67, while successful results with alitretinoin have been reported in several patients105. There are anecdotal reports of severely affected individuals improving with the use of immunomodulatory drugs, e.g. prednisone, cyclosporine, methotrexate, dapsone, or afamelanotide106–108.

59 Darier Disease and Hailey–Hailey Disease

Treatment

Copyright notice Daniel Hohl retains copyright to his original photographs in Chapter 59.

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42. Douwes FR. On the histology and histochemistry of Darier’s disease. Arch Klin Exp Dermatol 1968;233:309–22. 43. Hopf G. Über eine bisher noch nicht beschriebene disseminierte Keratose (Acrokeratosis verruciformis). Dermatol Z 1931;60:227–50. 44. Wang PG, Gao M, Lin GS, et al. Genetic heterogeneity in acrokeratosis verruciformis of Hopf. Clin Exp Dermatol 2006;31:558–63. 45. Hafner O, Vakilzadeh F. Acrokeratosis verruciformis-like changes in Darier disease. Hautarzt 1997;48:572–6. 46. Herndon JH, Wilson JD. Acrokeratosis verruciformis (Hopf ) and Darier’s disease: genetic evidence for a unitary origin. Arch Dermatol 1966;93:305–10. 47. Berk DR, Taube JM, Bruckner AL, Lane AT. A sporadic patient with acrokeratosis verruciformis of Hopf and a novel ATP2A2 mutation. Br J Dermatol 2010;163:653–4. 48. Fawcett HA, Miller JA. Persistent acantholytic dermatosis related to actinic damage. Br J Dermatol 1983;109:349–54. 49. Burge SM, Buxton PK. Topical isotretinoin in Darier’s disease. Br J Dermatol 1995;133:924–8. 50. Abe M, Inoue C, Yokoyama Y, Ishikawa O. Successful treatment of Darier’s disease with adapalene gel. Pediatr Dermatol 2011;28:197–8. 51. Abe M, Yasuda M, Yokoyama Y, Ishikawa O. Successful treatment of combination therapy with tacalcitol lotion associated with sunscreen for localized Darier’s disease. J Dermatol 2010;37:718–21. 52. Kragballe K, Steijlen PM, Ibsen HH, et al. Efficacy, tolerability, and safety of calcipotriol ointment in disorders of keratinization. Results of a randomized, double-blind, vehicle-controlled, right/left comparative study. Arch Dermatol 1995;131:556–60. 53. Burkhart CG, Burkhart CN. Tazarotene gel for Darier’s disease. J Am Acad Dermatol 1998;38:1001–2. 54. Perez-Carmona L, Fleta-Asin B, Moreno-Garcia-DelReal C, Jaen-Olasolo P. Successful treatment of Darier’s disease with topical pimecrolimus. Eur J Dermatol 2011;21:301–2. 55. Schmidt H, Ochsendorf FR, Wolter M, et al. Topical 5-fluorouracil in Darier disease. Br J Dermatol 2008;158:1393–6. 56. Millan-Parrilla F, Rodrigo-Nicolas B, Moles-Poveda P, et al. Improvement of Darier disease with diclofenac sodium 3% gel. J Am Acad Dermatol 2014;70:e89–90. 57. Kamijo M, Nishiyama C, Takagi A, et al. Cyclooxygenase-2 inhibition restores ultraviolet B-induced downregulation of ATP2A2/SERCA2 in keratinocytes: possible therapeutic approach of cyclooxygenase-2 inhibition for treatment of Darier disease. Br J Dermatol 2012;166:1017–22. 58. Letule V, Herzinger T, Ruzicka T, Molin S. Treatment of Darier disease with oral alitretinoin. Clin Exp Dermatol 2013;38:523–5. 59. Bleiker T, Bourke J, Graham-Brown R, Hutchinson P. Etretinate may work where acitretin fails. Br J Dermatol 1997;136:368–70. 60. Oostenbrink JH, Cohen EB, Steijlen PM, van de Kerkhof PC. Oral contraceptives in the treatment of DarierWhite disease–a case report and review of the literature. Clin Exp Dermatol 1996;21:442–4. 61. Martini P, Peonia G, Benedetti A, Lorenzi S. DarierWhite syndrome and cyclosporin. Dermatology 1995;190:174–5. 62. McElroy JA, Mehregan DA, Roenigk RK. Carbon dioxide laser vaporization of recalcitrant symptomatic plaques of Hailey-Hailey disease and Darier’s disease. J Am Acad Dermatol 1990;23:893–7. 63. Beier C, Kaufmann R. Efficacy of erbium:YAG laser ablation in Darier disease and Hailey-Hailey disease. Arch Dermatol 1999;135:423–7. 64. Roos S, Karsai S, Ockenfel HM, Raulin C. Successful treatment of Darier disease with the flashlamppumped pulsed-dye laser. Arch Dermatol 2008;144:1073–5. 65. Hailey H, Hailey H. Familial benign chronic pemphigus. Arch Dermatol 1939;39:679–85.

66. Steffen C, Thomas D. Was Henri Gougerot the first to describe “Hailey-Hailey Disease. Am J Dermatopathol 2003;25:256–9. 67. Burge SM. Hailey-Hailey disease: the clinical features, response to treatment and prognosis. Br J Dermatol 1992;126:275–82. 68. Ikeda S, Shigihara T, Mayuzumi N, et al. Mutations of ATP2C1 in Japanese patients with Hailey-Hailey disease: intrafamilial and interfamilial phenotype variations and lack of correlation with mutation patterns. J Invest Dermatol 2001;117:1654–6. 69. Pernet C, Bessis D, Savignac M, et al. Genitoperineal papular acantholytic dyskeratosis is allelic to Hailey-Hailey disease. Br J Dermatol 2012;167:  210–12. 70. Matsuda M, Hamada T, Numata S, et al. Mutationdependent effects on mRNA and protein expressions in cultured keratinocytes of Hailey-Hailey disease. Exp Dermatol 2014;23:514–16. 71. Hu Z, Bonifas JM, Beech J, et al. Mutations in ATP2C1, encoding a calcium pump, cause Hailey-Hailey disease. Nat Genet 2000;24:61–5. 72. Sudbrak R, Brown J, Dobson-Stone C, et al. HaileyHailey disease is caused by mutations in ATP2C1 encoding a novel Ca(2+) pump. Hum Mol Genet 2000;9:1131–40. 73. Behne MJ, Tu CL, Aronchik I, et al. Human keratinocyte ATP2C1 localizes to the Golgi and controls Golgi Ca2+ stores. J Invest Dermatol 2003;121:688–94. 74. Vanoevelen J, Dode L, Van Baelen K, et al. The secretory pathway Ca2+/Mn2+-ATPase 2 is a Golgilocalized pump with high affinity for Ca2+ ions. J Biol Chem 2005;280:22800–8. 75. Fairclough RJ, Lonie L, Van Baelen K, et al. HaileyHailey disease: identification of novel mutations in ATP2C1 and effect of missense mutation A528P on protein expression levels. J Invest Dermatol 2004;123:67–71. 76. Shibata A, Sugiura K, Kimura U, et al. A novel ATP2C1 early truncation mutation suggests haploinsufficiency as a pathogenic mechanism in a patient with Hailey-Hailey disease. Acta Derm Venereol 2013;93:719–20. 77. Durr G, Strayle J, Plemper R, et al. The medial-Golgi ion pump Pmr1 supplies the yeast secretory pathway with Ca2+ and Mn2+ required for glycosylation, sorting, and endoplasmic reticulum-associated protein degradation. Mol Biol Cell 1998;9:1149–62. 78. Hakuno M, Shimizu H, Akiyama M, et al. Dissociation of intra- and extracellular domains of desmosomal cadherins and E-cadherin in Hailey-Hailey disease and Darier’s disease. Br J Dermatol 2000;142:702–11. 79. Raiko L, Siljamaki E, Mahoney MG, et al. Hailey-Hailey disease and tight junctions: Claudins 1 and 4 are regulated by ATP2C1 gene encoding Ca(2+) /Mn(2+) ATPase SPCA1 in cultured keratinocytes. Exp Dermatol 2012;21:586–91. 80. Aronchik I, Behne MJ, Leypoldt L, et al. Actin reorganization is abnormal and cellular ATP is decreased in Hailey-Hailey keratinocytes. J Invest Dermatol 2003;121:681–7. 81. Iijima S, Hamada T, Kanzaki M, et al. Sibling cases of Hailey-Hailey disease showing atypical clinical features and unique disease course. JAMA Dermatol 2014;150:97–9. 82. Wieselthier JS, Pincus SH. Hailey-Hailey disease of the vulva. Arch Dermatol 1993;129:1344–5. 83. Bel B, Jeudy G, Vabres P. Dermoscopy of longitudinal leukonychia in Hailey-Hailey disease. Arch Dermatol 2010;146:1204. 84. Fischer H, Nikolowski W. Die Mundschleimhaut beim Pemphigus benignus familiaris chronicus. Arch Klin Exp Dermatol 1962;214:261–73. 85. Vaclavinkova V, Neumann E. Vaginal involvement in familial benign chronic pemphigus (Morbus Hailey- Hailey). Acta Derm Venereol 1982;62:80–1. 86. Oguz O, Gokler G, Ocakoglu O, et al. Conjunctival involvement in familial chronic benign pemphigus (Hailey- Hailey disease). Int J Dermatol 1997;36:282–5.

87. Mizuno K, Hamada T, Hashimoto T, Okamoto H. Successful treatment with narrow-band UVB therapy for a case of generalized Hailey-Hailey disease with a novel splice-site mutation in ATP2C1 gene. Dermatol Ther 2014;27:233–5. 88. Chave TA, Milligan A. Acute generalized Hailey-Hailey disease. Clin Exp Dermatol 2002;27:290–2. 89. Zaim MT, Bickers DR. Herpes simplex associated with Hailey-Hailey disease. J Am Acad Dermatol 1987;17:701–2. 90. Mashiko M, Akiyama M, Tsuji-Abe Y, Shimizu H. Bacterial infection-induced generalized Hailey-Hailey disease successfully treated by etretinate. Clin Exp Dermatol 2006;31:57–9. 91. Stallmann D, Schmoeckel C. Hailey-Hailey disease with dissemination and eczema herpeticatum in therapy with etretinate. Hautarzt 1988;39:454–6. 92. Cockayne SE, Rassl DM, Thomas SE. Squamous cell carcinoma arising in Hailey-Hailey disease of the vulva. Br J Dermatol 2000;142:540–2. 93. Poblete-Gutierrez P, Wiederholt T, Konig A, et al. Allelic loss underlies type 2 segmental Hailey-Hailey disease, providing molecular confirmation of a novel genetic concept. J Clin Invest 2004;114:1467–74. 94. Nicolis G, Tosca A, Marouli O, Stratigos J. Keratosis follicularis and familial benign chronic pemphigus in the same patient. Dermatologica 1979;159:346–51. 95. Pagliarello C, Paradisi A, Dianzani C, et al. Topical tacrolimus and 50% zinc oxide paste for Hailey-Hailey disease: less is more. Acta Derm Venereol 2012;92:437–8. 96. Laffitte E, Panizzon RG. Is topical tacrolimus really an effective therapy for Hailey-Hailey disease? Arch Dermatol 2004;140:1282. 97. Dammak A, Camus M, Anyfantakis V, Guillet G. Successful treatment of Hailey-Hailey disease with topical 5-fluorouracil. Br J Dermatol 2009;161:967–8. 98. Aoki T, Hashimoto H, Koseki S, et al. 1alpha,24dihydroxyvitamin D3 (tacalcitol) is effective against Hailey-Hailey disease both in vivo and in vitro. Br J Dermatol 1998;139:897–901. 99. Lapiere JC, Hirsh A, Gordon KB, et al. Botulinum toxin type A for the treatment of axillary Hailey-Hailey disease. Dermatol Surg 2000;26:371–4. 100. Koeyers WJ, Van Der Geer S, Krekels G. Botulinum toxin type A as an adjuvant treatment modality for extensive Hailey-Hailey disease. J Dermatolog Treat 2008;19:251–4. 101. Menz P, Jackson IT, Connolly S. Surgical control of Hailey-Hailey disease. Br J Plast Surg 1987;40:557–61. 102. Hamm H, Metze D, Brocker EB. Hailey-Hailey disease. Eradication by dermabrasion. Arch Dermatol 1994;130:1143–9. 103. Ruiz-Rodriguez R, Alvarez JG, Jaen P, et al. Photodynamic therapy with 5-aminolevulinic acid for recalcitrant familial benign pemphigus (Hailey-Hailey disease). J Am Acad Dermatol 2002;47:740–2. 104. Le Sache-de Peufeilhoux L, Raynaud E, Bouchardeau A, et al. Familial benign chronic pemphigus and doxycycline: a review of 6 cases. J Eur Acad Dermatol Venereol 2014;28:370–3. 105. Sardy M, Ruzicka T. Successful therapy of refractory Hailey-Hailey disease with oral alitretinoin. Br J Dermatol 2014;170:209–11. 106. Fairris GM, White JE, Leppard BJ, Goodwin PG. Methotrexate for intractable benign familial chronic pemphigus. Br J Dermatol 1986;115:640. 107. Berth-Jones J, Smith SG, Graham-Brown RA. Benign familial chronic pemphigus (Hailey-Hailey disease) responds to cyclosporin. Clin Exp Dermatol 1995;20:70–2. 108. Biolcati G, Aurizi C, Barbieri L, et al. Efficacy of the melanocortin analogue Nle4-D-Phe7-alphamelanocyte-stimulating hormone in the treatment of patients with Hailey-Hailey disease. Clin Exp Dermatol 2014;39:168–75.

GENODERMATOSES SECTION 9

Primary Immunodeficiencies Julie V. Schaffer and Amy S. Paller

Chapter Contents Ataxia–telangiectasia . . . . . . . . . . . . . . . . . . . . . . . . . . . . 955 Chronic mucocutaneous candidiasis . . . . . . . . . . . . . . . . . . . 958 Cartilage–hair hypoplasia syndrome . . . . . . . . . . . . . . . . . . . 962 Chédiak–Higashi syndrome . . . . . . . . . . . . . . . . . . . . . . . . 962

60 

Introduction Ataxia–telangiectasia (AT) is characterized by oculocutaneous telangiectasias, progressive cerebellar ataxia beginning in infancy, a variable immunodeficiency with a tendency to develop sinopulmonary infections, and chromosomal instability with persistent DNA damage after exposure to ionizing radiation.

Complement disorders . . . . . . . . . . . . . . . . . . . . . . . . . . . 964

Epidemiology

Chronic granulomatous disease . . . . . . . . . . . . . . . . . . . . . . 966

AT is an autosomal recessive disorder that occurs in 1 in 40 000 to 100 000 live births, with a carrier rate of up to 1% of the population.

Hyperimmunoglobulin E syndromes . . . . . . . . . . . . . . . . . . 971 Immunoglobulin deficiencies . . . . . . . . . . . . . . . . . . . . . . . 974 IPEX syndrome . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 974 Leukocyte adhesion deficiency . . . . . . . . . . . . . . . . . . . . . . 978 Severe combined immunodeficiency and Omenn syndrome . . . 979 Wiskott–Aldrich syndrome . . . . . . . . . . . . . . . . . . . . . . . . . 981

INTRODUCTION Primary immunodeficiencies represent a heterogeneous group of inherited disorders characterized by immune system defects that result in susceptibility to infections as well as additional manifestations such as autoimmunity, allergy, and malignancy. The molecular bases have been defined for >200 monogenic primary immunodeficiency diseases, providing valuable insight into the functions of the human immune system1–4. Patients with genetic immunodeficiency disorders often manifest with cutaneous abnormalities1,3. Some of these skin findings are highly characteristic of a particular disorder, while others, such as eczematous or granulomatous dermatitis, are shared by other immunodeficiencies5 (Table 60.1). Immunodeficiency disorders covered in other chapters are listed in Table 60.2. In general, immunodeficiency should be suspected when patients have recurrent infections of longer duration and greater severity or caused by unusual organisms. Additional signs may include incomplete clearance of infections or a poor response to antimicrobial therapy. Screening laboratory tests for a patient with recurrent cutaneous infections that raise suspicion of a primary immunodeficiency are listed in Table 60.36 Determination of the genetic etiology, which may require high-throughput approaches such as whole exome sequencing, can provide prognostic information and improve management6a.

ATAXIA–TELANGIECTASIA Synonym:  ■ Louis–Bar syndrome

Key features ■ Progressive cerebellar ataxia ■ Oculocutaneous telangiectasias, initially of the bulbar conjunctivae ■ Selective deficiency of humoral and cell-mediated immunity, leading to sinopulmonary infections ■ Increased sensitivity to ionizing radiation ■ Leukemias and lymphomas

Pathogenesis AT results from mutations in the ataxia–telangiectasia mutated gene (ATM), which encodes a phosphatidylinositol 3-kinase-like serine/ threonine protein kinase that plays a central role in activating apoptotic and cell cycle responses to DNA damage, particularly double-stranded breaks7. These DNA breaks are sensed directly by the MRE11–RAD50– nibrin (NBN) (MRN) complex, which recruits ATM and triggers its dissociation from inactive multimers to active monomers8,9. Autophosphorylated ATM monomers subsequently activate (via phosphorylation) a variety of targets, including p53, BRCA1, FANCD2, and Artemis in addition to NBS1 and MRE11. The result is cell cycle arrest and facilitation of DNA repair, both in the setting of external insults (e.g. ionizing radiation) and in the processing of physiologic DNA breaks that occur during V(D)J recombination in lymphocytes, telomere maintenance, and meiosis7. This provides an explanation for the sensitivity to ionizing radiation, immunodeficiency, premature aging, and defective spermatogenesis that are observed in patients with AT. Progressive neurologic deterioration in affected individuals likely reflects defective DNA repair in a cell population that cannot replicate. Oxidative stress related to ATM dysfunction has also been implicated in the pathogenesis of the disease. Of note, mutations in genes encoding components of the MRN complex cause conditions with manifestations similar to AT. MRE11 mutations underlie the AT-like disorder, which features radiosensitivity and neurologic manifestations but no telangiectasias, and NBN or rarely RAD50 mutations result in Nijmegen breakage syndrome characterized by microcephaly, immunodeficiency, chromosomal instability, and cancer predisposition.

Clinical Features The first manifestation of AT is usually ataxia, which typically appears when the affected child begins to walk. However, the diagnosis is often not recognized until the oculocutaneous telangiectasias are well developed, at a median age of 6 years10. The telangiectasias first appear at 3–6 years of age on the lateral and medial bulbar conjunctivae as red, symmetric horizontal streaks (Fig. 60.1A). Telangiectasias subsequently develop on the ears, eyelids, malar prominences, antecubital and popliteal fossae and presternal area, and less commonly on the dorsal aspects of the hands and feet as well as the hard and soft palate. The non-facial cutaneous telangiectasias are often subtle, resembling fine petechiae (Fig. 60.1B). Progeric changes of the skin and hair are noted in almost 90% of patients. Subcutaneous fat is lost early and the facial skin tends to become atrophic and sclerotic. Gray hairs frequently appear in young children, and diffuse graying of the hair may occur by adolescence. Non-infectious cutaneous granulomas are another common cutaneous manifestation of AT11 (Fig. 60.1C). These granulomatous plaques tend to be persistent and ulcerate, leading to significant discomfort. Children with AT often have hyper- or hypopigmented macules as well as nevoid

955

Primary immunodeficiencies represent a heterogeneous group of disorders characterized by increased susceptibility to infection. Many of these conditions have additional manifestations involving autoimmunity, allergy, lymphoproliferation, and risk of malignancy. Mucocutaneous abnormalities are often a presenting sign of primary immunodeficiencies, and recognition of these findings can facilitate diagnosis and appropriate management. Improved understanding of the genetic and molecular defects underlying many forms of immunodeficiency has led to improved treatment of affected individuals and provided important insights into immune functions.

ataxia–telangiectasia chronic mucocutaneous candidiasis cartilage–hair hypoplasia syndrome Chédiak–Higashi syndrome complement disorders chronic granulomatous disease hyperimmunoglobulin E syndromes DOCK8 deficiency immunoglobulin deficiencies IPEX syndrome leukocyte adhesion deficiency severe combined immunodeficiency (SCID) Wiskott–Aldrich syndrome

CHAPTER

60 Primary Immunodeficiencies

ABSTRACT

non-print metadata KEYWORDS

955.e1

SECTION

Genodermatoses

9

CUTANEOUS FINDINGS IN PRIMARY IMMUNODEFICIENCY DISORDERS

S. aureus infections Disorder

Superficial pyodermas

Abscesses

Ataxia–telangiectasia

+

+

Chédiak–Higashi syndrome

+

+

Chronic granulomatous disease

++

++

Eczematous CMC Warts dermatitis +

+

++

Chronic mucocutaneous candidiasis Common variable immunodeficiency

+

+

+

Complement deficiencies

+

+

+

DiGeorge syndrome† ++

++ (cold)

Hyper-IgM syndrome

+

+

Idiopathic CD4+ lymphocytopenia

IgA deficiency

+

+

IgM deficiency

+

+

IL-1 receptorassociated kinase-4 (IRAK-4) deficiency

++

++ (cold)

Ulcers SVV (PG-like) Other findings

+ (often ulcerate)

++ (nodular, necrotic)

Oculocutaneous telangiectasias, progeric changes, CALM, BCC

+

+

+

WHIM syndrome

+

+

Wiskott–Aldrich syndrome

++

+

X-linked agammaglobulinemia

+

++

Pigmentary dilution, hyperpigmentation in sunexposed sites, silvery hair, bleeding diathesis, gingivitis

+

DLE in female carriers, Sweet syndrome, oral ulcers

+

+

+

+



+

++

+

+

+

+

Dermatophyte infections, vitiligo, alopecia areata

++

+

+

Dermatomyositis, urticaria, lipodystrophy (C3), JIA

+

++

+

+

++

Dermatophyte infections, vitiligo, alopecia areata

Neonatal papulopustular eruption +

+

+

+

+

+

+

Oral ulcers CD4+ T cells 70%), hypogonadism (especially in female patients), and intellectual disability (~30%)14. Although lymphoid malignancy has been reported as the presenting sign of AT during infancy, most neoplasias occur in young adults. Patients who survive into their late teenage years have an up to 40% risk of developing a malignancy, especially leukemia (70-fold increase compared to unaffected individuals) and lymphoma (200-fold increase). Occasionally, patients develop basal cell carcinomas (BCCs) during the third decade of life. Carriers of heterozygous ATM mutations have a two- to threefold increase in both the risk of developing breast cancer and the likelihood of death from cancer, including malignancies of the stomach, colon, and lung as well as the breast. There is greater excess mortality in individuals AR

TNFRSF6

CD95 (Fas; cell-surface apoptosis receptor)

AD >AR

TNFSF6

CD95L (Fas ligand)

AR

FADD

Fas-associated death domain

Massive LAN and/or splenomegaly Increased CD4−/CD8− α/β T cells • Autoimmune cytopenias, LE, small vessel vasculitis • Recurrent bacterial and viral infections (CASP8) • Increased risk of lymphoma

AD > AR

CASP10

Caspase 8 and 10 (proteases in intracellular apoptosis cascade)

AR

CASP8

Mosaic

NRAS, KRAS

NRAS, KRAS (gain of function leads to decreased lymphocyte apoptosis)

AR

PRKCD

Protein kinase C δ (regulates B-cell proliferation)

AD

CTLA4

Cytotoxic T lymphocyte-associated protein 4 (costimulation of T cells)

AR

IL2RA

IL-2 receptor α-chain (apoptosis of developing T cells in the thymus)

Immunodeficiency with lymphoid proliferation

Decreased CD4+ T cells EBV infection with persistent viremia; recurrent sinopulmonary infections • EBV-associated lymphoma •



EBV-associated lymphoproliferation and lymphoma • Recurrent bacterial, viral (including warts, molluscum, HSV), and candidal infections • Autoimmune cytopenias • •

Bacterial, viral, and fungal infections Extensive lymphocytic infiltration of the liver, lung, gut and bones • Eczematous dermatitis; autoimmune polyendocrinopathy, cytopenias and enteropathy • •

*LRBA mutations (see Table 60.15) and gain-of-function CARD11 or STAT3 mutations can also lead to autoimmune lymphoproliferative syndrome-like disorders. Table 60.6 Inherited disorders characterized by lymphoproliferation due to immune dysregulation. Hemophagocytic syndromes result from uncontrolled T-cell and macrophage activation, manifesting with fever, pancytopenia, hepatosplenomegaly (HSM) and lymphadenopathy (LAN) (due to lymphohistiocytic infiltration), hypertriglyceridemia, and hypofibrinogenemia. AD, autosomal dominant; AR, autosomal recessive; CTL, cytotoxic T lymphocytes; Inh, inheritance; LE, lupus erythematosus; NK, natural killer; XR, X-linked recessive.  

COMPLEMENT DISORDERS Key features

964

■ Deficiency or dysfunction of early complement components increases susceptibility to pyogenic infections caused by encapsulated bacteria and autoimmune disorders, especially systemic lupus erythematosus ■ Deficiency of late complement components leads to a markedly increased risk of neisserial infections

Introduction The complement system represents an important effector of the innate immune response (see Ch. 4). An enzymatic cascade of complement activation can be triggered by three different pathways: classical, alternative, and lectin (Fig. 60.6). In addition to their roles in killing microbial pathogens, complement proteins serve as regulators of a variety of humoral and cellular immune functions (Table 60.7). As a result, clinical manifestations of complement deficiency include autoimmune diseases as well as increased susceptibility to infection49,50.

Lectin pathway

Alternative pathway

Antigen:antibody complex

Mannose-binding lectin binds mannan on pathogen surface

Pathogen surfaces

C1 C4 C2

MBL:MASP C4 C2

C3 B D

C3 convertase

C4a (weak) C3a C5a

C4b (minor opsonin)

Peptide mediators of inflammation, phagocyte recruitment

Bind to complement receptors on phagocytes

C3b (major opsonin)

Terminal complement components C5b C6 C7 C8 C9

Membrane attack complex, lysis of certain pathogens and cells

Opsonization of pathogens Removal of immune complexes

Fig. 60.6 The main components and effector actions of complement. The C3b bound to the C3 convertase binds C5, allowing the C3 convertase to generate C5b, which associates with the bacterial membrane and triggers the late events. MBL, mannose-binding lectin; MASP, MBL-associated serine protease. © 2005 from Immunobiology by Charles A. Janeway, et al. Adapted with permission of  

Garland Science/Taylor & Francis Books, Inc.

Epidemiology Deficiency of C2 represents the most common hereditary complement disorder49. Homozygous C2 deficiency occurs in ~1 in 20 000 individuals, and 1–2% of the population has the heterozygous form. Homozygous deficiencies of C1q, C1r, C1s, and C4 are rare, but affected individuals manifest with autoimmune disease more frequently than those with homozygous C2 deficiency. Heterozygotes usually make enough protein to ensure function and are generally asymptomatic, so most of the complement disorders are inherited as autosomal recessive traits. One exception is hereditary angioedema (HAE), an autosomal dominant condition due to deficiency or dysfunction of the C1 inhibitor (see Ch. 18). In contrast to the low prevalence of deficiencies in components of the classical complement pathway, 5–10% of the population is homozygous or compound heterozygous for alleles that lead to a lack of functional mannose-binding lectin (MBL), the major recognition factor of the lectin pathway of complement activation51. Although the clinical penetrance of MBL deficiency is low, it may have a substantial impact on immunity and autoimmunity at the population level. In addition, ~1 in 10 000 individuals has a homozygous deficiency in the MBLassociated serum protease (MASP) that functions in this pathway.

Deficiency of C2 can result from a defect in either protein synthesis (type 1) or secretion (type 2). Defects involving the early components of the classical complement pathway (C1, C4, C2) manifest with an increased risk of autoimmune disorders, especially systemic lupus erythematosus (SLE)52 (Table 60.8). The genes that encode these complement components, including four highly polymorphic genes for C4 (two each for C4A and C4B), are located within the HLA region on chromosome 6. C4-null alleles have been linked with SLE, and the C4A gene is deleted in the Caucasoid extended haplotype (HLA A1, B8, DR3) that is strongly associated with SLE. The pathogenesis of SLE in the setting of complement deficiency may also be related to impaired physiologic clearance of autoantigencontaining apoptotic cells52. Epidermal keratinocytes undergoing UVBinduced apoptosis preferentially display autoantigens such as SSA/Ro in plasma membrane blebs. Binding of C1q to these blebs and the nucleolus results in activation of the classical complement pathway and removal of the apoptotic cells by phagocytes53; in the absence of C1q, autoantibodies have the opportunity to bind to SSA/Ro, leading to activation of B and T cells and loss of immune tolerance. Decreased MBL-mediated clearance of apoptotic debris and DNA might likewise explain the predisposition to SLE associated with MBL deficiency. Furthermore, the complement system may enhance the elimination of self-reactive B cells during lymphocyte development, with complement deficiency leading to a lack of B-cell self-tolerance. Complement components are also important for handling immune complexes and regulating production of cytokines (e.g. type I interferons) that have a key role in SLE pathogenesis. The variety of recurrent infections associated with complement deficiencies underscores the central role of complement in bacterial clearance. Patients deficient in the early classical components, especially C2, have increased susceptibility to infections with encapsulated bacteria, especially Str. pneumoniae. Opsonization of bacteria and fungi may be ineffective in disorders of the classical pathway because of the slow, inadequate formation of C3b. However, because the lectin and alternative pathways can bypass early classical components to intersect with the cascade at the level of C3 (see Table 60.7 & Fig. 60.6), these deficiencies do not usually lead to overwhelming infections. C5 deficiencies result in impaired generation of chemotactic factors, which may lead to inadequate neutrophil function. Individuals with C5 to C9 (membrane attack complex; MAC), properdin, and factor D deficiencies develop recurrent neisserial infections in their teenage years. This underscores the importance of the bactericidal MAC complex and the alternative complement pathway (which requires properdin and factor D) in the destruction of these organisms. However, because a lack of lytic activity limits release of bacterial products (e.g. lipopolysaccharide) that stimulate a damaging cytokine response, the mortality of meningococcal infections in patients with MAC deficiency is actually lower than that in immunocompetent individuals. In contrast, patients with a properdin or factor D deficiency are unable to eradicate Neisseria spp. via opsonophagocytosis and have severe disease that is often fatal.

CHAPTER

60 Primary Immunodeficiencies

Classical pathway

Slow and inefficient

Rapid and efficient

THE MAIN COMPONENTS AND EFFECTOR ACTIONS OF COMPLEMENT

Pathogenesis

Clinical Features Individuals with homozygous deficiencies in the early components of the classical complement pathway (C1, C4, C2) have a risk of SLE that ranges from >90% for C1q to 10–20% for C2. Among those with C2 deficiency, features of lupus erythematosus (especially photosensitivity and subacute cutaneous lupus erythematosus) are most common in women, with the age at onset ranging from early childhood to adulthood (median 30 years). Other manifestations of C2 deficiencyassociated SLE are presented in Table 60.9. SLE in the setting of C1q/r/s or C4 deficiency usually develops during childhood, affects boys and girls equally, and is often associated with renal disease and palmoplantar keratoses as well as photosensitivity. Other autoimmune and/or inflammatory disorders and susceptibilities to infection associated with complement deficiencies are listed in Table 60.8. C2 deficiency may coexist with common variable immunodeficiency, and the development of Hodgkin disease has occasionally been reported. MBL deficiency may confer an increased risk of acute respiratory infections in children aged 6–18 months, who no longer have maternal antibodies but are not yet able to mount an efficient antibody response

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COMPLEMENT SPLIT PRODUCTS AND COMPLEXES

Split product

Function

C1q

Recognition factor of CP (binds Ag–Ab complexes) Activates C1r

C1r

Cleaves C1s to an active protease

C1s

Cleaves C4 and C2

C4a

Anaphylatoxin (weak)

C4b

Part of the CP C3 and C5 convertases Opsonization

C2a

Part of the CP C3 and C5 convertases

C2b

Unknown

C3(H2O)

Recognition factor of AP (binds bacterial surfaces, including lipopolysaccharide)

C3a

Anaphylatoxin Chemotaxis (eosinophils) Direct antimicrobial effect

C3b

Part of CP C5 and AP C3/C5 convertases Opsonization

C5a

Anaphylatoxin (strong) Chemotaxis (neutrophils and monocytes) Regulation of apoptosis

C5b

Part of membrane attack complex

Function

C1inh-C1r-C1s

Formed during C1 activation

C4b2a

CP C3 convertase

C3bBb

AP C3 convertase

C4b2a3b

CP C5 convertase

C3b(n)Bb

AP C5 convertase

C5b-9n SC5b-9

Membrane attack complex Soluble terminal complement complex

Pathology The total hemolytic complement (CH50) is markedly decreased or undetectable in complement deficiencies other than hereditary angioedema. The alternative pathway lytic test (AP50) can be used to screen for deficiencies in components of this pathway, although it is less sensitive than the CH50. Immunoprecipitation assays (e.g. radial immunodiffusion, ELISA) can determine the levels of specific complement components and MBL54, and functional studies of individual components may be informative when antigen levels are normal.

Differential Diagnosis Complement components may be specific targets of autoimmune responses; for example, anti-C1q antibodies are found in 30–50% of patients with SLE (often with renal involvement) and virtually all of those with hypocomplementemic urticarial vasculitis. The “Leiner phenotype” of exfoliative dermatitis, failure to thrive, chronic diarrhea, and recurrent infections has been observed in infants with C3 or C5 deficiency or C5 dysfunction. However, this constellation of findings can also develop in patients with other disorders such as X-linked agammaglobulinemia, hyper-IgE syndrome, and severe combined immunodeficiency. Low complement levels related to bacterial and viral infections should also be differentiated from primary complement deficiencies.

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Complex

to the carbohydrate antigens of encapsulated bacteria51. Several studies have shown that MBL deficiency is associated with an increased risk of developing SLE or dermatomyositis and a higher incidence of infections in the setting of immunosuppressive therapy.

Table 60.7 Complement split products and complexes. Dark blue, classical pathway (CP); medium blue, CP and lectin pathway; yellow-tan, alternative pathway (AP); green, all three pathways. Anaphylatoxins are inflammatory mediators that increase vascular permeability and cause mast cell degranulation. Opsonization represents binding of a protein to the pathogen surface in order to target it for destruction. C1 inh, C1 esterase inhibitor; SC, soluble complex.

in more severe cases, with consideration of the increased risk of infections in patients with complement deficiencies. The use of plasma transfusions to replace the deficient components may actually activate the cascade and accelerate immune complex deposition. Infections should be treated with early, aggressive antibiotic therapy. Pneumococcal vaccination is recommended for individuals with an early component complement deficiency and meningococcal vaccination for those with a C3, C5–C9, properdin, factor D, or factor H deficiency.

CHRONIC GRANULOMATOUS DISEASE Synonyms:  ■ Chronic granulomatous disorder ■ Bridges–Good syndrome ■ Quie syndrome

Key features ■ Inability to kill intracellular organisms through generation of oxidative metabolites ■ X-linked recessive or autosomal recessive inheritance ■ Recurrent pneumonias and cutaneous infections, lymphadenopathy, and hepatosplenomegaly ■ Patients develop granulomas as a compensatory effort to confine organisms

Treatment

Introduction

Conservative therapy is often effective for patients with autoimmune manifestations of complement deficiency. The use of topical corticosteroids and sun protection may be sufficient to treat cutaneous lupus erythematosus in these individuals. Antimalarial drugs, systemic corticosteroids, and other immunosuppressive medications are required

Chronic granulomatous disease (CGD) is a group of disorders characterized by severe, recurrent infections due to an inability of leukocytes to kill phagocytosed bacteria and fungi by generating oxidative metabolites55. The activity of the nicotinamide dinucleotide phosphate (NADPH) oxidase complex is reduced in all forms of CGD.

CHAPTER

Complement component

Common infectious agents

Autoimmune/inflammatory disorders

C1q

Encapsulated bacteria, Candida spp.

SLE*, dermatomyositis, GN

C1r

Encapsulated bacteria

SLE*, GN

C1s

Encapsulated bacteria

SLE*

Classical pathway

Hereditary angioedema ≫ SLE, GN, partial lipodystrophy, vasculitis

C1 inhibitor C4

Encapsulated bacteria

SLE* with PPK and scars, HSP, GN, urticaria, JIA‡

C2†

Encapsulated bacteria, especially Streptococcus pneumoniae

SLE*, SCLE, DLE, dermatomyositis, HSP, other vasculitides, atrophoderma, cold urticaria, JIA‡, IBD, atherosclerosis

MBL§

Encapsulated bacteria, especially N. meningitides

SLE, dermatomyositis, atherosclerosis, chronic pulmonary disease

MASP-2

Encapsulated bacteria, especially S. pneumoniae

SLE, IBD

C3

Encapsulated bacteria (severe infections)

SLE, vasculitis, lipodystrophy (partial [cephalo]thoracic), GN, “Leiner phenotype”

Factor H

Encapsulated bacteria

SLE, HUS, GN, age-related macular degeneration

Factor I (C3b inactivator)

Encapsulated bacteria

SLE, HUS, aquagenic urticaria, angioedema

Properdin (XLR)

Neisseria spp. (fulminant infections)

Factor D

Neisseria spp.

60 Primary Immunodeficiencies

COMPLEMENT DISORDERS

Lectin pathway

C3 and alternative pathway

Membrane attack complex C5 dysfunction

Gram-negative bacteria

“Leiner phenotype”

C5 deficiency

Neisseria spp., S. pneumoniae

SLE

C6

Neisseria, Brucella, Toxoplasma spp.

SLE, JIA, GN

C7

Neisseria spp.

SLE, limited systemic sclerosis, ankylosing spondylitis

C8α

Neisseria spp.

SLE, fever with HSM, eosinophilia, hypergammaglobulinemia

C8β

Neisseria spp.

SLE, JIA

C9

Neisseria spp.

*† Hierarchy of SLE risk with homozygous mutations: C1q (~90%) > C1r/s > C4 > C2 (~10–20%). Most common of the homozygous complement deficiencies.

‡Especially in heterozygous girls. §Very low penetrance.

Table 60.8 Complement disorders. Unless otherwise specified, affected individuals usually have biallelic defects. Pyogenic infections caused by encapsulated organisms (e.g. Streptococcus pneumoniae, Haemophilus influenzae, Streptococcus pyogenes) in individuals with classical pathway component deficiencies are not as frequent as neisserial infections in those with membrane attack complex component deficiencies. DLE, discoid lupus erythematosus; GN, glomerulonephritis; HSM, hepatosplenomegaly; HSP, Henoch–Schönlein purpura; HUS, hemolytic uremic syndrome; IBD, inflammatory bowel disease; INH, inhibitor; JIA, juvenile idiopathic arthritis; MBL, mannose-binding lectin; MASP, MBL-associated serum protease; PPK, palmoplantar keratoderma; SCLE, subacute cutaneous lupus erythematosus; SLE, systemic lupus erythematosus; XLR, X-linked recessive. Adapted with permission from Schachner L, Hansen R (eds). Pediatric Dermatology, 4th edn. London: Mosby, 2011.  

Epidemiology The incidence of CGD is ~1 in 200 000 live births56,57. Ninety percent of patients are boys. Approximately three-quarters of cases have X-linked recessive transmission, while the remainder are autosomal recessive.

Pathogenesis The defects in CGD involve five subunits of the phagocyte NADPH oxidase: the membrane-bound gp91phox (phagocyte oxidase) and p22phox; and the cytoplasmic p47phox, p67phox, and p40phox (Table 60.10). The failure of microbial killing that characterizes CGD results from an inability of the NADPH oxidase system to rapidly generate toxic reactive oxygen species (ROS) by transferring electrons from NADPH to molecular O2 (the “respiratory burst”) after phagocytosis of a pathogen. Regardless of the gene affected in patients with CGD, having residual NADPH oxidase activity and the resultant ability to generate ROS is associated with less severe disease and longer survival58,59. NADPH oxidase activity results in the activation of antimicrobial proteases within the phagosome and the formation of microbicidal

“neutrophil extracellular traps” (NETs)60,61. In addition to killing and degrading microorganisms, ROS produced by the NADPH oxidase system have roles in the regulation of cytokine synthesis as well as induction of neutrophil apoptosis, which prevents tissue damage at sites of inflammation. Animal models of CGD have shown that a lack of ROS leads to excess inflammation via decreased regulatory T-cell activity, unrestrained γ/δ T-cell activity, and augmented production of cytokines such as IL-1β, IL-8, and IL-17. NADPH oxidase also has a role in modulating MHC class II antigen presentation by B cells62.

Clinical Features The skin, perianal area, lymph nodes, and lungs are the sites most often affected by CGD. In general, the X-linked form tends to be more severe than the autosomal recessive forms, with a younger mean age at diagnosis (3 years versus 8 years)56. Organisms that commonly cause infections in patients with CGD are listed in Table 60.1163. Most carriers of CGD do not have an increased susceptibility to infections.

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The earliest manifestations of CGD are usually staphylococcal infections of the skin around the ears and nose, which may begin in the neonatal period and progress to extensive purulent dermatitis with regional lymphadenopathy during infancy. Initial presentation of CGD as ecthyma gangrenosum in the neonatal period has also been described64. Cutaneous abscesses occur in 40% of patients, usually due to S. aureus but also Serratia marcescens; these infections sometimes present as large, poorly healing cutaneous ulcers65. Non-infectious purulent inflammatory reactions may develop at sites of minor cutan­ eous trauma or regional lymph node drainage and heal slowly with scarring. Sterile cutaneous granulomas, which are often nodular and necrotic, occur less frequently than infections. Additional cutaneous manifestations include acute or chronic cutaneous lupus erythematosus-like skin lesions, most commonly discoid66 (Fig. 60.7A, B); Sweet syndrome-like lesions; ulcers involving the oral mucosa (resembling aphthous stomatitis), the perioral area, and other cutaneous sites (Fig. 60.7C); and seborrheic dermatitis or folliculitis of the scalp. Female carriers of X-linked CGD occasionally present with discoid lesions, lymphocytic infiltrate of Jessner, photosensitivity, Raynaud phenomenon, severe aphthous stomatitis, and granulomatous cheilitis.

FEATURES OF SYSTEMIC LUPUS ERYTHEMATOSUS IN C2 DEFICIENCY

The extracutaneous organs most frequently involved in CGD are the lymph nodes, lungs, liver, spleen, and gastrointestinal tract (Table 60.12). Suppurative lymphadenitis develops in half of patients, most often affecting cervical nodes and leading to abscess and fistula formation. Granulomas of the lungs, liver, spleen, and gastrointestinal and genitourinary tracts occur more frequently than those of the skin. These granulomas can lead to obstruction of the gastric outlet or urinary tract. Excessive inflammatory responses may also lead to wound dehiscence, pneumonitis, and hemophagocytic lymphohistiocytosis. Approximately 40–80% of CGD patients develop gastrointestinal manifestations (e.g. chronic diarrhea, fistulas) similar to those of inflammatory bowel disease; clinical presentations can also mimic sarcoidosis, rheumatoid arthritis, and IgA nephropathy57,67,68.

ORGANISMS THAT CAUSE INFECTIONS IN PATIENTS WITH CHRONIC GRANULOMATOUS DISEASE

Type of organism

Common causes

Less frequent causes

Gram-positive bacteria

Staphylococcus aureus* Nocardia spp.

Propionibacterium spp.

Gram-negative bacteria

Burkholderia cepacia Klebsiella spp. Serratia marcescens†

Acinetobacter spp. Other Burkholderia spp. Chromobacterium violaceum Enterobacter spp. Escherichia coli Granulobacter bethesdensis Francisella philomiragia Proteus spp. Pseudomonas spp. Salmonella spp.

Features more suggestive of C2 deficiency-associated SLE than classic SLE

Common features Photosensitivity* SCLE*, ACLE, or DLE Cicatricial alopecia Oral ulcerations (50%) Fever (>50%) Arthralgias and/or arthritis (80%) Leukopenia (50%) Anti-SSA/Ro antibody (75%) Rheumatoid factor (40%)

Childhood onset Extensive, treatment-resistant skin lesions Mild or absent renal disease Absent or low-titer ANA and antidsDNA antibodies Negative lupus band test Less severe disease overall Pyogenic infections with encapsulated bacteria, e.g. Streptococcus pneumoniae Increased risk of atherosclerosis

*Most common cutaneous manifestations. Table 60.9 Features of systemic lupus erythematosus (SLE) in C2 deficiency. Less frequent manifestations include central nervous system vasculitis, pleuritis, pericarditis, Raynaud phenomenon, thrombocytopenia, anti-Sm or anti-RNP antibodies, circulating immune complexes and a positive RPR. ACLE, acute cutaneous lupus erythematosus; DLE, discoid lupus erythematosus; SCLE, subacute cutaneous lupus erythematosus. Adapted with permission from Schachner L,  

Hansen R (eds). Pediatric Dermatology, 4th edn. London: Mosby, 2011.

Mycobacterium tuberculosis Atypical mycobacteria Bacillus Calmette–Guérin (BCG)**

Mycobacteria

Candida spp. Aspergillus spp.‡

Fungi

Paecilomyces spp. Penicillium spp. Phaeohyphomycetes Phellinus spp. Trichosporon spp.

*† Most common cause of cutaneous infections, abscesses, and suppurative adenitis.

Most common cause of osteomyelitis; also a frequent cause of cutaneous abscesses and ulcers. Including severe and disseminated infections. ** ‡Most common cause of pneumonia.

Table 60.11 Organisms that cause infections in patients with chronic granulomatous disease.  

GENETIC DEFECTS AFFECTING COMPONENTS OF THE PHAGOCYTE NADPH OXIDASE

Location within NADPH oxidase Disorder

Gene

Protein

Resting state

Active state

Approximate % of CGD patients

X-linked recessive chronic granulomatous disease

CYBB

gp91phox

Membrane-bound subunits of flavocytochrome b558

Same

70

Autosomal recessive chronic granulomatous disease

CYBA

p22phox

NCF1

p47phox

Cytosolic complex

NCF2

p67

phox

Associated with flavocytochrome b558

NCF4

p40phox

RAC2

Rac2 GTPase*

Neutrophil immunodeficiency syndrome

≤5 20 ≤5 Rare Cytosolic complex with RhoGDI

Membrane- and GTP-bound



*Also has a role in actin cytoskeletal dynamics, integrin-dependent adhesion and neutrophil migration; see Table 60.13. 968

Table 60.10 Genetic defects affecting components of the phagocyte NADPH oxidase. CGD, chronic granulomatous disease; NCF, neutrophil cytosolic factor; RhoGDI, Rho GDP-dissociation inhibitor.  

CHAPTER



MD.

$

FREQUENCY OF SIGNS AND SYMPTOMS IN PATIENTS WITH CHRONIC GRANULOMATOUS DISEASE

Symptom

Approximate % of patients

Lymphadenopathy

90

Hepatosplenomegaly

85

Pneumonia

80

Underweight

75

Short stature

50

Persistent diarrhea and/or abdominal pain

40

Hepatic/perihepatic abscess

35

Pleuritis/empyema

35

Septicemia or meningitis

35

Osteomyelitis

25

Conjunctivitis and/or chorioretinitis

25

Facial periorificial dermatitis

20

Perianal abscess

15

Lung abscess

15

Ulcerative stomatitis

15

Peritonitis

10

Onset by age 1 year

65

Onset with lymphadenitis

25

60 Primary Immunodeficiencies

Fig. 60.7 Chronic granulomatous disease. Lupus erythematosuslike annular plaques and papules on the infraorbital cheek (A) and neck (B). Pyoderma gangrenosum-like ulcers at an ostomy stoma site (C). Courtesy, Edward Cowen,

Table 60.12 Frequency of signs and symptoms in patients with chronic granulomatous disease.  

%

lack vacuolar degeneration of basal keratinocytes; immunofluorescence examination of lesional skin is negative in most cases. The screening test for CGD is the nitroblue tetrazolium (NBT) reduction assay. NBT is yellow in its soluble, oxidized form; when reduced, the dye precipitates and becomes blue (formazan precipitate). Only 5–10% of leukocytes from patients with CGD are able to reduce NBT during phagocytosis, compared to 80–90% of leukocytes from unaffected individuals and ~50% of leukocytes from carriers of X-linked CGD. The ferricytochrome c reduction and dihydrorhodamine (DHR) 123 assays are more accurate and quantitative in measuring the respiratory burst, and they can be performed to verify the diagnosis of CGD69. Immunoblot analysis may demonstrate lack of the gp91phox and p22phox proteins; however, gene sequencing must still be done to ascertain which gene is affected, since mutations resulting in the absence of one protein lead to the absence of the other. A lack of the p47phox, p67phox, or p40phox protein by immunoblot analysis indicates the affected gene.

Differential Diagnosis &

Laboratory tests allow differentiation of CGD from other immuno­ deficiency disorders characterized by increased susceptibility to bacterial infections. Additional inherited phagocyte disorders are listed in Table 60.13.

Treatment Pathology Common nonspecific abnormalities in CGD include leukocytosis, anemia, elevated ESR, hypergammaglobulinemia, a decreased number of T cells, and an abnormal chest radiograph. Skin testing for delayedtype hypersensitivity is normal, as are studies of phagocytosis and chemotaxis. Biopsy specimens from cutaneous granulomas that develop in CGD patients demonstrate histiocytic infiltrates associated with foreign body giant cells and accumulation of neutrophils with necrosis. Lupus erythematosus-like skin lesions in CGD patients and carriers may have histologic features similar to classic discoid lesions, but they sometimes

The use of antibiotics has markedly reduced the morbidity and mortality rates of CGD. Although cutaneous and nodal infections are often readily apparent, localized foci of internal infection (which may or may not be associated with fever) can be difficult to detect. Thorough periodic evaluation of the lungs, liver and bones by routine radiographs, ultrasounds or CT, MRI, positron emission tomography (PET), and bone scans often uncovers occult foci of inflammation or infection. Cultures should be performed to identify the infectious agent, and invasive procedures may be necessary to obtain adequate tissue samples. While awaiting culture results or in situations where material from the affected site cannot be obtained, patients with evidence of infection should be treated empirically with broad-spectrum parenteral antibiotics that cover S. aureus as

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well as Gram-negative bacteria. Intravenous therapy should be continued for at least 10–14 days, followed by a several-week course of oral antibiotics. Surgical interventions such as debridement, irrigation, and prolonged drainage are important for deeper infections. Chronic prophylaxis with trimethoprim–sulfamethoxazole has been shown to decrease the incidence of bacterial infection in CGD patients without increasing the incidence of fungal infections. The rate of Aspergillus spp. infections has been reduced by prophylaxis with itraconazole70. Patients with CGD have shown clinical improvement after administration of interferon-γ, which likely augments oxidant-independent antimicrobial pathways. Granulocyte transfusions have been used for rapidly progressive, life-threatening infections. Short courses of systemic corticosteroids have also been helpful for patients with obstructive granulomas of the bronchopulmonary, gastrointestinal, or genitourinary tract53. Additional immunomodulatory therapies with potential benefit for inflammatory

manifestations of CGD include azathioprine, hydroxychloroquine, anakinra, thalidomide, pioglitazone (increases ROS production and efferocytosis), and possibly sirolimus71,72; tumor necrosis factor (TNF) inhibitors may improve colitis but increase the risk of infectious complications. Hematopoietic stem cell transplantation represents a potentially curative treatment for CGD. Although younger patients without infection at the time of transplantation have the best outcomes (survival >95%), use of reduced-intensity conditioning regimens has enabled successful transplantation of higher-risk patients such as adults and individuals with recalcitrant infections or inflammatory manifestations73. Children with CGD who undergo transplantation have improved growth and fewer infections, surgical interventions, and hospital admissions than those managed conservatively74. Gene therapy was initially performed in five adults with the p47phoxdeficient form of CGD, and a single infusion of transduced CD34+

OTHER INHERITED PHAGOCYTE DEFECTS

Disorder

Inh

Gene

Protein (defect or function)

Clinical features

Selected disorders featuring neutropenia or neutrophil defects Severe congenital neutropenia

AD AD AR AD

ELANE GFI1 HAX1 CSF3R

Neutropenia MDS, AML

Neutrophil elastase (abnormal elastase trafficking and accumulation)



Transcriptional repressor of elastase (abnormal elastase accumulation)



Mitochondrial HS1-associated protein X1 (protects against apoptosis in myeloid cells)



Granulocyte colony-stimulating factor receptor





Neutropenia, lymphopenia Circulating myeloid progenitors



Neutropenia Increased apoptosis of myeloid cells



Neutropenia Severe myeloid hypoplasia



AR

G6PC3

Glucose 6 phosphatase catalytic subunit 3 (glucose metabolism)



Neutropenia, thrombocytopenia Urogenital and cardiac malformations • Ectatic veins on trunk/extremities •

Cyclic neutropenia

AD

ELANE

Neutrophil elastase



X-linked neutropenia

XR

WASP

WASP (gain of function; see text, Wiskott–Aldrich syndrome)



p14 deficiency

AR

LAMTOR2

Endosomal adaptor protein p14 (p14; endosomal biogenesis)



SBDS protein (ribosomal RNA metabolism)



Shwachman–Bodian– Diamond syndrome

AR

Poikiloderma with neutropenia, Clericuzio type

AR

Specific granule deficiency

AR

Myeloperoxidase deficiency

AR

SBDS

Alternating 21-day cycles of neutropenia & monocytopenia • Fever and oral ulcers at nadir Neutropenia

Neutropenia Pneumococcal infections • Diffuse pigmentary dilution of the skin and hair • Short stature, coarse facies •

Neutropenia > pancytopenia MDS, AML • Exocrine pancreatic insufficiency • Chondrodysplasia •

USB1

U6 snRNA biogenesis phosphodiesterase 1

Neutropenia Dermatitis → poikiloderma, keratotic papules • Recurrent skin & respiratory infections • •

CEBPE MPO

C/EBPε transcription factor (granulocyte differentiation)



Bilobed neutrophils Recurrent bacterial infections

Myeloperoxidase (microbial killing by granulocytes)





Candida spp. and S. aureus infections Often asymptomatic



Leukocyte adhesion deficiencies (LADs) and related conditions LAD-I

AR

β2-integrin subunit of LFA-1, CR3, and p150 (see text)

LAD-II

AR

SLC35C1 (FUCT1)

GDP-fucose transporter 1 (sialyl-Lewis X expression; see text)

LAD-III

AR

FERMT3

Kindlin-3 (defective integrin activation; see text)

Rac2 deficiency

AD

RAC2

Rac2 GTPase (NADPH oxidase, integrin-dependent adhesion, and neutrophil migration; see Table 60.10)

Neutrophilia; ↓ tissue neutrophils Necrotic abscesses, ulcers • Poor wound healing, delayed umbilical stump separation • Gingivitis • Bleeding diathesis (LAD-III) • •

Table 60.13 Other inherited phagocyte defects. See text and Tables 60.5 and 60.10 for Chédiak–Higashi syndrome and chronic granulomatous disease. AD, autosomal dominant; AML, acute myeloid leukemia; AR, autosomal recessive; BCG, bacillus Calmette–Guérin; IFN, interferon; IL, interleukin; Inh, inheritance; LFA-1, lymphocyte function-associated antigen-1; MDS, myelodysplastic syndrome; WASP, Wiskott–Aldrich syndrome protein; XR, X-linked recessive.  

970

ITGB2

CHAPTER

Disorder

Inh

Gene

Protein (defect or function)

Clinical features

Defects resulting in predisposition to specific infections Defects of the interleukin-12/ interferon-γ axis

Defects in Toll-like receptor (TLR) signaling

GATA2 deficiency/ MonoMAC syndrome

AR

IL12B

Subunit of IL-12 and IL-23 (stimulation of IFN-γ production)

AR

IL12RB1

IL-12 and IL-23 receptor β1 chain

AR, AD

IFNGR1

IFN-γ receptor (ligand binding)

AR

IFNGR2

IFN-γ receptor (signaling)

AR, AD

STAT1*

Signal transducer and activator of transcription 1 (STAT1)* (IFN receptor signaling is impaired by lossof-function mutations)

AR

TYK2

Tyrosine kinase 2 (IFN/IL-12/other cytokine receptor signaling)

AD

IFR8

IFN regulatory factor 8 (IL-12 signaling)

AR

ISG15

IFN-α/β-inducible ubiquitin-like modifier

AR

RORC

Retinoic acid receptor-related orphan receptor C (IFN-γ and IL-17 signaling)

AD

TLR3

TLR3 (signals IFN-α/β production)

AR

UNC93B1

UNC-93B (endoplasmic reticulum protein required for TLR3 signaling)

AD

TRAF3

TNF receptor-associated protein 3 (TLR3 signaling)

AD, AR

TICAM1 (TRIF)

TLR-adaptor molecule 1 (TLR3/4 signaling)

AD

TBK1

TANK-binding kinase 1 (TLR3 signaling)

AR

IRAK4

IL-1 receptor associated kinase-4 (IL-1 receptor & TLR signaling)

AR

MYD88

Myeloid differentiation primary response gene 88 (recruits IRAK4 to the IL-1 receptor and TLRs)

AD

GATA2

GATA binding protein 2

Severe mycobacterial and Salmonella infections • Disseminated BCG infection • Chronic mucocutaneous candidiasis (RORC, IL12RB1 > IL12B) • Viral infections (STAT1, TYK2) • Hyper-IgE syndrome (TYK2; see text) •

Primary Immunodeficiencies

60

OTHER INHERITED PHAGOCYTE DEFECTS

Herpes simplex encephalitis



Recurrent pyogenic sinopulmonary and skin infections with Streptococcus pneumoniae and S. aureus, respectively



Monocytopenia, B/NK lymphopenia, myelodysplasia, myeloid leukemia • Mycobacterial and fungal infections (e.g. histoplasmosis) • Recalcitrant warts • Lymphedema • Alveolar proteinosis •

*Gain-of-function STAT1 mutations lead to chronic mucocutaneous candidiasis (see Table 60.4) and/or confer susceptibility to endemic dimorphic fungal infections; loss-of-function STAT3

mutations underlie AD hyper-IgE syndrome (see text) while gain-of-function STAT3 mutations can result in lymphoproliferation, autoimmunity, hypogammaglobulinemia, mycobacterial infections, and occasionally psoriasiform dermatitis; defects in STAT5B, which is involved in IL-2 and growth hormone receptor signaling, lead to an AR syndrome of growth hormone insensitivity, decreased CD4+/CD25+ regulatory T cells, viral infections, and eczematous dermatitis.

Table 60.13 Other inherited phagocyte defects. (cont’d) AD, autosomal dominant; AR, autosomal recessive; IFN, interferon; IL, interleukin; Inh, inheritance.  

peripheral blood stem cells led to peak levels of corrected granulocytes in 3–6 weeks with persistence for as long as 6 months75. Subsequently, two young men with X-linked recessive CGD were treated with nonmyeloablative conditioning prior to the infusion of CD34+ peripheral blood stem cells transduced ex vivo with a retroviral vector expressing gp91phox; this led to sustained engraftment of functionally corrected phagocytes. However, following initial resolution of infections, the transgene was silenced due to methylation of the viral promoter in both patients, and within 3 years they developed myelodysplasia with monosomy 7 as a result of insertional activation of ecotropic viral integration site 1 (EVI1)76. To increase the safety and efficacy of gene therapy for CGD, current investigations are utilizing approaches such as selfinactivating lentiviral vectors, targeted integration of transgenes into a genomic “safe harbor” site, or the CRISPR-Cas9 site-specific nuclease system to encourage repair of the endogenous gene via homologous recombination (see Ch. 3)77,78. Dihydrorhodamine 123 flow cytometric studies may be utilized in determining the carrier status of the sisters and other female relatives of patients with X-linked CGD, which is important for genetic counseling prior to pregnancy. Prenatal diagnosis of CGD is also possible.

HYPERIMMUNOGLOBULIN E SYNDROMES Synonyms:  ■ Hyper-IgE syndromes ■ Job syndrome ■ Buckley syndrome

Key features ■ Characterized by recurrent skin and sinopulmonary tract infections, early-onset eczematous dermatitis, and extremely elevated IgE levels ■ The classic form is an autosomal dominant disorder with skin infections that are usually caused by S. aureus (in particular “cold abscesses”) and, especially during infancy, C. albicans ■ The autosomal dominant form also features a neonatal papulopustular eruption, progressively coarse facies, osteopenia with fractures, scoliosis, and dental abnormalities ■ Autosomal recessive forms have a broader spectrum of infectious complications

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Introduction

The classic form of HIES is inherited in an autosomal dominant fashion (AD-HIES) with variable expression. Clinically distinct autosomal recessive forms of HIES (AR-HIES) have also been described80–83.

the phosphoglucomutase 3 gene (PGM3), which lead to aberrant glycosylation affecting T-cell differentiation83. In addition, homozygous mutations in the gene encoding tyrosine kinase 2 (TYK2), a member of the JAK family, were identified in a patient with AR-HIES characterized by defects in signaling pathways for IL-12 and interferon-α/β (see Table 60.13) as well as IL-6 and IL-1091. However, other patients with PGM3 or TYK2 deficiency have had increased infections but not HIES. The dermatitis of HIES shares several immunopathologic features with atopic dermatitis, including abnormal cytokine responses. The expression of IgE in patients with HIES is maximally activated and does not increase further upon IL-4 administration; in contrast, IL-4 has a stimulatory effect on IgE production in both atopic dermatitis patients and normal individuals.

Pathogenesis

Clinical Features

Heterozygous mutations in the gene encoding signal transducer and activator of transcription 3 (STAT3) cause AD-HIES84,85. Different combinations of receptor-associated Janus kinases (JAKs) and STAT proteins transduce cytokine signals; upon phosphorylation by JAKs, the latter dimerize, translocate to the nucleus, and activate target genes (see Fig. 66.1). Susceptibility to bacterial and candidal infections in HIES reflects the roles of STAT3-dependent cytokines (e.g. IL-6, IL-21, IL-23) in the differentiation of IL-17-producing CD4+ T cells that help to defend against these organisms (see Fig. 4.10)86. A lack of stimulation of β-defensin production by IL-22, which is produced by Th17 cells and signals via STAT3, may contribute to the development of infections at epithelial surfaces (e.g. skin, lungs) in HIES. STAT3 is critical to the signaling pathways for both IL-6, which promotes acute phase responses and acts as a pyrogen, and IL-10, an anti-inflammatory cytokine. STAT3 dysfunction provides an explanation for the “cold” abscesses and destructive inflammation (e.g. in the lung) that characterize HIES. Defective generation of IL-10-induced tolerogenic dendritic cells and FOXP3+-induced regulatory T cells may contribute to other inflammatory features of HIES, such as the atopiclike dermatitis and high IgE levels87. STAT3 also down-regulates differentiation of osteoclasts, and osteoporosis represents a feature of STAT3 deficiency in mice as well as HIES. Lastly, leukocytes from both STAT3-deficient animals and patients with HIES produce higher levels of interferon-γ and tumor necrosis factor (TNF) upon stimulation with IL-12 and lipopolysaccharide/interferon-γ, respectively, than do leukocytes from unaffected controls84,85. Biallelic mutations in the dedicator of cytokinesis 8 protein gene (DOCK8) cause the most common form of AR-HIES (see below)81,82. The DOCK8 protein, a member of the DOCK180-related family of atypical guanine nucleotide exchange factors, interacts with the Wiskott–Aldrich syndrome protein (WASp) in a complex that links T-cell receptors to the actin cytoskeleton88. DOCK8 deficiency results in an increase in Th2 cells and production of the pruritogen IL-31, but a decrease in Th1 and Th17 cells89,90. Another form of AR-HIES that also presents with neurocognitive abnormalities and autoimmunity is caused by biallelic mutations in

Patients with AD-HIES typically present during the first month of life with a non-infectious, folliculocentric papulopustular eruption involving the face, scalp, neck, axillae, and diaper area92,93. Chronic candidiasis of the oral mucosa, periungual areas, and nails occurs in ~80% of HIES patients and may represent the initial infectious manifestation during infancy. Cutaneous staphylococcal infections include impetiginized plaques and retroauricular fissures, folliculitis, furunculosis, abscesses, cellulitis, lymphangitis, and paronychia leading to nail dystrophy93. The cutaneous abscesses are often large, and they most commonly involve the neck, scalp (Fig. 60.8A), periorbital area, axillae, and groin. Such lesions are referred to as “cold abscesses” because they are not as red or tender as those that develop in healthy individuals. Patients are often afebrile or have only a low-grade fever. Although the abscesses tend to be staphylococcal, many patients have recurrent skin infections with other organisms, including Str. pyogenes as well as C. albicans. The eczematous rash of AD-HIES shares many clinical features with atopic dermatitis, including severe pruritus, lichenification, and staphylococcal superinfection93. It is almost always present in young children with AD-HIES but frequently clears by adolescence. Unlike individuals with atopic dermatitis, patients with AD-HIES do not commonly exhibit allergic rhinitis, asthma, or other cutaneous signs of atopy. Although some AD-HIES patients have only cutaneous manifestations, most also develop recurrent bronchitis and pneumonias. S. aureus and Haemophilus influenzae usually cause the pulmonary infections, which may result in empyema, bronchiectasis, and pneumatocele formation. The pneumatoceles tend to persist and become the site of further infections with bacterial or fungal organisms, particularly Aspergillus spp. Massive hemoptysis occasionally ensues. Pneumocystis jiroveci pneumonia can also occur in infants and children with AD-HIES. Other common sites of infection include the ears, oral mucosa, sinuses, and eyes. Visceral infections other than pneumonia are unusual. AD-HIES patients develop progressive facial coarsening with thickened doughy skin, large follicular ostia, pitted scarring, a broad nasal bridge, a wide fleshy nasal tip, deep-set eyes, a prominent forehead, and irregularly proportioned cheeks and jaw (Fig. 60.8B). Osteopenia is

Hyperimmunoglobulin E syndromes (HIESs) are characterized by recurrent cutaneous and sinopulmonary infections, dermatitis beginning in infancy or early childhood, and extremely elevated IgE levels79. Job syndrome is a subgroup of autosomal dominant HIES that was originally described in female patients with fair skin, red hair, and hyperextensible joints as well as the typical features of HIES.

Epidemiology

Fig. 60.8 Autosomal dominant hyperimmunoglobulin E syndrome (AD-HIES). A Several erythematous, slightly purulent “cold” abscesses are apparent on the forehead and scalp of this infant. B Coarse facial features that developed progressively over time in an affected woman. Note the prominent follicular ostia, doughy skin, and broad nasal bridge. B, Courtesy, Edward  

Cowen, MD.

972

$

%

staphylococcal skin infections (including cold abscesses), respiratory tract infections, and mucocutaneous candidiasis. However, skeletal and dental abnormalities, facial coarsening, and pneumatoceles are not characteristic features80,94. Patients with DOCK8 deficiency are predisposed to the development of warts, molluscum contagiosum, severe herpes simplex and varicella–zoster viral infections, and opportunistic infections80,94,95 (Fig. 60.9B, C). Additional manifestations include asthma, food allergies resulting in anaphylaxis, autoimmunity, cerebral vasculitis, mucocutaneous squamous cell carcinomas, and lymphomas. Up to half of patients die by 20 years of age from infection, malignancy, or CNS disease80,94.

Laboratory Findings and Pathology

CHAPTER

60 Primary Immunodeficiencies

frequently present and is associated with an increased risk of fractures of the long bones, ribs, and pelvis. More than half of adolescents and adults with AD-HIES have had at least three fractures, often due to unrecognized or minor trauma. Scoliosis occurs in 75% of patients ≥16 years of age, and joint hyperextensibility affects ~70% of patients. Approximately half of individuals with AD-HIES have a high-arched palate, and retention of primary teeth due to failure of root resorption and lack of eruption of secondary teeth are characteristic dental manifestations. Several brain abnormalities have been described in patients with AD-HIES, including Chiari malformations, lacunar infarctions, and focal hyperintensities in white matter on T2-weighted MRI sequences. Development of coronary artery aneurysms during adulthood has also been reported. HIES is associated with an increased risk of non-Hodgkin lymphoma of B-cell origin. AR-HIES due to DOCK8 deficiency shares some features with AD-HIES, including highly elevated serum IgE levels, peripheral eosinophilia, chronic eczematous dermatitis (Fig. 60.9A), recurrent

HIES patients have markedly elevated serum levels of polyclonal IgE, usually peaking at >2000 IU/ml and sometimes declining during adulthood. Patients develop particularly high levels of anti-staphylococcal and anti-candidal IgE antibodies and often have immediate whealand-flare reactions to a variety of foods and environmental allergens. Many affected individuals also have eosinophilia of the peripheral blood and sputum. Cell-mediated immunity is often abnormal, as manifested by anergy to skin testing and impaired in vitro lymphoproliferative responses to specific antigens. Serum levels of IgG, IgA and IgM are usually normal in classic HIES, as are lymphocyte subsets. In contrast, AR-HIES due to DOCK8 deficiency features a combined immunodeficiency that is characterized by lymphopenia with a deficiency of CD4+ T cells > CD8+ T cells > B cells, low IgM levels, and variable IgG levels as well as elevated IgE levels and peripheral eosinophilia81,82. The infantile papulopustular eruption of HIES is characterized histologically by eosinophilic folliculitis, eosinophilic spongiosis, and a superficial and deep perivascular infiltrate with abundant eosinophils92,93.

Differential Diagnosis $

Fig. 60.9 Autosomal recessive hyperimmunoglobulin E syndrome (AR-HIES) due to DOCK8 deficiency. A Eczematous dermatitis with prurigo nodularis lesions. B Extensive molluscum contagiosum. C Numerous coalescing facial warts. A, B, Courtesy,  

Edward Cowen, MD.

%

&

Current diagnostic criteria for AD-HIES include an IgE level >1000 IU/ ml and a weighted score of five clinical features (Table 60.14)96; these characteristics plus a lack of Th17 cells or the detection of a heterozygous STAT3 mutation allow for a probable or definitive diagnosis, respectively. HIES must be differentiated from a number of other disorders that feature elevated IgE levels and a cutaneous eruption, including atopic dermatitis, Wiskott–Aldrich syndrome, Netherton syndrome, Omenn syndrome, DiGeorge syndrome, IPEX syndrome, and GVHD. Atopic dermatitis and Wiskott–Aldrich syndrome are most easily confused with HIES because they present with eczematous dermatitis and staphylococcal infections. However, the development of cold abscesses, recurrent pneumonia, coarse facial features, and osteopenia help to differentiate AD-HIES from these disorders, and platelet abnormalities distinguish Wiskott–Aldrich syndrome. In a series of pediatric patients who had a serum IgE level of >2000 IU/ml, 69% (48/70) had atopic dermatitis and only 8% (6/70) had HIES; no correlation was observed between the IgE level and diagnosis of HIES97. Elevated IgE levels, susceptibility to pyogenic infections, and eczematous dermatitis have also been described in patients with prolidase deficiency, an autosomal recessive condition due to PEPD mutations that also features chronic leg ulcers, facial dysmorphism, and intellectual disability. Patients with CGD and myeloperoxidase deficiency develop bacterial and candidal abscesses, but they do not typically have markedly elevated levels of IgE. In addition to DOCK8 deficiency and the other six conditions noted in Table 60.1, primarily immunodeficiencies that result in increased susceptibility to warts include epidermodysplasia verruciformis (see Ch. 79), Netherton syndrome (see Ch. 57), and activated phosphoinositide3-kinase δ syndrome (see Table 60.15) as well as deficiencies of serine/ threonine kinase 4 (STK4), GATA2 (see Table 60.13), TNF-like weak inducer of apoptosis (TWEAK; see Table 60.15), coronin 1A (see Table 60.16), RhoH GTPase, minichromosome maintenance complex component 4 (MCM4; also herpesvirus infections), and capping protein regulator and myosin 1 linker 2 (CARMIL2; also severe molluscum contagiosum). Of note, CD4+ lymphocytopenia can be a prominent feature of DOCK8 deficiency and other wart-prone immunodeficiency syndromes.

973

SECTION

Genodermatoses

9

DIAGNOSTIC GUIDELINES FOR HYPERIMMUNOGLOBULIN E SYNDROME (AD-HIES) DUE TO STAT3 MUTATIONS

Points Clinical finding

0

2

4

5

6

8

Multiplication factor

Pneumonias (X-ray proven, total #)

none

1

2



3

>3

2.5

Newborn papulopustular eruption (during first 3 weeks of life)

absent



present







2.1

Pathologic bone fractures

none



1–2





>2

3.3

Characteristic facies

absent

mild



present





3.3

High-arched palate

absent

present









2.5

Possible AD-HIES: IgE >1000 IU/ml plus weighted score of >30 Probable AD-HIES: As above plus lack of Th17 cells by peripheral blood flow cytometry or a family history of definitive AD-HIES Definitive AD-HIES: As above plus a dominant-negative heterozygous mutation in STAT3

Table 60.14 Diagnostic guidelines for autosomal dominant hyperimmunoglobulin E syndrome (AD-HIES) due to STAT3 mutations96.  

Treatment Treatment of the infectious complications of HIES includes incision and drainage of abscesses as well as therapeutic and prophylactic administration of antibiotics. Interferon-γ has been shown to help control infections, and IVIg may improve the dermatitis, prevent infections, and lower IgE levels. In anecdotal reports, treatment with omalizumab, a monoclonal antibody that targets IgE, improved the eczematous dermatitis of HIES.

IMMUNOGLOBULIN DEFICIENCIES Synonyms:  ■ X-linked agammaglobulinemia ■ Bruton

agammaglobulinemia ■ Bruton–Gitlin syndrome ■ Congenital hypogammaglobulinemia ■ X-linked hypogammaglobulinemia

Key features Agammaglobulinemia ■ The inheritance pattern is X-linked recessive in ~90% of patients and autosomal recessive in ~10% ■ Recurrent bacterial infections begin in the first few years of life Common variable immunodeficiency (CVID) ■ Heterogeneous group of disorders with defects in both humoral and cell-mediated immunity ■ May manifest during childhood or adulthood, with clinical onset at an average age of 30 years ■ Variable severity of infectious and autoimmune complications Selective IgA deficiency ■ Most common immunoglobulin deficiency, but usually asymptomatic, with clinical manifestations in only 10–15% of affected individuals ■ Bacterial sinopulmonary infections and autoimmune disorders may occur Hyper-IgM syndromes ■ Usually has an X-linked recessive inheritance pattern, but autosomal recessive forms also exist ■ Recurrent sinopulmonary and gastrointestinal infections with pyogenic bacteria and opportunistic organisms ■ Oral ulcerations and verrucae may develop

974

The most common immunoglobulin deficiency is selective IgA deficiency, overall found in ~1 in 500 persons with an equal sex distribution. Panhypogammaglobulinemia has a prevalence of 1 in 25 000, with X-linked agammaglobulinemia93 (affecting primarily boys) and common variable immunodeficiency98 (CVID; no sexual predilection)

representing the most frequent forms. CVID has its clinical onset at a mean age of 30 years whereas X-linked agammaglobulinemia often manifests during the first few years of life, after levels of maternal antibodies wane at ~6 months of age. Approximately 15% of patients with CVID have family members with selective IgA deficiency. The pathogenesis and clinical features of immunoglobulin deficiencies are presented in Fig. 60.10 and Table 60.1598–105. The treatment of hypogammaglobulinemia is antibody replacement by IVIg or subcutaneous immunoglobulins and antibiotic therapy for infections106. However, IVIg and other blood products containing IgA should be avoided in individuals with profound IgA deficiency, who may develop anti-IgA antibodies; fatal anaphylactic reactions have been reported. Recalcitrant non-infectious cutaneous and extracutaneous granulomas in patients with CVID may respond to treatment with TNF inhibitors. Female carriers of X-linked agammaglobulinemia may be detected via examination of B-cell X-inactivation patterns, which show skewing towards cells with inactivation of the mutated X chromosome. DNAbased prenatal diagnosis is possible when the genetic defect in affected family members has been identified.

IPEX SYNDROME Key features ■ X-linked recessive disorder due to mutations in FOXP3 ■ Cutaneous findings include a widespread eczematous dermatitis during infancy and a variety of autoimmune skin conditions ■ Also features enteropathy and endocrinopathies with autoimmune etiologies

IPEX – immune dysregulation, polyendocrinopathy, enteropathy, X-linked – syndrome is an X-linked recessive disorder caused by FOXP3 mutations that result in abnormal development of regulatory T cells. Affected individuals typically present during infancy with severe diarrhea secondary to autoimmune enteropathy and develop a variety of autoimmune endocrinopathies, e.g. early-onset type 1 diabetes mellitus, thyroiditis, cytopenias. Most IPEX patients have a widespread eczematous dermatitis and elevated IgE levels during early infancy, and this is often complicated by staphylococcal superinfections and sepsis. Cutaneous manifestations of IPEX can also include psoriasiform dermatitis, cheilitis, nail dystrophy, and autoimmune skin conditions such as alopecia areata, chronic urticaria, and bullous pemphigoid107. IPEX-like clinical presentations can occur in patients with IL-2 receptor α-chain (CD25) deficiency108, LPS-responsive beige-like anchor protein (LRBA) deficiency, gain-of-function STAT1 or STAT3 mutations, and loss-of-function STAT5B mutations (see Tables 60.4, 60.13, 60.15). In addition, an autosomal recessive disorder due to mutations in ADAM17, which encodes the TNF-α converting enzyme, features a

CHAPTER

60

PreNK

NK Thymus

$ Defects that primarily affect T-cell +/– natural killer (NK) cell development

ZAP70 TAP CD8

γc JAK3

CD8 IL-7Rα γc

IL-7Rα

Adenosine deaminase Purine nucleoside phosphorylase

++

CD3

**

++

CD45

RAG (Omenn) Artemis LIG4 NHEJ1

*

%

JAK3

__

__

CLP

MHCII

CD4

APRIL CD40L CD40

NEMO

NF-κB

B-cell

IgD

IgM

Pro

Pre

Autosomal recessive agammaglobulinemia: µ heavy chain Surrogate light chain (λ5) Igα,Igβ BLNK

BAFF

Deficiency leads to disruption

Pre-T-cell receptor

CD3

T-cell receptor

Hyper-IgM: CD40L CD40 AID UNG

C3d CD19 CR2

ICOSL ICOS CD4

IgA

IgG,E

IL-10 B

PC

CVID: ICOS

Common variable immunodeficiency (CVID): TACI BAFFR CD19

IgG,A,E

Igα

µ heavy chain

Immunoglobulin (Ig)

Subtypes of severe combined immunodeficiency

Antigen

Ig deficiencies

Surrogate light chain

Igβ

Antigenpresenting cell

B-cell lineage

CD4 T- or NKcell lineage

Chain switch recombination (CSR)

IgG,A,E

B

X-linked agammaglobulinemia: Bruton tyrosine kinase

Somatic hypermutation

Hypohidrotic ectodermal dysplasia with immunodeficiency: NEMO IκB-α

CD8

TACI

UNG

AID CSR†

&

CD4

BAFFR

Defects that affect both B-and T-cell development

Defects that primarily affect B-cell development

Primary Immunodeficiencies

MOLECULAR DEFECTS RESULTING IN IMMUNOGLOBULIN DEFICIENCIES AND SEVERE COMBINED IMMUNODEFICIENCY

Fig. 60.10 Molecular defects resulting in immunoglobulin deficiencies and severe combined immunodeficiency (SCID). *Also important for B-cell maturation in germinal centers. **Affects T cells more than B cells. †Switch from IgM to IgG, IgA or IgE. AID, activation-induced cytidine deaminase; APRIL, a proliferation-inducing ligand; BAFF(R), B-cell activating factor (receptor); BLNK, B-cell linker protein (binds Bruton tyrosine kinase); CD40L, CD40 ligand; CLP, common lymphoid precursor; CR2, complement receptor 2; γc, common γ chain; ICOS(L), inducible costimulator on activated T cells (ligand); IκB-α, inhibitor of κB-α; IL, interleukin; IL-7Rα, IL-7 receptor α-chain; MHC, major histocompatibility complex; NEMO, NF-κB essential modulator; NHEJ1, non-homologous end-joining 1 (Cernunnos); NK, natural killer cell; PC, plasma cell; TACI, transmembrane activator and CAML interactor; TAP, transporter associated with antigen processing; UNG, uracil-DNA glycosylase; −, double-negative thymocyte; ++, double-positive thymocyte.  

975

SECTION

Genodermatoses

9

PRIMARY IMMUNOGLOBULIN DEFICIENCY DISORDERS

Disorder

Gene

Protein (function)

Ig levels

Infectious and systemic B cells manifestations

Cutaneous manifestations

All ↓

↓↓



Block in B-cell differentiation at the pro-B- to pre-B-cell transition X-linked agammaglobulinemia

BTK

Bruton tyrosine kinase (pre-B-cell receptor [BCR] signaling)

AR agammaglobulinemia

IGHM

µ heavy chain of IgM (component of pre-BCR)

CD79A, CD79B

Igα chain, Igβ chain (bind µ heavy chain)

IGLL1

λ5 (surrogate light chain of pre-BCR)

BLNK

B-cell linker protein (binds Bruton tyrosine kinase)

LRRC8A

Leucine-rich repeatcontaining 8 family member A

AD agammaglobulinemia

Recurrent infections with Staphylococcus, Streptococcus, Pneumococcus, Haemophilus and Pseudomonas spp. • Hepatitis B and enteroviral infections • Lymphomas (~5%)



The skin is the most common site of infection - Furuncles and cellulitis - Ecthyma gangrenosum • Eczematous dermatitis • Papular dermatitis due to lymphohistiocytic infiltration • Non-infectious granulomas • Dermatomyositis-like disorder associated with chronic echoviral meningoencephalitis

Defective class switch recombination (e.g. from IgM to IgG, IgA or IgE), somatic hypermutation*, and related mechanisms Common variable immunodeficiency (CVID)†

Selective IgA deficiency

IgG,A ↓; ± IgM ↓

Nl or ↓



Bacterial sinopulmonary infections (organisms similar to X-linked agammaglobulinemia) • Giardia spp. gastroenteritis • Autoimmune diseases, especially hemolytic anemia and idiopathic thrombocytopenic purpura • Increased risk of cancer (10-fold overall) and lymphoma (400-fold)



See CVID section above

IgA ↓§; anti-IgA antibodies in ~half

Nl



Clinical manifestations in 10–15% • Similar to CVID



?

IgM ↓

Nl



Recurrent bacterial infections • Autoimmune diseases



Pneumonia, other bacterial infections • Thrombocytopenia, neutropenia



ICOS

Inducible costimulator on activated T cells (T-cell help for B-cell differentiation)

TNFRSF13B (AD or AR)

Transmembrane activator and CAML interactor (TACI; B-cell isotype switching)

TNFRSF13C

B-cell activating factor receptor (BAFFR; B-cell isotype switching)

CD19‡

CD19 antigen (B-cell survival and differentiation)

MSH5 (AD)

Mismatch repair protein (regulates class switch recombination)

LRBA (AR)

LPS-responsive beige-like anchor protein

TNFRSF13B (AD) MSH5 (AD)

Selective IgM deficiency

TWEAK deficiency

?

TWEAK

TNF-like weak inducer of apoptosis

IgM, A ↓

Nl



Pyodermas and mucocutaneous candidiasis • Extensive warts and dermatophyte infections • Eczematous dermatitis • Non-infectious granulomas (Fig. 60.11), which may also involve the lungs, liver and spleen • Autoimmune conditions such as vitiligo, alopecia areata and vasculitis • Clonal CD8+ lymphocytic infiltration of the skin • Clinical manifestations of LRBA deficiency variable; include an IPEX-like presentation (see text) and autoimmune lymphoproliferative syndrome (see Table 60.6) Mucocutaneous candidiasis • Eczematous dermatitis • Autoimmune conditions such as SLE, vitiligo and lipodystrophia centrifugalis abdominalis Extensive warts Eczematous dermatitis • SLE •

Warts

*† T-cell priming may also be defective, particularly in CD40–CD40L disorders (leading some authors to classify the latter as subtypes of severe combined immunodeficiency). 976

Relatively common, heterogeneous group of disorders characterized by decreased levels of at least two classes of immunoglobulins (IgG, IgA > IgM) and variable defects in T-cell function; currently, ≤10% of patients have an identifiable disease-causing mutation; several additional genes have also been associated with CVID104. ‡CD81 is required for CD19 expression, and a homozygous mutation in the CD81 gene was reported in a patient with hypogammaglobulinemia and autoimmune vasculitis. §Symptomatic patients often develop the immunodeficiency pattern of CVID.

Table 60.15 Primary immunoglobulin deficiency disorders. Conditions are autosomal recessive (AR) unless otherwise specified. AD, autosomal dominant; CAML, calcium-modulating cyclophilin ligand; Ig, immunoglobulin; Nl, normal; SLE, systemic lupus erythematosus.  

CHAPTER

Disorder

Gene

Protein (function)

Ig levels

Infectious and systemic B cells manifestations

Cutaneous manifestations

Block in B-cell differentiation at the pro-B- to pre-B-cell transition Activated PI3Kδ syndrome

PIK3CD, PIK3R1

Phosphoinositide3-kinase catalytic subunit δ (gainof-function) or regulatory subunit 1 (loss-of-function)

IgG/G2, A ↓; IgM ↑; also often CD4 lymphopenia

Nl or ↓



Recurrent sinopulmonary infections • Chronic EBV and CMV infections • LAN, HSM • Lymphoma • Autoimmune diseases, e.g. cytopenias • Growth retardation (PIK3R1)



X-linked hyper-IgM syndrome

CD40LG

CD40 ligand (on T cells)

Nl



CD40

CD40 (on B cells)

Recurrent sinopulmonary and GI infections with pyogenic bacteria and opportunistic organisms (e.g. PCP) • Neutropenia • Small lymph nodes • Autoimmune diseases, especially thyroiditis and hemolytic anemia



AR hyper-IgM syndromes

IgM ↑; isohemagglutinins ↑; IgA,E,G ↓↓

AICDA

Activation-induced cytidine deaminase





UNG

Uracil-DNA glycosylase

As above, but massive HSM/LAN (with germinal centers) and no opportunistic infections

IKBKG (NEMO) (X-linked recessive)

NF-κB essential modulator (activates NF-κB, which is involved in CD40 signaling)



IKBA (NFKBIA; AD, gain of function)

Inhibitor of κB-α (inhibits NF-κB)

Pyogenic bacterial and opportunistic infections • Subset of NEMO patients with osteopetrosis and lymphedema

Hypohidrotic ectodermal dysplasia with immunodeficiency

IgM ↑; ± IgA ↑ ; ± IgG ↓

NI



Staphylococcal abscesses, cellulitis • Severe/recurrent HSV and VZV infections, warts, molluscum contagiosum

Primary Immunodeficiencies

60

PRIMARY IMMUNOGLOBULIN DEFICIENCY DISORDERS

Pyodermas Extensive warts • Oral and anogenital ulcers • Non-infectious granulomas • Autoimmune conditions such as SLE •

Pyodermas

Pyodermas Ectodermal dysplasia (see Ch. 63)



Abnormal DNA methylation leading to defective B-cell negative selection and terminal differentiation Immunodeficiency, centromeric instability, and facial anomalies (ICF) syndrome

DNMT3B, ZBTB24

DNA methyltransferase 3β, zinc finger and BTB-containing 24

All ↓

NI or ↓



Bacterial sinopulmonary and GI infections • Abnormal facies, intellectual disability



CXC chemokine receptor 4 (binds CXCL12; key role in bone marrow homeostasis and lymphocyte trafficking)

IgG ↓; ± IgA,M ↓





Recurrent bacterial sinopulmonary infections • Myelokathexis (mature neutrophils fail to exit the bone marrow)



?

IgG,A ↓ (resolves by age 3 y)

Failure to thrive in infancy • Recurrent sinopulmonary and GI infections



Telangiectasias (uncommon) • Nevoid hyperpigmentation

Aberrant chemokine signaling WHIM syndrome¶

CXCR4 (AD, gain-of-function)

Cellulitis and pyodermas Extensive verruca vulgaris and condyloma acuminata (Fig. 60.12)



Delayed maturation of helper T-cell function Transient hypogammaglobulinemia of infancy

?

NI



Recurrent pyodermas and abscesses • Eczematous dermatitis

¶Warts, hypogammaglobulinemia, infections and myelokathexis; in a phase 1 trial, treatment with plerixafor (AMD 3100), a CXCR4 antagonist, led to higher neutrophil counts and improvement of

warts.

Table 60.15 Primary immunoglobulin deficiency disorders. (cont’d) Conditions are autosomal recessive (AR) unless otherwise specified. AD, autosomal dominant; GI, gastrointestinal; HSM, hepatosplenomegaly; HSV, herpes simplex virus; Ig, immunoglobulin; IKBKG, inhibitor of k light polypeptide gene enhancer in B cells, kinase g; LAN, lymphadenopathy; Nl, normal; PCP, Pneumocystis jiroveci pneumonia; SLE, systemic lupus erythematosus; VZV, varicella–zoster virus.  

977

SECTION

Genodermatoses

9

Fig. 60.11 Persistent granulomatous plaques in a patient with common variable immunodeficiency (CVID). Courtesy, Edward Cowen, MD.  

Fig. 60.13 Chronic ulcer in leukocyte adhesion deficiency type I. This 7-year-old boy was scratched by his sister, resulting in a large gaping wound that healed poorly. Reprinted with permission from Schachner L, Hansen R (eds). Pediatric  

Dermatology, 4th edn. London: Mosby, 2011.

lymphocytes to adhere to the vascular endothelium and migrate to sites of infection and tissue injury110,111.

Pathogenesis

Fig. 60.12 Extensive, recalcitrant perianal warts in a child with WHIM syndrome. Courtesy, Edward Cowen, MD.  

widespread psoriasiform dermatitis with pustular flares, brittle hair, staphylococcal skin infections, and chronic diarrhea109.

LEUKOCYTE ADHESION DEFICIENCY Key features ■ Group of autosomal recessive disorders characterized by decreased ability of leukocytes to adhere to the vascular endothelium and migrate to sites of tissue injury and infection ■ Gingivitis and periodontitis ■ Necrotic ulcerations clinically resembling pyoderma gangrenosum ■ Poor wound healing; delayed separation of the umbilical stump ■ Life-threatening bacterial and fungal infections

Introduction 978

Leukocyte adhesion deficiency (LAD) comprises three autosomal recessive disorders that affect the ability of neutrophils, monocytes, and

Leukocyte adhesion requires a group of cell surface integrins that share the 95-kDa β2-subunit known as CD18. This β2-subunit can be linked to different α-chains to form distinct cell surface glycoproteins including: (1) lymphocyte function antigen 1 (LFA-1; paired with CD11a); (2) complement receptor type 3 (CR3; iC3b receptor; Mac-1; paired with CD11b); and (3) p150,95 (complement receptor type 4; paired with CD11c). The primary ligand for these glycoproteins is intercellular adhesion molecule-1 (ICAM-1), which participates in the initiation and evolution of localized inflammation in the skin and other tissues (see Fig. 102.10). LAD-I is caused by mutations in ITGB2 which encodes CD18, and it manifests with dysfunction of all three glycoproteins. This leads to profound impairment of leukocyte firm adhesion to the vascular endothelium and mobilization into extravascular sites of inflammation, as well as defective neutrophil and monocyte chemotaxis and phagocytosis. LAD-II is due to mutations in the solute carrier family 35 member C1 gene (SLC35C1), which encodes the GDP-fucose transporter-1 (FUCT1) that is required for formation of sialyl-Lewis X, the fucosylated ligand for selectins on the surface of leukocytes112. This causes a defect in the initial steps of tethering and rolling of leukocytes on the endothelial cell surface via interaction of sialyl-Lewis X on leukocytes with E- or P-selectin on endothelial cells. These contacts are required for their targeting to sites of infection and inflammation. In order to undergo firm adhesion and subsequently extravasate from the bloodstream, circulating leukocytes must activate integrins in situ to rapidly increase their affinity and avidity for endothelial ligands. Patients with LAD-III have impaired integrin activation in hematopoietic cells, which leads to impaired leukocyte β1- and platelet β3-integrins in addition to leukocyte β2-integrins as in LAD-I. It is caused by lossof-function mutations in the fermitin family member 3 gene (FERMT3) that encodes kindlin-3, an effector of integrin activation in hematopoietic cells113.

Clinical Features The most common manifestation of LAD is gingivitis with periodontitis, which often leads to tooth loss and alveolar bone resorption and is thought to be related to excessive production of interleukin-17. Minor injuries to the skin may rapidly expand to form large, chronic ulcerations that can resemble “burnt out” pyoderma gangrenosum (Fig. 60.13). Poor wound healing also results in paper-thin, atrophic scars.

Pathology Individuals with LAD have marked peripheral blood neutrophilia (5–20 times normal levels). Although cutaneous ulcerations may resemble pyoderma gangrenosum clinically, histologic examination reveals a relative paucity of tissue neutrophils. Flow cytometric analysis reveals markedly decreased leukocyte CD18 expression in individuals with LAD-I. Patients with LAD-II have the Bombay red blood cell type due to a lack of the H blood group antigen, and those with LAD-III have abnormal platelet aggregation due to defective activation of β3-integrin and less often have anemia.

CHAPTER

Key features ■ Group of conditions characterized by defective function of both cell-mediated and humoral immunity ■ Recurrent infections, diarrhea, and failure to thrive within the first 3–6 months of life ■ Risk of GVHD, especially from unirradiated blood products ■ Lack of lymphoid tissue

Introduction Severe combined immunodeficiency (SCID) is a heterogeneous group of disorders that share clinical manifestations related to defective function of both cell-mediated and humoral immunity116–118 (Table 60.16).

Epidemiology SCID occurs in ~1 in 50 000 live births119, and three-quarters of affected patients are boys. Approximately 40% of cases have X-linked recessive inheritance, primarily due to defects in the gene encoding the common γ (γc) chain of the IL-2 receptor, while the remainder are autosomal recessive. Other relatively frequent causes of autosomal recessive SCID include deficiencies of adenosine deaminase (ADA), IL-7 receptor or JAK3, each accounting for 5–15% of cases119.

Pathogenesis Molecular defects that can lead to the SCID phenotype are presented in Fig. 60.10 and Table 60.16.

Differential Diagnosis

Clinical Features

A mutation in the gene encoding the Rac2 GTPase, which has a role in phagocyte NADPH oxidase activation as well as integrin-dependent adhesion and neutrophil migration, can lead to clinical features similar to those of LAD, including delayed separation of the umbilical stump, poor wound healing, neutrophilia, and recurrent perirectal abscesses with an absence of pus (see Tables 60.10 & 60.13).

Infants with SCID may present with widespread seborrheic-like dermatitis or morbilliform eruptions, often reflecting maternofetal GVHD. Cutaneous eruptions may also resemble lichen planus, acrodermatitis enteropathica, Langerhans cell histiocytosis, ichthyosiform erythroderma, and systemic sclerosis. Extensive eczematous dermatitis or exfoliative erythroderma, often associated with diffuse alopecia, may also occur in infants with Omenn syndrome, which also features lymphadenopathy, hepatosplenomegaly, chronic diarrhea, peripheral eosinophilia, leukocytosis, and elevated IgE levels in the setting of SCID (see Tables 10.2 and 60.16). Recurrent infections, chronic diarrhea, and failure to thrive are apparent within the first few months of life. Common early infections include mucocutaneous candidiasis, persistent viral gastroenteritis, and pneumonias due to bacteria, viruses, or P. jiroveci. Cutaneous infections are most often caused by C. albicans, S. aureus, and Str. pyogenes. Despite recurrent infections, patients with SCID typically lack tonsillar buds and palpable lymphoid tissue. SCID due to ADA deficiency is associated with an increased risk of developing dermatofibrosarcoma protuberans, often multiple and morpheaform, during the first two decades of life118.

Treatment Soft tissue infections in LAD patients require prolonged courses of antimicrobial therapy and, in some cases, surgical debridement. Meticulous dental hygiene is important in reducing the severity of the periodontitis. Granulocyte transfusions have potential benefit in LAD-I and -III, and oral administration of fucose may improve immune function in patients with LAD-II112. Healing of chronic ulcers following IVIg administration to a patient with LAD-I has been reported. Hematopoietic stem cell transplantation represents the only definitive therapy for LAD, but it is limited by infectious complications and GVHD. Two patients with severe LAD-I were treated without prior conditioning with an infusion of autologous hematopoietic stem cells that had been corrected ex vivo with a retroviral vector encoding CD18, but circulating CD18+ cells persisted for 4 cm. CALMs may not be apparent at birth and frequently become more noticeable during the first year of life; fading of these lesions during later adulthood has also been described37. When located within areas of dermal melanocytosis, CALMs may be surrounded by a rim of normally pigmented skin (see Ch. 112). Larger CALMs, especially those with associated hypertrichosis, should be palpated to exclude the possibility of an underlying plexiform neurofibroma (see below). Crowe et al.4 reported that 10% of the normal population has one to five CALMs, and Burwell et al.38 found that 26% of 732 white schoolchildren had at least one CALM >1 cm in diameter. In the latter study, ≥6 CALMs were found in only three children (0.4%) and they were siblings with a parent who had NF1. For the clinical diagnosis of NF1, a minimum of six CALMs is required to meet the specificity of this criterion (Tables 61.3 and 61.4). To avoid confusion with lentigines, CALMs must be >5 mm in prepubertal individuals and >15 mm in postpubertal individuals in order to satisfy this diagnostic criterion for NF1. In its fullest expression, NF1 can manifest with thousands of neurofibromas in an affected individual, hence the appellation

CHAPTER

Cutaneous Neurofibromas (60–90%) Café-au-lait macules (>90%) • Axillary and/or inguinal freckling (~80%) • Plexiform neurofibroma (25%) • Nevus anemicus (30–50%) • Juvenile xanthogranuloma (15–35% in first 3 years of life) • •

Ocular Lisch nodules (~90% by 20 years of age) Choroidal nodules (>80% of adults) • Neovascular glaucoma, retinal vasoproliferative tumors • •

Skeletal Cranial Macrocephaly (20–50%) Hypertelorism (25%) • Sphenoid wing dysplasia (5 mm in prepubertal individuals and >15 mm in postpubertal individuals • Two or more neurofibromas of any type or one plexiform neurofibroma • “Freckling” in the axillary or inguinal regions • Optic gliomas • Two or more Lisch nodules (iris hamartomas) • Osseous lesion, such as sphenoid wing dysplasia or thinning of long bone cortex, with or without pseudarthrosis • First-degree relative (parent, sibling or offspring) with NF1 by the above criteria •

Table 61.3 NIH diagnostic criteria for neurofibromatosis type 1. Updated diagnostic criteria including recently recognized manifestations (e.g. nevus anemicus, choroidal nodules) and NF1 gene testing are under development. When a multistep, comprehensive analysis of the NF1 gene is performed (see text), an underlying mutation can be detected in ≥95% of non-founder patients who fulfill these diagnostic criteria.  

Spinal Scoliosis (5–10%) Spina bifida

• •

Limbs Dysplasia of long bone cortex (5%), pseudarthrosis (2%)



Other Generalized osteopenia (~50%), osteoporosis (~20%) Short stature (~30% 95% of patients have missense mutation (Met918Thr) in substraterecognition pocket

Thyroid: medullary carcinoma§ Adrenal: pheochromocytoma (50% bilateral) GI: Diffuse ganglioneuromatosis (megacolon, diverticulosis) Medullated corneal nerve fibers Marfanoid habitus Reduced subcutaneous fat High-arched palate Flat nasal bridge Pectus excavatum Proximal myopathy Other: Bilateral pes cavus, high patella, scoliosis, kyphosis, lordosis, joint laxity Rare: Cushing syndrome

Multiple mucosal neuromas, especially eyelid margins, conjunctivae, lips, anterior tongue > gingiva, palate, nasal and laryngeal mucosa Increased nerve fibers in normal skin Prominent, everted lips Everted eyelids Hyperpigmentation around mouth and overlying small joints of hands and feet CALM Circumoral lentigines Hypertrichosis, synophrys Rare: multiple neuromas of perinasal skin

MEN type (synonyms)

Mode of inheritance

Gene locus

1 (Wermer syndrome)

AD

11q13

2A (MEN type 2, Sipple syndrome)

AD

2B (MEN type 3, multiple mucosal neuroma syndrome)

AD

*† A tumor suppressor gene.

Rearranged during transfection of proto-oncogene; mutations in the same gene can be responsible for Hirschsprung disease and familial medullary thyroid carcinoma.

‡Induce dimerization and activation of receptor in the absence of its ligand. §Screen via measurement of serum calcitonin level after calcium or pentagastrin injection. ¶Onset usually prior to medullary thyroid carcinoma.

Table 63.2 Types of multiple endocrine neoplasia (MEN). A rare fourth type of MEN (MEN 4), caused by mutations in cyclin-dependent kinase inhibitor 1B (CDKN1B) and characterized by pituitary and parathyroid tumors, has been described; familial medullary thyroid carcinoma can result from NTRK1 mutations as well as RET mutations. A woman with medullary thyroid carcinoma, macular amyloidosis, and multiple cutaneous neuromas in a widespread distribution (overlapping features of MEN 2A and MEN 2B) with a RET mutation in codon 768 has also been reported. AD, autosomal dominant; CALM, café-au-lait macules; NTRK1, neurotrophic tyrosine kinase receptor type 1.  

1028

vascular anomalies of CS and BRRS tend to be multifocal, fast-flow lesions with intramuscular involvement and associated ectopic fat16. A distinctive “PTEN hamartoma of soft tissue” that presents as a subcutaneous and intramuscular mass with adipocytic, fibrous, and vascular (arterial, venous) components and sometimes lymphoid, bony, and neural elements has also been described17. Lastly, recent series have suggested that CS patients may have a slightly increased risk of melanoma, with a lifetime incidence of ~5%7.

Oral lesions of CS appear as 1–3 mm, asymptomatic, mucosa-colored papules that often lead to a cobblestone appearance (Fig. 63.3B). They have a predilection for the lips and tongue, but extensive involvement of the entire oral cavity can occur15.

Extracutaneous manifestations Multinodular goiter or thyroid adenomas occur in more than two-thirds of patients with CS, and the lifetime risk of thyroid carcinoma is

CHAPTER

Clinical manifestations

Onset typically at birth or in childhood Mucocutaneous

Pigmented macules of genitalia (glans and shaft of penis, vulva) Lipomas Vascular anomalies* PTEN hamartoma of soft tissue (see text) Neuromas (facial, acral, mucosal) Epidermal nevi Café-au-lait macules

Craniofacial and skeletal

Macrocephaly Down-slanting palpebral fissures Frontal bossing High-arched palate, long philtrum Pectus excavatum Joint hyperextensibility Hand and foot abnormalities§

Onset typically in adolescence or adulthood Multiple facial papules†

Multiple oral papillomas (lips, tongue)‡ Sclerotic fibromas Inverted follicular keratoses Multiple acrochordons Acanthosis nigricans

Goiter and/or adenomas Carcinoma (follicular form over-represented)

Breast

Fibrocystic disease Virginal hypertrophy Ductal papillomas Fibroadenomas Adenocarcinoma Hepatic vascular anomalies

Genitourinary system

Acral/palmoplantar keratoses Scrotal tongue Perioral pigmented macules (rare)

Scoliosis, kyphoscoliosis

Thyroid

Gastrointestinal tract

Variable onset

63 Other Genodermatoses

CLINICAL MANIFESTATIONS OF PTEN HAMARTOMA TUMOR SYNDROME AND SCREENING RECOMMENDATIONS

Adenocarcinoma (rare)

Multiple polyps (usually 97th %ile; 58 cm in adult women, 60 cm in adult men) • Lhermitte–Duclos disease (LDD; in an adult) • Breast cancer • Endometrial cancer (epithelial) • Thyroid cancer (follicular) • Gastrointestinal (GI) hamartomas, including ganglioneuromas, but not hyperplastic polyps (≥3) •

Kalman Watsky, MD; B, Courtesy, Jean L Bolognia, MD.

Minor criteria Vascular anomalies, including multiple intracranial developmental venous anomalies • Lipomas (≥3) • Testicular lipomatosis • Autism spectrum disorder • Mental retardation (IQ ≤75) • Renal cell carcinoma • Colon cancer • Esophageal glycogenic acanthosis • Thyroid cancer (papillary or follicular variant of papillary) • Thyroid structural lesions (e.g. adenoma, multinodular goiter) •

$

Operational diagnosis in an individual: 3 major criteria including macrocephaly, LDD, or GI hamartomas –or– 2 major criteria + 3 minor criteria Operational diagnosis when a family member meets diagnostic criteria or has a PTEN mutation: 2 major criteria –or– 1 major + 2 minor criteria –or– 3 minor criteria

Table 63.4 Revised clinical diagnostic criteria for PTEN hamartoma tumor syndrome (2013). Adapted from reference 12. A scoring system incorporating age and clinical findings has also been developed to estimate a patient’s risk of having a PTEN mutation52.  

%

estimated to be 10 to >30%. Fibrocystic disease and fibroadenomas of the breast affect three-quarters of female patients. Breast carcinoma develops in up to 85% of female patients with CS and is diagnosed at a mean age of approximately 40 years7,18; it has also been reported in affected men19. Multiple polyps may be found anywhere in the gastrointestinal tract but most frequently affect the colon (≥85% of patients). The lifetime risk of colon carcinoma is estimated to be ~10%12,18. Benign ovarian cysts and uterine leiomyomas commonly develop and endometrial carcinoma occurs in as many as 20–30% of women with CS12,18. The lifetime risk of renal carcinoma is estimated to be as high as ~30%18.

Pathology Histologically, tricholemmomas are characterized by a lobular proliferation of pale keratinocytes, often in association with a hair follicle. Basal keratinocytes are oriented to form a palisade, and hyperkeratosis can lead to a cutaneous horn. Demonstration of complete loss of PTEN expression within a tricholemmoma via immunohistochemical staining is suggestive that the patient has CS20. Histologically, some facial papules in patients with CS may simply be squamous papillomas, while others show follicular infundibular hyperplasia. Oral lesions often represent fibromatous nodules with collagen fibers arranged in whorls. On biopsy, extrafacial and palmoplantar papules tend to be hyperkeratotic papillomas, and they may have changes reminiscent of verrucae or acrokeratosis verruciformis21.

Differential Diagnosis 1030

The clinical differential diagnosis of the oral papillomas of CS includes verrucae, focal epithelial hyperplasia (Heck disease), traumatic fibromas,

Fig. 63.4 Cowden syndrome. Multiple palmar keratoses, many of which have a glassy appearance. A few have a central depression. Courtesy, Joyce Rico, MD.  

Treatment Although the recognition of CS and other forms of PHTS is based upon clinical and histologic evaluation, genetic testing can help to confirm the diagnosis and facilitate identification of affected family members. Due to the high risk of malignancy, cancer surveillance is a critical part of PHTS management (see Table 63.3). Agents that downregulate the mTOR pathway, such as sirolimus (rapamycin), represent promising therapeutic approaches for PHTS that are currently under investigation, with reports of improvement of infiltrative vascular anomalies and lipomatosis following treatment25,26. The facial papules of CS respond variably to topical 5-fluorouracil, oral isotretinoin, curettage, laser ablation, or surgical excision13,27.

GARDNER SYNDROME Synonym:  ■ Familial polyposis of the colon

Key features ■ Autosomal dominant disorder characterized by premalignant intestinal polyposis and adenocarcinoma of the gastrointestinal tract ■ Extraintestinal manifestations include epidermoid cysts, osteomas, desmoid tumors and fibrous tumors (skin, mesentery, retroperitoneum) ■ Congenital hyperpigmentation of the retinal pigment epithelium (CHRPE) is an early sign ■ Caused by mutations in the APC (adenomatous polyposis coli) gene

CHAPTER

History In 1953, Gardner and Stephens described a large family in which many individuals had multiple cutaneous lesions, osteomatosis and fatal bowel cancer. The syndrome now bears Gardner’s name.

Epidemiology The incidence of GS is approximately 1 in 8000 to 1 in 16 000 births. It is inherited as an autosomal dominant trait with high penetrance and variable expressivity, affecting men and women equally.

Pathogenesis

63 Other Genodermatoses

mucosal neuromas of MEN 2B, papillomas of Goltz syndrome, and papular lesions of lipoid proteinosis. A combination of acral keratoses (including palmoplantar) plus oral and facial papules can also be seen in Darier disease, whereas multiple facial angiofibromas and gingival fibromas are characteristic of tuberous sclerosis. These disorders can usually be differentiated from CS by other characteristic features as well as histologic evaluation. The clinical differential diagnosis of multiple facial tricholemmomas may include angiofibromas (as seen in tuberous sclerosis or MEN 1), trichoepitheliomas, and fibrofolliculomas (Birt–Hogg–Dubé syndrome); in addition to their histologic features, the tendency of tricholemmomas to have a verrucous appearance clinically may help to distinguish them from these lesions. Common warts, seborrheic keratoses, basaloid follicular hamartoma syndrome, and epidermodysplasia verruciformis may represent additional diagnostic possibilities. Less commonly, multiple syringomas or the basal cell nevus syndrome might be considered (see Fig. 111.5). Germline mutations in the SDHB/C/D genes, which encode subunits of mitochondrial succinate dehydrogenase, have been associated with an autosomal dominant CS-like disorder characterized by a predisposition to the development of breast, thyroid, and renal carcinomas; to date, cutaneous manifestations have not been described22. Predisposition to the same malignancies as well as endometrial carcinoma has been associated with germline epigenetic alteration in the KLLN gene, which encodes a p53-regulated DNA replication inhibitor23. One study found that ~10% of patients with a CS-like disorder but no PTEN or SDHB/C/D mutations had a germline mutation in PIK3CA or AKT124, which encode proteins that activate mTOR signaling (see Fig. 55.3); cutaneous findings such as tricholemmomas and lipomas were noted in a few affected individuals.

GS is caused by heterozygous germline mutations in the adenomatous polyposis coli (APC) tumor suppressor gene. The APC gene encodes a protein that downregulates the Wnt/β-catenin signaling pathway, which has important functions in cellular proliferation, differentiation and adhesion (see Fig. 55.6).

Clinical Features Cutaneous and soft tissue manifestations Skin lesions and bony abnormalities appear during childhood and adolescence, frequently preceding the onset of polyposis. Cutaneous epidermoid cysts affect ~30–50% of patients with GS and are often multiple. These lesions are commonly found on the head and neck, may be present at birth, and tend to increase in size and number and then stabilize. Multiple familial pilomatricomas have also been reported as a presentation of GS30. Desmoid tumors are non-encapsulated, non-metastasizing, locally aggressive benign tumors that occur in 10–20% of patients with GS. There is a marked female predominance (70% to 85%). Desmoid tumors may occur spontaneously or at incision sites, arising from musculo-aponeurotic soft tissues. They commonly develop after colectomy and most often arise within the abdominal wall or intraabdominally, with the latter causing greater morbidity via obstruction of the small bowel and/or ureters. Extra-abdominal lesions affecting the shoulder girdle, chest wall, or inguinal region can also occur. Although cytologically benign, desmoid tumors can be locally aggressive and may lead to substantial morbidity and even mortality. Hereditary desmoid disease characterized by multiple desmoid tumors, often at unusual sites, in patients with few or no colonic polyps has been described in association with APC mutations31. Fibromas may occur in the skin, subcutaneous tissues, mesentery, or retroperitoneum. The “Gardner fibroma” often arises in the first decade of life, favors the back and paraspinal region, and can serve as a desmoid precursor. Lipomas, leiomyomas, trichoepitheliomas, neurofibromas, and ovarian cysts are observed less commonly.

Other extraintestinal manifestations Congenital hypertrophy of the retinal pigment epithelium (CHRPE) is evident in ~75% of patients with GS and can be an early sign of the disorder32 (Fig. 63.5). Because CHRPE is present at birth and easily detected by ophthalmologic examination, it is a useful finding in

Fig. 63.5 Congenital hypertrophy of the retinal pigment epithelium. Courtesy, L  

Tychsen, MD.

Introduction The main features of Gardner syndrome (GS) are premalignant intestinal polyposis, epidermoid cysts, osteomas, and desmoid or fibrous tumors of the skin and other sites. It is considered to represent a phenotypic variant of the familial adenomatous polyposis syndrome with prominent extraintestinal involvement28,29.

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SECTION

Genodermatoses

9

patients who do not yet have other manifestations. While unilateral solitary CHRPE may occur in unaffected individuals, multiple and bilateral lesions represent a sensitive and specific marker for GS. There are rare reports of adenocarcinoma arising from CHRPE. Osteomas occur in ~80% of patients and favor the mandible and maxilla, although they can develop in other bones of the skull and in long bones. Seen in children as young as 8 years of age, osteomas are painless and may grow large enough to be clinically obvious or they may be detectable only by radiographic studies. Other skeletal lesions include exostoses, endostoses, and cortical thickening of the long bones. Dental anomalies are seen in ~20% of patients with GS and include supernumerary teeth, odontomas, unerupted teeth, and multiple caries. Patients with GS are at increased risk for the development of other tumors, including papillary carcinoma of the thyroid (particularly in women), hepatoblastoma (usually affecting children less than 3 years of age), pancreatic and biliary tract carcinomas, adrenal adenomas (or occasionally carcinomas), and various sarcomas (e.g. fibrosarcoma, osteosarcoma). The association of brain tumors (most often medulloblastomas) with adenomatous polyposis in patients with heterozygous APC mutations has historically been referred to as Turcot syndrome type 2. The latter is distinct from the constitutional mismatch repair deficiency syndrome (previously referred to as Turcot syndrome type 1) that presents during childhood with brain tumors (primarily glioblastomas), colonic polyposis, hematologic malignancies, and multiple café-au-lait macules due to biallelic mutations in mismatch repair genes (see below and Table 61.4)33.

Gastrointestinal manifestations In adults, the diagnosis of GS is commonly made when the patient presents with gastrointestinal bleeding secondary to adenomatous polyps. Other findings may include anemia, abdominal pain, diarrhea or constipation, and weight loss. Premalignant adenomatous polyps most commonly occur in the colon but are also found in the small intestine and stomach in over half of patients. Polyps are typically extremities)41. Sebaceous adenomas are the most common tumor type, and they present as yellow papules or nodules numbering from one to hundreds42,43. Keratoacanthomas, which are keratotic skin-colored to erythematous papules or nodules that arise quickly, are seen in ~25% of patients with MTS and may exhibit sebaceous differentiation. The most frequently observed malignancies are colorectal (61%) and genitourinary (22%; endometrium, ovary, urinary tract) carcinomas44. Colorectal carcinoma in MTS most often involves the proximal colon and develops at a median age of 50 years, about one decade before colorectal carcinoma typically occurs in the general population. In addition, MTS patients can develop breast carcinomas (6%); hematologic malignancies (11%); head and neck cancers (5%); and neoplasms of the small intestine (3%), stomach, or pancreas45. The diagnosis of MTS is based on the presence of at least one sebaceous tumor (or keratoacanthoma with sebaceous differentiation) and a visceral malignancy in the absence of any known predisposing factor. In the absence of a sebaceous tumor, the diagnosis can be made in a patient with multiple keratoacanthomas, multiple visceral malignancies, and a family history of MTS. Findings that suggest a higher or lower likelihood of MTS in patients with sebaceous neoplasms are summarized in Table 63.546. Testing for a mismatch repair gene mutation is helpful for confirming the diagnosis and facilitating early identification and surveillance of affected family members.

Immunohistochemical (IHC) staining for MSH2, MSH6, MLH1, and PMS2 can be a valuable screening tool for MTS-associated tumors, which frequently show a lack of expression of one or more of these mismatch repair proteins (see Table 63.5)42,44,49. However, abnormal IHC staining is sometimes seen in sporadic sebaceous neoplasms, especially in immunocompromised patients; conversely, IHC staining is occasionally normal in lesions from patients with a mismatch repair gene mutation (see Ch. 111)49,50. PCR-based assays can also be used to demonstrate microsatellite instability (MSI) in tissue from MTSassociated neoplasms. Confirmatory testing for a germline mismatch repair gene mutation should be considered in patients with abnormal lesional IHC staining for these proteins, evidence of MSI, or a strong clinical suspicion of MTS.

Sebaceous hyperplasia is a common finding in normal individuals and sebaceous adenomas and carcinomas can occur in patients without MTS. Sebaceous adenomas and carcinomas as well as colorectal carcinomas and other malignancies have been described in patients with autosomal recessive colorectal adenomatous polyposis caused by mutations in the MUTYH base excision repair gene35. Multiple keratoacanthomas may occur as an isolated finding (i.e. without visceral malignancy), especially in patients with the Ferguson–Smith (multiple

RISK ASSESSMENT FOR MUIR–TORRE SYNDROME (MTS)

Higher likelihood of MTS

Lower likelihood of MTS

Clinicopathologic characteristics of skin lesions ≥2 sebaceous neoplasms [2] Located outside of the head and neck region • Sebaceous neoplasm with high specificity for MTS, e.g. a cystic lesion or seboacanthoma

Single sebaceous neoplasm Located in photodamaged facial skin • Sebaceous hyperplasia









Characteristics of patient and family history Age 95%, although the clinical benefits remain to be determined; a low-protein diet in conjunction with this medication may help to prevent excessively high plasma tyrosine levels54,56.

BIOTINIDASE AND HOLOCARBOXYLASE SYNTHETASE DEFICIENCIES Synonym:  ■ Late- and early-onset forms of multiple carboxylase deficiency

Key features ■ As biotin is an essential cofactor for carboxylases, there is overlap in these two autosomal recessive disorders ■ Cutaneous findings include alopecia and periorificial erythema and erosions, features of “nutritional dermatitis” ■ Metabolic acidosis occurs in both disorders ■ Biotinidase deficiency is associated with developmental delay, hearing loss, and seizures beginning during infancy or childhood, while patients with holocarboxylase synthetase deficiency classically develop encephalopathy and hypotonia within the first 3 months of life

CHAPTER

63 Other Genodermatoses

CLINICAL FEATURES OF ALKAPTONURIA

Biotinidase deficiency and holocarboxylase synthetase deficiency are genetically distinct autosomal recessive disorders that result in multiple carboxylase deficiency; the former has its onset during infancy or childhood, while the latter presents during the first 3 months of life. Dermatologic features, which overlap with other forms of “nutritional dermatitis” (see Fig. 51.13), occur in >50% of patients with biotinidase deficiency and a smaller proportion of those with holocarboxylase synthetase deficiency57,58. Characteristic skin findings include progressive alopecia and a well-demarcated dermatitis with erythema and scaling that typically begins in perioral, perianal and acral regions, but then can become generalized. This eruption is often eroded or fissured, and superimposed candidiasis may develop. Biotinidase deficiency, a pan-ethnic disorder with an incidence of approximately 1 in 60 000 births, represents a defect in biotin recycling. Patients with this disorder become functionally biotin-deficient under conditions of normal dietary biotin intake. Since biotin is an essential cofactor for the activity of carboxylases, multiple carboxylase deficiency ensues. The clinical manifestations of the disorder, although entirely preventable with the administration of 5–20 mg of biotin daily, are highly variable and may go unrecognized. This has led to the inclusion of biotinidase deficiency in the newborn screening panel of a number of countries, including the US58. Both cutaneous and extracutaneous manifestations usually develop between 3 months and 2 years of age but may be delayed until later childhood. Extracutaneous features include developmental delay, hearing loss, seizures, conjunctivitis, optic atrophy, myelopathy, and metabolic acidosis. Abnormalities on urine organic acid analysis are not consistently present. The diagnosis is established by an assay of biotinidase activity in blood; prenatal diagnosis is possible via enzymatic and molecular analyses. Holocarboxylase synthetase deficiency is significantly less common than biotinidase deficiency. It represents a defect in biotinylation of the apocarboxylases, leading to a failure in synthesis of intact functional holocarboxylases. Patients typically present within the first 3 months of life with symptoms of a metabolic encephalopathy, including poor feeding, lethargy, respiratory distress, and hypotonia. Metabolic acidosis, hyperammonemia, and organic aciduria are often observed. Definitive diagnosis is established by assays of carboxylases in leukocytes or cultured skin fibroblasts; prenatal diagnosis is also possible via enzymatic and molecular analyses. Most patients exhibit significant improvement when treated with 10 mg of biotin daily.

FABRY DISEASE Synonym:  ■ Anderson–Fabry disease

Key features ■ X-linked disorder due to a deficiency of α-galactosidase A ■ Characteristic mucocutaneous finding is multiple angiokeratomas ■ Additional features include pain and paresthesias of the extremities, hypohidrosis, and renal and coronary insufficiency

Fabry disease is an X-linked lysosomal storage disorder resulting from a defect in glycosphingolipid metabolism59. It is a pan-ethnic disorder affecting ~1 in 40 000 men. Female heterozygotes may also be affected, although their clinical manifestations vary and often have a later onset. Fabry disease is caused by mutations in GLA, which encodes the enzyme α-galactosidase A. This leads to systemic deposition of neutral glycosphingolipids, predominantly globotriaosylceramide and galabiosylceramide. The clinical manifestations result primarily from the accumulation of glycosphingolipids within the vascular endothelium of various organs and tissues, which leads to ischemia and infarction. Fabry disease classically presents during childhood or adolescence with the cardinal clinical features of acral pain, acral paresthesias, hypohidrosis, and angiokeratomas (Fig. 63.9). Characteristic whorled corneal opacities (“cornea verticillata”) are also evident in ~75% of both male hemizygotes and female heterozygotes by childhood or adolescence; posterior lenticular opacities and tortuous retinal or conjunctival

1035

SECTION

Genodermatoses

9

CLINICAL FEATURES OF FABRY DISEASE AND FUCOSIDOSIS

Cerebrovascular disease

*

Corneal opacities

**

Coarse facial features Hypertrophic cardiomyopathy§, arrhythmias, coronary insufficiency Hypohidrosis§

Neurologic deterioration/ developmental delay Retinal vascular abnormalities Hearing loss Sinopulmonary infections Cough, dyspnea Organomegaly

Increased sweat chloride Renal insufficiency Pain and paresthesias

Abdominal pain, diarrhea, vomiting Maltese crosses (lipid globules)

Angiokeratomas

Osteopenia, joint pain Dysostosis multiplex Pain and paresthesias = Fabry disease only = Fucosidosis only no box = Both

Fig. 63.9 Clinical features of Fabry disease and fucosidosis. *Also lenticular in Fabry disease. **Milder in Fabry disease. §Occasionally observed in fucosidosis.  

Angiokeratomas of Fabry disease, courtesy, Luis Requena, MD; photomicrograph of urinary sediment demonstrating Maltese crosses (via polarization), courtesy, Robert J Desnick, MD PhD.

1036

vessels may also be observed. However, these early findings can be subtle or absent in atypical variants of Fabry disease with delayed onset. With increasing age, progressive renal insufficiency develops, leading to the need for dialysis or transplantation by the fourth or fifth decade of life in most male patients. Cardiac sequelae such as hypertrophic cardiomyopathy, arrhythmias, valvular abnormalities, and coronary insufficiency occur in most affected men by middle age and represent the most common cause of premature death in both men and women with Fabry disease. Manifestations in other organ systems can include: transient ischemic attacks and strokes; abdominal pain, diarrhea, and vomiting (especially in children); obstructive lung disease; joint pain and osteopenia; and hearing loss59,60. Characteristic facial features such as periorbital fullness, bushy eyebrows, a broad nasal bridge, thick lips, prognathism, and prominent earlobes have been noted in men with Fabry disease. Angiokeratomas are one of the earliest signs of Fabry disease, typically beginning to appear during childhood or adolescence61–63. They develop in most male patients and ~30% of female heterozygotes. Angiokeratomas present as punctate, dark-red to blue–black macules or papules (Fig. 63.10). The lesions do not blanch with pressure and may become slightly keratotic as they enlarge. The angiokeratomas of Fabry disease, referred to as angiokeratoma corporis diffusum, tend to be concentrated between the umbilicus and the knees but can develop at any cutaneous site (see Fig. 63.10); oral and conjunctival lesions are also seen. Less frequent vascular findings include linear telangiectasias favoring the face, lips, and oral mucosa; episodic acral vasospasm resembling Raynaud phenomenon, typically accompanied by pain and paresthesias; and peripheral edema and lymphedema62,63. Hypohidrosis is an early and almost constant feature of Fabry disease that can result in heat intolerance. Decreased body hair has also been described.

Histologically, angiokeratomas are composed of dilated capillaries in the uppermost dermis, partially enclosed by elongated rete ridges (see Ch. 114); hyperkeratosis may be seen in older lesions. In the skin, there is evidence of lipid storage in endothelial cells, pericytes, arteriolar smooth muscle, and arrector pili muscle. This can be detected by a lipid stain such as Sudan black B, or highlighted by periodic acid Schiff (PAS) staining. Lipid accumulation may also be observed in sweat gland epithelium (see Ch. 39) and perineural cells. Ultrastructural examination demonstrates characteristic cytoplasmic inclusions in all of these cell types. The diagnosis of Fabry disease can be established by demonstration of deficient α-galactosidase A activity in plasma, leukocytes, or cultures of amniocytes or chorionic villi obtained from prenatal testing. However, enzyme activity is within the normal range in up to a third of female heterozygotes. Analysis of the GLA gene is clinically available and can be helpful in: (1) determining disease status in female patients; (2) predicting disease severity in affected male patients; and (3) establishing a prenatal/preimplantation diagnosis. Polarizing microscopy of urine from Fabry disease patients reveals birefringent lipid globules (“Maltese crosses”)60 (see Fig. 63.9). Although most commonly seen in association with Fabry disease, angiokeratoma corporis diffusum can also be observed in several other lysosomal storage disorders, as outlined in Table 63.764–70. Scrotal and vulvar angiokeratomas are also commonly found in older adults (see Ch. 114). Enzyme-replacement therapy with recombinant agalsidase-α or β is available (the latter is FDA-approved) and is administered biweekly by intravenous infusion. Accumulated data indicate that it is effective in arresting progression of the disorder, especially when initiated early in the disease process71–73. Current guidelines recommend considering enzyme-replacement therapy in all symptomatic patients, and at 8–10 years of age in asymptomatic boys with classic loss-of-function GLA mutations73. Recent controlled studies found that treatment with migalastat, an oral pharmacologic chaperone that stabilizes specific mutant forms of α-galactosidase, may reduce renal glycosphingolipid accumulation, left ventricular hypertrophy, and gastrointestinal symptoms in Fabry disease patients with suitable mutations73a,73b. Other interventions include gabapentin or carbamazepine for neuropathic pain and angiotensin-converting enzyme inhibitors to reduce proteinuria.

FUCOSIDOSIS Key features ■ Autosomal recessive disorder due to deficiency of α-fucosidase ■ Multiple angiokeratomas of the skin and oral mucosa ■ Extracutaneous findings include coarse facial features, dysostosis multiplex, and progressive mental and motor deterioration Fucosidosis is a rare autosomal recessive lysosomal storage disorder resulting from mutations in FUCA1, which encodes the enzyme α-fucosidase. In the past, patients were classified into two groups: type I, a more severe form with onset in the first year of life; and type II, a milder form with onset in the second year or later67. However, a continuous spectrum of severity is now recognized. The extracutaneous manifestations include coarse facial features, growth retardation, organomegaly, dysostosis multiplex, and neurologic deterioration with associated hypomyelination (see Fig. 63.9). Patients may also have corneal opacities, retinal vascular abnormalities, and frequent sinopulmonary infections. Angiokeratomas virtually indistinguishable from those associated with Fabry disease are found in approximately one-third of fucosidosis patients M

M=F

Birth

Other Genodermatoses

63

1043

SECTION

Genodermatoses

9

NUCLEAR ENVELOPATHIES

Primary feature and associated diseases

Inheritance

Laminopathies – due to mutations in the LMNA gene which encodes the lamin A and C proteins of the nuclear membrane lamina* Premature aging and/or cutaneous sclerosis Hutchinson–Gilford progeria syndrome (classic and atypical)

AD

Restrictive dermopathy†

AD > AR

“Atypical Werner syndrome”

AD

Other progeroid laminopathies

AD > AR

Skeletal dysplasia and/or arthropathy Mandibuloacral dysplasia†

AR

Arthropathy, tendinous calcinosis and progeroid features

AR

Lipodystrophy Dunnigan familial partial lipodystrophy

AD

Generalized lipodystrophy with pubertal onset‡

AD

Muscular dystrophy Emery–Dreifuss muscular dystrophy

AD > AR

Limb-girdle muscular dystrophy type 1B

AD

Early-onset myopathy with progeroid features

AD

Cardiomyopathy Dilated cardiomyopathy type 1A

AD

“Heart–hand syndrome”

AD

Neuropathy Charcot–Marie–Tooth type 2B1

AR

Cutaneous disorders with inner nuclear membrane dysfunction – due to mutations in the LEMD3 gene, whose protein product associates with lamin A Cutaneous sclerosis and/or skeletal dysplasia Buschke–Ollendorff syndrome

AD

Osteopoikilosis

AD

Melorheostosis

Type 2 segmental§

*Heterozygous mutations in the LMNB2 gene, which encodes the lamin B2 protein of the

nuclear membrane lamina, can cause “acquired” partial lipodystrophy (Barraquer–Simons syndrome). †Can also result from recessive mutations in the ZMPSTE24 gene, which encodes a zinc metalloproteinase involved in the processing of prelamin A into mature lamin A (see Fig. 63.13); mandibuloacral dysplasia often presents with progeroid features and lipodystrophy. ‡Overlaps with atypical Werner syndrome; numerous whitish, fibrotic papules on a background of diffuse hyperpigmentation have been described in some patients. §Germline heterozygous mutation (resulting in Buschke–Ollendorff syndrome or osteopoikilosis) with a presumed second hit in area of melorheostosis.

Table 63.10 Nuclear envelopathies. A heterogeneous group of genetic disorders that share the common findings of cutaneous fibrosis and bone dysplasia. Néstor–Guillermo progeria syndrome (see Table 63.9) is also characterized by abnormalities in the nuclear membrane lamina; this autosomal recessive disorder results from mutations in the barrier-toautointegration factor 1 gene (BANF1), which encodes a protein that interacts with prelamin A (and progerin). AD, autosomal dominant; AR, autosomal recessive.  

1044

the first year of life90,92,93,101. Weight gain is very slow, with marked loss during episodes of illness. Linear growth proceeds at half the normal pace and does not undergo the normal acceleration around puberty. Sexual maturation is absent in most patients, and affected individuals have both short stature and a low weight for height. Following the onset of growth failure, the skin becomes thin and dry, with less hair than normal. Some areas may appear taut and shiny, whereas others (especially the fingers and toes) lax and wrinkled. At

birth or during early infancy, some patients have thick, inelastic, scleroderma-like skin, usually on the lower abdomen, flanks, thighs, and buttocks. Infantile fat is rapidly lost with the onset of growth failure, resulting in prominent superficial veins and the appearance of perioral cyanosis. As the aged appearance progresses, irregular brown pigmentation becomes evident in sun-exposed areas. At the onset of growth failure, patients begin to develop characteristic facial features, including a disproportionately large cranium, frontal bossing, a large open anterior fontanelle, pronounced scalp veins, prominent eyes due to relatively slow growth of the facial bones, a thin beaked nose with a sculpted appearance, and micrognathia. The facial stigmata tend to become marked by age 2 to 3 years, giving a “pluckedbird” appearance. Alopecia develops during the first year of life and becomes diffuse and generalized, with later hair growth tending to be fine and lightly pigmented. Eyebrows and eyelashes are often sparse or absent. Although the nails may be normal, dystrophy in the form of small, short and thin nails is common. Marked delay in the eruption of primary and secondary dentition has also been noted in most patients. Teeth may be crowded, rotated, overlapped and maloccluded, and the voice tends to be high-pitched and piping. Truncal features include a narrow pyriform thorax, shoulders with thin and short clavicles, and prominent thoracic kyphosis giving a stooped appearance. Prominence of the abdomen (relative to the chest) and hypoplastic nipples also contribute to the distinctive habitus. The limbs are usually proportionate and become progressively thinner with increasing prominence of the joints, especially the knees, elbows, and small joints of the hand. Coxa valga is usually present by age 2 to 3 years and, in combination with increasing joint stiffness, contributes to a wide-based gait. Patients are of normal intelligence and may be self-conscious about their appearance. Early onset of progressive coronary and cerebral atherosclerosis results in a median lifespan of 14 years102. Other complications include osteopenia, low-frequency conductive hearing loss, corneal dryness, and hyperopia92. Although mild insulin resistance occurs in up to half of patients, overt diabetes mellitus is rare.

Pathology and Laboratory Findings Cutaneous histopathology varies with the site and the age of the patient, and it is usually not helpful in diagnosing the condition103,104. The epidermis is fairly normal with minimal hyperkeratosis and a slight increase in melanin in the basal cell layer. Although dermal elastic tissue is normal, dermal collagen tends to be thickened and hyalinized. Adnexal structures are normal or decreased in density and arrector pili muscles are usually prominent. Radiographic findings include hypoplasia of the facial bones, thinned cranial bones, open fontanelles, and hypoplasia of the mandible with crowding of the teeth. Progressive resorption of bone from the distal phalanges of the fingers and toes is also characteristic, but not diagnostic, of HGPS.

Differential Diagnosis The differential diagnosis is outlined in Table 63.9 and includes Werner syndrome, “atypical Werner syndrome”, Néstor–Guillermo progeria syndrome, metageria, and acrogeria105. In contrast to HGPS, patients with Werner syndrome have premature canities, cataracts and an increased incidence of malignancy. HGPS should also be distinguished from the following disorders: Cockayne syndrome (Ch. 87), Rothmund–Thomson syndrome (Ch. 87), ataxia–telangiectasia (Ch. 60), Kindler syndrome (Ch. 32), Wiedemann–Rautenstrauch syndrome (neonatal progeroid syndrome), and forms of Ehlers–Danlos syndrome and cutis laxa with progeroid features (Ch. 97). Lastly, clinical overlap may be seen with other disorders that are due to mutations in the LMNA gene, such as early-onset myopathy with progeroid features, restrictive dermopathy (Ch. 34), and mandibuloacral dysplasia (see Table 63.10).

Treatment Management is directed toward the prevention and treatment of complications, particularly cardiovascular, cerebrovascular, and musculoskeletal. No dietary regimen has been shown to alter the disease

WERNER SYNDROME Synonym:  ■ Progeria of the adult

Key features ■ Occurs in 1 in 1 million births, with a higher incidence in Japan ■ Autosomal recessive disorder due to mutations in the gene RECQL2 (WRN) that encodes a DNA helicase ■ Premature aging with the appearance of canities, cataracts, osteoporosis, diabetes mellitus and atherosclerosis during the second decade ■ Additional features include sclerodermoid changes, keratoses and ulcerations over bony prominences, short stature, and vascular and soft tissue calcification ■ Similar facies to progeria patients, with a pinched appearance and micrognathia ■ Increased risk of meningiomas, sarcomas, and (particularly in Japanese patients) thyroid carcinomas and melanomas

Introduction Werner syndrome is a genetic disorder of accelerated aging with an onset in the second decade of life. This rare progeroid syndrome has a higher incidence in certain populations in Japan110–114. Although it is often referred to as progeria of the adult, Werner syndrome has some distinctive clinical findings not normally associated with aging, such as hypogonadism, laryngeal atrophy, and osteosclerosis of the distal extremities110–113. The discovery of underlying mutations in the RECQL2 (WRN) gene has allowed investigation into the molecular aspects of Werner syndrome111.

History In 1904, Otto Werner described a family with two brothers and two sisters between the ages 36 and 40 years who displayed clini-

cal features of premature aging. In 1934, Oppenheimer and Kugel reported two similar cases and established the eponym Werner syndrome.

Epidemiology Werner syndrome is a rare autosomal recessive disorder with an overall incidence of 1 in 1 million births. However, its incidence in Japan is higher and may approach 1 in 3500 in some communities owing to high rates of consanguinity. It was the study of several large Japanese families that led to identification of the gene responsible for this disorder113. Werner syndrome has been reported in all races and affects both sexes equally.

CHAPTER

63 Other Genodermatoses

course. Although growth impairment in HGPS is not typically related to growth hormone deficiency, administration of exogenous growth hormone may increase weight and, to a lesser degree, height. Physical and occupational therapy can help to maintain joint mobility, and patients and families may benefit from psychological and genetic counseling. Because farnesylation of the dominant-mutant progerin form of prelamin A causes it to be anchored to the nuclear membrane, thereby disrupting nuclear structure (see Fig. 63.13), inhibitors of farnesylation were identified as a potential treatment for HGPS. Initial studies found that administration of farnesyltransferase inhibitors (FTIs) restored normal nuclear morphology to human HGPS fibroblasts in vitro, and these inhibitors improved body weight, bone density, strength, and survival in mouse models of progeria97,106. Additional investigation in mouse models showed benefit from treatment with the combination of a bisphosphonate and statin, which inhibit farnesyl pyrophosphate synthase and HMG-CoA reductase, respectively. Each of these enzymes functions in the protein prenylation pathway essential to both farnesylation and the alternative pathogenic geranylgeranylation that occurs in the setting of FTI monotherapy. Treatment of HGPS patients with the FTI lonafarnib, either alone or together with the bisphosphonate zoledronate and pravastatin, has been shown to result in small but significant increases in survival102,107. Other possible therapies being explored in preclinical studies include aminopyrimidines that modulate farnesylation, antisense oligonucleotides to reduce progerin production, rapamycin to increase autophagic degradation of progerin, inhibition of isoprenylcysteine carboxyl methyltransferase to mislocalize progerin away from the nuclear rim, resveratrol to restore sirtuin-1 deacetylase activity and prevent stem cell depletion, vitamin D to potentially reduce progerin production, and remodulin to inhibit N-acetyltransferase-10 and rescue nuclear shape108,109,109a.

Pathogenesis Werner syndrome is caused by mutations in the RECQL2 (WRN) gene, which encodes a homolog of the Escherichia coli RecQ DNA helicase. Almost all of the mutations identified to date predict a truncated protein, and over half of Japanese patients are homozygous for a specific splice-site mutation111. The Werner protein (WRN) has both exonuclease and helicase activities, and it plays a role both in optimizing DNA repair, particularly via base excision, and in suppressing illegitimate recombination. Therefore, loss of RecQ helicase results in genomic instability. The accumulation of senescent cells with decreasing replicative capacity and an increasing number of mutations is thought to lead to the clinical findings of premature aging and an increased risk of malignancy. Decreased heterochromatin stability is also thought to play a role in the accelerated cellular senescence of Werner syndrome as well as physiologic aging115. Loss of function of the RECQL2 gene may occur in the normal population as a function of age111. A subset of patients have “atypical Werner syndrome” and lack pathogenic changes in the RECQL2 gene. Rather, they have heterozygous missense mutations in the LMNA gene (see HGPS section) that affect the heptad repeat region and are predicted to interfere with protein– protein interactions116. Compared to patients with RECQL2 mutations, those with atypical Werner syndrome tend to have an earlier onset of disease and more severe age-related manifestations. Atypical Werner syndrome might therefore be better classified as a late-onset form of HGPS.

Clinical Features In most affected individuals, growth progresses normally until the beginning of the second decade, when short stature and thin limbs become noticeable. Graying of the hair may first appear during childhood but characteristically develops in late adolescence or the early twenties. Other findings of Werner syndrome become evident during the second and third decades of life110–113. The typical patient is short, with an average height of 5 ft (1.5 m), and has spindly limbs but central obesity. The hands and feet are small, and the face is thin with a pinched appearance, prominent eyes, a beaked nose, circumoral radial furrows, taut lips, protuberant teeth and micrognathia (Fig. 63.14). The voice is high-pitched and raspy. Cutaneous changes include atrophy (epidermal, dermal and subcutaneous), scale, mottled hyperpigmentation and tightness reminiscent of scleroderma. These findings are most prominent on the face, forearms, hands, legs and feet. Nails may be dystrophic, hypoplastic or absent, and plantar hyperkeratosis is common. Thick keratoses develop over pressure points such as the fingers, toes, ankles, elbows and, occasionally, the ears. Removal of these keratoses by accidental or deliberate trauma leaves painful progressive ulcers. Ulcers may be resistant to therapy and prone to infection because of ischemia related to peripheral vascular disease. Dystrophic soft tissue calcification and osteomyelitis can also complicate chronic ulcers. Other characteristic findings in Werner syndrome that reflect accelerated aging include bilateral cataracts, type 2 diabetes mellitus, hyperlipidemia, generalized atherosclerosis and osteoporosis. Additional features not normally associated with aging include hypogonadism, laryngeal atrophy, and osteosclerosis of the extremities. Affected individuals have an increased risk of meningiomas, soft tissue sarcomas, and osteosarcoma. Japanese patients are also at increased risk for

1045

SECTION

9

Fig. 63.14 Werner syndrome. Characteristic features include a beaked nose, taut skin, prominent veins, and micrognathia. Courtesy,

Genodermatoses



Ronald P Rapini, MD.

Peter H. Itin, Alanna F. Bree and Virginia P. Sybert

Key features ■ These genetic disorders share the central feature of abnormalities in at least two of the major ectodermally derived structures – hair, teeth, nails, and sweat glands ■ Other ectodermal structures, such as mucous and sebaceous glands, as well as non-ectodermally derived structures may also be affected ■ Different forms of ectodermal dysplasia are distinguished based on the types of ectodermal abnormalities, associated non-ectodermal anomalies, and mode of inheritance, as well as the underlying genetic defect ■ Some inherited abnormalities limited to one ectodermal structure (e.g. hair, nails) have a genetic basis related to that of ectodermal dysplasias, e.g. hypodontia due to heterozygous WNT10A mutations versus ectodermal dysplasia syndromes due to biallelic mutations in the same gene

thyroid carcinomas and melanomas, especially in acral and mucosal locations114. The average lifespan is approximately 50 years, and death is usually related to cardiovascular and cerebrovascular disease. Some authors have postulated that heterozygous carriers may have higher rates of malignancy and myocardial infarction than the general population111,112.

Pathology and Laboratory Findings The epidermis is hyperkeratotic and atrophic, with focal hypermelanosis of the basal layer. Appendages are decreased in number and atrophic, and there is fibrosis and variable hyalinization of the dermis. The fat is also atrophic and often replaced by hyalinized connective tissue. Vessels may show changes typical of diabetic angiopathy.

Differential Diagnosis A clinical diagnosis can usually be made when the characteristic premature canities, dysmorphic facies, skin findings, and body habitus are recognized. However, there is considerable overlap with the recently described mandibular hypoplasia, deafness, progeroid features and lipodystrophy (MDPL) syndrome caused by mutations in the POLD1 gene encoding DNA polymerase δ (see Table 63.9)117, which interacts with the Werner helicase during DNA replication and repair. However, MDPL is differentiated by frequent hearing impairment, absence of cataracts, and no predisposition to malignancy. In addition to other premature aging syndromes outlined in Table 63.9, Werner syndrome must be distinguished from ataxia–telangiectasia (see Ch. 60), prolidase deficiency (which features facial dysmorphism, telangiectasias, recalcitrant leg ulcers, and premature canities), and disorders associated with plantar keratoderma and scleroderma-like skin changes, such as Huriez syndrome (see Ch. 58).

Treatment

1046

ECTODERMAL DYSPLASIAS

Genetic counseling should be provided, and prenatal diagnosis can be offered to affected families. Skin ulcers may prove resistant to therapy and should be treated aggressively and early, with skin grafting occasionally necessary. Case reports have suggested that etidronate may ameliorate painful soft tissue calcifications. Management of diabetes mellitus and hyperlipidemia with proper diet and appropriate medications (e.g. pioglitazone, sitagliptin, lipid-lowering agents) can help to reduce complications, including atherosclerosis. Vitamin C supplementation was found to reverse age-related metabolic abnormalities and increase the lifespan in a mouse model of Werner syndrome, suggesting that vitamin C might be beneficial for Werner syndrome patients118.

Ectodermal dysplasias have long been recognized as a distinct group of inherited disorders that affect ectodermal appendages. Early descriptions of affected individuals were made by Danz in 1792, Wedderburn in 1838, and Darwin in 1875. The term “hereditary ectodermal dysplasia” was subsequently introduced by Weech in 1929. Currently, over 180 single-gene disorders qualify as ectodermal dysplasias by having abnormalities in two or more of the major ectodermal structures – hair, teeth, nails, and sweat glands; other ectodermal structures, such as sebaceous and mucous glands, can also be affected119,120. Some of the conditions included in this group have not been traditionally thought of as ectodermal dysplasias because they are recognized and diagnosed based upon another primary manifestation such as keratoderma, ichthyosis, aplasia cutis congenita, or skeletal dysplasia. It has been suggested that defects in ectodermal appendages should be the major clinical features used to classify and diagnose ectodermal dysplasias. There have been many classification schemes proposed over the years, including a descriptive clinical categorization by Pinheiro and Freire-Maia121, a clinical–genetic model by Priolo and Lagana122, and a functional classification by Lamartine123. Over the past two decades, the molecular basis of many ectodermal dysplasias has been elucidated, and we are beginning to understand the processes of cell signaling involved in the induction and development of ectodermal structures as well as their interactions with mesodermal structures119,124. International conferences were held in 2008 and 2012 with the aim of developing a classification system for ectodermal dysplasias that integrates clinical, genetic, and functional/pathway-based data and is fluid enough to incorporate new discoveries125,126. Tables 63.11, 63.12 and 63.13 summarize the key clinical and genetic features of ectodermal dysplasias with a known molecular basis and/or prominent cutaneous manifestations. Selected classic ectodermal dysplasias are discussed in detail in this chapter.

HYPOHIDROTIC ECTODERMAL DYSPLASIA Synonyms:  ■ Anhidrotic ectodermal dysplasia ■ Christ–Siemens– Touraine syndrome

Hypohidrotic ectodermal dysplasia (HED) refers to a group of disorders that share the following features: sparse or absent hair; missing or pegshaped teeth; and decreased ability to sweat. The most common form is X-linked, and traditionally the term HED has referred to this condition. However, clinically similar conditions with autosomal dominant and autosomal recessive inheritance can result from molecular defects that affect the same pathway as in X-linked HED.

CHAPTER

Hypohidrotic ED–immune deficiency

Hypohidrotic ED*

Hidrotic ED

Witkop tooth and nail syndrome

Inheritance (associated gene)

XL† (EDA); AD, AR (EDAR > EDARADD)

XL recessive (IKBKG/NEMO); AD (NFKBIA)

AD (GJB6)

AD (MSX1)

Protein product

Ectodysplasin A; EDAR; EDARADD

NF-κB essential modulator; NF-κB inhibitor-α

Connexin 30

Muscle segment homeobox 1

Scalp hair

Sparse to absent; often lightly pigmented in children

Sparse

Wiry, brittle; patchy alopecia; often lightly pigmented

Normal to thin

Teeth

Hypodontia, conical

Hypodontia, conical

Normal

Hypo- or anodontia of secondary teeth; primary teeth normal or small/ peg-shaped

Sweating

Markedly decreased

Mildly decreased

Normal

Normal

Nails

Normal

Normal

White and small during infancy; thickened, distal separation

Koilonychia improves with age; toenails worse than fingernails

Other

Characteristic facies; neonates may have collodion-like membrane; eczema common; thick nasal secretions and cerumen; frequent respiratory tract infections

Intertrigo, seborrheic-like dermatitis, erythroderma; colitis; recurrent infections (pyogenic or opportunistic); ↑ IgM and IgA, ↓ IgG; rare osteopetrosis and lymphedema, arthritis, and/or (esp. in AD form) autoimmune cytopenias and endocrinopathy

Stippled palmoplantar keratoderma; grid-like array of tiny acral papules; blepharitis, conjunctivitis

Prolonged retention of primary teeth

Other Genodermatoses

63

CLASSIC ECTODERMAL DYSPLASIAS

*† WNT10A mutations can also lead to a hypohidrotic ED phenotype (see Table 63.13 and text).

In female patients, clinical manifestations vary considerably and may have a mosaic pattern (see text).

Table 63.11 Classic ectodermal dysplasias. AD, autosomal dominant; AR, autosomal recessive; ED, ectodermal dysplasia; EDAR, ectodysplasin A receptor; EDARADD, EDAR-associated death domain; GJB6, gap junction β6; IKBKG, inhibitor of κ light polypeptide gene enhancer in B cells, kinase γ; XL, X-linked.  

p63-RELATED ECTODERMAL DYSPLASIA SYNDROMES

AEC*

EEC

Limb–mammary

ADULT

Inheritance

AD

AD

AD

AD

Typical TP63 mutations

Missense in SAM domain

Missense in DNA-binding domain

Truncating in C-terminal region†

Missense in hotspot at end of DNA-binding domain†,‡

Scalp hair

Lightly pigmented, wiry; sparse with patchy alopecia

Lightly pigmented, coarse; may be sparse

Normal

Lightly pigmented, sparse; frontal alopecia

Teeth

Hypodontia, misshapen (e.g. conical) teeth

Hypodontia, enamel hypoplasia

Hypodontia

Hypodontia, small teeth

Sweating

Hypohidrosis in some patients

Usually normal

Hypohidrosis in some patients

Usually normal

Nails

Hyperconvex, thickened or absent

Transverse ridges, pitting

Variable dystrophy

Ridges, pitting

Cleft lip/palate

Almost 100%; palate ± lip

~50%; usually lip + palate

~30%; palate only

None

Digital anomalies

Syndactyly in some patients; rarely ectrodactyly

Ectrodactyly > syndactyly

Ectrodactyly > syndactyly

Ectrodactyly, syndactyly

Skin findings

Neonatal erythroderma; erosive dermatitis, esp. of scalp; flexural reticulated hyperpigmentation

Xerosis, palmoplantar keratoderma

None

Xerosis, photosensitivity, freckling

Other

Ankyloblepharon; lacrimal duct defects; ectopic breast tissue; hypospadias; GER

Lacrimal duct defects; keratopathy, corneal scarring; GU anomalies

Lacrimal duct defects, hypoplastic nipples/breasts; GU anomalies

Lacrimal duct defects; hypoplastic nipples/breasts

*† Rapp–Hodgkin syndrome is now included within the AEC spectrum.

May also be caused by missense mutations in the proline-rich domain.

‡This mutation is thought to constitutively activate a transactivation domain.

Table 63.12 p63-related ectodermal dysplasia syndromes. TP63 mutations also occur in subsets of autosomal dominant (AD) non-syndromic split-hand/foot malformation (SHFM) and isolated cleft lip/palate. ADULT, acro-dermato-ungual-lacrimal-tooth; AEC, ankyloblepharon–ectodermal defects–cleft lip/palate; EEC, ectrodactyly–ectodermal dysplasia–clefting; GER, gastroesophageal reflux; GU, genitourinary; SAM, sterile alpha motif.  

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SECTION

Genodermatoses

9

OTHER SELECTED ECTODERMAL DYSPLASIAS WITH CUTANEOUS MANIFESTATIONS AND A KNOWN MOLECULAR BASIS

Cranioectodermal dysplasia (Sensenbrenner syndrome)

Nectinopathies: cleft lip/palate ED (CLPED), ED-syndactyly (EDS)

ED, ectrodactyly and macular dystrophy (EEM)

Odontoonychodermal dysplasia*

Tricho-dentoosseous syndrome

Ellis–van Creveld syndrome

“Pure” hair–nail type ED

Inheritance (associated gene)

AD (DLX3)

AR (EVC, EVC2)

AR (IFT122, WDR35, WDR19, IFT43)

AR (PVRL1 [CLPED], PVRL4 [EDS])

AR (CDH3)

AR (WNT10A)

AR (KRT85, KRT74, HOXC13)

AR (ORAI1)

Protein product

Distal-related homeobox 3

EVC and EVC2 (limbin)

Intraflagellar transport proteins

Nectin 1 (CLPED), nectin 4 (EDS)

Cadherin 3 (P-cadherin)

WNT10A

Keratin 85 or 74, homeobox C13 transcription factor

ORAI calcium release-activated calcium modulator 1

Scalp hair

Kinky (may straighten with age)

Normal

Thin, sparse

Brittle, sparse; involves eyebrows and eyelashes; pili torti; progressive alopecia

Sparse; involves eyebrows and eyelashes

Thin, sparse; involves eyebrows and eyelashes

Sparse to absent; fragile; involves eyebrows and eyelashes

Normal

Teeth

Small, widely spaced; thin enamel with pits; taurodontism (elongated pulp chamber)

Neonatal teeth; hypodontia; delayed eruption

Small, widely spaced; hypodontia; enamel defects, abnormally shaped

Hypodontia; peg-shaped teeth

Small, widely spaced

Hypodontia; small teeth

Normal

Defective enamel

Sweating

Normal

Normal

Normal

Normal

Normal

Hyperhidrosis of palms and soles; occasionally hypohidrosis

Normal

Hypohidrosis

Nails

Brittle

Dystrophic

Short, broad, thin

Dystrophic (variable)

Normal

Dystrophic or absent

Dystrophic; fragile, irregular distal ends

Normal

Other

Dolichocephaly, frontal bossing, increased bone density

Shortlimbed dwarfism, skeletal dysplasia; congenital heart defects

Lax, redundant skin; short proximal limbs, brachydactyly, narrow thorax; dolichocephaly, frontal bossing; nephronophthisis

Cleft lip/palate (CLPED); PPK (esp. CLPED); partial cutaneous syndactyly (EDS > CLPED)

Macular dystrophy; syndactyly, ectrodactyly

Facial telangiectasias, reticulated erythema, “atrophy”; xerosis, follicular keratoses; PPK; smooth tongue

Follicular papules on scalp

Recurrent severe infections, myopathy

Immunodeficiency, myopathy and ED

*Allelic with Schöpf–Schulz–Passarge syndrome, which has an overlapping phenotype but also features eyelid hidrocystomas and PPK with histologic evidence of eccrine syringofibroadenomas. In

addition, approximately 15% of patients with a hypohidrotic ED phenotype have WNT10A mutations, with milder manifestations in heterozygotes. Multiple milia, adnexal neoplasms (e.g. poromas, tumors of the follicular infundibulum), basal cell carcinomas, and pili annulati have also been described in patients with WNT10A mutations.

Table 63.13 Other selected ectodermal dysplasias with cutaneous manifestations and a known molecular basis. A recently described AR ectodermal dysplasia (ED) syndrome due to mutations in the grainyhead-like 2 gene (GRHL2) features nail dystrophy/loss, hypodontia with enamel hypoplasia, marginal PPK, keratoses on the dorsal hands and feet, and oral hyperpigmentation126. Another rare AR ED, SOFT syndrome – short stature, onychodysplasia, facial dysmorphism, and hypotrichosis – is caused by mutations in the POC1A gene, which encodes a centriolar protein. Naegeli–Franceschetti–Jadassohn syndrome and dermatopathia pigmentosa reticularis are discussed in Ch. 67 and epidermolysis bullosa simplex skin fragility syndromes with ED are discussed in Ch. 32. AD, autosomal dominant; AR, autosomal recessive; PVRL1, poliovirus receptor-related 1; PPK, palmoplantar keratoderma.  

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The X-linked form of HED is estimated to affect 0.5–2 in 10 000 liveborn boys and occurs in all racial and ethnic groups. The autosomal dominant and recessive forms are much less common.

Pathogenesis HED is caused by mutations in genes that affect the ectodysplasin signal transduction pathway127 (Fig. 63.15). Epithelial cells in the developing tooth, hair follicle and eccrine gland utilize this pathway during morphogenesis, and errors in signaling result in aplasia, hypoplasia or dysplasia of these structures. Activation of the ectodysplasin pathway at a critical time during development leads to translocation of the NF-κB transcription factor into the nucleus of these epithelial cells, thereby altering the expression of a variety of target genes. The change

ECTODYSPLASIN SIGNAL TRANSDUCTION PATHWAY Hypohidrotic ectodermal dysplasia XL

EDA

AD, AR

EDAR

AD, AR

EDARADD TRAF6

TAB2

TAK1 Hypohidrotic ectodermal dysplasia with immunodeficiency

+

*

NEMO

IκB Kinase

XLR

Ub Ub

Ub

P

IκB

AD

**

in gene expression likely has an effect on both cellular proliferation and survival128. The gene that is altered in the X-linked form of HED (EDA) codes for a soluble ligand, ectodysplasin A. It is secreted by a subset of epithelial cells and binds to its receptor (ectodysplasin-A receptor; EDAR) on another group of epithelial cells. Mutations in EDAR cause either autosomal recessive or autosomal dominant HED129. Autosomal recessive and autosomal dominant HED can also be caused by mutations in the EDARADD (EDAR-associated death domain) gene, which encodes an intracellular adapter protein that assists in transducing the signal from the activated receptor to the nucleus130. Molecular analysis of the EDA, EDAR, and EDARADD genes is available in commercial laboratories.

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63 Other Genodermatoses

Epidemiology

Clinical Features Affected newborns may present with a collodion-like membrane or with marked skin scaling. Scalp hair is sparse to absent (Fig. 63.16), and, when present, is usually lightly pigmented. Hair may darken at puberty and secondary sexual hairs are typically normal, although body hair is usually sparse or absent. Most male patients are unable to sweat to a detectable degree131. This can lead to elevation of the core temperature in warm environments or with exertion, and symptomatic hyperthermia is a major problem. Affected infants often present with fever of unknown origin, and hyperthermia during the first few years of life can be fatal when HED is not recognized131,132. The skin is smooth and dermatoglyphics may be effaced because of absent eccrine pores. Atopy is a major cause of morbidity, with eczema affecting nearly two-thirds of HED patients. Periorbital wrinkling and hyperpigmentation are common. Sebaceous hyperplasia of the face, clinically resembling milia, can develop over time (see Fig. 63.16D). The nails are usually normal. Both the primary and secondary dentition are affected. Teeth may be absent or reduced in number and abnormally shaped (e.g. peg-shaped). Affected individuals typically have an alteration in their facial appearance characterized by a saddle nose, full everted lips and frontal bossing (see Fig. 63.16). Nasal secretions and cerumen are thick and viscous, and recurrent respiratory tract infections are common. The voice is frequently hoarse or raspy. Affected infants often develop gastroesophageal reflux and feeding problems. Unilateral or bilateral amastia is an occasional feature. Female patients with the X-linked form of HED fall into one of three categories: (1) carriers with no detectable clinical features; (2) limited involvement with findings such as decreased hair density, one or more peg-shaped or missing teeth, patchy distribution of sweat glands along the lines of Blaschko, and relative hyperpigmentation of the skin that lacks adnexa (most evident on the back); or (3) full-blown features of the disorder (Fig. 63.17). This variability results from the random nature of X-inactivation (see Ch. 62).

Pathology A skin biopsy is usually not necessary, but a scalp or palmar biopsy specimen lacking eccrine structures is considered diagnostic of HED133. Microscopic examination of hairs often shows small or variable shaft diameters and parallel dark bands of various lengths resembling a “bar code”134.

NF κB Genes

TRAF6, TNF receptor-associated factor 6 TAK1, transforming growth factor β-activated kinase 1 TAB2, TAK1-binding protein 2 IκB, inhibitor of κB Ub, ubiquitin

Fig. 63.15 The ectodysplasin signal transduction pathway. *Allelic with incontinentia pigmenti. **A hypermorphic mutation in the gene encoding lκBα that prevents this protein’s phosphorylation (and subsequent ubiquitination/ degradation) can result in continued inhibition of NF-κB and a phenotype of hypohidrotic ectodermal dysplasia with immunodeficiency. AD, autosomal dominant; AR, autosomal recessive; EDA, ectodysplasin A; EDAR, EDA receptor; EDARADD, EDAR-associated death domain adapter protein; NEMO, NF-κB essential modulator (also known as IKBKG, inhibitor of κ light polypeptide gene enhancer in B cells, kinase γ); XL(R), X-linked (recessive). Additional details of NEMO function are in Fig. 62.4.  

Differential Diagnosis The majority of affected individuals, either male or female, have the X-linked form. In sporadic cases, molecular diagnosis may be helpful. Homozygous or compound heterozygous mutations in the WNT10A gene can give rise to an HED phenotype without associated facial dysmorphism, in addition to causing odonto-onycho-dermal dysplasia and Schöpf–Schulz–Passarge syndrome135 (see Table 63.13 and Fig. 55.6). Heterozygous WNT10A mutations also represent a common etiology of mild HED or isolated hypodontia. At birth, HED can be confused with an ichthyosis if a collodion-like membrane is present (see Ch. 57, Table 57.3). Recurrent fevers in an infant may lead to consideration of infectious diseases before the features of HED are recognized. HED with immune deficiency (HED-ID) due to mutations in the IKBKG (NEMO) gene can be differentiated by the clinical and laboratory features of the associated immune system abnormalities (see below).

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Fig. 63.16 Male patients with hypohidrotic ectodermal dysplasia. Note the flat nasal bridge, depressed nasal tip, sparse hair (scalp, eyebrows, eyelashes), peg-shaped teeth, full lips and sebaceous hyperplasia. Also note the normal secondary hair in adults. A, Courtesy, Julie V Schaffer, MD; B,D, Courtesy, Mary Williams,

Genodermatoses



MD.

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Treatment

Pathogenesis

Controlling ambient temperatures and external methods of cooling, e.g. wet T-shirts, wet headbands and cooling vests, are critical to prevent hyperthermia in children with HED. Regular use of moisturizers is helpful for dry skin. Dentures can be fitted in children as young as 3 years of age, and dental restoration through implants should be employed for older patients. Multidisciplinary care is often required for treatment of other manifestations, which range from nasal concretions, asthma and recurrent respiratory infections to weight deficits and reduced salivary secretion. Referral to the National Foundation for Ectodermal Dysplasias (www.nfed.org) is also an important aspect of care. This organization provides information and support to affected families, including yearly regional and national conferences. The potential for protein therapy for HED is on the horizon136,137. In Tabby mice (the murine form of X-linked HED), the administration of recombinant EDA protein in utero or in the immediate postnatal period can completely or partially correct the phenotype138. Neonatal administration of recombinant EDA in a canine model of X-linked HED has also led to significant correction of ectodermal defects139,140. The first human studies of recombinant EDA therapy for neonates and children with X-linked HED were recently initiated137.

HED-ID is most commonly inherited in an X-linked recessive pattern due to hypomorphic mutations in IKBKG (inhibitor of κ light polypeptide gene enhancer in B cells, kinase γ), which is also known as NEMO (nuclear factor-κB essential modulator). This gene encodes a subunit of a regulatory kinase that activates NF-κB downstream in the ectodysplasin (see Fig. 63.15) and tumor necrosis factor-α (TNF-α) pathways141. The condition primarily affects boys and is allelic to incontinentia pigmenti, which is caused by more detrimental IKBKG mutations that are lethal in male embryos unless in a mosaic state (see Ch. 62). Patients with HED-ID have a high frequency of somatic mosaicism in their T cells, reflecting revertant mutations that are critical for survival in this cell type. An autosomal dominant form of HED-ID due to mutations in the NFKBIA gene has also been described. These patients have decreased NF-κB signaling because the mutated α-component of the NF-κB inhibitor is resistant to degradation (see Fig. 63.15).

HYPOHIDROTIC ECTODERMAL DYSPLASIA WITH IMMUNE DEFICIENCY 1050

HED-ID is a rare condition that shares many features with classic HED but is differentiated by the associated immune abnormalities (see also Ch. 60).

Clinical Features Individuals with HED-ID often have milder abnormalities of ectodermal structures than do patients with classic HED. The findings can include hypodontia, conical teeth, hypotrichosis, and a reduced ability to sweat; frontal bossing, periorbital wrinkling, and everted lips may also be seen. A seborrheic- or atopic-like dermatitis that evolves into erythroderma may serve as a clue to the diagnosis142, and reticulated hyperpigmentation is occasionally observed. Extracutaneous inflammatory manifestations can include colitis, which affects ~25% of patients, and chronic arthritis.

Fig. 63.18 Hidrotic ectodermal dysplasia (Clouston syndrome). Note the thickened, shortened nails with distal separation and tiny papules in a regular distribution on the



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63 Other Genodermatoses

Fig. 63.17 Female patients with X-linked hypohidrotic ectodermal dysplasia. Note the peg-shaped teeth, hypodontia, and full lips (A), as well as sparse eyelashes and periorbital hyperpigmentation (B) and sebaceous hyperplasia in a distribution following the lines of Blaschko (C). A, Courtesy, Julie V Schaffer, MD.

Hidrotic ectodermal dysplasia was first described in a French-Canadian kindred145 and the ancestry of many affected individuals was traced to a single founder. Subsequently, the disorder has been reported in individuals of varying racial and ethnic backgrounds146. %

Pathogenesis Hidrotic ectodermal dysplasia is an autosomal dominant condition that is caused by missense mutations in the GJB6 gene, which encodes the connexin 30 protein and is thought to be regulated by the p63 transcription factor147. Connexins oligomerize to form gap junctions that are important for communication between cells (see Ch. 58), and GJB6 is expressed in keratinocytes. Mutations in genes that encode other connexins cause skin disorders ranging from Vohwinkel and keratitis– ichthyosis–deafness (KID) syndromes (GJB2) to erythrokeratodermia variabilis (GJB3 and GJB4) (see Table 58.5). Mutations in GJB6 can also cause non-syndromic, autosomal dominant, digenic (together with a GJB2 mutation) deafness, with normal teeth and hair in affected individuals; less often the inheritance pattern is autosomal recessive. A GJB6 mutation has also been described in a patient with a KID syndrome-like phenotype that included congenital atrichia. Molecular testing of the GJB6 gene is available in clinical laboratories.

Clinical Features

The immunodeficiency results in recurrent pyogenic bacterial infections, especially of the skin and respiratory tract, as well as opportunistic infections. It is characterized by a poor antibody response to polysaccharide antigens, dysgammaglobulinemia (typically elevated IgM and IgA but decreased IgG levels), and defective natural killer cell activity. Patients with the autosomal dominant form of HED-ID also have a severe T-cell deficiency. Occasionally, infants with X-linked HED-ID present with osteopetrosis (abnormally dense bones) and lymphedema141,143. Female carriers, e.g. mothers of affected children, may have mild features of incontinentia pigmenti (see Ch. 62).

This condition primarily affects the hair and nails, with normal teeth and sweating. The hair is wiry, brittle and pale; patchy alopecia is common. Both hair loss and nail changes may progress over time. In affected infants, the nails are typically milky white and smaller than normal with gradual thickening throughout childhood. In adults, the nail plates grow slowly, are thick, and separate from the nail bed distally (Fig. 63.18). Hyperkeratosis with stippling of the palms and soles can also be progressive (see Ch. 58). Tiny papules in a grid-like array, corresponding to eccrine acrosyringia, or larger papules coalescing in a cobblestone-like pattern may extend from the palms and soles onto the dorsal surface of the digits, especially distally (see Fig. 63.18 and Fig. 58.10); the latter corresponds to where the dermatoglyphics are more prominent. Similar papules may also occur on the extensor surfaces of the extremities. Oral leukoplakia has been described, and sparse eyelashes may predispose patients to conjunctivitis and blepharitis.

Treatment

Pathology

&

Intravenous immunoglobulin (IVIg) administration does not typically decrease the propensity to develop infections. Allogeneic hematopoietic stem cell transplantation can correct the immune defects, but reported recipients have had difficulty achieving engraftment and experienced post-transplant complications such as worsening colitis142,144.

HIDROTIC ECTODERMAL DYSPLASIA Synonym:  ■ Clouston syndrome

Histologic evaluation of thickened palms and soles shows orthohyperkeratosis with a normal granular layer. Eccrine syringofibroadenomatosis, which is characterized by proliferation of ductal structures within a fibrovascular stroma, may be observed when papular lesions are biopsied. The hair does not have specific microscopic changes.

Differential Diagnosis The hair abnormalities in hidrotic ectodermal dysplasia distinguish it from pachyonychia congenita, which may have similar nail findings. A hidrotic ectodermal dysplasia-like phenotype plus deafness has been reported in a few patients with a GJB2 mutation.

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Treatment The National Foundation for Ectodermal Dysplasias can provide support to affected individuals and families. Ablation of the nail matrix is occasionally necessary for pain relief, and patients with substantial alopecia may choose to use hairpieces. Management of hyperkeratotic palms and soles is difficult; similar strategies to those used for the palmoplantar keratodermas, e.g. α-hydroxy acids, urea, soaking and paring, can be employed.

WITKOP TOOTH AND NAIL SYNDROME

encodes the p63 protein’s sterile alpha motif (SAM) domain152. p63, a transcription factor, is expressed within basal keratinocytes of the skin, which have a high proliferative capacity that is lost in differentiated keratinocytes. The p63 protein has multiple isotypes, with the SAM domain present in only some forms. This helps to explain the phenotypic differences between AEC syndrome and ectodermal dysplasia– ectrodactyly–clefting (EEC) syndrome (see Table 63.12 and below), which is due to mutations within the DNA-binding domain of TP63152,153.

Clinical Features

Synonyms:  ■ Tooth and nail syndrome ■ Witkop syndrome ■ Hypodontia with nail dysgenesis

First described in 1965, this autosomal dominant disorder is probably more common than suggested by the relatively small number of reports in the literature148. Affected individuals have small, thin, brittle nail plates that grow slowly, and koilonychia may be evident at birth. The toenails are usually more prominently involved than the fingernails, and nail abnormalities tend to improve with age. Thin, fine scalp hair is an occasional feature. The primary teeth may be normal or small and/or peg-shaped (Fig. 63.19). There is usually prolonged retention of primary teeth and partially or totally absent secondary dentition, especially the mandibular incisors, second molars and maxillary canines. A mutation in MSX1 (muscle segment homeobox 1), which is expressed in developing teeth and nail beds in mice, has been identified in a family with Witkop tooth and nail syndrome149. Mutations in MSX1 have also been described in families with isolated tooth agenesis or non-syndromic cleft lip and/or palate. MSX1 is a transcription factor that has roles in the development of teeth and presumably nails. Fried tooth and nail syndrome represents a similar condition with autosomal recessive inheritance and more consistent hair abnormalities.

ANKYLOBLEPHARON–ECTODERMAL DEFECTS– CLEFT LIP/PALATE SYNDROME Synonyms:  ■ Hay–Wells syndrome ■ Rapp–Hodgkin syndrome This autosomal dominant ectodermal dysplasia, first described in 1976150, has been reported in ethnically and geographically diverse individuals and families151.

Pathogenesis The ankyloblepharon–ectodermal defects–cleft lip/palate (AEC) syndrome is caused by mutations in the region of the TP63 gene that Fig. 63.19 Witkop tooth and nail syndrome. Small primary teeth, some conical, in a 7-year-old boy. Radiographs showed an absence of nearly all of the secondary teeth.  

Courtesy, Julie V Schaffer, MD.

This disorder is evident at birth. Up to 90% of affected infants present with erythroderma, peeling skin or erosions, which can result in lifethreatening infectious complications (Fig. 63.20A). The scalp is almost always involved, and a chronic, erosive scalp dermatitis is common (Fig. 63.20B,C). The scalp hair is wiry and usually lightly pigmented and sparse, often with patchy alopecia. Some degree of nail dystrophy is typically evident, with findings ranging from hyperconvex, thickened nail plates to anonychia. Patients may have decreased sweating and heat intolerance154,155. Patients often develop abnormal granulation tissue and recurrent bacterial infections of the skin. Cribriform and stellate scarring tends to occur in a shawl-like distribution on the shoulders and upper trunk154. Progressive reticulated hyperpigmentation frequently appears in intertriginous areas, and hypopigmentation of the scalp and face may be seen in children with darkly pigmented skin. Congenital strands of tissue between the eyelids (ankyloblepharon adnatum filiforme) are observed in approximately three-quarters of affected individuals (Fig. 63.20D). These may lyse spontaneously, even prior to birth, or require surgical correction. The lacrimal ducts may be atretic. Almost all patients with AEC syndrome are born with a cleft palate with or without a cleft lip. Malformed external ears and recurrent otitis media with secondary conductive hearing loss are common156. Dental abnormalities include hypodontia and misshapen (e.g. conical) teeth, and most patients have maxillary hypoplasia. Gastroesophageal reflux develops in the majority of AEC patients, while one-quarter of affected children fail to thrive and require gastrostomy placement157. Hypospadias affects up to 80% of male patients, and supernumerary nipples and/or ectopic breast tissue have been described158. Limb abnormalities are more common in AEC syndrome than once thought154,155,159; these malformations, which are typically less severe than the defects seen in EEC syndrome (see below), can include syndactyly (partial or complete), camptodactyly, brachydactyly, and even ectrodactyly158 (Fig. 63.20E).

Pathology Hair shaft abnormalities such as pili torti and pili trianguli et canaliculi may be observed. Histopathologic changes are nonspecific and often include mild epidermal atrophy and dermal melanophages160.

Differential Diagnosis Rapp–Hodgkin syndrome, once considered to be a distinct entity, is now thought to fall within the AEC spectrum. Affected individuals have heterozygous mutations in the SAM domain of TP63; other than a lack of ankyloblepharon, clinical findings overlap with those of AEC syndrome, including maxillary hypoplasia, cleft palate ± lip, nail dystrophy, and abnormalities of the teeth and hair161. The clinical features of AEC also overlap with those of curly hair–ankyloblepharon–nail dysplasia syndrome (CHANDS), which may be caused by homozygous mutations in the receptor-interacting serine-threonine kinase 4 gene (RIPK4) that is a direct transcriptional target of p63162. The peeling erythroderma of neonates with AEC syndrome can lead to a misdiagnosis of epidermolysis bullosa or congenital ichthyosis.

Treatment

1052

Surgical repair of oral clefting is usually necessary. Treatment for the erosive scalp dermatitis should be gentle and non-occlusive, with surveillance for and treatment of secondary infections. Debridement often causes erosions to worsen, and skin grafts typically fail. Ulceration and granulation tissue may be very difficult to treat, and healing tends to be slow.

CHAPTER

Other Genodermatoses

63

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B &

E '

Fig. 63.20 Ankyloblepharon–ectodermal defects–cleft lip/palate syndrome. A Extensive erosions in an infant who succumbed to sepsis. B, C Thick scale-crust and alopecia of the scalp. D Strands of tissue between the eyelids (ankyloblepharon adnatum filiforme). E Digital abnormalities (including syndactyly, brachydactyly) and nail dystrophy (yellowing and thickening of the nail plate). B, Courtesy, Jean L Bolognia, MD; C, Courtesy, Julie V Schaffer, MD.  

ECTODERMAL DYSPLASIA–ECTRODACTYLY– CLEFTING SYNDROME Synonym:  ■ Split hand–split foot–ectodermal dysplasia–clefting syndrome

First described by Eckholdt and Martens in 1804, this disorder occurs in all ethnic groups and has been reported worldwide.

Pathogenesis Ectodermal dysplasia–ectrodactyly–clefting (EEC) syndrome is an autosomal dominant disorder caused by mutations in the region of the TP63 gene that encodes the protein’s DNA-binding domain163,164. These mutations disrupt the ability of the p63 transcription factor, which is expressed in proliferating epidermal basal cells, to regulate gene expression. TP63 mutations also occur in several related autosomal dominant disorders, including non-syndromic split hand/foot malformation (minority of affected families), limb–mammary syndrome and ADULT (acro-dermato-ungual-lacrimal-tooth) syndrome, as well as in AEC

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syndrome (see Table 63.12 and above). Patients with EEC syndrome typically have missense mutations within the DNA-binding domain that differ from those seen in the other disorders164. Molecular testing for TP63 mutations is commercially available.

Clinical Features The ectodermal changes in this highly variable condition may be quite mild165. The scalp hair is usually light in color and coarse. It may be sparse and grow slowly. The secondary sexual hair may also be affected. Scalp folliculitis and dermatitis are rare166,167. Approximately 80% of affected individuals have transverse ridging, pitting, and slow growth of the nail plates. Xerotic skin and palmoplantar hyperkeratosis can occur, and sweating is usually normal. Clefting of the palate/lip occurs in ~50% of affected individuals, and additional oral abnormalities include enamel hypoplasia, hypodontia, and premature loss of secondary teeth. Lacrimal duct defects leading to blepharitis and dacryocystitis are frequently present, and limbal stem cell deficiency can result in photophobia and keratopathy as well as corneal ulceration and scarring168. Secondary conductive hearing loss is also common, and choanal atresia is an occasional manifestation. Ectrodactyly, a specific split-hand/foot malformation due to failure of normal development of the central digits, represents a defining feature of EEC syndrome (Fig. 63.21). The ectrodactyly is frequently asymmetric, usually with more severe involvement of the feet than the hands. Intrafamilial variability is marked. Genitourinary abnormalities are an under-appreciated manifestation of EEC syndrome and may be associated with dysplasia of the urogenital epithelium; renal and urogenital malformations affect more than one-third of patients and can result in hydronephrosis.

Pathology Histologic features are neither diagnostic nor specific.

Differential Diagnosis The presence of split-hand/foot malformations and the absence of ankyloblepharon or cutaneous erosions help to distinguish EEC syndrome from AEC syndrome. The findings that differentiate limb–mammary syndrome and ADULT syndrome from EEC are presented in Table 63.12. Other ectodermal dysplasias that feature digital abnormalities include ectodermal dysplasia–ectrodactyly–macular dystrophy (EEM) syndrome, cleft lip/palate ectodermal dysplasia, oculodentodigital dysplasia, and ulnar–mammary syndrome (see Tables 63.13 and 64.6). Although Goltz syndrome (focal dermal hypoplasia) can present with split-hand/foot and other digital malformations, nail dystrophy, sparse

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Fig. 63.21 Ectodermal dysplasia–ectrodactyly–clefting syndrome. Note the characteristic split-hand (A) and foot (B) deformities in these three siblings.  

hair, dental anomalies and (occasionally) cleft lip/palate, it is easily recognized based on the highly characteristic skin findings as well as ocular and additional skeletal (e.g. osteopathia striata) defects (see Ch. 62). Lastly, the popliteal pterygium syndrome, which is caused by mutations in the interferon regulatory factor 6 gene (IRF6) that is transcriptionally activated by p63, has overlapping features (see Ch. 64).

Treatment As for the other ectodermal dysplasias with oral clefting and lacrimal abnormalities, management involves a multidisciplinary approach. Limb defects may be ameliorated by surgical interventions. All affected individuals should be screened with a renal ultrasound. The small compound APR-246/PRIMA-1MET, which was developed to activate mutant p53 in cancer cells, was found in vitro to rescue impaired epidermal and corneal differentiation in cells from EEC patients, providing a potential approach to therapy169.

REFERENCES

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1. Romei C, Pardi E, Cetani F, Elisei R. Genetic and clinical features of multiple endocrine neoplasia types 1 and 2. J Oncol 2012;2012:705036. 2. Darling TN, Skarulis MC, Steinberg SM, et al. Multiple facial angiofibromas and collagenomas in patients with multiple endocrine neoplasia type 1. Arch Dermatol 1997;133:853–7. 3. Asgharian B, Turner ML, Gibril F, et al. Cutaneous tumors in patients with multiple endocrine neoplasm type 1 (MEN1) and gastrinomas: prospective study of frequency and development of criteria with high sensitivity and specificity for MEN1. J Clin Endocrinol Metab 2004;89:5328–36. 4. Nord B, Platz A, Smoczynski K, et al. Malignant melanoma in patients with multiple endocrine neoplasia type 1 and involvement of the MEN1 gene in sporadic melanoma. Int J Cancer 2000;87:463–7. 5. Fang M, Xia F, Mahalingam M, et al. MEN1 is a melanoma tumor suppressor that preserves genomic integrity by stimulating transcription of genes that promote homologous recombination-directed DNA repair. Mol Cell Biol 2013;33:2635–47. 6. Starink TM. Cowden’s disease: analysis of fourteen new cases. J Am Acad Dermatol 1984;11:1127–41. 7. Bubien V, Bonnet F, Brouste V, et al. High cumulative risks of cancer in patients with PTEN hamartoma tumour syndrome. J Med Genet 2013;50:255–63. 8. Starink TM, Van Der Veen JPW, Arwert F, et al. The Cowden syndrome: a clinical and genetic study in 21 patients. Clin Genet 1986;29:222–3.

9. Pilarski R. Cowden syndrome: a critical review of   the clinical literature. J Genet Couns 2009;18:  13–27. 10. DiCristofano A, Pesce B, Cordon-Cardo C, Pandolfi PP. Pten is essential for embryonic development and tumour suppression. Nat Genet 1998;19:348–55. 11. Song MS, Salmena L, Pandolfi PP. The functions and regulation of the PTEN tumour suppressor. Nat Rev Mol Cell Biol 2012;13:283–96. 12. Pilarski R, Burt R, Kohlman W, et al. Cowden syndrome and the PTEN hamartoma tumor syndrome: systematic review and revised diagnostic criteria. J Natl Cancer Inst 2013;105:1607–16. 13. Salem OS, Steck WD. Cowden’s disease (multiple hamartoma and neoplasia syndrome). J Am Acad Dermatol 1983;8:686–96. 14. Requena L, Guiterrez J, Yus ES. Multiple sclerotic fibromas of the skin, a cutaneous marker of Cowden’s disease. J Cutan Pathol 1992;19:346–51. 15. Wade TR, Kopf AW. Cowden’s disease: a case report and review of the literature. J Dermatol Surg Oncol 1978;4:459–64. 16. Tan WH, Baris HN, Burrows PE, et al. The spectrum of vascular anomalies in patients with PTEN mutations: implications for diagnosis and management. J Med Genet 2007;44:594–602. 17. Kurek KC, Howard E, Tennant LB, et al. PTEN hamartoma of soft tissue: a distinctive lesion in   PTEN syndromes. Am J Surg Pathol 2012;36:  671–87.

18. Tan MH, Mester JL, Ngeow J, et al. Lifetime cancer risks in individuals with germline PTEN mutations. Clin Cancer Res 2012;18:400–7. 19. Fackenthal JD, Marsh DJ, Richardson AL, et al. Male breast cancer in Cowden syndrome patients with germline PTEN mutations. J Med Genet 2001;38:159–64. 20. Al-Zaid T, Ditelberg JS, Prieto VG, et al. Trichilemmomas show loss of PTEN in Cowden syndrome but only rarely in sporadic tumors. J Cutan Pathol 2012;39:493–9. 21. Starink TM, Hausman R. The cutaneous pathology of facial lesions in Cowden’s disease. J Cutan Pathol 1984;11:331–7. 22. Ni Y, He X, Chen J, et al. Germline SDHx variants modify breast and thyroid cancer risks in Cowden and Cowden-like syndrome via FAD/NAD-dependant destabilization of p53. Hum Mol Genet 2012;21:300–10. 23. Mahdi H, Mester JL, Nizialek EA, et al. Germline PTEN, SDHB-D, and KLLN alterations in endometrial cancer patients with Cowden and Cowden-like syndromes: an international, multicenter, prospective study. Cancer 2015;121:688–96. 24. Orloff MS, He X, Peterson C, et al. Germline PIK3CA and AKT1 mutations in Cowden and Cowden-like syndromes. Am J Hum Genet 2013;92:76–80. 25. Iacobas I, Burrows PE, et al. Oral rapamycin in the treatment of patients with hamartoma syndromes and PTEN mutation. Pediatr Blood Cancer 2011;57:321–3.

GENODERMATOSES SECTION 9

Developmental Anomalies Richard J. Antaya and Julie V. Schaffer

Chapter Contents The midline lesion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1057 Aplasia cutis congenita . . . . . . . . . . . . . . . . . . . . . . . . . . 1064 Other developmental anomalies . . . . . . . . . . . . . . . . . . . . 1068

Key features ■ The human neural tube is thought to close in an intermittent, multisite pattern, and neural tube defects that present as midline cutaneous lesions (e.g. cephaloceles, heterotopic brain tissue, rudimentary meningoceles) typically occur at the junction between two closure sites ■ Midline lesions of the nose and scalp have a high likelihood of representing developmental defects with a potential intracranial connection, and an evaluation with CT or MRI prior to surgical intervention is critical ■ The presence of a “hair collar” surrounding a lesion on the scalp is a sign of ectopic neural tissue or membranous aplasia cutis; the latter is thought to represent a forme fruste of a neural tube defect ■ Cutaneous lesions overlying the spinal axis can serve as a marker for spinal dysraphism, and their presence is often an indication for radiologic evaluation ■ Aplasia cutis congenita, a physical finding reflecting a disruption of intrauterine skin development, can be approached clinically based on the morphology and distribution of lesions as well as the presence or absence of associated abnormalities ■ A number of other developmental anomalies affect the skin; although they usually represent isolated defects, it is important to be aware of potential associated conditions

INTRODUCTION Developmental anomalies are a diverse group of congenital disorders that result from faulty morphogenesis. They include both malformations, defined as structural defects arising due to errors in embryologic development, and disruptions, which occur when a structure programmed to develop normally is damaged before it is fully formed. A classic example of the former is incomplete closure of the neural tube resulting in an encephalocele, while the latter process is illustrated by the anomalies associated with varicella embryopathy. Although developmental anomalies that affect the skin are often recognized at birth or during infancy, occasionally diagnosis is delayed until later in life. The cutaneous abnormalities range in severity from isolated, minor physical findings (e.g. rudimentary supernumerary digits) to deforming, potentially life-threatening defects (e.g. deep, irregular scalp aplasia cutis congenita in Adams–Oliver syndrome). Furthermore, some skin lesions that themselves appear to be innocuous may serve as important clues to the presence of a multiple congenital anomaly syndrome or, particularly when involving the midline, the existence of a serious defect of the underlying tissues. Such associations reflect the complex interactions between various ectodermal and mesodermal elements that occur during the intricate processes of morphogenesis and differentiation. This chapter begins with an overview of the midline lesion and its relationship to closure of the neural tube. A discussion of specific issues

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pertaining to midline lesions of the nose, scalp and spine follows, including a review of the different types of anomalies that can present in these sites. An overview of aplasia cutis congenita is followed by presentation of a clinical approach based on the morphology and distribution of lesions and the presence or absence of associated abnormalities. Finally, a variety of non-midline developmental anomalies are discussed, including lip pits, accessory tragi, supernumerary nipples, skin dimples, malformations of the dermatoglyphs, rudimentary supernumerary digits, and the amniotic band sequence. Developmental anomalies that are covered in Chapter 110 include ear pits as well as branchial cleft, thyroglossal duct, bronchogenic, median raphe, omphalomesenteric duct, and urachal cysts.

THE MIDLINE LESION A number of critical events occur during the third to fifth weeks of embryologic development (see Ch. 2). These include formation of the neural tube, separation of neuroectoderm from surface ectoderm, and interposition of mesodermal elements. Inherent in such a complicated process is the potential for error, which spans a spectrum from obvious, fulminant neural tube defects to subtle cutaneous anomalies. However, the latter may represent a sign of a significant underlying malformation. Classically, closure of the human neural tube was thought to be a continuous process, beginning at a single focus in the cervical region and progressing bidirectionally in a “zipper-like” fashion to culminate in the closure of the anterior and subsequently posterior neuropores. However, evidence suggests that in humans as well as other mammals, the cranial segment of the neural tube closes in an intermittent or multisite pattern. Four distinct initiation sites of neural tube closure have been identified in the mouse, and a similar pattern of closure has been proposed for humans, with an additional caudal site (Fig. 64.1)1. In support of the multisite closure model, neural tube defects (e.g. cephaloceles, myelomeningoceles, heterotopic brain/meningeal tissue) cluster either entirely within one closure site or at the junction of two sites, such as the nasal root (2–3) or vertex (2–4; see Fig. 64.1). Neural tube closure in the posterior cranial area is thought to occur via a membrane rather than a midline fusion of folds, and the appearance of this site during embryologic development in animals resembles that of human membranous aplasia cutis2. Specific genes may control individual closure sites, explaining repetitive events within families.

Midline Lesions of the Head and Neck The pathogenesis, differential diagnosis and management of midline lesions of the nose (Fig. 64.2) and scalp are discussed below, followed by a review of the individual developmental anomalies that may present with a midline lesion on the head or neck. Midline cysts of this region (e.g. thyroglossal duct, bronchogenic) are discussed in Chapter 110.

Midline nasal lesions It is important for physicians to recognize the potential intracranial connection of a midline nasal mass or pit3. Dermoid cysts, dermal sinuses, cephaloceles, and heterotopic brain tissue (nasal gliomas) resulting from faulty embryologic development of the frontobasal skull and/or adjacent ectodermal/neuroectodermal tissues all may present as congenital nasal lesions (Table 64.1). As a group, these midline nasal masses occur in ~2–5 per 100 000 live births. They are often misdiagnosed as more familiar entities such as epidermoid cysts and infantile hemangiomas. The various congenital midline nasal masses have similar developmental origins. As the bones of the skull form during the second month

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Developmental anomalies are congenital disorders that represent either malformations due to faulty embryologic development or disruptions caused by damage to normally developing structures. Midline skin lesions on the nose and scalp often represent developmental anomalies with the potential for intracranial extension, including dermoid cysts as well as neural tube defects such as cephaloceles and heterotopic brain or meningeal tissue. Likewise, cutaneous lesions overlying the spine can serve as a marker for spinal dysraphism. Aplasia cutis congenita reflects abnormal or disrupted intrauterine skin development and can be approached clinically based on the morphology and distribution of the lesions and the types of associated findings. Other developmental anomalies include congenital lips pits, branchial cleft sinuses, cutaneous dimples, abnormal dermatoglyphs, the amniotic band sequence, and accessory tragi, nipples and digits. Some are isolated defects while others are associated with additional cutaneous or visceral manifestations. The most common and significant developmental anomalies, their evaluation, and therapeutic interventions are reviewed.

cephalocele, heterotopic brain tissue, meningocele, dermoid cyst, spinal dysraphism, aplasia cutis congenita, lip pit, accessory tragus, supernumerary nipple, rudimentary polydactyly, dermatoglyphs, amniotic band sequence

CHAPTER

64 Developmental Anomalies

ABSTRACT

non-print metadata KEYWORDS:

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SECTION

INTERMITTENT/MULTISITE PATTERN OF NEURAL TUBE CLOSURE IN HUMANS

Genodermatoses

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2

4 3

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Fig. 64.1 Intermittent/ multisite pattern of neural tube closure in humans. The five separate initiation sites are labeled (in chronological order, 1–5), the direction of neural tube closure is indicated by the arrows, and the junctions (where defects tend to occur) designated with dots. The 2–3 junction corresponds to the location of frontoethmoidal neural tube defects, the 2–4 junction to parietal defects, and the 1–4 junction to occipital defects. Closure in region 4 is thought to occur   via membranous growth, proceeding in a superior direction; incomplete closure at this site could therefore result in a membranous defect at the 2–4 junction (i.e. the vertex).  

THE DIFFERENTIAL DIAGNOSIS OF NASAL MASSES PRESENTING AT BIRTH OR DURING INFANCY

Developmental defects Dermoid cyst*,† Cephalocele (encephalocele > meningocele)* • Nasal glioma * • Lymphatic malformation • Nasolacrimal duct cyst • •

Other cysts Epidermoid cyst Pilomatricoma • Ethmoid mucocele • •

Benign neoplasms and hamartomas Infantile hemangioma Hemangiopericytoma • Neurofibroma • Melanotic neuroectodermal tumor of infancy • Hamartomas: chondromesenchymal, chondroid, lipomatous or angiomatous • Teratoma‡ • •

Malignant neoplasms Rhabdomyosarcoma Fibrosarcoma • Osteosarcoma • Neuroblastoma •

5



*† Midline lesions.

The most common cause of a congenital midline nasal mass.

‡May also be malignant.

Table 64.1 The differential diagnosis of nasal masses presenting at birth or during infancy.  

COMMON SITES OF DEVELOPMENTAL ANOMALIES OF THE FACE AND NECK

Dermoid cysts (skin-colored, firm, +/– sinus ostium and hair) Nasal gliomas (red, firm, non-compressible) Encephaloceles (blue, soft, compressible; may transilluminate) Lip pits Midline cervical clefts Thyroglossal duct cysts (often move with swallowing or protrusion of the tongue) Bronchogenic cysts Sternal clefts Ear pits Accessory tragi/congenital cartilaginous rests of the neck Branchial cleft cysts/sinuses Facial aplasia cutis congenita (ACC) A: Brauer lines/Setleis syndrome (membranous ACC along the embryonic fusion plane between the frontonasal and maxillary prominences) B: Preauricular membranous ACC (along the embryonic fusion plane between the maxillary and mandibular prominences) C: Microphthalmia with linear skin defects syndrome (irregular, stellate ACC; also may involve neck)

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Fig. 64.2 Common sites of developmental anomalies of the face and neck.  

of gestation, diverticula of dura mater project: (1) inferiorly into the prenasal space that extends from the base of the skull to the nasal tip, deep to the nasal bone and skin but superficial to the nasal cartilage; and (2) anteriorly through the nasofrontal fontanelle into the glabellar area. These diverticula may make connections with the overlying dermis, but usually they regress completely, with subsequent bony fusion to form the base of the skull and the cribriform plate. However, if the dura mater does not separate from the dermis, an ectodermal residue, with or without a patent intracranial connection, can persist; furthermore, if faulty neural tube closure results in a bony defect, there may be herniation of brain tissue. Such ectopic elements can occur either within the prenasal space (nasoethmoidal, “intranasal”) or superiorly at the glabella (nasofrontal, “extranasal”)4. Depending on the contents of the lesion (e.g. cutaneous versus neural tissue, cyst versus tract only) and the patency of the intracranial connection, a dermoid cyst, dermal sinus, cephalocele, or nasal glioma results (see below). Many of these midline nasal lesions have the potential for intracranial communication, and, consequently, present a risk for the development of serious CNS infections such as meningoencephalitis or a brain abscess. In addition, recurrent inflammation and progressive expansion of the mass may result in bony atrophy and nasal distortion. Early and complete surgical excision with repair of associated bony and dural defects is imperative. In order to prevent ascending infections, a biopsy, needle aspiration, or other preoperative manipulations should be avoided. A thorough radiologic evaluation prior to surgery is mandatory. Ultrasound may detect some bony defects but has limited sensitivity. While CT is the most sensitive method for defining bony skull defects, falsepositive studies are common in young children undergoing bone maturation. MRI is superior in demonstrating intracranial masses and other soft tissue changes and may aid in planning surgical approaches5. In addition, surgical exploration is often necessary to definitively exclude the presence of an intracranial connection, as small fibrous tracts may not be detectable with imaging studies.

CHAPTER

Midline lesions of the scalp

• • • • • • • • • •

64 Developmental Anomalies

Subcutaneous nodules of the scalp are common, and in adults they are usually acquired lesions, such as epidermoid and tricholemmal cysts. However, midline scalp lesions that are noted at birth or in early childhood have a high likelihood of representing developmental defects, such as dermoid cysts, cephaloceles, heterotopic brain or meningeal tissue, and aplasia cutis congenita. In one series of 70 children presenting with a solitary, non-traumatic scalp nodule6, 61% of the lesions were dermoid cysts and 4% cephaloceles. More importantly, 37% of the lesions were found to extend intracranially to the dura or brain. In the evaluation of a patient with a subcutaneous nodule on the scalp, clinical clues that heighten suspicion of a developmental anomaly with potential intracranial extension include7: a patient who is an infant or child a lesion first noted at birth or during early childhood a family history of neural tube defects a history of meningitis the presence of neurologic signs or symptoms location of the lesion along the midline or over the suture lines of the scalp lesions that pulsate, transilluminate, or fluctuate in size with crying or straining lesions with a central pore in young children, who are less likely to have epidermoid cysts an overlying capillary malformation (port-wine stain) a positive hair collar sign (see below). A congenital midline lesion, or a scalp nodule with other concerning features, requires imaging studies prior to surgical excision or biopsy. If a bony defect is detected by ultrasound or CT, a follow-up MRI may be indicated to better evaluate whether there is extension of soft tissue transcranially. A neurosurgical referral is indicated if these studies are positive and, as small communications may be missed, complete surgical removal may be prudent even if they are negative8. The hair collar sign consists of a ring of long, dark, coarse hair surrounding a congenital scalp nodule. The presence of a hair collar is a relatively specific marker for ectopic neural tissue8,9. Hair collars are also seen in membranous aplasia cutis (Figs 64.3 & 64.4), a disorder thought to represent a forme fruste of a neural tube defect (i.e. without the presence of ectopic neural tissue)2. Drolet et al.8 hypothesized that cerebral herniation produces aberrant shearing forces during the formation of hair follicles early in development, causing them to point outward from the defect. The proximity of neuroectoderm expressing neural adhesion molecules may also alter normal epidermal–dermal interactions, thereby inducing the development of large, abnormal follicles2. These speculations correlate with the histologic and dermoscopic finding of numerous horizontally oriented, hypertrophic follicles emerging from the edge of scalp lesions to form the hair collar9,10. The differential diagnosis and evaluation of a positive hair collar sign is presented in Fig. 64.5.

Fig. 64.4 Hair collar sign. Membranous aplasia cutis congenita with a bullous appearance and a surrounding hair collar.  

DIFFERENTIAL DIAGNOSIS AND EVALUATION OF A POSITIVE HAIR COLLAR SIGN Scalp lesion with a hair collar

+ MRI CT →

Skull defect

Herniation of brain or meninges/CSF through defect

Transcranial stalk

• Encephalocele or • Meningocele

• Atretic encephalocele or • Atretic meningocele

• Neurosurgical repair

No skull defect

No transcranial connection

• Heterotopic brain tissue or • Rudimentary meningocele or • Aplasia cutis congenita, with skull defect

• Neurosurgical repair or • If the patient is a neonate and the lesion is consistent with membranous aplasia cutis, monitor clinically and follow radiographically to document closure of the skull defect

• Heterotopic brain tissue or • Rudimentary meningocele or • Aplasia cutis congenita, without skull defect

• Biopsy/excision or • If the lesion is consistent with membranous aplasia cutis, no further intervention is required

Fig. 64.5 Differential diagnosis and evaluation of a positive hair collar sign. In general, CT is the most accurate method of detecting skull defects. However, if a bony defect is detected by CT, a follow-up evaluation by MRI may be indicated to better determine whether there is extension of soft tissue transcranially.  

Fig. 64.3 Hair collar sign. Membranous aplasia cutis congenita with a hair collar.  

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Other developmental anomalies of the scalp Sinus pericranii is a rare disorder characterized by a congenital, or occasionally acquired, epicranial venous malformation of the scalp that communicates with an intracranial dural sinus through dilated diploic cranial veins11. The lesion is usually located near the midline, especially in the frontal region. Most are asymptomatic and appear as a compressible, fluctuant mass that varies in size with changes in intracranial pressure (Fig. 64.6). The differential diagnosis includes a simple venous or arteriovenous malformation, meningocele or encephalocele. Hairless congenital scalp lesions such as a nevus sebaceus (see Chs 62 & 111) and nevus psiloliparus (a hallmark of encephalocraniocutaneous lipomatosis; see Ch. 62) due to mosaic activating mutations may mimic developmental anomalies of the scalp.

fluid (CSF) can occur with intracranial dermoid cysts. Lastly, dermoid cysts and dermal sinuses overlying the spine may be associated with occult dysraphism (see below) and if the tract connects with the subarachnoid space, an increased risk of meningitis. Histologically, dermoid cysts in any location are lined by keratinizing stratified squamous epithelium and contain mature adnexal structures (see Ch. 110)13. Treatment is by excision, and preoperative imaging studies are required for lesions located on the nose, midline scalp, or posterior axis or those with other suspicious features (e.g. a draining sinus ostium) in order to exclude a connection to the CNS.

Cephaloceles

Dermoid cysts result from sequestration of ectodermal tissue along embryonic fusion planes during development. They are a separate entity from benign cystic teratomas, neoplasms that are also referred to as dermoids. Although dermoid cysts are congenital defects and may be recognized at birth, these lesions often escape notice until they become enlarged, inflamed, or infected. This typically occurs by early childhood, but diagnosis may be delayed until as late as the sixth decade of life. Dermoid cysts present as firm, non-compressible, non-pulsatile subcutaneous nodules that often reach a size of 1–4 cm in diameter. The lesions usually do not transilluminate. They are most commonly located around the eyes, particularly the lateral eyebrow (Fig. 64.7), but may also be found on the nose, scalp (often over the anterior fontanelle or the midline occiput), neck, sternum, sacrum, and scrotum. Dermoid cysts on the nose or midline scalp have a much higher likelihood of intracranial extension than those in a periocular location. Nasal lesions, which account for 2.5 cm from the anal verge in neonates (Figs 64.12 & 64.14); >0.5 cm in size or depth*

Dermal sinuses

Hair may be present at the ostium*

Acrochordons

May be associated with a dimple or dermal sinus

Pseudotails

Caudal protrusion due to prolonged vertebrae or hamartomatous elements, e.g. adipose tissue or cartilage (Fig. 64.14)

True tails

Persistent vestigial appendage with a central core of mature adipose tissue, muscle, blood vessels and nerves



spinal defect. Lumbosacral capillary stains often have rhomboidal or triangular shapes (“butterfly-like”) and are frequently associated with additional nevus simplex lesions of the head, neck, and (occasionally) upper back. Many authors feel that regardless of spinal level, capillary stains alone are rarely a sign of dysraphism26,28. A prospective study of 3623 neonates found that 1 of the 25 individuals noted to have a sacral capillary stain in the absence of other lumbosacral skin lesions had a spinal abnormality revealed by imaging studies33. Cutaneous lesions of the spinal axis that should alert the clinician to the possibility of dysraphism are summarized in Table 64.2. In one study27, 39% (22/56) of neonates with “high-risk” stigmata such as hypertrichosis, subcutaneous masses, infantile hemangiomas, tails, or dimples above the gluteal cleft were found to have spinal dysraphism (see Figs 64.13 & 64.14). The presence of two or more skin lesions is a particularly strong sign; in another series, 61% (11/18) of such patients had spinal dysraphism, compared to 8% (3/36) of those with only one skin lesion34. High-risk cutaneous stigmata overlying the spine represent an indication for radiologic evaluation, and superficial removal for cosmetic reasons is contraindicated until an underlying abnormality is excluded. MRI is highly sensitive and represents the imaging modality of choice in patients of all ages when occult spinal dysraphism is suspected. Although the vertebrae are not yet completely ossified in infants intraspinal hemangioma) in infants with lumbosacral infantile hemangiomas32. However, in infants with dysraphism associated with an anorectal malformation, spinal ultrasound had a sensitivity as low as 15%36. When infants are found to have anomalies with the potential to cause traction and/or pressure on the spinal cord, close follow-up is required and neurosurgical intervention may be recommended. Fig. 64.11 provides an algorithm for the approach to patients with cutaneous signs of spinal dysraphism.

APLASIA CUTIS CONGENITA Synonyms:  ■ Cutis aplasia ■ Congenital absence of skin ■ Congenital 1064

scars

May be capable of spontaneous or reflex motion Infantile hemangiomas

Superficial, usually segmental pattern (Fig. 64.14), often ulcerated

Telangiectasias

May represent an early, minimal/arrested growth, or regressed infantile hemangioma

Vascular malformations

Capillary malformations (CMs) are typically found together with other skin lesions Cobb syndrome: spinal arteriovenous malformation associated with skin involvement in the same segment mimicking a CM or angiokeratomas

Aplasia cutis congenita (ACC)

Ulcer, scar, or atrophic skin

Connective tissue nevus

Typically found together with other skin lesions

Hypo/depigmentation

May represent a nevus depigmentosus (typically found together with other skin lesions) or the residua of ACC

Hyperpigmentation

Typically found together with other skin lesions

Congenital melanocytic nevi

Spinal dysraphism has been reported in patients with neurocutaneous melanosis

Subcutaneous masses

May represent lipomas, meningoceles, lipomyelomeningoceles, teratomas, ependymomas, or plexiform neurofibromas

*Due to a potential risk of meningitis, these lesions should not be probed. Table 64.2 Skin lesions of the spinal axis associated with dysraphism. The presence of two or more types of lesions increases the risk of a spinal anomaly.  

Aplasia cutis congenita (ACC) is a condition in which localized or widespread areas of skin are absent or scarred at birth. It may occur as an isolated defect, in association with other developmental anomalies, or as a feature of a variety of disorders (Tables 64.3 & 64.4). There is no single underlying cause of ACC, which simply represents a physical finding that reflects an abnormality in intrauterine skin development. The many possible etiologies include genetic factors, vascular compromise, trauma, teratogens, and intrauterine infections37. As a result of its causal heterogeneity, the clinical appearance of ACC at birth is extremely variable, ranging from an erosion or deep ulceration to a scar due to healing in utero to a discrete ovoid defect covered by a membrane. The latter, referred to as membranous aplasia cutis, is the most common form. Occurring primarily on the scalp and often surrounded by a “hair collar” (see Figs 64.3 & 64.4), such lesions may represent a forme fruste of a neural tube defect2. However, membranous

CHAPTER

Inheritance (Gene)

Features

Associated abnormalities

Sporadic > AD

Usually at the vertex Membranous Hair collar

Often AD (BMS1)

Usually at the vertex Irregular and scar-like

No associated abnormalities Isolated abnormalities (most often associated with membranous ACC): cleft lip and/or palate, tracheoesophageal fistula, high myopia and cone-rod dysfunction, patent ductus arteriosus, intestinal lymphangiectasia, omphalocele, polycystic kidneys, double cervix and uterus, intellectual disability, temporal triangular alopecia

Group 2: Scalp ACC associated with Adams–Oliver syndrome (types 1–6)

AD (ARHGAP31, RBPJ, NOTCH1, DLL4) AR (DOCK6, EOGT)

Midline scalp Often large, irregular lesions Skull defect Dilated scalp veins

Adams–Oliver syndrome: terminal transverse limb defects (e.g. reductions, syndactyly, nail dystrophy), cutis marmorata telangiectatica congenita, cardiac malformations, CNS abnormalities

Group 3: Scalp ACC associated with epidermal and organoid nevi (and, occasionally, large congenital melanocytic nevi)

Sporadic due to mosaic mutations (e.g. HRAS, KRAS)

Scalp, often unilateral Membranous

Epidermal nevus or nevus sebaceus, usually in proximity to the ACC Large congenital melanocytic nevus: in a few reports* Ipsilateral ophthalmologic abnormalities: corneal opacities, scleral dermoids, eyelid colobomas, retinal dystrophy CNS abnormalities: intellectual disability, seizures

Group 4: ACC overlying embryologic malformations

Variable

Scalp, often with a hair collar if overlying a neural tube defect Lumbosacral Chest, abdomen

Cranial malformations: cephalocele, heterotopic brain or meningeal tissue, congenital midline porencephaly, holoprosencephaly, craniosynostosis, vascular malformation/ aplasia/arteriovenous fistula Spinal malformations: occult dysraphism, myelomeningocele Thoracic malformations: sternal cleft Abdominal malformations: omphalocele, gastroschisis Multiple malformations associated with generalized, lethal ACC (“systemic” ACC): corneal opacities, choanal atresia, hypoplastic lungs, absent greater omentum, intestinal malrotation & atresias, hepatosplenomegaly, skull defects, syndactyly, anonychia

Group 5: ACC associated with fetus papyraceus, placental infarcts, or other ischemic events

Sporadic

Scalp, chest, flanks, axillae and/or extremities (see Fig. 64.17) Multiple, symmetric Stellate/angulated configuration

Associated fetus papyraceus due to second-trimester death of twin/triplet or fetal reduction of higher-order pregnancies Placental infarction, single umbilical artery Duodenal, ileal, and/or biliary atresias with intestinal infarction Volkmann ischemic contracture of the forearm Intracranial hemorrhage/CNS abnormalities Amniotic bands, clubbed hands/feet, nail dystrophy

Group 6: ACC associated with EB

AD or AR, depending on EB type

Lower extremities (“Bart syndrome”) or large areas of the trunk and extremities

Simplex, junctional and dystrophic (including bullous dermolysis of the newborn) types of EB: blistering of skin and/or mucous membranes, skin fragility, nail dystrophy In more severe cases (most associated with junctional EB): pyloric atresia, ureteral stenosis, renal abnormalities, arthrogryposis, abnormal ears and nose, amniotic bands

Group 7: ACC localized to extremities without blistering

AD or AR

Pretibial areas, extensor forearms, dorsal hands and feet

Radial dysplasia (associated with ACC on the extensor forearm)

Group 8: ACC caused by specific teratogens, maternal conditions or intrauterine infections

Not inherited

Scalp with drugs Any site with congenital infections

Methimazole (thiamazole), carbimazole: imperforate anus, urachal malformations Misoprostol Low-molecular-weight heparin Valproic acid Maternal antiphospholipid syndrome Intrauterine varicella, herpes simplex or rubella infection: signs of these infections

Group 9: ACC associated with malformation syndromes

Variable

Variable

See Table 64.4 Amniotic band sequence and disorganization syndrome (see text)

Group 1: Scalp ACC without multiple anomalies

64 Developmental Anomalies

CLASSIFICATION SCHEME FOR APLASIA CUTIS CONGENITA (ACC)

*Referred to as “SCALP” syndrome (sebaceous nevus, CNS malformations, ACC, limbal dermoid, pigmented nevus). Table 64.3 Classification scheme for aplasia cutis congenita (ACC). Bold text in column 4 signifies main topics, followed by details. AD, autosomal dominant; AR, autosomal recessive; ARHGAP31, Rho GTPase activating protein 31; BMS1, ribosome biogenesis factor; CNS, central nervous system; DLL4, Delta-like 4; DOCK6, dedicator of cytokinesis 6; EB, epidermolysis bullosa; EOGT, EGF domain-specific O-linked N-acetylglucosamine transferase; RBPJ, recombination signal binding protein for immunoglobulin κ J region (transcriptional regulator for the Notch pathway). Adapted from Frieden IJ. J Am Acad Dermatol. 1986;14:646–60, with permission.  

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SYNDROMES ASSOCIATED WITH APLASIA CUTIS CONGENITA (ACC, GROUP 9)

Inheritance (Gene)

Features of ACC

Other features

Focal facial dermal dysplasia (FFDD) FFDD1 – Brauer FFDD2 – Brauer–Setleis FFDD3 – Setleis FFDD4 – preauricular

FFDD1 & 2: AD, variable expressivity FFDD3: AR (TWIST2) FFDD4: AR (CYP26C1) > AD

Round or oval, membranous, ± hair collar Linear arrangement FFDD1–3: bilateral temples (“forcep marks”), from lateral eyebrow to anterior hairline* FFD4: bilateral from preauricular cheek to angle of mouth†

FFDD1: sparse lateral eyebrows, distichiasis, flat nasal tip FFDD2 & 3: abnormal eyelashes, upwardslanting eyebrows, “leonine” facies (Fig. 64.15), imperforate anus FFDD4: buccal mucosal polyps

Microphthalmia with linear skin defects syndrome (MLS, MIDAS)

X-linked dominant (HCCS)

Mid-cheek to bridge of nose Also may occur on neck Stellate erosions that heal with reticulolinear scarring

Microphthalmia, sclerocornea, agenesis of the corpus callosum, genital anomalies, short stature

Oculocerebrocutaneous syndrome (Delleman syndrome)

Sporadic or AD

Membranous on supra-auricular scalp (often crescentic shape) Also may occur on neck and lumbosacral area

Orbital cysts, microphthalmia, giant tectumabsent vermis, agenesis of the corpus callosum, facial appendages composed of skeletal muscle

Oculoectodermal syndrome

Mosaic (KRAS)

Membranous

Epibulbar dermoids, macrocephaly, truncal hyperpigmentation

Johanson–Blizzard syndrome

AR (UBRI)

Stellate or membranous

Dwarfism, hypoplastic nasal alae, hypodontia/ peg-like teeth, deafness, microcephaly, hypothyroidism, pancreatic insufficiency

Scalp–ear–nipple syndrome (Finlay–Marks syndrome)

AD (KCTD1)

May heal with hypertrophic scarring

Nipple/breast hypo- or aplasia, abnormal ears and teeth, nail dystrophy, syndactyly, reduced apocrine secretion

Trisomy 13 (Patau syndrome)

Sporadic

Membranous Large defects

Holoprosencephaly, ocular abnormalities, deafness, cleft lip/palate, cardiac malformations, polydactyly, narrow and convex nails; early death

4p- (Wolf–Hirschhorn) syndrome

Sporadic

Midline

Microcephaly, ocular abnormalities, cleft lip/ palate, preauricular pits and accessory tragi; often early death

Facial ACC (see Fig. 64.2)

Scalp ACC Adams–Oliver syndrome (see Table 64.3, ACC group 2)

*† Along the embryonic fusion line between the frontonasal prominence and the maxillary prominence of the first branchial arch. Along the embryonic fusion line between the maxillary and mandibular prominences of the first branchial arch.

Table 64.4 Syndromes associated with aplasia cutis congenita (ACC, group 9). ACC also may be found in patients with Goltz syndrome (focal dermal hypoplasia), branchio-oculo-facial syndrome, and several types of ectodermal dysplasia, including the EEC syndrome (ectrodactyly, ectodermal dysplasia, clefting), AEC syndrome (ankyloblepharon, ectodermal dysplasia, cleft lip/palate), and tricho-odonto-onychial dysplasia. In addition, there have been reports of scalp ACC in patients with Pallister–Killian syndrome (tetrasomy 12p), Opitz syndrome, popliteal pterygium syndrome, Marshall syndrome, and hereditary sensory and motor neuropathy type I (www.ncbi.nlm.nih.gov/omim). AD, autosomal dominant; AR, autosomal recessive; CYP26C1, cytochrome P450 family 26C, polypeptide 1; HCCS, holocytochrome c synthase; KCTD1, potassium channel tetramerization domain-containing 1; MIDAS, microphthalmia, dermal aplasia and sclerocornea; UBR1, ubiquitin-protein E3 component n-recognin 1.  

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aplasia cutis can also be seen along the embryonic fusion lines of the face (Table 64.4; Figs 64.2 & 64.15)38. Membranous aplasia cutis typically presents at birth as a sharply marginated (“punched-out”), oval or round defect covered by a thin, translucent, glistening epithelial membrane. Lesions may contain serous fluid in the neonatal period, resulting in a bullous appearance (see Fig. 64.4). Eventually, they tend to flatten and transform into an atrophic scar (Fig. 64.16A). Dermoscopy typically shows a lack of follicular openings, telangiectatic vessels, and radially oriented hair follicles extending horizontally at the periphery (“starburst-like”)38a. Hypertrophic scarring can be a manifestation of an autosomal dominant form of scalp ACC in which mutations in the ribosomal GTPase BMS1 result in a cell cycle defect39. A second major type of ACC consists of stellate or angulated lesions, which are thought to result from vascular abnormalities and/ or intrauterine ischemic events. Examples include irregular midline scalp defects in Adams–Oliver syndrome40,41 and extensive, symmetric lesions on the trunk and/or extremities associated with fetus

Fig. 64.15 Facial aplasia cutis congenita. Atrophic cutaneous defect extending from the lateral eyebrow to the anterior hairline in a patient with Setleis syndrome. Note the upward-slanting eyebrows and “leonine” facial appearance. Courtesy,  

Seth Orlow, MD, PhD.

CHAPTER

Developmental Anomalies

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Fig. 64.16 Aplasia cutis congenita (ACC). A This hairless, round, scarred plaque on the scalp of a 6-month-old was present at birth. B Stellate ACC on the midline scalp of a neonate. This hemorrhagic lesion was associated with an underlying skull defect and cerebrovascular anomalies. C Stellate ACC on the lateral trunk of a neonate born of an initial sextuplet gestation for which fetal reduction was performed. The lesions had a bilateral, symmetric distribution. D ACC on the leg in a neonate with epidermolysis bullosa (“Bart syndrome”). E Membranous ACC associated with a large defect of the underlying skull in a patient with Goltz syndrome.  

A, Courtesy, Anthony J Mancini, MD; D, Courtesy, Emily Berger, MD.

TYPICAL LOCATIONS FOR SEVERAL FORMS OF APLASIA CUTIS CONGENITA

papyraceus, placental infarction and other forms of vascular insufficiency (Fig. 64.17)42. These defects usually appear as ulcers of variable depth with a raw, hemorrhagic, or granulating base (Fig. 64.16B,C). Other patterns of ACC include a lack of skin overlying embryologic malformations, either obvious or occult, and large erosions with jagged borders on the extremities of neonates with epidermolysis bullosa. The latter likely result from the mechanical trauma of fetal movements in a setting of increased skin fragility. The morphology and distribution of the skin defects (see Fig. 64.17) as well as the presence or absence of associated abnormalities represent important clues to the etiology of ACC. Table 64.3 presents a classification scheme for ACC, and Table 64.4 describes several syndromes associated with ACC. However, because ACC is a physical finding that may result from any intrauterine event that disrupts skin development, not all cases can be neatly categorized. Unusual presentations of ACC range from an isolated defect on the ventral penis to an extreme form with absence of skin and subcutaneous tissue over >90% of the body surface area associated with extracutaneous anomalies (“systemic” ACC; see Table 64.3). The scalp is the most common site for ACC, accounting for >85% of solitary lesions. The majority of cases of scalp ACC, whether membranous or irregular and scar-like, are located at or near the vertex, in proximity to the parietal hair whorl43. Approximately 25% of patients have more than one lesion, and multiple membranous lesions may occur in a linear arrangement. Most defects are 1–2 cm in diameter, although the size can range from 0.5 to >10 cm. Scalp ACC involves the underlying skull in 20–30% of cases44. Large, irregular lesions are more likely to extend to deeper structures and may affect the dura and/ or leptomeninges. Dilated scalp veins may also be seen in association with ACC, especially in patients with Adams–Oliver syndrome (see Table 64.3)40. Histologic features of membranous aplasia cutis include an atrophic flattened epidermis, replacement of the dermis by loose connective

Membranous ACC Adams−Oliver syndrome Microphthalmia with linear skin defects

ACC associated with fetus papyraceus/ ischemic events: More common sites Less common sites

“Bart syndrome” (ACC associated with epidermolysis bullosa) Oculocerebrocutaneous syndrome

Fig. 64.17 Typical locations for several forms of aplasia cutis congenita (ACC). See Fig. 64.2 for Brauer lines/Setleis syndrome, preauricular membranous ACC, and microphthalmia with linear skin defects.  

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tissue, and an absence of adnexal structures. Findings in other types of ACC vary but lesions that have healed generally show scarring and a lack of adnexa. Although histologic examination may be helpful in some instances, the diagnosis of ACC is primarily clinical. Cutaneous defects noted at birth may initially be erroneously attributed to obstetric trauma, such as injuries from forceps or fetal scalp electrodes. Evaluation of a patient with ACC is directed by the personal, obstetric, and family history as well as the physical examination; in a neonate, it may include specific investigations such as examination of the placenta and viral studies for herpes simplex and varicella zoster45. In patients with large, deep, irregular, or membranous lesions of the scalp (Fig. 64.16B,E), imaging studies are indicated to assess for underlying bone defects, vascular anomalies, or brain malformations. Lastly, elevated α-fetoprotein in midtrimester maternal serum and amniotic fluid as well as elevated acetylcholinesterase in the amniotic fluid may represent early signs of ACC, although they are neither sensitive nor specific for this condition. Most small lesions of ACC heal within the first few months of life, leaving an atrophic (see Fig. 64.16A) or, less often, hypertrophic (“lumpy”) scar. In such instances, daily cleansing and application of a topical antibiotic ointment or petrolatum until healing is complete are often the only interventions required. Underlying skull defects also tend to resolve spontaneously during infancy. However, potential complications of deep ACC of the scalp include life-threatening sagittal sinus hemorrhage/thrombosis and meningitis. Because the risk of complications increases if the period of healing is prolonged, early surgical repair of large stellate scalp lesions or those associated with a dural defect or exposure of the sagittal sinus is recommended. Preoperative imaging studies are required to identify underlying vascular structures. Even without surgical intervention, residual scarred, hairless areas generally become less conspicuous as the child grows. If desired for cosmetic reasons, excision or hair transplants can be performed later in life.

OTHER DEVELOPMENTAL ANOMALIES Congenital Lip Pits Synonyms:  ■ Lip sinuses ■ Congenital sinuses of the lower lip ■

Midline sinuses of the upper lip

Congenital lip pits are divided into three types based on their location: (1) commissural; (2) upper lip; and (3) lower lip. Commissural lip pits are by far the most common, occurring in 1–2% of newborns. Lip pits likely result from defective embryologic fusion of facial processes with epithelial entrapment. They usually represent the opening of a blind sinus tract, which can extend inward through the orbicularis oris muscle to a depth of >10 mm. This tract occasionally communicates with the ducts of underlying minor salivary glands, and saliva or mucus

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may drain from the ostium. Lesions are sometimes associated with swelling of the lip or, particularly if located on the philtrum, recurrent infection. Commissural lip pits are typically found bilaterally in the mucosal surface at the angles of the mouth (Fig. 64.18A). Although most often an isolated anomaly, they may be inherited in an autosomal dominant fashion along with preauricular pits and hearing impairment in patients with a form of branchio-otic syndrome linked to chromosome 1q3146. Commissural lip pits also have been described in association with alveolar synechiae, ankyloblepharon filiforme adnatum (congenital adhesions between the upper and lower eyelids), and ectodermal defects. Upper lip pits, also known as midline sinuses of the upper lip, are rare lesions that are typically located along the philtrum. Although usually an isolated defect, they may be associated with hypertelorism and other dysmorphic facial features. In addition, paramedian upper lip pits may occur (Fig. 64.18B) and are bilateral in patients with the branchio-oculo-facial syndrome (see below, Branchial cleft sinuses and fistulae). Lower lip pits may be an isolated finding or seen as a part of van der Woude syndrome, which is characterized by paramedian pits in the vermilion portion of the lower lip, cleft lip and/or palate, and hypodontia. The lip pits are usually bilateral, and they may be located on the apex of a conical elevation (Fig. 64.18C). Van der Woude syndrome, which occurs in ~1–3 per 100 000 live births, is an autosomal dominant disorder caused by mutations in the interferon regulatory factor 6 (IRF6)47 or grainyhead-like 3 (GRHL3) gene. The popliteal pterygium syndrome is also due to IRF6 mutations; in addition to lower lip pits, findings include cleft lip and/or palate, syngnathia, popliteal webbing, nail dysplasia, syndactyly, and genital anomalies. Lastly, lower lip pits are occasionally seen in oral–facial–digital syndrome type I (Table 64.5) and Kabuki syndrome (www.ncbi.nlm.nih.gov/omim). Histologically, the sinus tracts associated with lip pits are lined by stratified squamous epithelium; associated salivary or mucous glands are occasionally observed. The evaluation of patients with lip pits should include a family history and a physical examination to exclude associated anomalies. If lip pits of any type are symptomatic or cosmetically undesirable, surgical excision is the treatment of choice. The extent of the sinus can be estimated preoperatively by injection of a radio-opaque contrast medium.

Accessory Tragi Synonyms:  ■ Preauricular tags ■ Preauricular appendages Accessory tragi are relatively common congenital anomalies of the first branchial arch, and they are found in 3–6 per 1000 live births. Familial occurrence has been reported, sometimes with a consistent anatomic site within kindreds. During development, the external ear is formed by the fusion of six tubercles, three each from the first and second branchial arches; the tragus and anterior crus of the helix are the only

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Fig. 64.18 Lip pits. A Bilateral commissural lip pits. B Unilateral right-sided upper lip pit. C Bilateral paramedian lower lip pits, each located on the apex of a conical elevation. All were isolated anomalies.  

Syndrome

Other features

Ectodermal dysplasias (see Ch. 63) EEC syndrome

AD, TP63 gene; ectodermal dysplasia, ectrodactyly, cleft lip/palate

AEC syndrome

AD, TP63 gene; ankyloblepharon, ectodermal dysplasia, cleft lip/palate



Cleft lip/palate– ectodermal dysplasia*

AR, nectin-1 (PVRL1) gene; ectodermal dysplasia, pili torti, syndactyly

Branchio-oculo-facial syndrome

See text – branchial cleft sinuses

Oral–facial–digital syndrome, type 1

X-D, OFD1 gene; lobulated tongue, hypertrophic oral frenula, digital malformations, whorled alopecia of the vertex, transient facial milia, polycystic kidneys, CNS anomalies

Oculocerebrocutaneous syndrome

See Table 64.4

4p- syndrome (Wolf– Hirschhorn syndrome)

See Table 64.4

Pai syndrome

Facial skin tags, nasal polyps, midline cleft lip, CNS lipomas

Basal cell nevus (Gorlin) syndrome

See Ch. 107

Goltz syndrome (focal dermal hypoplasia)

See Ch. 62

Waardenburg syndrome, type 1 or 3

See Ch. 66

Van der Woude syndrome†

See text – congenital lower lip pits

Popliteal pterygium syndrome†

See text – congenital lower lip pits

Nail–patella syndrome

See Ch. 71

Beare–Stevenson cutis gyrata syndrome

AD, FGFR2 gene; craniosynostosis, cutis gyrata, acanthosis nigricans





Local lesions Dermal melanocytosis Encephaloceles or nasal gliomas

*Includes Zlotogora–Ogur syndrome, Rosselli–Gulienetti syndrome, and Margarita Island ectodermal dysplasia. †Allelic disorders.

Table 64.5 Diseases affecting the skin that are associated with cleft lip and/ or palate. Other disorders associated with cleft lip/palate that also can affect the skin include Cornelia de Lange, Roberts, Simpson–Golabi–Behmel, Pallister–Hall and CHIME (colobomas [ocular], heart defects, ichthyosis, mental retardation and ear anomalies) syndromes, hemifacial microsomia, Meige disease (familial lymphedema praecox), and trisomy 13. AD, autosomal dominant; AR, autosomal recessive; CNS, central nervous system; PVRL1, poliovirus receptor-related 1; X-D, X-linked dominant.  

portions of the ear derived from the former48. Whereas preauricular pits and cysts reflect defective fusion of the tubercles (see Ch. 110), accessory tragi represent remnants of and/or extra tubercles originating from the first branchial arch. Accessory tragi most often manifest as skin-colored papules or nodules in the preauricular area, but they also may be found on the mandibular cheek or on the neck along the anterior border of the sternocleidomastoid muscle (also referred to as congenital cartilaginous rests of the neck, see below)49 (Fig. 64.19). The latter locations reflect the embryologic migration of the external ear from the neck to the side of the head as the mandible develops. Accessory tragi are occasionally multiple (see Fig. 64.19B) and are bilateral in ~10% of affected

CHAPTER

64 Developmental Anomalies

DISEASES AFFECTING THE SKIN THAT ARE ASSOCIATED WITH CLEFT LIP AND/OR PALATE

individuals. They are typically covered by vellus hairs and can be either soft or firm due to a cartilaginous core48. Although they usually represent an isolated malformation, accessory tragi are sometimes associated with other developmental anomalies of the first branchial arch, such as cleft lip and palate50. Together with ipsilateral facial hypoplasia, ear deformities, epibulbar dermoids, and vertebral abnormalities, accessory tragi are a cardinal feature of hemifacial microsomia (Goldenhar syndrome). Accessory tragi may be seen in a number of other multiple congenital anomaly syndromes, including Nager acrofacial dysostosis, Townes–Brocks syndrome, Treacher Collins–Franceschetti syndrome, VACTERL association, Wildervanck syndrome, and Wolf–Hirschhorn syndrome (www.ncbi.nlm.nih.gov/ omim). Isolated accessory tragi may be associated with an increased risk of hearing impairment, but large controlled studies have failed to confirm a purported association between isolated accessory tragi and urinary tract abnormalities. Histologically, accessory tragi are polypoid lesions with numerous tiny, mature hair follicles, a prominent connective tissue framework within abundant subcutaneous fat, and often a central plate of elastic cartilage. When accessory tragi are surgically excised for cosmetic reasons, care must be taken to remove any protruding portion of underlying cartilage49. Evaluation of an infant with an accessory tragus should include assessment of hearing and examination for other dysmorphic features.

Congenital Cartilaginous Rests of the Neck Synonyms:  ■ Wattles ■ Cervical accessory tragi ■ Cutaneous cervical tabs

Congenital cartilaginous rests of the neck are branchial arch remnants that are considered to be the cervical variant of accessory tragi (see above). The alternative term “wattle” refers to the fleshy appendage that hangs from the throat of certain animals, such as turkeys and goats. Typically located over the lower anterior border of the sternocleidomastoid muscle (see Fig. 64.19C), these asymptomatic lesions may be unilateral or bilateral, and they are neither cystic nor fistulous. They may be attached to the underlying fascia by a fibrous band, which can be safely transected if excision is desired51.

Branchial Cleft Sinuses and Fistulae Synonym:  ■ Lateral cervical sinuses and fistulae Branchial cleft sinuses most often represent remnants of the second branchial cleft. They are usually detected at birth or during the first few years of life, unlike the more common branchial cleft cysts that lack a primary cutaneous opening and typically present in older children and adults (see Ch. 110). The ostium of a second branchial cleft sinus is located on the lateral lower third of the neck along the anterior border of the sternocleidomastoid muscle and there is frequently a history of mucus discharge; the associated tract extends superiorly in the subcutis and may be palpable. The less common first branchial cleft sinus can manifest with a cutaneous opening located higher on the neck or in the periauricular region. Approximately 70% of branchial cleft sinuses are located on the right and 5–10% are bilateral. There may be a history of recurrent infection, and a skin tag, sometimes with a cartilaginous component, can mark the ostium. Most branchial sinus tracts end blindly, but occasionally there is a fistulous connection with the tonsillar fossa of the pharynx or the external auditory canal52. Rarely, thyroid or squamous cell carcinoma develops within branchial cleft remnants. Although usually an isolated malformation, branchial cleft sinuses and fistulae are also features of several multiple congenital anomaly syndromes. These include the branchio-otic and branchio-oto-renal syndromes, autosomal dominant disorders that also feature ear pits, hearing loss, and, in the latter, renal anomalies. These syndromes can be caused by mutations in the EYA1 (both conditions), SIX1 (branchio-otic), and SIX5 (branchio-oto-renal) genes, which encode transcription factors that interact within a complex. Atrophic, eroded,

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Fig. 64.19 Accessory tragi. A Typical small preauricular papule. B Multiple skin-colored papulonodules on the mandibular cheek as well as in a preauricular location. C Congenital cartilaginous rest of the neck, which is considered to represent a cervical subtype of accessory tragus.  

or “hemangiomatous” skin overlying branchial cleft sinuses on the neck or in the periauricular area is a distinctive feature of the branchiooculo-facial syndrome that is due to mutations in the gene encoding transcription factor AP2-α. Additional manifestations of this disorder include cleft lip/palate, imperforate nasolacrimal ducts, eye and ear anomalies, and early graying of the hair. Histologically, a branchial sinus may be lined by stratified squamous or pseudostratified ciliated columnar epithelium. In order to prevent infectious complications, complete surgical excision of branchial sinuses and fistulae is indicated. Imaging may be helpful in delineating the course and extent of the lesion, although recommendations vary among otolaryngologists. Preoperative options include CT fistulography and MRI; in addition, intraoperative contrast fistulography and/or injection of methylene blue dye can be considered52,53.

Fig. 64.20 “Milk lines”. Supernumerary nipples and other forms of accessory mammary tissue represent focal remnants of the embryologic mammary ridges that extend from the anterior axillary fold to the upper medial thigh bilaterally.  

MILK LINES

Mammary tissue

Supernumerary Nipples and Other Forms of Accessory Mammary Tissue Synonyms:  ■ Accessory nipples, polythelia ■ Pseudomamma (nipple + areola) ■ Supernumerary breasts, polymastia

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Supernumerary nipples and other forms of accessory mammary tissue are remnants of the embryologic mammary ridges or “milk lines”, symmetric ectodermal thickenings that extend from the anterior axillary fold to the upper medial thigh (Fig. 64.20). Normally, there is further development in the pectoral region to form the nipples, while the remainder of the milk line regresses; focal areas of persistence result in accessory mammary tissue. Supernumerary nipples, the most common type of accessory mammary tissue, are found in 1–6% of the population54. They usually represent a sporadic developmental anomaly, although ~10% of cases are familial. The incidence of supernumerary nipples is similar in men and women. However, in women, accessory mammary tissue often becomes more apparent at puberty or during pregnancy. Conversely, changes in supernumerary nipples may actually represent an early cutaneous sign of pregnancy. Supernumerary nipples are most commonly seen on the inframammary chest, but they may be located anywhere along the milk lines (including the vulva) and occasionally in other sites such as the upper back, shoulder, posterior thigh, face, neck, or even foot. In addition, supernumerary nipples sometimes overlie the primary nipple or areola. Lesions are most often single, but they may be multiple and/or bilateral. Supernumerary nipples typically present as a small, soft, pink or brown papule, with or without a surrounding areola (Fig. 64.21). An areola also can also develop in the absence of a nipple, and ectopic glandular

breast tissue can be isolated or associated with a nipple and/or areola. When only breast tissue is present, it is most often located in the axilla or vulva and may demonstrate all of the functional changes of normal breasts, from tenderness and swelling related to the menstrual cycle to lactation through pores in the overlying skin. Of note, a tuft of hair located along the milk lines may be a marker of underlying mammary tissue (polythelia pilosa)55. A number of other abnormalities have been described in patients with supernumerary nipples. The association between supernumerary nipples and malformations of the kidneys and urinary tract is controversial. Although early reports supported the existence of a “supernumerary nipple/renal field defect”, several controlled studies failed to confirm this association56. However, a few studies have found supernumerary nipples to be significantly more common in patients with urogenital or renal malignancies than in control groups57. An increased incidence of predominantly ipsilateral Becker melanosis (nevus) has



Courtesy, Jean L Bolognia.

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Absent, Hypoplastic or Anomalous Nipples Synonyms:  ■ Athelia ■ Amastia ■ Hypomastia Absence or hypoplasia of the nipples may occur either as an isolated developmental abnormality or together with other malformations in a variety of congenital syndromes. The Poland anomaly is a predominantly sporadic developmental field defect in which hypoplasia or absence of the nipple and/or breast is associated with ipsilateral aplasia of the sternal head of the pectoralis major muscle, patchy absence of axillary hair, and symbrachydactyly. The Becker nevus syndrome may also include hypoplasia of the ipsilateral nipple, breast, pectoralis major muscle, and/ or arm; it results from mosaic mutations in the beta-actin gene that involve the mesenchymal lineage57a. In addition, nipple and breast hypoplasia or aplasia may occur in association with ectodermal dysplasias, including X-linked hypohidrotic and tricho-odonto-onychial types, as well as the scalp–ear–nipple syndrome (see Table 64.4), limb–mammary syndrome (ectrodactyly, other hand/foot anomalies, and nail dysplasia), ulnar–mammary syndrome (Table 64.6), and ablepharon–macrostomia syndrome. In a rare, lethal form of dwarfism known as Blomstrand chondrodysplasia, loss-of-function mutations in the gene encoding parathyroid hormone receptor 1 result in lack of nipples. Biallelic mutations in the protein tyrosine phosphatase receptor F (PTPRF) gene underlie hypo- or athelia associated with peaked eyebrows58, and a chromosomal translocation disrupting this gene was identified in a woman with amastia and unilateral renal agenesis. Both parathyroid hormone-related protein produced by the mammary bud epithelium and PTPRF produced by surrounding fibroblasts play a role in a Wnt-dependent pathway that regulates embryonic development of the mammary mesenchyme and is required for formation of the nipple and mammary ducts. Inverted nipples are most often inherited as an isolated autosomal dominant trait, but they may also be found in congenital syndromes such as the congenital disorder of glycosylation type Ia. Widely spaced nipples are a feature of congenital disorders including Turner syndrome, Noonan syndrome, cerebro-oculo-facio-skeletal syndrome, renal hypoplasia syndromes, and various chromosomal abnormalities (www.ncbi .nlm.nih.gov/omim).

CHAPTER

64 Developmental Anomalies

Fig. 64.21 Supernumerary nipples on the inframammary chest. A Brown papule that might be mistaken for a melanocytic nevus. B Nipple with a surrounding areola. B,

Skin Dimples Synonym:  ■ Skin fossae %

also been noted in patients with supernumerary nipples. Supernumerary nipples are found in several multiple congenital anomaly syndromes, including Simpson–Golabi–Behmel syndrome, cleft lip/ palate–ectodermal dysplasia syndrome, and tricho-odonto-onychial dysplasia (www.ncbi.nlm.nih.gov/omim). Histologic features of accessory mammary tissue are similar to those of normal breasts. For example, supernumerary nipples show acanthosis, pilosebaceous structures, smooth muscle, and in many cases, mammary glands. Fine-needle aspiration cytology can be helpful for evaluation of an axillary or vulvar mass suspected to represent breast tissue, although an incisional or excisional biopsy may be required for definitive diagnosis. Ectopic glandular breast tissue can develop any of the disorders that occur in normally positioned breasts, including galactorrhea, fibrocystic changes, mastitis, fibroadenomas, and carcinoma. Although such tissue does not have an increased malignant potential compared with the normal breast and prophylactic excision for cancer prevention is not required, routine screening should be performed with periodic physical examination and radiologic studies such as mammography or ultrasonography. Complete surgical excision is the treatment of choice for accessory mammary tissue that is symptomatic or cosmetically undesirable. Most authors do not recommend imaging studies to exclude an associated urinary tract malformation in asymptomatic individuals with accessory mammary tissue as an isolated anomaly.

Skin dimples are deep cutaneous depressions that are seen most commonly on the cheeks or chin, occurring in a familial pattern suggestive of autosomal dominant inheritance. Unilateral or bilateral dimples also may be found in a variety of other locations, most often overlying bony prominences such as the acromion process of the scapula, elbow, patella, tibia, and sacrum. These represent regions in which there is close proximity of the skin to the underlying bone during fetal development, and the dimples are thought to result from early fixation of the skin and deficient formation of the subcutaneous tissue. Bilateral skin dimples on the shoulders overlying the acromion processes can be inherited in an autosomal dominant fashion as an isolated anomaly. In addition, bilateral acromial dimples are a feature of several congenital malformation syndromes, including the 18q deletion syndrome, trisomy 9p syndrome, Say syndrome, and Russell–Silver dwarfism59. Skin dimples also may be seen in association with skeletal abnormalities. For example, dimpling may be found overlying the tibial bend in patients with camptomelic dysplasia and over bowing convexities or exostoses of long bones in those with hypophosphatasia. Distal arthogryposis (“whistling face”) syndrome type 2A features a characteristic H-shaped dimple on the chin. Although shallow coccygeal dimples are a common isolated finding25–27, larger or deeper midline lumbosacral dimples may represent a cutaneous sign of spinal dysraphism (see above) or a malformation syndrome59. Lastly, skin dimples overlying the knees and/or elbows have been reported in association with congenital rubella, Joubert syndrome, limb–mammary syndrome, ulnar– mammary syndrome, and multiple pterygium syndrome (www.ncbi .nlm.nih.gov/omim). In other sites, an enlarging dimple in a young child may indicate a nascent lipoblastoma (see Ch. 117).

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DISEASES AFFECTING THE SKIN THAT ARE ASSOCIATED WITH CONGENITAL DIGITAL ANOMALIES

Digital anomaly (-dactyly) Syndrome

Syn-

Ectro-

Poly-

Clino-

Brachy-

Other features

EEC syndrome*

x

x

AD; ectodermal dysplasia, ectrodactyly, cleft lip/palate

EEM syndrome

x

x

AR, P-cadherin gene; ectodermal dysplasia, ectrodactyly, macular dystrophy

Cleft lip/palate–ectodermal dysplasia

x

See Table 64.5

ED–syndactyly

x

AR, nectin 4 (PVRL4) gene; hypotrichosis with pili torti, hypodontia, PPK

Oculodentodigital dysplasia

x

Scalp–ear–nipple syndrome

x

Ectodermal dysplasias (see Ch. 63) • •









Ulnar–mammary syndrome

x

See Table 64.4 x



Oral–facial–digital syndrome, type 1

x

Goltz syndrome (focal dermal hypoplasia)

x

AD, GJA1 gene; small eyes, enamel hypoplasia, midphalangeal hypoplasia, PPK, hypotrichosis

x

x

TBX3 gene; absent/hypoplastic nipples, ulnar ray defects, genital anomalies, abnormal canine teeth

x

See Table 64.5

x

See Ch. 62

Terminal osseous dysplasia with pigmentary defects

x

x

X-D, filamin A gene; hyperpigmented, atrophic facial macules representing focal dermal hypoplasia, digital fibromas, multiple frenula, hypertelorism

Happle–Tinschert syndrome

x

x

Basaloid follicular hamartomas in a mosaic distribution; dental, skeletal, and cerebral anomalies

Epidermal/sebaceous nevus “syndromes”

x

x

x

See Ch. 62

Mosaicism/hypomelanosis of Ito

x

x

x

See Ch. 62

Klippel–Trenaunay syndrome†

x

x

Proteus syndrome†

x

See Ch. 104 See Ch. 62

Adams–Oliver syndrome

x

Megalencephaly–capillary malformation

x

Waardenburg syndrome, type 3

x

See Ch. 66

Apert syndrome

x

AD, FGFR2 gene; craniosynostosis, severe acne, diffuse pigmentary dilution

Basal cell nevus (Gorlin) syndrome Popliteal pterygium syndrome

x x

See Ch. 104

x

x

x

x

See Ch. 107 See text – congenital lip pits

Trichorhinophalangeal syndrome Congenital anonychia– onychodysplasia

See Table 64.3

x

x

AD, TRPS1 gene; cone-shaped epiphyses, pear-shaped nose, sparse hair

x

See Ch. 71

*Caused by mutations in the TP63 gene; allelic disorders with overlapping manifestations (e.g. ectrodactyly, nipple hypo-/aplasia) include ADULT (acro-dermato-ungual-lacrimal-tooth) syndrome and limb–mammary syndrome.

†Patients often have macrodactyly.

Table 64.6 Diseases affecting the skin that are associated with congenital digital anomalies. Other disorders associated with digital anomalies that also may affect the skin include Cornelia de Lange, Roberts, Simpson–Golabi–Behmel, Pallister–Hall, Russell–Silver, Rubinstein–Taybi and Hurler syndromes, trisomy 13, Fanconi anemia, and the Poland anomaly. Syndactyly, fused digits; ectrodactyly, absent digits resulting in a split hand–foot deformity (“lobster claw”); polydactyly, extra digits; clinodactyly, laterally or medially “bent” digits; brachydactyly, short digits. AD, autosomal dominant; AR, autosomal recessive; PPK, palmoplantar keratoderma; PVRL4, poliovirus receptor-related 4; X-D, X-linked dominant.  

Congenital Malformations of the Dermatoglyphs

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Congenital malformations of the dermatoglyphs (fingerprints) are divided into four main categories based on the appearance of the dermal ridges of which they are composed: (1) ridge aplasia (absent); (2) ridge hypoplasia (poorly formed); (3) ridge dissociation (discontinuous pattern with short segments); and (4) ridges-off-the-end (run off the end of the fingertip rather than looping around). Embryologic development of the dermal ridges occurs in conjunction with that of the eccrine glands of the palms and soles, and the sweat pores are found on the ridges. The lack of eccrine ducts and glands in the palmar skin of patients with ridge aplasia reflects this close relationship60. A recent study found that

variants in the ADAM metallopeptidase with thrombospondin motif 9 antisense RNA 2 (ADAMTS9-AS2) influence the whorls within dermatoglyphs.60a Congenital dermatoglyph malformations of all types can be inherited in an autosomal dominant fashion as an isolated defect. A nonsyndromic form of autosomal dominant adermatoglyphia (“immigration delay disease”) is caused by mutations in a skin-specific isoform of SMARCAD1, a member of the SNF subfamily of the helicase protein superfamily61. In addition, a SMARCAD1 variant of unknown significance was identified in a family with Basan syndrome, a rare autosomal dominant condition characterized by adermatoglyphia together with

Fig. 64.22 Bilateral rudimentary supernumerary digits. The ulnar side of the fifth digit is the most common location, referred to as  

CHAPTER

64 Developmental Anomalies

neonatal acral blistering and profuse facial milia; variable features include acral hypohidrosis, palmoplantar keratoderma, digital contractures, and nail dystrophy. Dermatoglyph malformations can also occur in association with chromosomal abnormalities, malformations of the distal limbs, and ectodermal dysplasias. The latter, which may present with ridge aplasia or hypoplasia, include hypohidrotic ectodermal dysplasia, AEC syndrome (ankyloblepharon, ectodermal dysplasia, cleft lip/palate), dermatopathia pigmentosa reticularis, and Naegeli– Franceschetti–Jadassohn (NFJ) syndrome (see Chs 63 & 67). Ridge dissociation can be seen in patients with Rosenthal–Kloepfer syndrome (acromegaloid changes, cutis verticis gyrata, and corneal leukoma) and cystic fibrosis. The spectrum of abnormal dermatoglyphs includes an acquired loss as is seen in Kindler syndrome and dyskeratosis congenita (see Chs 32 & 67) and the stippled dermatoglyphs (pachydermatoglyphia) found in Costello syndrome, KID (keratitis–ichthyosis–deafness) syndrome, and hidrotic ectodermal dysplasia (see Chs 55, 57 & 63). Lastly, aberrant dermatoglyph patterns have been used to screen for a predisposition to early childhood dental caries, congenital orodental anomalies, neurodevelopmental disorders, and schizophrenia.

Rudimentary Polydactyly Synonym:  ■ Rudimentary supernumerary digits Rudimentary polydactyly represents duplication of digital soft tissue, but without a skeletal component. It is typically found on the lateral surface of a digit, more often the ulnar side of the fifth finger (postaxial) than the radial side of the thumb (preaxial). Rudimentary polydactyly is present in ~0.5–1 per 1000 white neonates and ~3–10 per 1000 black neonates. It usually occurs as an isolated malformation with autosomal dominant inheritance; underlying mutations have been identified in GLI family zinc finger 3 (GLI3) and other genes. The stump remaining after intrauterine amputation of a larger structure is sometimes referred to as an amputation neuroma. Rudimentary polydactyly lesions are frequently bilateral and range from small, fleshy or wart-like papules (Fig. 64.22) to larger, often pedunculated nodules that may contain cartilage or a vestigial nail. Congenital ectopic nails located on the tips of the fifth fingers are regarded as a separate entity. Histologically, rudimentary supernumerary digits often show fascicles of nerve fibers in a pattern similar to that of an acquired neuroma (see Ch. 115). When removal is desired, surgical excision is the method of choice62. Removal via ligation with suture material increases the risk of infection and often leaves a residual papule, which may result in a painful neuroma later in life.

Amniotic Band Sequence and Disorganization Syndrome Synonyms:  ■ Amniotic band syndrome ■ Amniotic rupture sequence Congenital constriction bands ■ ADAM (amniotic deformity, adhesions and mutilations) complex ■

The amniotic band sequence (ABS) encompasses a variety of congenital anomalies of the limbs, head, body wall, and viscera with asymmetric, seemingly random distribution patterns that do not correspond to embryonic fusion planes. Characteristic findings include constriction rings and amputations of the limbs and digits that are associated with fibrous bands. Occurring in ~1–10 per 10 000 live births, ABS is primarily a sporadic disorder, although familial cases and one patient with a mutation in the IQ motif-containing K gene (IQCK) have been reported. ABS may be more common in children born to primiparous versus multiparous women63. Pseudoamniotic band syndrome is a rare complication of invasive intrauterine procedures in monochorionic twins. There are two classic hypotheses for the pathogenesis of ABS. The extrinsic theory postulates that rupture and repair of the amniotic

membrane during the first trimester is followed by loss of amniotic fluid and entanglement of fetal parts in fibrous strands of torn amnion, which form rings that encircle and constrict the limbs, face, or trunk. The intrinsic theory proposes that an abnormal endogenous developmental process leads to production of fibrous bands as well as other anomalies (e.g. internal malformations, duplicated structures) not explained by bands alone. Although the extrinsic theory has traditionally been more widely accepted, the striking similarities between ABS and the human “disorganization syndrome” as well as the mouse disorganization mutant provide support for an intrinsic mechanism64. The disorganization syndrome features a haphazard pattern of defects, most often limb duplications, reductions and circumferential constrictions with attached fibrous bands; hamartomatous digit-like appendages and craniofacial > truncal clefts represent additional features. Alternatively, fibrosis due to altered activation of the epithelial–mesenchymal transition process during embryogenesis has been hypothesized. The clinical spectrum of ABS is broad, ranging from isolated minor limb anomalies to major craniofacial and visceral defects. It includes the limb–body wall complex characterized by body wall defects with evisceration of thoracic and/or abdominal organs, irregular anencephaly/ encephaloceles, and bizarre facial clefting65. Variations in severity may depend upon differences in the timing of amniotic rupture or variable expressivity of genetic trait(s). Constriction rings present as circumferential grooves of variable depth on the digits, extremities, neck, or trunk; this must be distinguished from the circumferential creases of the “Michelin tire baby” syndrome (see Ch. 97). Deep lesions located on an extremity may be associated with distal lymphedema, nerve compression, deformity, or intrauterine amputation. Acrosyndactyly can result from a constriction band that encircles adjacent digits. In addition to the distinctive fibrofatty appendages of the disorganization syndrome, other cutaneous manifestations of ABS may include aplasia cutis congenita, often with a stellate morphology, and abnormal dermatoglyphs. Plastic surgery with wound closure via Z-plasty, anterior sheath Y–V plasty, or abdominal Scarpa fascia release is indicated for release of constriction bands that restrict growth, compress underlying nerves, or interfere with vascular and/or lymphatic circulation.

Other Developmental Anomalies Associated With Cutaneous Diseases Skin disorders that are associated with cleft lip/palate or congenital digital anomalies are presented in Tables 64.5 and 64.6, respectively. For additional online figures visit www.expertconsult.com

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CHAPTER

Developmental Anomalies

64

eFig. 64.1 Hair collar sign. Membranous aplasia cutis congenita with a hair collar and an associated capillary malformation. Courtesy, Kalman Watsky, MD.  

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%

eFig. 64.2 Dermoid scalp.  

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eFig. 64.4 Aplasia cutis congenita (ACC). A ACC associated with fetus papyraceus due to the second-trimester death of a co-twin. B Stellate ACC on the lateral trunk of a neonate born of an initial sextuplet gestation for which fetal reduction was performed. The lesions had a bilateral, symmetric distribution. C ACC resulting from congenital varicella. Note the sharply demarcated, deep ulcer on the lower abdominal wall.  

eFig. 64.3 Preauricular skin defects. Multiple discrete, round, atrophic skin defects in an infant, extending from the scalp line toward the angle of the mouth in a strikingly linear arrangement (arrows). Courtesy, Jean L Bolognia, MD.  

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SECTION

Genodermatoses

9

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Online only content eFig. 64.5 Supernumerary nipple. Note the supernumerary nipple with a surrounding areola in a typical location on the inframammary  

PIGMENTARY DISORDERS SECTION 10

Melanocyte Biology Jean L. Bolognia and Seth J. Orlow

Key features ■ The major determinant of normal skin color is the activity of melanocytes, i.e. the quantity and quality of pigment production, not the density of melanocytes ■ Melanocytes contain a unique intracytoplasmic organelle, the melanosome, which is the site of melanin synthesis and deposition ■ Compared with lightly pigmented skin, darkly pigmented skin has melanosomes that contain more melanin and are larger; once transferred to keratinocytes, the melanosomes are singly dispersed and degraded more slowly ■ Tyrosinase is the key enzyme in the melanin biosynthetic pathway ■ Two major forms of melanin are produced in melanocytes: brown–black eumelanin and yellow–red pheomelanin ■ The production of eumelanin versus pheomelanin is influenced by the binding of melanocyte stimulating hormone to the melanocortin 1 receptor

INTRODUCTION In order to understand the underlying pathophysiology of cutaneous disorders of hypopigmentation and hyperpigmentation, as well as the process of normal physiologic pigment production, an apprecia­ tion of the structure and function of the melanocyte is required. A classic example of basic pathogenesis is type 1 oculocutaneous albi­ nism (OCA1), in which pigmentary dilution of the skin, hair, and eyes is due to a reduction or absence of tyrosinase activity secondary to mutations in both copies of the tyrosinase gene (TYR). Within the realm of physiologic pigmentation, melanocytes in individuals with red hair often express variants of the melanocortin 1 receptor (MC1R)1. As a consequence of the altered amino acid sequences of the variant MC1Rs, their cell surface expression and interactions with melanocyte stimulating hormone (MSH) can be affected, leading to an increase in the production of pheomelanin as opposed to eumelanin. Based upon population genetics, genes that are mutated in OCA (e.g. TYR, OCA2, TYRP1, SLC45A2, SLC24A5) also influence normal pigment variation (Table 65.1)2–6. The major sections in this chapter are: the origin and function of the melanocyte the formation and function of the melanosome regulation of melanin biosynthesis.

• • •

ORIGIN AND FUNCTION OF THE MELANOCYTE The melanocyte is a neural crest-derived cell, and during embryogenesis precursor cells (melanoblasts) migrate along a dorsolateral then ventral pathway via the mesenchyme to reach the epidermis and hair follicles of the trunk (see Ch. 2). More recently, it was shown that cutaneous melanocytes can also arise from neural crest-derived Schwann cell precursors that migrate along nerves to the skin via a distinct ventral pathway7. Additional sites of melanocyte migration include the uveal tract of the eye (choroid, ciliary body, and iris), the leptomeninges, and the inner ear (cochlea) (Fig. 65.1). Presumably, the death of melanocytes within the leptomeninges, inner ear, and skin is responsible for the aseptic meningitis, auditory symptoms, and areas of vitiligo, respec­ tively, seen in patients with the Vogt–Koyanagi–Harada syndrome (see Ch. 66).

65 

In the inner ear, particularly in the stria vascularis, melanocytes are thought to play a role in the development of hearing. Aberrant migra­ tion or survival of melanocytes within the inner ear, the iris, and midportions of the forehead and extremities explains the presence of congenital deafness, heterochromia irides, and patches of leukoderma, respectively, in patients with Waardenburg syndrome, the classic neuro­ cristopathy. Also, aberrant migration or survival of enteric ganglion cells, another neural crest-derived cell population, provides an explana­ tion for the association of aganglionic megacolon (Hirschsprung disease) with Waardenburg syndrome or rarely piebaldism. The survival and migration of neural crest-derived cells during embryogenesis depends upon interactions between specific receptors on their cell surface and extracellular ligands. For example, KIT ligand (also known as steel factor or stem cell growth factor) binds to the transmembrane KIT receptor on melanocytes and melanocyte precur­ sors (melanoblasts) (Figs 65.2 & 65.3); melanoblasts require expression of the KIT receptor in order to maintain their normal chemotactic migration directed by production of KIT ligand by the dermamyotome. Heterozygous germline mutations in KIT that decrease the ability of the KIT receptor to be activated by KIT ligand are responsible for human piebaldism, whereas in mice, mutations in either kit or steel can lead to white spotting. In the developing embryo, melanoblasts expressing endothelin receptor type B (EDNRB) are stimulated to migrate by endothelin-3 (ET3 [EDN3]), which is produced by the ecto­ derm and dermamyotome. Mutations in one or both copies of EDN3 or EDNRB can result in Waardenburg syndrome plus aganglionic mega­ colon (see Fig. 65.3). Transcription factors represent another group of proteins that play an essential role during embryogenesis. Because transcription factors can bind DNA and influence the activity of other genes, they are able to regulate the complex interplay of various sets of genes that is required for embryonic development. Several of the genes that, when mutated, give rise to Waardenburg syndrome encode transcription factors (e.g. PAX3, MITF, SOX10; see Table 66.4). Fig. 65.4 demonstrates some of these interactions (e.g. PAX3 and SOX10 can control expression of MITF)8,9. MITF is sometimes referred to as the master regulator of melanocyte development and function given its modulation of mul­ tiple differentiation genes and its early up-regulation in neural crest cells that will eventually become melanocytes and emigrate from the dorsal neural tube. During embryogenesis, melanin-producing melanocytes are found diffusely throughout the dermis. They first appear in the head and neck region at ~10 weeks of gestation. However, by the end of gestation, active dermal melanocytes have “disappeared”, except in three primary anatomic locations – the head and neck, the dorsal aspects of the distal extremities, and the presacral area10. Some of the dermal melanocytes have clearly migrated into the epidermis, but, given the absolute numbers of cells in the two compartments, apoptosis of pigment cells has also occurred. The three sites where active dermal melanocytes are still present at the time of birth coincide with the most common sites for dermal melanocytoses and dermal melanocytomas (blue nevi). Hepatocyte growth factor may play a role in the survival and prolifera­ tion of these dermal melanocytes as well as somatic activating muta­ tions in GNA11 and GNAQ, which encode G proteins and are found in blue nevi (see Table 112.3). As depicted in Fig. 65.1, melanocytes also migrate to the basal layer of the hair matrix and the outer root sheath of hair follicles. Cells that are actively producing melanin are easily recognized in the matrices of pigmented anagen hairs, whereas melanocytes within the outer root sheath are usually amelanotic and more difficult to identify11. It has been hypothesized that there are two populations of melanocytes in the skin, one in the interfollicular epidermis and the second in the hair

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The major determinant of normal skin color is the activity of melano­ cytes, i.e. the quantity and quality of pigment production, not the density of melanocytes. Melanocytes contain a unique intracytoplasmic organelle, the melanosome, which is the site of melanin synthesis and deposition. Compared with lightly pigmented skin, darkly pigmented skin has melanosomes that contain more melanin and are larger; once transferred to keratinocytes, the melanosomes are singly dispersed and degraded more slowly. Tyrosinase is the key enzyme in the melanin biosynthetic pathway and the two major forms of melanin produced in melanocytes are brown–black eumelanin and yellow–red pheomelanin. The production of eumelanin versus pheomelanin is influenced by the binding of melanocyte stimulating hormone to the melanocortin 1 receptor.

melanocyte, melanosome, tyrosinase, eumelanin, pheomelanin, melanocortin 1 receptor, MC1R, melanocyte stimulating hormone, MSH, pigmentation, agouti, melanin biosynthetic pathway

CHAPTER

65 Melanocyte Biology

ABSTRACT

non-print metadata KEYWORDS:

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DISORDERS CHARACTERIZED BY DIFFUSE PIGMENTARY DILUTION IN WHICH THE GENETIC DEFECT IS KNOWN

Disorder SECTION

Pigmentary Disorders

10

Gene

Protein product

Comments

Oculocutaneous albinism (OCA) [~40% of patients have OCA1 and ~50% have OCA2] TYR

OCA1A

Tyrosinase

Complete absence of tyrosinase activity and melanin production Retention of misfolded tyrosinase protein within the ER

• •

TYR

OCA1B

Tyrosinase

Decreased tyrosinase activity; can produce pheomelanin Variant with temperature-sensitive tyrosinase (normal activity at 35°C, but diminished at 37°C) • Additional variants: minimal pigment, platinum, yellow • •

OCA2

OCA2

TYRP1

OCA3

SLC45A2

OCA4

P protein (OCA2 was previously known as P) Tyrosinase-related protein 1*

Melanosomal transmembrane protein that is also present in the ER Possible functions include regulating organelle pH, facilitating vacuolar accumulation of glutathione, and processing/trafficking of tyrosinase

• •

TYRP1 stabilizes tyrosinase in mice and humans, and it can function as a DHICA oxidase Both “mutant” TYRP1 and tyrosinase are retained in the ER and then degraded • Rufous phenotype ≫ brown phenotype; latter seen in OCA2 • •

Solute carrier family 45 member 2 (previously known as MATP)



Variable phenotype, with hair ranging from white to yellow–brown; most common in Asians Transmembrane transporter with a role in tyrosinase processing and intracellular trafficking of proteins to the melanosome



OCA5

Not known





OCA6

SLC24A5

Solute carrier family 24 member 5



OCA7

C10orf11

Chromosome 10 open reading frame 11



Locus linked to 4q24 Cation exchanger that may be involved in ion transport in melanosomes Expressed in melanoblasts and melanocytes Possible role in melanocyte differentiation



Hermansky–Pudlak syndrome (HPS)† HPS1

HPS1

HPS1 (BLOC-3 subunit 1)



HPS2

AP3B1

Adaptor related protein complex 3 β1 subunit



HPS3

HPS3

HPS3 (BLOC-2 subunit 1)



HPS4

HPS4

HPS4 (BLOC-3 subunit 2)



Defective trafficking of organelle-specific proteins to melanosomes, lysosomes and cytoplasmic granules (including platelet dense granules and lytic granules in cytotoxic T lymphocytes) • Pulmonary fibrosis and granulomatous colitis • Component of BLOC-3 (see Fig. 65.8) AP-3 recognizes sorting signals within cytosolic tails of cargo molecules and is involved in the trafficking of proteins from the trans-Golgi network to appropriate organelles (see Fig. 65.8) • Pulmonary fibrosis (some patients) • Abnormal targeting of CD1 may play a role in associated immunodeficiency Component of BLOC-2 Pulmonary fibrosis Component of BLOC-3



HPS5

HPS5

HPS5 (BLOC-2 subunit 2)



HPS6

HPS6

HPS6 (BLOC-2 subunit 3)



HPS7

DTNBP1

Dystrobrevin binding protein 1



HPS8

BLOC1S3

BLOC1S3 (BLOC-1 subunit 3)



HPS9

BLOC1S6

BLOC1S6 (BLOC-1 subunit 6)



HPS10

AP3D1

Adaptor related protein complex 3 δ1 subunit



Component of BLOC-2 Component of BLOC-2 Component of BLOC-1 Component of BLOC-1 Component of BLOC-1 See AP-3 above Neurologic impairment (e.g. seizures), immunodeficiency



Chédiak–Higashi syndrome LYST

Lysosomal trafficking regulator



Abnormal vesicle trafficking and fission/fusion of lysosome-related organelles result in giant organelles (e.g. melanosomes, neutrophil granules [lysosomes], platelet dense granules)

Griscelli syndrome GS1

MYO5A

Myosin Va (attaches melanosomes to actin filaments)



GS2

RAB27A

RAB27A (melanosomal membrane GTPase that binds melanophilin)



GS3

MLPH

Melanophilin (links myosin Va and RAB27A)



MYO5A

Myosin Va F-exon deletion



In all three forms, melanosomes are retained in the body of the melanocyte rather than trafficking to the tips of dendrites for transfer to keratinocytes (see Fig. 65.10) • Silvery hair seen in all three forms • Myosin Va expressed in neurons (as well as melanocytes) and dysfunction leads to neurologic abnormalities GTPase also expressed in hematopoietic cells; defective release of granule contents from cytotoxic T cells leads to recurrent infections and hemophagocytic syndrome Melanophilin only expressed in melanocytes, so only pigmentary dilution in type 3 F-exon only expressed in melanocytes

*† Recognized by Mel-5 antibody.

Reflecting a founder effect, individuals of Puerto Rican origin have HPS1 and HPS3 (3 : 1 ratio); non-Puerto Ricans most commonly have HPS1, followed by HPS3 and HPS4 with ~70% of patients having one of these three types.

Table 65.1 Disorders characterized by diffuse pigmentary dilution in which the genetic defect is known. See Chapter 66 for details of clinical findings. BLOC-1 promotes endosomal maturation by recruiting the Rab5 GTPase-activating protein Msb3; BLOC-2 targets recycling endosomal tubules to melanosomes for cargo delivery; BLOC-3 functions as a Rab32/38 guanine nucleotide exchange factor that is capable of activating small GTPases (activated Rab 32/38 is needed for transport of tyrosinase and TYRP1 to melanosomes). AP-3, adaptor protein complex 3; BLOC, biogenesis of lysosome-related organelles complex; DHICA, 5,6-dihydroxyindole-2-carboxylic acid; ER, endoplasmic reticulum; MATP, membrane associated transporter protein; TYRP, tyrosinase-related protein.  

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ACTIVATION OF THE KIT RECEPTOR ON MELANOCYTES

MIGRATION OF MELANOCYTES FROM THE NEURAL CREST

CHAPTER

Eye cell membrane KIT receptor Iris

Choroid

extracellular

Retina

intracellular

Melanocyte Biology

65

KIT ligand (steel factor)

Skin Neural tube (optic cup) P Tyr-

Tyr-

Neural crest

inactive Schwann cell precursor along nerve

-Tyr P active

Fig. 65.2 Activation of the KIT receptor on melanocytes. Because the KIT receptor is a tyrosine kinase receptor, it has the ability to phosphorylate the tyrosine residues of other proteins as well as itself, i.e. autophosphorylation. Heterozygous germline mutations in KIT that prevent the activation of the KIT receptor by KIT ligand, also referred to as steel factor, lead to piebaldism, whereas somatic activating mutations in KIT are seen in patients with mastocytosis as well as melanomas arising in acral sites, mucosae, and chronically photodamaged skin (see Figs 118.2 & 113.1). A form of familial progressive hyperpigmentation with or without hypopigmentation can result from heterozygous gain-of-function germline mutations in the gene that encodes KIT ligand49. P, phosphorylation; Tyr, tyrosine.  

Inner ear Medulla oblongata (leptomeninges)

Fig. 65.1 Migration of melanocytes from the neural crest. Melanocytes migrate to the uveal tract of the eye (iris, ciliary body, and choroid), the leptomeninges, and the cochlea of the inner ear, as well as to the epidermis and hair follicle. Cutaneous melanocytes can also arise from Schwann cell precursors located along nerves in the skin, which also originate from the neural crest. The retina actually represents an outpouching of the neural tube.  

RECEPTOR–LIGAND INTERACTIONS IN PRECURSORS OF MELANOCYTES

melanoblast or enteric neural crest-derived cell

follicle12. Based upon antigen expression and clinical observations, it is the former that is more sensitive to the destructive forces of vitiligo. As a result, repigmentation of patches of vitiligo in which the hairs are still pigmented relies upon activation and subsequent upward migra­ tion of the melanocytes present in the outer root sheath11. Of note, melanocyte stem cells have been identified within the lower portion of the hair follicle bulge, i.e. the lowermost permanent portion of the hair follicle (see Fig. 2.6). In addition, KROX20+ cells, which give rise to the hair shaft, have recently been identified within the hair bulb. These hair progenitor cells produce stem cell factor (SCF) which was shown to be essential for hair pigmentation, i.e., mouse hairs turn white when the SCF gene was deleted12a. By immunohistochemical staining, melanocytes are identified within the fetal epidermis as early as 50 days of gestation13. Melanin-containing melanosomes are recognizable by electron microscopy during the fourth month of gestation. Except in benign and malignant neoplasms, mela­ nocytes reside within the basal layer of the epidermis, a location they maintain throughout life (Fig. 65.5). Although the cell body of the melanocyte sits on a specialized region of basal lamina, its dendrites come into contact with keratinocytes as far away as the mid stratum spinosum. This association of a melanocyte with ~30–40 surrounding keratinocytes to which it transfers melanosomes has been called the epidermal melanin unit14. However, melanocytes fail to form desmo­ somal connections with neighboring keratinocytes; their interactions with keratinocytes are via cadherins. Although there is variation in the density of epidermal melanocytes/ mm2 when different regions of the body are analyzed via DOPA-stained epidermal sheets (Fig. 65.6), e.g. the density of melanocytes is greater in the genital region (~1500/mm2) compared with the back (~900/ mm2), there are smaller differences between individuals when the same anatomic site is examined. This is despite the wide variation in

melanoblast

ET3

EDNRB

KIT ligand (steel factor)

KIT receptor

Fig. 65.3 Receptor–ligand interactions in precursors of melanocytes. In the developing embryo, melanoblasts expressing endothelin receptor type B (EDNRB) are stimulated to migrate by endothelin-3 (ET3) which is produced by the ectoderm and dermamyotome. Melanoblasts also require expression of the KIT receptor to maintain their normal chemotactic migration directed by production of KIT ligand/steel factor by the dermamyotome.  

pigmentation seen within the human race. In other words, a person who has minimal baseline pigmentation and an inability to tan has a similar density of melanocytes when compared with a person whose skin is dark brown to black in color. Indeed, even patients with the most severe form of OCA, OCA type 1A, have a normal complement of epidermal melanocytes. The major determinant of normal skin color is the activity of the melanocytes, i.e. the quantity and quality of pigment production, not

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Fig. 65.4 Signal transduction pathways and transcription factors that contribute to melanocyte differentiation. MITF expression is activated early on during the transition from pluripotent neural crest cells to melanoblasts and is required for melanoblast survival8; mutations in MITF lead to Waardenburg syndrome, a classic neurocristopathy. MITF also regulates the expression of multiple pigment genes including those that encode tyrosinase, TYRP1, TYRP2, PMEL/PMEL17/gp100, and MART-1/Melan-A. Additional transcriptional targets are CDK2, CDKN2A, and BCL-2 (whose protein product is an inhibitor of apoptosis)9. Small molecule inhibitors of SIK (salt-inducible kinase) can upregulate MITF, and application of these inhibitors to normal human skin led to an increase in pigmentation54. In mice, Wnt signaling in melanocyte stem cells is critical for hair pigmentation50. Details of how activation of G-protein-coupled receptors leads to an increase in intracellular cAMP is shown in Fig. 65.15. Of note, EDNRB interacts with the G proteins GNAQ and GNA11, and activating mutations in the genes that encode these latter two proteins can lead to blue nevi and phakomatosis pigmentovascularis. cAMP, cyclic adenosine monophosphate; CREB, cAMP response-element binding protein; ET3, endothelin-3; EDNRB, endothelin receptor type B; LEF1, lymphoid enhancer binding factor 1; MC1R, melanocortin 1 receptor; MITF, microphthalmia-associated transcription factor; MSH, melanoctye stimulating hormone; P, phosphorylation; PKA, protein kinase A; SOX10, SRY-box containing gene 10.  

SIGNAL TRANSDUCTION PATHWAYS AND TRANSCRIPTION FACTORS THAT CONTRIBUTE TO MELANOCYTE DIFFERENTIATION SECTION

Pigmentary Disorders

10

α-MS

WNT

H

KIT ligand

MC

1R ET

3

cAMP

KIT receptor β-Catenin

RAS/RAF/ MEK/ERK

ED

PKA

SOX10

LEF1

N

P CREB

PAX3

R

B

MITF (activated)

MITF promoter P MITF Melanogenesis Melanocyte differentiation Melanocyte proliferation Activation and Degradation

Melanocyte survival

Fig. 65.5 A melanocyte residing in the basal layer of the epidermis. In normal skin, approximately every tenth cell in the basal layer is a melanocyte. Melanosomes are transferred from the dendrites of the melanocyte into neighboring keratinocytes of the epidermis, hair matrices and mucous membranes; no transfer occurs in the pigment epithelium of the retina. The epidermal melanin unit refers to the association of a melanocyte with ~30–40 surrounding keratinocytes to which it transfers melanosomes.  

A MELANOCYTE RESIDING IN THE BASAL LAYER OF THE EPIDERMIS

stratum corneum stratum granulosum

epidermis

phagocytosis of tip

stratum spinosum

melanosomes

keratinocyte

dendrite basal layer

melanocyte fusion of membranes

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the density of melanocytes15. Several factors play a role in deter­ mining the level of melanocyte activity; they include specific character­ istics of the individual melanosomes (e.g. their dimensions) as well as both baseline (constitutive) and stimulated (facultative) levels and activity of the enzymes involved in the melanin biosynthetic pathway. The latter are influenced by receptor-mediated interactions with extra­ cellular ligands such as MSH which then influence the expression of transcription factors including MITF (see Fig. 65.4).

dermis

FORMATION AND FUNCTION OF THE MELANOSOME Within the cytoplasm of melanocytes is a unique organelle known as the melanosome, in which melanin pigments are synthesized, depos­ ited, and transported. The melanosome is most closely related to the lysosome16. Through compartmentalization, both organelles provide protection for the remainder of the cell – lysosomes protect against

Fig. 65.6 Dihydroxyphenylalanine (DOPA)-stained epidermal sheet. Following incubation with 5 mM L-DOPA for 4–5 hours, the epidermal melanocytes turn black because they contain the enzyme tyrosinase, which converts DOPA to black DOPA-melanin. Note the multiple dendrites and regular spacing of the melanocytes.  

Fig. 65.7). In patients with OCA1 and OCA3, misfolded tyrosinase or aberrant tyrosinase-related protein 1 (TYRP1) plus tyrosinase polypep­ tides, respectively, accumulate within the endoplasmic reticulum (ER)17. This leads to ER stress and activation of the unfolded protein response (UPR)18. As a result of the UPR, which acts as a form of quality control, these proteins become targets for destruction by proteasomes and there­ fore are not incorporated into melanosomes (see Fig. 65.7 inset). Several of the enzymes in the melanin biosynthetic pathway are glycoproteins that require the attachment of sugars in order to gain full function. For this reason, they undergo post-translational modification in the ER and the Golgi apparatus and then join up with the matrix proteins (e.g. PMEL/PMEL17/gp100) to initiate melanogenesis. The targeting of proteins to the plasma membrane versus intracytoplasmic organelles and the targeting of specific proteins to the correct type of organelle are complicated processes. This triaging requires the equiva­ lent of traffic police within the cell, an example of which is adaptor protein complex 3 (AP-3). Mutations in the gene that encodes the β3A subunit of AP-3 are responsible for a subset of patients with Hermansky– Pudlak syndrome (HPS2)19. Other forms of HPS are due to dysfunction of the proteins that serve as components of biogenesis of lysosomerelated organelles complexes (BLOCs; Fig. 65.8)20. It then follows that these patients have dysfunction of more than one intracytoplasmic organelle, i.e. not just melanosomes but other lysosome-related organ­ elles such as NK cell granules and platelet dense granules (see Table 65.1). The associated hypopigmentation can be explained by the failure to efficiently deliver melanogenic proteins, e.g. tyrosinase, TYRP1, to the melanosome. The progression of a melanosome from an organelle that lacks melanin to one that is fully melanized is arbitrarily divided, for conve­ nience, into four stages (Fig. 65.9). Proteins that play a key role in the biogenesis of early-stage melanosomes are PMEL/PMEL17/ gp100, MART-1/Melan-A, and the ocular albinism type 1 (OA1) G-protein-coupled receptor21. Cleavage and processing of PMEL/

Fig. 65.7 Formation of a melanosome and pathophysiology of oculocutaneous albinism type 1 (OCA1). After glycosylation and processing within the endoplasmic reticulum (ER) and Golgi apparatus, several of the enzymes involved in the formation of melanin (including tyrosinase) are packaged in vesicles and then combine with the matrix proteins (e.g. PMEL/ PMEL17/gp100). As more melanin is deposited within the melanosomes, they migrate into the dendrites in preparation for their transfer into neighboring keratinocytes. In patients with OCA1 and OCA3 (triangular insert), tyrosinase polypeptides are retained too long within the lumen of the RER and then become targets for destruction within proteasomes. Thus, they are not incorporated into melanosomes. The primary matrix protein is PMEL/PMEL17/gp100 (recognized by HMB45 antibody); formation of the matrix fibers requires cleavage of this protein by a proprotein convertase51. Sorting of proteins to the correct organelles is a complex process and it requires regulators such as adaptor protein complex 3 (AP-3; see Fig. 65.8); in the case of tyrosinase, specific dileucine residues in its cytoplasmic tail aid in the sorting. M, matrix proteins; RER, rough endoplasmic reticulum; SER, smooth endoplasmic reticulum; T, tyrosinase.

CHAPTER

65 Melanocyte Biology

pro-enzymes such as proteases and melanosomes protect against melanin precursors (e.g. phenols, quinones) that can oxidize lipid membranes. The melanosome contains both matrix proteins (chiefly PMEL/ PMEL17/gp100), which form a scaffolding upon which the melanin is deposited, and enzymes such as tyrosinase that regulate the biosyn­ thesis of melanin. Following their formation via ribosomes, all these proteins are found within the rough endoplasmic reticulum (RER;



FORMATION OF A MELANOSOME AND PATHOPHYSIOLOGY OF OCA1

late endosome

myosin Va

T

Golgi apparatus T

M RER

ribosome

M proteasome SER

dendrite

T

actin cytoskeleton

plasma membrane

nucleus

abnormal/ misfolded nascent protein (e.g. T in OCA1)

1079

REGULATION OF PROTEIN TRAFFICKING BY ADAPTOR PROTEIN COMPLEX 3 (AP-3) AND BIOGENESIS OF LYSOSOME-RELATED ORGANELLES COMPLEXES (BLOCs) SECTION

10

BLOC-2

Pigmentary Disorders

HPS7 HPS8 HPS9

Lysosome

HPS3 HPS5 HPS6

BLOC-1

Lysosomerelated organelle (e.g. melanosome)

AP-3 HPS2 HPS10

FOUR MAJOR STAGES OF EUMELANIN MELANOSOMES Stage

Description

I

Spherical; no melanin deposition

II

Oval; obvious matrix in the form of parallel longitudinal filaments; minimal deposition of melanin; high tyrosinase activity

III

Oval; moderate deposition of melanin; high tyrosinase activity

IV

Oval; heavy deposition of melanin; electron-opaque; minimum tyrosinase activity

MOVEMENT OF MELANOSOMES WITHIN MELANOCYTE DENDRITES

Electron micrographs

UVR

Fig. 65.9 Four major stages of eumelanin melanosomes. Courtesy, Raymond Boissy,  

PhD.

1080



BLOC-3 HPS1 HPS4

Golgi

Fig. 65.8 Regulation of protein trafficking by adaptor protein complex 3 (AP-3) and biogenesis of lysosome-related organelles complexes (BLOCs). Lysosome-related organelles include melanosomes, platelet dense granules, and lytic granules of cytotoxic lymphocytes and natural killer cells. Subtypes of Hermansky-Pudlak syndrome (HPS) that are associated with a particular BLOC can have similar clinical findings, e.g. patients with HPS1 and HPS4, both members of BLOC-3, develop pulmonary fibrosis and granulomatous colitis.

PMEL17/gp100, an amyloidogenic protein, leads to a fibrillar matrix that acts as a scaffold upon which melanin is deposited22. As melanin is deposited within the melanosome, the organelle migrates via micro­ tubules into the dendrites in preparation for transfer into the neighbor­ ing keratinocytes, either within the epidermis or within the anagen hair matrix. In addition to microtubules, proteins such as kinesin and dynein are involved in the movement of melanosomes (Fig. 65.10)23. Within the dendrites, there is a specialized myosin protein, myosin Va, that aids in the process of melanosome transfer by assisting attach­ ment between the actin cytoskeleton beneath the plasma membrane and the organelle itself. RAB27A and melanophilin also play a role in ensuring this attachment. The importance of the interactions between these three proteins – myosin Va, RAB27A, and melanophilin – is illustrated by the three different forms of Griscelli syndrome in which there are mutations in the respective genes (see Table 65.1)24,25. The various phenotypes are explained by the tissue-specific expression of these three genes, e.g. neurons versus cytotoxic T cells. All three genes are expressed in melanocytes and as expected, the associated diffuse pigmentary dilution is a reflection of a lack of transfer of melano­ somes from the melanocytes to nearby keratinocytes. Histologically, numerous melanosomes are seen to congregate within the center of the melanocytes. To reiterate, normal pigmentation of the skin is dependent on an orderly transfer of melanosomes from melanocytes to keratinocytes. When this transfer is disrupted, either in inherited diseases such as Griscelli syndrome or in acquired diseases such as atopic dermatitis, the result is hypopigmentation. In the former there is diffuse pigmentary

Microtubule

Myosin Va

Actin filament

Melanophilin

Melanosome

RAB27A

Kinesin

Dynactin

Dynein

Fig. 65.10 Movement of melanosomes within melanocyte dendrites. As melanin is deposited within melanosomes, they migrate along microtubules from the cell body into dendrites in preparation for transfer to keratinocytes. Kinesin and dynein serve as molecular motors for microtubule-associated anterograde and retrograde melanosomal transport, respectively, and UVR results in augmented anterograde transport via increased kinesin and decreased dynein activity. Myosin Va, which is linked to the melanosomal RAB27A GTPase by melanophilin, captures mature melanosomes when they reach the cell periphery and attaches them to the actin cytoskeleton.  

dilution, whereas in the latter the hypopigmentation is circumscribed. Phagocytosis of melanosomes by keratinocytes can be triggered by acti­ vation of the keratinocyte growth factor (KGF) receptor (KGFR/FGFR2b) by KGF, also referred to as fibroblast growth factor 726, as well as by acti­ vation of protease-activated receptor 2 (PAR-2)27. Inhibitors of PAR-2 receptor–ligand interactions, e.g. inhibitors of serine proteases, have led to cutaneous hypopigmentation in animal models28. In summary, it is the activity of the melanocytes and their interac­ tions with neighboring keratinocytes, not their density, that is the major determinant of normal skin color. The activity of a melanocyte is reflected in the number and size of melanized melanosomes it pro­ duces as well as in its efficiency at transferring those melanosomes to keratinocytes. For example, primarily stage II and stage III melano­ somes are seen in lightly pigmented skin, whereas primarily stage IV melanosomes are seen in darkly pigmented skin (Table 65.2). An

REGULATION OF MELANIN BIOSYNTHESIS

VARIATION OF PREDOMINANT MELANOSOMAL STAGES WITH LEVEL OF CUTANEOUS PIGMENTATION

Predominant melanosomal stages

CHAPTER

Pigmentation of skin

Melanocytes

Keratinocytes

Fair

II, III

Occasional III

Medium

II, III, IV

III, IV

Dark

IV > III

IV

Table 65.2 Variation of predominant melanosomal stages with level of cutaneous pigmentation.  

This section will begin with a review of the melanin biosynthetic pathway and then examine the factors, both external and internal, that can influence the level of melanin production. The “starting material” for the production of melanin, both the brown–black eumelanin and the yellow–red pheomelanin, is the amino acid tyrosine. The key regu­ latory enzyme in the pathway is tyrosinase, which controls the initial biochemical reactions in this pathway (Fig. 65.11). It should then come as no surprise that the initial investigations into the molecular basis of OCA focused on the gene that encodes tyrosinase. In OCA1A, the form of OCA where mutations in both copies of the tyrosinase gene lead to complete loss of enzyme activity, no melanin is found in the hair, skin, or eyes (see Table 65.1). However, in OCA1B, where there is decreased enzyme activity, pheomelanin is produced, especially in the hair as the patient ages. The formation of pheomelanin requires less tyrosinase activity than does the formation of eumelanin (see Fig. 65.11) and therefore the formation of pheomelanin can be thought of as a default pathway. The activity of tyrosinase is enhanced by DOPA and is stabilized by tyrosinase-related protein 1 (TYRP1) (see below). Competitive inhibi­ tors of tyrosinase activity include hydroquinone, which is used to treat disorders of hyperpigmentation such as melasma, and L-phenylalanine. In patients with phenylketonuria (PKU), there is a diffuse pigmentary

65 Melanocyte Biology

additional factor is the rate of degradation of the melanosomes once they are transferred to the surrounding keratinocytes and this is related in part to the size of the individual melanosomes. The smaller mela­ nosomes of lightly pigmented skin are clustered in groups of two to ten within secondary lysosomes in the keratinocytes and are degraded by the mid stratum spinosum (Table 65.3)15. In darkly pigmented skin, the melanosomes are larger and singly dispersed within lysosomes of the keratinocytes; they are degraded more slowly, such that melanin granules can still be found in the stratum corneum.

MELANOSOMES IN LIGHTLY PIGMENTED VERSUS DARKLY PIGMENTED SKIN

Lightly pigmented skin

Darkly pigmented skin

Melanization

Stages II, III

Stage IV

Size (diameter)

0.3–0.5 microns

0.5–0.8 microns

Number per cell

200

Distribution of melanosomes within the lysosomes of keratinocytes

Groups of 2–10

Single

Degradation

Fast

Slow

Table 65.3 Melanosomes in lightly pigmented versus darkly pigmented skin.  

THE MELANIN BIOSYNTHETIC PATHWAY

Tyrosinase CO2H NH2

HO

Tyrosinase

O

CO2H HO NH2

O

Tyrosine

DOPAquinone

CO2H

O

NH2 HO CycloDOPA then DOPA

CO2H NH2

O

DOPAquinone

Dopachrome tautomerase (DCT)/TYRP2 HO + CO2 HO

NH

CO2H

DHICA

CO2H NH2

HO NH2

*

S 5-S-cysteinylDOPA CO2H DQ

O

HO

Cysteine

HO

N

HO

CO2H

HO

NH

DOPAchrome

CD-quinones

DHI DQ

Tyrosinase or TYRP1 O2

DOPA

O2

o-Quinoneimine

DOPA 1, o-Benzothiazine intermediates

DHICA-melanin brown, slightly soluble, intermediate MW

Eumelanin

DHI-melanin black, insoluble, high MW

Pheomelanin yellow/red, alkalisoluble, low MW

*Or 2-S-cysteinylDOPA Fig. 65.11 The melanin biosynthetic pathway. The pathway includes the sites of dysfunction in OCA1 (tyrosinase) and OCA3 (TYRP1). The two major forms of melanin in the skin and hair are brown–black eumelanin and yellow–red pheomelanin. The enzymes are transmembrane proteins located within the melanosome. DHI, 5,6-dihydroxyindole; DHICA, 5,6-dihydroxyindole-2-carboxylic acid; DOPA, dihydroxyphenylalanine; MW, molecular weight; TYRP, tyrosinase-related protein.  

Adapted from Hearing VJ. Determination of melanin synthetic pathways. J Invest Dermatol. 2011;131:E8–E11.

1081

SECTION

Pigmentary Disorders

10

dilution due to elevated levels of L-phenylalanine resulting from a deficiency in the enzyme L-phenylalanine hydroxylase that converts L-phenylalanine to L-tyrosine15. The characteristic blonde hair of PKU can undergo darkening when the patient is on a low-phenylalanine diet. Of note, tyrosinase is a copper-requiring enzyme and it has two copperbinding sites. Rare cases of copper deficiency can lead to diffuse cutane­ ous pigmentary dilution, and in patients with Menkes disease, where a transmembrane Cu2+-transporting ATPase that delivers copper to the trans-Golgi network and melanosomes is dysfunctional29, the kinky hair is hypopigmented. In a test tube, L-DOPA can spontaneously oxidize to form melanin, an insoluble biopolymer. For this reason, it was originally thought that tyrosinase was the sole enzyme involved in melanin biosynthesis. However, by the late 1970s, it was becoming clear that there were additional control points in the pathway (see Fig. 65.11). For example, dopachrome tautomerase, also known as tyrosinase-related protein 2 (TYRP2), which like TYRP1 shares similarities in its amino acid sequence with tyrosinase, converts DOPAchrome to 5,6-dihydroxyindole2-carboxylic acid (DHICA). In mice and humans, TYRP1 stabilizes tyrosinase30 and mutations in both copies of TYRP1 lead to OCA3 (see Table 65.1). Decreased function of yet another transmembrane protein, the P protein, leads to OCA231 (Fig. 65.12). Based upon its amino acid sequence, a prediction was made that the P protein was involved in the transport of small molecules across the membrane of the melanosome. Tyrosine, the initial precursor in the melanin biosynthetic pathway, was considered the most likely candidate for transmembrane transport. However, the nature of what might be transported by the P protein remains unclear. Data suggest that the P protein regulates processing and trafficking of tyrosinase, possibly via control of pH or glutathione content within intracellular compartments32. Melanins represent a group of complex polymers whose functions vary from camouflage to the quenching of oxidative free radicals gener­ ated via exposure to UV radiation (UVR). The level and type of melanin production is a complex interplay of the activity of the various enzymes involved in the biosynthetic pathway as well as the activity of proteins such as the P protein and those that stabilize the activity of tyrosinase (e.g. TYRP1). Several factors are known to influence the activity of these key proteins of melanogenesis, and they include α-MSH, basic fibroblast growth factor (bFGF), endothelin-1, KIT ligand, and UVR (see below).

Among the multiple protein products of the proopiomelanocortin (POMC) gene are adrenocorticotropic hormone (ACTH), β-endorphin, and the three forms of MSH (α, β, and γ) (Fig. 65.13); in humans, α-MSH represents the major biologically active form of MSH. The primary site of expression of POMC is the pituitary gland; however, other sites of expression include the testis, the endothelium, and, of particular importance, epidermal keratinocytes. Although MSH is clas­ sically associated with the pigmentary system, this peptide has a wide range of biologic properties, including suppression of inflammation and regulation of body weight. For example, mutations in POMC can result in severe early-onset obesity, adrenal insufficiency, and red hair33. It then follows that mutations in the genes that encode the melanocortin receptors to which the protein products of POMC bind can lead to similar clinical findings; for example, mutations in MC4R are associ­ ated with morbid obesity and variant alleles in MC1R are associated with red hair (see below). Of note, subcutaneous afamelanotide (4-norleucyl-7-phenylalanine-α-MSH), which has enhanced binding to MC1R compared to α-MSH, can lead to cutaneous hyperpigmentation. When subcutaneous implants of afamelanotide were administered monthly, patients with erythropoietic protoporphyria experienced fewer phototoxic reactions and could tolerate more direct sunlight without pain while patients with vitiligo had more rapid and extensive repig­ mentation in response to treatment with UVB. As outlined in Table 65.4, there are five major melanocortin receptors, all of which have seven transmembrane domains (Fig. 65.14). Although the MC1R is present on a variety of cells within the skin, from endothe­ lial cells to fibroblasts, the highest density of this receptor is found on melanocytes34. As in the case of the β-adrenergic receptor, the MC1R is a G-protein-coupled receptor, i.e. it uses proteins that bind guanosine triphosphate (GTP) and guanosine diphosphate (GDP) as intermediary messengers (Fig. 65.15). Following the binding of MSH to the MC1R, the protein pair interacts with a complex of G proteins. The GTP-Gsα subunit then activates adenylate cyclase, leading to increased produc­ tion of cyclic adenosine monophosphate (cAMP) within the melanocyte. An increase in the intracellular concentration of cAMP leads to an increase in tyrosinase activity and eumelanin production via MITF (see Fig. 65.4). If the MC1R is dysfunctional and fails to initiate a significant rise in the intracellular level of cAMP, then pheomelanogenesis is favored (Fig. 65.16). Of note, the majority of individuals with red hair are compound heterozygotes or homozygotes for a variant R allele in the gene that encodes the MC1R1,35 (see Fig. 65.14). MC1R also interacts with a protein known as the agouti protein (mouse) or agouti signaling protein (ASIP; human). Agouti is a term

THE P PROTEIN WITHIN THE LIPID BILAYER POST-TRANSLATIONAL PROCESSING OF THE POMC POLYPEPTIDE Cytoplasmic

NH3+

POMC

1

241

COO–

174 180

352 347

352 354

407 401

419 424

533 530

617 621

670 664

676 680

742 737

759 761

837 834

1

2

3

4

5

6

7

8

9

10

11

12

721 718

777 780

818 812

PC1

− −

196 199

331 329

370 372

385 382



440 449

514 503

637 648

648 645

PC2

+

696 701

Pro γ-MSH

JP

ACTH1-17

ACTH

β-LPH

β-END

des α-MSH Luminal ac α-MSH

Fig. 65.12 The P protein within the lipid bilayer. The polypeptide has 12 putative transmembrane domains. The solute carrier family 45 member 2 (previously known as membrane-associated transporter protein), which is dysfunctional in OCA4, has a similar configuration within the plasma membrane. Adapted from Rinchik EM, Bultman SJ, Horsthemke B, et al. A gene for the mouse  

1082

pink-eyed dilution locus and for human type II oculocutaneous albinism. Nature. 1993;361:72–6.

Fig. 65.13 Post-translational processing of the POMC polypeptide. Pituitary hypersecretion of ACTH and/or α-MSH can lead to generalized hyperpigmentation in patients with Addison disease. ac, acetylated; ACTH, adrenocorticotropic hormone; des, desacetyl; END, endorphin; JP, joining peptide; LPH, lipotropic hormone; MSH, melanocyte stimulating hormone; PC, prohormone-converting enzyme; POMC, proopiomelanocortin.  

MAJOR FORMS OF THE MELANOCORTIN RECEPTOR

Receptor

Distribution, major (minor)

Ligands

MC1R*

Melanocytes (keratinocytes, fibroblasts, endothelial cells, antigen-presenting cells)

α-MSH, ACTH > β-MSH

MC2R

Adrenal cortex (adipocytes)

ACTH

MC3R†

Brain (gut, placenta)

α-, β-, γ–MSH, ACTH

MC4R†

Brain

α-, β-MSH, ACTH

MC5R

Peripheral tissues, e.g. sebaceous glands, fibroblasts, adipocytes

α-, β-MSH, ACTH

*† Antagonistic ligands – agouti protein (mouse) and agouti signaling protein (ASIP; human). Antagonistic ligand – agouti-related protein (AGRP).

Table 65.4 Major forms of the melanocortin receptor (MCR). ACTH, adrenocorticotropic hormone; MSH, melanocyte stimulating hormone.  

of this disorder, the increase in intracellular cAMP leads to increased tyrosinase activity and eumelanin production. Exposure of melanocytes to phorbol esters, e.g. tetradecanoyl phorbol acetate (TPA), can lead to increased melanin formation via the activa­ tion of protein kinase C (PKC) (Fig. 65.18). Growth factors, including bFGF and KIT ligand, can also lead to an increase in the pigment content within melanocytes whereas KIT receptor inhibitors (e.g. ima­ tinib) can lead to hypopigmentation. Endothelin-1, a small peptide originally isolated from endothelial cells, is produced by keratinocytes and can lead to an increase in tyrosinase activity followed by an increase in melanin production. Multiple genes have been implicated as playing a role in normal pigment variation in humans, including: (1) MC1R and ASIP; (2) several genes that play a role in OCA, e.g. TYR, OCA2, TYRP1, SLC45A2, SLC24A5 (see Table 65.1); (3) KITLG which encodes KIT ligand; (4) TPCN2 which encodes an ion channel transporter; and (5) IRF4 which encodes interferon regulatory factor 42–4. The presence of a variant (rather than the African ancestral) allele of SLC24A5, whose protein product is a putative cation exchanger in the melanosomal membrane, correlates with lighter skin color5. In addition, variants in OCA2 are thought, at least in part, to determine the normal phenotypic variation in human eye color2. A haplotype with several polymorphisms in ASIP (and presumably a gain of ASIP function) has been associated with red or blonde hair, freckling and a tendency to burn, while variants that lead to destabilized ASIP mRNA have been associated with darker skin phototypes3,39,40. A polymorphism in the regulatory region of KITLG that reduces its responsiveness to the WNT-activated transcription factor LEF1 is associated with blonde hair41, and in mice, decreased lef1 leads to light-colored hair. Of note, some loss-of-function muta­ tions in MC1R confer a risk for developing cutaneous melanoma, inde­ pendent of pigmentary phenotype35. In humans, graying or whitening of hair is a normal aging phenom­ enon. There is evidence that reactive oxygen species accumulate within affected hair follicles and lead to oxidative damage of hair follicle mela­ nocytes. Both hair bulb melanocytes and precursor cells in the bulge region can be affected42. In addition, melanocytes that disappear fail to express TYRP2 and SOX10. The role of SCF production by KROX20+ cells within the hair bulb was discussed previously.

CHAPTER

65 Melanocyte Biology

used to describe the banding of hairs seen in some mammals, including dogs, foxes and mice, that is due to alternating production of eumelanin and pheomelanin (Fig. 65.17). The production of agouti protein by the cells in the hair follicle papillae is cyclic, and, when the agouti protein is present, it effectively competes with MSH and the formation of pheomelanin within pheomelanosomes is favored36,37 (see Fig. 65.16). Compared to eumelanosomes, pheomelanosomes are characterized by a more spherical shape and the presence of an unstructured matrix with vesicular bodies. An enhancement of pigment production can be seen following expo­ sure of melanocytes to agents that increase intracytoplasmic levels of cAMP such as cholera toxin, forskolin38, dibutyryl cAMP, and MSH (see Fig. 65.15). The activation of protein kinase A (PKA) by cAMP leads to the phosphorylation of various proteins, which can result in their acti­ vation. One of the proteins that is phosphorylated by PKA is the cAMP response-element binding protein (CREB), which functions as a tran­ scription factor, regulating the expression of other genes, including MITF (see Fig. 65.4). Patients with the McCune–Albright syndrome (polyostotic fibrous dysplasia) are mosaics for an activating mutation in the gene that encodes the G protein Gsα (see Fig. 65.15). As a result, the cAMP cascade is permanently “turned on” and, with continued transcription of the CREB-controlled genes, there is hyperplasia of the bones and endocrine organs, albeit in a mosaic pattern. Presumably within the melanocytes of the segmental café-au-lait macules typical

Ultraviolet Radiation (UVR) Following a single exposure to UVR, an increase in the size of mela­ nocytes can be observed, along with an increase in tyrosinase activ­ ity15. Repeated exposures to UVR lead to an increase in the number Fig. 65.14 Melanocortin 1 receptor (MC1R) within the plasma membrane of a melanocyte. MC1R has seven transmembrane domains and is a G-coupled receptor (see Fig. 65.15). There are numerous genetic variants of the MC1R. The null or hypomorphic R alleles D84E, R151C, R160W, and D294H have red hair odds ratios of 62, 118, 50, and 94, respectively; the low penetrance r alleles of V60L, V92M, and R163Q have red hair odds ratios of 6, 5, and 2, respectively52. In general, R/R individuals have red hair and light skin.  

MELANOCORTIN-1 RECEPTOR (MC1R) WITHIN THE PLASMA MEMBRANE OF A MELANOCYTE

NH2

Major R alleles: D84E R151C R160W D294H

Plasma membrane

COOH

Cytoplasm

1083

INTERACTION OF MSH AND AGOUTI PROTEIN WITH THE MELANOCORTIN 1 RECEPTOR (MC1R)

THE ACTIVATION OF A G-PROTEIN-COUPLED RECEPTOR SUCH AS THE MELANOCORTIN1 RECEPTOR (MC1R) SECTION

A

Effector hormone

10

MC1R

Pigmentary Disorders

Hormone receptor

α-MSH G s

G s

Gs

GDP

Adenylate cyclase Dysfunctional MC1R

GDP

Agouti protein GTP GDP

B

α-MSH

β-Defensin

Agouti

Attractin

MC1R

Extracellular GTP

Adenylate cyclase

*

GTP ATP cAMP In melanocytes, ↑ tyrosinase activity and eumelanin production

*

Intracellular

Gsα Mahogunin

Fig. 65.16 Interaction of melanocyte stimulating hormone (MSH) and agouti protein with the melanocortin 1 receptor (MC1R). A There is baseline activity of the MC1R, enhanced by binding with MSH. Agouti protein represents an antagonist ligand for the MC1R whose binding can lead to pheomelanogenesis. Dysfunction of the MC1R can also lead to pheomelanogenesis, as in the case of humans with red hair. B Interactions are actually more complex, in that to be fully effective, agouti requires attractin and mahogunin; the former aids in the binding of agouti to MC1R while the latter acts on the cytosolic side. There is also a neutral agonist, β-defensin, which interferes with both agonist and antagonist binding. Adapted from Schiaffino  

P

GDP

Fig. 65.15 Activation of a G-protein-coupled receptor such as the melanocortin 1 receptor (MC1R). In the case of the MC1R, the increase in the intracellular concentration of cAMP leads to an increase in tyrosinase activity and eumelanin production. GDP, guanosine diphosphate; GTP, guanosine triphosphate; P, phosphate group; S, stimulatory. Adapted from Alberts B. Molecular  

MV. Signaling pathways in melanosome biogenesis and pathology. Int J Biochem Cell Biol. 2010;42:1094–104.

Biology of the Cell. Garland Publishing; 1989.

1084

of stage IV melanosomes transferred to keratinocytes, as well as an increase in the number of active melanocytes. When chronically sun-exposed sites (e.g. the upper outer arm) are compared with nonsun-exposed sites (e.g. the upper inner arm), the density of mela­ nocytes is up to two times greater in sun-exposed sites43. Melano­ cytes, like other neural-derived tissues, have a low mitotic rate, and whether this increase in number represents an increase in mitotic rate or an activation of “inactive” melanocytes or melanocyte precursors is not known. Following exposure to UVA irradiation, an immediate pigmentary darkening can be observed, which occurs within minutes and fades over 20–30 minutes. It is clinically most obvious in darkly pigmented skin and is thought to represent oxidation of pre-existing melanin or melanin precursors. Given its transient nature, it does not provide photoprotec­ tion. Delayed tanning is visible within 24–72 hours of exposure to UVB and UVA radiation and represents new pigment production via an

increase in tyrosinase activity. In addition to an increase in melanocyte size and number, tyrosinase activity, and transfer of melanosomes to keratinocytes, the response to PUVA includes an alteration in size and aggregation pattern of melanosomes, i.e. from smaller and grouped to larger and singly dispersed (see Table 65.3). UVR may work by increasing one or more of the following: transcription of the tyrosinase gene (via MITF) the number or activity of MC1R on melanocytes the expression of POMC and its derivative peptides by keratinocytes and several cell types within the dermis (e.g. endothelial cells, sebocytes, lymphocytes) the release of diacylglycerol from the plasma membrane, which activates protein kinase C an activation of the nitrous oxide/cGMP pathway the production of cytokines and growth factors by keratinocytes (e.g. endothelin-1)

• • • • • •

Fig. 65.17 Formation of agouti hairs – underlying physiology. A Fox hairs with alternating eumelanin and pheomelanin production within individual hairs, a pattern referred to as agouti. B Explanation for the agouti pattern based on different ligands interacting with the melanocortin 1 receptor (MC1R). Both gain-of-function mutations at the agouti locus and loss-of-function of MC1R can lead to yellow-haired mice. In the CNS, an abundance of agouti protein leads to obesity, and yellow mice with gain-offunction mutations at the agouti locus are also obese53.  

A

B

MSH

Agouti protein

CHAPTER

65 Melanocyte Biology

FORMATION OF AGOUTI HAIRS – UNDERLYING PHYSIOLOGY

MC1R

Fig. 65.18 Mechanisms of UVR-induced pigmentation. These include an increase in one or more of the following: (1) expression of proopiomelanocortin (POMC) and its derivative peptides by cells within the skin, in particular keratinocytes; (2) the number of melanocortin 1 receptors (MC1R) on melanocytes; (3) the release of diacylglycerol (DAG) from the plasma membrane, which activates protein kinase C; (4) the induction of an SOS response to UVR-induced DNA damage; (5) nitric oxide (NO) production, which activates the cGMP pathway; and (6) production of cytokines and growth factors by keratinocytes. As a result, there is enhanced transcription of the genes that encode microphthalmia-associated transcription factor (MITF) and melanogenic proteins including tyrosinase, tyrosinase-related protein 1 (TYRP1), TYRP2, and PMEL/PMEL17/gp100. In addition, melanocyte dendricity and transfer of melanosomes to keratinocytes is stimulated via increased activity of Rac1 (involved in dendrite formation), the ratio of kinesin to dynein, and expression of proteaseactivated receptor-2 (PAR-2; involved in melanosome transfer). TPA, tetradecanoyl phorbol acetate.  

MECHANISMS OF UVR-INDUCED PIGMENTATION

α-MSH

MC1R

cAMP Protein kinase A DAG

+

POMC

Cytokines and growth factors: IL-1 Endothelin-1 bFGF KIT ligand/SCF

Keratinocyte p53

Ca2+

+

MITF

+

Protein kinase C

NO Genes for melanogenic proteins

TPA

Keratinocyte

+ cGMP

Protein kinase G

Melanocyte

induction of an SOS response to UVR-induced DNA • the damage of the POMC promoter by p53 • transactivation the ratio of kinesin to dynein, affecting melanosome transport (see • Fig. 65.10). 34,44,45

46,47

The inability of the majority of red-haired individuals to develop a tan following exposure to UVR can be explained, at least in part, by dysfunction of their melanocyte MC1R. This phenomenon, along

with the production of oxygen radicals following the UV irradiation of pheomelanins, probably contributes to the increased incidence of both cutaneous melanoma and keratinocyte carcinomas in persons with red hair. In addition, chemiexcitation of melanin derivatives induces DNA photoproducts long after UV exposure48. For table on genes associated with physiologic variation in human pigmentation and references visit www.expertconsult.com

1085

Online only content GENES ASSOCIATED WITH PHYSIOLOGIC VARIATION IN HUMAN PIGMENTATION

Protein

TYR

Tyrosinase

Ser192Tyr

Freckles





Arg402Gln

Fair, sunsensitive

Light (weak)

rs1408799 C>T

Sun-sensitive

rs2733832 C>T



Arg305Trp Arg419Gln

TYRP1

TYRP1

OCA2 (P)

P protein

SLC45A2

MATP

Skin color, sun sensitivity, and freckles

Hair color

Eye color

Skin cancer risk*

Population frequencies of variant haplotype European

East Asian

African

SCC

0.4

0

0

Blue (vs green)

Melanoma, BCC

0.4

0

0.07

Light

Blue

Melanoma

0.7

0.02

0.2

Light

Blue



0.6

0.02

0.07





Brown



0.07

0.04

0.02





Green/hazel

Melanoma, BCC

0.07



0

His615Arg





Brown



0

0.5

0

rs12913832 T>C in HERC2†

Fair

Light

Blue

Melanoma (weak)

0.75





Glu272Lys

Dark

Dark

Non-blue



0

0.4

0.05

Leu374Phe

Fair

Light

Blue

Melanoma, NMSC

0.95

0.01

0

SLC24A5

NCKX5

Ala111Thr

Light







0.99

0.01

0.02

SLC24A4

SLC24A4

rs12896399 G>T

Sun-sensitive

Light

Blue (vs green)



0.6

0.5

0.01

MC1R

R alleles‡

Fair, sunsensitive, freckles

Red/light



Melanoma, NMSC

0.3

0

0

r alleles§

Variable

Variable



Melanoma, NMSC

0.3

0.4

0.01

g.8818 A>G

Dark

Dark

Brown



0.15



0.6

ASIP haplotype¶

Fair, sunsensitive, freckles

Red/light

Light

Melanoma, NMSC

0.1–0.3

0–0.2

0–0.1

MC1R

ASIP

ASIP

KITLG

KIT ligand

rs642742 A>G

Fair







0.85

0.8

0.07

rs12821256 T>C



Light





0.15

0

0



Light





0.2

0

0

TPCN2

TPCN2

Met484Leu Gly734Gln



Light





0.4

0.2

0.02

IRF4

Interferon regulatory factor 4

rs12203592 C>T

Fair, sunsensitive

Dark

Blue



0.8

0

0

rs1540771 G>A

Sun-sensitive, freckles

Dark (weak)





0.5

0.2

0.05

CHAPTER

65 Melanocyte Biology

Gene

Selected variant(s): amino acid alteration (if applicable) or SNP

*† Independent of pigmentary phenotype.

Intronic regulatory region that determines expression of the OCA2 gene; other intronic polymorphisms in the HERC2 gene have also been linked to decreased pigmentation, with the same proposed mechanism. ‡High-penetrance “red hair color” alleles, e.g. Asp84Glu, Arg151Cys, Arg160Trp, and Asp294His. §Low-penetrance alleles, e.g. Val60Leu, Val92Met, and (especially in East Asians) Arg163Gln. ¶Single long (~1.8 Mb) haplotype that includes multiple single nucleotide polymorphisms (SNPs; e.g. rs4911414 G>T and rs4911442 A>G) and encompasses several smaller haplotype blocks.

eTable 65.1 Genes associated with physiologic variation in human pigmentatione1–e6. Gray highlight = polymorphism associated with darker pigmentation. The genes in the first four rows are those responsible for OCA types 1 to 4. ASIP, agouti signaling protein; BCC, basal cell carcinoma; MATP, membrane-associated transporter protein; MC1R, melanocortin 1 receptor; NCKX5, Na-Ca-K exchanger 5; NMSC, non-melanoma skin cancer; SCC, squamous cell carcinoma; SLC24A4/5, solute carrier family 24, member 4/5; SLC45A2, solute carrier family 45, member 2; TPCN2, two-pore segment channel 2; TYRP1, tyrosinase-related protein 1.  

From Schaffer JV, Bolognia JL. The biology of the melanocyte. In: Rigel DS, et al (eds). Cancer of the Skin, 2nd edn. St Louis, MI: Elsevier, 2011:23–39.

1085.e1

PIGMENTARY DISORDERS SECTION 10

Vitiligo and Other Disorders of Hypopigmentation

66 

Thierry Passeron and Jean-Paul Ortonne

Chapter Contents Vitiligo . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1087 Hereditary hypomelanosis . . . . . . . . . . . . . . . . . . . . . . . . 1096 Nutritional hypomelanosis . . . . . . . . . . . . . . . . . . . . . . . . 1103 Hypomelanosis secondary to cutaneous inflammation . . . . . . 1103 Infectious and parasitic hypomelanosis . . . . . . . . . . . . . . . . 1106 Halo nevus and melanoma-associated leukoderma . . . . . . . . 1108 Chemical and pharmacologic hypomelanosis . . . . . . . . . . . . 1109 Hypomelanosis from physical agents . . . . . . . . . . . . . . . . . 1110

Key features ■ Leukoderma and hypopigmentation refer to lightening of the skin, which is classically due to decreased epidermal melanin (hypomelanosis) ■ Melanocytopenic hypomelanosis, characterized by a reduction in the number of melanocytes, can result from a variety of defects in pigment cell differentiation, proliferation, migration, and/or survival ■ Melanopenic hypomelanosis features a normal number of melanocytes but decreased melanin synthesis or transfer to keratinocytes, and the underlying abnormalities often involve melanosomes ■ The age of onset (congenital or acquired), degree of pigment loss (hypo- versus amelanosis), presence or absence of preceding inflammation, anatomic location, and distribution pattern – circumscribed, diffuse, linear, or guttate – represent key considerations in the evaluation of a patient with hypopigmentation ■ Vitiligo is a common multifactorial disorder involving the autoimmune destruction of melanocytes; patients present with circumscribed depigmented macules and patches in a localized (including segmental) or generalized distribution ■ Presentations of hereditary hypomelanosis range from congenital, stable, circumscribed areas of amelanosis in piebaldism and Waardenburg syndrome to diffuse pigmentary dilution of the skin, hair, and/or eyes in the various forms of oculocutaneous albinism and related conditions ■ Postinflammatory, infectious, and chemical hypomelanosis as well as halo nevi and melanoma-associated leukoderma represent other etiologies of circumscribed hypo- or amelanosis ■ Linear nevoid hypopigmentation and idiopathic guttate hypomelanosis are the most common causes of linear and guttate hypopigmentation

INTRODUCTION Leukoderma and hypopigmentation are general terms used to designate disorders characterized by lightening of the skin. They are classically the result of decreased epidermal melanin content (melanin-related), but they may be secondary to a decreased blood supply to the skin (hemoglobin-related). Hypomelanosis is a more specific term that denotes a reduction of melanin within the skin; amelanosis signifies

the total absence of melanin. Depigmentation usually implies a total loss of skin color, most commonly due to disappearance of pre-existing melanin pigmentation, as in vitiligo. The term pigmentary dilution is used to describe a generalized lightening of the skin and hair, as in oculocutaneous albinism; this may only be apparent if the affected individuals are compared with unaffected relatives. Cutaneous hypomelanosis is often classified into two groups: melanocytopenic hypomelanosis, caused by a reduction in the number of epidermal and/or follicular melanocytes melanopenic hypomelanosis, in which the number of epidermal and/or follicular melanocytes is normal, but the pigment cells fail to synthesize normal amounts of melanin and/or transfer it to surrounding keratinocytes. Melanocytopenic hypomelanosis may be hereditary and/or congenital due to a defect in melanoblast differentiation, proliferation, migration and/or survival, or it may be acquired. In the latter case, functional melanocytes can disappear as a result of their destruction from insults such as external trauma (e.g. cryosurgery) or an autoimmune attack. The factors controlling melanocyte survival may also play a role in the postnatal disappearance of dermal melanocytes. Melanopenic hypomelanosis may result from complex pathologic mechanisms, including melanosomal abnormalities that affect biogenesis, melanization, transfer, or degradation.

• •

DIAGNOSIS OF LEUKODERMAS Any patient with a leukoderma should be fully examined under visible light and using a Wood’s lamp (~365 nm). The latter is particularly useful in circumscribed leukodermas, individuals who have very lightly pigmented skin (phototypes I or II), and neonates. Under visible light, it is sometimes difficult to distinguish between hypomelanosis and amelanosis, but the greater the loss of epidermal pigmentation, the more marked the contrast on Wood’s lamp examination. This technique is also helpful in differentiating hypomelanotic macules from hemoglobinrelated leukodermas; for example, nevus anemicus becomes inapparent. Most leukodermas are diagnosed clinically following a complete history and physical examination. Determining whether the distribution pattern is circumscribed (e.g. vitiligo), diffuse (e.g. albinism), linear, or guttate (e.g. idiopathic guttate hypomelanosis) helps to narrow the differential diagnosis. The age of onset, presence or absence of preceding inflammation, anatomic location, and degree of pigment loss represent other pertinent features. Histologic examination of involved skin is most useful for several of the hypomelanoses associated with inflammatory processes (e.g. sarcoidosis, lichen sclerosus, mycosis fungoides).

VITILIGO Vitiligo is an acquired disorder characterized by circumscribed depigmented macules and patches that result from the loss of functional melanocytes.

Epidemiology Worldwide vitiligo affects approximately 0.5–2% of the general population1, and it may appear any time from shortly after birth to late adulthood. The average age of onset is ~20 years. Although patients with vitiligo may attribute the onset of their disease to specific life events (e.g. physical injury, sunburn, emotional distress, illness, pregnancy), with the exception of the Koebner phenomenon, there is no proof that these factors cause or precipitate vitiligo.

1087

Leukoderma and hypopigmentation refer to lightening of the skin, which is classically due to decreased epidermal melanin (hypomelanosis) but may also result from decreased cutaneous blood supply. Melanocytopenic hypomelanosis is characterized by reduced or absent vs a reduction in the number of melanocytes, whereas melanopenic hypomelanosis features a normal number of melanocytes but decreased melanin synthesis or transfer to keratinocytes. The age of onset (congenital or acquired), degree of pigment loss (hypo- versus depigmentation), presence or absence of preceding inflammation, anatomic location, and distribution pattern – circumscribed, diffuse, linear, or guttate – represent key considerations in the evaluation of a patient with hypomelanosis. This chapter first discusses vitiligo, a common multifactorial disorder involving the autoimmune destruction of melanocytes that presents with depigmented macules and patches in a localized or generalized distribution. Hereditary, nutritional, postinflammatory, infectious, and chemical forms of hypomelanosis as well as halo nevi and melanoma-associated leukoderma are also reviewed.

hypopigmentation leukoderma hypomelanosis depigmentation vitiligo oculocutaneous albinism piebaldism Waardenburg syndrome Hermansky–Pudlak syndrome Griscelli syndrome Chédiak–Higashi syndrome ash leaf spot nevus depigmentosus linear nevoid hypopigmentation hypomelanosis of Ito segmental pigmentation disorder progressive macular hypomelanosis postinflammatory hypomelanosis pityriasis alba melanoma-associated leukoderma halo nevus idiopathic guttate hypomelanosis

CHAPTER

66 Vitiligo and Other Disorders of Hypopigmentation

ABSTRACT

non-print metadata KEYWORDS

1087.e1

10

Pathogenesis

Pigmentary Disorders

SECTION

Genetics of vitiligo

group of diseases with different genetic backgrounds and environmental triggers. The immune system clearly plays a central role, in particular Th1 and Th17 cells, along with cytotoxic T cells, regulatory T cells, and dendritic cells; key mediators include interferon-γ (IFN-γ), C-X-C chemokine ligand 10 (CXCL10), and interleukin-22 (IL-22)8–12b. Animal models of vitiligo in which there are T cells reactive against melanocyte antigens have demonstrated the importance of an inflammatory dendritic cell (DC) phenotype and the INF-γ pathway13,14. Intrinsic defects of melanocytes and exogenous triggers may also play a role in vitiligo development. In addition, oxidative stress has been investigated as a pathogenic factor that could activate the immune response in vitiligo and underlie impaired WNT signaling that prevents melanoblast differentiation15–18a. Accumulating data highlight the complexity of vitiligo, with involvement of multiple cell types, including keratinocytes, fibroblasts, and stem cells as well as immune cells19,20. These hypotheses are not mutually exclusive and the various pathways may converge to induce the disappearance of melanocytes from the skin and hair follicles. However, the exact cascade of events remains to be elucidated.

Vitiligo is a multifactorial disorder related to both genetic and nongenetic factors. It is generally agreed that there is an absence of functional melanocytes in vitiligo skin and that the loss of histochemically recognizable melanocytes is the result of their destruction.

Both twin and family studies point to the importance of genetic factors in the development of vitiligo2,3. For example, a survey in the US and UK found that 7% of the first-degree relatives of vitiligo probands had vitiligo. However, a 23% concordance rate in monozygotic twins supported the additional role of environmental factors4. Genome-wide linkage analyses have been performed in multiple patient populations, resulting in the identification of a number of susceptibility loci and candidate genes. Many of these genes are involved in melanogenesis, immune regulation, or apoptosis and have been associated with other pigmentary, autoimmune, or autoinflammatory disorders5–7 (Table 66.1).

Pathogenic hypotheses for vitiligo Many pathogenic hypotheses have been proposed for vitiligo, in part reflecting the incomplete understanding of the mechanisms that underlie this complex condition (Fig. 66.1). A primary challenge is the fact that what is referred to as vitiligo likely represents a heterogeneous

Clinical Features The most common presentation of vitiligo is totally amelanotic (milkor chalk-white) macules or patches surrounded by normal skin.

PROPOSED MODEL FOR THE PATHOGENESIS OF VITILIGO Melanocyte stress Intrinsic risks

signal transducer & activator of transcription 1 (STAT1) phosphorylated STAT1 Janus kinase 1 (JAK1) Janus kinase 2 (JAK2)

Environmental factors Oxidative stress MBEH 4-TBP

Genetic risk

Melanocyte stress signals

ER stress Tyrosinase and TYRP-1

Responding cell type(s) in the skin

HSP70

Macrophage

Exosomes Dendritic cell

ROS Other DAMPs

Keratinocyte

Autoimmune T-cell attack CXCL10

Skin chemokine source

CXCR3

Treg?

IFN-R Autoreactive CD8 T cell

Activated resident cells

IFN- Activated T cells

Antigen presentation and T-cell activation in lymph node

Fig. 66.1 Proposed model for the pathogenesis of vitiligo. Inherited genetic risk (see Table 66.1) and environmental insults (e.g. monobenzyl ether of hydroquinone [MBEH], 4-tertiary butyl phenol [4-TBP]) induce melanocyte stress, exemplified by endoplasmic reticulum (ER) stress. Stressed melanocytes signal to local innate and resident skin cell types via exosomes containing antigen and damage-associated molecular patterns (DAMPs), soluble heat shock protein 70 (HSP70), and other factors. These signals activate several cell types, some of which migrate to the draining lymph nodes and stimulate T cells, which secrete interferon-γ (IFN-γ). IFN-γ signals through the IFN-γ receptor (IFN-γR) on keratinocytes and/or other cells; this involves phosphorylation of the transcription factor STAT1 by Janus kinases (JAK) 1 and 2. Phosphorylated STAT1 homodimerizes and then translocates into the nucleus, where IFN-γ-dependent genes such as CXCL10 (C-X-C chemokine ligand 10) are transcribed. Autoreactive CD8+ T cells that express C-X-C chemokine receptor 3 (CXCR3) follow secreted CXCL10 to the skin, where they kill melanocytes. Approaches targeting this IFN-γ–STAT1–CXCL10 axis that drives melanocyte destruction (e.g. with JAK inhibitors or antibodies against CXCR3) hold promise as potential treatments for vitiligo. ROS, reactive oxygen species; STAT1, signal transducer and activator of transcription 1; TYRP-1, tyrosinase-related protein 1. Adapted from Strassner JP, Harris JE. Understanding mechanisms of autoimmunity through translational research in vitiligo. Curr Opin Immunol. 2016;443:81–8.  

1088

Activated migrating cells

CHAPTER

Chromosomal location

Candidate gene

Defective protein

1p13

PTPN22

Protein tyrosine phosphatase, non-receptor type 22

1p31.3

FOXD3*

Forkhead box D3*

2q24

IFIH1

Interferon induced with helicase C domain 1

2q33.2

CTLA4

Cytotoxic T-lymphocyte-associated protein 4

Involved in immune regulation

3p14.1

FOXP1

Forkhead box P1

3q13.33

CD80

CD80 molecule

3q27–q28

LPP

LIM domain containing preferred translocation partner in lipoma

4p16.1

CLNK

Cytokine dependent hematopoietic cell linker

5q22.1

TSLP

Thymic stromal lymphopoietin

6q15

BACH2

BTB domain and CNC homolog 2

6p21.3

HLA (various genes), BTNL2

Major histocompatibility complex classes I–III, butyrophilin-like 2

6q27

CCR6

Chemokine (C-C motif) receptor 6

SMOC2

SPARC related modular calcium binding 2

8q24

SLA

Src-like-adaptor

10p15–p14

IL2RA

Interleukin 2 receptor α

11p13

CD44

CD44 molecule

11q23.3

CXCR5

C-X-C motif chemokine receptor 5

12q13

IKZF4

IKAROS family zinc finger 4

12q24

SH2B3

SH2B adaptor protein 3

17p13

NLRP1 (formerly NALP1)

NOD-like receptor family, pyrin domain containing 1

18q21.33

TNFRSF11A

TNF receptor superfamily member 11a (RANK)

19p13.3

TICAM1

Toll-like receptor adaptor molecule 1

20q13.13

PTPN1

Protein tyrosine phosphatase, non-receptor type 1

21q22.3

UBASH3A, AIRE

Ubiquitin associated and SH3 domain containing A, autoimmune regulator

22q12.1

XBP1

X-box binding protein 1

22q13.1

C1QTNF6

C1q and tumor necrosis factor related protein 6

22q13.2

TOB2

Transducer of ERBB2, 2

Xp11.23

FOXP3

Forkhead box P3

66 Vitiligo and Other Disorders of Hypopigmentation

SELECTED SUSCEPTIBILITY LOCI AND CANDIDATE GENES FOR VITILIGO

Involved in apoptosis and/or cytotoxicity FASL

1q24.3

Fas ligand

1p36.23

RERE

Arginine–glutamic acid dipeptide (RE) repeats

10q22.1

SLC29A3

Solute carrier family 29 member 3

10q25

CASP7

Caspase 7

14q11.2

GZMB

Granzyme B

6p25.3

IRF4

Interferon regulatory factor 4

6q27

FGFR1OP, RNASET2

Fibroblast growth factor receptor 1 oncogene partner, ribonuclease T2

Melanocyte related

10q22.3

ZMIZ1

Zinc finger MIZ-type containing 1

11q14–q21

TYR

Tyrosinase

12q13.2

PMEL

Premelanosome protein

15q13.1

OCA2, HERC2

Oculocutaneous albinism 2 transmembrane protein, HECT and RLD domain containing E3 ubiquitin protein ligase 2

16q24.3

MC1R

Melanocortin-1 receptor

20q11.22

ASIP

Agouti signaling protein

*In one family to date, a functional variant in the promoter of the FOXD3 melanoblast developmental regulator gene was associated with autosomal dominant inheritance of an atypical vitiligo phenotype (early onset, widespread, progressive depigmentation).

Table 66.1 Selected susceptibility loci and candidate genes for vitiligo. There is evidence that vitiligo has significant genetic heterogeneity in different ethnic populations. Genome-wide association studies have identified other susceptibility loci, including 7p13, 7q11, 9q22, and (in Chinese patients) 4q13–q21. HLA, human leukocyte antigen.  

1089

SECTION

Pigmentary Disorders

10

Well-developed lesions typically have discrete margins and may be round, oval, irregular, or linear in shape. The borders are usually convex, as if the depigmenting process were “invading” the surrounding normally pigmented skin. However, at their onset or when actively spreading, areas of vitiligo may be more ill-defined and hypo- rather than depigmented21. Lesions enlarge centrifugally over time at a rate than can be slow or rapid. Vitiligo macules and patches range from millimeters to centimeters in diameter and often have variable sizes within an area of involvement. In lightly pigmented individuals, the lesions may be subtle or inapparent without Wood’s lamp examination or tanning of uninvolved skin. In darkly pigmented patients, the contrast between vitiliginous

areas and the surrounding skin is striking (Fig. 66.2). Vitiligo is usually asymptomatic, but pruritus is occasionally noted, especially within active lesions. Vitiligo may develop anywhere on the body. Interestingly, it frequently localizes to sites that are normally relatively hyperpigmented, such as the face, dorsal aspect of the hands, nipples, axillae, umbilicus, and sacral, inguinal and anogenital regions (see Fig. 66.2). Typically, facial vitiligo occurs around the eyes and mouth (i.e. periorificial), and on the extremities it favors the elbows, knees, digits, flexor wrists, dorsal ankles and shins (Figs 66.3 & 66.4). The most common sites of involvement are areas subjected to repeated trauma, pressure, or friction (e.g. in body folds or via contact with clothing). Palmoplantar and

Fig. 66.3 Vitiligo. Depigmentation of the volar wrists as well as the palmar surfaces. Courtesy, Jean L Bolognia, MD.  

Fig. 66.2 Genital vitiligo. Complete loss of pigment on the penis and scrotum. Note the lack of any secondary changes. Courtesy, Lorenzo Cerroni, MD.  

DISTRIBUTION PATTERN OF AMELANOTIC SKIN LESIONS IN VITILIGO Generalized Vitiligo

Vulgaris

1090

Acrofacial

Localized Vitiligo

Universal

Focal

Segmental

Fig. 66.4 Distribution pattern of amelanotic skin lesions in vitiligo. Adapted with permission from Le Poole C, Boissy RE. Vitiligo. Semin Cutan Med Surg. 1997;16:3–14.  

Clinical variants Vitiligo ponctué, an unusual clinical presentation of vitiligo, is characterized by multiple, small, discrete amelanotic macules (confetti-like), sometimes superimposed upon a hyperpigmented macule. Erythema at the margin of a vitiligo macule is referred to as “vitiligo with raised inflammatory borders” or inflammatory vitiligo (Fig. 66.6); a figurate papulosquamous variant has also been described. Occasionally, a hyperpigmented margin is seen. Blue vitiligo can result when vitiligo develops in areas of postinflammatory dermal pigmentation. Trichrome vitiligo is characterized by a hypopigmented zone between the normal and depigmented skin. This intermediate zone has a fairly uniform hue rather than gradually progressing from white to normal.

The number of melanocytes is also intermediate in this zone, suggesting a slower centrifugal progression compared with typical vitiligo. Quadrichrome and pentachrome vitiligo have also been described. Hypochromic vitiligo (vitiligo minor) was recently described in patients with skin types V and VI22. They presented with persistent hypopigmented macules in a seborrheic distribution, with lesions coalescing on the face and scattered on the neck, trunk, and scalp. A few individuals had additional achromic macules, and there was no history of prior inflammatory lesions. Decreased melanocyte density was noted histologically. One of the manifestations of vitiligo is the isomorphic Koebner phenomenon (IKP), which is characterized by the development of vitiligo in sites of trauma, such as a surgical excision, burn, or abrasion. The IKP is more common in patients with progressive vitiligo, and it can occur in various forms of vitiligo. There appears to be a minimal threshold of injury required for the IKP to occur, bringing into question the hypothesis that minor trauma, such as friction from clothes (in the absence of true injury), can induce vitiligo lesions.

Clinical classification of vitiligo Multiple attempts to classify the different types of vitiligo have resulted in confusing terminology. Two major forms are generally recognized: (1) segmental, which usually does not cross the midline; and (2) nonsegmental, also simply called “vitiligo” without qualification23,24. Mixed vitiligo refers to segmental and non-segmental forms occurring in the same patient25. The following classification scheme divides vitiligo into two major types, localized and generalized (see Fig. 66.4). Localized: Focal: one or more macules in one area, but not clearly in a segmental distribution Unilateral/segmental: one or more macules involving one or rarely multiple segments of the body (Fig. 66.7); lesions are typically unilateral and stop abruptly at the midline Mucosal: mucous membranes alone Generalized: Vulgaris: scattered patches that are widely distributed Acrofacial: distal extremities and face Mixed: combination of segmental and generalized (acrofacial and/ or vulgaris) types Universal: complete or nearly complete depigmentation Overall, >90% of vitiligo patients have the vulgaris or acrofacial variants of the generalized type. In the remainder, localized vitiligo is more common than mixed or universal vitiligo. Segmental vitiligo is more common in children than adults, accounting for ~15–30% of vitiligo in pediatric patients (see below).

CHAPTER

66 Vitiligo and Other Disorders of Hypopigmentation

oral mucosal involvement in lightly pigmented individuals is often difficult to visualize without Wood’s lamp examination. In acrofacial vitiligo, periungual involvement of one or more digits may be associated with lip depigmentation; however, either can be an isolated finding. The incidence of body leukotrichia varies from 10% to >60%, as vitiligo often spares follicular melanocytes. The occurrence of leukotrichia does not correlate with disease activity. Rarely, follicular vitiligo presents with leukotrichia in the absence of depigmentation of the surrounding epidermis21a. Although vitiligo of the scalp, eyebrows, and eyelashes usually presents as one or more localized patches of white or gray hair (poliosis; Fig. 66.5), scattered white hairs due to involvement of individual follicles or even total depigmentation of all scalp hair may occur.

• • • • • • •

Fig. 66.5 Segmental vitiligo. Under normal light, vitiligo can be subtle in lightly pigmented individuals. The clue to the diagnosis is the poliosis of the eyelashes. Courtesy, Jean L Bolognia, MD.  

Course of the disease The onset of vitiligo is usually insidious. Many patients become aware of the depigmented macules and patches, especially in sun-exposed

Fig. 66.7 Segmental vitiligo. Unilateral band of depigmentation on the face, the most common location for segmental vitiligo. Note the pigmented and depigmented hairs within the affected area. Courtesy, Kalman Watsky, MD.  

Fig. 66.6 Inflammatory vitiligo. An erythematous inflammatory border is evident. Such lesions are sometimes misdiagnosed as tinea corporis.  

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areas, during the summer when tanning increases the contrast between involved and uninvolved skin. Clinical erythema or pruritus rarely precedes vitiligo. The course of vitiligo is unpredictable. It becomes more extensive by the appearance of new depigmented macules, centrifugal enlargement of pre-existing lesions, or both processes. Peripheral hypopigmentation and poorly defined borders appear to be predictive of active vitiligo21. A spotty pattern of depigmentation may also represent a marker of progressive disease. The natural course of generalized vitiligo is usually one of slow spread, but it may stabilize for a long period of time or evolve rapidly. Rarely, total body involvement develops within a few weeks or even days. In contrast, segmental vitiligo usually reaches its full extent within 1–2 years and remains restricted to the initial segmental area. The presence of halo nevi and leukotrichia increases the likelihood of evolution from segmental to mixed vitiligo26. Some degree of sun-induced or spontaneous repigmentation of vitiligo is not uncommon, but complete and stable repigmentation is rare. The vitiligo area scoring index (VASI) and Vitiligo European Task Force (VETF) score represent validated quantitative assessment scales27. However, universally accepted definitions for active and stable vitiligo are still lacking.

Vitiligo and ocular disease The uveal tract (iris, ciliary body, and choroid) and retinal pigment epithelium contain pigment cells. Uveitis is the most significant ocular abnormality associated with vitiligo. Vogt–Koyanagi–Harada (VKH) syndrome is characterized by: (1) uveitis; (2) aseptic meningitis; (3) otic involvement (e.g. dysacusia); and (4) vitiligo, especially of the face or sacral region, and associated poliosis. Histologic examination of amelanotic skin, which classically appears after the extracutaneous symptoms, demonstrates an infiltrate consisting primarily of CD4+ lymphocytes, suggesting a prominent role for cell-mediated immunity. Non-inflammatory depigmented lesions of the ocular fundus are evident in some patients with vitiligo, presumably representing focal areas of melanocyte loss. Although abnormal sensory hearing loss has been described in vitiligo patients, suggesting impairment of cochlear melanocytes, clearcut evidence of otic abnormalities remains to be demonstrated. Alezzandrini syndrome is a rare disorder characterized by unilateral whitening of scalp hair, eyebrows, and eyelashes as well as ipsilateral depigmentation of facial skin and visual changes. In the affected eye, there is decreased visual acuity and an atrophic iris. The pathogenesis of Alezzandrini syndrome is unknown, but it is believed to be closely related to VKH syndrome.

Associated disorders Although most vitiligo patients are otherwise healthy, generalized vitiligo is associated with a number of other autoimmune diseases, especially in patients with a family history of vitiligo and other forms of autoimmunity. Autoimmune thyroid disease occurs in ~15% of adults and ~5–10% of children with vitiligo28, and other less frequently associated conditions include pernicious anemia, Addison disease, lupus erythematosus, rheumatoid arthritis, and adult-onset insulin-dependent diabetes mellitus29,30. Of note, these conditions have been linked to the same autoimmunity predisposition genes as in vitiligo (e.g. PTPN22, NLRP1; see Table 66.1). Halo melanocytic nevi, alopecia areata, and lichen sclerosus are additional autoimmune skin conditions that may be associated with vitiligo. Patients with the autosomal recessive autoimmune polyendocrinopathy–candidiasis–ectodermal dystrophy (APECED) syndrome often develop vitiligo. The gene responsible for APECED, AIRE (autoimmune regulator), encodes a transcription factor that promotes expression of tissue-specific self-antigens in the thymus, which facilitates development of peripheral tolerance. In APECED, failure to delete autoreactive T cells leads to autoimmune disease. In a mouse model, AIRE deficiency was found to result in tyrosinase-related protein-1 (TYRP1)-specific T cells that enhanced immune responses against melanoma31.

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Although vitiligo vulgaris is the most common clinical type observed in children, the frequency of segmental vitiligo (~15–30%) is

significantly increased compared to that in adults (75% repigmentation with class 1 (superpotent) or 2–3 (high potency) topical corticosteroids; cutaneous atrophy was observed in 14% and 2% of these groups, respectively34. To minimize side effects, class 1 corticosteroids can be used in 6–8-week cycles or on a twice-weekly basis, alternating with topical tacrolimus or a less potent topical corticosteroid35. Treatment should be discontinued if there is no visible improvement after 2–3 months. In general, intralesional corticosteroids should be avoided because of the pain associated with injection and the higher risk of cutaneous atrophy (≥30%). Systemic corticosteroid regimens utilizing high-dose pulses, mini-pulses, or low daily oral doses have been reported to arrest rapidly spreading vitiligo and induce repigmentation36,37. However, given the potential for serious side effects, the role of systemic corticosteroids in the treatment of vitiligo remains controversial.

Psoralen photochemotherapy involves the use of psoralens combined with UVA light (see Ch. 134). The psoralen most commonly used is 8-methoxypsoralen (8-MOP, methoxsalen). 5-methoxypsoralen (5-MOP, bergapten) is not approved in the US and 4,5′,8-trimethylpsoralen (TMP, trioxsalen) is no longer commercially available. Psoralens can be administered orally (oral PUVA) or applied topically (topical PUVA), followed by exposure to either UVA light or natural sunlight (PUVASOL). Oral PUVA treatments using 8-MOP (0.4–0.6 mg/kg) are typically administered two times weekly. For patients with vitiligo, the initial dose of UVA is usually 0.5–1.0 J/cm2, which is gradually increased until minimal asymptomatic erythema of the involved skin occurs. To reduce the risk of the Koebner phenomenon, significant erythema (phototoxicity) is avoided. 5-MOP has about the same response rate as 8-MOP in repigmenting vitiligo, but a lower incidence of phototoxicity as well as less nausea and vomiting. The response rate to PUVA is variable; it often produces cosmetically acceptable improvement, but complete repigmentation is uncommon. The total number of PUVA treatments required is generally 50–300. The absolute and relative contraindications, as well as the short- and long-term side effects, of oral PUVA therapy are reviewed in Chapter 134. To date, only a few vitiligo patients with PUVA-induced cutaneous carcinomas have been reported. Although this probably reflects a smaller cumulative UVA dose than in patients treated for other disorders such as psoriasis, large follow-up studies have not yet been done in PUVA-treated vitiligo patients. Until more data are available, it seems wise to recommend 1000 J/cm2 as the maximum cumulative (P) UVA dose and 300 as the maximum number of UVA treatments. Topical (paint) PUVA is more difficult to perform because of the high risk of phototoxicity and subsequent blistering or koebnerization. A low concentration (≤0.1%) of psoralen should be used, which requires dilution of the commercially available preparation. Approximately 20–30 minutes after applying the topical cream or ointment onto the lesions,

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the patient should be exposed to initial UVA doses of no more than 0.25 J/cm2, with the same fractional increments until mild erythema is achieved in the treated sites. PUVASOL (psoralens + natural sunlight) can be used in sunnier climates, utilizing the same principles as for PUVA. Less phototoxic oral psoralens such as 5-MOP are preferred in order to avoid phototoxic reactions.

Other phototherapies

Oral khellin plus UVA (KUVA) and phenylalanine plus UVA have also been employed. There have been conflicting reports regarding efficacy as well as concerns regarding the hepatotoxicity of khellin. As a result, these modalities are not recommended. Topical KUVA has a relatively low risk of phototoxicity, but it requires a longer duration of treatment and higher UVA doses than does oral PUVA44. Focused microphototherapy has the advantage of irradiating only the depigmented skin. A directed beam of broadband or narrowband UVB light is applied to areas of vitiligo using spot sizes of 1–5 cm. Treatments are administered from several times weekly to twice monthly. In one large study, 70% of patients who received a mean of 24 treatments over a 12-month period achieved >75% repigmentation.

Lasers and related light devices Excimer laser and lamp

The operational wavelength of the 308 nm excimer laser and lamp is close to that of NB-UVB45. The therapeutic benefit of the excimer laser for vitiligo has been investigated in multiple studies, and, overall, 20–50% of lesions achieve ≥75% repigmentation46–48; the excimer lamp appears to have similar efficacy49,50. Only a few studies have directly compared excimer laser to NB-UVB, and some but not all showed superior results with the former modality48,51. This may be explained by the excimer laser’s higher irradiance (power per unit area), which is thought to stimulate melanocyte development52. Localized patches of vitiligo are treated one to three times weekly with the excimer laser, typically for a total of 24 to 48 sessions; the repigmentation rate depends on the total number of sessions, not their frequency39. In practice, twice weekly treatments for a total of ~40 sessions is thought to be optimal. As with other vitiligo therapies, facial lesions respond better than those on the distal extremities and overlying bony prominences48. Erythema and (rarely) blistering represent potential side effects38.

Helium–neon laser

The helium–neon laser emits a wavelength (632.8 nm) in the red visible light range that can enhance melanocyte proliferation and melanogenesis in vitro53. In a study performed in 30 patients with segmental vitiligo, 20% of lesions achieved ≥75% repigmentation after a mean of 79 treatment sessions, which were administered once or twice weekly54.

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For vitiligo patients who fail to respond to medical therapy, surgical treatment with autologous transplantation techniques may be an option55,56. The general selection criteria for autologous transplantation include stable disease for ≥6 months, absence of the Koebner phenomenon, no tendency for scar or keloid formation, and age >12 years57. A minigraft test showing retention/spread of pigment at the recipient site and no koebnerization at the donor site after 2–3 months can also assist in patient selection. Several methods of surgical repigmentation have been successfully utilized. Minigrafting is the simplest technique. Small punch grafts (1–2 mm) from uninvolved skin are implanted within achromic areas, separated from each other by 5–8 mm. A cobblestone effect, a variegated appearance of the grafts, and sinking pits represent potential unfavorable outcomes. Because scarring and dyspigmentation may occur at the donor sites, cosmetically insensitive areas are chosen. The advantages of suction blister epidermal grafting are the absence of scarring at the donor site and the possibility of reusing this area. However, failure of the graft to take and koebnerization may occur. Grafting of cultured autologous melanocytes is an expensive technique that requires specialized laboratory expertise; grafts consist of pure melanocytes or melanocytes admixed with keratinocytes58. To avoid the need for in vitro culture, which involves mitogens to enhance cell growth, grafting of non-cultured epidermal cell suspensions that include melanocytes

has been advocated59. Grafting of individual hairs to repigment vitiligo leukotrichia has also been successfully performed. Most of these techniques require clinical expertise.

Combination therapy Combination therapy may produce higher rates of repigmentation compared to traditional monotherapies. Examples include phototherapy following surgical procedures as well as combining TCIs and/or topical corticosteroids with NB-UVB or excimer laser therapy60–65. Although topical vitamin D derivatives are relatively ineffective as monotherapy, these agents may result in additional repigmentation when used in conjunction with phototherapy.

Micropigmentation The technique of permanent dermal micropigmentation utilizes a nonallergenic iron oxide pigment to camouflage recalcitrant areas of vitiligo. This tattooing method is especially useful for the lips, nipples and distal fingers, which have a poor rate of repigmentation with currently available treatments. Although the color may not match perfectly with the normal surrounding skin and can fade over time, the result is immediate and can represent a dramatic aesthetic improvement.

Depigmentation Depigmentation represents a treatment option for patients who have widespread vitiligo with only a few areas of normally pigmented skin in exposed sites. The patients must be carefully chosen, i.e. adults who recognize that their appearance will be altered significantly and who understand that depigmentation requires lifelong strict photoprotection (e.g. sunscreens, clothing, umbrellas). The most commonly used agent is 20% monobenzyl ether of hydroquinone (MBEH), applied once to twice daily to the affected areas for 9–12 months or longer66. MBEH is a potent irritant and allergen, and an open application test can be performed before more widespread application. It typically takes 1–3 months to initiate a response, and a loss of pigment can occur at distant sites. Although depigmentation from MBEH is considered permanent, repigmentation (especially perifollicular in areas with pigmented hairs) can be seen following a sunburn or intense sun exposure. Monomethyl ether of hydroquinone (MMEH) in a 20% cream can be used as an alternative to MBEH67. Side effects include contact dermatitis, exogenous ochronosis, and leukomelanoderma en confetti. Depigmentation via Q-switched ruby laser therapy was reported to achieve faster depigmentation than that achieved with a bleaching agent67, and this laser has also been used in combination with topical 4-methoxyphenol to induce depigmentation68. Lastly, depigmentation with the Q-switched alexandrite laser has been described69.

Psychological support The impact of vitiligo on quality of life is severe in many affected individuals, and it is critical for physicians to recognize this aspect of the condition and address their patients’ psychological needs. Although a “magic” treatment is not yet available, there is always something beneficial that can be done for vitiligo patients. They first need to know what their skin disorder is. Explaining the nature of the disease process and the potential and limits of available therapies is important and more productive than a fatalistic attitude that there is no cure and vitiligo is “only” a cosmetic disorder. Even helping patients to conceal the condition so that it is not visible can be part of the management plan. The use of support groups and, if indicated, psychological counseling are important supplementary therapies.

Additional controversial therapies Pseudocatalase with narrowband UVB

The rationale for this treatment is based on the hypothesis that accumulation of hydrogen peroxide leads to pathogenic inactivation of catalase in the skin of patients with vitiligo (Table 66.2). In an open uncontrolled study, complete repigmentation of lesions on the face and hands was observed in 90% of patients (30 of 33) treated with topical pseudocatalase and calcium twice daily plus UVB twice weekly, with initial repigmentation at 2–4 months70. Controlled trials, however, showed no efficacy of topical pseudocatalase/superoxide dismutase compared to placebo and no additional benefit of pseudocatalase compared to UVB alone71,72.

CHAPTER

Hypothesis

Evidence for hypothesis

Evidence against hypothesis

Autoimmune destruction of melanocytes



Epidemiologic association with autoimmune disorders (see text) Variants in immunoregulatory genes linked with vitiligo and associated autoimmune disorders (see Table 66.1) • Detection of antibodies against melanocyte proteins (e.g. TYR, TYRP1, DCT, MCHR1, SOX10) in the sera of patients with vitiligo • Destruction of melanocytes in normal human skin engrafted onto nude mice after injection with vitiligo patient sera • Infiltration of CD8+ T cells into perilesional vitiligo skin • Skin-homing, melanocyte-specific cytotoxic T cells (e.g. against surface proteins such as Melan-A/MART-1) frequently detectable in the peripheral blood of vitiligo patients • Reports of generalized vitiligo following bone marrow transplantation from donors with vitiligo • T-cell receptor transgenic mice that recognize an epitope of tyrosinase develop depigmented lesions with characteristics similar to human vitiligo



An intrinsic defect in melanocytes, their adhesive properties, and/or factors critical to their survival



Abnormalities of cultured vitiligo melanocytes: - Dilation of the rough endoplasmic reticulum - Abnormal synthesis/processing of TYRP1 - Increased sensitivity to oxidative stress (e.g. UVB) • Evidence for transepidermal melanocytorrhagy due to defective melanocyte adhesion: - Detachment and transepidermal loss of melanocytes observed in in vivo studies of vitiligo skin - Induction of detachment by mechanical stress, which could explain the Koebner phenomenon - Decreased adhesion to collagen type IV and “stubby” dendrites in melanocytes cultured from perilesional skin of unstable vitiligo • Evidence for reduced melanocyte survival and dysregulation of melanocyte apoptosis in vitiligo: - The progressive loss of hair follicle melanocytes observed in bcl-2−/− mice provides a model of apoptotic loss of melanocytes - Variants in genes that regulate apoptosis associated with vitiligo (see Table 66.1) - Deficiency of factors important for melanocyte maintenance (e.g. SCF, KIT, MITF) in vitiligo skin - Vitiligo-like depigmentation and hair graying observed in patients treated with tyrosine kinase inhibitors that target KIT



Defective defense against oxidative stress leading to destruction of melanocytes

Detection of high in vivo levels of epidermal H2O2 in vitiligo skin, with potential sources including: - Accumulation of oxidized pteridines, e.g. 6-biopterin (bluish fluorescence) and 7-biopterin (yellow/green fluorescence) - Increased catecholamine biosynthesis in association with increased monoamine oxidase A activity - Inhibition of thioredoxin/thioredoxin reductase by calcium in the setting of defective calcium transfer/homeostasis in vitiligo epidermis • Oxidative degradation of catalase resulting in low levels of this protective enzyme in vitiligo skin







Limited evidence for autoimmune pathogenesis of segmental vitiligo • Although there is strong evidence for an autoimmune etiology of generalized vitiligo, it is unclear whether a primary immune attack targets normal melanocytes or if immune activation is triggered by damage to melanocytes by an exogenous or endogenous factor

Melanocytorrhagy is observed only in lesional and perilesional areas of vitiligo and appears to be a secondary process • No alteration in the expression of apoptosis regulatory molecules in vitiligo melanocytes compared with normal melanocytes

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PATHOGENIC HYPOTHESES FOR VITILIGO

Whether these abnormalities are the cause of vitiligo lesions, versus secondary consequences of immune attack or an intrinsic defect in melanocytes has not been determined • No conclusive evidence of benefit from therapeutic approaches using pseudocatalase or systemic antioxidant agents in clinical studies

Table 66.2 Pathogenic hypotheses for vitiligo. A “convergence theory” that vitiligo results from a combination of several of these pathogenic mechanisms has also been proposed. Hypotheses with less support include destruction of melanocytes by neurochemical substances or a viral infection (e.g. cytomegalovirus). DCT, dopachrome tautomerase; MCHR1, melanin-concentrating hormone receptor 1; MITF, microphthalmia-associated transcription factor; SCF, stem cell factor; TYR, tyrosinase; TYRP1, tyrosinase-related protein 1; UVB, ultraviolet B.  

Systemic antioxidant therapy

The rationale for this approach rests on the hypothesis that vitiligo results from a deficiency of natural antioxidant mechanisms. Although to date not validated by controlled clinical trials, selenium, methionine, tocopherols, ascorbic acid, and ubiquinone are prescribed by some physicians.

the topical corticosteroid73,74. Similar studies have shown that treatment of recalcitrant vitiligo lesions with an ablative fractional carbon dioxide laser led to greater efficacy of subsequent therapy with NB-UVB, outdoor sun, and/or a potent topical corticosteroid75,76. In order to minimize koebnerization, these approaches should be reserved for patients with stable vitiligo.

Potential emerging treatments

Topical prostaglandins

Ablative laser treatment followed by narrowband UVB plus topical 5-fluorouracil or corticosteroids

In difficult-to-treat sites (e.g. distal extremities, over bony prominences), erbium:YAG laser ablation of vitiligo lesions followed by NB-UVB therapy twice weekly for 3–4 months, plus topical application of either 5-fluorouracil or a potent corticosteroid, was found to result in significantly greater repigmentation than treatment with NB-UVB ±

Preliminary studies have suggested the utility of topical prostaglandin E2 and latanoprost (an analogue of prostaglandin F2) in the treatment of vitiligo77,78. Although interesting, these results require confirmation.

Afamelanotide

Afamelanotide is an α-melanocyte stimulating hormone (α-MSH) analogue that stimulates melanogenesis and melanocyte proliferation by binding to the melanocortin-1 receptor (MC1R; see Ch. 65). A recent

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randomized controlled study found that the addition of afamelanotide (monthly subcutaneous implants) to NB-UVB therapy increased the speed and extent of repigmentation compared to NB-UVB alone in patients with generalized vitiligo, especially those with skin types IV– VI79. However, afamelanotide-induced excessive tanning of non-lesional skin can increase the contrast with lesional skin, thereby reducing cosmetic acceptance in lightly pigmented patients80. Additional studies are needed to determine the indications and limitations of afamelanotide therapy for vitiligo.

Janus kinase (JAK) inhibitors

Administration of the JAK inhibitors ruxolitinib and tofacitinib has been reported to lead to repigmentation of vitiligo. Further investigation is needed to determine how approaches targeting the IFN-γ–JAK–STAT1 signaling pathway that drives melanocyte destruction can be utilized to treat vitiligo (see Fig. 66.1).

HEREDITARY HYPOMELANOSIS Oculocutaneous Albinism Oculocutaneous albinism (OCA) consists of a group of genetic disorders characterized by diffuse pigmentary dilution due to a partial or total absence of melanin pigment within melanocytes of the skin, hair follicles, and eyes81. The number of epidermal and follicular melanocytes is normal. Hypopigmentation involving primarily the retinal pigment epithelium is termed ocular albinism (OA).

Epidemiology OCA is the most common inherited disorder that leads to diffuse hypomelanosis. In most populations, the estimated frequency is 1 : 20 000; however, it is as high as 1 : 1500 in some African tribes.

Pathogenesis

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All well-characterized types of OCA have an autosomal recessive inheritance pattern, although a few rare families with autosomal dominant OCA have been described82. Based upon molecular studies, four types of OCA have been defined (see Table 65.1). OCA type 1 (OCA1) results from reduced (OCA1B) or absent (OCA1A) tyrosinase activity; at least 320 distinct mutations in the tyrosinase gene (TYR) have been identified in patients with OCA183. OCA2 is due to mutations in the P gene (pink-eyed dilution; now referred to as OCA2)84. Although the function of the P protein is still debated, studies have pointed to a possible role in regulating organelle pH and facilitating vacuolar accumulation of glutathione. OCA3 results from mutations in the tyrosinase-related protein 1 (TYRP1) gene85. The TYRP1 protein is a melanocyte-specific gene product involved in eumelanin synthesis (see Fig. 65.11), probably via stabilization of tyrosinase. Both OCA1 and OCA3 appear to be endoplasmic reticulum (ER) retention diseases wherein the abnormal proteins (tyrosinase or TYRP1) never leave the ER to become incorporated into melanosomes86 (see Fig. 65.7). Of note, dysfunction of the P protein can also lead to abnormal processing and trafficking of tyrosinase. OCA4 is caused by mutations in SLC45A2 which encodes solute carrier family 45 member 2 (formerly membrane-associated transporter protein [MATP]), a transmembrane transporter with roles in tyrosinase processing and intracellular trafficking of proteins to the melanosome87. OCA5 has been linked to chromosome 4q24, but the responsible gene has not yet been identified. OCA6 was recently found to result from mutations in SLC24A5, which encodes a putative cation exchanger localized to the melanosomal membrane88. Of note, this gene was previously identified as one of the determinants of the physiologic variation in human pigmentation. Lastly, mutations in C10orf11 (chromosome 10 open reading frame 11) underlie OCA7; the C10orf11 protein is expressed in melanoblasts as well as melanocytes and is thought to have a role in melanocyte differentiation89. Autosomal recessive OA (AROA) is genetically heterogeneous, and some cases actually represent OCA1B or OCA2 but with subtle cutaneous findings. The most common form of OA is an X-linked recessive disorder caused by mutations in the G protein-coupled receptor 143 gene (GPR143; formerly OA1), which encodes a pigment cell-specific

intracellular G protein-coupled receptor that regulates melanosome formation and transport within melanocytes and cells of the retinal pigment epithelium90. Mutations in GPR143 that lead to ocular albinism can result in retention of the aberrant protein within the ER.

Clinical features Ocular manifestations

The many ocular manifestations of OA and OCA reflect a reduction in melanin within eye structures or misrouting of optic nerve fibers during development. The former leads to a translucent iris that transmits light upon globe transillumination, as well as a relatively hypopigmented retina and fovea that are associated with photophobia and reduced visual acuity; the severity of these findings correlates with the amount of reduction in melanin pigment. Misrouting of the optic fibers is thought to be responsible for the characteristic strabismus, nystagmus, and lack of binocular vision.

OCA1

There are two clinical subtypes of OCA1, based upon whether tyrosinase activity is reduced (OCA1B) or absent (OCA1A).

OCA1A

OCA1A corresponds to the classic “tyrosinase-negative” OCA. The melanocytes of the skin, hair, and eyes synthesize no melanin. The characteristic phenotype includes white hair, milky white skin, and blue–gray eyes at birth. With age, the skin color remains white and melanocytic nevi amelanotic, but the hair may develop a slight yellow tint due to denaturing of hair keratins. These patients have an extreme sensitivity to UV light and a strong predisposition to skin cancer. Reduced visual acuity is most severe in OCA1A, and some patients are legally blind.

OCA1B

Because the decrease in tyrosinase activity varies, the phenotype ranges from obvious to subtle pigmentary dilution when compared with firstdegree relatives. One of the original OCA1B phenotypes was called “yellow albinism” because of the eventual color of the patient’s hair, since the formation of yellow pheomelanin requires less tyrosinase activity. Other clinical types of OCA1B have been referred to as “minimal pigment OCA”, “platinum OCA”, and “temperature-sensitive OCA”. All of these patients have little or no pigment at birth, but they develop some pigmentation of the hair and skin during the first and second decades of life. The majority burn without tanning after sun exposure, and some degree of iris translucency is often present. Amelanotic or pigmented melanocytic nevi can develop. In the temperature-sensitive OCA1B phenotype, patients are born with white hair and skin and blue eyes. During puberty, scalp and axillary hairs remain white, but arm hairs turn light reddish brown and leg hairs turn dark brown. The abnormal tyrosinase enzyme is temperature-sensitive, losing its activity above 35°C. As a result, melanin synthesis does not occur in warmer areas of the body, akin to the phenotype of a Siamese cat, which also has temperature-sensitive tyrosinase activity.

OCA2

The OCA2 phenotype (in addition to OCA1B) corresponds to the classic “tyrosinase-positive” OCA. The clinical spectrum of OCA2 is broad, ranging from minimal to moderate pigmentary dilution of the hair, skin, and iris, with little to no ability to tan. The vast majority of individuals of African descent who have “tyrosinase-positive” OCA have OCA2. With time, pigmented melanocytic nevi and lentigines may develop in sun-exposed areas (Fig. 66.10); the latter can become rather large and darkly colored (Fig. 66.11). Another phenotype called “brown OCA” in African and African-American populations results primarily from mutations in the P gene. In these individuals, the hair and skin are light brown, the irides are gray to tan at birth, and sunburns are unusual. The hypopigmentation seen in a subset of patients with Prader–Willi syndrome (PWS) and Angelman syndrome (AS) represents a form of OCA2. PWS features hyperphagia, obesity, hypogonadism, and intellectual disability, whereas AS is characterized by severe intellectual disability, microcephaly, ataxic movements, and inappropriate laughter. Due to genomic imprinting (see Ch. 54), deletions of the 15q region (which includes the P gene) in the paternal chromosome lead to PWS,

Ocular albinism type 1 is characterized by a substantial reduction in visual acuity, hypopigmentation of the retina, and the presence of macromelanosomes in the eyes. Affected boys have nystagmus, photophobia, and foveal hypoplasia90. Their skin is usually clinically normal without notable pigmentary dilution, although hypopigmented macules have been described in affected individuals who have darkly pigmented skin. Macromelanosomes are evident on histologic examination of the skin.

Pathology Although there is a reduction in melanin content, a normal number of melanocytes are present within the epidermis.

Differential diagnosis Fig. 66.10 Oculocutaneous albinism type 2 (OCA2). African patient with obvious squamous cell carcinomas on the cheek as well as multiple pigmented lentigines. Courtesy, James Nordlund, MD.  

This is outlined in Fig. 66.12. Occasionally, patients with total body vitiligo may be thought to have OCA, but their epidermis lacks melanocytes.

Treatment

CHAPTER

66 Vitiligo and Other Disorders of Hypopigmentation

Ocular albinism type 1 (OA1)

No specific treatment is available. Photoprotection (sunscreens, hats, clothing, sun avoidance) is mandatory in patients who have minimal or no pigmentation, in order to avoid cutaneous photocarcinogenesis, in particular the development of squamous cell carcinomas. The latter are a significant cause of morbidity and mortality, especially in tropical regions (see Fig. 66.10). All patients should undergo ophthalmologic evaluation early in life, with longitudinal care as required. Nitisinone, which is FDA approved for treating hereditary tyrosinemia type 1, represents a potential therapy for OCA. In a mouse model of OCA1B, administration of this agent elevated plasma tyrosine levels and led to increased pigmentation of the hair and eyes92.

Piebaldism Piebaldism is an uncommon autosomal dominant disorder characterized by poliosis and congenital, stable, circumscribed areas of leukoderma due to an absence of melanocytes within involved sites. Fig. 66.11 Oculocutaneous albinism type 2 (OCA2). African patient with hypopigmented hair and large pigmented lentigines. Courtesy, James Nordlund, MD.  

while deletions in the maternal chromosome give rise to AS. Approximately 1% of patients with AS or PWS also have OCA2, which occurs when deletion of one copy of the P gene is accompanied by a mutation in the second copy.

OCA3

The phenotypes of individuals with OCA3 are classified as “rufous” (vast majority of OCA3 patients) and “brown” (more often seen in OCA2). Rufous OCA has been identified in individuals with type III–V skin color, and the phenotype includes a red–bronze skin color, ginger-red hair, and blue or brown irides. Rufous OCA is associated with mutations in TYRP1. A patient with the brown OCA phenotype due to mutations in both copies of TYRP1 has also been described: an African-American child with light brown skin, light brown hair and blue–gray irides.

OCA4

OCA4 is most common among individuals with albinism who are from Japan (~25% of patients), China (10–20% of patients), or India (~10% of patients), and it accounts for ~5% of albinism in Caucasians91. The phenotype of OCA4 is variable; hair color ranges from white to yellow or brown, and patients may or may not develop increased pigmentation of the skin and hair over time.

OCA5–7

OCA5 was described in a consanguineous Pakistani family, in which affected individuals had white skin and golden hair. Patients with OCA6 from China and French Guiana were said to have white to light brown skin with some ability to tan, yellow hair at birth that darkened with age, and light brown irides88. OCA7 has been described primarily in patients from the Faroe Islands of Denmark; affected individuals have lighter skin than their relatives and hair color ranging from light yellow to brown89.

Epidemiology The exact prevalence of this condition is not known, but it is estimated to occur in approximately 1 in 40 000 Caucasians.

Pathogenesis Piebaldism usually results from mutations in the KIT proto-oncogene93, which encodes a member of the tyrosine kinase family of transmembrane receptors that is found on the surface of melanocytes (see Fig. 65.2). A functioning KIT receptor is required for the normal development of melanocytes, both immediately before melanoblast migration from the neural crest and postnatally. Heterozygous deletion of SNAI2, which encodes a transcription factor important to melanocyte development, has been found to cause piebaldism in a few patients.

Clinical features The leukoderma has a characteristic distribution pattern that favors the central anterior trunk, mid extremities, central forehead, and midfrontal portion of the scalp; the latter results in a white forelock (Fig. 66.13). The lesions are present at birth and classically spare the posterior midline. The white forelock, which is found in 80–90% of patients, is the most familiar feature of piebaldism. However, its absence does not exclude the diagnosis. All the hairs of the forelock are white, and the underlying skin is also amelanotic. This depigmented patch is midline in location, triangular or diamond-shaped, and often symmetrical. The apex can reach the vertex posteriorly, and the affected area may extend to the root of the nose and include the medial third of the eyebrows; involvement of the nose is rare. The areas of leukoderma are distinctive and can establish the diagnosis of piebaldism, even in the absence of a white forelock. They are irregular in shape, well-circumscribed, and milk-white in color. Normally pigmented and hyperpigmented macules and patches, ranging from a few millimeters to several centimeters in diameter, are typically

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Fig. 66.12 Differential diagnosis of diffuse pigmentary dilution with onset at birth or during infancy. Patients with Griscelli syndrome and Chédiak–Higashi syndrome (CHS) have silvery hair and those with CHS can have an admixture of hyper- and hypopigmentation in chronically sun-exposed skin. Additional rare causes of diffuse pigmentary dilution include deficiency of the endosomal adaptor p14 and biallelic KIT mutations.  

Pigmentary Disorders

DIFFERENTIAL DIAGNOSIS OF DIFFUSE PIGMENTARY DILUTION WITH AN ONSET AT BIRTH OR DURING INFANCY Diffuse pigmentary dilution

Adapted from Bolognia JL. A clinical approach to leukoderma. Int J Dermatol. 1999;38:568–72.

Eyes, skin and hair

Skin and/or hair

Menkes syndrome

Oculocutaneous albinism

OCA 1

OCA 2

Griscelli syndrome

**

Ectodermal dysplasia Apert syndrome Pseudothalidomide syndrome Sialic acid storage disease

Nutritional deficiencies, e.g. selenium, copper

*

Phenylketonuria Histidinemia Homocystinuria

OCA 3–7

Prader−Willi syndrome Angelman syndrome

Hermansky−Pudlak syndrome Chédiak−Higashi syndrome Cross syndrome

Tietz syndrome

*

*Eye findings in these patients can be subtle or absent **With ectodactyly and cleft lip/palate (EEC)

Fig. 66.13 Piebaldism. White forelock and characteristic triangular amelanotic patch on the mid-forehead. Courtesy, Julie V Schaffer, MD.  

apparent within the leukodermic patches (Fig. 66.14). Hyperpigmented patches also occur within uninvolved skin and should not be misinterpreted as evidence of neurofibromatosis 1. Poliosis of the eyebrows and eyelashes is a common finding, as are white hairs within areas of leukoderma. Limited contraction of the areas of involvement over time is occasionally observed, and premature graying of the hair is not uncommon.

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Fig. 66.14 Piebaldism. Characteristic involvement of the mid extremities. Note the normally pigmented and hyperpigmented macules within the leukoderma.  

Courtesy, Julie V Schaffer, MD.

Pathology

Differential diagnosis

By light and electron microscopy, no melanocytes can be identified in either the interfollicular epidermis or the hair follicles of amelanotic skin94. The hyperpigmented macules are characterized by an abundance of melanosomes in the melanocytes and keratinocytes.

The presence of stable amelanotic patches since birth, the characteristic distribution pattern, and the distinctive normally pigmented or hyperpigmented macules within the areas of leukoderma allow the differentiation of piebaldism from vitiligo. The differential diagnosis of

Treatment Autografting of normal skin or melanocytes into amelanotic areas represents a therapeutic option, but this typically requires multiple procedures. Cosmetic products can be used to camouflage affected areas; protection against sunburn is also necessary.

Waardenburg Syndrome Waardenburg syndrome (WS) is a rare autosomal dominant or less often autosomal recessive disorder that is characterized by various combinations of the following features97: achromia of the hair, skin, or both in the same pattern as piebaldism (see above) congenital deafness partial or total heterochromia irides (including isohypochromia) medial eyebrow hyperplasia (synophrys) a broad nasal root dystopia canthorum (increased distance between the inner canthi, with a normal interpupillary distance).

• • • • • •

DIFFERENTIAL DIAGNOSIS OF CIRCUMSCRIBED SCALP POLIOSIS

Inflammatory, autoimmune, or traumatic Vitiligo Halo nevus • Alopecia areata (primarily initial cycle of growth) • Postinflammatory (e.g. discoid lupus, blepharitis [eyelashes]) • Postinfectious (e.g. zoster) • Post-traumatic • Vogt–Koyanagi–Harada syndrome • Alezzandrini syndrome • Melanoma-associated leukoderma (spontaneous or following immunotherapy) • •

Inherited Tuberous sclerosis* Piebaldism (midline frontal) • Waardenburg syndrome (primarily midline frontal) • Isolated white forelock† • Isolated occipital white lock (X-linked recessive) • White forelock with osteopathia striata (autosomal or X-linked dominant) • White forelock with multiple malformations (autosomal or X-linked recessive) • Neurofibromatosis type 1 – overlying a neurofibroma • Prolidase deficiency and Marfan syndrome (single case reports) • •

Nevoid Angora hair nevus Associated with nevus comedonicus • Scalp heterochromia secondary to mosaicism * • •

Pharmacologic agents Imiquimod Latanoprost (eyelash poliosis) • Tyrosine kinase inhibitors (e.g. eyelash poliosis with cetuximab) • •

Idiopathic

*May be lighter than surrounding hair rather than white (e.g. blond streaks in a patient with brown hair).

†Separate entity vs possible forme fruste of piebaldism.

Table 66.3 Differential diagnosis of circumscribed scalp poliosis. Adapted from  

Bolognia JL, Shapiro PE. Albinism and other disorders of hypopigmentation. In: Arndt KA, et al (eds). Cutaneous Medicine and Surgery. Philadelphia: WB Saunders, 1995.

Four clinical subtypes of WS have been described (Table 66.4): WS type I, the classic form (WS1); WS type II, which lacks dystopia canthorum (WS2); WS type III, with associated limb abnormalities (WS3, Klein– Waardenburg syndrome); and WS type IV, with Hirschsprung disease (WS4, Shah–Waardenburg syndrome).

Epidemiology The incidence of WS in the Netherlands has been estimated as ~1 in 200 000. In the US, deafness in the setting of WS afflicts 1 in 50 000. WS has been observed in various races and from all regions of the world. Men and women are equally affected.

Pathogenesis The facial dysmorphism seen in WS points to abnormal fetal development. It is therefore not surprising that several of the genes responsible for WS (PAX3, MITF, SNAI2, SOX10; see Table 66.4) encode transcription factors that, by binding DNA and regulating the expression of other genes, have important functions during embryogenesis (see Fig. 65.4). The neural crest is the source of the connective tissues of the head and neck and intestinal ganglion cells as well as melanoblasts, explaining the manifestations of this neurocristopathy. Presumably, the deafness in WS reflects the role of melanocytes in the development of the inner ear. The PAX3 transcription factor that is mutated in WS1 and WS3 activates melanoblasts and other cells to proliferate and then migrate from the neural crest. The abnormalities of the upper extremities that characterize WS3 imply that PAX3 also regulates limb development98. Mutations in the microphthalmia-associated transcription factor gene (MITF; expression of which is regulated by PAX3 and SOX10), which encodes a helix-loop-helix/leucine zipper transcription factor, can result in WS2. Of note, a mutation in MITF that affects the nuclear localization of this protein underlies Tietz syndrome (see below)99. In addition to its critical role in melanocyte development, MITF regulates the expression of a number of melanocyte-specific genes (e.g. tyrosinase; see Ch. 65). Homozygous deletion of SNAI2 (the expression of which is regulated by MITF) has also been identified as a cause of WS2. SNAI2 is a zinc finger transcription factor that has an essential role in the development of neural crest-derived cells, and its complete absence leads to both auditory and pigmentary abnormalities100. The SOX10 transcription factor plays an essential role in the development of melanoblasts and ganglion cells, and mutations in this gene can cause WS4 or (if milder) WS2101. WS4 can also be caused by mutations in the genes encoding the endothelin B receptor and its endothelin-3 ligand102. The endothelin B receptor is found on melanoblast-ganglion cell precursors in the developing neural crest, and its binding to endothelin-3 is essential for the generation of these cell types (see Fig. 65.3).

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66 Vitiligo and Other Disorders of Hypopigmentation

circumscribed poliosis of scalp hairs is broad and includes both inherited and acquired causes (Table 66.3)95. Of note, an isolated white forelock can also be inherited as an autosomal dominant trait. The diagnosis of piebaldism should prompt the clinician to exclude the possibility of Waardenburg syndrome via an ocular examination and evaluation of hearing. Albinism–deafness syndrome (Ziprkowski– Margolis or Woolf syndrome), a rare X-linked disorder linked to Xq26.3– q27.1, presents with congenital sensorineural deafness and a severe piebald-like phenotype with extensive areas of hypopigmentation96.

Clinical features Waardenburg syndrome type 1 (WS1)

A white forelock, generally similar to that of piebaldism, is the most frequently observed pigmentary abnormality in WS (20–60% of patients). Although the forelock is usually white, patches of red, brown, or black hair have also been described. A few patients have additional areas of poliosis in the frontoparietal or occipital scalp. Premature graying can involve the scalp hair, eyebrows, and body hair, and the onset may be as early as the teens. Areas of leukoderma with an appearance, distribution pattern, and natural history similar to piebaldism have been observed in ~15% of patients. The prevalence of hearing impairment ranges from 10% to >35%103; it may be bilateral or unilateral and severe or moderate. Heterochromia irides, partial (sectorial) or complete, is found in >20% of patients (Fig. 66.15). Complete heterochromia irides gives rise to irides of different colors, one being whitish blue. Bilateral involvement results in bilateral pale blue eyes (isohypochromia). Hypomelanotic fundi may be present. The eyebrows may be confluent (synophrys) or show hyperplasia of their medial portions (15–70% of patients). The characteristic dystopia canthorum represents an increase in the distance between the inner canthi, with normal distances between the pupils and between the outer canthi. This is accompanied by a shortening in the length of the palpebral fissure (blepharophimosis) and a lateral displacement

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DISORDERS OF MELANOCYTE DEVELOPMENT

Human disease

Mouse model

Inheritance

Gene

Protein

Piebaldism*

Dominant spotting

AD

KIT

KIT tyrosine kinase

AD

SNAI2

Snail homolog 2 transcription factor

Splotch

AD

PAX3

Paired box 3 transcription factor

Microphthalmia

AD

MITF

Microphthalmia-associated transcription factor

AR

SNAI2

Snail homolog 2 transcription factor

Waardenburg syndrome WS1 WS2**

A D

AD

SOX10

SRY-box 10 transcription factor

Splotch

AD≫AR†

PAX3

Paired box 3 transcription factor

A

Piebald spotting

AD, AR

EDNRB

Endothelin B receptor

B

Lethal spotting

AD, AR

EDN3

Endothelin-3

C

Dominant megacolon

AD

SOX10

SRY-box containing 10

E WS3 WS4

Tietz syndrome

AD

MITF

Microphthalmia-associated transcription factor

Albinism, black lock, cell migration disorder of the neurocytes of the gut, and deafness (ABCD) syndrome

AR

EDNRB

Endothelin receptor type B

*Diffuse pigmentary dilution of the skin, hair, and eyes as well as deafness and developmental delay have been described in patients with biallelic KIT mutations. Other forms of WS2 have been linked to 1p21–p13.3 (WS2B) and 8p23 (WS2C). ** † Homozygous PAX3 mutations have been described in individuals with WS3 whose parents were affected with WS1.

Table 66.4 Disorders of melanocyte development. AD, autosomal dominant; AR, autosomal recessive.  

Tietz syndrome

Tietz syndrome is a rare autosomal dominant disorder characterized by diffuse pigmentary dilution of the skin and hair together with deafness and hypoplasia of the eyebrows. Although the eyes are blue, affected individuals do not have photophobia or nystagmus and the fundi are normal. The clinical phenotype is significantly different from WS2, despite being allelic.

Pathology As in piebaldism, the areas of involvement in WS have an absence or minimal number of melanocytes when examined by light or electron microscopy.

Diagnosis

Fig. 66.15 Waardenburg syndrome type 2. Heterochromia irides in the absence of dystopia canthorum. The white forelock is seen in the upper left corner. Courtesy, Daniel Albert, MD.  

of the inferior lacrimal points, which are then situated in front of the cornea. The dystopia is usually symmetric but may be asymmetric. Dystopia canthorum is a characteristic feature of WS1 and WS3.

Waardenburg syndrome type 2 (WS2)

WS2 differs from WS1 primarily by the absence of dystopia canthorum. In addition, deafness is probably more common in patients with WS2.

Klein–Waardenburg syndrome (WS3)

WS3 is similar to WS1 but is also associated with upper limb abnormalities (e.g. hypoplasia, syndactyly).

Shah–Waardenburg syndrome (WS4)

1100

In WS4, the characteristic findings of WS occur in association with Hirschsprung disease. In many patients, a white forelock, amelanotic macules, and heterochromia irides are present. Deafness is fairly common, but dystopia canthorum and a broad nasal root are uncommon. Additional rare manifestations (associated with SOX10 mutations) include central nervous system dysfunction, neonatal hypotonia, and arthrogryposis.

In patients with the complete WS phenotype, the diagnosis is clear. However, there is significant clinical heterogeneity, and in some forme fruste cases the diagnosis can be difficult to establish. Examination of family members can be helpful as they may have other features of the disease.

Treatment No specific treatment is available. However, early diagnosis permits appropriate management of the deafness.

Disorders of Melanosome Biogenesis Melanosomes are considered members of the lysosome-related organelle family, which includes platelet dense granules and the lytic granules of cytotoxic lymphocytes and natural killer (NK) cells. When the biogenesis of these organelles is disrupted, affected individuals present with the clinical findings of OCA due to their defective melanosomes together with additional symptoms (e.g. bleeding diathesis, immunodeficiency) that reflect abnormalities in other lysosome-related orgenelles104,105. These genetic diseases include Hermansky–Pudlak syndrome (HPS) and Chédiak–Higashi syndrome (CHS).

Hermansky–Pudlak syndrome To date, ten subtypes of HPS have been identified, each of which is inherited in an autosomal recessive manner (see Table 65.1)106.

Pathogenesis

Most forms of HPS result from mutations in genes that encode components of the biogenesis of lysosome-related organelles complexes 1–3

Clinical features Compared to unaffected first-degree relatives, patients with HPS have pigmentary dilution of the skin, hair, and eyes. The degree varies, depending upon the underlying mutations and the patient’s ethnic origin. With age, an increase in pigmentation is usually seen, but patients still have difficulty tanning. Ocular manifestations of albinism, such as nystagmus and reduced visual acuity, are also present. Systemic manifestations due to organelle dysfunction include a bleeding tendency (e.g. with tooth extraction or childbirth) as well as interstitial pulmonary fibrosis and granulomatous colitis secondary to ceroid lipofuscin accumulation within lysosomes. Granulomatous plaques and “knife-cut” ulcers of the vulva, intertriginous areas, and peristomal skin similar to cutaneous Crohn disease have also been described108. Less often, renal failure and cardiomyopathy develop, usually during adulthood. Patients with HPS2 and 10 experience recurrent bacterial infections due to neutropenia and abnormal cytotoxic T-cell function, and HPS10 presents with neurodevelopmental delay and seizures.

Laboratory findings and pathology

By electron microscopy, macromelanosomes as well as stage I to III (rarely stage IV) melanosomes are seen. Although the platelet count is normal, the bleeding time and platelet function analyzer (PFA)-100 time are prolonged due to platelet dysfunction. Ultrastructurally, there is an absence of dense bodies within platelets. Ceroid deposits, derived from the degradation of lipids and glycoproteins, are found within lysosomes in affected internal organs, including the lungs and gastrointestinal tract. Presumably, this reflects a defect in lysosomal function.

Differential diagnosis

In addition to the entities in Fig. 66.12, diagnostic considerations may include the autosomal recessive deficiency of the endosomal adaptor p14, which features diffuse pigmentary dilution of the skin and hair, neutropenia, and recurrent pulmonary infections.

Treatment

The development of progressive pulmonary fibrosis often leads to premature death in patients with HPS, who have an average lifespan of only 30–50 years. Although the antifibrotic agent pirfenidone appeared to slow the progression of pulmonary fibrosis in HPS1 patients in an initial controlled study, a more recent controlled trial found no benefit of this agent in HPS1 patients with mild to moderate pulmonary disease109. Platelet transfusions can be administered prior to surgical procedures in HPS patients.

Cross syndrome Cross syndrome is characterized by diffuse pigmentary dilution, silvery hair, ocular anomalies, and neurologic abnormalities (e.g. psychomotor retardation, ataxia and spasticity). A family with overlapping features of HPS and Cross syndrome has raised the possibility that this latter syndrome may be a clinical variant of HPS110.

Chédiak–Higashi syndrome Chédiak–Higashi syndrome (CHS) is a rare autosomal recessive disorder characterized by OCA with a silvery-gray cast to the hair, photophobia, nystagmus, and ocular hypopigmentation; an admixture of hyper- and hypopigmentation may be evident in chronically sunexposed skin, especially in patients with relatively dark constitutive pigmentation. Additional findings include a bleeding diathesis due to diminished function of platelet dense granules, progressive neurologic

dysfunction, and severe immunodeficiency due to abnormal lytic granules in lymphocytes, NK cells, and neutrophils (see Ch. 60). A hallmark of the disorder is the presence of giant lysosome-related organelles, including melanosomes, platelet dense granules, and neutrophil granules. Examination of a peripheral blood smear for the latter represents a simple method of screening for this condition. CHS is caused by mutations in the lysosomal trafficking regulator gene (LYST), which encodes a cytoplasmic protein that regulates fission/fusion of lysosomerelated organelles111.

Tricho-hepato-enteric syndrome (phenotypic diarrhea of infancy) This autosomal recessive disorder caused by mutations in the tetratricopeptide repeat domain 37 gene (TTC37) can present with diffuse pigmentary dilution of the skin and hair, platelet defects (including abnormal granules) and immunodeficiency. Unlike CHS, it is also characterized by brittle hair with trichorrhexis nodosa, intractable diarrhea during infancy, primary liver disease, facial dysmorphism, and cardiac defects.

Disorders of Melanosome Transport and/or Transfer

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66 Vitiligo and Other Disorders of Hypopigmentation

(BLOC1/2/3; see Table 65.1 & Fig. 65.8). These complexes are involved in the formation of lysosome-related organelles, including melanosomes, by a mechanism distinct from that of the adaptor protein 3 (AP-3) complex. The exceptions are HPS2 and the recently described HPS10, which are caused by mutations in the AP3B1 and AP3D1 genes, respectively107. These genes encode the β3A and δ1 subunits of the AP-3 complex, which is involved in protein sorting to lysosomes and lysosome-related organelles (see Fig. 65.8). AP-3 also functions in CD1b-associated antigen presentation and secretion of lytic granules from cytotoxic T cells, explaining the additional clinical feature of immunodeficiency in patients with HPS2 and 10. In addition, a neuronspecific AP-3 heterotetramer requires δ1 but not β3A; as a result, HPS10 but not HPS2 has neurologic manifestations.

Identification of the defective proteins in various forms of Griscelli syndrome (GS) has led to better understanding of processes of melanosome transport.

Epidemiology Griscelli syndrome is a rare autosomal recessive disorder.

Pathogenesis On the basis of molecular genetics (as well as clinical findings), GS has been separated into three entities, GS1, GS2, and GS3 (see Table 65.1). GS1 is due to mutations in the gene that encodes myosin Va112. One end of the myosin Va protein binds the actin cytoskeleton, while the other can bind an organelle, e.g. a melanosome. This linkage plays a key role in the transfer of melanosomes from melanocytes to keratino­ cytes. GS2 is caused by mutations in RAB27A113, which encodes a small Ras-like GTPase (belonging to the Rab family) that is present in melanosomes. GS3 is due to mutations in MLPH, whose protein product, melanophilin, serves to link myosin Va to Rab27a114 (see Fig. 65.10). Because MLPH is expressed only in melanocytes, the associated phenotype is limited to diffuse pigmentary dilution and silvery hair. On the other hand, expression of MYO5A in neurons explains the associated neurologic abnormalities in GS1, and expression of RAB27A in hematopoietic cells accounts for the immunodeficiency and hemophagocytic syndrome observed in GS2. Elejalde syndrome is now thought to likely represent a variant of GS1.

Clinical features All three types of GS are characterized by pigmentary dilution of the skin and silvery-gray hair due to pigment clumping within melanocytes. As noted above, patients with GS1 exhibit primarily neurologic impairment112, while those with GS2 have immune abnormalities due to defective release of cytotoxic lysosomal contents from hematopoietic cells. A hemophagocytic syndrome can also occur in GS2, with uncontrolled T-lymphocyte and macrophage activation leading to death113; this process can involve the CNS in a secondary manner.

Treatment Hematopoietic stem cell transplantation is indicated for the treatment for GS2 (but not GS1 or GS3).

Tuberous Sclerosis Complex Tuberous sclerosis complex (TSC) represents an autosomal dominant disorder characterized by hamartomas in multiple organs, most commonly the skin, brain, eye, heart, and kidney (see Ch. 61).

Clinical features The classic TSC triad of facial angiofibromas (“adenoma sebaceum”), seizures, and intellectual disability is preceded by the appearance of

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white macules. In one study utilizing Wood’s lamp examination, hypomelanotic macules were found in 64 of 65 patients with TSC. Hypomelanotic macules are often evident at birth or during the neonatal period. In fact, all lesions are probably present at birth, but they may be inapparent, particularly in lightly pigmented infants, until the skin is exposed to UV light or the patient is examined with a Wood’s lamp. The number of lesions varies from one to >100 per patient. The vast majority of patients have 2–20 hypomelanotic macules, with 50% having 200 guttate, minimally elevated hypopigmented papules. The lesions developed after several months of PUVA therapy. Histologically, there was no evidence of verruca plana. B Clear cell papulosis presenting as multiple hypopigmented, barely elevated, small flat-topped papules and macules in the suprapubic area and on the abdomen along the “milk lines” in a 2-year-old boy. Histologically, these lesions are characterized by large clear cells in the lower epidermis that have a pattern of immunohistochemical staining similar to clear cells of Toker and extramammary Paget disease. C Guttate hypopigmentation in sun-exposed areas on the extensor aspect of the arm in a 3-year-old Hispanic boy with xeroderma pigmentosum. Note the sparing of the proximal upper arm, which is normally covered by a T-shirt. A, Courtesy, Jean L Bolognia, MD; B, C, Courtesy, Julie V Schaffer, MD.  

melanogenic activity, while others lack mature melanosomes. The keratinocytes show marked variation in their content of melanin, which may be absent or markedly decreased. The diagnosis of IGH is usually made clinically; the differential diagnosis of guttate leukoderma includes achromic verrucae planae, pityriasis lichenoides chronica, disseminated hypopigmented keratoses that follow PUVA therapy, and clear cell papulosis (Fig. 66.31; see Table 66.5). Although lesions of atrophie blanche favor the distal shins and ankles, these porcelain white scars are usually depressed and encircled by papular telangiectasias. The cause of IGH is unknown, but sun exposure probably plays a role. Cryotherapy with liquid nitrogen has been described as a possible therapy for IGH. As sunlight is most likely a precipitating factor, use of sunscreens and physical barriers should be recommended.

Vagabond’s Leukomelanoderma This skin disorder occurs in older persons in whom dietary deficiency is combined with lack of cleanliness and heavy infestation with Pediculus humanus var. corporis. These patients have small macules of hypomelanosis (related to scratching) superimposed on a background of diffuse hypermelanosis, especially of the wrists, axillae, groin, medial thighs, and posterior neck.

Progressive Macular Hypomelanosis Progressive macular hypomelanosis (PMH) is a fairly common skin disorder, observed more frequently in young women with darkly pigmented skin who originate from or reside in tropical climates. The

Fig. 66.32 Progressive macular hypomelanosis. Note the coalescence of the non-scaly hypopigmented macules on the center of the  

condition is characterized by poorly defined, nummular, non-scaly hypopigmented macules and small patches on the trunk, with rare extension onto the proximal extremities or head and neck region; confluence of lesions may occur centrally (Fig. 66.32)132. Another variant of PMH features large circular lesions. There is no associated pruritus or preceding inflammation, and patients are sometimes misdiagnosed as having residual hypopigmentation related to tinea versicolor. Histologically, there is decreased pigment in the epidermis and a normal-appearing dermis. Electron microscopy demonstrates a shift from large melanosomes in uninvolved skin to small aggregated membrane-bound melanosomes in hypopigmented skin. Proliferation of Propionibacterium acnes or another Propionibacterium spp. within

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hair follicles is thought to play a role in PMH pathogenesis133. Treatment regimens include various combinations of topical 1% clindamycin, 5% benzoyl peroxide, and phototherapy with NB-UVB or UVA (e.g. three times weekly for 12 weeks).

DISORDERS ASSOCIATED WITH PREMATURE GRAYING OF SCALP HAIR Piebaldism Waardenburg syndrome • Vitiligo • Sudden whitening of hair • Hereditary premature canities • “Bird-headed” dwarfism • Progeria • Werner syndrome • Ataxia telangiectasia • Rothmund–Thomson syndrome • Dyskeratosis congenita • Fisch syndrome • Myotonic dystrophy • Prolidase deficiency (also in Table 66.9) • Oasthouse disease • •

Hair Hypomelanosis Poliosis refers to a circumscribed hypomelanosis of hair (see Table 66.3), whereas canities implies a more generalized depigmentation of hair. Graying of hair, localized or generalized, is characterized by an admixture of normally pigmented, hypomelanotic, and amelanotic hairs. Whitening of hair is the endpoint of canities and graying of hair. The graying and whitening of human hair that occurs with aging is due to defective maintenance of melanocyte stem cells134,135. A number of genetic disorders are associated with premature graying of hair (Table 66.8), while there are both hereditary and acquired causes of diffuse hypomelanosis of hair (Table 66.9). In Chédiak–Higashi and Griscelli syndromes, the scalp hairs have a silvery hue due to pigment clumping.

Leukodermas Without Hypomelanosis

Table 66.8 Disorders associated with premature graying of scalp hair.  

Woronoff’s ring Woronoff ’s ring is a blanched halo of fairly uniform width surrounding psoriatic lesions after phototherapy or topical treatments. There is an element of vasoconstriction, but it is uncertain whether there is any decrease in pigmentation.

Nevus anemicus Nevus anemicus presents as a pale area of variable size (often 3–6 cm) with an irregular, “broken up” outline (see Ch. 106). It is usually unilateral and located on the trunk. Present since birth, the lesion is most commonly detected later in life, and it is most noticeable when there is surrounding vasodilation due to heat or emotional stress. On diascopy, the lesion becomes indistinguishable from surrounding skin. Histologically, there are no abnormalities in the melanocytes or melanin content. Nevus anemicus is caused by decreased blood flow through the capillaries in the dermal papillae, due to a localized hypersensitivity of the blood vessels to catecholamines. Approximately 30–60% of patients with neurofibromatosis type 1 (NF1) have a nevus anemicus, and its use as a diagnostic criterion has been suggested.

Cutaneous edema and anemia Cutaneous edema and anemia also produce lightening of the skin and mucous membranes. In the case of anemia, it is due to decreased hemoglobin levels in the skin.

Angiospastic macules (Bier spots) Pale macules, usually 3–6 mm in diameter, are seen primarily on the extremities and are often more noticeable on the legs (see Ch. 106).

DISORDERS ASSOCIATED WITH DIFFUSE HYPOMELANOSIS OF SCALP HAIR Fanconi syndrome Book syndrome • Down syndrome • Hallermann–Streiff syndrome • Treacher Collins syndrome • Prolidase deficiency (also in Table 66.8) • Hyperthyroidism • Chronic protein loss or deficiency (e.g. due to kwashiorkor, nephrosis, ulcerative colitis, malabsorption) • Vitamin B12 deficiency • Tyrosine kinase inhibitors (e.g. sunitinib, imatinib, dasatinib, cabozantinib) • Antimalarials (chloroquine > hydroxychloroquine) • •

Table 66.9 Disorders associated with diffuse hypomelanosis of scalp hair. See also Fig. 66.12.  

The lesions are due to localized vasoconstriction and occur most often in young women. Their appearance may be induced by a dependent position or placing a tourniquet on the limb. Prominent or widespread angiospastic macules have been described in association with pregnancy, lymphedema, cryoglobulinemia, tuberous sclerosis, and aortic hypoplasia. For additional online figures visit www.expertconsult.com

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1. Ortonne JP, Mosher DB, Fitzpatrick TB. Piebaldism. In: Vitiligo and Other Hypomelanoses of Hair and Skin. New York: Plenum; 1983. p. 310–37. 2. Passeron T, Ortonne JP. Physiopathology and genetics of vitiligo. J Autoimmun 2005;25(Suppl.):63–8. 3. Zhang XJ, Chen JJ, Liu JB. The genetic concept of vitiligo. J Dermatol Sci 2005;39:137–46. 4. Alkhateeb A, Fain PR, Thody A, et al. Epidemiology of vitiligo and associated autoimmune diseases in Caucasian probands and their families. Pigment Cell Res 2003;16:208–14. 5. Spritz RA. The genetics of generalized vitiligo: autoimmune pathways and an inverse relationship with malignant melanoma. Genome Med 2010;2:78. 6. Shen C, Gao J, Sheng Y, et al. Genetic susceptibility to vitiligo: GWAS approaches for identifying vitiligo susceptibility genes and loci. Front Genet 2016;7:3. 7. Jin Y, Andersen G, Yorgov D, et al. Genome-wide association studies of autoimmune vitiligo identify 23 new risk loci and highlight key pathways and regulatory variants. Nat Genet 2016;48:1418–24. 8. Ratsep R, Kingo K, Karelson M, et al. Gene expression study of IL10 family genes in vitiligo skin biopsies,

peripheral blood mononuclear cells and sera. Br J Dermatol 2008;159:1275–81. 9. Gregg RK, Nichols L, Chen Y, et al. Mechanisms of spatial and temporal development of autoimmune vitiligo in tyrosinase-specific TCR transgenic mice. J Immunol 2010;184:1909–17. 10. Klarquist J, Denman CJ, Hernandez C, et al. Reduced skin homing by functional Treg in vitiligo. Pigment Cell Melanoma Res 2010;23:276–86. 11. Lili Y, Yi W, Ji Y, et al. Global activation of CD8(+) cytotoxic T lymphocytes correlates with an impairment in regulatory T cells in patients with generalized vitiligo. PLoS ONE 2012;7:e37513. 12. Kotobuki Y, Tanemura A, Yang L, et al. Dysregulation of melanocyte function by Th17-related cytokines: significance of Th17 cell infiltration in autoimmune vitiligo vulgaris. Pigment Cell Melanoma Res 2012;25:219–30. 12a.  Richmond JM, Bangari DS, Essien KI, et al. Keratinocyte-derived chemokines orchestrate T-cell positioning in the epidermis during vitiligo and may serve as biomarkers of disease. J Invest Dermatol 2017;137:350–8.

12b.  Richmond JM, Masterjohn E, Chu R, et al.   CXCR3 depleting antibodies prevent and reverse vitiligo in mice. J Invest Dermatol 2017;137:  982–5. 13. Mosenson JA, Zloza A, Nieland JD, et al. Mutant HSP70 reverses autoimmune depigmentation in vitiligo. Sci Transl Med 2013;5:174ra28. 14. Rashighi M, Agarwal P, Richmond JM, et al. CXCL10 is critical for the progression and maintenance of depigmentation in a mouse model of vitiligo. Sci Transl Med 2014;6:223ra23. 15. Maresca V, Roccella M, Roccella F, et al. Increased sensitivity to peroxidative agents as a possible pathogenic factor of melanocyte damage in vitiligo. J Invest Dermatol 1997;109:310–13. 16. Bellei B, Pitisci A, Ottaviani M, et al. Vitiligo: a possible model of degenerative diseases. PLoS ONE 2013;8:e59782. 17. Schallreuter KU, Salem MA, Holtz S, Panske A. Basic evidence for epidermal H2O2/ONOO(-)-mediated oxidation/nitration in segmental vitiligo is supported by repigmentation of skin and eyelashes after reduction of epidermal H2O2 with topical

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Vitiligo and Other Disorders of Hypopigmentation

66

eFig. 66.1 Vitiligo. Complete loss of pigment of the glans penis. Note the lack of any secondary changes. Courtesy, Jean L Bolognia, MD.  

eFig. 66.2 Inflammatory vitiligo. There is a figurate outline to the inflammatory border, which is sometimes misdiagnosed as tinea corporis.  

B

A

C

eFig. 66.3 Piebaldism. A White forelock and characteristic triangular amelanotic patch on the mid-forehead. B Mother and son with the characteristic involvement of the mid extremities. C Amelanotic patch on the upper calf. In all of these examples, note the normally pigmented macules of varying sizes within the leukoderma, especially at the periphery. A, Courtesy, Diane Davidson, MD; B, Courtesy, Jean L Bolognia, MD; C, Courtesy, Julie V Schaffer, MD.  

eFig. 66.4 Linear nevoid hypopigmentation. Note the S-shaped pattern of the hypopigmented streaks along the lines of Blaschko on the flank and abdomen.  

eFig. 66.5 Lichen striatus. Hypopigmented band along the lines of Blaschko on the  

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eFig. 66.7 Hypopigmentation due to injection of corticosteroids into the anatomic snuff box. The outline is both stellate and  

eFig. 66.6 Postinflammatory hypopigmentation in a child with atopic dermatitis. Courtesy, Antonio Torrelo, MD.  

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PIGMENTARY DISORDERS SECTION 10

Disorders of Hyperpigmentation Mary Wu Chang

Chapter Contents Diffuse and circumscribed hyperpigmentation . . . . . . . . . . . 1115 Postinflammatory hyperpigmentation . . . . . . . . . . . . . . 1115 Erythema dyschromicum perstans . . . . . . . . . . . . . . . . 1116

67 

hypermelanosis. Diffuse hyperpigmentation can also be a manifestation of metabolic diseases, sclerodermoid disorders, nutritional deficiencies, and occasionally HIV infection.

POSTINFLAMMATORY HYPERPIGMENTATION

Lichen planus pigmentosus . . . . . . . . . . . . . . . . . . . . . 1118 Melasma . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1119 Drug-induced hyperpigmentation or discoloration . . . . . . 1122

Synonym:  ■ Postinflammatory hypermelanosis

Linear hyperpigmentation . . . . . . . . . . . . . . . . . . . . . . . . 1125 Pigmentary demarcation lines . . . . . . . . . . . . . . . . . . . 1125 Linear postinflammatory hyperpigmentation . . . . . . . . . 1127 Flagellate pigmentation from bleomycin . . . . . . . . . . . . 1127 Flagellate mushroom dermatitis . . . . . . . . . . . . . . . . . . 1129 Hyperpigmentation along the lines of Blaschko . . . . . . . . 1130 Reticulated hyperpigmentation . . . . . . . . . . . . . . . . . . . . . 1131 Prurigo pigmentosa . . . . . . . . . . . . . . . . . . . . . . . . . . 1131 Dyskeratosis congenita . . . . . . . . . . . . . . . . . . . . . . . . 1132 Naegeli–Franceschetti–Jadassohn syndrome . . . . . . . . . . 1136

Key features ■ Extremely common, especially in individuals with more darkly pigmented skin ■ Develops after inflammation or injury to the skin, but preceding inflammation may be transient or subclinical ■ The increased melanin may be primarily within the dermis (e.g. following lichen planus) or in the epidermis (e.g. following acne or atopic dermatitis) ■ Epidermal hyperpigmentation fades more readily than dermal hyperpigmentation

Dermatopathia pigmentosa reticularis . . . . . . . . . . . . . . 1137 X-linked reticulate pigmentary disorder . . . . . . . . . . . . . 1137 Dowling–Degos disease . . . . . . . . . . . . . . . . . . . . . . . 1138

Introduction

Reticulate acropigmentation of Kitamura . . . . . . . . . . . . 1139

PIH represents an acquired excess of melanin pigment following cutaneous inflammation or injury. It can occur anywhere on the skin surface, including the mucous membranes and the nail unit. PIH is extremely common and can have significant cosmetic and psychosocial consequences.

Dyschromatoses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1139 Dyschromatosis symmetrica hereditaria . . . . . . . . . . . . . 1140 Dyschromatosis universalis hereditaria . . . . . . . . . . . . . . 1142

Epidemiology Skin color depends upon the amount and distribution of melanin and other pigments such as hemoglobin, which can influence light absorption, reflection, and scattering. Disorders of hyperpigmentation usually result from an increase in melanin production and, on occasion, from an increase in the density of active melanocytes. Discoloration of the skin may also be caused by deposition of exogenous substances such as drugs, drug complexes (e.g. with melanin or iron), or heavy metals within the dermis. To aid in the clinical approach, disorders of hyperpigmentation can be divided into diffuse, circumscribed, linear, and reticulated subsets (Fig. 67.1). A discussion of each of these categories is followed by an overview of dyschromatoses, disorders characterized by both hypo- and hyperpigmentation. Benign melanocytic neoplasms are covered in Chapter 112.

DIFFUSE AND CIRCUMSCRIBED HYPERPIGMENTATION Introduction Diffuse and circumscribed hyperpigmentation are discussed together because both postinflammatory hyperpigmentation (PIH) and reactions to systemic drugs, two major causes of hyperpigmentation, can assume either of these patterns. PIH most often presents as circumscribed lesions, and the size, shape, and distribution pattern provide clues to the etiology. Melasma is another common cause of circumscribed

PIH can occur at any age and there is no gender preference. Individuals with darkly pigmented skin tend to have a greater frequency, severity, and duration of PIH than those with lighter complexions.

Pathogenesis In the epidermal form of PIH, there is increased melanin production and/or transfer to keratinocytes. Inflammatory mediators (e.g. prostaglandins E2 and D2) that enhance pigment production may play a role in this process. In dermal hyperpigmentation, melanin enters (“falls into”) the dermis via a damaged basement membrane, where it is phagocytosed by and subsequently resides within dermal macrophages (referred to as melanophages). Macrophages may also migrate into the epidermis, phagocytose melanosomes, and then return to the dermis. Melanin within dermal melanophages tends to persist for long periods of time (e.g. years).

Clinical Features Asymptomatic hyperpigmented macules and patches range in color either from tan to dark brown (epidermal melanin) or from gray–blue to gray–brown (dermal melanin). Primary lesions of the underlying inflammatory disorder may or may not be evident admixed with the hyperpigmentation or elsewhere. When primary lesions are absent, the size, shape, and distribution pattern of the hyperpigmented lesions may provide clues to the underlying etiology (Table 67.1). PIH can be exa­ cerbated by continued inflammation, trauma, exposure to ultraviolet (UV) irradiation, or treatment-related irritation.

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Disorders of hyperpigmentation usually result from an increase in melanin production, which is occasionally associated with an increased density of active melanocytes. Skin discoloration may also be caused by dermal deposition of exogenous substances such as drugs or heavy metals. Clinically, disorders of hyperpigmentation can be classified into diffuse, circumscribed, linear, and reticulated subsets. This chapter reviews disorders within each of these categories, including both common and rare conditions. A discussion of dyschromatoses, disorders characterized by both hypo- and hyperpigmentation, follows.

diffuse hyperpigmentation, flagellate pigmentation, reticulated hyperpigmentation, linear hyperpigmentation, postinflammatory hyperpigmentation, dyschromatosis, melasma, erythema dyschromicum perstans, pigmentary demarcation lines, pigmentary mosaicism, flagellate pigmentation, prurigo pigmentosa, dyskeratosis congenital, Naegeli–Franceschetti–Jadassohn syndrome, dermatopathia pigmentosa reticularis, X-linked reticulate pigmentary disorder, Dowling–Degos disease, reticulate acropigmentation of Kitamura, dyschromatosis symmetrica hereditaria, dyschromatosis universalis hereditaria

CHAPTER

67 Disorders of Hyperpigmentation

ABSTRACT

non-print metadata KEYWORDS:

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Fig. 67.1 Approach to disorders of hyperpigmentation.  

Pigmentary Disorders

APPROACH TO DISORDERS OF HYPERPIGMENTATION

Disorders of hyperpigmentation

Circumscribed

Postinflammatory hyperpigmentation

Melasma

Diffuse

Linear

Reticulated

Exclude dyschromatosis

Exclude reticulated erythema (e.g. livedo reticularis, early stage erythema ab igne)

Druginduced

Exclude poikiloderma (e.g. poikiloderma of Civatte, dermatomyositis, lupus erythematosus)

See Table 67.1

See Table 67.4

See Figure 67.10

See Table 67.6

See Table 67.7

Disorders that commonly lead to epidermal PIH include acne, insect bites, pyodermas, atopic dermatitis, psoriasis, and pityriasis rosea (Fig. 67.2A–D). In contrast, dermal PIH is associated with dermatoses characterized by degeneration of the basal layer of the epidermis and inflammation at the dermal–epidermal junction, such as lichen planus, lichenoid drug reactions, lupus erythematosus, and fixed drug eruptions (Fig. 67.2E). Upon treatment of the underlying disorder, epidermal PIH generally resolves over time, although fading may require months or years in darkly pigmented individuals. Dermal melanosis tends to persist longer and is sometimes permanent.

Pathology Epidermal PIH is characterized by increased pigment in keratinocytes and dermal PIH by melanophages within the dermis.

Differential Diagnosis The size, shape, and distribution of the hyperpigmented lesions can provide clues to the inflammatory disease or injury that preceded PIH (see Table 67.1), and a thorough skin examination may detect active primary lesions. A history of prior inflammatory lesions and medication use (including prescription, over-the-counter, and alternative products) should be obtained. Disorders such as erythema dyschromicum perstans, melasma, pityriasis versicolor, and atrophoderma of Pasini and Pierini should be considered in patients without evidence of preceding inflammation by history or on examination. Occasionally, a biopsy may assist in establishing the diagnosis.

Treatment

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Provided that the underlying dermatosis is successfully treated, PIH eventually improves in most patients, especially those with epidermal hypermelanosis. Sun protection, including daily application of a broadspectrum sunscreen, can help to prevent accentuation of the pigmentation by UV exposure. Topical hydroquinone (2–4%) may lead to lightening over 3–6 months if the increase in pigmentation is limited to the epidermis. As with melasma (see below), use of a topical retinoid and corticosteroid together with hydroquinone may be more effective than monotherapy. Topical azelaic acid, α-hydroxy acid, L-ascorbic acid, and kojic acid as well as arbutin, licorice extracts, mequinol, niacinamide, N-acetyl glucosamine, and soy are additional potential therapeutic options1. However, it is important to avoid irritant contact dermatitis

See Table 67.10

from any topical agent. Chemical peels (e.g. with salicylic or glycolic acid) and laser therapy may be of benefit but can also result in hypopigmentation, especially in patients with darkly pigmented skin. Q-switched ruby, alexandrite, and Nd:YAG lasers are variably successful in removing dermal pigment (see Ch. 137).

ERYTHEMA DYSCHROMICUM PERSTANS Synonyms:  ■ Ashy dermatosis ■ Dermatosis cenicienta

Key features ■ Most common in individuals with skin phototypes III–IV ■ Gray–brown to blue–gray macules and patches in a symmetric distribution ■ Favors the neck, trunk, and proximal extremities ■ A consistently effective treatment is not currently available

Introduction Ramirez first described erythema dyschromicum perstans (EDP) in 1957, referring to affected individuals as los cenicientos (ashen ones). This is an asymptomatic, slowly progressive eruption that is characterized by circumscribed areas of dermal pigmentation2.

Epidemiology Although EDP occurs worldwide, it is most common in Latin America. There is no gender preference. The disorder usually presents during the second to third decade, but it occasionally develops in younger children or older adults.

Pathogenesis The etiology of EDP is not known. Although it has been postulated that a cell-mediated immune reaction to an ingestant, contactant, or

CHAPTER

Inflammatory disease

Clinical clues

Common Acne vulgaris

Head/neck region, upper trunk; 90% of cases), with a predilection for individuals of African descent16, and M. canis is the second most frequent etiology. Globally, there is significant variation in the epidemiology of tinea capitis. While M. canis is a common cause in many countries, T. tonsurans has emerged as a major agent in Europe and elsewhere. The incidence of tinea capitis due to T. violaceum, which is endemic in Africa, has also recently increased in some areas of the US and Europe (especially western and Mediterranean regions), likely reflecting immigration patterns. The anthropophilic dermatophyte M. audouinii, which was once common and then subsequently diminished secondary to social and therapeutic advances, has more recently reappeared in Europe and may also potentially re-emerge in the US. Different clinical presentations arise from the various causative organisms. For example, T. tonsurans causes an endothrix infection (see below), which classically results in “black dot” tinea capitis due to hair breakage near the scalp. In contrast, M. audouinii is an ectothrix form of tinea capitis that typically presents with dry, scaly patches of alopecia (“gray patch” tinea capitis). Both the pathogenicity of the culprit organism and the host immune response are factors that determine the severity of disease. Tinea capitis can range from non-inflammatory scaling that resembles seborrheic dermatitis (especially with T. tonsurans; Fig. 77.12A) to a severe pustular reaction with alopecia, known as a kerion. Alopecia with or without obvious scale is the most common presentation of tinea capitis (Fig. 77.12B–D). The alopecia may occur in discrete patches or involve the entire scalp. Use of dermoscopy can highlight “comma”, “corkscrew”, and dystrophic broken hairs that represent clues to the diagnosis of tinea capitis (see Ch. 69)17. Many patients have posterior cervical and posterior auricular lymphadeno­ pathy, which is helpful in differentiating tinea capitis from less inflammatory causes of alopecia, such as alopecia areata. A kerion results from advanced disease coupled with an exaggerated host response that leads to boggy, purulent plaques with abscess formation and associated alopecia (Fig. 77.12E). Some patients may even become systemically ill with extensive lymphadenopathy. The hair in the affected area usually returns, but the longer the infection persists, the more likely the alopecia will be permanent. If a kerion is misdiagnosed as a bacterial abscess and treated with antibiotics following incision and drainage, the infection will likely worsen, thereby increasing the likelihood of scarring alopecia.

The “carrier state” of T. tonsurans refers to a clinical situation in which there are no obvious signs or symptoms of a scalp infection, yet a positive fungal culture is obtained. Although also seen in children, this typically occurs in adults who have been exposed to infected children. The carriers shed the fungus and are considered contagious18. Consequently, some experts advocate treating all carriers with oral or topical antifungals. For those dermatophytes that invade hair, three patterns of invasion exist: endothrix, ectothrix, and favus (Fig. 77.13): The endothrix pattern results from infection with anthropophilic fungi in the genus Trichophyton and is characterized by nonfluorescent arthroconidia within the hair shaft (Fig. 77.12F). The clinical presentation varies from scaling to “black dots” with patchy alopecia to kerion formation. T. tonsurans and T. violaceum are important causes of endothrix infection. The ectothrix pattern occurs when arthroconidia are formed from fragmented hyphae outside the hair shaft (see Fig. 77.13). Cuticle destruction ensues. Ectothrix infection can be fluorescent (Microsporum) or non-fluorescent (Microsporum and Trichophyton), as determined by Wood’s lamp examination. Clinical features vary from patchy, scaly alopecia with little inflammation that may mimic alopecia areata to kerion formation. Favus is the most severe form of dermatophyte hair infection and is most frequently caused by T. schoenleinii. Hyphae and air spaces are observed within the hair shaft, and a bluish-white fluorescence by Wood’s light examination is typically seen. Favus presents as thick, yellow crusts composed of hyphae and skin debris (“scutula”). Scarring alopecia may develop in chronic infections (Fig. 77.14). There are many scalp and hair disorders that lead to scaling or alopecia (scarring and non-scarring) that are not due to fungal infections (see Table 77.9). However, one should always consider and exclude a fungal infection (especially in children), because the treatment is typically quite simple and effective, and chronic untreated tinea capitis can lead to scarring alopecia. Oral therapy is required, as the drug must penetrate the hair follicle to be effective. Preventative measures are also important in the management of tinea capitis. Because the disease is contagious, all individuals residing with the infected patient should be examined for signs of tinea capitis and appropriately treated. Chronicity may develop if a child is continually re-exposed from untreated family members. Appropriate adjunctive treatment for household contacts as well as the patient includes regular (e.g. every other day) use of an antifungal shampoo, such as 2% ketoconazole or 2.5% selenium sulfide, until the patient is free of disease. Although routine screening in schools is difficult, screening children who have two or more infected







CHAPTER

Fungal Diseases

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Fig. 77.12 Tinea capitis. The range of clinical presentations of tinea capitis due to Trichophyton tonsurans, from mild scalp scaling (A) to patchy alopecia with black dots (B) or scale (C) to large areas of alopecia with pustules and scale-crust (D). E Kerion formation due to T. tonsurans. F Microscopic examination of involved hairs demonstrates an endothrix pattern (KOH–chlorazol black stain). G Histologic examination shows arthroconidia and hyphae within hair shafts to the level of Adamson’s fringe (limit of the zone of keratinization; inset). B, Courtesy, Louis A Fragola, Jr, MD;  

G, Courtesy, Lorenzo Cerroni, MD.

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Fig. 77.13 The three patterns of hair invasion and the causative dermatophytes.  

THE THREE PATTERNS OF HAIR INVASION AND THE CAUSATIVE DERMATOPHYTES Ectothrix M. canis M. audouinii M. ferrugineum M. distortum M. gypseum T. rubrum (rarely)

*

* * *

Endothrix T. tonsurans T. violaceum T. soudanense T. gourvilli T. yaoundei T. rubrum (rarely)

Arthroconidia Hyphae and air spaces

Favus T. schoenleinii

** *Displays yellow fluorescence with Wood's lamp examination **Displays blue−white fluorescence with Wood's lamp examination Fig. 77.14 Favus due to Trichophyton schoenleinii. Scarring alopecia with erosions and several scutula on the occipital scalp. The latter represent masses of keratin plus fungi.  

Courtesy, Israel Dvoretzky, MD.

different associated morbidities and complications that can affect diagnostic considerations and therapeutic options. These include bacterial superinfection (the “dermatophytosis complex”), dermatophytid reactions, cellulitis (especially in patients who have venous hypertension, harvested saphenous veins, and chronic edema), and even osteomyelitis leading to amputation in diabetics. Other conditions that can mimic tinea pedis are listed in Table 77.9. KOH examination and culture easily differentiate the moccasin and inflammatory forms of tinea pedis from these entities21. Erythrasma can be diagnosed with Wood’s light examination because of its “coral red” fluorescence. Oral antifungal therapy should be considered in diabetics, immunocompromised patients, and those with moccasin-type tinea pedis. Finally, other dermatophyte infections often occur together with tinea pedis – in particular, tinea cruris, onychomycosis, and tinea manuum – and these sites should be examined (Fig. 77.16).

Tinea unguium (dermatophytic onychomycosis)

classmates may be beneficial19. Combs, brushes and headwear used by the patient should be disinfected or preferably discarded.

Tinea pedis

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Tinea pedis is a dermatophyte infection of the soles and interdigital web spaces of the feet. Infection of the dorsal aspect of the foot is considered tinea corporis. The feet are the most common location for dermatophyte infections, and the majority of the US adult population has experienced tinea pedis. This condition is more common in adults than children and is found around the world, affecting both sexes. The lack of sebaceous glands and the moist environment created by occlusive shoes are important factors in the development of tinea pedis20. In fact, tinea pedis is uncommon in populations that do not wear shoes. However, the fungus may be acquired from going barefoot (locker rooms, gyms, public facilities). The dermatophytes that are typically responsible for tinea pedis are T. rubrum, T. interdigitale (previously T. mentagrophytes var. interdigitale), T. mentagrophytes, E. floccosum, and T. tonsurans (in children). Non-dermatophyte pathogens that produce clinical findings identical with tinea pedis include Neoscytalidium dimidiatum and N. hyalinum (moccasin and interdigital types) and, occasionally, Candida spp. (interdigital type). There are four major clinical types of tinea pedis, as outlined in Table 77.11: moccasin (Fig. 77.15A), interdigital (Fig. 77.15B), inflammatory (Fig. 77.15C), and ulcerative. Each type has

Onychomycosis is a term used to encompass all fungal infections of the nail and includes those due to dermatophytes as well as nondermatophytes. It is divided into three patterns based upon the point of fungal entry into the nail unit: distal/lateral subungual, with invasion via the hyponychium (most common; Fig. 77.17A–C) superficial white, with direct penetration into (and usually confinement to) the dorsal surface of the nail plate (often due to T. interdigitale; Fig. 77.17D) proximal subungual, with invasion under the proximal nail fold (frequently in immunocompromised hosts) mixed pattern, with ≥2 of the above patterns in the same nail. Onychomycosis can be challenging to manage due to difficulties in diagnosis, the requirement for long treatment periods, potential side effects of systemic medications, and frequent recurrences. Although many consider onychomycosis solely as an annoyance, patients with the condition often complain of discomfort and pain associated with trimming the nails, running, and other activities such as dancing. In addition, serious complications such as cellulitis can result from onychomycosis, especially in patients who are diabetic or immunocompromised. Infections with non-dermatophytes such as Fusarium spp. (see below) are of particular concern in the latter group. Tinea unguium refers specifically to dermatophyte infection of the nail unit. It occurs worldwide, affects men more often than women, and is frequently associated with chronic tinea pedis. Trauma and other nail disorders represent predisposing factors. Although all dermatophytes can cause tinea unguium, Microsporum spp. do so very rarely. The most common causative pathogens are T. rubrum, T. interdigitale, T. tonsurans (in children), and E. floccosum. Toenail infections are considerably more common than fingernail infections, and only rarely does fingernail onychomycosis occur without

• • • •

CHAPTER

Type

Causative organism

Clinical features

Treatment considerations

Moccasin

Trichophyton rubrum Epidermophyton floccosum

Diffuse hyperkeratosis, erythema scaling and fissures on one or both plantar surfaces; frequently chronic and difficult to cure*; occasionally associated with immune deficiency

Topical antifungal plus product with urea or lactic acid; may require oral antifungal therapy

Most common type; erythema, scaling, fissures and maceration in the web spaces; the two lateral web spaces are most commonly affected; “dermatophytosis complex” (fungal infection followed by bacterial invasion†) can develop; pruritus common; may extend to dorsum and sole of foot

Topical antifungal; may require topical or oral antibiotic if superimposed bacterial infection

Neoscytalidium hyalinum N. dimidiatum Interdigital

T. interdigitale (previously mentagrophytes var. interdigitale) T. rubrum E. floccosum N. hyalinum N. dimidiatum Candida spp. Fusarium spp.

Inflammatory (vesicular)

T. mentagrophytes (previously T. mentagrophytes var. mentagrophytes)

Vesicles and bullae on the medial foot; often associated with a dermatophytid reaction‡

Topical antifungal usually sufficient

Ulcerative

T. rubrum T. interdigitale (previously T. mentagrophytes var. interdigitale) E. floccosum

Typically an exacerbation of interdigital tinea pedis; ulcers and erosions in the web spaces; commonly secondarily infected with bacteria; seen in immunocompromised and diabetic patients

Topical antifungal; may require topical or oral antibiotics if secondary bacterial infection (common)

Dermatophytes

77 Fungal Diseases

THE FOUR MAJOR TYPES OF “TINEA PEDIS” CAUSED BY DERMATOPHYTES AND NON-DERMATOPHYTES

Non-dermatophytes

*† Because of the thickness of stratum corneum on plantar surfaces and the inability of T. rubrum to elicit a sufficient immune response to eliminate the fungus

21

.

Often Pseudomonas, Proteus spp., or Staphylococcus aureus. ‡Reaction to fungal elements presenting as a dyshidrotic-like eruption on the fingers and palms (culture negative for fungus).

Table 77.11 The four major types of “tinea pedis” caused by dermatophytes and non-dermatophytes.  

Fig. 77.15 Tinea pedis. A Diffuse scaling on both feet (moccasin type) as well as on the right hand, representing “one hand–two feet” tinea.   B Maceration between the third and fourth toes in the interdigital form. C Erythema, scale-crust, and bullae in the inflammatory form. D Extension of tinea pedis onto the dorsal foot in a serpiginous configuration of erythema and papules. Scale is minimal due to the patient’s use of a potent topical corticosteroid for presumed dermatitis.    

B, Courtesy, Jean L Bolognia, MD; D, Courtesy, Julie V Schaffer, MD.

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Fig. 77.16 Extensive tinea corporis emanating from tinea manuum and tinea pedis. Note the confluent involvement, serpiginous scaly borders, and associated tinea unguium of the toenails and one fingernail.

Infections, Infestations, and Bites



concurrent toenail infection. A single nail may be involved, but more frequently, multiple nails on one or both hands or feet are affected. In the distal/lateral subungual type, invasion of the hyponychial region leads to hyperkeratosis of the nail bed. With further progression of infection, there is yellowing and thickening of the distal nail plate as well as onycholysis (Fig. 77.17A–C), which provides an ideal environment for further proximal invasion and growth of the dermatophyte. Eventually, the entire nail bed and plate may become involved (total dystrophic pattern). The clinical appearance of the superficial white type of onychomycosis can vary based on host factors (e.g. immunosuppression) and the causative organism. Discrete white patches are seen in the classic form due to T. interdigitale (see Fig. 77.17D). However, transverse striate bands, origination from the proximal nail fold (which may overlap with the proximal subungual type if there is also invasion under the nail fold), and deeper invasion of the nail plate can also occur. These variants are more likely be caused by T. rubrum, with more invasive forms observed in healthy children as well as individuals with HIV infection; deep invasion of the nail plate can also result from non-dermatophyte molds such as Fusarium spp.22 Although nail dystrophy can be the result of trauma, psoriasis, inherited disorders, and other conditions (see Ch. 71), an estimated 50% or more of cases are due to onychomycosis. Dermatophytes account for ~90% of cases of onychomycosis, and the remainder are due to yeasts or non-dermatophyte molds (Table 77.12). Candida spp. are often found in association with chronic paronychia (see Ch. 71), and infection of the nail may occur in this setting. The fingernails are usually affected, with ridging, yellow discoloration, and onycholysis. Candida spp. are a relatively common cause of onychomycosis in children less than 3 years of age, and nail involvement also represents a manifestation of chronic mucocutaneous candidiasis (see Ch. 60).

Pathology

1342

Tinea pedis, manuum, faciei, cruris, and corporis are usually diagnosed via KOH examination (see Fig. 77.5B) and occasionally with fungal cultures. The chlorazol black E stain can help to highlight fungal elements in KOH preparations. Use of calcofluor, a fluorescent stain specific for the chitin in the fungal cell wall, and examination with a fluorescent microscope can also demonstrate fungi (apple-green fluorescence). If biopsies are performed of cutaneous dermatophyte infections, hyphae are seen within the stratum corneum; the fungi are made more apparent by PAS or silver stains. In dermatophytoses affecting glabrous skin, spongiosis, parakeratosis, and pustules are often seen. In onychomycosis, hyphae and arthroconidia may be visible in the nail plate and nail bed with PAS staining, and little to no inflammation is generally

present2. Histologic examination of formalin-fixed, PAS-stained nail plates is a quick and reliable method for diagnosing onychomycosis (Fig. 77.17E), with a sensitivity of 80 to >95%, compared with 35–60% for culture alone23. Biopsy specimens of tinea capitis, Majocchi granuloma, and tinea barbae can demonstrate hyphae or arthroconidia within hair shafts and are usually done if the diagnosis is suspected but KOH examination and culture are negative. However, false-negative results are a potential problem and tissue should also be sent for culture.

Differential diagnosis

Careful clinical examination is the first and most important step in diagnosing dermatophyte infections. Because many other conditions can mimic dermatophytoses (see Table 77.9), KOH examination and/ or culture are often necessary to confirm the diagnosis. Guidelines for proper specimen collection are outlined in Fig. 77.18. Because all dermatophytes have hyaline hyphae, they essentially look the same in KOH preparations. When identification of the particular species will provide helpful information or culture is needed to confirm the diagnosis, the specimen is cultured at 25–30°C (and in some instances also at 37°C) for 2 to 4 weeks. Colonial morphology, microscopic examination of conidia (the asexual propagules formed de novo by the fungus), noting the growth rate/requirements, and biochemical tests allow precise identification of the dermatophyte. The presence or absence of microconidia (usually small and unicellular) and macroconidia (usually larger and multicellular) and the typical features of each (e.g. shape, cell wall texture) remain fairly consistent among genera (Fig. 77.19). Other distinguishing microscopic features include the identification of arthroconidia (infective fungal elements) and chlamydoconidia. Sometimes, conidia may not be present in culture (“sterile” organism), and the hyphal patterns (spiral, pectinate, antler, racquet, and nodular bodies) may be important in identification of the organism. The color, texture and topography of the colony are features that are typical of, or even unique to, a particular species (see Table 77.6). Dermatophytes are able to grow on media containing cycloheximide (e.g. Mycosel®, DTM [dermatophyte test medium]). However, some clinically relevant non-dermatophyte fungi do not, including Scopulariopsis brevicaulis, Aspergillus spp., Cryptococcus neoformans, Candida tropicalis, Pseudallescheria boydii/Scedosporium apiospermum, and Trichosporon spp.24 These can potentially be missed if specimens, in particular from nails, are grown only on cycloheximide-containing media25.

Treatment

Topical antifungals are the first-line treatment for many patients with uncomplicated, localized cutaneous dermatophyte infections such as tinea corporis, tinea cruris, and tinea pedis (see Ch. 127). The major potential adverse reaction is irritant (or, occasionally, allergic) contact dermatitis, usually from alcohols or other components in the vehicle26. Systemic antifungal therapy, although associated with both a higher incidence of side effects including potentially severe adverse reactions and the potential for drug–drug interactions, is typically required to cure tinea manuum, capitis, and unguium. Suggested regimens are presented in Table 77.1327. In general, oral treatment is also needed for infections involving extensive areas of skin, in hairy sites other than the scalp (e.g. tinea barbae), or associated with excessive inflammatory reactions. The adjunctive use of topical products containing glycolic acid, lactic acid, or urea may help to reduce the amount of hyperkeratosis in infections such as tinea manuum and pedis. Treatment of tinea unguium deserves special consideration. Oral antifungal therapy is usually required to achieve a complete cure (see Table 77.13), with the occasional exception of classic superficial white onychomycosis. Topical therapies that have been FDA-approved for mild to moderate onychomycosis have combined clinical and mycologic cure rates after daily application for 48 weeks ranging from 6–10% for tavaborole 5% and ciclopirox olamine 8% solutions to 15–20% for efinaconazole 10% solution. Although mycologic cure rates of up to 80% (or higher with prolonged therapy) have been reported with oral antifungal drugs (terbinafine, itraconazole, and fluconazole), the combined clinical and mycologic cure rates are lower, i.e. ~20–40% after 12 weeks for toenails. Recurrent disease is common, especially in the toenails and when the degree of involvement is severe (Table 77.14)7,28. Preventive measures include breathable footwear and socks, antifungal or

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Fig. 77.17 Tinea unguium. Onycholysis, yellowing, crumbling and thickening of the fingernails (A), thumb nails (B), and toenails (C) in the distal/lateral subungual variant. D White discoloration of the toenail in the superficial white variant. E Hyphae within a formalin-fixed, PAS-stained nail plate. A, D Courtesy, Jean  

L Bolognia, MD; B, Courtesy, Louis A Fragola, Jr, MD; E, Courtesy, Mary Stone, MD.

(

absorbent powders, frequent nail clipping, and avoiding re-exposure (e.g. not going barefoot in locker rooms). Old shoes often harbor large numbers of infectious organisms and should be discarded or treated with disinfectants or antifungal powders. Combination therapy consisting of a topical corticosteroid plus a topical antifungal has been advocated by some clinicians for the treatment of dermatophyte infections. While a reduction in inflammation can be seen, the negative effects of high-potency corticosteroids on immune defenses coupled with restrictions on treatment duration to avoid side effects such as striae lead to an unacceptable failure rate29. Low-potency corticosteroids are a safer option when anti-inflammatory activity is needed.

Invasive dermatophytosis

Rarely, dermatophytes proliferate within the dermis. Invasion or dissemination of dermatophytes typically occurs in the setting of a chronic dermatophyte infection (most commonly T. rubrum) in an individual with a primary immunodeficiency such as CARD9 deficiency (see Ch. 60) or iatrogenic immunosuppression30. Hematogenous spread can lead to an acute onset of ulcerating or draining dermal and subcutaneous nodules. A more indolent process can also occur and most often presents as tender nodules on the extremities. Currently, the recommended treatment is surgical excision (if localized) and systemic itraconazole or terbinafine31,32, but amphotericin B and griseofulvin have also been used successfully.

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Fig. 77.18 Proper specimen collection. Proper collection of skin, hair, and nails is important. Following these simple guidelines will help the clinician to achieve the most accurate diagnosis.  

PROPER SPECIMEN COLLECTION

Skin specimens • Cleanse skin with alcohol or soap/water and allow to dry • Scrape scale from the advancing border of lesion with no.15 blade or glass slide

Hair specimens • Epilate several broken hairs with tweezers; if Wood's lamp examination is performed, remove any hairs that fluoresce • Scrape scale from affected scalp with a blade • For scalp culture, an option is to swab affected scalp with a cotton tip applicator or culturette

*

Nail specimens • Cleanse affected nail(s) with alcohol or soap/water and allow to dry • Clip nail(s) to the most proximal point possible (without causing discomfort) • Collect any subungual debris by scraping the area under trimmed nail with 1–2 mm serrated curette or no.15 blade

Courtesy, Judy Warner.

• Perform KOH examination of specimens or PAS if nail specimen • Place scale, hairs and/or nails on culture media (Sabouraud dextrose agar with chloramphenicol

and cycloheximide +/– plain Sabouraud dextrose agar, depending on presumed organism) • If sending to fungal reference library place samples in a sterile container

*If culturette is used for transport, do not break the ampule; swab fungal culture media with applicator; KOH/calcofluor are not possible with this method

NON-DERMATOPHYTE MOLDS THAT CAN CAUSE ONYCHOMYCOSIS

Fungus

Key features

Fusarium spp.

Superficial white pattern*

Aspergillus spp.

Superficial white pattern*

Acremonium

Superficial white pattern*

Scopulariopsis brevicaulis

Lateral yellow–brown discoloration KOH of nail reveals lemon-shaped conidia and atypical hyphae

Neoscytalidium hyalinum

Distal and lateral nail invasion†

Neoscytalidium dimidiatum

Distal and lateral nail invasion†

APPEARANCE OF CONIDIA AND HYPHAE AND HAIR PERFORATION TEST Conidia

Macroconidia

Epidermophyton

Table 77.12 Non-dermatophyte molds that can cause onychomycosis.  

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Microsporum

Intercalary

May also be associated with paronychia or tinea pedis.

Mucocutaneous candidiasis has a wide spectrum of clinical presentations. Early descriptions of oral candidiasis (thrush) were made by Hippocrates. In the 1940s, the association between oral antibiotic use and candidal infections was recognized. Oral candidiasis often presents as thrush, with the pseudomembranous form characterized by a white exudate resembling cottage cheese (Fig. 77.20A,B) and the chronic atrophic form by a patch of erythema; it can also lead to a chronic hyperplastic form with adherent white plaques or glossitis with painful atrophy of the dorsal tongue. Other presentations include denture stomatitis, angular cheilitis (perlèche) (Fig. 77.20C), vulvovaginitis, and balanitis (see Ch. 73). Predisposing factors for mucocutaneous candidiasis include diabetes mellitus, xerostomia, occlusion, hyperhidrosis, the use of corticosteroids or broad-spectrum antibiotics, and immunosuppression, including HIV infection33. In the case of angular cheilitis, deep grooves due to overlap of the skin at the angles of the mouth, which is common in edentulous and older patients, is a key contributing factor, along with the use of orthodontic appliances, drooling, atopic dermatitis, and (occasionally) iron or vitamin deficiencies (e.g. B2). Cutaneous Candida infections present with markedly erythematous, sometimes erosive, patches that are often accompanied by satellite papules and pustules (Fig. 77.20D–F). The most common sites of involvement are intertriginous zones (e.g. submammary, beneath

Trichophyton

Chlamydoconidia Terminal

*† Deeper invasion of the nail plate can also occur.

Mucocutaneous candida infections

Microconidia (Microsporum and Trichophyton only)

Arthroconidia Hyphae

Spiral Pectinate Antler (T. mentagrophytes, (M. audouinii) (T. schoenleinii and T. interdigitale) T. concentricum) In vitro hair perforation test

Positive (T. mentagrophytes, T. interdigitale)

Hair shaft

Fig. 77.19 Microscopic appearance of various forms of conidia and hyphae and the in vitro hair perforation test.  

pannus, inguinal creases, intergluteal fold) and the scrotum, as well as the diaper area in infants. Candidiasis is sometimes superimposed on intertriginous seborrheic dermatitis or psoriasis. Candida can also infect periungual areas (e.g. in the setting of chronic paronychia), nails (see Tinea unguium above), and the web space between the third and fourth fingers (erosio interdigitalis blastomycetica; Fig. 77.20G), especially in individuals whose hands are frequently exposed to water.

CHAPTER

Fluconazole

Griseofulvin

Itraconazole*

Terbinafine

Tinea pedis (moccasin type)/ tinea manuum (adults)

150–450 mg/week × 4–6 weeks27

750–1000 mg/day (microsize) or 500–750 mg/ day (ultramicrosize) × 4 weeks

200–400 mg/day × 1 week

250 mg/day × 2 weeks

Tinea pedis (moccasin type)/ tinea manuum (children)

6 mg/kg/week × 4–6 weeks

15–20 mg/kg/day (microsize suspension) × 4 weeks

3–5 mg/kg/day (maximum 400 mg) × 1 week

Daily dosing as for tinea capitis (see below) × 2 weeks

200 mg/day × 12 weeks or 200 mg BID × 1 week/month for 3–4 consecutive months

250 mg/day × 12 weeks

Tinea unguium (adults)

Fungal Diseases

77

SUGGESTED SYSTEMIC REGIMENS FOR DERMATOPHYTOSES

Toenail ± fingernail involvement: 150–450 mg/week until nails are clear27

1–2 g/day (microsize) or 750 mg/day (ultramicrosize) until nails are normal†

Fingernail involvement only: 150–450 mg/week until nails are clear27

1–2 g/day (microsize) or 750 mg/day (ultramicrosize) until nails are normal†

200 mg/day × 6 weeks or 200 mg BID × 1 week/month for 2 consecutive months

250 mg/day × 6 weeks

Tinea unguium (children)

6 mg/kg/week × 3–4 months (fingernails) or 5–7 months (toenails), or until nails are clear

20 mg/kg/day (microsize suspension) until nails are normal†

5 mg/kg/day (50 kg) × 1 week/month for 2 (fingernails) or 3 (toenails) consecutive months

62.5 mg/day (40 kg) × 6 weeks (fingernails) or 12 weeks (toenails)

Tinea corporis (extensive, adults)

150–200 mg/week × 2–4 weeks

500–1000 mg/day (microsize) or 375–500 mg/ day (ultramicrosize) × 2–4 weeks

200 mg/day × 1 week

250 mg/day × 1 week

Tinea corporis (extensive, children)

6 mg/kg/week × 2–4 weeks

15–20 mg/kg/day (microsize suspension) × 2–4 weeks

3–5 mg/kg/day (maximum 200 mg) × 1 week

Daily dosing as for tinea capitis (see below) × 1 week

Tinea capitis (adults)‡

6 mg/kg/day × 3–6 weeks

10–15 mg/kg/day (ultramicrosize; usually maximum 750 mg/day) × 6–8 weeks

5 mg/kg/day (maximum 400 mg) × 4–8 weeks

250 mg/day × 3–4 weeks§

Tinea capitis (children)‡

6 mg/kg/day × 3–6 weeks

20–25 mg/kg/day (microsize suspension) × 6–8 weeks

5 mg/kg/day (maximum 500 mg) × 4–8 weeks

Granules: 125 mg (35 kg) × 3–4 weeks§

*† Not approved in US for use in children.

No longer commonly used for this indication.

‡Combined with 2.5% selenium sulfide shampoo or ketoconazole 2% shampoo; “id” reaction should not be confused with a medication allergy. §Not recommended for Microsporum canis, unless given at double-dose.

Table 77.13 Suggested systemic regimens for dermatophytoses. BID, twice daily.  

INDICATORS OF MORE SEVERE ONYCHOMYCOSIS WITH A POOR RESPONSE TO TREATMENT Nail factors

Subungual hyperkeratosis >2 mm thick* Significant lateral involvement • Dermatophytoma† • >50% involvement of nail bed • Slow nail growth rate • Total dystrophic onychomycosis • Matrix involvement • •

Patient factors

Immunosuppression Peripheral arterial disease • Poorly controlled diabetes mellitus • •

*† Measurement of nail plate plus nail bed.

Streak or patch representing a subungual pocket of densely packed hyphae; removal prior to initiating antifungal therapy can be helpful.

Table 77.14 Indicators of more severe onychomycosis with a poor response to treatment. Adapted from ref 28.  

Mucocutaneous candidiasis is most commonly due to C. albicans, followed by C. tropicalis. The diagnosis is established by the presence of budding yeast and pseudohyphae on KOH examination (see Fig. 77.5D) and by a positive fungal culture. C. albicans and C. stellatoidea can be distinguished by their ability to form chlamydoconidia on cornmeal-Tween 80 agar. Identifying and removing predisposing factors is very important in the management of mucocutaneous candidiasis. Treatment with topical nystatin or azole antifungals is often effective34,35. When oral therapy is required for more extensive involvement, options include fluconazole and itraconazole (see Ch. 127). Treatment regimens for various forms of mucocutaneous candidiasis are outlined in Table 77.15.

Chronic mucocutaneous candidiasis

This is discussed in detail in Chapter 60. Chronic mucocutaneous candidiasis is not a single entity but rather a clinical manifestation of a number of disorders, including primary immunodeficiencies. Patients have defects in the T helper 17 (Th17) response that prevent effective handling of Candida organisms, leading to chronic, recalcitrant infections of the skin (including granulomatous lesions), nails, and mucosae. Some patients have associated autoimmune endocrinopathies as well as alopecia areata and vitiligo. Therapy involves oral fluconazole and itraconazole (see Table 77.15).

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Fig. 77.20 Mucocutaneous candidiasis. A Thrush with “cottage cheese”-like exudate on the buccal mucosa. B Thrush and candidal cheilitis. C Angular cheilitis (perlèche). D Candidiasis of the suprapubic area and penis in a young boy. Note the collarettes of scale on the coalescing, brightly erythematous papules. E Candidiasis of the scrotum and medial thighs with beefy red erythema, scale, and satellite papules. F This infection occurred in a hospitalized patient with diabetes mellitus who was receiving broad-spectrum antibiotics. Note the multiple satellite lesions. G Erosive interdigital candidiasis (erosio interdigitalis blastomycetica) in the classic location between the third and fourth fingers. H Dermal candidiasis in an immunosuppressed patient. A, Courtesy, Judit Stenn, MD; B, D Courtesy, Louis A Fragola, Jr, MD;  

C, Courtesy, Kalman Watsky, MD; E, G, Courtesy, Eugene Mirrer, MD.

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Granuloma gluteale infantum/adultorum and perianal pseudoverrucous papules/nodules

SUBCUTANEOUS MYCOSES

Granuloma gluteale infantum/adultorum is a reactive condition that occurs in the setting of chronic, severe irritant contact dermatitis in the anogenital region of either infants with chronic diarrhea or children and adults with encopresis or urinary incontinence36. It exists on a spectrum with perianal pseudoverrucous papules/nodules, and the term Jacquet erosive dermatitis has been used for a variant with prominent punched-out erosions37. Erythematous to violaceous nodules and plaques, often ovoid in shape and sometimes eroded, develop on the vulva, lower buttocks, perianal region, and occasionally scrotum (Fig. 77.21). Similar to Candida infections, satellite pustules may also be seen. In addition to chronic irritation (e.g. from frequent loose stools), predisposing factors may include occlusion, topical corticosteroid use, and candidal infection. Histologically, epidermal hyperplasia, a variably dense mixed inflammatory infiltrate in the dermis, and vascular proliferation are typically observed. Although barrier creams and topical antifungal agents may have some benefit, the condition tends to persist until the irritant trigger is eliminated.

The “subcutaneous” mycoses are due to a large and diverse group of organisms that cause disease when implanted or otherwise introduced into the dermis or subcutis. Chromoblastomycosis, mycetoma, sporotrichosis, and lobomycosis are discussed in detail in this section. Another chronic subcutaneous fungal infection is basidiobolomycosis, which is caused by Basidiobolus ranarum. Although this organism is an environmental saprophyte that is found worldwide, the associated infection occurs most commonly in children living in tropical and subtropical climates. The most common portal of entry is the skin, typically after arthropod bites or minor trauma. Clinically, the disease manifests as a solitary, painless, indurated subcutaneous nodule or swelling of the thigh or buttock. The classic treatment is saturated solution of potassium iodide (SSKI; see Ch. 100), although successful results have been reported with oral azole antifungals and trimethoprim–sulfamethoxazole. Surgical excision is not recommended. A related organism, Conidiobolus coronatus, causes an infection that

CHAPTER

Type of infection

Treatment regimen (adult doses unless otherwise indicated)

Oropharyngeal candidiasis



Nystatin* 100 000 units/ml suspension: Children and adults – 4–6 ml swish and swallow four times daily • Infants – 2 ml (1 ml inside each cheek) four times daily Clotrimazole* 10 mg troche five times daily Fluconazole† 200 mg po on day 1, then 100–200 mg po daily Continue treatment for 7–14 days after clinical resolution

Esophageal candidiasis

Fluconazole* 200–400 mg po on day 1, then 100–400 mg daily Itraconazole 200 mg po daily Voriconazole 200 mg po or iv BID Posaconazole 400 mg po BID Caspofungin 50 mg po iv daily Continue treatment for 7–14 days following resolution of symptoms, for a minimum of 21 days total

Candidal vulvovaginitis§

Fluconazole* 150 mg po single dose or (for severe disease or an immunosuppressed patient) three doses at 3-day intervals Butoconazole 2% vaginal cream, 5 g daily for 1–3 days Clotrimazole*,‡ • 1% vaginal cream (or other topical formulation), 5 g daily for 7–14 days • Vaginal suppositories: 100 mg daily for 7 days or 200 mg daily for 3 days Miconazole*,‡ • 2% cream, 5 g daily for 7 days • Vaginal suppositories: 100 mg daily for 7 days, 200 mg daily for 3 days, or 1200 mg single dose Tioconazole* 6.5% cream, 5 g single dose Terconazole* • 0.4% or 0.8% cream, 5 g daily for 7 or 3 days, respectively • 80 mg vaginal suppository daily for 3 days Nystatin 100 000 units vaginal suppository daily for 14 days For suppression in patients with recurrent infections: Fluconazole 150 mg weekly for 6 months Clotrimazole vaginal suppository, 200 mg twice weekly or 500 mg weekly for 6 months

Chronic mucocutaneous candidiasis Candidal intertrigo or balanitis§

77 Fungal Diseases

TREATMENT OF MUCOCUTANEOUS CANDIDA INFECTIONS

Fluconazole Eradication: 400–800 mg po daily for 4–6 months • Suppressive therapy: 200 mg po daily •

Topical imidazole (see Table 127.12) or ciclopirox cream or lotion twice daily for 1–2 weeks or until resolved¶ Systemic agents for recalcitrant or severe cases: Fluconazole • 50 to 100 mg po daily for 14 days • 150 mg po weekly for 2–4 weeks Itraconazole 200 mg po twice daily for 14 days

*† Recommended as first-line treatment for immunocompetent individuals.

Recommended as first-line treatment for HIV-infected patients (or other immunosuppressed individuals) with moderate to severe disease, recurrent infection, or a CD4 count of 100-fold due to transmission by infected cats, which (in contrast to humans) harbor large numbers of organisms in cutaneous ulcers46.

Pathogenesis

%

Fig. 77.23 Mycetoma (Madura foot). A Note the soft tissue swelling of the foot as well as multiple nodules with pustular discharge. B Histology of a grain, which represents tightly packed colonies of fungal organisms. B, Courtesy, Lorenzo  

Cerroni, MD.

Sporotrichosis is most commonly acquired from cutaneous inoculation, especially by vegetation such as thorns and wood. With the exception of cats in Brazil, animal-to-human transmission is rare. Multiple inoculations may occur simultaneously, not to be confused with spread of a single primary lesion. The presentation and course

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COLORS OF GRAINS AND GEOGRAPHIC DISTRIBUTION OF EUMYCOTIC AND ACTINOMYCOTIC MYCETOMAS

Pathogen Eumycotic

Actinomycotic

Grain color

Geographic distribution

Madurella mycetomatis

Black

North, Central and South America; Caribbean, Africa, Europe, Middle East, Asia

Madurella grisea

Black

North, Central and South America; Africa, Asia

Leptosphaeria senegalensis

Black

Africa, Asia

Pseudallescheria boydii/Scedosporium apiospermum* (sexual/asexual states, respectively)

White

North, Central and South America; Africa, Oceania, Asia, Europe

Acremonium and Sarocladium spp.

White

North, Central and South America; Asia, Europe, Oceania

Nocardia brasiliensis†

White

Worldwide (all Nocardia spp.)

Nocardia asteroides‡

White

Nocardia caviae

Yellow–white

Actinomyces israelii§

Yellow–white

Worldwide

Actinomadura madurae

Pink or white

Worldwide

Actinomadura pelletieri

Red

North and South America, Africa, India

Streptomyces somaliensis

Brown or yellow

Africa (arid regions)

*† Most common cause in the US. Most common cause in Mexico. ‡Rare. §Very rare cause of mycetoma; usually causes actinomycosis (e.g. cervicofacial, thoracic and abdominal), which also has draining sinuses and grains. Table 77.16 Colors of grains and geographic distribution of eumycotic and actinomycotic mycetomas. Grains can also be seen in botryomycosis and actinomycosis (see Ch. 74).  

of sporotrichosis depends on the host immune response as well as the size and virulence of the inoculum. In naive hosts, involvement of regional lymphatics ensues. However, in those with a prior history of exposure to Sporothrix, lymphatic spread does not occur and a “fixed” ulcer47 or granulomatous plaque develops at the site of inoculation; the latter is often seen on the face, especially in children living in endemic areas. Extensive cutaneous disease with or without systemic involvement is also possible, especially in an immunocompromised host. Cases of inhaled sporotrichosis have been reported with systemic and cutaneous dissemination, similar to disseminated histoplasmosis and other dimorphic fungal infections.

whether a hyphal or yeast form develops depends on the temperature. Growth is rapid at 25°C, revealing a glabrous white to brown mold that becomes firm, wrinkled, and more darkly pigmented over time. Microscopically, delicate conidia are clustered at the ends of conidiophores (specialized hyphae); single, thick-walled pigmented conidia can also arise from hyphae. At 37°C, on enriched glucose-containing media, there are slow-growing, whitish, pasty, yeast-like colonies. On microscopic examination of the latter, cigar-shaped budding yeasts are seen. Full speciation depends on molecular studies45. The differential diagnosis of fixed plaque sporotrichosis and disseminated lesions is broad and includes other granulomatous disorders, both infectious and inflammatory.

Clinical features

Treatment

The initial presentation of sporotrichosis is a single papule at a site of injury, most commonly on the hand, appearing several weeks after inoculation. The lesion then becomes eroded or ulcerated with purulent drainage, but it is generally not painful. Additional lesions appear weeks later, typically developing as dermal and subcutaneous nodules and ulcers along the path of lymphatic drainage (often up the arm; Fig. 77.24). This is the well-known “sporotrichoid” pattern. The involved lymphatic vessels may become fibrosed48. Lesions of “fixed” cutaneous sporotrichosis can have a granulomatous appearance, often with ulceration, while disseminated lesions typically present as subcutaneous nodules.

Pathology

Histologically, suppurative and granulomatous inflammation is found in the dermis and subcutis. The causative organisms are rarely evident; staining with fluorescent-labeled antibodies may aid in recognition of the sparse cigar-shaped yeast forms. Asteroid bodies are often seen. When numerous fungi are present (e.g. in an immunocompromised host), budding yeast and cigar-shaped organisms can often be visualized with PAS (Fig. 77.24B) or silver stains.

Differential diagnosis

1350

When there is a sporotrichoid pattern, the major entity to be excluded is an atypical mycobacterial infection, in particular with M. marinum; less common causes are outlined in Table 77.17. As organisms are not typically seen by KOH or histopathologic examination, culture (of pus or tissue) is often required to definitively diagnose sporotrichosis; a nested PCR assay can also be used to detect organisms in clinical samples49. Sporothrix spp. are dimorphic fungi (see below), and

Topical therapy is not effective. Oral saturated solution of potassium iodide (SSKI) has been used with success. Although neither fungistatic nor fungicidal, SSKI is thought to affect the host’s immune reaction to the organism. Its cost is low, but it has a bitter taste as well as potential side effects including iododerma, gastrointestinal upset, and thyroid suppression (see Ch. 100). Based upon multicenter, non-randomized trials and case series, the Mycoses Study Group of the Infectious Diseases Society of America has recommended itraconazole (100–200 mg/ day) for 3–6 months as the treatment of choice for lymphocutaneous or fixed cutaneous sporotrichosis50. The drug is generally safe and well tolerated, and the relapse rate is low. Amphotericin B may be indicated in severe or disseminated disease.

Lobomycosis Synonyms:  ■ Keloidal blastomycosis ■ Lacaziosis ■ Lobo’s disease Lobomycosis is a chronic fungal infection characterized by cutaneous nodules that resemble keloids. The causative organism, Lacazia loboi (previously known as Loboa loboi)51, is closely related to Paracoccidioides brasiliensis and has never been cultured in vitro52. Lobomycosis occurs in Central and South America and has been linked to contact with dolphins and a marine environment as well as soil and vegetation in rural areas. Infection typically occurs after minor trauma and most often affects men53. Lobomycosis presents as asymptomatic, firm, keloid-like nodules that favor the distal extremities, ears (especially the helices), and face



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77 Fungal Diseases

Fig. 77.24 Lymphocutaneous (sporotrichoid) pattern. A An eroded nodule on the thumb representing the primary lesion with a secondary lesion along the lymphatics due to sporotrichosis.   B Multiple yeast forms of Sporothrix schenckii in the dermis; note that many of the organisms have the characteristic cigar shape. C Ulcerated nodule on the extensor forearm with multiple more proximal nodules due to nocardiosis in a patient with lymphoma who was receiving systemic corticosteroids. B, Courtesy, Ronald P Rapini, MD; C, Courtesy, Jean L Bolognia, MD.

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INFECTIOUS CAUSES OF A LYMPHOCUTANEOUS (“SPOROTRICHOID”) PATTERN

Most common Atypical mycobacteria, especially M. marinum, but also other species (e.g. M. chelonae, M. kansasii) Sporotrichosis (Fig. 77.24A)

bridges (Fig. 77.25C); PAS or silver stains highlight these organisms, which can also be identified in scrapings from the surface of skin lesions54. Additional findings include a dermal granulomatous infiltrate and either atrophy or pseudoepitheliomatous hyperplasia of the epidermis. Treatment with surgical excision or cryosurgery is employed if feasible, since antifungal medications are typically ineffective. However, clofazamine and itraconzole may be of some benefit for patients with widespread disease55.

Unusual Nocardiosis (Fig. 77.24C) Pyogenic bacteria (e.g. Staphylococcus aureus, Streptococcus pyogenes) Pseudallescheria boydii/Scedosporium apiospermum

Rare (in high-income countries) Leishmaniasis Tularemia* Tuberculosis* Dimorphic fungi (other than Sporothrix spp.) Opportunistic fungi in immunocompromised hosts (e.g. Fusarium, Alternaria spp.) Glanders (Burkholderia mallei)* Cat scratch disease* Anthrax Cowpox Acanthamoeba spp.

*Often ulceroglandular. Table 77.17 Infectious causes of a lymphocutaneous (“sporotrichoid”) pattern. There are also non-infectious causes such as lymphoma, Langerhans cell histiocytosis, and in-transit metastases. In addition, perineural spread of leprosy can mimic a lymphocutaneous pattern.  

but can also affect the trunk (Fig. 77.25A,B). The lesions enlarge slowly over years, forming broad, multinodular plaques that may have a smooth surface or (occasionally) a verrucous appearance and ulceration. Histologic evaluation shows highly characteristic chains of thickwalled, yeast-like cells (known as “brass knuckles”) with intercellular

SYSTEMIC MYCOSES This section reviews systemic infections caused by opportunistic as well as true fungal pathogens. The true pathogens are generally dimorphic and cause infection in hosts with normal immune status, while opportunistic pathogens, which are generally less virulent, take advantage of the immunocompromised state.

True Pathogens Introduction The systemic mycoses due to true pathogens include histoplasmosis, blastomycosis, coccidioidomycosis, and paracoccidioidomycosis. They are caused by dimorphic fungi, meaning the organisms can exist in two forms – as molds (with septate hyphae and conidia) in nature and as other forms (usually yeasts) in living tissue and (with the exception of Coccidioides spp.) at 37°C. Each pathogen has certain geographic preferences (Fig. 77.26; see below). Acquisition of disease is typically through inhalation of the causative fungi, leading to pulmonary symptoms and pneumonitis. The vast majority of infections resolve spontaneously, and patients are left with strong, specific immunity. Disseminated histoplasmosis and coccidioidomycosis may occur in HIV-infected persons, as can disseminated infections with S. schenckii (dimorphic) and Talaromyces (Penicillium) marneffei (dimorphic and opportunistic)56. Emergomyces spp. are dimorphic fungal pathogens recently described in South Africa (E. africanus; formerly Emmonsia pasteuriana) and China (E. orientalis); disseminated infection in

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Fig. 77.25 Lobomycosis. A, B Multinodular pinkish-brown plaques with a keloid-like appearance on the helix and back. C Spherical organisms with doubly refractile walls are seen within the dermis. Chain formation is commonly observed (inset; methenamine silver stain). A, B, Courtesy, Regina

Infections, Infestations, and Bites



Carneiro, MD and Caroline Brandao, MD; C, Courtesy, C Massone, MD.

Introduction

Histoplasmosis is caused by the dimorphic fungus Histoplasma capsulatum var. capsulatum57.

Epidemiology

H. capsulatum is found in the soil in warm, moist climates, particularly the Mississippi, Ohio, and St Lawrence river valleys in the US and Canada. Between 80% and 90% of persons from endemic areas may exhibit positive histoplasmin skin testing58. Birds, fowl, and bats are significant reservoirs for histoplasmosis. Because the feces of these animals contain the organisms, the areas in which they live can harbor infectious fungal spores. Caves, schoolyards, construction sites, unoccupied buildings, and chicken coops tend to be high-risk areas. H. capsulatum var. capsulatum is also endemic along river basins in some areas of Africa, India, Southeast Asia, and Australia.

Pathogenesis

Histoplasmosis is caused either by inhalation of H. capsulatum or, rarely, by direct cutaneous inoculation of the fungus. Immunocompetent hosts can acquire the disease, but immunocompromised hosts have a higher risk of dissemination. Clinical presentations include acute and chronic pulmonary histoplasmosis, disseminated histoplasmosis, and primary cutaneous histoplasmosis. In disseminated histoplasmosis, the most common sites of involvement (after the lung) are the spleen, lymph nodes, bone marrow, and liver; calcifications within the lymph nodes, lungs, and spleen can serve as evidence of prior infection. Cutaneous manifestations most commonly result from disseminated disease. Severe disseminated histoplasmosis has been reported in individuals with impaired interferon-γ responses due to mutations in IFNGR1 or STAT1, which encode interferon-γ receptor 1 and signal transducer and activator of transcription 1, respectively (see Ch. 60).

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Clinical features

The skin lesions of histoplasmosis are nonspecific, making the diagnosis virtually impossible with physical examination alone. When chronic disseminated histoplasmosis occurs in immunocompetent hosts, the most common mucocutaneous finding is oral ulcers but occasionally nodules and vegetative plaques are also seen. Disseminated histoplasmosis in immunocompromised hosts (including those with HIV infection) can present with mucocutaneous erosions or ulcers as well as multiple erythematous papules or nodules with scale or crust (Fig. 77.27A,B). In African histoplasmosis, a variant caused by H. capsulatum var. duboisii, most patients present with mucocutaneous, subcutaneous, and bone lesions.

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Pathology

Microscopic examination of biopsy specimens demonstrates characteristic intracellular yeast forms surrounded by a rim of clearing (Fig. 77.27C). Histiocytes and giant cells are the host cells in histoplasmosis, which is in the differential diagnosis of “parasitized macrophages” (Table 77.18). For easier identification of the fungi, tissue may be stained with PAS or methenamine silver (Fig. 77.27D).

Differential diagnosis

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immunocompromised patients (e.g. those with HIV infection) can present with multiple crusted papules/nodules or ulcers, with parasitized macrophages similar to histoplasmosis and penicilliosis evident histologically56a (see Table 77.18).

Histoplasmosis Synonyms:  ■ Darling’s disease ■ Cave disease ■ Ohio valley disease 1352



Reticuloendotheliosis

Because cutaneous histoplasmosis has a wide spectrum of clinical presentations, the diagnosis usually rests on histologic examination and culture of involved skin tissue. To evaluate for disseminated disease, bone marrow (sensitivity 70–90%) and blood should be cultured at 25°C and 37°C, with plates held for up to a month. At 25°C, characteristic tuberculate macroconidia develop. Additional diagnostic tests include cultures of sputum and body fluids, polysaccharide antigen testing of blood and urine (useful in detecting disseminated disease), histoplasmin skin testing (indicated only in non-endemic areas), and serologic assays to measure antibody responses (complement fixation, immunodiffusion). Highly sensitive and specific PCR-based assays can be used to identify histoplasmosis in blood and tissue59,60. Diseases in the differential diagnosis include other dimorphic fungal infections (e.g. paracoccidioidomycosis), mucocutaneous tuberculosis, major aphthae, and oral squamous cell carcinoma. For primary cutaneous histoplasmosis, entities in Table 77.17 should be considered.

Treatment

In primary, self-limited, asymptomatic histoplasmosis, treatment may not be necessary. However, in symptomatic or disseminated disease,



MAJOR GEOGRAPHIC DISTRIBUTION OF DIMORPHIC FUNGI

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77 Fungal Diseases

Fig. 77.26 Major geographic distribution of dimorphic fungi. Histoplasma capsulatum var. capsulatum is also endemic along river basins in some areas of India, Southeast Asia, and Australia. Courtesy, Braden A Perry, MD.

Blastomycosis dermatiditis Blastomycosis dermatiditis + Histoplasma capsulatum var. capsulatum Coccidioides immitis Coccidioides immitis + Histoplasma capsulatum var. capsulatum C. immitis, B. dermatiditis, H. capsulatum var. capsulatum Histoplasma capsulatum var. capsulatum Coccidioides immitis + Histoplasma capsulatum var. capsulatum + Paracoccidioides brasiliensis Paracoccidioides brasiliensis Penicillium marneffei Histoplasma capsulatum var. duboisii & var. capsulatum

DIFFERENTIAL DIAGNOSIS OF PARASITIZED MACROPHAGES

Disease

Organism

Key features

Rhinoscleroma

Klebsiella rhinoscleromatis

Russell bodies (dilated endoplasmic reticulum cisternae containing aggregated immunoglobulins; form within plasma cells); Mikulicz cell (large histiocyte containing organisms)

Granuloma inguinale

Calymmatobacterium granulomatis

“Donovanosis”; Donovan bodies (vacuoles containing bacilli within macrophages)

Histoplasmosis

Histoplasma capsulatum

Yeast within cytoplasm of macrophages; surrounded by clear halo

Leishmaniasis

Leishmania spp.

Non-encapsulated organism; contains nucleus and paranucleus (kinetoplast)

Penicilliosis

Talaromyces (Penicillium) marneffei

Small yeast within macrophages; resembles histoplasmosis

Emmonsiosis

Emergomyces spp. (formerly Emmonsia pasteuriana)

Small yeast within macrophages

Table 77.18 Differential diagnosis of parasitized macrophages. Adapted from ref 2.  

systemic antifungal therapy is required. Amphotericin B, given intravenously and titrated up to 1 mg/kg/day, is currently the most effective therapy and should be used initially for severe disease, followed by itraconazole. In immunocompetent hosts with mild to moderate, stable disease, itraconazole (200–400 mg/day) is the treatment of choice61. HIV-infected patients with disseminated histoplasmosis require lifelong maintenance therapy with itraconazole after initial treatment with amphotericin B (if required for severe disease). Successful treatment

with voriconazole and posaconazole have also been described62, but ketoconazole is no longer routinely used.

Blastomycosis Synonyms:  ■ North American blastomycosis ■ Gilchrist’s disease

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Fig. 77.27 Histoplasmosis. A, B Disseminated papules and nodules with scale-crust in a patient with AIDS. C Numerous yeasts within giant cells as well as dermal macrophages. D The organisms are highlighted with a methenamine silver stain (inset). C, Courtesy, Jennifer McNiff, MD; D, Courtesy, C Massone, MD.  

Introduction

Blastomyces dermatitidis is a dimorphic fungus and the causative agent of blastomycosis.

Epidemiology

This disease is endemic to North America, particularly the Mississippi and Ohio river valleys, Great Lakes region, and southeastern states. While all ages and genders can be affected, adult men are most likely to develop systemic infection, and children are more likely to develop acute pulmonary blastomycosis rather than chronic or cutaneous disease. The soil is an important source of infection, making those who have occupations with frequent outdoor exposure at higher risk than the remainder of the population. Blastomycosis also rarely occurs in other regions of the world, including Africa and India.

Pathogenesis

The lungs are typically the first site of infection, via inhalation of organisms. In contrast to infections with other dimorphic fungi, secondary cutaneous dissemination is a common occurrence and may even be the first sign of disease. Cutaneous manifestations are sometimes seen in the absence of overt pulmonary disease. Primary cutaneous blastomycosis is uncommon and results from direct inoculation of the skin from trauma, such as in the laboratory.

Clinical features

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The most common cutaneous findings are papulopustules and welldemarcated verrucous plaques with scale-crust and pustules within their borders (Fig. 77.28A,B). Central ulceration can occur, and more advanced disease may have an appearance similar to pyoderma gangrenosum. The number of lesions can vary from one to several, and they tend to occur on exposed skin. Healing begins centrally and is followed by cribriform scarring. Mucous membrane involvement is occasionally observed.

Pulmonary infection is subclinical in up to 50% of patients with inhalation blastomycosis. Bone involvement may occur and presents as osteomyelitis with rare extension to muscle; genitourinary disease is uncommon.

Pathology

Histologic examination of skin lesions demonstrates pseudoepitheliomatous hyperplasia, suppurative and granulomatous inflammation, and round yeast forms with characteristic broad-based budding and thick, double-contoured walls. This budding pattern helps to differentiate blastomycosis from other fungal infections. Methenamine silver and PAS staining allow better visualization of the fungi within giant cells and neutrophilic abscesses (Fig. 77.28C). Similar budding yeast forms can be seen in sputum samples.

Differential diagnosis

Cutaneous blastomycosis must be differentiated from other cutaneous infections (e.g. verrucae, folliculitis, nocardiosis, tuberculosis, chromoblastomycosis, those due to other dimorphic fungi), inflammatory dermatoses (e.g. pyoderma gangrenosum, halogenoderma, sarcoidosis) and neoplasms (e.g. squamous cell carcinoma). Lesions of blastomycosis-like pyoderma, an exaggerated vegetative response to a prolonged primary or secondary bacterial infection, can also resemble cutaneous blastomycosis. Current or past residence in an area in which blastomycosis is endemic is a helpful clue. Identification of characteristic broad-based budding yeast forms in pus by KOH or calcofluor examination is diagnostic of blastomycosis. Either skin tissue or pus should be cultured at both 37°C and 25°C. The former temperature allows identification of the budding yeast form, while the characteristic colonial morphology with white spikes (coremia) is observed at 25°C. Other tests such as blastomycin skin

is no longer routinely used. Occasionally, surgical treatment is indicated.

A, Courtesy, Louis A Fragola, Jr, MD; B, Courtesy, Paul Lucky, MD; C, Courtesy, Mary Stone, MD.

Epidemiology



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Coccidioidomycosis Synonyms:  ■ Valley fever ■ Desert rheumatism ■ San Joaquin valley fever ■ California disease

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77 Fungal Diseases

Fig. 77.28 Blastomycosis. A Facial plaque with scale-crust and a border with a granulomatous appearance. B Welldemarcated plaques with erosions, central scarring, and black crusting. C Budding yeast forms in the dermis, several of which are within a giant cell (PAS stain). Note the single, broad-based budding (arrow).  

Introduction

Coccidioidomycosis is caused by two dimorphic and highly virulent pathogens that are closely related, Coccidioides immitis and C. posadasii66. Coccidioidomycosis occurs predominantly in the summer and fall in the southwestern US, northern Mexico, and Central and South America; C. immitis is found primarily in California and C. posadasii elsewhere within these regions. The arthroconidia of Coccidioides spp. are inhaled via dust particles. Primary infection of the respiratory tract shows no gender or age preference, but disseminated disease is more common in Mexicans (5×), African-Americans (25×) and Filipinos (175×). Immunosuppressed states (e.g. HIV infection) and pregnancy also predispose to dissemination; Caucasian women are most likely to have more limited disease.

Pathogenesis

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C. immitis and C. posadasii are thought to be the most virulent of all fungi66. Infectious arthroconidia are inhaled and cause pulmonary infection in the vast majority of people living in endemic areas. The infection is asymptomatic in ~60% of affected individuals, while the remainder develop flu-like symptoms several weeks after exposure67. Dissemination to the skin and other organs can occur and depends on host factors (see above). Of note, similar to histoplasmosis, severe disseminated disease has been associated with an impaired interferon-γ response due to mutations in IFNGR1 or STAT1. Rarely, primary cutaneous coccidioidomycosis results from direct inoculation of the organism into the skin.

Clinical features

Symptomatic primary inhalation coccidioidomycosis typically presents as a flu-like syndrome with fatigue, anorexia, fever, cough, and pleuritic chest pain. The cutaneous manifestations can occur alone or in combination with the above symptoms and are grouped into four patterns: papules, pustules, plaques, abscesses, and sinus tracts favoring the face (Fig. 77.29A,B) ulcerations toxic erythema presenting as a diffuse macular eruption early in the disease course and sometimes mimicking contact dermatitis hypersensitivity reactions such as erythema multiforme and erythema nodosum. In HIV-infected patients, the papules may resemble molluscum contagiosum. Bone and meningeal involvement can also occur, presenting as osteomyelitis and meningitis, respectively.

• • • •

Pathology &

testing and complement fixation testing are not usually helpful, but PCR-based assays are available63.

Treatment

Blastomycosis, like histoplasmosis, requires systemic treatment with amphotericin B (given at the same doses) when severe or progressive. In mild to moderate non-CNS disease, itraconazole (200–400 mg/day) is the treatment of choice64. Fluconazole (400–800 mg/day), voriconazole, and posaconazole are alternative medications62,65; ketoconazole

Biopsy specimens of specific lesions (types 1 and 2 above) reveal characteristic endospore-containing spherules that measure 30–60 microns when mature (Fig. 77.29C). PAS and methenamine silver stains are helpful in identifying immature spherules. A suppurative granulomatous reaction with histiocytes, lymphocytes, and giant cells typically surrounds the spherules and released endospores.

Differential diagnosis

Coccidioidomycosis can be diagnosed via direct examination (with KOH or calcofluor) and culture of infected tissue, pus, or body fluids. Histologically, larger sporangia (up to 300 microns in diameter) containing numerous endospores can also be seen in mucosal polyps due to Rhinosporidium seeberi. When cultured at 25°C or 37°C, Coccidioides spp. proliferate quickly (within days) and yield white to tan-brown colonies with varying morphology. Microscopically, septate hyphae that

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Fig. 77.29 Coccidioidomycosis. Moist erythematous plaque on the face (A) and multiple papules and suppurative nodules on the arm (B) in two patients living in the southwestern US. C An endosporecontaining spherule within a giant cell. C, Courtesy, Jennifer  

McNiff, MD.

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Treatment

LIFE CYCLE OF COCCIDIOIDES IMMITIS and C. POSADASII

Chlamydospore Segmented hyphae Arthrospores

As in the other dimorphic fungal infections, systemic antifungal therapy is required for severe or disseminated disease. Amphotericin B is the most effective medication, and the intravenous dose for severe disease is 1.0–1.5 mg/kg per day (higher dose for patients with AIDS). The chronic nature of disseminated disease requires prolonged therapy with itraconazole (400 mg/day) or, in the case of meningitis, fluconazole. Voriconazole and posaconazole, which have in vitro activity against coccidioidomycosis equal or superior to that of itraconazole, have been used successfully (alone or in combination with liposomal amphotericin B) to treat disseminated disease62. Ketoconazole is no longer routinely used.

Paracoccidioidomycosis Endospores

Germ tube

Spherule

Endospore germination

Fig. 77.30 Life cycle of Coccidioides immitis and C. posadasii.  

Synonyms:  ■ South American blastomycosis ■ Brazilian blastomycosis

Introduction and epidemiology

Paracoccidioidomycosis is caused by the dimorphic fungus Paracoccidioides brasiliensis. It is endemic to the Central and South American countries of Brazil, Argentina, Venezuela, Ecuador, and Colombia.

Pathogenesis

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form thick-walled, barrel-shaped arthroconidia are seen at both temperatures. These arthroconidia alternate with thin-walled, vacant cells, which rupture and release the infectious arthroconidia when mature (Fig. 77.30). The infectious hyphal forms produced in culture should be examined with extreme caution, as the examiner is at risk for contracting the disease. Serologic testing and exoantigen testing are useful in making the diagnosis of coccidioidomycosis. PCR-based assays are also available and in situ hybridization has been described63,68.

P. brasiliensis is a dimorphic saprophyte that is found in the soil. In most cases, infection occurs via inhalation of the conidia from the environment. Pulmonary disease ensues and can be followed by dissemination to the skin, mucous membranes, gastrointestinal tract, spleen, adrenal glands, and lymph nodes.

Clinical features

Paracoccidioidomycosis has several different clinical presentations with varying prognoses. In many patients, the primary pulmonary disease



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Ramos-e-Silva, MD, PhD; C, Courtesy, C Massone, MD.

accompanied by suppurative and granulomatous inflammation. Yeast forms are found within and outside of giant cells. Large, thick-walled organisms with multiple narrow-based buds may be seen, leading to an outline that resembles a “mariner’s wheel” (Fig. 77.31C).

Differential diagnosis

The differential diagnosis includes mucocutaneous leishmaniasis, granulomatosis with polyangiitis, NK-cell lymphoma, and syphilis (endemic and epidemic) (see Table 45.3). Microscopic examination and culture of the organism are essential for diagnosing paracoccidioidomycosis. KOH or calcofluor examination of an appropriate specimen (sputum, dermal scraping, or pus) may reveal round to ovoid cells with narrow-based buds, which are also seen when the organism is cultured at 37°C.

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77 Fungal Diseases

Fig. 77.31 Paracoccidioidomycosis. Ulcerated plaques on the palate (A) and verrucous granulomatous red– brown plaques with crusting involving the perioral region and upper lip (B). C Dermal histiocytic infiltrate and yeast forms with multiple small, narrow-based buds. The organisms are highlighted with a methenamine silver stain (inset). A, B, Courtesy, Marcia

Treatment

There are several effective treatment options for paracoccidioidomycosis, including amphotericin B, systemic azoles, and sulfonamides. Prolonged therapy is generally required. In disseminated disease, systemic therapy with amphotericin B or an azole antifungal is indicated. Itraconazole is a preferred treatment because it provides reasonable efficacy and side-effect profile, as well as low potential for recurrent disease. Treatment with voriconazole can also be effective. Attempts to modulate the immune system via peptides derived from the P. brasiliensis 43 kDa glycoprotein have been described69.

Opportunistic Pathogens Introduction %

Opportunistic mycotic infections may occur in individuals with primary or secondary immunodeficiencies. Worldwide, disseminated candidiasis and aspergillosis are the two most common systemic mycoses in neutropenic patients. Less commonly, zygomycosis, phaeohyphomycosis (due to pigmented fungi; see below), and hyalohyphomycosis (due to non-pigmented [hyaline] fungi; most often fusariosis) are seen (Fig. 77.32). Disseminated histoplasmosis, coccidioidomycosis, cryptococcosis, and infection due to Talaromyces (Penicillium) marneffei are the systemic mycoses seen most commonly in the setting of HIV infection56. Opportunistic pathogens are less virulent than true pathogens and impart no specific protective immunity to those infected.

History Aspergillosis was among the first mycoses recognized, with the initial report of a human case by Sluyter in 1847. In 1855, Kurchenmeister isolated Mucor from the lung and described zygomycosis. Benham distinguished cryptococcosis from blastomycosis in the 1930s. Fusarium emerged as an opportunistic pathogen in neutropenic oncology patients in the 1990s. &

is subclinical to mild. When progressive disseminated disease occurs, mucocutaneous involvement is commonly seen. Lesions are often painful and ulcerative or verrucous; they are typically found on the face and in the nasal and oral mucosae (Fig. 77.31A,B). The ulcerations are referred to as “moriform stomatitis”. Lymphangitic spread may occur, resulting in cervical lymphadenopathy. Another clinical presentation is that of primary mucocutaneous paracoccidioidomycosis. This frequently has an intraoral and perioral distribution due to trauma from chewing contaminated sticks and leaves. Granulomatous lesions are typically seen. Primary cutaneous paracoccidioidomycosis can also occur via direct inoculation of the skin, resulting in the development of a verrucous papule or plaque or cutaneous ulceration.

Pathology

The histologic features of paracoccidioidomycosis resemble those of blastomycosis (see above). Pseudoepitheliomatous hyperplasia is

Epidemiology With the exception of several dimorphic fungi, opportunistic fungal infections occur worldwide and have no geographic predilection. The causative pathogens are commonly found in the environment. For example, Aspergillus spp., Fusarium spp., and Mucormycetes are soil saprophytes found in decaying vegetation70. Cryptococcus neoformans can be isolated from avian (especially pigeon) droppings. T. marneffei is endemic to Southeast Asia and China, where the reservoir is thought to be in bamboo rats, but imported infections have been reported in the US. Lastly, Candida spp. commonly colonize the skin and gastrointestinal tract1. Overall, the incidence of opportunistic mycoses increased in conjunction with the greater use of immunosuppressive therapy and the HIV pandemic. In fact, some opportunistic mycoses are considered to be AIDS-defining diseases (see Ch. 78). Notably, the incidence of disseminated candidiasis and aspergillosis has fallen with the use of prophylactic voriconazole in high-risk oncology patients (e.g. neutropenic patients with hematologic malignancies, hematopoietic stem cell transplant recipients). However, voriconazole lacks activity against Mucormycetes, which are covered by more recently approved antifungals (e.g. posaconazole, isavuconazole).

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CUTANEOUS FEATURES OF COMMON OPPORTUNISTIC MYCOSES Microscopic appearance

Mycosis

Common cutaneous presentations

Systemic candidiasis† • Candida albicans • C. tropicalis (frequent skin lesions) • C. glabrata, C. krusei (intrinsic fluconazole resistance)

Firm erythematous papules and nodules, often with a pale center (but possibly hemorrhagic); ecthyma gangrenosum-like lesions

Aspergillosis† • Aspergillus flavus and fumigatus

Necrotic papulonodules, subcutaneous nodules (secondary cutaneous); may be associated with an intravenous catheter site (primary cutaneous); disseminated disease usually results from primary pulmonary involvement; galactomannan (more specific, lower sensitivity) and 1,3β-D-glucan (less specific for aspergillosis) serum assays can be used to screen high-risk patients

Mucormycosis† • Mucor • Rhizopus • Lichtheimia (formerly Absidia)

Ecthyma gangrenosum-like lesions, cellulitis, facial edema (commonly unilateral due to contiguous spread of sino-orbital disease), necrotic papulonodules, plaques, large hemorrhagic crusts on the face; may be associated with an intravenous catheter site (primary cutaneous)

Aspergillus

45˚ branching, septate

Rhizopus

90˚ branching, non-septate

Subcutaneous cysts, ulcerated plaques, hemorrhagic pustules, necrotic papulonodules

Alternaria

Phialophora

Hyalohyphomycosis • Fusarium • Talaromyces (Penicillium) • Paecilomyces

Umbilicated or necrotic papules, pustules, abscesses, cellulitis, subcutaneous nodules; Fusarium infection can be associated with a periungual focus

Fusarium

Talaromyces

Trichosporonosis • Trichosporon spp.

Papulovesicles, purpuric papules, necrotic papulonodules

**

Cryptococcosis • Cryptococcus

Ulceration, cellulitis, molluscum contagiosum-like lesions; assays to detect cryptococcal antigens in blood or CSF are available

*

Phaeohyphomycosis • Alternaria • Exophiala • Phialophora

*

**

* Less common **† Especially in the setting of AIDS

With the use of prophylactic voriconazole, posaconazole, and isavuconazole in high-risk oncology patients (e.g. neutropenic patients with hematologic malignancies, hematopoietic stem cell transplant recipients), the incidences of disseminated candidiasis, systemic aspergillosis, and mucormycosis (posaconazole and isavuconazole) have declined in these individuals

Fig. 77.32 Cutaneous features of common opportunistic mycoses. While the lesions of opportunistic fungal infections seem nonspecific, certain presentations may be more likely associated with a particular species.  

Pathogenesis

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Aspergillosis is an opportunistic mycosis that is caused by fungi in the genus Aspergillus, most often A. fumigatus and A. flavus. Burns, sites of trauma, surgical wounds, intravenous catheters (Fig. 77.33A), and macerated skin underlying occlusive dressings typically serve as portals of entry in primary cutaneous aspergillosis71. The risk of dissemination is significant in immunocompromised individuals. In secondary cutaneous aspergillosis (a more common form), the conidia are inhaled, producing a primary lung infection that is followed by dissemination to the skin. Immunosuppression – particularly neutropenia plus chronic use of corticosteroids and sometimes late-stage AIDS – is a major risk factor for the development of invasive or disseminated aspergillosis. Fungi in the subphylum Mucoromycotina, class Mucormycetes (also known as Mucoromycetes; formerly Zygomycetes), and order Mucorales cause mucormycosis, which was previously called zygomycosis. The genera most commonly responsible are Rhizopus, Mucor, Rhizomucor, and Lichtheimia (formerly Absidia)72. Risk factors include poorly controlled diabetes mellitus as well as other forms of immunosuppression, especially when associated with neutropenia. Primary infections can be rhino-orbito-cerebral, pulmonary or gastrointestinal as well as cutaneous via direct inoculation of the skin in settings similar to those of primary cutaneous aspergillosis; hematogenous dissemination may occur in immunocompromised hosts. Skin lesions that arise from contiguous spread (e.g. from the sinuses) or hematogenous dissemination are referred to as secondary cutaneous mucormycosis.

Aspergillosis and mucormycosis are both characterized by necrotic skin lesions due to the angioinvasive nature of these organisms. Cryptococcus neoformans is the causative pathogen in cryptococcosis. This organism (which can be acquired from pigeons) is inhaled, resulting in a primary pulmonary infection with subsequent dissemination to the CNS, bone, and skin. The latter is referred to as secondary cutaneous cryptococcosis. Primary cutaneous cryptococcosis can also occur, but the diagnosis is made after a systemic evaluation has been performed. Immunocompetent hosts may acquire this infection, but they have a low risk for dissemination, while immunocompromised hosts, particularly those with AIDS, often develop disseminated disease. The use of antiretroviral therapy (ART) in HIV-infected individuals has led to a dramatic decrease in the incidence of cryptococcosis. Yeasts belonging to the genus Candida are responsible for candidiasis, which can present as a mucocutaneous condition (see above) or, in immunocompromised hosts, a disseminated infection that often originates from the gastrointestinal tract. The ability of Candida to exist in the form of pseudohyphae in tissue and blastoconidia in the bloodstream allows for adaptation and evasion of host defenses73. C. albicans is the most common species, but C. tropicalis is often implicated as the causative agent of fungemia in patients with leukemia. Neutropenia, especially in patients who have received prolonged courses of corticosteroids, sets the stage for disseminated candidiasis; patients are usually also receiving broad-spectrum antibiotics. Hyalohyphomycosis includes infections with Fusarium, Talaromyces, and Paecilomyces spp. (see Fig. 77.32). These molds are found in the soil and throughout the environment and can cause disseminated

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Fungal Diseases

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,

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Fig. 77.33 Clinical findings of opportunistic fungal infections in immunocompromised hosts. Primary cutaneous aspergillosis characterized by hyperpigmented plaques with brown–black scale-crusts at the site of intravenous catheters on the arm (A); firm pink papulonodule due to disseminated candidiasis (B); erythematous papulonodules with central purpura, vesiculation and/or crusting in a leukemic patient with disseminated fusariosis (C); necrotic hemorrhagic bulla due to embolus of Aspergillus flavus (D); cellulitis with large areas of necrosis due to Rhizopus (E) and cryptococcosis (F); disseminated cryptococcosis presenting with crusted lesion(s) resembling molluscum contagiosum (G) and a basal cell carcinoma (H); cryptococcal cellulitis (I); numerous papules and nodules with central umbilication and crusting in disseminated Talaromyces (Penicillium) marneffei infection (J). J, Courtesy, Evangeline Handog, MD and the Dermatology Department, Research Institute for  

Tropical Medicine.

infections in immunocompromised hosts. Disseminated infections with Fusarium, an angioinvasive organism, most often affect neutropenic oncology patients and may originate from a periungual focus (e.g. paronychia, onychomycosis). Talaromyces marneffei is a dimorphic fungus, and HIV patients are particularly at risk.

Clinical features All of the opportunistic mycoses can present with several different types of cutaneous lesions (see Fig. 77.32). Skin findings range from firm papules (Fig. 77.33B) and purpuric or necrotic papulonodules (Fig. 77.33C) to hemorrhagic bullae (Fig. 77.33D) and ulcers. Subcutaneous nodules and cellulitis, often with areas of necrosis, can also be seen (Fig. 77.33E,F). In disseminated aspergillosis, the CNS, kidneys, and heart (in addition to the lungs) are often involved in severe widespread disease. The prognosis is poor but improves when the patient is no longer neutropenic or corticosteroids are discontinued. Secondary cutaneous mucormycosis due to an underlying sinus infection may initially present with subtle unilateral facial swelling and mild erythema, while advanced

disease is characterized by large areas of necrosis covered by a thick hemorrhagic crust. Secondary cutaneous cryptococcosis is associated with a poor overall prognosis, with a mortality rate of up to 80% if left untreated74. Findings range from papulonodules to cellulitis and panniculitis to necrotic ulcers and abscesses; they may also resemble lesions of molluscum contagiosum, herpes viral infections, or basal cell carcinoma (Fig. 77.33G,H)75. Approximately 15% of patients with systemic cryptococcosis have skin lesions, and no predictable body distribution has been identified76. Cutaneous lesions of disseminated candidiasis frequently present as firm pink papules or nodules (see Fig. 77.33B) on the trunk and extremities. The lesions often have a pale center but may be purpuric in patients with thrombocytopenia. Other presentations include ecthyma gangrenosum-like lesions (hemorrhagic bulla followed by a necrotic eschar; see Fig. 77.20H), pustules, abscesses, and purpura (in thrombocytopenic patients). While C. albicans is the most commonly associated species, C. tropicalis is more likely to produce cutaneous lesions multidrug-resistant C. auris is an emerging cause of systemic infections

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Infections, Infestations, and Bites

12

and can also contaminate wounds76a. Systemic sites of involvement include the liver, spleen, muscle, kidney, retina, and heart valves. A sepsis-like syndrome may occur, with tachycardia, hypotension, dyspnea, and high fevers. Like histoplasmosis, T. marneffei typically infects the liver, spleen, and lymph nodes. The skin may be involved with umbilicated papules that resemble molluscum contagiosum, necrotic nodules, and acneiform lesions. The most common sites are the face (particularly the forehead), arms, and trunk (Fig. 77.33I). When mucosal surfaces are involved, ulcers and papules are seen; prominent lymphadenopathy is often present. Skin lesions develop in ~75% of patients with disseminated fusariosis, typically presenting as targetoid erythematous, ecthyma gangrenosum-like, or purpuric nodular lesions in a widespread, scattered distribution (see Fig. 77.33C). Affected individuals often have high fevers and severe myalgias.

Pathology Histologic examination of lesions of cutaneous aspergillosis demonstrates 45° dichotomous branching of hyaline, septate hyphae that are best demonstrated with methenamine silver or PAS staining (Fig. 77.34A). Suppurative and granulomatous inflammation and/or necrosis may be observed. In mucormycosis, there are highly characteristic broad, non-septate hyphae that have 90° branching and have been likened to ribbons (Fig. 77.34B). PAS staining may be helpful. Suppuration and necrosis, as well as blood vessel invasion by the fungi, are often seen. Histologic findings in cryptococcosis are described as either gelatinous with numerous organisms and little inflammation, or granulomatous with fewer organisms, more inflammation, and little necrosis. While a PAS stain highlights the central yeast forms (Fig. 77.34C), mucicarmine or Alcian blue is used to visualize the characteristic capsule. India ink preparations, e.g. of CSF or dermal scrapings, also demonstrate the presence of the capsule. The wider the capsule and the more severe the immunocompromised state, the less the inflammation. In disseminated candidiasis, budding yeast and pseudohyphae are seen in the dermis, rather than in the stratum corneum as in mucocutaneous candidiasis. T. marneffei has microscopic characteristics similar to histoplasmosis. The small organisms are numerous and found within macrophages and giant cells (see Table 77.18). The histologic findings of fusariosis are similar to those of aspergillosis, with acute-branching, septate hyphae, angioinvasion, necrosis and a variable granulomatous infiltrate.

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Differential diagnosis

1360

Microscopic examination of dermal scrapings (using KOH or calcofluor), histologic analysis, and culture of skin tissue are used to diagnose opportunistic fungal infections. The former studies are important considering that many of these organisms can also represent culture contaminants77. The clinical differential diagnosis ranges from folliculitis and molluscum contagiosum to cellulitis and ecthyma gangrenosum due to a disseminated bacterial infection. When there are necrotic eschars, the possibility of herpes zoster or vasculitis may be raised (see Fig. 77.32). Macroscopically, cultures of Aspergillus flavus and A. fumigatus have been likened to “south sea islands” because the central portion is khaki green (flavus) or blue–green (fumigatus) with a rim of white to yellow color. Microscopically, spherical “heads” with conidia forming on the exterior are seen. In zygomycoses, culture reveals fast-growing “woolly” colonies in most instances. Microscopically, rhizoids, round sporangia, and sporangiospores (asexual spores formed within sporangia) are seen (see Fig. 77.32)47. Culture of Cryptococcus neoformans yields a creamcolored colony that is similar in appearance to Candida colonies. On birdseed agar, the C. neoformans colony becomes brown. Because T. marneffei is a dimorphic fungus, at 25°C the mold form is seen with a diffusible red pigment, and at 37°C the colony appears as a yeast. Antibodies against the capsule can be detected in cryptococcosis, and high titers herald a poor prognosis. Serum assays for components of the fungal cell wall, such as 1,3 β-D-glucan (detects a variety of fungi, including Aspergillus and Fusarium) and galactomannan (relatively specific for Aspergillus but somewhat less sensitive), have been used to screen high-risk patients for early evidence of an invasive fungal

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Fig. 77.34 Histologic findings of opportunistic fungal infections in immunocompromised hosts. A Septate hyphae (arrow) within necrotic skin from a patient with disseminated aspergillosis. B Ribbon-like, non-septate Rhizopus hyphae in a “touch” preparation of dermal scrapings from the base of a necrotic bulla. C Numerous dermal yeast forms with gelatinous capsules in secondary cutaneous cryptococcosis (PAS stain). A, Courtesy, Lorenzo Cerroni, MD;  

B, Courtesy, Jean L Bolognia, MD; C, Courtesy, Athanasia Syrengelas, MD, PhD.

Treatment Prevention of opportunistic mycoses in high-risk patients can be aided by reduced exposure to environments such as construction sites and the use of ventilation systems. Prophylaxis with systemic antifungals (e.g. fluconazole, posaconazole, voriconazole, isavuconazole) is commonly administered to patients receiving myelosuppressive chemotherapy and to hematopoietic stem cell transplant recipients, both before and during periods of neutropenia. Even in the absence of neutropenia, individuals on chronic high-dose systemic corticosteroids (e.g. with chronic GVHD) are at significant risk for opportunistic fungal infections and represent another group now receiving prophylaxis. In the past, a febrile neutropenic patient unresponsive to systemic broadspectrum antibiotics was empirically begun on amphotericin B. Nowadays, that patient might receive voriconazole, posaconazole, isavuconazole, or one of the echinocandins (e.g. caspofungin; Table 77.19; see Ch. 127). Of note, voriconazole is a triazole that has activity against Aspergillus and Fusarium as well as Candida (but not Mucormycetes); it causes photosensitivity associated with an increased risk of squamous cell carcinoma and melanoma and, like itraconazole, drug–drug interactions due to inhibition of cytochrome P450. Posaconazole and isavuconazole, triazoles with a similar range of activity (except for less Fusarium coverage with isavuconazole) that also cover Mucormycetes, are used for both treatment and prophylaxis of opportunistic fungal infections. Once an opportunistic mycosis is diagnosed, prompt treatment is essential. Primary cutaneous infections with opportunistic molds, if localized, can be surgically excised, followed by administration of oral antifungals. Disseminated infections carry a poor prognosis and are frequently fatal, particularly when treatment is delayed or ineffective. Amphotericin B (including lipid formulations) had been the standard treatment for several decades. However, voriconazole has proven superior for invasive fungal infections due to Aspergillus, and, in the case of disseminated candidiasis, caspofungin can also be administered80 (see Ch. 127). For systemic infections due to other opportunistic fungi, amphotericin B is sometimes still employed, but voriconazole does have activity against Fusarium and posaconazole has activity against both Fusarium and Mucormycetes. In addition to amphotericin B and several triazoles, terbinafine may have activity against T. marneffei, which has a high mortality rate if inadequately treated. Unfortunately, recurrence is likely unless treatment is continued indefinitely81.

Phaeohyphomycosis Introduction and history

Phaeohyphomycosis refers to infections with a group of dematiaceous fungi (i.e. pigmented due to melanin in the cell wall) that produce distinct brown to black hyphae in tissue rather than Medlar bodies or

grains (see chromoblastomycosis and eumycotic mycetoma above). Although systemic disease can occur, particularly spread to the CNS from a primary lung source, this section will focus on the other three forms of phaeohyphomycosis – superficial, cutaneous, and subcutaneous. Ajello and colleagues coined the term “phaeohyphomycosis” in 1974. Initially, the list of causative pathogens was limited, but it is now extensive and continues to lengthen11.

CHAPTER

77 Fungal Diseases

infection. PCR-based assays have also become available for detection of many opportunistic fungi (especially Aspergillus)78,79.

Epidemiology

Because phaeohyphomycosis encompasses infections caused by many fungi, the epidemiology is complex. All age groups and both genders may be affected. There may be a slightly higher incidence in men due to increased environmental and occupational exposure. The culprit fungi in phaeohyphomycosis are found in plants and soil, making individuals with certain occupations, activities, and cultural habits (such as not wearing protective footwear) at higher risk of infection.

Pathogenesis

Superficial phaeohyphomycosis includes tinea nigra and black piedra (see above), while cutaneous phaeohyphomycosis includes infections of the hands, feet, and nails that mimic tinea infections in the same locations (e.g. N. hyalinum, N. dimidiatum; see Table 77.11). Trauma is typically the cause of subcutaneous phaeohyphomycosis. Both immuno­ competent and immunocompromised hosts may acquire this disease. The immune status of the patient has a significant effect on the severity and the likelihood for disseminated disease; Cladophialophora bantiana is most commonly associated with CNS disease74. Secondary cutaneous phaeohyphomycosis occurs when dematiaceous fungi spread from other sites to the skin.

Clinical features

The clinical presentation of cutaneous phaeohyphomycosis is similar to that of dermatophyte infections of the hands, feet, or nails. Subcutaneous phaeohyphomycosis most commonly presents as a nodule or plaque in regions of the body that are prone to trauma (Fig. 77.35A). The course is usually chronic, with slowly progressive disease. Clinical manifestations of disseminated disease include nonspecific skin lesions (papules, plaques, nodules) and signs of cerebral involvement.

Pathology

Histologic examination of cutaneous and subcutaneous phaeohyphomycosis reveals pigmented hyphae in the stratum corneum and dermis/ subcutis, respectively (Fig. 77.35B). In the latter, there are cyst-like abscesses that can have a fibrous capsule, hence the term “phaeomycotic cysts.” Occasionally, implanted material (e.g. a splinter) may also be observed.

Differential diagnosis

For the subcutaneous and systemic forms, the differential diagnosis may include a foreign body granuloma, cutaneous leishmaniasis, chromoblastomycosis, and dimorphic fungal infections. KOH examination

TREATMENT OF OPPORTUNISTIC MYCOSES

Aspergillosis

Mucormycosis

Cryptococcosis

Candidiasis

T. marneffei infection

Fusariosis

Forms of administration

Amphotericin B

+

+

+

+

+

+

iv

Itraconazole (200–400 mg/day)

+



+

+

+



po, iv

Fluconazole





+

+





po, iv

Voriconazole

+



+

+

+

+

po, iv

Posaconazole

+

+

+

+

+

+

po

Isavuconazole

+

+

+

+





po, iv

Caspofungin

+





+





iv

Micafungin

+





+





iv

Anidulafungin

+





+





iv

Table 77.19 Treatment of opportunistic mycoses. Appropriate selection of therapy for opportunistic infections is essential, given the likelihood of rapid, widespread dissemination and high mortality rates60. iv, intravenously; po, orally.  

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12 Infections, Infestations, and Bites

(superficial and cutaneous types), culture (all types), and histopathology (usually just subcutaneous and systemic types) allow the diagnosis to be made. Determination of genera and species requires fungal culture, but histopathology is useful in determining the extent of invasion and in differentiating causative pathogens from contaminants in culture specimens. Exophiala jeanselmei and E. dermatitidis are the organisms most commonly isolated from subcutaneous phaeohyphomycosis.

Treatment

Subcutaneous disease is surgically excised, if possible82; complete surgical excision is usually curative. Systemic disease due to dematiaceous fungi continues to be a therapeutic dilemma, as it is difficult to eliminate with oral antifungals alone. Nevertheless, itraconazole, given at a dose of 200 mg twice daily for a prolonged course (>12 months), has some efficacy for the non-surgical treatment of phaeohyphomycosis. Close follow-up is required and includes repeat cultures and histologic analyses of affected sites. Additional treatments for systemic disease include voriconazole, posaconazole, amphotericin B, and flucytosine.

Pneumocystis $

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Fig. 77.35 Phaeohyphomycosis – clinical and histopathologic findings. A Purpuric plaque with central necrosis and surrounding erythema in a patient with subcutaneous phaeohyphomycosis due to Exerohilum rostratum. B PAS-positive hyphae with focal pigmentation within a phaeohyphomycotic cyst. B, Courtesy, Luis Requena, MD.

In the past, Pneumocystis jiroveci (formerly referred to as Pneumocystis carinii) was classified as a protozoan. Currently, it is considered to be a fungus, based on genetic and biochemical analyses. This opportunistic infection occurs in individuals who are immunocompromised, including those with AIDS. The lungs are the most common site of infection (pneumonia), but, on occasion (500 CD4 cells/mm +

3

Asymptomatic Persistent generalized lymphadenopathy

• •

Clinical stage 2 – mild; immunologic correlate*: 350–499 CD4+ cells/mm3 Herpes zoster Fungal nail infection • Pruritic papular eruptions • Angular cheilitis • Recurrent oral ulcerations • Recurrent/chronic upper respiratory tract infections (sinusitis, otitis media/otorrhea, tonsillitis, pharyngitis)

Seborrheic dermatitis Moderate unexplained weight loss (1 month in adults, >2 weeks in children) • Unexplained persistent fever (≥37.6°C intermittent or constant, for >1 month) • Pulmonary tuberculosis (current) • Unexplained anemia (1 month) • Chronic cryptosporidiosis (with diarrhea) • Chronic isosporiasis • Symptomatic HIV-associated nephropathy or symptomatic HIV-associated cardiomyopathy • Cerebral or B-cell non-Hodgkin lymphoma, or other HIV-associated solid tumor •

Atypical disseminated leishmaniasis Recurrent severe bacterial pneumonia • Recurrent non-typhoidal Salmonella bacteremia • Invasive cervical carcinoma • •

Recurrent severe bacterial infections such as empyema, pyomyositis, bone or joint infection, or meningitis (but excluding pneumonia)



*In individuals ≥6 years of age; corresponding counts in children 500 CD4+ cells/mm3

adults with atopic dermatitis (Fig. 80.5); risk is associated with mutations in the gene encoding filaggrin • A similar presentation can occur in patients with an impaired skin barrier due to other conditions such as burns, irritant contact dermatitis, pemphigus (foliaceus, vulgaris), Darier disease, Hailey–Hailey disease, mycosis fungoides, Sézary syndrome, ichthyoses, and rarely Grover disease and pityriasis rubra pilaris with acantholysis, as well as following ablative laser procedures or application of topical 5-fluorouracil • Usually due to HSV-1 •

Table 80.3 Other clinical presentations of herpes simplex virus (HSV) infections.  

Rapid, widespread cutaneous dissemination of HSV infection in areas of dermatitis/skin barrier disruption • Monomorphic, discrete, 2–3 mm punched-out erosions with hemorrhagic crusts (see Fig. 80.5) are evident more often than intact vesicles • May have fevers, malaise and lymphadenopathy • Occasionally complicated by bacterial superinfections (e.g. Staphylococcus aureus, group A streptococci) or systemic dissemination of HSV infection • Differential diagnosis includes “eczema coxsackium” due to coxsackievirus A6 infection and streptococcal infection •

CHAPTER

Form of infection

Clinical settings and HSV type(s)

Cutaneous and/or extracutaneous findings

Herpetic whitlow



Often in young children, usually due to HSV-1 (Fig. 80.6A) • Increasing frequency in adolescents/adults (Fig. 80.6B,C) secondary to digital–genital contact, usually due to HSV-2 • Historically in dental and medical personnel who did not use gloves



Herpes gladiatorum



Participation in contact sports such as wrestling (Fig. 80.7) • Usually due to HSV-1



Herpes simplex folliculitis



Shaving with a blade razor (e.g. herpetic sycosis in a man’s beard area) • Usually due to HSV-1 • HIV-positive or otherwise immunocompromised individuals



Severe/chronic HSV infections



Immunocompromised patients, e.g. hematopoietic stem cell or solid organ transplant recipients, individuals with HIV infection or leukemia/lymphoma



Pain, swelling, and clustered vesicles on a digit (Fig. 80.6); appearance of vesicles may be delayed • Recurrences in the same location can be a clue to the diagnosis • Often misdiagnosed as blistering dactylitis or paronychia

80 Human Herpesviruses

OTHER CLINICAL PRESENTATIONS OF HERPES SIMPLEX VIRUS INFECTIONS

Distribution reflects sites of contact with another athlete’s skin lesions and is sometimes widespread Rapid development of follicular vesicles and pustules See Table 38.1



Most common presentation is chronic, enlarging ulcerations (Fig. 80.8A,B) • Cutaneous lesions may affect multiple sites or be disseminated • Skin findings are often atypical, i.e. verrucous, exophytic or pustular lesions • Recurrences can involve oral mucosa, including the tongue (Fig. 80.8C) and movable areas that do not overlie bone • Involvement of the respiratory tract, esophagus, and remainder of the gastrointestinal tract may also occur

Predominantly extracutaneous Ocular HSV infection

Often due to HSV-2 in newborns (see below) Usually due to HSV-1 in children and adults

Primary infection: unilateral or bilateral keratoconjunctivitis with eyelid edema, tearing, photophobia, chemosis, and preauricular lymphadenopathy • Branching dendritic lesions of the cornea represent a pathognomonic finding • Recurrent episodes are common and typically unilateral • Complications include corneal ulceration and scarring, globe rupture, and blindness







Herpes encephalitis



Most common cause of fatal sporadic viral encephalitis in the US • Associated with mutations in the genes encoding Toll-like receptor 3 or UNC-93B, which impair interferon-based cellular antiviral responses (see Table 80.2) • Usually due to HSV-1 • Natalizumab, an anti-α4 integrin monoclonal antibody used for the treatment of multiple sclerosis and Crohn disease, increases the risk of encephalitis and meningitis due to HSV and VZV

Proctitis



Most common in men who have sex with men

Manifestations can include fever, altered mental status, bizarre behavior, and localized neurologic findings • The temporal lobe is often involved • Mortality ≥70% without treatment; residual neurologic defects in most survivors • Herpes labialis may be a coincidental finding •

Manifestations include diarrhea, anal pain, and a feeling of rectal fullness



Cutaneous and extracutaneous Neonatal HSV infection

Occurs in ~1 : 10 000 newborns in the US8,9, usually resulting from exposure to HSV during a vaginal delivery • Risk of transmission is highest (30–50%) for women who acquire a genital HSV infection (which is often asymptomatic) near the time of delivery • Risk of transmission is low (50% without treatment and ~15% with treatment; many survivors have neurologic deficits • •

Table 80.3 Other clinical presentations of herpes simplex virus (HSV) infections. (cont’d)  

Treatment and Prevention FDA-approved antiviral agents for treatment of recurrent episodes of orolabial herpes in immunocompetent persons include valacyclovir 2 g twice daily for 1 day, a single 1.5-g dose of famciclovir, and the topical treatments listed in Table 80.4. Randomized controlled trials have shown that these therapies have modest benefits, decreasing the dura-

tion of mucocutaneous lesions, viral shedding, and pain20–23; efficacy is maximized when treatment is started at the first sign or symptom of a recurrence. Both valacyclovir and famciclovir have also been shown to reduce the frequency of orofacial herpes outbreaks after laser resurfacing. For treatment of primary and recurrent genital herpes, oral antivirals are the agents of choice (see Table 80.4). With initiation within 24–48

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Fig. 80.6 Herpetic whitlow. A Coalescing vesicles and erosions on the distal finger of a child. B An edematous erythematous plaque with relatively subtle central vesicle formation on the thumb of a child. C Grouped vesicles on the toe of an adult. Herpetic whitlow   is sometimes misdiagnosed as cellulitis or blistering distal dactylitis, or, depending on the distribution, paronychia.

Infections, Infestations, and Bites



$

C, Courtesy, Louis A Fragola, Jr, MD.

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%

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Fig. 80.5 Eczema herpeticum. A Monomorphic, punched-out erosions with a scalloped border in this infant with a history of facial atopic dermatitis.   B Monomorphic, small hemorrhagic crusts and erosions coalescing in the popliteal fossae, an area of pre-existing atopic dermatitis. A, Courtesy, Julie V Schaffer,  

MD; B, Courtesy, Kalman Watsky, MD.

1406

hours of onset, acyclovir, famciclovir, and valacyclovir reduce the duration of viral shedding, pain, and time to healing for first-episode and recurrent genital herpes. Intravenous acyclovir is indicated for neonatal HSV infection, severe infections in immunocompromised hosts, severe eczema herpeticum, and patients with systemic complications. In immunocompromised patients, it is important to treat with oral or intravenous antivirals until the cutaneous lesions are completely healed. Systemic antiviral agents need to be dose-adjusted for patients with impaired renal function (Table 80.5). Chronic suppressive therapy with oral antiviral agents is usually reserved for patients with six or more outbreaks per year (see Table 80.4), although clinicians often exercise more lenient criteria for initiation of therapy for individuals with severe or problematic outbreaks, an insufficient prodrome to benefit from episodic therapy, or immunosuppression. In addition to decreasing the frequency of symptomatic outbreaks or even eliminating them, suppressive therapy decreases asymptomatic viral shedding by 95% and can thereby reduce transmission of genital herpes to a susceptible partner24. Daily suppressive therapy, together with consistent condom use and avoidance of sexual activity during recurrences, is therefore also recommended for individuals with genital herpes who have a seronegative partner.

Fig. 80.7 Herpes gladiatorum. Grouped vesicles and erosions on the neck of a high-school wrestler. Courtesy, Louis A Fragola, Jr, MD.  

The emergence of acyclovir-resistant HSV is an increasing concern for immunocompromised individuals. Foscarnet is the only antiviral drug approved by the FDA for treatment of acyclovir-resistant HSV (see Fig. 127.10). Cidofovir is another antiviral agent that has shown efficacy in the treatment of acyclovir-resistant HSV. The use of foscarnet or systemic cidofovir is limited by potentially severe renal toxicity and the requirement for intravenous administration. Although not



Courtesy, Frank Samarin, MD.

CHAPTER

80 Human Herpesviruses

Fig. 80.9 Neonatal herpes. Grouped papulovesicles with an erythematous base on the chest. Note the scalloped borders in areas of coalescence.

$

Fig. 80.10 Direct fluorescent antibody assay. A keratinocyte that is infected with herpes simplex virus fluoresces green. This assay can also detect the presence of varicella– zoster virus and has a rapid turnaround time.  

Courtesy, Marie L Landry, MD.

%

Fig. 80.8 Herpes simplex virus infections in immunocompromised hosts. A, B Enlarging ulcerations in a child with acute lymphocytic leukemia who was presumed to have a Rhizopus infection (A) and in a young man with AIDS (B). C Coalescence of eroded, yellow–white papules and plaques on the tongue.  

&

FDA-approved, compounded topical cidofovir has been advocated by the CDC as a “user-friendly”, albeit expensive, alternative treatment25. Individuals co-infected with HIV and HSV have more severe outbreaks and more frequent viral shedding than those without HIV infection. When added to the medical regimen of HIV-infected patients, antiherpetic suppressive therapy appears to allow the co-infected person to respond better to antiretroviral therapy and to reduce genital and plasma HIV-1 RNA levels, but it does not seem to decrease the risk of HIV-1 transmission26. Oral acyclovir, famciclovir, and valacyclovir can be used for genital and orolabial HSV in the setting of HIV infection if there is no evidence of acyclovir resistance. There is significant interest in prevention of HSV disease. Between 70% and 80% of HSV is transmitted during periods of asymptomatic viral shedding. Sexual abstinence is the only method for absolute

Fig. 80.11 Tzanck smear. Note the multinucleated epithelial giant cells from a patient with herpes simplex viral infection. Courtesy, Louis A Fragola, Jr, MD.  

prevention of genital herpes, which can be transmitted even with the use of condoms27. In addition to antiviral therapy, patient education regarding prevention of genital herpes transmission is essential. There is currently no licensed vaccine available for HSV, although several vaccines are under development and evaluation for prevention of HSV infection and recurrences. GEN-003, a therapeutic vaccine under investigation for genital HSV-2 infection, was found in a phase I/IIa clinical trial to reduce the rates of outbreaks and asymptomatic viral shedding28. In randomized controlled studies, adults with a history of genital herpes due to HSV-2 who received the helicase-primase inhibitor pritelivir had significantly decreased HSV shedding and fewer days with genital lesions than those who received placebo or valacyclovir28a; however, drug development in the US has been suspended due to possible adverse effects such as anemia in primate studies.

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Epidemiology

Infections, Infestations, and Bites

12

Fig. 80.12 Histology of herpes simplex viral infection. Intraepidermal vesicle with ballooning degeneration of keratinocytes and multinucleated giant cells; the latter arise from the fusion of infected keratinocytes. Note the steel-gray nuclei with margination of chromatin and inclusions (insets). Courtesy, Lorenzo  

Cerroni, MD.

VARICELLA–ZOSTER VIRUS (VZV; HHV-3) Synonyms/clinical forms:  ■ Varicella – chickenpox ■ Herpes zoster – shingles

Key features ■ VZV is the etiologic agent of varicella (chickenpox) and herpes zoster (shingles) ■ VZV has a high morbidity and mortality rate in immuno­ compromised hosts ■ Antiviral treatment as well as vaccination can reduce or eliminate serious disease-associated sequelae and decrease the incidence of VZV infection

Introduction VZV is the etiology of varicella (chickenpox) and herpes zoster (shingles). Varicella is usually symptomatic, and before the advent of the varicella vaccine, it occurred in 90% of children in the US by the time they reached 10 years of age. Herpes zoster represents reactivation of latent VZV infection and develops in ~20% of healthy adults and 50% of immunocompromised persons, with substantial morbidity and mortality in the latter group. Early initiation of antiviral treatment can reduce or eliminate serious sequelae of VZV infections.

History

1408

Heberden first distinguished chickenpox from smallpox in 1767. The term “chickenpox” is thought to come from either the French word “chiche-pois” for chickpea (referring to the size of the vesicles) or the Old English word “gigan” meaning “to itch”. The relationship between varicella and herpes zoster was first recognized in 1888, when von Bokay described the development of varicella in children following exposure to those with herpes zoster infection. Kundratitz (1922) and Bruusgaard (1932) more convincingly demonstrated the association between the two diseases by the development of varicella in susceptible children who had been inoculated with vesicle fluid from patients with herpes zoster. This was followed by the identification of the same virus in both diseases, confirming that their etiologies were identical.

VZV has a worldwide distribution and 98% of the adult population is seropositive. In the pre-vaccine era, 90% of children 80 years of age. However, there is evidence that exposure to varicella can protect seropositive adults from the development of zoster, and it has been postulated that widespread vaccination against varicella could reduce this immune boosting effect and increase the incidence of zoster. Whether this hypothetical increase will be counterbalanced by the zoster vaccine remains to be determined. Other risk factors for herpes zoster include mental and physical stress, a family history of zoster, use of tofacitinib or proteasome inhibitors (e.g. bortezomib, carfilzomib), and an immunocompromised state, especially when due to HIV infection and allogeneic hematopoietic stem cell transplantation30,31.

Pathogenesis Airborne droplets are the usual route of transmission of varicella, although direct contact with vesicular fluid is another mode of spread, and the incubation period is 11–20 days. Varicella is extremely contagious, and 80–90% of susceptible household contacts develop a clinically evident infection. The affected individual is infectious from 1–2 days before skin lesions appear until all the vesicles have crusted. During varicella infection, primary viremia occurs after an initial 2–4 days of viral replication within regional lymph nodes. A cycle of viral replication in the liver, spleen, and other organs is then followed by a secondary viremia, which seeds the entire body 14–16 days postexposure. During this period, the virus enters the epidermis by invading capillary endothelial cells. VZV subsequently travels from mucocutaneous lesions to dorsal root ganglion cells, where it remains latent until reactivation at a later time. Herpes zoster appears upon reactivation of latent VZV, which may occur spontaneously or be induced by stress, fever, radiation therapy, local trauma, or immunosuppression. During a herpes zoster outbreak, the virus continues to replicate in the affected dorsal root ganglion and produces a painful ganglionitis. Neuronal inflammation and necrosis can result in a severe neuralgia that intensifies as the virus spreads down the sensory nerve. Fluid from herpes zoster vesicles can transmit VZV to seronegative individuals, leading to varicella but not herpes zoster. The transmission rate to susceptible household contacts is ~15% for zoster, compared to 80–90% for varicella.

Clinical Features Varicella A prodrome of mild fever, malaise, and myalgia may occur, especially in adults. This is followed by an eruption of pruritic, erythematous macules and papules, which starts on the scalp and face, and then spreads to the trunk and extremities (Fig. 80.13). Lesions rapidly evolve over ~12 hours into 1–3 mm clear vesicles surrounded by narrow red halos (“dew drops on a rose petal”). The number of vesicles varies from only a few to several hundred, and there is often involvement of the oral mucosa (see Fig. 80.13D). Sparing of the distal and lower extremities is common. Older vesicles evolve to form pustules and crusts, with individual lesions healing within 7–10 days. The presence of lesions in all stages of development is a hallmark of varicella. The disease course is usually self-limited and benign in healthy children. However, prior to introduction of the varicella vaccine,

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Disease context

Drug and dosage

Herpes simplex infections Orolabial herpes* (recurrence)

Topical Docosanol: 5×/d until healed Penciclovir: 1% cream applied q2 h while awake × 4 days Acyclovir: 5% ointment applied q3 h/6 times/day × 7–10 days Acyclovir + hydrocortisone: 5%/1% cream applied 5×/d × 5 days Acyclovir mucoadhesive tablet: 50 mg single application in the canine fossa on the side affected Oral* Acyclovir**: 400 mg po TID × 7–10 days Famciclovir: 1.5 g po × 1 dose Valacyclovir: 2 g po BID × 1 day

Genital herpes (first episode)

Acyclovir: 200 mg po 5×/d × 10 days or 400 mg po TID × 10 days Famciclovir: 250 mg po TID × 10 days Valacyclovir: 1 g po BID × 10 days

Genital herpes (recurrence)

Acyclovir: 400 mg po TID × 5 days or 800 mg po BID × 5 days or 800 mg po TID × 2 days Famciclovir: 1 g po BID × 1 day or 500 mg po × 1 dose then 250 mg po BID × 2 days or 125 mg po BID × 5 days Valacyclovir: 500 mg po BID × 3 days or 1 g po daily × 5 days

Chronic suppression

Acyclovir: 400 mg po BID Famciclovir: 250 mg po BID Valacyclovir: 500 mg po daily for B) Urticarial vasculitis (B, C) Polyarteritis nodosa (B [classic]>C) Livedo reticularis (C) Serum sickness-like reaction (B, C) Urticaria (B, C) Gianotti–Crosti syndrome (B>C)

Necrolytic acral erythema (C) Porphyria cutanea tarda (B, C) Pruritus (B, C) Lichen planus – particularly erosive oral disease (C) Sarcoidosis (with interferon and/or ribavirin therapy*; C>B) Erythema multiforme (B, C) Erythema nodosum (B>C)

*Employed less nowadays. Table 81.8 Cutaneous manifestations of hepatitis B and/or C infection.  

TRICHODYSPLASIA SPINULOSA Synonyms:  ■ Viral-associated trichodysplasia (of

immunosuppression) ■ “Cyclosporine-induced” folliculodystrophy ■ Follicular dystrophy of immunosuppression ■ Pilomatrix dysplasia ■ Trichodysplasia of immunosuppression Trichodysplasia spinulosa is an increasingly recognized entity that was first described in 199967 and subsequently found to be associated with a novel trichodysplasia spinulosa-associated polyomavirus (TSPyV)68,69. This condition occurs primarily in solid organ transplant recipients receiving immunosuppressive medications and patients undergoing chemotherapy for a leukemia or lymphoma. A recent report described trichodysplasia spinulosa-like hyperkeratosis in a patient with basal cell nevus syndrome treated with vismodegib70. Patients present with numerous erythematous to skin-colored papules with a central spiny projection on the face (especially the mid portion), ears, and less often extremities and trunk (see Fig. 130.8). Associated alopecia of the eyebrows and eyelashes, or less often other facial and body hair, as well as thickening of the skin resulting in a leonine appearance may develop. Histologic evaluation is characterized by dilated anagen follicles with abnormal maturation and eosinophilic keratinocytes containing large trichohyaline granules71. Large eosinophilic inclusions within affected keratinocytes show positive immunohistochemical staining for the polyomavirus middle T antigen, and electron microscopy demonstrates intranuclear icosahedral viral particles. The diagnosis can be confirmed by PCR-based viral detection in skin scrapings or a biopsy specimen. The condition may improve following reduction or discontinuation of immunosuppressive medications, and successful treatment with topical cidofovir, oral valganciclovir, and leflunomide has been described71a.

RABIES While rabies is not accompanied by a cutaneous eruption, dermatologists may be asked to perform a biopsy of nuchal skin that can be assayed for rabies virus antigen or (via PCR) rabies virus RNA.

KAWASAKI DISEASE Synonym:  ■ Mucocutaneous lymph node syndrome

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■ Fever, conjunctival injection, oral mucosal changes, acral swelling, and cervical lymphadenopathy ■ Polymorphous exanthem, often with early perineal involvement ■ Represents the most common cause of acquired heart disease in children in the US

Introduction and History Kawasaki disease (KD) is an acute febrile multisystem disease that primarily affects children under 5 years of age. Initially described by Kawasaki in Japanese children72, KD has subsequently been reported worldwide, and in the US it represents the leading cause of acquired heart disease in the pediatric population. Coronary artery aneurysms or ectasias develop in 15–25% of untreated KD patients, resulting in substantial morbidity and mortality. The clinical manifestations of KD can mimic a variety of other diseases, in particular viral exanthems, and the need to promptly treat KD in order to prevent potentially lifethreatening complications makes differentiation among these entities essential.

Epidemiology The peak incidence of KD is in children ≤2 years of age, and 85% of patients with KD are 80% of patients with KD. It is usually composed of macular and papular erythematous lesions, often in a morbilliform pattern, but may also be erythema multiforme-like (Fig. 81.15A), urticarial, scarlatiniform, or even pustular. Petechiae and crusting are unusual findings and vesiculobullous lesions are rarely if ever seen. In some patients, ulceration at the site of a bacillus Calmette– Guérin (BCG) vaccination has been observed during the disease course. A characteristic early cutaneous finding is erythema of the perineum, which often desquamates within 48 hours (Fig. 81.15A–C). Edema and brawny induration of the hands and feet are also common early in the disease course (Fig. 81.15D), with eventual desquamation that is prominent in the periungual regions. Gangrene of the peripheral extremities occasionally occurs. Transverse orange-brown (pseudo)chromonychia, thought to result from splinter hemorrhages within the nail bed, has also been described in the subacute phase of KD78a. The conjunctival injection of KD is typically bulbar with sparing of the limbus (an avascular zone around the iris); it is not associated with increased tearing or an exudate. Keratitis and photophobia are uncommon and should suggest an alternative diagnosis. Oropharyngeal changes consist of dry, fissured lips, a “strawberry tongue” (Fig. 81.16), and in some patients diffuse hyperemia of the oral mucous membranes. Cardiac involvement can include myocarditis, pericardial effusions, congestive heart failure, and coronary aneurysms; the latter represent the source of greatest morbidity in KD. Valvular disease, usually mitral or aortic, may also occur. Tachycardia, murmurs, gallops or distant heart sounds may be noted on cardiac examination. Other possible sites of involvement include the CNS (extreme irritability, aseptic meningitis, cranial nerve palsies, sensorineural hearing loss), gastrointestinal



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FACIAL FINDINGS IN KAWASAKI DISEASE, STAPHYLOCOCCAL SCALDED SKIN SYNDROME AND ERYTHEMA MULTIFORME MAJOR/STEVENS-JOHNSON SYNDROME Staphylococcal scalded skin syndrome

Kawasaki disease

Dilated conjunctival blood vessels

Diffuse erythema and desquamation (scale)

"Chapped" lips +/− fissures

Periorificial accentuation with radial scale-crusts

Unilateral lymphadenopathy

Erythema multiforme major/ Stevens–Johnson syndrome

Purulent discharge (if site of infection) Superficial erosions

Pink edematous papules and target lesions

Atypical targets and bullous lesions Conjunctivitis +/− erosions

Coalescing lesions with bulla formation

Erosions and hemorrhagic crusts

Fig. 81.16 Facial findings in Kawasaki disease, staphylococcal scalded skin syndrome and erythema multiforme major/Stevens–Johnson syndrome. Hemorrhagic crusting and erosions of the vermilion portion of the lips can also be seen in primary gingivostomatitis due to herpes simplex virus, pemphigus vulgaris, and paraneoplastic pemphigus. Histologic examination of the flaccid sterile bullae of staphylococcal scalded skin syndrome shows cleavage at or below the stratum granulosum (see inset).  

may also have utility as a diagnostic marker in young infants82. Macrophage activation syndrome is a rare complication of recalcitrant KD that presents with hepatosplenomegaly, cytopenias, hypofibrinogenemia, and marked hyperferritinemia83 (see Table 91.1). The differential diagnosis of KD includes viral exanthems (e.g. adenoviral, enteroviral, EBV, measles), scarlet fever, toxic shock syndrome, staphylococcal scalded skin syndrome, erythema multiforme, drug eruptions, serum sickness-like reaction, recurrent toxin-mediated perineal erythema, systemic juvenile idiopathic arthritis, annular erythema of infancy, infantile polyarthritis nodosa, and periodic fever syndromes. Fig. 81.16 shows the facial findings that differentiate KD from staphylococcal scalded skin syndrome and erythema multiforme major.

Pathology Histologic findings are nonspecific and include dermal edema and a perivascular mononuclear infiltrate73.

Treatment During its acute phase, the treatment for KD is aimed at decreasing inflammation, and the current first-line therapy is IVIg administered in a single infusion of 2 g/kg over 8–12 hours. This regimen was demonstrated to be more efficacious in preventing coronary aneurysms than the prior recommendation of multiple daily infusions84. However, the mechanism of action of IVIg in the treatment of KD is unknown. With the utilization of IVIg, the incidence of coronary aneurysms decreases from 25% to ≤5–10%, and mortality from 2% to 0.3%. Aspirin is also recommended during the acute phase, with initial administration of

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30–100 mg/kg daily (maximum 4 g/day) divided into four doses for 14 days or until afebrile for 48–72 hours, followed by a maintenance dosage of 3–5 mg/kg daily, usually for 6 to 8 weeks79. Approximately 10–20% of children with KD have persistent or recrudescent fevers after receiving a single dose of IVIg, and these individuals have a greater risk of coronary artery disease. A second dose of IVIg may be given to patients who fail to become afebrile within 24–48 hours after completion of the first dose. Management options for high-risk or refractory KD include corticosteroids and infliximab administered along with or following failure of IVIg therapy, respectively. One large randomized, double-blind trial found that initial treatment with pulsed corticosteroids plus conventional therapy (IVIg and aspirin) showed no benefit over conventional therapy alone in terms of hospital days, days of fever, rates of retreatment with IVIg, or adverse events85. However, another randomized controlled study found that the addition of pulsed corticosteroids to initial IVIg therapy in patients at high risk of having refractory KD was associated with fewer days of fever and a lower likelihood of coronary artery dilation86. Randomized controlled studies have shown that infliximab is well tolerated and equally or more effective than a second dose of IVIg in pediatric patients with IVIg-resistant KD87–89, although it did not decrease the likelihood of resistant disease when given as initial therapy together with IVIg and aspirin90. Long-term cardiac follow-up of KD patients is recommended, as adults with a history of KD may have vascular endothelial dysfunction and an increased risk for early-onset atherosclerosis. For additional online figures visit www.expertconsult.com

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C

B

A

E

D

F

eFig. 81.1 Hand-foot-and-mouth disease. A–D Coxsackievirus A6 infection presenting with multiple papulovesicles and crusts on the arm (A), on the knee (B), in the perioral area with accentuation in a scar on the chin (C), and in the groin (D). E Small lesions on the labial mucosa. F Erythematous macules and early vesicles on the palm. C, D, Courtesy, Julie V Schaffer, MD; E, Courtesy, Kalman Watsky, MD.  

eFig. 81.2 Papular-purpuric gloves and socks syndrome. Erythematous patches with petechiae on the plantar surface.  

eFig. 81.3 Orf. Vesiculopustule and ulceration on the  

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A

eFig. 81.4 Molluscum contagiosum. A Inflamed lesions with surrounding “molluscum dermatitis”. B Furunclelike presentation of an inflamed molluscum. A culture revealed only normal skin flora. Courtesy,  

Julie V Schaffer, MD.

B

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eFig. 81.5 Trichodysplasia spinulosa histology. Nucleated eosinophilic keratinocytes contain large trichohyaline granules. Courtesy, Boni Elewski, MD.  

eFig. 81.6 Pathogenesis of rabies. Reprinted from Cohen J,  

Powderly WG. Infectious Diseases, 2nd edn, 2004, Mosby, St Louis, with permission from Elsevier.

PATHOGENESIS OF RABIES INFECTION

Route of infection Broken skin Intact mucosa (respiratory tract) Corneal transplant

INCUBATION

Incubation period 20–90 days Salivary gland Centripetal retrograde axonal transport of virus to CNS

DISEASE Skin biopsy from hairy area of nape of neck Fluorescent antibody test Reverse transcription PCR

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Rabies encephalomyelitis Intracellular viral replication Inclusion (Negri) body formation Trans-synaptic spread Neurotransmitter functions altered Neuronal dysfunction

Clinical effects: behavioral changes, hydrophobia, paralysis, electroencephalographic changes

Centrifugal axonal transport Virus may replicate in muscle at bite site. Viral binding at nerve endings especially at motor end plates

Extracellular virus appears Virus produced in salivary glands Dissemination also to lungs, heart, adrenal and lacrimal glands, skin and skeletal muscle

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83. 84.

85.

86.

diagnostic marker of KD in infants younger than 3 months. Korean J Pediatr 2014;57:357–62. Wang W, Gong F, Zhu W, et al. Macrophage activation syndrome in Kawasaki disease: more common than we thought? Semin Arthr Rheum 2015;44:405–10. Newburger JW, Takahashi M, Beiser AS, et al. A single intravenous infusion of gamma globulin as compared with four infusions in the treatment of acute Kawasaki syndrome. N Engl J Med 1991;324:1633–9. Newburger JW, Sleeper LA, McCrindle BW, et al. Randomized trial of pulsed corticosteroid therapy for primary treatment of Kawasaki disease. N Engl J Med 2007;356:663–75. Ogata S, Ogihara Y, Honda T, et al. Corticosteroid pulse combination therapy for refractory Kawasaki disease: a randomized trial. Pediatrics 2012;129:e17–23.

87. Youn Y, Kim J, Hong YM, Sohn S. Infliximab as the first retreatment in patients with Kawasaki disease resistant to initial intravenous immunoglobulin. Pediatr Infect Dis J 2016;35:457–9. 88. Burns JC, Best BM, Mejias A, et al. Infliximab treatment of intravenous immunoglobulin-resistant Kawasaki disease. J Pediatr 2008;153:833–8. 89. Son MB, Gauvreau K, Burns JC, et al. Infliximab for intravenous immunoglobulin resistance in Kawasaki disease: a retrospective study. J Pediatr 2011;158:  644–9. 90. Tremoulet AH, Jain S, Jaggi P, et al. Infliximab for intensification of primary therapy for Kawasaki   disease: a phase 3 randomised, double-blind, placebo-controlled trial. Lancet 2014;383:  1731–8.

INFECTIONS, INFESTATIONS, AND BITES SECTION 12

Sexually Transmitted Infections Georg Stary and Angelika Stary

Chapter Contents Syphilis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1447

SEXUALLY TRANSMITTED AND TRANSMISSIBLE PATHOGENS Bacteria

Neisseria gonorrhoeae Treponema pallidum Haemophilus ducreyi Chlamydia trachomatis Mycoplasma hominis, M. genitalium Ureaplasma urealyticum Gardnerella vaginalis Atopobium vaginae Mobiluncus curtisii, M. mulieris Klebsiella (Calymmatobacterium) granulomatis Shigella spp. Campylobacter spp. Helicobacter cinaedi, H. fennelliae

Viruses

Human immunodeficiency virus, types 1 and 2 Herpes simplex virus, types 2 > 1 Human papillomavirus (several types) Hepatitis viruses, B > C and (via fecal–oral contact) A Cytomegalovirus Molluscum contagiosum virus Human T-cell leukemia/lymphotrophic virus, types I and II Human herpesvirus, type 8

Protozoa

Trichomonas vaginalis Entamoeba histolytica Giardia lamblia

Fungi

Candida albicans

Ectoparasites

Phthirus pubis Sarcoptes scabiei

Gonorrhea . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1459 Chancroid . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1463 Lymphogranuloma venereum . . . . . . . . . . . . . . . . . . . . . . 1466 Donovanosis (granuloma inguinale) . . . . . . . . . . . . . . . . . . 1467

INTRODUCTION The term “venereal diseases” was historically used to refer to infections that are sexually transmitted, i.e. syphilis, gonorrhea, chancroid, lymphogranuloma venereum, and granuloma inguinale. These disorders are now referred to as “sexually transmitted diseases” (STDs) or “sexually transmitted infections” (STIs), terms that directly reflect recognition that they are caused predominantly by sexual contact with an infected person. For infections caused by pathogens for which nonsexual routes of transmission predominate, e.g. yeasts or cytomegalovirus, the term “sexually transmissible infections” is used. Table 82.1 lists the names of commonly encountered sexually transmitted or transmissible pathogens.

SYPHILIS Synonym: 



Lues

82 

Table 82.1 Sexually transmitted and transmissible pathogens.  

Key features ■ Sexually acquired, chronic infection caused by Treponema pallidum and characterized by a variety of clinical manifestations and involvement of multiple organ systems ■ Can also be transmitted before birth (congenital) ■ Intermittently active disease with primary, secondary, and tertiary stages as well as a latent period of variable length that occurs before the onset of tertiary syphilis ■ Mucocutaneous manifestations vary from genital ulcers to widespread papulosquamous eruptions to granulomatous nodules ■ Syphilis facilitates the transmission of HIV, especially in countries with a high rate of both infections

History Syphilis has been of great historical importance and has played a major role in medicine for centuries. The disease was named after an afflicted shepherd named Syphilus in 1530. Theories on the origin of the disease in the late fifteenth century are controversial. One theory proposes that Christopher Columbus and his crew acquired the disease from Native Americans living in the Caribbean islands and brought it back to a nonimmune population in Europe in 1493, as signs of syphilis have been found in skeletons of pre-Columbian Native Americans1. Another theory is that venereal syphilis may have already been endemic but became more widespread and severe as a consequence of the wars at that time in Europe. Lastly, the environmental theory claims that

venereal syphilis is a variant of other diseases caused by Treponema spp. and became modified by environmental factors, especially temperature2,3. Information on the natural course of untreated syphilis (Fig. 82.1) has come primarily from two large studies. The Oslo Study4 was a prospective investigation of infected, but untreated, individuals conducted between 1890 and 1910, with a follow-up period of 50 years. Approximately one-quarter of infected persons had at least one additional relapse of secondary syphilis, often occurring during the first year (90%). Approximately 15% of infected persons developed benign late syphilis with gummas of the skin (70%), bones (10%), and mucous membranes (10%). Cardiovascular syphilis was reported in ~14% of men and 8% of women, while neurosyphilis was observed in 10% of men and 5% of women. Altogether, the study concluded that 17% of men and 8% of women died as a result of untreated syphilis. The Tuskegee Study was undertaken in 1932 in infected black men, with regular examinations for short- and long-term consequences of untreated infection. This represented a highly unethical investigation, as penicillin treatment was withheld without written consent. The principal finding was an increased mortality rate in the syphilitic group compared to the controls, with an ~20% loss-of-life expectancy at an interval of 12 years. Specific lesions of late syphilis were found in about 14% of infected men at the 20-year evaluation, and 12% after 30 years, with cardiovascular syphilis and neurosyphilis representing the primary causes of death5–7.

1447

Every day, more than 1 million people worldwide are newly infected with sexually transmitted infections (STIs), leading not just to an increase in morbidity and mortality, but also a higher risk of transmission of HIV. Existing prevention and management strategies have not reduced global incidence and prevalence, making STIs an ongoing public health problem. In addition, the increases in antibiotic resistance provide health professionals with new challenges. This chapter reviews important aspects of syphilis, gonorrhea, chancroid, lymphogranuloma venereum, and donovanosis (granuloma inguinale), including diagnostic tools, clinical manifestations, and treatment guidelines.

sexually transmitted infections sexually transmitted diseases STI STD syphilis lues gonorrhea GC chancroid lymphogranuloma venereum LGV donovanosis granuloma inguinale genital ulcer disease gonorrhea antibiotic resistance

CHAPTER

82 Sexually Transmitted Infections

ABSTRACT

non-print metadata KEYWORDS

1447.e1

SECTION

Infections, Infestations, and Bites

12

Epidemiology Syphilis is distributed worldwide and is particularly problematic in lowincome countries, where it is a leading cause of genital ulcer disease. Worldwide, the rates of primary and secondary syphilis decreased dramatically with the introduction of penicillin treatment after the Second World War. In contrast to Western European countries, an increase in the infection rate was observed during the late 1980s in rural southern and urban regions of the US. Although the number of syphilis cases per year in the US subsequently declined and in 2000 fell to its lowest point since reporting began in 1941, over the past 15 years the number of primary and secondary syphilis cases diagnosed per year in men has more than quintupled (Fig. 82.2). According to the Centers for Disease Control and Prevention (CDC), the incidence rate of primary and secondary syphilis in 2015 in the US was 13.7 cases per 100 000 population in men and 1.4 cases per 100 000 population in women. In the US, the incidence in black and Hispanic individuals is 2- to 5-fold higher than in other population groups, but the highest risk group is men who have sex with men (MSM) as they accounted for >60% of cases of primary and secondary syphilis in 20158.

With the resurgence of syphilis in Eastern Europe in the 1990s and migration of sex workers from this region to Western Europe, syphilis has also been observed more frequently in Western European countries over the past 15 years.

Biology of T. pallidum T. pallidum is a member of the genus Treponema of the order Spirochaetales, and it was identified in 1905 by Schaudinn and Hoffmann (Table 82.2)9. The characteristics of this microorganism are outlined in Table 82.3. Fig. 82.3 represents a darkfield photomicrograph of T. pallidum.

Pathogenesis of Untreated Syphilis Syphilis is a chronic systemic infection that progresses through active and latent stages (Fig. 82.4). Inoculation and penetration occurs via mucosal surfaces and abraded skin, followed by attachment to host cells and multiplication of the microorganism. Within a few hours, treponemes disseminate to the regional lymph nodes and internal organs10.

CLASSIFICATION OF TREPONEMA SPECIES

NATURAL HISTORY OF UNTREATED SYPHILIS

Order Spirochaetales   Genus Leptospira   Genus Borrelia   Genus Treponema

33%

Disease arrested by host Serum RPR becomes negative Disease does not progress during patient's lifetime Serum RPR remains positive

33%

Late (tertiary) syphilis

33%

Serum RPR variable, but usually positive

“Benign” tertiary syphilis (gummas of parenchymal 17% organs, bone or skin)

Cardiovascular syphilis

Distribution

Transmission

Venereal syphilis

Worldwide

Sexual; maternal–fetal

T. pallidum subsp. pertenue

Yaws

Tropics

Non-venereal (all ages)

T. pallidum subsp. endemicum

Endemic syphilis (Bejel)

Desert

Non-venereal (all ages)

T. carateum

Pinta

Tropics

Non-venereal (all ages)

T. denticola, T. socranskii

Periodontal disease

Worldwide

Non-venereal

Common features shared by all spirochetes within the genus Treponema:   morphology, antigenic properties, many DNA sequences, serologic detection, biochemical properties. Variable features for spirochetes within the genus Treponema:   transmission mode, geography, age of patients, appearance of clinical lesions.

8%

Neurosyphilis

Disease T. pallidum subsp. pallidum

8%

Fig. 82.1 Natural history of untreated syphilis. The data represent a composite of several studies. The specific antibody assays (e.g. MHA-TP) usually remain positive. RPR, rapid plasma reagin.  

Table 82.2 Classification of Treponema species.  

Fig. 82.2 Reported rates of primary and secondary syphilis in the US (by sex, 1990–2015). Note the elevated male : female ratio since 2000. Unfortunately, the use of pre-emptive antiretroviral therapy has been associated with a reduction in the use of condoms, including in men who have sex with men.  

REPORTED RATES OF PRIMARY AND SECONDARY SYPHILIS IN THE US (BY SEX, 1990–2015)

Rate (per 100 000 population)

25 20

From www.cdc.gov/std/.

15 10 5 0

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Male rate Female rate Total rate Male-to-female rate ratio

1990

1992

1994

1996

1998

2000

2002 Year

2004

2006

2008

2010

2012

2014

6–20 microns in length, 0.1–0.18 microns in diameter Regular tight spirals • Inability to survive outside an animal host • Cannot be cultured in vitro for an extended time period • Limited capacity for DNA repair • Outer membrane: - lipid-rich - contains uniform-sized transmembrane rare outer membrane proteins (TROMP) - lacks lipopolysaccharide • Periplasmic flagella • •

Table 82.3 Characteristic features of Treponema pallidum.  

The primary lesion develops 10–90 days after infection (median of 3 weeks) as an indolent papule, followed by surface necrosis and the typical well-circumscribed ulceration that is firm to palpation (chancre). It is accompanied by enlarged regional lymph nodes. Histopathologically, the microorganism is observed among cells typical of a Th1predominant cellular response; the latter leads to macrophage activation and destruction of a large number of treponemes. Several pathogenic mechanisms have been proposed, including an antigenically inert treponemal cell surface, resistance to phagocytosis, and premature downregulation of the local host immune response.

Secondary stage The secondary stage is characterized by dissemination and multiplication of the microorganism in different tissues, either simultaneously with or up to 6 months after healing of the primary local lesion. This stage follows primary syphilis in almost every patient who does not receive appropriate treatment. Circulating immune complexes (which contain treponemal outer membrane proteins), human anti-fibronectin antibodies, and complement are present during this stage of the disease and play a role in the pathogenesis of the different types of lesions11. Secondary syphilis is characterized by a broad spectrum of clinical manifestations involving the skin as well as systemic signs such as malaise, fever, and generalized lymphadenopathy. It lasts several weeks or months, with relapses in ~25% of patients. Pregnant women can infect a fetus via transplacental passage of the microorganism.

CHAPTER

82 Sexually Transmitted Infections

CHARACTERISTICS OF TREPONEMA PALLIDUM

Primary stage

Latency

Fig. 82.3 Positive darkfield examination. Treponemes are recognized by their characteristic corkscrew shape, and deliberate forward and backward movement with rotation about the longitudinal axis. From Morse SA, et al. Atlas of  

Sexually Transmitted Diseases and AIDS, 3rd edn. London: Mosby, 2003.

NATURAL HISTORY OF UNTREATED SYPHILIS

Inoculation 10–90 days incubation (average 3 weeks)

Primary syphilis Hematogeneous dissemination

3–10 weeks after appearance of chancre

Secondary syphilis After 3–12 weeks lesions disappear spontaneously

Up to 25% of patients relapse within the first 1–2 years

Latent syphilis 2–20 years

No recurrence (cure )

*

Tertiary syphilis

*

Fig. 82.4 Evolution of untreated syphilis. Or clinically asymptomatic. Adapted from Rein MF, Musher DM. Late syphilis. In: Rein MF (ed). Atlas of Infectious Diseases, Vol V: Sexually Transmitted Diseases. New York: Current Medicine, 1995:10.1–10.13.  



Latency is the period between healing of the clinical lesions and appearance of late manifestations, and it can last for many years. About 70% of untreated individuals will remain in this stage for the rest of their lives and are immune to new primary infection (see Fig. 82.1). Latent syphilis is divided into early (1 year or less) and late (more than 1 year) subsets, and it is characterized by positive serologic tests for specific antibodies (see below) without clinical signs or symptoms. Infectivity may occur intermittently due to the presence of treponemes in the bloodstream, and pregnant women with latent syphilis may infect the fetus in utero.

Tertiary stage The tertiary stage is also called late syphilis and is characterized by the presence of a small number of organisms and a high cellular immune reactivity against the organism. Signs of late syphilis can be recognized in approximately one-third of untreated individuals several months to years after being infected with treponemes (see Fig. 82.1). The microorganisms may invade the central nervous and cardiovascular systems as well as the skin (and other organs), leading to damage related to host delayed-type hypersensitivity responses, which produce local inflammation and gummas in affected tissues.

Syphilis and HIV Syphilis and other STIs that produce genital ulcers further increase the risk of acquiring HIV. Reasons for the increased risk of HIV transmission include: lack of an epithelial barrier due to ulceration of the skin or mucous membranes large numbers of macrophages and T cells with receptors for HIV production of cytokines by macrophages stimulated by treponemal lipoproteins. In addition, syphilitic manifestations are altered in HIV-positive patients12, with a higher likelihood of neurologic findings and (in those with secondary syphilis) ulcerative lesions.

• • •

Clinical Features Syphilis is usually sexually acquired, but maternal–fetal transmission also occurs and can result in congenital syphilis. Syphilis is an intermittent disease with primary, secondary, and tertiary stages as well as a latent period of variable length (divided into early and late subsets) that precedes the onset of tertiary syphilis (see Fig. 82.4)13. The definitions of early and late syphilis by the CDC and World Health Organization (WHO) differ slightly. Early syphilis includes the primary and secondary stages as well as early latency (CDC: acquired 2 years previously) through the tertiary stage.

Primary syphilis The chancre usually presents as a single, indolent, round or oval, indurated ulcer (Fig. 82.5) that is associated with regional adenopathy. Some patients report a preceding painless papule that enlarged and ulcerated a few days later. The time of onset ranges from 10 to 90 days (average

3 weeks) after T. pallidum exposure. Untreated, chancres heal within a few weeks (Fig. 82.6). Asymptomatic infections are common due to unrecognized chancres, especially when located in the cervical region in women; in these cases, syphilis is more frequently diagnosed during the secondary stage. The same applies to chancres located in the anal, perianal, or rectal areas (see Fig. 82.5C), seen more commonly in MSM. The mechanism of spontaneous healing without treatment is not well understood and seems to depend on local immunity.

C

B

A

Fig. 82.5 Chancres of primary syphilis. The lesions are firm to palpation and are occasionally multiple. Sites of chancres can include the penis (A, B), perianal area (C) and lip (D). Occasionally, other sites are affected, e.g. fingers.  

D

Fig. 82.6 Clinical manifestations of syphilis. L, lues; LI, primary syphilis; LII, secondary syphilis; LIII, tertiary syphilis. Adapted from Fritsch P, Zangerle R, Stary A. Venerologie. In:  

Cutaneous syphilitic gumma

Relapses

Localized papules

First skin eruption

Generalized lymphadenopathy

Regional lymphadenitis

Ulcers

Infection

CLINICAL MANIFESTATIONS OF SYPHILIS

LII Symptoms

LIII

LI Clinical horizon Latent syphilis 0

1450

1

2

3

4

5

6

7 8 9 10 11 12 13 14 15 16 Time (weeks)

1 Time (years)

2

Fritsch P (ed). Dermatologie und Venerologie. Berlin: Springer, 2004:865–86.

• •

Secondary syphilis The secondary stage of the disease results from the hematogenous and lymphatic dissemination of treponemes after a few weeks or months (3–10 weeks). It is characterized by recurrent disease activity, with mucocutaneous as well as systemic manifestations. Prodromal symptoms include low-grade fever, malaise, sore throat, adenopathy, weight loss, muscle aches, and sometimes a headache from meningeal irritation (Table 82.4). During the second stage of syphilis, the most commonly observed clinical presentation (80%) is a generalized, non-pruritic papulosquamous eruption (Fig. 82.7). Lesions can range from 1–2 mm to 15–20 mm in diameter, and they vary in color from pink to violaceous to red–brown. Mucosal lesions range from small, superficial ulcers that

CLINICAL FEATURES OF SECONDARY SYPHILIS Prodromal symptoms and signs: Weight loss Low-grade fever Malaise Headache (meningeal irritation) Sore throat Conjunctivitis (iridocyclitis) Arthralgia (periostitis) Myalgias Hepatosplenomegaly (mild hepatitis) • Generalized lymphadenopathy with indolent enlargement of lymph nodes (50–85%) • Skin manifestations: Early (10%): generalized eruption; non-pruritic, roseola-like, discrete macules, initially distributed on the flanks and shoulders Late (70%): generalized maculopapular and papulosquamous eruptions; more infiltrated lesions, often copper-colored; annular plaques on the face; corymbose arrangement (satellite papules around a larger central lesion); occurs in successive waves and is polymorphic Localized syphilids (specific infiltrations of treponemes; positive darkfield examination): - palms and soles: symmetric papules and plaques with a collarette of scale (collarette of Biett) - anogenital area: condylomata lata - seborrheic area: “corona veneris” along the hairline Hypopigmented macules, mainly on the neck (postinflammatory; “necklace of Venus”) • Manifestations involving mucous membranes (30%): Syphilitic perlèche, split papules Mucous patches: “plaques muqueuses” in the oropharynx (equivalent to condylomata lata in the genital area) Syphilitic sore throat: inflammation of the whole pharynx • Patchy alopecia (7%): “moth-eaten” localized areas of hair loss; toxic telogen effluvium •

Table 82.4 Clinical features of secondary syphilis.  

resemble painless aphthae to large gray plaques (Fig. 82.8A,B). Condylomata lata are often observed in the moist regions of the anogenital area due to local spreading of the microorganisms (Fig. 82.8C,D). Lymph node enlargement is present in the majority of patients. Focal neurologic findings occasionally occur. Additional clinical presentations of secondary syphilis include annular or figurate plaques with central hyperpigmentation on the face (Fig. 82.9A), non-scarring “moth-eaten” alopecia, split papules at the oral commissures (Fig. 82.9B), granulomatous nodules and plaques (Fig. 82.9C), and crusted necrotic lesions (Fig. 82.9D). Malignant syphilis (lues maligna) is extremely rare; the disseminated lesions resemble primary chancres (Fig. 82.9E). Without treatment, the lesions resolve over several weeks to months. Relapse occurs in ~20% of patients within 1 year, often with mucosal or mucocutaneous manifestations in the anogenital area. Laboratory diagnosis of secondary syphilis includes the following: Presence of treponemes by darkfield examination of serous exudates from localized lesions of the skin and mucous membranes (the exception being the oral cavity; see below). Serologic tests are more useful in secondary, as compared to primary, syphilis. Cardiolipin antibodies (e.g. RPR or VDRL tests) as well as specific antibodies are always positive in patients with secondary syphilis; a mistakenly or temporarily negative non-treponemal test rarely occurs due to the prozone phenomenon or HIV infection, respectively (see Table 82.8). Spirochetes can be detected by immunohistochemistry in the majority of biopsy specimens. Management considerations for patients diagnosed with secondary syphilis include the following: All patients should be tested for HIV infection, and testing should be repeated in those who fail to respond to treatment. Patients with ocular symptoms (e.g. photophobia, visual changes) should undergo ophthalmologic evaluation to assess for uveitis and neuroretinitis, including slit-lamp examination. A lumbar puncture and cerebrospinal fluid (CSF) analysis should be performed in patients with ocular or neurologic (e.g. headache, hearing loss, cranial neuropathies) signs/symptoms and when treatment failure is suspected (e.g. persistent/recurrent signs/ symptoms or failure of non-treponemal test titers to decline fourfold within 6–12 months). Patients with HIV are at increased risk for neurosyphilis, especially if they have a CD4 count 0.7 is indicative of IgG synthesis in the brain due to local inflammation. The intrathecal T. pallidum antibody index is calculated by dividing the TPHA titer in the CSF by the CSF to serum albumin ratio multiplied by a factor of 103, and an index >100 is indicative of the synthesis of treponemal-specific antibodies within the CNS. The presence of nonspecific antibodies, e.g. a positive VDRL test or RPR assay in CSF, is observed in most, but not all, cases, and a negative test does not exclude the presence of neurosyphilis.

Congenital syphilis Congenital syphilis was initially described in 1497 and is therefore the oldest recognized congenital infection. In 1906, it was demonstrated via the Wassermann test that transmission of syphilis to the fetus required an infection in the pregnant woman. There was an upsurge in congenital syphilis in Eastern Europe in the late 1990s, which paralleled the increased incidence of syphilis in adults and adolescents in this region. In the early 1990s, an increased frequency of congenital syphilis was also observed in some inner-city minority populations in the US15. In the US, there are currently ~12 cases of congenital syphilis per 100 000 live births. The risk of mother-

to-child transmission of untreated syphilis and its potential consequences are outlined in Table 82.6.

Early congenital syphilis

Infants generally present with symptoms during the neonatal period or within the first 3 months of life (Fig. 82.12). At the latest, they develop symptoms within the first 2 years of life. Typical manifestations are marasmic syphilis (i.e. cachexia) and skin lesions similar to those of acquired secondary syphilis (Fig. 82.13), except that they may be bullous (pemphigus syphiliticus) and tend to be more erosive. Additional clinical findings are “snuffles” (bloody or purulent mucinous nasal discharge), perioral and perianal fissures, lymphadenopathy, and hepatosplenomegaly. Skeletal involvement (i.e. osteochondritis) may result in pseudoparalysis of Parrot because of reduced movement of the extremities due to pain; other manifestations include anemia, thrombocytopenia, syphilitic pneumonitis (pneumonia alba), hepatitis, nephropathy, and congenital neurosyphilis.

Late congenital syphilis and stigmata

Late congenital syphilis in a child or adolescent corresponds to tertiary syphilis in an adult and is not infectious. The stigmata represent the delayed consequences of localized inflammation at the sites of treponemal infection (Table 82.7). In about one-third of children, an interstitial keratitis is seen; this finding together with typical dental abnormalities (Hutchinson teeth) and neural deafness forms the Hutchinson triad.

Laboratory diagnosis of congenital syphilis

A confirmed diagnosis of congenital syphilis requires laboratory demonstration of treponemes or child-specific antibodies. Serodiagnosis of congenital syphilis poses a difficult problem because IgG antibodies that are present may have been acquired transplacentally from the mother. A serum titer for a non-treponemal test that is fourfold higher than the mother’s titer is suggestive of infection, but infected neonates may have lower titers. The detection of chromatographically separated 19S-antibodies in the FTA-ABS-19S-IgM test has a sensitivity of about 90%, similar to the IgM-capture ELISA. More recently, it has been shown that the detection of spirochetemia by PCR can improve the sensitivity of the diagnosis of congenital syphilis in neonates. In late congenital syphilis, diagnosis is based on clinical findings in association with reactive serologic tests.

Laboratory Diagnosis of Syphilis The diagnosis of syphilis is based on the direct detection of treponemes or treponemal DNA by microscopy or molecular biologic techniques as well as various serologic tests that assess antibody responses to either cardiolipin (non-treponemal tests) or treponemal antigens (treponemal tests). Diagnosis of the different stages of syphilis depends on the interpretation of laboratory test results, the presence of clinical signs

1455

SECTION

Fig. 82.12 Time course for clinical manifestations of congenital syphilis. Adapted from Fritsch P, Zangerle R,  

CLINICAL MANIFESTATIONS OF CONGENITAL SYPHILIS

Early congenital syphilis

Stary A. Venerologie. In: Fritsch P (ed). Dermatologie und Venerologie. Berlin: Springer, 2004:865–86.

Be nig nl ate Ne syp uro hili syp s hili s

Relapse period

Symptoms

Infections, Infestations, and Bites

12

Clinical horizon

Spontaneous healing

Latent syphilis 0

1

2

3

4 5 Time (years)

6

10

20

Birth

STIGMATA OF CONGENITAL SYPHILIS

Cutaneous Rhagades – radial periorificial (mouth, nose, eyes, anus) scars at sites of previous fissures



Dental Hutchinson teeth – peg-shaped, notched permanent incisors* Mulberry molars – multiple rounded rudimentary cusps on the permanent first molars • Caries due to defective enamel • •

Skeletal Saddle nose – depression of the nasal root due to destruction of cartilage/bone • Frontal bossing of Parrot (“Olympian brow”) • Hypoplastic maxilla, relatively prominent mandible • High palatal arch ± perforation • Higouménakis’ sign – thickening of the medial clavicle • Scaphoid scapulae • Saber shins – anterior tibial bowing • Clutton’s joints – painless synovitis and effusions of the knees •

Other Fig. 82.13 Congenital syphilis. Red–brown plaques on the plantar surface.  

Eighth nerve deafness* Interstitial keratitis leading to corneal ulcers and opacities*

• •

*Components of Hutchinson triad. Table 82.7 Stigmata of congenital syphilis.  

and symptoms, and their history. All patients who have syphilis should also be tested for HIV infection.

Identification of T. pallidum The detection of the microorganism depends on microscopic examination and molecular assays, since T. pallidum cannot be routinely cultured in vitro. For propagation and experimental studies, growth in rabbit testicles is possible.

Microscopic examination

1456

Darkfield microscopy permits the definite diagnosis of syphilis by visual detection of motile spirochetes from lesions of the skin (see Fig. 82.3). It requires careful specimen collection, ideally consisting of serous fluid free of red blood cells. Identification is easy for an experienced microbiologist because of the typical episodic movements of the microorganism. Due to the presence of saprophytic spirochetes in the oral cavity, there is limited utility for darkfield examination of serous exudate from lesions in this site. Immunologic detection of the microorganism by the indirect fluorescent antibody test, which utilizes fluorescein-labeled anti-T. pallidum antibodies, is especially useful for oral lesions.

In the case of a negative result from microscopic examination, repeat testing is recommended. Serologic tests are also indicated.

Polymerase chain reaction-based assays PCR-based assays for detection of T. pallidum DNA are commercially available and may be useful in special circumstances, e.g. neurosyphilis, congenital syphilis, extragenital primary syphilis.

Serologic tests for syphilis Non-treponemal tests

The VDRL and RPR tests and related assays such as the unheated serum reagin (USR), reagin screen test (RST), and toluidine red unheated serum test (TRUST) detect antibodies to cardiolipin. The latter is a component of mammalian cells that is incorporated and modified by treponemes, which results in the development of host antibodies against it (comparable with autoantibodies directed against phospholipids; see Ch. 23). All these tests measure IgG and IgM antibodies



SPECIFIC AND NONSPECIFIC SEROLOGIC TESTS FOR SYPHILIS

Zangerle R, Stary A. Venerologie. In: Fritsch P (ed). Dermatologie und Venerologie. Berlin: Springer, 2004:865–86.

Specific IgG

Nonspecific IgM

CHAPTER

82 Sexually Transmitted Infections

Fig. 82.14 Specific and nonspecific serologic tests for syphilis. These curves represent untreated patients. Non-treponemal tests are nonspecific and treponemal tests are specific. Adapted from Fritsch P,

Specific IgM Nonspecific IgG 0 1 2 3 4 5 6 7 8 9 10 11 12 Time (weeks)

1 2 3 4 5 (years)

10

20

30

40

against this lipoprotein-like material released from damaged host cells and from treponemes. Titers of these antibodies correlate with disease activity and are useful in screening and monitoring treatment (Fig. 82.14). Qualitative non-treponemal tests are suitable for screening purposes, and reactive results have to be confirmed by antibody titer. The performance of a quantitative non-treponemal test is generally requested even with a positive darkfield examination, in order to provide a baseline for longitudinal evaluation after antibiotic therapy. A fourfold decrease in the antibody titer indicates successful treatment, while a fourfold increase indicates relapse or reinfection. In the case of early and efficacious treatment, non-treponemal assays usually become negative. Limitations of the tests are listed in Table 82.8.

LIMITATIONS OF NON-TREPONEMAL AND TREPONEMAL TESTS

Non-treponemal tests Lack of reactivity in early darkfield-positive primary syphilis Usually become negative with effective therapy (~15% of patients with early syphilis do not achieve a fourfold decline in titers 1 year after appropriate treatment, which is considered to represent a therapeutic failure) • False-negative results - Prozone phenomenon: inhibition of flocculation in the setting of high titers of antibodies; requires serum dilution - Temporary negative result: secondary syphilis in the setting of HIV infection; reactive on subsequent testing • Biologic false-positive results due to tissue damage - Pregnancy - Autoimmune diseases (e.g. lupus erythematosus) - Illicit drug abuse - Lymphomas - Infectious diseases (e.g. malaria) - Vaccinations - Hepatic cirrhosis - Antiphospholipid syndrome - Idiopathic, familial • False-positive: endemic treponematoses and borreliosis • •

Treponemal tests

The major indication for treponemal tests for syphilis is confirmation of reactive non-treponemal tests. IgM and IgG antibodies are usually detected in these assays by the end of the fourth week after infection. Accurate quantitative evaluation is not useful. The specific treponemal tests generally remain positive indefinitely, except in the case of treatment of very early syphilis where they do revert to negative. The specificity is very high and biologic false-positive reactions seldom occur. The sensitivity varies with the stage of syphilis: between 70% and 100% in primary syphilis, 100% in secondary and latent syphilis, and about 95% in late syphilis16. There is no differentiation between antibodies to T. pallidum and other treponemes and spirochetes. Specific assays include the following: TPHA, MHA-TP, T. pallidum particle agglutination test (TPPA): these assays measure antibodies directed against surface proteins of T. pallidum (sonicated fragments of treponemes) attached to rabbit erythrocytes as antigen carriers. Automatization is useful for large-scale testing and screening purposes. A positive result means that the patient had or still has active syphilis, but no assessment about the activity of the disease can be concluded from the qualitative result. Ninety percent of patients are positive at the time they seek medical care for a chancre. FTA-ABS assay: the serum reacts with the whole treponeme and forms antigen–antibody complexes visualized by fluoresceinisothiocyanate. To avoid nonspecific reactions with antibodies directed against saprophytic treponemes, a further step with Reiter treponemes is included to absorb nonspecific antibodies. The differentiation into IgM and IgG is possible by including selective anti-Ig antibodies. FTA-ABS-19S-IgM test: the isolated IgM antibody fraction is separately tested and provides a higher specificity than other tests. It is restricted to special situations, e.g. congenital

Treponemal tests Lack of reactivity in early darkfield-positive primary syphilis Remain positive indefinitely, so not useful for monitoring response to treatment • Biologic false-positive: autoimmune diseases, HIV infection, hypergammaglobulinemia • False-positive: endemic treponematoses and borreliosis • •







Table 82.8 Limitations of non-treponemal and treponemal tests.  



syphilis or the differentiation of relapsing syphilis from reinfection. Solid phase hemadsorption test (SPHA) or IgM ELISA: the SPHA test is used for the detection of specific IgM antibodies that attach to the solid phase of microtiter plates by reacting with the treponemal antigen on rabbit erythrocytes as antigen carriers. IgM antibodies can also be measured by the ELISA technology. These tests are useful for the diagnosis of congenital syphilis, neurosyphilis (positive, but low-titer), and reinfection.

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DIFFERENTIAL DIAGNOSES FOR SYPHILIS

Infections, Infestations, and Bites

Primary syphilis Other causes of genital ulcers should be considered: • Genital herpes • Genital trauma • Fixed drug eruption • Ulcerative genital carcinoma (e.g. squamous cell carcinoma) • Chancroid: jagged border, yellow exudate, painful • Lymphogranuloma venereum: transient, indurated, painless • Primary EBV infection • Behçet disease

Secondary syphilis Cutaneous: pityriasis rosea, guttate psoriasis, viral exanthems, lichen planus, pityriasis lichenoides chronica, primary HIV infection, drug eruption, nummular eczema, folliculitis • Mucous membranes: lichen planus; chronic aphthae; hand, foot and mouth disease; herpangina; perlèche • Condylomata lata: warts due to HPV, bowenoid papulosis, squamous cell carcinoma •

Tertiary syphilis

A

Cutaneous: lupus vulgaris, chromoblastomycosis, dimorphic fungal infections, leishmaniasis, lupus erythematosus, mycosis fungoides, sarcoidosis, tumors, venous ulcer



Table 82.9 Differential diagnoses for syphilis.  

Differential Diagnosis The differential diagnoses for the different stages of syphilis are listed in Table 82.9.

Treatment

B

Fig. 82.15 Histology of secondary syphilis. A Psoriasiform epidermal hyperplasia and a dense dermal infiltrate of plasma cells (see inset), lymphocytes, and histiocytes are observed. B Positive immunohistochemical staining with an anti-Treponema pallidum antibody; note the characteristic elongated, twisted shape of the spirochetes. Courtesy, Lorenzo Cerroni, MD.  

Pathology

1458

In primary syphilis, there is ulceration and a diffuse dermal infiltrate of plasma cells, lymphocytes, and histiocytes. Endothelial swelling is also present. Spirochetes may be detected with Warthin–Starry or immunohistochemical staining. In secondary syphilis, there is great variability in the histopathological pattern, reflecting the variable clinical appearance of the disease. The epidermis may be normal, psoriasiform, necrotic or ulcerated. Dermal infiltrates of plasma cells, lymphocytes and histiocytes can be perivascular, lichenoid, nodular, or diffuse (Fig. 82.15A). Older lesions of secondary syphilis may be granulomatous and can resemble sarcoidosis or other granulomatous dermatoses, except for the presence of plasma cells. Endothelial swelling and vascular proliferation can also be seen in secondary syphilis. By immunohistochemistry, spirochetes are identified in the majority of cases (Fig. 82.15B). Lues maligna is characterized by vasculitis. In tertiary syphilis, tuberculoid granulomas (with or without caseation) are present together with plasma cells. Endothelial swelling is evident, but organisms may be difficult to identify.

Penicillin G is still the treatment of choice for all stages of syphilis, and recommended regimens are listed in Table 82.10. A treponemicidal level of the antimicrobial should be achieved in the serum and (for patients with neurosyphilis) in the CSF. A penicillin level of >0.018 mg/L is considered treponemicidal, but the maximally effective in vitro concentration is considerably higher (0.36 mg/L)17,18. No tendency toward penicillin resistance has been detected in T. pallidum. Tetracyclines are used as second-line therapy if penicillin cannot be given; although a single 2 g dose of azithromycin can be effective19, treatment failures due to macrolide-resistant T. pallidum have been reported. Recommended treatment regimens in the settings of pregnancy and congenital syphilis are summarized in Table 82.11. Although HIV-infected patients are at increased risk for neurologic complications and may have higher rates of treatment failure, prevention of these outcomes by altered therapeutic regimens has not been demonstrated. The CDC and International Union Against Sexually Transmitted Infections (IUSTI) currently recommend that HIV-infected individuals receive the same syphilis regimens as HIV-negative patients. Treatment guidelines and additional information are provided by the CDC (www.cdc.gov/mmwr) and IUSTI (www.iusti.org)20. Of note, a Jarisch–Herxheimer reaction characterized by the acute onset of fever, headache, and myalgias can occur upon treatment of early syphilis. The IUSTI recommends that non-treponemal tests (e.g. VDRL, RPR) be performed 1, 2, 3, and 6 months following antibiotic treatment of early syphilis, then every 6 months for up to 2 years post treatment20; the CDC suggests clinical and serologic evaluation at 6 and 12 months for uncomplicated cases, with more frequent and extended evaluation (e.g. at 3, 6, 9, 12, 24 months) for HIV-infected patients. Evaluation of late syphilis at 6-month intervals for up to 3 years is recommended. In the setting of abnormal CSF findings, a CSF examination is recommended at 6-month intervals until cell counts are normal and the CSF-VDRL is negative. Evaluation of sexual partners and reporting are mandatory in many countries.

CHAPTER

TREATMENT RECOMMENDATIONS FOR SYPHILIS IN SPECIAL SITUATIONS

Early syphilis (primary, secondary, and early latent [acquired 1 year previously or of unknown duration), cardiovascular and gummatous syphilis; retreatment of primary, secondary or latent syphilis after failed initial treatment¶ Recommended: Benzathine penicillin, 2.4 million units* im weekly for three doses – or – • Procaine penicillin, 1.2 million units im daily for 20 days† •

Alternative regimens for penicillin-allergic patients‡: Doxycycline, 200 mg daily (100 mg po BID preferred over a single 200 mg dose) for 28 days – or – • Tetracycline, 500 mg po four times daily for 28 days •

Neurosyphilis and ocular syphilis Recommended: Aqueous penicillin G, 3–4 million units iv q4h (18–24 million units daily) for 10–14 days – or – • Procaine penicillin, 2.4 million units im daily plus probenecid, 500 mg po four times daily, both for 10–14 days •

Alternative regimens for penicillin-allergic patients: Ceftriaxone, 2 g im or iv daily for 10–14 days – or – Consider desensitization

Benzathine penicillin, 2.4 million units im weekly for two (early syphilis) or three (late syphilis) doses – or – • Procaine penicillin, regimen appropriate for the stage of syphilis (see Table 82.10) •

In the case of penicillin allergy: Desensitization to penicillin – or – Alternative regimens*: - Azithromycin, 500 mg daily for 10 days – or – - Ceftriaxone, 1 g im or iv daily for 10–14 days

• •

82 Sexually Transmitted Infections

TREATMENT RECOMMENDATIONS FOR SYPHILIS

Congenital Neonate with proven or highly probable disease or born to mother with untreated early syphilis†: Aqueous penicillin G, 50 000 U/kg iv q12h for the first 7 days of life, then q8h for 3 days (100 000–150 000 U/kg/day for a total of 10 days) – or – • Procaine penicillin, 50 000 U/kg im daily for 10–14 days •

Neonate with no signs of disease born to mother with treated syphilis‡: Benzathine penicillin, 50 000 U/kg im in a single dose



*Limited data; not recommended by the Centers for Disease Control (CDC) but included in

the World Health Organization (WHO) and European Branch of the International Union against Sexually Transmitted Infections (IUSTI) guidelines. †CSF analysis should be performed prior to therapy. ‡Neonate with a normal physical examination and serum non-treponemal antibody titer less than fourfold the maternal titer; treatment is optional if the mother was fully treated before pregnancy.

Table 82.11 Treatment recommendations for syphilis in special situations. h, hours; im, intramuscularly; iv, intravenously; q, every.  

• •

*† In children, 50 000 U/kg up to the adult dose.

Alternative treatment regimens in the World Health Organization (WHO) guidelines (http://apps.who.int/iris/bitstream/10665/249572/1/9789241549806-eng.pdf) and the guidelines of the International Union against Sexually Transmitted Infections (http://www.iusti.org/sti-information/guidelines/). ‡Limited data. §Resistance reported. ¶e.g. if RPR/VDRL titers fail to decrease fourfold or symptoms persist/progress; must first examine the CSF to exclude neurosyphilis.

Table 82.10 Treatment recommendations for syphilis. BID, twice daily; h, hours; im, intramuscularly; iv, intravenously; po, orally; q, every. Also see CDC guidelines (http://www.cdc.gov/std/tg2015/tg-2015-print.pdf ).  

GONORRHEA Synonyms:  ■ Gonorrhea: “clap” ■ Disseminated gonococcal infection: arthritis–dermatosis syndrome

Key features ■ Gonorrhea is the most common reportable STI in high-income countries ■ It is caused by Neisseria gonorrhoeae, which infects the mucosal surfaces of the human genital tract (as well as the anus, rectum and mouth) after direct – usually sexual – contact with an infected person ■ Cutaneous pustules as well as systemic symptoms such as arthritis and fever can result from hematogenous dissemination, which occurs in only a small percentage of infected individuals

■ Overall, the incidence of gonorrhea has declined during the past several decades, although there has been a recent increase in Eastern Europe ■ Over the past few decades, resistance of N. gonorrhoeae to various antimicrobials has increased in frequency

History Gonorrhea was mentioned in ancient literature from China, Egypt, the Roman Empire and Greece, as well as in the Old Testament21. Over the centuries, several names have been used to denote infection with N. gonorrhoeae, including: “strangury”, as used by Hippocrates; “clap”, derived from the district of prostitution called “Les Clapiers” in Paris; “gonorrhea”, chosen by Galen (130 AD) to describe the urethral exudate as a “flow of seed”; and “M. Neisser”, recognizing Albert Neisser, who discovered the microorganism in 1879 in stained smears from vaginal, urethral, and conjunctival exudates. Culture of N. gonorrhoeae was first described by Leistikow and Lüffler in 1882, and it was improved in 1964 by Thayer and Martin, who devised selective growth conditions on special agar plates22. Understanding the differences in the virulence of gonococci and studies of its molecular biology have led to greater insight into the pathology of the organism23. Treatment of gonococcal infections was problematic until sulfonamides were introduced in 1936 and penicillin in 1943. For decades, gonorrhea was easily treated with just a single dose of one antibiotic. However, over the past 25–30 years, an increase in antimicrobial resistance to penicillin and other antibiotics, such as tetracyclines and quinolones, has been observed and has become problematic. Recently, declining in vitro susceptibility to cefixime led to a change in treatment guidelines, such that dual therapy with ceftriaxone and azithromycin is the recommended therapeutic regimen for uncomplicated gonorrhea.

Epidemiology During the past century, the incidence of gonorrhea was influenced by politics, with peaks at the ends of the First and Second World Wars. A

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Infections, Infestations, and Bites

12

sudden decrease in reported cases occurred after the introduction of penicillin and other effective antimicrobials. Subsequently, the sexual freedom of the 1970s led again to an increase in the incidence of gonorrhea. However, with the advent of the AIDS epidemic, sexual practices again changed due to concerns regarding transmission of HIV, and this had a remarkable impact on the incidence of gonorrhea. Total gonorrhea rates in the US peaked in the mid 1970s and have remained relatively low and stable over the past 20 years. Political changes in Eastern Europe led to an increased rate of gonorrhea (as well as syphilis) in the 1990s, especially in prostitutes and those with sexual exposure to prostitutes. Migration of sex workers with a high infection rate also increased the number of reported cases of gonorrhea in other regions of Europe, especially in urban areas and high-risk groups, e.g. MSM. This probably reflects an increase in unsafe sexual behavior, particularly among young people and in high-risk populations. Similar to other venereal diseases, the incidence of gonorrhea varies with age and is highest in the 15- to 24-year-old age group, in which there is a higher rate in women than in men. In the US, AfricanAmericans have a 10-fold higher rate of gonococcal infections than whites. This may reflect different sexual behavior patterns and exposures as well as a better reporting system in public health institutions, which are more often utilized by African-Americans.

Transmission N. gonorrhoeae is a pathogen restricted to humans as its only host and transmitted primarily by sexual contact. The most efficient transmission occurs by vaginal or anal intercourse where there is physical contact with the mucosal surface of a sexual partner with an asymptomatic or mildly symptomatic infection. An exception is indirect contact among prepubescent girls sharing contaminated objects. There is no evidence that gonococci can be spread by air droplet transmission as occurs with meningococci. Vertical transmission can occur from an infected mother to the newborn during parturition, and this may lead to gonococcal conjunctivitis, pneumonia, or even vulvovaginal infection.

CLINICAL MANIFESTATIONS OF GONORRHEA

Disseminated infection Arthritis Fever • Tenosynovitis • Acral cutaneous pustules • Scalp abscesses (in neonates at sites of fetal scalp monitor electrodes) • Endocarditis • Meningitis • •

Direct mucosal infection Urethritis Cervicitis • Proctitis • Pharyngitis • Vulvovaginitis (children) • Ophthalmia neonatorum • •

Local extension Prostatitis Vesiculitis • Epididymitis • Salpingitis • Oophoritis • Pelvic inflammatory disease • •

Table 82.12 Clinical manifestations of gonorrhea.  

Fig. 82.16 Gonococcal urethritis with a purulent urethral discharge.  

Biology of N. gonorrhoeae Gonococci are Gram-negative diplococci that typically grow in pairs. They exhibit multiple colony types when grown on hemoglobincontaining media in a 3% CO2 atmosphere. The outer membrane structure of N. gonorrhoeae is typical for Gram-negative bacteria but, in contrast to N. meningitidis, it lacks the polysaccharide capsule that is responsible for the virulence of meningococci. Surface molecules on the outer membrane are involved in attachment, invasion and host injury, and they also represent important antigenic structures, especially the fibrillar pili (composed of 18 kDa pilin subunits)24. Gonococci require iron to grow, with sources including transferrin, lactoferrin, and hemoglobin; acquisition of iron is mediated by binding to host proteins via specific receptors. The microorganism cannot tolerate drying or low temperatures, and its growth is optimal at 35–37°C in a 5% CO2 atmosphere on a complex growth medium containing inorganic iron, glucose, vitamins, and cofactors as well as antibiotics.

Pathogenesis

1460

Although there is increasing knowledge about the pathogenicity of this microorganism, the exact molecular mechanisms of invasion of gonococci into the host cell are still unknown. Several virulence factors are involved in the processes of adherence, inflammation, and mucosal invasion25. Because pili increase adhesion to the host cell and allow movement, they also play an important role in pathogenesis; this may explain why non-piliated gonococci have a reduced ability to cause infections in humans. The adherence of gonococci to the human epithelial host cell and to neutrophils is dependent not just on the pili but also on Opa ligands. Anti-pilus antibodies have been shown to block epithelial adherence and increase phagocytic killing. Expression of the transferrin receptor and full-length lipo-oligosaccharide (LOS) appear to increase infectivity. Gonococci are able to multiply and divide intracellularly, where they are immune to host defense mechanisms. Cellular invasion is favored by expression of certain Opa proteins and non-sialylated LOS. Gonococci have the ability to cause tissue destruction by production of a variety of enzymes and lipids such as phospholipase, peptidases,

and lipid A. This plays a role in their damage of fallopian tubes and the development of postinflammatory arthritis.

Clinical Features Gonorrhea has a broad spectrum of clinical manifestations in both men and women, including asymptomatic infections, local symptomatic mucosal infections (with or without local complications), and systemic dissemination (Table 82.12). Symptoms vary according to the site of infection and strain of organism. The incubation period for gonorrhea is relatively short; it only takes 2–5 days until signs and symptoms of an infection with N. gonorrhoeae appear. Up to 10% of infected men and 50% of infected women lack clinical symptoms, which is especially common in rectal and pharyngeal infections26.

Gonococcal infection in men The most common clinical presentation of gonococcal infection in men is an acute anterior urethritis with dysuria and a urethral discharge that is typically purulent and profuse (Fig. 82.16). In about one-quarter of infected men, the urethral symptoms are less pronounced, similar to those of non-gonococcal urethritis, and appear only after urethral manipulation (“stripping”). Without treatment, clinical symptoms disappear in most patients after about 6 months. Local complications can include inflammation of the Cowper and Tyson glands and gonococcal pyoderma; ascension of the infection may lead to epididymitis, prostatitis, and vesiculitis. Patients with gonococcal epididymitis present with unilateral testicular pain and swelling accompanied by urethritis.

CHAPTER

Gonococcal infection in women

Extragenital gonorrhea Pharyngeal gonorrhea

This can occur in both men and women after oral sexual exposure. Because it is usually asymptomatic, the infection typically goes undetected and spontaneously resolves within a few weeks27. Pharyngeal gonorrhea may be an important source of urethral gonorrhea in MSM.

Rectal gonorrhea

Rectal gonorrhea is mainly seen in MSM and in heterosexual women who practice receptive anal intercourse. Rectal gonorrhea is asymptomatic in at least 50% of patients, but it may result in gonococcal proctitis that is accompanied by inflammation, rectal discharge, anal pruritus, bleeding, tenesmus, and constipation.

Gonococcal ophthalmia (including ophthalmia neonatorum)

Gonococcal ophthalmia is uncommon in adults but still represents a major cause of blindness in some low-income countries. Primarily due to self-inoculation and unusual sexual practices, it initially presents as purulent conjunctivitis and, if left untreated, can rapidly progress to severe keratitis followed by corneal opacification. Gonococcal infection in newborns is caused by inoculation with N. gonorrhoeae during delivery through an infected birth canal, and most often it presents with purulent conjunctivitis (ophthalmia neonatorum). Due to preventive application of antimicrobial ointment (usually erythromycin) immediately after birth, the rate of this gonococcal infection is currently low.

Disseminated gonococcal infection Arthritis–dermatosis syndrome (gonococcemia)

The most common clinical manifestation of gonococcal bacteremia is an acute arthritis–dermatosis syndrome, which occurs in ~0.5–1% of patients with mucosal gonorrhea28. Risk factors for disseminated gonococcal infection include: (1) menstruation, with the majority of cases in women developing during or immediately following menses; and (2) deficiencies in the late complement components C5–C9 (see Ch. 60). The classic syndrome consists of fever, joint pain, and a paucilesional eruption of hemorrhagic pustules. Gonococcal tenosynovitis affects primarily larger joints (e.g. knees, elbows, wrists, ankles) and is sometimes visible as erythema overlying the tendons. The cutaneous lesions consist of scattered pustules, often necrotic, due to an embolic septic vasculitis. They occur primarily on the distal portions of the extremities (Fig. 82.17) and contain gonococci. With a longer duration of symptoms, positive blood cultures become less common.

Laboratory Diagnosis Laboratory diagnosis is based on the identification of N. gonorrhoeae in secretions from infected mucous membranes by using stained smears, molecular biologic techniques, and/or bacterial culture (Fig. 82.18). Samples are typically obtained from the endocervical canal

82 Sexually Transmitted Infections

In about 50% of infected women, gonococcal infection is asymptomatic and therefore remains unnoticed. The primary site of gonococcal infection in women is the endocervical canal, with associated clinical symptoms consisting of increased vaginal discharge, dysuria, intermenstrual bleeding, and menorrhagia. Clinical inspection shows purulent cervical discharge with erythema and edema; swabbing of the endocervical canal results in a highly characteristic yellow color. Urethral colonization is present in 70–90% of infected women and is the usual site of infection in women who have had a hysterectomy. Occasionally, inflammation of Bartholin glands is observed, with acute swelling of the labial folds and appearance of purulent discharge when pressure is applied to the gland. The most common local complication in women is acute salpingitis or pelvic inflammatory disease (PID) due to ascension of the microorganisms. It occurs in ~10–20% of infected women (often developing immediately after a menstrual period) and may result in the long-term consequences of infertility, chronic pelvic pain, and ectopic pregnancy. The clinical manifestations of PID vary and include lower abdominal pain, adnexal tenderness, elevation of the ESR, leukocytosis, and fever. Gonorrheic perihepatitis (Fitz-Hugh–Curtis syndrome), with inflammation of the adjacent peritoneal area, is an infrequent complication in which symptoms of PID are accompanied by pain in the right upper quadrant that mimics acute cholecystitis.

Fig. 82.17 Gonococcemia (arthritis–dermatosis syndrome). Pustule with surrounding erythema on the toe.  

in women (after wiping off exudate), the urethra in men (and occasionally in women who have had a hysterectomy), and (when indicated) the posterior pharynx. For diagnosis by nucleic acid amplification methods (see below), a vaginal swab or urine sample can also be used. Anorectal specimens should be obtained via direct visualization using anoscopy if possible.

Staining methods Direct detection of Gram-negative diplococci within neutrophils in Gram- or methylene blue-stained smears provides an immediate diagnosis (Fig. 82.19), which is especially helpful in symptomatic individuals. Gram-stained urethral exudate detects between 95% and 98% of symptomatic infections in men, whereas Gram-stained cervical smears have a sensitivity of about 50%. The specificity of Gram-stained exudates depends primarily on the experience of the microscopist and on proper collection, and it may approach 100% in an optimal setting. However, because of its lower sensitivity in asymptomatic individuals, a negative Gram stain should not be considered sufficient for excluding infection in such patients. Smears are not helpful for detection of rectal and pharyngeal gonorrhea due to the presence of a large number of other bacteria.

Non-culture techniques for gonococcal diagnosis Molecular techniques for diagnosing gonococcal infections are widely employed and are advantageous over bacterial culture when specimen transport and storage are potential problems. The former are also more sensitive than culture for extragenital sites and when the infection is asymptomatic29. In addition, molecular tests can detect chlamydial infections without the need for an additional specimen (see Fig. 82.18). Their major disadvantage is the lack of antibiotic sensitivity testing. Therefore, if non-culture techniques are routinely used for diagnosing gonococcal infections, then culture-based regional monitoring of antibiotic susceptibilities is necessary.

Nucleic acid amplification techniques (NAATs)

With respect to overall sensitivity, specificity and ease of specimen transport, NAATs outperform other tests that are currently available for the diagnosis of infections due to Chlamydia trachomatis (CT) and N. gonorrhoeae (NG). NAATs used to detect gonococcal DNA or RNA, often in addition to chlamydial DNA or RNA, include: (1) PCR, e.g. cobas® 4800 CT/NG Test (Roche), RealTime CT/NG assay (Abbott); (2) transcription-mediated amplification, e.g. Aptima Combo 2® for CT/NG assay; and (3) strand displacement amplification, e.g. BD ProbeTecTM ET CT/GC. The Xpert® CT/NG test kit (Cepheid) is also based on NAAT technology; it can detect N. gonorrhoeae in 90 minutes and is able to co-amplify CT and NG. In addition to the advantages outlined above, the specimens can be obtained “non-invasively”, e.g. a urine sample, vaginal or introital swab30.

Non-amplified DNA hybridization

The non-amplified DNA probe test Gen-Probe PACE® 2 is based upon hybridization of gonococcal RNA and is still used in some parts of the world. It has a sensitivity and specificity comparable to that of bacterial culture and is not recommended for routine use.

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Fig. 82.18 Diagnostic algorithm for evaluation of urethral discharge or dysuria.  

DIAGNOSTIC ALGORITHM FOR EVALUATION OF URETHRAL DISCHARGE OR DYSURIA

Infections, Infestations, and Bites

12

Urethral discharge, dysuria

Physical examination

Gram stain

PMNs with diplococci

PMNs without diplococci

Diagnosis: Gonorrhea

Diagnosis: Gonorrhea? NGU?

Gonococcal culture Neisseria gonorrhoeae/Chlamydia molecular test

GC culture/test positive Chlamydia positive

GC culture/test negative Chlamydia positive

GC culture/test negative Chlamydia negative

Diagnosis: Co-infection with GC and Ct

Diagnosis: Chlamydia infection

Diagnosis: NGU?

Appropriate treatment Partner notification and treatment Confirm response to treatment

NGU: Non-gonococcal urethritis GC: Gonorrhea Ct: Chlamydia PMNs: Polymorphonuclear cells

1462

Repeat GC culture, N.gonorrhoeae/Chlamydia test

Positive result Appropriate treatment Confirm response to treatment

Culture techniques

Pathology

Isolation of N. gonorrhoeae by culture is still considered to be the gold standard for the diagnosis of gonococcal infections, and positive results obtained by stained smears should be confirmed by culture. Culture is currently the only acceptable method for cases of rape or other medico­legal situations, and it allows sensitivity testing. Pustular lesions due to gonococcemia should be punctured for culture. Depending on the symptomatic status of the infected person, currently available antibiotic-containing selective media (Thayer–Martin) or selective New York media have a sensitivity of 80–95% for genital samples directly plated at the time of collection. Sensitivity is much lower for extragenital specimens such as those from the rectal area ( 1

Primary syphilis

10–90 days, average 3 weeks

Non-purulent; usually single ulcer; indurated; relatively painless

Darkfield microscopy, serology, PCR

Treponema pallidum

Chancroid

3–10 days

Purulent; often multiple ulcers; soft, undermined edges; painful

Culture, PCR

Haemophilus ducreyi

LGV

3–12 days

Transient ulcer; indurated; painless

PCR, culture, serology

Chlamydia trachomatis serovars L1–3

Donovanosis

2–12 weeks

Chronic ulcer; indurated, beefy red, friable

Smears, histology

Klebsiella (Calymmatobacterium) granulomatis

Table 82.14 Infectious causes of genital ulcer disease. DFA, direct fluorescent antibody assay; LGV, lymphogranuloma venereum.  

is no evidence that women harbor the organism for a significantly long period of time without clinical findings.

Chancroid and HIV Chancroid and other diseases that produce genital ulcers are important risk factors for transmission of HIV. Men infected with HIV more often have had a history of genital ulcers compared with HIV-negative men37. The risk of acquiring HIV after having sexual contact with HIV-positive women was highest for uncircumcised men with genital ulcer disease compared with circumcised men with and without genital ulcer disease (29% versus 6% versus 2%). In women, the risk of becoming infected with HIV also increases with the number of episodes of genital ulcer disease. The presence of increased numbers of CD4+ lymphocytes and macrophages in ulcers due to infection with H. ducreyi provides an ideal opportunity for a latent HIV infection to become productive, with excretion of the virus into ulcer secretions. Genital lesions therefore become both a portal of viral entry for non-infected individuals and exit for HIV-infected persons38.

Biology of the Organism H. ducreyi is a Gram-negative, facultatively anaerobic bacillus of small size that shows a typical chaining pattern on Gram stain (Fig. 82.21). It does not share many similarities with other members of the genus Haemophilus.

Pathogenesis 1464

The penetration of the microorganism occurs via microscopic barrier defects in the epidermis. Signs of inflammation develop due to infiltration of lymphocytes, macrophages, and granulocytes in a primarily

Fig. 82.21 Gram-stained smear in chancroid. This smear of exudate from a genital ulcer shows the characteristic chaining pattern of Haemophilus ducreyi.  

Th1 cell-mediated immune response combined with pyogenic inflammation. Chancroid is associated with regional lymphadenitis due to the spread of the infection and resultant pyogenic inflammation.

Clinical Features The incubation period is 3–10 days; usually, the onset of clinical symptoms occurs between days 4 and 7. In men, the lesion starts with a papule surrounded by erythema and soon progresses to a pustule and then a painful ulcer. The latter typically has a purulent base and soft, undermined edges and is sharply demarcated (Fig. 82.22A,B). In about



A

CHAPTER

82 Sexually Transmitted Infections

Fig. 82.22 Chancroid. A Well-demarcated painful ulcers on the penis. B Multiple purulent ulcers with undermined borders. C Unilateral lymphadenitis with overlying erythema. B, Courtesy, Joyce Rico, MD.

B C

one-half of infected men, several ulcers develop due to apposition with the initial lesion, and they can coalesce to form giant ulcers. Most lesions are located on the internal or external surface of the prepuce, in the coronal sulcus (particularly in uncircumcised men), or around the frenulum. They are often accompanied by edema of the prepuce. Occasionally, a so-called “septic sore” can be observed on the shaft of the penis or prepuce, with pus trapped within the skin in the absence of an obvious ulcer. In this case, the pus that can be expressed is full of microorganisms33. In contrast to chlamydial infections, chancroid is symptomatic in almost all infected individuals. Co-infections with syphilis or herpes simplex virus (HSV) are possible. In Kenya, ~4% of men with genital ulcer disease have a co-infection with both T. pallidum and H. ducreyi (ulcus mixtum) and about the same percentage have HSV plus H. ducreyi, which makes etiologic diagnosis based on clinical findings impossible. In women, the majority of lesions are within the introital area; they may also occur on the cervix or vaginal wall, or in the perianal area, but rarely occur in an extragenital location. Lesions in women are sometimes only mildly symptomatic and are more often multiple. In both men and women, painful inguinal lymphadenitis may accompany the genital lesions. It is more often observed in men (about 40% of patients) and is usually unilateral (Fig. 82.22C). Inguinal buboes may rupture and lead to inguinal ulceration.

Pathology Biopsies of chancroid classically have three zones of inflammation beneath the ulcers. The first zone has necrotic debris, fibrin, and neutrophils. The middle zone is an area of granulation tissue, and the deepest zone contains lymphocytes and plasma cells. Gram-negative coccobacilli are only rarely found with tissue Gram or Giemsa stains and are best seen with smears.

Diagnosis Material is usually obtained with a cotton swab, on which the organism can only survive for a few hours without being refrigerated at 4°C. Gram stain of H. ducreyi in a smear of the exudate shows a “school-of-fish” or “railroad track” pattern of small Gram-negative bacilli (see Fig. 82.21). The finding is not specific because other bacteria may have a similar arrangement, and it is insensitive because the responsible bacteria are only seen in about a third to a half of infected persons.

TREATMENT REGIMENS FOR CHANCROID Azithromycin, 1 g po, single dose – or – Ceftriaxone, 250 mg im, single dose – or – • Ciprofloxacin, 500 mg po twice daily for 3 days ,† – or – * • Erythromycin base, 500 mg po four times daily for 7 days† • •

*† Contraindicated for pregnant or lactating women. Worldwide, isolates with intermediate resistance.

Table 82.15 Treatment regimens for chancroid. im, intramuscularly; po, orally.  

Accurate diagnosis of chancroid requires isolation of H. ducreyi on special culture media; small, non-mucoid semiopaque or translucent colonies appear after 24–72 hours if grown at 33–35°C in a 5–10% CO2 atmosphere. Further identification methods are needed, such as the porphyrin test, to prove the requirement of hemin (factor X) for growth. There are variations in media (which are not widely available from commercial sources) and the sensitivity of culture is between 60% and 80%, depending on the quality and handling of the specimen, culture conditions, and laboratory experience. If culture is not possible or is inconclusive, diagnosis can be based on the clinical picture and the exclusion of other microorganisms that cause genital ulcer disease, such as syphilis or genital herpes, as well as on the epidemiologic data and response to therapy. A genital ulcer disease panel that can detect HSV-1, HSV-2, T. pallidum, and H. ducreyi via real-time PCR is commercially available in some countries39. Other diagnostic procedures, such as antigen detection methods or serologic tests, are still under development and cannot yet be recommended for routine diagnosis.

Differential Diagnosis Other infections that cause genital ulcers have to be considered (see Table 82.14), as well as trauma, a fixed drug eruption, and, occasionally, carcinoma.

Treatment Successful treatment can be achieved using several antimicrobial drugs (Table 82.15); ulcers improve within 3 days and typically heal in 14 days or less, depending on the initial lesions. The different treatment

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regimens cure about 95% of infected individuals, with azithromycin and ceftriaxone requiring only a single dose. Ciprofloxacin is contra­ indicated in pregnant and lactating women. In patients with HIV infection, the treatment recommendations are the same, but with a longer treatment course; close monitoring may be necessary because of delayed healing and possible treatment failures. Sexual partners from the 10 days preceding the onset of symptoms should be examined and treatment offered regardless of whether the microorganism can be cultured or clinical symptoms are present.

LYMPHOGRANULOMA VENEREUM Synonyms:  ■ Durand–Nicolas–Favre disease ■ Climatic bubo ■

Strumous bubo ■ Poradenitis inguinale ■ Lymphogranuloma inguinale

CLINICAL MANIFESTATIONS OF LYMPHOGRANULOMA VENEREUM

Initial manifestations: 3–12 days Papule Erosion or ulcer • Herpetiform vesicle • Nonspecific urethritis or cervicitis • •

Inguinal syndrome: 10–30 days up to 6 months Regional lymphadenopathy (mostly inguinal and femoral; also perirectal, deep iliac) • Overlying erythema • Constitutional symptoms • Eruption of buboes • Pelvic inflammatory disease (PID), back pain •

Ano-genito-rectal syndrome: months to years Proctocolitis Hyperplasia of intestinal and perirectal lymphatic tissue • Perirectal abscesses • Ischiorectal and rectovaginal fistulas • Anal fistulas • Rectal strictures and stenoses •

Key features ■ Lymphogranuloma venereum (LGV) is a rare STI caused by Chlamydia trachomatis serovars L1–3 ■ LGV is endemic in some areas of Africa, Asia and South America and is observed sporadically in other parts of the world ■ The disease progresses through three stages: (1) initial infection of the genital mucosa; (2) inguinal lymphadenopathy that is usually unilateral; and (3) a firm mass and bubo with spontaneous drainage and involution, often accompanied by proctocolitis and involvement of perirectal or perianal lymphatic tissue



Other manifestations Urethro-genito-perineal syndrome Peno-scrotal elephantiasis • Erythema nodosum • Submaxillary or cervical lymphadenopathy associated with oropharyngeal lesions • •

Table 82.16 Clinical manifestations of lymphogranuloma venereum.  

History Lymphogranuloma venereum (LGV) has been confused with other diseases that cause lymphadenopathy, especially syphilis, genital herpes, and chancroid. A major diagnostic advantage arose with the introduction of the Frei test, a specific skin test established in 192540. The first isolation of Chlamydia was reported in 1930, enabled by intracerebral inoculation of monkeys, followed in 1935 by cultivation in fertilized eggs41.

Epidemiology LGV is endemic in East and West Africa, Southeast Asia, India, South America, and the Caribbean basin; it occurs sporadically throughout the rest of the world. In some countries, it is a reportable disease. LGV classically affects sailors, soldiers, and travelers who acquire the disease in endemic regions. Data on the prevalence of LGV have often been based on the results of serologic tests and the Frei skin test, both of which are nonspecific and have cross-reactivity with other genito-ocular chlamydial infections. LGV is reported more often in men than in women and the peak age correlates with the period of maximum sexual activity. However, the frequency of infection following sexual intercourse has not been well investigated. Since 2003, a series of outbreaks of LGV have been reported in Western Europe and the US42. The affected individuals were primarily MSM who lived in large cities43, many of whom had concurrent HIV infection and ulcerative proctitis44.

Pathogenesis

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Caused by specific Chlamydia trachomatis serovars (L1–3), LGV affects mainly the lymphatic tissue in the genitorectal area. The organisms enter the body via microscopic defects in the mucosa or the skin. The microorganisms then enter the lymphatics, leading to lymphangitis, perilymphangitis, and infection of lymph nodes. Over a period of many weeks to months, the inflammatory process expands and results in periadenitis, involvement of a few neighboring lymph nodes, the development of abscesses (which can rupture), and the formation of fistulas and strictures. In the rectum, destruction and ulceration of the mucosa may occur. Local progression and systemic dissemination are both influenced by host immunity. Latent persistence of the microorganism within involved tissues may last for many years.

Clinical Features The clinical manifestations of LGV can be separated into primary lesions, inguinal and ano-genito-rectal syndromes, and other manifestations (Table 82.16). The initial clinical presentations vary, appearing after an incubation period of 3–12 days (see Table 82.16). In up to half of infected individuals, a herpetiform lesion develops at the site of exposure and heals rapidly without a scar. This transient lesion is most often located on the coronal sulcus in men and on the posterior vaginal wall in women, and it is usually accompanied by local lymphangitis. Cervicitis and urethritis are mild and often remain unrecognized. Rectal exposure might result in proctocolitis associated with rectal discharge, anal pain, and tenesmus. Co-infection with other pathogens can sometimes be observed. The secondary stage is characterized by the inguinal syndrome, in which unilateral lymphadenopathy (depending on the site of the primary infection) is accompanied by overlying erythema. The bubo is initially firm and then undergoes rapid enlargement, becoming more painful. Eventually the overlying skin develops a bluish discoloration and the bubo finally ruptures through the skin; pus may drain through numerous sinus tracts (Fig. 82.23), followed by healing. If untreated, relapses occur in about 20% of patients. Constitutional symptoms such as meningeal irritation, hepatitis, and arthritis are rare and may occur due to systemic spread of the organism. Inguinal adenopathy is only observed in about one-third of infected women; proctitis and pain in the lower abdomen may be the only symptoms. The manifestations of the ano-genito-rectal syndrome include proctocolitis and hyperplasia of the intestinal and perirectal lymphatic tissue. This leads to late manifestations dominated by local abscesses with anal fistulas as well as rectal strictures and stenoses45. Additional manifestations include urinary incontinence because of papillary growth of the mucosa of the urethral meatus in women. Extragenital lesions in the oropharynx, due to infection from oral sexual contact, are difficult to diagnose.

Pathology Histologically, the skin may be ulcerated. A diffuse mixed infiltrate of neutrophils, histiocytes, plasma cells, and sometimes multinucleated giant cells is seen in the dermis. Although abscesses may occur in the

DONOVANOSIS (GRANULOMA INGUINALE) Synonyms:  ■ Granuloma venereum ■ Granuloma inguinale tropicum Granuloma venereum genitoinguinale ■ Granuloma genitoinguinale Ulcerating sclerosing granuloma ■ Ulcerating granuloma of the pudendum ■ Serpiginous ulceration of the groin ■ Lupoid form of groin ulceration ■ ■

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82 Sexually Transmitted Infections

positive individuals may need prolonged treatment due to delayed resolution of symptoms.

Key features

Fig. 82.23 Lymphogranuloma venereum. Inguinal bubo that has ruptured and drained.  

TREATMENT REGIMENS FOR LYMPHOGRANULOMA VENEREUM Recommended: doxycycline, 100 mg po twice daily • Alternative and in case of pregnancy: erythromycin base, 500 mg po four times daily •

Duration for both regimens: at least 3 weeks

Table 82.17 Treatment regimens for lymphogranuloma venereum. po, orally.  

skin, characteristic stellate abscesses are usually only observed in the lymph nodes. Organisms are rarely demonstrated within histiocytes (Gamna–Favre bodies) by Giemsa stain. An anti-C. trachomatis antibody has been used successfully to demonstrate microorganisms in skin biopsies.

Diagnosis The diagnosis of LGV is based primarily on the detection of Chlamydiaspecific DNA in lesional tissue by PCR or other nucleic acid amplification assays. This method is diagnostically more sensitive than is isolation of the organism via tissue culture. Typically, rectal specimens are tested for the presence of C. trachomatis and, if positive, are then genotyped in order to diagnose LGV. Serology testing is only recommended if it is performed in conjunction with DNA detection. In serologic assays, such as the complement fixation test or other assays that detect specific antibodies to the serovars L1–3 of C. trachomatis, the titer of antibodies is high. A differentiation of antibodies to L1–3 from those to other serovars is difficult but possible in the micro­ immunofluorescence test. A disadvantage of this diagnostic procedure is the lack of commercial availability.

Differential Diagnosis Other causes of lymphadenopathy in the genital region (e.g. chancroid, lymphoma, cat scratch disease) or of genital ulcers or erosions should be excluded by additional diagnostic procedures (see Table 82.14). Pyogenic and mycobacterial infections also need to be considered, as well as Crohn disease, especially in the case of the ano-genital-rectal syndrome. Routine syphilis and HIV serologies are recommended and should be repeated after 3–6 months.

Treatment Doxycycline is the treatment of choice, followed by macrolides (Table 82.17). Antibiotic treatment can cure the infection, but surgical intervention may be required in the case of large buboes. Examination and treatment of sexual partners is required if contact occurred during the 30 days preceding the onset of symptoms. HIV-

■ Donovanosis is a rare, chronic, progressive ulcerative bacterial infection with Klebsiella granulomatis (previously known as Calymmatobacterium granulomatis), a Gram-negative bacillus ■ Ulcers occur primarily in the genital region ■ The responsible microorganisms are found within macrophages in smears or biopsy specimens (Donovan bodies)

History The disease was initially described in India as ulcerations followed by elephantiasis of the genitalia. The microorganism was first identified in 1905 by Donovan, who noted the characteristic Donovan bodies in macrophages and epithelial cells of the stratum malpighii46. In 1950, Marmell and Santora proposed the name “donovanosis”47. Limited success in culturing the organism until the 1990s explains the slow progress in donovanosis research48.

Epidemiology In the pre-antibiotic era, donovanosis was distributed in both hemispheres, but now it is restricted primarily to a few low-income countries. A large number of cases, the majority in the 20- to 40-year-old age group, are reported from South Africa, India, Papua New Guinea, and some parts of Australia (Fig. 82.24). Although donovanosis is listed among the group of STIs, the disease can also occur in individuals who are not sexually active, and a wide variation in the prevalence of the infection (from 0.4% to 52%) is reported in sexual partners49. This is probably due to different diagnostic procedures and a long incubation period of up to 1 year. It is also not clear whether fecal contamination represents a route of non-sexual transmission.

Pathogenesis Donovanosis is caused by Klebsiella granulomatis (previously known as Calymmatobacterium granulomatis), an intracellular Gram-negative bacillus. The primary lesion is a small cutaneous papule or nodule that contains mononuclear cells with cytoplasmic vacuoles that are filled with microorganisms. The cytoplasmic vacuoles can rupture and release bipolar Donovan bodies50 of coccoid, coccobacillary, and bacillary morphology.

Clinical Features The average incubation period is thought to be ~17 days, but a range from 1 day to 1 year has been reported. A small papule or nodule initially appears and eventually ulcerates. The lesions of donovanosis are usually painless or mildly painful and slowly expand over a period of weeks to months. They are often highly vascular, with a beefy red appearance and a tendency to bleed (Fig. 82.25). Extensive tissue destruction may result, and a foul-smelling exudate is characteristic of necrotic donovanosis. Inguinal lesions occur in up to 20% of patients and are often combined with genital involvement. The most frequent sites of lesions in men are the prepuce, glans penis, frenulum, and coronal sulcus. In women, the most common location is the vulvar area, where large ulcers as well as granulomatous or verrucous papules may be observed.

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Fig. 82.24 Worldwide distribution of donovanosis.  

Infections, Infestations, and Bites

WORLDWIDE DISTRIBUTION OF DONOVANOSIS

Uncommonly affected areas

More commonly affected areas

TREATMENT REGIMENS FOR DONOVANOSIS

Recommended: Azithromycin, 1 g po once weekly – or – 500 mg po daily



Alternative: Doxycycline, 100 mg po BID – or – Trimethoprim–sulfamethoxazole, 1 double-strength (160 mg/800 mg) tablet po BID – or – • Ciprofloxacin, 750 mg po BID – or – • Erythromycin base, 500 mg po four times daily • •

Duration for all regimens: until all lesions completely healed (at least 3 weeks)

Table 82.18 Treatment regimens for donovanosis. For any of the regimens, the addition of an aminoglycoside (e.g. gentamicin 1 mg/kg iv q8h) should be considered if lesions do not respond within the first few days of therapy. BID, twice daily; po, orally.  

Fig. 82.25 Donovanosis (granuloma inguinale). Large ulcers with a characteristic “beefy” appearance. Courtesy, Joyce Rico, MD.  

Extragenital lesions due to autoinoculation or secondary to dissemination have been observed in the skin, bones, abdominal cavity, and oral cavity; they can involve any organ, with the bones most commonly affected. In some patients, primary extragenital lesions are seen.

Pathology Histologically, ulceration with exuberant granulation tissue is evident. Pseudoepitheliomatous hyperplasia may be present at the ulcer edge. A diffuse infiltrate of histiocytes, plasma cells, and a few lymphocytes is present in the dermis, sometimes with small neutrophilic abscesses. The organisms are easier to find in smears than in histologic sections. They are 1–2 microns in diameter and are within histiocytes, as is also characteristic of leishmaniasis, rhinoscleroma, and histoplasmosis (see Table 77.18). Bipolar staining is found at two ends of the organisms (Donovan bodies), giving them a “safety pin” appearance.

Diagnosis

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The diagnosis of donovanosis is usually based on the demonstration of Donovan bodies in smears from active lesions by Giemsa, Wright, or Leishman stains. The smears are prepared from tissue scrapings or touch preparations of biopsies taken from the dermis or subcutis of lesions. There are no serologic tests available for the diagnosis of donovanosis. Nucleic acid amplification assays such as PCR are under investigation, but they are not yet commercially available. Although successful

culture of K. granulomatis has been reported in human peripheral blood mononuclear cells and Hep2 cells, attempts to grow this organism in fertilized eggs or on routinely available artificial media have been unsuccessful.

Differential Diagnosis Donovanosis is frequently confused with other diseases of the anogenital region. Other infectious causes of genital ulcer disease have to be considered (see Table 82.14); early lesions of secondary syphilis, especially condylomata lata, often have a clinical appearance similar to donovanosis. Carcinoma, amebiasis, tuberculosis, dimorphic fungal infections, pyoderma vegetans, Crohn disease, and pyoderma gangrenosum may represent additional diagnostic possibilities.

Treatment The recommended treatment is azithromycin, but treatment regimens in different geographic areas reflect the availability of antibiotics; for example, in Papua New Guinea, chloramphenicol is used. Doxycycline, trimethoprim–sulfamethoxazole, quinolones, and erythromycin (recommended during pregnancy) have also been shown to be effective in the treatment of donovanosis (Table 82.18). For azithromycin, successful treatment with a daily dose of 500 mg for 1 week has been reported51. However, the CDC 2015 guidelines recommend 1 g weekly or 500 mg daily for at least 3 weeks and until all lesions have completely healed. Examination of sexual partners is recommended if there has been sexual contact during the previous 60 days or if the partner is symptomatic. Relapses can occur 6–18 months later, despite effective initial treatment.

CHAPTER

1. Rosahn PD. Autopsy studies in syphilis. J Vener Dis 1947;649(Information Suppl.# 21):US Public Health Service, Venereal Disease Division, Washington DC, 1–67. 2. Hollander DH. Treponematosis from pinta to venereal syphilis revisited: hypothesis from temperature determination of disease patterns. Sex Transm Dis 1981;8:34–7. 3. Fieldsteel AH. Genetics of treponema. In: Schell RF, Musher DM, editors. Pathogenesis and immunology of treponemal infection. New York: Marcel Dekker; 1983. p. 39–55. 4. Gjestland T. The Oslo study of untreated syphilis: an epidemiologic investigation of the natural course of syphilis infection based on a restudy of the BoeckBruusgaard material. Acta Derm Venereol Suppl (Stockh) 1955;35(Suppl. 34):3–368. Annex I-LVI. 5. Olansky S, Schuman SH, Peters JJ, et al. Untreated syphilis in the male Negro: X. Twenty years of clinical observation of untreated syphilitic and presumably non-syphilitic groups. J Chronic Dis 1956;4:177–85. 6. Heller JR Jr, Bruyere PT. Untreated syphilis in the male Negro: II. Mortality during 12 years of observation. J Vener Dis Inf 1946;27:34–8. 7. Rockwell DH, Yobs AR, Moore MB Jr. The Tuskegee study of untreated syphilis. Arch Intern Med 1964;114:792–8. 8. Centers for Disease Control and Prevention (CDC). Sexually transmitted diseases (STDs). www.cdc.gov/ std/. 9. Smibert RM, Genus III. Treponema Schaudinn 1905, 1728. In: Krieg NR, Holt JG, editors. Bergey’s manual of systematic bacteriology, vol. 1. Baltimore: Williams; 1984. p. 49–57. 10. Lukehart SA, et al. Biology of Treponemes. In: Holmes KK, Sparling PF, Stamm WE, editors. Sexually transmitted diseases. New York: McGraw-Hill; 2008. p. 647–59. 11. Baughn RE, McNeely MC, Jorizzo JL, Musher DM. Characterization of the antigenic determinants and host components in immune complexes from patients with secondary syphilis. J Immunol 1986;136:1406–14. 12. Marra CM. Syphilis and human immunodeficiency virus infection. Semin Neurol 1992;12:43–50. 13. Sparling PF. Clinical manifestations of syphilis. In: Holmes KK, Sparling PF, Stamm WE, et al., editors. Sexually transmitted diseases. New York: McGraw-Hill; 2008. p. 661–84. 14. Merritt HH, Adams RD, Solomon HC. Neurosyphilis. New York: Oxford University Press; 1946. 15. Shafii T, Radolf JD, Sanchez PJ, et al. Congenital syphilis. In: Holmes KK, Sparling PF, Stamm WE, et al., editors. Sexually transmitted diseases. New York: McGraw-Hill; 2008. p. 1577–612. 16. Larsen SA, Steiner BM, Rudolph AH. Laboratory diagnosis and interpretation of tests for syphilis. Clin Microbiol Rev 1995;8:1–21. 17. Rolfs RT. Treatment of syphilis 1993. Clin Infect Dis 1995;29(Suppl.):S23–38. 18. van Voorst Vader PC. Syphilis management and treatment. Dermatol Clin 1998;16:699–711.

19. Riedner G, Rusizoka MJ, Todd J, et al. Single-dose azithromycin versus penicillin G benzathine for the treatment of early syphilis. N Engl J Med 2005;353:1236–44. 20. French P, Gomberg M, Janier M, et al. 2008 European guidelines on the management of syphilis. Int J STD AIDS 2009;20:300–9. 21. Morton RS. Gonorrhea. In: Rook A, editor. Major problems in dermatology, vol. 9. London: WB Saunders; 1977. 22. Thayer JD, Martin JE. Selective medium for the cultivation of N. gonorrhoeae and N. meningitidis. Public Health Rep 1964;79:49–57. 23. Kellogg DS Jr, Peacock WL Jr, Deacon WE, et al. Neisseria gonorrhoeae: 1. Virulence genetically linked to clonal variation. J Bacteriol 1963;85:1274–9. 24. Parge HE, Forest KT, Hickey MJ, et al. Structure of the fibre-forming protein pilin at 2.6A resolution. Nature 1995;378:32–8. 25. Sparling PF. Biology of Neisseria gonorrhoeae. In: Holmes KK, Sparling PF, Stamm WE, et al., editors. Sexually transmitted diseases. New York: McGraw-Hill; 2008. p. 607–26. 26. Handsfield HH, Lipman TO, Harnisch JP, et al. Asymptomatic gonorrhea in men: diagnosis, natural course, prevalence, and significance. N Engl J Med 1974;290:117–23. 27. Wiesner PJ, Tronca E, Bonin P, et al. Clinical spectrum of pharyngeal gonococcal infections. N Engl J Med 1973;288:181–5. 28. Hook EW III, Handsfield HH. Gonococcal infections in the adult. In: Holmes KK, Sparling PF, Stamm WE, et al., editors. Sexually transmitted diseases. New York: McGraw-Hill; 2008. p. 627–45. 29. Stary A, Ching SF, Teodorowicz L, Lee H. Comparison of ligase chain reaction and culture for detection of Neisseria gonorrhoeae in genital and extragenital specimens. J Clin Microbiol 1997;35:239–42. 30. Smith KR, Ching S, Lee H, et al. Evaluation of ligase chain reaction for use with urine for identification of Neisseria gonorrhoeae in females attending a sexually transmitted disease clinic. J Clin Microbiol 1995;33:455–7. 31. Centers for Disease Control (CDC). Update to CDC’s Sexually Transmitted Diseases Treatment Guidelines, 2010: oral cephalosporins no longer a recommended treatment for gonococcal infections. MMWR Morb Mortal Wkly Rep 2012;61:590–4. 32. Cole MJ, Spiteri G, Chisholm SA, et al. Emerging cephalosporin and multidrug-resistant gonorrhoea in Europe. Euro Surveill 2014;19:20955. 32a.  Allan-Blitz L-T, Humphries RM, Hemarajata P, et al. Implementation of a rapid genotypic assay to promote targeted cirprofloxacin therapy of Neisseria gonorrhoeae in a large health system. Clin Infect Dis 2017;64:1268–70. 33. Ducrey A. Experimentelle Untersuchungen über den Ansteckungsstoff des weichen Schankers und über die Bubonen. Monatshr Prakt Dermatol 1889;9:387–405. 34. Ronald A. Chancroid. In: Mandell GL, (editor.-in-chief ), Rein MF, editor. Atlas of infectious diseases, vol. 5.

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REFERENCES

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Protozoa and Worms Francisco G. Bravo

Chapter Contents Protozoa . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1470 Leishmaniasis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1470 Cutaneous diseases caused by amebas . . . . . . . . . . . . . . 1476 Trypanosomiasis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1479 Toxoplasmosis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1483 Worms (helminths) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1484 Cutaneous larva migrans . . . . . . . . . . . . . . . . . . . . . . . . 1484

■ The clinical manifestations of leishmaniasis depend on the host’s cell-mediated immune response and the species of Leishmania involved; clinical subtypes include cutaneous, disseminated cutaneous, diffuse cutaneous, mucocutaneous/mucosal, and visceral leishmaniasis ■ The most common cutaneous finding is a papule at the site of inoculation that classically evolves into an ulcer ■ The vector is a sandfly infected with promastigotes ■ The disease has a worldwide distribution but is endemic in Latin America, the Mediterranean basin, and parts of Asia and Africa

Gnathostomiasis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1488 Onchocerciasis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1493 Filariasis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1496 Schistosomiasis and swimmer’s itch . . . . . . . . . . . . . . . . 1498 Cysticercosis and echinococcosis . . . . . . . . . . . . . . . . . . 1499

Key features ■ Protozoa are responsible for many tropical diseases that not only affect large regions of the world but also can have different clinical presentations in the Old World versus the New World (e.g. leishmaniasis) ■ Protozoal infections can lead to significant morbidity in both immunocompromised hosts (e.g. toxoplasmosis) and immunocompetent individuals (e.g. Balamuthia spp.) ■ Worms (helminths) are common parasites with a worldwide distribution; cutaneous manifestations vary considerably, from pruritus ani to elephantiasis ■ Even helminthic diseases with a restricted geographic distribution, such as onchocerciasis and echinococcosis, may be observed in individuals from non-endemic areas due to immigration, tourism, disaster relief efforts or military service

PROTOZOA LEISHMANIASIS Synonyms:  ■ Old World cutaneous leishmaniasis: oriental sore, Delhi boil, Baghdad boil ■ New World cutaneous and mucocutaneous leishmaniasis: American tegumentary leishmaniasis, chiclero ulcer (Mexico), uta and espundia (Peru), ulcera de Bauru (Brazil), bush or forest yaws, pian boi (Guyanas) ■ Diffuse cutaneous leishmaniasis: anergic, lepromatous, or pseudolepromatous leishmaniasis ■ Visceral leishmaniasis: kala-azar, Dumdum fever

Key features 1470

■ Chronic parasitic (protozoan) disease in which organisms are found within phagolysosomes of mononuclear phagocytes

Introduction Leishmaniasis encompasses a spectrum of chronic infections in humans and several animal species. It is caused by over 20 species of Leishmania (Table 83.1), flagellated protozoans belonging to the order Kinetoplastidae. Transmission is via the bite of infected female sandflies from the genera Phlebotomus and Lutzomyia. The disease has a worldwide distribution, affecting millions of people in South America, the Mediterranean basin, and parts of Asia and Africa1 (Figs 83.1 & 83.2). There are four major clinical patterns: (1) cutaneous, which is restricted to the skin and is seen more often in the Old World; (2) mucocutaneous, which affects both the skin and mucosal surfaces and occurs almost exclusively in the New World; (3) diffuse cutaneous, which occurs mainly in the New World; and (4) visceral, which affects the organs of the mononuclear phagocyte system, e.g. liver, spleen2,3.

Epidemiology Worldwide, there are approximately 2 million new cases of leishmaniasis annually, with cutaneous or mucocutaneous disease in >75% of affected individuals; it is estimated that 12 million people are currently infected4. Over 90% of cutaneous infections with Leishmania occur in the Middle East (Afghanistan, Algeria, Iran, Iraq, Saudi Arabia, Syria) and South America (Brazil, Peru, Colombia) (Table 83.2), but the disease is also found in the Mediterranean basin, sub-Saharan Africa, Central Asia, and India (see Fig. 83.1). South-central Texas is the only endemic area for cutaneous leishmaniasis in the US; most infections diagnosed in the US are acquired outside of the country5. Mucocutaneous leishmaniasis is endemic in several countries in Central and South America. Although the visceral form of leishmaniasis has a worldwide distribution, it is seen most frequently in Africa and Asia1,2,6. Old World cutaneous leishmaniasis is usually due to L. major or L. tropica, and less often L. infantum (Europe) or L. aethiopica (Ethiopia and Kenya) (see Table 83.1). In the New World, cutaneous leishmaniasis is caused primarily by subspecies of L. mexicana and the L. braziliensis complex, whereas mucocutaneous/mucosal disease is associated with the latter organisms. Diffuse cutaneous leishmaniasis is most commonly associated with L. amazonensis3. Infections with L. donovani (e.g. India, Bangladesh, the Sudan) and L. infantum (e.g. Europe, especially in the setting of HIV infection) as well as the subspecies L. infantum chagasi (e.g. Central and South America; previously known as L. chagasi) are the major causes of visceral leishmaniasis (Table 83.3). The species of Leishmania can also vary within a particular geographic region. For example, in the Middle East, L. major is found in rural areas where the primary animal reservoirs are desert rodents, whereas L. tropica is endemic in urban areas6. Canine and rodent species act as the main reservoirs for Leishmania (see Table 83.1). Transmission between these species (as well as to

Protozoal and helminth infections are major causes of tropical disease in many parts of the world. For some of the conditions, the clinical presentations differ depending on the geographic region, e.g. New World vs Old World leishmaniasis. Protozoal infections can lead to significant morbidity in both immunocompromised hosts (e.g. toxoplasmosis) and immunocompetent individuals (e.g. Balamuthia spp.). The cutaneous manifestations of helminth infections range from larva migrans to elephantiasis. Even diseases with a restricted geographic distribution, such as leishmaniasis, may be observed in individuals from nonendemic areas due to immigration, tourism, disaster relief efforts, or military service.

leishmaniasis Balamuthia mandrillaris infection amebiasis trypanosomiasis toxoplasmosis helminths cutaneous larva migrans onchocerciasis gnathostomiasis filariasis schistosomiasis swimmer’s itch cysticercosis echinococcosis

CHAPTER

83 Protozoa and Worms

ABSTRACT

non-print metadata KEYWORDS

1470.e1

CHAPTER

Major geographic distribution

Clinical patterns (in addition to cutaneous)

Complex

Major species

Major reservoirs

Leishmania donovani

L. donovani

Humans

Sudan, Kenya, Tanzania, India, Bangladesh

Visceral, PKD, mucosal (rare)

(Uncommon)

L. infantum

Dogs, foxes

Mediterranean region

Favors children (uncommon)

L. infantum chagasi**

Dogs, foxes, opossums

Central and South America

Visceral (favors children), PKD*, mucosal† (rare)

L. major

Rodents

Arid areas of Africa (north and south of the Sahara), Middle East and Central Asia

Mucosal (rare)

Old World zoonotic/rural (moist, early ulcerative with rapid course), recidivans (rare), lupoid (rare)

L. tropica

Humans, dogs

Eastern Mediterranean region, Middle East, Central Asia

Visceral (rare), mucosal (rare)

Old World anthroponotic/urban (dry, late ulcerative with chronic course), recidivans, lupoid

L. aethiopica

Hyraxes

Ethiopia, Kenya, Yemen

Diffuse cutaneous, mucocutaneous

Dry/late ulcerative or moist/early ulcerative

L. mexicana

Forest rodents

Mexico, Central America

Diffuse cutaneous (rare)

L. amazonensis

Forest rodents

South America

Diffuse cutaneous, mucocutaneous, visceral (rare), PKD (rare)

New World Variants include ulcerative, plaque-like, pustular, impetigo-like, erysipeloid, sarcoidosis-like, papulotuberous, verrucous, sporotrichoid, eczematous

L. venezuelensis, pifanoi, garnhami

Unknown

Venezuela

Diffuse cutaneous (rare)

L. braziliensis

Forest rodents

Central and South America

Mucocutaneous, visceral†

L. guyanensis

Sloths, anteaters

Guyana, Brazil

Mucocutaneous

L. panamensis

Sloths

Panama, Costa Rica, Colombia

Mucocutaneous

L. peruviana

Dogs

Peru, Argentina

Leishmania tropica

Leishmania mexicana

Leishmania (Viannia) braziliensis

Clinical forms of the cutaneous pattern

Protozoa and Worms

83

EPIDEMIOLOGIC AND CLINICAL PATTERNS OF INFECTIONS WITH LEISHMANIA SPECIES

*Rare/controversial; reported in children and in HIV-infected adults following antiretroviral therapy. L. infantum subspecies in the New World; previously known as L. chagasi. ** †Especially in immunocompromised hosts. Table 83.1 Epidemiologic and clinical patterns of infections with Leishmania species. Common clinical patterns for particular species are in bold. Additional minor species include L. garnhami, naiffi, lainsoni, colombiensis, shawi, archibaldi, and martiniquensis. Viannia is a subgenus of Leishmania. Mucosal leishmaniasis refers to oronasal lesions not preceded or accompanied by cutaneous involvement. PKD, post-kala-azar dermal leishmaniasis. Modified from Lupi O, Barlett BL, Haugen RN, et al.  

Tropical dermatology: tropical diseases caused by protozoa. J Am Acad Dermatol. 2009;60:897–925 and Peters W, Pasvol G. Tropical Medicine and Parasitology, 6th edition. London: Mosby, 2007.

DISTRIBUTION OF VISCERAL LEISHMANIASIS DISTRIBUTION OF CUTANEOUS LEISHMANIASIS

Leishmania infantum Leishmania braziliensis complex Leishmania mexicana complex Leishmania major

Leishmania tropica Leishmania aethiopica Leishmania infantum

Fig. 83.1 Distribution of cutaneous leishmaniasis. Adapted with permission from Davidson RN. Leishmaniasis. In: Cohen J, Powderly WG (eds). Infectious Diseases. Edinburgh: Mosby, 2004.  

Leishmania infantum chagasi

Leishmania donovani

Fig. 83.2 Distribution of visceral leishmaniasis. These organisms, in particular L. infantum and L. donovani, can also cause cutaneous disease. Adapted with  

permission from Davidson RN, Leishmaniasis. In Cohen J, Powderly WG, eds, Infectious Diseases. Edinburgh: Mosby, 2004.

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SECTION

Infections, Infestations, and Bites

12

humans) is via sandflies, primarily of the genera Phlebotomus (Old World) and Lutzomyia (New World). Human-to-human spread of L. tropica can also occur. In general, humans contract leishmaniasis as accidental hosts when they intrude into the sandfly’s habitat. Overall, the disease is seen most commonly in men between 20 and 40 years of age, but Old World cutaneous leishmaniasis occurs more often in children2.

Pathogenesis Leishmania spp. are obligate intracellular parasites that exist in two forms: the promastigote and the amastigote. In the gut of the sandfly, the organisms multiply as extracellular flagellated promastigotes. Following migration to the proboscis, the parasites are inoculated (in the promastigote form) via the sandfly bite. Once inoculated into the skin, the parasites are rapidly engulfed by the host’s mononuclear phagocytes, where they transform into amastigotes and multiply via binary fission (Fig. 83.3). The incubation time from infection until the first clinical manifestation can vary from ≤2 weeks for cutaneous lesions (typically several weeks to 2 months) to >2 years for mucocutaneous lesions or visceral involvement (typically 3 to 9 months)7. The clinical manifestations of leishmaniasis depend on the species of Leishmania (see Table 83.1), the host’s cell-mediated response, and the ability of the parasite to evade host defense mechanisms7a. A robust Th1 response with production of interleukin-2 (IL-2) and interferon-γ (IFN-γ) is associated with quicker resolution, whereas a lack of a Th1 response and/or the development of a Th2-type response with production of IL-4 and IL-10 is associated with disease progression8–10. Depending on the type of immune response, L-arginine metabolism within infected macrophages occurs via two alternative pathways: (1) Th2 cytokines promote its catabolism by arginase to produce L-ornithine, which favors parasitic growth; or (2) Th1 cytokines promote nitric oxide synthase-induced generation of L-citrulline plus nitric oxide, and the latter increases host

resistance via NLRP3 (NLR family pyrin domain-containing-3) inflammasome-derived IL-1β10a. Resistance of L. amazonensis and L. braziliensis promastigotes to nitric oxide in vitro correlates with poorer clinical outcomes. Mucocutaneous disease is associated with the infection of Leishmania organisms with Leishmania RNA virus-1 (LRV1); this virus is recognized by human Toll-like receptor 3, leading to a proinflammatory cascade that subverts the immune response to Leishmania, and allows disease progression11. L. donovani has been shown to induce epigenetic changes via macrophage DNA methylation that down-regulate host defense mechanisms, allowing parasitic replication and survival11a. Human genetic factors include HLA variants that contribute to leishmaniasis risk and IL2RA variants that reduce IL-2dependent responses and thereby increase susceptibility to cutaneous and visceral leishmaniasis11b. IFN-γ is the most potent cytokine involved in the induction of activity against organisms residing within macrophage phagolysosomes. It leads to the production of oxygen species and activates naive CD4+ cells to become Th1 cells (see Fig. 4.10). The latter differentiation process is aided by IL-12, which stimulates natural killer (NK) cells to produce IFN-γ8,10,12. Tumor necrosis factor (TNF) produced by macrophages and NK cells amplifies the IFN-γ driven macrophage activation9,13. Consequently, use of TNF inhibitors increases the risk of developing leishmaniasis, especially the visceral form. Recent studies have also

LIFE CYCLE OF LEISHMANIA SPECIES

Infect other cells Amastigotes in histiocyte Taken up by fly

COUNTRIES WITH THE HIGHEST INCIDENCE OF LEISHMANIASIS Old World cutaneous leishmaniasis

Afghanistan, Algeria, Iran, Iraq, Saudi Arabia, Syria

New World cutaneous leishmaniasis

Brazil, Peru, Colombia

Mucocutaneous/mucosal leishmaniasis

Bolivia, Brazil, Peru

Visceral leishmaniasis

Brazil, Ethiopia, India, Kenya, Somalia, South Sudan, Sudan.

Sandfly Promastigote

Table 83.2 Countries with the highest incidence of leishmaniasis. The incidence of visceral leishmaniasis has been decreasing in Bangladesh, Nepal, and India. Further information is provided at http://www.who.int/mediacentre/ factsheets/fs375/en/ and http://new.paho.org/leishmaniasis.

Binary fission Engulfed by histiocytes



Fig. 83.3 Life cycle of Leishmania species. Promastigotes develop within the gut of the sandfly and then migrate to the proboscis.  

EPIDEMIOLOGY AND CLINICAL PATTERNS OF VISCERAL LEISHMANIASIS

1472

Type of disease

Major species

Major geographic distribution

Kala-azar (60% 10–20 years of age)

Leishmania donovani

India, China (north of Yangtze River), Kenya, Sudan

Infantile kala-azar (90% 300) secondary lesions, either in proximity to or distant from the primary site. The lesions resemble those of classic cutaneous leishmaniasis, including papules and small nodules that may have an acneiform appearance, and ulceration is common (Fig. 83.8B). Up to 25% of affected individuals have concomitant mucosal disease, and patients may have systemic symptoms such as fever and malaise. Disseminated skin disease most likely results from early hematologic spread, and it is associated with decreased production of IFN-γ and TNF15. Diffuse cutaneous leishmaniasis is a rare presentation that develops in the setting of reduced cell-mediated immunity, analogous to lepromatous leprosy. L. aethiopica (in Africa) and L. amazonensis (in the Americas) are the most common pathogens (see Table 83.1). Multiple nodular and keloid-like lesions on the face and limbs are usually observed3 (Fig. 83.8A); ulceration is uncommon but occasionally occurs secondary to trauma. Nasal infiltration and mucosal ulceration may develop due to spread from nearby skin lesions, but destruction of the nasal septum is rare. There may also be laryngeal and pharyngeal involvement14.

A

Mucocutaneous/mucosal leishmaniasis

B

Fig. 83.8 Diffuse and disseminated cutaneous leishmaniasis. A Diffuse cutaneous leishmaniasis presenting with large nodules that resemble lepromatous leprosy. B Small papules in disseminated cutaneous leishmaniasis.  

1474

characterized by recurrence at the site of an original ulcer, generally within 2 years and often at the edge of the scar14. Anthroponotic or, less frequently, zoonotic cutaneous leishmaniasis occasionally develops into chronic lupoid leishmaniasis, which clinically and histologically (epithelioid granulomas surrounded by lymphocytes) resembles the lupus vulgaris form of cutaneous tuberculosis. The amastigotes are few in number and difficult to find in lupoid leishmaniasis, making establishment of the diagnosis more challenging. New World cutaneous leishmaniasis has a wide clinical spectrum, including plaque-like, sporotrichoid, pustular, impetigo-like, eczematoid, sarcoid-like, lupoid, erysipeloid, papulotuberous, verrucous14, disseminated, and diffuse presentations. Disseminated cutaneous leishmaniasis, which most often results from L. braziliensis or L. amazonensis infection, is characterized by

After a variable time period ranging from a few months to more than 20 years, mucocutaneous/mucosal disease develops in some patients infected with Leishmania spp. in the Viannia subgenus (known as the L. braziliensis complex), most commonly L. braziliensis and occasionally L. panamensis, L. guyanensis, or hybrid genotypes16. Mucosal lesions range from edema of the lips and nose to perforation of the nasal septum or (less often) the laryngeal cartilage or palate. Infiltration and/or ulceration of the mucosal surfaces of the nose, lips, and oropharynx are typical features (Figs 83.9 & 83.10); ocular or genital involvement is rare. In some patients, there is extensive loss of tissue in both the mouth and nose, causing a characteristic “tapir face” known as espundia. Hoarseness may result from vocal cord involvement14,16.

Visceral leishmaniasis (kala-azar) Visceral leishmaniasis, or kala-azar, occurs when the parasite spreads to the bone marrow, spleen, and liver3. It is primarily caused by L. donovani in adults and L. infantum or L. chagasi in children. The incubation period ranges from 1 to 36 months. Fever, wasting, cough, lymphadenopathy, and hepatosplenomegaly are the most common systemic findings (Table 83.4). There may be an abrupt onset or slow progression, and fever may be continuous or intermittent. Additional complications include enteritis, oronasal or gastrointestinal hemorrhage, pneumonia, and nephritis, which may lead to death14. Cutaneous manifestations may be disease-specific papules, nodules, or ulcers





Peters W, Pasvol G. Tropical Medicine and Parasitology, 6th edition. London: Mosby, 2007.

Courtesy, Kalman Watsky, MD.

CHAPTER

83 Protozoa and Worms

Fig. 83.11 Post-kala-azar dermal leishmaniasis. Nodules of various sizes, some pedunculated, are seen in this patient who had been treated for kala-azar over a period of 6 months, 20 years previously. With permission from

Fig. 83.10 Mucocutaneous leishmaniasis due to Leishmania braziliensis. Ulceration and induration of the nasal vestibule extends onto the cutaneous lip.

SYSTEMIC FEATURES OF VISCERAL LEISHMANIASIS (L. DONOVANI)

Clinical features

Proportion affected (%)

Age 10% of patients with visceral leishmaniasis who live in Leishmania-endemic areas19.

Laboratory findings Globulin >30 g/l

95

Albumin 5 mm in diameter forms at the site of inoculation after 48–72 hours (see Fig. 83.5)14. It is positive in up to 90% of patients with cutaneous and mucocutaneous leishmaniasis of over 3 months’ duration3 and is invariably negative in patients with diffuse cutaneous (anergic) leishmaniasis14. However, this test (which is not approved by the US Food and Drug Administration [FDA]) cannot distinguish between past and present infections, so it is most useful in patients who do not reside in areas where leishmaniasis is endemic; positivity develops while the skin lesions are still active, and the test remains positive long after spontaneous cure. The test is usually negative during the febrile phase of visceral leishmaniasis, but it often becomes positive after cure. For culturing Leishmania, specialized media are required, e.g. Nicolle– Novy–MacNeal (NNM) media or chick embryo media. Cultures are positive in approximately 40% of cases. Serologic and immunologic tests are also available, e.g. indirect immunofluorescence, ELISA, immunoprecipitation, and isoenzyme electrophoresis. Serologic testing is most useful for visceral and occasionally mucocutaneous disease, although it is not specific due to cross-reactivity (e.g. with Chagas disease antibodies)21. PCR-based methods represent the most sensitive and specific diagnostic tests, and their availability is increasing2,14. An FDA-approved real-time PCR assay for the diagnosis of leishmaniasis is available through the Centers for Disease Control and Prevention (CDC)20.

Differential Diagnosis

1476

The differential diagnosis of cutaneous leishmaniasis includes persistent arthropod bite reaction, basal cell carcinoma, tuberculosis, nontuberculous mycobacterial infections, and subcutaneous mycoses; other infectious causes of lesions in a lymphocutaneous pattern are listed in Table 77.17. Mucocutaneous leishmaniasis can resemble paracoccidioidomycosis and tertiary syphilis. In addition, granulomatosis with polyangiitis (formerly Wegener granulomatosis) and angiocentric NK/Tcell lymphoma should be considered when ulcerative mucocutaneous lesions affect the central part of the face. Cocaine-induced nasal

Factors to consider in the treatment of leishmaniasis include the region of the world in which the infection was acquired, the species of Leishmania, the site(s) and severity of the infection, and host factors such as immune status and age. The benefit of therapy needs to be balanced with the goal of minimizing drug toxicity. Without treatment, Old World cutaneous leishmaniasis typically resolves within 2–4 months (L. major) or 6–15 months (L. tropica). Indications for systemic treatment of Old World cutaneous leishmaniasis include (1) an immunocompromised host; (2) >4 lesions of substantial size (e.g. >1 cm) or individual lesion(s) measuring ≥5 cm; (3) markedly enlarged regional lymph nodes; and (4) involvement of the mucosa, face, ears, genitalia, fingers, toes, or skin overlying a joint22–24. Local therapy or, if the lesions are healing spontaneously within 6 months, observation are options for patients who do not meet these criteria. New World cutaneous leishmaniasis caused by L. mexicana resolves within 3 months in >75% of cases. In contrast, cutaneous disease caused by L. braziliensis and L. panamensis spontaneously heals in less than 10% and 35% of cases, respectively. Therefore, systemic treatment is indicated when L. braziliensis complex infection is suspected in order to accelerate healing, decrease scarring (especially in cosmetically sensitive sites), and prevent dissemination, relapse, or the development of mucosal disease24. Parenteral pentavalent antimonials and miltefosine are first-line systemic treatments for cutaneous and mucocutaneous/mucosal leishmaniasis, whereas liposomal amphotericin B is the treatment of choice for visceral leishmaniasis22,24. Table 83.5 summarizes treatment regimens for cutaneous and mucocutaneous/mucosal leishmaniasis24–30. Table 83.6 lists frequent adverse reactions to drugs used for the treatment of leishmaniasis. Additional interventions that have shown some efficacy for cutaneous and (in combination with other agents) muco­ cutaneous/mucosal leishmaniasis include heat therapy31, cryotherapy, photodynamic therapy, and oral allopurinol. Drugs or vaccines that completely prevent leishmanial infection have not yet been developed. The best form of protection is to avoid the bite of the sandfly and eliminate animal reservoirs. Personal protection includes applying DEET-based repellants, bed netting, permethrintreated clothing, and sleeping in minimal-risk areas. People are at increased risk of bites in the early morning and late evening25.

CUTANEOUS DISEASES CAUSED BY AMEBAS Amebas (ameboid protozoa) are single-celled eukaryotes characterized by movement via pseudopodia (temporary cytoplasmic extensions). Organisms in this group that can produce cutaneous disease include enteric pathogens (e.g. Entamoeba histolytica) and free-living amebas such as Acanthamoeba spp. and Balamuthia mandrillaris. E. histolytica has a worldwide distribution and may infect the skin via inoculation or extension from the gastrointestinal tract. B. mandrillaris and Acanthamoeba spp. can cause skin infections and granulomatous encephalitis in immunocompromised and (for B. mandrillaris) immunocompetent patients. Acanthamebiasis may present with papules, nodules, and ulcers on the trunk and extremities in patients with advanced HIV infection (see Ch. 78).

Amebiasis due to Entamoeba Histolytica Key features ■ Amebiasis due to Entamoeba histolytica usually affects the gastrointestinal tract and rarely spreads to the skin

CHAPTER

Cutaneous leishmaniasis Drugs of choice

Sodium stibogluconate* Meglumine antimonate*

Alternatives

20 mg/kg/day IV or IM × 20 days Various intralesional regimens, e.g. 0.2–5 ml (5 sites/lesion intradermally for 0.1 ml/cm2 until blanched) every 3–21 days for 5–8 sessions or until healing

Miltefosine**

50 mg BID if weight is 30–44 kg and TID if weight is ≥45 kg × 28 days

Paromomycin 15% and MBCL 12% ointment

Topically BID × 10 days, wait 10 days, then repeat

Paromomycin 15% and gentamicin 0.5% cream

Topically daily for 20 days

Pentamidine

3–4 mg/kg IV or IM every other day × 3–4 doses

Fluconazole†

200 mg/day or 6–8 mg/kg/day PO × 6 weeks

Liposomal amphotericin B†

3 mg/kg/day IV on days 1–5 + 10 or days 1–7

Amphotericin B deoxycholate

0.5–1 mg/kg IV daily or every other day for a total dose of 15–30 mg/kg

Mucocutaneous leishmaniasis Drugs of choice

Sodium stibogluconate*

20 mg/kg/day IV or IM × 28 days

Meglumine antimonate*

Alternative

Liposomal amphotericin B

∼3 mg/kg/day IV for a total dose of ∼20–60 mg/kg

Amphotericin B deoxycholate

0.5–1 mg/kg IV daily or every other day for a total dose of ∼20–45 mg/kg

Miltefosine**

50 mg BID if weight is 30–44 kg and TID if weight is ≥45 kg × 28 days

Pentamidine

2–4 mg/kg IV or IM every other day or 3 times per week for ≥15 doses

stibogluconate *Doses refer®to mg of pentavalent antimony – 100 mg/ml for sodium ® (Pentostam ), 85 mg/ml for meglumine antimonate (Glucantime ).

**FDA-approved for the treatment of cutaneous and mucosal leishmaniasis due to L. braziliensis, L. guyanensis, and L. panamensis in patients ≥12 years of age.

†Limited evidence of efficacy; other azole antifungals that have been utilized (with variable

results) include ketoconzaole (600 mg/day or 10 mg/kg/day PO × 4 weeks) and itraconzaole (7 mg/kg/day PO × 3 weeks).

Table 83.5 Treatment recommendations for leishmaniasis. The treatment regimen (drug, dose, duration) that is chosen depends upon the geographic region, species of Leishmania, location and severity (e.g. number and size of lesions) of disease, and host factors. The Centers for Disease Control and Prevention (CDC), World Health Organization (WHO) and Pan-American Health Organization (PAHO) represent resources for up-to-date information. Sodium stibogluconate is not approved by the US Food and Drug Administration (FDA), but it is available from the CDC; meglumine antimonate and paromomycin are not readily available in the US. A recent randomized controlled study found no benefit from adding pentoxifylline to sodium stibogluconate for the treatment of cutaneous leishmaniasis. BID, twice daily; IM, intramuscular; IV, intravenous; MBCL, methylbenzethonium chloride; PO, orally; TID, three times daily.  

ADVERSE SIDE EFFECTS OF THE MOST COMMONLY USED DRUGS FOR LEISHMANIASIS

Drug

Side effect

Intralesional pentavalent antimony

Localized pain, erythema, edema

Parenteral pentavalent antimony

Raised amylase/lipase and/or LFTs

Miltefosine

Pentamidine

Incidence 25–50% >50%

Myalgia, arthralgia

25–50%

Abdominal pain/nausea

25–50%

Thrombocytopenia/leukopenia

50%

Hyperglycemia

diarrhea, abdominal pain > elevated transaminases, cholestasis • Neurologic: dizziness, drowsiness > headache, paresthesias, weakness > tinnitus, seizures, hallucinations • Ocular: irritation, blurred vision, xerophthalmia • Other: crystalluria without hematuria, transient leukopenia, xerostomia



GI nematode infections (e.g. enterobiasis, ascariasis, ancylostomiasis), toxocariasis, trichinosis, sparganosis



GI: nausea, vomiting, diarrhea, abdominal pain > elevated transaminases • Neurologic: dizziness, drowsiness > tinnitus, seizures • Hematologic: anemia, thrombocytopenia, leukopenia > agranulocytosis • Other: alopecia, oligospermia



Cutaneous larva migrans, GI nematode infections (as above), gnathostomiasis, echinococcosis, neurocysticercosis, toxocariasis



GI: nausea, vomiting, diarrhea, abdominal pain, elevated transaminases > cholestasis • Neurologic: headache, dizziness > increased intracranial pressure (with treatment of neurocysticercosis), seizures • Hematologic: leukopenia > thrombocytopenia, agranulocytosis, pancytopenia • Other: alopecia



Filariasis, dirofilariasis, loiasis, toxocariasis (second-line therapy)



GI: nausea, vomiting, anorexia Neurologic: headache



Mebendazole

Albendazole

Diethylcarbamazine



Cutaneous: urticaria (3%), exanthem ( fixed drug eruption, pruritus, perianal rash, flushing, angioedema, contact dermatitis, Jarisch– Herxheimer reaction, Stevens–Johnson syndrome • Fever, anaphylaxis

Cutaneous: exanthem, urticaria, angioedema, pruritus, flushing

Precautions and contraindications FDA pregnancy category C Discontinue during lactation • Use with caution if hepatic disease • •

Protozoa and Worms

83

ANTIHELMINTHIC DRUGS: THERAPEUTIC USES, SIDE EFFECTS, AND CONTRAINDICATIONS

FDA pregnancy category C Use with caution in children angioedema, Stevens–Johnson syndrome • Fever, anaphylaxis



FDA pregnancy category C Avoid during lactation • Use with caution if hepatic disease

Mazzotti reaction: pruritus, lymphadenopathy > papular exanthem, fever, tachycardia, arthralgias, headache • Nodular swellings along the lymphatics • Leukocytosis, eosinophilia • Ocular: limbitis, punctate keratitis > uveitis, atrophy of the retinal pigment epithelium > retinal hemorrhage (L. Ioa) • Encephalitis (L. Ioa) • Proteinuria





Appears to be safe for use during pregnancy (controlled studies show no fetal risk) • Avoid population-based administration in regions where onchocerciasis or loiasis is endemic

Table 83.7 Antihelminthic drugs: therapeutic uses, side effects, and contraindications. In 2015, the FDA replaced pregnancy risk categories with narrative sections addressing pregnancy and lactation; the new format is used for prescription drugs approved from June 30, 2015 onward and is being phased in for other drugs approved since 2001. GI, gastrointestinal. Continued  

inoculation is the eye, other entities to consider include a reaction to a bite from another type of insect, angioedema, and bacterial cellulitis.

Treatment Treatment is most effective early in the course of Chagas disease55. Benznidazole and nifurtimox (both available through the CDC) can reduce the severity and duration of symptoms associated with the acute phase, with a parasitologic cure in 60–90% of patients51a,56. Because benznidazole is better tolerated, it is favored by most experts51a. The side effects of these two medications are reviewed in Table 83.7. Benznidazole, allopurinol, itraconazole, and posaconazole have also been evaluated for the treatment of chronic Chagas disease57,57a,57b. Although these agents can decrease serum parasite load, to date, there is no evidence that pathologic changes or progression of the chronic phase of this disease can be reversed or stopped by any therapy. Thus, chronic disease is managed primarily by supportive care (e.g. antiarrhythmics)53.

Prevention of the infection involves education about sanitation and the use of residual insecticides in domestic areas. Vaccines are being investigated but are not currently available.

African Trypanosomiasis Key features ■ In West Africa, the disorder is due to Trypanosoma brucei gambiense infection, and in East Africa it is caused by Trypanosoma brucei rhodesiense infection ■ The vectors are several species of tsetse flies ■ Cutaneous manifestations include a localized bite reaction (“trypanosomal chancre”) and an annular erythematous eruption that coincides with fever spikes

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ANTIHELMINTHIC DRUGS: THERAPEUTIC USES, SIDE EFFECTS, AND CONTRAINDICATIONS

Toxicity and side effects Drug

Therapeutic use

Direct drug effects

“Allergic” reactions

Ivermectin

Onchocerciasis, filariasis (second-line therapy), cutaneous larva migrans, gnathostomiasis, ascariasis, strongyloidiasis



GI: nausea, vomiting, diarrhea, elevated transaminases > cholestasis • Neurologic: dizziness > drowsiness, headache, tremor • Other: leukopenia



Schistosomiasis; liver fluke and tapeworm infections (e.g. cysticercosis, sparganosis)



GI: nausea, vomiting, abdominal discomfort > bloody diarrhea, elevated transaminases • Neurologic: headache, dizziness > drowsiness • Other: arrhythmias



GI nematode infections (e.g. ascariasis, ancylostomiasis; second-line therapy)



GI: nausea, vomiting, diarrhea, abdominal discomfort • Neurologic: headache > dizziness, insomnia, paresthesias > multifocal leukoencephalopathy • Hematologic: leukopenia, anemia, thrombocytopenia > agranulocytosis • Other: dysgeusia, xerosis, alopecia, arthralgias



Nifurtimox

Chagas disease



GI: nausea, vomiting, anorexia > abdominal pain, diarrhea • Neurologic: paresthesias, weakness, headache, insomnia > psychiatric disturbances, seizures • Other: myalgias > leukopenia, oligospermia

Benznidazole

Chagas disease



GI: nausea, vomiting, anorexia Neurologic: paresthesias, weakness • Hematologic: leukopenia > thrombocytopenia, agranulocytosis • Other: myalgias GI: nausea, vomiting > diarrhea, abdominal pain, elevated transaminases, cholestasis • Neurologic: palmoplantar hyperesthesia/paresthesias, weakness, headache > seizures • Ocular: blepharitis, conjunctivitis, photophobia, excessive lacrimation • Hematologic: leukopenia > agranulocytosis, hemolytic anemia, thrombocytopenia • Other: malaise, dysgeusia, proteinuria > renal or adrenal insufficiency



GI: diarrhea (40%) > nausea, vomiting, abdominal pain • Neurologic: dizziness, headache, seizures (~5%) • Hematologic: anemia (50%) > leukopenia (25%) > thrombocytopenia • Other: alopecia > hearing loss



Praziquantel

Levamisole



Suramin

African trypanosomiasis

Eflornithine

African trypanosomiasis (T. brucei gambiense)





Precautions and contraindications

Mazzotti-like reaction and ocular side effects (O. volvulus; see above) • Pruritus, urticaria, peripheral edema • Orthostatic hypotension



Cutaneous: pruritus > urticaria, exanthem • Arthralgias, myalgias • Fever • Meningismus, CSF pleocytosis, seizures (in neurocysticercosis)



Cutaneous: exanthem (5–10%) > pruritus, urticaria, angioedema, fixed drug eruption, lichenoid eruption, vasculitis/vasculopathy (favors the ears), Stevens–Johnson syndrome • Stomatitis (5%) • Fever, anaphylaxis





Cutaneous: exanthem, urticaria, angioedema • Fever, anaphylaxis





Cutaneous (more common than with nifurtimox): exanthem, urticaria, angioedema, generalized peripheral edema • Fever, lymphadenopathy, anaphylaxis



Cutaneous: exanthem, urticaria > exfoliative dermatitis, generalized peripheral edema • Stomatitis • Fever, anaphylaxis (1 : 2000)



Cutaneous: exanthem Fever

FDA pregnancy category C Considered safe during lactation



FDA pregnancy category B Avoid during lactation • Contraindicated for ocular cysticercosis •

FDA pregnancy category C Considered safe during lactation



FDA pregnancy category C

FDA pregnancy category C

FDA pregnancy category C Use with caution if renal disease



FDA pregnancy category C





Table 83.7 Antihelminthic drugs: therapeutic uses, side effects, and contraindications. (cont’d) CSF, cerebrospinal fluid; GI, gastrointestinal.  

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The incidence of African trypanosomiasis decreased from ∼10 000 cases in 2009 to 90% and a specificity of 100%90. Highly sensitive and specific PCR-based tests have also been developed. Tests based on antibody detection cannot distinguish between active and past infections.

Differential Diagnosis

Fig. 83.30 Onchocerciasis. Extraction of adult worms from an onchocercal nodule on the buttocks.  

In chronic onchocerciasis, the skin becomes thickened and wrinkled; this is accompanied by lichenification and hyperpigmentation and is sometimes referred to as “lizard” or “elephant” skin or “sowda”. The back, thighs, and lower trunk are frequently affected, and hyperpigmentation may develop on one lower extremity in association with inguinal lymphadenopathy (see Fig. 83.31). Atrophy and a loss of pigment with sparing of perifollicular skin are also seen in late stage onchocerciasis. The latter changes, sometimes referred to as “leopard” skin, are most often evident on the shins87 (see Fig. 83.31; Ch. 66). Chronic lymphatic obstruction and involvement of the inguinal lymph nodes can lead to hanging groin or elephantiasis of the genitalia (see Fig. 83.31). In Central America, young patients who are heavily infested may develop erythema on the face or upper trunk (erisipela de la costa). Older patients may have violaceous papules or plaques (mal morado), which can lead to leonine facies. In addition to skin lesions, microfilariae can also be found in the conjunctivae; from there they can move through the cornea into the anterior and posterior chambers of the eye, leading to conjunctivitis, sclerosing keratitis, uveitis, chorioretinal lesions, optic atrophy, and glaucoma80. Blindness occurs in the most severe cases. Dead microfilariae in the cornea can induce a tissue reaction that produces characteristic “snowflake” opacities.

Early lesions of onchocercal dermatitis must be distinguished from insect bites, scabies, and atopic or allergic contact dermatitis. The chronic skin lesions may be mistaken for chronic eczema with postinflammatory pigmentary changes, leprosy, or the leukoderma of scleroderma. The differential diagnosis of elephantiasis includes other types of filarial infestation (see Fig. 83.24), and a false-positive skin snip can occur if the tissue is contaminated with blood filariae, especially Mansonella perstans or Loa loa.

Treatment Therapy for onchocerciasis has drastically improved as a result of the widespread use of oral ivermectin since 198791. As the drug of choice, it is effective in rapidly killing microfilariae and in preventing their escape from gravid females. Ivermectin causes few or no adverse reactions and no Mazzotti reaction, whereas older drugs, e.g. diethylcarbamazine and suramin, are associated with severe hypersensitivity or dangerous toxic reactions. Ivermectin is administered as a single dose of 150 mcg/kg every 3 to 12 months. After treatment, microfilariae usually disappear from the skin within 1 week and from the eye within 3 months. Although multiple doses of oral ivermectin can kill adult worms, treatment is typically continued for the worm’s lifetime (10–15 years). Administration of doxycycline (100–200 mg/day for 6 weeks) to target Wolbachia endosymbionts represents a promising therapeutic approach that can markedly reduce or eliminate microfilariae for >18 months92,93. Nodulectomy (see Fig. 83.30) is a popular method of treatment in countries where nodules on the head are common; their removal reduces the chance of ocular disease. Preventive measures such as spraying black fly breeding sites with larvicides have not significantly changed the epidemiology of the disease. In contrast, mass treatment of endemic populations with

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Fig. 83.31 Cutaneous findings in onchocerciasis. Photos: left, depigmentation with perifollicular sparing (“leopard” skin); middle, hanging groin due to chronic lymphatic obstruction and lymph node involvement; right, lichenified onchodermatitis (“sowda”). Insets, courtesy, David O Freeman, MD.  

CUTANEOUS FINDINGS IN ONCHOCERCIASIS

Microfilariae within the cornea (seen with slit lamp) Onchocercal nodules (see Fig. 83.30)

Male and female adult worms inside onchocercal nodule

Acute papular onchodermatitis

Chronic papular onchodermatitis

Hanging groin

Lichenified onchodermatitis

Atrophy

Depigmentation

ivermectin once or twice yearly has resulted in significant progress toward elimination of the disease in the Americas and an attainable goal for Africa in the next decade94.

FILARIASIS Synonyms:  ■ Lymphatic filariasis, elephantiasis ■ Elephantiasis

Key features

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■ Filariasis is an infection of the lymphatic system by tissue nematodes (roundworms) acquired via mosquito vectors ■ There are acute, chronic, and asymptomatic forms of filariasis ■ Manifestations of the acute phase include lymphangitis and orchitis ■ Chronic disease is characterized by the sequelae of lymphatic obstruction, e.g. lymphedema, elephantiasis, hydroceles, and chyluria; associated skin findings include hyperkeratosis, verrucous changes, soft tissue hypertrophy, and fibrosis

Introduction Lymphatic filariasis is an infection of the lymphatic system by two genera of filarial nematodes (roundworms). Several species of mosquitoes act as vectors (see Fig. 83.24). Cutaneous findings during the acute and chronic stages include lymphangitis and lymphedema accompanied by changes of elephantiasis.

Epidemiology There are two major forms of filariasis, Bancroftian (due to Wuchereria bancrofti), causing 90% of infections, and Malayan (due to Brugia malayi and B. timori). The disease affects approximately 120 million people living in 73 countries located primarily within the tropical and subtropical regions of South America, Africa, Asia, and the Pacific Islands. W. bancrofti is found worldwide, whereas B. malayi is restricted to South and East Asia. The distribution of B. timori is limited to islands in the Indonesian archipelago95. A number of mosquito species act as vectors for filarial nematodes. The most important ones for W. bancrofti are Culex quinquefasciatus, Anopheles gambiae, Anopheles funestus, Aedes polynesiensis, Aedes scapularis, and Aedes pseudoscutellaris. Both B. malayi and B. timori are transmitted by Anopheles barbirostris. B. malayi can also be transmitted by several species of Aedes and Mansonia mosquitoes95,96.

Multiple bites from infected mosquitoes seem to be required to produce symptomatic infections, and the incubation period varies from 2 to 18 months. Larvae enter lymphatic vessels and then, once mature, the adult worms mate within the lymphatics or lymph nodes and release sheathed microfilariae into the bloodstream95. The mosquito then acquires microfilariae during a blood meal. Over several days, the microfilariae develop into larvae within the mosquito, which can then transmit infection to other humans during subsequent blood meals (see Fig. 83.24). The clinical manifestations of lymphatic filariasis reflect a complex interplay of the pathogenic potential of the parasite, the immune response of the host, and secondary bacterial and fungal infections. Maturing adult worms provoke an eosinophilic and chronic inflammatory cell infiltrate around lymphatic vessels, leading to dilation and valvular damage with eventual scarring and obstruction of lymphatic flow. The death of worms within lymphatic vessels and lymph nodes results in an intense inflammatory reaction with granulomatous changes and necrosis95. Wolbachia bacterial endosymbionts are required for the worms’ development, embryogenesis, and survival; Wolbachia also stimulates an innate and adaptive immune response that leads to expression of vascular endothelial growth factors (VEGFs) that promote lymphangiogenesis, lymphatic endothelial proliferation, and dilation of lymphatic vessels92.

Clinical Features There are acute, chronic, and asymptomatic forms of filariasis. Acute episodes of retrograde adenolymphangitis typically last up to one week and usually recur 1 to 10 times per year; the inguinal lymph nodes are most often involved. Early on, the affected body part appears clinically normal in between these episodes. Men with W. bancrofti infection often present with orchitis and epididymitis. Another disease manifestation is acute dermatolymphangioadenitis characterized by cutaneous or subcutaneous inflammatory plaques associated with ascending lymphangitis, regional lymphadenitis, and fever; this may result from a bacterial or fungal superinfection, often with an interdigital entry point97. Acute symptoms, which are thought to reflect a lack of tolerance to filarial antigens, are most common in recently infected young adults and older patients; children residing in endemic areas are often asymptomatic until they reach puberty, when they typically develop chronic manifestations98. After 10 to 15 years of infection, the clinical features of chronic disease, i.e. the sequelae of lymphatic obstruction due to both adult worms and granulomatous inflammation, are noted97. These include lymphedema, elephantiasis, hydroceles, and chyluria. In some communities in endemic regions, 40–60% of adult men have hydroceles. In sites of lymphedema and elephantiasis, the skin can be hyperkeratotic, verrucous, and fibrotic with soft tissue hypertrophy and redundant folds. Fissures, ulceration, and gangrene may also develop. Secondary bacterial and fungal infections are very common. There are two major reasons for the predilection of filariasis for the lower extremities and genitalia: (1) the female mosquito flies near the ground, thus it is more likely to bite the lower limbs, which is followed by retrograde involvement of the inguinal region; and (2) due to gravitational forces, the legs are at greater risk for venous hypertension and valvular incompetency and therefore more susceptible to the development of chronic lymphedema95. Tropical pulmonary eosinophilia occurs in some patients with filarial infections. Clinical findings include cough, wheezing, dyspnea, chest pain, and fever accompanied by marked eosinophilia and pulmonary infiltrates. This may progress to restrictive pulmonary disease99. Travelers to endemic areas who became infected do not manifest the classic findings of filariasis. Instead, they have a hyperresponsive clinical presentation, known as “expatriate syndrome”, with more intense inflammatory reactions to the filarial parasites. Clinical findings include lymphangitis, lymphadenitis, and genital pain from the associated lymphatic inflammation, as well as urticaria, nonspecific cutaneous eruptions, and peripheral eosinophilia80.

or test strips are typically utilized92. Similar tests are not currently available for Malayan filariasis, which can be diagnosed using a dipstick test for IgG4 antibody specific for the Brugia antigen BmR1. Alternatively, the diagnosis can be established by the demonstration of microfilariae in the blood, urine, or other body fluids and tissues, or by the identification of adult worms100,101 (Fig. 83.32). Visualization of motile adult worms may be possible using ultrasound to evaluate the infected lymphatics. As the parasite exhibits a nocturnal periodicity in humans, 10 p.m. to 2 a.m. is the optimal time period for collection and direct smear of blood or other fluids. The use of filters with a pore size of 3 microns has improved the rate of detection of microfilariae in the blood and urine. However, parasite detection is not a particularly reliable method because many symptomatic patients are amicrofilaremic. Species-specific PCR-based assays have been developed and are utilized in research studies on filariasis102. Peripheral eosinophilia and elevated serum IgE are very common laboratory findings. In addition, more than 50% of microfilaremic patients with W. bancrofti infections have hematuria and/or proteinuria98.

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Pathogenesis

Differential Diagnosis The differential diagnosis depends upon the stage of the infection. Acute infection may be misdiagnosed as a bacterial lymphangitis. Lymphedema and elephantiasis have multiple possible etiologies, including recurrent bacterial lymphangitis, severe venous hypertension, lymph node dissections, podoconiosis, Milroy disease, and Klippel– Trenaunay syndrome103 (see Ch. 105).

Treatment The drug of choice is diethylcarbamazine, which is active against microfilariae but has a limited effect on adult worms. The usual course for filariasis patients is 6 mg/kg/day for 12 days92. Mass drug administration programs providing at-risk individuals yearly single doses of diethylcarbamazine represent the basis of strategies to eradicate filariasis from endemic countries. Doxycycline (200 mg/day for 4–8 weeks) targeting the Wolbachia endosymbiont can also eliminate microfilariae, kill adult worms, and improve lymphatic drainage. During the treatment period, antihistamines and corticosteroids may be useful in decreasing the allergic reaction that may result from massive disintegration of microfilariae. Because severe reactions may follow the administration of diethylcarbamazine in patients who have loiasis or onchocerciasis, it is important to exclude other helminthic diseases before instituting therapy103. Other management strategies include elevation of the affected body part, compression stockings, other antiinflammatory drugs, treatment of secondary infections, and protection of the affected area from trauma103.

Diagnosis Detection of circulating filarial antigen is now the preferred method for diagnosis of Bancroftian filariasis; immunochromatographic card tests

Fig. 83.32 Histopathology of filariasis. Dilated lymphatic with a mature adult worm and surrounding enlarged inguinal lymph  

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SCHISTOSOMIASIS AND SWIMMER’S ITCH

DISTRIBUTION OF SCHISTOSOMIASIS

Synonyms:  ■ Schistosomiasis: bilharziasis ■ Swimmer’s itch: clam digger’s itch

Key features ■ Schistosomiasis is a trematode (fluke) infection caused by five species of anthropophilic schistosomes, each with a specific geographic distribution and distinct intermediate host (snails) ■ The disease is most commonly seen in Africa, the Far and Middle East, and South America ■ Clinical manifestations include cercarial dermatitis, Katayama fever, and chronic fibro-occlusive disease involving the liver, intestine, and urinary tract ■ The cercariae of more than 20 species of animal schistosomes may penetrate human skin and cause a transient dermatitis called swimmer’s itch

Schistosoma mansoni Schistosoma intercalatum

Introduction Schistosomiasis is a trematode (fluke) infection endemic to the tropics and subtropics caused by members of the superfamily Schistosomatidea104. The disease has a worldwide distribution, affecting more than 200 million people in over 75 countries. Human disease can be caused by five schistosome species, most often Schistosoma haematobium, which infects the urinary system, and S. japonicum and S. mansoni, which infect the gastrointestinal tract104. In addition, when the cercariae of other species that usually infect birds and mammals penetrate human skin, they can evoke “swimmer’s itch”, a local inflammatory response associated with marked pruritus.

Schistosoma haematobium Schistosoma japonicum Schistosoma mekongi

Fig. 83.33 Distribution of schistosomiasis. Adapted from Peters W, Pasvol G. Tropical Medicine and Parasitology, 6th edition. London: Mosby, 2007.  

Epidemiology Schistosomes have a two-host life cycle (see Fig. 83.25). Snails serve as the intermediate host, while the definitive host is species-dependent. Humans are the major definitive host for five schistosome species104, each of which has a specific geographic distribution (Fig. 83.33): S. mansoni occurs in Africa, South America, and the Caribbean; S. japonicum in Japan, China, and the Philippines; S. haematobium in Africa and the Middle East; S. mekongi in Southeast Asia; and S. intercalatum in West and Central Africa. The geographic distribution of schistosomiasis has changed significantly in recent decades. It has been nearly eradicated from Japan and the Caribbean islands, and the transmission cycle has been interrupted in North Africa, the Philippines, Saudi Arabia, and Venezuela. However, environmental changes related to water resource development and population movement have led to spread of the disease to previously non-endemic areas such as sub-Saharan Africa. Schistosomiasis is now present in and around several major cities in northeastern Brazil and is a major public health problem in certain regions of China. Swimmer’s itch (cercarial dermatitis) is due to over 20 species of schistosomes that usually infect birds and mammals (e.g. Trichobilharzia, Gigantobilharzia, Ornithobilharzia spp.). It is a cutaneous disease with distribution on every continent except Antarctica. In the US, it occurs most often in the north central states. Outbreaks of swimmer’s itch are episodic.

Pathogenesis

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Adult worms live in the venous system of the liver, rectum, or urinary bladder of their definitive host. The eggs penetrate the rectum or bladder and are passed into the feces or urine (see Fig. 83.25). In freshwater environments, the eggs hatch and release miracidia that penetrate the body of a snail, which acts as an intermediate host. For each schistosome species, a specific snail species acts as an intermediate host. In the snail, the miracidia develop into cercariae, the infective forms that can penetrate human skin on contact105.

The species responsible for swimmer’s itch complete their life cycle in birds and animals, including ducks, cows, sheep, and rodents. In contrast to human schistosomes, which cause systemic disease, the cercariae of animal schistosomes die after penetration into human skin, inducing only a local inflammatory reaction. Because humans cannot support the development of these schistosomes, they represent incidental, “dead-end” hosts104–106.

Clinical Features The cutaneous manifestations produced by the anthropophilic species of schistosomes can be classified into five categories: cercarial dermatitis, Katayama fever, late nonspecific allergic dermatitis, perigenital infiltrative granulomas, and extragenital infiltrative lesions107–109. Cercarial dermatitis is associated with cutaneous penetration by the cercariae. Though fairly common, patients rarely present with this transient, erythematous, pruritic papular or urticarial eruption at the site of inoculation. The reaction is relatively nonspecific and is more severe with S. japonicum and S. mansoni infections. Within hours of contact, macules develop and then either disappear or, more commonly, are replaced by small pruritic papules that may persist for a few days105. In some patients, a systemic allergic reaction (Katayama fever) occurs during the acute phase of a moderate or heavy infection. Affected individuals have an acute onset of fever, chills, sweats and headaches, in association with peripheral blood eosinophilia and urticaria. Katayama fever is seen most commonly with S. japonicum infections and is due to circulating immune complexes. Approximately 4 to 6 weeks later, some patients experience another transient cutaneous reaction with nonspecific findings ranging from urticarial or purpuric lesions to periorbital edema106,107,109. Bilharziasis cutanea tarda is characterized by papular, granulomatous, or verrucous lesions on genital and perineal skin secondary to the deposition of ova within dermal vessels in this area106,109. Occasionally, “ectopic” cutaneous lesions have been observed due to inflammatory

Pathology Histologically, cercarial dermatitis is characterized by spongiosis and a mixed inflammatory infiltrate composed of histiocytes, lymphocytes, neutrophils, and eosinophils. Edema is present in the dermis. Genital and perineal lesions of bilharziasis cutanea tarda show hyperkeratosis and acanthosis and occasionally prominent pseudoepitheliomatous hyperplasia. The dermis may contain numerous ova, which can be associated with a granulomatous reaction. “Ectopic” extragenital lesions contain ova in the superficial dermis associated with granuloma formation.

Differential Diagnosis The diagnosis of cercarial dermatitis or swimmer’s itch requires a history of exposure to contaminated water. The lesions may be confused with arthropod bites, but the distribution is clearly distinct from that of seabather’s eruption, which affects areas under the swimsuit. The differential diagnosis of anogenital and ectopic cutaneous ova deposition includes secondary syphilis (in particular the granulomatous form), condylomata acuminata, cutaneous Crohn disease, granuloma inguinale, and lichen planus.

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83 Protozoa and Worms

reactions to deposited ova. They have been described as hyperpigmented lichenoid papules in several patients and may have a zosteriform distribution on the trunk107. Systemically, chronic infections with S. mansoni and S. japonicum are associated with hepatic fibrosis and cirrhosis as a reaction to the ova; portal hypertension, including ascites and esophageal varices; and splenomegaly. Additional findings include colonic polyps (which contain ova) and granulomas around ova in the liver, lung, and colon (Hoeppli reaction). Urogenital infections with S. haematobium can lead to polyp­ oid lesions composed of numerous ova, fibrosis, and calcification. Calcified ova may be seen through the atrophic epithelium, leading to “sandy patches” that are pathognomonic of schistosomiasis on cystoscopy110. Additionally, the presence of numerous ova can lead to obstruction of the urinary tract and hydronephrosis. Carcinoma of the bladder is a life-threatening complication. Lesions of swimmer’s itch have an appearance similar to that of cercarial dermatitis, i.e. pruritic papules at sites of inoculation (Fig. 83.34). As a result, areas of skin covered by clothing are spared111. The eruption may last for days but is self-limited.

Treatment Praziquantel is an antihelminthic agent that is safe and effective against all five human schistosomal species114. The recommended regimen is 40 mg/kg (for S. mansoni, S. haematobium, and S. intercalatum) or 60 mg/kg (for S. japonicum and S. mekongi) divided into 2–3 oral doses administered over one day113. A single 40 mg/kg dose is used in massive population control programs, with an efficacy of 65–95%. Retreatment in 4 to 6 weeks can improve the cure rate113. Side effects are mild and include abdominal discomfort, fever, and headache. Although topical remedies (e.g. phenolized calamine) and antihistamines have been recommended for swimmer’s itch, no controlled studies have defined the most effective therapy111,115. If left untreated, the acute episode resolves spontaneously within 7–10 days. The most effective way to prevent swimmer’s itch is to avoid lakes and bodies of fresh water known to be infested, especially those periods of the year when cercariae are most plentiful, i.e. the early and mid summer in temperate regions.

CYSTICERCOSIS AND ECHINOCOCCOSIS

Diagnosis The diagnosis is usually established by microscopic detection of eggs in the urine or feces. In the case of S. japonicum and S. mansoni infections, microscopic evaluation of mucosal biopsy specimens may point to the diagnosis. Serologic tests (e.g. ELISA) can detect IgG, IgM, and IgE against worm and egg antigens. Monoclonal antibody-based assays that detect circulating antigens, such as the urine circulating cathodic antigen (CCA) dipstick, also represent sensitive and specific methods for establishing the diagnosis as well as assessing response to therapy and cure112. In addition, sensitive and specific PCR-based tests have been developed for the detection of schistosome DNA in feces, urine, and serum113.

Fig. 83.34 Swimmer’s itch. Numerous edematous dark red papules on the feet and ankles. Courtesy, Kalman  

Synonyms:  ■ Echinococcosis: hydatidosis, hydatid disease

Key features ■ Cestodes (tapeworms) that commonly affect animals (e.g. Taenia solium, Echinococcus granulosus) can also infect humans ■ Cutaneous cysticercosis is characterized by papules and nodules that are usually multiple and asymptomatic; the brain (neurocysticercosis), eye, heart, other muscles, and peritoneal cavity may also be affected ■ In echinococcosis, the liver and lungs are the major sites of involvement, with development of one or more hydatid cysts. Allergic symptoms, such as urticaria, asthma and anaphylaxis, are uncommon

Watsky, MD.

Introduction In the two stages of their life cycle (adult and larval), cestodes (tapeworms) can cause disease in humans. The adult worms reside in the definitive host’s intestines (including humans) and are often associated with minimal clinical manifestations (see Fig. 83.28). In intermediate hosts, the larval stage can lead to clinical disease, e.g. cysticercosis or echinococcosis in humans116.

Epidemiology The four most common human cestodes (tapeworms) are Taenia solium (pork tapeworm), Taenia saginata (beef tapeworm), Diphyllobothrium latum (fish tapeworm) and Hymenolepis nana. In humans, they cause primarily gastrointestinal symptoms, but the larval stage of T. solium also causes cysticercosis. Larvae of T. solium and T. saginata, respectively, can cause cysticercosis in pigs and cattle. Cysticercosis has a worldwide distribution, affecting more than 50 million people, and it is more common in rural areas. Endemic regions include Central and South America, sub-Saharan Africa, India, and East Asia117,118. Echinococcosis is a zoonosis caused by Echinococcus species, the definitive hosts of which are dogs and other members of the family

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Canidae. Humans are only infected by the larval stage, i.e. they are intermediate hosts, and develop cysts within viscera. Most human disease is due to larval stages of E. granulosus and E. multilocularis. Echinococcosis occurs in tropical and subtropical countries worldwide, primarily in sheep- and cattle-raising areas. Endemic regions include the southern province of Brazil, the Middle East, parts of Asia, and Northern and East Africa. It is particularly common in Lebanon and Greece116,117.

Pathogenesis The adult tapeworm can reach a length of up to 30 feet in the intestinal tract of its definitive host. Its body has two main parts: a single head (scolex) for attachment to the host and many proglottids, each of which has male and female reproductive organs. Fertilized eggs accumulate in large numbers inside the uterine horns of the proglottids; the eggs can be released directly into the host’s intestine or the entire gravid terminal proglottid can be excreted by the host116. Both eggs and proglottids are found in the host’s stool (see Fig. 83.28). When eggs or proglottids are ingested by a susceptible intermediate host, they develop into larvae called oncospheres. In humans, onchospheres can develop into encysted forms (cysticerci in cysticercosis) or generate germinal tissue with a cyst (hydatid in echinococcosis). Subsequent ingestion of cyst-containing tissues by a susceptible definitive host allows the development of the larvae into adults and completion of the life cycle119. Humans are the only definitive host for T. saginata (beef tapeworm) and T. solium (pork tapeworm), becoming infected with the adult form after eating poorly cooked muscle of a diseased animal (see Fig. 83.28). Humans are also intermediate hosts of T. solium, developing cysticercosis as a result of ingestion of food or water contaminated with infected human feces or via autoinfection from anus to mouth. In contrast, humans are only intermediate hosts of E. granulosus (as are sheep and cattle) as a result of ingesting contaminated dog feces. Dogs are the definitive host of E. granulosus, becoming infected with adult tapeworms after eating infected beef or lamb. When humans are infected by the adult stage of T. solium (i.e. are the definitive host), the tapeworms within the intestine usually cause no morphologically identifiable change in the mucosa or submucosa. Some patients may develop moderate peripheral eosinophilia. Immunity plays only a limited role during infections with the adult stage and has little effect on the duration of infection or on the susceptibility to reinfection. However, immunity plays an important role when humans are the intermediate host, i.e. develop cysticercosis. After penetrating the host’s intestinal wall and disseminating, the oncosphere matures rapidly and by 10 weeks is fully developed. The cyst that forms is usually 0.5–1.0 cm in diameter and remains viable for 3 to 5 years before degenerating. At this time, the inflammatory response is markedly intensified, and calcification also often takes place117,120,121. The signs and symptoms triggered by these reactions depend on the location of the cysts. For example, if there are cysts at the base of the brain, a cysticercic meningitis may ensue. In brain tissue itself, cysts that calcify may cause seizures. When humans ingest the eggs of E. granulosus, oncospheres penetrate the mesenteric vessels. While the majority are trapped by the liver sinusoids, some bypass the liver and are carried in the bloodstream to other organs and tissues. Within hours, an inflammatory response may be seen. If the larvae survive, they develop into hydatid cysts within 5 days. Cell-mediated immunity controls dissemination during the early phase of infection.

Clinical Features In cysticercosis, cysts can develop in almost any organ or tissue in the body. Skin involvement presents as subcutaneous papulonodules that

are more often palpable than visible120,122,123. They are usually multiple and asymptomatic. The brain, eye, heart, other muscles, and peritoneal cavity may also be affected. Subcutaneous involvement is recognized in ∼1–20% of patients122,123, and it is said to be more common in Asia and Africa than in Latin America124. However, in a Brazilian study of 30 patients with cysticercosis, 90% had cysts in the subcutaneous tissue, skeletal muscle, or mucous membranes, while the CNS was affected in humans

Reservoir

Humans

Antelope, cattle

Location

West/central regions of sub-Saharan Africa

Ethiopia, Uganda, Zambia, Botswana, Tanzania, Mozambique

Clinical presentation



Chancre uncommon Chronic neurologic symptoms • Posterior cervical (Winterbottom sign) and supraclavicular lymphadenopathy • Trypanids (10–50% of patients, especially if lightly pigmented skin)





Chancre common (75% of patients) • Acute neurologic symptoms • Axillary and epitrochlear lymphadenopathy • Trypanids common (especially if lightly pigmented skin) • Myocarditis/heart failure

Protozoa and Worms

COMPARISON BETWEEN WEST AFRICAN AND EAST AFRICAN TRYPANOSOMIASIS

A

Treatment   Hemolymphatic stage



  CNS involvement



Pentamidine



Suramin

Melarsoprol or eflornithine



Melarsoprol

eTable 83.1 Comparison between West African and East African trypanosomiasis.  

eFig. 83.1 Mucocutaneous leishmaniasis. There is edema and infiltration of the nose as well as focal deep ulceration of the vestibule and upper lip.  

B

eFig. 83.2 Immunostaining to detect Leishmania organisms. Demonstration of improved detection of Leishmania organisms via immunostaining with CD1a (A) as compared to H&E staining (B). Courtesy, Jennifer McNiff, MD.  

Courtesy, Omar P Sangüeza, MD.

eFig. 83.3 Chagas disease: apical aneurysm of the heart. Mural thrombi may be present at the apex of the left ventricle, with marked thinning of the ventricular wall (illuminated). With  

permission from Peters W, Pasvol G. Tropical Medicine and Parasitology, 6th edition. London: Mosby, 2007.

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eFig. 83.4 Chagas disease: radiograph of megaesophagus. Muscular degeneration and denervation of segments of the alimentary tract through destruction of the cells of Auerbach’s plexus cause megaesophagus, megastomach and megacolon, which can be detected radiologically. With

Infections, Infestations, and Bites



LIFE CYCLE OF TRICHINELLA SPIRALIS

permission from Peters W, Pasvol G. Tropical Medicine and Parasitology, 6th edition. London: Mosby, 2007.

eFig. 83.5 Life cycle of Trichinella spiralis. This nematode is a zoonotic infection that circulates between rats and various carnivores. Trichinosis in humans commonly results from eating raw or inadequately cooked pork products such as sausages. Infection is acquired by eating muscle containing encysted larvae which excyst in the small intestine and develop into adults. Mature females deposit larvae which migrate from the gastrointestinal tract through tissues to reach skeletal muscles in which they then encyst. With  

LIFE CYCLE OF TOXOCARA CANIS

permission from Peters W, Pasvol G. Tropical Medicine and Parasitology, 6th edition. London: Mosby, 2007.

Predation

Paratenic hosts Ingestion of embryonated eggs

Embryonation of eggs in soil

Eggs in feces

eFig. 83.6 Life cycle of Toxocara canis. This demonstrates the importance of transplacental transmission in maintaining canine infection, and the role of young dogs in transmitting infection to humans. With permission from Gillespie S.  

Migrating worms. In: Cohen J, Powderly W (eds). Infectious Diseases, 2nd edition. London: Mosby, 2004.

eFig. 83.7 Onchocerciasis. Diffuse lichenification and hyperpigmentation in a patient with intense pruritus. Focal areas of leukoderma are also present.  

Courtesy, Omar P Sangüeza, MD.

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eFig. 83.8 Living microfilariae of Onchocerca volvulus. After some time, actively moving microfilariae emerge from the skin snip into the surrounding saline, where they can be counted. With permission from Peters W, Pasvol G. Tropical Medicine  

and Parasitology, 6th edition. London: Mosby, 2007.

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72. Smith JD, Goette DK, Odom RB. Larva currens. Cutaneous strongyloidiasis. Arch Dermatol 1976;112:1161–3. 73. Bravo F, Sanchez MR. New and re-emerging cutaneous infectious diseases in Latin America and other geographic areas. Dermatol Clin 2003;21:655–68. 74. Veraldi S, Angileri L, Parducci BA, Nazzaro G. Treatment of hookworm-related cutaneous larva migrans with topical ivermectin. J Dermatolog Treat 2017;28:  263. 75. Herman JS, Chiodini PL. Gnathostomiasis, another emerging imported disease. Clin Microbiol Rev 2009;22:484–92. 76. Moore DA, McCroddan J, Dekumyoy P, et al. Gnathostomiasis: an emerging imported disease. Emerg Infect Dis 2003;9:647–50. 77. Zambrano-Zaragoza JF, Durán-Avelar Mde J, Messina-Robles M, et al. Characterization of the humoral immune response against Gnathostoma binucleatum in patients clinically diagnosed with gnathostomiasis. Am J Trop Med Hyg 2012;86:  988–92. 78. Laga AC, Lezcano C, Ramos C, et al. Cutaneous gnathostomiasis: report of 6 cases with emphasis on histopathological demonstration of the larva. J Am Acad Dermatol 2013;68:301–5. 79. Strady C, Dekumyoy P, Clement-Rigolet M, et al. Long-term follow-up of imported gnathostomiasis shows frequent treatment failure. Am J Trop Med Hyg 2009;80:33–5. 80. Rehmus W, Nguyen J. Nematodal helminths: onchocerciasis. In: Tyring S, Lupi O, Hengge U, editors. Tropical dermatology. London: Elsevier; 2006. p.   62–7. 81. Stingl P. Onchocerciasis: developments in diagnosis, treatment and control. Int J Dermatol 2009;48:  393–6. 82. Hamada N, Fouque F. Black flies (Diptera: Simuliidae) of French Guyana: cytotaxonomy and a preliminary list of species. Mem Inst Oswaldo Cruz 2001;96:  955–9. 83. Gustavsen K, Hopkins A, Sauerbrey M. Onchocerciasis in the Americas: from arrival to (near) elimination. Parasit Vectors 2011;4:205. 83a.  Zarroug IM, Hashim K, El Mubark WA, et al. The first confirmed elimination of an onchocerciasis focus in Africa: Abu Hamed, Sudan. Am J Trop Med Hyg 2016;95:1037–40. 84. Tamarozzi F, Halliday A, Gentil K, et al. Onchocerciasis: the role of Wolbachia bacterial endosymbionts in parasite biology, disease pathogenesis, and treatment. Clin Microbiol Rev 2011;24:459–68. 85. Stingl P. Onchocerciasis: clinical presentation and host parasite interactions in patients of southern Sudan. Int J Dermatol 1997;36:23–8. 86. Murdoch ME, Hay RJ, Mackenzie CD, et al. A clinical classification and grading system of the cutaneous changes in onchocerciasis. Br J Dermatol 1993;129:260–9.

87. Vernick W, Turner SE, Burov E, Telang GH. Onchocerciasis presenting with lower extremity hypopigmented macules. Cutis 2000;65:293–7. 88. Studeman K, Fishback JL, Connor DH. Onchocerciasis. In: Connor DH, Chandler FW, Schwartz DA, editors. Pathology of infectious diseases, vol. II. Stamford: Appleton & Lange; 1997. p. 1505–26. 89. Rosenblatt JE. Laboratory diagnosis of infections due to blood and tissue parasites. Clin Infect Dis 2009;49:1103–8. 90. Ayong LS, Tume CB, Wembe FE, et al. Development and evaluation of an antigen detection dipstick assay for the diagnosis of human onchocerciasis. Trop Med Int Health 2005;10:228–33. 91. Burnham G. Ivermectin treatment of onchocercal skin lesions: observations from a placebo-controlled, double-blind trial in Malawi. Am J Trop Med Hyg 1995;52:270–5. 92. Taylor MJ, Hoerauf A, Bockarie M. Lymphatic filariasis and onchocerciasis. Lancet 2010;376:1175–85. 93. Turner JD, Tendongfor N, Esum M, et al. Macrofilaricidal activity after doxycycline only treatment of Onchocerca volvulus in an area of Loa loa co-endemicity: a randomized controlled trial. PLoS Negl Trop Dis 2010;4:e660. 94. African Programme for Onchocerciasis Control: meeting of National Onchocerciasis Task Forces, September 2013. Wkly Epidemiol Rec 2013;88:  533–44. 95. Kalungi S, Tumwine LK. Nematodal helminths: filariasis. In: Tyring S, Lupi O, Hengge U, editors. Tropical dermatology. London: Elsevier; 2006. p. 57–61. 96. Ivoke N. Rural bancroftian filariasis in northwestern Cameroon: parasitological and clinical studies. J Commun Dis 2000;32:254–63. 97. Nutman TB. Insights into the pathogenesis of disease in human lymphatic filariasis. Lymphat Res Biol 2013;11:144–8. 98. Díaz-Menéndez M, Norman F, Monge-Maillo B, et al. Filariasis in clinical practice]. Enferm Infecc Microbiol Clin 2011;29(Suppl. 5):27–37. 99. Boggild AK, Keystone JS, Kain K. Tropical pulmonary eosinophilia: a case series in a setting of nonendemicity. Clin Infect Dis 2004;39:1123–8. 100. Dey P, Walker R. Microfilariae in a fine needle aspirate from a skin nodule. Acta Cytol 1994;38:114–15. 101. Denham DA. The diagnosis of filariasis. Ann Soc Belg Med Trop 1975;55:517–24. 102. Tang TH, López-Vélez R, Lanza M, et al. Nested PCR to detect and distinguish the sympatric filarial species Onchocerca volvulus, Mansonella ozzardi and Mansonella perstans in the Amazon Region. Memórias do Instituto Oswaldo Cruz 2010;105:823–8. 103. Ottesen EA. Filariasis now. Am J Trop Med Hyg 1989;41:9–17. 104. Leutscher P, Magnussen P. Trematodes. In: Tyring S, Lupi O, Hengge U, editors. Tropical dermatology. London: Elsevier; 2006. p. 85–91.

105. Stirewald MA, Hackey JR. Penetration of host skin by cercariae of Schistosoma mansoni. I. Observed entry into skin of mouse, hamster, rat, monkey and man. J Parasitol 1956;42:565–80. 106. Gonzales E. Schistosomiasis, cercarial dermatitis, and marine dermatitis. Dermatol Clin 1989;7:291–300. 107. Amer M. Cutaneous schistosomiasis. Dermatol Clin 1994;12:713–17. 108. Farrell AM. Ectopic cutaneous schistosomiasis: extragenital involvement with progressive upward spread. Br J Dermatol 1996;135:110–12. 109. Davis-Reed L, Theis JH. Cutaneous schistosomiasis: report of a case and review of the literature. J Am Acad Dermatol 2000;42:678–80. 110. Torres VM. Dermatologic manifestations of Schistosoma mansoni. Arch Dermatol 1976;11: 539–42. 111. Mulvihill CA, Burnett JW. Swimmer’s itch: a cercarial dermatitis. Cutis 1990;46:211–13. 112. Elliott DE. Schistosomiasis: pathophysiology, diagnosis and treatment. Gastroenterol Clin North Am 1996;25:599–602. 113. Gray DJ, Ross AG, Li YS, et al. Diagnosis and management of schistosomiasis. BMJ 2011;342:  d2651. 114. King CH, Mahmoud AF. Drugs five years later: praziquantel. Ann Intern Med 1989;110:290–6. 115. Hoeffler DF. Cercarial dermatitis. Arch Environ Health 1974;29:225–9. 116. Cook GC. Gastrointestinal helminth infections. Trans R Soc Trop Med Hyg 1986;80:675–8. 117. Machado-Pinto J. Cestodes. In: Tyring S, Lupi O, Hengge U, editors. Tropical dermatology. London: Elsevier; 2006. p. 81–3. 118. Sammarchi L, Strohmeyer M, Bartalesi F, et al. COHEMI Project Study Group.Epidemiology and management of cysticercosis and Taenia solium taeniasis in Europe, systematic review 1990-2011. PLoS ONE 2013;8:e69537. 119. Smyth JD, Heath DD. Pathogenesis of larval cestodes in mammals. Helm Abstr 1970;39:1–23. 120. Falanga V, Kapoor W. Cerebral cysticercosis: diagnostic value of subcutaneous nodules. J Am Acad Dermatol 1985;12:304–7. 121. Vianna LG, Macedo V, Costa JM. Musculocutaneous and visceral cysticercosis: a rare disease? Rev Inst Med Trop Sao Paulo 1991;33:129–36. 122. Vidal S. Comunicación de un caso de cisticercosis subcutánea. Rev Chil Infectol 2013;30:323–5. 123. Veena G, Shon GM, Usha K, et al. Extracranial cysticercosis of the parotid gland: a case report with a review of the literature. J Laryngol Otol 2008;122:1008–11. 124. García HH, Gonzalez AE, Evans CA, et al. Taenia solium cysticercosis. Lancet 2003;362:547–56. 125. Okelo GBA. Hydatid disease: research and control in Turkana. III. Albendazole in the treatment of inoperable hydatid disease in Kenya – a report of 12 cases. Trans R Soc Trop Med Hyg 1986;80:193–5.

INFECTIONS, INFESTATIONS, AND BITES SECTION 12

Infestations Craig N. Burkhart, Craig G. Burkhart and Dean S. Morrell

Chapter Contents Scabies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1503 Head lice . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1507 Crab lice . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1510 Body lice . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1511 Tungiasis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1512 Cutaneous myiasis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1512

SCABIES Synonyms:  ■ Itch mite infestation ■ “Seven-year itch”

Key features ■ Human scabies is a pruritic condition caused by infestation with the host-specific mite Sarcoptes scabiei var. hominis, which lives its entire life within the epidermis ■ Although the scabies mite is not a known vector for any systemic disease, secondary bacterial infections with Streptococcus pyogenes or Staphylococcus aureus may develop ■ Transmission typically occurs via direct close contact with an infested person; fomite transmission is also possible, especially with the crusted variant ■ Permethrin 5% cream is currently the first-line treatment for classic scabies

Introduction The scabies mite continues to plague all countries of the world. An estimated 300 million individuals are affected. Pruritus associated with this infestation is usually severe, especially at night, and treatment requires prescription scabicidal therapy.

History Scabies has been a common companion of the human species for over 2500 years1.

Epidemiology Scabies is a worldwide problem and all ages, races, and socioeconomic groups are susceptible. Environmental factors that promote its spread include overcrowding, delayed treatment, and lack of public awareness of the condition. There is considerable variation in the prevalence of scabies, with rates in low-income countries ranging from 4% to 100%1,2. Higher incidences occur with overcrowding related to natural disasters, wars, economic depression, and refugee camps1,2. Scabies can be transmitted directly by close personal contact, sexual or otherwise, or indirectly via fomites. Prevalence is higher in children and people who are sexually active, and spread of the infestation among family members

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and other close contacts is common2. The scabies mite is not a known vector for systemic disease. Crusted scabies (formerly called Norwegian scabies) is found in individuals with compromised immune systems, such as the elderly, people infected with HIV or human T-cell lymphotropic virus type 1 (HTLV1), and solid organ transplant recipients; it can also occur in those with decreased sensory functions and/or ability to scratch (e.g. patients with leprosy or paraplegia). These patients may experience minimal pruritus despite their infestation with a large number of mites and are highly contagious3.

Pathogenesis The species-specific, eight-legged mite Sarcoptes scabiei var. hominis causes human scabies (Fig. 84.1). The Sarcoptes mites that cause infestations in animals (e.g. S. scabiei var. canis in dogs) are not a source of human infestation, but they can produce bite reactions (see Ch. 85). The scabies mite is 0.35 × 0.3 mm in size and too small to be seen by the naked eye. The entire 30-day life cycle of these mites is completed within the epidermis (Fig. 84.2). Each day a female mite lays 3 eggs, which require approximately 10 days to mature. The number of mites living on an infested host can vary greatly, although there are usually fewer than a hundred and often no more than 10–15. However, patients with crusted scabies may have thousands of mites on their skin surface, and live mites can be recovered in debris from sheets, the floor, curtains, and chairs in the environment of affected individuals4. Scabies mites usually live 3 days or fewer off a human host, but those from patients with crusted scabies may live up to 7 days by feeding on sloughed skin. The incubation period before symptoms develop can range from days to months. In first-time infestations, it usually takes 2–6 weeks before the host’s immune system becomes sensitized to the mite or its by-products, resulting in pruritus and cutaneous lesions. In contrast, a subsequent infestation often becomes symptomatic within 24–48 hours. Asymptomatic scabies-infested individuals are not uncommon, and they can be considered “carriers”4.

Clinical Features The epidemiologic history (e.g. pruritus in household members or other close personal contacts), the distribution and types of lesions, and pruritus form the basis of the clinical diagnosis. The intense pruritus is classically accentuated at night and by a hot bath or shower. Pruritus may be present before any overt physical signs appear. Cutaneous lesions are symmetrical, typically involving the interdigital web spaces of the hands, flexural aspect of the wrists, axillae, posterior auricular area, waist (including the umbilicus), ankles, feet, and buttocks. In men, penile and scrotal lesions are common, while in women, the areolae, nipples, and vulvar area are often affected. In infants, the elderly and immunocompromised hosts, all skin surfaces are susceptible, including the scalp and face1,4. Typically, small erythematous papules are present in association with a variable degree of excoriation (Fig. 84.3). Vesicles, indurated nodules, eczematous dermatitis, and secondary bacterial infection are also common. The pathognomonic sign is the burrow, representing the tunnel that a female mite excavates while laying eggs. Clinically, the burrow is wavy, thread-like, grayish-white, and 1–10 mm in length. Many patients, however, do not have obvious burrows on inspection, especially in warm climates. Acral vesiculopustules can represent a clue to the diagnosis of scabies in infants. Crusted scabies often manifests with marked hyperkeratosis

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Infestations occur worldwide and are frequently encountered in the practice of dermatology. The most common human infestations, scabies and head lice, are pruritic conditions caused by host-specific mites living within the epidermis and wingless bloodsucking insects living on the hairs of the scalp, respectively. In both of these entities, tolerance to standard therapies has been observed and newer treatment approaches have been developed. Crab lice infest the pubic region as well as other hair-bearing sites such as the beard, eyelashes and axillae. Body lice are typically found in the seams of clothing and can transmit infections including epidemic typhus, trench fever, and relapsing fever. Tungiasis and cutaneous myiasis represent additional infestations discussed in this chapter.

scabies, permethrin, ivermectin, head lice, crab lice, body lice, tungiasis, cutaneous myiasis

CHAPTER

84 Infestations

ABSTRACT

non-print metadata KEYWORDS:

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SECTION

12 Infections, Infestations, and Bites

LIFE CYCLE OF THE SCABIES MITE (Sarcoptes scabiei var. hominis)

Egg 1–2 days Female mite burrows and lays egg

2–2.5 days

Larva Looks like an adult but has 3 pairs of legs instead of 4

15 minutes copulation occurs once per female mite lifetime

1 day spent on skin then burrows back into skin 3–4 days

Fig. 84.1 Female scabies mite with eggs and scybala in skin scrapings. Note the mite’s flattened, oval body and eight legs.  

Protonymph

3 days

Adult scabies mite

2–3 days

Tritonymph

Fig. 84.2 Life cycle of the scabies mite (Sarcoptes scabiei var. hominis).  

A

B

C

D

E

F

Fig. 84.3 Scabies. A, B Erythematous papules, linear burrows, areas of crusting and acral vesiculopustules in two infants with scabies. C Close-up of a linear burrow. D, E Penile involvement with erythematous papules and nodules. F Nodular scabies in an infant. A, B, Courtesy, Julie V Schaffer, MD. E, Courtesy, Robert Hartman, MD.  

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F, Courtesy, Kalman Watsky, MD.

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Infestations

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Fig. 84.4 Crusted scabies. Scabies incognito in which a patient with impaired sensory function had an asymptomatic hyperkeratotic hand “rash”. Courtesy, Joyce  

Rico, MD.

Fig. 84.6 Scabies – histologic features. A mite is evident in the stratum corneum and an eosinophil-rich dermal infiltrate is present. Courtesy, Lorenzo Cerroni,  

MD.

84.6). Pink “pigtail”-like structures attached to the stratum corneum, which represent fragments of the adult mite exoskeleton, can serve as a clue to the diagnosis of scabies when entire mites, scybala, and eggs are not identified8.

Differential Diagnosis

Fig. 84.5 Microscopy of a skin scraping from a patient with scabies. Four mites, eggs and scybala are present. The mites blend in with the background scale, making them difficult to see.  

that favors acral sites including subungual areas (Fig. 84.4), but involvement may be widespread. Areas of affected skin have been referred to as pachyderma. Secondary bacterial infections with Staphylococcus aureus or Streptococcus pyogenes sometimes develop. In resource-poor countries with endemic scabies, post-streptococcal glomerulonephritis is a significant issue. Peripheral eosinophilia can be the primary sign of scabies in patients with disorders of keratinization. Confirmation of the diagnosis can be achieved by light microscopic examination of mineral oil preparations of skin scrapings (from infested areas) for adult mites, eggs, and/or fecal pellets (scybala; Fig. 84.5). A scalpel or curette may be used to obtain the skin sample5. Microscopic examination of transparent adhesive tape following its application to infested areas of skin represents another diagnostic technique6. Dermoscopy and confocal microscopy can prove useful for direct in vivo visualization of mites and eggs (see Fig. 0.43). A skin biopsy may confirm the clinical diagnosis, but only if the specimen obtained happens to contain the mite or its eggs. Often, however, the diagnosis simply rests on the clinical impression and response to treatment. The diagnostic potential of a serologic test that detects IgE specific for a recombinant S. scabiei antigen is under investigation7.

Pathology A patchy to diffuse infiltrate with prominent eosinophils as well as lymphocytes and histiocytes is noted in the reticular dermis. A transected scabies mite may occasionally be seen within the epidermis (Fig.

Unless burrows or (via dermoscopy) mites and eggs are noted clinically, a wide variety of pruritic skin diseases should be considered in the differential diagnosis. These include atopic, allergic contact, autosensitization (“id” reaction), and nummular dermatitis as well as arthropod bites, pyoderma, dermatitis herpetiformis, and bullous pemphigoid. Occasionally, scabies can mimic Langerhans cell histiocytosis clinically and histologically, as a dense infiltrate of Langerhans cells may be present. The clinical and histologic features of infantile scabies may also resemble findings in the inflammatory stage of incontinentia pigmenti. Acropustulosis of infancy can both mimic scabies and follow scabies as a hypersensitivity phenomenon.

Treatment Two topical treatments 1 week apart with a prescription antiscabetic medication are recommended (Table 84.1). The topical preparation is applied overnight to the entire body surface, from head to toe, in infants and the elderly. In other age groups, the face and scalp can be excluded from treatment. Special attention should be paid to the interdigital spaces, intergluteal cleft, umbilicus, and subungual areas. To reduce the potential for reinfestation by fomite transmission, at the time of each treatment, clothing, linens, and towels used within the previous week can be either washed in hot water and dried on high heat or stored in a bag for 10 days. The relatively common occurrence of asymptomatic mite carriers in households necessitates that all family members and other close contacts be treated simultaneously, even if they have not developed any pruritus or clinical signs. Pets cannot harbor human mites and do not have to be treated. Secondary bacterial infections need to be treated with appropriate antibiotics. Following successful treatment, pruritus and skin lesions can persist for 2–4 weeks or longer, especially for acral vesiculopustules in infants and nodules. This is referred to as “postscabetic” pruritus or dermatitis. Patients should be informed that such reactions do not imply treatment failure, but rather represent the body’s response to dead mites that are eventually sloughed off (within 2 weeks) along with normal epidermal exfoliation. Many patients, however, experience relief from pruritus within 3 days. The second application of topical medication is performed in order to reduce the potential for reinfestation from fomites as well as to ensure killing of any nymphs that may have survived within the semi-protective environment of the egg and subsequently hatched (see Fig. 84.2).

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12

TOPICAL AND ORAL TREATMENTS FOR SCABIES

FDA pregnancy category

Therapy

Administration

Concerns

Efficacy & resistance

Use in infants

Permethrin cream (5%)

Topically overnight on days 1 and 8

Allergic contact dermatitis in individuals with sensitivity to formaldehyde

Good, but some signs of tolerance developing

FDA approved for infants ≥2 months of age

B

Lindane lotion or cream (1%)

Topically overnight on days 1 and 8

Potential CNS toxicity, especially in individuals weighing 30 000 somatic single and tandem base substitution mutations, especially in lentigo maligna melanoma; the majority (~70%) are UV-signature mutations (C→T transition mutations). While the etiology of melanoma is clearly complex, these findings provide molecular evidence for a significant role for UV exposure. Since C→T transitions can be generated by UVB and UVA, it is not possible to conclude from these molecular fingerprints which wavelengths have caused these mutations. However, given the relative scarcity of mutations typically generated by oxidative DNA damage, including G→T transversions, it is unlikely that UV-induced oxidative processes make a significant contribution to melanoma formation. Both melanomas and melanocytic nevi have a high frequency of T→A mutations in BRAF at one particular site, leading to an amino acid substitution in the BRAF protein at position 600 which is most often a substitution of glutamic acid (E) for valine (V), i.e. V600E. Because these BRAF mutations have been found predominantly in melanomas from intermittently sun-exposed areas (and much less frequently in melanomas from unexposed areas or chronically UV-exposed areas), it has been suggested that this type of mutation is UV-induced59. However, such a mutation is not generated by any of the common types of UV-induced DNA lesions, and the pre-mutagenic lesion, i.e. the type of DNA damage that causes this type of mutation, remains elusive.

To ensure that most of the damage inflicted by sun exposure will not lead to the formation of skin cancer, UV-exposed cells have several lines of defense against the photocarcinogenesis cascade (Fig. 86.14). In order to prevent DNA damage as a consequence of UV exposure, the epidermis has constitutive as well as inducible melanin. It can increase its thickness (which reduces UV exposure in the basal layer), and there are anti-oxidative enzymes within the epidermis which quench reactive oxygen species and reduce the formation of oxidative DNA damage. Cellular melanin is a mixture of different polymerized pigments that absorb UV radiation (see Ch. 65). Illumination of the brown to black eumelanin generates the superoxide radical within the molecule, which is very rapidly scavenged. The red or yellow pheomelanin is a less effective radical scavenger; upon UV exposure, pheomelanin is degraded, with a net formation of superoxide. Therefore, pheomelanin is regarded as a photosensitizer, rather than a photoprotector like eumelanin. In order to prevent mutation formation after DNA damage has been introduced, cells have several different DNA repair systems (see above) as well as the ability to bypass DNA damage without inducing mutations. Cells also have the ability to halt proliferation (cell cycle arrest) in order to allow more time for repair, reducing the chance of replicating a damaged template, or they can die via apoptosis when they accrue overwhelming DNA damage. Of note, even after mutations have fixed the inflicted damage for the lifetime of the affected cells, the organism still removes most of these cells, e.g. via immune surveillance. Some of these protective mechanisms can be upregulated, facilitating an adaptive response to repeated UV “attacks”. These include pigmentation, skin thickening, and antioxidant enzymes. DNA excision repair can also be upregulated in an SOS-like response60. In contrast, immune surveillance is down-regulated following UV exposures (see above), likely contributing significantly to photocarcinogenesis. Exposure to UVA cannot be regarded as harmless, and dermatologists must warn not only against UVB but also UVA exposure. There are at least three areas where increased exposure to UVA might pose a public health risk:

1) Use of high-dose UVA emitters for cosmetic purposes in tanning parlors continues to be highly popular, in particular amongst female adolescents and young adults. A marked increase in melanoma incidence in Iceland has already been linked to the use of tanning parlors24. It is estimated that approximately 35 million Americans use tanning beds or sunlamps every year. 2) An increase in UVA exposure may result from the use of sunscreens. The latter are often used in order to prolong sun exposure61, and since broad-spectrum sunscreens still do not filter UVA as efficiently as UVB, an increase in UVA exposure may result as a consequence of sunscreen use62. 3) High-dose UVA1 phototherapy has been shown to be an effective treatment for atopic dermatitis, systemic sclerosis, cutaneous T-cell lymphoma, and other dermatoses. However, the long-term risks of this treatment have not been established. Considering the possible role of UVA in the development of cutaneous melanoma, one must weigh the risks and benefits of the use of high-dose UVA1, especially in children. In addition to the intrinsic protective mechanisms that counteract the chain of events leading to the formation of skin cancer, there are extrinsic protective agents and behaviors that can help individuals reduce their skin cancer risk (see Fig. 86.14). In order to prevent or reduce UV irradiation of the skin, one can limit outdoor activities, especially around midday, stay in the shade, wear protective clothing, and/or wear sunscreens. Sunscreens are topical preparations that attenuate UV radiation before it enters the skin, by reflection, absorption or both (see Ch. 132). They protect not only against the acute skin injury of sunburn, but also against UV-induced immune suppression, photoaging and skin cancer63. The sun protection factor (SPF) of sunscreens, which indicates by what factor sunburn is prevented by sunscreen use (see Ch. 132), does not correlate well with protection factors for other non-erythema endpoints. Therefore, the SPF cannot be regarded as a reliable guide to non-erythema and chronic endpoints64. A good sunscreen should provide broad-spectrum protection against UVB and UVA, ideally in a balanced way with equal protection against both UVA and UVB. Additionally, it should be photostable and have a

CHAPTER

86 Ultraviolet Radiation

PROTECTION AGAINST PHOTOCARCINOGENESIS

MECHANISMS THAT PROTECT AGAINST OR PREVENT THE PHOTOCARCINOGENESIS CASCADE AND DISORDERS THAT PREDISPOSE TO SKIN CANCER BECAUSE OF IMPAIRED INTRINSIC PROTECTIVE MECHANISMS Hereditary or acquired disorders with an increased risk for UV-induced skin cancer

Intrinsic protective mechanisms

Methods to prevent skin cancer

UV exposure Hair/fur

Alopecia, in particular androgenetic

Sun avoidance Protective clothing, hats

Pigmentation Epidermal thickening and hyperkeratosis Anti-oxidative enzymes

Oculocutaneous albinism

Broad-spectrum sunscreens Antioxidants

Xeroderma pigmentosum Xeroderma pigmentosum variant Familial melanoma

Increased DNA repair Increased apoptosis

Immunosuppression, e.g. solid organ transplant patients

Improve immune surveillance

DNA damage DNA repair High-fidelity translesional DNA synthesis Cell cycle arrest/apoptosis Mutations Removal of mutated cells (immune surveillance) Skin cancer

Fig. 86.14 Mechanisms that protect against or prevent the photocarcinogenesis cascade and disorders that predispose to skin cancer because of impaired intrinsic protective mechanisms. Several intrinsic mechanisms protect against the formation of skin cancer following UV exposure at different points of the photocarcinogenesis cascade of events. These mechanisms are impaired in disorders with increased risk for UV-induced skin cancer. Each step of the photocarcinogenesis cascade can be targeted for therapeutic modification and reduction of skin cancer risk.  

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comfortable vehicle to ensure its regular use. Filters that degrade with UV exposure lose their effectiveness and need reapplication. In addition, degradation products may induce further reactions, providing an explanation for why unstable sunscreen filters are more likely to cause photoallergic reactions65. Lastly, sunscreens should not be used to prolong sun exposure, because this would offset any protective effect and might even increase exposure to unfiltered or less-well-filtered wavelengths, such as UVA. In order to prevent oxidative damage – in particular, oxidative DNA damage – the addition of antioxidants to sunscreens has been advocated. However, their protective effects against any of the abovementioned endpoints have not been well established, or are marginal at best. In addition, the finding that oxidative DNA damage might not contribute significantly to UVA-induced mutagenesis (as was previously thought) brings into question whether antioxidants provide any

protection against skin cancer. Of note, reactive oxygen species are not only damaging to cells, but they also induce cellular responses that can protect against photocarcinogenesis, including induction of senescence via generation of the aging-associated protein progerin66. Thus, in theory, antioxidants could actually promote photocarcinogenesis. Topical application of DNA repair enzymes has been shown to increase DNA repair in skin cells and to accelerate removal of DNA photoproducts. In patients with XP, such applications have been reported to reduce the occurrence of actinic keratoses. This indicates that it may be possible to prevent the formation of mutations after the introduction of DNA photoproducts with the use of such “enzymatic sunscreens”. Similarly, it may be possible in the future to accelerate or improve the removal of damaged or mutated cells (e.g. by increasing apoptosis of damaged cells) or to improve immune surveillance (e.g. by vaccination).

REFERENCES 1. Anderson RR, Parrish JA. The optics of human skin. J Invest Dermatol 1981;77:13–19. 2. Bruls WAG, Slaper H, van der Leun JC, Berrens L. Transmission of human epidermis and stratum corneum as a function of thickness in the ultraviolet and visible wavelengths. Photochem Photobiol 1984;40:485–95. 3. Yarosh D, Dong K, Smiles K. UV-induced degradation of collagen I is mediated by soluble factors released from keratinocytes. Photochem Photobiol 2008;84:67–8. 4. Li WH, Pappas A, Zhang L, et al. IL-11, IL-1alpha, IL-6, and TNF-alpha are induced by solar radiation in vitro and may be involved in facial subcutaneous fat loss in vivo. J Dermatol Sci 2013;71:58–66. 5. Schwarz T, Beissert S. Milestones in photoimmunology. J Invest Dermatol 2013;133:E7–10. 5a.  Moore C, Cevikbas F, Pasolli HA, et al. UVB radiation generates sunburn pain and affects skin by activating epidermal TRPV4 ion channels and triggering endothelin-1 signaling. Proc Natl Acad Sci USA 2013;110:E3225–34. 6. Young AR, Chadwick CA, Harrison GI, et al. The similarity of action spectra for thymine dimers in human epidermis and erythema suggests that DNA is the chromophore for erythema. J Invest Dermatol 1998;111:982–8. 7. Palmer RA, Friedmann PS. Ultraviolet radiation causes less immunosuppression in patients with polymorphic light eruption than in controls. J Invest Dermatol 2004;122:291–4. 8. Lembo S, Fallon J, O’Kelly P, Murphy GM. Polymorphous light eruption and skin cancer prevalence: is one protective against the other? Br J Dermatol 2008;159:1342–7. 9. Halliday GM, Byrne SN, Damian DL. Ultraviolet A radiation: its role in immunosuppression and carcinogenesis. Semin Cutan Med Surg 2011;30:214–21. 10. Poon F, Kang S, Chien A. Mechanisms and treatments of photoaging. Photodermatol Photoimmunol Photomed 2015;31:65–74. 11. Gilchrest BA. Photoaging. J Invest Dermatol 2013;133:E2–6. 12. Moulin G, Thomas L, Vigneau M, Fiere A. A case of unilateral elastosis with cysts and comedones. Favre-Racouchot syndrome. Ann Dermatol Venereol 1994;121:721–3. 13. Gordon JR, Brieva JC. Images in clinical medicine. Unilateral dermatoheliosis. N Engl J Med 2012;366:e25. 14. Berneburg M, Grether-Beck S, Kurten V, et al. Singlet oxygen mediates the UVA-induced generation of the photoaging-associated mitochondrial common deletion. J Biol Chem 1999;274:15345–9. 15. Codriansky K, Quintanilla-Dieck MJ, Gan S, et al. Intracellular degradation of elastin by cathepsin K in skin fibroblasts – a possible role in photoaging. Photochem Photobiol 2009;85:1356–63. 16. Takeuchi H, Rünger TM. Longwave ultraviolet light induces the aging-associated progerin. J Invest Dermatol 2013;133:1857–62. 17. Krutmann J, Schroeder P. Role of mitochondria in photoaging of human skin: the defective powerhouse model. J Investig Dermatol Symp Proc 2009;14:44–9. 18. El Ghissassi E, Baan R, Straif K, et al. A review of human carcinogens – part D: radiation. Lancet Oncology 2009;10:751–2.

18a.  Martincorena I, Roshan A, Gerstung M, et al. Tumor evolution. High burden and pervasive positive selection of somatic mutations in normal human skin. Science 2015;348:880–6. 19. de Gruijl FR, Sterenborg HJ, Forbes PD, et al. Wavelength dependence of skin cancer induction by ultraviolet irradiation of albino hairless mice. Cancer Res 1993;53:53–60. 20. Rünger TM. The role of UVA in the pathogenesis of melanoma and non-melanoma skin cancer. Photodermatol Photoimmunol Photomed 1999;15:212–16. 21. Autier P, Dore JF, Eggermont AM, Coebergh JW. Epidemiological evidence that UVA radiation is involved in the genesis of cutaneous melanoma. Curr Opin Oncol 2011;23:189–96. 22. Gallagher RP, Spinelli JJ, Lee TK, et al. Tanning beds, sunlamps, and risk of cutaneous malignant melanoma. Cancer Epidemiol Biomarkers Prevention 2005;14:562–6. 23. Veierød MB, Weiderpass E, Thorn M, et al. A prospective study of pigmentation, sun exposure, and risk of cutaneous malignant melanoma in women. J Natl Cancer Inst 2003;95:1530–8. 24. Hery C, Tryggvadottir L, Sigurdsson T, et al. A melanoma epidemic in Iceland: possible influence of sunbed use. Am J Epidemiol 2010;172:762–7. 25. Lazovich D, Vogel RI, Berwick M, et al. Indoor tanning and risk of melanoma: a case-control study in a highly exposed population. Cancer Epidemiol Biomarkers Prev 2010;19:1557–68. 26. Noonan FP, Zaidi MR, Wolnicka-Glubisz A, et al. Melanoma induction by ultraviolet A but not ultraviolet B radiation requires melanin pigment. Nat Commun 2012;3:884. 27. Wang HT, Choi B, Tang MS. Melanocytes are deficient in repair of oxidative DNA damage and UV-induced photoproducts. Proc Natl Acad Sci USA 2010;107:12180–5. 28. Rünger TM. Is UV-induced mutation formation in melanocytes different from other skin cells? Pigment Cell Melanoma Res 2010;24:10–12. 29. Moan J, Grigalavicius M, Baturaite Z, et al. The relationship between UV exposure and incidence of skin cancer. Photodermatol Photoimmunol Photomed 2015;31:26–35. 30. Gilchrest BA, Eller MS, Geller AC, Yaar M. The pathogenesis of melanoma induced by ultraviolet radiation. N Engl J Med 1999;340:1341–8. 31. Cadet J, Sage E, Douki T. Ultraviolet radiation-mediated damage to cellular DNA. Mutat Res 2005;571: 3–17. 32. Young AR, Chadwick CA, Harrison GI, et al. The similarity of action spectra for thymine dimers in human epidermis and erythema suggests that DNA is the chromophore for erythema. J Invest Dermatol 1998;111:982–8. 32a.  Premi S, Wallisch S, Mano CM, et al. Photochemistry. Chemiexcitation of melanin derivatives induced DNA photoproducts long after UV exposure. Science 2015;347:842–7. 33. Perdiz D, Grof P, Mezzina M, et al. Distribution and repair of bipyrimidine photoproducts in solar UV-irradiated mammalian cells. J Biol Chem 2000;275:26732–42.

34. Rünger TM, Kappes UP. Mechanisms of mutation formation with long-wave ultraviolet light (UVA). Photodermatol Photoimmunol Photomed 2008;24:2–10. 35. Piette J, Merville-Louis MP, Decuyper J. Damages induced in nucleic acids by photosensitization. Photochem Photobiol 1986;44:793–802. 36. Danpure HJ, Tyrrell RM. Oxygen-dependance of near UV (365 nm) lethality and the interaction of near UV and x-rays in two mammalian cell lines. Photochem Photobiol 1976;23:171–7. 37. Kvam E, Tyrell RM. Induction of oxidative DNA base damage in human skin cells by UV and near visible radiation. Carcinogenesis 1997;18:2379–84. 38. Douki T, Reynaud-Angelin A, Cadet J, Sage E. Bipyrimidine photoproducts rather than oxidative lesions are the main type of DNA damage involved in the genotoxic effect of solar UVA radiation. Biochem 2003;42:9221–6. 39. Darr D, Fridovich I. Free radicals in cutaneous biology. J Invest Dermatol 1994;102:671–5. 40. Kielbassa C, Roza L, Epe B. Wavelength dependence of oxidative DNA damage induced by UV and visible light. Carcinogenesis 1997;18:811–16. 41. Rünger TM. C to T transition mutations are not solely UVB-signature mutations, because they are also generated by UVA. J Invest Dermatol 2008;128:2138–40. 42. Dunn J, Potter M, Rees A, Rünger TM. Activation of the Fanconi anemia/BRCA pathway and recombination repair in the cellular response to solar UV. Cancer Res 2006;66:11140–7. 43. Rizzo JL, Dunn J, Rees A, Rünger TM. No formation of DNA double-strand breaks and no activation of recombination repair with UVA. J Invest Dermatol 2011;131:1139–48. 44. de Boer J, Hoeijmakers JHJ. Nucleotide excision repair and human syndromes. Carcinogenesis 2000;21:453–60. 45. Kraemer KH, Lee MM, Scotto J. Xeroderma pigmentosum. Cutaneous, ocular, and neurologic abnormalities in 830 published cases. Arch Dermatol 1987;123:241–50. 46. Bootsma D. Nucleotide excision repair syndromes: xeroderma pigmentosum, Cockayne syndrome, and trichothiodystrophy. In: Vogelstein B, Kinzler KW, editors. The Genetic Basis of Human Cancer. New York: McGraw-Hill; 2002. p. 211–37. 47. Wei Q, Lee JE, Gershenwald JE, et al. Repair of UV light-induced DNA damage and risk of cutaneous malignant melanoma. J Natl Cancer Inst 2003;95:308–15. 48. Blankenburg S, Konig IR, Moessner R, et al. Assessment of 3 xeroderma pigmentosum group C gene polymorphisms and risk of cutaneous melanoma: a case-control study. Carcinogenesis 2005;26: 1085–90. 49. Torres SM, Luo L, Lilyquist J, et al. DNA repair variants, indoor tanning, and risk of melanoma. Pigment Cell Melanoma Res 2013;26:677–84. 50. Wei Q. Effect of aging on DNA repair and skin carcinogenesis: a minireview of population-based studies. J Investig Dermatol Symp Proc 1998;3:19–22. 51. Woodgate R. A plethora of lesion-replicating DNA polymerases. Genes Develop 1999;13:2191–5.

58. 59. 60. 61. 62.

doses of UVA and UVB: a less effective cell cycle arrest with UVA may render UVA-induced pyrimidine dimers more mutagenic than UVB-induced ones. Photochem Photobiol Sci 2012;11:207–15. Hocker T, Tsao H. Ultraviolet radiation and melanoma: a systematic review and analysis of reported sequence variants. Hum Mutat 2007;28:578–88. Maldonado JL, Fridlyand J, Patel H, et al. Determinants of BRAF mutations in primary melanomas. J Natl Cancer Inst 2003;95:1878–90. Smith ML, Seo YR. p53 regulation of DNA excision repair pathways. Mutagenesis 2002;17:149–56. Autier P, Doré JF, Négrier S, et al. Sunscreen use and duration of sun exposure: a double-blind, randomized trial. J Natl Cancer Inst 1999;91:1304–9. Yarosh D, Klein J, O’Conner A, et al. Effect of topically applied T4 endonuclease V in liposomes on skin cancer

63.

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in xeroderma pigmentosum: a randomized study. Lancet 2001;357:926–9. Green AC, Williams GM, Logan V, Strutton GM. Reduced melanoma after regular sunscreen use: randomized trial follow-up. J Clin Oncol 2011;29: 257–63. Young AR, Walker SL. Sunscreens: photoprotection of non-erythema endpoints relevant to skin cancer. Photodermatol Photoimmunol Photomed 1999;15:221–5. Nash JF, Tanner PR. Relevance of UV filter/sunscreen product photostability to human safety. Photodermatol Photoimmunol Photomed 2014;30:88–95. Takeuchi H, Rünger TM. Longwave UV light induces the aging-associated progerin. J Invest Dermatol 2013;133:1857–62.

CHAPTER

86 Ultraviolet Radiation

52. Johnson RE, Kondratick S, Prakash S, Prakash L. hRAD30 mutations in the variant form of xeroderma pigmentosum. Science 1999;285:263–5. 53. David SS, O’Shea VL, Kundu S. Base-excision repair of oxidative DNA damage. Nature 2007;447: 941–50. 54. Loeb LA. Cancer cells exhibit a mutator phenotype. Adv Cancer Res 1998;72:25–56. 55. Wikondahl NM, Brash DE. Ultraviolet radiation induced signature mutations in photocarcinogenesis. J Invest Dermatol Symp Proc 1999;4:6–10. 56. Ikehata H, Kawai K, Komura J, et al. UVA1 genotoxicity is meditated not by oxidative damage but by cyclobutane pyrimidine dimers in normal mouse skin. J Invest Dermatol 2008;128:2289–96. 57. Rünger TM, Farahvash B, Hatvani Z, Rees A. Comparison of DNA damage responses following equimutagenic

1547

SECTION 13 DISORDERS DUE TO PHYSICAL AGENTS

87 

Photodermatologic Disorders Henry W. Lim, John L. M. Hawk and Cheryl F. Rosen

All skin can react to light because it contains molecules (chromophores) whose chemical structures are capable of absorbing ultraviolet radiation (UVR) or other electromagnetic energy. This absorbed energy is then either re-emitted harmlessly as biologically inactive radiation or diverted to driving thermochemical reactions, leading to molecular, cellular, tissue, and clinical changes. These alterations are subsequently repaired or result in permanent effects. Nucleic acids are the most ubiquitous chromophores, initiating UVR-induced changes including sunburning, tanning, hyperplasia, aging, and carcinogenesis. Photodermatoses result from either abnormal tissue responses following absorption by endogenous molecules or expected responses to absorption by porphy­ rins or photosensitizing drugs or chemicals (Table 87.1). Clues to the diagnosis of specific photodermatoses are provided in Fig. 87.1.

ABNORMAL CUTANEOUS EFFECTS TO LIGHT Polymorphous light eruption is consistently the most common photo­ dermatosis, based upon relative frequency analyses from photoderma­ tology centers worldwide; it is followed (in decreasing order of frequency) by photoaggravated dermatoses, drug-induced photosensitivity, chronic actinic dermatitis, and solar urticaria1. It has been well documented that photodermatoses have a significant negative effect on patients’ quality of life2,3.

Immunologically-Mediated Photodermatoses This group of disorders is outlined in Table 87.2.

Polymorphous light eruption Synonyms:  ■ Polymorphic light eruption ■ Benign summer light

eruption (clinical variant) ■ Juvenile spring eruption (clinical variant)

Key features ■ The most common photodermatosis ■ Papules, vesicles or plaques within hours of sun exposure; lasts for a few days ■ Action spectra: UVB, UVA, and rarely visible light ■ Management: photoprotection and narrowband (NB)-UVB; occasionally, brief courses of topical or oral corticosteroids for acute attacks

Introduction and history

1548

Polymorphous light eruption (PMLE) is a common, sunlight-induced eruption affecting individuals of all races and skin colors4. Attacks are intermittent and follow minutes to hours (rarely days) of exposure of the skin to sunlight or artificial UVR. Non-scarring, pruritic, erythe­ matous papules, papulovesicles, vesicles, or plaques then develop hours later (occasionally within minutes). The eruption is generally most severe in the spring and early summer, especially in temperate climates. It improves by autumn and then usually completely disappears over the winter. In some patients, PMLE may only occur when they travel to tropical regions. PMLE was first described by Carl Rasch in 1900 and mentioned again by Haxthausen in 1918.

Epidemiology

The prevalence of PMLE in the general population is inversely related to latitude, being highest in Scandinavia (22%), high in the UK and northern US (10–15%), and low in Australia (5%) and equatorial Singa­ pore (~1%)4. This is probably due to the development of UVR-induced immunologic tolerance, commonly referred to as “hardening”, second­ ary to constant year-round solar exposure in sunny climates. Women are affected slightly more often than men, with the second and third decades being the most common times of onset.

Pathogenesis

Attacks of PMLE are triggered by exposure to UVR (and perhaps, on occasion, visible light) from sunlight or other sources such as tanning beds. Spring and summer sunlight in temperate regions is most likely to induce outbreaks, but generally at amounts lower than the minimal erythema dose (MED). The action spectrum ranges from UVB to UVA and rarely to visible light. Photoprovocation studies, requiring repeated exposures of UVR to the same sites over several days, have shown a positive response in 50% of patients to NB-UVB, 50% to UVA, and 80% to both UVB and UVA5. However, patients with PMLE typically have normal MEDs to UVB, UVA, and visible light4. PMLE appears to represent a delayed-type hypersensitivity (DTH) response to as-yet-undefined, endogenous cutaneous, photoinduced antigens4. Timed biopsy specimens, following solar-simulated irradia­ tion (~0.6 MED), have shown perivascular infiltrates of lymphocytes, primarily CD4+ (within hours) and CD8+ (within days), in association with an increased number of dermal and epidermal antigen-presenting cells6. Following UV exposure, reductions in IL-4 and IL-10 production as well as in infiltrates of neutrophils and mast cells have been observed in PMLE4. Susceptibility to PMLE appears to be genetic, with up to 70% of the population having a propensity for developing this condition, but not all expressing it, because of variations in disease penetrance7. There appears to be a resistance to the normal UVR-induced suppression of the induction8, but not the elicitation9, of cutaneous DTH responses. As a result, in PMLE, a lesser degree of cutaneous immunosuppression following UVR exposure (compared to normal individuals) likely results in a persistent ability to mount a DTH response against UVR-altered endogenous cutaneous molecules, leading to the development of clini­ cal lesions. Possible underlying mechanisms include: (1) an underexpression of apoptotic-cell clearance genes in keratinocytes, thus prolonging antigen presence; and/or (2) inefficient free radical removal, thereby increasing photoantigen production. In evolutionary terms, UVR-induced cutaneous immunosuppression may protect against developing disruptive PMLE, but it can increase the risk of skin cancer; of note, PMLE patients appear to have a reduced tendency to develop such cancers10.

Clinical features

PMLE occurs most commonly during the spring and early summer, following minutes to hours (occasionally days) of sun exposure4. Out­ breaks may also occur after exposure to snow-reflected sunlight, tanning beds, or UV phototherapy. The eruption develops hours (occasionally minutes) after UVR exposure; it then fades over one to several days or occasionally weeks if the exposure is ongoing. However, the likelihood of occurrence often diminishes or ceases over the summer or a lengthy sunny vacation, presumably due to the development of immunologic tolerance, sometimes called “hardening”4. Typically, some, but virtually never all, of the exposed skin is affected. Lesions are usually symmetrically distributed in a patchy fashion. Areas that are normally continuously exposed to sunlight (e.g. face) are often spared, although not always (Fig. 87.2). The distribution pattern and

Pathologic reactions of the skin to light can arise from multiple etiolo­ gies including: immunologic photodermatoses, e.g. polymorphous light eruption, solar urticaria, actinic prurigo, hydroa vacciniforme, and chronic actinic dermatitis; photosensitivity due to defective DNA repair, e.g. xeroderma pigmentosum, trichothiodystrophy, Bloom syn­ drome, Rothmund–Thomson syndrome; dermatologic disorders that may be aggravated by sun exposure; and phototoxic and photoallergic reactions due to exogenous and endogenous photosensitizers, especially drugs. Normal responses to sunlight exposure include sunburn, imme­ diate pigment darkening, tanning, vitamin D synthesis, immunosup­ pression, and chronic changes such as wrinkling, solar elastosis, and photocarcinogenesis.

photodermatoses, polymorphous light eruption, polymorphic light eruption, solar urticaria, actinic prurigo, hydroa vacciniforme, chronic actinic dermatitis, ultraviolet radiation, defective DNA repair, photoaggravated dermatoses, phototoxicity, photoallergy, drug-induced photosensitivity, photoallergic drug reaction, phototoxic drug reaction, allergic photocontact dermatitis, photopatch testing, xeroderma pigmentosum, Cockayne syndrome, trichothiodystrophy, Bloom syndrome

CHAPTER

87 Photodermatologic Disorders

ABSTRACT

non-print metadata KEYWORDS:

1548.e1

skin-colored papules of varying sizes, sometimes coalescing into large, smooth or unevenly surfaced plaques, are seen. In darkly pigmented individuals, the most common morphology is grouped, pinhead-sized papules in sun-exposed areas. Vesicles, bullae, papulovesicles, and con­ fluent edematous swelling are additional manifestations; rarely, only pruritus occurs. Occasionally, particularly in boys, the helices of the

CLASSIFICATION OF PHOTODERMATOSES

IDIOPATHIC, POSSIBLY IMMUNOLOGICALLY MEDIATED PHOTODERMATOSES

Idiopathic, possibly immunologically mediated (see Table 87.2) Defective DNA repair and chromosomal instability disorders • Photoaggravated dermatoses • Chemical- and drug-induced photosensitivity - Exogenous: ingested or externally applied drugs or chemicals - Endogenous: cutaneous porphyrias, pellagra, Smith–Lemli–Opitz syndrome •

Polymorphous light eruption Actinic prurigo • Hydroa vacciniforme • Chronic actinic dermatitis • Solar urticaria •





CHAPTER

87 Photodermatologic Disorders

type of lesions in a given patient are usually consistent over time. Areas commonly affected are the neck, outer aspects of the arms, and dorsal hands (Fig. 87.3), but there may be more widespread involvement of sun-exposed sites (Fig. 87.4). Lesions are polymorphous and vary widely amongst affected individu­ als. Clinically, mildly to markedly pruritic, grouped, erythematous or

Table 87.2 Idiopathic, possibly immunologically mediated photodermatoses.  

Table 87.1 Classification of photodermatoses.  

CLUES TO THE DIAGNOSIS OF SPECIFIC PHOTODERMATOSES IN ADULTS

Fig. 87.1 Clues to the diagnosis of specific photodermatoses in adults. LE, lupus erythematosus; PMLE, polymorphous light eruption.  

Clinical scenario: • Patient presents with a photodistributed cutaneous eruption • Patient presents with a history of “sun sensitivity” but has no visible cutaneous eruption at the time of examination

*

+ • Onset within hours of sun exposure • Pink to red, edematous papules, papulovesicles and plaques • Primarily on the extensor forearms, dorsal hands, and face • Onset within minutes of sun exposure • Lesions resemble hives • Primarily on the upper chest, outer arms

• Eczematous eruption • Primarily in sun-exposed areas

+

+

+

• Pruritic • Lesions last days to a few weeks

+

• Non-pruritic • Lesions last weeks to months

+

• Pruritus > burning, pain • Lesions last < 24 hours

+

• Review topical medications or sunscreens (Table 87.6)

+

• Review systemic drugs (Table 87.6) • Examine for signs or a history of an underlying dermatosis (e.g atopic dermatitis) • Initially sharp cut-off at clothing lines • Profound lichenification • Long duration

+

• Review systemic drugs (Table 87.6)

PMLE

Cutaneous lupus erythematosus (check ANA, -Ro, -La)

Solar urticaria

+

+

+

Photoallergic contact dermatitis

Photoallergic drug eruption Photoaggravated dermatosis (Table 87.5)

Chronic actinic dermatitis

+

• Phototoxic drug reaction to systemic medication

+

• Phototoxic contact dermatitis to topical medication or chemical

• Resembles sunburn • Review topical medications or chemicals (Table 87.6)

*In particular, is characteristic for PMLE and solar urticaria

1549

SECTION

Disorders Due to Physical Agents

13

$

$

%

%

Fig. 87.2 Polymorphous light eruption of the face. A Larger erythematous patch on the nose as well as erythematous plaques on the malar eminence and chin. B Edematous erythematous plaques on the cheek in a young child.  

ears may be principally affected in a form of PMLE referred to as juve­ nile spring eruption. Vesicles are commonly observed in this variant and rarely patients develop fever, general malaise, headache, and nausea. PMLE may be lifelong; however, in a 32-year follow-up of 94 patients, the disease improved or resolved in 58% over a period of 16 years, and in 75% over a period of 32 years.

&

Fig. 87.3 Polymorphous light eruption of the upper extremity. A Small pink edematous papules that are coalescing into plaques on the forearm of an Asian patient. B Scattered discrete papulovesicles. C Larger and more pronounced edematous erythematous papules and plaques.  

Pathology

There is variable epidermal spongiosis and a superficial and deep, peri­ vascular and periappendageal, lymphohistiocytic dermal infiltrate, often with scattered eosinophils and neutrophils. Significant papillary dermal edema occurs commonly (Fig. 87.5). Rarely, difficulty in distinc­ tion from cutaneous lupus may occur if interface changes are signifi­ cant, or from lymphoma if the dermal inflammatory cell infiltrate is marked.

Differential diagnosis 1550

PMLE can often be distinguished from lupus erythematosus (LE), photo­ aggravated dermatoses (e.g. atopic dermatitis, seborrheic dermatitis), solar urticaria, and rarely, erythropoietic protoporphyria (EPP) by the natural history and clinical appearance of the cutaneous lesions.

Occasionally, clinicopathologic correlation and laboratory evaluation are required (Table 87.3; see Fig. 87.1). For photoaggravated dermato­ ses, the characteristic clinical features of the primary disorder usually allow for distinction.

Treatment

PMLE in its milder forms may respond to photoprotection, including the use of broad-spectrum, high SPF sunscreens and physical barriers. In patients with more severe disease, hardening via prophylactic, twoto-three times weekly sessions of NB-UVB, usually for 15 sessions in the spring, may be effective for several months11. An initial starting dose of 50% of the MED for NB-UVB is recommended, with the dose



Courtesy, Jean L Bolognia, MD.

then increased by 10–15% per treatment. Oral prednisone (0.5–1 mg/ kg) may be used during the initial seven to ten days of phototherapy to minimize photoexacerbation. Once hardening is achieved, it may be possible to maintain the effect by having patients expose themselves weekly to sunlight between 10 AM and 2 PM for 15–20 minutes (without sunscreen) for the remainder of the sunny season. However, some patients find that they do not need to intentionally seek sun exposure to maintain the hardening. Other therapeutic options for prevention of PMLE include oral pred­ nisone ( extremities

Rare eye and visceral lesions; spontaneous resolution; association with CALM, NF1, and/or juvenile myelomonocytic leukemia

Benign cephalic histiocytosis

0–3 years

Face and neck > trunk and extremities

Usually none (diabetes insipidus rare); spontaneous resolution

Giant cell reticulohistiocytoma

Adults

Head (solitary lesion)

None; spontaneous resolution

Generalized eruptive histiocytoma

head & neck, genitalia

Uncommon visceral and bone lesions; possible association with B-cell lymphoma and leukemia

Histiocytoses

Histiocytosis Langerhans cell histiocytoses

Non-Langerhans cell histiocytoses Primarily cutaneous, usually self-resolving

Primarily cutaneous, often persistent/progressive Papular xanthoma*

Any

Generalized (discrete yellow papules and papulonodules with relative sparing of flexural sites)

Mucous membrane involvement can occur occasionally

Progressive nodular histiocytoma*

Any

Generalized (discrete yellow papules and nodules, sometimes with prominent facial involvement)

May represent same entity as the progressive form of papular xanthoma83; mucous membrane involvement can occur

Hereditary progressive mucinous histiocytosis*

Childhood/ adolescence

Generalized (skin-colored to erythematous papules and nodules)

Usually occurs in female patients; histologically, abundant dermal mucin in addition to histiocytes

Cutaneous, with frequent systemic involvement Necrobiotic xanthogranuloma

17–60 years

Periorbital > other face, trunk, extremities

Paraproteinemia due to plasma cell dyscrasia or lymphoproliferative disorder, hepatosplenomegaly

Multicentric reticulohistiocytosis

30–50 years

Head; hands, elbows (over joints); mucosa (oral, nasopharyngeal)

Arthritis (often destructive); up to 30% with internal malignancy

Rosai–Dorfman disease

10–30 years

Eyelids and malar area

Massive lymphadenopathy in a subset of patients, fever, hypergammaglobulinemia; skin-limited form increasingly recognized

Xanthoma disseminatum

Any

Flexural areas to widespread > mucosa (oral, nasopharyngeal)

Diabetes insipidus

Systemic, with skin involvement rare to unusual Erdheim–Chester disease*

Any, but usually adults

Skin involvement ~25% of patients: eyelids, scalp, neck, trunk, axillae (red–brown to yellow nodules and indurated plaques)

Fever, bone pain (osteosclerosis of long bones), exophthalmos, diabetes insipidus; involvement of the lungs, kidneys, adrenals, heart (up to 50%), CNS, retroperitoneum (fibrosis), and testes; high mortality rate; ~55% of patients have BRAF V600E mutations Foamy histiocytes with a small nucleus (CD68+. CD163+, CD1a−); a few multinucleated histiocytes or Touton giant cells also often present

Sea-blue histiocyte syndrome (sea-blue histiocytosis)* • Inherited • Acquired

Usually adolescence/ young adulthood (inherited form)

Skin involvement rare (inherited form): facial (macular hyperpigmentation and nodules)

Histiocytes contain cytoplasmic granules that stain azure blue with May–Gruenwald stain; multiple organs involved; can be fatal

*Not covered in the body of the text. Table 91.1 Clinical features of the histiocytoses. CALM, café-au-lait macule; NF, neurofibromatosis.  

Continued

1615

SECTION

Disorders of Langerhans Cells and Macrophages

14

CLINICAL FEATURES OF THE HISTIOCYTOSES CLINICAL FEATURES OF THE HISTIOCYTOSES

Histiocytosis

Usual age

Most common mucocutaneous sites

Other findings

Histiocytosiscell histiocytoses Langerhans

Usual age

Most common mucocutaneous sites

Other findings

Hemophagocytic lymphohistiocytosis (HLH; hemophagocytic syndrome)* • Primary (genetic; see Table 60.6) - Familial HLH‡; Chédiak–Higashi syndrome, Griscelli syndrome type 2 > Hermansky–Pudlak type 2; X-linked lymphoproliferative syndrome • Secondary (acquired) - Infection-associated (e.g. EBV, CMV, dengue) - Malignancy-associated (e.g. NK/T-cell lymphoma, B cell lymphoma) - Macrophage activation syndrome (MAS) associated with autoimmune connective tissue disease (e.g. sJIA, Still disease, systemic lupus erythematosus)

Primary: 0–2 years Secondary: any

Generalized (purpuric macules and papules, morbilliform eruptions, erythroderma, keratotic nodules) or acral (erythematous macules); malignancy-associated forms may present with lesions of cutaneous/ subcutaneous cytotoxic NK/T-cell lymphomas; skin biopsy specimens rarely demonstrate hemophagocytosis



HLH diagnosed if genetic mutation detected or if at least 5 of the following 8 criteria: (1) fever for >7 days; (2) splenomegaly; (3) cytopenias; (4) hypertriglyceridemia or hypofibrinogenemia; (5) histologic evidence of hemophagocytosis (in the bone marrow, lymph nodes or spleen); (6) low or absent natural killer cell activity; (7) hyperferritinemia**; and (8) elevated soluble CD25, plus evidence of infectious agent, malignancy or autoimmune connective tissue disease in secondary forms • Some of the patients with secondary forms may be heterozygous for genetic mutations that cause primary HLH • MAS in the setting of sJIA requires at least 2 laboratory criteria (thrombocytopenia, transaminitis, leukopenia, hypofibrinogenemia) or at least 2 clinical criteria (CNS dysfunction, hemorrhages, hepatomegaly)

*‡ Not covered in the body of the text.

In the US, most commonly due to mutations in the gene that encodes perforin (PRF1), referred to as subtype 2; additional genes include UNC13D (subtype 3), STX11 (subtype 4), and STXBP2 (subtype 5). Their protein products play a role in the cytotoxic activity of lymphocytes, including the exocytosis of cytotoxic granules by NK cells. **The primary differential diagnosis is iron overload, Still disease, HLH or MAS, infection, and malignancy.

Table 91.1 Clinical features of the histiocytoses. (cont’d) CMV, cytomegalovirus; EBV, Epstein–Barr virus; sJIA, systemic juvenile idiopathic arthritis.

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Letterer–Siwe disease is the acute diffuse form of LCH. It is a multi­system disease that nearly always develops prior to age 2 years, and commonly presents in children less than 1 year of age. Cutaneous involvement occurs in most patients as 1–2  mm pink to skincolored papules, pustules and/or vesicles in the scalp, flexural areas of the neck, axilla and perineum, and on the trunk (Fig. 91.1A,B,C). Rarely, the lesions resemble mollusca contagiosa (Fig. 91.1D)8. Scale and crust with secondary impetiginization are common findings, as is the development of petechiae and purpura (Fig. 91.1E). The lesions tend to coalesce and become tender, especially when fissures develop in intertriginous zones (Fig. 91.1B,F). Palmoplantar and nail involvement can occur, as can soft tissue nodules (Fig. 91.1G). In patients with darkly pigmented skin, the lesions may appear relatively hypopigmented (Fig. 91.1H). The eruption is most often confused with seborrheic dermatitis, various forms of diaper dermatitis or intertrigo (see Figs 13.3 and 13.11), arthropod bites (including scabies), and varicella. During the course of the disease, many organs can become infiltrated by clonal LCH cells. However, only if the key functions of the organ are affected is such involvement of prognostic significance. Lung, liver, lymph node, and bone involvement commonly occur at some point during the illness. Osteolytic bone lesions are painful, usually multiple, and most frequently involve the cranium. Occasionally, the hematopoietic system can be affected, with thrombocytopenia and anemia portending a poor prognosis. Classically, Hand–Schüller–Christian disease represents the triad of diabetes insipidus, bone lesions, and exophthalmos. These patients tend to have a chronic, progressive course. Typically, Hand–Schüller– Christian disease begins between the ages of 2 and 6 years. Patients with the complete triad are rare, as exophthalmos is uncommon and often a late finding. Approximately 30% of patients develop skin or mucous membrane lesions. While early cutaneous lesions are similar to those seen in Letterer–Siwe disease, older lesions can become xanthomatous. Ulcerative nodules may develop in the oral and genital areas, with premature loss of teeth possible secondary to gingival lesions. At least 80% of patients with Hand–Schüller–Christian disease develop bone lesions, the cranium being preferentially involved. Chronic otitis media occurs commonly in these patients and in patients with

all forms of LCH. Diabetes insipidus, secondary to infiltration of the posterior pituitary by LCH cells, develops in approximately 30% of patients and is more common in those individuals with cranial bone involvement. The chances of reversing the diabetes insipidus with radiation or chemotherapy are remote once symptoms develop. However, symptomatic treatment with vasopressin is effective. Eosinophilic granuloma is a localized variant of LCH that generally affects older children, boys more than girls. Skin and mucous membrane lesions are rare, with a single asymptomatic granulomatous lesion of the bone the most common manifestation. The cranium is most frequently affected, though lesions can also develop within the ribs, vertebrae, pelvis, scapulae, and long bones. A spontaneous fracture or otitis media may be the first sign of disease. Congenital self-healing reticulohistiocytosis (Hashimoto–Pritzker disease) is a variant of LCH which is generally limited to the skin and rapidly self-healing (Fig. 91.2). It presents at birth or in the first few days of life with a characteristic eruption of widespread red to purplish-brown papulonodules, which may have a vascular appearance or resemble a “blueberry muffin” rash (see Ch. 121). After several weeks to months, the lesions crust and involute. Solitary papules or nodules (often eroded or ulcerated) and disseminated vesicular eruptions have also been observed. Mucous membrane lesions and systemic involvement occasionally occur, including later-onset diabetes insipidus. While congenital self-healing reticulohistiocytosis is usually a benign, self-resolving disorder, its relationship to other LCH variants suggests a cautious approach with respect to prognosis, and longitudinal evaluation is recommended. Adults rarely develop LCH, but when they do, the most commonly involved sites are the skin, lung, and bone (see Fig. 91.1F). Diabetes insipidus can also develop and, as in children, is more likely when bony involvement of the skull is present. Severe multisystem disease, classically referred to as Letterer–Siwe disease, is rare in adults. However, LCH can be a progressive disease in adults, especially when both bone and extraskeletal sites are involved. Pulmonary involvement can be isolated or be a component of multisystem disease and it favors men who smoke cigarettes8a. There are two patterns of associations between LCH and malignancy9. The first is the development of acute leukemias and solid tumors in patients with a history of LCH who have been treated with

CHAPTER

Histiocytoses

91

A

D

B

C

E

F

Fig. 91.1 Langerhans cell histiocytosis – clinical spectrum. A Scalp involvement may initially be diagnosed as seborrheic dermatitis; however, there are usually more discrete papules and crusting. B Pink, thin plaques with fissuring along the inguinal creases can also resemble seborrheic dermatitis.  C Advanced disease with coalescence of papules into large plaques and prominent inguinal lymphadenopathy. D Pale pink to skin-colored papules, several of which have central umbilication and resemble mollusca contagiosa. E The presence of petechiae and purpuric papules is a clue to the diagnosis. F In an adult, the clinical presentation of inguinal involvement is similar to that of infants. G This subcutaneous nodule on the scalp involved the skull and represented the initial manifestation of multisystem Langerhans cell histiocytosis in an infant. H In patients with darkly pigmented skin, the papules can be hypopigmented. B, Courtesy, Richard Antaya,  

G

H

MD; D, Courtesy, Kristen Hook, MD; E, G, H, Courtesy, Julie V Schaffer, MD.

chemotherapy, radiotherapy or both, and the malignancies are likely to be treatment-related. There are reports of a few patients who developed skin or solid tumors (e.g. basal cell carcinoma, osteosarcoma) within the fields of radiotherapy for their LCH. A second, more fascinating association is the apparent increased incidence of LCH in patients with hematologic malignancies, including acute myelogenous leukemia, acute lymphocytic leukemia, chronic myelomonocytic leukemia, and lymphomas of both T- and B-cell origin. These malignancies can occur prior to, concurrently, or following the diagnosis of LCH10. In contrast to treatment-related (often referred to as secondary) hematologic malignancies, it has been demonstrated in several patients that the LCH and the hematologic malignancy are clonally related, possibly suggesting origin from a common neoplastic stem cell11. The prognosis of patients with LCH varies dramatically. Involvement of “risk organs” - hematopoietic system, liver, lungs and/or spleen substantially increases the risk of disease-related mortality. However, in individuals with single-system disease or multisystem disease that does not involve risk organs, mortality rates are very low (e.g. M

Skin

+ S100, CD1a, Langerin

Aggressive; >50% mortality

Histiocytic sarcoma

Adults > children

GI, skin, soft tissue

+ CD68, CD163, lysozyme

Aggressive; 60–80% mortality

Interdigitating dendritic cell sarcoma

Adults > children

Solitary lymph node > skin

+ S100 protein, vimentin, fascin; weakly + CD68, lysozyme, CD45

Aggressive; ~50% mortality

Follicular dendritic cell sarcoma

Adults > children

Cervical lymph node

+ CD21, CD35, CD23, clusterin; +/− S100 protein, CD68

Indolent; 10–20% mortality

91 Histiocytoses

CLINICAL AND IMMUNOPHENOTYPIC FEATURES OF THE MALIGNANT HISTIOCYTIC DISORDERS (HISTOCYTOSIS III)

Table 91.3 Clinical and immunophenotypic features of the malignant histiocytic disorders (histiocytosis III). F, female; M, male.

Fig. 91.18 Xanthoma disseminatum. Sclerotic form of xanthoma disseminatum in a patient who developed multiple myeloma.  

MALIGNANT HISTIOCYTIC DISORDERS Synonym:  ■ Class III histiocytosis The malignant histiocytic disorders are all very rare tumors (Table 91.3). Because most malignancies previously diagnosed as being of histiocytic origin have subsequently been shown to be either high-grade B-cell or T-cell lymphoid malignancies, their true incidence is uncertain. Nonetheless, the most recent WHO classification of tumors of hematopoietic and lymphoid tissues includes several true malignant histiocytic tumors77.

DERMAL DENDROCYTE HAMARTOMAS Synonym:  ■ CD34+ dermal dendrocytomas The dermal dendrocyte hamartomas are exceptionally rare and most cases are of recent description (Table 91.4)78–82. As the name implies, they are thought to be derived from dermal dendrocytes/dendritic cells, in particular CD34+ dermal dendrocytes. The most common of these entities is the medallion-like dermal dendrocyte hamartoma78, perhaps better named plaque-like CD34-positive dermal fibroma79. For additional online figure visit www.expertconsult.com

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eFig. 91.1 Xanthoma disseminatum. Sclerotic form of xanthoma disseminatum in a patient who developed multiple myeloma.  

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Disorders of Langerhans Cells and Macrophages

14

THE DERMAL DENDROCYTE HAMARTOMAS

Epidemiology*

Most common site

Clinical presentation

Pathology

Immunophenotype

CD34+ plaque-like dermal fibroma (medallion-like dermal dendrocyte hamartoma)†

Congenital > acquired 17 pts, mostly female

Chest

Single, 2–16 cm erythematous, atrophic (wrinkled) patch or plaque

Dermal spindle cell proliferation

+ CD34; inconsistent factor XIIIa expression

Fat-storing hamartoma of dermal dendrocytes

Congenital 1 pt (male)

Lumbar‡

Single, reddish-brown plaque with nodularity

Lipidized histiocytes between collagen bundles within reticular dermis

+ Factor XIIIa (CD34 was not performed)

Dermal dendrocyte hamartoma with stubby white hair

Congenital 1 pt (female)

Back‡

Single, soft, red nodule with short white hairs

Spindle cells

+ CD34; − factor XIIIa

Congenital CD34+ granular cell dendrocytosis

Congenital 1 pt (male)

Face and extremities‡

Numerous skin-colored papules and plaques

“Granular cells” interstitially arranged, primarily within superficial dermis

+ CD34; − factor XIIIa

Fibroblastic connective tissue nevus

Mostly children; F > M

Trunk > head & neck > extremities

Tan-brown to tan-white, smooth, firm nodule

Proliferation of bland intradermal fibroblastic/ myofibroblastic cells

+ CD34; − factor XIIIa in two-thirds of analyzed cases

*† To date.

May require analysis for the COL1A1-PDGFB fusion gene (e.g. via fluorescence in situ hybridization [FISH]) to exclude an atrophic dermatofibrosarcoma protuberans, which can have similar clinicopathologic features (see Ch. 116) ‡Based on only one reported patient.

Table 91.4 The dermal dendrocyte hamartomas.

REFERENCES

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1. Lichtenstein L, Histiocytosis X. integration of eosinophilic granuloma of bone, Letterer-Siwe disease and Schüller-Christian disease as related manifestations of a single nosologic entity. AMA Arch Pathol 1953;56:84–102. 2. Hashimoto K, Pritzker MS. Electron microscopic study of reticulohistiocytoma. An unusual case of congenital self-healing reticulohistiocytosis. Arch Dermatol 1973;107:263–70. 3. Chu A, D’Angio GJ, Favara BE, et al. Histiocytosis syndromes in children. Lancet 1987;2:41–2. 4. Arico M, Nichols K, Whitlock JA, et al. Familial clustering of Langerhans cell histiocytosis. Br J Haematol 1999;107:883–8. 5. Badalian-Very G, Vergilio J, Degar BA, et al. Recurrent BRAF mutations in Langerhans cell histiocytosis. Blood 2010;116:1919–23. 6. Willman CL, Busque L, Griffith BB, et al. Langerhans’-cell histiocytosis (histiocytosis X) – a clonal proliferative disease. N Engl J Med 1994;331:154–60. 7. Yu RC, Chu C, Buluwela L, et al. Clonal proliferation of Langerhans cells in Langerhans cell histiocytosis. Lancet 1994;343:767–8. 8. Huang JT, Mantagos J, Kapoor R, et al. Langerhans cell histiocytosis mimicking molluscum contagiosum. J Am Acad Dermatol 2012;67:e117–18. 8a.  Li CW, Li MH, Li JX, et al. Pulmonary Langerhans cell histiocytosis: analysis of 14 patients and literature review. J Thorac Dis 2016;6:1283–9. 9. Egeler RM, Neglia JP, Arico M, et al. The relation of Langerhans cell histiocytosis to acute leukemia, lymphomas, and other solid tumors. Hematol Oncol Clin North Am 1998;12:369–78. 10. Edelbroek JR, Vermeer MH, Jansen PM, et al. Langerhans cell histiocytosis first presenting in the skin in adults: frequent association with a second malignancy. Br J Dermatol 2012;167:1287–94. 11. Yohe SL, Chenault CB, Torlakovic EE, et al. Langerhans cell histiocytosis in acute leukemias of ambiguous or myeloid lineage in adult patients: support for a possible clonal relationship. Mod Pathol 2014;27:651–6. 12. Berres ML, Lim KP, Peters T, et al. BRAF-V600E expression in precursor versus differentiated dendritic cells defines clinically distinct LCH risk groups. J Exp Med 2014;211:669–83. 13. Pinkus GS, Lones MA, Matsumura F, et al. Langerhans cell histiocytosis immunohistochemical expression of

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fascin, a dendritic cell marker. Am J Clin Pathol 2002;118:335–43. Haroche J, Cohen-Aubart F, Emile J-F, et al. Vemurafenib as first line therapy in BRAF-mutated Langerhans cell histiocytosis. J Am Acad Dermatol 2015;73:e29–30. Gianotti F, Caputo R, Ermacora E. Singuliére histiocytose infantile à cellules avec particules vermiformes intracytoplasmiques. Bull Soc Fr Dermatol Syphiliogr 1971;78:232–3. Patsatsi A, Kyriakou A, Sotiriadis D. Benign cephalic histiocytosis: case report and review of the literature. Pediatr Dermatol 2014;31:547–50. Gianotti R, Alessi E, Caputo R. Benign cephalic histiocytosis: a distinct entity or a part of a wide spectrum of histiocytic proliferative disorders of children? Am J Dermatopathol 1993;15:315–19. Weston WL, Travers SH, Mierau GW, et al. Benign cephalic histiocytosis with diabetes insipidus. Pediatr Dermatol 2000;17:296–8. Gianotti F, Caputo R, Ermacora E, et al. Benign cephalic histiocytosis. Arch Dermatol 1986;122:1038–43. Zelger BG, Zelger B, Steiner H, et al. Solitary giant xanthogranuloma and benign cephalic histiocytosis – variants of juvenile xanthogranuloma. Br J Dermatol 1995;133:598–604. Winkelmann RK, Muller SA. Generalized eruptive histiocytoma: a benign papular histiocytic reticulosis. Arch Dermatol 1963;88:586–96. Sidoroff A, Zelger B, Steiner H, et al. Indeterminate cell histiocytosis – a clinicopathological entity with features of both X- and non-X histiocytosis. Br J Dermatol 1996;134:525–32. Shon W, Peters MS, Reed KB, et al. Atypical generalized eruptive histiocytosis clonally related to chronic myelomonocytic leukemia with loss of Y chromosome. J Cutan Pathol 2013;40:725–9. Seward JL, Malone JC, Callen JP. Generalized eruptive histiocytosis. J Am Acad Dermatol 2004;50:116–20. Caputo R, Ermacora E, Gelmetti C, et al. Generalized eruptive histiocytoma in children. J Am Acad Dermatol 1987;17:449–54. Repiso T, Roca-Miralles M, Kanitakis J, et al. Generalized eruptive histiocytoma evolving into xanthoma disseminatum in a 4-year-old boy. Br J Dermatol 1995;132:978–82. Wood GS, Hu CH, Beckstead JH, et al. The indeterminate cell proliferative disorder: report of a case manifesting

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SECTION 14 DISORDERS OF LANGERHANS CELLS AND MACROPHAGES

92 

Xanthomas William Trent Massengale

Key features ■ Cutaneous xanthomas can signal the presence of an underlying hyperlipidemia or monoclonal gammopathy ■ An understanding of basic lipid metabolism provides insight into the underlying hyperlipoproteinemias as well as the formation of xanthomas ■ The major forms of xanthomas associated with hyperlipidemia are: eruptive, tuberous, tendinous and plane (including xanthelasma) ■ Normolipemic plane xanthomas occur in association with monoclonal gammopathies ■ Histologically, lipid-laden macrophages (foam cells) are seen in the dermis ■ Prompt recognition and proper treatment can lead to xanthoma resolution as well as prevention of potentially life-threatening complications

INTRODUCTION Cutaneous xanthomas develop as a result of deposition of lipid in the dermis, primarily within macrophages (foam cells) but also extracellularly. One of their major distinguishing clinical features is a characteristic yellow to orange hue. Xanthomas may present with a variety of morphologies, from macules and papules to plaques and nodules. As discussed below, the morphology and anatomic location of the lesions often suggest the type of underlying lipid disorder or the presence of a paraproteinemia. Xanthomas can develop in the setting of primary or secondary disorders of lipid metabolism. Thus, early recognition of these lesions can make a significant impact on the diagnosis, management, and prognosis of patients who suffer from an underlying disease. It is therefore important for dermatologists to become familiar with the basic concepts of lipid metabolism and the associated disease states, as well as to be able to recognize the often pathognomonic cutaneous findings.

a hydrophobic core. The outer shell consists of phospholipids, free cholesterol, and non-covalently linked specialized proteins known as apolipoproteins or apoproteins (apo). The inner core contains triglycerides and cholesterol esters. Lipoproteins differ in their core lipid content. Triglycerides are the major core lipids in chylomicrons and very-low-density lipoproteins (VLDLs), while cholesterol esters dominate the core of low-density lipoproteins (LDLs), high-density lipoproteins (HDLs), and remnants of chylomicrons and VLDLs. The apoproteins found in the outer shell can also differ amongst the various lipoproteins (Table 92.1). These apoproteins serve several important functions, such as mediating the binding of lipoproteins to their respective receptors in target organs and activating enzymes involved in their metabolism. There are two major pathways of lipoprotein synthesis (Fig. 92.1A). The exogenous pathway begins with dietary fat intake. Through the action of pancreatic lipase and bile acids, dietary triglycerides are degraded to fatty acids and monoglycerides. After absorption by the intestinal epithelium, the triglycerides are reformed and packaged with a small amount of cholesterol esters into the central core of a chylomicron. The outer shell of the chylomicron consists of phospholipids, free cholesterol, and several apoproteins, including B-48, E, A-I, A-II, and C-II. Chylomicrons then enter the lymphatics and eventually the systemic circulation via the thoracic duct. Once in the circulation, hydrolysis of the core triglycerides occurs, releasing free fatty acids to the peripheral tissues. This is mediated through the action of the enzyme lipoprotein lipase that is bound to capillary endothelium. The activation of the lipoprotein lipase system is complex and involves not only hormones such as insulin, but also apoproteins such as C-II, located on the lipoprotein outer surface, and GPIHBP1, a protein expressed on endothelial cells that binds lipoprotein lipase and shuttles it to its site of action in the capillary lumen. After hydrolysis of approximately 70% of the original triglyceride content, a chylomicron “remnant” exists. The central core now contains predominantly cholesterol ester that has been acquired from circulating HDL molecules. The chylomicron remnant is taken up by the liver via specialized high-affinity apo B-100/E receptors that

EPIDEMIOLOGY Hyperlipidemia is quite common in the general population. In North America alone, it is estimated that over 100 million people currently have an elevated serum cholesterol level >200 mg/dl. Despite the large number of people who suffer from hyperlipidemia, only a minority will develop cutaneous xanthomas. Also, because the exact mechanism by which xanthomas form is not yet fully understood, it is not always possible to predict who will develop them. Xanthomas are thought to result from the permeation of circulating plasma lipoproteins through dermal capillary blood vessels followed by phagocytosis of the lipoproteins by macrophages, forming lipid-laden cells known as foam cells1. However, the precise steps and their regulation are still an area of investigation.

PATHOGENESIS

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There is strong evidence to support the theory that the lipids found in the various xanthomas are the same as those in the circulation2. The majority of plasma lipids are transported in complex structures known as lipoproteins. The basic structure of the lipoprotein allows the delivery of triglycerides and cholesterol to peripheral cells for their metabolic needs. This structure consists of a hydrophilic outer shell and

IMPORTANT APOPROTEINS

Apoprotein

Lipoprotein association

Function and comments

A-I

Chylomicrons, HDLs

Major protein of HDL; activates lecithin:cholesterol acyltransferase (LCAT)

B-48

Chylomicrons, chylomicron remnants

Unique marker for chylomicrons

B-100

VLDLs, IDLs, and LDLs

Major protein of LDL; binds to LDL receptor

C-II

Chylomicrons, VLDLs, IDLs, and HDLs

Activates lipoprotein lipase

E (at least 3 alleles [E2, E3, E4])

Chylomicrons, chylomicron remnants, VLDLs, IDLs, and HDLs

Binds to LDL receptor

Table 92.1 Important apoproteins. HDL, high-density lipoprotein; IDL, intermediate-density lipoprotein; LDL, low-density lipoprotein; VLDL, very-lowdensity lipoprotein.  

Cutaneous xanthomas develop as a result of intracellular and dermal deposition of lipid. One of their major distinguishing clinical features is a characteristic yellow to orange hue. They are a reflection of a range of disorders that affect lipid metabolism, from primary causes such as familial hypercholesterolemia to secondary etiologies such as cholestasis or medications (e.g. retinoids). The major forms of xanthomas associated with hyperlipidemia are: eruptive, tuberous, tendinous, and plane (including xanthelasma). In addition, normolipemic plane xanthoma can develop in association with monoclonal gammopathies. Histologically, lipid-laden macrophages (foam cells) are seen in the dermis. The therapeutic approach is dependent upon the underlying cause and includes medications (e.g. HMG-CoA reductase inhibitors, insulin), dietary restrictions, and in the case of xanthelasma, chemical or physical destruction.

xanthomas, hypercholesterolemia, hyperlipidemia, hypertriglyceridemia, eruptive xanthoma, tuberous xanthoma, tuberoeruptive xanthoma, tendinous xanthoma, plane xanthoma, xanthelasma, normolipemic plane xanthoma, verruciform xanthoma

CHAPTER

92 Xanthomas

ABSTRACT

non-print metadata KEYWORDS:

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CHAPTER

92

$

Exogenous pathway

Xanthomas

EXOGENOUS AND ENDOGENOUS PATHWAYS OF LIPOPROTEIN SYNTHESIS AND SITES OF DYSFUNCTION THAT LEAD TO THE MAJOR FORMS OF HYPERLIPIDEMIA

Endogenous pathway

Dietary fat E

Insulin

+

VLDL TG >> CE TG degraded

Hydrolysis of TG by LPL

TG reformed Hepatic FFA, TG, and cholesterol storage CM TG >> CE

Hydrolysis of TG by hepatic lipase

E

FFA Hydrolysis of TG by LPL

Peripheral tissues

+ Insulin

E = E3 or E4

E CM remnant CE > TG

= C-II apoprotein = A-I apoprotein

= B-100/E receptor (LDL receptor)

%

E

LDL CE

= B-48 apoprotein

= B-100

IDL* CE > TG

FFA

Peripheral tissues

Donate free cholesterol to HDL LCAT HDL CE

+CE

E

+CE

+CE Cholesterol used for cell membrane synthesis, steroidogenesis, myelin sheath formation

CE = Cholesterol esters FFA = Free fatty acids LCAT = Lecithin: cholesterol acyltransferase LPL = Lipoprotein lipase TG = Triglycerides

Peripheral tissues

CM = Chylomicron HDL = High-density lipoprotein IDL = Intermediate-density lipoprotein LDL = Low-density lipoprotein VLDL = Very-low-density lipoprotein VLDL remnant

*

Exogenous pathway

Endogenous pathway

Dietary fat E

Insulin

+

VLDL TG >> CE TG degraded

Hydrolysis of TG by LPL

TG reformed Hepatic FFA, TG, and cholesterol storage CM TG >> CE

Hydrolysis of TG by hepatic lipase

E

FFA Peripheral tissues

Hydrolysis of TG by LPL

+ Insulin

IDL* CE > TG E

Donate free cholesterol to HDL LCAT HDL CE

+CE

E LDL CE

E CM remnant CE > TG

FFA Peripheral tissues

+CE

+CE Peripheral tissues

* VLDL remnant

= Type I = Type II = Type III (only express E2) = Increased in Type IV

Fig. 92.1 Exogenous and endogenous pathways of lipoprotein synthesis (A) and sites of dysfunction that lead to the major forms of hyperlipidemia (B). Lipoprotein lipase (LPL) is activated by the C-II apoprotein.  

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Disorders of Langerhans Cells and Macrophages

14

recognize the apoproteins E3 or E4 on the remnant’s outer shell. Once in the liver, the remaining lipids enter hepatic storage and apoproteins such as B-48 are degraded. The endogenous pathway begins with the hepatic formation of VLDL particles. The central core of the VLDL consists primarily of triglycerides, which are derived from circulating free fatty acids and hepatic triglyceride stores. Important apoproteins found on the outer shell include B-100, E, and C-II. In a fashion similar to the chylomicron, lipoprotein lipase mediates hydrolysis of the VLDL molecule, removing the majority of its triglyceride content, and its cholesterol esters are acquired from HDL molecules. Lipoprotein lipase activation requires the presence of apo C-II on the VLDL outer shell. After removal of the majority of the triglyceride content, the VLDL “remnant”, also known as an intermediate-density lipoprotein (IDL), can then be taken up by the liver via apo B-100/E receptors and degraded. IDLs that escape uptake by the hepatocyte are stripped of their remaining core triglycerides by extracellular hepatic lipases and enter the circulation as LDLs. The LDL contains predominantly cholesterol ester in its central core and expresses B-100 on its surface. LDL delivers cholesterol ester to peripheral tissues, where it can be converted to free cholesterol. Cholesterol has several important functions within the body, including being an essential component of cell membrane bilayers. It is also important in the production of the myelin sheath of nerves, adrenal and gonadal steroidogenesis, and the production of bile acids. Hepatocytes play the major role in the catabolism of LDLs. Their uptake is mediated through the high-affinity apo B-100/E receptor found on the cell surface of the hepatocytes. Free cholesterol in excess of metabolic needs is re-esterified for storage. HDLs serve several important functions in cholesterol metabolism. One of the primary functions of HDLs is the removal of cholesterol from the peripheral tissues. During this process, free cholesterol and phospholipids are transferred from the cell membranes of peripheral cells to the HDL molecules. The free cholesterol is then esterified by the enzyme lecithin:cholesterol acyltransferase, or LCAT. This enzyme requires the presence of the HDL apoprotein A-I. HDL molecules then transfer the cholesterol esters to other lipoproteins such as LDLs and remnants of chylomicrons or VLDLs for transportation back to the liver. The liver plays the central role in the overall cholesterol economy. Hepatic intracellular cholesterol levels have a direct impact on the activity of HMG-CoA reductase, the rate-limiting enzyme of cholesterol synthesis, and on the expression of the high-affinity apo B-100/E receptor. When intracellular cholesterol levels are low, HMG-CoA reductase becomes activated and high-affinity apo B-100/E receptor expression increases. The increase in high-affinity receptors leads to increased uptake of cholesterol-containing lipoproteins such as chylomicron remnants, IDLs and LDLs. This is followed by the lowering of plasma cholesterol levels. As discussed later, this mechanism will be the basis for many of the pharmacologic interventions aimed at lowering cholesterol levels.

Eruptive Xanthomas Eruptive xanthomas appear as erythematous to yellow papules, approximately 1 to 5 mm in diameter (Figs 92.2 & 92.3). They are usually distributed on the extensor surfaces of the extremities, buttocks, and hands. Early in their development, lesions may have an inflammatory halo (likely due to their triglyceride component), which may be accompanied by tenderness and pruritus. The Koebner phenomenon has been reported to occur with eruptive xanthomas4. Eruptive xanthomas can be seen in the setting of primary or secondary hypertriglyceridemia. Triglyceride levels in patients with eruptive xanthomas often exceed 3000 to 4000 mg/dl. In the Frederickson classification of hyperlipidemias, hypertriglyceridemia can be seen in type I (elevated chylomicrons), type IV (elevated VLDLs) and type V (elevated chylomicrons and VLDLs). One reason for elevated triglyceride levels is failure to remove such lipids from the circulation (Fig. 92.4). Deficient activity of lipoprotein lipase will lead to accumulation of triglyceride-rich chylomicrons and VLDLs (see Fig. 92.1B). This can be related to either abnormalities in the enzyme itself, as in lipoprotein lipase deficiency (chylomicronemia syndrome), or in other controlling factors such as dysfunctional apoprotein C-II or impaired insulin activity5,6. In addition to deficiency of GPIHBP1, autoantibodies against GPIHBP1 can also lead to hypertriglyceridemia6a. Another reason for increased triglyceride levels is hepatic overproduction of triglyceride-rich lipoproteins via the endogenous pathway. In endogenous familial hypertriglyceridemia, a genetic defect exists that causes the liver to respond abnormally to dietary carbohydrates and insulin, with overproduction of hepatic VLDLs. The result is a Frederickson type IV pattern of hypertriglyceridemia. Secondary acquired defects in lipoprotein lipase activity, such as those due to diabetes mellitus, are not uncommon in these patients. With this second insult, the lipoprotein lipase system can become saturated and, as a result, no longer handles dietary lipids, leading to chylomicron elevations as well. This pattern is classified as a Frederickson type V phenotype. Environmental factors and underlying diseases commonly exacerbate genetic defects of triglyceride metabolism, leading to worsening of the hypertriglyceridemia with eruptive xanthoma formation (see Fig. 92.4). Such factors include obesity, high caloric intake, diabetes mellitus, alcohol abuse, oral estrogen replacement, and systemic medications that can lead to hypertriglyceridemia (e.g. retinoids, protease inhibitors, olanzapine). The resultant pattern usually leads to a Frederickson type IV phenotype. Oral retinoid therapy, especially bexarotene, can elevate triglyceride levels through an elevation in hepatic VLDL secretion. With isotretinoin, this elevation seems to be more prevalent in genetically predisposed individuals and may signal an increased risk for future metabolic syndrome7. Two of the five criteria for the clinical diagnosis of metabolic syndrome are lipid abnormalities – elevated triglycerides and reduced HDLs (see Table 53.5). The treatment of eruptive xanthomas involves the identification and treatment of the underlying causes of the hypertriglyceridemia (see

CLINICAL FEATURES

1636

Due to the complexity of cholesterol homeostasis, there are several possible ways in which hyperlipidemia may occur, from inherited disorders to metabolic diseases such as diabetes mellitus. Genetic mutations can affect important enzymes, receptors or receptor ligands, with such defects leading to the overproduction of lipoproteins or the inhibition of their clearance (Fig. 92.1B). Each possible defect would lead to a different abnormal lipid profile. In 1965, Lees and Frederickson3 published a system for classifying various disorders of lipid metabolism based upon the electrophoretic migration of the serum lipoproteins present. This system for phenotyping hyperlipoproteinemias is used today in a modified form (Table 92.2). In the next section, descriptions of underlying lipid disorders will reference not only the Frederickson classification system, but also the specific molecular defects when possible. With the exception of the homozygous form of familial hypercholesterolemia (type II), most cutaneous xanthomas do not appear until adulthood. Once the diagnosis is established, treatment of associated disorders (e.g. metabolic syndrome [see Table 53.5]) should reduce the incidence of potential systemic sequelae such as myocardial infarctions, cerebrovascular accidents, and hepatic steatosis.

Fig. 92.2 Eruptive xanthomas due to hypertriglyceridemia. The lesions favored the extensor surface of the lower extremities, in particular the knees.  

CHAPTER

Clinical findings Skin (types of xanthoma)

Type

Pathogenesis

Laboratory findings

Systemic

Type I (familial LPL deficiency, familial hyperchylomicronemia)

( a) Deficient or abnormal LPL (AR) (b) Apo C-II deficiency (AR) (c) Deficient glycosylphosphatidylinositol-anchored HDL-binding protein 1 [GPIHBP1] (AR) (d) Apo A-V deficiency (AR)

Slow chylomicron clearance Reduced LDL and HDL levels Hypertriglyceridemia

Eruptive

No increased risk of coronary artery disease Recurrent pancreatitis

Type II (familial hypercholesterolemia)

( a) LDL receptor defect (AD)^ (b) Reduced affinity of LDL for LDL receptor due to dysfunction of apo B-100 (ligand) (AD) (c) Accelerated degradation of LDL receptor due to missense PCSK9 mutations (AD*) (d) Defective LDL receptor adaptor protein 1 (required for receptor internalization) (AR)

Reduced LDL clearance Hypercholesterolemia

Tendinous, tuberoeruptive, tuberous, plane (xanthelasma, intertriginous areas, interdigital web spaces†)

Atherosclerosis of peripheral and coronary arteries

Type III (familial dysbetalipoproteinemia, remnant removal disease, broad beta disease, apo E deficiency)

Hepatic remnant clearance impaired due to apo E abnormality; vast majority of patients only express the apo E2 isoform that interacts poorly with the apo E receptor (AR>>AD)

Elevated levels of chylomicron remnants and IDLs Hypercholesterolemia Hypertriglyceridemia

Tuberoeruptive, tuberous, plane (palmar creases) – most characteristic Tendinous

Atherosclerosis of peripheral and coronary arteries

Type IV (endogenous familial hypertriglyceridemia)

Elevated production of VLDL associated with glucose intolerance and hyperinsulinemia; may be associated with heterozygous variants, e.g. in apo A-V, LPL, or the glucokinase regulator protein

Increased VLDLs Hypertriglyceridemia

Eruptive

Frequently associated with type 2 noninsulin-dependent diabetes mellitus, obesity, alcoholism (see Fig. 92.4)

Type V

Elevated chylomicrons and VLDLs; may be associated with heterozygous variants, e.g. in apo A-V, LPL, or the glucokinase regulator protein

Decreased LDLs and HDLs Hypertriglyceridemia

Eruptive

Diabetes mellitus

Xanthomas

92

IMPORTANT HYPERLIPOPROTEINEMIAS

^In patients with the LDLR IVS14+1G-A mutation, the phenotype can be altered by SNPs in the genes that encode apo A-II, cytoplasmic epoxide hydrolase 2, or growth hormone receptor.

*† Gain-of-function mutations cause autosomal dominant hypercholesterolemia24, whereas loss-of-function mutations (most prevalent in African-Americans) result in low LDL levels25. Said to be pathognomonic for homozygous state.

Table 92.2 Important hyperlipoproteinemias. In bold are the major lipid abnormalities found on routine screening. AD, autosomal dominant; Apo, apolipoprotein; AR, autosomal recessive; HDL, high-density lipoprotein; IDL, intermediate-density lipoprotein; LDL, low-density lipoprotein; LPL, lipoprotein lipase; PCSK9, proprotein convertase subtilisin/kexin type 9; VLDL, very-low-density lipoprotein.  

Fig. 92.3 Eruptive xanthomas. A,B The yellow hue is influenced by the degree of pigmentation of the skin. Note the clustering of some of the lesions.  

$

%

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Disorders of Langerhans Cells and Macrophages

14

UNDERLYING DISORDERS IN PATIENTS WITH ERUPTIVE XANTHOMAS AND HYPERTRIGLYCERIDEMIA

Eruptive xanthomas and hypertriglyceridemia

Failure to remove TGs from circulation

Primary

Primary lipoprotein lipase deficiency

Hepatic overproduction of triglyceride-rich lipoproteins

Secondary

Dysfunctional apoprotein C-II

*

Diabetes mellitus & impaired insulin activity Hypothyroidism Nephrotic syndrome Systemic retinoids

Primary

Endogenous familial hypertriglyceridemia (type IV)

Secondary

Secondary lipoprotein lipase deficiency (usually due to diabetes mellitus)

Type V

• • • •

Obesity High caloric intake Diabetes mellitus Hypothyroidism

*

• Alcohol abuse • Estrogen replacement • • • •

*

therapy Systemic retinoids Antiretroviral therapy Olanzapine Azacitidine

**

Fig. 92.4 Underlying disorders in patients with eruptive xanthomas and hypertriglyceridemia. *Multiple contributory mechanisms. **Examples include ritonavir, indinavir and stavudine. TGs, triglycerides.  

Fig. 92.6 Nodular tuberous xanthoma of the elbow. Courtesy, Lorenzo  

Cerroni, MD.

Fig. 92.5 Tuberoeruptive xanthomas on the elbow of a child with homozygous familial hypercholesterolemia. Note the yellowish hue. Courtesy,  

Julie V Schaffer, MD.

Fig. 92.4). Failure to recognize and treat the patient with hypertriglyceridemia could lead to complications such as acute pancreatitis. Pharmacologic and dietary lowering of the circulating triglycerides to reasonable levels will result in the prompt resolution of the eruptive lesions.

Tuberous/Tuberoeruptive Xanthomas 1638

Tuberoeruptive and tuberous xanthomas are clinically and pathologically related and often described as being on a continuum. Tuberoeruptive xanthomas present as pink–yellow papules or nodules on extensor surfaces, especially the elbows and knees (Fig. 92.5). Tuberous lesions

are noted to be larger than tuberoeruptive lesions and may exceed 3 cm in diameter (Fig. 92.6). Together, these lesions can be seen in hypercholesterolemic states such as dysbetalipoproteinemia (Frederickson type III) and familial hypercholesterolemia (Frederickson type II; see below). In contrast to eruptive xanthomas, tuberous xanthomas are usually slow to regress following institution of appropriate therapy. Dysbetalipoproteinemia, or broad beta disease, is a genetic disorder of lipid metabolism that is usually inherited in an autosomal recessive fashion. It is caused by the presence of an isoform of apo E, primarily apo E2, that is a poor ligand for the high-affinity apo B-100/E receptor (see Fig. 92.1B). This results in the poor hepatic uptake of chylomicron and VLDL remnants. As a result, the serum levels of both triglycerides and cholesterol are elevated. The cutaneous lesions that are most characteristic of this disease are tuberous or tuberoeruptive xanthomas

Tendinous Xanthomas Tendinous xanthomas are firm, smooth, nodular lipid deposits that can affect the Achilles tendons (Fig. 92.7) or the extensor tendons of the hands (Fig. 92.8), knees, or elbows. The overlying skin is normal in appearance. Ultrasound can aid in the diagnosis of subtle lesions of the Achilles tendon by demonstrating hypoechoic nodules or an increase in the anteroposterior diameter of the tendon9. The presence of tendinous xanthomas is almost always a clue to an underlying disorder of lipid metabolism. Lipid disorders that have been associated with this type of xanthoma include familial hypercholesterolemia, dysbetalipoproteinemia, and hyperlipidemia secondary to hypothyroidism (Table 92.3). Tendinous xanthomas are most frequently seen in the setting of familial hypercholesterolemia. This disorder results from a deficiency of normal LDL receptors on cell membranes, which leads to the poor hepatic clearance of circulating LDLs and, therefore, elevated LDL cholesterol levels (Frederickson type II). This condition is inherited in an autosomal dominant fashion with a high degree of penetrance. Homozygotes can have LDL cholesterol levels of 800 to 1000 mg/dl with widespread atherosclerosis and the appearance of xanthomas during the first decade of life. Heterozygosity for the disorder is more common and is estimated to occur in 1 in 500 individuals in the US. The types of xanthomas seen in this disorder include tendinous,

Fig. 92.7 Tendinous xanthoma. Linear swelling of the Achilles area, representing a tendinous xanthoma in a patient with dysbetalipoproteinemia.  

Fig. 92.8 Tendinous xanthomas of the fingers in a patient with homozygous familial hypercholesterolemia. Note intertriginous plane xanthomas of the web spaces.

tuberous, tuberoeruptive, and plane (including xanthelasma). Because of its relatively common occurrence, patients with tendinous xanthomas are more likely to have the heterozygous form of the disease than the rare homozygous state. Plane xanthomas of the intertriginous web spaces of the fingers are thought to be pathognomonic for the homozygous condition (see Fig. 92.8)10. There is a closely related disorder, known as familial defective apolipoprotein B-100. In this dominantly inherited genetic disorder, the LDL receptor is normal. However, there is decreased affinity of LDL for the LDL receptor because the mutation affects its ligand, apo B-100. Patients may present with identical clinical findings as in familial hypercholesterolemia, although usually not as severe11. From a therapeutic standpoint, distinguishing this disorder from dysfunction or accelerated degradation of the LDL receptor (see Table 92.2) would become more important in the future should treatments aimed at correcting LDL receptor function become commercially available. Rarely, tendinous xanthomas can develop in the absence of a lipoprotein disorder. Two examples are cerebrotendinous xanthomatosis and β-sitosterolemia. In cerebrotendinous xanthomatosis, an enzymatic defect exists in the bile acid synthetic pathway, leading to the abnormal accumulation of an intermediate known as cholestanol. This intermediate is deposited in most tissues, including the brain, and can also form tendinous xanthomas12. In β-sitosterolemia, an abnormal accumulation of plant sterols occurs, leading to tendinous xanthoma formation.

CHAPTER

92 Xanthomas

(present in 80% of patients) and plane xanthomas of the palmar creases (xanthoma striatum palmare), which are present in two-thirds of patients (see below)8.

Plane Xanthomas and Xanthelasma Plane xanthomas appear as yellow to orange, non-inflammatory macules, papules, patches, and plaques. They can be circumscribed or diffuse. While anatomic locations vary, the site often serves as a clue to the particular underlying disease state. For example, intertriginous plane xanthomas may occur in the antecubital fossae (Fig. 92.9) or the web spaces of the fingers (see Fig. 92.8), where they are almost patho­ gnomonic for homozygous familial hypercholesterolemia10. Plane xanthomas of the palmar creases, or xanthoma striatum palmare (Fig. 92.10), are nearly diagnostic for dysbetalipoproteinemia, especially when accompanied by tuberous xanthomas13. Xanthelasma, or xanthelasma palpebrarum, are commonly observed plane xanthomas of the eyelids (Fig. 92.11). Although the presence of xanthelasma warrants investigation for hyperlipidemia, the latter is present in only about one-half of the patients with these lesions. Younger patients or those with a strong family history of hyperlipidemia are more likely to have an underlying lipid disorder and should be appropriately screened. Plane xanthomas of cholestasis may occur as a complication of diseases such as biliary atresia or primary biliary cirrhosis. In these conditions, unesterified cholesterol begins to accumulate in the blood, leading to plane xanthoma formation. The lesions often begin as localized plaques on the hands and feet, but can become generalized. Plane xanthomas can also occur in a normolipemic patient, where they may signal the presence of an underlying monoclonal gammopathy (Fig. 92.12), usually due to a plasma cell dyscrasia, but occasionally SECONDARY HYPERLIPIDEMIA – UNDERLYING DISORDERS



Diabetes mellitus* Cholestasis - Primary biliary cirrhosis (often plane xanthomas, including palmar) - Alagille syndrome (elbows/knees, flexures, fingers, palms, helices)*,† • Biliary atresia * • Hypothyroidism * • Nephrotic syndrome * • Type I glycogen storage disease (von Gierke) * • •

*Xanthomas can develop during childhood.

†Autosomal dominant disorder due to mutations in JAG1, which encodes the Notch signaling

pathway ligand Jagged-1, or (in ~5% of patients) NOTCH2. Patients have cholestasis due to a paucity of intrahepatic bile ducts, elevated LDL (cholesterol) levels, cardiac defects, peculiar facies, growth retardation, and posterior embryotoxon; xanthomas within body folds may become very firm26–28.

Table 92.3 Secondary hyperlipidemia – underlying disorders. In addition to a fasting lipid panel, screening blood tests include fasting glucose, liver function tests, TSH, and albumin.  

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14

secondary to a lymphoproliferative disorder such as B-cell lymphoma or Castleman disease (see Ch. 119). This type of xanthoma can also be seen in patients with chronic myelomonocytic leukemia. In gammopathy-associated plane xanthomas, monoclonal IgG is thought to bind to circulating LDL, rendering the antibody–LDL complex more susceptible to phagocytosis by macrophages14. Favored locations include the neck, upper trunk, flexural folds, and periorbital region. In the setting of a monoclonal gammopathy, the coexistence of plane xanthomas and necrobiotic xanthogranuloma has been observed, suggesting a disease overlap15. Of note, there is an entity known as hyperlipidemic myeloma in which xanthomas appear on the elbows and knees as well as within the palmar creases.

Verruciform Xanthomas

Fig. 92.9 Plane xanthomas of the antecubital fossae. This young patient had dysbetalipoproteinemia.  

Fig. 92.10 Plane xanthomas of the palmar creases (arrows) in a patient with dysbetalipoproteinemia. They are seen in approximately two-thirds of patients with this disorder. Plane xanthomas are also seen in the setting of cholestasis, e.g. biliary atresia or primary biliary cirrhosis.  

Verruciform xanthomas are asymptomatic, planar or verrucous, solitary plaques that are usually 1 to 2 cm in diameter. They occur primarily in the mouth (Fig. 92.13), but sometimes in anogenital (including the scrotum) or periorificial sites. There is usually no associated hyperlipidemia and these xanthomas persist for years. Single or multiple lesions are also seen in the setting of lymphedema, epidermolysis bullosa, pemphigus, discoid lupus erythematosus and GVHD, as well as within cutaneous lesions of the X-linked dominant disorder CHILD (congenital hemidysplasia with ichthyosiform erythroderma and limb defects) syndrome. The latter is due to mutations in NSDHL, which encodes 3β-hydroxysteroid dehydrogenase, an enzyme involved in cholesterol biosynthesis (see Ch. 57). In a molecular study of sporadic verrucous xanthomas, two of nine lesions were found to have a missense somatic mutation in exon 6 of NSDHL (only exons 4 and 6 were examined) which differed from the mutations seen in CHILD syndrome16.

Fig. 92.12 Normolipemic plane xanthoma. The large thin plaques have a yellow–orange color. The patient was found to have a monoclonal gammopathy.  

Courtesy, Whitney High, MD, JD.

Fig. 92.13 Verruciform xanthoma of the oral mucosa. Courtesy, Kishore  

Shetty, DDS.

1640

Fig. 92.11 Xanthelasma palpebrarum with typical yellowish hue.  

CHAPTER

Eruptive xanthomas - Non-Langerhans cell histiocytoses Xanthoma disseminatum Papular xanthoma Generalized eruptive histiocytomas Indeterminate cell histiocytosis Rosai–Dorfman disease Juvenile xanthogranuloma (micronodular form) - Xanthomatous lesions of Langerhans cell histiocytosis - Disseminated granuloma annulare • Tuberous xanthomas - Erythema elevatum diutinum - Multicentric reticulohistiocytosis • Tendinous xanthomas - Giant cell tumor of the tendon sheath - Rheumatoid nodule - Subcutaneous granuloma annulare - Erythema elevatum diutinum • Xanthelasma - Syringomas - Necrobiotic xanthogranuloma - Adult-onset asthma and periocular xanthogranuloma (AAPOX) - Sebaceous hyperplasia - Palpebral sarcoidosis •

Fig. 92.14 Histology of a tuberous xanthoma. Foamy macrophages fill the dermis. Courtesy, Lorenzo Cerroni, MD.  

One proposal is that enzymatic dysfunction leads to an excess formation and accumulation of lipid storage droplets, followed by formation of lipid-laden dermal macrophages. Another hypothesis suggests that the foam cells result from damage to the epithelium, analogous to the amyloid deposits within the dermal papillae in lichen amyloidosis. The few foam cells beneath the epithelium may be subtle and easy to miss, in which case verruciform xanthomas may be confused histologically with warts and other papillomatous disorders. Surgery is generally curative.

92 Xanthomas

DIFFERENTIAL DIAGNOSIS OF XANTHOMAS

Table 92.4 Differential diagnosis of xanthomas.  

DIFFERENTIAL DIAGNOSIS A selection of the diseases included in the differential diagnosis of xanthomas is listed in Table 92.4.

PATHOLOGY

TREATMENT

The characteristic histologic finding in xanthomas is the foam cell. Foam cells consist of macrophages that contain imbibed lipid within their cytoplasm (Fig. 92.14). All xanthomas contain dermal infiltrates of lipid, but they may vary in the degree of lipid content, the inflammatory infiltrate, the amount and location of the infiltrate, and the presence of extracellular lipid. The histologic appearance of xanthomas is somewhat altered by routine processing, as formalin fixation can remove deposits of lipid and leave artifactual clefting. Immunohistochemical staining for adipophilin can be performed to detect lipid accumulation17. Adipophilin, also known as adipose differentiationrelated protein, is a lipid droplet-associated protein. Eruptive xanthomas contain lipid deposits in the reticular dermis. Of note, early in lesion development, foam cells are relatively small in number and size. The initial inflammatory infiltrate is mixed, containing both neutrophils and lymphocytes. As an increase in lipidization occurs, the appearance of the lesion becomes more typical of a xanthoma, but foam cells remain fewer in number compared with other types of xanthomas. Extracellular lipids are present in the dermis, which are seen as artifactual clefts filled with a wispy faint blue–gray material. Tuberous xanthomas demonstrate large aggregates of foam cells in the dermis, often accompanied by fibrosis, but without a large number of inflammatory cells. Tendinous xanthomas have a similar histology, with foam cells that are even larger in size. Cholesterol esters are present in these lesions and can be seen with polarized microscopy. Plane xanthomas such as xanthelasma can have a unique histologic appearance. The foam cells in this type of xanthoma are more superficial than in other types of xanthomas. Small aggregates of foam cells are often present in the superficial dermis. The lesions are noninflammatory and have minimal fibrosis. With xanthelasma, there are often clues as to the location of the lesion, such as a thin epidermis, fine vellus hair follicles, and striated muscle fibers that are characteristic of the eyelid. A distinctive papular neutrophilic xanthoma, in which dermal foam cells are intermingled with neutrophils and prominent nuclear dust, has been described in HIV-infected patients with an IgA gammopathy. In verruciform xanthomas, there is usually hyperkeratosis, acanthosis, and papillomatosis, with foamy macrophages limited to the submucosa or dermal papillae.

The treatment of xanthomas associated with hyperlipidemia requires the identification of the underlying lipoprotein disorder and other possible exacerbating factors. In addition to dietary measures, there are several medications available for lowering lipid levels in patients with primary and secondary hyperlipidemia. Table 92.5 outlines their mechanisms of action, clinical effects, and side effects. Correction of the underlying lipid disorder leads to the eventual resolution of the xanthomas in many patients. Xanthomas that have grown slowly over years, such as tendinous and tuberous xanthomas, are often slow to regress, whereas eruptive xanthomas may disappear within weeks of aggressive therapy. Dietary measures are an important component of lipid-lowering therapy, in addition to oral medications (see Table 92.5). Decreasing total caloric intake and the achievement of ideal body weight alone can make a significant impact on lipid levels in some patients. Dietary fat restriction to 5 cm

1–3 mm papules, annular plaques usually 10 cm

3 to >10 cm

Variable

1–3 cm

No. of lesions

Variable

1–10

1–10

1–10

1–5

1–10

Associations

Systemic manifestations of sarcoidosis (see Table 93.3); can be drug-induced (e.g. IFN, TNF inhibitors) or reaction pattern to underlying lymphoma

Possible diabetes mellitus, thyroid disease, or hyperlipidemia; rare reports of HIV infection, malignancy

Actinic damage

Diabetes mellitus

Intestinal Crohn disease

Rheumatoid arthritis

Special clinical characteristics

Develop within sites of trauma including scars and tattoos

Central hyperpigmentation

Central atrophy and hypopigmentation

Yellow–brown atrophic centers, ulceration

Draining sinuses and fistulas

Occasional ulceration, especially at sites of trauma

Non-infectious Granulomas

93

CLINICAL FEATURES OF THE MAJOR NON-INFECTIOUS GRANULOMATOUS DERMATITIDES

*† Clinical variants include lupus pernio and subcutaneous (Darier–Roussy), psoriasiform, ichthyosiform, angiolupoid, and ulcerative sarcoidosis. Clinical variants include generalized/disseminated, micropapular, nodular, perforating, subcutaneous, and patch granuloma annulare.

‡Although rheumatoid arthritis has a female : male ratio of 2–3 : 1.

Table 93.1 Clinical features of the major non-infectious granulomatous dermatitides. AEGCG, annular elastolytic giant cell granuloma; HIV, human immunodeficiency virus.  

SPECTRUM OF CUTANEOUS MANIFESTATIONS OF SARCOIDOSIS

Common Papules – favor periorificial sites on face



Lupus pernio – favors nose and central face



• •

Plaques – favor trunk and extremities Scar-associated – initial insult weeks to decades prior

Tattoo-associated – favors sites of red and yellow pigments



Uncommon Annular



Lichenoid



• •

Atrophic – favors head and neck region Psoriasiform

Subcutaneous (Darier-Roussy) – favors extremities



Rare Angiolupoid – favors face and can mimic rosacea

Alopecia – scarring or nonscarring



Erythrodermic



Ichthyosiform



Nail dystrophy – subungual hyperkeratosis, onycholysis



Ulcerative



• • • • •

Hypopigmented Micropapular Photodistributed/photo-exacerbated Verrucous

Nonspecific and common Erythema nodosum



Table 93.2 Spectrum of cutaneous manifestations of sarcoidosis. Photographs of entities in chapter or online in italics.

Adapted from Haimovic A, et al.



Sarcoidosis: a comprehensive review and update for the dermatologist: part I. Cutaneous disease. J Am Acad Dermatol. 2012;66:699.e1–18.

History

Epidemiology

Sarcoidosis was described initially by Sir Jonathan Hutchinson in 1875 and cutaneous sarcoidosis (lupus pernio) by Besnier in 1889. Ten years later, Caesar Boeck coined the term “multiple benign sarkoid”, noting that the lesions resembled benign sarcomas.

Sarcoidosis, which occurs in patients of all races and ages as well as both sexes, is characterized by a bimodal age distribution, with peaks between 25 and 35 years and then between 45 and 65 years in women. In the US, there is an increased incidence of sarcoidosis in

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14

African-Americans, ranging from 35 to 64 per 100 000. Middle-aged African-American women have the highest incidence (107 per 100 000), with African-American women having a lifetime risk of developing the disease of 2.7%1. In comparison, the incidence in Caucasians in the US ranges from 10 to 14 per 100 000. Sarcoidosis in African-Americans also tends to be more chronic and severe with a higher mortality rate than in other populations2. Worldwide, the incidence of sarcoidosis is highest in Sweden (64 per 100 000) and the UK (20 per 100 000) and lowest in Spain and Japan (both 1.4 per 100 000). A greater number of patients with new-onset sarcoidosis are reported in the winter and spring3.

Pathogenesis Immune mechanisms Sarcoidosis is a multisystem granulomatous disease characterized by hyperactivity of the cell-mediated immune system. Patients with a genetic susceptibility are exposed to a triggering antigen, leading to activation of macrophages and T cells, with subsequent granuloma formation. While classically considered a Th1-predominant immune response, the inflammatory cascade in sarcoidosis likely spans multiple pathways, including the innate immune system (via activation of pattern recognition receptors such as Toll-like receptors or NOD-like receptors) and potentially the Th17 arm of the immune system4,5. Specifically, upregulation of CD4+ T helper cells of the Th1 subtype occurs following antigen presentation by monocytes bearing MHC class II molecules, which initiates formation of epithelioid granulomas in a variety of tissue types6. In the lung, an oligoclonal α/β T-cell population has been described, suggesting that antigenic triggers of sarcoidosis favor a progressive accumulation and activation of specific T-cell clones7. Increased production of Th1 cytokines, including interleukin (IL)-2, IL-12, IL-18 and interferon (IFN)-γ, as well as release of tumor necrosis factor (TNF)-α by macrophages and some CD8+ T cells, leads to persistent Th1 activity and persistent IFN-γ elevation. There is macrophage accumulation and hyperactivity, along with B-cell stimulation and hypergammaglobulinemia. TNF-α and GM-CSF promote fusion of activated macrophages into the multinucleated cells seen within the granuloma5. Monocyte chemotactic factor (MCF), produced by activated T helper cells, attracts monocytes from the circulation into peripheral tissues. Compartmentalization of granuloma-forming T lymphocytes and monocytes within peripheral tissues leads to lymphopenia and decreased delayed-type hypersensitivity to common antigens (anergy), most pronounced during the initial stages of sarcoidosis. In addition, T regulatory cells may play a role in this anergic state. However, in some patients, there actually may be inadequate regulatory T-cell function such that production of TNF-α or IFN-γ is not suppressed8.

Triggers

1646

The identity of the antigen responsible for the cascade of events leading to granuloma formation in patients with sarcoidosis remains uncertain. Some investigators have proposed an autoimmune etiology, while others have searched for exposures to inorganic dusts and particles (e.g. zirconium, talc)9 or an infectious cause. The latter is suggested by several observations, including the identification of microbial components such as mycobacterial DNA sequences in different sarcoidal tissues10, the transmissibility of sarcoidal lesions via the Kveim reagent, and the observation that sarcoidal granulomas have developed in patients receiving organ transplants from donors with sarcoidosis. In a meta-analysis, mycobacterial nucleic acids were identified in ~25% of sarcoidal tissues11. Also, the catalase-peroxidase (mKatG) protein from Mycobacterium tuberculosis has been proposed as a potential triggering antigen for granulomatous inflammation. However, arguments against a purely infectious etiology include the observation that sarcoidosis patients do not develop fulminant infectious symptoms when placed on immunosuppressive agents. In addition, mycobacteria have not been cultured from sarcoidal tissues or from the sarcoid-like lesions that develop during antiretroviral-induced immune reconstitution12. Occupational associations have been noted in healthcare workers, navy personnel on aircraft carriers, and firemen10, with a marked increase in sarcoidosis-like illnesses in the first responders to the 9/11 World Trade Center terrorist attacks. Additional proposed triggers include viruses13, Propionibacterium acnes, and an abnormal accumulation of serum amyloid A (SAA).

Over the past two decades, an increasing number of medications have been reported to induce cutaneous sarcoidosis and sarcoid-like granulomatous eruptions, including IFN, TNF inhibitors, immune checkpoint inhibitors (e.g. ipilimumab, nivolumab), and targeted kinase inhibitors (e.g. vemurafenib). Patients with lymphoma may also develop secondary sarcoidal reactions, most commonly in lymph nodes but occasionally in the skin.

Genetics

Sarcoidosis is a polygenic not a monogenic disease. A genetic component is supported by a twin study in which the monozygotic twins of patients with sarcoidosis had an 80-fold increased risk of having sarcoidosis14. The largest case–control study to date demonstrated a familial relative risk of 4.715. The impact of HLA alleles varies significantly, depending upon disease subtype and racial group. Overall, HLADRB1*01 and DRB1*04 protect against sarcoidosis in some populations, while DRB1*03, DRB1*11, DRB1*12, DRB1*14, and DRB1*15 appear to confer risk16; HLA-B8/DR3 may be associated with the development of Löfgren syndrome (see below). In African-Americans, HLADQB1 alleles may play a role16, and patients with DRB1*03 may have a better prognosis. Specific susceptibility genes include TNF (variants associated with Löfgren syndrome) and IL23R (variants confer risk for Crohn disease and sarcoidosis)16. While the etiologic agent clearly remains elusive, investigation of the immunopathogenesis of the disease (see above) has been aided by examining the cutaneous reaction produced by injection of a tissue suspension prepared from sarcoidal spleen. The suspension (Kveim– Siltzbach antigen) causes characteristic non-caseating granuloma formation in the skin of patients with sarcoidosis6. Nowadays, however, this skin test is rarely performed.

Clinical Features Up to a third of patients with systemic sarcoidosis develop skin lesions, which may be the first or only clinical manifestation of the disease. Although cutaneous sarcoidosis most commonly presents as papules and plaques, often red–brown to violaceous in color (Figs 93.2A–D), the skin manifestations are protean (Table 93.2). Sarcoidal lesions are fairly symmetric in distribution and favor the nose, especially the alae, and the periocular and perioral regions of the face, followed by the neck, upper trunk, and extremities. Involvement at sites of prior injuries, e.g. scars, tattoos, is a characteristic finding (Fig. 93.2E). Unusual variants include hypopigmented, ichthyosiform, micropapular, psoriasiform, and ulcerative (Fig. 93.3A,B; see Table 93.2). Although many lesions are red–brown to violaceous in color, they can vary from yellow–brown to erythematous, especially in lightly pigmented skin. Upon diascopy, in which pressure induces blanching, the lesions are said to have the color of “apple jelly” (Fig. 93.4); this finding is usually easier to appreciate in lightly pigmented skin. Individual plaques can develop central clearing leading to an annular configuration or they can contain prominent telangiectasias (angiolupoid sarcoidosis). Dermoscopic features include small translucent yellow to orange globules, linear vessels, and central scar-like areas. Additional variants of sarcoidosis of relevance to dermatologists include Löfgren syndrome, Darier–Roussy disease, and lupus pernio. Patients with Löfgren syndrome present acutely with fever, arthritis, hilar adenopathy, and erythema nodosum. They often require supportive measures and occasionally systemic corticosteroids, with spontaneous resolution occurring over 1–2 years. Patients with Darier–Roussy sarcoidosis present with painless, firm, subcutaneous nodules or plaques without epidermal changes. This variant represents sarcoidosis limited to the panniculus and is often associated with systemic sarcoidosis. Lupus pernio is characterized by papulonodules and plaques, which are often on the nose and cheeks and have a violaceous color, along with scale; there may be a beaded appearance along the nasal rim (see Fig. 93.3C). Recognition of lupus pernio is important because of its association with chronic sarcoidosis of the lungs (~75% of patients) and of the upper respiratory tract (~50% of patients). The most important nonspecific cutaneous manifestation of sarcoidosis is erythema nodosum (Fig. 93.5). Erythema nodosum is associated with subacute, transient sarcoidosis that usually resolves spontaneously and typically does not require systemic corticosteroid therapy. In general, there are no additional cutaneous manifestations.



$

CHAPTER

93 Non-infectious Granulomas

Fig. 93.2 Cutaneous sarcoidosis – papules and plaques. A Cutaneous sarcoidosis usually consists of papules and plaques with a typical reddish-brown to violet–brown color. B, C Lesions often favor the nose, lips and perioral region. D Hyperpigmented plaques, some of which have scale. E Papules of cutaneous sarcoidosis arising within a tattoo; the differential diagnosis includes foreign body

'

%

&

(

Nail changes can be seen in sarcoidosis, including clubbing, subungual hyperkeratosis, and onycholysis. Oral sarcoidosis may affect the soft mucosa, gingival tissue, tongue, hard palate, and major salivary glands. Heerfordt syndrome (uveoparotid fever) includes parotid gland enlargement, uveitis, fever, and cranial nerve palsies, usually of the facial nerve. Systemic manifestations of sarcoidosis are also protean. Lung disease occurs in ~90% of patients, ranging from alveolitis to granulomatous infiltration of the alveoli, blood vessels, bronchioles, pleura, and fibrous septa17. The end stage of pulmonary sarcoidosis is fibrosis with bronchiolectasis and “honeycombing” of the lung parenchyma. Hilar and/ or paratracheal lymphadenopathy, which is usually asymptomatic, occurs in 90% of patients. Additional systemic manifestations are outlined in Table 93.3. Childhood sarcoidosis is rare, and it usually presents with a triad of arthritis, uveitis and cutaneous lesions, along with constitutional symptoms. Peripheral lymphadenopathy is frequently present, but pulmonary involvement is less common than in adults. If sarcoidosis is being considered in a child, it is important to exclude Blau syndrome (see Ch. 45).

be observed in up to 10% of cases. Multinucleated histiocytes (“giant cells”) are usually of the Langhans type, with nuclei arranged in a peripheral arc or circular fashion. The giant cells may contain eosinophilic stellate inclusions known as asteroid bodies (Fig. 93.7) or rounded laminated basophilic inclusions known as Schaumann bodies, although neither is specific or required for the diagnosis. Asteroid bodies represent engulfed collagen, whereas Schaumann bodies likely represent degenerating lysosomes. Notably, up to 20% of biopsies of sarcoidosis contain polarizable material; therefore its presence does not exclude the diagnosis. In vulvar sarcoidosis, transepidermal elimination of the granulomas may be seen. A range exists within the histologic spectrum of sarcoidosis, from the characteristic tubercles with minimal or no surrounding lymphocytic inflammation to unusual cases with dense lymphocytic and plasmacytic infiltrates around and within the nodular histiocytic aggregates. Occasionally, these aggregates may extend into the subcutaneous fat, producing the clinical features of Darier–Roussy sarcoidosis.

Pathology

Sarcoidosis is a diagnosis of exclusion, both clinically and histologically. In order to establish the diagnosis, a supportive clinical history must be accompanied by the histologic presence of non-caseating granulomas in at least one organ system. Details of systemic manifestations are outlined in Table 93.3. An algorithm for initial and longitudinal evaluation has been proposed18.

The histopathologic hallmark of sarcoidosis is the presence of superficial and deep dermal epithelioid cell granulomas devoid of prominent infiltrates of lymphocytes or plasma cells (“naked tubercles”) (Fig. 93.6). Central caseation is usually absent, although fibrinoid deposition may

Diagnosis and Differential Diagnosis

1647

SECTION

Disorders of Langerhans Cells and Macrophages

14

Fig. 93.3 Cutaneous sarcoidosis – clinical variants. A The hypopigmented variant is more noticeable in individuals with darkly pigmented skin.   B Ichthyosiform presentation with obvious scale.   C Coalescing violaceous papules   on the nose in lupus pernio; note the notching of the nasal rim. A, Courtesy, Louis A

Fig. 93.4 Cutaneous sarcoidosis – diascopy. With diascopy, a yellow–brown, “apple jelly” color is seen.





Fragola, Jr, MD; B, Courtesy, Jean L Bolognia, MD.

$

%

Fig. 93.5 Erythema nodosum in a patient with sarcoidosis. These patients often have hilar lymphadenopathy. Löfgren syndrome consists of erythema nodosum, hilar lymphadenopathy, fever, and arthritis. Courtesy, Louis A Fragola, Jr, MD.  

&

1648

Serologically, elevated antinuclear antibody titers occur in ~30% of patients. The serum angiotensin-converting enzyme (ACE) level is elevated in ~60% of patients; it has a false-positive incidence of 10%, making it a more useful test for monitoring disease progression than for establishing the diagnosis. An ACE level >2–3 times the upper limit of normal is more suggestive of sarcoidosis. Like syphilis, sarcoidosis is a great mimic and the clinical differential diagnosis depends upon the type of presenting clinical lesions. For example, a list of other disorders, in addition to sarcoidosis, that can present with annular lesions is provided in Table 19.1. Papules, nodules and plaques may be nonspecific clinically, dictating a biopsy,

and then the differential diagnosis rests upon the histopathologic findings. It is important to exclude the possibility of drug-induced cutaneous sarcoidosis (e.g. IFN-α for hepatitis C viral infection, TNF-α inhibitors). The histologic differential diagnosis is broad, and includes multiple infections that lead to granulomatous inflammation. Special stains for acid-fast and fungal organisms should be obtained. When clinically appropriate, tissue culture should be performed. Increasingly, PCR is being utilized to exclude infections, including mycobacterial. Both tuberculoid leprosy and lupus vulgaris are in the differential diagnosis and for the latter, a QuantiFERON®-TB Gold test may provide additional information. It is especially important to exclude infectious etiologies before initiating immunosuppressive agents. Other histologic mimics include foreign body reactions to zirconium, beryllium, silica, tattoo ink, or soft tissue fillers. Special laboratory techniques, including histochemical, microincineration or spectrophotometric examinations, may be required to identify the causative agents (see Table 94.3). Specimens should be polarized to exclude birefringent foreign material as a causative agent, although up to 20% of known sarcoidal granulomas will have foreign material present within them. This finding is particularly common in lesions from the elbows and knees. Therefore, the dermatologic diagnoses of foreign body granuloma and sarcoidosis are not mutually exclusive19. In addition, granulomatous mycosis fungoides, Hodgkin disease, granulomatous rosacea, cutaneous Crohn disease, Blau syndrome (see Ch. 45), cheilitis granulomatosa, and the sarcoidal reaction to an underlying lymphoma can have histologic appearances similar to

CHAPTER

Organ

% of patients affected

Clinical manifestations/radiographic and laboratory findings

Lungs

90–95

Dyspnea, non-productive cough/pulmonary infiltrates, fibrosis, restrictive lung disease (↓VC, ↓RV, ↓TLC, ↓DLCO)

CXR, high resolution chest CT scan (more sensitive than CXR), PFTs that include DLCO

Lymph nodes (LN)

30–40*

Lymphadenopathy/enlarged hilar and/or paratracheal LN

CXR, high resolution chest CT scan (more sensitive than CXR)

Eyes

25

Uveitis (can be asymptomatic despite being severe), conjunctivitis, sicca symptoms

Yearly ophthalmologic examination

Liver/spleen

10–20

Hepatomegaly and/or splenomegaly (rarely clinically relevant), cirrhosis, consequences of splenic enlargement (e.g. thrombocytopenia)/↑LFTs, ↓plts



25 (5% clinically relevant)

Palpitations, sudden death, CHF/arrhythmias, cardiomegaly



CNS and peripheral nervous system

10–20

Neuropathies – cranial, spinal cord, peripheral, small fiber



Upper respiratory tract, including sinuses

5–10

Sinusitus, nasal congestion, stridor, parotiditis

Referral to otolaryngologist and/or dedicated imaging

Bones

5–10

Usually asymptomatic/lytic bone lesions

Radiography

Joints/muscles

5–10

Arthritis, weakness (up to a third of patients have severe fatigue), myopathy



Heart

Evaluation

LFTs, physical examination If clinically relevant hypersplenism suspected, abdominal/pelvic CT scan (lymphadenopathy common finding)



EKG, echocardiogram, Holter monitor If any abnormalities on history, physical examination, or initial screening, referral to cardiologist and additional testing (PET scan, cardiac MRI)



Dictated by symptoms (e.g. MRI, nerve conduction studies) • Referral to neurologist

Referral to rheumatologist EMG



Bone marrow

50



Lymphopenia (↓CD4+:CD8+ ratio), leukopenia, eosinophilia, hypergammaglobulinemia, nonhemolytic anemia (5%) • Elevated risk of developing lymphoma is debatable**

CBC, SPEP

Kidneys

10–40

Nephrolithiasis/hypercalciuria, ↓renal function



Endocrine

5–10









“Masses” – GI tract (luminal), ovarian, testicular – often asymptomatic • Granulomatous breast infiltration that can lead to ulceration

Site-specific imaging

upper trunk

Decreased elastic fibers in the papillary and mid reticular dermis; thickened collagen bundles

Heritable Disorders of Connective Tissue

97

DIFFERENTIAL DIAGNOSIS OF PSEUDOXANTHOMA ELASTICUM

*† Also referred to as periumbilical perforating PXE.

Occasionally associated with an increased calcium–phosphate product in the setting of chronic kidney disease.

‡Similar lesions have been reported on the breasts. §Within the spectrum of fibroelastolytic diseases of the skin.

Table 97.4 Differential diagnosis of pseudoxanthoma elasticum (PXE). The differential diagnosis also includes PXE-like skin lesions in patients receiving D-penicillamine, after local exposure to saltpeter, and in chronic kidney disease. In addition, the possibility of underlying β-thalassemia or sickle cell anemia needs to be considered.  

Fig. 97.8 Funduscopic findings in pseudoxanthoma elasticum (PXE). A Broad, lightly colored streaks (arrow) represent angioid streaks.   B Mottling with “peau d’orange” color changes (arrow) over the entire retinal pigment epithelium, which may precede the onset of angioid streaks and represents the most common ophthalmologic finding in PXE.  

A

Fig. 97.7 Mucosal lesions in pseudoxanthoma elasticum. Yellow papules on the inner aspect of the lower lip. Courtesy, Addenbrooke’s Hospital, Cambridge, UK.  

stains for elastin (Verhoeff–van Gieson) and calcium (von Kossa) are sometimes necessary to visualize the characteristic alterations in the elastic fibers. In some patients without skin manifestations who are suspected to have PXE because of other findings, such as angioid streaks, biopsy of a pre-existing scar can confirm the diagnosis35. Increased deposition of matrix proteins with a high degree of affinity for calcium is observed on an ultrastructural level; these proteins include osteonectin, fibronectin and vitronectin, as well as alkaline phosphatase and bone sialoprotein36. Serum levels of calcium and phosphate are normal23.

Differential Diagnosis Although the characteristic skin lesions of PXE are easily diagnosed in younger patients, actinic damage within chronically sun-exposed sites in older individuals can clinically mimic the yellowish, lax plaques of

B

PXE. However, the latter involves the neck but not the axillae or groin. The differential diagnosis may also include late-onset focal dermal elastosis, elastoderma, perforating calcific elastosis, PXE-like papillary dermal elastolysis, and white fibrous papulosis of the neck (see Table 97.4).

1705

SECTION

15 Atrophies and Disorders of Dermal Connective Tissue

A MULTIDISCIPLINARY APPROACH TO MANAGEMENT OF PSEUDOXANTHOMA ELASTICUM

Skin No specific treatment is available Surgical intervention for excessive skin folds46

Eyes Prevention and early detection Biannual funduscopic examination Regular use of an Amsler grid to assess for central visual field defects • Use of sunglasses • Diet/vitamins rich in antioxidants • Avoidance of head trauma, heavy straining, and smoking • •

Treatment Intravitreal injections of VEGF antagonists (e.g. bevacizumab, ranibizumab)47 • Laser photocoagulation or photodynamic therapy with verteporfin for choroidal neovascularization related to angioid streaks in patients with visual symptoms (high recurrence rates; now used infrequently)48 • Macular translocation (only for extensive neovascularization)49 •

Cardiovascular system Prevention and early detection

Fig. 97.9 Histopathology of pseudoxanthoma elasticum (PXE). Purple clumps in the mid and deep reticular dermis in H&E-stained sections represent calcium deposits on elastic fibers in advanced PXE (see left inset). An orcein stain highlights the fragmented, clumped elastic fibers (see right inset). Courtesy, Lorenzo  

Cerroni, MD.

Skin lesions with the same morphology and distribution as PXE and similar histologic features have been observed in patients receiving D-penicillamine (which interferes with desmosine cross-linking in elastin; see below)37, after local exposure to saltpeter38, in chronic kidney disease39, and (historically) in L-tryptophan-induced eosinophilia myalgia syndrome40. There is no calcification of the abnormal fibers in D-penicillamine-induced PXE-like skin changes, whereas calcification occurs with saltpeter exposure and chronic kidney disease. Ophthalmologic and cardiovascular findings are absent and the skin lesions may resolve after cessation of the causative exposure or (in patients with renal disease) normalization of the serum calcium–phosphate product. A PXE-like phenotype is present in up to 20% of the patients with β-thalassemia (Mediterranean populations) or sickle cell anemia41. Affected individuals may have characteristic cutaneous involvement as well as angioid streaks and vascular stigmata, but none of their siblings without a hematologic disorder have signs of PXE, and mutations in ABCC6 have not been detected. Interestingly, down-regulation of ABCC6 expression in the liver has been observed in a mouse model of β-thalassemia, suggesting a possible pathogenic mechanism42. PXE-like skin lesions have also been encountered in amyloid elastosis, which typically occurs in the setting of primary systemic amyloidosis; histologic examination reveals amyloid deposits that encase dermal elastic fibers, which may be short and fragmented43.

Baseline electrocardiogram and echocardiogram Annual cardiovascular examination • Healthy lifestyle with balanced diet, regular exercise, weight control, and avoidance of smoking and excessive alcohol intake • Magnesium supplementation (e.g. magnesium carbonate-containing * phosphate binders) • Moderate calcium intake (as appropriate for age) • Low-dose therapy with acetylsalicylic acid if not contraindicated • •

Treatment Correction of hyperlipidemia and hypertension Low-dose acetylsalicylic acid, pentoxyfylline, cilostazol, or clopidogrel for intermittent claudication

• •

*A diet high in50magnesium was shown to reduce connective tissue mineralization in a mouse model of PXE ; clinical trials are in progress.

Table 97.5 A multidisciplinary approach to management of pseudoxanthoma elasticum. Studies in mice have shown reduced dystrophic calcification with administration of bisphosphonates or 4-phenylbutyrate, which promotes maturation of mutant ABCC644,45; clinical trials are in progress. VEGF, vascular endothelial growth factor.  

■ Both heritable (autosomal dominant, autosomal recessive, and X-linked recessive) and acquired forms ■ Features loose, sagging skin with reduced elasticity and resilience ■ Extracutaneous manifestations include emphysema, hernias, diverticula, and craniofacial anomalies

Treatment An approach to the multidisciplinary management of PXE is presented in Table 97.544–50.

CUTIS LAXA

The clinical differences between cutis laxa (CL) and EDS were delineated in 1923 by F Parkes Weber3, and the generalized nature of the elastolysis and potential for internal involvement were recognized by Goltz and co-workers in 196551.

Synonyms:  ■ Dermatochalasia ■ Dermatomegaly ■ Generalized

Epidemiology

Key features

The heritable forms of CL are rare and no precise estimate of their prevalence is available. There appears to be no racial or ethnic predilection, and inheritance can be autosomal dominant, autosomal recessive, or X-linked recessive. Heritable CL is typically apparent at birth or during early childhood, but the development of lax skin is occasionally delayed until early adulthood in autosomal dominant forms. Acquired CL frequently has a later onset.

elastolysis ■ Generalized elastorrhexis

1706

History

■ Group of conditions characterized by sparse and fragmented elastic fibers

CL represents a disorder of the elastic fiber network and can involve multiple tissues, including internal organs as well as the skin. Insights into the molecular bases of inherited forms of CL have refined their classification52 (Table 97.6). Mutations in the elastin gene (ELN) that lead to qualitative as well as quantitative abnormalities in this protein have been identified as the cause of an autosomal dominant form of CL53. Defects in several genes can underlie autosomal recessive CL (ARCL), which tends to be more severe and is divided into groups with different patterns of extracutaneous involvement. ARCL type 1 features potentially fatal involvement of the lungs, vascular abnormalities, and gastrointestinal/genitourinary diverticula, whereas ARCL types 2 and 3 (de Barsy syndrome) are characterized by craniofacial anomalies and delayed growth and development (see Table 97.6). Fibulins are calcium-dependent glycoproteins that stabilize ECM networks and provide support for elastic fiber assembly. Biallelic mutations in the genes that encode fibulin 5 and fibulin 4 (EGF-containing fibulinlike extracellular matrix protein 2) cause ARCL types 1A and 1B, respectively; a heterozygous duplication within the fibulin 5 gene was also found to underlie CL in one patient54–56. Mutations in the latent TGF-β binding protein-4 gene (LTBP4) result in ARCL type 1C, which is characterized by severe pulmonary, gastrointestinal, and genitourinary involvement57. LTBP4 is an ECM protein that binds to fibrillin and controls the bioavailability of TGF-β, and LTBP4 deficiency leads to aberrant TGF-β activity and defective elastic fiber assembly in many tissues (see Fig. 95.7). Defects in several intracellular proteins that play a role in metabolic pathways underlie other forms of ARCL. For example, biallelic mutations in ATP6V0A2, which encodes the A2 subunit of the vacuolar H+-ATPase, produce a phenotypic spectrum that ranges from primarily “wrinkly skin” to ARCL type 2A featuring facial dysmorphism, microcephaly, joint laxity, and delayed growth and development58. ATP6V0A2 defects result in impaired N- and O-glycosylation, vesicular transport, and secretion of tropoelastin, thereby reducing production of functional elastin. Mutations in the genes encoding the mitochondrial enzymes pyrroline-5-carboxylate reductase 1 (PYCR1) and pyrroline5-carboxylate synthetase cause ARCL types 2B and 3A/B, which have prominent progeroid features and neurodevelopmental manifestations thought to be related to mitochondrial dysfunction59 (see Table 97.6). PYCR1 mutations may also lead to features of EDS (e.g. joint hypermobility) and osteogenesis imperfecta59a. These enzymes are critical for the biosynthesis of proline, which is a major component of collagen and plays a role in an oxidative cycle important to cellular metabolism. In PYCR1 deficiency, there is increased apoptosis of fibroblasts following oxidative stress. An alternate pathogenic mechanism for CL, in particular acquired variants, is enhanced degradation of elastic fibers. Sagging of the skin,

B

usually with little or no associated internal organ involvement, can develop in the weeks to months following the onset of an inflammatory skin condition such as a drug reaction, chronic urticaria, or Sweet syndrome. In these cases, release of elastases into the extracellular milieu by inflammatory cells (e.g. neutrophils, monocytes/macrophages) leads to proteolytic degradation of elastic fibers60. Generalized or localized CL can develop following a Sweet syndrome-like neutrophilic dermatosis (referred to as Marshall syndrome) some of these patients may have increased susceptibility to proteolysis due to α1-antitrypsin deficiency. Immunopathogenic mechanisms may play a role in some cases of acquired CL, as evidenced by the occurrence of acral or generalized CL in association with monoclonal gammopathies and observation of IgG, IgA, or amyloid deposition on elastic fibers in lesional skin61. In addition, there may be an underlying genetic susceptibility for the development of CL, e.g. polymorphisms or “mild” mutations in the elastin and/or fibulin 5 genes62. Finally, CL-like cutaneous changes as well as elastosis perforans serpiginosa and PXE-like findings have been observed in patients treated for a prolonged period with high-dose D-penicillamine for conditions such as Wilson disease or cystinuria. D-Penicillamine can interfere with elastin cross-linking by two mechanisms. First, D-penicillamine is a copper chelator and can lower serum copper levels, which reduces the activity of lysyl oxidase, an enzyme required for elastin cross-linking (see Ch. 95)63. Second, D-penicillamine can chemically block the allysine and lysine residues that come together to form desmosine crosslinks. Because of these actions, newly synthesized elastin molecules do not become stably cross-linked. Instead, they are subject to rapid proteolysis, thus precluding the synthesis of functional elastic fibers.

CHAPTER

97 Heritable Disorders of Connective Tissue

Pathogenesis

Clinical Features All forms of CL are characterized by loose, sagging skin with reduced elasticity and resilience. This often gives the affected patient an “aged” facial appearance with down-slanting palpebral fissures and a long philtrum (Fig. 97.10). Cutaneous findings are present at birth in most heritable forms of CL but may develop later in life in autosomal dominant as well as acquired variants. The laxity and wrinkling usually progress over time, although improvement of the skin with age has been noted in ARCL type 2A. Skin involvement is frequently generalized; however, it can be primarily acral, especially in ARCL type 2B or acquired CL. In some patients with CL, clinical manifestations are limited to the skin, and the phenotype is primarily of cosmetic concern. In other patients, the cutaneous findings are associated with prominent extracutaneous features, which can include emphysema, umbilical and inguinal hernias, gastrointestinal and genitourinary tract diverticula, cardiac or arterial abnormalities, skeletal or joint involvement, and delayed growth and development. The extracutaneous manifestations,

C

Fig. 97.10 Clinical features in cutis laxa. A Loose skin and drooping jowls in an infant with heritable cutis laxa. B Sagging folds of skin giving a prematurely aged appearance to a man with acquired cutis laxa associated with multiple myeloma. C Acquired cutis laxa with pseudoxanthoma elasticum-like skin changes from penicillamine use for cystinuria. A, Courtesy, Thomas Schwarz, MD; B, Courtesy, Jeffrey P Callen, MD; C, Courtesy, Jonathan Leventhal, MD.  

A

1707

SECTION

Atrophies and Disorders of Dermal Connective Tissue

15

HERITABLE FORMS OF CUTIS LAXA AND RELATED CONDITIONS

Disorder

Inheritance

Gene

Protein

Distribution of cutis laxa

Additional features

ELN

Elastin

Generalized



FBLN5

Fibulin 5

FBLN4 (EFEMP2)

Fibulin 4

Generalized



FBLN5

Fibulin 5

Heritable forms of cutis laxa AD†

ADCL

ARCL type 1B

AR

ARCL type 1A

Cardiac valve abnormalities, aortic dilatation (variable) • Emphysema (uncommon) • Hernias‡ Arterial or aortic tortuosity/aneurysms (1B) and stenosis • Emphysema (more severe in 1A) • Bladder diverticula, hernias‡ • In 1B: joint laxity, arachnodactyly, fractures, micrognathia

ARCL type 1C (Urban–Rifkin–Davis syndrome)

AR

LTBP4

Latent TGF-β binding protein-4

Generalized



ARCL type 2A (Debré type; allelic to wrinkly skin syndrome)

AR

ATP6V0A2

Vacuolar H+-ATPase V0, subunit A2

Generalized; improves over time



ARCL type 2B

AR

PYCR1

Pyrroline-5-carboxylate reductase 1

Progeroid ADCL (PADCL)

AD

ALDH18A1

Pyrroline-5-carboxylate synthetase

Generalized; may favor dorsal hands/feet (2B) or improve over time; occasionally fat pads (e.g. on buttocks; DBS-A)

De Barsy syndrome (DBS) A (ARCL type 3A)

AR

ARCL types 2C and 2D

AR

ATP6V1E1 (2C) ATP6V1A (2D)

Vacuolar H+-ATPase V1, subunits E1 and A

Generalized with sparse or subcutaneous fat; large skin folds on extremities, fat pads on buttocks; may improve over time (2D)



Gerodermia osteodysplastica (geroderma osteodysplasticum)

AR

GORAB

Golgin, RAB6interacting

Primarily on dorsal hands/feet



Macrocephaly, alopecia, CL, and scoliosis (MACS)

AR

RIN2

RAS and RAB interactor 2

Generalized, most pronounced on face



De Barsy syndrome (DBS) B (ARCL type 3B)

Pulmonary malformations/ emphysema (severe, often fatal) • Pulmonary arterial stenosis, valvular defects • GI and GU malformations (diverticula, stenoses) • Micrognathia, large fontanelles • Joint laxity, hypotonia Translucent skin with prominent veins (especially 2B, DBS) • Ocular abnormalities: strabismus & high myopia (2A); corneal opacities & cataracts (DBS, PADCL) • Facial dysmorphism§; triangular face with more progeroid appearance (2B, DBS); large fontanelles • Microcephaly, partial pachygyria (2A), absent corpus callosum (2B) • Intellectual disability; neurologic degeneration (2A); dystonia/athetosis (DBS) • Congenital hip dysplasia, joint laxity, hypotonia, scoliosis, short stature; osteopenia (2B, DBS) • Cranial arterial tortuosity (DBS-A, PADCL) • O- and N-glycosylation defect (2A||) Pneumothoraces Cardiac abnormalities, aortic dilation • “Mask-like” triangular face, hypotonia; variable hip dysplasia, marfanoid habitus • Neurodevelopmental abnormalities (2D) •

Malar hypoplasia, prognathism, oblique furrow lateral to eyebrows • Joint laxity • Osteoporosis, fractures, dwarfism Sparse hair Gingival hypertrophy, facial dysmorphism • Macrocephaly • Scoliosis, joint laxity •

Table 97.6 Heritable forms of cutis laxa (CL) and related conditions. In addition to ARCL types 2A and 2C, CL can occur in other congenital disorders of glycosylation, e.g. due to mutations in a component of oligomeric Golgi complex 7 (COG7; multiple-system malformations) or steroid 5-α-reductase 3 (SRD5A3; also ichthyosis, ocular colobomas, and midline brain malformations). Transaldolase deficiency can present with neonatal CL (generalized or of the forehead) that improves over time as well as hypertrichosis, hepatosplenomegaly, hemolytic anemia, and GU malformations. “Neonatal CL with a marfanoid phenotype” was described in an infant who lacked immunohistochemical evidence of laminin-β1 in the skin. AD, autosomal dominant; ALDH18A1, aldehyde dehydrogenase 18 family, member A1; AR, autosomal recessive; EFEMP2, EGF-containing fibulin-like extracellular matrix protein 2; GI, gastrointestinal; GU, genitourinary; TGF, transforming growth factor; X-R, X-linked recessive.  

1708

CHAPTER

Disorder

Inheritance

Gene

Protein

Distribution of cutis laxa

ATP7A

ATPase, Cu2+transporting, α-polypeptide

Generalized, most pronounced on face and neck



Additional features

Heritable forms of cutis laxa Occipital horn syndrome

X-R

Easy bruising, coarse hair (variable) Arterial tortuosity • Chronic diarrhea; bladder diverticula • Long face, high forehead, hooked nose • Developmental delay • Wedge-shaped occipital calcifications • Joint laxity •

Related heritable conditions that feature lax and/or redundant skin SLC2A10 (GLUT10)

Solute carrier family 2, member 10 (a glucose transporter)

Generalized; soft, hyperextensible skin has also been described



AR

B3GAT3

Glucuronosyltransferase I

Wrinkled acral skin



Costello syndrome

AR

HRAS

HRAS

Variable, especially on hands and feet



Donohue syndrome (“leprechaunism”; see Ch. 101)

AR

INSR

Insulin receptor

Variable



Finnish-type amyloidosis

AD

GSN

Gelsolin

Generalized



Cranioectodermal dysplasia (Sensenbrenner syndrome)

AR

Circumferential skin creases, Kunze type

Arterial tortuosity syndrome

AR

Larsen-like syndrome

Nonsyndromic “Michelin tire baby”

Telangiectasias on cheeks (variable) Arterial tortuosity • Long face, micrognathia, high-arched palate • Joint laxity and contractures •

Heritable Disorders of Connective Tissue

97

HERITABLE FORMS OF CUTIS LAXA AND RELATED CONDITIONS

Joint dislocations, craniofacial dysmorphism, short stature • Congenital heart defects Deep palmoplantar creases, acanthosis nigricans, periorificial papillomas • Curly or sparse hair, coarse facies • Cardiac malformations • Mental and growth retardation • Risk of malignancies, e.g. rhabdomyosarcoma Generalized lipodystrophy, hypertrichosis, acanthosis nigricans • Insulin resistance • Distinctive “elfin” facies • Severe growth retardation Corneal dystrophy Polyneuropathy



IFT122 IFT43

Intraflagellar transport proteins 122 and 43

WDR35 WDR19

WD repeat domain 35 and 19

AD, AR

MAPRE2

Microtubule-associated protein RP/EB family member 2

AD

TUBB

Tubulin-β class I

AD

?

?

Generalized; redundant skin folds at neck, ankles, and wrists



Sparse, fine hair; short, broad nails Narrow thorax, short proximal limbs, joint laxity, brachydactyly, dolichocephaly, dysmorphic facies, dental anomalies • Nephronophthisis, hepatic fibrosis, retinal dystrophy

Multiple circumferential creases/folds of skin on the extremities (see Fig. 97.12) > neck > trunk (excess rather than lax skin); may resolve over time





Cleft palate, short stature, dysmorphic facies (e.g. epicanthal folds, small eyes), overfolded helices • Intellectual disability Affected skin may have excess fat or smooth muscle, and the latter is often associated with hypertrichosis; elastic fibers are usually normal (fragmentation noted in only one report)



†An AR form of cutis laxa due to a homozygous elastin mutation has been reported in two related families. ‡E.g. inguinal, umbilical, diaphragmatic. §Features may include a broad forehead and midfacial hypoplasia as well as findings related to the lax skin (e.g. down-slanting palpebral fissures, long philtrum). ||Can be assessed via analysis of the glycosylation of serum transferrin ± apolipoprotein C-III.

Table 97.6 Heritable forms of cutis laxa (CL) and related conditions. (cont’d)  

particularly pulmonary complications, can cause considerable morbidity and mortality64. Association with congenital hemolytic anemia has also been reported65. The cutaneous and extracutaneous features of specific types of heritable CL are summarized in Table 97.6. Generalized acquired CL without an identifiable trigger may be clinically indistinguishable from milder heritable forms of CL, e.g. late-

onset autosomal dominant CL. Generalized or localized forms of acquired CL can also occur in association with a plasma cell dyscrasia (see Fig. 97.10B), as a consequence of drug intake (particularly penicillamine), and subsequent to a systemic or cutaneous inflammatory disorder (Table 97.7). In the latter situation, the inflammatory reaction is followed by progressive sagging of the skin, which can become exten-

1709

SECTION

Atrophies and Disorders of Dermal Connective Tissue

15

ACQUIRED CUTIS LAXA: ASSOCIATED CONDITIONS

Skin disorders Urticaria and/or angioedema Drug eruptions (e.g. due to penicillin or an SSRI) • Sweet syndrome-like eruptions (Marshall syndrome ) * • Arthropod bite reactions • Erythema multiforme • Dermatitis herpetiformis • Lupus panniculitis • Interstitial granulomatous dermatitis • Cutaneous mastocytosis • Cutaneous lymphoma • •

Extracutaneous inflammatory disorders Rheumatoid arthritis Systemic lupus erythematosus • Nephrotic syndrome • Celiac disease • Sarcoidosis • •

Hematologic disorders

Fig. 97.11 Histologic features of cutis laxa. Dermal elastic fibers are sparse and fragmented. Courtesy, Lorenzo Cerroni, MD.  

Monoclonal gammopathy (especially acral CL; underlying plasma cell dyscrasia) • Congenital hemolytic anemia •

Infectious diseases Febrile viral syndrome Borrelia burgdorferi infection • Syphilis • •

Drug intake (also see drug eruptions above) Penicillamine Isoniazid

• •

*Referred to as type II acquired CL, with other forms of acquired CL classified as type I. Table 97.7 Acquired cutis laxa (CL): associated conditions. Generalized or localized CL (including Marshall syndrome) can occur in the setting of α1-antitrypsin deficiency. SSRI, selective serotonin reuptake inhibitor.  

Fig. 97.12 “Michelin tire baby” phenotype. Note the circumferential skin creases on the extremities. Courtesy, Antonio Torrelo, MD.  

sive and lead to a prematurely aged appearance. Acquired CL most commonly develops in adults and when it presents with generalized skin involvement, often beginning on the face and neck, there can be associated internal manifestations such as emphysema and diverticula (e.g. gastrointestinal, genitourinary). Occasionally, localized CL is found predominantly around the eyes (blepharochalasis) or on the distal extremities, particularly the palms and soles. Marshall syndrome refers to CL in association with a Sweet syndrome-like neutrophilic dermatosis, and it occurs primarily in infants and young children66.

Pathology In the skin of patients with CL, the characteristic histologic feature is sparse and/or fragmented elastic fibers (Fig. 97.11). This ranges from virtual absence of elastic fibers in a newborn with severe CL (e.g. ARCL type 1) to fragmentation but a normal density of fibers in late-onset autosomal dominant CL. Electron microscopy shows irregular fragmentation of the elastic fiber structure. In some patients, elastic fiber abnormalities are accompanied by alterations in collagen fibers, which likely reflect a general perturbation of the ECM and mechanical properties of the skin due to the primary elastic fiber defect.

Differential Diagnosis

1710

Clinical findings similar to CL can develop as a consequence of the normal skin aging. In contrast to CL, the hyperextensible skin of patients with EDS retains elasticity and recoil, with the exception of the rare dermatosparaxis type. Skin fragility and bruising represent additional features of EDS but not CL. In PXE and the related PXE-like disorder with multiple coagulation factor deficiency, the skin can be loose and sagging without recoil; however, the primary papular lesions at the predilection sites distinguish these conditions from CL.

Mid-dermal elastolysis is an acquired disorder with a predilection for young and middle-aged women that is characterized by circumscribed or diffuse areas of fine wrinkling, most often in sun-exposed sites on the upper trunk, lateral neck, and upper arms (see Ch. 99)67. It features the pathognomonic histopathologic finding of a band-like loss of elastic fibers in the mid dermis. Anetoderma presents as focal areas of flaccid skin (e.g. 1 to 2 cm in diameter) with loss of elastic tissue and may have an antecedent inflammatory process. It is histologically and ultrastructurally identical to CL and may be regarded as a variant of acquired localized CL with smaller, circumscribed lesions. Additional rare syndromes that can present with lax skin and elastic fiber abnormalities are outlined in Table 97.668. Of note, the “Michelin tire baby” phenotype of congenital circumferential skin creases on the extremities may be reminiscent of CL, but the folds reflect excess tissue rather than cutaneous laxity (Fig. 97.12).

Treatment The redundant and sagging skin may be of major cosmetic concern to patients with CL, and reconstructive surgery can provide improvement with significant psychosocial benefit. Surgical wounds heal with scars that have a normal appearance and tensile strength. However, sagging may reoccur, necessitating additional surgical procedures. The associated internal organ involvement requires appropriate care through a multidisciplinary approach. For additional online figures visit www.expertconsult.com

eFig. 97.1 Molluscoid pseudotumors on the knees in a patient with Ehlers–Danlos syndrome.

eFig. 97.2 Atrophic scar in a patient with the classical type of Ehlers–Danlos syndrome.

eFig. 97.3 Typical facial features of the vascular type of Ehlers–Danlos syndrome. Courtesy,

eFig. 97.4 Clinical features of pseudoxanthoma elasticum. Yellowish papules and “cobblestoned” plaques in the antecubital fossa.





Addenbrooke’s Hospital, Cambridge, UK.



CHAPTER

97 Heritable Disorders of Connective Tissue

Online only content



Courtesy, Julie V Schaffer, MD.

1710.e1

CHAPTER

1. Sybert VP. Genetic Skin Disorders. Oxford Monographs on Medical Genetics, No. 33. Oxford: Oxford University Press; 1997. 2. Pulkkinen L, Ringpfeil F, Uitto J. Progress in heritable skin diseases: molecular bases and clinical implications. J Am Acad Dermatol 2002;47:91–104. 3. McKusick VA. Heritable Disorders of Connective Tissue. 4th ed. St Louis: Mosby; 1972. 4. Beighton P, De Paepe A, Steinmann B, et al. EhlersDanlos syndromes: revised nosology, Villefranche, 1997. Ehlers-Danlos National Foundation (USA) and Ehlers-Danlos Support Group (UK). Am J Med Genet 1998;77:31–7. 5. Malfait F, De Paepe A. The Ehlers-Danlos syndrome. Adv Exp Med Biol 2014;802:129–43. 5a. Malfait F, Francomano C, Byers P, et al. The 2017 international classification of the Ehlers-Danlos syndromes. Am J Med Genet C Semin Med Genet 2017;175:8–26. 6. Myllyharju J, Kivirikko KI. Collagens and collagenrelated diseases. Ann Med 2001;33:7–21. 7. Pepin MG, Schwarze U, Rice KM, et al. Survival is affected by mutation type and molecular mechanism in vascular Ehlers-Danlos syndrome (EDS type IV). Genet Med 2014;16:881–8. 8. Schalkwijk J, Zweers MC, Steijlen PM, et al. A recessive form of the Ehlers-Danlos syndrome caused by tenascin-X deficiency. N Engl J Med 2001;345:1167–75. 9. Beighton PH, Solomon L, Soskolne CL. Articular mobility in an African population. Ann Rheum Dis 1973;32:413–18. 10. Steinmann B, Royce PM. Connective Tissue and its Heritable Disorders. Molecular Genetic, and Medical Aspects. New York: Wiley-Liss; 1993. 11. Atzinger CL, Meyer RA, Khoury PR, et al. Cross-sectional and longitudinal assessment of aortic root dilation and valvular anomalies in hypermobile and classic Ehlers-Danlos syndrome. J Pediatr 2011;158:826–30. 12. De Wandele I, Rombaut L, Leybaert L, et al. Dysautonomia and its underlying mechanisms in the hypermobility type of Ehlers-Danlos syndrome. Semin Arthritis Rheum 2014;44:93–100. 13. Pepin M, Schwarze U, Superti-Furga A, Byers PH. Clinical and genetic features of Ehlers-Danlos syndrome type IV, the vascular type. N Engl J Med 2000;342:673–80. 14. Murray ML, Pepin M, Peterson S, Byers PH. Pregnancyrelated deaths and complications in women with vascular Ehlers-Danlos syndrome. Genet Med 2014;16:874–80. 15. Ong KT, Perdu J, De Backer J, et al. Effect of celiprolol on prevention of cardiovascular events in vascular Ehlers-Danlos syndrome: a prospective randomised, open, blinded-endpoints trial. Lancet 2010;376:1476–84. 16. Balzer F. Recherches sur les caractères anatomiques du xanthelasma. Arch Physiol. 1884;4:65–80. 17. Chauffard MA. Xanthelasma disséminé et symmétrique sans insufficiance hépatique. Bull Soc Med Hop Paris 1889;6:412–19. 18. Darier J. Pseudo-xanthome élastique. IIIe Congrès Intern de Dermat de Londres. 1896;5:289–95. 19. Grönblad E. Angioid streaks – pseudoxanthoma elasticum. Acta Ophthalmol 1929;7:329. 20. Strandberg J. Pseudoxanthoma elasticum. Z Haut Geschlechtskr 1929;31:689–94. 21. Ringpfeil F, Lebwohl MG, Christiano AM, Uitto J. Pseudoxanthoma elasticum: mutations in the MRP6 gene encoding a transmembrane ATP-binding cassette (ABC) transporter. Proc Natl Acad Sci USA 2000;97:6001–6. 22. Ringpfeil F, McGuigan K, Fuchsel L, et al. Pseudoxanthoma elasticum is a recessive disease characterized by compound heterozygosity. J Invest Dermatol 2006;126:782–6. 23. Neldner KH. Pseudoxanthoma elasticum. Clin Dermatol 1988;6:1–159. 24. Martin L, Maître F, Bonicel P, et al. Heterozygosity for a single mutation in the ABCC6 gene may closely mimic PXE: consequences of this phenotype overlap for the definition of PXE. Arch Dermatol 2008;144:301–6. 25. Jansen RS, Duijst S, Mahakena S, et al. ABCC6-Mediated ATP Secretion by the Liver Is the Main Source of the Mineralization Inhibitor Inorganic Pyrophosphate in the Systemic Circulation-Brief Report. Arterioscler Thromb Vasc Biol 2014;34:1985–9.

26. Hendig D, Schulz V, Arndt M, et al. Role of serum fetuin-A, a major inhibitor of systemic calcification, in pseudoxanthoma elasticum. Clin Chem 2006;52:227–34. 27. Miglionico R, Armentano MF, Carmosino M, et al. Dysregulation of gene expression in ABCC6   knockdown HepG2 cells. Cell Mol Biol Lett 2014;19:  517–26. 28. Nitschke Y, Baujat G, Botschen U, et al. Generalized arterial calcification of infancy and pseudoxanthoma elasticum can be caused by mutations in either ENPP1 or ABCC6. Am J Hum Genet 2012;90:25–39. 29. Li Q, Schumacher W, Siegel D, et al. Cutaneous features of pseudoxanthoma elasticum in a patient with generalized arterial calcification of infancy due to a homozygous missense mutation in the ENPP1 gene. Br J Dermatol 2012;166:1107–11. 30. Li Q, Brodsky JL, Conlin LK, et al. Mutations in the ABCC6 gene as a cause of generalized arterial calcification of infancy: genotypic overlap with pseudoxanthoma elasticum. J Invest Dermatol 2014;134:658–65. 31. Vanakker OM, Martin L, Gheduzzi D, et al. Pseudoxanthoma elasticum-like phenotype with cutis laxa and multiple coagulation factor deficiency represents a separate genetic entity. J Invest Dermatol 2007;127:584–7. 32. Li Q, Grange DK, Armstrong NL, et al. Mutations in the GGCX and ABCC6 genes in a family with pseudoxanthoma elasticum-like phenotypes. J Invest Dermatol 2009;129:553–63. 33. Lebwohl M, Lebwohl E, Bercovitch L. Prominent mental (chin) crease: a new sign of pseudoxanthoma elasticum. J Am Acad Dermatol 2003;48:620–2. 34. Nitschke Y, Rutsch F. Generalized arterial calcification of infancy and pseudoxanthoma elasticum: two sides of the same coin. Front Genet 2012;3:302. 35. Lebwohl M, Phelps RG, Yannuzzi L, et al. Diagnosis of pseudoxanthoma elasticum by scar biopsy in patients without characteristic skin lesions. N Engl J Med 1987;317:347–50. 36. Contri MB, Boraldi F, Taparelli F, et al. Matrix proteins with high affinity for calcium ions are associated with mineralization within the elastic fibers of pseudoxanthoma elasticum dermis. Am J Pathol 1996;148:569–77. 37. Bolognia JL, Braverman I. Pseudoxanthoma-elasticumlike skin changes induced by penicillamine. Dermatology 1992;184:12–18. 38. Christensen OB. An exogenous variety of pseudoxanthoma elasticum in old farmers. Acta Derm Venereol 1978;58:319–21. 39. Nickoloff BJ, Noodleman FR, Abel EA. Perforating pseudoxanthoma elasticum associated with chronic renal failure and hemodialysis. Arch Dermatol 1985;121:1321–2. 40. Mainetti C, Masouye I, Saurat JH. Pseudoxanthoma elasticum-like lesions in the L-tryptophan-induced eosinophilia-myalgia syndrome. J Am Acad Dermatol 1991;24:657–8. 41. Aessopos A, Farmakis D, Loukopoulos D. Elastic tissue abnormalities resembling pseudoxanthoma elasticum in beta thalassemia and the sickling syndromes. Blood 2002;99:30–5. 42. Martin L, Douet V, VanWart CM, et al. A mouse model   of β-thalassemia shows a liver-specific down-regulation of Abcc6 expression. Am J Pathol 2011;178:774–  83. 43. Sepp N, Pichler E, Breathnach SM, et al. Amyloid elastosis: analysis of the role of amyloid P component. J Am Acad Dermatol 1990;22:27–34. 44. Pomozi V, Brampton C, Szeri F, et al. Functional rescue of ABCC6 deficiency by 4-phenylbutyrate therapy reduces dystrophic calcification in Abcc6-/- mice. J Invest Dermatol 2017;137:595–602. 45. Li Q, Kingman J, Sundberg JP, et al. Dual effects of bisphosphonates on ectopic skin and vascular soft tissue mineralization versus bone architecture in a mouse model of generalized arterial calcification of infancy. J Invest Dermatol 2016;136:275–83. 46. Viljoen DL, Bloch C, Beighton P. Plastic surgery in pseudoxanthoma elasticum: experience in nine patients. Plast Reconstr Surg 1990;85:233–8. 47. Sawa M, Gomi F, Tsujikawa M, et al. Long-term results of intravitreal bevacizumab injection for choroidal

neovascularization secondary to angioid streaks. Am J Ophthalmol 2009;148:584–90. 48. Lim JI, Bressler NM, Marsh MJ, Bressler SB. Laser treatment of choroidal neovascularization in patients with angioid streaks. Am J Ophthalmol 1993;116:414–23. 49. Roth DB, Estafanous M, Lewis H. Macular translocation for subfoveal choroidal neovascularization in angioid streaks. Am J Ophthalmol 2001;131:390–2. 50. LaRusso J, Li Q, Uitto J. Elevated dietary magnesium prevents connective tissue mineralization in a mouse model of pseudoxanthoma elasticum. J Invest Dermatol 2009;129:1388–94. 51. Goltz RW, Hult AM, Goldfarb M, Gorlin RJ. Cutis laxa. A manifestation of generalized elastolysis. Arch Dermatol 1965;92:373–87. 52. Mohamed M, Voet M, Gardeitchik T, Morava E. Cutis Laxa. Adv Exp Med Biol 2014;802:161–84. 53. Tassabehji M, Metcalfe K, Hurst J, et al. An elastin gene mutation producing abnormal tropoelastin and abnormal elastic fibers in a patient with autosomal dominant cutis laxa. Hum Mol Genet 1998;7:1021–8. 54. Loeys B, Van Maldergem L, Mortier G, et al. Homozygosity for a missense mutation in fibulin-5 (FBLN5) results in a severe form of cutis laxa. Hum Mol Genet 2002;11:2113–18. 55. Elahi E, Kalhor R, Banihosseini SS, et al. Homozygous missense mutation in fibulin-5 in an Iranian autosomal recessive cutis laxa pedigree and associated haplotype. J Invest Dermatol 2006;126:1506–9. 56. Hucthagowder V, Sausgruber N, Kim KH, et al. Fibulin-4: a novel gene for an autosomal recessive cutis laxa syndrome. Am J Hum Genet 2006;78:1075–80. 57. Urban Z, Hucthagowder V, Schürmann N, et al. Mutations in LTBP4 cause a syndrome of impaired pulmonary, gastrointestinal, genitourinary, musculoskeletal, and dermal development. Am J Hum Genet 2009;85:593–605. 58. Kornak U, Reynders E, Dimopoulou A, et al. Impaired glycosylation and cutis laxa caused by mutations in the vesicular H+-ATPase subunit ATP6V0A2. Nat Genet 2008;40:32–4. 59. Guernsey DL, Jiang H, Evans SC, et al. Mutation in pyrroline-5-carboxylate reductase 1 gene in families with cutis laxa type 2. Am J Hum Genet 2009;85:120–9. 59a.  Vahidnezhad H, Karamzadeh R, Saeidian AH, et al. Molecular dynamics simulation of the consequences of a PYCR1 mutation (p.Ala189Val) in patients with complex connective tissue disorder and severe intellectual disability. J Invest Dermatol 2017;137:525–8. 60. Shapiro SD. Matrix metalloproteinase degradation of extracellular matrix: biological consequences. Curr Opin Cell Biol 1998;10:602–8. 61. Krajnc I, Rems D, Vizjak A, Hodl S. Acquired generalized cutis laxa with paraproteinemia (IgG lambda). Immunofluorescence study, clinical and histologic findings with review of the literature. Hautarzt 1996;47:545–9. 62. Hu Q, Reymond J-L, Pinel N, et al. Inflammatory destruction of elastic fibers in acquired cutis laxa is associated with missense alleles in the elastin and fibulin-5 genes. J Invest Dermatol 2006;126:283–90. 63. Uitto J, Pulkkinen L. Heritable disorders affecting the elastic tissues: cutis laxa, pseudoxanthoma elasticum and related disorders. In: Rimoin DL, Connor JM, Pyeritz RE, editors. Emery and Rimoin’s Principles and Practice of Medical Genetics. 3rd ed. London: Churchill Livingstone; 2002. 64. Berk DR, Bentley DD, Bayliss SJ, et al. Cutis laxa; A review. J Am Acad Dermatol 2012;66:842.e1–17. 65. Anderson CE, Finklestein JZ, Nussbaum E, et al. Association of hemolytic anemia and early-onset pulmonary emphysema in three siblings. J Pediatr 1984;105:247–51. 66. Marshall J, Heyl T, Weber HW. Post inflammatory elastolysis and cutis laxa. S Afr Med J 1966;40:1016–22. 67. Rao BK, Endzweig CH, Kagen MH, et al. Wrinkling due to mid-dermal elastolysis: two cases and literature review. J Cutan Med Surg 2000;4:40–4. 68. Morava E, Guillard M, Lefeber DJ, et al. Autosomal recessive cutis laxa syndrome revisited. Eur J Hum Genet 2009;17:1099–110.

97 Heritable Disorders of Connective Tissue

REFERENCES

1711

SECTION 15 ATROPHIES AND DISORDERS OF DERMAL CONNECTIVE TISSUES

98 

Dermal Hypertrophies Salma Machan, Ana María Molina-Ruiz and Luis Requena

Chapter Contents Hypertrophic scars and keloids . . . . . . . . . . . . . . . . . . . . . 1712 Dupuytren disease . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1716 Cutis verticis gyrata . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1717 Hyaline fibromatosis syndrome . . . . . . . . . . . . . . . . . . . . . 1718 Elastic tissue-related disorders . . . . . . . . . . . . . . . . . . . . . 1719

is constantly transmitted to the skin from the underlying cartilaginous and bony skeleton, and skin tension can be aggravated by loss of tissue, as occurs with surgical excisions5. In addition, hormonal influences have been proposed as an explanation for the appearance of keloids at or after puberty and their resolution following menopause, as well as reports of the onset or enlargement of keloids during pregnancy2. Lastly, insights should come from genetic disorders such as Goeminne syndrome and Bethlem myopathy in which spontaneous keloids are a characteristic feature6.

Pathogenesis This chapter will discuss disorders in which there are increased amounts of collagen within the skin, followed by those with increased elastin.

HYPERTROPHIC SCARS AND KELOIDS Key features ■ Conventional scars are preceded by injury, immediate in onset, flat, and asymptomatic ■ Hypertrophic scars are raised and confined to the wound margin. Sometimes they improve spontaneously and tend to have a good response to treatment ■ Keloids extend beyond the wound margin and are delayed in onset. They seldom resolve spontaneously and response to treatment is often poor

Introduction All wounds heal with some degree of scar formation, but the mechanisms that govern whether the result will be a fine thin scar, a prominent hypertrophic scar, or a tumor-like keloid remain unclear. The latter represent two forms of abnormal wound healing. Both are characterized by local fibroblast proliferation and excessive collagen production in response to cutaneous injury. However, their clinical and histopathologic features differ, as well as proposed pathogeneses.

Epidemiology There is a higher prevalence of keloids in African, African-American, Spanish and Asian populations, with an incidence ranging from 4–16%1. Although the incidence of hypertrophic scars is probably higher than that of keloids, precise data are lacking2. Neither entity has a gender prevalence; they occur most commonly in those 10 to 30 years of age3. Individuals in this age group are more frequently subjected to trauma and their rate of collagen synthesis is higher. Younger skin also possesses greater tension, as compared to older skin which has less elasticity and is more redundant2.

Etiology

1712

Proposed etiologic factors include: genetic predisposition; depth, type and location of the skin injury or wound; degree of tension; local infection or inflammation; and hormonal influences2,3. There is often a familial tendency to develop hypertrophic scars and keloids and possibly an autosomal dominant mode of inheritance with incomplete clinical penetrance and variable expression3. A range of skin injuries can lead to abnormal scarring, from lacerations, burns, surgical excisions and skin piercings to injections (vaccines, tattoo inks) and cutaneous inflammation (e.g. acne vulgaris, insect bites)4. Moreover, tension

In fetuses, cutaneous wounding during the first and second trimesters of gestation does not lead to scarring. This is thought to reflect a healing process that is occurring via tissue regenerative pathways in a sterile environment and in the absence of inflammation7. The ability to heal wounds created by injuries, in particular trauma, offers an evolutionary advantage, with associated scarring being less of an issue. However, cutaneous scarring resulting from surgical procedures is viewed as an unwanted consequence. A regenerative response would be preferred, thereby conceivably providing a superior cosmetic result and avoiding the formation of hypertrophic scars and keloids8. Conventional wound healing occurs in three phases (see Fig. 141.3): an inflammatory phase which aims to contain the injury and prevent infection; a proliferative phase in which there is formation of granulation tissue; and a remodeling (maturation) phase in which the redness of the wound lightens and its nodularity softens and flattens due to simultaneous collagen synthesis and degradation8. The latter phase can last up to one year. Greater understanding of this remodeling phase could provide targets for preventative or therapeutic interventions. Since Chapter 141 discusses the molecular basis of wound healing, this section will focus on key mediators of tissue scarring8–11. Within keloids, collagen synthesis by fibroblasts is markedly increased as is production of transforming growth factor (TGF)-β. TGF-β has been shown to play a pivotal role during the proliferative phase of wound healing. Expression of TGF-β1 or TGF-β2 leads to an increase in scarring12, whereas expression of TGF-β3 is associated with a reduction in scarring13. This has led to the introduction of therapies based upon the biologic effects of these different forms of TGF, e.g. injections of recombinant TGF-β3, injections of mannose-6-phosphate which inhibits TGF-β1 and TGF-β2 signaling (see Table 98.4). In regenerative healing, there is both a lack of scarring and an absence of inflammation. Support for this association comes from studies in which proinflammatory cytokines interleukin-6 (IL-6) and IL-8 enhanced scarring, while the anti-inflammatory cytokine IL-10 decreased the amount of scar tissue8. Several additional factors propagate a robust fibroblast response within the healing wound that can lead to increased scar formation, including platelet-derived growth factor (PDGF), two transcription factors – homeobox B13 and early growth response protein 1, and components of the Wnt signaling pathway8. Of note, fibroblasts isolated from keloids have increased expression of receptors for PDGF and TGF-β.

Clinical Features Although distinguishing a hypertrophic scar from a keloid clinically can sometimes be difficult, especially if the lesion is small or of recent onset, each has several characteristic features (Table 98.1). Both keloids and hypertrophic scars have a smooth surface and are firm to palpation. They may be pruritic or painful and occasionally inhibit normal motion of adjacent tissues. The color can vary from pink–purple (early lesions) to skin-colored to hypo- or hyperpigmented. While keloids may be more elevated above the skin surface than hypertrophic scars, the key

This chapter describes disorders in which there is an increase in the amount of collagen within the skin, followed by those with an increase in elastic fibers. The first group includes hypertrophic scars, which remain confined to the site of the original injury, and keloids, which extend in a claw-like fashion beyond the original wound margin into adjacent normal skin. Additional entities in this group include fibromatoses such as Dupuytren disease, characterized by a thickening of the palmar and digital fascia that can lead to flexion contractures of the digits, and cutis verticis gyrata, in which there is hypertrophy and folding of the skin of the scalp. The range of clinical findings in hyaline fibromatosis syndrome, a genodermatosis due to CMG2 mutations, is also reviewed. Lastly, disorders characterized by an increase in elastic tissue are discussed, including late-onset focal dermal elastosis, linear focal elastosis, elastoderma, elastofibroma dorsi, and elastoma.

hypertrophic scar, keloid, Dupuytren disease, Dupuytren contracture, cutis verticis gyrata, hyaline fibromatosis syndrome, juvenile hyaline fibromatosis, infantile systemic hyalinosis, late-onset focal dermal elastosis, linear focal elastosis, elastoderma, elastofibroma dorsi, elastoma

CHAPTER

98 Dermal Hypertrophies

ABSTRACT

non-print metadata KEYWORDS:

1712.e1

CLINICAL FEATURES OF CONVENTIONAL SCARS, HYPERTROPHIC SCARS, AND KELOIDS

Preceded by injury

Most keloids appear within one year of an injury, although the intervening interval may be up to 24 years5. Hypertrophic scars usually develop within a few weeks to months after wounding, and they frequently flatten spontaneously within 1 to 2 years. Keloids, on the other hand, do not regress over time. While both favor sites of increased wound tension such as the upper trunk, shoulder, and upper outer arm, keloids can also develop in sites such as the earlobe, where there is minimal tension. In addition, keloids can form spontaneously, most often in the midchest region.

Scar assessment

Conventional scar

Hypertrophic scar

Keloid

Yes

Yes

Not always

Onset

Immediate

Immediate

Delayed

Erythema

Temporary

Prominent

Varies

Profile

Flat

Raised

Raised

Symptomatic

No

Yes

Yes

Confined to wound margin

Yes

Yes

No

Spontaneous resolution

N/A

Possible, gradual

Rare

Treatment response

N/A

Good

Poor

Table 98.1 Clinical features of conventional scars, hypertrophic scars, and keloids. N/A, not applicable.  

CHAPTER

98 Dermal Hypertrophies

difference is that keloids extend beyond the boundary of the original wound into adjacent normal skin, often with claw-like extensions resembling the pincers of a crab (in Greek, chelè means claw) (Figs 98.1 & 98.2). In contrast, hypertrophic scars remain confined to the site of the original injury (Fig. 98.3).

Scar evaluation ranges from simple scales to use of technologically advanced devices that analyze one or more variables in a reproducible manner14. The Vancouver Scar Scale (Table 98.2) and the Patient & Observer Scar Assessment Scale (POSAS) are the two that have been most commonly employed14,15. These scales have significant interpatient variation because they score subjective features from color to degree of pain and pruritus. More recently, a Scar Cosmesis Assessment and Rating (SCAR) scale was proposed which consists of six observerscored parameters – scar spread, erythema, dyspigmentation, suture marks, hypertrophy/atrophy, and overall impression (desirable/undesirable) - in addition to two yes/no questions answered by the patient regarding itch and pain15a. Non-invasive techniques can be used to more objectively measure scar color, blood flow, transcutaneous oxygen tension, skin hardness, elasticity, and hydration16. In addition, skin imaging techniques such as dedicated scar photography, dermoscopy, high-frequency ultrasound, laser Doppler perfusion imaging, confocal microscopy, and magnetic resonance imaging can be employed to evaluate scars17.

&

$

%

'

Fig. 98.1 Keloids. Common sites include the upper trunk (A–C) and neck (D). There is a higher prevalence of keloids in patients with darkly pigmented skin, but they can occur in individuals with any skin phototype. Note the extension of the keloids into the normal surrounding skin in a claw-like manner. C, Courtesy, Lorenzo  

Cerrroni, MD.

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15

Fig. 98.2 Comparison of a keloid and a hypertrophic scar. A The keloid has claw-like extensions that extend beyond the original wound margin into adjacent normal skin.   B The hypertrophic scar remains confined to the site of the original surgical wound. A, Courtesy,  

Edward Cowen, MD; B, Courtesy, Jean L Bolognia, MD.

$

Fig. 98.3 Hypertrophic scar at the site of a knife injury.  

%

VANCOUVER SCAR SCALE

Score for each clinical feature

0

1

2

3

4

5

Pliability

Normal

Supple

Yielding

Firm, solid unit

Banding/“ropes”

Contracture

Height

Flat

5 mm





Vascularity

Normal

Pink

Red

Purple





Pigmentation

Normal

Hypopigmentation

Hyperpigmentation







Table 98.2 Vancouver scar scale. Adapted from Sullivan T, Smith J, Kermode J, et al. Rating the burn scar. J Burn Care Rehabil. 1990;11:256–60.  

Pathology

1714

Distinguishing between a keloid and a hypertrophic scar is important when contemplating treatment, especially more aggressive therapies such as radiation. In some patients, histologic examination is required to make this distinction (Table 98.3). In hypertrophic scars, there is an increase in both the number of fibroblasts and the density of collagen fibers within the dermis, both of which are oriented parallel to the skin surface (Fig. 98.4). Keloids are characterized by the presence of whorls and nodules of strikingly thick, glassy, homogeneous collagen bundles that are composed of densely packed fibrils and oriented haphazardly throughout the dermis (keloidal collagen) (Fig. 98.5). Early on, there are abundant deposits of fibrillary collagen within the reticular dermis of keloids, while mature lesions often have the characteristic thick sclerotic collagen. In longstanding keloids, there may be a return to the earlier fibrillary pattern. It is noteworthy that keloidal collagen may be absent in up to 45% of keloids18. In scars with no detectable keloidal collagen, histologic features that favor a keloid include: no flattening of the epidermis; a lack of fibrosis within the papillary dermis; a tongue-like advancing edge as the scar tissue extends through the reticular dermis; a horizontal cellular fibrous band within the upper reticular dermis with a sharp demarcation from the normal-appearing papillary and reticular dermis; and prominent fascia-like fibrous bands in the deeper portion of the scar18. Attempts to differentiate hypertrophic scars from keloids via immuno­ histochemistry has led to conflicting results18–20. In one study, nodules of α-smooth muscle actin (α-SMA)-positive cells (myofibroblasts) were only observed in hypertrophic scars19, whereas another investigation found α-SMA expression in both hypertrophic scars (70%) and keloids (45%)18. Expression of cyclooxygenase (COX)-1 was observed in 100% of keloids, but it was also expressed in ~50% of hypertrophic scars20; thus COX-1 expression favored, but did not specifically identify, keloids.

HISTOPATHOLOGIC FEATURES OF HYPERTROPHIC SCARS AND KELOIDS

Hypertrophic scar

Keloid

Epidermis

Flattened

Not involved

Papillary dermis

Fibrotic

Not involved

Fibroblasts

Increased

Not increased

Collagen bundles

Fine, wavy; orientation is parallel to the epidermis

Large, thick, closely packed; orientation is random relative to the epidermis

Elastic fibers

Diminished or absent

Increased within the deep dermis

Dermal mucin

Not increased

Increased

Dermal blood vessels

Increased; oriented vertically, perpendicular to the epidermis

Not increased; few, if any, vertically oriented vessels

Inflammatory infiltrate

Sparse, perivascular

Sparse, perivascular

Mast cells

Increased

Increased

Adnexal structures within the reticular dermis

Absent

Absent

Myofibroblasts

+++

++

COX-1 expression

+

+++

Table 98.3 Histopathologic features of hypertrophic scars and keloids. Shading indicates differences.  

CHAPTER

Dermal Hypertrophies

98

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Fig. 98.5 Keloid – histopathologic features. A Nodules of thick collagen bundles are oriented haphazardly within the dermis (keloidal collagen). There is neither flattening of the epidermis nor involvement of the papillary dermis, and a sharp demarcation is seen between the normal-appearing papillary and reticular dermis and the nodules. B Strikingly thick, glassy, homogeneous collagen bundles composed of multiple, densely packed fibrils.  

%

Fig. 98.4 Hypertrophic scar – histopathologic features. A Increased density of collagen fibers within the dermis and vertically oriented blood vessels. B Increase in the number of fibroblasts and density of collagen fibers, both of which are oriented horizontally (parallel to the epidermis). The central blood vessel is oriented vertically and there is a sparse perivascular inflammatory infiltrate.  

Differential Diagnosis For keloids, the clinical differential diagnosis includes the sclerotic form of xanthoma disseminatum, lobomycosis (keloidal blastomycosis; lacaziosis), and the keloidal forms of scleroderma and morphea. Rarely, carcinoma en cuirasse can present as keloidal nodules. Patients with the vascular type of Ehlers–Danlos syndrome may occasionally develop keloidal plaques on their lower extremities, and spontaneous formation of keloids can be a clinical clue to other rare inherited syndromes such as Bethlem myopathy, Rubenstein–Taybi syndrome, and Goeminne syndrome (see below). Histopathologically, keloids and hypertrophic scars need to be differentiated from spindle cell tumors, primarily dermatofibroma (DF), dermatofibrosarcoma protuberans (DFSP), desmoplastic melanoma, and the scar-like variant of squamous cell carcinoma (SCC). Immunostaining for CD34 and factor XIIIa, which is usually positive in DFSP and DF, respectively, is negative in keloids and hypertrophic scars21. While there is minimal or no immunostaining for S100 protein in scars, desmoplastic melanomas usually demonstrate strong expression of this marker22. Finally, the unusual scar-like variant of SCC may only have focal keratin expression, and a complete panel of keratin stains (to increase sensitivity) may be required for its detection23.

Treatment The management of keloids and hypertrophic scars continues to challenge clinicians, and there is no universally accepted treatment al­ gorithm. Potential evidence-based treatments are outlined in Table 98.424. Prevention remains the best strategy in predisposed patients, including avoidance of nonessential surgery in high-risk anatomic sites and attention to postsurgical wound care24. There is limited evidence to support over-the-counter scar reduction products such as silicone sheeting and topical creams containing vitamin E24. While potent topical corticosteroids are sometimes used to address pruritus, intralesional triamcinolone is the major first-line therapy for flattening hypertrophic scars and keloids25. Its utility was confirmed in a recent meta-analysis25a. An alternative, especially for needle-averse individuals, is clobetasol propionate 0.05% cream under silicone dressing occlusion25b. Intralesional or topical corticosteroids may be combined with intralesional 5-fluorouracil25c. Surgical revision of both hypertrophic scars and keloids must be undertaken with caution given the high recurrence rates. Cryosurgery has been used successfully24 and is often combined with intralesional triamcinolone. Pulsed dye laser therapy has become popular as a modality for postsurgical scar reduction and is associated with few side effects26. Due to theoretical concerns regarding carcinogenesis, radiotherapy is reserved primarily for treatment-resistant keloids. However, current postoperative protocols limit total exposure and vary from

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15

TREATMENT OPTIONS FOR HYPERTROPHIC SCARS AND KELOIDS

Treatment

Mechanism(s) of action

Level of evidence

Silicone sheeting

Reduction in collagen deposition due to an increase in temperature, hydration (reduces water vapor loss), and perhaps oxygen tension

2

Pressure therapy

Pressure-induced hypoxic effects lead to collagen and fibroblast degeneration

2

Onion extract (topical)

Decrease in inflammation and fibroblast proliferation rate

1

Vitamin E (topical)

Antioxidant properties

2

Triamcinolone (intralesional; 10–40 mg/ml)*

Inhibits fibroblast proliferation and collagen synthesis; vasoconstriction; decreases in TGF-β1 and TGF-β2

1

5-Fluorouracil (intralesional; 50 mg/ml not to exceed 100 mg/session; administered weekly)

Inhibits fibroblast proliferation

2

Bleomycin (1.5 IU/ml – multiple puncture technique; maximum 2 ml/cm2 and 10 IU per session; once monthly)

Direct or indirect, TGF-β-mediated, inhibitory effects on collagen

2

Surgical scar revision

Reorientation and construction of multiple tension vectors

2

Cryosurgery (needles more effective than contact or spray; monthly × 3–10 months)*

Direct cellular freezing effects; post-thaw vascular stasis

2

Radiation therapy (postoperative [within 72 hours]; 10 Gy in a single dose; 6–15 Gy in 3–5 fractions)

Induction of fibroblast apoptosis; restoration of balance between synthesis and degradation of collagen within scar; damage to connective tissue stem cells

2

Laser therapy (pulsed dye laser [PDL] – can begin day of suture removal then every 3–4 weeks; CO2 fractional laser*)

Induces wound contraction and collagen remodeling following thermal necrosis; decreased levels of TGF-β from heat shock response

1 (PDL)

Avotermin (intralesional)**

Recombinant TGF-β3 (form of TGF associated with a reduction in scarring)

1 (phase II trial; no difference in phase III trial)

Human recombinant interleukin-10 (intralesional)**

Anti-inflammatory activity

1^ ^^

Mannose-6-phosphate (intralesional)**

Inhibition of TGF-β1 and TGF-β2 signaling (two forms of TGF associated with an increase in scarring)

1^

Insulin (intralesional)

Inhibitor of myofibroblasts

1

,

*Cryotherapy or CO2 laser sometimes administered prior to intralesional injections of corticosteroids. Not commercially available. ** ^ Based upon phase II trial.

^^In lightly, but not darkly, pigmented individuals.

Table 98.4 Treatment options for hypertrophic scars and keloids. There are also reports of the use of topical retinoic acid, calcineurin inhibitors, imiquimod (deemed ineffective in controlled trials), and tamoxifen; botulinum toxin A; mitomycin C (topical or intralesional); and systemic methotrexate and calcium channel blockers50. Treatments reserved for the treatment of keloids are shaded mid-blue and experimental treatments are shaded dark blue. Key to evidence-based support: (1) prospective controlled trial; (2) retrospective study or large case series; (3) small case series or individual case reports. TGF, transforming growth factor.  

Adapted from Tziotzios et al. J Am Acad Dermatol. 2012;66:13–24.

12–16 Gy in 3–4 fractions to 20 Gy in 5 fractions, beginning within 24–48 hours following surgery (see Ch. 139). Potential therapies based upon insights into pathogenesis (see above) include recombinant TGF-β3 (avotermin), human recombinant IL-10, and mannose-6-phosphate which is a potent inhibitor of TGF-β1 and TGF-β2 signaling24,27.

History

DUPUYTREN DISEASE

Dupuytren disease is common in Caucasians of northern European ancestry, with a prevalence in Western countries that ranges from 1–30%; it is rare in patients with dark skin phototypes. The incidence of Dupuytren disease increases with age and it is most common in middle-aged and older men29. Familial associations suggest an autosomal dominant inheritance, but sporadic cases are common. The lesion is associated with other fibromatoses (e.g. plantar fibromatosis; see Ch. 116) as well as diabetes mellitus, alcoholism, and perhaps cigarette smoking30. Recently, use of vemurafenib was associated with a new onset or worsening of Dupuytren disease and plantar fascial fibromatosis.

Synonyms:  ■ Dupuytren’s contracture ■ Palmar fibromatosis Dupuytren’s diathesis



Key features

1716

■ ■ ■ ■

Thickening of palmar and digital fascia Progressive flexion contracture of affected digits Myofibroblast proliferation followed by excess collagen synthesis Treatment includes injections of collagenase and surgical fasciotomy/fasciectomy

Henry Cline described thickening of the palmar fascia in 1777 and proposed palmar fasciotomy as a cure. In 1831, Guillaume Dupuytren characterized and popularized this entity28.

Epidemiology

Pathogenesis Fibrogenic cytokines (e.g. TGF-β1, TGF-β2) are thought to play a role due to their ability to induce collagen production, proliferation of fibroblasts, and the differentiation of fibroblasts into myofibroblasts. Of nine

Clinical Features Patients often present late in the course of their disease with flexion contractures of the affected digits. Lesions usually have an ulnar distribution, and the ring finger is most commonly affected (Fig. 98.6). The disorder begins with a nodule in the fascia of the palm, which grows to produce a cord which then contracts, producing a flexion contracture of the metacarpophalangeal and proximal interphalangeal joints. Complications of Dupuytren disease include nerve injury, loss of joint mobility, and the development of reflex sympathetic dystrophy33.

Pathology Histologically, the nodular lesion consists of a proliferation of myofibroblasts, which align along lines of tension. The initial stages are more cellular and there are some mitotic figures; the cells may express αSMA, indicative of myofibroblastic differentiation. Thicker collagen, fewer myofibroblasts, and scarce to absent mitotic figures characterize later stages34.

Differential Diagnosis Although usually the diagnosis is straightforward, one must consider a ganglion cyst, giant cell tumor of the tendon sheath, soft tissue sarcoma (e.g. epithelioid sarcoma), callus, and tenosynovitis. A rare case of a lung cancer metastasis simulating Dupuytren disease has been reported35, and in injection drug users, flexion digital contractures (camptodactyly) due to repeated vascular injury and infection of the digits can be seen.

Treatment Fasciectomy/fasciotomy to release the joint contracture is the most common therapeutic intervention, but recurrence is possible. Injectable collagenase (from Clostridium histolyticum) is an alternative to surgery36. Up to three monthly injections are performed per cord, followed by a finger-extension procedure the following day. Reduction in the contracture (to 0–5°) was observed in 45–65% of collagenasetreated cords, compared to ~5% of placebo-treated cords. Possible

complications include tendon, ligament or nerve injury, cold intolerance, urticaria, and angioedema. At two years post-injection, a 20% recurrence rate was noted37. Some authors have advocated the use of radiotherapy during the early stage of Dupuytren disease37a. Based upon insights into pathogenesis, future treatments may include inhibitors of TGF-β1, TGF-β2 or TNF38.

CUTIS VERTICIS GYRATA

CHAPTER

98 Dermal Hypertrophies

susceptibility loci identified in a genome-wide association study, 6 of 9 harbored genes that encode proteins in the Wnt signaling pathway31. In more recent genome-wide assays of fibroblasts from Dupuytren disease, the differential expression patterns included genes that encode proteins involved in the extracellular matrix (e.g, collagen), fibrosis (e.g. follistatin), tissue remodeling (e.g. collagenases, matrix metalloproteinases), cellular movement (e.g. kinesins), and signaling pathways (e.g. STAT1, Wnt2), as well as growth factors (e.g. fibroblast growth factor 9)32.

Key features ■ Hypertrophy and folding of the scalp ■ Primary (idiopathic) form occurs almost exclusively in males, with an onset at puberty and without facial involvement ■ Underlying disorders in the secondary form include endocrinopathies (e.g. acromegaly, myxedema) and genetic disorders (e.g. Turner syndrome)

Clinical Features Primary cutis verticis gyrata (CVG) consists of overgrowth of the scalp that progresses to produce symmetric gyrate or cerebriform folding of the skin (Fig. 98.7). The folds are usually aligned in an anterior– posterior direction on the crown and vertex and are soft to spongy on palpation. Typically, terminal hair density is reduced on the folds, but not in the furrows. Primary CVG can be subdivided into: (1) isolated CVG; and (2) CVG associated with neurologic and/or ophthalmologic abnormalities. Both subtypes have a male predominance and usually develop around puberty. Secondary CVG is less common and its onset varies from birth to adulthood. In secondary CVG, there is a more equal gender distribution and it may be asymmetric, depending on the underlying etiology (Table 98.5).

Pathology Biopsy specimens typically show normal skin or diffuse dermal thickening with packed hyalinized collagen and an increased number of fibroblasts. Prominent adnexal structures may be present39.

Differential Diagnosis A cerebriform congenital melanocytic nevus of the scalp may simulate CVG. One must also differentiate the latter from pachydermoperiostosis (primary hypertrophic osteoarthropathy), which is associated with facial involvement, thickening of the skin on the hands and

Fig. 98.7 Cutis verticis gyrata. Cerebriform folding of the skin of the scalp.  

Fig. 98.6 Dupuytren disease. Fibrotic nodule at the base of the fourth finger with an obvious cord extending proximally. In addition to palpation, fibrotic cords can be accentuated by extension of the digit. Eventually, flexion contractures develop.  

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CUTIS VERTICIS GYRATA – DISEASE ASSOCIATIONS

Primary isolated None



Primary with associated anomalies Neurologic (e.g. intellectual disability, seizures) Ophthalmologic (e.g. cataracts, optic atrophy)



CLINICAL FEATURES OF HYALINE FIBROMATOSIS SYNDROME

Good prognosis (classic juvenile hyaline fibromatosis)

Poor prognosis (classic infantile systemic hyalinosis)

Onset during childhood (60

20

eTable 98.1 Differences in adult versus fetal wound healing.  

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Atrophies and Disorders of Dermal Connective Tissues

15

DISORDERS CHARACTERIZED BY INCREASED ELASTIC TISSUE FIBERS

Disorder

Clinical features

Histopathologic features

Comments

Late-onset focal dermal elastosis

Multiple 1–3 mm yellow papules that may coalesce Favors the neck, axillae, groin, antecubital and popliteal fossae

Increased normal-appearing elastic fibers in the mid and deep reticular dermis

Lacks the systemic features of PXE (see Ch. 97)

Linear focal elastosis (elastotic striae)

Multiple yellow, palpable, striae-like bands of the lumbosacral region

Focal increase in number of elongated or fragmented elastic fibers (thickened > thinned) within the mid dermis; the ends of the elastic fibers may be split with a “paintbrush” appearance Early lesions may have inflammation and elastolysis

May represent an excessive regenerative process of elastic fibers, perhaps to repair striae distensae (see Ch. 99)

Elastoderma

Localized areas of lax, pendulous skin; neck, trunk, arm

Increased normal- and abnormalappearing elastic fibers throughout the dermis and subcutis

Lacks the systemic features of PXE (see Ch. 97)

Elastofibroma dorsi

Large mass in the deep subcutaneous tissue of the infrascapular area

Arises within the fascia Increased elastic fibers with a globular and beaded morphology admixed with plump collagen bundles, fibroblasts, and mature fat cells (Fig. 98.11)

Favors older women > men and Japanese Possibly related to chronic mechanical stress

Elastoma (nevus elasticus)

Firm, skin-colored to yellowish papule(s) which may be clustered Favors the trunk

Accumulation of thick, tortuous, branching elastic fibers within the reticular dermis

Type of connective tissue nevus (see Ch. 116) Associated with Buschke–Ollendorf syndrome

Elastosis perforans serpiginosa

Annular and polycyclic plaques composed of keratotic papules Favors the neck, face, antecubital fossae and other flexural areas

Transepidermal or perifollicular channels that contain fragments of elastotic material Increased number of coarse elastic fibers in the superficial dermis No secondary calcium deposition on elastic fibers

Associated with penicillamine (lumpy-bumpy fibers*), Down syndrome and connective tissue disorders (e.g. Ehlers–Danlos syndrome, Marfan syndrome; see Ch. 96)

Pseudoxanthoma elasticum (PXE)

Yellowish skin papules and “cobblestoned” plaques; redundant folds Favors flexural sites, especially the neck and axillae, and periumbilical region

Distorted and fragmented elastic fibers in mid and deep reticular dermis Calcium deposition on altered elastic fibers

Angioid streaks, GI hemorrhage, atherosclerotic cardiovascular disease (see Ch. 97)

Idiopathic or inherited

Related to cumulative actinic damage Actinic or solar elastosis (including cutis rhomboidalis nuchae, solar elastotic bands, elastotic nodules of the ear)

Yellow to yellow-white, thickened, coarsely wrinkled skin that favors the lateral forehead, malar region, posterolateral neck, mid extensor arms Bands – forearms Nodules – antihelix > helix

Bluish-grey elastotic material composed of degenerated elastic fibers within the upper and mid dermis In more advanced phases, the elastotic material may aggregate into dense amorphous masses (“actinic elastoma”)

Photodamage may be accelerated by medications, e.g. voriconazole (see Ch. 87)

Favré-Racouchot syndrome (nodular elastosis with cysts and comedones)

Bilateral, clustered, open > closed comedones within thickened skin Favors malar prominence and lateral periorbital region

Severe solar elastosis with follicular distention and cystic structures filled with compact keratin

See Ch. 87

Acrokeratoelastoidosis

Bands of waxy or translucent papules and plaques Favors ulnar side of thumb and radial side of forefinger

Shallow depression of the epidermis Usually a decrease in thin and partially fragmented elastic fibers in the mid and deep reticular dermis In some cases, elastic fibers are increased, coarse, and aggregated

Also an inherited form that can involve non-sun-exposed sites of the hands and/or feet (see Ch. 58)

Elastoma of Dubreuilh

Yellow to yellow-brown papules or plaques Favor forehead, cheeks, lateral neck

Amorphous masses composed of aggregated elastotic material in the upper dermis

See Ch. 87

*By electron microscopy. Table 98.7 Disorders characterized by increased elastic tissue fibers. Special stains for elastic fibers include Verhoeff–van Gieson and orcein (acid orcein–Giemsa; see Ch. 0). GI, gastrointestinal.  

1720

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98

A

B

Fig. 98.11 Elastofibroma dorsi – histopathologic features. A Irregular, partially fragmented elastic fibers admixed with swollen collagen bundles. B An elastic tissue stain accentuates the fragmented fibers.  

REFERENCES 1. Robles DT, Berg D. Abnormal wound healing: keloids. Clin Dermatol 2007;25:26–32. 2. English RS, Shenefelt PD. Keloid and hypertrophic scars. Dermatol Surg 1999;25:631–8. 3. Niessen FB, Spauwen PH, Schalkwijk J, Kon M. On the nature of hypertrophic scars and keloids: a review. Plast Reconstr Surg 1999;104:1435–58. 4. Alster TS, Tanzi EL. Hypertrophic scars and keloids: etiology and management. Am J Clin Dermatol 2003;4:235–43. 5. Nemeth AJ. Keloids and hypertrophic scars. J Dermatol Surg Oncol 1993;19:738–46. 6. Collins J, Foley AR, Straub V, Bönnemann CG. Spontaneous keloid formation in patients with Bethlem myopathy. Neurology 2012;79:2158. 7. Shaw AM. Recent advances in embryonic wound healing. In: Garg HG, Longaker MT, editors. Scarless Wound Healing. New York: Marcel Dekker; 2000. p. 227–37. 8. Profyris C, Tziotzios C, Do Vale I. Cutaneous scarring: Pathophysiology, molecular mechanisms, and scar reduction therapeutics Part I. The molecular basis of scar formation. J Am Acad Dermatol 2012;66:1–10. 9. Cole J, Tsou R, Wallace K, et al. Early gene expression profile of human skin to injury using high-density cDNA microarrays. Wound Repair Regen 2001;9:  360–70. 10. Schafer M, Werner S. Transcriptional control of wound repair. Annu Rev Cell Dev Biol 2007;23:69–92. 11. Werner S, Grose R. Regulation of wound healing by growth factors and cytokines. Physiol Rev 2003;83:835–70. 12. Shah M, Foreman DM, Ferguson MW. Neutralising antibody to TGF-beta 1,2 reduces cutaneous scarring in adult rodents. J Cell Sci 1994;107:1137–57. 13. Shah M, Foreman DM, Ferguson MW. Neutralisation of TGF-beta 1 and TGF-beta 2 or exogenous addition of TGF-beta 3 to cutaneous rat wounds reduces scarring. J Cell Sci 1995;108:985–1002. 14. Brusselaers N, Pirayesh A, Hoeksema H, et al. Burn scar assessment: a systematic review of different scar scales. J Surg Res 2010;164:e115–23. 15. Van de Kar A, Corion L, Smeulders M, et al. Reliable and feasible evaluation of linear scars by the Patient and Observer Scar Assessment Scale. Plast Reconstr Surg 2005;116:514–22.

15a.  Kantor J. The SCAR (Scar Cosmesis Assessment and Rating) scale: development and validation of a new outcome measure for postoperative scar assessment. Br J Dermatol 2016;175:1394–6. 16. Nguyen DQ, Potokar T, Price P. A review of current objective and subjective scar assessment tools. J Wound Care 2008;17:101–2, 104–6. 17. Oliveira GV, Chinkes D, Mitchell C, et al. Objective assessment of burn scar vascularity, erythema, pliability, thickness and planimetry. Dermatol Surg 2005;31:48–58. 18. Lee JY, Yang CC, Chao SC, Wong TW. Histopathological differential diagnosis of keloid and hypertrophic scar. Am J Dermatopathol 2004;26:379–84. 19. Ehrlich HP, Desmouliere A, Diegelmann RF, et al. Morphological and immunochemical differences between keloid and hypertrophic scar. Am J Pathol 1994;145:105–13. 20. Abdou AG, Maraee AH, Saif HF. Immunohistochemical evaluation of COX-1 and COX-2 expression in keloid and hypertrophic scar. Am J Dermatopathol 2014;36:311–17. 21. Kuo T, Hu S, Chan H. Keloidal dermatofibroma: report of 10 cases of a new variant. Am J Surg Pathol 1998;22:564–8. 22. Kaneishi NK, Cockerell CL. Histologic differentiation of desmoplastic melanoma from cicatrices. Am J Dermatopathol 1998;20:128–34. 23. Velázquez EF, Werchniack AE, Granter SR. Desmoplastic/ spindle cell squamous cell carcinoma of the skin. A diagnostically challenging tumor mimicking a scar: clinicopathologic and immunohistochemical study of 6 cases. Am J Dermatopathol 2010;32:333–9. 24. Tziotzios C, Profyris C, Sterling J. Cutaneous scarring: Pathophysiology, molecular mechanisms, and scar reduction therapeutics Part II. Strategies to reduce scar formation after dermatologic procedures. J Am Acad Dermatol 2012;66:13–24. 25. Chowdri NA, Masarat M, Mattoo A, Darzi MA. Keloids and hypertrophic scars: results with intraoperative and serial postoperative corticosteroid injection therapy. Aust N Z J Surg 1999;69:655–9. 25a.  Wong TS, Li JZ, Chen S, et al. The efficacy of triamcinolone acetonide in keloid treatment: A systematic review and meta-analysis. Front Med (Lausanne) 2016;3:71.

25b.  Nor NM, Ismail R, Jamil A, et al. A randomized, single-blind trial of clobetasol propionate 0.05% cream under silicone dressing occlusion versus intra-lesional triamcinolone for treatment of keloid. Clin Drug Investig 2017;37:295–301. 25c.  Shah VV, Aldahan AS, Mlacker S, et al. 5-Fluorouracil in the treatment of keloids and hypertrophic scars: A comprehensive review of the literature. Dermatol Ther (Heidelb) 2016;6:169–83. 26. Leventhal D, Furr M, Reiter D. Treatment of keloids and hypertrophic scars: a meta-analysis and review of the literature. Arch Facial Plast Surg 2006;8:362–8. 27. Ferguson MWJ, Duncan J, Bond J, et al. Prophylactic administration of avotermin for improvement of skin scarring: three double-blind, placebo-controlled, phase I/II studies. Lancet 2009;373:1264–74. 28. Holzer LA, de Parades V, Holzer G. Guillaume Dupuytren: his life and surgical contributions. J Hand Surg Am 2013;38:1994–8. 29. Lanting R, Broekstra DC, Werker PM, van den Heuvel ER. A systematic review and meta-analysis on the prevalence of Dupuytren disease in the general population of Western countries. Plast Reconstr Surg 2014;133:593–603. 30. Picardo NE, Khan WS. Advances in the understanding of the aetiology of Dupuytren’s disease. Surgeon 2012;10:151–8. 31. Dolmans GH, Werker PM, Hennies HC, et al. Wnt signaling and Dupuytren’s disease. N Engl J Med 2011;365:307–17. 32. Forrester HB, Temple-Smith P, Ham S, et al. Genomewide analysis using exon arrays demonstrates an important role for expression of extra-cellular matrix, fibrotic control and tissue remodelling genes in Dupuytren’s disease. PLoS ONE 2013;8:e59056. 33. Weinzweig N, Culver JE, Fleegler EJ. Severe contractures of the proximal interphalangeal joint in Dupuytren’s disease: combined fasciectomy with capsuloligamentous release versus fasciectomy alone. Plast Reconstr Surg 1996;97:560–6. 34. Requena L, Kutzner H. Fibromatosis. In: Requena L, Kutzner H, editors. Cutaneous Soft Tissue Tumors. Philadelphia: Wolters Kluwer Health; 2015. 35. Ragois P, Didailler P, Rizzi P. Métastase cutanée d’un cancer pulmonaire simulant une maladie de Dupuytren. Chir Main 2012;31:259–61.

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36. Hurst LC, Badalamente MA, Hentz VR, et al. CORD I Study Group. Injectable collagenase clostridium histolyticum for Dupuytren’s contracture. N Engl J Med 2009;361:968–79. 37. Eaton C. Evidence-based medicine: Dupuytren contracture. Plast Reconstr Surg 2014;133:1241–51. 37a.  Eberlein B, Biedermann T. To remember: Radiotherapy - a successful treatment for early Dupuytren’s disease. J Eur Acad Dermatol Venereol 2016;30:1694–9. 38. Verjee LS, Verhoekx JS, Chan JK, et al. Unraveling the signalling pathways promoting fibrosis in Dupuytren’s disease reveals TNF as a therapeutic target. Proc Natl Acad Sci USA 2013;110:E928–37. 39. Hsu YJ, Chang YJ, Su LH, Hsu YL. Using novel subcision technique for the treatment of primary essential cutis verticis gyrata. Int J Dermatol 2009;48:307–9. 40. Sasaki T, Niizeki H, Shimizu A, et al. Identification of mutations in the prostaglandin transporter gene SLCO2A1 and its phenotype-genotype correlation in Japanese patients with pachydermoperiostosis. J Dermatol Sci 2012;68:36–44. 41. Przylepa KA, Paznekas W, Zhang M, et al. Fibroblast growth factor receptor 2 mutations in Beare-Stevenson cutis gyrata syndrome. Nat Genet 1996;13:  492–4.

42. Fryns JP, Gevers D. Goeminne syndrome (OMIM 314300): another male patient 30 years later. Genet Couns 2003;14:109–11. 43. Saha D, Kini UA, Kini H. Cutaneous neurocristic hamartoma presenting as cutis verticis gyrata. Am J Dermatopathol 2014;36:e66–9. 44. Kim JE, Choi KH, Kang SJ, et al. Angiosarcoma mimicking cutis verticis gyrata. Clin Exp Dermatol 2011;36:806–8. 45. El-Kamah GY, Fong K, El–Ruby M, et al. Spectrum of mutations in the ANTXR2 (CMG2) gene in infantile systemic hyalinosis and juvenile hyaline fibrosis. Br J Dermatol 2010;163:213–15. 45a.  Bürgi J, Kunz B, Abrami L, et al. CMG2/ANTXR2 regulates extracellular collagen VI which accumulates in hyaline fibromatosis syndrome. Nat Commun 2017;8:15861. 46. Hanks S, Adams S, Douglas J, et al. Mutations in the gene encoding capillary morphogenesis protein 2 cause juvenile hyaline fibromatosis and infantile systemic hyalinosis. Am J Hum Genet 2003;73:  791–800. 47. Ruiz-Maldonado R, Durán-McKinster C, Sáez-de-Ocariz M, et al. Interferon alpha-2B in juvenile hyaline fibromatosis. Clin Exp Dermatol 2006;31:478–9.

48. Deuquet J, Lausch E, Guex N, et al. Hyaline fibromatosis syndrome inducing mutations in the ectodomain of anthrax toxin receptor 2 can be rescued by proteasome inhibitors. EMBO Mol Med 2011;3:208–21. 49. Lewis KG, Bercovitch L, Dill SW, Robinson-Bostom L. Acquired disorders of elastic tissue: part I. Increased elastic tissue and solar elastotic syndromes. J Am Acad Dermatol 2004;51:1–21. 50. Viera MH, Amini S, Valins W, Berman B. Innovative therapies in the treatment of keloids and hypertrophic scars. J Clin Aesthet Dermatol 2010;3:20–6. 51. Khanijow K, Unemori P, Leslie KS, et al. Cutis verticis gyrata in men affected by HIV-related lipodystrophy. Dermatol Res Pract 2013;2013:941740. 52. Lang N, Sterzing F, Enk AH, Hassel JC. Cutis verticis gyrata-like skin toxicity during treatment of melanoma patients with the BRAF inhibitor vemurafenib after whole-brain radiotherapy is a consequence of the development of multiple follicular cysts and milia. Strahlenther Onkol 2014;190:1080–1. 53. Harding JJ, Barker CA, Carvajal RD, et al. Cutis   verticis gyrata in association with vemurafenib and whole-brain radiotherapy. J Clin Oncol 2014;32:  e54–6.

ATROPHIES AND DISORDERS OF DERMAL CONNECTIVE TISSUES SECTION 15

Atrophies of Connective Tissue Catherine Maari and Julie Powell

99 

Mid-dermal elastolysis . . . . . . . . . . . . . . . . . . . . . . . . . . . 1723

also be playing a role, in addition to CD34+ dendritic fibroblasts6. Recently, a decrease in lysyl oxidase-like 2 (LOXL2) expression, potentially affecting elastin renewal, was observed in this condition7.

Anetoderma . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1724

Clinical features

Striae . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1727

In mid-dermal elastolysis, patients can have well-circumscribed to large diffuse areas of fine wrinkling (Fig. 99.1), usually in a symmetric distribution (type I). The wrinkles themselves tend to follow cleavage lines. Discrete perifollicular papules are seen in some patients (type II), with the site of the central hair follicle being indented. Occasionally, erythematous patches, telangiectasias, and reticulated erythema may be present (type III)3. Although in the majority of patients there is no history of a prior inflammatory dermatosis, some patients do report previous mild to moderate erythema and, rarely, the elastolysis is preceded by urticarial lesions or granuloma annulare. Sites of predilection are the trunk, lateral neck, and upper extremities. Once the patches of wrinkling have appeared, they usually remain stationary. They are asymptomatic and give the skin a prematurely aged appearance. The affected areas usually have normal pigmentation and no associated scaling, induration, or herniation. There is neither associated systemic involvement nor a family history of similar lesions. While diagnosis is usually confirmed via histologic examination of involved skin, non-invasive imaging techniques such as optical coherence microscopy or high-frequency ultrasound may also prove helpful8.

Chapter Contents

Atrophoderma of Pasini and Pierini . . . . . . . . . . . . . . . . . . 1728 Follicular atrophoderma . . . . . . . . . . . . . . . . . . . . . . . . . . 1730 Atrophia maculosa varioliformis cutis . . . . . . . . . . . . . . . . . 1731 Piezogenic pedal papules (piezogenic papules) . . . . . . . . . . 1731

Atrophies of the skin that are due to a diminution or loss of collagen and/or elastic fibers are discussed in this chapter. The areas of involvement can be quite large, as in mid-dermal elastolysis, or punctate, as in follicular atrophoderma. In most disorders, the underlying pathogenesis remains to be discovered.

MID-DERMAL ELASTOLYSIS Key features ■ Uncommon disorder with areas of fine wrinkling ■ Usually affects Caucasian middle-aged women ■ Selective loss of elastic tissue in the mid dermis

Introduction Mid-dermal elastolysis is a rare acquired disorder of elastic tissue. Clinically, it is usually characterized by diffuse fine wrinkling, most often located on the trunk, neck, and arms. Histologically, a clear band of elastolysis is present in the mid dermis.

History In 1977, Shelley and Wood reported the first case of “wrinkles due to idiopathic loss of mid-dermal elastic tissue”. Their patient, a 42-yearold woman, had circumscribed areas of fine wrinkles that gave her an inappropriately aged appearance1.

Epidemiology To date, ~100 cases have been reported in the literature. The vast majority of patients are Caucasian women between the ages of 30 and 50 years2,3.

Pathogenesis The cause of the acquired elastic tissue degeneration in mid-dermal elastolysis is still unclear. Exposure to UV light is thought to be a major contributing factor in the degeneration of elastic fibers4 (as in annular elastolytic giant cell granuloma). There are reports of mid-dermal elastolysis developing after significant UV exposure, including natural sunlight, UVA (tanning salon), and narrowband UVB phototherapy5. Other possible mechanisms include defects in the synthesis of elastic fibers, autoimmunity against elastic fibers, and damage to elastic fibers via the release of elastase by inflammatory cells or fibroblasts. Of note, it has been observed in the setting of immune reconstitution inflammatory syndrome (IRIS). An imbalance between matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs) may

Pathology The epidermis is normal in appearance and, occasionally, a mild perivascular infiltrate is noted in the dermis. Elastic tissue stains, such as Verhoeff–van Gieson or Weigert’s stain, reveal a selective loss of elastic fibers in the mid dermis (Fig. 99.2). There is preservation of normal elastic tissue in the superficial papillary dermis above, in the reticular dermis below, and along adjacent hair follicles. The preservation of elastic tissue around the hair follicles explains the perifollicular papules observed in some patients. By electron microscopy, phagocytosis of normal as well as degenerated elastic fiber tissue by macrophages has been described7. Elastophagocytosis by macrophages is also occasionally observed by routine histology.

Differential diagnosis Mid-dermal elastolysis must be differentiated from the other disorders of elastic tissue such as anetoderma, pseudoxanthoma elasticum (PXE), PXE-like papillary dermal elastolysis, elastoderma and cutis laxa, especially the acquired form (Table 99.1). Clinically, anetoderma is characterized by soft macules and papules that herniate upon palpation, as opposed to diffuse wrinkling. Histologically, elastolysis can occur in the papillary and/or mid-reticular dermis in anetoderma (see below). Patients with generalized cutis laxa have loose, redundant skin, hanging in folds, and histologic examination shows elastolysis that frequently involves the entire dermis. Acquired cutis laxa, both generalized and acral, can be a manifestation of an underlying paraproteinemia, with binding of immunoglobulins to elastic fibers (see Table 97.7). In addition, there is a form of post­ inflammatory elastolysis and cutis laxa that was originally described in young girls of African descent; an inflammatory phase consisting of indurated plaques or urticaria, malaise and fever precedes the development of diffuse wrinkling, atrophy, and severe disfigurement. Insect bites may be the trigger for the initial inflammatory lesions9. Less often, mid-dermal elastolysis is confused with solar elastosis or the perifollicular elastolysis that is usually seen on the trunk in association with acne vulgaris. Solar elastosis differs clinically by its onset in

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Atrophies of the skin are caused by a diminution or loss of collagen and/or elastic fibers. These disorders range from common conditions, such as striae distensiae, to those conditions associated with very rare syndromes (e.g. Conradi–Hünermann–Happle syndrome, Rombo syndrome). In addition, the areas of atrophy can range from quite large, as in mid-dermal elastolysis, to punctate, as in follicular atrophoderma. The involvement can also vary from subtle to obvious. In most disorders, the underlying pathogenesis remains to be discovered.

anetoderma, atrophoderma, atrophoderma of Pasini and Pierini, idiopathic atrophoderma of Pasini and Pierini, mid-dermal elastolysis, piezogenic papules, piezogenic pedal papules, striae, follicular atrophoderma, atrophia maculosa varioliformis cutis, atrophoderma vermiculatum

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ABSTRACT

non-print metadata KEYWORDS:

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Fig. 99.1 Mid-dermal elastolysis. A Type I – large diffuse patch as well as reticulated areas of fine wrinkling on the upper trunk and proximal arm. The junction of involved and uninvolved skin is marked with an arrow. B Types I and II – both circumscribed areas of wrinkling and follicular papules are present. C Type II – multiple skin-colored follicular papules.   D Type III – primarily reticulated erythema. A, Courtesy, Judit Stenn, MD;  

B–D, Courtesy, Lorenzo Cerroni, MD.

A

B

C

D

with preservation of elastic fibers around follicles in mid-dermal elastolysis.

Treatment Currently, there is no effective treatment for mid-dermal elastolysis. Sunscreens, colchicine, chloroquine, vitamin E, and topical agents (retinoic acid, corticosteroids) have been tried without success2.

ANETODERMA Synonyms:  ■ Macular atrophy ■ Anetoderma maculosa ■

Anetoderma maculosa cutis ■ Atrophia maculosa cutis

Key features

Fig. 99.2 Mid-dermal elastolysis – histopathologic features. A near absence of elastic fibers in a band-like distribution in the mid reticular dermis. Identification of these changes requires an elastic tissue stain (e.g. orcein).  

Courtesy, Lorenzo Cerroni, MD.

1724

an older age group, restriction to only sun-exposed areas, yellow color, and coarser wrinkling and differs histologically by hyperplasia of abnormal elastic fibers and basophilic degeneration of the collagen in the papillary dermis. Perifollicular elastolysis leads to a selective and almost complete loss of the elastic fibers that surround hair follicles, compared

■ Circumscribed 1–2 cm areas of flaccid skin, which may be elevated, macular, or depressed ■ Primary anetoderma has classically been divided into inflammatory and non-inflammatory ■ Secondary anetoderma is associated with infectious and inflammatory cutaneous disorders as well as tumors and autoimmune disorders (e.g. antiphospholipid antibody syndrome) ■ Focal dermal defect of elastic tissue

Introduction The term “anetoderma” is derived from anetos, the Greek word for slack, and derma for skin. Anetoderma is an elastolytic disorder

CHAPTER

Condition

Clinical findings

Site of predilection

Pathology

Anetoderma

Multiple circumscribed areas of flaccid skin; lesions are often elevated (protruding), but can be macular or depressed

Usually on trunk

Focal or complete loss of elastic tissue in the papillary and/or reticular dermis

Cutis laxa (see Ch. 97)

Loose, sagging skin folds resulting in prematurely aged appearance. Hereditary or acquired. Internal organ involvement, e.g. pulmonary, in hereditary form and generalized acquired form

Eyelids, cheeks, neck, shoulder girdle and abdomen; distal digits in acquired acral form

Diminished and fragmented elastic fibers usually throughout the dermis

Mid-dermal elastolysis

Diffuse areas of fine wrinkling (type I), perifollicular papules (type II), and/or reticulated erythema (type III) in middleaged women

Trunk, arms, and lateral neck

Selective loss of elastic fibers within the mid dermis in a band-like pattern

Pseudoxanthoma elasticum (PXE; see Ch. 97)

Yellowish coalescing skin papules, “cobblestoning”, and redundant folds in flexural sites; associated ocular and cardiovascular involvement

Lateral neck, axillae, and groin; scars

Clumped and calcified elastic fibers in the mid dermis

PXE-like papillary dermal elastolysis

Multiple, 2–3 mm, yellow or skin-colored papules that can coalesce into cobblestoned plaques

Neck, flexor forearms, axillae, lower abdomen, inframammary folds

Decreased elastic tissue in the papillary dermis (band-like pattern); clumping and fragmentation of elastic fibers; no calcification of elastic fibers

Atrophies of Connective Tissue

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DISORDERS OF ELASTIC TISSUE

Table 99.1 Disorders of elastic tissue. For additional entities, see Tables 95.5, 97.4 and 97.6.  

characterized by localized areas of flaccid skin, which may be depressed, macular or papular; the latter can reflect herniation of the subcutaneous tissue. Anetoderma may be idiopathic or associated with an inflammatory disorder of the skin.

CLASSIFICATION OF ANETODERMA Primary anetoderma



Secondary anetoderma



Familial anetoderma



Anetoderma of prematurity



History The first case of primary inflammatory anetoderma was reported by Jadassohn in 1892. The patient was a 23-year-old woman with depressed pink-to-red lesions on her elbows that were noted to have an atrophic, wrinkled appearance10. A year previously, Schweninger and Buzzi described a 29-year-old woman with multiple sac-like tumors that demonstrated herniation upon palpation; the lesions were located on the trunk and upper extremities but lacked inflammation11.

Epidemiology Several hundred cases of anetoderma have been reported in the world literature since the original report. Primary anetoderma favors young adults between 15 and 25 years of age and occurs more frequently in women than men. The epidemiology of secondary anetoderma reflects that of the underlying etiologies (see Table 99.3).

Pathogenesis The pathogenesis of anetoderma is not known. These lesions could be considered unusual scars, since scars also have decreased elastic tissue. The loss of dermal elastin may reflect an impaired turnover of elastin, caused by either increased destruction or decreased synthesis of elastic fibers. There are a number of proposed explanations for the focal elastin destruction, e.g. the release of elastase from inflammatory cells, the release of cytokines such as interleukin-6, an increased production of progelatinases A and B12, and the phagocytosis of elastic fibers by macrophages. In addition, immunologic mechanisms may play a role in anetoderma and may explain the reported associated findings of antiphospholipid antibodies, antinuclear antibodies, false-positive serologic testing for syphilis or Borrelia spp., and positive direct immunofluorescence (see below). In primary anetoderma, there is no underlying associated disorder and lesions arise within clinically normal skin. It can be classified into two major forms: those with preceding inflammatory lesions (the Jadassohn–Pellizzari type) and those without preceding inflammatory lesions (the Schweninger–Buzzi type) (Table 99.2). This clinical classification is primarily of historical interest, since the two types of lesions can coexist in the same patient and their histopathology is often the same (i.e. inflammation has been observed in both types of lesions);

Jadassohn–Pellizzari type: preceding inflammatory lesions • Schweninger–Buzzi type: no preceding inflammatory lesions Associated with a primary dermatosis or cutaneous tumor • Associated with a systemic disease (autoimmune, antiphospholipid syndrome, infectious) or drug Both autosomal dominant and autosomal recessive forms • Usually develops in first decade of life Occurs in extremely premature infants At sites of monitoring leads or adhesives



Table 99.2 Classification of anetoderma.  

the presence or absence of clinical inflammation at the onset of the disease is not related to prognosis13. Secondary anetoderma can arise in the setting of a primary inflammatory dermatosis, skin infection or cutaneous tumor, as well as in patients with systemic disorders (e.g. autoimmune). Over the past decade, an association with antiphospholipid antibody syndrome has been highlighted. Although the vast majority of cases are sporadic, familial anetoderma has been described and is usually not associated with pre-existing lesions14.

Clinical features The characteristic lesions are flaccid, circumscribed areas of slack skin that are a reflection of a marked reduction or absence of dermal elastic fibers; they can appear as depressions, wrinkling, or sac-like protrusions (Fig. 99.3). These atrophic lesions vary in number from a few to hundreds, and they typically measure 1–2 cm in diameter and are skincolored to blue–white in color. The skin surface can be normal in appearance or wrinkled, and a central depression may be seen. Coalescence of smaller lesions can give rise to larger herniations. The examining finger sinks into a distinct pit with sharp borders as if into a hernia ring. The bulge reappears when the pressure from the finger is released. This clinical finding is referred to as the “buttonhole” sign and is similar to that observed in neurofibromas.

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$

&

%

Fig. 99.3 Primary anetoderma. Lesions can range from soft, skin-colored papules that herniate upon palpation (A) to flaccid papules that have a central depression (B). The upper trunk and neck is a common location for primary anetoderma (C). A, Courtesy, Ronald P Rapini, MD; C, Courtesy, Thomas Schwarz, MD.  

Predilection sites for these asymptomatic lesions are the chest, back, neck, and upper extremities. Primary anetoderma usually develops in young adults, and new lesions often continue to form for many years as the older lesions fail to resolve. Secondary anetoderma implies that the characteristic atrophic lesion has appeared in the same site as a previous specific skin lesion. Some authors also consider lesions associated with an underlying disease (e.g. HIV infection, antiphospholipid antibody syndrome, autoimmune thyroiditis) as secondary anetoderma; however, in this instance, the atrophic areas do not necessarily develop within areas of known inflammation. Evaluation for the presence of antiphospholipid antibodies should be performed before patients with idiopathic anetoderma are labeled as having primary anetoderma15. The range of heterogeneous conditions associated with secondary anetoderma are outlined in Table 99.3. With the exception of distribution (and perhaps size), the clinical features are the same as those of primary anetoderma. Anetoderma has increasingly been reported in premature infants. In most neonates, it appears to be related to the use of cutaneous monitoring leads or adhesives16, as well as extreme prematurity16. In patients with anetoderma, a variety of systemic abnormalities have been reported, including ocular, endocrinologic, skeletal, cardiac, pulmonary, and gastrointestinal disease. Because there has been no consistency with regard to these associated abnormalities, they are probably coincidental, although the possibility exists that they may reflect a more generalized elastolytic disorder that has yet to be defined.

SECONDARY ANETODERMA – ASSOCIATED CONDITIONS Infectious



Drugs



Inflammatory



Penicillamine

Differential diagnosis

1726

Anetoderma must be differentiated from other disorders of elastic tissue such as mid-dermal elastolysis (see Table 99.1) as well as atrophodermas (see below). However, the major differential diagnosis consists of post-traumatic scars and papular elastorrhexis. The latter is an acquired disorder characterized by firm, white, non-follicular papules that measure 2–5 mm in diameter and are evenly scattered on the trunk.

Acne vulgaris Mastocytosis • Lichen planus • Granuloma annulare • Juvenile xanthogranuloma • Cutaneous sarcoidosis • Cutaneous lymphoid hyperplasia (lymphocytoma cutis) • Prurigo nodularis • Insect bites •

Autoimmune

Discoid and systemic lupus erythematosus Antiphospholipid syndrome • Primary Sjögren syndrome • Addison disease • Graves disease • •

Pathology In routinely stained sections, the collagen within the dermis of affected skin appears normal. Perivascular lymphocytes are often present but do not correlate with clinical findings of inflammation. The majority of lymphocytes are T helper cells. The predominant abnormality (as revealed by elastic tissue stains) is a focal, more or less complete loss of elastic tissue in the papillary and/ or reticular dermis. There are usually some residual abnormal, irregular, and fragmented elastic fibers (Fig. 99.4)17. Plasma cells and histiocytes with occasional granuloma formation can be seen. Direct immunofluorescence sometimes shows linear or granular deposits of immunoglobulins and complement along the dermal– epidermal junction or around the dermal blood vessels in affected skin18. However, these findings are not helpful diagnostically. By electron microscopy, the elastic fibers are fragmented and irregular in shape and occasionally they are engulfed by macrophages.

Varicella Folliculitis • Syphilis (cutaneous) • Lepromatous leprosy • Molluscum contagiosum • Tuberculosis (cutaneous) • HIV infection • Acrodermatitis chronica atrophicans • Post-hepatitis B immunization •

Tumors and depositions

Involuted infantile hemangioma Pilomatricoma • Melanocytic nevus • Dermatofibroma • Dermatofibrosarcoma protuberans • Primary cutaneous marginal zone B-cell lymphoma (formerly primary cutaneous plasmacytoma or immunocytoma) • Mycosis fungoides • Nodular amyloidosis • Xanthoma • •

Table 99.3 Secondary anetoderma – associated conditions.  

The lesions usually appear during adolescence or early adulthood. Histology demonstrates focal degeneration of elastic fibers and normal collagen. There are no associated extracutaneous abnormalities. This disorder is believed by some authors to be a variant of connective tissue nevi19 or an abortive form of the Buschke–Ollendorff syndrome20, while others think that these lesions represent papular acne scars21. In contrast to anetoderma, lesions of papular elastorrhexis are firm and non-compressible.

Pathogenesis Factors leading to the development of striae have not been fully elucidated. Striae distensae are a reflection of “breaks” in the connective tissue that lead to dermal atrophy. A number of factors, including hormones (particularly corticosteroids), mechanical stress and genetic predisposition, appear to play a role.

Clinical features

Fig. 99.4 Anetoderma – histopathologic features. A decrease of elastic fibers in both the papillary and reticular dermis (Weigert’s stain). Courtesy, Lorenzo Cerroni,  

MD.

Less often, anetoderma is confused with perifollicular elastolysis (see above), nevus lipomatosus, or focal dermal hypoplasia (Goltz syndrome). Nevus lipomatosus superficialis of Hoffman and Zurhelle presents as a clustered group of soft, skin-colored to yellow nodules, usually located on the lower trunk and present since birth (see Ch. 117). Histology shows ectopic mature lipocytes located within the dermis. The lesions of Goltz syndrome (including telangiectasias, vermiculate dermal atrophy, hypopigmentation, hyperpigmentation, and fatty herniations/ hamartomas) are in a linear array along the lines of Blaschko (see Ch. 62). Histologically, a decrease in dermal content is seen as well as extension or deposition of subcutaneous fat into the dermis.

Treatment Various therapeutic modalities have been tried, but have not resulted in improvement of existing atrophic lesions; these include intralesional injections of triamcinolone and systemic administration of aspirin, dapsone, phenytoin, penicillin G, vitamin E, and inositol niacinate. Some authors have reported improvement with hydroxychloroquine. Surgical excision of limited lesions may be helpful, with informed consent from the patient regarding the risk of scar formation. The utility of soft tissue fillers is inconclusive.

STRIAE Synonyms:  ■ Striae distensae ■ Striae atrophicans ■ “Stretch marks” ■

Striae gravidarum

Introduction Striae are a very common condition in most age groups. They are linear atrophic depressions of the skin that form in areas of dermal damage produced by stretching of the skin. They are associated with various physiologic states, including puberty, pregnancy, rapid growth, weight gain or loss, obesity22, and disorders that lead to hypercortisolism. Striae also develop at sites of potent topical corticosteroid application, in particular occluded intertriginous zones.

History Striae were first described by Roederer in 1773, and the first histologic descriptions were made by Troisier and Menetrier in 1889.

Epidemiology Striae are very common and usually develop between the ages of 5 and 50 years. They are seen more commonly in Caucasians and occur about

Striae are usually multiple, symmetric, well-defined, linear atrophic lesions that often follow the lines of cleavage. They are usually more of a cosmetic concern, but rarely they can ulcerate. Initially, striae appear as red-to-violaceous elevated lines that can be mildly pruritic and are called striae rubrae (Fig. 99.5). Over time, the color gradually fades, and the lesions become atrophic, exhibiting a fine wrinkled appearance. These striae albae are usually permanent, but they may fade somewhat over time23. The striae can measure several centimeters in length and a few millimeters to a few centimeters in width. During puberty, striae appear in areas where there is a rapid increase in size. In girls, the most common sites are the thighs, hips, buttocks and breasts, whereas in boys, they are seen on the shoulders, thighs, buttocks, and lumbosacral region (Fig. 99.6). Other less common sites include the abdomen, upper arms, neck, and axillae. Striae distensae are a common finding on the abdomen, and less so on the breasts and thighs, of pregnant women, especially during the last trimester. They are more common in younger primigravidas than in older pregnant women, in those who gained more weight during pregnancy, and/or those who had babies with a higher birth weight. The development of striae gravidarum has been associated with an increased risk of laceration during vaginal delivery as well as subsequent pelvic relaxation and clinical prolapse25,26. The striae associated with systemic corticosteroid therapy and Cushing syndrome can be larger and more widely distributed (see Ch. 53). Flexural and intertriginous areas are particularly at risk for developing striae from the use of potent topical corticosteroids. Atrophic striae may become elevated and “worm-like” in the setting of severe edema, including lymphedema. In polymorphic eruption of pregnancy, initial lesions often arise within striae gravidarum.

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99 Atrophies of Connective Tissue

twice as frequently in women as in men. They commonly develop during puberty, with an overall incidence of 25–35%23, or during pregnancy, with an incidence of approximately 75%24.

Pathology Histologic findings are similar to those of scars and depend upon the stage of evolution of the striae at the time the biopsy is performed. The epidermis can be normal during the early stages, but eventually becomes atrophic with blunted rete ridges. The dermal thickness is decreased, as is the collagen in the upper dermis. The collagen bundles lie parallel to the epidermis. Alterations in elastic fibers are variable, but they can be fragmented, and specific elastin staining can demonstrate a marked reduction compared with adjacent normal dermis27. There is an absence of both hair follicles and other adnexal structures.

Differential diagnosis The diagnosis of striae distensae is usually straightforward, but the differential diagnosis does include linear focal elastosis (elastotic striae), an entity first described by Burket et al.28 in 1989. Linear focal elastosis is characterized by rows of yellow, palpable, striae-like bands on the lower back. Unlike striae, the lesions are raised and yellow rather than depressed and white. Elderly men are most commonly affected. Histologically, there is a focal increase in the number of elongated or fragmented elastic fibers as well as a thickened dermis. It is postulated that linear focal elastosis may represent an excessive regenerative process of elastic fibers and could be viewed as a keloidal repair of striae distensae29. An entity referred to as linear lumbar localized elastolysis is said to occur most often in young men; the linear, raised bands are skincolored and histologically there is elastolysis within the mid dermis.

Treatment Striae distensae have no medical consequences, but they are frequently distressing to those afflicted. As striae tend to improve spontaneously over time, the value of anecdotal therapies without case controls is

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COMMON ANATOMIC SITES OF STRIAE AND LINEAR FOCAL ELASTOSIS

$

Pregnancy-related striae Striae and linear focal elastosis Other striae (e.g. puberty-related)

Fig. 99.6 Common anatomic sites of striae and linear focal elastosis. Striae associated with pregnancy are in green and lesions of linear focal elastosis are in blue.  

%

on striae albae; secondary pigmentary alterations in darker skin are a potential complication32. Improvement in the leukoderma of striae albae was noted with the 308 nm excimer laser, but maintenance treatment was required to sustain the cosmetic benefit33. Use of radiofrequency and pulsed magnetic fields may also lead to improvement34. However, currently, there is no specific therapy that results in a complete response.

ATROPHODERMA OF PASINI AND PIERINI Synonyms:  ■ Idiopathic atrophoderma of Pasini and Pierini

Atrophoderma ■ Sclérodermie atrophique d’emblée ■ Morphea plana atrophica ■

Key features

&

Fig. 99.5 Striae. A Linear erythematous lesions on the abdomen (striae rubrae). B Atrophic linear lesions of striae albae in a teenager. C Large axillary striae in a patient receiving chronic, high-dose systemic corticosteroids. B, Courtesy, Kalman

■ Depressed patches, usually on the posterior trunk and brown in color ■ “Cliff-drop” or abrupt transition from normal to diseased skin ■ Lesions are asymptomatic and lack induration ■ Disorder lasts for many years but has a benign course



Watsky, MD.

1728

difficult to assess. Treatment of early-stage striae with tretinoin 0.1% cream can improve their appearance, and its application has been shown to decrease the length and width of striae30. Other topical treatments, including 0.05% tretinoin/20% glycolic acid and 10% L-ascorbic acid/20% glycolic acid, may also improve the appearance of stretch marks31. Several lasers have been used to treat striae: the 585 nm pulsed dye laser may improve the appearance of striae rubrae, but it has no effect

Introduction Atrophoderma of Pasini and Pierini is a form of dermal atrophy that presents as one or more sharply demarcated depressed patches, usually on the back of adolescents or young adults. Whether atrophoderma represents an atypical, primarily atrophic form of morphea or “burntout” morphea or a separate distinct entity is still debated.

History In 1923, Pasini described atrophic cutaneous lesions on the trunk of a 21-year-old woman that he referred to as progressive idiopathic

CHAPTER

atrophoderma35. In 1936, and over the subsequent years, Pierini and associates extensively studied and defined the condition and its possible link to morphea. This prompted Canizares et al.36 in 1958 to rename this entity “idiopathic atrophoderma of Pasini and Pierini”.

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Epidemiology This disorder is more frequently encountered in women than in men, with a ratio of 6 : 1 in adults37. It usually starts insidiously in young individuals during the second or third decade of life. However, a number of cases have been described in children younger than 13 years of age. More recently, rare congenital cases have been reported38.

Pathogenesis The etiology of atrophoderma of Pasini and Pierini remains as yet unknown. Some authors have suggested the possible role of Borrelia burgdorferi infection, as in acrodermatitis chronica atrophicans, since a positive serology can be found in up to 40–50% of European patients39. However, false-positive results can occur, and results have varied widely. Given some overlap between atrophoderma and morphea, perhaps insights into the pathogenesis of the latter will provide clues to the former.

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Fig. 99.7 Atrophoderma of Pasini and Pierini. A,B Multiple light brown patches on the back; note the subtle depression of the lesions with a “cliff-drop” edge. In A, dermal blood vessels are easily seen within a few patches; the white papule is a healed biopsy site. A,  

Clinical features Lesions usually appear on the trunk, especially the back and lumbo­ sacral region, followed in frequency by the chest, arms, and abdomen39. The face, hands, and feet are usually spared. The distribution is often symmetric and bilateral, but a linear pattern along the lines of Blaschko has been described (atrophoderma of Moulin; see Ch. 67). The lesions are single or multiple and usually round or ovoid, ranging in size from a few centimeters to patches covering large areas of the trunk. They are usually asymptomatic and lack inflammation. When lesions coalesce, they can form large irregular patches. The patches usually have a brown color (Fig. 99.7), but some are blue to violet in color or occasionally hypopigmented40. The surface of the skin is normal in appearance, as is the consistency upon palpation. There is a lack of cutaneous induration or sclerosis. The borders or edges of these lesions are sharply defined, and they are usually described as abrupt “cliff-drop” borders ranging from 1 to 8 mm in depth, although they can have a gradual slant and the depression may be subtle36. These depressed patches often give the impression of inverted plateaus, or, if multiple lesions are present, they can have the appearance of Swiss cheese. The lesions are even more apparent when present on the back, because the dermis is thicker in this area. Occasionally, dermal blood vessels are visible within the depressed patches. The skin surrounding the patches is normal in appearance, and there is no erythema or lilac ring as in morphea. However, typical lesions of morphea, lichen sclerosus, and atrophoderma have been observed to occur simultaneously in the same patient (but in different areas), supporting the view that these conditions are related41. In addition, sclerodermatous changes can occasionally appear years later in the center of the depressed lesions, leading to a white, shiny induration36. In a series of 139 patients, 17% had a white induration in the central portions of their atrophic lesions, and, in 22%, superficial plaques of morphea coexisted in sites separate from the atrophic foci37. The course of this benign disease is progressive, and lesions can continue to appear for decades before reaching a standstill. Transformation to generalized morphea has not been observed.

Pathology In general, the histologic picture is not diagnostic, so the diagnosis is primarily a clinical one. The epidermis is usually normal or slightly atrophic. Pigmentation of the basal layer may be increased. A perivascular infiltrate consisting of T cells and histiocytes may be seen. Collagen bundles in the reticular dermis show varying degrees of homogenization and clumping. Dermal thickness is reduced when compared with adjacent normal skin42. Dermal atrophy is difficult to evaluate on a punch biopsy, but it can be more easily demonstrated if an elliptical biopsy is taken in an area that includes the cliff-drop border and is then sectioned longitudinally to show the transition between normal and lesional skin. MRI performed in one patient with atrophoderma of Pierini and Pasini showed that the clinical depression was not

Courtesy, Julie V Schaffer, MD; B, Courtesy, Catherine C McCuaig, MD.

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secondary to subcutaneous atrophy43. In most series, no abnormality has been observed with elastic tissue stains37,39; however, a retrospective study described a spectrum of changes, ranging from normal to severe diminution and fragmentation of the elastic fiber network40. The diagnostic value of elastic tissue changes is still debatable. The adnexal structures are usually preserved. If sclerodermatous changes appear in pre-existing patches, the histology reveals varying degrees of collagen sclerosis resembling morphea. Direct immunofluorescence may show nonspecific IgM and C3 staining in the dermal papillary blood vessels in early lesions or at the dermal–epidermal junction44.

Differential diagnosis Since the original description, there has been much discussion over whether atrophoderma of Pasini and Pierini is a distinct entity or an atrophic, non-indurated, perhaps “burnt-out” variant of morphea (see Ch. 44). Active lesions of morphea present as indurated, often hyperpigmented plaques with a characteristic peripheral lilac rim. Although atrophoderma of Pasini and Pierini lacks sclerosis37,39,41,44, its relationship to morphea is favored by its striking clinical and histologic similarities to the atrophy seen at sites of regressing plaques of morphea. To some, the different course and outcome of atrophoderma of Pierini and Pasini as compared with morphea justifies preservation of a distinct name. Anetoderma, also an atrophic dermal process, is easily differentiated by palpation and histology, which consistently shows a loss of elastic fibers in the dermis (as opposed to a loss of collagen).

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Treatment The natural course of the disease is often protracted (10–20 years) but self-healing, making the evaluation of therapy difficult. No treatment has been proven effective. In view of the possibility of an underlying Borrelia infection, penicillin and doxycycline have been used to treat atrophoderma of Pasini and Pierini, but the results have been variable39,45. A dramatic response to oral hydroxychloroquine was reported in one patient46, and three treatment sessions with the Q-switched alexandrite laser were effective in diminishing hyperpigmentation by 50% in another patient47.

FOLLICULAR ATROPHODERMA Follicular atrophoderma refers to dimple-like depressions at the follicular orifices. It can occur as an isolated defect of limited extent, in association with a variety of disorders in which hair follicles are plugged with keratin, or with rare genodermatoses. In 1944, Miescher described follicular atrophoderma in an 8-year-old girl with atypical chondrodystrophy48. Six years later, Curth also used the term follicular atrophoderma (although there was no evidence of follicular atrophy but rather follicular agenesis) and further reported in 1978 on the genetics of follicular atrophoderma49.

Clinical features Distinctive follicular ice-pick depressions can be seen most commonly on the back of the hands and feet or on the cheeks. These pitted scars are often present at birth or appear during childhood. A family history may be present. Follicular atrophoderma can be associated with Bazex– Dupré–Christol and Conradi–Hünermann–Happle syndromes. When the lesions are found exclusively on the cheeks, the term “atrophoderma vermiculatum” applies. Atrophoderma vermiculatum can in turn be associated with various disorders discussed in the next section.

Atrophoderma Vermiculatum Atrophoderma vermiculatum, a disorder limited to the face, has been described under a variety of names, including ulerythema acneiforme, acne vermoulante, atrophoderma reticulata symmetrica faciei, folliculitis ulerythema reticulata, folliculitis ulerythemosa, and honeycomb atrophy (“ulerythema” means scar plus redness and “vermiculatum” means worm-eaten). Atrophoderma vermiculatum may: (1) occur sporadically; (2) be inherited as an autosomal dominant disorder; (3) be part of a group of related diseases that are referred to as “keratosis pilaris atrophicans” (see Table. 38.2); or (4) be associated with various syndromes. Multiple symmetric inflammatory papules on the cheeks, presumably centered around hair follicles, may precede the atrophic lesions. These papules then go on to become pitted, atrophic, depressed scars in a reticulated or honeycomb pattern (Fig. 99.8). The severity of erythema varies, as does the presence of milia and horny follicular plugs.

Fig. 99.8 Atrophoderma vermiculatum. Multiple small pitted scars on the cheek of a young girl. Note the honeycomb pattern on the lower inner cheek; the skin is said to appear “worm-eaten”. Courtesy, Robert Hartman, MD.  

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Lesions can extend to the forehead and preauricular regions. Atrophoderma vermiculatum usually has its onset during childhood or, less often, around puberty. Both sexes appear to be equally affected50, and it usually has a slowly progressive course. Atrophoderma vermiculatum can be associated with a group of closely related disorders referred to as keratosis pilaris atrophicans (see Table. 38.2)51. This group also includes keratosis follicularis spinulosa decalvans and ulerythema ophryogenes. These conditions are characterized by keratotic follicular papules, variable degrees of inflammation, and secondary atrophic scarring. Ulerythema ophryogenes (or keratosis pilaris atrophicans faciei) differs from atrophoderma vermiculatum by affecting primarily the lateral portion of the eyebrows (ophryogenes) in the form of erythema, follicular papules, and alopecia. The inheritance pattern is autosomal dominant with incomplete penetrance, and progression usually ceases after puberty. Keratosis follicularis spinulosa decalvans begins during childhood as keratotic follicular papules on the malar area and progresses to involve the eyebrows, scalp and extremities, with associated scarring alopecia. In most patients, this disorder is inherited in an X-linked recessive fashion. The underlying pathogenesis in atrophoderma vermiculatum as well as the other disorders in the keratosis pilaris atrophicans group appears to be abnormal follicular hyperkeratinization. The latter occurs in the upper third of the hair follicle, leading to obstruction of the growing hair shaft and production of chronic inflammation. The end result is scarring below the level of obstruction. Histopathology is usually not very helpful and shows dilated follicles, sometimes associated with plugging, inflammation, and sclerosis of dermal collagen. Syndromes associated with atrophoderma vermiculatum include Rombo syndrome (milia, telangiectasias, basal cell carcinomas [BCCs], hypotrichosis, acrocyanosis, and, rarely, trichoepitheliomas), Nicolau– Balus syndrome (syringomas and milia), and Loeys–Dietz syndrome (see Ch. 95). In addition, the presence of an ipsilateral congenital cataract has been reported. The differential diagnosis of atrophoderma vermiculatum includes atrophia maculosa varioliformis cutis, keratosis pilaris rubra of the cheeks, and, in older adults, erythromelanosis faciei. This disorder is primarily a cosmetic problem. Various topical treatments, including emollients, corticosteroids, tretinoin and keratolytics, have shown no consistent benefit. In some instances, systemic isotretinoin has been shown to stop progression and to induce remission51. Dermabrasion, laser therapy (e.g. CO2, 585 nm pulsed dye), and fillers (e.g. hyaluronic acid, autologous fat) are other options for improving the appearance of the atrophic scars52.

Bazex–Dupré–Christol Syndrome Bazex, Dupré and Christol first described this genodermatosis in 1964, not to be confused with Bazex syndrome (acrokeratosis paraneoplastica) in which hyperkeratotic plaques of the ears, nose, cheeks, hands, feet and knees are associated with carcinomas of the upper aerodigestive tract (see Ch. 53). Bazex–Dupré–Christol syndrome is characterized by follicular atrophoderma, milia, multiple BCCs, hypotrichosis, and localized hypohidrosis (above the neck)53. It is inherited in an X-linked dominant fashion, and the gene has been linked to Xq24–q2754. Additional reported findings include facial hyperpigmentation, hair shaft anomalies and multiple trichoepitheliomas. Systemic manifestations are absent. Recently, it was suggested that this syndrome might better be classified as an ectodermal dysplasia55. The follicular atrophoderma, described as multiple ice-pick marks or patulous follicles, is found most commonly on the dorsal aspect of the hands, but can also be seen on the feet, lower back, elbows, and rarely the face; it may be present at birth or appear later during childhood. No abnormalities of the elastic fibers have been found (nor any evidence of atrophy of the epidermis, hair or dermis), making the term “follicular atrophoderma” a misnomer. The histopathology usually shows hair follicles that are abnormally wide, plugged, and surrounded by an inflammatory cell infiltrate and clusters of basaloid cells. Sweat glands can be absent. The BCCs develop in about 40% of patients (primarily on the face) and they can resemble melanocytic nevi; the age of onset varies from 9 to 50 years of age. To date, ~20 families with this syndrome have been described.

Conradi–Hünermann–Happle Syndrome (X-Linked Dominant Chondrodysplasia Punctata, CDPX2) Conradi–Hünermann–Happle syndrome is an X-linked dominant disorder that occurs almost exclusively in girls, since it is usually lethal in hemizygous males. This form of chondrodysplasia punctata results from mosaicism for mutations in the gene on the X chromosome that encodes the emopamil-binding protein56,57. The clinical manifestations include ichthyosiform streaks (composed of erythema plus feathery, adherent scale) patterned along the lines of Blaschko; they usually resolve during the first year of life and are replaced by bands of follicular atrophoderma57. Hyperpigmentation, cataracts, scarring alopecia, saddle-nose deformity, asymmetric limb reduction defects, and stippled calcifications of the epiphyses are additional manifestations (see Ch. 57). Within the ichthyosiform areas in newborns, keratotic follicular plugs containing dystrophic calcification is a distinctive histopathologic feature56.

ATROPHIA MACULOSA VARIOLIFORMIS CUTIS Atrophia maculosa varioliformis cutis was first described by Heidingsfeld in 191858 and is not as rare as the number of published cases would suggest. It consists of small round “varioliform” and linear facial depressions that are asymptomatic (Fig. 99.9)59. It occurs spontaneously on the cheeks and occasionally involves the forehead or chin. There is a gradual increase in the number of lesions, but in the absence of preceding trauma, acne, or inflammatory lesions. A familial variant has been described. Pachydermodactyly and extrahepatic biliary atresia have been associated findings, but this association is probably fortuitous. The pathogenesis is unknown. The histologic changes include a depression of the epidermis and normal collagen fibers, but a slightly decreased number of elastic fibers. There is usually little or no inflammation. The differential diagnosis includes simple scars, which can be differentiated by history and the

presence histologically of dermal fibrosis, and atrophoderma vermiculatum. The latter is harder to differentiate, but it can present with inflammatory papules that are followed by pitted scars, and atrophoderma vermiculatum usually has a honeycombed (rather than sharply linear) pattern and is usually centered on hair follicles. There is no known treatment to prevent the occurrence of these lesions.

PIEZOGENIC PEDAL PAPULES (PIEZOGENIC PAPULES) Piezogenic pedal papules were first described by Shelley and Rawnsley in 196860. This term is somewhat of a misnomer as piezogenic means “producing pressure”, when in fact these lesions are produced by pressure. It is postulated that pressure induces herniation of fat through connective tissue in the dermis of the heels. These papules are common enough in the general population to be considered normal and have also been described in association with Ehlers–Danlos syndrome and Prader–Willi syndrome. An infantile variant characterized by larger nodules on the medial aspect of the heel (present without weight-bearing) has been described (Fig. 99.10)61 and has to be distinguished from juvenile aponeurotic fibroma. Skin-colored papules and nodules are seen on the sides of the heels (see Ch. 88); they are induced by weight-bearing and disappear when the leg is raised. The lesions are usually asymptomatic, but pain has been described during weight-bearing, and, in these cases, an ortho­ pedic shoe or surgical excision may help. Similar lesions have been described on the wrists62.

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99 Atrophies of Connective Tissue

The differential diagnosis includes other genodermatoses with multiple BCCs: basal cell nevus syndrome (Gorlin syndrome), an autosomal dominant disorder most commonly due to mutations in the PTCH1 gene; Rombo syndrome, an autosomal dominant disorder characterized by BCCs, atrophoderma vermiculatum, milia, hypotrichosis, acrocyanosis, and, occasionally, trichoepitheliomas; and xeroderma pigmentosum.

OTHER ATROPHIES OF THE CONNECTIVE TISSUE Many systemic conditions (scleroderma, lupus erythematosus, dermatomyositis) and genodermatoses (Rothmund–Thomson syndrome, dyskeratosis congenita, Cockayne syndrome, Hallermann–Streiff syndrome) have cutaneous atrophy (epidermal, dermal, and/or subcutaneous) as an associated finding. Lichen sclerosus is discussed in Chapter 44, progeria in Chapter 63, Ehlers–Danlos syndrome and cutis laxa in Chapter 97, and acrodermatosis chronica atrophicans in Chapter 74. Cutaneous atrophy is also a well-known complication of prolonged use of either systemic or topical corticosteroids (see Ch. 125). For additional online figures visit www.expertconsult.com

Fig. 99.10 Pedal papules of infancy. Soft nodules on the medial and plantar surfaces of the foot. Courtesy, Julie V Schaffer, MD.  

Fig. 99.9 Atrophia maculosa varioliformis cutis. Multiple linear scar-like depressions (between and above arrows) with no history of trauma. Courtesy, Jean  

L Bolognia, MD.

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B, Courtesy, Louis A Fragola, Jr, MD.

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eFig. 99.1 Secondary anetoderma. Wrinkling of the skin at sites of sarcoidosis (A) and lepromatous leprosy (B).

eFig. 99.2 Linear focal elastosis. This is the most common site of involvement. Note that the lesions are elevated and yellowish in color.  

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eFig. 99.3 Piezogenic pedal papules (piezogenic  

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REFERENCES 1. Shelley WB, Wood MG. Wrinkles due to idiopathic loss of mid-dermal elastic tissue. Br J Dermatol 1977;97:441–5. 2. Patroi I, Annessi G, Girolomoni G. Mid-dermal elastolysis: a clinical, histologic, and immunohistochemical study of 11 patients. J Am Acad Dermatol 2003;48:846–51. 3. Gambichler T. Mid-dermal elastolysis revisited. Arch Dermatol Res 2010;302:85–93. 4. Snider RL, Lang PG, Maize JC. The clinical spectrum of mid-dermal elastolysis and the role of UV light in its pathogenesis. J Am Acad Dermatol 1993;28:938–42. 5. Vatve M, Morton R, Bilsland D. A case of mid-dermal elastolysis after narrowband ultraviolet B phototherapy. Clin Exp Dermatol 2009;34:263–4. 6. Gambichler T, Breuckmann F, Kreuter A, et al. Immunohistochemical investigation of mid-dermal elastolysis. Clin Exp Dermatol 2004;29:192–5. 7. Gambichler T, Skrygan M. Decreased lysyl oxidase-like 2 expressionmin mid-dermal elastolysis. Arch Dermatol Res 2013;305:359–63. 8. Scola N, Goulioumis A, Gambichler T. Non-invasive imaging of mid-dermal elastolysis. Clin Exp Dermatol 2011;36:155–60. 9. Harmon CB, Su WPD, Gagne EJ, et al. Ultrastructural evaluation of mid-dermal elastolysis. J Cutan Pathol 1994;21:233–8. 10. Jadassohn J. Uber eine eigenartige form von ‘atrophica maculosa cutis. Arch Dermatol Syphilol 1892;24:342–58. 11. Schweninger E, Buzzi F. Multiple benign tumor-like new growths of the skin. In: International Atlas Sellltener Hautkrankheiten, plate 15. Leipzig: L Voss; 1891. 12. Venencie PY, Bonnefoy A, Gogly B, et al. Increased expression of gelatinases A and B by skin explants from patients with anetoderma. Br J Dermatol 1997;137:517–25. 13. Venencie PY, Winkelmann RK, Moore BA. Anetoderma: clinical findings, associations, and long-term follow-up evaluations. Arch Dermatol 1984;120:1032–9. 14. Patrizi A, Neri I, Virdi A, et al. Familial anetoderma: a report of two families. Eur J Dermatol 2011;21:680–5. 15. Hodak E, Feureman H, David M. Primary anetoderma is a cutaneous sign of antiphospholipid antibodies. J Am Acad Dermatol 2008;58:351. 16. Gougeon E, Beer F, Gay S, et al. Anetoderma of prematurity: an iatrogenic consequence of neonatal intensive care. Arch Dermatol 2010;146:565–7. 17. Venecie PY, Wilkelmann RK. Histopathologic findings in anetoderma. Arch Dermatol 1984;120:1040–4. 18. Bergman R, Friedman-Birnbaum R, Hazaz B, et al. An immunofluorescence study of primary anetoderma. Clin Exp Dermatol 1990;15:124–30. 19. Sears J, Stone M, Argenyi Z. Papular elastorrhexis:   a variant of connective tissue nevus: case reports and review of the literature. J Am Acad Dermatol 1988;19:409–14. 20. Schirren H, Schirren C, Stolz W, et al. Papular elastorrhexis: a variant of dermatofibrosis lenticularis disseminata (Buschke-Ollendorff syndrome). Dermatology 1994;189:368–72. 21. Wilson B, Dent C, Cooper P. Papular acne scars:   a common cutaneous finding. Arch Dermatol 1990;126:797–800. 22. Garda-Hidalgo L, Orozco-Topete R, Gonzalez-Barranco J, et al. Dermatoses in 156 obese adults. Obes Res 1999;7:299–302.

23. Ammar NM, Rao B, Schwartz RA, et al. Adolescent striae. Cutis 2000;65:69–70. 24. Muzaffar F, Hussain I, Haroon TS. Physiologic skin changes during pregnancy: a study of 140 cases. Int J Dermatol 1998;37:429–31. 25. Wahman AJ, Finan MA, Emerson SC. Striae gravidarum as a predictor of vaginal lacerations at delivery. South Med J 2000;93:873–6. 26. Salter SA, Batra RS, Rohrer TE, et al. Striae and pelvic relaxation: two disorders of connective tissue with a strong association. J Invest Dermatol 2006;126:1745–8. 27. Arem A, Ward Kisher C. Analysis of striae. Plast Reconstr Surg 1980;65:22–9. 28. Burket JM, Zelickson AS, Padilla RS. Linear focal elastosis (elastotic striae). J Am Acad Dermatol 1989;20:633–6. 29. Hashimoto K. Linear focal elastosis: keloidal repair of striae distensae. J Am Acad Dermatol 1998;39:309–13. 30. Kang S. Topical tretinoin therapy for management of early striae. J Am Acad Dermatol 1998;39:S90–2. 31. Ash K, Lord J, Zukowski M, McDaniel D. Comparison of topical therapy for striae alba (20% glycolic acid/0.05% tretinoin versus 20% glycolic acid/10% L-ascorbic acid). Dermatol Surg 1998;24:849–56. 32. Jimenez GP, Flores F, Berman B, Gunja-Smith Z. Treatment of striae rubra and striae alba with the 585-nm pulsed-dye laser. Dermatol Surg 2003;29:362–5. 33. Alexiades-Amenakas MR, Bernstein LJ, Friedman PM, Geronemus RG. The safety and efficacy of the 308-nm excimer laser for pigment correction of hypopigmented scars and striae alba. Arch Dermatol 2004;140:955–60. 34. Dover JS, Rothaus K, Gold MH. Evaluation of safety and patient subjective efficacy of using radiofrequency and pulsed magnetic fields for the treatment of striae (stretch marks). J Clin Aesthet Dermatol 2014;7:30–3. 35. Pasini A. Atrophoderma idiopathica progressiva. Gior Ital Derm Sif 1923;58:785. 36. Canizares O, Sachs PM, Jaimovich L, Torres VM. Idiopathic atrophoderma of Pasini and Pierini. Arch Dermatol 1958;77:42–60. 37. Kencka D, Blaszczyk M, Jablonska S. Atrophoderma Pasini-Pierini is a primary atrophic abortive morphea. Dermatology 1995;190:203–6. 38. Kang CY, Lam J. Congenital idiopathic atrophoderma of Pierini and Pasini. Int J Dermatol 2015;54:e44–6. 39. Buechner SA, Rufli T. Atrophoderma of Pasini and Pierini: clinical and histopathologic findings and antibodies to Borrelia burgdorferi in thirty-four patients. J Am Acad Dermatol 1994;30:441–6. 40. Saleh Z, Abbas O, Dahdah MJ, et al. Atrophoderma of Pierini and Pasini: a clinical and histopathological study. J Cutan Pathol 2008;35:1108–14. 41. Amano H, Nagai Y, Ishikawa O. Multiple morphea coexistent with atrophoderma of Pierini-Pasini (APP): APP could be abortive morphea. J Eur Acad Dermatol Venereol 2007;21:1254–6. 42. Yokoyama Y, Akimoto S, Ishikawa O. Disaccharide analysis of skin glycosaminoglycans in atrophoderma of Pasini and Pierini. Clin Exp Dermatol 2000;25:436–40. 43. Franck JM, Macfarlan D, Silvers ON, et al. Atrophoderma of Pasini and Pierini: atrophy of dermis or subcutis?   J Am Acad Dermatol 1995;32:122–3. 44. Berman A, Berman GD, Kinnkelmann RK. Atrophoderma (Pasini-Pierini): findings on direct immunofluorescent, monoclonal antibody, and ultrastructural studies. Int J Dermatol 1988;27:487–90.

45. Lee Y, Oh Y, Ahn SY, et al. A case of atrophoderma of Pasini and Pierini associated with Borrelia burgdorferi infection successfully treated with oral doxycycline. Ann Dermatol 2011;23:352–6. 46. Carter JD, Valeriano J, Vasey FB. Hydroxychloroquine as a treatment for atrophoderma of Pasini and Pierini. Int J Dermatol 2006;45:1255–6. 47. Arpey CJ, Patel DS, Stone MS, et al. Treatment of atrophoderma of Pasini and Pierini-associated hyperpigmentation with Q-switched alexandrite laser:   a clinical, histologic, and ultrastructural appraisal. Lasers Surg Med 2000;27:206–12. 48. Miescher G. Atypische Chondrodystrophie, Typus morquino kombiniert mit follikularer atrophodermie. Dermatologica 1944;89:38–51. 49. Curth HO. The genetics of follicular atrophoderma. Arch Dermatol 1978;114:1479–83. 50. Luria RB, Conologue T. Atrophoderma vermiculatum:   a case report and review of the literature on keratosis pilaris atrophicans. Cutis 2009;83:83–6. 51. Callaway SR, Lesher JL. Keratosis pilaris atrophicans: case series and review. Pediatr Dermatol 2004;21:14–17. 52. Handrick C, Alster T. Laser treatment of atrophoderma vermiculata. J Am Acad Dermatol 2001;44:693–5. 53. Torrelo A, Sprecher E, Medeiro IG, et al. What syndrome is this? Bazex-Dupré-Christol syndrome. Pediatr Dermatol 2006;23:286–90. 54. Parren LJ, Abuzahra F, Wagenvoort T, et al. Linkage refinement of Bazex-Dupré-Christol syndrome to an 11-4-Mb interval on chromosome Xq25-27.1. Br J Dermatol 2011;165:201–3. 55. Castori M, Castiglia D, Passarelli F, et al. Bazex-DupréChristol syndrome: an ectodermal dysplasia with skin appendage neoplasms. Eur J Med Genet 2009;52:250–5. 56. Hoang MP, Carder KR, Pandya AG, Bennettt MJ. Ichthyosis and keratotic follicular plugs containing dystrophic calcification in newborns: distinctive histopathologic features of X-linked dominant chondrodysplasia punctata (Conradi-HünermannHapple syndrome). Am J Dermatopathol 2004;26:53–8. 57. Canueto J, Giros M, Ciria S, et al. Clinical, molecular and biochemical characterization of nine Spanish families with Conradi-Hünermann-Happle syndrome: new insights into X-linked dominant chondrodysplasia punctata with a comprehensive review of the literature. Br J Dermatol 2012;166:830–8. 58. Heidingsfeld ML. Atrophia maculosa varioliformis cutis. J Cutan Dis 1918;36:285–8. 59. Kuflik JH, Schwartz RA, Becker KA, Lambert WC. Atrophia maculosa varioliformis cutis. Int J Dermatol 2005;44:864–6. 60. Shelley WB, Rawnsley JM. Painful feet due to herniation of fat. JAMA 1968;205:308–9. 61. Greenberg S, Krafchik BR. Infantile pedal papules. J Am Acad Dermatol 2005;53:333–4. 62. Laing VB, Fleischer AB Jr. Piezogenic wrist papules: a common and symptomatic finding. J Am Acad Dermatol 1991;24:415–17.

DISORDERS OF SUBCUTANEOUS FAT SECTION 16

Panniculitis James W. Patterson and Luis Requena

Chapter Contents

Predominantly septal panniculitis

Morphea/scleroderma panniculitis . . . . . . . . . . . . . . . . . . . 1738



Erythema induratum . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1740 Pancreatic panniculitis . . . . . . . . . . . . . . . . . . . . . . . . . . . 1742 Sclerema neonatorum, subcutaneous fat necrosis of the newborn, and post-steroid panniculitis . . . . . . . . . . . . . . . 1743 Lupus erythematosus panniculitis (lupus panniculitis) . . . . . . 1746 Panniculitis of dermatomyositis . . . . . . . . . . . . . . . . . . . . . 1747 Traumatic panniculitis . . . . . . . . . . . . . . . . . . . . . . . . . . . 1748 Lipodermatosclerosis . . . . . . . . . . . . . . . . . . . . . . . . . . . 1749 Infection-induced panniculitis . . . . . . . . . . . . . . . . . . . . . . 1752 Cytophagic histiocytic panniculitis . . . . . . . . . . . . . . . . . . . 1753 Malignant subcutaneous infiltrates . . . . . . . . . . . . . . . . . . 1753 Unusual or newly described forms of panniculitis . . . . . . . . . 1753

INTRODUCTION Panniculitis is a diagnostically challenging arena for dermatologists and pathologists. Terminology is difficult, partly because various names have been applied to the same disorder (e.g. nodular vasculitis and erythema induratum), and partly because new discoveries have resulted in the introduction of new terms and the abandonment of others. From a clinical standpoint, many forms of panniculitis with diverse etiologies closely resemble one another, presenting as tender, erythematous, subcutaneous nodules. Some panniculitides can be a manifestation of different disease processes (erythema nodosum is the classic example), and, even if the type of panniculitis is correctly identified, this is only the first step in a series of investigations required to determine the underlying cause. From a pathologic standpoint, the subcutaneous fat responds to a variety of different insults in a limited number of ways, and, therefore, histopathologic differences among the various forms of panniculitis may be subtle. Management can also be difficult, since there are often at least two therapeutic desiderata: specific treatment of the panniculitis treatment of the underlying illness. In this chapter, these issues will be addressed by introducing a schema for the classification of these disorders, recommending an approach to the histopathologic diagnosis, and providing information about the specific forms of panniculitis and their management. Table 100.1 provides a working classification for the multiple forms of panniculitis. The categories are determined partly by clinical characteristics such as anatomic location (Fig. 100.1), partly by histopathology, and partly by etiology. A word should be said about septal versus lobular panniculitis. These are largely artificial constructs, since there is no purely septal or purely lobular panniculitis. Certain forms of panniculitis can be characterized as having predominantly septal involvement, and this finding can provide a useful clue to diagnosis when combined with other clinical and histopathologic features.

• •

CLASSIFICATION OF THE PANNICULITIDES

Erythema nodosum . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1733 Alpha-1 antitrypsin deficiency panniculitis . . . . . . . . . . . . . . 1738

100 

Erythema nodosum Erythema nodosum migrans (subacute nodular migratory panniculitis) • Panniculitis of morphea/scleroderma • Alpha-1 antitrypsin deficiency panniculitis *

Lobular and mixed septal–lobular panniculitis With vasculitis involving septal veins or arteries, lobular venules or small veins Erythema induratum (nodular vasculitis) • With necrosis as an early finding Pancreatic panniculitis • With needle-shaped clefts within lipocytes Sclerema neonatorum Subcutaneous fat necrosis of the newborn Post-steroid panniculitis • Associated with autoimmune connective tissue disease Lupus erythematosus panniculitis (lupus profundus) Panniculitis of dermatomyositis • Lipodystrophic panniculitis (see Ch. 101) Lipoatrophy Lipohypertrophy • Traumatic panniculitis, including factitial panniculitis Cold panniculitis (popsicle panniculitis, Haxthausen disease) Sclerosing lipogranuloma (including grease gun granuloma) Panniculitis due to other injectable substances Panniculitis due to blunt trauma • Lipodermatosclerosis • Infection-induced panniculitis • Malignancy-related panniculitis-like infiltrates Subcutaneous panniculitis-like T-cell lymphoma (see Ch. 120) Other lymphomas with involvement of subcutaneous tissues •

*Descriptions vary; some authors regard this as a lobular or mixed septal–lobular panniculitis.

Table 100.1 Classification of the panniculitides. The categories for classification of panniculitis are determined partly by clinical characteristics such as location and associated diseases and partly by histopathology. This classification scheme does not include Weber–Christian disease as cases initially assigned this designation have subsequently been reclassified as other forms of panniculitis, including alpha-1 antitrypsin deficiency, lipodermatosclerosis, lupus panniculitis, and traumatic panniculitis.  

Table 100.2 provides an approach to the histopathologic diagnosis of an unknown case of panniculitis. When performing a biopsy in a patient with panniculitis, it is absolutely critical that the specimen includes a generous portion of subcutaneous fat. Therefore, excisional biopsies extending through the subcutis or narrow incisional biopsies that incorporate a broad expanse of subcutaneous fat are preferable to punch biopsies.

ERYTHEMA NODOSUM Synonyms:  ■ Erythema contusiformis ■ Erythema nodosum migrans (variant form)

1733

Panniculitis represents infiltration of the subcutaneous tissue by inflammatory cells, although the term has also been applied to neoplastic infiltration. Typically there is deep induration or swelling of the skin, accompanied by erythema, warmth, pain, and sometimes ulceration or drainage. Occasionally, induration or nodularity may be present without significant inflammation clinically or these changes may persist after inflammation has abated. There are numerous causes of panniculitis and given the overlap in clinical and pathologic features, findings are not always diagnostic of a particular entity. That said, there is a group of primary panniculitides, each of which has recognizable clinical, histopathologic and/or laboratory features that in general point to a specific diagnosis and targeted therapeutic approaches. These conditions comprise the subject of this chapter.

CHAPTER

100

panniculitis, subcutis, erythema nodosum, erythema induratum, alpha-1 antitrypsin deficiency panniculitis, connective tissue panniculitis, pancreatic panniculitis, sclerema neonatorum, subcutaneous fat necrosis of the newborn, post-steroid panniculitis, lupus panniculitis, traumatic panniculitis, lipodermatosclerosis, infection-induced panniculitis, factitial disease

Panniculitis

ABSTRACT

non-print metadata KEYWORDS:

1733.e1 AU_form_BS

SECTION

MOST COMMON LOCATIONS FOR SEVERAL FORMS OF PANNICULITIS

Disorders of Subcutaneous Fat

16

Erythema nodosum

Erythema induratum

Lipodermatosclerosis

Lupus panniculitis

Alpha-1 antitrypsin deficiency panniculitis

Fig. 100.1 Most common locations for several forms of panniculitis. Classification of panniculitis depends upon multiple factors, including clinical characteristics such as location and ulceration as well as histopathology and etiology.  

Key features ■ Tender, erythematous, subcutaneous nodules ■ Usually distributed symmetrically and favor the pretibial areas; occasionally occur elsewhere ■ In later stages, lesions acquire a bruise-like appearance ■ May be accompanied by fever, arthralgias and malaise ■ Associated with a wide variety of systemic disorders

Introduction Erythema nodosum is the best known of the various forms of panniculitis, as well as the most common. It typically presents as an acute eruption of tender, erythematous, subcutaneous nodules in the pretibial areas bilaterally. It is widely regarded as a delayed hypersensitivity response to a variety of antigenic challenges1, although the mechanisms of its development are more complex than this statement would indicate. Histopathologically, it is the prototype of a “septal” panniculitis. Identification and treatment of the underlying disorder, if found, is of primary importance, but therapy directed toward the lesions themselves is also an option, especially when idiopathic.

History At the beginning of the eighteenth century, Robert Willan gave the first clear description of erythema nodosum, and he provided its name in his famous work, On Cutaneous Disease2,3.

Epidemiology

1734

Erythema nodosum can occur at any age, in both sexes, and in all racial groups. It is more common among women and is more frequently observed during the second through fourth decades of life4,5. The relative ranking of underlying causes may vary according to geographic location; for example, in areas where Coccidioides immitis is endemic or regions where Behçet disease is more prevalent.

Pathogenesis Erythema nodosum has been considered a delayed hypersensitivity response to a variety of antigenic stimuli, including bacteria, viruses and chemical agents1,6. Llorente et al.7 observed expression of mRNA for Th1 cytokines (interferon-γ, interleukin-2) in the skin lesions and peripheral blood of patients with erythema nodosum, and a Th1 pattern of cytokine synthesis is associated with delayed-type hypersensitivity reactions. However, a complex series of intermediate steps is involved in the development of these lesions. A variety of adhesion molecules and inflammatory mediators appear to be associated with erythema nodosum. For example, in erythema nodosum lesions, vascular cell adhesion molecule-1 (VCAM-1; CD106), platelet endothelial cell adhesion molecule-1 (PECAM-1; CD31), HLA-DR and E-selectin are expressed on endothelial cells, while intercellular adhesion molecule-1 (ICAM-1; CD54), very late antigen-4 (VLA-4), L-selectin and HLA-DR are expressed by inflammatory cells (see Ch. 102)8. Neutrophils are often numerous in early lesions, and it has been shown that a higher percentage of circulating neutrophils in patients with erythema nodosum leads to the production of reactive oxygen intermediates; these intermediates, in turn, may provoke inflammation and tissue damage9. Support for a pathogenic role for these cells and molecules is provided by studies on the effects of colchicine10. This inhibitor of neutrophil chemotaxis has been shown to diminish L-selectin expression on the neutrophil surface, inhibit E-selectinmediated endothelial adhesiveness for neutrophils, and diminish stimulated expression of ICAM-1 on the endothelium8. Additional indirect evidence for the role of inflammatory cells and mediators includes reports of erythema nodosum following treatment with granulocyte colony-stimulating factor11, and improvement (as well as flares) of erythema nodosum lesions with administration of tumor necrosis factor (TNF) inhibitors12. Erythema nodosum, especially in its chronic phase, is characterized by granuloma formation and TNF is known to play a role in granuloma formation. A link between deregulation of TNF-α production and granuloma formation is further supported by the strong correlation of a polymorphism in the promoter region of the gene that encodes TNF-α and the development of sarcoidosis-associated erythema nodosum13. A wide range of precipitating factors has been linked with erythema nodosum. Infectious causes are common, particularly upper respiratory infections (both streptococcal and non-streptococcal). Other commonly reported causes are listed in Table 100.34,5,14,14a,14b.

Clinical features Erythema nodosum presents with bilateral, tender, erythematous nodules. These arise in crops and clearly the most common site is the shins (Fig. 100.2). Other locations are occasionally involved, particularly the thighs and forearms4. Nodules may also appear on the trunk, neck and face3, but this is sufficiently rare that development of lesions in these locations should prompt consideration of other diagnoses. Unlike other forms of panniculitis, ulceration is not a feature of erythema nodosum. Systemic symptoms may occur that are not necessarily related to a specific coexisting systemic disorder; these include arthritis, arthralgia, fever and malaise3. Because of its close association with a variety of disorders and infections, erythema nodosum is an important skin sign of systemic disease. For example, its development may precede or accompany a flare of inflammatory bowel disease15. It may also have some value as a prognostic indicator in certain disorders. For example, erythema nodosum is associated with a protective effect against disseminated disease in patients with coccidioidomycosis, and it is closely aligned with a more benign and self-limited form of sarcoidosis1,16. Nevertheless, a significant percentage of cases – more than one-third – have no known disease association, even when followed for a year or more5. Clinical or laboratory data that tend to predict that the development of erythema nodosum may be secondary to a systemic disease are listed in Table 100.4. Erythema nodosum lesions usually last a few days or weeks and then slowly involute, without scar formation. Discoloration suggestive of a bruise may be seen as the erythema subsides. More chronic forms do occur, some of which show a tendency toward migration or centrifugal spread; the latter have been termed subacute nodular migratory panniculitis or erythema nodosum migrans (see below). Up to one-third of

CHAPTER

Histopathologic aspects to consider

Conclusions

Look for the “center of gravity” of the infiltrate

Recommended originally by Pinkus, the purpose is to determine whether or not the inflammatory process is centered in the subcutis (favoring a primary panniculitis), in the dermis, or in the fascia (in which case the panniculitis may be a secondary manifestation of a deeper inflammatory process)

Determine if the panniculitis is predominantly septal, predominantly lobular, or mixed

Generally, a predominantly septal panniculitis narrows the diagnostic considerations (see Table 100.1). If the panniculitis is lobular or mixed, look for other distinguishing features

Determine if there is vasculitis involving a medium-sized vessel, in the face of a lobular or mixed panniculitis

This is characteristic of erythema induratum (nodular vasculitis); caveat: deeper levels are often required in order to demonstrate the involvement of vessels

Look for fat necrosis with saponification and “calcium soap” formation

This is a feature of pancreatic panniculitis

Look for needle-shaped clefts within lipocytes

Their presence favors a diagnosis of sclerema neonatorum, subcutaneous fat necrosis of the newborn, or post-steroid panniculitis

Determine if the panniculitis has a lymphoplasmacytic predominance

This tends to be a feature of panniculitis due to connective tissue disease, including lupus erythematosus; beware of lymphocytic predominance in cases of subcutaneous panniculitis-like T-cell lymphoma (see Table 100.9)

Check for a “central nidus” of inflammation or evidence of a needlestick injury. Look for vacuolated spaces or foreign material

These are clues to traumatic panniculitis including factitial panniculitis. Polarization microscopy can be helpful

Determine if lobular panniculitis has a predominance of neutrophils

Infection-induced panniculitis, neutrophilic panniculitis associated with inflammatory bowel disease and rheumatoid arthritis, subcutaneous Sweet syndrome, traumatic panniculitis; less so in alpha-1 antitrypsin deficiency panniculitis and pancreatic panniculitis

Look for membranocystic changes in the subcutis

This change is characteristic of (though not pathognomonic for) lipodermatosclerosis; it can be observed in any panniculitis with prominent degenerative changes

Determine if the panniculitis is associated with substantial cellular necrosis, vascular proliferation, hemorrhage, sweat gland necrosis, or neutrophilic aggregates

These changes are often encountered in infection-induced panniculitis. Tissue cultures and special stains for organisms may be indicated

Determine if the infiltrating cells are particularly monotonous or atypical in appearance

Consider subcutaneous panniculitis-like T-cell lymphoma and other lymphomas with involvement of the subcutaneous fat. Rarely, non-hematologic malignancies mimic panniculitis. Immunohistochemical stains are mandatory for a precise diagnosis

Determine if there are large cells with cytophagic activity

Cytophagic activity (hemophagocytosis) observed primarily in subcutaneous infiltrates of primary cutaneous γ/δ T-cell lymphoma. This finding was previously termed “cytophagic histiocytic panniculitis”

Panniculitis

100

AN APPROACH TO THE HISTOPATHOLOGIC DIAGNOSIS OF PANNICULITIS

Table 100.2 An approach to the histopathologic diagnosis of panniculitis.  

Fig. 100.2 Erythema nodosum – clinical appearance. A Erythematous, tender nodules bilaterally on the shins and dorsal feet; the patient is pregnant. B The nodules and plaques may develop a bruise-like appearance. A, Courtesy,  

Ian Odell, MD, PhD; B, Courtesy, Kalman Watsky, MD.

A

cases of erythema nodosum recur. Annual recurrences are particularly common among idiopathic cases14.

Pathology Erythema nodosum is the prototypic septal panniculitis (Fig. 100.3), but this should not be taken to imply that histopathologic changes are entirely confined to subcutaneous septa17. Biopsy specimens of early lesions tend to show edematous septa and mild lymphocytic infiltrates. Of note, neutrophils may predominate in early lesions8, and a variant with a predominance of eosinophils has been reported18,19. True vasculitis of the type seen in leukocytoclastic vasculitis is not observed, and

B

erythema nodosum is not generally regarded as a vasculitic process. However, “secondary” vasculitis may be observed in lesions when they contain relatively heavy, mixed, or neutrophil-rich inflammatory infiltrates. Erythema nodosum-like lesions in Behçet disease may demonstrate leukocytoclastic or lymphocytic vasculitis involving subcutaneous venules or muscular veins; the latter changes are prone to occur in patients with more severe forms of Behçet disease20. In early lesions, one may also find Miescher microgranulomas, a characteristic if not pathognomonic feature of erythema nodosum. These are small collections of macrophages, found within septa or at a septal–lobular interface, that tend to surround neutrophils or small

1735

SECTION

Disorders of Subcutaneous Fat

16

CAUSES OF ERYTHEMA NODOSUM

Incidence

Cause

Comments

Most common

Idiopathic

Still the largest single category, accounting for a third to a half of cases

Streptococcal infections, especially of the upper respiratory tract

The largest single infectious cause

Other infections: Viral upper respiratory tract infections Bacterial gastroenteritis – Yersinia > Salmonella, Campylobacter

Overall, infection may account for a third or more of cases

Coccidioidomycosis

Erythema nodosum is associated with a lower incidence of disseminated disease

Drugs*

Especially estrogens and oral contraceptive pills; also sulfonamides, penicillin, bromides, iodides; occasionally, TNF inhibitors, BRAF inhibitors^

Sarcoidosis**

10–20% of cases in some series

Inflammatory bowel disease

Crohn disease has a stronger association with erythema nodosum than does ulcerative colitis

Uncommon

Infections: Brucella melitensis Chlamydophila† pneumonia Chlamydia trachomatis Mycoplasma pneumoniae Mycobacterium tuberculosis Histoplasma capsulatum Hepatitis B virus‡ Neutrophilic dermatoses: Behçet disease Sweet syndrome

“Erythema nodosum” in Behçet disease more closely resembles erythema induratum (nodular vasculitis)

Acne fulminans, including isotretinoin-associated Pregnancy Pernicious anemia

Rare

Diverticulitis Infections: Neisseria gonorrhoeae, N. meningitidis Escherichia coli, Bartonella henselae, Bordetella pertussis Treponema pallidum Dermatophytes (kerion), Blastomyces dermatitidis HIV Giardiasis, amoebiasis (abscesses)

Erythema nodosum leprosum is a different disease that is characterized by a cutaneous small vessel vasculitis

MonoMAC syndrome (GATA2 mutations) Malignancy, most often acute myelogenous leukemia, Hodgkin disease

May overlap with Sweet syndrome

Lupus erythematosus

One of several forms of panniculitis reported in LE, in addition to lupus panniculitis

*To be distinguished from panniculitis that can develop at sites of injection of medications, e.g. glatiramer acetate, interferon-β, phytonadione (vitamin K), interleukin-2, heparin (eosinophilic panniculitis), pentazocine, vaccines (e.g. tetanus).

Löfgren syndrome is an acute, spontaneously resolving form of sarcoidosis characterized by erythema nodosum, hilar lymphadenopathy, fever, polyarthritis and uveitis. ** ^ Also lobular neutrophilic panniculitis.

†Previously referred to as Chlamydia. ‡Erythema nodosum secondary to the hepatitis B vaccine has also been reported.

Table 100.3 Causes of erythema nodosum. LE, lupus erythematosus; TNF, tumor necrosis factor.  

FINDINGS SUGGESTIVE OF A SYSTEMIC CAUSE FOR ERYTHEMA NODOSUM Synovitis Diarrhea* • Abnormal chest X-ray • Preceding upper respiratory tract infection • Elevated antistreptolysin O and/or anti-DNase B titers • Positive tuberculin skin test or interferon-gamma release assay (e.g. QuantiFERON®-TB Gold In-Tube test, T-SPOT®.TB test) • •

*Check for fecal white blood cells and stool culture for bacteria and, if indicated, ova and parasites.

1736

Table 100.4 Findings suggestive of a systemic cause for erythema nodosum. Additional evaluation can include viral hepatitis panel and in women of child-bearing age, serum β-human chorionic gonadotropin.  

cleft-like spaces3. Reported variations in the frequency of these granulomas in erythema nodosum3,21 may result in part from differences in definition, in the acceptance of subtle changes, and in the rigor of the search. In older lesions, Miescher microgranulomas may feature epithelioid and multinucleated giant cells (Fig. 100.3, inset). As lesions progress, the septa become widened and contain a mixed, partly granulomatous infiltrate. These cells infiltrate the periphery of fat lobules in a lace-like configuration. The extent of lobular involvement may vary, and in some cases can be prominent8. Nevertheless, in the case of a lobular panniculitis without the characteristic septal changes, a diagnosis of erythema nodosum should be made with caution. Frequently, there is also a mild to moderate perivascular lymphocytic infiltrate in the overlying dermis. In later stages, the septa become fibrotic, partially replacing the fat lobules. Residual granulomas and lipophages can be observed, and a degree of vascular proliferation

CHAPTER



Cerrroni, MD.

TREATMENT RECOMMENDATIONS FOR ERYTHEMA NODOSUM In all patients

Discontinue possible causative medications Diagnose and treat underlying cause Bed rest and leg elevation Compression

First-line

Nonsteroidal anti-inflammatory medications (3)* Salicylates Potassium iodide (2) (see Table 100.6)

Second-line**

Colchicine (3)# Infliximab (3)## Hydroxychloroquine (3)^ Adalimumab (3)^ Etanercept Mycophenolate mofetil (3)

Third-line**

Systemic corticosteroids (3) Thalidomide (3)^^ Cyclosporine (3) Dapsone (3)

100 Panniculitis

Fig. 100.3 Erythema nodosum – histopathologic features. A predominantly septal panniculitis with Miescher microgranulomas within the septa. Note the multinucleated giant cells (inset). Courtesy, Lorenzo

*May trigger a flare of inflammatory bowel disease. **Immunosuppressives to be used only if underlying infection has been excluded and/or treated.

#Helpful for erythema nodosum associated with Behçet disease. ##Helpful for erythema nodosum associated with inflammatory bowel disease. ^Helpful for chronic erythema nodosum. ^^May transiently exacerbate erythema nodosum associated with Behçet disease.

Table 100.5 Treatment recommendations for erythema nodosum. Key to evidence-based support: (1) prospective controlled trial; (2) retrospective study or large case series; (3) small case series or individual case reports.  

may be present3. Over the long term, a remodeling process takes place that usually results in minimal residual scarring3.



Differential diagnosis The clinical scenario of an acute eruption of tender subcutaneous nodules over both shins of a young person is highly characteristic of erythema nodosum. However, when lesions are few in number, are located in sites other than the lower legs, or are of longer duration (>6 weeks), erythema nodosum can be difficult to distinguish from other forms of panniculitis. Lesions of erythema induratum (nodular vasculitis) can resemble those of erythema nodosum, but they tend to occur on the posterior aspect of the lower legs and may ulcerate. Ulceration is also a feature of pancreatic panniculitis, which occurs more frequently in other locations (although still favoring the lower legs), is more likely to be accompanied by arthritis and serositis, and is associated with elevated serum amylase and lipase levels. Histopathologically, the picture of a predominantly septal panniculitis usually limits the differential diagnosis and tends to exclude those conditions that are chiefly lobular or mixed. Pancreatic panniculitis may show predominantly septal changes in its earliest stages22, but eventually, these lesions exhibit the characteristic fat necrosis, with saponification and “ghost cell” formation. Infectioninduced panniculitis can sometimes mimic erythema nodosum, but there are often more extensive neutrophilic infiltrates, cellular necrosis (including sweat gland necrosis), vascular proliferation, and hemorrhage23.

Treatment Treatments most often recommended for uncomplicated erythema nodosum include bed rest, salicylates, and nonsteroidal antiinflammatory drugs (NSAIDs; Table 100.5)2,15. Potassium iodide has been used with success, with adult dosages ranging from 450 to 1500 mg/day (Table 100.6)24. Improvement can be seen within 2 weeks. Potassium iodide may work through inhibition of cell-mediated immunity, as well as via inhibition of neutrophil chemotaxis and suppression of neutrophil-generated oxygen intermediates2. In light of this treatment response, reports of erythema nodosum triggered by potassium iodide seem contradictory. Treatment of erythema nodosum is influenced by underlying conditions. Thus, colchicine is useful in management of erythema nodosum that accompanies Behçet disease8. Various treatments for inflammatory bowel disease are also effective in managing coexistent erythema nodosum12,25. Both etanercept and infliximab have been reported to be

USE OF POTASSIUM IODIDE (KI)

Saturated solution of potassium iodide (SSKI) 1000 mg/ml Droppers are supplied with calibrations for: 0.3 ml (300 mg)* 0.6 ml (600 mg) • In adults and older children, common dose = 300 mg TID po with starting dose = 150–300 mg TID • In infants and young children, common dose = 150 mg TID po • SSKI should be diluted in water or juice to try to minimize the bitter aftertaste • Crystallization may occur with cold temperatures, but rewarming and shaking dissolves the crystals; discard if solution turns yellow–brown • •

Side effects of SSKI Acute – nausea, bitter eructation, excessive salivation, urticaria, angioedema, cutaneous small vessel vasculitis • Chronic – enlargement of salivary and lacrimal glands, acneiform eruption, iododerma, hypothyroidism, hyperkalemia, occasionally hyperthyroidism •

*0.3 ml = 10 drops from the calibrated dropper supplied with SSKI. Table 100.6 Use of potassium iodide (KI).  

effective in treating erythema nodosum25,26, but paradoxically both have been noted to produce erythema nodosum as a cutaneous side effect27,28. In case reports, adalimumab has led to improvement of refractory chronic erythema nodosum29. Additional systemic therapies are listed in Table 100.5.

Subacute Nodular Migratory Panniculitis Synonyms:  ■ Erythema nodosum migrans ■ Chronic erythema

nodosum

1737

SECTION

Disorders of Subcutaneous Fat

16

Fig. 100.4 Morphea panniculitis. Septal thickening, mucin deposition and mild lymphocytic infiltrate. Lymphoplasmacytic infiltrates concentrate at the dermal– subcutaneous interface (inset). Courtesy, Lorenzo

Key features



■ Nodules on the lower extremities that migrate or undergo centrifugal spread, with central clearing ■ Often unilateral ■ Most cases are idiopathic; occasionally associated with streptococcal infection or thyroid disease ■ More chronic course than typical erythema nodosum

Cerrroni, MD.

Clinical features This condition was first described by Bafverstedt in 195430 and was named subacute nodular migratory panniculitis by Vilanova and Piñol Aguade in 195631. Some of its clinical and microscopic characteristics are similar to chronic erythema nodosum, and it is believed by many to represent a variant of the latter3,30. However, others consider it to be a separate disorder32. Subacute nodular migratory panniculitis is seen predominantly in women, is often unilateral, and is characterized by nodules that migrate or expand in a centrifugal manner (with central clearing)3 and may assume a yellowish or morpheaform appearance33. Lesions tend to be less tender than those of classic erythema nodosum. There may be few, if any, associated systemic symptoms30, though arthralgias have been reported and the ESR may be elevated31. Most cases are idiopathic, but some are associated with streptococcal infection (as evidenced by elevated antistreptolysin O and anti-DNase B titers) or thyroid disease32.

Pathology Microscopically, the changes are those of a chronic septal panniculitis33. However, in contrast to more classic forms of chronic erythema nodosum, subacute nodular migratory panniculitis shows greater septal thickening, more prominent granulomatous inflammation along the borders of widened subcutaneous septa, absence of phlebitis, and rare hemorrhage32.

Treatment Untreated, subacute nodular migratory panniculitis can last for months or years. However, treatment with potassium iodide is usually effective, resulting in clearing of lesions within several weeks33.

outlined above is more difficult, requiring clinical data for accurate classification. Sclerosis with lesser degrees of subcutaneous inflammation characterizes scleroderma, while a predominance of fascial involvement with extension into the subcutis is more typical of eosinophilic fasciitis.

ALPHA-1 ANTITRYPSIN DEFICIENCY PANNICULITIS

MORPHEA/SCLERODERMA PANNICULITIS (See also Chs 43 & 44.)

Synonym:  ■ Alpha-1 protease (proteinase) deficiency panniculitis

Clinical features Both morphea and scleroderma (systemic sclerosis) can affect the subcutaneous fat (Table 100.7), which is the primary site of involvement in deep morphea (morphea profunda)34. Subcutaneous extension also occurs in variants such as disabling pansclerotic morphea of childhood, generalized morphea, and linear morphea. In addition, eosinophilic fasciitis can involve the subcutaneous fat as well as the fascia35. These syndromes may be associated with peripheral eosinophilia, polyclonal gammopathy, and serologic abnormalities35,36. Fleischmajer et al.37 proposed that the sclerosing process in scleroderma is initiated by the changes that take place in the subcutis.

Key features ■ Erythematous, painful, subcutaneous nodules or plaques that often ulcerate and drain ■ Associated with alpha-1 antitrypsin deficiency; patients with the most severe disease are homozygotes for the Z allele of the SERPINA1 gene (PiZZ) ■ A characteristic histologic finding is liquefactive necrosis of the dermis and subcutaneous septa, but lobular or mixed septal– lobular changes with neutrophils may occur

Pathology Table 100.7 outlines the microscopic changes in morphea- and scleroderma-associated septal panniculitis (Fig. 100.4). Lymphocytes and plasma cells predominate35,38,39, although macrophages and eosinophils may be present. In some cases, the number of plasma cells is striking38. In late stages of morphea, the subcutis is largely replaced by hyalinized connective tissue, very often accompanied by changes of lipoatrophy.

Differential diagnosis 1738

The combination of septal panniculitis with lymphoplasmacytic predominance and dermal and subcutaneous sclerosis is unique, and this helps to separate morphea/scleroderma panniculitis from other septal forms of panniculitis. Differentiation among the several variants

Introduction Alpha-1 antitrypsin deficiency is a well-established, but uncommon, cause of panniculitis. The most severely affected individuals, with markedly decreased levels of the protease inhibitor, are most prone to the development of ulcerating neutrophilic panniculitis. Recognition of the disorder is important not only in the selection of appropriate therapy, but also in addressing other systemic manifestations of the disease and in dealing with its genetic aspects.

History Alpha-1 antitrypsin deficiency is an inborn error of metabolism that was first delineated by Eriksson and others in the early 1960s40. In

CHAPTER

Disorder

Clinical presentation

Lesion distribution

Relation to systemic disease

Histopathology of panniculitis

Morphea and scleroderma (systemic sclerosis)

Indurated plaques

Extremities, trunk

Occurs in scleroderma, but usually more pronounced in morphea

Septal, with thickening and sometimes mucin deposition; inflammation especially at dermal–subcutaneous interface; lymphocytes and plasma cells; lymphoid follicles in morphea*

Lupus panniculitis

Tender subcutaneous nodules and plaques; may have overlying lesions of discoid LE

Face (especially cheeks), upper arms, shoulders, hips, buttocks, breasts, trunk

Only minority of patients have associated systemic LE

Lobular or mixed lobular/septal; mucin deposition; hyaline necrosis of lobules; lymphocytes and plasma cells, sometimes with prominent nuclear dust; nodular lymphocytic aggregates or lymphoid follicles

Dermatomyositis

Indurated, painful plaques and nodules; may ulcerate

Buttocks, abdomen, thighs, arms

Can arise in patients with established dermatomyositis or precede other disease manifestations

Lobular or mixed septal/lobular; fat necrosis; lipomembranous changes; sometimes calcification; lymphocytes and plasma cells; sometimes nodular lymphocytic aggregates

Annular atrophic connective tissue panniculitis of the ankles

Subcutaneous atrophy, which may be preceded by induration and tenderness

Circumferential bands around the ankles

Patients often have antinuclear antibodies and/or autoimmune conditions such as thyroiditis or rheumatoid arthritis

Lobular or mixed septal/lobular lymphohistiocytic panniculitis with areas of fat necrosis

Atrophic connective tissue panniculitis

Erythematous, indurated plaques that resolve with subcutaneous atrophy

Favors extremities; may be widespread

As above

As above

Panniculitis

100

CLINICAL AND MICROSCOPIC FEATURES OF CONNECTIVE TISSUE PANNICULITIS

*Less often than in lupus panniculitis. Table 100.7 Clinical and microscopic features of connective tissue panniculitis. Based on references 35, 37, 38, 105 and 183. LE, lupus erythematosus.  

1972, Warter and colleagues identified members of a family with alpha-1 antitrypsin deficiency and “Weber–Christian syndrome”. Subsequent investigations linked the clinical and microscopic findings to known effects of proteinase inhibitor deficiency.

Epidemiology No apparent racial or geographic prevalence has been noted for alpha-1 antitrypsin deficiency panniculitis. The incidence of the disease is approximately equal in men and women41,42. Age of onset ranges from infancy to the eighth decade of life42.

Pathogenesis Alpha-1 antitrypsin, a glycoprotein produced in the liver, is the most abundant circulating serine protease inhibitor (serpin). The more than 120 different alleles of the gene that encodes this protein (SERPINA1; formerly known as PI) are divided into categories based upon the electrophoretic mobility of their protein products (M = medium, S = slow, Z = very slow). The most common protease inhibitor (Pi) phenotype is MM (homozygous for M alleles), which is associated with normal serum levels of alpha-1 antitrypsin (100–200 mg/dl)43. Heterozygotes with one copy of the S or Z allele have mild to moderate deficiencies of the inhibitor (PiMS and PiMZ; prevalences of 1–3% in Caucasian populations). Patients who are homozygous for the Z allele (PiZZ; prevalence of 1 : 150–1 : 5000 in Caucasian populations) or whose genotype is the rare PiZnull have severe alpha-1 antitrypsin deficiency, with serum levels in the range of 20–45 mg/dl. In these individuals, most of the aberrant alpha-1 antitrypsin protein accumulates in the endoplasmic reticulum of hepatocytes, and the small amounts that enter the circulation have decreased function and a tendency to form inactive polymers that may stimulate neutrophil chemotaxis44. Of note, Z-type polymers have been detected in the skin of a patient with alpha-1 antitrypsin deficiency panniculitis, further suggesting a possible proinflammatory role45. Alpha-1 antitrypsin acts upon a wide range of proteolytic enzymes that play a direct role in degradation of tissues, including trypsin,

collagenase, and elastase46. It also has important effects on immune function, e.g. inhibition of membrane-bound serine proteases involved in the activation of lymphocytes and macrophages47. It may also inhibit complement activation, both through a direct effect on complementrelated proteases48 and by inhibiting the neutrophil proteases that activate enzymes of the complement system49. In addition to panniculitis, the consequences of alpha-1 antitrypsin deficiency include chronic liver disease with cirrhosis (resulting from retention of the aberrant protein within the liver), emphysema, pancreatitis, membranoproliferative glomerulonephritis, rheumatoid arthritis, c-ANCA (cytoplasmic antineutrophil cytoplasmic antibody)-positive vasculitis, other cutaneous vasculitides such as Henoch-Schönlein purpura, and angioedema (resulting from deficiency of the protease inhibitor)41,49. The initiating event in individuals who develop panniculitis is not always clear; trauma appears to play a role in some patients. Postpartum flares of the disease have been reported in genetically susceptible individuals. This is attributed to the estrogen-promoted increase in proteinase inhibitor levels during pregnancy, followed by a precipitous decline to subnormal levels postpartum50. Absence of the alpha-1 antitrypsin protease inhibitor results in activation of lymphocytes and macrophages, lack of restraint upon the complement cascade, release of chemotactic factors, accumulation of neutrophils with release of their proteolytic enzymes, and consequent attack upon fat and nearby connective tissues44,46. The subcutis may be particularly vulnerable to this process, since fatty acids make nearby elastin more susceptible to proteolytic degradation49.

Clinical features Large, erythematous to purpuric, tender nodules or plaques appear in a variety of sites (Fig. 100.5), especially the lower trunk and proximal extremities (flanks, buttocks and thighs)41,44,46. Ulcers develop that may be deep and necrotic, accompanied by an oily discharge42,44,46. Migration of lesions has been reported41. A history of antecedent trauma can be elicited in approximately one-third of patients42. Panniculitis may be accompanied by fever, pleural effusions and pulmonary emboli42. The clinical course of the panniculitis is often prolonged, and

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16

Fig. 100.5 Alpha-1 antitrypsin deficiency panniculitis – clinical appearance. Purpuric nodules on the ankle.

Disorders of Subcutaneous Fat



Courtesy, Kenneth E Greer, MD.

Fig. 100.6 Alpha-1 antitrypsin deficiency panniculitis – histopathologic features. Predominantly septal involvement is seen, with inflammation and collagenolysis of fibrous septa.  

lesions are resistant to immunosuppressive therapy. Healing is accompanied by scarring and subcutaneous atrophy42. The most severe manifestations arise in those with profound proteinase inhibitor deficiency (PiZZ), although the panniculitis can also occur in heterozygotes41.

Pathology Descriptions of the pathology of alpha-1 antitrypsin deficiency panniculitis have varied. Early, there is a neutrophilic panniculitis, followed rapidly by necrosis and destruction of fat lobules46. Splaying of neutrophils between collagen bundles in the reticular dermis has been described as an early clue to the diagnosis51. Dissolution of dermal collagen, with resultant liquefactive necrosis and separation of fat lobules from adjacent septa, is a principal change in most cases52. Another characteristic feature is the presence of “skip areas” of normal fat adjacent to foci of severe necrotizing panniculitis46. Chronic inflammation and hemorrhage may be present at the periphery of areas of involvement46. Most authors have not found evidence for primary leukocytoclastic vasculitis, although there may be evidence for lymphocytic vasculitis, secondary vasculitis in areas of heavy neutrophilic infiltration, or thrombosis46. In individuals with intermediate levels of protease inhibitor deficiency, lipophage and giant cell accumulation may be prominent46. Lesions heal with scarring and obliteration of fat lobules. Views differ on whether alpha-1 antitrypsin deficiency panniculitis should be regarded as a primarily septal or lobular panniculitis. Clearly, involvement of fat lobules can be significant, and, as a result, there are authors who have labeled the process a lobular panniculitis. On the other hand, some descriptions have emphasized early septal inflammation, collagenolysis of the fibrous septa (Fig. 100.6)52, and the prominent septal fibrosis in late-stage lesions51.

Differential diagnosis

1740

Clinically, the degrees of inflammation, ulceration and drainage associated with alpha-1 antitrypsin deficiency panniculitis may actually elicit a differential diagnosis more focused upon ulcerative skin disorders (see Fig. 105.1). Ulcers associated with alpha-1 antitrypsin deficiency generally lack the necrotic, “undermined” borders associated with pyoderma gangrenosum46. Tissue culture to exclude infection-induced panniculitis may be required. Entities in the microscopic differential diagnosis include traumatic (factitial) panniculitis, infection-induced panniculitis, pancreatic panniculitis, and erythema induratum (nodular vasculitis)46. Each of these can be associated with infiltrates that include neutrophils and varying degrees of necrosis, yet each has other distinct findings (see below). In the appropriate clinical setting, subcutaneous Sweet syndrome and neutrophilic panniculitis in patients with rheumatoid arthritis or inflammatory bowel disease may represent additional diagnostic considerations.

Treatment Treatments that are usually ineffective include corticosteroids and other immunosuppressants, cytotoxic agents, colchicine, danazol, and hydroxychloroquine41,46. Doxycycline is sometimes effective, particularly in mild cases; one suggested dosage schedule is 200 mg twice daily for 3 months48,53. Dapsone may also be beneficial in mild cases, by suppressing neutrophil migration and inhibiting oxidation reactions induced by myeloperoxidase41. Reduction of alcohol intake has also been recommended, since ethanol (as a hepatotoxin) may precipitate alpha-1 antitrypsin-associated hepatitis49. The most effective therapeutic intervention is replacement of alpha-1 antitrypsin via intravenous infusions. Dosages are generally 60 mg/kg per week, administered over a period of 3 to 7 weeks41,42. Improvement is relatively rapid, in that clearing of the panniculitis can occur after three weekly doses41. Recurrences are possible when alpha-1 antitrypsin levels fall below 50 mg/dl41, but these typically respond to further replacement therapy. Other successful therapies include plasma exchange and liver transplantation (in appropriate clinical circumstances). There is evidence that autophagy-enhancing drugs, such as carbamazepine, may reduce systemic manifestations, including hepatic fibrosis54, and clinical trials are currently underway55.

ERYTHEMA INDURATUM Synonyms:  ■ Nodular vasculitis ■ Erythema induratum of Bazin or Bazin disease (tuberculous etiology) ■ Erythema induratum of Whitfield (non-tuberculous etiology)

Key features ■ Erythematous nodules or plaques, usually on the posterior lower legs of young to middle-aged women ■ Ulceration and drainage may occur ■ Microscopic features of lobular or mixed panniculitis with evidence of vasculitis involving arteries or veins ■ Classically associated with tuberculosis, but similar lesions can be idiopathic or induced by other infectious agents or drugs

Introduction Erythema induratum is a condition characterized by nodules on the lower extremities, which may ulcerate and drain. Originally regarded



History Erythema induratum was first described by Ernest Bazin in 1861. It was generally regarded as a tuberculid because of a strong association with tuberculosis, although Koch’s postulates could not be fulfilled. In 1945, Montgomery and colleagues proposed the term nodular vasculitis for cases with similar clinical and pathologic features that were not of tuberculous origin. Since the early 1970s, erythema induratum and nodular vasculitis have generally been considered as synonyms referring to a clinicopathologic entity with several possible causes, one of which is tuberculosis. The detection of mycobacterial DNA in cutaneous lesions has confirmed a tuberculous origin in some patients56. There are certain clinicians, however, who prefer to use the term nodular vasculitis when referring to individuals with a non-tuberculous etiology.

Kenneth E Greer, MD.

CHAPTER

100 Panniculitis

Fig. 100.7 Erythema induratum – clinical appearance. Inflamed nodular lesions on the lower leg, with evidence of ulceration. Courtesy,

as a tuberculid, its relationship to tuberculosis in a subset of patients has been solidified by more recent studies that have detected mycobacterial DNA in cutaneous lesions.

Epidemiology In erythema induratum, an overwhelming female predominance is observed, but men can also develop the disease57. There is no apparent racial predilection, and although there is a wide age range among affected patients, the mean is between 30 and 40 years57. Erythema induratum of tuberculous etiology occurs more frequently in populations with a high prevalence of tuberculosis.

Pathogenesis As mentioned previously, some cases have been strongly associated with Mycobacterium tuberculosis infection. This can be substantiated by the detection of mycobacterial DNA in skin lesions by PCR56,58,59, with specific primers used to distinguish M. tuberculosis complex DNA from that of other mycobacterial pathogens59. Non-tuberculous cases have been related to other infectious agents (e.g. Nocardia23, hepatitis C virus60) or to drugs (e.g. propylthiouracil61). There is a report of erythema induratum being induced by a tuberculin skin test. Although it has been suggested that erythema induratum results from an immune complex-mediated vasculitis57, most investigators believe that the process represents a type IV, cell-mediated response to an antigenic stimulus62. Biopsy specimens show a predominance of T lymphocytes, macrophages and dendritic cells, including Langerhans cells57,63,64. One study of peripheral blood mononuclear cells from a patient with erythema induratum and active tuberculosis showed a high proliferative response to purified protein derivative (PPD) and marked production of interferon-γ, suggesting a pathogenic role for these PPD-specific T cells in a delayed hypersensitivity response to mycobacterial antigens65.

A

Clinical features Erythema induratum is characterized by tender, erythematous to violaceous nodules and plaques that most often develop on the lower legs, especially the calves63,64. Lesions have also been reported on the feet, thighs, buttocks and arms57. An annular arrangement of nodules has been described in M. tuberculosis-related cases66. Ulceration can occur (Fig. 100.7). Lesions are persistent, tend to heal with scarring, and are prone to recurrence57,63,67. In erythema induratum associated with M. tuberculosis, there may be clinical and radiographic evidence for active tuberculosis, positive skin tests to PPD, or a positive interferon-gamma release assay such as the QuantiFERON®-TB Gold In-Tube test68. In addition, other tuberculids, e.g. papulonecrotic, may be present. Clinical differences between tuberculous and non-tuberculous cases are minor.

Pathology Erythema induratum is generally described as a lobular or mixed septal/lobular panniculitis. Inflammation is mixed, and can include neutrophils, lymphocytes, macrophages and multinucleated giant cells (Fig. 100.8A). Vasculitis is identifiable in the vast majority of cases, and most frequently involves veins or arteries of connective tissue septa and small venules of the fat lobules69 (Fig. 100.8B). It may be predominantly neutrophilic63, lymphocytic67, or granulomatous. Necrosis with a coagulative or caseous appearance may be

B

Fig. 100.8 Erythema induratum – histopathologic features. A A predominantly lobular panniculitis is seen with an infiltrate that is lymphocytic and granulomatous; note the multinucleated giant cells (inset). B Vasculitis involving a medium-sized vessel in the subcutis.  

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Disorders of Subcutaneous Fat

16

present, sometimes with palisading granulomas63. Necrosis has been described in both tuberculous and non-tuberculous cases, and the incidence and degree of necrosis are greater in those cases that are positive for M. tuberculosis DNA by PCR methods58. However, this finding is absent in over half of cases.

Differential diagnosis Infection-induced panniculitis tends to show a more prominent neutrophilic component, granular basophilic necrosis, sweat gland necrosis and proliferation of small vessels, and organisms may be identified on special staining. Lupus panniculitis tends to be less granulomatous, has a prominent lymphoplasmacellular infiltrate, may show mucin deposits, and sometimes has overlying epidermal and dermal changes typical for lupus erythematosus. Both polyarteritis nodosa and thrombophlebitis tend to show inflammation limited to the immediate perivascular zone, in contrast to the extensive lobular panniculitis often encountered in erythema induratum. Histologically, perniosis can be difficult to distinguish from erythema induratum, but there is typically a history of cold exposure63, and on microscopic examination prominent involvement of dermal vessels is often observed, with “fluffy edema” of their walls.

Treatment Treatment should be directed at the underlying cause, if found. This includes multi-drug antituberculous therapy66 (see Ch. 75) and discontinuing possible inciting medications. Therapeutic options for nontuberculous erythema induratum include NSAIDs, corticosteroids, tetracyclines, potassium iodide, and mycophenolate mofetil70. Supportive care is similar to that for erythema nodosum (see Table 100.5).

PANCREATIC PANNICULITIS Synonyms:  ■ Pancreatic fat necrosis ■ Enzymatic panniculitis

Key features ■ Subcutaneous nodules, sometimes accompanied by fever, arthritis or abdominal pain ■ Associated with pancreatic disorders, including acute and chronic pancreatitis and pancreatic carcinoma ■ Mixed septal/lobular panniculitis featuring “ghost cell” formation and the deposition of basophilic material due to saponification of fat by calcium salts ■ Treatment primarily directed towards the underlying pancreatic disorder

urine71, and skin lesions, even in the absence of detectable pancreatic disease. Lipase has the clearest relationship with the panniculitis, with a number of patients having elevated serum lipase levels but normal amylase levels72. Utilizing an anti-pancreatic lipase monoclonal antibody, positive intracellular adipocyte staining was observed in a biopsy of lesional skin74. Amylase levels, when elevated, tend to peak 2–3 days after eruption of the skin lesions and return to normal 2–3 days after regression of the lesions. Trypsin and perhaps amylase may act by promoting increased permeability of vessel walls, thereby permitting lipase to hydrolyze neutral fat to form glycerol and free fatty acids, with resulting fat necrosis and inflammation72,73. Venous stasis may promote this process, possibly explaining the predilection for the lower extremities. Elevated enzyme levels may not be the complete explanation for the changes of pancreatic panniculitis75; immunologic factors probably also play a role.

Clinical features Subcutaneous nodules develop in association with acute or chronic pancreatitis, pancreatic carcinoma (acinar cell > other types [e.g. neuroendocrine carcinomas]), pancreatic pseudocysts, pancreas divisum, or traumatic pancreatitis72,76. The possibility of a pancreaticoportal fistula should be considered when panniculitis develops in individuals with chronic pancreatitis, and in some of these patients, an acinar cell carcinoma can also be found. Panniculitis may precede detection of pancreatic disease by 1–7 months73, and in the case of pancreatic carcinoma, its onset may signal the presence of metastatic disease72,73. In pancreatic panniculitis, subcutaneous nodules develop, frequently on the legs but also on the anterior trunk, arms (Fig. 100.9), and scalp72,73. Erythematous, edematous, sometimes painful lesions arise singly or in crops, and they may migrate. They can become fluctuant and ulcerate, discharging an oily material72. Panniculitis may also involve visceral fat, including the omentum and preperitoneal fat72. Associated findings include fever, abdominal pain, inflammatory polyarthritis, ascites and pleural effusions72. The association of subcutaneous nodules, polyarthritis and eosinophilia is known as Schmid’s triad, and it is associated with a poor prognosis. Some patients have radiographic evidence of multiple lytic areas involving the cortical bone near large joints. Cutaneous lesions may involute within a period of weeks, leaving hyperpigmented scars. In acute pancreatitis, the panniculitis resolves as the acute inflammatory phase passes72. However, lesions may also persist and expand until the underlying pancreatic abnormality has been treated.

Pathology Pancreatic panniculitis may begin as a septal panniculitis22, but with progression, the lesion takes on the appearance of a lobular or mixed Fig. 100.9 Pancreatic panniculitis – clinical appearance. Multiple red to violet–brown nodules on the arm. There is also postinflammatory desquamation.  

Introduction Pancreatic panniculitis is an unusual complication of pancreatic disease. In addition to the symptoms associated with fat necrosis, its chief importance is as a sign of a significant systemic disorder, particularly because the panniculitis may be recognized prior to detection of the underlying pancreatic disease.

History Chiari first described pancreatic panniculitis in 1883. By 1999, fewer than 100 cases had been reported71,72. Since then, an additional 90 publications have appeared, primarily as case reports.

Epidemiology Panniculitis develops in up to 2% of patients with pancreatic disorders73. No geographic, racial or gender predilections have been reported.

Pathogenesis 1742

There is considerable evidence that the enzymes lipase, amylase and trypsin are involved in producing the lesions of pancreatic panniculitis71. Elevated enzyme levels have been detected in the blood72,73,



Lorenzo Cerroni, MD.

point for stored fat and promotes crystallization under certain conditions. Microsized crystals (type A) apparently do not produce an inflammatory response; they are actually common (in a widely dispersed form) in healthy infants 6 months of age or less, but are more numerous in sclerema neonatorum. Larger, type B crystals that tend to be arranged in rosettes are capable of eliciting a granulomatous response; these larger crystals are most often seen in subcutaneous fat necrosis of the newborn and post-steroid panniculitis77. Crystallization and defects in fat mobilization account for the clinical findings in these disorders.

CHAPTER

100 Panniculitis

Fig. 100.10 Pancreatic panniculitis – histopathologic features. Lobular and septal panniculitis with neutrophilic inflammation, cellular necrosis, ghost cells (inset), and deposition of homogeneous basophilic material due to saponification of fat by calcium salts. Courtesy,

Sclerema Neonatorum Key features ■ Arises in premature infants ■ Skin is diffusely cold, rigid, and board-like ■ Microscopically, needle-shaped clefts are present within lipocytes and there is minimal inflammation ■ Affected infants are often hypothermic and may have a variety of other medical problems; early death is common

History septal/lobular process. Even in early stages, fat necrosis with liquefaction and microcyst formation is observed71,75. Lipocytes lose their nuclei and develop thick, shadowy walls, forming the characteristic “ghost cells”. Saponification of fat by calcium salts results in deposition of granular or homogeneous basophilic material (Fig. 100.10). Neutrophils, occasional eosinophils, macrophages, and multinucleated giant cells are sometimes present and may encroach upon the septa. Fibrosis and lipoatrophy are seen in late stages as the process resolves.

Differential diagnosis Clinically, the nodules of pancreatic panniculitis can resemble those of a number of other forms of panniculitis. Ulceration and discharge would argue against erythema nodosum, and an association with fever, polyarthritis and/or abdominal pain should raise suspicion of associated pancreatic disease. Serum amylase and lipase levels, if elevated, may also be helpful. Histologic evidence of “ghost cell” formation and saponification of fat distinguishes pancreatic panniculitis from other panniculitides, with the exception of ghost cell formation in mucormycosis panniculitis. Eosinophilic “hyaline necrosis” is seen in lupus panniculitis, rather than the granular or homogeneous basophilic necrosis typical of pancreatic panniculitis.

Treatment Although supportive measures such as compression and elevation can be helpful, effective management of pancreatic panniculitis is dependent upon treatment of the underlying pancreatic disease. In chronic pancreatitis, a pancreatic duct stent can be used to relieve obstruction, or, if a fistula or cyst is involved, biliary bypass surgery can be undertaken if simple drainage measures are unsuccessful. Octreotide, a synthetic somatostatin-like polypeptide, can be used to inhibit pancreatic enzyme production72. Resection of pancreatic cancer may be followed by regression of the panniculitis.

SCLEREMA NEONATORUM, SUBCUTANEOUS FAT NECROSIS OF THE NEWBORN, AND POSTSTEROID PANNICULITIS Three entities – sclerema neonatorum, subcutaneous fat necrosis of the newborn, and post-steroid panniculitis – are characterized histologically by the formation of needle-shaped clefts within lipocytes. In contrast to adult fat, the subcutaneous fat of infants is thought to be prone to crystal formation because of a higher content of saturated fatty acids, including palmitic and stearic acids, and a relatively lower content of unsaturated fatty acids, such as oleic acid77. This increased saturated : unsaturated fatty acid ratio results in a higher melting

Uzembenzius first recognized sclerema neonatorum in 1722, although the classic description is usually attributed to Underwood (1784). Ballantyne provided an early description of the histopathologic changes, and Knopfelmacher noted the presence of needle-shaped crystals in subcutaneous tissue in 1897.

Epidemiology Sclerema neonatorum presents most often in premature, debilitated infants, usually during the first week of life. There is a slight male predominance, with no substantial gender differences in death rates78.

Pathogenesis In infants who develop sclerema, crystallization and hardening of fat occur in the setting of an increased saturated : unsaturated fatty acid ratio and a defective ability to mobilize fatty acids. Precipitating factors are listed in Table 100.877.

Clinical features The clinical features are outlined in Table 100.877–79. Rapid hardening of the subcutaneous tissues leads to firm, rigid skin over most of the body. Low birth weight and hypothermia as well as hemorrhagic phenomena portend a particularly poor prognosis78.

Pathology Table 100.8 outlines the microscopic features. Inflammation is usually sparse, and most of the needle-shaped clefts are found within lipocytes rather than within giant cells (Fig. 100.11)77,79. At a later stage, thickened connective tissue bands may be the only histologic finding79.

Differential diagnosis In contrast to sclerema neonatorum, subcutaneous fat necrosis of the newborn is a localized process with a favorable prognosis; histologically, the latter is distinguished by more prominent inflammation and localization of needle-shaped clefts within giant cells. Scleredema neonatorum is a condition seen in premature infants with congenital heart disease. In this disorder, the skin is distended and wax-like, and on biopsy the dermis appears edematous, with increased amounts of mucin77. Other conditions that can present with diffusely indurated skin in the neonatal period include stiff skin syndrome (usually favoring the trunk, buttocks and thighs), restrictive dermopathy, and Hutchinson– Gilford progeria. While subcutaneous needle-shaped clefts are generally observed in infants and children, radially arranged needle-shaped clefts (resembling those of sclerema neonatorum) were recently reported in an adult with gemcitabine-related thrombotic microangiopathy80; however, these crystals were quite small.

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Disorders of Subcutaneous Fat

16

PANNICULITIDES WITH NEEDLE-SHAPED CLEFTS IN THE SUBCUTIS

Condition

Patient characteristics

Onset

Cutaneous findings

Associated systemic findings

Histopathology

Possible precipitating factors

Sclerema neonatorum

Severely ill premature neonates

First week of life

Widespread, diffuse hardening, sparing only the genitalia, palms and soles; cool, waxy, rigid and board-like skin with purple mottled discoloration

Respiratory difficulties, congestive heart failure, intestinal obstruction, diarrhea; death, usually from septicemia, in three-quarters of patients

Needle-shaped clefts in lipocytes; septal thickening; inflammation sparse to absent (few neutrophils, eosinophils, macrophages or multinucleated giant cells may be seen)

Hypothermia, perinatal asphyxia, defective complement activity, dehydration

Subcutaneous fat necrosis of the newborn

Full-term neonates

First 2–3 weeks of life

Circumscribed, erythematous, indurated subcutaneous nodules favoring the cheeks, shoulders, back, buttocks, thighs; may become fluctuant

Hypercalcemia (onset may be delayed for several months), thrombocytopenia, hypertriglyceridemia; severe hypercalcemia may be associated with fever, eosinophilia, and persistent nephrocalcinosis

Lobular panniculitis with neutrophils, lymphocytes, macrophages; needle-shaped clefts in a radial array within lipocytes and giant cells; sometimes foci of calcification, hemorrhage

Hypothermia (including exposure to cooling blankets), hypoglycemia (e.g. due to gestational diabetes), perinatal hypoxemia (e.g. due to meconium aspiration, placenta previa, umbilical cord prolapse, pre-eclampsia)

Post-steroid panniculitis

Children (ages 1–14 years)

1–40 days* after cessation of high-dose systemic corticosteroids

Firm red plaques on the cheeks, arms, trunk; small and discrete or large and confluent lesions; pruritic, tender or asymptomatic

Underlying conditions treated with systemic corticosteroids have included leukemia, cerebral edema, nephrotic syndrome, secretory diarrhea, and acute rheumatic fever as well as chronic obstructive pulmonary disease and Sjögren syndrome in adults

Lobular panniculitis with lymphocytes, macrophages, multinucleated giant cells; needle-shaped clefts in lipocytes and giant cells

Follows rapid withdrawal of systemic corticosteroids

*Usually within 10 days. Table 100.8 Panniculitides with needle-shaped clefts in the subcutis.  

Subcutaneous Fat Necrosis of the Newborn Key features ■ Development of one or more mobile, firm, subcutaneous nodules or plaques during the newborn period ■ Sometimes associated with hypercalcemia or thrombocytopenia ■ Granulomatous lobular panniculitis with needle-shaped clefts within lipocytes and giant cells ■ Prognosis is usually favorable; spontaneous resolution is common

Introduction In contrast to sclerema neonatorum, subcutaneous fat necrosis is a localized process. Although complications can arise, particularly in relation to hypercalcemia, most cases resolve spontaneously. Fig. 100.11 Sclerema neonatorum. Needle-shaped clefts within lipocytes with chronic granulomatous inflammation.  

Treatment

1744

Attempts to treat this disorder are disappointing78. Management includes treatment of sepsis, ventilatory support, correction of fluid and electrolyte imbalances, and maintenance of body temperature77,81. Exchange transfusions may be of value in selected instances77,81. Systemic corticosteroids are of questionable utility77,78.

History At the beginning of the twentieth century, Fabyan described “abscesses” that spontaneously resorbed, and he provided the first microscopic description of subcutaneous fat necrosis.

Epidemiology Subcutaneous fat necrosis of the newborn typically occurs in full-term neonates during the first 2 to 3 weeks of life82.

It is believed that a variety of stresses imposed upon fetal fat, with its high ratio of saturated : unsaturated fatty acids, results in crystallization, adipocyte injury, and granulomatous inflammation. Hypothermia is one potential eliciting factor, as illustrated by cases of subcutaneous fat necrosis that developed following hypothermic cardiac surgery and the use of cooling blankets83–85. Other proposed causes are listed in Table 100.877,82,84. The role of birth trauma has been questioned, since many cases have occurred in infants delivered by cesarean section82.

4 months) is recommended. Hypercalcemia is managed by hydration, dietary restriction of both calcium and vitamin D, calcium-wasting diuretics (e.g. furosemide), calcitonin, and bisphosphonates (e.g. etidronate, pamidronate)82,84,91. Corticosteroids may be helpful in managing hypercalcemia, by interfering with the metabolism of vitamin D to calcitriol, and by inhibiting calcitriol production by macrophages84.

Post-Steroid Panniculitis

CHAPTER

100 Panniculitis

Pathogenesis

Key features

Clinical features The clinical features are outlined in Table 100.8. Smooth, circumscribed, mobile, red to violaceous, subcutaneous nodules or plaques develop, sometimes in a symmetrical fashion77,82 (Fig. 100.12). The areas of fat necrosis can be detected by CT86 and MRI87. Some patients develop hypercalcemia or thrombocytopenia, and the former may appear 1–4 months after the onset of the skin lesions84. It is believed that the hypercalcemia results from extrarenal production of 1,25-dihydroxyvitamin D3 (calcitriol) by activated macrophages (expressing 1-α-hydroxylase) within areas of granulomatous panniculitis. This stimulates calcium absorption from the gut and mobilization from the bones82,88. The mechanism for thrombocytopenia may be local sequestration in the subcutis, as studies have shown normal bone marrow cellularity and resolution of the thrombocytopenia as the inflammatory process resolves89. Spontaneous resolution of lesions is the rule, but some patients develop residual lipoatrophy. Deaths have been reported in those with associated hypercalcemia89.

Pathology The microscopic changes are outlined in Table 100.8. They include a predominantly lobular panniculitis with mixed cellularity (Fig. 100.13). Needle-shaped clefts are observed within both lipocytes and giant cells (Fig. 100.13, inset). The crystals are doubly refractile and stain with oil red O77. Occasionally, however, needle-shaped clefts are not evident in otherwise typical cases. Eosinophilic granules are sometimes found within multinucleated giant cells; their origin is not entirely certain, but they may be derived from degranulating eosinophils90.

Differential diagnosis

■ A rare complication of rapid withdrawal of systemic corticosteroids ■ Subcutaneous nodules develop on the cheeks, arms and trunk ■ Lesions resolve spontaneously, or when corticosteroids are readministered ■ Microscopically, granulomatous lobular panniculitis with needleshaped clefts within both lipocytes and giant cells

History In 1956, Smith and Good92 reported 11 children with acute rheumatic fever who were treated with large doses of corticosteroids that were rapidly tapered. Five children developed pruritic, erythema nodosumlike lesions.

Epidemiology Post-steroid panniculitis is typically a disorder of children. It occurs in an older age group than either sclerema neonatorum or subcutaneous fat necrosis of the newborn, with reported ages ranging from 20 months to 14 years93. Occasionally, the disorder occurs in adults94,95.

Pathogenesis Post-steroid panniculitis occurs after rapid withdrawal of systemic corticosteroids that have been administered either orally or intravenously. For patients who had received prednisone, cumulative dosages ranged from 2000 to 6000 mg93. The precise mechanism by which the panniculitis arises is not known.

Clinical features

The extensive cutaneous involvement in sclerema neonatorum is usually distinguishable from the localized, self-limited process of subcutaneous fat necrosis; histologically, inflammation in sclerema is minimal. Post-steroid panniculitis is microscopically indistinguishable from subcutaneous fat necrosis, but it arises in a different clinical setting (see below).

Patients who have developed this form of panniculitis received corticosteroid therapy for a variety of conditions92–96, including those listed in Table 100.8. Lesions appear 1 to 40 days after rapid corticosteroid withdrawal and disappear spontaneously over a period of months to a year96.

Treatment

Pathology

Since many lesions resolve spontaneously, the emphasis is on supportive care. Systemic corticosteroids may be indicated to control the inflammation in severe cases77. Serial monitoring of calcium levels (for at least

Microscopic changes are outlined in Table 100.896. Needle-shaped clefts, some with a “starburst” pattern, can be identified within lipocytes or giant cells. Fig. 100.13 Subcutaneous fat necrosis of the newborn – histopathologic features. A predominantly lobular panniculitis is seen. Needle-shaped clefts in a radial configuration are present within giant cells (inset). Similar findings are seen in post-steroid panniculitis.  

Fig. 100.12 Subcutaneous fat necrosis of the newborn – clinical appearance. Red–violet indurated plaques, primarily on the back and shoulders.  

Courtesy, Lorenzo Cerroni, MD.

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Disorders of Subcutaneous Fat

16

Differential diagnosis

Fig. 100.14 Lupus panniculitis – clinical appearance. Red–brown plaques on the upper outer arm. Note the significant subcutaneous atrophy and overlying lesions of discoid lupus erythematosus. Courtesy,  

A less nodular presentation involving the cheeks can mimic nonpanniculitic disorders such as erythema infectiosum, atopic dermatitis, lupus erythematosus, or facial cellulitis. The microscopic changes in these conditions would be quite different from those of post-steroid panniculitis. Cold panniculitis has clinical and microscopic similarities, but the history of cold exposure and the lack of needle-shaped clefts on biopsy permit distinction. The microscopic changes of poststeroid panniculitis are virtually identical to those of subcutaneous fat necrosis of the newborn, although calcification and hemorrhage are more commonly observed in the latter condition. Clinical history allows distinction.

Kenneth E Greer, MD.

Treatment Since spontaneous resolution is the rule, treatment is usually unnecessary. Readministration of corticosteroids followed by a more gradual taper may be helpful96.

LUPUS ERYTHEMATOSUS PANNICULITIS (LUPUS PANNICULITIS) Synonyms:  ■ Lupus profundus ■ Subcutaneous lupus erythematosus

Key features ■ Tender subcutaneous nodules and plaques arising on the face, proximal extremities and trunk ■ Associated with discoid lupus erythematosus in at least one-third of patients; less often associated with systemic lupus erythematosus (10–15% of patients) ■ Often precedes onset of other manifestations of lupus erythematosus ■ Characteristic microscopic changes include lobular panniculitis with hyaline necrosis and a predominantly lymphoplasmacytic infiltrate; nodular aggregates of lymphocytes are common ■ Overlying epidermal or dermal changes of lupus erythematosus are frequently present

Lupus panniculitis constitutes a small subset of all cases of cutaneous LE, representing 2–3% of this group98. It usually occurs in adults, with a median age of onset of 30–40 years99. Children can also develop lupus panniculitis, and an association with neonatal lupus has been described97. There is a predominance among women, with a female : male ratio ranging from 2 : 1 to 4 : 136,99. Sometimes there is a family history of either LE or another autoimmune connective tissue disease98.

Lupus panniculitis is characterized by tender subcutaneous nodules and plaques that may arise in crops (see Table 100.7). A history of trauma can sometimes be elicited. Lesions tend to develop on the face, upper arms, hips and trunk (Fig. 100.14). Linear scalp lesions are common among, but not restricted to, East Asian populations103. The lack of involvement of the distal extremities is noteworthy99. Changes in the overlying skin range from a light pink color to those of discoid LE, i.e. scaling, follicular plugging, dyspigmentation, telangiectasias, atrophy and scarring. At times, findings of discoid LE are too subtle to be recognized clinically but can be seen on microscopic examination of biopsy specimens. The overlying skin may also be “tethered” to the subcutaneous nodule or plaque, creating a surface depression, and ulceration occasionally occurs. Lupus panniculitis has a chronic, relapsing clinical course104. It usually eventuates in subcutaneous atrophy, which can be disfiguring (see Chs 41 & 101). Lupus panniculitis often occurs prior to other manifestations of LE and in the absence of other autoimmune connective tissue diseases99. For example, lesions of discoid LE have developed up to 10 years after the appearance of the panniculitis. However, manifestations of systemic LE or discoid LE can also occur long before or simultaneously with the panniculitis36. There is a closer relationship of lupus panniculitis to other forms of chronic cutaneous LE (e.g. discoid LE) than to systemic LE. Coexistent discoid lesions are observed in at least one-third of patients, whereas only 10–15% meet the diagnostic criteria for systemic LE99,105. Most individuals in the latter group have relatively mild systemic manifestations, usually arthralgias or Raynaud phenomenon98. It is common for patients to have low-titer antinuclear antibodies; they can also have other circulating autoantibodies (e.g. anti-dsDNA, antiRNP), leukopenia, hypocomplementemia, and an elevated ESR98.

Pathogenesis

Pathology

The autoimmune basis of lupus panniculitis is thought to be similar to that of other types of LE (see Ch. 41). The cells comprising the infiltrates of lupus panniculitis are T lymphocytes and macrophages100. Lupus panniculitis, often with a childhood onset and widespread distribution, has been described in patients with partial C4 deficiency101. This complement deficiency causes defective opsonization of immune complexes, which may play a role in the pathogenesis of the disease101. Immunohistochemical analysis has shown an interferon-driven Th1biased immune response in active lesions of lupus panniculitis; this may result in recruitment of cytotoxic CXCR3-positive lymphocytes102.

Lupus panniculitis is a predominantly lobular process with a variable degree of inflammation (Fig. 100.15A). Nodular aggregates of lymphocytes are often present (Fig. 100.15B). The characteristic microscopic changes, e.g. hyaline necrosis of the fat lobules, are outlined in Table 100.7 (Fig. 100.15C). Granulomas can occur and tend to encroach upon the septa, but they are usually not prominent. Other features include lymphocytic vasculitis and mucin or calcium deposition. The subcutaneous findings alone are considered sufficiently characteristic to permit a diagnosis of lupus panniculitis. However, overlying epidermal or dermal changes of discoid LE occur in one-half to

History Kaposi first described the clinical characteristics of lupus panniculitis in 1869. In 1940, it was recognized as a manifestation of lupus erythematosus (LE) by Irgang. Lupus panniculitis was firmly established as a specific subtype of LE in a 1956 paper by Arnold97.

Epidemiology

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Clinical features



CHAPTER

100 Panniculitis

Fig. 100.15 Lupus panniculitis – histopathologic features. A,B A primarily lobular panniculitis with nodular aggregates of lymphocytes. C Hyaline necrosis of fat lobules is also a characteristic feature. A focus of lipomembranous changes, a nonspecific finding observed in the late stages of several types of panniculitis, is present. Courtesy, Lorenzo Cerroni, MD.

B

A

C

two-thirds of cases and are also helpful diagnostically 100,105,106. With direct immunofluorescence, a positive lupus band can be identified in the overlying skin in a high percentage of cases, even in those where the histopathologic changes are nonspecific106.

Differential diagnosis

Overlying discoid lesions, if present, can be treated with potent topical or intralesional corticosteroids.

PANNICULITIS OF DERMATOMYOSITIS

Clinically, lesions of lupus panniculitis can resemble other forms of panniculitis. The rarity of involvement of the distal extremities helps to distinguish it from conditions such as erythema nodosum and erythema induratum. It should also be remembered that other forms of subcutaneous inflammation may occur in patients with LE, including erythema nodosum, thrombophlebitis, pancreatic panniculitis, and juxta-articular, rheumatoid nodule-like lesions. Microscopically, lupus panniculitis can resemble the panniculitis associated with morphea and dermatomyositis (see Table 100.7), traumatic panniculitis (which often has evidence of foreign material) and, in its later stages, localized lipoatrophy due to other etiologies98,104. The most important entity in the differential diagnosis is subcutaneous panniculitis-like T-cell lymphoma, as there can be considerable histopathologic overlap between the two disorders. The distinguishing features are outlined in Table 100.9. It should be noted, however, that changes such as vacuolar alteration of the basilar layer and dermal mucin deposition have been reported in panniculitis-like T-cell lymphoma107. To complicate matters further, features of both disorders can be present in the same biopsy specimen108.

Introduction

Treatment

ment of subcutaneous fat without overt clinical features of panniculitis is more common.

Antimalarials are frequently used to treat lupus panniculitis, and they produce improvement in most patients99. Addition of a second antimalarial may prove useful in patients who do not respond to a single agent104. In view of the chronic, relapsing nature of the disease, treatment may be required for several years98. Systemic corticosteroids, when used, are often restricted to initial phases of the disease98. Other systemic therapies include dapsone, mycophenolate mofetil, cyclophosphamide, thalidomide, and IVIg99,101,109.

Panniculitis is a rare but established clinical manifestation of dermatomyositis. However, there is some evidence that microscopic involve-

Key features ■ An uncommon manifestation of dermatomyositis ■ More frequently, incidental microscopic changes of panniculitis (in the absence of clinical lesions) are observed ■ Can precede or follow other manifestations of dermatomyositis ■ Microscopically, it is a lobular or mixed panniculitis with lymphoplasmacytic predominance ■ Usually responds to therapy

Clinical features The characteristic lesions are persistent, indurated, painful plaques and nodules that may ulcerate and lead to lipoatrophy (see Table 100.7)110. They can arise in the setting of established dermatomyositis110 or represent the first manifestation of the disease111. In affected individuals, the other clinical and laboratory features as well as the incidence of

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16

LUPUS PANNICULITIS VS SUBCUTANEOUS PANNICULITIS-LIKE T-CELL LYMPHOMA – DISTINGUISHING FEATURES

Lupus panniculitis

SPTCL

Clinical features Subcutaneous nodules, indurated plaques; sometimes large painful ulcers; lipoatrophy • Proximal extremities, hips, trunk; face and scalp in Asian populations • Precedes, accompanies, or follows the development of other manifestations of LE • Treatment: corticosteroids (intralesional, ultrapotent topical), antimalarials, cyclosporine, dapsone •

Multiple plaques and nodules; usually do not ulcerate



Favors the extremities, but can be generalized



Fever, weight loss, and/or hemophagocytic syndrome in a small subset of patients • Treatment: systemic corticosteroids; chemotherapy reserved for advanced disease; cyclosporine •

Differential diagnosis Lupus panniculitis is more likely to show hyaline necrosis and lymphoid nodules, but clinical and laboratory findings may be needed to make a distinction. Overlying poikilodermatous changes can occur in both diseases, but lupus is more likely to show appendageal involvement and is associated with positive basement membrane zone fluorescence.

Treatment Good responses to therapy have generally been reported112, and treatments include prednisone, methotrexate, azathioprine, cyclosporine, and IVIg110–112. Panniculitis lesions have shown variable responses to hydroxychloroquine. Residual facial lipoatrophy has been successfully treated with hyaluronic acid and poly-L-lactic acid dermal fillers.

TRAUMATIC PANNICULITIS

Microscopic and laboratory features Epidermal and dermal changes of LE in half of cases



Lobular lymphocytic panniculitis • Nuclear dust can be observed in later stages • Cytologic atypia or adipocyte rimming by lymphocytes: uncommon • Lymphoid follicles: 20–50% of cases • Clusters of B cells: present •

Staining for MxA: more extensive • Clusters of plasmacytoid dendritic cells • Infiltrate: plasma cells, sometimes eosinophils •

Fat necrosis: hyaline or lipomembranous • TCR-γ gene rearrangement: polyclonal •

Epidermal changes occur infrequently; changes usually confined to the subcutis • Lobular lymphocytic involvement • Nuclear dust can be observed in later stages • Cytologic atypia and adipocyte rimming by lymphocytes: seen more frequently • Lymphoid follicles: generally absent • Clusters of B cells: generally not seen • Staining for MxA: less extensive •

Clusters of plasmacytoid dendritic cells not observed • Infiltrate: plasma cells not prominent; granulomas may be seen • Fat necrosis; fibrinoid/coagulative •

TCR-γ gene rearrangement: monoclonal (positive)



Table 100.9 Lupus panniculitis versus subcutaneous panniculitis-like T-cell lymphoma (SPTCL) – distinguishing features. LE, lupus erythematosus; MxA, human myxovirus resistance protein 1; TCR, T-cell receptor.  

malignancy appear to be similar to those of dermatomyositis patients without panniculitis110. Partial or generalized lipoatrophy without preceding clinical lesions of panniculitis (occasionally accompanied by increased abdominal fat) occurs in up to one-quarter of patients with juvenile dermatomyositis, and it is often associated with metabolic abnormalities such as hypertriglyceridemia and insulin resistance (see Ch. 101).

Pathology

1748

The microscopic features are outlined in Table 100.7. Lymphocytic vasculitis has been described, and fat necrosis has been noted in several reports110. Membranocystic changes have been observed in some cases (see section on lipodermatosclerosis), and lesions with these changes may be particularly resistant to therapy110. Calcification is variable and is an expected finding in cases of dermatomyositis associated with calcinosis of deep soft tissues and skeletal muscle35. Vacuolar alteration of the basal layer of the overlying epidermis has been described110, and the dermis may be edematous or mucinous with perivascular lymphocytic inflammation112. Direct immunofluorescence is reported to be negative for deposits along the dermal–epidermal junction110, although immunoreactants have been detected in vessel walls112.

Key features ■ Inflammation in the subcutis resulting from external injury ■ The injurious event may be accidental, purposeful or iatrogenic, and it may be a manifestation of an underlying psychiatric disturbance ■ A variety of histopathologic changes are observed, depending upon the inciting agent ■ Identification of foreign material is of greatest help in diagnosis

Introduction Extrinsic injury of varying types can produce panniculitis. There are four broad categories: cold panniculitis (Haxthausen disease), sclerosing lipogranuloma, panniculitis due to other injectable substances or therapies (e.g. megavoltage radiation), and panniculitis due to blunt trauma.

History Lemez described cold panniculitis in 1928, when he noted that newborns and infants up to 6 months of age were particularly susceptible to cold injury, as demonstrated by the production of a subcutaneous nodule following application of an ice cube113. In 1941, Haxthausen described a condition occurring in small children a few days after exposure to cold, consisting of firm infiltrated nodules of the cheeks and chin. A similar type of cold injury due to popsicles was reported by Epstein and Oren in 1970114. Injection of foreign lipid material into the skin for cosmetic or other purposes has been performed for centuries115. In 1950, Smetana and Bernhard reported 14 cases of what they termed sclerosing lipogranuloma of the male genitalia. They believed it was an endogenous process, but subsequent studies demonstrated the presence of mineral oil in similar cases115.

Epidemiology Infants and small children are most at risk for cold panniculitis. A form of the disease also occurs on the thighs of young women who are equestrians116. Sclerosing lipogranuloma of the male genitalia is seen mostly in young adults117. A sclerosing, pseudosclerodermatous panniculitis has been reported following megavoltage radiation for metastatic carcinoma118 and as a radiation recall reaction after cyclophosphamide therapy119.

Pathogenesis Cold injury to fat favors small children, due in part to the previously discussed characteristics of their fat120. Cold injury is also related to fluctuations in blood flow that occur with declining temperatures (the “hunting phenomenon”), ice crystal formation, and the changes that occur with thawing120. Injections of oils (and associated impurities) are known for producing subcutaneous inflammation. Substances include

Clinical features In cold panniculitis (including popsicle panniculitis), erythematous, firm nodules develop, particularly on the cheeks and chin120. In equestrian cold panniculitis, erythematous to violaceous, tender plaques appear on the thighs following exposure to cold while wearing tightfitting clothing (Fig. 100.16)116. In lipogranuloma, nodules are sometimes migratory and can be accompanied by varying degrees of swelling, erythema, abscess formation, lymphangitis, and fibrosis115. The term sclerosing lipogranuloma often refers to lesions arising on the male genitalia due to self-injection of oily materials (see Ch. 94). There has also been a report of a sclerosing lipogranuloma that apparently resulted from topical application of vitamin E cream127. In several Japanese patients, Y-shaped induration of the scrotum (in which exogenous lipids could not be detected) was described as eosinophilic sclerosing lipogranuloma128. Patients with sclerosing lipogranuloma frequently deny self-injection, making diagnosis difficult. Another variant of lipogranuloma is the grease gun granuloma, which results from accidental firing of the grease gun used by mechanics. This results in formation of a verrucous nodule, often on the dorsum of the hand129. Inflamed nodules with varying degrees of pain and fibrosis have been observed in other forms of panniculitis due to injection, with the distribution of lesions sometimes providing a clue to their cause. A dramatic example of this is Texier disease, a panniculitis due to phytonadione (vitamin K) injections. In this disorder, sclerotic lesions with lilac-colored borders form on the buttocks and thighs, in a configuration resembling a “cowboy gunbelt and holster”121. Lesions due to blunt trauma often have an ecchymotic character and involve locations such as the shin, arm or hand126. Hypertrichosis

may also be present, possibly the consequence of local hyperemia or angiogenesis130.

Pathology Table 100.10 outlines the microscopic changes in various forms of traumatic panniculitis117–119,129–133. In addition, sclerosing lipogranuloma is discussed in Chapter 94.

CHAPTER

100 Panniculitis

mineral oil (paraffin) as well as camphor, cottonseed, and sesame oils. Even medical grade silicone may contain impurities, and since encapsulation of this material is desirable when used for cosmetic purposes, fibrosis-inducing substances such as olive oil or castor oil are often added115. Injected substances responsible for factitial panniculitis have included milk, feces, and a host of other substances. Panniculitis has been produced by numerous therapeutic agents, such as meperidine, morphine, pentazocine, phytonadione (vitamin K)121, glatiramer acetate, interferon-β, interleukin-2122, and vaccines (e.g. tetanus), as well as substances that have been used for tissue augmentation such as bovine collagen123 or poly-L-lactic acid. More recently, panniculitis due to “mesotherapy” (injection of substances such as phosphatidylcholine to treat localized fat accumulations; see Ch. 156)124 and electroacupuncture125 have been described. In addition to the foreign body response elicited by many of these agents, other immune mechanisms may also be involved. With blunt trauma, granulomas contain material that may be derived from the breakdown of erythrocyte membranes126.

Differential diagnosis In cold panniculitis, the absence of needle-shaped clefts in lipocytes and location of the most intense inflammation near the dermal– subcutaneous interface help to distinguish this condition from subcutaneous fat necrosis of the newborn. In sclerosing lipogranuloma and related lipogranulomas, distinctive large vacuoles are found in the dermis and subcutis (Fig. 100.17). Radiographs are sometimes useful in differentiating lipogranulomas from silicone granulomas, since only the latter are radio-opaque134. Mineral oil in non-processed tissue can be identified by infrared spectrophotometry129. Panniculitis due to injectable substances can be diagnosed when foreign material (often identified by polarization microscopy) is present. Cosmetic fillers have distinctive histologic features (see Fig. 94.10), and they can be identified by cutaneous sonography135. Cases with acute inflammation and necrosis may resemble infection-induced panniculitis, and, in fact, infection may accompany injection panniculitis136; special stains and cultures for organisms (including atypical mycobacteria) are useful in this regard. Sclerosing traumatic panniculitis (e.g. due to phytonadione or pentazocine injections) may resemble morphea clinically, but would not present as a septal panniculitis histologically.

Treatment Treatment of these disorders should focus on removal of the inciting stimulus and eradication of any associated infection. Intralesional or systemic corticosteroids can be helpful in controlling the inflammation, and they have been used in the management of sclerosing lipogranuloma115 and granulomatous panniculitis due to other injected substances123. Surgical excision may also be an option for sclerosing lipogranuloma115.

LIPODERMATOSCLEROSIS Synonyms:  ■ Sclerosing panniculitis ■ Hypodermitis sclerodermiformis ■

Chronic panniculitis with lipomembranous changes

Fig. 100.17 Mineral oil granuloma (paraffinoma). There is sclerosis throughout the dermis and subcutis as well as numerous vacuolated spaces (inset). Scattered histiocytes and lymphocytes are also seen. Courtesy, Lorenzo Cerroni,  

MD.

Fig. 100.16 Cold panniculitis. Violaceous nodules and plaques, some with central crusting, on the thigh of a young woman. Collarettes of scale developed as the lesions healed. Courtesy, Kendra Lesiak, MD.  

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Disorders of Subcutaneous Fat

16

MICROSCOPIC FEATURES OF TRAUMATIC PANNICULITIS

Condition

Microscopic features

Special considerations

Cold panniculitis

Septal/lobular inflammation, especially at the dermal–subcutaneous border and periadnexally; lymphocytes, neutrophils, foamy macrophages, poorly developed granulomas; mucin, adipocyte necrosis, microcysts

Needle-shaped clefts are not observed

Lipogranuloma

Sclerosing lipogranuloma – granulomatous lobular panniculitis with marked fibrosis and numerous round or oval vacuoles of various sizes in the dermis and subcutis, producing a “Swiss cheese” appearance (Fig. 100.17); nodular aggregates of lymphocytes, plasma cells, eosinophils, macrophages or giant cells often present Grease gun granuloma – also pseudoepitheliomatous hyperplasia

Exogenous oils within the vacuoles can be identified in frozen sections stained with oil red O, silver bromide and osmium tetroxide; infrared spectroscopy

Injection-induced panniculitis

Central nidus of subcutaneous inflammation; sometimes fibrosis* or polarizing foreign material

Povidone panniculitis – gray–blue material within macrophages on routine staining that also stains with Congo red and chlorazol-fast pink Cancer vaccines, heparin – eosinophils may be numerous

Panniculitis due to aluminum in hyposensitization vaccines

Nonspecific lobular panniculitis with fibrosis; formation of numerous lymphoid follicles; may resemble lupus panniculitis, pseudolymphoma

Macrophages display greyish to violaceous, granular cytoplasm due to lysosomes that contain aluminum salts; can be identified using X-ray microanalysis or possibly aluminum staining

Panniculitis due to injectable aesthetic microimplants

Diffuse granulomatous infiltrate that may involve the dermis and subcutis; focal areas of collagen degeneration

Different “fillers“ can have specific histopathologic features (see Fig. 94.10 & Table 94.4)

Blunt trauma

Organizing hematoma, focal granuloma

Deposits of glycosaminoglycans (mucopolysaccharides) and iron can be seen

Postirradiation or radiation recall panniculitis

Deep fibrosis, mixed inflammation

Inflammation includes lymphocytes, plasma cells, macrophages, eosinophils

*Especially with phytonadione (vitamin K) and pentazocine injections; lipid-containing vacuoles, fat necrosis, foam cells, thrombosis and endarteritis are also observed in the latter. Table 100.10 Microscopic features of traumatic panniculitis.  

Key features ■ Favors the medial aspect of the lower extremities above the malleolus ■ Acute phase with erythema, warmth and tenderness, which may be misdiagnosed as infectious cellulitis ■ Chronic phase with induration and red–brown to violet–brown discoloration ■ Usually develops in the setting of chronic venous insufficiency ■ Both septal and lobular panniculitis; lipomembranous changes are common, particularly in chronic lesions

Introduction Erythema, induration and pigmentary changes have long been known to be associated with venous insufficiency. Because of the variety of clinical appearances and histopathologic findings that can occur at different stages of the disease, a number of diagnostic terms have been employed to explain the changes. Recently, the various manifestations of this panniculitis have been consolidated under the heading of lipodermatosclerosis or sclerosing panniculitis.

History In 1955, Huriez drew attention to a related indurated lesion, which he termed hypodermitis sclerodermiformis137.

Epidemiology 1750

Most patients are women over the age of 40 years, but appearance after the age of 75 years has also been reported138,139.

Pathogenesis There is considerable evidence for venous insufficiency in patients with lipodermatosclerosis140, and fibrinolytic abnormalities are also present in these individuals. Venous hypertension leads to a compromised ability to reduce foot vein pressure during exercise. This results in increased capillary permeability, which causes leakage of fibrinogen, its polymerization to form fibrin cuffs around vessels, impedance of oxygen exchange, and tissue anoxia (see Ch. 105)139. Pericapillary fibrin deposits can be seen in uninvolved, clinically normal extremities of patients with healed venous ulcers of the opposite extremity, suggesting that this abnormality precedes the clinical changes of lipodermatosclerosis141. There may also be an abnormal regulation of angiogenesis within lesions of lipodermatosclerosis. In particular, increased expression of vascular endothelial growth factor receptor 1 (VEGFR-1), which can act as a negative regulator of VEGF-mediated angiogenesis, has been observed, along with increased expression of angiopoietin-2 (Ang-2)142. Additional factors contributing to the pathogenesis of lipodermatosclerosis may include protein C and S deficiencies143, local stimulation of collagen synthesis139, including an increased number of cells expressing procollagen type 1 mRNA144, and obesity.

Clinical features The acute phase of lipodermatosclerosis presents with pain, warmth, erythema and some induration (Fig. 100.18), most often initially on the medial lower leg above the malleolus. Other dependent sites such as the lower aspect of the abdominal pannus can also develop lipodermatosclerosis. At this point, the changes are relatively diffuse139. In the chronic phase, there is marked sclerosis of the dermis and subcutis, resulting in induration that is more sharply demarcated from adjacent normal skin. Hyperpigmentation due to hemosiderin deposition may

CHAPTER

Panniculitis

100

Fig. 100.19 Lipodermatosclerosis. Lipomembranous change, consisting of cystic formation with elaborate papillary configurations.  

A

Membranocystic change is a key feature in lipodermatosclerosis146. This consists of thickened, undulating membranes that form cysts and papillary configurations (Fig. 100.19). The membranes are believed to result from degenerated cell membranes of lipocytes and/or macrophages. The material comprising the membranes is ceroid, an oxidation product of unsaturated fatty acids147. Short, frayed elastic fibers can be present within the subcutaneous septa, and these may be calcified, features that resemble pseudoxanthoma elasticum148. By phosphotungstic acid–hematoxylin stain or by immunofluorescent methods, pericapillary fibrin can also be demonstrated in lesions of lipodermatosclerosis146. Dermal changes include fibrosis, tortuous thick-walled veins, and superficial and deep perivascular inflammation138. Biopsy should be avoided if the diagnosis is obvious, since poor wound healing and ulceration frequently result. When necessary, a thin elliptical excision should be obtained from the margin of a lesion.

Differential diagnosis

B

Fig. 100.18 Lipodermatosclerosis. A Acute phase with tender erythematous plaques on both lower extremities. B Chronic phase with sclerotic red–brown plaque on the lower medial leg. B, Courtesy, Kenneth E Greer, MD.  

Difficulties in clinical diagnosis arise most often in early lesions, when the process is more diffuse and erythematous. At this stage, consideration is often given to cellulitis, erythema nodosum, or erythema induratum138,139,145. Persistence of a lesion, association with stasis changes, and lack of response to antimicrobials suggest the correct diagnosis, perhaps aided by studies of venous function140. As induration develops and progresses, differentiation from morphea and scleromyxedema may be necessary. In morphea, subcutaneous involvement is predominantly septal, and lipophagic and lipodystrophic changes are not as prominent as they are in lipodermatosclerosis138. Membranocystic changes, when present, can be of great diagnostic help; however, these findings can occur in a variety of other conditions, including lupus and dermatomyositis panniculitis, liposarcoma, erythema nodosum, and diabetic dermopathy147.

Treatment also be present138. These features give the affected leg the appearance of an inverted wine bottle145.

Pathology Early lesions show mid-lobular ischemic necrosis, a lymphocytic infiltrate in the septa that rims the fat lobules, variable degrees of capillary congestion and thrombosis, and hemorrhage with hemosiderin deposition. With progression, septal thickening, hyaline sclerosis involving lipocytes, lipophage formation, and mixed inflammatory cell infiltrates appear138. Advanced lesions show marked septal sclerosis and membranocystic change in the face of a marked reduction in inflammation.

Leg elevation and consistent compression therapy are the mainstays of treatment for lipodermatosclerosis139. Traditional anti-inflammatory therapies are usually ineffective in this condition138, although intralesional corticosteroids (e.g. triamcinolone 5–10 mg/cc) may be of benefit when used in conjunction with compression therapy. Good results were reported with the anabolic steroid stanozolol139, especially in the earlier phases of the disease, but this medication is no longer commercially available. As a result, danazol has been used (successfully) as a substitute149. Anabolic steroids enhance fibrinolysis, and they can reduce pain, extent of involvement, and induration of the skin. However, side effects of sodium retention, lipid profile abnormalities, hepatotoxicity, and virilization in women do limit their use. Oxandrolone, an anabolic steroid with less hepatotoxicity and fewer androgenic effects, represents another therapeutic option145.

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16

Other reported treatments include ultrasound, pentoxifylline, fasciotomy, and phlebectomy139,150.

INFECTION-INDUCED PANNICULITIS Synonym:  ■ Infective panniculitis

Key features ■ A wide variety of infectious agents has been reported to produce panniculitis ■ Some degree of immunosuppression is common, but not invariable ■ Histopathologic findings vary, but often include mixed septal/ lobular panniculitis, neutrophilic infiltration, hemorrhage and necrosis ■ Special staining and culture of drainage and tissue can provide a definitive diagnosis

Introduction Panniculitis can result from a distant focus of infection (a classic example being erythema nodosum) or panniculitis can be directly induced by an infectious agent. The latter can produce a variety of clinical and microscopic appearances, although there are some features that infection-induced lesions have in common, regardless of the etiologic agent.

INFECTION-INDUCED PANNICULITIS – REPORTED CAUSATIVE AGENTS

Bacteria Staphylococcus aureus Group A Streptococcus Pseudomonas aeruginosa Brucella melitensis Nocardia asteroides Tropheryma whipplei (causative agent of Whipple disease)

Mycobacteria M. tuberculosis M. marinum, M. avium-intracellulare, M. chelonae, M. fortuitum, M. ulcerans

Coxiella C. burnetii

Borrelia B. burgdorferi

Fungi Blastomyces dermatitidis, Histoplasma capsulatum Microsporum spp. (including M. canis) Candida spp. (including C. albicans) Cryptococcus neoformans Aspergillus spp. (including A. flavus), Mucor or related zygomycetes, Fusarium spp., Aureobasidium pullulans

Helminths & protozoa Nematodes (Gnathostoma spp.) Trematodes (Fasciola hepatica, Schistosoma spp.)

Table 100.11 Infection-induced panniculitis – reported causative agents.  

History While multiple reports of panniculitis directly caused by infectious agents have been published151,152, most early studies of deep skin infections did not focus upon the changes in the subcutaneous fat. In 1989, Patterson et al.23 studied 15 cases of infection-induced panniculitis, with an emphasis upon the histopathologic features in the subcutis. Since that time, additional reports of panniculitis due to infection have continued to appear.

Epidemiology There appears to be no age, gender or racial predilection among cases of infection-induced panniculitis. Many of these patients are immunosuppressed23 or have predisposing medical conditions such as diabetes mellitus151.

Pathogenesis In this group of disorders, infectious agents are considered to be directly responsible for the panniculitis. Examples of reported microorganisms to date are listed in Table 100.1123,151–165b. Involvement of the subcutis can result from direct inoculation or septicemia. Other potential modes of spread include transfascial from an enteric source, in the case of abdominal panniculitis158, or via “persorption”, a proposed mechanism by which Candida migrates across intact endothelium from the gut to a subcutaneous site159. Immunosuppression is common, but not invariable, among individuals with infection-induced panniculitis.

Clinical features Patients develop local swelling and erythema. There may be one or more fluctuant nodules that ulcerate and drain. Lesions on the legs and feet are common, but other sites of involvement include the gluteal region, abdomen, axillae, arm or hand. Underlying conditions include diabetes mellitus, leukemias or solid tumors, autoimmune connective tissue disease, AIDS, and organ transplantation.

Pathology 1752

Individual cases can mimic other primary forms of panniculitis. Common changes (regardless of the infectious agent) include a mixed

Fig. 100.20 Infection-induced panniculitis. Bacterial panniculitis, showing heavy neutrophilic infiltration, basophilic necrosis, vascular proliferation and hemorrhage.  

septal/lobular panniculitis, neutrophilic infiltration, vascular proliferation, hemorrhage, and necrosis that involves lipocytes, inflammatory cells and eccrine sweat coils23 (Fig. 100.20). In Q fever due to Coxiella burnetii, there may be a “doughnut-like” granulomatous lobular panniculitis, in which fibrin and inflammatory cells form a ring around a central clear space; similar changes have been found in the liver and bone marrow of patients with Q fever154.

Differential diagnosis Fluctuant, ulcerating nodules also occur in pancreatic panniculitis, traumatic panniculitis, and alpha-1 antitrypsin deficiency panniculitis. Clinical and laboratory data can usually permit distinction. As noted previously, traumatic panniculitis may be accompanied by infection.

CHAPTER

100

Fig. 100.21 Cytophagic histiocytic panniculitis. Subcutaneous nodules with purpura. Courtesy,

Panniculitis



Kenneth E Greer, MD.

Fig. 100.22 Cytophagic histiocytic panniculitis. Macrophages engaged in cytophagic activity. Some of them have the appearance of “bean bag cells”.  

MALIGNANT SUBCUTANEOUS INFILTRATES

Examples of infection-induced panniculitis with predominantly septal involvement or vasculitis could be confused with acute erythema nodosum or erythema induratum, respectively. Panniculitis due to mucormycosis may feature “ghost cells” and granular calcium deposits and thus resemble pancreatic panniculitis; it can also mimic gouty panniculitis due to the presence of intracellular crystalline deposits162. Special stains for organisms and cultures of drainage and tissue are keys to the diagnosis. In one study, special stains were positive for organisms in 14 of 15 cases23.

Treatment Treatment consists of appropriate antimicrobial therapy. Surgery may be indicated for isolated lesions caused by grain-forming fungi or bacteria, such as mycetoma or botryomycosis153. A more radical surgical approach has been used successfully in treating abdominal panniculitis due to enteric bacteria158.

Malignant infiltrates may involve the subcutis, mimicking the clinical and microscopic appearance of panniculitis. The best known of these is subcutaneous panniculitis-like T-cell lymphoma (see Ch. 120). While cytophagia can be seen in the latter disorder, it is particularly characteristic of subcutaneous involvement of primary cutaneous γ/δ T-cell lymphoma and EBV-associated extranodal NK/T-cell lymphoma, nasal type (see above). Other lymphomas (e.g. B-cell), leukemias, and metastatic solid tumors may infiltrate the subcutis. For example, a case of melanophagic panniculitis that obscured foci of metastatic melanoma has been reported171. Obviously, clinical information is crucial in such cases. Histopathologic clues include the recognition of significant pleomorphism or monotony among infiltrating cells in the subcutis, infiltration between collagen bundles of the dermis or around adnexal structures, and supporting immunohistochemical studies. Of note, the diagnosis of subcutaneous panniculitis-like T-cell lymphoma can sometimes be elusive as the initial impression may be lupus panniculitis (see Table 100.9) or even a nonspecific panniculitis with lipomembranous changes172.

CYTOPHAGIC HISTIOCYTIC PANNICULITIS

UNUSUAL OR NEWLY DESCRIBED FORMS OF PANNICULITIS

The term “cytophagic histiocytic panniculitis” (CHP) has been used to describe subcutaneous nodules or plaques that on histiologic examination show infiltrates of macrophages containing erythrocytes, lymphocytes and/or karyorrhectic debris, i.e. exhibiting hemophagocytosis (Figs 100.21 & 100.22)166. These macrophages with cytophagic activity have been referred to as “bean bag” cells. With the advent of immunophenotyping and genetic techniques, it has become apparent that the vast majority of patients have lymphoma, with atypical lymphoid cells also present within the panniculus167. In general, the lymphomas represent subcutaneous involvement of primary cutaneous γ/δ T-cell lymphoma or EBV-associated extranodal NK/T-cell lymphoma, nasal type (see Ch. 120)168. Occasionally, patients have subcutaneous panniculitis-like T-cell lymphoma, and, rarely, no lymphoma169. Individuals in the latter group may still have a fatal course due to a hemophagocytic syndrome that involves the liver, spleen and bone marrow (leading to pancytopenia). Mutations in a number of genes can predispose individuals to the development of hemophagocytic syndrome, including that which encodes perforin (see Table 91.1). Of note, a child with microscopic findings of CHP but no evidence of lymphoma was found to have a heterozygous nonsense mutation in the gene that encodes perforin170.

Table 100.12 lists several more recently described or unusual forms of panniculitis155,173–182. When a patient presents with panniculitis that is not readily classifiable, it may be worthwhile to consider these alternative diagnoses. Several of them probably do not actually represent distinct entities but rather, overarching terms that include established forms of panniculitis. For example, plasma cell panniculitis could include not only morphea and postirradiation pseudosclerodermatous panniculitis but also other autoimmune connective tissue diseases or infectious diseases. The fasciitis–panniculitis syndrome is a term that has appeared from time to time, primarily in the non-dermatology literature. While sometimes discussed as if it were a single entity, fasciitis–panniculitis syndrome has been used to include eosinophilic fasciitis, morphea profunda, lupus panniculitis, lipodermatosclerosis, and a variety of other conditions. Sweet syndrome and Lyme disease are established entities that can occasionally have panniculitis as a significant finding. Two other more recently described conditions, atypical lymphocytic lobular panniculitis and panniculitic bacterid, may require further study and experience before being widely accepted as distinct entities. No doubt this list will change as disease mechanisms are better understood and disorders are reclassified or absorbed into other classification schemes.

1753

SECTION

Disorders of Subcutaneous Fat

16

UNUSUAL OR RECENTLY DESCRIBED FORMS OF PANNICULITIS

Type of panniculitis

Clinical features

Microscopic findings

Comments

Crystal deposition panniculitis

Red nodules, sometimes with necrosis; may have drainage; legs and elsewhere

Necrotizing and/or granulomatous panniculitis; calcium oxalate crystals in subcutaneous vessels; subcutaneous deposits of sodium urate crystals

Oxalosis: primary (inherited) or secondary (chronic renal failure) Urate deposition: may be an isolated cutaneous finding in gout

Idiopathic palmoplantar hidradenitis (see Ch. 39)

Sudden onset of painful erythematous nodules; soles > palms Self-limited

Neutrophilic eccrine hidradenitis

Precipitated by trauma (mechanical, thermal) Mimicked by erythema nodosum, pseudomonas hot-foot syndrome, cold panniculitis

Sweet panniculitis (subcutaneous Sweet syndrome)*

Erythematous nodules that may be painful; extremities; associated with leukemias (e.g. AML, hairy cell leukemia), treatment of acute promyelocytic leukemia with all-trans-retinoic acid, and, rarely, solid tumors

Predominantly neutrophilic lobular panniculitis, without vasculitis; immature myeloid forms have been described

Must exclude other neutrophil-rich forms of panniculitis, such as infection-induced, traumatic, alpha-1 antitrypsin deficiency and pancreatic panniculitides

Panniculitic bacterid

Sudden onset of tender subcutaneous nodules; lower extremities; polyclonal hypergammaglobulinemia, cold agglutinins, cryofibrinogens

Lobular panniculitis, predominantly neutrophils with microabscesses; angiopathy; extravascular granulomas

Triggered by non-tuberculous infections; underlying disorders include atopy, antiphospholipid antibody syndrome

Plasma cell panniculitis

Hyperpigmentation and induration; trunk and extremities

Sclerosis of subcutaneous septa; plasma cells prominent component of infiltrate

Not a single entity; manifestation of morphea profunda, other autoimmune connective tissue disorders, and postirradiation pseudosclerodermatous panniculitis

Panniculitis of Lyme disease

Tender nodules or diffuse fasciitis; fever, chills, photophobia, polyarthritis

Acute septal panniculitis; may contain eosinophils, plasma cells; lymphocytic vasculopathy

Detection of Borrelia spp. in tissues; positive serologies confirm the diagnosis

Fasciitis–panniculitis syndrome

Subcutaneous induration, sometimes with regional pain

Chronic inflammation, accompanied by replacement of fat lobules by fibrous tissue; thickening of fascia

Term used primarily in the rheumatologic literature; encompasses several autoimmune connective tissue diseases; also described as a paraneoplastic syndrome with hematologic, pancreatic and gastrointestinal malignancies

Atypical lymphocytic lobular panniculitis

Recurrent, infiltrative plaques; lower extremities, abdomen

Interstitial subcutaneous infiltrate with well-differentiated lymphocytes; no significant fat necrosis

Molecular studies show clonal or oligoclonal profile; no progression to lymphoma; considered T-cell dyscrasia

Infantile-onset panniculitis with uveitis and systemic granulomatosis

High fever, anemia, hepatosplenomegaly, uveitis, arthritis

Histiocytic lobular panniculitis, with lymphocytes and neutrophils initially; granulomas in later stage

Resemblance to Blau syndrome, but lacks NOD2/CARD15 mutations; may respond to TNF inhibitors

*Neutrophilic panniculitis also may precede the lipodystrophy of proteasome-associated autoinflammatory syndrome/CANDLE (chronic atypical neutrophilic dermatosis with lipodystrophy and elevated temperature) syndrome (see Table 45.7).

Table 100.12 Unusual or recently described forms of panniculitis. AML, acute myelogenous leukemia; TNF, tumor necrosis factor.  

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100 Panniculitis

effect mimicking subcutaneous melanoma metastasis. J Eur Acad Dermatol Venereol 2015;29:392–3. 14b.  Ramani NS, Curry JL, Kapil J, et al. Panniculitis with necrotizing granulomata in a patient on BRAF inhibitor (Dabrafenib) therapy for metastatic melanoma. Am J Dermatopathol 2015;37:e96–9. 15. Hanauer SB. How do I treat erythema nodosum, aphthous ulcerations, and pyoderma gangrenosum? Inflamm Bowel Dis 1998;4:70, discussion 73. 16. Arsura EL, Kilgore WB, Ratnayake SN. Erythema nodosum in pregnant patients with coccidioidomycosis. Clin Infect Dis 1998;27:1201–3. 17. Thurber S, Kohler S. Histopathologic spectrum of erythema nodosum. J Cutan Pathol 2006;33:18–26. 18. Winkelmann RK, Frigas E. Eosinophilic panniculitis: a clinicopathologic study. J Cutan Pathol 1986;13: 1–12. 19. Egawa T, Okuyama R, Tagami H, et al. Erythema nodosum with eosinophilic panniculitis. Int J Dermatol 2010;49:965–7. 20. Misago N, Tada Y, Koarada S, et al. Erythema nodosum-like lesions in Behçet’s disease: a clinicopathological study of 26 cases. Acta Derm Venereol 2012;92:681–6. 21. Sanchez Yus E, Sanz Vico MD, de Diego V. Miescher’s radial granuloma. A characteristic marker of erythema nodosum. Am J Dermatopathol 1989;11:434–42. 22. Ball NJ, Adams SP, Marx LH, et al. Possible origin of pancreatic fat necrosis as a septal panniculitis. J Am Acad Dermatol 1996;34:362–4. 23. Patterson JW, Brown PC, Broecker AH. Infectioninduced panniculitis. J Cutan Pathol 1989;16:183–93. 24. Horio T, Imamura S, Danno K, et al. Potassium iodide in the treatment of erythema nodosum and nodular vasculitis. Arch Dermatol 1981;117:29–31. 25. Banks PA, Present DH. Treatment of erythema nodosum, aphthous stomatitis, and pyoderma gangrenosum in patients with IBD. Inflamm Bowel Dis 1998;4:73. 26. Boyd AS. Etanercept treatment of erythema nodosum. Skinmed 2007;6:197–9. 27. Rosen T, Martinelli P. Erythema nodosum associated with infliximab therapy. Dermatol Online J 2008;14:3. 28. Rajakulendran S, Deighton C. Adverse dermatological reactions in rheumatoid arthritis patients treated with etanercept, an anti-TNFalpha drug. Curr Drug Saf 2006;1:259–64. 29. Benitez-Gutierrez L, Tutor-de Ureta P, Mellor-Pita S, et al. Refractory chronic erythema nodosum treated with adalimumab. Rev Clin Esp 2013;213:466–7. 30. Bafverstedt B. Erythema nodosum migrans. Acta Derm Venereol 1954;34:181–93. 31. Vilanova X, Piñol Aguade J. Subacute nodular migratory panniculitis. Br J Dermatol 1959;71:45–50. 32. de Almeida Prestes C, Winkelmann RK, Su WP. Septal granulomatous panniculitis: comparison of the pathology of erythema nodosum migrans (migratory panniculitis) and chronic erythema nodosum. J Am Acad Dermatol 1990;22:477–83. 33. Ross M, White GM, Barr RJ. Erythematous plaque on the leg. Vilanova’s disease (subacute nodular migratory panniculitis). Arch Dermatol 1992;128:1644– 5, 1647. 34. Su WP, Person JR. Morphea profunda. A new concept and a histopathologic study of 23 cases. Am J Dermatopathol 1981;3:251–60. 35. Winkelmann RK. Panniculitis in connective tissue disease. Arch Dermatol 1983;119:336–44. 36. Peters MS, Su WP. Eosinophils in lupus panniculitis and morphea profunda. J Cutan Pathol 1991;18:189–92. 37. Fleischmajer R, Damiano V, Nedwich A. Alteration of subcutaneous tissue in systemic scleroderma. Arch Dermatol 1972;105:59–66. 38. Vincent F, Prokopetz R, Miller RA. Plasma cell panniculitis: a unique clinical and pathologic presentation of linear scleroderma. J Am Acad Dermatol 1989;21:357–60. 39. Fleischmajer R, Nedwich A. Generalized morphea. I. Histology of the dermis and subcutaneous tissue. Arch Dermatol 1972;106:509–14. 40. Eriksson S. Alpha 1-antitrypsin deficiency: lessons learned from the bedside to the gene and back again. Historic perspectives. Chest 1989;95:181–9. 41. O’Riordan K, Blei A, Rao MS, et al. Alpha 1-antitrypsin deficiency-associated panniculitis: resolution with intravenous alpha 1-antitrypsin administration and liver transplantation. Transplantation 1997;63:480–2. 42. Pittelkow MR, Smith KC, Su WP. Alpha-1-antitrypsin deficiency and panniculitis. Perspectives on disease

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Disorders of Subcutaneous Fat

16

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93. Roenigk HH Jr, Haserick JR, Arundell FD. Poststeroid panniculitis. Arch Dermatol 1964;90:387–91. 94. Kim ST, Kim TK, Lee JW, et al. Post-steroid panniculitis in an adult. J Dermatol 2008;35:786–8. 95. Marovt M, Miljkovic J. Post-steroid panniculitis in an adult. Acta Dermatovenerol Alp Pannonica Adriat 2012;21:77–8. 96. Silverman RA, Newman AJ, LeVine MJ, et al. Poststeroid panniculitis: a case report. Pediatr Dermatol 1988;5:92–3. 97. Nitta Y. Lupus erythematosus profundus associated with neonatal lupus erythematosus. Br J Dermatol 1997;136:112–14. 98. Peters MS, Su WP. Lupus erythematosus panniculitis. Med Clin North Am 1989;73:1113–26. 99. Martens PB, Moder KG, Ahmed I. Lupus panniculitis: clinical perspectives from a case series. J Rheumatol 1999;26:68–72. 100. Riccieri V, Sili Scavalli A, Spadaro A, et al. Lupus erythematosus panniculitis: an immunohistochemical study. Clin Rheumatol 1994;13:641–4. 101. Burrows NP, Walport MJ, Hammond AH, et al. Lupus erythematosus profundus with partial C4 deficiency responding to thalidomide. Br J Dermatol 1991;125:62–7. 102. Wenzel J, Proelss J, Wiechert A, et al. CXCR3-mediated recruitment of cytotoxic lymphocytes in lupus erythematosus profundus. J Am Acad Dermatol 2007;56:648–50. 103. Chiesa-Fuxench ZC, Kim EJ, Schaffer A, et al. Linear lupus panniculitis of the scalp presenting as alopecia along Blaschko’s lines: a variant of lupus panniculitis not unique to East Asians. J Dermatol 2013;40:231–2. 104. Chung HS, Hann SK. Lupus panniculitis treated by a combination therapy of hydroxychloroquine and quinacrine. J Dermatol 1997;24:569–72. 105. Ng PP, Tan SH, Tan T. Lupus erythematosus panniculitis: a clinicopathologic study. Int J Dermatol 2002;41:488–90. 106. Sanchez NP, Peters MS, Winkelmann RK. The histopathology of lupus erythematosus panniculitis. J Am Acad Dermatol 1981;5:673–80. 107. Pincus LB, LeBoit PE, McCalmont TH, et al. Subcutaneous panniculitis-like T-cell lymphoma with overlapping clinicopathologic features of lupus erythematosus: coexistence of 2 entities? Am J Dermatopathol 2009;31:520–6. 108. Bosisio F, Boi S, Caputo V, et al. Lobular panniculitic infiltrates with overlapping histopathologic features of lupus panniculitis (lupus profundus) and subcutaneous T-cell lymphoma: a conceptual and practical dilemma. Am J Surg Pathol 2015;39:206–11. 109. Espirito Santo J, Gomes MF, Gomes MJ, et al. Intravenous immunoglobulin in lupus panniculitis. Clin Rev Allergy Immunol 2010;38:307–18. 110. Lee MW, Lim YS, Choi JH, et al. Panniculitis showing membranocystic changes in the dermatomyositis. J Dermatol 1999;26:608–10. 111. Solans R, Cortes J, Selva A, et al. Panniculitis: a cutaneous manifestation of dermatomyositis. J Am Acad Dermatol 2002;46:S148–50. 112. Molnar K, Kemeny L, Korom I, et al. Panniculitis in dermatomyositis: report of two cases. Br J Dermatol 1998;139:161–3. 113. Lemez L. Beitrag zur Pathogenese der subcutanen Fettgewebsnekrose Neugeborener (Sog. Sclerodermia neonatorum) an der Hand. Einer Kalterreaktion des subcutanen Fettgewebes bei Neugeborenen und jungen Sauglingen. Zeitung der Kinderheilkunden; 1928. p. 46. 114. Epstein EH Jr, Oren ME. Popsicle panniculitis. N Engl J Med 1970;282:966–7. 115. Behar TA, Anderson EE, Barwick WJ, et al. Sclerosing lipogranulomatosis: a case report of scrotal injection of automobile transmission fluid and literature review of subcutaneous injection of oils. Plast Reconstr Surg 1993;91:352–61. 116. Beacham BE, Cooper PH, Buchanan CS, et al. Equestrian cold panniculitis in women. Arch Dermatol 1980;116:1025–7. 117. Oertel YC, Johnson FB. Sclerosing lipogranuloma of male genitalia. Review of 23 cases. Arch Pathol Lab Med 1977;101:321–6. 118. Carrasco L, Moreno C, Pastor MA, et al. Postirradiation pseudosclerodermatous panniculitis. Am J Dermatopathol 2001;23:283–7. 119. Borroni G, Vassallo C, Brazzelli V, et al. Radiation recall dermatitis, panniculitis, and myositis following cyclophosphamide therapy: histopathologic findings

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of a patient affected by multiple myeloma. Am J Dermatopathol 2004;26:213–16. Rajkumar SV, Laude TA, Russo RM, et al. Popsicle panniculitis of the cheeks. A diagnostic entity caused by sucking on cold objects. Clin Pediatr (Phila) 1976;15:619–21. Pang BK, Munro V, Kossard S. Pseudoscleroderma secondary to phytomenadione (vitamin K1) injections: Texier’s disease. Australas J Dermatol 1996;37:44–7. Baars JW, Coenen JL, Wagstaff J, et al. Lobular panniculitis after subcutaneous administration of interleukin-2 (IL-2), and its exacerbation during intravenous therapy with IL-2. Br J Cancer 1992;66:698–9. Garcia-Domingo MI, Alijotas-Reig J, Cistero-Bahima A, et al. Disseminated and recurrent sarcoid-like granulomatous panniculitis due to bovine collagen injection. J Investig Allergol Clin Immunol 2000;10:107–9. Tan J, Rao B. Mesotherapy-induced panniculitis treated with dapsone: case report and review of reported adverse effects of mesotherapy. J Cutan Med Surg 2006;10:92–5. Jeong KH, Lee MH. Two cases of factitial panniculitis induced by electroacupuncture. Clin Exp Dermatol 2009;34:e170–3. Winkelmann RK, Barker SM. Factitial traumatic panniculitis. J Am Acad Dermatol 1985;13:988–94. Foucar E, Downing DT, Gerber WL. Sclerosing lipogranuloma of the male genitalia containing vitamin E: a comparison with classical ‘paraffinoma’. J Am Acad Dermatol 1983;9:103–10. Takihara H, Takahashi M, Ueno T, et al. Sclerosing lipogranuloma of the male genitalia: analysis of the lipid constituents and histological study. Br J Urol 1993;71:58–62. Henrichs WD, Helwig EB. Grease gun granulomas. Mil Med 1986;151:78–82. Lee JH, Jung KE, Kim HS, et al. Traumatic panniculitis with localized hypertrichosis: two new cases and considerations. J Dermatol 2013;40:139–41. Kaufman HL, Harandi A, Watson MC, et al. Panniculitis after vaccination against CEA and MUC1 in a patient with pancreatic cancer. Lancet Oncol 2005;6:62–3. Chong H, Brady K, Metze D, Calonje E. Persistent nodules at injection sites (aluminum granuloma) – clinicopathological study of 14 cases with a diverse range of histological reaction patterns. Histopathology 2006;48:182–8. Requena C, Izguierdo MJ, Navarro M, et al. Adverse reactions to injectable aesthetic microimplants. Am J Dermatopathol 2001;23:197–202. Claudy A, Garcier F, Schmitt D. Sclerosing lipogranuloma of the male genitalia: ultrastructural study. Br J Dermatol 1981;105:451–6. Wortsman X, Wortsman J, Orlandi C, et al. Ultrasound detection and identification of cosmetic fillers in the skin. J Eur Acad Dermatol Venereol 2012;26:292–301. Oh C, Ginsberg-Fellner F, Dolger H. Factitial panniculitis and necrotizing fasciitis in juvenile diabetes. Diabetes 1975;24:856–8. Huriez C. Ulceres de jambes et troubles trophiques d’origine veineuse (donnes tirees de l’etude d’un millier d’ulcereux hospitalises). Rev Pract 1955;5:2703–21. Jorizzo JL, White WL, Zanolli MD, et al. Sclerosing panniculitis. A clinicopathologic assessment. Arch Dermatol 1991;127:554–8. Kirsner RS, Pardes JB, Eaglstein WH, et al. The clinical spectrum of lipodermatosclerosis. J Am Acad Dermatol 1993;28:623–7. Greenberg AS, Hasan A, Montalvo BM, et al. Acute lipodermatosclerosis is associated with venous insufficiency. J Am Acad Dermatol 1996;35:566–8. Stacey MC, Burnand KG, Bhogal BS, et al. Pericapillary fibrin deposits and skin hypoxia precede the changes of lipodermatosclerosis in limbs at increased risk of developing a venous ulcer. Cardiovasc Surg 2000;8:372–80. Herouy Y, Kreis S, Mueller T, et al. Inhibition of angiogenesis in lipodermatosclerosis: implication for venous ulcer formation. Int J Mol Med 2009;24:645–51. Falanga V, Bontempo FA, Eaglstein WH. Protein C and protein S plasma levels in patients with lipodermatosclerosis and venous ulceration. Arch Dermatol 1990;126:1195–7. de Giorgio-Miller AM, Treharne LJ, McAnulty RJ, et al. Procollagen type I gene expression and cell

proliferation are increased in lipodermatosclerosis. Br J Dermatol 2005;152:242–9. 145. Segal S, Cooper J, Bolognia J. Treatment of lipodermatosclerosis with oxandrolone in a patient with stanozolol-induced hepatotoxicity. J Am Acad Dermatol 2000;43:558–9. 146. Alegre VA, Winkelmann RK, Aliaga A. Lipomembranous changes in chronic panniculitis. J Am Acad Dermatol 1988;19:39–46. 147. Ishikawa O, Tamura A, Ryuzaki K, et al. Membranocystic changes in the panniculitis of dermatomyositis. Br J Dermatol 1996;134:773–6. 148. Walsh SN, Santa Cruz DJ. Lipodermatosclerosis: a clinicopathologic study of 25 cases. J Am Acad Dermatol 2010;62:1005–12. 149. Hafner C, Wimmershoff M, Landthaler M, Vogt T. Lipodermatosclerosis: successful treatment with danazol. Acta Derm Venereol 2005;85:365–6. 150. Goldman MP. The use of pentoxifylline in the treatment of systemic sclerosis and lipodermatosclerosis: a unifying hypothesis? J Am Acad Dermatol 1994;31:135–6. 151. Maioriello RP, Merwin CF. North American blastomycosis presenting as an acute panniculitis and arthritis. Arch Dermatol 1970; 102:92–6. 152. Sanderson TL, Moskowitz L, Hensley GT, et al. Disseminated Mycobacterium avium-intracellulare infection appearing as a panniculitis. Arch Pathol Lab Med 1982;106:112–14. 153. Farnsworth GA. Case for diagnosis. Panniculitis, pyogranulomatous, diffuse, severe, with numerous fungal aggregates; etiology consistent with deep dermatophytosis. Mil Med 1990;155:618, 622. 154. Galache C, Santos-Juanes J, Blanco S, et al. Q fever: a new cause of ‘doughnut’ granulomatous lobular panniculitis. Br J Dermatol 2004;151:685–7. 155. Kramer N, Rickert RR, Brodkin RH, Rosenstein ED. Septal panniculitis as a manifestation of Lyme disease. Am J Med 1986;81:149–52. 156. Paredes CJ, Del Gordo EC, Torrado E, et al. Chronic septal panniculitis caused by Phaeohyphomycosis. J Clin Rheumatol 1998;4:323–7. 157. Ollague Torres JM, Ollague Loaiza W. Histologic chronology of eosinophilic migratory nodular panniculitis (gnathostomiasis). Med Cutan Ibero Lat Am 1987;15:85–8. 158. Nauta RJ. A radical approach to bacterial panniculitis of the abdominal wall in the morbidly obese. Surgery 1990;107:134–9. 159. Ginter G, Rieger E, Soyer HP, et al. Granulomatous panniculitis caused by Candida albicans: a case presenting with multiple leg ulcers. J Am Acad Dermatol 1993;28:315–17. 160. Canal L, Fuente Dde L, Roriguez-Moreno J, et al. Specific cutaneous involvement in Whipple disease. Am J Dermatopathol 2014;36:344–6. 161. Al Jasser M, Al Ajrouish W. Brucellosis presenting as septal panniculitis with vasculitis. Int J Dermatol 2012;51:1526–9. 162. Requena L, Sitthinamsuwan P, Santonja C, et al. Cutaneous and mucosal mucormycosis mimicking pancreatic panniculitis and gouty panniculitis. J Am Acad Dermatol 2012;66:975–84. 163. Diallo M, Niang SO, Faye PM, et al. Schistosomainduced granulomatous panniculitis. An unusual presentation of cutaneous schistosomiasis. Ann Dermatol Venereol 2012;139:132–6. 164. Sharquie KE, Hameed AF. Panniculitis is an important feature of cutaneous leishmaniasis pathology. Case Rep Dermatol Med 2012;2012:612434. 165. Lencastre A, Joao A, Lopes MJ. Panniculitis in the setting of visceral leishmaniasis. Acta Med Port 2011;24:649–52. 165a.  Sharquie KE, Hameed AF, Noaimi AA. Panniculitis is a common unrecognized histopathological feature of cutaneous leishmaniasis. Indian J Pathol Microbiol 2016;59:16–19. 165b.  Drago F, Ciccarese G, Tomasini CF, et al. First report of tertiary syphilis presenting as lipoatrophic panniculitis in an immunocompetent patient. Int J STD AIDS 2017;28:408–10. 166. Winkelmann RK, Bowie EJ. Hemorrhagic diathesis associated with benign histiocytic, cytophagic panniculitis and systemic histiocytosis. Arch Intern Med 1980;140:1460–3. 167. Wick MR, Patterson JW. Cytophagic histiocytic panniculitis – a critical reappraisal. Arch Dermatol 2000;136:922–4.

173. Buezo GF, Requena L, Fraga Fernandez J, et al. Idiopathic palmoplantar hidradenitis. Am J Dermatopathol 1996;18:413–16. 174. Rabinowitz LG, Cintra ML, Hood AF, Esterly NB. Recurrent palmoplantar hidradenitis in children. Arch Dermatol 1995;131:817–20. 175. Tomb R, Soutou B, Chehadi S. Plasma cell panniculitis: a histopathological variant of morphea profunda. Ann Dermatol Venereol 2009;136:256–9. 176. Wouters CH, Martin TM, Stichweh D, et al. Infantile onset panniculitis with uveitis and systemic granulomatosis: a new clinicopathologic entity. J Pediatr 2007;151:707–9. 177. Magro CM, Schaefer JT, Morrison C, et al. Atypical lymphocytic lobular panniculitis: a clonal subcutaneous T-cell dyscrasia. J Cutan Pathol 2008;35:947–54. 178. Magro CM, Drysen ME, Crowson AN. Acute infectious id panniculitis/panniculitic bacterid: a distinctive form of neutrophilic lobular panniculitis. J Cutan Pathol 2008;35:941–6.

179. Somach SC, Davis BR, Paras FA, et al. Fatal cutaneous necrosis mimicking calciphylaxis in a patient with type 1 primary hyperoxaluria. Arch Dermatol 1995;131:821–3. 180. LeBoit PE, Schneider S. Gout presenting as lobular panniculitis. Am J Dermatopathol 1987;9:334–8. 181. Jagdeo J, Campbell R, Long T, et al. Sweet’s syndrome-like neutrophilic lobular panniculitis associated with chemotherapy in a patient with acute promyelocytic leukemia. J Am Acad Dermatol 2007;56:690–3. 182. Naschitz JE, Yeshurun D, Zuckerman E, et al. The fasciitis-panniculitis syndrome: clinical spectrum and response to cimetidine. Semin Arthritis Rheum 1992;21:211–20. 183. Massone C, Kodama K, Salmhofer W, et al. Lupus erythematosus panniculitis (lupus profundus): clinical, histopathological, and molecular analysis of nine cases. J Cutan Pathol 2005;32:396–404.

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168. Willemze R, Jaffe ES, Burg G, et al. WHO-EORTC classification for cutaneous lymphomas. Blood 2005;105:3768–85. 169. Craig AJ, Cualing H, Thomas G, et al. Cytophagic histiocytic panniculitis – a syndrome associated with benign and malignant panniculitis: case comparison and review of the literature. J Am Acad Dermatol 1998;39:721–36. 170. Chen RL, Hsu YH, Ueda I, et al. Cytophagic histiocytic panniculitis with fatal haemophagocytic lymphohistiocytosis in a paediatric patient with perforin gene mutation. J Clin Pathol 2007;60: 1168–9. 171. Pierard GE. Melanophagic dermatitis and panniculitis. A condition revealing an occult metastatic malignant melanoma. Am J Dermatopathol 1988;10:133–6. 172. Weenig RH, Ng CS, Perniciaro C. Subcutaneous panniculitis-like T-cell lymphoma: an elusive case presenting as lipomembranous panniculitis and a review of 72 cases in the literature. Am J Dermatopathol 2001;23:206–15.

1757

SECTION 16 DISORDERS OF SUBCUTANEOUS FAT

101 

Lipodystrophies Suat Hoon Tan, Mark Boon Yang Tang and Hong Liang Tey

Synonyms:  ■ Lipodystrophy: lipoatrophy, lipohypertrophy

Key features ■ Lipodystrophies are inherited or acquired disorders characterized by a paucity or complete absence of fat that may be generalized, partial or localized; lipohypertrophy may accompany the lipoatrophy ■ Though the terms lipodystrophy and lipoatrophy are often used interchangeably, lipoatrophy should be used specifically for selective loss of fat, with lipodystrophy implying a redistribution of fat, in part due to a hypertrophic compensation of the nonatrophic fat ■ Lipodystrophy syndromes represent a heterogeneous group of disorders that are characterized by lipoatrophy ± fat accumulation in characteristic body distribution patterns ■ Fat is a metabolically active organ, thus fat loss can be associated with metabolic derangements, which parallel the extent and duration of lipoatrophy ■ Patients with lipodystrophy typically develop the metabolic syndrome, which includes insulin resistance, diabetes mellitus, hyperinsulinemia, dyslipidemia, cardiovascular disease and hepatic steatosis ■ Systemic manifestations of generalized and partial lipodystrophy syndromes include medical complications of the metabolic syndrome, hormonal abnormalities, organ dysfunction, anabolic features, glomerulonephritis, and autoimmune disorders ■ A distinct syndrome of peripheral lipoatrophy, central obesity, breast hypertrophy, dorsocervical fat pad enlargement, hyperlipidemia and insulin resistance occurs in patients with HIV infection undergoing treatment with antiretroviral therapy (ART; formerly referred to as highly active antiretroviral therapy [HAART]) ■ Isolated or localized lipoatrophy can occur at the site of medication injection, trauma or pressure, in association with autoimmune connective tissue disease, or following certain panniculitic inflammatory or neoplastic processes ■ Microscopically, there may be a complete absence of subcutaneous fat or a decrease in adipocyte size and number. An inflammatory panniculitis may be seen in early disease

INTRODUCTION

1758

Lipodystrophy is the term that describes a heterogeneous group of diseases characterized by a selective fat loss in a characteristic body distribution pattern that is often accompanied by secondary fat accumulation. Adipose tissue has crucial metabolic and endocrine functions, in addition to having a role in mechanical protection. The loss of peripheral subcutaneous fat and a compensatory accumulation of visceral fat is closely associated with insulin resistance, diabetes mellitus, dyslipidemia, hypertension, and coronary artery disease. These metabolic abnormalities and their sequelae are now referred to as the metabolic syndrome and they underscore the important functions of fat, in its role as a diverse and crucial body organ. More than a century after the first description of lipodystrophy1 and then delineation of generalized lipodystrophy into congenital and

acquired forms2, the genetic basis of several of the inherited lipodystrophies has now been elucidated. Mutations have been found in genes ranging from those encoding proteins essential for adipocyte differentiation to those encoding nuclear lamins (see below). Clinically, lipodystrophy can be broadly classified into inherited or acquired forms and then further subclassified based on the extent of fat loss, in conjunction with genetic mutations, age of onset, and systemic manifestations (Fig. 101.1 & Table 101.1). Based upon the distribution pattern, lipodystrophy may be subdivided into three major groups: (1) generalized; (2) partial (extensive, but not generalized); and (3) localized (limited to an isolated area). Localized lipodystrophy, which may be due to injections of medications or vaccines, pressure, previous surgery, trauma or panniculitis, is commonly seen. Of the partial lipodystrophies, the one associated with antiretroviral therapy (ART) for HIV infections has become the most common form3. It is important for dermatologists to recognize this drug effect and the associated metabolic syndrome, as there are profound social, psychological, and medical implications. The dermatologist is also likely to occasionally encounter partial lipodystrophy that may be associated with glomerulonephritis or with autoimmune diseases such as dermatomyositis or lupus erythematosus. Finally, there are several rare genetic syndromes that will be discussed (see Table 101.1).

PATHOGENESIS Adipose tissue functions as an endocrine organ via its secretion of hormones and adipocytokines, such as leptin, TNF-α, interleukin (IL)-6, and adiponectin. Altered expression and activity of these factors play a role in the development of insulin resistance and other metabolic changes seen in lipodystrophic syndromes, which are similar to those observed with obesity and the metabolic syndrome4,5. There appears to be a final common pathway of defective adipocyte triglyceride storage in conditions characterized by fat loss as well as fat excess. This defect can result from impaired triglyceride synthesis due to an enzyme deficiency (e.g. 1-acylglycerol-3-phosphate O-acyltransferase 2), defective adipocyte development caused by mutations in genes critical to adipocyte differentiation (e.g. BSCL2/seipin, PPARG, LMNA), adipocyte apoptosis, or autoimmune- or drug-mediated adipocyte destruction. All of these processes can impair normal adipocyte differentiation, development, lifespan, and/or function6. The destruction or impaired differentiation of adipocytes leads to a cascade of hormonal and metabolic consequences. Adiponectin, a product of the ADIPOQ gene, is expressed in and secreted exclusively by differentiated adipocytes. It plays a positive role in regulating insulin sensitivity and glucose and lipid homeostasis. Plasma adiponectin levels are inversely correlated with fasting insulin levels and insulin resistance7. Serum adiponectin and leptin levels are reduced both in murine models of lipoatrophy with insulin resistance and in humans with congenital and acquired lipodystrophies8, including HIV/ARTrelated lipodystrophy9,10. In mouse models with deficient mRNAs encoding leptin, infusion of leptin reverses insulin resistance11. Similarly, leptin replacement was found to result in significant and sustained improvements in hyperglycemia, dyslipidemia, and hepatic steatosis in patients with different forms of lipodystrophy12,13.

Congenital Generalized Lipodystrophy (Berardinelli–Seip Congenital Lipodystrophy, Berardinelli–Seip Syndrome) Congenital generalized lipodystrophy (CGL) is an autosomal recessive disorder with four known genetic subtypes. The two major forms, types

Lipodystrophy is the term that describes a heterogeneous group of diseases characterized by a selective fat loss in a characteristic body distribution pattern that is often accompanied by secondary fat accumulation. The lipodystrophies can be broadly categorized into congenital/inherited and acquired types and then further subdivided into generalized, partial, and localized forms. Examples of inherited disorders are congenital generalized lipodystrophy (Berardinelli–Seip syndrome) and familial partial lipodystrophy while examples of acquired disorders are acquired generalized lipodystrophy and HIV/ART-associated lipodystrophy syndrome. The localized forms of lipoatrophy are most commonly observed and they occur at sites of medication or vaccine injections, pressure or panniculitis.

lipoatrophy, lipohypertrophy, lipodystrophy, fat, adipose, congenital generalized lipodystrophy, familial partial lipodystrophy, acquired generalized lipodystrophy, acquired partial lipodystrophy, CANDLE syndrome, metabolic syndrome, anabolic features, insulin resistance, antiretroviral therapy, HIV/ART-associated lipodystrophy syndrome

CHAPTER

101 Lipodystrophies

ABSTRACT

non-print metadata KEYWORDS:

1758.e1

Localized

Trauma, injections, pressure, AI-CTD Congenital or familial

Generalized (birth)

Partial (puberty)

Generalized (childhood to puberty)

Partial

Partial

Congenital generalized lipodystrophy (Berardinelli–Seip syndrome)

Familial partial lipodystrophy (FPLD)

Acquired generalized lipodystrophy (Lawrence syndrome)

Acquired partial lipodystrophy (Barraquer–Simons syndrome)

HIV/ART-associated lipodystrophy syndrome

Associations: Associations: Diabetes mellitus/IR Diabetes mellitus/IR Hypertriglyceridemia/ Hypertriglyceridemia pancreatitis Liver disease Menstrual irregularity Autoimmune disease Prior panniculitis LMNA, PPARG, PLIN1, (25%)

Associations: Hypocomplementemia C3 nephritic factor Glomerulonephritis Recurrent Neisseria infections

2 months to 2 years after initiation of ART Associations: Insulin resistance Hypertriglyceridemia Cardiovascular disease

Associations: Diabetes mellitus/IR Hypertriglyceridemia/ pancreatitis “Anabolic features” Hypertrophic cardiomyopathy Liver disease Nephropathy Organomegaly Type 2: Loss of palmoplantar fat Type 4: pyloric stenosis AGPAT2, BSCL2, CAV1, CAVIN1/PTRF

CIDEC, LIPE

*

LMNB2

CHAPTER

101 Lipodystrophies

Lipodystrophy

Acquired

Fig. 101.1 Lipodystrophy syndromes and localized forms. Schematic representation of the predominant sites of lipoatrophy and lipohypertrophy. Additional syndromes, including CANDLE and familial partial lipodystrophy with   mandibuloacral dysplasia, are outlined in Table 101.1. Tables 63.9 and 63.10 review progeroid syndromes in which lipoatrophy can be seen. AI-CTD, autoimmune connective tissue disease; ART, antiretroviral therapy; IR, insulin resistance. AGPAT2, encodes 1-acylglycerol-3-phosphate O-acyltransferase 2 (triglyceride and phospholipid synthesis); BSCL2, encodes seipin (lipid droplet formation); CAV1, encodes caveolin 1 (binds fatty acids and translocates them to lipid droplets); CIDEC, encodes cell death-inducing DNA fragmentation factor-like effector C (adipocyte apoptosis); LIPE, encodes lipase E, hormone sensitive type (hydrolysis of triglycerides to free fatty acids); LMNA, encodes lamins A/C (structural integrity of the nuclear lamina); LMNB2, encodes lamin B2 (structural integrity of the nuclear lamina); PLIN1, encodes perilipin 1 (formation, maturation, and function of lipid droplets within adipocytes); PPARG, encodes peroxisome proliferator-activated receptor-gamma (essential role in lipogenesis); CAVIN1/PTRF, encodes caveolae associated protein 1 (biogenesis of caveolae and expression of caveolins 1 and 3).  

LIPODYSTROPHY SYNDROMES AND LOCALIZED FORMS

Lipoatrophy, often with muscular prominence Muscular hypertrophy with lipoatrophy Lipohypertrophy

*Few patients

1 and 2, are due to mutations in AGPAT2, which encodes 1-acylglycerol3-phosphate O-acyltransferase 2, and BSCL2/seipin, respectively (see Table 101.1). It has been postulated that these genetic mutations cause lipodystrophy primarily by affecting adipocyte differentiation or lipid droplet formation in adipose tissue. In type 1, aberrant AGPAT2 enzyme activity causes a marked reduction in triglyceride and phospholipid synthesis, resulting in abnormal adipocyte function14. In type 2, BSCL2 mutations affect the endoplasmic reticulum membrane protein seipin which is critical for lipid droplet morphology. In types 3 and 4 CGL, genetic mutations have been detected that affect the function of caveolae, which are invaginations of the plasma membrane involved in signal transduction and endocytosis, including internalization of the insulin receptor. Patients with type 3 CGL have mutations in CAV1 which encodes caveolin 115; caveolins are essential components of caveolae and caveolin 1 binds fatty acids and translocates them to lipid droplets. Type 4 CGL is due to mutations in CAVIN1/PTRF, whose protein product is involved in the biogenesis of caveolae and the expression of caveolins 1 and 316.

Differences in the molecular basis of CGL may account for the phenotypic heterogeneity17. AGPAT2 has been found to be highly expressed in human omental adipose tissue, which may explain the preferential loss of metabolically active intra-abdominal adipose tissue but preservation of mechanical palmoplantar adipose tissue in patients with type 1 CGL. BSCL2 has been found to also be highly expressed in the brain18, which may account for the higher prevalence of intellectual disability in type 2 patients.

Familial Partial Lipodystrophy Familial partial lipodystrophy (FPLD) is a heterogeneous group of autosomal dominantly and rarely autosomal recessively inherited disorders (see Table 101.1). The most prevalent subtype is the FPLD2, which is due to mutations in LMNA19,20. LMNA encodes lamins A and C, with lamins belonging to the intermediate filament family of structural proteins that compose the nuclear lamina. LMNA mutations lead to disruption of nuclear function, resulting in apoptosis and premature

1759

SECTION

Disorders of Subcutaneous Fat

16

LIPODYSTROPHY SYNDROMES

Age of onset

Sex

Genetics

Congenital generalized lipodystrophy (CGL; Berardinelli– Seip syndrome)

Birth

F = M

Familial partial lipodystrophy (FPLD; previously referred to as Köbberling– Dunnigan syndrome)

Puberty

F > M

Syndrome

Distribution of fat changes

Metabolic derangements

Systemic associations

Systemic complications

AR Type 1: AGPAT2 Type 2: BSCL2/ seipin Type 3: CAV1 Type 4: CAVIN1/PTRF

↓ Fat: face, trunk, extremities, viscera Types 1, 3, 4: loss of metabolically active adipose tissue in the skin and viscera, but preservation of mechanical adipose tissue (palmoplantar, retro-orbital) Type 2: both metabolically active and mechanical adipose tissue are lost Types 1, 2: lack of bone marrow fat Types 3, 4: preserved bone marrow fat

+++: IR, DM, ↑ TG; anabolic features; ↑ metabolic rate

Type 3: associated with vitamin D resistance

Hypertrophic cardiomyopathy, liver failure/ cirrhosis, organomegaly, acute pancreatitis, proteinuric nephropathy (see Table 101.3) More severe disease in type 2, with higher incidence of intellectual disability and cardiomyopathy Type 4: prominent skin veins, cardiac, conduction defects, pyloric stenosis, muscle weakness

AD FPLD1 (Köbberling type): not known FPLD2 (Dunnigan type): LMNA [lamin A/C] FPLD3: PPARG FPLD4: PLIN1

FPLD1: ↓ fat on extremities ± ↑ fat on face/neck, trunk FPLD2: ↓ fat on extremities ± trunk, ↑ fat on face/neck (double chin), muscular hypertrophy FPLD3: ↓ fat on extremities/buttocks (less severe than FPLD2); trunk/ viscera spared FPLD4: ↓ fat on lower extremities with small adipocytes and increased fibrosis of adipose tissues FPLD5: ↓ fat on lower extremities/ buttocks; small, multiloculated lipid droplets histologically FPLD6: ↓ fat on lower extremities, ↑ fat of abdomen and axillae

IR, DM, ↑ TG, ↓ HDL (more severe in FPLD3 than FPLD2)

None preceding

Acute pancreatitis, hepatic steatosis/ cirrhosis, menstrual abnormalities Clinical findings and metabolic complications more severe in women

Inherited

AR* FPLD5: CIDEC FPLD6: LIPE

*Provisional for FPLD5 and FPLD6. Table 101.1 Lipodystrophy syndromes. Patients with POEMS syndrome (polyneuropathy, organomegaly, endocrinopathy, monoclonal gammopathy, and skin changes) can also develop facial lipoatrophy. AR, autosomal recessive; AD, autosomal dominant; AGPAT2, 1-acylglycerol-3-phosphate O-acyltransferase 2; BSCL2, Berardinelli–Seip congenital lipodystrophy 2 (Seipin) gene; CAV1, caveolin 1 gene; CAVIN1, caveolae associated protein 1; CIDEC, cell death-inducing DFFA-like effector C; DM, diabetes mellitus; HDL, high-density lipoproteins; IR, insulin resistance; LIPE, lipase, hormone-sensitive; PLIN, perilipin 1; PPARG, peroxisome proliferator-activated receptor-γ; PTRF, polymerase I and transcript release factor; TG, triglycerides; ZMPSTE24, gene that encodes a zinc metalloproteinase.  

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CHAPTER

Syndrome

Age of onset

Sex

Genetics

Distribution of fat changes

Metabolic derangements

Systemic associations

Systemic complications

Familial partial lipodystrophy with mandibuloacral dysplasia (MAD)

Childhood or puberty

M > F

AR Type A: LMNA Type B: ZMPSTE24

↓ fat on extremities Type B – may have generalized lipodystrophy

IR, DM, ↑ TG, ↓ HDL in some patients

None preceding

Premature aging, hypoplasia of mandible, clavicles and terminal digits, short stature, scleroderma-like skin lesions with mottled skin pigmentation

Autoinflammatory disorders (JMP and CANDLE syndromes)

Childhood

M = F

AR PSMB8

JMP syndrome: ↓ fat: face, upper extremities > generalized CANDLE syndrome: ↓ fat: face, extremities

JMP syndrome: ↓ HDL cholesterol CANDLE syndrome: ↑ TG

None preceding

JMP syndrome: panniculitis precedes lipoatrophy; see text for other findings CANDLE syndrome: atypical neutrophilic dermatosis, progressive lipodystrophy, recurrent fevers; see text for other findings

Acquired generalized lipodystrophy (Lawrence syndrome)

Childhood or adolescence

F > M 3 : 1

None known

↓ Fat: face, trunk, extremities Preservation of fat within the bone marrow

++: IR, DM, ↑ TG (correlates with the degree of lipodystrophy)

1/3 have a preceding autoimmune disease (e.g. juvenile dermatomyositis, Sjögren syndrome) or infection; 25% have a preceding panniculitis

Liver failure/ cirrhosis, proteinuric nephropathy

Acquired partial lipodystrophy (Barraquer–Simons syndrome)

Childhood or adolescence Rarely adults

F > M 3 : 1

Sporadic or AD: LMNB2 (Lamin B2)

↓ Fat: face, upper extremities, trunk, with spread in a cephalocaudal direction Spares lower extremities ↑ Fat: hips and legs Hemilipodystrophic variants

Rare IR, DM, ↑ TG

Often preceded by a febrile illness; 1/5 have mesangiocap­ illary glomeru­ lonephritis Almost all have low levels of C3 and presence of circulating C3 nephritic factor Autoimmune disease associations include SLE, dermatomyositis

Sequelae of renal abnormalities

HIV/ARTassociated lipodystrophy syndrome

2 months to 2 years after initiation of combination antiretroviral therapy (ART) Adults >  children

M = F overall, F > M central adiposity

None known

↓ Fat: face, extremities ↑ Fat: central (trunk/viscera), dorsocervical (“buffalo hump”), breasts Lipomas (e.g. pubic)

++: IR, ↑ TG, ↑ LDL, ↓ HDL; ± DM

HIV infection

Cardiovascular disease

Lipodystrophies

101

LIPODYSTROPHY SYNDROMES

Acquired

Table 101.1 Lipodystrophy syndromes. (cont’d) AR, autosomal recessive; AD, autosomal dominant; CANDLE, chronic atypical neutrophilic dermatosis with lipodystrophy and elevated temperature; DM, diabetes mellitus; HDL, high-density lipoproteins; HIV, human immunodeficiency virus; IR, insulin resistance; JMP, joint contractures, muscle atrophy, microcytic anemia, and panniculitis-induced lipodystrophy; LDL, low-density lipoproteins; PSMB8, proteasome subunit beta 8; SLE, systemic lupus erythematosus; TG, triglycerides.  

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SECTION

Disorders of Subcutaneous Fat

16

cell death of adipocytes. These mutations also alter plasma levels of leptin, with heterozygotes (mutation in one copy of LMNA) having decreased plasma leptin and increased fasting plasma insulin and C-peptide levels21. Of note, LMNA mutations are also responsible for a group of laminopathies that includes muscular dystrophy, cardiomyopathy, neuropathies, and syndromes of premature aging (see Tables 63.9 & 63.10). The clinical phenotype/syndrome is determined by the site and type of LMNA mutations22. The genetic basis of FPLD1 is unknown, but FPLD3 results from heterozygous missense mutations of the gene that encodes peroxisome proliferator-activated receptor-γ (PPARG)23. The PPAR-γ protein plays an essential role in adipogenesis (see Fig. 101.14), but the entire pathogenesis remains unclear. Although this subtype has a milder clinical phenotype than FPLD2, with a later age of onset and involvement confined to the distal extremities, metabolic disturbances are more severe, suggesting that PPARG mutations may have additional direct effects on metabolism. In patients with FPLD4, heterozygous loss-of-function mutations have been described in the gene that encodes perilipin 1 (PLIN1)24,25. Perilipin is responsible for the formation, maturation, and function of lipid droplets within adipocytes. Lipoatrophy of the lower extremities is accompanied by marked hypertriglyceridemia and severe insulin resistance with type 2 diabetes. To date, FPLD5 and FPLD6 are based on a single patient and two siblings, respectively, and because of homozygous missense mutations (FPLD5) and consanguinity (FPLD6), an autosomal recessive pattern is favored. The associated genes encode a member of the cell deathinducing DNA fragmentation factor-like effector family (CIDEC) that is thought to play a role in adipocyte apoptosis26 and lipase, hormone sensitive (LIPE). Partial lipodystrophy may also be seen in association with mandibuloacral dysplasia (MAD), an autosomal recessive syndrome associated with mutations in LMNA (type A), or with mutations in ZMPSTE24, which encodes a zinc metalloproteinase involved in post-translational proteolytic processing of prelamin A (type B)27,28. The latter has been associated with severe mandibuloacral dysplasia, premature aging, and generalized lipodystrophy. Mesangiocapillary glomerulonephritis type 2 (MCGN II) has been reported in a case of partial lipodystrophy due to a mutation in the LMNA gene, suggesting that partial lipodystrophy of both the sporadic and familial subtypes may predispose to this condition and the observed renal and complement abnormalities may be secondary to other factors associated with lipodystrophy29.

Regional differences in factor D expression parallel the regional distribution of adipocyte loss in partial lipodystrophy, which may explain the cephalocaudal distribution of fat. Renal cells also express complement components, and a similar mechanism of complement-mediated injury may be responsible for the MCGN II seen in these patients34.

Localized Lipoatrophy The pathogenesis of localized lipoatrophy is heterogeneous. Circumscribed areas of lipoatrophy may follow inflammation from pyogenic abscesses, various lobular panniculitides (especially lupus profundus and panniculitic dermatomyositis), localized autoimmune connective tissue diseases (e.g. morphea), or subcutaneous panniculitis-like T-cell lymphoma. Iatrogenic causes include traumatic and inflammatory responses to injected medications (Table 101.2). In the case of insulin lipoatrophy, it may be induced by impurities and is significantly associated with the presence of anti-insulin antibodies35; mononuclear infiltrates near insulin injections suggest a localized immune response. Because repeated use of the same injection site increases the risk of lipoatrophy, the latter can be largely prevented by regular rotation of injection sites. Of note, lipoatrophy is fairly rare with the use of human insulin and insulin pump therapy. Lipoatrophy may also occur at injection sites of growth hormone and glatiramer acetate due to a direct lipolytic effect and panniculitis, respectively. Lipoatrophia semicircularis may represent repetitive trauma or pressure-induced changes (Fig. 101.2), due to constant or intermittent pressure from leaning against a desk or chair edge, basin, bathtub or counter, or from tight-fitting jeans or girdles. Both resolution of the lesions when trauma is avoided and the occurrence of similar lesions in multiple employees in the same workplace provide support for microtrauma as the etiology36. Local hyperproduction of TNF-α by macrophages has also been implicated37. Localized lipoatrophy of the upper and lateral calf due to pressure is commonly observed in women who cross their legs when seated (Fig. 101.3). Up to 60% of involutional lipoatrophy (see below) may be associated with prior local injections, suggesting a trauma-related phenomenon38. Lipophagocytizing macrophages seen by electron microscopy suggest an initial stimulation by injectable material; typically, an active foreign body reaction is absent. Lipodystrophia centrifugalis abdominalis infantilis is usually idiopathic, but has been reported to be associated with mechanical trauma or focal infection. Predominance of this condition in East Asia is notable and reports in twins and siblings point to the possibility of an HLA predisposition. In one patient with lipodystrophia centrifugalis

Acquired Generalized Lipodystrophy (Lawrence Syndrome) There is no known genetic defect. A third of patients have an antecedent autoimmune disease or viral or bacterial infection, but a causal relationship with the latter has not been established. Twenty-five percent of cases of acquired generalized lipodystrophy are heralded by panniculitis (see Table 101.1)30. The preceding panniculitis and the frequent association of autoimmune disease imply immunologically mediated fat cell lysis. Autoantibodies against the adipocyte membrane have been reported in one patient with this condition31. As with the other forms of lipodystrophy, most patients have low serum levels of leptin and adiponectin.

Acquired Partial Lipodystrophy Syndrome (Barraquer–Simons Syndrome)

1762

Acquired partial lipodystrophy syndrome occurs sporadically or may be autosomal dominant, with mutations in LMNB2 reported in some patients32,33. Subcutaneous fat is often lost acutely after a viral illness. The exact pathogenesis is not known, but it may be related to adipsin, a protein produced by adipocytes which is identical to factor D (a component of the alternative complement pathway; see Ch. 60), as well as C3 nephritic factor (C3NeF), an IgG autoantibody against an alternative pathway enzyme. There is dysregulated activation of the alternative pathway, associated with C3NeF binding to the rate-limiting C3 convertase enzyme (C3bBb). This results in unopposed activation of the alternative complement pathway, excessive consumption of C3, and complement-dependent lysis of adipocytes.

INJECTED MEDICATIONS THAT CAN CAUSE LOCALIZED LIPOATROPHY

Most common Insulin • Non-human ≫ human, insulin analogues • Rarely, can occur at distant sites Corticosteroids

Less common Antibiotics • Benzathine penicillin * • Amikacin Immunomodulatory drugs • Glatiramer acetate (multiple sclerosis) • Methotrexate * Vaccines • Diphtheria–pertussis–tetanus vaccine • Quadrivalent human papillomavirus vaccine Growth hormone Heparin Iron dextran Exogenous material

*Including semicircular lipoatrophy. Table 101.2 Injected medications that can cause localized lipoatrophy. Lipoatrophy can also be seen at sites of acupuncture.  

CHAPTER

Lipodystrophies

101

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Fig. 101.2 Lipoatrophia semicircularis (semicircular lipoatrophy). Bilateral slightly curved depressions on the anterolateral thighs. Courtesy, Diane Thaler, MD.  

Fig. 101.3 Localized lipoatrophy of the upper lateral calf due to pressure. A fairly common finding in women who cross their legs while seated. Courtesy,  

Jean L Bolognia, MD.

%

Fig. 101.4 Congenital generalized lipodystrophy syndrome (Berardinelli– Seip syndrome). A Lipoatrophy of the trunk leading to muscle definition. B Extensive acanthosis nigricans. Courtesy, Edward Cowen, MD.  

The inability to store sufficient fat in the adipocytes results in the metabolic syndrome (see Ch. 53), which becomes more profound during puberty40. Diabetes mellitus is evident by adolescence, but hyperinsulinemia can be detected as early as infancy. Enlarged genitalia are seen, especially in women, and may be associated with polycystic ovarian syndrome and infertility. Hepatosplenomegaly is typical and may be associated with umbilical herniation. Dermatologic sequelae (see Table 101.3) include acanthosis nigricans, which is noted by adolescence and may be extensive (Fig. 101.4B). Serious medical complications and metabolic derangements include cirrhosis from fatty liver, premature atherosclerosis, sequelae of diabetes, pancreatitis from hypertriglyceridemia, and a high mortality rate from hypertrophic cardiomyopathy. The mean age of death is 32 years. Type 2 appears to be a more severe disorder that is associated with intellectual disability, hypertrophic cardiomyopathy and a higher incidence of premature death while type 4 patients have cardiac arrhythmias and pyloric stenosis.

Familial Partial Lipodystrophy

abdominalis infantilis, positive immunohistochemical staining for Fas, bcl-2 and p53 as well as terminal transferase-mediated dUTP nick endlabeling (TUNEL) in degenerating fatty tissue suggested apoptosis as a possible factor39.

CLINICAL FEATURES Congenital Generalized Lipodystrophy (CGL) CGL is rare, with an estimated prevalence of less than 1 case in 10 million40. As an autosomal recessive disorder, there is often consanguinity. All subtypes are characterized by generalized loss or absence of metabolically active subcutaneous fat from birth, resulting in a cadaveric facies and distinctive muscular-appearing body habitus (Fig. 101.4A). Anabolic features are evident in early childhood (Table 101.3). There is also a deficiency of bone marrow fat (types 1,2) and visceral fat (types 1,3,4). Type 2 CGL also lacks mechanical fat, in addition to metabolically active fat.

Familial partial lipodystrophy (FPLD) was first described by Dunnigan and Köbberling41, who outlined the clinical characteristics of large Scottish and German pedigrees with familial syndromes of partial lipodystrophy. FPLD is classified based upon genetic mutations and clinical phenotype (see Table 101.1). This group of disorders differs from other forms of inherited lipodystrophy by a later onset (after puberty) and fat loss predominantly affecting the extremities, with sparing of the face40,42. FPLD is a rare disorder, with a prevalence of less than 1 in 15 million40. In FPLD2, a normal childhood is followed by a progressive, symmetric loss of subcutaneous fat; the latter uniformly involves the extremities and variably extends to the trunk (anterior > posterior). Compensatory accumulation of excess fat occurs and results in a fat head and neck, with a round face, as well as increased supraclavicular fat (see Fig. 101.1). Acromegalic facies with a double chin is characteristic. As a result of the loss of fat in the limbs, there is an accentuation of subcutaneous veins and muscular prominence (Fig. 101.5). Although FPLD3 has milder clinical features and an onset after the second decade of life, the metabolic disturbances may be more severe40. Metabolic disturbances in FPLD are similar to those in the generalized lipodystrophy syndromes. Glucose intolerance, ranging from mild to severe, develops during young adulthood. Acute pancreatitis and hepatic steatosis and cirrhosis may occur, with complications from diabetes mellitus, atherosclerotic cardiovascular disease, or hypertrophic cardiomyopathy leading to premature death. When compared to men, affected women have been reported to have more severe triglyceride elevations. Dermatologic manifestations include tuberous xanthomas, acanthosis nigricans and hirsutism, while gynecologic findings include menstrual irregularities, polycystic ovaries, and fat hypertrophy within the labia majora.

1763

SECTION

Disorders of Subcutaneous Fat

16

Fig. 101.5 Lipoatrophy of the lower extremities, leading to muscular prominence. Courtesy,  

FEATURES OF CONGENITAL GENERALIZED LIPODYSTROPHY

Lipodystrophic features Lack of fat in the buccal region, resulting in a cadaveric facies MRI studies show near total absence of subcutaneous fat and other metabolically active adipose tissues • Preservation of fat deposits in “mechanical” sites (types 1, 3, 4): orbit, palms, soles, tongue, breasts, vulva, and in periarticular and epidural regions • Muscular body habitus due to the extreme paucity of subcutaneous fat •

William D James, MD.



Anabolic features Muscular hypertrophy with prominent superficial veins Acromegalic facial and acral features • Voracious appetite • Increased basal metabolic rate • Heat intolerance • Accelerated growth with a normal to slightly increased adult height • Advanced bone and dental age • Osteosclerotic and lytic skeletal changes • Masculine features in females (clitoromegaly rare) • Enlarged genitalia (usually limited to infancy and childhood) • •

Metabolic disturbances Insulin resistance and severe fasting or postprandial hyperinsulinemia from early infancy • Insulin levels may decrease after several years, due to exhaustion of pancreatic β cells • Very insulin-resistant diabetes mellitus: noted at puberty with growth cessation • Impaired glucose tolerance is noted around age 8–10 years • Hypertriglyceridemia and sequelae (chylomicronemia, pancreatitis) • Hyperlipidemia accelerates at puberty (with growth cessation) • Low HDL-cholesterol levels (accurate assessment may be hindered by the increased TGs) • Low plasma leptin levels, corresponding to decreased body fat •

Dermatologic manifestations Acanthosis nigricans, often early onset and widespread • Hypertrichosis, including increased (often curly) scalp hair at birth • Hyperhidrosis • Coarse skin on the upper body • Hyperkeratotic epidermal papillomatosis (may represent an exaggerated form of AN) • Xanthomas •

Gynecologic disturbances Oligomenorrhea Polycystic ovaries • Infertility (females) • •

Organomegaly and organ dysfunction Hypertrophic cardiomyopathy (often fatal) Fatty liver, hepatomegaly, cirrhosis, liver failure • Organomegaly: tonsils and adenoids, lymph nodes, spleen, kidneys, adrenals, pancreas, ovaries • Central nervous system abnormalities: hypothalamic–pituitary dysfunction, ventricular dilation, below average intelligence, ± mild mental retardation • Proteinuric nephropathy • •

2,34

Table 101.3 Features of congenital generalized lipodystrophy . HDL, high-density lipoprotein; MRI, magnetic resonance imaging; TG, triglyceride.  

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Familial partial lipodystrophy with mandibuloacral dysplasia is a rare variant of partial lipodystrophy characterized by mandibular and clavicular hypoplasia, short stature, a high-pitched voice, and ectodermal abnormalities of the skin, teeth, nails and hair27,40. There are multiple craniofacial defects, including dental overcrowding and a bird-like facies with prominent eyes and a beaked nose. Skeletal abnormalities include osteolysis of the clavicles, acro-osteolysis, delayed closure of cranial sutures, and joint contractures. Mottled hyperpigmentation, alopecia, atrophy of extremity skin, and nail dysplasia are the characteristic cutaneous findings. Less common clinical features include sensorineural hearing loss, delayed puberty, a high-arched palate, and

cutaneous calcinosis. Features of the metabolic syndrome may be present (see Ch. 53).

Autoinflammatory Syndromes (see Table 45.7) Joint contractures, muscle atrophy, microcytic anemia, and panniculitis-induced lipodystrophy (JMP) syndrome In addition to the clinical findings in its name, patients with this childhood-onset, autosomal recessive syndrome can have hypergammaglobulinemia, an elevated ESR, hepatosplenomegaly, and calcification of basal ganglia43,44. The lipodystrophy may be partial, involving primarily the face and upper extremities, or less often generalized. Affected individuals have mutations in PSMB8 which encodes pro­ teasome subunit beta 8, a component of the immunoproteasome, which is found predominantly in monocytes and lymphocytes45. Immunoproteasome-mediated proteolysis generates immunogenic epitopes that, upon presentation by MHC class I molecules, may trigger an autoinflammatory response. This results in a mixed inflammatory infiltrate within the adipose tissue and loss of adipocytes.

Chronic atypical neutrophilic dermatosis with lipodystrophy and elevated temperature (CANDLE) syndrome CANDLE syndrome is also an autoinflammatory syndrome whose onset is during the first year of life and is characterized by violaceous swollen eyelids, pernio-like lesions, and progressive peripheral lipodystrophy involving the face and extremities as well as recurrent fevers, arthralgias, contractures of the extremities, delayed physical development, anemia, and increased acute phase reactants46–48. Most of the patients have mutations in PSMB8 (see above). There is currently no established treatment, but some patients have been reported to benefit from corticosteroids and NSAIDs.

Recurrent lipoatrophic panniculitis of children This is a recently described syndrome in which painful subcutaneous nodules are accompanied by fever, malaise, abdominal pain, and arthralgias.48a Localized lipoatrophy then develops at the sites of nodules. Histopathologically, there is a lobular panniculitis with a mixed infiltrate composed of neutrophils, lymphocytes, macrophages,

Acquired Generalized Lipodystrophy To date, ~80 cases of acquired generalized lipodystrophy (AGL; Lawrence or Lawrence–Seip syndrome) have been reported in the English literature. New diagnostic criteria for AGL have been proposed, as well as a subclassification into three subtypes (Table 101.4). In approximately one-third to one-half of patients, there is a preceding systemic illness, in particular a viral or bacterial infection or an autoimmune disorder (e.g. a connective tissue disease, thyroiditis)40. Clinical features of AGL are similar to those of the congenital variant, but are of later onset and milder. The lipoatrophy typically does not become apparent until childhood or adolescence and rarely develops during adulthood. This disorder is ~3× more common in women. Large areas of the face, trunk and extremities have fat loss (Fig. 101.6), and the palms and soles may even be involved. Loss of peripheral fat as well as perinephric and intra-abdominal fat can be documented by MRI

ACQUIRED GENERALIZED LIPODYSTROPHY: PROPOSED DIAGNOSTIC CRITERIA AND SUBTYPES

Essential criterion Selective loss of fat involving large regions of the body beginning during childhood or adolescence

Supportive criteria Clinical • Loss of subcutaneous fat from the palms and soles • Acanthosis nigricans • Hepatosplenomegaly • Panniculitis prior to onset (by clinical history and/or histologic confirmation; see below) • Associated autoimmune diseases (see below) Laboratory • Diabetes mellitus or impaired glucose tolerance • Severe hyperinsulinemia (fasting and/or postprandial) • Increased serum triglyceride and/or decreased HDL-cholesterol levels • Reduced serum leptin and/or adiponectin levels • Anthropometric or MRI evidence of large regions of fat loss • MRI evidence of preserved bone marrow fat

Subtypes Panniculitic variant (type 1) • Panniculitis precedes the onset of lipoatrophy, which may be noted in the center of expanding annular lesions or at distant sites • Mean age of onset is 7 years; slight female predominance (~1.5-fold) • Associated symptoms include low-grade fever, malaise, arthralgias, and abdominal pain • May be associated with autoimmune diseases (see below) • Relatively mild metabolic derangements and leptin abnormalities • Histopathologic evaluation reveals a lymphohistiocytic subcutaneous infiltrate ± granulomatous foci Autoimmune variant (type 2) • Concurrent or prior autoimmune disease without preceding panniculitis; associated with juvenile dermatomyositis, Sjögren syndrome, juvenile idiopathic arthritis, vitiligo, chronic urticaria/angioedema, and autoimmune thyroiditis, hepatitis or hemolytic anemia • Mean age of onset is 15 years; female predominance (~3-fold) • Hepatomegaly is invariably present; hypertriglyceridemia and diabetes mellitus occur in most patients • Laboratory abnormalities may be observed without clinical evidence of autoimmune disease, including antinuclear, anti-smooth muscle, anti-glomerular basement membrane, anti-salivary duct, antimitochondrial, and anti-adrenal/ovary/placenta/testis antibodies Idiopathic (type 3) • No evidence of panniculitis or autoimmune disease • Mean age of onset is 20 years (range, 90% of patients presenting by age 5 years. In Koreans, there is a four-fold female predominance53. Although lipodystrophia centrifugalis abdominalis infantilis affects primarily Asian children, it may occasionally occur in Caucasians and in adults. Clinically, a well-demarcated area of lipoatrophy with a periphery of erythema and scale is seen on the abdomen or elsewhere on the trunk, often with associated regional lymphadenopathy. The lipoatrophy begins on the lower abdomen or in the groin region (and may include the genitalia) in about 80% of patients, and in the axillary region in

lipoatrophy, it may be accompanied by atrophy of the underlying cartilage and bone, with potential ophthalmologic and dental consequences. Non-progressive late-onset linear hemifacial lipoatrophy occurs on the malar cheek, primarily in elderly individuals. Inflammatory reactions due to material injected for cosmetic purposes or from self-inflicted injections of foreign material can lead to lipoatrophy which may be associated with scarring and dyschromia.

Lipohypertrophy

CHAPTER

101 Lipodystrophies

about 20% of patients; it spreads onto the abdomen or chest, respectively, in a centrifugal fashion (Fig. 101.10). The underlying blood vessels become visible and ulceration may occur within the depressed areas. Contrary to its original name, this condition can affect nonabdominal sites such as the face, neck and lumbosacral region (Fig. 101.11A), and it is not limited to infants. The lesions may progress slowly over several years, then often cease enlarging by 13 years of age52. Although there is no specific therapy, >60% of patients spontaneously improve (Fig. 101.11B). Progressive hemifacial atrophy (Parry–Romberg syndrome) is considered to be a form of severe morphea (see Ch. 44), and in addition to

Lipohypertrophy remains a frequent complication of insulin therapy, irrespective of the insulin source and mode of administration54. As with insulin lipoatrophy, anti-insulin antibodies are associated with lipohypertrophy in children and adolescents with type 1 diabetes. The clinical consequence is that injection of insulin into a site of lipohypertrophy, while painless, may lead to erratic absorption of the insulin, with the potential for poor glycemic control. Of note, insulin-induced nodular amyloidosis may have a clinical appearance similar to lipohypertrophy. Injection of pegvisomant, a growth hormone receptor antagonist used to treat acromegaly, is another cause of lipohypertrophy (Table 101.5).

PATHOLOGY Generally speaking, the histologic picture of the various lipodystrophy syndromes (see Table 101.1) is non-inflammatory. In generalized

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Fig. 101.9 Localized lipoatrophy secondary to lupus panniculitis. A An area of depression on the cheek due to burnt-out lupus panniculitis; note the dyspigmentation and scarring from an overlapping lesion of discoid lupus erythematosus.   B Circular depressions on the upper arm, a common location for lupus panniculitis.  

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A, Courtesy, National Skin Centre, Singapore.

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Fig. 101.11 Lipodystrophia centrifugalis infantilis (centrifugal lipodystrophy) of the face. A A 2-year-old girl with a serpentine violaceous band involving the cheek in association with lipoatrophy. B The same child two years later, with spontaneous resolution. The most common location for lipodystrophia centrifugalis infantilis is the abdomen (see Fig. 101.10). Courtesy, National Skin Centre,  

Fig. 101.10 Lipodystrophia centrifugalis abdominalis infantilis (centrifugal lipodystrophy). A 5-year-old Malay boy with a two-year history of progressive lipoatrophy involving the groin bilaterally and the lower abdomen. The veins in the involved area are readily visible. Courtesy, National Skin Centre, Singapore.  

Singapore.

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SECTION

Disorders of Subcutaneous Fat

16

CAUSES OF LIPOHYPERTROPHY Insulin therapy – risk factors include duration of therapy, frequent injections, failure to rotate sites of injections, and poor injection technique Pegvisomant (growth hormone receptor antagonist) injections* Growth hormone injections Excess corticosteroids – includes Cushing disease (excessive ACTH production by the pituitary gland) and Cushing syndrome (iatrogenic, adrenal tumors, nodular adrenal hyperplasia, ectopic ACTH production) HIV/ART-associated – risk factors include extended exposure to nucleoside reverse transcriptase inhibitors, exposure to protease inhibitors, age ≥40 years, longer duration of therapy, higher body mass index before onset of therapy, and presence of metabolic derangements (elevated serum triglyceride and insulin levels; depressed serum testosterone levels)

*Used to treat acromegaly.

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Table 101.5 Causes of lipohypertrophy.  

Fig. 101.12 Histopathologic features of the preceding panniculitis in type 1 acquired generalized lipodystrophy. Lobular panniculitis with infiltrate of lymphocytes, histiocytes, multinucleated giant cells, and lipophages. There is also cytoplasmic vacuolization of the fat cells (inset). See Table 101.4 for three types.  

Courtesy, Jacqueline Junkins-Hopkins, MD.

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Fig. 101.13 Histopathologic features of involutional lipoatrophy secondary to corticosteroid injection. A There is marked diminution and collapse of the fat lobules, without inflammation. B Higher power demonstrates decreased size of fat cells with eosinophilic thickened cell walls with a hyalinized and mucinous stroma. Courtesy, Jacqueline Junkins-Hopkins, MD.  

1768

lipodystrophy, there is complete or near-complete loss of subcutaneous fat, with the dermis and fascia in direct apposition. Less often, biopsy specimens appear to have no overt abnormalities, except for an increased amount of collagen, which has replaced the subcutaneous fat. In contrast, biopsies of acquired generalized lipodystrophy, in particular type 1, may show a lobular panniculitis (Fig. 101.12; see Table 101.4). In acquired generalized lipodystrophy and areas of lipoatrophy in some forms of partial lipodystrophy, two histologic patterns have been recognized: (1) non-inflammatory with involutional changes of the fat; and (2) inflammatory in the form of a lobular panniculitis with lymphocytes, lipophages, and plasma cells55. Whether these two patterns are stage-related remains to be clarified, as even in patients without panniculitis clinically, biopsies of early lesions may show inflammation, but it is usually mild. Involutional changes of the subcutaneous fat are characterized by small fat lobules with a reduction in the size and number of adipocytes (Fig. 101.13). Involutional lipoatrophy can be further divided into two histologic subtypes38. In the first type, the lobules may be composed of faintly acidophilic, small fat cells that retract from one another as well as the surrounding connective tissue, leading to an appearance similar to embryonic fat; the lobules often have an eosinophilic appearance. These histologic findings are more prominent at the periphery of the clinically depressed area, with tiny acidophilic fat cells present more centrally. Inflammation is absent to sparsely mononuclear. The second type, with indistinguishable clinical features, shows small atrophic

adipocytes with a normal fat cell membrane surrounded by prominent vasculature. At scanning magnification, the lobules are collapsed (with an orientation parallel to the skin surface) and surrounded by numerous capillaries. Acid mucopolysaccharide deposition within the fat lobules and fibrosis of the septae may be seen, as well as occasionally lipomembranous changes. Although birefringent, non-crystalline foreign material may be observed, foreign body giant cells and lipophages are typically absent in both subtypes of involutional lipoatrophy. CD68+ macrophages can be demonstrated with immunohistochemical staining. Ultrastructural studies have shown that these are lysosomally active macrophages adjacent to lipocytes, and they may contain degenerated lipid38. In localized lipodystrophy, a loss of fatty tissue is seen, along with a variable degree of fibrosis. There is usually no inflammatory infiltrate, although panniculitis has been reported in a few cases. Deposits of immunoreactants can be seen within blood vessel walls or the basement membrane, particularly in the inflammatory type. Histologically, well-developed areas of lipodystrophia centrifugalis abdominalis infantilis show a diminution of subcutaneous fat with scant or absent inflammation. The erythematous rim tends to correspond to a moderate or marked lymphohistiocytic infiltrate in the subcutaneous fat; a deep dermal and peri-eccrine lymphocytic infiltrate is an uncommon finding. There may be fibrosis and thickening of the septae within the subcutis. The few adipocytes that are present may have myxoid changes. Other localized variants such as lipoatrophia semicircularis (semicircular lipoatrophy) and drug-induced lipoatrophy usually show a loss of fatty tissue and replacement by collagen, with no features of panniculitis. There are often scattered lipophages. However, at sites of glatiramer acetate injections, panniculitis that resembles lupus profundus

DIFFERENTIAL DIAGNOSIS There are a variety of other complex syndromes that present with lipoatrophy along with a number of other physical and systemic features (see below). A detailed discussion of these syndromes is beyond the scope of this chapter. The excessive fat accumulation seen in patients with FPLD2 and HIV/ART-associated lipodystrophy could be confused with Cushing syndrome. Acromegaly can have overlapping features with generalized lipodystrophy. In an infant with generalized lipodystrophy, the following conditions should also be considered: Leprechaunism (Donohue syndrome) is included in some lipodystrophy classifications, as the patients present with generalized lipodystrophy, severe insulin resistance, acanthosis nigricans, and hirsutism. In contrast to CGL, these patients have a distinct elfin facies, severe intrauterine growth retardation, prominent nipples, loose skin, mutations in the insulin receptor gene, and death during infancy. SHORT syndrome (short stature, hyperextensible joints or hernia, ocular depression, Rieger anomaly [iridocorneal mesodermal dysgenesis], and teething delay) is also included in some lipodystrophy classifications, as there is congenital lipoatrophy of the face and upper body. This condition is distinguished by the above-outlined abnormalities, intrauterine growth retardation, delayed bone age, mutations in PIK3R1, and a dysmorphic facies, which includes a triangular shape, micrognathia, deep-set eyes, and anteverted ears. Carbohydrate metabolic abnormalities are rare to absent. Progeria-type syndromes are characterized by limb lipoatrophy, cardiovascular disease and diabetes, but they are accompanied by muscle wasting, sclerodermatous changes, cataracts, and other signs of premature aging. Some of the progeric syndromes have LMNA mutations similar to those associated with FPLD, and may be considered as part of a broader group of disorders termed laminopathies (see Table 63.10). In Cockayne syndrome, lipoatrophic changes are accompanied by growth delay, retinal abnormalities, photosensitivity, and defects in DNA repair (see Chs 63 & 87). AREDYLD syndrome: congenital generalized lipoatrophic diabetes is associated with an acrorenal field defect, and ectodermal dysplasia. In the case of partial lipodystrophy, there was a report of diffuse, symmetrical lipoatrophy of the lower extremities following extensive inflammation due to lobular panniculitis56. Neither underlying autoimmune diseases nor exogenous causes were identified. Localized lipodystrophies should be differentiated from initial phases of progressive lipodystrophy, morphea, lupus panniculitis, and atrophoderma of Pasini and Pierini. Although there is overlap amongst the various types of localized lipodystrophy, the distribution and morphology combined with a history of injections, the presence clinically or histologically of panniculitis, and associated autoimmune disorders may aid in the diagnosis. Poland syndrome is a rare congenital disorder consisting of unilateral partial or total absence of a breast and/or pectoralis major muscle plus ipsilateral symbrachydactyly, which may simulate lipoatrophy. Lastly, MRI can help to differentiate loss of fat from other causes of localized depressions of the skin.







• •

TREATMENT Management issues for lipodystrophy syndromes are threefold: (1) cosmetic concerns; (2) metabolic derangements; and (3) systemic associations. Also, with better elucidation of the genetic basis of the various inherited lipodystrophy syndromes (see Table 101.1), determination of the underlying genetic mutation can have important implications for prognosis and genetic counseling. Treatment options for the physical aspects of lipodystrophy are limited (see below). Localized lipodystrophy may resolve spontaneously,

depending on the etiology and/or subtype. In trauma-induced cases, in particular lipoatrophia semicircularis, the depressions may normalize over a period of weeks. Switching to purified human insulin may improve insulin lipoatrophy, but it may take 1–3 years54. Surgical treatment has had variable and limited success. Persistent facial lipoatrophy may be amenable to flaps. Soft tissue augmentation using a variety of permanent and non-permanent fillers may be helpful (see Ch. 158). Solid synthetic volumetric midfacial implants, constructed using computer-aided design and manufacturing technology57, may offer a more durable correction of the defects. A thoughtful assessment of possible long-term complications of permanent fillers is always mandatory prior to treatment. Fat transplantation via lipoinjection may also help facial defects58. While medical therapy is directed predominantly at the metabolic derangements in order to reduce the associated morbidity and mortality, it may also offer some benefit for the lipodystrophic features. Thiazolidinediones (TZDs; also referred to as glitazones), which are PPAR-γ agonists, have been used to increase insulin sensitivity, increase body fat, improve adipocytokine levels, and lower triglyceride levels59. However, there have been concerns regarding the adverse side effects of this group of drugs, including hepatotoxicity, weight gain, congestive heart failure, and bone fractures in women. Fibrates are PPAR-α agonists that increase fatty acid oxidation and have been used to treat hypertriglyceridemia. Omega-3 polyunsaturated fatty acids can also lower circulating triglyceride levels by reducing hepatic triglyceride synthesis via competitive inhibition. To date, controlled trials supporting the efficacy of these various drugs in inherited lipodystrophies are lacking. Therapy has also been targeted at the adipokine abnormalities, such as leptin deficiency. Treatment with recombinant methionyl human leptin (r-metHuLeptin) for generalized lipodystrophy, both congenital and acquired forms, has resulted in an improvement of glycemic control, hyperlipidemia, hepatomegaly, and diabetic complications such as proteinuria. The therapy is generally well tolerated, with no notable serious adverse effects60,61. In addition to correcting the metabolic derangements, leptin replacement may improve appetite regulation. With long-term treatment, benefits have been shown to persist60. However, administration of metHuLeptin has not led to improvement in the lipodystrophy. Nutritional alteration (e.g. low-fat diet), exercise, and a weightmanagement program can further improve the hyperlipidemia and hyperglycemia. Management by an endocrinologist is recommended.

CHAPTER

101 Lipodystrophies

histologically can be seen. Lastly, HIV/ART-associated lipodystrophy resembles the non-inflammatory pattern of lipodystrophy.

Acquired Partial Lipodystrophy Management of patients with acquired partial lipodystrophy should include initial evaluation and continued monitoring for autoimmune disease (such as lupus and dermatomyositis), thyroid disease, and renal disease. The latter should include evaluation for proteinuria, low C3, and C3 nephritic factor (C3NeF), and, if necessary, renal biopsy to exclude MCGN. The presence of neutralizing antibodies against C3NeF in IVIg led to treatment of a patient with MCGN II and C3NeF with IVIg, with encouraging results62. Because there is activation of the alternative complement pathway, eculizumab has been tried, with mixed results. Genetic counseling should be considered for the familial variants.

Insulin Lipodystrophy While the incidence of insulin lipoatrophy has decreased significantly with the advent of purified human insulin, some patients may be injecting other forms. Switching to human insulin and changing the mode of delivery are helpful interventions (see above). For prevention, constant rotation of injection sites, such that the same site is not used more often than once a month, is recommended. Liposuction may lead to improvement in the hypertrophic form.

HIV/ART-ASSOCIATED LIPODYSTROPHY HIV/ART-associated lipodystrophy has become the most common form of non-localized lipodystrophy. It is linked in particular to protease inhibitors (PI) and nucleoside analogue reverse transcriptase inhibitors (NRTIs), affecting up to 40% of patients within 1 to 2 years of initiation of ART63.

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16

within different tissues, all in a complex interplay with host-specific factors such as age, genetics, severity of HIV infection, and inflammatory states63. Proposed mechanisms for ART-induced subcutaneous fat loss include (Table 101.6 & Fig. 101.14): impaired pre-adipocyte differentiation and increased adipocyte apoptosis65,66 impaired insulin-stimulated lipogenesis and increased lipolysis65, leading to decreased adipocyte size mitochondrial toxicity67. HIV/ART-related lipodystrophy was initially considered a PI-mediated disease, but exposure to thymidine analogue NRTIs has been identified as an independent and significant risk factor for its development. In particular, stavudine and zidovudine were more strongly associated with lipoatrophy, as was didanosine67,68. Inhibition of DNA polymerase-γ within mitochondria is the proposed major site of action of NRTIs (see Fig. 101.14), leading to the

The clinical findings in HIV/ART-associated lipodystrophy include: lipoatrophy of peripheral sites, primarily the face, limbs, heel pads, and buttocks central lipohypertrophy or adipose tissue accumulation, especially dorsocervical, supraclavicular, within the breasts, intra-abdominal and visceral (e.g. liver) metabolic abnormalities – insulin resistance, type 2 diabetes, dyslipidemia, hypertension, lactic acidosis. The progressive body changes resulting from a combination of lipoatrophy and lipohypertrophy can be disfiguring and potentially stigmatizing, resulting in a loss of adherence to ART64.

• •

• • •



Pathogenesis The etiology of HIV/ART-associated lipodystrophy is multifactorial and includes multiple sites of drug actions in metabolic pathways and

MECHANISMS OF ANTIRETROVIRAL THERAPY (ART)-ASSOCIATED LIPOATROPHY

HIV drugs implicated

Drug-induced effect

Cellular response

↓ Adipocyte differentiation*

PIs, NRTIs

Defect in lamin A/C processing and/or RXR-PPAR-γ heterodimer activation decreases function of SREBP-1c & other downstream transcription factors

↓ Production of new mature fat cells → ↓ fat cell number

↑ Adipocyte apoptosis*

PIs, NRTIs

↑ TNF-α signaling (as well as mechanism described above for ↓ differentiation)

↑ Fat cell death → ↓ fat cell number

↑ Lipolysis*

PIs, NRTIs

↓ Expression of perilipin

↑ Release of stored TGs as FFAs and glycerol into circulation → ↓ fat cell size

↓ Lipogenesis

PIs, NRTIs

↓ Expression and function of lipogenic SREBP-1c

↓ FFA uptake by adipocytes → ↓ fat cell size

Mitochondrial toxicity

NRTIs

Inhibition of mitochondrial DNA polymerase-γ

↑ Catabolic pathways (lipolysis), altered production of hormones and cytokines (↓ adiponectin, ↑ TNF-α), ↓ adipocyte differentiation, ↑ adipocyte apoptosis

*Also represent sequelae of mitochondrial toxicity. Table 101.6 Mechanisms of antiretroviral therapy (ART)-associated lipoatrophy. FFA, free fatty acids; HIV, human immunodeficiency virus; NRTI, nucleoside reverse transcriptase inhibitor; PI, protease inhibitor; PPAR-γ, peroxisome proliferator-activated receptor-γ; RXR, retinoid X receptor; SREBP-1c, sterol regulatory element-binding protein-1c; TG, triglycerides; TNF-α, tumor necrosis factor-α. From refs 65–67, 69, 70.  

PROPOSED MECHANISMS OF HIV/ART-ASSOCIATED LIPODYSTROPHY

Capillary endothelium Adipocyte

Fatty acids

Glycerol Central fat deposition

at-RA-CRABP-1 Nucleoside reverse transcriptase inhibitors, e.g. stavudine, didanosine, zidovudine

Mitochondrion DNA polymeraseγ 6

PI

mtRNA Proteins of respiratory chain

Triglyceride storage

PI P450 3A

9-cis-RA PPAR-γ SREBP-1c

mtDNA

Fatty acid oxidation

1

Apoptosis and reduced differentiation

2 PI

LPL LRP

3

Triglyceride storage

Increased breast fat

4 Increased circulating triglycerides

Dorso-cervical fat (buffalo hump)

5 LRP

Insulin resistance

LRP

Liver Lipoatrophy of the face and extremities

Fig. 101.14 Proposed mechanisms of HIV/ART-associated lipodystrophy. The combination of decreased PPAR-γ expression and decreased fatty acid oxidation capacity resulting from drug exposure could explain how these drugs cause adipocyte toxicity and lipoatrophy. See Table 101.6 for additional details. The numbers represent sites of drug effects. ART, antiretroviral therapy; at-RA, all-trans-retinoic acid; CRABP-1, cytoplasmic retinoic acid binding protein type 1; LPL, lipoprotein lipase; LRP, low-density lipoprotein receptor-related protein; mtRNA, mitochondrial RNA; mtDNA, mitochondrial DNA; PIs, protease inhibitors; PPAR-γ, peroxisome proliferator-activated receptor-γ; RXR, retinoid X receptor; SREBP-1c, sterol regulatory element-binding protein-1c. Adapted from Carr A. HIV protease inhibitor-related lipodystrophy  

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syndrome. Clin Infect Dis. 2000;30:S135–42.

CHAPTER

101

Fig. 101.15 HIV/ ART-associated lipoatrophy. A The side view highlights the loss of temporal fat. B There is symmetric loss of buccal and parotid fat, resulting in prominent zygomata and a cachectic appearance, in a second patient.

Lipodystrophies



A, Courtesy, Ken Katz, MD; B, Courtesy, National Skin Centre, Singapore.

$

Fig. 101.16 HIV/ ART-associated lipoatrophy. A Marked indentation of the medial cheeks in an older patient, with redundant melolabial folds. B Lower extremities with prominent veins and defined musculature. A,  

$

Courtesy, Priya Sen, MD.

%

mitochondrial dysfunction that has been observed in several tissues, including adipose tissue67. Of note, the latter has a high concentration of mitochondria. When the NRTI-induced mitochondrial DNA depletion reaches a threshold, this results in decreased adipocyte size66 and increased adipocyte death, culminating in the development of lipoatrophy. Interference with the function of the respiratory chain complexes leads to impaired fatty acid oxidation and intracellular accumulation of triglycerides and lactate, which can then enter the systemic circulation. PIs cause adipose toxicity via their effects on sterol regulatory element-binding proteins (SREBP) which function as transcription factors. In part, PIs prevent the cellular maturation of the SREBP-1c isoform to its active form in adipocytes69, resulting in impairment of intracellular fatty acid and glucose metabolism as well as adipocyte differentiation (see Table 101.6). In addition, PIs decrease the expression of peroxisome proliferator-activated receptor-γ (PPAR-γ) and this can also lead to a reduction in differentiation of adipocytes70. These regulators of lipid metabolism, SREBP-1 and PPAR-γ, are linked through PPAR-γ coactivator-1. Decreases in PPAR-γ expression correlate with decreases in mitochondrial RNA expression, again providing a link between NRTI-induced mitochondrial toxicity and lipoatrophy. PPAR-γ expression is also decreased by the HIV viral protein R (vpr), lending support to a direct role of HIV itself in the pathogenesis of lipodystrophy.

Clinical Features As in hereditary lipodystrophy syndromes, fat redistribution may precede the development of metabolic complications. HIV/ART-associated lipodystrophy usually has its onset within the first 6 to 12 months after commencing therapy. In cross-sectional studies using DEXA scans and computed tomography, a 14–65% prevalence of central lipohypertrophy was noted within 1 to 2 years of initiation of ART71. However,

%

patient self-report, in concert with physician examination, still remains the earliest and best indicator of body shape change. Peripheral lipoatrophy occurs primarily in the face (Figs 101.15 & 101.16A), limbs (Fig. 101.16B), buttocks, and heel pads. The loss of subcutaneous facial fat, in particular the buccal, parotid and temporal fat, results in prominent zygomata, sunken eyes, deepened and redundant melolabial folds, and a cachectic facies. Central lipohypertrophy presents as: (1) an accumulation of intra-abdominal fat (omental, mesenteric, retroperitoneal), resulting in abdominal protrusion (“protease paunch”; “Crix belly”); and/or (2) increased fat deposition within the dorsocervical fat pad (“buffalo hump”), breasts (gynecomastia in men, larger breasts in women), anterior neck and/or lateral mandibular region, and the muscles and liver. Lipoma formation has also been noted, and the presence of a “buffalo hump” has been shown to be associated with insulin resistance and diabetes mellitus. The use of different combinations of drugs in ART may lead to distinct clinical syndromes of fat redistribution. For example, PIs are more frequently associated with central fat hypertrophy and metabolic derangements, whereas treatment with NRTIs (stavudine in particular) is a stronger independent risk factor for the development of peripheral fat wasting and lipoatrophy. In addition, multiple NRTI-induced complications related to mitochondrial toxicity, including myopathy,

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16

polyneuropathy, liver steatosis, pancreatitis, hyperlactatemia, bone marrow toxicity and a Fanconi-like syndrome, can also develop. HIV-related lipodystrophy is clearly associated with metabolic abnormalities72, including insulin resistance, diabetes, dyslipidemia (hypertriglyceridemia, decreased high-density lipoproteins [HDL]), and bone disorders, e.g. osteopenia, osteoporosis, avascular necrosis. Insulin resistance in HIV/ART-associated lipodystrophy arises via direct effects of PIs on insulin-mediated whole-body glucose uptake as well as the indirect effects of dyslipidemia, mitochondrial toxicity, and changes in body composition on whole-body insulin sensitivity. Adipocytokines, in particular leptin and adiponectin, affect insulin sensitivity and low levels of both factors have been observed in HIV/ART-associated lipodystrophy5,9. In HIV-infected patients receiving ART, the prevalence of metabolic syndrome has been reported to be 16–24%, resulting in an increased risk for cardiovascular disease73. The Data Collection on Adverse Events of Anti-HIV Drugs (DAD) study found an ~25% increase in the rate of myocardial infarction per year of ART during the first 4–6 years of exposure74. The most common significant risk factors for the development of lipoatrophy or lipohypertrophy are age (>40 years), disease severity at the onset of therapy (CD4 count 5 cm in diameter, can pose challenges beyond the complications noted above. They are often associated with extracutaneous anomalies, especially in female infants66. These hemangiomas may present as segmental telangiectatic patches (e.g. IH-MAG), vascular plaques, or deep masses. A relationship between facial hemangiomas and structural or vascular CNS anomalies was recognized >35 years ago67. Since then, other

PHACE(S) SYNDROME

Posterior fossa and other brain malformations, e.g. Dandy−Walker malformation, cerebellar hypoplasia Eye abnormalities, e.g. retinal vascular anomalies, optic nerve hypoplasia

Segmental infantile Hemangiomas, most often of the face and/or neck

Sternal defects

Supraumbilical raphe

Arterial anomalies, e.g. aplasia, dysplasia, and aneurysms of cervical and cerebral vessels

Coarctation of the aorta

Cardiac defects, e.g. ventricular septal defect, atrial septal defect

Fig. 103.14 PHACE(S) syndrome. Major clinical features are illustrated. Additional possible associated features include hearing impairment and endocrine abnormalities such as hypopituitarism and hypothyroidism. Inset,  

courtesy, Julie V Schaffer, MD.

Lower facial or “beard” hemangiomas often serve as markers of laryngeal hemangiomatosis, and the risk can be estimated by the extent of cutaneous involvement in this region (Fig. 103.16)76. However, airway hemangiomas are occasionally associated with segmental hemangiomas that primarily involve the upper face or small hemangiomas in the “beard” area77. Airway hemangiomas are typically subglottic. The onset of symptoms, which include noisy breathing and biphasic stridor, ranges from a few weeks to several months of age76. Infants with lower facial hemangiomas of concern should be referred for otolaryngologic evaluation. Hemangiomas located in the midline lumbosacral area (Fig. 103.17) are a marker for occult spinal dysraphism. The risk of spinal dysraphism in an infant or child with an isolated midline lumbosacral hemangioma or residuum of an involuted hemangioma >2.5 cm in diameter is ~35%78. Factors that further increase the risk include a larger or ulcerated hemangioma and the presence of additional cutaneous markers such as a deviated gluteal cleft, lipoma, or skin appendage (see Ch. 64)78. Large hemangiomas on the lower body, especially extensive segmental IHs-MAG, are associated with a broad spectrum of regional extracutaneous abnormalities, analogous to those of the upper body in PHACE(S) syndrome. Several acronyms have been proposed for this group of findings, and the most recent and inclusive is LUMBAR syndrome: L, lower body/lumbosacral hemangioma and lipomas or other cutaneous anomalies (e.g. “skin tags”); U, urogenital anomalies and ulceration of the hemangioma; M, myelopathy (spinal dysraphism); B, bony deformities; A, anorectal and arterial anomalies; and R, renal anomalies79 (Fig. 103.18). Recommendations for evaluation of infants with hemangiomas in a midline lumbosacral location and/ or a segmental distribution on the lower body are summarized in Fig. 103.15. Multifocal lesions are found in 10–25% of infants with hemangiomas and may be associated with visceral hemangiomatosis80. Most infants with both internal and skin involvement have many small, superficial cutaneous hemangiomas that range from a few millimeters to a few centimeters in diameter, referred to as a miliary pattern (Fig. 103.19). Evaluation for hepatic involvement is recommended when ≥5 skin lesions are present. Rarely, infants with a large hemangioma plus 30 cm2) hemangioma and fewer than five lesions in total85. Segmental cutaneous hemangiomas are occasionally associated with segmental hemangiomas in the gastrointestinal tract, most often in the distribution of the superior mesenteric artery and potentially complicated by bleeding86. True IHs within the CNS are rare, affecting only 1% (15/1454) of patients seen at a vascular anomalies referral center over a 10-year period87. Most of these represented intracranial or intraspinal extension of an overlying IH, some of which were segmental lesions; a few patients had hydrocephalus, but invasion into the CNS parenchyma was not observed87. Additional sites of internal involvement rarely

CHAPTER

103 Infantile Hemangiomas

associated congenital anomalies have been identified. In 199668, the acronym PHACE(S) syndrome was coined for this spectrum of findings: P, posterior fossa and other structural brain malformations; H, hemangioma; A, arterial anomalies of cervical and cerebral vessels; C, cardiac defects (especially coarctation of the aorta); E, eye anomalies; and S, sternal defects and supraumbilical raphe (Fig. 103.14). Occasionally, impaired hearing and endocrine abnormalities such as hypopituitarism and hypothyroidism are additional features69,70. Diagnostic criteria for PHACE(S) syndrome were established by a multidisciplinary group of specialists in 2009 and updated in 201671,72 (Table 103.4). In a prospective study of 108 infants (age 5 cm in diameter of the head including scalp PLUS 1 major criterion or 2 minor criteria • Hemangioma of the neck, upper trunk, or trunk and proximal upper extremity PLUS 2 major criteria Possible PHACE(S): • Hemangioma >5 cm in diameter of the head including scalp PLUS 1 minor criterion • Hemangioma of the neck, upper trunk, or trunk and proximal upper extremity PLUS 1 major criterion or 2 minor criteria • No hemangioma PLUS 2 major criteria

Organ system

Major criteria

Arterial

Anomalies of major cerebral or cervical arteries* – dysplasia**, hypoplasia, stenosis/occlusion, aberrant origin/course • Persistent carotid–vertebrobasilar anastomosis (e.g. proatlantal segmental, hypoglossal, otic, trigeminal arteries)

Minor criteria

Structural brain



Aneurysm of cerebral arteries



Cardiovascular



Posterior fossa anomalies – Dandy–Walker complex, other hypoplasia/dysplasia of the mid or hind brain



Midline anomalies Malformation of cortical development



Aortic arch anomalies Aberrant origin of subclavian artery ± vascular ring







Posterior segment anomalies – persistent hyperplastic primary vitreous/ persistent fetal vasculature, retinal vascular anomalies, optic nerve hypoplasia, morning glory disc anomaly



Sternal defect/pit/cleft Supraumbilical raphe



Ventricular septal defect Right/double aortic arch • Systemic venous anomalies

Ocular



Ventral or midline









Anterior segment anomalies, e.g. sclerocornea, cataract, coloboma, microphthalmia

Hypopituitarism Ectopic thyroid • Midline sternal papule/hamartoma

*Includes internal carotid artery; middle, anterior, or posterior cerebral artery; and vertebrobasilar system. **Includes kinking, looping, tortuosity, and/or dolichoectasia. Table 103.4 Diagnostic criteria for PHACE(S) syndrome71,72.  

EVALUATION OF A CHILD WITH INFANTILE HEMANGIOMAS FOR POSSIBLE SYSTEMIC INVOLVEMENT

*

Multiple (≥5) hemangiomas

• Abdominal (hepatic) ultrasound • Consider CBC, stool guaiac, and

Abnormal +

urinalysis

− Within normal limits

• Echocardiogram, cardiac evaluation • TFTs if hepatic hemangiomas • Consider a chest X-ray • Consider an abdominal CT/MRI

"Beard" hemangiomas

ENT evaluation, laryngoscopy

+ Abnormal

Segmental hemangioma

**

Cervicofacial : exclude PHACE(S) syndrome

Ophthalmologic examination Echocardiogram, cardiac evaluation • MRI/MRA of head and neck • •

Evaluation of other organ systems as clinically indicated

Serial examinations Treatment as indicated

Serial physical examinations

Serial examinations Treatment as indicated

Serial examinations Treatment as indicated

CT, computed tomography; MRI, magnetic resonance imaging; MRA, magnetic resonance angiography; MRV, magnetic resonance venography; TFTs, thyroid function tests

* In infants ≤6 months of age and as clinically indicated in older infants. **† Consider evaluation for hepatic/gastrointestinal tract involvement and thyroid abnormalities if a large lesion.

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LUMBAR: lower body/l umbosacral hemangioma, l ipoma/other skin lesions; urogenital anomalies, ulceration; myelopathy (spinal dysraphism); bony deformities; anorectal malformations, arterial anomalies; renal anomalies. Also referred to as SACRAL (spinal dysraphism, anogenital anomalies, cutaneous anomalies, renal/urologic anomalies, angioma, in l umbosacral area) and PELVIS (perineal hemangioma, external genital malformations, lipomyelomeningocele, vesicorenal abnormalities, i mperforate anus, skin tag) syndrome.

Fig. 103.15 Evaluation of a child with infantile hemangiomas for possible systemic involvement.  

**

Lower body and/or lumbosacral : exclude LUMBAR syndrome†

Initial evaluation (preferably at age 0.8 Screen for neuropathy – nylon monofilament testing

CHAPTER

105 Ulcers

Fig. 105.8 Approach to the evaluation and treatment of chronic venous ulcers. See Table 105.8 for determination and interpretation of the ankle-brachial index (ABI). EMG, electromyography.

*

Treatment

• Compression • Leg elevation

Local wound care, including: • Dressings (see Ch. 145) • Debridement (autolytic, chemical, and/or mechanical) • Treat surrounding stasis dermatitis if present • Antimicrobial therapy, as needed (topical or systemic) • Occasionally, vacuum-assisted closure (VAC) Tetanus booster vaccination

Expected healing

Consider venous surgery if superficial reflux present

Non-healing

Consider skin constructs, pinch grafts

*May be falsely high in diabetics ABI, ankle−brachial index

Reconsider the diagnosis and reassessment (see Fig. 105.1), including possible biopsy, tissue culture, hypercoagulability evaluation, serologies, imaging for osteomyelitis, EMG, genetic testing

CAUSES OF LYMPHEDEMA

Primary lymphedema

Secondary lymphedema

Congenital lymphedema (presents at birth or within first 1–2 years of life)



Congenital aplasia of the thoracic duct Hypoplasia of peripheral lymphatics • Congenital abnormalities of the abdominal or thoracic lymphatics • Hereditary (Milroy disease; type 1A): AD; caused by VEGFR3 (FLT4) mutations in some families • Turner syndrome • Noonan syndrome and other RASopathies • Osteoporosis, lymphedema, hypohidrotic ectodermal dysplasia, and immunodeficiency (OL-HED-ID)



• •

Lymphedema praecox (presents around puberty)

Recurrent lymphangitis and cellulitis Parasitic infections, e.g. filariasis • Lymph node dissection, e.g. for melanoma or breast cancer • Malignant obstruction, e.g. lymphoma, Kaposi sarcoma, retroperitoneal sarcoma • Radiation injury • Obesity • Surgical excisions, e.g. mastectomy, prostatectomy • Podoconiosis (exposure to mineral microparticles in volcanic soils) • Acne vulgaris and acne rosacea (midface) • Granulomatous disease (e.g. Crohn disease, granuloma inguinale, sarcoidosis)

Meige disease (type II); yellow nail syndrome; lymphedema–distichiasis syndrome: AD; caused by FOXC2 mutations in some families • Hypotrichosis–lymphedema–telangiectasia syndrome: AR or AD (with renal defect); caused by SOX18 mutations •

Lymphedema tarda (presents after age 35 years)

Table 105.7 Causes of lymphedema. In distichiasis, there is abnormal growth of eyelashes from the orifices of meibomian glands, leading to a double row of eyelashes. AD, autosomal dominant; AR, autosomal recessive. Table 104.2 lists additional forms of hereditary lymphedema, e.g. Hennekam lymphangiectasia– lymphedema syndrome (CCBE1 or FAT4), lymphedema-microcephaly-chorioretinopathy syndrome (KIF11), and primary lymphedema with myelodysplasia (GATA2). WILD syndrome is discussed in Ch. 79, with the L representing lymphedema.  

Clinically, lymphedema begins as painless pitting edema of the dorsal aspect of the foot which then progresses proximally. Over time, the skin becomes indurated due to fibrosis, and the affected areas are prone to ulceration and secondary infection. Recurrent infections lead to worsening of the lymphedema and a vicious cycle is established28. Elephantiasis nostras verrucosa is a complication of chronic lymphedema and most commonly affects the feet and distal lower extremities. In addition to profound non-pitting edema and progressive fibrosis of the dermis and subcutaneous tissue, there are verrucous changes with papillomatosis and hyperkeratosis (Fig. 105.11B). The skin acquires a

mossy or cobblestone appearance and discrete firm fibrous papules or nodules may develop. Colonization with bacteria and fungi often results in ulcers becoming crusted and malodorous38. Elephantiasis nostras verrucosa is difficult to treat. Compression stockings, pneumatic pumps and massage are used to decrease lymph accumulation. Topical keratolytics or humectants, such as salicylic acid and urea, may improve the hyperkeratosis38. Oral retinoids have been reported to be of benefit for both the verrucous changes and the lymphedema39. Surgical debridement can be considered for patients who do not respond to more conservative therapies40.

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Fig. 105.12 Lipedema. This middle-aged woman has bilateral “stovepipe” enlargement of the legs and minimal involvement of the feet. Note the sharp demarcation between normal and abnormal tissue at the ankle, referred to as the “cuff sign”. Courtesy, Jean L Bolognia,

Vascular Disorders



MD.

Fig. 105.9 Bilateral primary lymphedema due to Milroy disease.  

Fig. 105.10 Lymphedema secondary to morbid obesity associated with myxedema.  

ARTERIAL ULCERS Peripheral arterial disease (PAD) is a common manifestation of atherosclerosis. Cigarette smoking and diabetes mellitus are the strongest risk factors, with hypertension, dyslipidemia and hyperhomocysteinemia representing additional risk factors42. Up to 25% of patients with leg ulcers have PAD, and a significant number of patients have a combination of arterial and venous insufficiencies15.

Pathogenesis A lack of blood perfusion decreases tissue resilience and leads to tissue necrosis; it also impedes wound healing by reducing the supply of oxygen, nutrients, and soluble mediators involved in the repair process. Although PAD alone infrequently precipitates ulceration, arterial insufficiency plays a major role in delayed wound healing and complications including gangrene. Ischemic foot ulcers are often precipitated by trauma in a patient with relatively mild symptoms of arterial insufficiency. In such an individual, the degree of skin perfusion is sufficient to maintain cutaneous integrity, but is not adequate enough to support proper wound healing. In such a setting, the ulcer will inevitably progress into a chronic wound or gangrene unless perfusion is restored43.

Clinical Manifestations

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Fig. 105.11 Elephantiasis nostras verrucosa. A Podoconiosis (endemic, nonfilarial elephantiasis) due to pedal exposure to volcanic soils. B The patient had both lymphedema and venous insufficiency. Note the involvement of the foot. A, Courtesy, Claire Fuller, MD.  

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The differential diagnosis includes lipedema41, in which there is an abnormal deposition of subcutaneous fat and lymphatic vessel dysfunction with sparing of the feet (Fig. 105.12), thyroid dermopathy (pretibial myexedema), and obesity-associated lymphedematous mucinosis, where there can be dermal mucin deposition in the absence of thyroid disease.

Most patients with significant PAD are symptom-free. Intermittent claudication, defined as leg pain induced by ambulation and relieved by resting, represents the earliest and the most common presenting symptom of PAD of the lower extremities. With disease progression, patients begin to complain of pain at rest, especially when the legs are elevated in bed at night, which is ameliorated by dependency. While symptoms of claudication are usually localized to the calf or the thigh, pain at rest is often felt in the feet. In advanced stages of PAD, the reduction in cutaneous blood supply may lead to ischemic ulceration and gangrene, and this may necessitate amputation44. Arterial ulcers are usually round with a sharply demarcated border and are characterized by an absence of bleeding (Fig. 105.13). These wounds typically occur on the distal lower extremities, often over bony prominences. The surrounding skin may be hairless, shiny and atrophic. Wound pain is often significant and is exacerbated by limb elevation. Additional manifestations of impaired arterial perfusion to the foot include diminished or absent pedal pulses, cool feet, pallor of the foot with elevation of the leg and then subsequent redness with lowering (dependent rubor), sluggish refilling of toe capillaries, thickened nails, and absence of toe hair (see Table 105.1)15,43.

Laboratory Evaluation The ankle–brachial pressure index, more commonly referred to as the ankle–brachial index (ABI), is a simple, non-invasive test that is widely used for diagnosis of PAD and to assess its severity. The ABI is calculated by dividing the systolic blood pressure in the ankle by the systolic blood pressure in the arm while the patient is in a resting supine



CHAPTER

105 Ulcers

Fig. 105.14 Cholesterol emboli. Ischemia of the toes and necrosis with early ulcer formation.

Fig. 105.13 Arterial ulcer. The punched-out appearance and surrounding smooth shiny skin are common features.  

DETERMINATION AND INTERPRETATION OF THE ANKLE–BRACHIAL INDEX With the patient in a supine position, the systolic blood pressure is measured in the: • brachial arteries (right and left) • dorsalis pedis and posterior tibial arteries (right and left) • The ABI is determined by: •

the highest of the systolic pressures from the dorsalis pediis or posterior tibial arteries the higher of the brachial artery systolic pressures Interpretation of the ABI: 0.91–1.30 = normal range >1.30 = suggests incompressible tibial arteries due to medial calcification (diabetes mellitus, chronic renal insufficiency, older age) 32 mmHg (normal capillary pressure range = 12–32 mmHg) usually compromise oxygenation and microcirculation. There is an inverse time–pressure curve, with slow ulcer formation at low pressures and rapid ulcer formation at high pressures (≥70 mmHg). The length of continuous exposure of the skin to pressure is also of critical importance, thus explaining why intermittent relief of the pressure can prevent ulcer formation. Because subcutaneous tissues are most susceptible to the damaging effects of prolonged exposure to pressure, deep tissue trauma can occur with relatively little superficial damage that would alert caregivers to the extent of tissue injury63.

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Shearing forces result from the sliding and relative displacement of two apposing surfaces. Although externally applied pressure is more effective than shearing forces alone in reducing skin arteriolar blood flow, these two factors can combine to enhance vascular occlusion. When the head of a supine patient is raised more than 30°, shearing forces occur in the sacral and coccygeal areas. Sliding of the torso transmits pressure to the sacrum and deep fascia, as the outer sacral skin is fixed because of friction with the bed. Vessels within the deeper portion of the superficial fascia angulate and thrombose, which manifests clinically as undermining of the ulcer63. Friction is often associated with shearing and it reflects the degree of resistance generated when two surfaces move across each other. When a bedridden patient is dragged across the bed sheets, friction is produced. Damage to the protective stratum corneum enhances ulcer formation by compromising the skin barrier. Fig. 105.18 Black eschar of the heel at site of pressure necrosis.  

Moisture results from perspiration due to fevers and from urine and feces. It has been shown to increase the risk of pressure ulcer formation fivefold63.

Clinical Features Pressure ulcers are usually classified according to a four-stage system designed by the National Pressure Ulcer Advisory Panel (NPUAP) (Fig. 105.19). Of note, the ulcers do not necessarily progress sequentially from stage I to stage IV, nor do they necessarily heal from stage IV to stage I64. Stage I: nonblanchable erythema of intact skin which heralds skin ulceration. For darker-skinned individuals, warmth, edema, discoloration of the skin, and induration may serve as indicators of impending ulceration63,64. Stage II: partial-thickness skin loss involving the epidermis, dermis, or both. This superficial lesion presents as an erosion, blister, or shallow ulcer63,64. Stage III: full-thickness skin loss with damage to the subcutaneous tissue, extending down to (but not including) the underlying fascia. This deep lesion presents as a crater-like ulcer and sometimes involves adjacent tissue63,64. Stage IV: full-thickness skin loss and extensive tissue necrosis with destruction extending to muscle, bone, or supporting structures such as tendons or joint capsules. Undermining or sinus tracts can be present63,64. As mentioned previously, a major limitation in the clinical classification of pressure ulcers stems from the fact that extensive deep tissue damage may be accompanied initially by minimal superficial manifestations. Adequate evaluation may also be hampered by the presence of an eschar, which should be debrided for full assessment63.

• • • •

Pathology When the diagnosis is in doubt or when a secondary malignancy is suspected in the setting of a longstanding lesion, histologic examination is indicated. In all four stages, the histopathologic findings are rather nonspecific. When there is blanchable erythema clinically, the superficial dermal capillaries and venules are dilated. Mild to moderate edema within the papillary dermis is seen in association with a Fig. 105.19 National Pressure Ulcer Advisory Panel classification of pressure ulcers. A Stage I: nonblanchable erythema of intact skin. This lesion is the heralding sign of impending skin ulceration. For darker-skinned individuals, other signs may be indicators and include warmth, edema, discoloration of the skin, and induration. B Stage II: partialthickness skin loss involving the epidermis, dermis or both. This superficial lesion presents as an abrasion, blister or shallow crater. C Stage III: full-thickness skin loss, in which subcutaneous tissue is damaged or necrotic and may extend down into, but not including, the underlying fascia. This deep lesion presents as a crater and sometimes involves adjacent tissue. D Stage IV: full-thickness skin loss and extensive tissue necrosis, destruction to muscle, bone, or supporting structures such as a tendon or joint capsule. Undermining or sinus tracts can be present.  

NATIONAL PRESSURE ULCER ADVISORY PANEL CLASSIFICATION OF PRESSURE ULCERS Fascia Epidermis Dermis Subcutaneous fat Muscle Bone

A

Stage I Nonblanchable erythema with induration and warmth

B

Stage II Irregular shallow ulceration; loss of epidermis, dermis or both, with erythema, induration and warmth

Undermining

1842

C

Stage III Deep ulceration with necrotic base

D

Stage IV Deep ulceration reaching underlying bone

Treatment Pressure ulcers are preventable, primarily by relief of pressure on the skin. This can be accomplished by frequent position changes in addition to use of a variety of support surfaces to relieve pressure; the latter include air- or liquid-filled flotation devices, foam products, and pillows or foam wedges as positioning devices. Adequate nutrition, education, pain management, and psychosocial support are also important interventions. Causes of immobility and systemic conditions that interfere with wound healing or decrease tissue perfusion must be addressed, including congestive heart failure, diabetes, and/or spastic paresis. The general principles of ulcer and chronic wound care discussed previously also apply to pressure ulcer management. Briefly, debridement may be accomplished via mechanical, enzymatic, and/or autolytic means. Wounds should be cleansed as non-traumatically as possible, and normal saline for irrigation is preferred rather than cytotoxic agents

such as hydrogen peroxide or povidone-iodine. As always, bacterial colonization and infection must be controlled. Dressings should provide a moist, but not macerated, environment and occlusive dressings are often utilized. In general, stage I, II, and III pressure ulcers are more likely to heal with local therapy, whereas stage IV ulcers, particularly those over the ischial tuberosities, often require surgical intervention. Adjuvant therapies such as laser, ultrasound, hyperbaric oxygen, and UV irradiation are investigational and to date cannot be considered as standard of care. The application of growth factors, cultured keratinocyte grafts, and skin substitutes is promising, but these are also still in the investigational stage.

CHAPTER

105 Ulcers

mild perivascular lymphocytic infiltrate. The epidermis, pilosebaceous structures, and reticular dermis remain normal. At the stage of nonblanchable erythema, engorgement of capillaries and venules with red blood cells, platelet thrombi, and hemorrhage are observed in the papillary dermis. Although the epidermis still appears normal, sweat gland and subcutaneous fat degeneration is often present63. Subepidermal separation can occur with formation of a subepidermal bulla. In early ulcers, the epidermis is lost and acute inflammation of the papillary and reticular dermis is seen. Chronic ulcers have a diffusely fibrotic dermis with a loss of adnexa. The surface may have a hemorrhagic crust containing acute inflammatory cells or a thin zone of coagulation necrosis. In the black eschar stage, full-thickness destruction of the skin occurs. General dermal architecture is preserved, but there is obliteration of cellular details.

OTHER CAUSES OF SKIN ULCERATION Ulcers that are apparently recalcitrant to prescribed treatments should be reevaluated regarding compliance with the program of care, and when non-compliance is excluded, then rare or unusual causes should be considered (see Fig. 105.1).

Diffuse Dermal Angiomatosis Diffuse dermal angiomatosis is an unusual manifestation of vascular atherosclerosis. There is rather rapid development of one or several violaceous plaques in a reticulated pattern, often with central ulceration. The lesions are typically painful and are usually located on the lower extremities, but they may appear elsewhere (e.g. breast, forearm) (Fig. 105.20A). Histologically, a diffuse interstitial proliferation of CD31-positive endothelial cells is present within the papillary and reticular dermis, with focal formation of small vascular channels. Cytologic atypia and atypical mitoses are absent.

Fig. 105.20 Additional causes of ulcers. A Diffuse dermal angiomatosis develops most often in pendulous breasts (note the scars from previous breast reduction surgery) and the lower extremities in association with atherosclerosis. B Multiple ulcers secondary in a patient with sickle cell anemia. C Systemic sclerosis with an ulcer of the fingertip.   D Necrobiosis lipoidica. Controversy exists about the exact risk of diabetes mellitus in such patients, but it is much more strongly associated with diabetes than is granuloma annulare.    

A, Courtesy, Margo Peters, MD; D, Courtesy, Jeffrey P Callen, MD.

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17

Interventions to correct the underlying PAD, such as femoral artery angioplasty or femoral popliteal bypass surgery, lead to rapid resolution. Less often, lesions resolve without therapy65.

Hematologic Disorders Anemia is a major and often underrecognized cause for delayed wound healing. It prevents proper tissue oxygenation. In addition, some forms of anemia are associated with a marked tendency for ulcer formation, such as the hemoglobinopathies (Fig. 105.20B)66. Hematologic

malignancies are also associated with ulcerative processes including pyoderma gangrenosum, vasculitis, and cryoglobulinemia (particularly type I). Clotting abnormalities can play a direct role in the formation of ulcers (e.g. antiphospholipid antibody syndrome)67,68, as well as serving as a predisposing factor for more common types of cutaneous ulcerations such as venous ulcers69,70. Acute massive venous thrombosis, also known as phlegmasia cerulea dolens, can lead to massive edema in the legs, with subsequent ischemia and ulceration due to venous limb gangrene71. Table 105.9 summarizes the recommended evaluation when thrombophilia is suspected.

EVALUATION FOR THROMBOPHILIA

%*

Screening tests

Potential confounding conditions

5

Activated protein C (APC) resistance†

Warfarin, heparin, OCP, pregnancy, ↑ factor VIII level, lupus anticoagulant†

5

Factor V Leiden mutation (AD) [reflex test if APC detected]



Prothrombin G20210A

2

Prothrombin G20210A mutation (AD)



Protein C deficiency

0.3

↓ Protein C activity (AD)

Warfarin, OCP, pregnancy, liver disease, ↑ factor VIII level, lupus anticoagulant, acute thrombosis

Protein S deficiency

0.05

↓ Free protein S antigen level and/or activity (AD)

Warfarin, OCP, pregnancy, liver disease, ↑ factor VIII level, lupus anticoagulant, acute thrombosis

Antithrombin deficiency

0.1

↓ Antithrombin activity (AD)

Heparin, liver disease, acute thrombosis

Hyperhomocysteinemia

>5

↑ Homocysteine level (may have homozygous MTHFR C677T mutation or be compound heterozygote for MTHFR C677T/A1298C > heterozygous CBS mutation)

Deficient folate, B12 or B6; older age, smoking

Excess factor VIII/von Willebrand factor

10

↑ Factor VIII level

Acute phase response, OCP, pregnancy, old age

Excess fibrinogen

ND

↑ Fibrinogen level

Acute phase response, pregnancy, smoking, older age

Dysfibrinogenemia

ND

↓ Functional fibrinogen; ↑ thrombin time

Heparin, recent birth, liver disease

Excess lipoprotein (a)

10

↑ Lipoprotein (a) level



Excess plasminogen activator inhibitor-1 (PAI-1)

ND 10

↑ PAI-1 PAI 4G/4G polymorphism (promoter)

Wide range of normal values and diurnal variation

Thrombomodulin deficiency

ND (rare)

↓ Thrombomodulin



Plasminogen deficiency

ND

↓ Plasminogen



Lupus anticoagulant‡

ND

↑ RVVT (dilute), sensitive PTT, or kaolin clotting time§

Warfarin, heparin, direct oral anticoagulants (DOACs)

Anticardiolipin antibodies‡

ND

IgG or IgM anti-cardiolipin antibodies at moderate–high levels, on ≥2 occasions ≥12 weeks apart

Various infectious diseases

Anti-β2-glycoprotein I antibodies‡

ND

Anti-β2-glycoprotein I antibodies present, on ≥2 occasions ≥12 weeks apart



Cryoglobulinemia, type I

ND

Type I cryoglobulins present



Heparin-induced thrombocytopenia

ND**



Disorder Inherited Factor V Leiden

Acquired



Cryofibrinogenemia

ND

Screening: anti-heparin/platelet factor 4 (PF4) antibodies Confirmatory: serotonin release assay

Cryofibrinogens present



Acute phase response

*† Approximate percentage of general population with the defect.

Factor V Leiden accounts for ~ 90–95% of patients with APC resistance when the latter is assessed by “second generation” assays, which are not limited by most potential confounding conditions.

‡Antiphospholipid antibodies. §Confirmed by: (1) failure to correct the prolonged coagulation time in mixing studies; and (2) correction with the addition of excess phospholipids.

**Exposed to heparin or low-molecular-weight heparin.

Table 105.9 Evaluation for thrombophilia. Darkly shaded areas represent first-tier screening tests; lighter shading denotes screening for hyperhomocysteinemia remains controversial and screening for heparin-induced thrombocytopenia is situational. Drugs in bold can significantly affect test. The initial laboratory evaluation should also include a complete blood count with differential and platelet count, examination of a peripheral blood smear, ESR, activated partial thromboplastin time (PTT), and hepatic and renal function panels. Testing for antineutrophil cytoplasmic antibodies (ANCA) can be considered for patients with retiform purpura, as ANCA-positive vasculitides occasionally present with minimally inflammatory lesions. Additional inherited causes of thrombophilia include polymorphisms in the genes encoding the endothelial protein C receptor, the protein Z-dependent protease inhibitor, and E-selectin while whole exome sequencing can detect variants in other genes including those that encode serine protease inhibitors (SERPINs). AD, autosomal dominant; CBS, cystathionine β-synthase; MTHFR, methylenetetrahydrofolate reductase; ND, not determined; OCP, oral contraceptive pills; RVVT, Russell viper venom time.  

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CHAPTER

Cause

Favored anatomic site

Location of review

Site of exposure

Chapters 15, 16, 88

Physical Burns – thermal, electrical, chemical Cold injury (e.g. frostbite)

Acral

Chapter 88

Radiation (e.g. orthovoltage)

Site of exposure

Chapter 139

Lower extremities

Chapter 24; Fig. 105.1

Ulcers

105

ADDITIONAL CAUSES OF CUTANEOUS ULCERATION

Inflammatory Vasculitis (small and medium-sized vessels, primary and secondary) Pyoderma gangrenosum

Lower extremities, sites of trauma

Chapter 26

Necrobiosis lipoidica

Lower extremities

Chapter 93

Behçet disease

Lower extremities

Chapter 26

Panniculitis, (e.g. nodular vasculitis, equestrian cold panniculitis/ perniosis)

For the two examples, calves and outer thighs

Chapter 100

Digital, extensor surface of joints

Chapter 43

Exposed sites Pressure sites in the case of leprosy and tertiary syphilis*

Chapters 74–83; Fig. 105.1

Vascular Raynaud phenomenon and systemic sclerosis Infectious Bacterial (e.g. Streptococcus spp., Treponema spp.), mycobacterial, viral (e.g. chronic HSV), fungal, parasitic Bites and stings

Chapter 85

Neoplastic BCC, SCC > metastases, other primary cutaneous malignancies (epithelial and non-epithelial), cutaneous T- and B-cell lymphomas

For BCC and SCC, sites of chronic sun exposure For SCC, chronic ulcers, scars, sites of chronic inflammation or oncogenic HPV infection

Chapters 108, 120, 122

Varies from juxta-articular (calcinosis cutis, gout) to “fatty” areas (calciphylaxis)

Chapters 48, 50

Varies from scalp due to aplasia cutis congenita to lower extremity

Chapters 41, 45, 50, 60, 63, 64; Fig. 105.1

Hydroxyurea

Lower extremities

Chapters 21, 23

Methotrexate

Psoriatic plaques

Warfarin

“Fatty” areas, e.g. breasts

Heparin

Sites of injection and distant sites

All-trans retinoic acid (systemic)

Scrotum

Interferon, glatiramer acetate

Sites of sc injection**

NSAIDs, penicillin, hydroxyzine, vitamin K, chlorpheniramine, bismuth salts

Sites of IM injection**

Metabolic Examples: calcinosis cutis, calciphylaxis, gout Genodermatoses Examples: Adams–Oliver syndrome, prolidase deficiency, laryngo-onycho-cutaneous syndrome, familial tumoral calcinosis, Werner syndrome, familial chilblain lupus (TREX1 mutations), Klinefelter syndrome, leukocyte adhesion deficiency, SAVI Drugs

Photodamage Erosive pustular dermatosis

Usually hairless scalp, but occasionally lower extremity

Chapter 87

*Due to neuropathy. **Associated with ischemia in a livedo pattern in Nicolau syndrome. Table 105.10 Additional causes of cutaneous ulceration. In addition to lower extremity ulcers, patients with prolidase deficiency develop diffuse telangiectasias, dermatitis, lymphedema and manifestations of systemic lupus erythematosus. BCC, basal cell carcinoma; HPV, human papillomavirus; HSV, herpes simplex virus; IM, intramuscular; sc, subcutaneous; SAVI, STING (stimulator of interferon genes)-associated vasculopathy with onset in infancy; SCC, squamous cell carcinoma.  

Tropical Ulcers These ulcers are found in children and adults residing in the tropics who typically live in rural areas and are malnourished or otherwise debilitated. They may also occur in travelers returning from those areas. Although many tropical diseases manifest with chronic ulceration, the term “tropical ulcer” is often used to describe a phagedenic ulcer, usually located on the leg, which often occurs secondarily to minor trauma72.

The ulcer is invariably associated with a polymicrobial infection including Fusobacterium spp., other anaerobic bacteria, and spirochetes. Tropical ulcers are always painful and progress rapidly to often involve deep tissues. The edges are undermined and violaceous, and malignant degeneration can occur. Assessment includes a smear and cultures plus soft tissue and bone imaging when deep involvement is suspected. These ulcers are best managed with systemic antibiotics (e.g.

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tetracycline, metronidazole) and nonadherent dressings; they occasionally require surgical debridement. The differential diagnosis of tropical ulcers73 includes other common causes of ulceration in tropical areas such as bacterial (including anthrax), mycobacterial, deep fungal, and parasitic (leishmaniasis) infections as well as non-infectious causes such as sickle cell anemia, venous insufficiency, neuropathy, and trauma.

Additional Causes A variety of physical, inflammatory, infectious, metabolic, and inherited disorders are also associated with cutaneous ulceration (Fig. 105.20C,D) and they are outlined in Fig. 105.1 and Table 105.10. For additional online figures visit www.expertconsult.com

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ulcers. Results of a prospective investigation in 100 patients. Dermatology 2008;217:69–73. O’Meara S, Tierney J, Cullum N, et al. Four layer bandage compared with short stretch bandage for venous leg ulcers: systematic review and meta-analysis of randomised controlled trials with data from individual patients. BMJ 2009;338:b1344. Barwell JR, Davies CE, Deacon J, et al. Comparison of surgery and compression with compression alone in chronic venous ulceration (ESCHAR study): randomised controlled trial. Lancet 2004;363:1854–9. Kerchner K, Fleischer A, Yosipovitch G. Lower extremity lymphedema update: pathophysiology, diagnosis, and treatment guidelines. J Am Acad Dermatol 2008;59:324–31. Mayrovitz HN. The standard of care for lymphedema: current concepts and physiological considerations. Lymphat Res Biol 2009;7:101–8. Hunter JE, Teot L, Horch R, Banwell PE. Evidence-based medicine: vacuum-assisted closure in wound care management. Int Wound J 2007;4:256–69. Venturi ML, Attinger CE, Mesbahi AN, et al. Mechanisms and clinical applications of the vacuum-assisted closure (VAC) device: a review. Am J Clin Dermatol 2005;6:185–94. Rizzi SC, Upton Z, Bott K, Dargaville TR. Recent advances in dermal wound healing: biomedical   device approaches. Expert Rev Med Devices 2010;7:143–54. Dabiri G, Heiner D, Falanga V. The emerging use of bone marrow-derived mesenchymal stem cells in the treatment of human chronic wounds. Expert Opin Emerg Drugs 2013;18:405–19. Kirsner RS, Marston WA, Snyder RJ, et al. Spray-applied cell therapy with human allogeneic fibroblasts and keratinocytes for the treatment of chronic venous leg ulcers: a phase 2, multicentre, double-blind, randomised, placebo-controlled trial. Lancet 2012;380:977–85. Paquette D, Badiavas E, Falanga V. Short-contact topical tretinoin therapy to stimulate granulation tissue in chronic wounds. J Am Acad Dermatol 2001;45:382–6. Jull A, Waters J, Arroll B. Pentoxifylline for treatment of venous leg ulcers: a systematic review. Lancet 2002;359:1550–4. Brice G, Child AH, Evans A, et al. Milroy disease and the VEGFR-3 mutation phenotype. J Med Genet 2005;42:98–102. Sisto K, Khachemoune A. Elephantiasis nostras verrucosa: a review. Am J Clin Dermatol 2008;9:  141–6. Zouboulis CC, Biczo S, Gollnick H, et al. Elephantiasis nostras verrucosa: beneficial effect of oral etretinate therapy. Br J Dermatol 1992;127:411–16. Iwao F, Sato-Matsumura KC, Sawamura D, Shimizu H. Elephantiasis nostras verrucosa successfully treated by surgical debridement. Dermatol Surg 2004;30:939–41. Langendoen SI, Habbema L, Nijsten TEC, Neumann HAM. Lipoedema: from clinical presentation to therapy. A review of the literature. Br J Dermatol 2009;161:980–6. White C. Clinical practice. Intermittent claudication. N Engl J Med 2007;356:1241–50. Sumpio BE. Foot ulcers. N Engl J Med 2000;343:787–93. Ouriel K. Peripheral arterial disease. Lancet 2001;358:1257–64. Al-Qaisi M, Nott DM, King DH, Kaddoura S. Ankle brachial pressure index (ABPI): an update for practitioners. Vasc Health Risk Manag 2009;5:833–41. Grenon SM, Gagnon J, Hsiang Y. Video in clinical medicine. Ankle-brachial index for assessment of peripheral arterial disease. N Engl J Med 2009;361:  e40. Cavanagh PR, Lipsky BA, Bradbury AW, Botek G. Treatment for diabetic foot ulcers. Lancet 2005;366:1725–35.

48. Alavi A, Sibbald RG, Mayer D, et al. Diabetic foot ulcers: Part II. Management. J Am Acad Dermatol 2014;70:21. e1–24. 49. Andersen CA, Roukis TS. The diabetic foot. Surg Clin North Am 2007;87:1149–77, x. 50. Falanga V. Wound healing and its impairment in the diabetic foot. Lancet 2005;366:1736–43. 51. Boulton AJ. Pressure and the diabetic foot: clinical science and offloading techniques. Am J Surg 2004;187:17S–24S. 52. Richard J-L, Sotto A, Lavigne J-P. New insights in diabetic foot infection. World J Diabetes 2011;15:24–32. 53. Boulton AJ, Kirsner RS, Vileikyte L. Clinical practice. Neuropathic diabetic foot ulcers. N Engl J Med 2004;351:48–55. 54. Kranke P, Bennett M, Roeckl-Wiedmann I, Debus S. Hyperbaric oxygen therapy for chronic wounds. Cochrane Database Syst Rev 2004;(2):CD004123. 55. Thackham JA, McElwain DL, Long RJ. The use of hyperbaric oxygen therapy to treat chronic wounds: a review. Wound Repair Regen 2008;16:321–30. 56. Tecilazich F, Dinh TL, Veves A. Emerging drugs for the treatment of diabetic ulcers. Expert Opin Emerg Drugs 2013;18:207–17. 57. Steed DL. Clinical evaluation of recombinant human platelet-derived growth factor for the treatment of lower extremity ulcers. Plast Reconstr Surg 2006;117:143S–149S, discussion 150S–151S. 58. White R, McIntosh C. A review of the literature on topical therapies for diabetic foot ulcers. Part 2: Advanced treatments. J Wound Care 2009;18:335–41. 59. Dinh TL, Veves A. The efficacy of Apligraf in the treatment of diabetic foot ulcers. Plast Reconstr Surg 2006;117:152S–157S, discussion 8S–9S. 60. Marston WA. Dermagraft, a bioengineered human dermal equivalent for the treatment of chronic nonhealing diabetic foot ulcer. Expert Rev Med Devices 2004;1:21–31. 61. Mayfield JA, Reiber GE, Sanders LJ, et al. Preventive foot care in diabetes. Diabetes Care 2004;27(Suppl. 1):S63–4. 62. Markuson M, Hanson D, Anderson J, et al. The relationship between hemoglobin A(1c) values and healing time for lower extremity ulcers in individuals with diabetes. Adv Skin Wound Care 2009;22:365–72. 63. Olesen CG, de Zee M, Rasmussen J. Missing links in pressure ulcer research — an interdisciplinary overview.   J Appl Physiol 2010;108:1458–64. 64. Morton LM, Phillips TJ. Wound healing and treating wounds: Differential diagnosis and evaluation of chronic wounds. J Am Acad Dermatol 2016;74:589–605. 65. Draper BK, Boyd AS. Diffuse dermal angiomatosis. J Cutan Pathol 2006;33:646–8. 66. Trent JT, Kirsner RS. Leg ulcers in sickle cell disease. Adv Skin Wound Care 2004;17:410–16. 67. Nakano J, Nakamura M, Ito T, et al. A case of antiphospholipid syndrome with cutaneous ulcer and intrauterine fetal growth retardation. J Dermatol 2003;30:533–7. 68. Schwartzfarb EM, Romanelli P. Hyperhomocysteinemia and lower extremity wounds. Int J Low Extrem Wounds 2008;7:126–36. 69. Darvall KA, Sam RC, Adam DJ, et al. Higher prevalence of thrombophilia in patients with varicose veins and venous ulcers than controls. J Vasc Surg 2009;49:1235–41. 70. Hafner J, Kuhne A, Schar B, et al. Factor V Leiden mutation in postthrombotic and non-postthrombotic venous ulcers. Arch Dermatol 2001;137:599–603. 71. Musani MH, Musani MA, Verardi MA. Venous gangrene a rare but dreadful complication of deep venous thrombosis. Clin Appl Thromb Hemost 2011;17:E1–3. 72. Lupi O, Madkan V, Tyring SK. Tropical dermatology: bacterial tropical diseases. J Am Acad Dermatol 2006;54:559–78. 73. Zeegelaar JE, Faber WR. Imported tropical infectious ulcers in travelers. Am J Clin Dermatol 2008;9:219–32.

eFig. 105.1 Venous ulcer of the medial malleolus. This is a common site for this type of ulcer. Induration due to lipodermatosclerosis, hemosiderin deposition, and atrophie blanche scars were present in the surrounding skin. Courtesy,

eFig. 105.3 Sacral decubitus ulcer. Courtesy,





Ronald P Rapini, MD.

CHAPTER

105 Ulcers

Online only content

Jean L Bolognia, MD.

eFig. 105.2 Mal perforans. Neuropathic ulcerations at pressure points on the plantar surface of the great toes in a patient with diabetic neuropathy. Note the thick rim of callus.  

eFig. 105.4 Elephantiasis nostras verrucosa. Multiple fibrotic papules and nodules. Courtesy, Jean L Bolognia, MD.  

1846.e1

VASCULAR DISORDERS SECTION 17

Other Vascular Disorders Robert Kelly and Christopher Baker

Chapter Contents Livedo reticularis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1847 Flushing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1850 Erythromelalgia . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1851 Telangiectasias . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1853 Venous lakes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1856 Nevus anemicus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1856 Angiospastic macules (Bier spots) . . . . . . . . . . . . . . . . . . . 1856

INTRODUCTION This chapter will cover several disorders of the skin vasculature, including livedo reticularis, flushing and erythromelalgia, as well as vascular ectasias such as telangiectasias and venous lakes. Some of the diseases described here are important skin signs of systemic disease, while others are incidental findings. Additional disorders of blood vessels are covered elsewhere, e.g. infantile hemangiomas (Ch. 103), vascular malformations (Ch. 104), and vascular neoplasms and proliferations (Ch. 114).

LIVEDO RETICULARIS

106 

Pathogenesis LR results from alterations in blood flow through the cutaneous microvasculature system (Fig. 106.1). The latter consists of arterioles that are oriented perpendicularly to the skin surface. The vessels then divide into capillary beds that in turn drain into a subpapillary plexus. It has been proposed that this arrangement of vessels gives rise to a series of 1–3 cm cones with the ascending arteriole at the apex of each cone. At the edge of the cone, the venous plexus is more prominent and the arterial bed is diminished. Any process that either reduces blood flow to and through the skin or reduces drainage of blood out of the skin will result in the accumulation of deoxygenated blood in the venous plexus, leading to the clinical appearance of LR1–3. There are a number of causes of LR (Table 106.1), and the clinical pattern of LR can vary with the nature of the underlying cause. A complete fine network is indicative of alterations in blood flow caused by vasospasm or by factors within the blood that alter the viscosity and the flow through the vessels. Vessel wall pathology and intraluminal obstruction are more likely to result in a patchy distribution of LR, depending on the distribution of the underlying pathology. Livedo racemosa refers to a form of LR that has a larger, branching, and more irregular pattern and is often more widespread, affecting both the extremities and the trunk (Figs 106.2 & 106.3). It is generally indicative of several vaso-occlusive disorders including Sneddon syndrome4, the antiphospholipid antibody syndrome (APS)5, and lymphocytic thrombophilic arteritis6.

Clinical Features Congenital livedo reticularis

Key features ■ A common physiologic finding consisting of a mottled, reticulated vascular pattern ■ May occur secondarily due to an underlying disease, e.g. autoimmune connective tissue disease, antiphospholipid antibody syndrome ■ The pattern varies depending on the underlying cause ■ Appropriate investigations depend on the clinical context and associated findings

Cutis marmorata telangiectatica congenita

Cutis marmorata telangiectatica congenita (CMTC) is characterized by a persistent reticulated vascular pattern that is often limited to one extremity (see Ch. 104), but can be more widespread. Lesions are usually noted at birth, and, when the trunk is involved, there may be a sharp cut-off at the midline. Associated anomalies include other vascular malformations, limb asymmetry, and occasionally neurologic or ocular abnormalities7,8. Cutaneous vascular changes can improve during the first few years of life, with 20% of patients showing complete resolution.

Acquired livedo reticularis Livedo reticularis without systemic associations

Introduction Livedo reticularis (LR) is an extremely common finding and usually results from a physiologic vasospastic response to cold exposure. Among normal healthy individuals, the predisposition to LR will vary. However, it can also be a reflection of a number of underlying systemic diseases. LR resulting from any cause can vary to some degree with changes in external temperature. Physiologic LR will usually disappear with warming and reappear with cooling whereas other variants may persist to varying degrees with warming.

History The term “livedo reticularis” was first used by Hebra over a century ago to describe a violaceous skin discoloration caused by an abnormality of the cutaneous circulation. Renault (1883) and later Unna (1896) and Spalteholz (1927) suggested that a cone arrangement of the cutaneous microvasculature served as an explanation for the occurrence and pattern of LR1.

Physiologic livedo reticularis/cutis marmorata

These terms are synonymous and refer to a normal pattern of LR that occurs in response to cold (Fig. 106.4A). It is often more marked in neonates, infants, and young children2,3. In adults, it may be associated with a tendency towards acrocyanosis and chilblains.

Primary/idiopathic livedo reticularis

This refers to a persistent fine network of LR that is often widespread, particularly on the lower extremities. While there is some fluctuation with temperature, the LR will usually persist with warming. It is due to persistent vasospasm of arterioles and is not secondary to any underlying cause. However, primary LR is a diagnosis of exclusion and it is important to consider secondary causes (see Table 106.1). This is especially true when the LR is extensive2,3.

Livedo reticularis secondary to systemic disease Livedo reticularis due to vasospasm

Vasospasm is the most common cause of LR, including that seen in association with autoimmune connective tissue diseases (CTD;

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This chapter focuses on disorders characterized by dysfunction of skin vasculature, including livedo reticularis, flushing, erythromelalgia, and nevus anemicus. In addition, vascular ectasias such as telangiectasias and venous lakes are discussed. The significance of these cutaneous vascular diseases can vary, from being an important sign of a systemic disease to simply a cosmetic concern. Distinguishing physiologic changes of the skin vasculature from pathologic disease is sometimes challenging, and it is the dermatologist who often makes this distinction.

livedo reticularis, livedo racemosa, vasculitis, vasculopathy, erythromelalgia, flushing, telangiectasia, venous lake, nevus anemicus, angiospastic macules, Bier spots, spider telangiectasia, hereditary hemorrhagic telangiectasia, generalized essential telangiectasia, unilateral nevoid telangiectasia, angioma serpiginosum, cutaneous collagenous vasculopathy

CHAPTER

106 Other Vascular Disorders

ABSTRACT

non-print metadata KEYWORDS:

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SECTION

CAUSES OF LIVEDO RETICULARIS

ANATOMICAL BASIS FOR THE DEVELOPMENT OF LIVEDO RETICULARIS

Congenital livedo reticularis

Vascular Disorders

17

Cutis marmorata telangiectatica congenita



Zone of venous predominance

Zone of arterial predominance

Acquired livedo reticularis Vasospasm Cutis marmorata/physiologic livedo reticularis Primary (idiopathic) livedo reticularis • Autoimmune connective tissue diseases (e.g. SLE) • Raynaud phenomenon/disease • •

Vessel wall pathology Vasculitis - Cutaneous polyarteritis nodosa - Systemic polyarteritis nodosa - Cryoglobulinemic vasculitis - Autoimmune connective tissue disease-associated vasculitis (e.g. rheumatoid arthritis, SLE, Sjögren syndrome) • Lymphocytic thrombophilic arteritis (may be variant of polyarteritis nodosa) • Calciphylaxis • Sneddon syndrome • Deficiency of adenosine deaminase 2 • Livedoid vasculopathy (also intraluminal obstruction) •

Venous drainage

Arterial cone

Fig. 106.1 Anatomical basis for the development of livedo reticularis. An elliptical biopsy from the paler central “hole” in the net pattern is necessary in order to sample the affected arterioles (dashed oval); serial sectioning may be required.  

Intraluminal pathology Increased normal blood components - Thrombocythemia - Polycythemia vera • Abnormal proteins - Cryoglobulinemia - Cryofibrinogenemia - Cold agglutinins - Paraproteinemia • Hypercoagulability (see Table 105.9) - Antiphospholipid syndrome - Protein S and C deficiencies - Antithrombin III deficiency - Factor V Leiden mutation - Homocystinuria, hyperhomocysteinemia - Disseminated intravascular coagulation • Thrombotic thrombocytopenic purpura • Embolic - Cholesterol emboli - Septic emboli - Atrial myxoma - Nitrogen (decompression sickness) - Carbon dioxide arteriography • Hyperoxaluria • Intralymphatic histiocytosis •

PATTERN OF LIVEDO RETICULARIS VERSUS LIVEDO RACEMOSA

A Livedo reticularis

B Livedo racemosa

Fig. 106.2 Pattern of livedo reticularis (A) versus livedo racemosa (B).  

Fig. 106.3 Livedo racemosa in a patient with lymphocytic thrombophilic arteritis. A more irregular, broken, and branching pattern is seen, as compared to livedo  

Other Medications (e.g. amantadine, norepinephrine, interferon) Infections (e.g. hepatitis C [vasculitis], Mycoplasma spp. [cold agglutinins], syphilis) • Neoplasms (e.g. pheochromocytoma) • Neurologic disorders (e.g. complex regional pain syndrome [reflex sympathetic dystrophy], paralysis) • Moyamoya disease • •

Table 106.1 Causes of livedo reticularis. SLE, systemic lupus erythematosus.  

Fig. 106.4B). Reflecting a vasospastic tendency, it occurs more commonly in patients with Raynaud phenomenon.

Livedo reticularis due to vessel wall pathology

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Vasculitis involving the medium-sized arterioles at the dermal– subcutaneous junction or in the deep dermis is the most common cause of vessel wall pathology associated with LR. Involvement of mediumsized arterioles is characteristic of cutaneous polyarteritis nodosa (PAN)9, but can also be seen with systemic PAN and ANCA-associated vasculitides (see Ch. 24). Patients with lymphocytic thrombophilic arteritis, in which the peri-arteriolar inflammation is lymphocytic rather than neutrophilic, characteristically develop livedo racemosa (see

CHAPTER

Other Vascular Disorders

106

$

Fig. 106.5 Calciphylaxis in a patient with end-stage chronic renal disease. There is retiform purpura and a large black eschar overlying cutaneous necrosis. Note the violaceous reticulated pattern on the inner thighs. Because the patient was also receiving warfarin, the differential diagnosis included warfarin necrosis. Courtesy, Alicia Little, MD.  

%

Fig. 106.4 Livedo reticularis. A An even, net-like pattern is seen on the thigh in physiologic livedo reticularis. B Livedo reticularis in a patient with systemic lupus erythematosus. B, Courtesy, Jeffrey P Callen, MD.  

Fig. 106.3)6,10. Whether this disorder represents a distinct entity or a variant of cutaneous PAN is a matter of debate. LR can also be seen in patients with livedoid vasculopathy (see Ch. 23)11. Deficiency of adenosine deaminase 2 (DADA2) is an autosomal recessive autoinflammatory disorder (see Ch. 45). It has features of both Sneddon syndrome and polyarteritis nodosa, i.e. patients can have both a vasculopathy and vasculitis. Characteristic features include intermittent fevers, early-onset lacunar strokes, hepatosplenomegaly, hypogammaglobulinemia and lymphopenia, as well as cutaneous nodules and livedo racemosa (see Fig. 45.11)12,13. Calciphylaxis consists of calcium deposition in the walls of blood vessels (see Ch. 50). It is most commonly seen in the setting of endstage chronic kidney disease complicated by secondary hyperparathyroidism. Calciphylaxis may initially commence with LR that then becomes purpuric and subsequently necrotic (Fig. 106.5). Sneddon syndrome is rare and is characterized by widespread livedo racemosa in conjunction with multiple cerebral ischemic episodes leading to progressive neurologic impairment4,5 (see Ch. 23). It remains uncertain as to whether the vascular pattern results from vasculopathy, vasculitis or coagulopathy (as some patients have antiphospholipid antibodies while others have DADA2), but characteristic changes are seen within affected vessels.

Livedo reticularis due to intraluminal pathology

LR can result either from factors (e.g. within the blood) that slow intravascular blood flow or from complete obstruction of the vessel lumen.

Altered blood flow due to an increase in blood viscosity may be secondary to abnormal circulating proteins (e.g. cryoglobulins14, cryofibrinogens, cold agglutinins, paraproteins) or an increase in normal blood components (e.g. polycythemia vera15, thrombocytosis). A fine, evenly distributed pattern of LR is usually seen. Hypercoagulable states can also be associated with LR, including the APS16 and protein C17, protein S, or antithrombin III deficiencies18. LR of the lower extremities is often seen in patients with neurologic conditions that lead to immobility of the lower limbs and stasis. Complete obstruction of the vessel lumen can result from either emboli (e.g. cholesterol emboli derived from atheromata19) or thromboses within vessels (e.g. APS, heparin or warfarin necrosis). Intracellular crystal deposition is seen in hyperoxaluria and this also gives rise to luminal obstruction and LR20. A patchy, discontinuous-pattern LR is seen with intraluminal obstruction and it may subsequently become purpuric with areas of infarction and necrosis.

Other causes of livedo reticularis

There are numerous causes of LR cited in the literature, and, in most, one of the above mechanisms can generally be implicated. The other causes include drugs such as amantadine21 and norepinephrine (noradrenaline), as well as infections. The latter can lead to: the production of cryoglobulins, cold agglutinins or antiphospholipid antibodies; the induction of immune vasculitis; or septic vasculitis or septic emboli. Neoplasms may also be associated with LR via hypercoagulability or paraproteinemia as well as vasospasm (e.g. pheochromocytoma). Lastly, LR may be seen in several neurologic conditions (e.g. reflex sympathetic dystrophy) as a result of vasospasm or vasodilation (this is in addition to stasis arising from immobility).

Differential Diagnosis Erythema ab igne is a heat-induced skin disease that begins as a reversible LR, then with continued heat exposure, it evolves into a fixed reticulated hyperpigmentation in the same pattern. When present on the anterior thighs, the possibility of direct contact with a laptop computer should be considered. Various cutaneous eruptions may have a reticulated pattern and might be confused with LR, including reticulated erythematous mucinosis (favors mid central trunk) and some viral exanthems (e.g. erythema infectiosum). Poikilodermatous conditions may also have a reticulate pattern (e.g. dermatomyositis, mycosis fungoides); however, the presence of epidermal changes and telangiectasias will help distinguish these conditions from LR.

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SECTION

Vascular Disorders

17

Pathology

Pathogenesis

The histology of LR varies depending on the underlying cause. In idiopathic or physiologic forms resulting from vasospasm, no abnormality will be evident. With secondary causes of LR, a number of abnormalities may be seen, including vasculitis, calcium deposition within vessel walls (calciphylaxis; see Fig. 50.6), intravascular eosinophilic plugging (monoclonal cryoglobulinemia; see Fig. 23.4), intraluminal thromboses (hypercoagulable states), cholesterol clefting (cholesterol emboli; see Fig. 23.5), and crystal deposition (oxalosis). In Sneddon syndrome, vessel walls demonstrate endothelial inflammation and subendothelial myointimal hyperplasia with partial or complete occlusion of affected arterioles; however, in order to find these histopathologic changes, it is necessary to sample the affected arterioles. An elliptical biopsy from the paler central “hole” in the net pattern is necessary and serial sectioning may be required (see Fig. 106.1).

An increase in cutaneous blood flow occurs with relaxation of vascular smooth muscle. This may occur via the autonomic nervous system23 (usually leading to active vasodilation), endogenous vasoactive agents (such as histamine and serotonin), or exogenous agents (Table 106.3). Alcohol-induced flushing may result from the direct effect of alcohol as well as cutaneous vasodilation from elevated blood levels of acetaldehyde; the latter occurs in those with alcohol dehydrogenase deficiency (prevalent in Asians) and in the “disulfiram reaction” induced by some medications. Flushing from fermented alcoholic drinks may be caused by vasoactive substances such as tyramine. Vasodilation mediated by the autonomic nervous system is often accompanied by eccrine sweating due to a direct effect on both sweat glands and blood vessels (wet flush)24. Direct vasodilation by vasoactive agents is usually not associated with increased sweating (dry flush).

Treatment

Clinical Features

LR is a clinical sign and does not require treatment per se. It is unresponsive to treatments such as vascular laser therapy or vasodilatory medications. Underlying causes require identification and appropriate treatment.

Blushing is a common emotionally triggered form of flushing associated with embarrassment and anxiety and is considered an exaggerated physiologic response. Physiologic flushing also occurs as part of normal thermoregulation in response to heat or exercise. “Hot flashes” refer to flushing associated with menopause, which lasts for a few minutes and is usually associated with sweating25. Flushing of any cause may be exacerbated or triggered by a number of common factors such as heat, hot drinks, exercise, anxiety, food additives (e.g. sulfites), and alcohol. Affected patients often report a feeling of heat and burning of the skin during episodes and find the color change a social hindrance. Some patients become anxious that they will flush at inopportune times and this further exacerbates the problem. Repeated flushing may result in permanent “fixed” erythema and telangiectasias. Carcinoid tumors that secrete vasoactive agents (e.g. serotonin) are associated with the carcinoid syndrome (Table 106.4). This syndrome includes flushing, which is often severe26, and it may be precipitated by common triggers of flushing. The classic “carcinoid flush” occurs with ~10% of midgut tumors (small intestine, appendix, proximal colon), but only when there are associated liver metastases; it lasts minutes and consists of erythema and pallor as well as a cyanotic hue. Type III gastric carcinoid tumors are associated with a pruritic, patchy, bright red flush admixed with white patches and probably mediated by histamine. Bronchial tumors are associated with a prolonged (hours to days), intensely red to purple flush. Hindgut tumors (distal colon, rectum) are rarely, if ever, associated with the carcinoid syndrome and flushing, even with liver metastases.

FLUSHING Key features ■ Flushing is a physiologic response, but in an exaggerated form causes clinical symptoms ■ Common triggers (e.g. heat, emotion, exercise, some foods) will exacerbate flushing of any cause ■ Causes of excessive flushing include exogenous medications, menopause, neurologic disorders, and systemic diseases (e.g. carcinoid syndrome)

Introduction Flushing is the term used to describe transient and episodic reddening of the skin, most commonly of the face, and less often the neck, ears and upper chest. It is the visible sign of a generalized increase in cutaneous blood flow. The greater visibility and capacitance of the superficial cutaneous vasculature of the face and adjacent areas accounts for the limited distribution22. In the evaluation of an affected patient, there are a number of causes to consider, including underlying systemic disorders (Table 106.2).

EXOGENOUS AGENTS THAT CAN CAUSE FLUSHING CAUSES OF FLUSHING Physiologic Exogenous agents (see Table 106.3) • Menopause • Neurologic disorders - Anxiety - Autonomic dysfunction - Tumors (e.g. hypogonadal pituitary tumors) - Migraine - Frey syndrome (auriculotemporal syndrome) • Systemic diseases - Carcinoid syndrome - Mastocytosis - Pheochromocytoma - Medullary carcinoma of the thyroid - Thyrotoxicosis - POEMS syndrome - Pancreatic tumors (e.g. VIPomas) - Prostaglandin-secreting renal cell carcinoma • •

Table 106.2 Causes of flushing. Rosacea may be associated with pronounced flushing, but usually fixed erythema, papulopustules, edema, and/or telangiectasia are present to some degree. POEMS, polyneuropathy, organomegaly, endocrinopathy, M-protein (monoclonal gammopathy), skin changes; VIP, vasoactive intestinal polypeptide.  

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Alcohol Drugs - Angiotensin-converting enzyme (ACE) inhibitors - Calcium channel blockers - Calcitonin - Chlorpropamide* - Cholinergic agonists (e.g. pilocarpine) - Cyclosporine - Disulfiram* - Fumaric acid esters - Gold (“nitritoid reactions”) - Hydralazine - Nicotinic acid - Nitrates (e.g. glyceryl trinitrate) - Opiates - Prostaglandins - Sildenafil, tadalafil, vardenafil - Tamoxifen • Foods - Spoiled scombroid fish • Food additives - Monosodium glutamate (MSG), sodium nitrite, sulfites • •

*With alcohol intake. Table 106.3 Exogenous agents that can cause flushing.  

Cutaneous - Flushing - Vascular rosacea-like changes - Pellagra - Edema and induration of the face > extremities • Bronchospasm • Diarrhea • Cardiac dysfunction (right-sided) • Hypotension • Peptic ulcers •

ERYTHROMELALGIA

CHAPTER

106 Other Vascular Disorders

SIGNS AND SYMPTOMS OF THE CARCINOID SYNDROME

dine may be effective in idiopathic flushing. Anxiolytics may be helpful, particularly if emotional symptoms or anxiety are evident. Menopausal flushing may respond to hormone replacement therapy, clonidine, or selective serotonin reuptake inhibitors (SSRIs). In troublesome cases unresponsive to these measures, transthoracic endoscopic sympathectomy may be considered.

Synonyms:  ■ Erythermalgia ■ Erythralgia

Table 106.4 Signs and symptoms of the carcinoid syndrome.  

Key features ■ Characterized by painful burning and erythema of the distal extremities (lower > upper) ■ Precipitated by heat and relieved by cooling ■ May be idiopathic, familial, or arise secondarily due to an underlying condition (e.g. thrombocythemia)

CLINICAL APPROACH TO THE EVALUATION OF FLUSHING 1. Identify provocative factors • Direct questioning • Patient diary (food, medications, activities) 2. Check for associated symptoms • Sweating • Urticaria • Diarrhea • Bronchospasm 3. Investigation (not required in all cases) Indicated if flushing: • Of sudden or recent onset • Severe • Associated with systemic symptoms Investigations to consider: • Complete blood count with differential and platelets • Thyroid function tests • Serum estrogen, FSH, LH • Serum tryptase [M]; serum chromogranin A levels [C]; plasma free metanephrines [P] • 24-hour urine collection for: - Serotonin metabolites such as 5-hydroxyindole acetic acid (5-HIAA) [C] - Fractionated metanephrines (more specific but less sensitive than plasma) [P] - Histamine metabolites such as methylimidazole acetic acid (MeImAA) [M] • CT/MRI scans; octreotide/somatostatin receptor scintigraphy (using radiolabeled octreotide) 4. Elimination • Exclude suspected drugs and food additives

Table 106.5 Clinical approach to the evaluation of flushing. C, carcinoid; FSH, follicle stimulating hormone; LH, luteinizing hormone; M, mastocytosis; P, pheochromocytoma.  

An approach to the clinical assessment of flushing and relevant investigations are listed in Table 106.5.

Differential Diagnosis Fixed erythema, and sometimes telangiectasia, of the face and neck are seen in fair-skinned individuals with photodamage as well as patients with seborrheic dermatitis and photosensitive autoimmune CTD (e.g. dermatomyositis). Affected individuals may complain of the persistent redness and burning of the skin rather than actual flushing. Rosacea may be associated with pronounced flushing, but usually fixed erythema, papulopustules, edema, and/or telangiectasia are present to some degree.

Treatment The clinician should consider and eliminate any suspected exogenous cause (see Table 106.3). Underlying systemic causes, although rare, should be considered (see Table 106.2). Triggers of flushing are likely to be clinically relevant in most patients and should be avoided where possible. Non-selective β-blockers (e.g. nadolol, propranolol) or cloni-

Introduction Erythromelalgia is an episodic condition characterized by a burning sensation, erythema, and increased skin temperature. It affects acral sites, particularly the lower extremities. Classically, there are three major forms, including: type 1 – associated with thrombocythemia type 2 – primary or idiopathic form type 3 – associated with underlying causes other than thrombocythemia.

• • •

History The term “erythromelalgia” was first coined by Mitchell in 1878. It was used to describe redness (erythros), involvement of extremities (melos), and pain (algos). The diagnostic criteria were established by Thompson27 in 1979: (1) burning pain in the extremities; (2) pain aggravated by warming; (3) pain relieved by cooling; (4) erythema of affected skin; and (5) increased temperature of affected skin.

Epidemiology In Norway, the estimated incidence of erythromelalgia is 0.25/100 000 with a prevalence of 2/100 00028. While types 1 and 3 usually appear during adulthood, type 2 may appear in childhood and may be familial. The female : male incidence varies from 2 : 1 to almost 3 : 1. In one study, the mean age of onset was 56 years (range, 5–91 years) with 4% having their symptoms begin during childhood.

Pathogenesis While the discovery of SCN9A mutations in patients with primary familial erythromelalgia has provided insights into this disorder, in general, the pathogenesis of erythromelalgia is not entirely understood. Firstly, it may vary depending on the underlying cause and between different patient subgroups. For example, in patients with thrombocythemia, the pathophysiology is likely to be related to both increased numbers of platelets as well as abnormalities in platelet function. Of note, one explanation for why type 1 erythromelalgia does not respond to heparin or warfarin is that the microthrombi that form do not require thrombin activation29. In other types of erythromelalgia, changes in vascular dynamics may be a factor. It has been proposed that hyperemia results from increased blood flow through arteriovenous shunts with a resultant reduction in blood flow within nutritional vessels, thus leading to cutaneous hypoxia28,30. Another proposed mechanism is vasoconstriction (as occurs in Raynaud phenomenon), but in erythromelalgia this is followed by a prolonged phase of hyperemia31. A temperature-triggered release of vasoactive substances and chemical pain mediators may also play a role.

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In 2004, gain-of-function missense mutations in SCN9A, which encodes the voltage-gated sodium channel alpha subunit Nav1.7, were first described in patients with primary familial erythromelalgia32. Nav1.7 produces threshold currents and is expressed primarily within dorsal root ganglia of sensory neurons (especially nociceptors) and sympathetic ganglion neurons. Mutations lead to lowered thresholds and “over-excitability” of pain-signaling sensory neurons33 while at the same time producing “under-excitability” of sympathetic neurons. Certain mutations that produce a lesser effect on sodium channel activation and subsequent neuron excitability are associated with a later onset of clinical signs and symptoms34. Another dominantly inherited pain syndrome, paroxysmal extreme pain disorder, has also been found to be due to gain-of-function mutations in SCN9A, whereas loss-of-function mutations in both copies of this gene lead to a recessively inherited insensitivity to pain35. Lastly, there exist additional families that are not linked to chromosome 2q31–32 (SCN9A locus), suggesting genetic heterogeneity36. Associations in secondary erythromelalgia include myelodysplastic syndromes, diabetes mellitus, peripheral arterial disease, vasculitis, systemic lupus erythematosus, and other autoimmune CTDs.

Clinical Features Erythromelalgia is characterized by burning, erythema, and warmth of acral sites (Fig. 106.6). Attacks most commonly occur late in the day, last through the night, and frequently impair sleep. The symptoms are usually episodic, although occasionally they may be continuous. The feet are involved in 90% of patients, whereas the hands are

affected in 25%. Less commonly, there is also involvement of the head and neck. Type 1 erythromelalgia may be unilateral and is more frequently associated with progression to ischemic necrosis. In contrast, the idiopathic type is more likely to be bilateral. The pain is precipitated by minor elevations in temperature (between 32°C and 36°C). Other exacerbating factors include exercise, standing, walking, fever, and limb dependency. Cooling and limb elevation generally reduce the symptoms. The affected areas will often appear red and swollen. Other findings include acrocyanosis, livedo reticularis, facial flushing, cutaneous necrosis, and ulceration. In up to 40% of patients, the limb may appear normal between attacks. Prolonged immersion in water can lead to extensive maceration and contribute to ulcer formation. Prognosis is variable. In one long-term study, approximately 30% of patients fell into each of three categories: worsening, no change, and improvement. A further 10% had complete resolution of their symptoms37.

Pathology In type 1 erythromelalgia, vessels may show intimal proliferation and occlusive thrombosis followed by complete fibrosis of the affected arterioles. In general, however, biopsies are not required and histology is nonspecific.

Differential Diagnosis Complex regional pain syndrome (CRPS; reflex sympathetic dystrophy) may sometimes have features similar to erythromelalgia (see Ch. 6). Abnormal warmth, erythema, and burning pain may be seen in both, but CRPS does not have the characteristic close relationship to temperature and tends to be constant rather than episodic. Peripheral neuropathy may also cause tingling and burning and may require differentiation by nerve conduction studies. Calcium channel blockers, autonomic dysfunction, acrodynia and mushroom poisoning, as well as occlusive vascular diseases such as thromboangiitis obliterans, may be associated with erythromelalgia-like symptoms. It is important to consider underlying causes of erythromelalgia – in particular, chronic myeloproliferative disorders – as erythromelalgia may be the first sign of the latter.

Treatment

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Fig. 106.6 Erythromelalgia. Red hot painful hand (A) and feet (B) in two patients with erythromelalgia. A, Courtesy,  

Agustin Aloma, MD.

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Although numerous treatments have been reported as possible therapies for erythromelalgia, no single therapy is consistently effective and many cases can prove difficult to control. The assistance of a specialist pain clinic can be valuable. Various methods of cooling the limbs during attacks, such as fans, wet dressings, and ice packs wrapped in towels, should be explored and have often already been tried by the time of presentation. Frequent periods of leg elevation can be helpful in reducing both discomfort and leg edema, whereas prolonged periods of leg dependency should be avoided. Simple oral analgesia is also important. Aspirin can be effective for type 1 erythromelalgia and treatment for the thrombocythemia with medications such as hydroxyurea should also be considered. Topical therapies include 10% capsaicin cream, 1% amitriptyline/0.5% ketamine gel, and lidocaine patches, while possible oral medications include SSRIs (e.g. venlafaxine), tricyclic antidepressants (e.g. amitriptyline), anticonvulsants (e.g. gabapentin, carbamazepine), calcium channel blockers (e.g. diltiazem), the prostaglandin analogue misoprostol, and especially in primary inherited erythromelalgia, sodium channel blocking agents (e.g. mexiletine, flecainide)38,39. With the report of functional expression studies (based upon a specific mutation) correlating with clinical responsiveness to carbamazepine or mexiletine, the possibility exists of utilizing such assays in the future to guide therapy. In addition, there are ongoing trials of Nav1.7 channel blockers, both oral and topical. Several intravenous therapies have been used for more severe cases, including nitroprusside, prostaglandin E1, and lidocaine (combined with oral mexiletine). More invasive approaches include epidural infusions of bupivacaine and opiates, lumbar sympathetic blocks, and bilateral lumbar sympathectomies40. Oral medications should be tried initially, but more invasive procedures may be necessary for more severe cases.

CHAPTER

Primary Spider telangiectasias (also associated with estrogen excess) Hereditary benign telangiectasia (Fig. 106.8)* • Costal fringe • Angioma serpiginosum • Unilateral nevoid telangiectasia • Generalized essential telangiectasia • Cutaneous collagenous vasculopathy • •

Secondary to physical changes or damage

106 Other Vascular Disorders

CAUSES OF TELANGIECTASIAS

Photodamage Post radiation therapy • Traumatic • Venous hypertension • •

Skin disease Telangiectatic rosacea Incipient or involuted infantile hemangiomas • Basal cell carcinoma •

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Hormonal/metabolic Estrogen-related - Liver disease - Pregnancy - Exogenous estrogens • Corticosteroids •

Systemic conditions Carcinoid syndrome Mastocytosis (telangiectasia macularis eruptiva perstans) • Autoimmune connective tissue diseases - Lupus erythematosus - Dermatomyositis - CREST syndrome/systemic sclerosis • Mycosis fungoides, including poikilodermatous • B-cell lymphomas • Angiolupoid sarcoidosis • GVHD (in the context of poikiloderma) • HIV infection (anterior chest) • •

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Congenital malformations and genodermatoses

Fig. 106.7 Telangiectasias. A Sun-induced telangiectasias on the cheek. B Prominent telangiectasias on the breast following radiation therapy.  

TELANGIECTASIAS Key features ■ Telangiectasia is due to persistently dilated dermal vessels and not angiogenesis ■ Can occur as a primary process, a result of cutaneous damage, or secondary to systemic disease

Introduction Telangiectasia refers to abnormal, small, persistently dilated blood vessels visible in the skin (Fig. 106.7). Individual vessels can be discerned and range in color from light red to deep purple and will usually empty with pressure. They occur as a result of vascular dilation rather than new vessel growth and are thought to arise from capillaries, venules or small arteriovenous malformations. Telangiectasias are seen in a range of clinical settings (Table 106.6). Treatment is often not required; however, options include cosmetic camouflage, light or fine wire diathermy, injection sclerotherapy, and laser or intense pulsed light therapies.

Spider Telangiectasia Synonyms:  ■ Nevus araneus ■ Spider nevus ■ Spider angioma

Cutis marmorata telangiectatica congenita Klippel–Trenaunay syndrome • Hereditary hemorrhagic telangiectasia • Ataxia–telangiectasia • Hypotrichosis–lymphedema–telangiectasia syndrome • Rombo syndrome • Bloom syndrome • Rothmund–Thomson syndrome • Poikiloderma with neutropenia • Dyskeratosis congenita • Xeroderma pigmentosum • Goltz syndrome (in lines of Blaschko) • GM1-gangliosidosis (also associated with angiokeratoma corporis diffusum) • Prolidase deficiency • •

*Childhood onset of multiple punctate, linear or arborizing telangiectasias favoring

sun-exposed areas of the face and upper extremities; the vermilion lips and palate are occasionally affected, but there is no visceral involvement.

Table 106.6 Causes of telangiectasias. GVHD, graft-versus-host disease.  

This localized lesion has a slightly raised central red papule (which often becomes more prominent with time) and multiple small, radiating, dilated vessels (“legs”)41 (Fig. 106.9). The lesion can vary from several millimeters to more than a centimeter in diameter. They are commonly located on the face, neck, upper trunk, and hands. Spider telangiectasias represent a form of telangiectasia with a central feeding arterial vessel. They are usually seen in otherwise healthy individuals, especially women and children. Lesions, often multiple, commonly occur with pregnancy, liver disease, and oral contraceptive pills (OCPs). Spontaneous resolution may occur, especially after pregnancy. Treatment options include electrosurgery or vascular lasers.

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Fig. 106.10 Generalized essential telangiectasia. The site of initial involvement is usually the distal lower extremities. Sheets of asymptomatic blanchable telangiectasias appear bilaterally and over time can become widespread. Courtesy, Jean L Bolognia, MD.  

Fig. 106.8 Hereditary benign telangiectasia. Fine linear and branching telangiestasias are seen on the cheeks bilaterally in this five-year-old boy. There is no associated visceral involvement. Courtesy, Julie V Schaffer, MD.  

Fig. 106.9 Spider telangiectasia. They are characterized by a central arteriole with radiating telangiectatic “legs”. A Single lesion on the nose of a young child. B Multiple lesions on the shoulder of an adult with liver disease.    

A, Courtesy, Julie V Schaffer, MD; B, Courtesy, Jeffrey P Callen, MD.

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The differential diagnosis includes cutaneous collagenous vasculopathy; typically it is not confused with telangiectasia macularis eruptiva perstans. While improvement with vascular lasers is possible, the progressive nature must be considered and the cost of treating extensive involvement may prove prohibitive.

Cutaneous Collagenous Vasculopathy Cutaneous collagenous vasculopathy (CCV) was first described in 200044. Clinically, it can resemble generalized essential telangiectasia (GET). However, based upon the limited number of reported cases, there is not a female predominance, the telangiectasias may involve just the trunk and/or proximal extremities, and history of an “upward march” of lesions is lacking (Fig. 106.11A)45. The etiology is unknown and there is no clear association with any underlying systemic illness or medication. CCV does have unique histologic findings consisting of ectatic superficial blood vessels with hyalinized and laminated, concentric concretions surrounding the basement membrane of affected vessels. With special staining, this material is PAS-positive and diastase-resistant, and by immunohistochemistry, it reacts with antibodies against collagen type IV (Fig. 106.11B). Ultrastructurally, the deposits have been shown to consist of collagen with abnormal banding patterns (Luse bodies)45. This condition, like GET, is benign in nature. There are scattered case reports of improvement following pulsed dye laser therapy.

Unilateral Nevoid Telangiectasia

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Telangiectasias in this condition are usually confined to the trigeminal or upper cervical dermatomes (Fig. 106.12) and may follow the lines of Blaschko46,47. Congenital and acquired forms are recognized. It has been proposed that an increase in estrogen receptors on blood vessels in affected areas and/or an increase in estrogen levels is causative. Situations of relative estrogen excess such as pregnancy, puberty, and liver disease are associated with the acquired form.

Angioma Serpiginosum Generalized Essential Telangiectasia

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This is a primary disorder that typically affects adult women but may commence during childhood. Initially, the limbs are affected, especially the distal lower extremities, with sheets of asymptomatic blanchable telangiectasias (Fig. 106.10)42,43. The involvement is usually symmetric. Over time, there is often a progression proximally such that the telangiectasias become more widespread. Although the telangiectasias are persistent, patients do not have associated systemic illnesses.

Angioma serpiginosum is a rare vascular disorder with a characteristic appearance48,49. It is usually sporadic, but familial cases have been reported. Typically, the condition affects female patients and commences during the first two decades of life. Multiple, small, asymptomatic, non-palpable, deep-red to purple puncta occur in small clusters and sheets (Fig. 106.13). The arrangement and extension of the lesions may produce a serpiginous pattern. The extremities are most commonly affected, initially with a unilateral distribution; over months to years, the involvement may become more widespread. The palms, soles, and mucous membranes are not involved.

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106

Fig. 106.11 Cutaneous collagenous vasculopathy – clinical and histologic features. A Multiple violaceous branching telangiectasias on the forearm; the patient also had involvement of the thighs, abdomen and back. B In the upper dermis, there are some extravasated red blood cells and clumped RBCs within an ectatic blood vessel. Note the concentric hyaline deposits at the periphery of the affected blood vessel. Immunohistochemical staining with antibodies to collagen type IV highlight the deposits (inset). B, Courtesy,

Other Vascular Disorders



Lorenzo Cerrroni, MD.

Fig. 106.13 Angioma serpiginosum. Grouped dark red puncta on the arm in a serpiginous pattern.  

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Fig. 106.14 Hereditary hemorrhagic telangiectasia. The tongue and lips are a common location for the mat-like and papular telangiectasias that actually represent small arteriovenous  

extravasated erythrocytes. Treatment is not necessary, but lesions can be improved with the pulsed dye laser.

Hereditary Hemorrhagic Telangiectasia Synonym:  ■ Osler–Weber–Rendu disease

Fig. 106.12 Unilateral nevoid telangiectasia. Note the segmental, unilateral distribution pattern of discrete telangiectasias. Courtesy, Robert Hartman, MD.  

The puncta represent dilated non-inflamed capillaries within the dermal papillae. These can be seen with dermoscopy. Incomplete blanching occurs with pressure, but lesions are not purpuric. The differential diagnosis includes pigmented purpuric eruptions, particularly the Majocchi variant (purpura annularis telangiectoides), which is more likely to be bilateral and on biopsy has perivascular lymphocytes and

Hereditary hemorrhagic telangiectasia (HHT) is an autosomal dominant condition in which there are multiple mucocutaneous and gastrointestinal telangiectasias (which are actually arteriovenous malformations) as well as variable visceral involvement (lung, liver and CNS). The diagnosis may first be suspected in children who have repeated episodes of epistaxis; however, the initial presentation can occur during the second or third decades of life. The characteristic matlike and papular telangiectasias on the mucous membranes are first seen during adolescence50. Cutaneous lesions usually appear after puberty or even later in life. Lesions, which increase in size and number as the patient ages, are most commonly seen on the face, tongue, lips, nasal mucosa, hands and fingertips (Fig. 106.14). They frequently occur throughout the gastrointestinal tract and may result in obvious hemorrhage or iron

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deficiency anemia. Hemorrhage from vascular lesions in the lung, liver, CNS, spleen and urinary tract may occur, as well as paradoxical emboli due to pulmonary arteriovenous malformations. HHT can result from mutations in several genes, most commonly HHT1 and HHT2 which encode endoglin and ALK-1, respectively (see Table 104.2). Both of these glycoproteins are TGF-β receptors expressed by vascular endothelium, and they are thought to play a role in angiogenesis and vessel wall integrity. Treatment of the mucocutaneous vascular lesions may not be required. Destructive treatments such as diathermy, cautery or laser may be used to treat individual lesions. Surgical management or embolization may be required for uncontrolled hemorrhage from mucosal lesions or complications arising from visceral lesions. Initial and longitudinal evaluation of patients with HHT is outlined in Table 104.6.

Ataxia–Telangiectasia Synonym:  ■ Louis-Bar syndrome

catecholamines and are permanently vasoconstricted54. The border and extent of the lesion become imperceptible with pressure (or diascopy) sufficient to cause blanching of surrounding skin. Conversely, application of heat or an ice cube will often accentuate the lesion; the border becomes hyperemic during warming, while the lesion stays pale. The pale appearance of the lesion (rather than an absence of pigmentation) and the results of the above clinical maneuvers allow nevus anemicus to be differentiated from vitiligo and nevus depigmentosus, respectively. Interestingly, islands of sparing may be present within the lesion, and skin transplanted within the nevus anemicus retains the characteristics of the donor site (donor dominance). No histologic abnormalities have been reported. No treatment is required or effective.

ANGIOSPASTIC MACULES (BIER SPOTS) These were first described by Bier in 1898 and represent a pattern of vascular mottling consisting of white macular areas surrounded by a red to occasionally blue cyanotic background. Bier spots most commonly occur on the arms and legs of young adults (Fig. 106.17), but

Ataxia–telangiectasia was first described by Louis-Bar in 1941. It is an autosomal recessive disorder characterized by cerebellar ataxia, chromosomal instability (frequent translocations between chromosomes 7 and 14), growth retardation, oculocutaneous telangiectasias, pulmonary infections (including bronchiectasis), immunodeficiency, and the development of lymphomas51. It is covered in more detail in Chapter 60. Linear telangiectasias first appear on the bulbar conjunctivae between 4 and 6 years of age. Cutaneous telangiectasias favor the head and neck region, and they are most common on the malar prominences, ears and eyelids in addition to the popliteal and antecubital fossae. Patients may have poikiloderma (hypopigmentation, hyperpigmentation, atrophy, telangiectasia), premature hair graying, and decreased subcutaneous fat.

VENOUS LAKES Venous lakes are small, dark-blue, slightly elevated, soft lesions that are predominantly localized on the lips (Fig. 106.15), ears or face of older adults. They can usually be emptied of most of their blood content by persistent pressure52,53. Pathologically, venous lakes represent telangiectasias in the dermis. Either one great, dilated venule or several communicating dilated spaces that contain erythrocytes are seen. Thrombosis is sometimes present. Optional treatment with electrosurgery or a hemoglobin-targeting laser is usually effective.

Fig. 106.16 Nevus anemicus. Pale area of vasoconstriction with irregular borders on the back.  

NEVUS ANEMICUS Nevus anemicus is a congenital pale area of skin, most commonly found on the upper to mid trunk. These patches have an irregular border and an average diameter of 5–10 cm (Fig. 106.16). Within the body of the lesion, local blood vessels are very sensitive to endogenous

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Fig. 106.15 Venous lake on the lip. The lesion is soft and, with compression, can be emptied of most of its blood content. Courtesy, Ronald P Rapini, MD.  

Fig. 106.17 Angiospastic macules (Bier spots). Multiple pale spots with an erythematous background on the forearm.  

(diascopy). The vascular pattern is thought to result from a benign physiological response consisting of vasoconstriction. Bier spots have also been associated with pregnancy and cryoglobulinemia. For additional online figures visit www.expertconsult.com

REFERENCES 1. Fleischer AB Jr, Resnick SD. Livedo reticularis. Dermatol Clin 1990;8:347–54. 2. Gibbs MB, English JC, Zirwas MJ. Livedo reticularis: an update. J Am Acad Dermatol 2005;52:1009–19. 3. Dowd PM. Reactions to cold. In: Burns T, Breathnach S, Cox N, Griffiths C, editors. Textbook of Dermatology. 7th ed. Blackwell Science; 2004. p. 23.7–23.12. 4. Francés C, Piette JC. The mystery of Sneddon syndrome: relationship with antiphospholipid syndrome and systemic lupus erythematosus. J Autoimmun 2000;15:139–43. 5. Francés C, Papo T, Wechsler B, et al. Sneddon syndrome with or without antiphospholipid antibodies: a comparative study in 46 patients. Medicine (Baltimore) 1999;78:209–19. 6. Lee JS, Kossard S, McGrath MA. Lymphocytic thrombophilic arteritis: a newly described mediumsized vessel arteritis of the skin. Arch Dermatol 2008;144:1175–82. 7. Devillers AC, de Waard-van der Spek FB, Oranje AP. Cutis marmorata telangiectatica congenita: clinical features in 35 cases. Arch Dermatol 1999;135:34–8. 8. Gerritsen MJP, Steijlen PM, Brunner HG, Rieu P. Cutis marmorata telangiectatica congenita: report of 18 cases. Br J Dermatol 2000;142:366–9. 9. Bauzá A, España A, Idoate M. Cutaneous polyarteritis nodosa. Br J Dermatol 2002;146:694–9. 10. Shen S, Williams RA, Kelly RI. Neuropathy in a patient with lymphocytic thrombophilic arteritis. Australas J Dermatol 2013;54:e28–32. 11. Anavekar NS, Kelly R. Heterozygous prothrombin gene mutation associated with livedoid vasculopathy. Australas J Dermatol 2007;48:120–3. 12. Zhou Q1, Yang D, Ombrello AK, et al. Early-onset stroke and vasculopathy associated with mutations in ADA2. N Engl J Med 2014;370:911–20. 13. Navon Elkan P, Pierce SB, Segel R, et al. Mutant adenosine deaminase 2 in a polyarteritis nodosa vasculopathy. N Engl J Med 2014;370:921–31. 14. Speight EL, Lawrence CM. Reticulate purpura, cryoglobulinaemia and livedo reticularis. Br J Dermatol 1993;129:319–23. 15. Filo V, Brezová D, Hlavcák P, Filová A. Livedo reticularis as a presenting symptom of polycythemia vera. Clin Exp Dermatol 1999;24:428. 16. Gibson GE, Su WPD, Pittelkow MR. Antiphospholipid syndrome and the skin. J Am Acad Dermatol 1997;36:970–82. 17. Weir NU, Snowden JA, Greaves M, Davies-Jones GAB. Livedo reticularis associated with hereditary protein C deficiency and recurrent thromboembolism. Br J Dermatol 1995;132:283–5. 18. Donnet A, Khalil R, Terrier G, et al. Cerebral infarction, livedo reticularis, and familial deficiency in antithrombin-III. Stroke 1992;23:611–12.

19. Rosman HS, Davis TP, Reddy D, Goldstein S. Cholesterol embolization: clinical findings and implications. J Am Coll Cardiol 1990;15:1296–9. 20. Spiers EM, Sanders DY, Omura EF. Clinical and histologic features of primary oxalosis. J Am Acad Dermatol 1990;22:952–6. 21. Sladden MJ, Nicolaou N, Johnston GA, Hutchinson PE. Livedo reticularis induced by amantadine. Br J Dermatol 2003;149:655–80. 22. Wilkin JK. Why is flushing limited to a mostly facial cutaneous distribution? J Am Acad Dermatol 1988;19:309–13. 23. Freeman R, Waldorf HA, Dover JS. Autonomic neurodermatology (Part II): Disorders of   sweating and flushing. Semin Neurol 1992;12:  394–407. 24. Wilkin JK. The red face: flushing disorders. Clin Dermatol 1993;11:211–23. 25. Wilkin JK. Flushing reactions. Recent Adv Dermatol 1983;6:157–87. 26. Hurst E, Heffernan M. Cutaneous changes in the flushing disorders and the carcinoid syndrome. In: Freedberg I, Eisen A, Wolff K, et al., editors. Dermatology in General Medicine. 6th ed. New York, NY: McGraw-Hill; 2003. p. 1673–5. 27. Thompson GH, Hahn G, Rang M. Erythromelalgia. Clin Orthop Relat Res 1979;144:249–54. 28. Kvernebo K. Erythromelalgia: a condition caused by microvascular arteriovenous shunting. Vasa 1998;(Suppl. 51):1–40. 29. van Genderen PJ, Lucas IS, van Strik R, et al. Erythromelalgia in essential thrombocythemia is characterized by platelet activation and endothelial cell damage but not by thrombin generation. Thromb Haemost 1996;76:333–8. 30. Mork C, Asker CL, Salerud EG, Kvernebo K. Microvascular arteriovenous shunting is a probable pathogenetic mechanism in erythromelalgia. J Invest Dermatol 2000;114:643–6. 31. Berlin AL, Pehr K. Coexistence of erythromelalgia and Raynaud’s phenomenon. J Am Acad Dermatol 2004;50:456–60. 32. Yang Y, Wang Y, Li S, et al. Mutations in SCN9A, encoding a sodium channel alpha subunit, in patients with primary erythermalgia. J Med Genet 2004;41:171–4. 33. Choi JS, Dib-Hajj SD, Waxman SG. Inherited erythermalgia: limb pain from an S4 charge-neutral Na channelopathy. Neurology 2006;67:1563–7. 34. Han C, Dib-Hajj SD, Lin Z, et al. Early- and late-onset inherited erythromelalgia: genotype-phenotype correlation. Brain 2009;132:1711–22. 35. Fischer TZ, Waxman SG. Familial pain syndromes from mutations of the NaV1.7 sodium channel. Ann N Y Acad Sci 2010;1184:196–207.

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may also occur on the trunk. They are more noticeable in patients with lightly pigmented skin. Angiospastic macules may be induced by venous congestion and can be elicited by placing a limb in a dependent position or by placing a tourniquet around a limb. The spots disappear with limb elevation or release of the tourniquet. As with nevus anemicus, the border of the lesions becomes imperceptible with pressure

36. Burns TM, Te Morsche RH, Jansen JB, Drenth JP. Genetic heterogeneity and exclusion of a modifying locus at 2q in a family with autosomal dominant primary erythermalgia. Br J Dermatol 2005;153:174–7. 37. Davis MDP, O’Fallon WM, Rogers RS III, Rooke TW. Natural history of erythromelalgia. Arch Dermatol 2000;136:330–6. 38. Iqbal J, Bhat MI, Charoo BA, et al. Experience with oral mexiletine in primary erythromelalgia in children. Ann Saudi Med 2009;29:316–18. 39. Natkunarajah J, Atherton D, Elmslie F, et al. Treatment with carbamazepine and gabapentin of a patient with primary erythermalgia (erythromelalgia) identified to have a mutation in the SCN9A gene, encoding a voltage-gated sodium channel. Clin Exp Dermatol 2009;34:e640–2. 40. Cohen JS. Erythromelalgia: new theories and new therapies. J Am Acad Dermatol 2000;43:841–7. 41. Bean WB. Vascular Spiders and Related Lesions of the Skin. Oxford: Blackwell Scientific; 1958. 42. Rothe MJ, Grant-Kels JM. Nomenclature of the primary telangiectasias. Int J Dermatol 1992;31:320. 43. McGrae JD Jr, Winkelmann RK. Generalized essential telangiectasia: report of a clinical and histochemical study of 13 patients with acquired cutaneous lesions. J Am Med Assoc 1963;185:909–13. 44. Salama S, Rosenthal DJ. Cutaneous collagenous vasculopathy with generalized telangiectasia: an immunohistochemical and ultrastructural study. J Cutan Pathol 2000;27:40–8. 45. Davis TL, Mandal RV, Bevona C, et al. Collagenous vasculopathy: a report of three cases. J Cutan Pathol 2008;35:967–70. 46. Wilken JK. Unilateral dermatomal superficial telangiectasia. Arch Dermatol 1984;120:579–80. 47. Uhlin SR, McCarty KS Jr. Unilateral nevoid telangiectatic syndrome: the role of estrogen and progesterone receptors. Arch Dermatol 1983;119:226–8. 48. Hunt SJ, Santa Cruz DJ. Acquired benign and ‘borderline’ vascular lesions. Dermatol Clin 1992;10:97–115. 49. Marriott PJ, Munro DD, Ryan T. Angioma serpiginosum: familial incidence. Br J Dermatol 1975;93:701–6. 50. Abrahamian LM, Rothe MJ, Grant-Kels JM. Primary telangiectasia of childhood. Int J Dermatol 1992;31:307–13. 51. Smith LL, Conerly SL. Ataxia-telangiectasia or Louis-Bar syndrome. J Am Acad Dermatol 1985;12:681–96. 52. Bean WB, Walsh JR. Venous lakes. Arch Dermatol 1956;74:459–63. 53. Alcalay J, Sandbank M. The ultrastructure of cutaneous venous lakes. Int J Dermatol 1987;26:645–6. 54. Mountcastle EA, Diestelmeier MR, Lupton GP.   Nevus anemicus. J Am Acad Dermatol 1986;14:  628–32.

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106 Other Vascular Disorders



eFig. 106.1 Sneddon syndrome. The characteristic irregular, broken, branching pattern of livedo racemosa is seen on the back and arms.  

eFig. 106.3 Reticulate purpura and cutaneous necrosis due to calciphylaxis. These patients also often have patchy areas of livedo reticularis. Courtesy, Norbert  

Sepp, MD.

eFig. 106.4 Hereditary benign telangiectasia. Fine linear and punctate telangiectasias are seen on the cheeks and vermilion lips bilaterally in this child. There is no associated visceral involvement. Courtesy, Antonio Torrelo, MD.  

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eFig. 106.5 Spider telangiectasia. A Central arteriole with radiating telangiectatic “legs” on the cheek of a young child. B Multiple lesions in a jaundiced patient with liver disease.  

Vascular Disorders



A, Courtesy, Phillip Bekhor, MD; B, Courtesy, Ronald P Rapini, MD.

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SECTION 18 NEOPLASMS OF THE SKIN

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Principles of Tumor Biology and Pathogenesis of BCCs and SCCs Oscar R. Colegio, Edel A. O’Toole, Fredrik Pontén, Joakim Lundeberg and Anna Asplund

Chapter Contents Structure and function of p53 . . . . . . . . . . . . . . . . . . . . . . 1863 Structure and function of Patched . . . . . . . . . . . . . . . . . . . 1865 Pathogenesis of BCC . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1867 Pathogenesis of SCC . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1868 Related diseases . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1870

Key features ■ Oncogenes act in a dominant fashion and gain-of-function results in increased cellular proliferation ■ Tumor suppressor genes act in a recessive fashion and loss of normal function results in uncontrolled growth ■ TP53, the gene that encodes p53, is the single most frequently mutated gene in human cancer; p53 controls signaling pathways involved in cell division and apoptosis ■ Mutations in either apoptosis- or senescence-regulating genes are considered “driver” mutations and are uniformly present in cancers ■ PTCH1 controls proliferation and differentiation, and disruption of its normal function is required for the development of basal cell carcinoma (BCC) ■ BCCs, the most frequent cancer in humans, develop in skin that contains hair follicles, and they arise without precursors ■ BCCs are stroma-dependent, locally invasive, and very rarely develop metastasis ■ Squamous cell carcinomas (SCCs) arise in chronically sun-exposed skin and originate from epidermal keratinocytes ■ SCC develops through a series of progressive stages, including actinic keratosis, SCC in situ, invasive cancer, and eventual metastasis

INTRODUCTION

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No definition of cancer is entirely satisfactory from a cell biology point of view, despite the fact that cancer is essentially a cellular disease, characterized by a transformed cell population with autonomous cell growth and invasive behavior. Microscopic evaluation of a tissue section taken from an excised skin tumor remains the gold standard for determining the diagnosis of skin cancer. Analysis of genomic DNA, transcribed genes, and expressed proteins adds important information to the histologic features detected by light microscopy. In the future, diagnosis and prognostic information as well as choice of treatment will most likely be based upon a synoptic evaluation of tissue architecture in conjunction with an analysis of molecular characteristics. Even today, evolving knowledge based on the human genome sequence and biochemical pathways, including signaling within and between cells, enables us to dissect some of the mechanisms that underlie different stages in tumor formation as well as the variation of phenotypes which define the different types of cancer.

Carcinogenesis Malignant transformation represents the transition from a normal to malignant phenotype and is based on the progressive accumulation of genetic alterations. Although not formally proven, malignant transformation takes place in one cell from which a subsequently developed tumor originates (the dogma of cancer clonality). Carcinogenesis is the process by which cancer is generated and is generally accepted to include multiple events, which ultimately lead to growth of a malignant tumor1. This multistep process includes several rate-limiting steps, representing the acquisition of mutations and epigenetic modifications, eventually leading to the formation of cancer (after various stages of precancerous proliferation). The most common forms of cancer arise in somatic cells and are predominantly of epithelial origin (most often skin, prostate, breast, lung or colon), followed by cancers originating from hematopoietic lineage (leukemia and lymphoma) and mesenchymal cells (sarcomas). The stepwise changes involve an accumulation of errors (mutations) in vital regulatory pathways that control cell division, apoptosis, senescence, cell–cell and cell–matrix interactions, and cell death. Each of these changes provides a selective growth advantage compared to surrounding cells, resulting in a net growth of the tumor cell population. A certain degree of genomic instability is likely required in order to accumulate a sufficient number of mutations. The spontaneous mutation rate is not high enough to explain the speed with which a cancer develops and thus tumor cells display a “mutator phenotype” with a higher mutation rate compared to neighboring normal cells. Decreased efficiency in DNA repair systems is one important mechanism that leads to a “mutator phenotype”2. Knowledge of the events involved in carcinogenesis has been obtained from experimental cell culture and animal studies, as well as from clinicopathologic studies in humans. Information regarding cellular, molecular and genetic changes that represent tumor initiation and progression can be correlated with histopathologic findings. Primary genetic alterations leading to initiation of cancer can be identified and validated in experimental systems, but in clinical investigations this is not feasible. Progression is ascribed to the events that occur after malignant transformation and can in part be defined by histology. This multistep model includes defined stages of tumor development accompanied by features including multiple genetic and epigenetic events involving different signaling pathways. Specific changes in DNA, signifying different steps in cancer development, were first described for colorectal cancer3. This model illustrates distinct genetic hits acquired during the passage from normal epithelium to metastatic cancer and provides support for the multi-hit carcinogenesis hypothesis. The hallmarks of cancer have also been described from a functional perspective and consist of a number of molecular, biochemical, and cellular traits that are shared by most human cancers. Six traits have been proposed and include self-sufficiency with regard to growth signals, insensitivity to anti-growth signals, evasion of apoptosis, limitless replicative potential, sustained angiogenesis, and tissue invasion/ metastasis4. Self-sufficiency with regard to growth signals can be achieved by activation of oncogenes. Loss-of-function of tumor suppressor genes results in uncontrolled proliferation due to insensitivity to anti-growth signals. Evasion of apoptosis can be accomplished via inactivation of the TP53 tumor suppressor gene and production of survival factors. Constitutively active telomerase can render limitless replicative potential. The production of vascular endothelial growth factors results in sustained angiogenesis, and inactivation of cellular adhesion

Oncogenes act in a dominant fashion and gain-of-function results in increased cellular proliferation. Tumor suppressor genes act in a recessive fashion and loss of normal function results in uncontrolled growth. TP53, the tumor suppressor gene that encodes p53, is the single most frequently mutated gene in human cancer and controls signaling pathways involved in cell division and apoptosis. Mutations in either apoptosis- or senescence-regulating genes are considered “driver” mutations and are uniformly present in cancers. Disruption of the normal function of the Sonic hedgehog (SHH)– Patched–Smoothened (SMO) pathway is required for the development of basal cell carcinoma (BCC). BCCs, the most frequent cancer in humans, develop within skin that contains hair follicles, and they arise without precursors. BCCs are stroma-dependent, locally invasive, and very rarely develop metastasis. Squamous cell carcinomas (SCCs) arise in chronically sun-exposed skin and originate from epidermal keratinocytes. SCC develops through a series of progressive stages, including actinic keratosis, SCC in situ, invasive cancer, and eventual metastasis.

basal cell carcinoma, squamous cell carcinoma, p53, TP53, Patched, Sonic hedgehog (SHH), Smoothened, Hedgehog signaling pathway, oncogenes, tumor suppressor genes, apoptosis, skin cancer, PTCH1

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107  Principles of Tumor Biology and Pathogenesis of BCCs and SCCs

ABSTRACT

non-print metadata KEYWORDS:

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The Cell Cycle Normal cell growth and cell mass are influenced by several internal factors, including signals which regulate proliferation, differentiation, and cell death. These factors are in part triggered by blood supply and the external environment, including soluble molecules as well as matrix–cell and cell–cell contacts. Proliferation involves DNA replication and mitosis via a series of events termed the cell cycle (Fig. 107.1). Three primary checkpoints (G1, G2 and M), which act to ensure successful cell division, have been identified in the cell cycle5. Regulation of these G1, G2 and M transitions involves three major protein families: cyclins, cyclin-dependent kinases (CDKs), and cyclin-dependent kinase inhibitors (CKIs). CDKs regulate the phosphorylation of key proteins involved in cell cycle progression, e.g. the retinoblastoma (Rb) protein. The concentration and balance of cyclins versus CKIs in turn regulate CDK activity. CDKs are activated by mitogenic growth factors and are removed by ubiquitin-mediated proteolysis in a cyclic manner correlating with the different phases of the cell cycle.

The G1 transition is a critical one and is regulated by a complex interplay of macromolecules influenced by growth factors, hormones, and cell contacts. The key factor is the degree of phosphorylation of Rb. If, at the G1 checkpoint, Rb is underphosphorylated, then cell proliferation is blocked and the cell is arrested in G1. The repression can be reversed by CDK–cyclin complex-mediated phosphorylation. This phosphorylation/dephosphorylation cycle can thus reversibly regulate cell cycle progression and rate of proliferation (see Fig. 107.1). There are two major families of CKIs, and both are involved in the G1 checkpoint. The family of inhibitors of CDK4, also referred to as INK4, consists of p15, p16, p18 and p19; these inhibitors specifically bind to CDK4 and CDK6. The other family of CKIs is less specific with respect to the type of CDK they bind and includes the general CDK– cyclin complex inhibitors p21, p27 and p57. Expression of these CKIs is in part tissue-specific. The CDKN2A (INK4A) gene locus, which is involved in familial melanoma (see Ch. 113), has an extraordinary feature; it encodes two different mRNAs by shifting the codon reading frame (hence the term alternative reading frame [ARF]) and these two mRNAs are independently regulated. As a result, the two protein products – p16 and p14ARF – have different amino acid sequences and different functions. p16 is a CKI that blocks Rb phosphorylation, whereas p14ARF binds MDM2, resulting in an increase in p53 through interference with the p53–MDM2 feedback loop (see Fig. 107.1). Thus, both p16 activation and p14ARF activation lead to cell cycle arrest through different pathways and their dysfunction can lead to cell proliferation. In carcinomas, cyclin and CKI alterations are common, whereas activating mutations in CDKs are rare, e.g. only a few families with familial melanoma have been described with mutations in CDK4. p53 and Rb alterations are also common events in human cancer.

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107  Principles of Tumor Biology and Pathogenesis of BCCs and SCCs

molecules, e.g. E-cadherin, facilitates the cell migration necessary for tissue invasion and metastasis. The order in which these capabilities are acquired is not static and varies amongst different forms of cancer. Several traits can be achieved through a single genetic change, whereas a certain trait may require several genetic alterations. For example, inactivation of the TP53 tumor suppressor gene can result in insensitivity to anti-growth signals, resistance to apoptosis, and increased angiogenesis. In addition, impairment of cell cycle control and apoptotic pathways contributes to the “mutator phenotype”. In individuals predisposed to cancer at an early age, certain traits result from alterations in the germline and are thus carried in every cell. Xeroderma pigmentosum (“mutator phenotype”; mutations in nuclear excision repair genes; Ch. 86), familial melanoma (defect in cell cycle control; CDKN2A [INK4A] mutations), Li–Fraumeni syndrome (defect in cell cycle control/apoptosis; TP53 mutations), and basal cell nevus syndrome (BCNS; defect in control of proliferation/differentiation; PTCH1 mutations) are examples of how mutations within single genes in the germline predispose one to the development of cancer.

Cancer Genes – Oncogenes and Tumor Suppressor Genes With advances in technology, it is now possible to catalogue genomewide changes in DNA, at unparalleled resolution. In breast and colon cancer, sequencing the exomes (coding exons) of tumors has revealed

Fig. 107.1 Cell cycle regulation. In normally dividing cells, the first gap (G1 phase, 8–30 h) prepares the cell for DNA synthesis (S phase, 8 h). The G1 gap includes a connection to a resting state (G0 phase) representing quiescent cells capable of entering into G1 after appropriate stimuli. Certain cells that exit the cell cycle and enter G0 phase are destined for terminal differentiation or senescence, irreversibly locked out of the cell cycle. After S phase, reorganization of the chromatin occurs in a second gap (G2 phase, 3 h) prior to mitosis (M, 1 h). Differentiation, which has a reciprocal correlation to proliferation, takes place in G0 after exit from G1. Cyclin waves, an underlying mechanism for cell cycle progression, are illustrated inside the cell cycle. Protein products of proto-oncogenes, acting as driving forces on the cell cycle (green traffic lights), are depicted in green. Protein products of tumor suppressor genes, regulating the G1 checkpoint (red traffic light) of the cell cycle, are depicted in red. Yellow traffic light symbols represent checkpoints in the cell cycle. Both p16 and p14ARF are encoded by CDKN2A. CDK, cyclin-dependent kinase; E2-F, a transcription factor that controls transcription of cyclins; Rb, retinoblastoma protein.  

CELL CYCLE REGULATION

Protooncogenes

Growth factors

Cell membrane

Growth factor receptors Myc

Inhibition Stimulation Phosphorylation

Resting G0

Signal Ras transduction

Tumor suppressor genes

Underphosphorylated Rb Mitosis Metaphase M checkpoint

G1 Gap 1 EA

B1 B2

D1 C

G0

G1

S

G2

M

Cyclin waves drive cell cycle progression G2 checkpoint

G1 checkpoint

G2

S

Gap 2

DNA synthesis

p15

Rb

Mitogenic signals

CDK

E2-F

p16

Phosphorylated Rb

p21

Rb

p27

Cyclin

CDK inhibitors

CDK E2-F Cyclin-dependent kinase-cyclin complex Transcription of G1/S cyclins MDM2

p53

p14ARF

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an average of 50 to 100 somatic mutations in “cancer genes” in each tumor6. Are these all significant? The answer is probably no. Somatic alterations in tumor DNA are called either driver mutations that confer a selective growth advantage to the cancer cells or passenger mutations that have no effect on tumorigenesis. Somatic copy number alterations can also occur7,8. An increase in gene function (oncogenes) as well as a loss of gene function (tumor suppressor genes) will affect cell proliferation and can lead to uncontrolled growth. These two categories of genes, and their encoded proteins, represent the functional features that drive carcinogenesis at a molecular level. Oncogenes, originally named with three-letter acronyms (e.g. ras, myc, src, fos), are genes that gain oncogenic or transforming potential as a result of genetic changes9. More than 400 “cancer genes” have been identified that participate in diverse regulatory pathways that control cell fate; examples are listed in Table 107.1. Extracellular signals such as growth factors and extracellular matrix components determine if cells move from a quiescent state into a proliferative state. These signals are transmitted into the cell through transmembrane structures that have distinct features (e.g. receptors) and the signals are then propagated into the nucleus by a multitude of interacting pathways (i.e. signal transduction). Increased production of growth factors and growth factor receptors is frequently observed in cancer cells; this results in autocrine and paracrine loops that lead to enhanced cell proliferation10. Upon ligand binding, growth receptors mediate signals via tyrosine kinases or serine/threonine kinases on the cytosolic side of the membrane (see Ch. 55). Cancer cells can also alter receptor activity via “activating” mutations in the genes that encode the receptors, thus generating constitutively active, ligand-independent receptor molecules (e.g. KIT in acral melanoma). The ras proto-oncogene, which is mutated in at least 30% of human cancers, plays a key role in signal transduction pathways between the cell membrane and the nucleus, communicating signals to a number of effector pathways. The ras family members are H-ras, K-ras and N-ras, and the 21 kDa Ras protein is a GTP-binding protein with latent GTPase activity, active when bound to GTP and inactive when GTP is hydrolyzed to GDP. The ras oncogene acts as a multifunctional modulator capable of redirecting input signals from growth receptors to alternative pathways. The end result of the signal cascade following Ras

EXAMPLES OF ONCOGENES AND TUMOR SUPPRESSOR GENES ASSOCIATED WITH CARCINOGENESIS

Gene

Protein product

Name

Function

Chromosome

PDGFB

Oncogene

HRAS SRC

Location

Function

22

Extracellular

Platelet-derived growth factor (PDGF)

Oncogene

11

Membrane

GTPase

Oncogene

20

Cytoplasm/ membrane

Tyrosine kinase

Apoptosis

RAF1

Oncogene

3

Cytoplasm/ membrane

Serine/threonine kinase

MYC

Oncogene

8

Nucleus

Transcription factor

FOS

Oncogene

14

Nucleus

Transcription factor

RB1

Suppressor gene

13

Nucleus

Cell cycle regulator

TP53

Suppressor gene

17

Nucleus

DNA repair, apoptosis

BCL2

Suppressor gene

18

Mitochondria

Apoptosis

An equilibrium between proliferation and cell death is essential for normal homeostasis, and an imbalance can lead to abnormal growth. Cell death is important for tissue remodeling during embryogenesis and for maintaining homeostasis in normal adult tissues. Cell death is equally crucial for the removal of damaged cells, and this can occur via two different mechanisms – necrosis or apoptosis13. Necrosis involves poor nutrient supply leading to membrane disruption and cell lysis without de novo protein synthesis. In contrast, apoptosis is regulated and requires mRNA and protein synthesis. Microscopically, apoptosis is characterized by the appearance of apoptotic bodies composed of cell membrane remnants and condensed chromatin. Apoptosis-related proteases, termed caspases, become activated and affect signal transduction pathways by activation of: (1) enzyme precursors that digest genomic DNA into 200 base pair (bp) units; and (2) proteases that degrade structurally important proteins such as lamins and actin (Fig. 107.4). Apoptosis can be induced by several different stimuli, including DNA damage (e.g. due to radiation, chemicals), withdrawal of growth cytokines (e.g. EGF, TGF-α, IGF,

Table 107.1 Examples of oncogenes and tumor suppressor genes associated with carcinogenesis. A non-mutated oncogene is often referred to as a “proto-oncogene” and it encodes a protein that is part of the necessary network for regulating cell proliferation.  



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activation is increased transcription due to an alteration in the quantity or function of nuclear transcription factors (see Ch. 113). For oncogenes, a change in one of the two inherited alleles leads to a gain-of-function that is dominant (over that of the unaffected allele). In contrast, tumor suppressor genes act in a recessive manner, i.e. a mutation in one allele has no effect (Fig. 107.2). The biologic consequence of a recessive mutation becomes apparent when the second, normal (wild-type) allele is lost. Loss of this allele is termed loss of heterozygosity (LOH) and represents alteration from a heterozygous to a homozygous state for a gene (Fig. 107.3). The tumor suppressor genes are of critical importance in human carcinogenesis. In contrast to the diverse interactions of oncogenes converging to stimulate growth, tumor suppressor genes act by inhibiting proteins that control cell cycle progression. Inactivation of both alleles of a suppressor gene (one of which may be inherited in an inactivated state as in familial cancer syndromes) is required to inactivate the normal repressive function. In normal cells, inactivation of the protein products of tumor suppressor genes is achieved via binding to other proteins or by phosphorylation. In tumor cells, inactivation is often due to mutations, insertions, and/or deletions (allelic loss; see Fig. 107.3). The Rb protein serves as a classic example for examining the functions of tumor suppressor genes. Underphosphorylated Rb protein blocks proliferation in normal cells by binding to, and thereby inactivating, a transcription factor (E2F); E2F is necessary for propagation of the cell cycle (see Fig. 107.1). Serine/threonine phosphorylation of the Rb protein disrupts this binding, releasing E2F and enabling cell cycle progression. Genes that control the levels of Rb phosphorylation (e.g. CDKN2A) act as tumor suppressor genes and are often inactivated in cancer by mutation or promoter methylation. The TP53 gene is frequently inactivated by a point mutation, and as opposed to classic tumor suppressor genes (that act in a recessive manner), TP53 mutations can act in a dominant-negative manner (see Ch. 54 & Fig. 107.3). This is because the p53 protein is a tetrameric protein and oligomerization of a mutant allele product and a normal allele product results in an inactive protein. MicroRNA (miRNA) is non-coding RNA that regulates translation and degradation of specific mRNAs (see Fig. 3.15). Dysregulation of miRNA expression has been associated with oncogenic transformation, and miRNAs whose actions mimic oncogenes or tumor suppressors have been identified in human cancer. For example, miRNA-31 has been identified as a metastasis suppressor11. Epigenetic change is a modification to DNA or associated histone proteins, without variation in DNA sequence. There are two major mechanisms of epigenetic modification, DNA methylation (addition of a methyl [CH3] group) and chromatin or histone modification. DNA methylation occurs in cytosines that precede guanines, known as dinucleotide CpGs or CpG islands, which occur in the promoter regions of many genes and generally results in gene silencing. However, changes in methylation may also occur in non-CpG-island regions, usually in close proximity to CpG islands. In cancer, methylation of cancer genes is more common than loss-of-function mutations or deletions12.

Fig. 107.2 Carcinogenesis: oncogenes versus tumor suppressor genes. A Under physiologic conditions, proto-oncogenes control the rate of cell cycle progression (left). Oncogenes are proto-oncogenes that have acquired activating mutations, represented by the yellow dot within the second allele (center) or gene amplifications (right). Oncogenes function in a dominant fashion, meaning that activating alterations in only one allele are sufficient for the gene to gain oncogenic potential. B A tumor suppressor gene acts as a brake on the cell cycle, decreasing cell proliferation. Tumor suppressor genes are inactivated by mutations in both alleles. Tumor suppressor genes function in a recessive manner, meaning that a mutation in only one allele is not sufficient for loss of gene function. Fig. 107.3 demonstrates the various mechanisms by which the “second hit” occurs in tumor suppressor genes.  

A

Oncogenes Normal cell

Cancer cell

Cancer cell

Activating mutation Alleles

Gene amplification

Alleles CCP

Alleles

↑ CCP

B

↑ CCP

Tumor suppressor genes Normal cell

Normal cell (vulnerable)

Alleles

Cancer cell

Alleles

Alleles

Deletion or CCP inactivating mutation

CCP

↑ CCP

Deletions or inactivating mutations

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107  Principles of Tumor Biology and Pathogenesis of BCCs and SCCs

CARCINOGENESIS: ONCOGENES VS TUMOR SUPPRESSOR GENES

CCP = Cycle cell progression ↑ CCP = Increased cycle cell progression

Fig. 107.3 Mechanisms of loss of heterozygosity and inactivation of wild-type tumor suppressor genes. Mechanisms depicted by which both copies of a gene can be inactivated (bottom). With loss of heterozygosity (LOH), the resultant changes are best explained by the absence of wild-type protein. While translocations usually activate oncogenes or generate new fusion proteins, they can also be associated with microdeletions. An alternative mechanism exists (right) in which the wild-type allele is rendered non-functional. That is, some mutations can lead to expressed truncated proteins, and the latter may have dominant-negative effects or may be partially functional. An example would be the p53 protein.  

MECHANISMS OF LOSS OF HETEROZYGOSITY AND ACTIVATION OF WILD-TYPE TUMOR SUPPRESSOR GENES

Maternal

Paternal

Inherited or acquired “first hit”

If no “second hit” required

Adapted and redrawn from Foulkes WD. Inherited susceptibility to common cancers. N Engl J Med. 2008;359:2143–53.

*

Epigenetic silencing

Gene conversion

Disruptive translocation

Dominant negative

Interstitial deletion

Point mutation

Loss without reduplication

Loss of reduplication

Mitotic recombination

Terminal deletion

Acquired “second hit”

*For example: methylation of CpG islands within the promoter region can lead to gene silencing. 1861

Fig. 107.4 Apoptotic pathways. Various triggering events are depicted within blue-colored boxes. Consequences of induced apoptosis are shown at the bottom of the figure within green-colored boxes. Fragmentation of genomic DNA by endonucleases results in a discrete ladder of DNA fragments of decreasing lengths as seen in the left two lanes compared to the DNA standard ladder in the right-most lane. Cyt, cytochrome; EGF, epidermal growth factor; TNF, tumor necrosis factor.  

APOPTOTIC PATHWAYS

SECTION

Death-promoting signals (e.g. TNF)

18 Neoplasms of the Skin

Withdrawal of growth stimulatory signals (e.g. EGF)

Caspases

Cytoplasm

BCL2

BAX

p53

Nucleus

DNA damage

Mitochondrion

Cyt C

Caspases

Activate endonuclease (internal DNA breaks)

Degradation of lamins (nuclear matrix)

Degradation of actin (cytoskeleton)

DNA fragmentation

Chromatin condensation

Apoptotic bodies

PDGF), and death-promoting agents (e.g. TNF) (see Fig. 107.4). Conflicts between different signaling pathways can also provoke apoptosis. Independent of triggering apoptotic stimuli, apoptosis converges into a common series of molecular events that lead to irreversible morphologic changes and ultimately cell death. The regulation of apoptosis is under the strict control of proteins, including BCL-2 and BAX, both members of the BCL-2 family of proteins that are capable of regulatory cross-talk by heterodimerization of protein subunits. The mitochondrial membranes contain proteins that either activate apoptosis (BAX) or inhibit apoptosis (BCL-2). Overexpression of the survival factor BCL-2 blocks apoptosis and thus protects the cells against radiation and chemotherapeutic agents. The p53 protein activates transcription of BAX and inhibits transcription of BCL2, the net result favoring apoptosis. Thus, the p53 protein is a key factor for integrating pathways regulating DNA synthesis, DNA repair, and apoptosis.

Limitless Replicative Potential

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The number of mutations in a cell increases with time and partially explains the increasing risk for acquiring cancer as we age. The increased number of mutations is evident in normal cultured cells, which undergo ~60–70 doublings before reaching senescence and then death as a consequence of accumulating mutations and telomere shortening. Senescent cells are viable, but they are incapable of proliferation. During senescence, abnormal chromosomes accumulate and the telomere sequences diminish, eventually resulting in a crisis that leads to apoptosis.

The progressive erosion of telomere sequences (50–100 bp per mitosis) through successive cycles of replication eventually precludes protection of the ends of the chromosomes (see Fig. 67.22). This facilitates end-to-end chromosomal fusions, resulting in karyotypic disarray and then apoptosis. Carcinogenesis involves disruption of these normal apoptotic events, yielding limitless replicative potential for the tumor cells. Up to 90% of all cancers exhibit increased levels of telomerase, the enzyme required for maintenance of telomere sequences in normal cells; this leads to retention of telomeres irrespective of the number of cell divisions14. Cancer cell populations also contain a subpopulation of self-renewing cells called cancer stem cells. These latter cells can increase in number as tumors enlarge and they can give rise to progeny that have the ability to invade locally as well as metastasize to distant sites, referred to as tumor-propagating cells (TPCs)15. Markers such as CD133, CD44 and ALDH (aldehyde dehydrogenase) are expressed by TPCs, and this population can be expanded within tumors by symmetrical division of TPCs and by cancer cells undergoing epithelial–mesenchymal transition.

Angiogenesis Formation of new blood vessels (angiogenesis) is essential for tumor mass expansion, in order to provide adequate levels of oxygen and nutrients16. Endothelial cells are normally quiescent, with low proliferative rates and mitoses rarely being observed (aside from the setting of wound healing). Angiogenesis is initiated by growth factors, e.g. fibroblast growth factor (FGF) and vascular endothelial growth factor (VEGF), acting in a paracrine fashion and stimulating local endothelial

Invasion/Metastasis Cell–cell interactions and extracellular glycoprotein matrix recognition are achieved by four classes of membrane-bound receptors, consisting of integrins, cadherins, selectins, and members of the immunoglobulin family. All of these cellular adhesion molecules have an extracellular domain that binds ligands, leading to a conformational change in the cytoplasmic tail of the receptor. Upon ligand binding, internal regions of the receptors bind to specific cytoplasmic proteins influencing various pathways involved in proliferation, cell migration, differentiation, and apoptosis. The extracellular ligands for integrins are matrix components composed of collagen, fibronectin or laminin (see Fig. 141.9) and immunoglobulin family members (see Table 102.3). Cadherins bind to cadherins present on adjacent cells and selectins bind to carbohydrate chains. Disruption of tissue organization is a hallmark of cancer and is the result of alterations in cellular adhesion receptors, resulting in selective growth advantage. In cell cultures, dysregulation of cell adhesion pathways underlies anchorage-independent growth. Metastases from epithelial cancers often lose E-cadherin expression, facilitating the escape of cells from the primary site to other locations. E-cadherin expression can be inactivated by hypermethylation of regulatory regions as well as mutations in the coding sequence. Alternatively, inactivation occurs through proteolysis of the extracellular domain of E-cadherin or mutations in the gene encoding E-cadherin’s intracellular ligand, β-catenin. Tumors are not comprised purely of neoplastic cells. Rather, they share properties with organs, including being composed of multiple cell types, possessing an extracellular matrix, and having both blood and lymphatic vessels17. Signaling between neoplastic cells and the tumor constituent cells, e.g. fibroblasts, macrophages and endothelial cells, appears to be important for the growth of a tumor and is often induced by signals from the neoplastic cells18. Reciprocal release of abundant growth-stimulating signals creates amplifying loops enabling growth of both the tumor and its cognate stroma. In humans, the most common cancers are basal cell carcinoma (BCC) and squamous cell carcinoma (SCC), often termed “nonmelanoma skin cancers”. Although BCCs and SCCs possess many similar features, there are fundamental biologic differences, justifying a distinction between the two and rendering “non-melanoma skin cancer” a poor conceptual term. In the remainder of this chapter, BCC and SCC will be described with an emphasis on the similarities and the differences between their tumor biology. Disruption of the Hedgehog–Patched signaling pathway is closely linked to development of BCC while the TP53 gene is often mutated in both BCC and SCC. The Patched (PTCH1) and TP53 genes will serve as a model to illustrate some of the basic features of epithelial skin carcinogenesis.

STRUCTURE AND FUNCTION OF p53 Background The TP53 tumor suppressor gene was first described in 1979 and was initially erroneously classified as an oncogene due to its ability to transform cells. The wild-type p53 protein is involved in a multitude of cellular events and illustrates the complex molecular machinery within a cell19. The p53 protein is regarded as the “guardian of the genome” as it protects DNA integrity in response to cytotoxic stress, including radiation. Protection is achieved by management of signaling pathways that regulate cell cycle progression, DNA repair, and apoptotic cell death. The ability of p53 to induce apoptosis by transactivation of target genes is critical for its function as a tumor suppressor gene. Aside from genomic alterations, p53 protein can also be inactivated by binding to other proteins, such as the viral proteins adenovirus E1B, human papillomavirus E6, and the SV40 T-antigen.

Regulation of the TP53 Gene and p53 Protein The TP53 gene is located on the long arm of chromosome 17 and contains 11 exons spanning some 20 000 bp of genomic sequence. The gene encodes a 53 kDa nuclear phosphoprotein of 393 amino acid residues. Four functional domains involved in the regulation of transcription, DNA binding, oligomerization, and auto-inhibition are recognized (Fig. 107.5A). Transcription is indirectly regulated within the transactivation domain (42 amino acid residues) either by binding to other proteins or by phosphorylation. For example, the nuclear protein MDM2 is capable of inactivating wild-type p53 protein by binding to the transactivation domain. Subsequent to binding to MDM2, p53 is degraded via the ubiquitin-mediated proteolysis pathway. In normal cells containing latent p53 protein bound to MDM2, the half-life of p53 is approximately 2 minutes. Interaction between MDM2 and the p53 protein is dependent upon phosphorylation of the p53 transactivation domain as well as interactions with other proteins. Upon DNA damage, serine protein kinases are activated that readily phosphorylate p53 and release it from MDM2 binding. Up to a 100-fold increased cellular content of functional p53 is thus obtained without a requirement for protein synthesis. p53 protein is a transcription factor for MDM2, thus creating a feedback loop between p53 and MDM2. MDM2 protein levels are further regulated by binding to the p14ARF protein (see Fig. 107.1), which translocates MDM2 to the nucleolus and thus prevents MDM2–p53 interaction. The structure of the DNA-binding domain has been shown to consist of a scaffold with three loops. The first loop binds to the major groove of the target DNA sequence. The second loop has contact with the minor groove, and the third loop stabilizes the second loop via a zinc atom. The majority (80–90%) of detected TP53 mutations involve the sequence-specific DNA-binding domain and there are a number of hotspots within this region (Fig. 107.5B,C). The p53 protein requires a tetramer configuration for DNA binding (Fig. 107.6). The oligomerization domain is responsible for assembly of the protein. Because both normal and mutant allele products can be assembled together, this leads to the dominant-negative phenotype (see Ch. 54) that is characteristic of the mutant p53 protein. The autoinhibitory domain of 30 basic amino acid residues is thought to block the DNA-binding domain and can be removed by phosphorylation or binding to other proteins such as TATA box-binding proteins (TBP). The p53 protein exerts its effects predominantly (but not exclusively) at the level of transcription. Genes that increase their transcription due to interaction with p53 contain a promoter (response) element for binding to the p53 tetramer (Table 107.2). The transactivation domain of p53 can also recruit additional transcription factors required for transcription.

CHAPTER

107  Principles of Tumor Biology and Pathogenesis of BCCs and SCCs

proliferation (see Ch. 102). Sprouts from surrounding vasculature migrate toward the tumor via protease-mediated remodeling of extracellular matrix (e.g. by serine proteases and metalloproteinases), thereby establishing new matrix–cell contacts. Of note, cancer cells express increased levels of VEGF and FGF. Inhibitors of angiogenesis, e.g. angiostatin, endostatin and thrombospondin, have been identified in plasma and extracellular matrix. Because thrombospondin is activated by p53, inactivation of p53 facilitates angiogenesis.

The Cellular Response to DNA Damage p53 is a general sensor of cytotoxic stress and can be activated by several types of DNA insults that create single- and double-strand breaks as well as cyclobutane pyrimidine dimers and 6-4 photoproducts, e.g. chemicals or gamma and UV radiation (see Ch. 86). In response to DNA damage, the level of p53 protein increases rapidly within the cell

EXAMPLES OF GENES WHOSE TRANSCRIPTION IS REGULATED BY THE p53 TETRAMER

Gene (protein)

Regulation

Cellular function

CDKN1A (p21)

Activation

Cell cycle inhibition

GADD45A (GADD45)

Activation

Cell cycle inhibition

BAX (Bax)

Activation

Apoptosis

THBS1 (Thrombospondin)

Activation

Angiogenesis

MDM2 (MDM2)

Inhibition

Regulatory

BCL2 (BCL-2)

Inhibition

Apoptosis

Table 107.2 Examples of genes whose transcription is regulated by the p53 tetramer.  



1863

Fig. 107.5 The TP53 gene: functional organization and map of mutations. A There are four functional domains and they are involved in transactivation, sequence-specific DNA binding, oligomerization, and auto-inhibition. Binding sites for MDM2 and TBP proteins are noted. The frequencies of mutations are shown with respect to specific codons within TP53 in all cancers (B) versus skin cancers (basal cell carcinoma + squamous cell carcinoma; C). Numbers represent hotspot codons for TP53 mutations. The gray bars represent evolutionary conserved regions of TP53. TBP, TATA box-binding protein. Adapted from  

THE TP53 GENE

SECTION

Functional organization

Transactivation 1

Neoplasms of the Skin

18

A

DNA binding 100

300

Auto-inhibition Oligomerization 393 Phosphorylation sites

Phosphorylation sites

MDM2

Hernandez-Boussard T, et al. IARC p53 mutation database. Hum Mutat. 1999;14:1–8.

TBP

MAP OF MUTATIONS

B

All cancers 700 248

273

600

Mutation frequency

500

175

400 245

300

249 282

200 100 0 0

20

40

60

C

80 100 120 140 160 180 200 220 240 260 280 300 320 340 360 380 400 Codon Skin cancers (BCC and SCC)

25 248 278

Mutation frequency

20

15 178 177

10 136 152

196

245 282 286 273

5

0 0

1864

20

40

60

80 100 120 140 160 180 200 220 240 260 280 300 320 340 360 380 400 Codon

and exerts multiple, complex functions, including protection of DNA integrity and cellular proofreading19. The former involves cell cycle arrest at G1 in order to facilitate the repair of damaged DNA prior to cell division. The pathway downstream of p53 involves upregulation of p21, which, in turn, inhibits cyclin-dependent kinases and subsequent phosphorylation of Rb protein (see Fig. 107.1). Underphosphorylated

Rb protein binds the transcription factor E2F and prevents the cell from entering into the S phase. Cellular proofreading involves apoptosis as a response to irreversible damage of genomic DNA and prevents survival of cells with severe genetic alterations. Sunburn cells in the epidermis represent apoptotic keratinocytes and can frequently be observed in normal skin subjected to sunburn.

The TP53 gene is the most frequently altered gene in human cancer. A majority of TP53 mutations are missense mutations leading to an altered amino acid sequence. Missense mutations are primarily found in the DNA-binding domain between codons 112 and 286 (see Fig. 107.5B,C). Mutations in the DNA-binding domain do not affect oligomerization; thus, mutant p53 can still form tetramers with normal p53 protein derived from the intact TP53 allele. The formed heterodimers are, however, incapable of binding to promoter sequences.

2 1

3

4

The addition of small peptides (corresponding to the C-terminal domain) can potentially disrupt the auto-inhibitory binding of the C-terminal region to the DNA-binding domain of the mutant heterodimers and thereby reactivate the function of mutated p53. This observation may eventually translate into a therapeutic intervention. At the time of writing, drugs that disrupt p53–MDM2 interactions are in clinical trials (www.clinicaltrials.gov). Clandestine proliferations of keratinocytes overexpressing p53 protein are evident in normal, chronically sun-exposed skin of Caucasians20. The pattern and degree of overexpression are distinctly different from the dispersed pattern of p53-immunoreactive keratinocytes following a single exposure to UV irradiation (Fig. 107.7). A recent study, using next-generation sequencing of sun-exposed versus shielded mid-life skin, revealed that persistent TP53 mutations had accumulated in 14% of epidermal cells in phenotypically normal skin, with no apparent evidence of a growth advantage21. Six percent of the mutated cells encoded for a truncated p53 protein. The authors estimated the accumulation of ~35 000 protein-altering TP53 mutations annually in the sun-exposed skin of a single individual, suggesting that UV-induced TP53 mutations are tolerated and not as hazardous as previously thought. Further evidence of the resilience of skin to the accumulation of somatic mutations was provided in a recent study of normal sunexposed eyelid skin. Two to 6 mutations per megabase of sequence from 74 cancer-associated genes per cell was observed21a. This mutation burden is similar to that observed in many other cancers.

STRUCTURE AND FUNCTION OF PATCHED Background A

2, 3

1, 4

B

Fig. 107.6 Structure of the p53 core domain tetramer bound to DNA. A A 20-bp segment of DNA (green) interacts with four core domains of p53 (labeled 1,2,3,4). The core tetramer is a dimer of dimers consisting of 1 + 2 (aqua) and 3 + 4 (light red). Four zinc atoms (purple circles) are also depicted. B En face view down the DNA helix axis. Adapted from Kitayner M, Rozenberg H, Rohs R, et al. Diversity in DNA  

recognition by p53 revealed by crystal structures with Hoogsteen base pairs. Nat Struct Mol Biol. 2010;17:423–9.

$

CHAPTER

107  Principles of Tumor Biology and Pathogenesis of BCCs and SCCs

Mutated TP53

The Hedgehog signaling pathway plays a critical role during normal development, regulating both proliferation and cell fate. Initially, patched and hedgehog genes were identified in Drosophila melanogaster, where members of this complex signaling pathway were found to act as segment polarity genes involved in embryonic development. Later on, it became evident that Hedgehog was also involved in driving tumorigenesis22. When screening candidate genes for the hereditary BCNS (Gorlin syndrome), the human homolog of the patched gene, PTCH1, was identified as a tumor suppressor gene associated with this syndrome23. The PTCH1 gene encodes a receptor that mediates Hedgehog signaling (Fig. 107.8). Later studies demonstrated that inactivating mutations in the PTCH1 gene are also common events in sporadic BCCs. Activating mutations in SMO, which encodes Smoothened, have also been detected in sporadic BCCs where the PTCH1 gene is intact. The significant cellular effects of Hedgehog signaling are mediated by proteins encoded by the GLI gene family. The human Hedgehog signaling pathway is complex, with three identified hedgehog genes (sonic hedgehog [SHH], Indian hedgehog [IHH] and desert hedgehog [DHH]), two PTCH genes (PTCH1 and PTCH2), and three GLI genes (GLI1, GLI2 and GLI3). The encoded proteins within these families are similar, although they display variations in expression levels in different cells and tissues as well as slightly

%

Fig. 107.7 p53 immunoreactivity. Photomicrographs of two different patterns of p53 immunoreactivity found in normal skin. A Dispersed pattern of p53 positivity representing a normal reactive response to DNA damage (e.g. single exposure to UVB). B Epidermal p53 clone representing a clonal expansion of morphologically normal keratinocytes with a TP53 mutation. The latter is seen in chronically sun-exposed skin. Of note, mutated p53 protein has an extended half-life as compared to wild-type protein (due to a less efficient MDM2/ubiquitin degradation pathway) and this property is used as a semiquantitative surrogate marker for altered p53 in immunohistochemical examination of tissue.  

1865

THE HEDGEHOG SIGNALING PATHWAY

SECTION

Neoplasms of the Skin

18

Unliganded Patched

A

B

Extracellular

Hedgehog signaling

C

Inactivating mutations in PTCH1

D

Activating mutations in SMO

Sonic Hedgehog (SHH)

N 2H

Smoothened activated

Patched COOH

SUFU

GLI

Inhibition of Smoothened by vismodegib or sonidegib Vismodegib or sonidegib

− Smoothened

E

Smoothened activated Dysfunctional Patched

GLI

GLI SUFU

Constitutively activated Smoothened

SUFU

− Activated Smoothened

SUFU

GLI

GLI

SUFU

Cytoplasm

Nucleus

GLI

GLI

GLI

GLI

GLI

PTCH

PTCH

PTCH

PTCH

PTCH

BCL2

Nucleus

BCL2

Nucleus

BCL2

Nucleus

BCL2

Nucleus

BCL2

Fig. 107.8 The Hedgehog signaling pathway. A Unbound Patched silences Smoothened (SMO) signaling. B As Hedgehog binds to its receptor Patched, the repression of SMO is removed and signals are transduced via GLI to the nucleus. C Inactivating mutations in PTCH lead to dysfunctional Patched and this simulates Hedgehog binding and results in constitutive activation of GLI and downstream target genes. D An activating mutation in SMO results in constitutive signaling to GLI and downstream target genes. Such mutations are detected in sporadic BCCs in which PTCH1 is intact. E Vismodegib and sonidegib are inhibitors of SMO that have been used to treat patients with BCNS as well as metastatic or locally advanced BCCs (see Ch. 108). At least 50% of advanced BCCs develop resistance to vismodegib, commonly via acquiring mutations in SMO.  

different modes of interactions. In the skin, the SHH pathway is responsible for maintaining the stem cell niche and controlling development of sebaceous glands and hair follicles24. In the next section, a simplified scheme using Hedgehog, Patched, Smoothened, and Gli as common denominators will be used to illustrate interactions and effects in this important pathway.

of PTCH1, thus creating a negative feedback loop. Other genes induced via the SHH–Patched signaling pathway include those that encode platelet-derived growth factor receptor-α (PDGFRA), the DNA-binding protein MYCN, β-catenin, members of the forkhead box (FOX) family, cyclins, and runt-related transcription factor 3, a nuclear effector of the TGF-β family.

PTCH1 Gene

Regulation of Patched

The human PTCH1 gene was cloned and identified in 1996. Positional cloning was used to search the region within 9q22.3 in order to identify the gene responsible for BCNS. The gene is 35 kb in length and consists of 23 exons. The first exon has three splice variants, 1, 1A and 1B. The different transcripts have been identified in human epidermis.

Knowledge about genes and molecules involved in SHH–Patched signaling has been obtained mainly by genetic analyses in Drosophila. The signaling pathway is well conserved, although with increasing complexity, from insects to vertebrates, including humans. The SHH–Patched signaling pathway induces transcription of PTCH1 itself, creating a negative feedback loop for PTCH1. Unbound Patched interacts with and suppresses signaling by the co-receptor SMO. SHH signaling accordingly induces transcription of target genes by opposing the repressive activity of Patched. In other words, when SHH binds to the receptor Patched, repression of SMO is relieved and downstream target genes are induced. In a simplified scheme (see Fig. 107.8B), secreted SHH proteins bind to the receptor protein Patched and upon binding to the ligand, Patched dissociates from its co-receptor Smoothened. Inactivating mutations of PTCH1 simulate SHH signaling due to the failure of mutated Patched protein to suppress SMO (see Fig. 107.8C). The loss of negative autoregulation leads to increased transcription of non-functional PTCH1 mRNA. In carcinogenesis, several lines of evidence (including experiments using transgenic mice) suggest that the critical cellular effect is stimulation of proliferation as opposed to differentiation, and this effect is mediated by upregulation of Gli.

PTCH1 Protein Product (Patched) The protein product of the human PTCH1 gene is the sonic hedgehog (SHH) receptor, which is an integral membrane protein with 12 predicted transmembrane regions and two large extracellular loops as well as a putative sterol-sensing domain. Patched protein normally binds and inhibits a seven-pass transmembrane G-protein receptor named Smoothened (SMO). SMO has been shown to be constitutively active when not bound to Patched (see Fig. 107.8).

Normal Function of Patched

1866

By controlling proliferation, differentiation and cell fate, the SHH– Patched signaling pathway is critical for early embryologic development, including formation of the neural tube, musculoskeletal system, hematopoietic cells, skin, and teeth. Mutations leading to dysfunctional proteins in the SHH pathway cause holoprosencephaly, a Cyclops-like phenotype with severe congenital abnormalities. Patched function is mediated via release of suppression of SMO. SMO signaling is then transduced and executed through the transcription factor Gli (see Fig. 107.8); atypical protein kinase C ι/λ phosphorylates and thereby activates Gli in the setting of unrepressed SMO, resulting in an increase in DNA binding and transcriptional activity24a. Active Gli serves as a transcription factor for GLI itself as well as inducing transcription

PTCH1 Mutations An early onset of multiple BCCs is a hallmark of BCNS, a rare autosomal dominant disease. The PTCH1 gene is mutated in patients with BCNS and thus strongly linked to the development of BCCs. Additional features that constitute BCNS include skeletal abnormalities, odontogenic keratocysts, macrocephaly, and palmoplantar pits. A majority of the germline mutations in PTCH1 are truncating, suggesting that

PTCH2 and SUFU Mutations There are only isolated reports of mutations in PTCH2 or SUFU leading to BCNS or atypical BCNS, respectively. PTCH2 is highly homologous to PTCH1, but BCNS due to mutations in PTCH2 have a milder or incomplete clinical presentation25,26. As shown in Fig. 107.8, SUFU (suppressor of fused homolog [Drosophila]) serves as a negative regulator of the SHH–Patched signaling pathway via binding to GLI.

PATHOGENESIS OF BCC Sun exposure and anatomic site appear to be of etiologic importance in the development of BCC. Intermittent, recreational sun exposure, more so than cumulative UV radiation, is a significant risk factor27. The development of BCCs is restricted to skin containing pilosebaceous units. The fact that BCCs commonly develop on the face, and in particular on the nose, suggests that anatomic site, i.e. specific areas of skin that contain a higher number of target progenitor cells, plays an important role. Analogous to other malignancies, BCC appears to have a capacity for infinite growth and spontaneous regression is not a feature. A challenge to the study of BCC tumor biology stems from the difficulty in establishing in vitro cultures of BCC cells from explanted tumors. Transplantation of BCC into athymic mice has been more successful, although extensive studies of long-term effects have been sparse. The development of transgenic mice as a model to study BCC has been rewarding, especially with regard to elucidating the role of different components of the SHH–Patched signaling pathway28. Determining the cell of origin in BCCs remains an area of active investigation, with some models implicating stem cells within the hair follicle versus cells of the interfollicular epidermis29.

Tumor progression Perhaps the most striking feature of BCCs is that tumors virtually never develop metastases. Although tumors can grow for many years in the setting of sustained exposure to mutagenic UV radiation, the tumors remain indolent. Non-aggressive forms of BCC, such as superficial and nodular BCC, appear to develop de novo and continue to grow without progressing to more aggressive forms of BCC. Aggressive forms of BCC, e.g. morpheaform BCC, also show an unusual genomic stability, with a persistent pattern of locally invasive growth and tissue destruction, but without progression to metastatic disease. This also holds true for BCCs that develop in xeroderma pigmentosum patients, where there are high numbers of unrepaired mutations. It is unclear why BCC cells are resistant to acquiring additional genetic hits leading to more autonomous growth.

Cancer BCC is a tumor with unique growth characteristics. It is dependent on a specific loose connective tissue stroma for its continued growth, and one hypothesis for the inability of a BCC to transform into a metastasizing tumor is an unconditional dependence on a stroma produced by dermal fibroblasts. In an experiment where autotransplantation of BCC with and without its cognate stroma was performed, it became evident that BCC devoid of its stroma failed to proliferate and instead differentiated into keratin-filled cysts30.

The loose connective tissue stroma that characteristically surrounds nests of BCC cells consists of dermal fibroblasts and thin collagen fibers. The cross-talk between tumor cells and mesenchymal cells of the cognate stroma simulates the epithelial–stromal interactions found in normal developing and adult cycling hair follicles. For example, the growth factor receptors for PDGF are upregulated in BCC stroma, whereas the ligand, PDGF, is expressed primarily in tumor cells. In morpheaform or infiltrative BCCs, the stroma is myofibroblast-rich as compared with nodular BCCs. These myofibroblasts secrete hepatocyte growth factor (HGF) which promotes invasion of epithelial cells via binding of HGF to c-Met, a tyrosine kinase receptor expressed in the epithelium of morpheaform BCCs. The invasive nature of BCCs can be explained in part by proteolytic activity of the tumor. Increased expression of enzymes such as metalloproteinases and collagenases, which degrade pre-existing dermal tissue and facilitate spread of tumor cells, can be found in both BCC cells and stromal cells. Microscopically, BCCs often appear as multicentric tumors. In superficial BCCs, nests of tumor cells connected to the basal cell layer of the overlying epidermis appear as discontinuous buds of tumor cells. More recent studies based on microdissection, gene amplification, and gene sequencing have shown that BCCs develop as a monoclonal proliferation consistent with a unicellular origin. Interestingly, BCCs often consist of subclones (Fig. 107.9). Using TP53 mutations as a marker for clonality, it was shown that different parts of a tumor share a common mutation but differ with respect to second, third or even fourth mutations within the two alleles of the TP53 gene31. Although BCC appears as a tumor with extraordinary genomic stability, a large number of tumors are aneuploid. Analyses of LOH have shown allelic loss of chromosome 9q, while LOH involving other chromosomes was observed infrequently32. Of note, the gene most often altered in BCCs is the PTCH1 gene, which is located on chromosome 9q. Two out of three BCCs show LOH and/or truncating mutations in the PTCH1 gene. In tumors where the PTCH1 gene is intact, other mutations such as activating mutations in SMO (up to 20%) have been detected. Accumulating data suggest that a sufficiently elevated expression level of Gli, by homozygous inactivation of PTCH1 or by activating mutations of SMO, in a responding cell is necessary and perhaps also sufficient to drive the formation of BCC. Constitutive SHH signaling has also been demonstrated to be required for growth of established BCCs (see Fig. 107.8)33. The second most common genetic alteration found in BCCs is point mutations in the TP53 gene. TP53 mutations appear early during carcinogenesis and at least 50% of BCCs have a mutated TP53 gene. The vast majority of TP53 mutations are missense mutations that carry a UV signature (see Ch. 86)34. In many BCCs, both TP53 alleles are affected by point mutations, unlike the more common combination of a point mutation and a deletion (LOH) observed in most other solid tumors. The role of TP53 mutations in the carcinogenesis of BCCs could be based on the expansion of the number of target cells, i.e. epidermal p53 clones, susceptible to transformation. Mutations in the CDKN2A (INK4A) locus, which encodes both p16 and p14ARF (see above), have also been detected in a smaller number of sporadic BCCs. In contrast to tumor suppressor genes (e.g. PTCH1, TP53), oncogenes appear to play a lesser role in the development of BCC. ras genes are the most studied oncogenes and the frequency of ras mutations in BCC has varied between 0 and 30%, usually within H-ras. Alterations in other oncogenes and tumor suppressor genes have only sporadically been recorded. Genome-wide association studies in the Icelandic population have revealed genetic susceptibility variants in the keratin 5 gene in patients with BCC35. Limitless replicative potential is essential for the malignant phenotype, and telomere maintenance is also evident in BCCs, due to high telomerase activity. Interestingly, BCCs express equal or higher levels of telomerase when compared to high-grade malignancies. The presence of intact DNA repair genes is also of critical importance. The detrimental effect of insufficient repair of UV-induced DNA damage is well illustrated in patients with xeroderma pigmentosum, who develop numerous BCCs at an early age.

CHAPTER

107  Principles of Tumor Biology and Pathogenesis of BCCs and SCCs

haploinsufficiency underlies the developmental abnormalities. Both alleles of PTCH1 are often inactivated in both familial and sporadic cases of BCC, as would be expected for a classic tumor suppressor gene. Most tumors where PTCH1 is inactivated display a truncating mutation in one allele and deletion of the other allele, i.e. loss of heterozygosity (LOH). Alternatively, point mutations in both alleles can occur in tumors without LOH at the PTCH1 locus. Constitutive activation of SHH signaling by either inactivating mutations in PTCH1 or activating mutations in SMO appear to be required, and possibly also sufficient, for development of BCC. Disruption of the SHH–Patched pathway has also been found in other tumors such as medulloblastoma, as well as ovarian and cardiac fibromas, which are common in patients with BCNS. In addition, PTCH1 mutations have been found in sporadic trichoepitheliomas, bladder carcinoma, and SCC of the esophagus. Mutational analysis has shown that two-thirds of reported mutations were truncating or affected splicing.

Metastasis Although BCCs virtually never metastasize, there have been a few reports in the literature of BCCs that developed metastases, and the

1867

BASAL CELL CARCINOMA – DEVELOPMENT OF SUBCLONES

SECTION

Neoplasms of the Skin

18

TP53 gene

TP53 gene

TP53 mutations

TP53 mutations

TP53 gene

TP53 gene

TP53 mutations

TP53 mutations

TP53 gene

TP53 mutations

Fig. 107.9 Basal cell carcinoma (BCC) – development of subclones. A common TP53 mutation (red cross) is found in different parts of the tumor. Despite indistinguishable morphology, different parts of individual BCCs have acquired additional mutations in the TP53 gene (blue, orange and green crosses). Boxes illustrate the two TP53 alleles. Note normal TP53 status (outlined in orange) in overlying epidermal keratinocytes.  

incidence has been estimated to be 1 : 1000 to 1 : 35 000. It appears as if these rare cases represent aggressive tumors with perineural spread of tumor cells. Lymph node metastasis followed by lung and bone metastasis is the most common progression. The diagnosis has been based on morphology, and the possibility that some of these cases represent poorly differentiated variants of SCCs cannot be excluded. In summary, BCC is a common, locally invasive tumor of the skin for which UV radiation and alterations in the PTCH1 gene are important etiologic factors. BCC is stroma-dependent for its growth, arises without precursors, and shows continuous growth without progression to metastatic disease.

PATHOGENESIS OF SCC

1868

UV solar radiation is also a major etiologic factor in the development of cutaneous SCC. The cumulative dose of UV radiation received over time is a significant risk factor, in contrast to the more complex relationship between BCC and sun exposure early in life or cutaneous melanoma and sunburns27. SCC of the skin is a “classic cancer”, as it has precursor lesions, tumor progression, and the potential to develop metastatic disease. SCC can develop in different regions of the skin as well as other sites lined by squamous epithelia, e.g. mouth, esophagus, vagina. The biology of cutaneous SCC differs in part from that of SCCs that arise in other tissues. In particular, SCC in areas of chronically sun-exposed skin exhibits a relatively indolent behavior and the development of metastases is infrequent (less than 5% overall). There is a strong correlation between tumor thickness and metastasis (2.1–6 mm, 4% metastasize; >6 mm, 16% metastasize)36. Secondary risk factors for metastasis included immunosuppression and location on the lips or the ear. SCCs arising in the anogenital region are also more aggressive, with a higher risk of metastasis. A recent study identified additional high-risk factors including tumor diameter ≥2 cm, poorly differentiated histology, and perineural invasion ≥0.1 mm37.

Precursors The current opinion regarding cutaneous SCC is that the cancer is derived from a single transformed cell of keratinocytic lineage. The precise genetic events and number of mutations required for malignant transformation are unknown. However, cutaneous SCC develops through the addition of genetic alterations leading to a selective growth advantage. In this scheme of events, several stages can be defined. An attractive model (supported by studies in hairless mice) includes epidermal p53 clones as forerunners to squamous cell dysplasia (Fig. 107.10)38. According to the dogma, slight dysplasia precedes moderate and severe dysplasia (which is seen in SCC in situ) and invasive SCC then develops from carcinoma in situ. Further genetic alterations and selection leads to the final stage, where a locally invasive SCC gives rise to metastases in regional lymph nodes and distant organs. Clinical precursor lesions associated with cutaneous SCC include actinic keratoses and Bowen disease. Microscopically, actinic keratoses display signs of chronic sun damage, i.e. solar elastosis and a slight to severe grade of squamous cell dysplasia within the epidermis, especially in its lowermost portions. Bowen disease also displays squamous cell dysplasia, which is full-thickness and often high-grade. Actinic keratoses are exceedingly common in chronically sun-exposed skin of older Caucasians. Lesions occur primarily on the face, hairless scalp, dorsal aspects of the hands and forearms, and helices of the ears (primarily in men). The risk for an individual actinic keratosis to progress into an invasive cancer is low, probably less than 1 in 1000 per year. The risk of SCC in situ progressing to invasive cancer is considered to be higher.

Cancer UV solar radiation is accepted as a major risk factor for SCC. Numerous experiments using chemical multistage carcinogenesis models have been performed in mice, yielding SCC-like tumors. A typical protocol consists of a single application of an initiating compound, e.g. 7,12-dimethylbenz[a]anthracene (DMBA), which leads to irreversible

THE MULTISTEP DEVELOPMENT OF SQUAMOUS CELL CARCINOMA

CHAPTER

Normal skin

Epidermal TP53 clone

TP53 mutation

UV-induced DNA damage Manifest mutation

Second TP53 mutation

Resistance to UV-induced apoptosis Clonal expansion

Metastasis of squamous cell cancer Lymph node

Actinic keratosis

Additional mutations Selection for growth advantage

Invasive squamous cell cancer

Squamous cell cancer in situ

Lung

Tumor progression Metastatic properties Additional genetic alterations Acquisition of metastatic capacity

Tumor progression Invasive properties Additional genetic alterations Acquisition of invasive capacity

Additional genetic alterations

Principles of Tumor Biology and Pathogenesis of BCCs and SCCs

107 

Proliferation of neoplastic clone and genomic instability

Fig. 107.10 The multistep development of squamous cell carcinoma. UV irradiation of normal skin induces mutations in keratinocytes and facilitates clonal expansion of keratinocytes with a mutated TP53 gene. Additional mutations (including a second TP53 mutation) that affect genes controlling proliferation, cell migration and cell death provide for selective growth advantage and cause genomic instability. The final result is metastatic tumor cells, capable of growing in regional lymph nodes and internal organs.  

activating mutations in H-ras genes within basal cells of the epidermis. In a second step, repetitive doses of a tumor-promoting agent, e.g. 12-O-tetradecanoylphorbol 13-acetate (TPA), induces a hyperproliferative response. In part through epigenetic mechanisms, this leads to the development of squamous cell papillomas. Conversion of benign papillomas into malignant SCCs then involves a number of chromosomal and genetic alterations required for the acquisition of the malignant phenotype. A limitation of the chemical carcinogenesis model is that it is different from UV-induced carcinogenesis, in particular H-ras is not implicated as a key oncogene in sporadic human cutaneous SCC. A second murine skin carcinogenesis model is UVB-induced SCC in the hairless, SKH-1 mouse. Skin tumors in this model have a high frequency of TP53 mutations and a low incidence of Ras mutations. Invasive SCCs can have different degrees of differentiation. Highly differentiated tumors show features of keratinization and often invade the dermis with a broad rounded tumor margin. Papillomatous extensions and cords of slightly atypical squamous epithelia grow down into the dermis. Verrucous SCC, which very rarely metastasizes, is considered a special variant of highly differentiated SCC. Poorly differentiated SCCs show more anaplastic cytologic features and the squamous cell phenotype can sometimes only be verified via immunohistochemistry with anti-keratin antibodies. In general, poorly differentiated SCC exhibits a higher grade of malignancy. However, biologic behavior can rarely be predicted by the degree of differentiation alone. SCC is dependent on a supportive stroma, as are all other solid tumors, and a vasculature induced by angiogenic signals is needed for the tumor to enlarge. Unlike the stroma surrounding a BCC, the SCC stroma is considered nonspecific and cell–cell interactions between tumor cells and stromal cells are not well characterized. SCC thus has the potential to grow at sites distant from the primary tumor.

Alterations in the TP53 gene are the most common genetic abnormalities found in actinic keratoses, SCC in situ, and invasive SCC, and dysregulation of p53 pathways appears to be an early event in carcinogenesis of SCC. In typical cases, one allele contains a missense point mutation with a UV signature at dipyrimidine sites, while the remaining TP53 allele is deleted. Studies utilizing TP53 mutations as a clonality marker have suggested a direct relationship between actinic keratoses, SCC in situ, and invasive SCC. By studying individual patients with lesions (e.g. SCC) adjacent to various morphologic entities (e.g. actinic keratoses), a genetic link has been found between coexisting lesions. The conclusion from these studies is that coexisting lesions represent different stages in SCC development. One possible role for early TP53 mutations in SCCs (analogous to the situation in BCCs) is resistance to apoptosis, allowing for clonal expansion at the expense of neighboring keratinocytes containing a normal (wild-type) TP53 gene. Another common genetic aberration is mutation or epigenetic silencing of the CDKN2A locus, with the most frequent mechanism of inactivation being promoter methylation. The frequency of activating mutations in the oncogene ras ranges from 10–50%, depending on the experimental technique used and the site of the tumors analyzed. Amplification of the c-Myc oncogene has been reported in up to 50% of SCCs from immunosuppressed patients, often as a result of amplification of the chromosomal locus39. Unlike the case in BCC, where LOH is mainly restricted to chromosome 9q, actinic keratoses and SCCs demonstrate more widespread genomic copy number variations with deletions and gains in several chromosomes. A more recent study using high-resolution single nucleotide polymorphism microarrays of 60 SCC tumors showed that the most frequent aberrations were LOH at 3p and 9p, observed in 65% and 75% of tumors, respectively40. Three tumors had homozygous deletions within the fragile histidine triad (FHIT) gene at 3p14 and

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Neoplasms of the Skin

18

homozygous and heterozygous deletions were also found in the protein tyrosine phosphatase receptor type D (PTPRD) gene at 9p23 in 9 of 60 tumors. This study also revealed uniparental disomy (UPD) as a mechanism of copy number-neutral LOH in SCC. Of note, UPD results in loss of one allele and subsequent duplication of the remaining allele (see Ch. 54). Poorly differentiated tumors had a greater number of chromosomal aberrations than well-differentiated tumors40. Loss-of-function mutations in NOTCH1 or NOTCH2 have been identified in 75% of cutaneous SCCs41. These genes encode cellular receptors whose signaling pathways interact with that of the Wnt/β-catenin pathway (see Fig. 55.6). In addition, ~20% of cutaneous SCCs were found to have point mutations in KNSTRN42. The latter encodes kinastrin/SKAP, a kinetochore protein that is important in chromosome segregation. When selective BRAF inhibitors are used alone, i.e. without concurrent MEK inhibitors, to treat advanced malignancies (see Ch. 113), up to 30% of patients can develop SCCs and keratoacanthomas. As noted above, mutations in RAS family member genes are observed in the minority of sporadic human SCCs (3–30%). In contrast, the majority (60%) of BRAF inhibitor-associated SCCs have RAS mutations43. A paradoxical activation of the MAPK pathway is thought to occur when cells, e.g. keratinocytes, with wild-type BRAF are exposed to BRAF inhibitors, leading to proliferation and the formation of SCCs.

protein have been reported. Additional mutational analysis found that keratoacanthomas bear mutations in known drivers of SCC, including NOTCH1, NOTCH2, TP53 and PI3CA, but in regressing keratoacanthomas no mutations were detected in any of these known driver genes44b. Although microsatellite instability and LOH have been reported in keratoacanthomas from patients with the mismatch repair-deficient and cancer-prone Muir–Torre syndrome, sporadic keratoacanthomas appear to be more genetically stable. Ferguson–Smith syndrome, an autosomal dominant condition characterized by multiple keratoacanthomas, is due to mutations in the TGFBR1 gene45.

Summary

Li–Fraumeni Syndrome

In summary, SCC arising in chronically sun-exposed skin is a common tumor for which cumulative sun exposure is an important etiologic factor. SCC arises through a series of stages involving precursor lesions, such as actinic keratoses, and in high-risk cases results in metastasis to regional lymph nodes and elsewhere.

RELATED DISEASES Adnexal Tumors Tumors that mimic cutaneous adnexal differentiation display a multitude of different phenotypes (see Ch. 111). A majority of these tumors are benign, although malignant counterparts do exist. The degree of differentiation allows these tumors to be distinguished from BCC and SCC. An organoid nevus, e.g. nevus sebaceus of Jadassohn, represents a cutaneous malformation that includes pilosebaceous structures. These lesions most often arise from postzygotic mutations in either HRAS or KRAS and harbor an increased risk for the development of other adnexal tumors (e.g. trichoblastoma) and less so BCC44.

Keratoacanthoma Keratoacanthomas represent tumors characterized by the proliferation of atypical, highly differentiated squamous epithelia. Clinically, and even more so microscopically, keratoacanthomas resemble SCC. Clear distinction from a highly differentiated SCC is often impossible. However, the clinical course is usually benign and lesions are believed to undergo spontaneous regression if not excised. Expression analysis of keratoacanthomas (versus normal skin) revealed an upregulation of genes involved in cell death and apoptosis pathways, which may represent the molecular basis for the commonly observed regression44a. Sporadic cases with TP53 mutations and/or overexpression of p53

Xeroderma Pigmentosum Xeroderma pigmentosum (XP) represents a family of DNA repair syndromes, most of which are caused by inherited defects in nucleotide excision repair (NER) genes (see Ch. 86), resulting in a complex skin pathology including lentigines, epidermal hyperplasias, BCCs, SCCs, and cutaneous melanomas triggered by exposure to the sun. Due to the deficient DNA repair, the rate at which skin cancers develop in young XP patients is increased at least 1000-fold. The variant form of XP is caused by mutations in the gene that encodes DNA polymerase eta (POLη) which has been shown to act like a “molecular splint” to stabilize damaged DNA46.

The Li–Fraumeni syndrome is a rare familial cancer syndrome where germline mutations of the TP53 gene play an important role. The syndrome is characterized by an autosomal dominant inheritance pattern and affected individuals display an early onset of various tumors, including breast cancer, brain tumors, osteosarcoma, and leukemia. Excessive genomic DNA copy number variation has been described in this syndrome, accounting for variation in phenotypes in affected families. However, skin cancer does not occur as commonly as expected given that TP53 mutations are frequently observed in BCCs and SCCs.

Basal Cell Nevus Syndrome The most common inherited disorder associated with BCCs is the BCNS (see above); it is transmitted in an autosomal dominant fashion. Affected individuals have a wide range of developmental anomalies, including skeletal abnormalities, craniofacial dysmorphism, and macrocephaly. Multiple BCCs with an early onset are a hallmark of the syndrome which also includes features such as odontogenic keratocysts, palmoplantar pits, and calcification of the falx cerebri. In addition to BCCs, patients have an increased incidence of medulloblastomas, meningiomas, ovarian fibromas and ovarian cancer, as well as cardiac fibromas. Germline inactivating mutations in the PTCH1 gene are found in the vast majority of patients with this syndrome.

Bazex Syndrome Bazex syndrome is a rare genodermatosis characterized by follicular atrophoderma and the early onset of multiple BCCs. The responsible gene has been linked to Xq24–q27 and there is no male-to-male transmission. It should not be confused with acrokeratosis paraneoplastica, also known as Bazex syndrome, which occurs most commonly in the setting of carcinomas of the upper aerodigestive tract (see Ch. 53).

REFERENCES

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1. Kinzler KW, Vogelstein B. Life (and death) in a malignant tumour. Nature 1996;379:19–20. 2. Loeb LA, Bielas JH, Beckman RA. Cancers exhibit a mutator phenotype: clinical implications. Cancer Res 2008;68:3551–7. 3. Vogelstein B, Fearon ER, Hamilton SR, et al. Genetic alterations during colorectal-tumor development. N Engl J Med 1988;319:525–32. 4. Hanahan D, Weinberg RA. The hallmarks of cancer. Cell 2000;100:57–70. 5. Malumbres M, Barbacid M. Cell cycle, CDKs and cancer: a changing paradigm. Nat Rev Cancer 2009;9: 153–66. 6. Wood LD, Parsons DW, Jones S, et al. The genomic landscapes of human breast and colorectal cancers. Science 2007;318:1108–13.

7. Beroukhim R, Mermel CH, Porter D, et al. The landscape of somatic copy-number alteration across human cancers. Nature 2010;463:893–8. 8. Bignell GR, Greenman CD, Davies H, et al. Signatures of mutation and selection in the cancer genome. Nature 2010;463:899–905. 9. Land H, Parada LF, Weinberg R. Cellular oncogenes and multistep carcinogenesis. Science 1983;222:771–8. 10. Turner N, Grose R. Fibroblast growth factor signalling: from development to cancer. Nat Rev Cancer 2010;10:116–29. 11. Dykxhoorn DM. MicroRNAs and metastasis: little RNAs go a long way. Cancer Res 2010;70:6401–6. 12. Cowin PA, Anglesio M, Etemadmoghadam D, et al. Profiling the cancer genome. Annu Rev Genomics Hum Genet 2010;11:133–59.

13. Letai AG. Diagnosing and exploiting cancer’s addiction to blocks in apoptosis. Nat Rev Cancer 2008;8:121–32. 14. Murnane JP. Telomere loss as a mechanism for chromosome instability in human cancer. Cancer Res 2010;70:4255–9. 15. Alison MR, Islam S, Wright NA. Stem cells in cancer: instigators and propagators? J Cell Sci 2010;123:2357–68. 16. Lichtenberger BM, Tan PK, Niederleithner H, et al. Autocrine VEGF signaling synergizes with EGFR in tumor cells to promote epithelial cancer development. Cell 2010;140:268–79. 17. Egeblad M, Nakasone ES, Werb Z. Tumors as organs: complex tissues that interface with the entire organism. Dev Cell 2010;18:884–901.

29. Epstein EH Jr. Mommy – where do tumors come from? J Clin Invest 2011;121:1681–3. 30. van Scott EJV, Reinertson RP. The modulating influence of stromal environment on epithelial cells studied in human autotransplants. J Invest Dermatol 1961;36:109–17. 31. Pontén F, Berg C, Ahmadian A, et al. Molecular pathology in basal cell cancer with p53 as a genetic marker. Oncogene 1997;15:1059–67. 32. Teh MT, Blaydon D, Chaplin T, et al. Genomewide single nucleotide polymorphism microarray mapping in basal cell carcinomas unveils uniparental disomy as a key somatic event. Cancer Res 2005;65:8597–603. 33. Hutchin ME, Kariapper MS, Grachtchouk M, et al. Sustained Hedgehog signaling is required for basal cell carcinoma proliferation and survival: conditional skin tumorigenesis recapitulates the hair growth cycle. Genes Dev 2005;19:214–23. 34. Brash DE, Rudolph JA, Simon JA, et al. A role for sunlight in skin cancer: UV-induced p53 mutations in squamous cell carcinoma. Proc Natl Acad Sci USA 1991;88:10124–8. 35. Stacey SN, Sulem P, Masson G, et al. New common variants affecting susceptibility to basal cell carcinoma. Nat Genet 2009;41:909–14. 36. Brantsch KD, Meisner C, Schönfisch B, et al. Analysis of risk factors determining prognosis of cutaneous squamous-cell carcinoma: a prospective study. Lancet Oncol 2008;9:713–20. 37. Karia PS, Jambusaria-Pahlajani A, Harrington DP, et al. Evaluation of American Joint Committee on Cancer, International Union Against Cancer, and Brigham and Women’s Hospital tumor staging for cutaneous squamous cell carcinoma. J Clin Oncol 2014;32: 327–34. 38. Kramata P, Lu YP, Lou YR, et al. Patches of mutant p53-immunoreactive epidermal cells induced by chronic UVB irradiation harbor the same p53 mutations as squamous cell carcinomas in the skin of hairless SKH-1 mice. Cancer Res 2005;65:3577–85.

39. Pelisson I, Soler C, Chardonnet Y, et al. A possible role for human papillomaviruses and c-myc, c-Ha-ras, and p53 gene alterations in malignant cutaneous lesions from renal transplant recipients. Cancer Detect Prev 1996;20:20–30. 40. Purdie KJ, Harwood CA, Gulati A, et al. Single nucleotide polymorphism array analysis defines a specific genetic fingerprint for well-differentiated cutaneous SCCs. J Invest Dermatol 2009;129: 1562–8. 41. Wang NJ, Sanborn Z, Arnett KL, et al. Loss-of-function mutations in Notch receptors in cutaneous and lung squamous cell carcinoma. Proc Natl Acad Sci USA 2011;108:17761–6. 42. Lee CS, Bhaduri A, Mah A, et al. Recurrent point mutations in the kinetochore gene KNSTRN in cutaneous squamous cell carcinoma. Nat Genet 2014;46:1060–2. 43. Su F, Viros A, Milagre C, et al. RAS mutations in cutaneous squamous-cell carcinomas in patients treated with BRAF inhibitors. N Engl J Med 2012;366:207–15. 44. Groesser L, Herschberger E, Ruetten A, et al. Postzygotic HRAS and KRAS mutations cause nevus sebaceous and Schimmelpenning syndrome. Nat Genet 2012;44:783–7. 44a.  Ra SH, Su A, Li X, et al. Keratoacanthoma and squamous cell carcinoma are distinct from a molecular perspective. Mod Pathol 2015;28:799–806. 44b.  Lim YH, Fisher JM, Bosenberg MW, et al. Keratoacanthoma shares driver mutations with cutaneous squamous cell carcinoma. J Invest Dermatol 2016;136:1737–41. 45. Goudie DR, D’Alessandro M, Merriman B, et al. Multiple self-healing squamous epithelioma is caused by a disease-specific spectrum of mutations in TGFBR1. Nat Genet 2011;43:365–9. 46. Silverstein TD, Johnson RE, Jain R, et al. Structural basis for the suppression of skin cancers by DNA polymerase eta. Nature 2010;465:1039–43.

CHAPTER

107  Principles of Tumor Biology and Pathogenesis of BCCs and SCCs

18. Colegio OR, Chu NQ, Szabo AL, et al. Functional polarization of tumour-associated macrophages by tumour-derived lactic acid. Nature 2014;513:559–63. 19. Lane DP. p53, guardian of the genome. Nature 1992;358:15–16. 20. Jonason AS, Restifo RJ, Spinelli HM, et al. Frequent clones of p53-mutated keratinocytes in normal human skin. Proc Natl Acad Sci USA 1996;93:14025–9. 21. Ståhl PL, Stranneheim H, Asplund A, et al. Sun-induced nonsynonymous p53 mutations are extensively accumulated and tolerated in normal appearing human skin. J Invest Dermatol 2011;131:504–8. 21a.  Martincorena I, Roshan A, Gerstung M, et al. Tumor evolution. High burden and pervasive positive selection of somatic mutations in normal human skin. Science 2015;348:880–6. 22. Epstein EH. Basal cell carcinomas: attack of the hedgehog. Nat Rev Cancer 2008;8:743–54. 23. Hahn H, Wiking C, Zaphiropoulos PG, et al. Mutations of the human homolog of Drosophila patched in the nevoid basal cell carcinoma syndrome. Cell 1996;85:841–51. 24. Blanpain C, Fuchs E. Epidermal homeostasis: a balancing act of stem cells in the skin. Nat Rev Mol Cell Biol 2009;10:207–17. 24a.  Atwood SX, Li M, Lee A, et al. GLI activation by atypical protein kinase C ι/λ regulates the growth of basal cell carcinomas. Nature 2013;494:484–8. 25. Fan Z, Li J, Du J, et al. A missense mutation in PTCH2 underlies dominantly inherited NBCCS in a Chinese family. J Med Genet 2008;45:303–8. 26. Fujii K, Ohashi H, Suzuki M, et al. Frameshift mutation in the PTCH2 gene can cause nevoid basal cell carcinoma syndrome. Fam Cancer 2013;12:611–14. 27. Armstrong BK, Kricker A. The epidemiology of UV induced skin cancer. J Photochem Photobiol B 2001;63:8–18. 28. Fan H, Oro AE, Scott MP, Khavari PA. Induction of basal cell carcinoma features in transgenic human skin expressing Sonic Hedgehog. Nat Med 1997;3:788–92.

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Actinic Keratosis, Basal Cell Carcinoma, and Squamous Cell Carcinoma H. Peter Soyer, Darrell S. Rigel and Erin McMeniman

Chapter Contents Actinic keratosis and squamous cell carcinoma . . . . . . . . . . . 1876 Basal cell carcinoma . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1884

Synonyms:  ■ Solar keratosis and senile keratosis are non-preferred

synonyms for actinic keratosis (solar keratosis is abbreviated to SK, causing confusion with seborrheic keratosis) ■ Bowen disease: squamous cell carcinoma in situ, intraepidermal carcinoma ■ Basal cell epithelioma and rodent ulcer are antiquated synonyms for basal cell carcinoma ■ Basal cell nevus syndrome: nevoid basal cell carcinoma syndrome, Gorlin syndrome, Gorlin–Goltz syndrome

Key features ■ Keratinocyte carcinoma, also referred to as non-melanoma skin cancer (NMSC), represents the most common malignancy among Caucasians ■ The major risk factor for BCCs and SCCs is exposure to UVR; other factors include exposure to ionizing radiation, arsenic or organic chemicals, human papilloma virus infection, immunosuppression, and genetic predisposition ■ Prevention efforts are aimed at lowering incidence and morbidity via educational programs and sun protection campaigns ■ If neglected or inappropriately managed, skin cancer can cause significant morbidity and even death ■ Surgery remains a mainstay of treatment, but additional modalities include topical chemotherapy and immunomodulators, photodynamic therapy, and drugs that address genetic defects

INTRODUCTION Keratinocyte carcinomas, specifically basal cell carcinoma (BCC) and squamous cell carcinoma (SCC), represent the most frequently observed malignancy among Caucasians. In individuals with fair skin, approximately 75–80% of these malignancies are BCCs and up to 25% are SCCs1. The incidence of both continues to rise, leading to an increasing burden of disease.

HISTORY

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In 1775, Sir Percivall Pott noted an etiologic relationship between SCC and chimney soot exposure in his short treatise Chirurgical Observations Relative to the Cancer of the Scrotum. During the Industrial Revolution, links to arsenic, coal tar, shale oil, and creosote were also identified. In the late 1800s, Paul Unna noted a connection to UVR, when he described skin cancer development in chronically sun-exposed sites in sailors. Evidence of the basal cell nevus syndrome (BCNS), consisting of jaw cysts, syndactyly and bifid ribs, has been identified in Egyptian mummies almost 4000 years old. In the 1850s, Lebert first used the

term “rodent ulcer” to describe untreated BCCs of long duration. Several years later, Sir Jonathan Hutchinson published a review of 42 cases of BCCs, identifying the tumor as a single entity with many different clinical and histopathologic forms. Krompecher first suggested that a BCC arose from the cells of the basal layer of the epidermis, but there were additional theories regarding the site of origin of this tumor, including from the hair follicle and other adnexal structures.

EPIDEMIOLOGY Keratinocyte carcinomas occur worldwide in all races. It is estimated that ~5.5 million occurred in ~3.3 million individuals in the US in 20122. There are more skin cancers in the US population than there are all other cancers combined and it is estimated that one in five Americans will develop skin cancer during their lifetime3 (over 95% will be NMSC). The most important factor related to development of these neoplasms appears to be skin phenotype (Table 108.1)4–10, but other factors also play a significant role. As an example, the incidence is about ten times higher in white versus Hispanic men and five times higher in white versus Hispanic women11. The exact incidence of BCCs and SCCs may be difficult to determine due to issues such as diagnostic accuracy and diagnostic criteria (e.g. differentiation between actinic keratoses and SCC in situ). In addition, deriving precise data is hampered by the fact that these neoplasms are not routinely included in state cancer registries and they are often treated in private offices. The average amount of annual UVR correlates with the incidence of skin cancer. There is also a direct relationship between the incidence and latitude, in that the closer individuals are to the equator, the greater their exposure to UVR. In Australia, in 2002, the cumulative risk by age 70 years of having at least one BCC or SCC was 70% for men and 58% for women. Incidence also increases with age, with a sharp increase in BCCs in men after the age of 60 years. In those under 40 years of age, the majority of NMSC is found in women, but, by age 80, the incidence in men exceeds that in women by a 2–3 : 1 ratio11. Actinic keratoses (AKs) are most often found in fair-skinned individuals, but can be seen in all races. AKs are so common that it has been estimated that currently up to 12% of individuals in the US have them12. Over 80% of AKs occur in sites with the most cumulative sun exposure, e.g. the bald scalp, superior helices of the ears, face, dorsal hands, extensor forearms. Risk factors include skin phototypes I and II, significant cumulative sun exposure, a prior history of AKs, increasing age, immunosuppression, and male gender13. AKs are also markers for an increased risk of developing invasive SCC14, but the rates of transformation are low and difficult to assess (see below)15. The demographics of SCC are similar to those of AKs, with the majority of SCC occurring on the head, neck, upper extremities16, or shins. In light-skinned populations, the degree of UV exposure is related to SCC development while chronic irritation or injury can play a role in all populations. SCC is found more frequently in men (3 : 1 male : female) and the incidence increases significantly after age 60 years11. The incidence of SCC has been rising worldwide in all age groups over the last several decades at an estimated 3–10% per year, with >400 000 cases of invasive SCC diagnosed annually in the US17. Similar incidence trends have been noted worldwide. Weinstock18 reported an age-adjusted mortality rate for confirmed cases of SCC in Rhode Island of 0.26/100 000. SCC-associated

Tumors composed of keratinocytes, both premalignant and malignant, account for significant morbidity and some mortality. Primary and secondary prevention efforts, from public health awareness campaigns and improved protection against UVR-induced skin damage to screening of high-risk individuals, can have a positive impact. Key elements of clinical care include: (1) identification of patients at increased risk for the development of actinic keratoses (AKs), basal cell carcinomas (BCCs), and squamous cell carcinomas (SCCs) who require screening; (2) recognition of the clinical features, including dermoscopic ones, of early skin cancer; (3) knowledge of appropriate biopsy techniques and the histopathology of cutaneous carcinomas; and (4) counseling regarding changes in behavior that lead to a reduction in exposure to UVR. Once the diagnosis is established, treatment options vary from observation to field treatments in the case of AKs and destruction to surgical excision with margin control for BCCs and SCCs. More recently, oral medications for advanced or metastatic BCCs have been introduced that take advantage of insights into signal transduction pathways.

keratinocyte carcinoma, skin cancer, actinic keratosis, basal cell carcinoma, superficial basal cell carcinoma, nodular basal cell carcinoma, morpheaform basal cell carcinoma, fibroepithelial basal cell carcinoma, squamous cell carcinoma, Bowen disease, non-melanoma skin cancer, verrucous carcinoma, keratoacanthoma, 5-fluorouracil, imiquimod, pigmented actinic keratosis, vismodegib, sonidegib, basal cell nevus syndrome, basosquamous carcinoma

CHAPTER

108 Actinic Keratosis, Basal Cell Carcinoma, and Squamous Cell Carcinoma

ABSTRACT

non-print metadata KEYWORDS:

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CHAPTER

Lightly pigmented individuals

Darkly pigmented individuals

NMSC – annual incidence per 100 000

230

3.4

BCC : SCC ratio

4 : 1

1.1 : 1

BCC male : female ratio

1.5 : 1

1.3 : 1

SCC male : female ratio

2 : 1 to 5 : 1

1.3 : 1

% of SCCs developing in scars and chronic non-healing ulcers

2× compared with women).

RISK FACTORS FOR THE DEVELOPMENT OF BASAL CELL CARCINOMAS (BCCs) AND SQUAMOUS CELL CARCINOMAS (SCCs)

SCC

BCC

Environmental exposures UV exposure

+

+

Other exposures to UV light (PUVA, tanning beds)

+

+

Ionizing radiation

+

+

Chemicals, including arsenic, mineral oil, coal tar, soot, mechlorethamine (nitrogen mustard), polychlorinated biphenyls, 4,4′ bipyridyl, psoralen (plus UVA)33

+

+

Human papillomavirus (HPV)

+

(+)

Cigarette smoking

+

Pigmentary phenotype Fair skin, always burns, never tans

+

+

Freckling

+

+

Red hair

+

+

Genetic syndromes Xeroderma pigmentosum

+

+

Oculocutaneous albinism

+

+

Epidermodysplasia verruciformis

+

(+)

Dystrophic epidermolysis bullosa (primarily recessive)

+

Ferguson–Smith syndrome

+

Muir–Torre syndrome

+*

+*

Basal cell nevus syndrome

+

Bazex–Dupré–Christol and Rombo syndromes

+

Predisposing clinical settings Chronic non-healing wounds

+

Longstanding discoid lupus erythematosus, lichen planus (erosive), or lichen sclerosus

+

Porokeratosis (especially linear)

+

Nevus sebaceus

+

+†

Immunosuppression Organ transplantation

+

+

Other (e.g. chronic lymphocytic leukemia treated with fludarabine, AIDS patients with HPV infection)

+

(+)

*† Both SCCs (keratoacanthoma type) and BCCs typically have sebaceous differentiation. More often trichoblastomas.

Table 108.2 Risk factors for the development of basal cell carcinomas (BCCs) and squamous cell carcinomas (SCCs).  

RISK FACTORS (Table 108.2)

and animal studies. There is, however, a difference in the type of UV exposure (see Table 108.2). For BCCs, intermittent intense episodes of UV exposure and sunburns at any age appear to increase risk, whereas cumulative long-term UV exposure and childhood sunburns increase the risk for developing SCCs and AKs22,23. Sun exposure early in life appears to have a greater influence on subsequent skin cancer risk than at a later age. For example, individuals born in countries with high ambient UV radiation such as Australia have significantly higher incidence rates of BCC and SCC as compared to those with a similar genetic background (e.g. British, northern Europeans) who migrated to these locales later in life from countries with lower ambient UV radiation22,24,25.

Environmental Exposures

Indoor tanning usage

PATHOGENESIS See Chapter 107.

Ultraviolet radiation UV exposure is the predominant cause of BCC and cutaneous SCC as evidenced by migrant studies, the correlation of incidence to latitude,

108 Actinic Keratosis, Basal Cell Carcinoma, and Squamous Cell Carcinoma

INFLUENCE OF SKIN COLOR ON EPIDEMIOLOGY OF NMSC AND CUTANEOUS MELANOMA

Several studies have demonstrated an increased risk for the development of BCCs and SCCs in those who are exposed to artificial sources of UV radiation. Intentional tanning has been shown to increase the

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risk of SCC development26 and Karagas et al.27 demonstrated that any use of tanning devices was associated with odds ratios of 2.5 for SCC and 1.5 for BCC, even after adjustment for history of sunburns, sunbathing, and sun exposure. In response to these findings, many countries have passed legislation aimed at regulating indoor tanning facilities, including banning minors. Notably, Australia has actually completely banned this commercial industry28.

Therapeutic UVR exposure Individuals with psoriasis have been shown to be at increased risk for the development of keratinocyte carcinomas. While long-term follow-up of psoriasis patients who underwent UVR plus tar (Goeckerman) therapy found no increased risk, long-term PUVA therapy was associated with a significant, dose-related risk of SCC development (adjusted relative risk = 8.6 for an accumulated exposure of between 100 and 337 treatments)29. With prolonged therapy, a slightly increased risk for BCC development was noted as well. In addition to the direct effects of PUVA, PUVA-induced immunosuppression may also play a role.

Ionizing radiation Exposure to ionizing radiation leads to a threefold increased risk for BCC and SCC30. The risk is in proportion to the radiation dose. Larger fractionated doses (>12–15 Gy) are thought to be necessary to induce tumor formation, so the risk with a given total dose may be less if a larger number of smaller fractionated doses are given. Most SCCs and BCCs that arise after exposure to ionizing radiation do so after a long latency period of up to several decades, with most tumors appearing ~20 years after the initial exposure. Treatment of tinea capitis with radiation (prior to the discovery of effective systemic antifungal medications) has been linked to the development of multiple BCCs. In a study of 2224 children given X-ray therapy for tinea capitis (compared with a control group of 1380 tinea capitis patients given only topical medications), the relative risk for developing BCC of the head and neck among irradiated Caucasians was 3.631. Patients with BCNS are exquisitely sensitive to ionizing radiation and it should be avoided if possible (see below).

Occupational risk factors Persons with outdoor occupations have a higher risk of developing skin cancer. Airline pilots, who are exposed to ionizing radiation at flight altitudes, have been shown to have an elevated risk for both BCC and SCC32. Other occupations associated with an increased risk for NMSC include agricultural workers, sailors, locomotive engineers, and textile workers.

Chemical exposures Multiple organic chemicals have been associated with an increased risk for the development of keratinocyte carcinomas33 (see Table 108.2). Occupational chemical exposures which can lead to skin cancer most commonly involve pesticides, asphalt, tar, and polycyclic aromatic hydrocarbons, and they typically result in SCC. The skin cancers induced by chemical exposures are usually localized as well as multiple, most often appearing on the arms34. Arsenic is a well-defined cause of SCC (see Ch. 88). A clue to arsenic exposure is the presence of palmoplantar arsenical keratoses. BCC has also been reported following extensive arsenic exposure. The typical latency period from exposure to tumor development is 20–40 years35.

Human Papillomavirus Infection

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Human papillomaviruses (HPV) represent a large group of DNA tumor viruses that infect the epithelia of both skin and mucosae, inducing hyperproliferative lesions, most commonly warts. HPV is associated with anogenital SCCs, particularly in HIV-infected patients. Individuals with the genetic condition epidermodysplasia verruciformis (EV) are known to have a significantly increased risk of developing SCCs, especially in sun-exposed sites. Infection with the HPV types referred to as EV- or beta-types (see Table 79.1) is also observed in the general population, in particular in immunosuppressed solid organ transplant recipients36. Because specific HPV subtypes are thought to act as co-carcinogens

in conjunction with UVR in the early development of SCC37, a goal is to design HPV vaccines that address this issue38.

Immunosuppression Organ transplantation Solid organ transplant recipients have a markedly increased incidence of skin cancer, primarily SCC. The incidence of BCC in organ transplant recipients is up to 5–10 times greater than in the general population, while the incidence of SCC is 40–250 times greater. Risk factors include skin phototypes I/II, cumulative sun exposure, age at transplantation, and the degree and the length of immunosuppression. SCC is a significant cause of morbidity and mortality in transplant recipients39,40. The pathogenesis of skin cancer in transplant recipients is multifactorial, involving decreased immunity, direct carcinogenic effects of immunosuppressive medications, and HPV infection in addition to UVR exposure. Transplant recipients are prone to developing numerous lesions and are more likely to suffer local and regional recurrences and metastases39. AKs and SCCs begin to appear with increasing frequency several years after transplantation. Lesions are often multiple and usually develop in sun-exposed areas. HPV DNA is found in approximately 70–90% of transplant-associated SCCs. Tumors from transplant recipients contain HPV strains that occur in common benign cutaneous warts (HPV types 1 and 2), EV (HPV-5 and others), high-risk oncogenic warts (HPV types 16 and 18), and low-risk oncogenic genital warts (HPV types 6 and 11). Sometimes, several HPV types are detected within a single tumor. In one series of renal transplant patients from the US, 5% of the patients died of skin cancer. In another series of heart transplant patients from Australia, 27% died of skin cancer. Two-thirds of these deaths were due to SCC. Several studies have shown that in renal transplant patients sirolimus, an mTOR inhibitor, reduced the development of SCCs when compared to calcineurin inhibitors (e.g. cyclosporine, tacrolimus)41. In an Australian study, the SCCs in those receiving sirolimus were more superficial, but this has not been observed in other studies. Based upon currently available data, sirolimus appears to be preferable in patients with a history of SCCs or strong risk factors. Unfortunately, 30–50% of renal transplant patients may not tolerate prolonged administration of sirolimus41. Patients who receive hematopoietic transplants do not experience this marked increase in skin cancer incidence (unless they have received long-term voriconazole), presumably because of a shorter duration of immunosuppression.

Immunosuppressive drugs Use of immunosuppressive drugs, including systemic immunomodulators (“biologics”), increases the risk for the development of skin cancer42. Risk of SCC development is directly related to length of immunosuppressive drug usage. In one study, the risk of SCC was significantly increased among recipients of oral glucocorticoids (odds ratio = 2.31) and the risk of BCC was also elevated (odds ratio = 1.49)43. Similarly, thiopurine use for inflammatory bowel disease has been shown to increase the risk for NMSC42.

HIV infection Patients with HIV infection are at increased risk for the development of several cancers, including cutaneous SCC44. The incidence of HPVrelated SCC of the anus is significantly increased in this population, and can be more aggressive. For monitoring, anal cytology can be performed.

Other Risk Factors, Including BRAF Inhibitors Up to 25% of patients receiving selective BRAFV600 inhibitors (e.g. vemurafenib, dabrafenib) can develop either SCCs or keratoacanthomas (KAs). They develop primarily in individuals with cutaneous photodamage and can appear within weeks of beginning the kinase inhibitor. Fortunately, the combination of a selective BRAF inhibitor with a MEK inhibitor, as is routinely done nowadays, significantly reduces the incidence of side effects of both drugs, including the formation of SCCs and KAs. Other possible risk factors include residence at high altitudes, thermal burns, chronic ulcers, and tobacco abuse45. While evidence from animal models suggested a relationship between fat intake and skin cancer

Genetic Risk Factors Genetic predisposition Phenotypic characteristics such as red hair, light skin, poor ability to tan, and freckling have been identified as risk factors for melanoma as well as NMSC22. Pigmentation is a polygenic trait, with polymorphisms in several genes leading to the variation observed in the human race (see Ch. 65). A key gene encodes the human melanocortin-1 receptor (MC1R) which is expressed on the cell surface of melanocytes. Population-based studies in diverse ethnic groups have shown that the coding region of the human MC1R is remarkably polymorphic. In Caucasians, there is a strong association between nine common MC1R variant alleles and the red hair/fair skin phenotype, thus placing these individuals at higher risk of photocarcinogenesis49. Based upon genomewide association studies and candidate gene studies (see Ch. 54), ~30 and at least 11 susceptibility loci for BCC and SCC, respectively, have been identified, and they include multiple pigmentation loci.

Genetic syndromes associated with an increased risk of BCCs and/or SCCs Xeroderma pigmentosum

Xeroderma pigmentosum (XP) consists of a group of autosomal recessive disorders characterized by defects in unscheduled DNA repair (see Ch. 86). A markedly increased incidence of keratinocyte carcinoma and melanoma is observed in these individuals, if they are exposed to sunlight. SCCs and BCCs appear at an early age (median age, 8 years), and in affected individuals who are 5 cm (see Fig. 108.1A). The BCCs favor the sun-exposed areas of the face, neck and upper trunk, but may occur in sun-protected sites. As in the general population, nodular BCCs usually occur on the face, while superficial BCCs are found primarily on the torso. Individual lesions may be papulonodular, pedunculated, pigmented, eroded, ulcerated, or have a combination of these features. The pigmented BCCs are sometimes misdiagnosed clinically as melanocytic nevi (see Fig. 108.21). The clinical course of the cutaneous tumors is usually indolent prior to puberty, after which they enlarge and eventually ulcerate, as in the general population. Individuals with BCNS are exquisitely sensitive to ionizing radiation, and hundreds of tumors can develop in children within radiation ports following radiotherapy for medulloblastoma. Additional cutaneous findings include epidermoid (infundibular) cysts and facial milia.

Bazex–Dupré–Christol syndrome and Rombo syndrome

Bazex–Dupré–Christol syndrome is a rare condition, consisting of follicular atrophoderma (usually occurring as circumscribed areas on the dorsal aspect of the hands and feet), hypotrichosis, localized hypohidrosis, milia, epidermoid cysts, and multiple, primarily facial, BCCs. The BCCs develop during the second decade of life and frequently have a trichoepithelioma-like histopathologic appearance. In most families, the inheritance pattern is X-linked dominant. Sometimes a source of confusion is the completely different Bazex syndrome (acrokeratosis paraneoplastica), in which psoriasiform plaques of the fingers, toes, ears and nose are often associated with SCC of the upper aerodigestive tract. The so-called Rombo syndrome has many of the features of Bazex–Dupré–Christol syndrome. Patients have an atrophoderma vermiculatum-like appearance on the cheeks, with evidence of sweat duct proliferation histologically. In addition, they often have hypotrichosis, blepharitis, peripheral (facial/acral) telangiectatic erythema, milia, trichoepitheliomas, and BCCs.

Risk of Additional Cancers Individuals who have had a BCC or SCC are at increased risk for the development of additional BCCs and SCCs51, compared to the general population. They are also at increased risk for developing cutaneous melanoma52. Based upon epidemiologic studies, persons with a history of BCCs or SCCs are at increased risk for developing and dying from other (non-skin) cancers53,54,54a.

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Fig. 108.1 Basal cell nevus syndrome. A Numerous small and several large nodular BCCs on the face.   B Multiple palmar pits.

Neoplasms of the Skin



B, Courtesy, Jeffrey P Callen, MD.

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ACTINIC KERATOSIS AND SQUAMOUS   CELL CARCINOMA Clinical Features Actinic keratosis

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Actinic keratoses (AKs) were initially described as solar keratoses (due to their suspected cause) and senile keratoses (due to the age of onset). The term “actinic keratosis” is preferred over solar keratosis, partly because the abbreviation SK also stands for seborrheic keratosis. AKs have historically been characterized as being “precancerous” or “premalignant” because the atypical keratinocytes within these lesions are confined to the epidermis. There is no risk of metastasis until these lesions evolve into invasive carcinoma. The likelihood of an invasive SCC evolving from a given AK has been estimated to occur at a rate of 0.075–0.096% per lesion per year. Additional estimates of progression to invasive SCC range from 0 to 0.6% per year; the latter figure was derived from an elderly population with a history of keratinocyte carcinoma55. AKs are among the most frequently encountered skin lesions in clinical practice. They present on sun-damaged skin of the head, neck, upper trunk, and extremities (Fig. 108.2A). Individuals at higher risk of developing AKs include the elderly, those with lighter skin phototypes and those with a history of chronic sun exposure. The primary

lesion is a rough erythematous papule with white to yellow scale. Patients may report tenderness. AKs can range in size from a few millimeters to large confluent patches several centimeters in diameter, especially in patients with severe photodamage. One of the earliest signs is slight erythema with almost imperceptible scale (Fig. 108.2B), although some lesions are devoid of visible erythema and present only as slight scale with indistinct borders. A clue to their presence is background photodamage, i.e. dyspigmentation, telangiectasia and solar elastosis (see Ch. 87). Advanced lesions are typically thicker and welldefined with more visible hyperkeratosis and erythema. Lesions typically are clustered in areas of highest cumulative sun exposure, such as the superior helices of the ears, upper forehead, supraorbital ridge, nasal bridge, malar eminences, dorsal hands, extensor forearms, shins, and the bald scalp (Fig. 108.2C). Of note, clinically, AKs may spontaneously regress, but then can reappear in the same site55. Visual inspection is best performed with simultaneous palpation to detect lesions that may not be readily apparent. This is especially true in individuals with significant background erythema from chronic sun exposure or rosacea. Tenderness on palpation should alert the clinician to the possibility that the lesion has evolved into carcinoma. Clinical subtypes of AKs include the classic variant already described, hypertrophic (or hyperkeratotic), pigmented, lichenoid, atrophic, bowenoid, and actinic cheilitis. Hypertrophic (hyperkeratotic) AKs are easily identified on visual inspection as papules and plaques with scale or scale-crust and an erythematous base (Fig. 108.2D). The erythematous base often extends beyond the overlying hyperkeratosis. The hyperkeratotic scale can become white or yellow–brown over time. Due to their thickness, patients often find these lesions to be bothersome. Sometimes distinction from SCC can be difficult and biopsy is warranted. Occasionally, hyperkeratotic AKs may develop cutaneous horns which manifest as columns of thick cornified material that protrude above the skin. These should be biopsied to exclude the possibility of an underlying malignancy, as ~15% of cutaneous horns have invasive SCC at their bases56. Pigmented AKs, sometimes called superficial pigmented AKs (SPAKs), represent a subtype that often lacks associated erythema and has a hyperpigmented or reticulated appearance (Fig. 108.3). These lesions can at times be difficult to distinguish from reticulated seborrheic keratoses, lentigines, or even the lentigo maligna subtype of cutaneous melanoma. Dermoscopy may be a useful adjunct in these situations. Clinical clues are the location on sun-exposed skin, background solar changes, and hyperkeratosis that is sometimes appreciable by palpation. In cases in which the diagnosis is questionable, a biopsy is required to exclude the possibility of melanoma. Lichenoid AK is characterized histopathologically by the presence of a dense band-like inflammatory infiltrate. Clinically, this lesion is similar to the classic form of AK but has more erythema surrounding the base of the lesion. Patients may relate pruritus or tenderness that coincides with the onset of the lichenoid infiltrate in a pre-existing AK. It may be confused with a related lesion, the lichen planus-like keratosis, which also arises within areas of sun-damaged skin and can be pruritic, multiple, and eruptive57. Atrophic AKs usually have minimal surface change but are appreciated as pink to red, slightly scaly macules or patches (see Fig. 108.2B) that are found by histopathologic examination to have an atrophic epidermis. Actinic cheilitis is the term used to describe the characteristic changes that occur on the lower vermilion lip of individuals with moderate to severe photodamage. Actinic cheilitis may resemble the classic form of AK, with well-demarcated, erythematous papules or thin plaques with scale. In other patients, the erythema and especially the scale is more diffuse and can involve the entire lower vermilion lip; areas of leukoplakia may also be present (Fig. 108.4). When clinical distinction between actinic cheilitis and SCC of the lip is not possible, a biopsy should be performed. The potential for evolving into invasive SCC is higher for actinic cheilitis than it is for classic AKs.

Squamous cell carcinoma in situ SCC in situ is commonly called Bowen disease (Fig. 108.5). The most common presentation of SCC in situ is an erythematous scaly patch or slightly elevated plaque that often arises within sun-exposed skin of an elderly individual. However, it can develop in younger individuals



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Courtesy, Iris Zalaudek, MD; D, Courtesy, Jean L Bolognia, MD.

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108 Actinic Keratosis, Basal Cell Carcinoma, and Squamous Cell Carcinoma

Fig. 108.2 Actinic keratoses (AKs). A Multiple AKs on the face of an elderly woman with fair complexion, blue eyes, and moderate to severe photodamage; the AKs vary in size from a few millimeters to over a centimeter. On the left forehead, the red nodule with slight scale-crust represents a welldifferentiated SCC.   B Pink-colored atrophic AK with minimal scale on the forehead. C Multiple AKs on the bald scalp, some of which are hyperkeratotic; the area of hypopigmentation represents a site of previous treatment and due to the field defect, recurrence at the edge is commonly observed.   D Multiple, large hypertrophic AKs on the shin of an elderly woman; note the thick scale. B,

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Fig. 108.4 Actinic cheilitis. Erythema and scale of the entire lower vermilion lip with erosions and areas of leukoplakia. Courtesy, Kalman Watsky, MD.  

Fig. 108.3 Pigmented actinic keratoses. A,B The hyperpigmentation can have a reticulated appearance and there may be associated scale but an absence of erythema. Courtesy, Kalman Watsky, MD.  

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Fig. 108.5 Squamous cell carcinomas in situ, Bowen disease type. A Scaly red plaque on the chest with skip areas and background photodamage. B Larger broken-up pink plaque with scale-crust in the pubic region, a sun-protected site. This type of lesion is often misdiagnosed as dermatitis or psoriasis and treated with topical corticosteroids. C Bright red, well-demarcated plaque on the proximal nail fold with associated horizontal nail ridging; the possibility of HPV infection needs to be considered. D Dermoscopic findings of tiny dotted vessels in the upper half of the lesion combined with superficial scales. E Extensive involvement of the finger which was misdiagnosed clinically as an inflammatory dermatosis and treated for years with corticosteroid creams. B, Courtesy Kalman Watsky, MD; D, Courtesy, Iris Zalaudek, MD.  

Fig. 108.6 Squamous cell carcinoma in situ, erythroplasia of Queyrat type. Large, eroded erythematous plaque with well-demarcated borders. The lesion began on the shaft of the penis.  

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with significant photodamage or in sun-protected sites. Bowen disease may arise de novo or from a pre-existing AK. The head and neck, followed by the extremities and trunk, are the most common sites. Lesions can become crusted and in SCC in situ of anogenital mucosa, erosions may be prominent (Fig. 108.6).

Clinical distinction of SCC in situ from AK, superficial BCC, psoriasis, or chronic eczema may at times be difficult (see Fig. 108.5B,E). Generally, AKs are smaller lesions and superficial BCCs often have a more translucent quality with slight elevation of the leading edge as well as characteristic dermoscopic features (see Ch. 0). Patients with psoriasis and diffuse actinic damage can pose a diagnostic dilemma, as concomitant psoriatic papules and plaques may clinically resemble AKs and Bowen disease. Arsenic-induced SCC in situ resembles the classic variety clinically but has a marked tendency to be multifocal and to arise in sunprotected areas of the trunk. Associated findings include palmoplantar keratoses and guttate hypopigmentation superimposed on hyperpigmentation (see Ch. 88). Bowenoid papulosis is a term used when histopathologic changes of SCC in situ are found within genital warts, usually due to infection with an oncogenic strain such as HPV-16 or -18. Dermatologists often prefer to use this term when multiple papules are present, as opposed to calling all of them SCC in situ, because the lesions rarely become invasive. The clinical appearance can vary from small brown papules of the penis to perianal pink papules to corrugated pink to brown plaques of the inguinal creases (see Chs 73 & 79). Whether this entity represents true SCC in situ, or is a histopathologic simulant, is a matter of debate. Other variants of SCC in situ include a pigmented variant often seen in individuals with darker skin types and a verrucous form. Pigmented SCC in situ may be mistaken for a pigmented AK or even a superficial

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Fig. 108.7 Clinical spectrum of cutaneous squamous cell carcinoma (SCC). A Eroded and keratotic nodule that developed rapidly at the site of trauma on the shin. B Large, fungating nodule on the dorsum of the hand. C Multiple eroded superficial SCCs in association with actinic damage and sites of previous treatment on the cheek and neck of an elderly man. D Eroded, slightly vegetating, thick plaque arising within lichen sclerosis of the vulva. A, Courtesy, Jean L Bolognia, MD.  

melanoma and verrucous SCC in situ may simulate a seborrheic keratosis or a wart clinically.

Invasive cutaneous squamous cell carcinoma Invasive cutaneous SCC usually arises within a background of sundamaged skin, most commonly on the bald scalp, face, neck, extensor forearms, dorsal hands, and shins (Fig. 108.7A,B). The color usually varies from erythematous to skin-colored; rarely there are pigmented variants. SCCs are often papulonodular, but can be plaque-like, papillomatous, or exophytic. The degree of associated scale varies, with some lesions becoming quite hyperkeratotic; other secondary changes include crusting, erosions, and ulcerations (Fig. 108.7C,D). The natural history of SCCs also varies, from slowly enlarging to rapidly growing with significant tenderness and even pain. Of note, paresthesias, anesthesia and pain may be signs of perineural invasion. The clinical differential diagnosis, in addition to hypertrophic AK, is outlined in Table 108.4. Staging of SCC takes into account tumor volume as measured by diameter (2 mm), and SCCs arising within sun-damaged skin are often early stage, i.e. T1/AJCC Stage I (Table 108.5). Anatomic sites with a greater risk of aggressive biologic behavior include the ear58, the lips (Fig. 108.8), and mucosal sites including the vulva and penis (see Fig. 108.7D). Clinical examination of patients with invasive SCC includes palpation of regional lymph nodes for enlargement and firmness, followed by assessment of size if enlarged.

Keratoacanthoma Keratoacanthomas (KAs) are considered by some to be a variant of SCC and by others to represent benign tumors (i.e. pseudomalignancy). The exact nosology is still uncertain, although there are some data that support its differentiation from “conventional” SCC. Typically, a rapidly enlarging papule evolves into a sharply circumscribed, crateriform nodule with a keratotic core over a period of a few weeks (Fig. 108.9A,B), and then it may resolve slowly over months to leave an atrophic scar59. Most lesions occur on the head and neck or in sun-exposed areas of the extremities, with or without symptoms of pain or tenderness. There are several distinct clinical presentations of KA, including solitary, multiple, grouped, keratoacanthoma centrifugum marginatum (Fig. 108.9C), giant (Fig. 108.9D), subungual, palmoplantar, intraoral, multiple spontaneously regressing (Ferguson–Smith), multiple nonregressing, and generalized eruptive (Grzybowski). KAs are also seen in patients with Muir–Torre syndrome and they may have sebaceous differentiation (see Ch. 63). In addition, multiple KAs have been associated with chemical exposures, immunosuppression33, BRAF inhibitors, and HPV infection60. By far the most common presentation is the solitary KA. While most of these tumors are small (5 to 15 mm), some KAs (e.g. keratoacanthoma centrifugum marginatum [see Fig. 108.9D]) may reach several centimeters in diameter, persist for months before resolution, and heal with prominent scarring. Grouped KAs may resolve more slowly than

BASAL CELL CARCINOMA (BCC), SQUAMOUS CELL CARCINOMA (SCC), AND KERATOACANTHOMA (KA) – CLINICAL DIFFERENTIAL DIAGNOSES

BCC

SCC

KA

Benign and malignant neoplasms and reactive disorders with pseudoepitheliomatous hyperplasia √

Seborrheic keratosis, including inflamed or irritated Lichen planus-like keratosis

Actinic Keratosis, Basal Cell Carcinoma, and Squamous Cell Carcinoma

108



√ √

Verruca vulgaris, especially periungual Amelanotic melanoma*





Merkel cell carcinoma





Atypical fibroxanthoma



Prurigo nodularis



Hypertrophic lichen planus



Hypertrophic lupus erythematosus





√ √

Additional entities √

Cysts, especially inflamed or proliferating variant Adnexal carcinomas





Lymphoma cutis, especially ALCL mimicking SCC



KA-like lesions in cutaneous ALCL and in LyP



DFSP, cutaneous leiomyosarcoma



Cutaneous metastases from visceral carcinomas





Mammary and extramammary Paget disease





Epithelioid sarcoma



Verrucous melanoma



Molluscum contagiosum

√ √

√ √

*Pigmented variants of BCC and SCC can also be confused with melanoma. Table 108.4 Basal cell carcinoma (BCC), squamous cell carcinoma (SCC), and keratoacanthoma (KA) – clinical differential diagnoses. ALCL, anaplastic large cell lymphoma; DFSP, dermatofibrosarcoma protuberans; LyP, lymphomatoid papulosis.  

solitary KAs, while subungual KAs have been associated with underlying bony destruction. The Ferguson–Smith syndrome is an autosomal dominant condition due to mutations in TGFBR1 which encodes TGF-β receptor type 1. Multiple KAs develop within sun-exposed areas, usually beginning during the third decade of life. Lesions typically regress over weeks to months, but rare examples of metastases have been reported.

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STAGING OF CUTANEOUS SQUAMOUS CELL CARCINOMA (SCC) OF THE HEAD AND NECK T, N, M

Primary tumor (T) TX

Primary tumor cannot be identified

Tis

Carcinoma in situ

T1

Tumor 3 cm but 6 cm in greatest dimension and ENE(−) (2b); or in bilateral or contralateral lymph nodes, none >6 cm in greatest dimension and ENE(−) (2c)

N3

Metastasis in a lymph node, >6 cm in greatest dimension and ENE(−) (3a); or metastasis in any node(s) and ENE(+) (3b)

%

Distant metastasis (M) M0

No distant metastasis

M1

Distant metastasis

Fig. 108.8 Squamous cell carcinoma (SCC) of the lower lip. A Extensive hyperkeratosis and leukoplakia of the lower vermilion lip; histopathologically, the SCC was superficially invasive and well-differentiated. B Verrucous and eroded nodule on the lower vermilion lip in a heavy smoker.  

Stage 0

T

N

M

Tis

N0

M0

I

T1

N0

M0

II

T2

N0

M0

III

IV

T3

N0

M0

T1

N1

M0

T2

N1

M0

Verrucous carcinoma

T3

N1

M0

T1

N2

M0

T2

N2

M0

T3

N2

M0

T Any

N3

M0

T4

N Any

M0

T Any

N Any

M1

Verrucous carcinoma is a rare, well-differentiated variant of SCC which tends to occur in middle-aged and older adults. It is considered a lowgrade malignancy with three major subtypes: (1) epithelioma cuniculatum (plantar surface of the foot); (2) giant condyloma acuminatum of the genitalia (also known as Buschke–Löwenstein tumor; see Ch. 79); and (3) oral florid papillomatosis (oral mucosa). Of note, the “cuniculatum” refers to the rabbit burrow-like appearance with crevices. Clinically, verrucous carcinomas present as large (sometimes huge), exophytic tumors with a papillomatous or verrucous surface (Fig. 108.10A,B). They are commonly associated with HPV infection, and distinguishing between a verrucous carcinoma and a large wart or condyloma acuminatum can be difficult. Gradual penetration of verrucous carcinomas into underlying tissues can result in destruction of subcutis, fascia, and bone. These tumors can arise within scars and amputation stumps (Fig. 108.10C) as well as in association with osteomyelitis fistulae and chronic venous insufficiency. Verrucous carcinomas often recur after attempted removal, but they usually do not metastasize, except for recurrent or irradiated tumors with anaplastic transformation. Some authors consider subungual keratoacanthomas, proliferating tricholemmal cysts (proliferating pilar tumors), and papillomatosis cutis carcinoides (which favors the shins and dorsal feet) to be subtypes of verrucous carcinoma.

*Deep invasion is defined as invasion beyond the subcutaneous fat or >6 mm (as measured from the granular layer of adjacent normal epidermis to the base of the tumor); perineural invasion for T3 classification is defined as tumor cells within the nerve sheath of a nerve lying deeper than the dermis or measuring 0.1 mm or larger in caliber, or presenting with clinical or radiographic involvement of named nerves without skull base invasion or transgression.

Table 108.5 Staging of cutaneous squamous cell carcinoma (SCC) of the head and neck. The Brigham and Women’s Hospital (BWH) T staging system divides T2 into a and b and considers T1 = 0 high-risk factors (HRF), T2a = 1 HRF, T2b = 2–3 HRF, and 3 = ≥4 HRF or bone invasion; the HRF are diameter ≥2 cm, poorly differentiated, perineural invasion ≥0.1 mm, or invasion beyond fat114. ENE, extranodal extension. Adapted from American Joint Committee on Cancer, 2017.  

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Multiple KAs of the Grzybowski type present as thousands of papules resembling milia or early eruptive xanthomas. They develop rapidly and may slowly resolve over a period of months59. Patients often have scarring, ectropion, and a mask-like facies.



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Fig. 108.10 Verrucous carcinoma. A Longstanding large nodule on the plantar surface with a rabbit burrow-like appearance; such a tumor is also referred to as an epithelioma cuniculatum. B Keratotic and ulcerated plaque on the ventromedial aspect of the great toe. C A classic location in an amputation stump. In general, these welldifferentiated SCCs enlarge slowly.  

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108 Actinic Keratosis, Basal Cell Carcinoma, and Squamous Cell Carcinoma

Fig. 108.9 Clinical spectrum of keratoacanthomas. A,B Rapidly growing, erythematous crateriform nodules with a rolled border and central keratotic core. C Progressive peripheral expansion and central involution with residual atrophy characterize keratoacanthoma centrifugum marginatum. D Giant keratoacanthoma with a yellow–red color and a history of rapid growth.

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Lymphoepithelioma-like carcinoma of the skin Lymphoepithelioma-like carcinoma of the skin (LELCS) is an uncommon neoplasm that shows histopathologic similarities to lymphoepithelioma-like carcinoma (LELC), an undifferentiated nasopharyngeal carcinoma associated with EBV infection. It has been suggested that LELCS has “the potential for both sweat glandular and follicular differentiation”61. Clinically, it presents as a dermal papule or nodule arising in the head and neck region62. In contrast to LELC, EBV genome integration is not found in LELCS, and metastases are rare. Evidence of HPV infection is also usually absent. LELCS is considered by some to be a variant of cutaneous SCC, while others view it as a type of cutaneous adnexal carcinoma. Histologically, LELCSs are localized within the dermis or subcutis, with involvement of the overlying epidermis having been observed in only a few cases63. The tumor consists of clusters of epithelial cells (with large vesicular nuclei and prominent nucleoli) intermingled with a prominent inflammatory infiltrate that sometimes forms germinal

centers. However, classic signs of squamous differentiation such as keratin “pearls”, dyskeratotic cells, or intercellular bridges are absent62. By immunohistochemistry, there is expression of cytokeratin and epithelial membrane antigen within the neoplastic cells; stromal lymphocytes express leukocyte common antigen (CD45). The histopathologic differential diagnosis includes cutaneous lymphadenoma, lymphocytoma cutis, follicle center lymphoma, and carcinoma with thymus-like differentiation.

In vivo Imaging Methods Dermoscopy Dermoscopy of invasive SCC reveals linear-irregular vessels, elongated vessels resembling hairpins, dotted vessels or a combination of these findings (polymorphous or atypical vascular pattern). Typically, vessels are surrounded by a whitish halo; the latter is the dermoscopic hallmark of all keratinizing tumors and is also found in KAs and in seborrheic keratoses (see Ch. 0). Ulceration and hemorrhagic crusts appear as red-, brown-, or black-colored surface blotches. Rare pigmented SCCs may have a scaly surface, diffuse or homogenous blue pigmentation, and/or irregularly distributed blue–gray granular structures. AKs on the face demonstrate a so-called “strawberry pattern” (an erythematous

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pseudonetwork surrounding hair follicle orifices filled with yellowish keratotic plugs)64, whereas in other body sites they often display surface scales and dotted vessels. Bowen disease typically has a scaly surface and glomerular vessels.

Reflectance confocal microscopy (RCM) RCM is an imaging technique which allows non-invasive horizontal imaging of the epidermis and superficial dermis at almost the same resolution as routine histology. RCM (and dermoscopic) features of keratinizing tumors are often difficult to visualize due to the surface scaling which obscures underlying structures. Although to date, a limited number of publications have described the diagnostic RCM features of AKs and SCCs, one study suggested that a disarranged pattern and/or an atypical honeycomb pattern, in conjunction with round nucleated cells at the level of the spinous/granular layer, were key features of SCC65.

Pathology

Squamous cell carcinoma in situ

Actinic keratosis There is partial thickness involvement of the epidermis by atypical keratinocytes displaying nuclear pleomorphism, especially in the basal layer, and disordered maturation. The lesion may be acanthotic, often with an increased number of buds protruding into the papillary dermis, or atrophic with a loss of rete ridges. Hyperkeratosis and parakeratosis are constant findings. Acrosyringia and acrotrichia are often uninvolved, resulting in orthokeratosis above the ostia of these structures (Fig. 108.11A). This produces a characteristic pattern of alternating ortho- and parakeratosis, often referred to as the “flag” or “pink and blue” sign, since the color of the stratum corneum shows a more eosinophilic column (parakeratosis) alternating with a basophilic one (orthokeratosis). AKs are associated with solar elastosis within the dermis (Fig. 108.11B,C).

Fig. 108.11 Histopathology of actinic keratoses (AKs). A Hyperkeratotic AK with alternating pink and blue colors in the cornified layer; the pink-colored parakeratotic columns within the stratum corneum are located above the atypical keratinocytes in the spinous layer, while the blue-colored columns of orthohyperkeratosis are above the acrosyringia. Atypical epidermal keratinocytes also display a pinkish color that contrasts with the color of the basophilic, normal keratinocytes of the acrosyringia. B Acantholytic variant with clefts within the stratum spinosum. C Pigmented actinic keratosis with increased melanin pigmentation within the basal layer. Note the solar elastosis in the dermis. B,C, Courtesy Lorenzo  

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The keratinocytic atypia of an AK is usually confined to the lower portion of the epidermis, as opposed to full-thickness atypia in SCC in situ. Diagnostic difficulty arises when small foci of full-thickness atypia occur within a lesion that otherwise has the characteristic features of an AK. Some pathologists may use the term “bowenoid AK” in this setting. In addition to atrophic and bowenoid AKs, several other histopathologic variants have been described, including acantholytic (see Fig. 108.11B), hypertrophic (hyperkeratotic), pigmented, lichenoid, and actinic cheilitis. In hypertrophic AKs, marked hyperkeratosis with associated parakeratosis is evident. If pronounced, this can lead to cutaneous horn formation. Pigmented AKs additionally show basilar pigmentation in a pattern similar to a solar lentigo (see Fig. 108.11C). Lichenoid AKs demonstrate a band-like infiltrate of lymphocytes in the papillary dermis directly beneath the dermal–epidermal junction. Actinic cheilitis arises on the vermilion lips, primarily lower one, and may or may not have associated inflammation.

SCC in situ (Bowen disease), by definition, demonstrates full-thickness atypia of the epidermis over a broad zone (Fig. 108.12). Dyskeratosis, nuclear pleomorphism, and apoptosis are often more florid than in AKs, and mitoses are frequent. The epidermis commonly exhibits acanthosis. Atypical keratinocytes more commonly extend down the adnexa than in an AK. Diffuse confluent parakeratosis is also observed more often than the focal parakeratosis seen in an AK. Lastly, in contrast to AKs, the basal layer of the epidermis is usually spared and, at least focally, is composed of small compressed basaloid keratinocytes arranged in a palisade.

Invasive squamous cell carcinoma Well-differentiated SCC generally arises in the setting of epidermal changes consistent with AK. In addition, there is a downward proliferation of lobules and detached aggregations of glassy, brightly eosinophilic keratinocytes containing nuclei with some degree of pleomorphism and mitoses (Fig. 108.13A). Nucleoli may be prominent. Intercellular bridges (desmosomes) are often apparent, along with keratin pearls and apoptotic cells. The degrees of nuclear atypia and cellular differentiation vary within and among tumors (Fig. 108.13B). The pink quality of the cytoplasm arises from abundant high-molecular-weight keratin. When invasive SCC arises from Bowen disease, the intradermal tumor cells often have a more basophilic appearance. The inflammatory infiltrate varies considerably in intensity and consists primarily of lymphocytes and plasma cells. Poorly differentiated SCCs display progressive and overlapping features, ending in highly infiltrative tumors that lack overt keratinization

Cerroni, MD.

Fig. 108.12 Histopathology of Bowen disease (squamous cell carcinoma in situ). Irregular epidermal hyperplasia with atypical pleomorphic keratinocytes throughout the entire epidermal thickness. Note several necrotic keratinocytes (inset). Courtesy Lorenzo Cerroni, MD.  

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Fig. 108.13 Squamous cell carcinoma (SCC): range of histopathologic findings. A Well-differentiated SCC with numerous horn pearls (eosinophilic parakeratotic keratinization). B Poorly differentiated SCC with strands and cords of epithelial cells with prominent nuclear atypia and no signs of keratinization. C Perineural growth and neurotropism of a poorly differentiated SCC. D Acantholytic SCC characterized by epithelial aggregations composed of atypical keratinocytes with acantholysis. Courtesy, Lorenzo Cerroni, MD.  

and sometimes have a spindle cell morphology. Perineural infiltration (Fig. 108.13C) and desmoplastic or sclerotic stromal change become more common in these forms. Neurotropic SCCs behave in a more aggressive manner, with local recurrence rates approaching 50%66. Poorly differentiated tumors (cytokeratin-positive) generally require immunohistochemistry to distinguish them from spindle-cell melanoma (generally S100-positive), atypical fibroxanthoma (cytokeratinand S100-negative; vimentin- and CD10-positive), leiomyosarcoma (smooth muscle actin- and desmin-positive), and mycobacterial spindle cell pseudotumor (Fite stain-positive). There are several variants of SCC. The acantholytic type (Fig. 108.13D) and the related adenoid (pseudoglandular) SCC possibly have a worse prognosis, but this has recently been questioned66a. Other variants include SCC with overlying cutaneous horn formation as well as bowenoid, clear cell, pseudovascular, desmoplastic, mucinous, and pigmented SCC. Marjolin ulcer is a SCC that occurs in a chronic wound or scar, including scars from a burn. A large, prospective study focusing on risk factors that predict metastasis and local recurrence in cutaneous SCC reported overall rates of 4% for metastasis and 3% for local recurrence58. Only tumors >2 mm in vertical thickness had a significant risk of developing metastases. For SCCs whose thickness was between 2.1 and 6 mm, the metastatic rate was 4%, and it was 16% for lesions thicker than 6 mm. Other risk factors for metastasis included location on the ear, increased horizontal size, and immunosuppression (Table 108.6). Tumor thickness and the presence of a desmoplastic stroma were found to be risk factors for local

RISK FACTORS FOR METASTASIS OF INVASIVE SQUAMOUS CELL CARCINOMA Tumor thickness: >2 mm (high risk: tumor thickness >6 mm) Diameter: >2 cm Location: ear, lips, mucosae including tongue, vulva, penis (perineural growth may be an additional risk factor in these locations) Arising within a scar (e.g. burn, radiation) Histopathologic features: poorly differentiated or undifferentiated, acantholytic*, developing within Bowen disease Immunosuppression

*Recently questioned66a. Table 108.6 Risk factors for metastasis of invasive squamous cell carcinoma.  

Based in part upon ref. 58.

recurrence. For example, of the 51 patients with desmoplastic SCC, 24% developed local recurrences, compared to 1% of the 564 patients with non-desmoplastic SCCs.

Keratoacanthoma A KA typically has a “volcano-like” architecture. The tumor is comprised of well-differentiated keratinocytes with a brightly eosinophilic

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glassy cytoplasm, surrounding a core filled with cornified material (Fig. 108.14). An inflammatory infiltrate of lymphocytes, and often eosinophils, is usually present. Small intratumoral abscesses of neutrophils are common, and neurotropism may be observed. As the lesion regresses, the dome-shaped architecture flattens and fibrosis develops at the base of the lesion. Cytologic atypia is usually minimal in a KA. If hyperchromatic nuclei or abnormal mitoses are prominent, then the diagnosis of an invasive KA-like SCC should be rendered.

Verrucous carcinoma Verrucous carcinoma is defined as a well-differentiated and distinct clinicopathologic variant of SCC (Fig. 108.15). However, this term should not be applied to every SCC that has a warty appearance. Cytologic atypia is minimal, and the tumor has a pushing border as opposed to an infiltrating invasive edge. Verrucous carcinoma can be associated with HPV infection, and histopathologic distinction from a large wart or condyloma is often difficult and may be impossible if the entire tumor is not available for microscopic examination. The major distinguishing features of a verrucous carcinoma are the massiveness and depth of the lesion, as well as the more pronounced irregular architecture.

Histopathologic simulators of SCC There are a number of histopathologic simulators of SCC, including irritated seborrheic keratosis, verruca vulgaris, warty dyskeratoma, inverted follicular keratosis, prurigo nodularis, hypertrophic lichen planus, hypertrophic lupus erythematosus, atypical mycobacterial or “deep” fungal infections, granular cell tumor, and pseudocarcinomatous hyperplasia (e.g. in a healing wound). Architectural pattern and recognition of cellular and nuclear features of malignancy are critical in

establishing a diagnosis. In some cases, only clinical correlation allows a distinction between SCC and some of these conditions.

BASAL CELL CARCINOMA Clinical Features BCC is a tumor that arises within sun-damaged skin. It rarely develops on the palms and soles or mucous membranes. Currently, despite the description of more than 26 different subtypes of BCC, a universally accepted classification scheme is lacking67. In the view of the authors, there are four major distinctive clinicopathologic types, namely, nodular, superficial, morpheaform, and fibroepithelial (also referred to as fibroepithelioma of Pinkus)68. Combinations of the latter three types with nodular BCC may occur. While all types of BCC may ulcerate, ulceration is observed more often in the nodular type. Also, variable amounts of melanin may be present within these tumors, even though the majority of BCCs are amelanotic; pigmented BCCs are observed more commonly in those with darker skin phototypes69. When one attempts to classify BCCs, a significant confounding factor is the number of different histopathologic patterns that become entwined with clinical subtypes. Examples are cystic, mucinous, micronodular, and basosquamous BCCs. Although these patterns may be seen in all four major clinicopathologic types of BCC, they are observed more frequently in the nodular type.

Nodular basal cell carcinoma Nodular BCC is the most common subtype, accounting for ~50% of all BCCs. Lesions typically present as a shiny, pearly papule or nodule with a smooth surface and the presence of arborizing telangiectasias (Fig. 108.16). With time, the tumor can enlarge and ulcerate (rodent ulcer, phagedenic ulcer), but an elevated rolled border usually remains and is a clinical clue to the diagnosis. A variable degree of pigmentation may be seen within the tumor (Fig. 108.17A–C). Sites of predilection are the face, especially the cheeks, nose, nasolabial folds, forehead and eyelids, but nodular BCCs may arise in any hair-bearing area of the skin. They are rarely seen in non-hair-bearing sites, e.g. genital mucosa. The clinical differential diagnosis of non-ulcerated lesions includes adnexal neoplasms (see Ch. 111), fibrous papules, and intradermal melanocytic nevi (softer and comma vessels by dermoscopy) as well as the entities outlined in Table 108.4; for ulcerated lesions, see Table 45.3 and Fig. 105.1.

Superficial basal cell carcinoma

Fig. 108.14 Histopathology of keratoacanthoma. Scanning magnification of a stereotypical keratoacanthoma with a keratin-filled crater encompassed by epithelial lips. Courtesy Lorenzo Cerroni, MD.  

Superficial BCCs typically present as a well-circumscribed, erythem­ atous, macule/patch or thin papule/plaque, with the diameter varying from a few millimeters to several centimeters (Fig. 108.18). Additional findings include focal scale and/or crusts, a thin rolled border, and variable amounts of melanin; in larger lesions, areas of spontaneous regression may be present, characterized by atrophy and hypopigmentation. The mean age at diagnosis is 57 years, a younger age than for other types of BCC47, and in younger age groups, superficial BCC is the most common subtype70. This BCC variant favors the trunk and extremities; less often, it occurs in the head and neck region. Multiple lesions may be present. The growth pattern of superficial BCCs is primarily horizontal, but tumors may occasionally become deeply invasive, with induration, ulceration, and nodule formation. Subclinical lateral spread accounts for the significant recurrence rate of these tumors after routine surgical treatment. The clinical differential diagnosis includes solitary lichenoid keratosis and Bowen disease (more scale) as well as inflammatory diseases such as psoriasis, dermatitis, and cutaneous lupus erythematosus.

Morpheaform basal cell carcinoma Fig. 108.15 Histopathology of verrucous carcinoma. A markedly irregular epithelial hyperplasia with prominent hyperkeratosis is seen. For the histopathologic diagnosis of verrucous carcinoma, the size of the lesion and architectural features are more important than cytomorphology, which usually does not show prominent atypia, thus emphasizing the need for large excisional biopsies in order to make a proper diagnosis. Courtesy, Lorenzo Cerroni, MD.  

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This less common subtype of BCC frequently presents as a slightly elevated to even depressed area of induration that is usually light pink to white in color and has ill-defined borders; it may resemble a scar or plaque of morphea (Fig. 108.19). The surface of the lesion is typically smooth, although crusts with underlying erosions or ulcerations as well as superimposed papules may be observed. While an elevated pearly border is typically absent, telangiectasias may be present. The biologic behavior is usually more aggressive, with extensive local destruction.

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Fig. 108.16 Clinical spectrum of nodular basal cell carcinoma. A Translucent papulonodule with prominent telangiectasias on the infraorbital cheek.   B Classic presentation with a pearly rolled border and central hemorrhagic crust. C Larger plaque with rolled borders and multiple telangiectasias. D Noduloulcerative tumor of the preauricular region with translucent rolled borders, most obvious at “12 o’clock”. E Depressed scar on the nose. A, Courtesy, Stanley J Miller, MD.  

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E, Courtesy, Kalman Watsky, MD.

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Fig. 108.17 Additional variants of basal cell carcinoma (BCC) – pigmented and fibroepithelial (fibroepithelioma of Pinkus). A,B Pigmented nodular BCCs with varying degrees of melanin pigmentation that may clinically resemble cutaneous melanoma. However, the glassy translucency, in concert with characteristic dermoscopic features such as arborizing telangiectasias and multiple blue–gray ovoid globules (C), point to the diagnosis of pigmented BCC. D A soft, skin-colored to light pink, broad, sessile plaque on the lower back is a classic presentation for a fibroepithelial BCC. A, Courtesy, Kalman Watsky, MD; C, Courtesy, Giuseppe Argenziano, MD; D,  

Courtesy, Oscar Colegio, MD.

Fibroepithelial basal cell carcinoma (fibroepithelioma of Pinkus) This rare variant of BCC usually presents as a skin-colored or pink, sessile plaque or pedunculated papulonodule with a smooth surface (Fig. 108.17D). It favors the trunk, especially the lower back. Fibroepithelial BCCs often occur in individuals with multiple superficial BCCs. The clinical differential diagnosis includes an intradermal melanocytic nevus or large fibroepithelial polyp (skin tag). Of note, some experts believe that fibroepithelioma of Pinkus is a variant of trichoblastoma (not BCC).

Additional histopathologic subtypes of BCC Basosquamous carcinoma

Basosquamous carcinoma (metatypical BCC) is a tumor that has histologic features of both BCC and SCC. These tumors may behave biologically more like an SCC than a BCC, i.e. have more aggressive behavior with a greater likelihood of both recurring after treatment and

metastasizing71. It has been estimated that this variant constitutes 1% of all keratinocyte carcinomas. When metastases occur, they may have the same microscopic appearance as the original tumor or may resemble a poorly differentiated SCC. The incidence of metastases with this variant of BCC has been estimated to be >5%.

Micronodular basal cell carcinoma

This histopathologic term applies to BCCs in which smaller aggregations of basaloid cells infiltrate the dermis. Micronodular BCCs have a destructive behavior, with subclinical spread and high rates of recurrence. Clinically, they may present as macules, papules or slightly elevated plaques and may be difficult to differentiate from nodular BCC.

In vivo Imaging Methods Dermoscopy Dermoscopy provides a demonstrated benefit in the diagnosis of nonpigmented and pigmented BCCs. The dermoscopic hallmark of BCC

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Fig. 108.19 Morpheaform basal cell carcinomas. A Recurrent tumor two years after microscopically controlled surgery; note the scar-like appearance with superimposed glassy pink and brown papules. B Oval hypopigmented firm plaque that resembles   a scar (e.g. post electrodesiccation and curettage). While there   is a light pink color between 6 and 9 o’clock, no translucency or rolled border is present. C A classic example with indistinct borders and scar-like appearance.

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Fig. 108.18 Superficial basal cell carcinomas. A Numerous erythematous patches and thin plaques on the back of a man with a history of arsenic exposure decades previously. B A solitary large, thin, dark pink plaque. There are scattered areas of fine scaling and small foci of brown pigment within the rolled border. As a rule, these lesions are neither pruritic nor tender.  

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is the presence of well-focused arborizing vessels in conjunction with foci of microulceration (Fig. 108.20). Additional dermoscopic findings with a high specificity for BCC include large blue–gray ovoid nests, multiple blue–gray globules, leaf-like structures, and spoke-wheel areas (Fig. 108.21; see Ch. 0). As expected, there is no pigment network69. Short, fine superficial telangiectasias as well as concentric structures and multiple, “in-focus” blue–gray dots have also been described72.

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Reflectance confocal microscopy (RCM) The following RCM features (see above for description of technique) have been described for all BCCs (Fig. 108.22), regardless of subtype73,74: (1) variable architectural disarray of the epidermis; (2) a streaming pattern of elongated monomorphic nuclei that are polarized along the same axis; (3) tightly packed cells in the papillary dermis with a nodular/ cord-like growth pattern; (4) palisading of tumor cell nuclei; (5) peritumoral dark cleft-like spaces (representing peritumoral mucinous edema); and (6) the presence of bright dendritic cells and melanophages (in pigmented BCC)73.

Pathology

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All types of BCC have, as a least common denominator, the presence of aggregations of basaloid keratinocytes within a variably fibromyxoid stroma. A connection to the epidermis is usually observed, at least focally (Fig. 108.23A). The tumor cells have large, relatively uniform nuclei and scant cytoplasm; cellular borders are indistinct and desmosomes are inapparent. Apoptotic cells are common. The fibromyxoid stroma is intimately associated with the tumor islands, often showing increased cellularity. A characteristic feature of BCC is retraction of the stroma around the tumor islands, creating microscopically visible clefts (Fig. 108.23B). Although this latter feature may not be seen in all instances, when present it is useful in differentiating BCCs from histopathologic simulators. In nodular BCC, large, round or oval aggregations of basaloid keratinocytes extend from the epidermis into the dermis (Fig. 108.23C).

Fig. 108.20 Dermoscopy of a nodular basal cell carcinoma of the forehead. The arborizing telangiectasias are in sharp focus (inset).  

Overlying ulceration with an associated inflammatory response may be present. Peripheral palisading is usually prominent and peritumoral clefts are often conspicuous in nodular BCC (Fig. 108.23D). Centrally, the nuclei lack organization and are more randomly distributed. In larger tumor islands, central areas of necrosis may develop, leading to the formation of cystic spaces. True cystic or nodulocystic BCCs have mucin pools within the tumors (Fig. 108.23E). Micronodular BCCs are composed of tumor islands much smaller than those of nodular BCC (Fig. 108.23F). The cellular features are similar.

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Major distinguishing features

Fig. 108.21 Dermoscopy of pigmented “nevoid” basal cell carcinomas of the abdomen in a patient with basal cell nevus syndrome. There are pigment globules, maple leaf structures, and one arborizing telangiectasia as well as a pink background color (inset).  

Adenoid cystic carcinoma

Cribriform pattern; EMA-positive

Ameloblastoma

Location in mouth

Basaloid follicular hamartoma

Multiple small papules; positive family history

Cloacogenic carcinoma

Anal location

Dermatofibroma

Basaloid induction in overlying epidermis

Eccrine carcinoma

Small sweat ducts

Folliculocentric basaloid proliferation

Focal follicular budding

Merkel cell carcinoma

Punctate keratin (CK20-positive) in cytoplasm; positivity for Merkel cell polyomavirus

Metastatic breast carcinoma

History; single filing; expression of CK7, mammoglobulin, gross cystic disease fluid protein-15

Microcystic adnexal carcinoma

Small keratin cysts, absent stromal retraction, ductal differentiation

Mucinous carcinoma

Pools of mucin with floating basaloid islands

Nevus sebaceus

Basaloid induction; trichoblastomas and BCCs may arise within a nevus sebaceus

Sebaceous carcinoma

Adipophilin-positive sebocytes

Trichoblastoma

Clefts within the stroma; hair germs and papillae; PHLDA1-positive

Trichoepithelioma and desmoplastic trichoepithelioma

Horn cysts, absent stromal retraction, papillary mesenchymal bodies; PHLDA1positivity; peritumoral CD34 positivity; positive family history when multiple

108 Actinic Keratosis, Basal Cell Carcinoma, and Squamous Cell Carcinoma

HISTOLOGIC SIMULANTS OF BASAL CELL CARCINOMA (BCC)

Table 108.7 Histologic simulants of basal cell carcinoma (BCC). CK, cytokeratin; EMA, epithelial membrane antigen.  

Fig. 108.22 Reflectance confocal microscopy of a basal cell carcinoma. A 0.5 × 0.5 mm image at a depth of 85 microns. Aggregations of basaloid cells with hyporeflective cleft-like peritumoral spaces (arrowheads) and dilated tortuous blood vessels can be seen (arrows). Courtesy, Claudia Curchin, MBBS.  

Superficial BCCs are characterized by small, superficially located buds of basaloid cells extending no more deeply than the papillary dermis, with or without clefting (see Fig. 108.23A,B). In a given twodimensional plane of section, there are skip areas along the epidermis, hence the synonym “superficial multifocal BCC”. There is evidence that many of these multifocal buds connect in a net-like pattern, such that most tumors are not truly multifocal. Keratotic BCCs or BCCs with follicular differentiation contain small keratinized cysts (that lack a granular layer) within the aggregates of neoplastic cells. These lesions display differentiation towards hair follicle structures. Although they can be difficult to differentiate from trichoepitheliomas or other follicular adnexal neoplasms, immunostaining for PHLD1, a marker of epithelial follicular stem cells, is stronger and more diffuse in trichoepitheliomas75. In addition, prominent clefting between the palisaded tumor islands and the stroma, as

well as a myxoid (rather than a fibrocellular) stroma, characterize these BCCs. Pigmented BCCs usually have the overall architecture of a nodular BCC. They contain aggregates of melanin, often irregularly distributed, and melanocytes (Fig. 108.23G). Melanophages are frequently dispersed within the dermis. Basosquamous BCCs have histologic features of both BCC and SCC (Fig. 108.23H). Morpheaform, sclerosing and infiltrative BCCs share similar histopathologic features. A common finding is a pattern of strands and cords of basaloid keratinocytes extending between collagen bundles (Fig. 108.23I). These tumor islands may be composed of very few cells and may surround nerves. A peripheral palisaded pattern of tumor cells is absent and stromal retraction (cleft formation) is also frequently not evident. Fibroepithelial BCC (fibroepithelioma of Pinkus) is a variant of BCC characterized by thin anastomosing strands and cords of tumor cells that project downward from the epidermis in a fenestrated pattern and are embedded in a fibrous stroma (Fig. 108.23J). Both peripheral palisading and peritumoral retraction are less prominent. The differential diagnosis includes eccrine syringofibroadenoma and reticulated seborrheic keratosis.

Histopathologic simulators of BCC Of the other basaloid tumors that may simulate BCC (Table 108.7), adnexal neoplasms (see Ch. 111) cause the most difficulties, in particular trichoblastoma. In contrast to BCC, clefts in trichoblastoma are located within the stroma and not in direct proximity to the tumor, and follicular germs and papillae, simulating rudimentary hair follicles, are commonly found. Positive immunostaining with PHLDA1, a marker of epithelial follicular stem cells, favors the diagnosis of trichoblastoma and trichoepithelioma over BCC, although exceptions exist.

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Fig. 108.23 Basal cell carcinoma (BCC): range of histopathologic findings. A Superficial type with a few basaloid buds and stromal retraction spaces. B A single basaloid aggregation with all the morphologic findings (e.g. peripheral palisading of nuclei, retraction between the tumor and surrounding stroma) characteristic of a superficial BCC. C Nodular BCC with large, partly confluent aggregations of basaloid cells as well as a few cystic spaces. D Nodular aggregations of basaloid cells with peripheral palisading and retraction spaces commonly seen in conventional nodular BCCs. E Nodular aggregations of basaloid cells with mucin deposition within the epithelial component, referred to as mucinous BCC. F Micronodular BCC characterized by numerous, densely packed, small nodular aggregations of basaloid cells. G Pigmented BCC with nodular aggregations of basaloid cells that contain brown melanin pigment. H Basosquamous BCC in which both basaloid cells with peripheral palisading and eosinophilic cells with slightly pleomorphic nuclei and foci of keratinization (“horn pearls”) are present. I Morpheaform BCC with numerous basaloid strands and cords with an irregular jagged outline embedded within a fibrous stroma. J Fibroepithelial BCC (fibroepithelioma of Pinkus) with a fenestrated pattern of anastomosing epithelial cords. Courtesy, Lorenzo Cerroni, MD.  

Basaloid induction within dermatofibromas and nevus sebaceus may also simulate BCC histopathologically.

TREATMENT The National Comprehensive Cancer Network (NCCN) has established guidelines of care for BCCs and SCCs. These guidelines are not strictly evidence-based, but developed through consensus by a working group of expert clinicians who review, interpret, and synthesize the existing literature. For the most current version, see www.nccn.org/ professionals/physician_gls/f_guidelines.asp.

Evaluation and Risk Assessment

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Evaluation of a suspected NMSC requires a history, physical examination, and biopsy of the suspicious lesion. The history should assess duration, rate of growth, and any prior therapy, as well as any personal or family history of prior skin cancers. Localized neurologic symptoms, although rare, may suggest the possibility of perineural involvement. Any history of prior radiation therapy to the area should be elicited. Current medical problems (e.g. chronic lymphocytic leukemia),

medications (e.g. voriconazole), and allergies should be reviewed. Evidence of immunosuppression (e.g. organ transplantation, underlying hematologic malignancy, immunosuppressive medications, HIV infection) should be determined, and any of the risk factors listed in Table 108.2 identified. Physical examination should include observation and palpation of the tumor to determine exact location and size, and whether it appears to have any connection to underlying structures such as muscle, cartilage, or bone. An assessment should be done of how well or poorly defined the tumor borders are, whether there is physical evidence of prior surgery or other therapeutic interventions (indicating the possibility of recurrence), and if the tumor has developed within a site of chronic inflammation or scar. Careful inspection of the surrounding skin to exclude the presence of satellite lesions is necessary, as is examination of the draining lymph nodes, especially for high-risk tumors, since in-transit76 and distant metastases77 are more common in these patients. In all patients, a full skin examination is required, to exclude other cutaneous malignancies. Skin cancers are often identifiable visually by an experienced clinician. Nevertheless, a properly performed biopsy is essential to the diagnosis and management of any lesion. Numerous biopsy techniques,

Surgical and Destructive Procedures Standard excision Standard surgical excision is effective for most primary BCCs. Mohs micrographic surgery should be considered for tumors where there is a high risk for positive surgical margins and recurrence and when maximal preservation of normal tissue is desired (see below). It has been demonstrated that 4 mm margins are adequate for removal in 98% of cases of non-morpheaform BCC 2 cm, poor differentiation, invasion to fat, and location in high-risk (H) areas associated with a greater risk of subclinical tumor extension. Incompletely excised lesions, especially those involving high-risk sites or those involving the deep margin, should be re-treated. Re-excision or Mohs micrographic surgery are the treatments of choice in these cases82, but radiation therapy may be considered depending upon age, comorbidities, and patient preference (see below).

Curettage with electrodesiccation Curettage with electrodesiccation is frequently used by dermatologists to treat BCCs. Cure rates as high as 97–98% have been reported83, but careful selection of appropriate lesions (e.g. those without extension into the deep dermis) is necessary. In terminal hair-bearing sites, extension of neoplastic cells down follicular structures could also lead to incomplete removal. Curettage and electrodesiccation can be used for small SCCs in situ and well-differentiated primary SCCs 2 cm in diameter.

Curettage alone Barlow et al.85 reported a 5-year cure rate of 96% for 302 biopsy-proven BCCs treated by a single investigator with curettage alone, with minimal complications (hypopigmentation, scarring). Tumors involving more than 50% of the deep edge of the shave biopsy specimen had an increased risk of recurrence. Some clinicians combine curettage with application of topical agents such as imiquimod postoperatively.

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RISK FACTORS FOR RECURRENCE OF NMSC

Low risk

High risk

Area L KRAS

Acneiform nevus with hypopigmented background skin (Munro acne nevus)

FGFR2

Nevus comedonicus

NEK9

A

See Table 62.7 for genes underlying nevus sebaceus and epidermal nevi with epidermolytic hyperkeratosis, acantholytic dyskeratosis, or associated overgrowth syndromes

*Germline mutations in this gene lead to skeletal dysplasia syndromes associated with acanthosis nigricans.

**Germline mutations in this gene are often lethal, but occasionally can lead to a Cowden syndrome-like phenotype.

†Related to benign lentigo, SK or actinic keratosis; the latter can have RAS mutations.

Table 109.1 Somatic activating mutations in benign epidermal tumors. Phosphatidylinositol-4,5-bisphosphate 3-kinase functions downstream of FGFR3. FGFR3, fibroblast growth factor receptor 3; NEK9, NIMA-related kinase 9; PIK3CA, phosphatidylinositol-4,5-bisphosphate 3-kinase, catalytic subunit alpha.  

cells of the rete ridges, and the lesional keratinocytes are larger than those of adjacent, non-involved epidermis. In some (but not all) cases, the melanocytes are slightly increased in number. Melanocytes in DOPA-stained sections of solar lentigines exhibit increased melanogenesis, and these cells have more numerous as well as longer and thicker dendritic processes than the melanocytes of normal skin. The superficial dermis often contains melanophages and occasionally a mild perivascular infiltrate of lymphocytes. Solar elastosis is also prominent. Electron microscopic studies reveal abundant melanosome complexes in keratinocytes which appear to be larger than in normal surrounding skin.

B

Fig. 109.2 Solar lentigines. A Multiple, round to irregularly shaped, brown macules on the dorsal aspect of the hands in an older woman. B The rete ridges have club-shaped extensions and the epidermis between the rete ridges appears thinned. There is increased basal layer pigmentation, but the number of melanocytes is normal or only slightly increased. B, Courtesy, Lorenzo Cerroni, MD.  

Differential Diagnosis The differential diagnosis of a solar lentigo includes an ephelid, macular seborrheic keratosis, pigmented actinic keratosis, lentigo maligna, simple lentigo, junctional melanocytic nevus, and large cell acanthoma. Table 112.1 outlines the similarities and differences between solar lentigines and ephelides. There is essentially a continuum extending from solar lentigo to macular seborrheic keratosis. Demonstration of a keratotic surface with horn cysts is consistent with seborrheic keratosis. Pigmented actinic keratosis is more likely to have a scaly rough

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surface. Lentigo maligna often exhibits greater variation in pigmentation and irregularity of borders compared with solar lentigo, and by dermoscopy, rhomboid structures and grey dots can be seen, in particular on the face. Simple lentigines are often smaller and more heavily pigmented than solar lentigines, and they arise during childhood with less relationship to UVR exposure (see Ch. 112).

Treatment Although a solar lentigo is a benign lesion of cosmetic concern only, it is an indication of chronic UVR exposure which dictates monitoring of the patient for cutaneous carcinomas. Bleaching agents (e.g. hydroquinone) are not effective. Cryotherapy and laser surgery have been shown to be equally effective5, but caution must be used to prevent posttreatment dyspigmentation. Preventive measures include sunscreens, physical barriers, and limitation of sun exposure4.

SEBORRHEIC KERATOSIS Key features ■ Common benign lesions that typically begin to appear during the fourth decade of life ■ Develop anywhere except mucous membranes, palms and soles ■ Tan to black, macular, papular or verrucous lesions; often have a waxy “stuck-on” appearance ■ May become irritated or inflamed ■ Large variation in clinical appearance and can simulate melanocytic neoplasms

and neck in contrast to non-sun-exposed areas in the same subjects. The authors also reported a higher frequency and an earlier age of onset in their Australian study group population compared to a UK study group7. An alteration in the distribution of epidermal growth factor receptors has been observed in SKs. Based upon analysis of androgen receptor polymorphisms, a clonal origin was detected in over half of lesions evaluated, suggesting a neoplasm rather than hyperplasia8. More recently, somatic activating mutations in two genes – FGFR3, which encodes fibroblast growth factor receptor 39, and PIK3CA, whose protein product is the alpha subunit of phosphoinositide-3-kinase10 – have been demonstrated within SKs (see Table 109.1). The enhanced activity of these two proteins leads to increased AKT activity10a. In irritated SKs, apoptosis within areas of squamous differentiation has been implicated as a cause of the irritation11. Although SKs are often clinically verrucous, human papillomavirus (HPV) has been detected infrequently, except in lesions in the genital region. It is likely that these latter lesions actually represent condyloma acuminatum, as the two entities may appear similar both clinically and histologically12.

Clinical Features Although occasionally solitary, SKs more commonly present as multiple, pigmented, sharply marginated lesions. They may be macules, papules or even plaques, depending on their stage of development (Fig. 109.3). Even within the same lesion there may be a marked variation in color. They are usually light brown but may appear white to waxy yellow to brown–black in color. SKs typically evolve from a macule and may progress to become papular or verrucous. Keratotic plugging, a “stuck-on” appearance, and/or overlying scale are helpful features in

Introduction Seborrheic keratoses (SKs) are common benign skin lesions that are almost ubiquitous among older individuals. They develop in hairbearing skin, invariably sparing the mucosal surfaces and the palms and the soles. Thus, SKs can appear on the head and neck, extremities, and trunk, especially the upper back and submammary region (in women). Many clinical and histologic variants of SK have been described, and although they are usually easily recognized clinically, some lesions may prove difficult to diagnose by inspection alone, so biopsy for histopathologic examination may be required. This is especially true when there is a history of recent change or if there is inflammation. Larger dark lesions are sometimes biopsied when there is concern about the possibility of melanoma, but with the advent of dermoscopy, this occurs less frequently.

A

History The date of the initial description of SKs is uncertain. In 1927, Freudenthal delineated their clinical and histologic features.

Epidemiology Autosomal dominant inheritance with incomplete penetrance has been postulated to explain an apparent familial predisposition. Despite their frequent occurrence, there are few statistics on prevalence, gender or racial predilection, or geographic distribution. Almost all epidemiologic studies have noted SKs as coincidental findings. They have been reported to be more common in Caucasian populations and to affect men and women equally6. Their appearance prior to the fourth decade is uncommon. Usually, lesions continue to develop throughout one’s lifetime.

Pathogenesis

1896

Although SKs are common in areas covered by clothing, sun exposure has been implicated in their development. Supporting evidence comes from the more frequent occurrence and earlier age of onset of SKs in individuals residing in tropical climates. An Australian study found a higher prevalence of SKs within sun-exposed areas such as the head

B

Fig. 109.3 Seborrheic keratoses. A Multiple seborrheic keratoses of the anterior trunk that vary in size and color. B Sharply demarcated, pigmented papule and plaques with a papillomatous surface and horn pseudocysts. Note the “stuck-on” appearance.  

Seborrheic Keratosis and Malignancy Instances of malignant neoplasms arising within and adjacent to SKs were reported as early as 193216. Invasive and in situ squamous cell carcinoma (SCC), cutaneous melanoma, basal cell carcinoma (BCC), and keratoacanthoma have all been observed in association with SKs. This likely represents a coincidental neoplasm developing in adjacent skin, although it is possible that the various cell types present in an SK could develop into their respective neoplasms. In theory, the basaloid cells could give rise to BCC, the spinous cells to SCC, and melanocytes to melanoma16. BCC is thought to be the most frequently associated neoplasm16–18, although one prospective histopathologic study only identified SCC in situ in 60 (1.4%) of 4310 specimens accessioned as SK clinically19. In another investigation, 4.6% of SCCs were clinically diagnosed as SKs, and in some of these, features of SK were seen in association with the SCC. The “collision” theory, when two distinct neoplasms develop separately at the same site, was entertained as a possible cause for this occurrence, especially given the prevalence of both of these lesions in the population at large17. Others believe that BCCs and SKs are both derived from the infundibular portion of the hair follicle, cells of which could evolve into either neoplasm, and in some cases, both concurrently. The sign of Leser–Trélat is a rare cutaneous marker of internal malignancy, in particular gastric or colonic adenocarcinoma, breast carcinoma, and lymphoma. It is considered to be a paraneoplastic cutaneous syndrome characterized by an abrupt and striking increase in the number and/or size of SKs occurring before, during or after an internal malignancy has been detected20–22. Associated pruritus has been documented in over 40% of cases and the majority of the lesions are located on the back, followed by the extremities, face and abdomen23,24. Malignant acanthosis nigricans, another paraneoplastic syndrome, may appear at the same time or shortly after the sign of Leser–Trélat in approximately 20% of patients23. Since its initial description in 1900, the validity of the sign of Leser– Trélat as a reliable marker of internal malignancy has been challenged, given the frequency of both neoplasia and SKs in the elderly population, in whom the condition is usually observed24. Its description is also loosely defined, which is problematic as there are no standards for quantifying the number of lesions required for the diagnosis. The few studies investigating SKs and their link with internal malignancy have largely been inconclusive. One retrospective review examined 1752 consecutive patients with the diagnosis of SK, and of these, 62 individuals were diagnosed with an internal malignancy within 1 year before or after the diagnosis of SK. Of those 62 patients, six patients presented with findings consistent with the sign of Leser–Trélat. However, an age- and sex-matched control group demonstrated similar findings25. The pathogenesis of the sign of Leser–Trélat is uncertain, but it is thought to be related to secretion of a growth factor by the neoplasm which leads to epithelial hyperplasia23, as in malignant acanthosis nigricans. To qualify as a paraneoplastic process, the cutaneous findings need to coincide with the presence of the malignancy, resolving when the primary tumor is excised or successfully treated and reappearing with its recurrence or metastasis, i.e. fulfill Curth’s postulates (see Ch. 53).

Pathology There are at least six histologic types of SK: acanthotic, hyperkeratotic, reticulated, irritated, clonal, and melanoacanthoma. Different histologic features are often present in the same lesion, resulting in diverse appearances. There are varying degrees of hyperkeratosis, acanthosis and papillomatosis. Horn pseudocysts, the product of cross-sectioned epidermal invaginations, are highly characteristic, though not invariably present. Generally, the base of an SK lies on a flat horizontal plane flanked by normal epidermis. The characteristic acanthosis is the result of an accumulation of benign squamous and basaloid keratinocytes, typically projecting outward and upward in an irregular fashion. The sharp demarcation at the base of most lesions has been called the “string” sign. The marked papillomatosis and hyperkeratosis are often likened to “church spires” with shadows of retained cornified material at their peaks. The squamous cells of many SKs are representative of those found in the normal-appearing epidermis, but some SKs may contain basaloid cells that have a smaller size, uniform appearance, and large ovalshaped nuclei. When slight intercellular edema is present, intercellular bridges are easily visualized. Cytologic atypia is usually not a feature of most SKs. Mild keratinocyte atypia and mitotic figures, when present, are usually associated with irritation and inflammation. The papillary dermis in most instances is unremarkable. The acanthotic SK is the most common histologic type. It usually presents as a smooth-surfaced, dome-shaped papule. Slight hyperkeratosis and papillomatosis are often present, while the greatly thickened epidermis typically contains a preponderance of basaloid cells (Fig. 109.4A). Papillae may be narrow in some lesions, while others may be composed of interwoven aggregates of epithelial cells surrounding islands of connective tissue in a retiform pattern. Invaginated horn pseudocysts are most prevalent in this variant. Melanin is often increased in the acanthotic type of SK; it is primarily concentrated in keratinocytes and is transferred from neighboring melanocytes. Deeply pigmented lesions contain abundant melanin in basaloid cells. The hyperkeratotic type of SK, also known as a digitated, serrated or papillomatous type, is almost the morphologic reverse of the acanthotic type. Acanthosis is present but there is more prominent hyperkeratosis and papillomatosis (Fig. 109.4B). A preponderance of squamous cells relative to basaloid cells is seen. Abundant pigmentation is unusual, and keratinizing pseudocysts are observed less frequently than in acanthotic SKs. The hyperkeratotic type is the variant often described as having epidermal projections resembling “church spires”, a finding also seen in acrokeratosis verruciformis. The reticulated or adenoid type of SK is characterized histologically by delicate strands of epithelium that extend from the epidermis in an interlacing pattern (Fig. 109.4C). They are composed of a double row or more of basaloid cells that may be hyperpigmented. Horn pseudocysts, although less common than in the acanthotic variant, may be observed. Often, a solar lentigo is seen at the lateral margins of the lesion, supporting the notion that reticulated SK evolves from a solar lentigo. A lymphoid infiltrate is often present in the dermis of inflamed or irritated SKs (Fig. 109.4D). It may be perivascular, diffuse or lichenoid. Spongiosis is often present and there may be necrosis of keratinocytes. Squamous eddies are common findings as well. These consist of whorls of eosinophilic keratinocytes. Irritated SKs often lack the sharply demarcated horizontal base seen with most SKs. Clonal SKs are considered by some to represent a variant of irritated SK. The clonal, or nested, type of SK is characterized by having welldefined nests of loosely packed cells within the epithelium (Fig. 109.4E). The nests are composed predominantly of variably sized keratinocytes that are often paler than adjacent cells and have a uniform appearance. They may also contain melanocytes. There is a rare variant of SK with numerous basal clear cells that histologically can mimic melanoma in situ26–27. However, these clear cells demonstrate negative immunostaining for Melan-A/MART-1 and S100 protein.

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distinguishing SKs from melanocytic neoplasms, noting that occasionally keratotic plugging can be seen in compound and intradermal melanocytic nevi. Individual lesions may be of any size but usually measure about 1 cm in diameter. They can become quite large, i.e. >5 cm in diameter. SKs may become inflamed or irritated due to friction or trauma, or rarely from secondary bacterial infection. Although usually asymptomatic, irritated or inflamed lesions may become tender, pruritic, erythematous, crusted, and rarely, pustular. Sometimes inflammation reflects an underlying diathesis, e.g. psoriasis. Spontaneous regression, although observed, is not a common feature of SKs, even following inflammation. With trauma, the lesion may crumble, explaining reports of SKs “falling off”. Conditions associated with an abrupt appearance or increase in number of lesions, followed by regression when the condition resolves, include pregnancy13, coexisting inflammatory dermatoses (in particular erythroderma)14, and malignancy (next section)15.

Differential Diagnosis Most SKs are easily identified clinically, although there are entities that may have a similar appearance. Conditions thought to be variants of SKs include dermatosis papulosa nigra, stucco keratosis, and inverted follicular keratoses. They are discussed in this chapter under their

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Neoplasms of the Skin

18

A

B

C

D

E

Fig. 109.4 Seborrheic keratoses (SKs) – spectrum of histologic subtypes. A Acanthotic type with lobular hyperplasia with prominent horn cysts. B Papillomatous or hyperkeratotic type with church spires of papillomatosis and hyperkeratosis. C Reticulated or adenoid type with delicate, lace-like strands of interconnecting epithelium and interspersed horn pseudocysts.   D Irritated seborrheic keratosis. Exophytic lesion with papillomatosis, hyperkeratosis, hemorrhagic crust, and dermal inflammation. Mild keratinocyte atypia and mitotic figures, when present in SKs, are usually associated with irritation and inflammation. E Clonal type with Borst–Jadassohn phenomenon characterized by well-demarcated nests of keratinocytes within the epidermis.  

C, D, Courtesy, Lorenzo Cerroni, MD.

1898

respective headings. The clinical differential diagnosis includes solar lentigo, verruca vulgaris, condyloma acuminatum, Bowen disease, SCC, melanocytic nevus, melanoma, acrochordon, and tumor of the follicular infundibulum. Clinical differentiation between macular SKs, solar lentigines, and melanocytic neoplasms such as melanoma may at times be impossible.

Solar lentigines are neither keratotic nor elevated, but some are considered to represent an incipient reticulated type of SK. Over time, solar lentigines can develop into SKs as the buds of pigmented basaloid cells become thicker and there is greater acanthosis. Dermoscopy can prove useful in distinguishing these entities (see Ch. 0). A review of 20 cases of verrucous melanoma demonstrated how difficult it may be to distinguish between benign and malignant tumors. Of interest, 50% of these verrucous melanomas were thought to represent SKs clinically and a histopathologic diagnosis of a benign nevus was assigned to 10%. A broad spectrum of histopathologic findings, including hyperkeratosis, pseudoepitheliomatous hyperplasia, asymmetry and exophytic papillomatous growth pattern, were present in these cases28. Acanthotic and irritated types of SK should be delineated from eccrine poroma. On occasion, SKs may demonstrate “poroid” differentiation. Clinically, poromas are skin-colored, brown, pink or sometimes red papules or nodules that may be pedunculated and multilobular. Histologically, poromas are comprised of homogeneous, small basophilic cells with a delicate fibrovascular stroma and narrow ductal lumina with eosinophilic, PAS-positive, diastase-resistant cuticles (see Ch. 111). Differentiation between an irritated SK, an SCC in situ (Bowen disease), and SCC may require histopathologic examination. An irritated SK may be misdiagnosed as an SCC if atypia is present. Although squamous eddies may be abundant in both tumors, there should be no evidence of involvement of the dermis in irritated SKs. Bowen disease demonstrates a preponderance of atypical keratinocytes with vacuolated cytoplasm, close crowding of nuclei, abundant mitoses and parakeratosis. The adnexal epithelium is also involved. The Borst–Jadassohn pattern of clonal SK is also seen in some examples of Bowen disease. In general, Bowen disease with a clonal or nested pattern has greater atypia of the individual keratinocytes. Melanoacanthoma was originally described by Bloch and named “non-nevoid melano-epithelioma, type 1”29. It is now regarded as a heavily pigmented SK by most authorities. In this variant, melanocytes are distributed throughout the lesion. While the keratinocytes contain melanin, the bulk of the pigment is present within melanocytes, many of which also have long dendrites30. Although the melanocytes are prominent, there is no significant increase in their number. The heavy pigmentation of melanoacanthoma has been explained by the blockage of transfer of melanin to keratinocytes, perhaps leading to an increase in the amount of melanin within melanocytes. Intraoral melanoacanthoma or melanoacanthosis was first described in 1979. These lesions bear a striking clinical resemblance to the melanoacanthoma type of SK. Histopathologically, they are distinct from the cutaneous variant by having only minimal epithelial hyperplasia. Their histologic features are most like those of a heavily pigmented lentigo simplex, with a proliferation of dendritic melanocytes within the basal layer of the epithelium31. Verrucae and condylomata acuminata are hyperplasias caused by HPV. Both can clinically mimic SKs but differ in that they most frequently occur in younger individuals. Verrucae often present as rough papules with pinpoint red or black dots that represent dilated or thrombosed capillary loops at the tips of the underlying dermal papillae. Verrucae favor acral locations, while condylomata acuminata occur in the anogenital region and rarely on the buccal mucosa. HPV has been reported in anogenital lesions with histologic features of SK32 (see above). Koilocytic changes of perinuclear vacuolization with nuclear pyknosis in the superficial epidermis may not be present in some verrucae, but are helpful if present. An SK generally tends to be oriented in a more horizontal than vertical fashion, often has horn pseudocysts, and lacks koilocytes. Tumor of the follicular infundibulum is distinguished from an SK by a superficial distinct plate-like epithelial proliferation. The latter consists of multiple slender epidermal connections composed of basaloid or pale cells, without as much hyperkeratosis as an SK. The reticulated type of SK has a similar pattern but lacks the distinct plate-like growth. Skin-colored SKs, especially in flexural sites, can easily be mistaken for an acrochordon, which has a pedunculated shape and is usually smoother and smaller in size. Other conditions with papillated epidermal hyperplasia histologically are readily distinguished on a clinical basis. Some of these include acanthosis nigricans, epidermal nevus, and confluent and reticulated papillomatosis. Epidermal nevi tend to follow the lines of Blaschko, appearing in a linear arrangement on the extremities and a whorled

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109 Benign Epidermal Tumors and Proliferations

pattern on the trunk. Although histologic sections of epidermal nevi typically exhibit acanthosis and hyperkeratosis, they usually lack the pseudocysts seen in many SKs. Epidermal nevi are also usually apparent at birth or shortly thereafter, unlike SKs, which are seen in adults. Acrokeratosis verruciformis of Hopf has a “church spire” configuration similar to that described for hyperkeratotic SK33, but it is an autosomal dominant disorder and lesions are usually limited to the distal extremities (see Ch. 59). Acanthoma fissuratum may clinically resemble a large SK, but histologic analysis reveals irregular epidermal hyperplasia due to friction.

Treatment Treatment of asymptomatic SKs is largely performed for cosmetic reasons. Symptomatic lesions are usually removed by destruction, curettage or shave excision. The most common method of destruction is cryotherapy. Other methods include electrodesiccation and laser vaporization (e.g. erbium:YAG). Inhibitors of AKT activity have been shown to induce apoptosis in cultured intact seborrheic keratoses and may possibly represent a future topical therapy10a.

A

LICHENOID KERATOSIS Synonyms:  ■ Lichen planus-like keratoses (LPLK)



Solitary lichenoid

keratosis (SLK) ■ Benign lichenoid keratosis (BLK)

Key features ■ A pink to red–brown scaly papule that arises in sun-exposed sites, most commonly the forearms and upper chest ■ Histologically, it appears almost identical to lichen planus, but is distinguished by clinical correlation ■ Represents an inflammatory stage of a solar lentigo, SK or actinic keratosis

History In 1966, two independent groups reported solitary asymptomatic lesions with the histologic features of lichen planus. These two groups referred to these lesions as solitary lichen planus and solitary lichen planus-like keratosis.

Epidemiology Eighty-five percent of lichenoid keratoses (LKs) develop between the ages of 35 and 65 years34. Women are diagnosed with the condition twice as frequently as men, and the vast majority of lesions are seen in Caucasians. Occasionally, patients with a fair complexion and significant photodamage develop multiple LKs.

Pathogenesis LKs have been thought to represent inflammation of a benign lentigo, SK or actinic keratosis. FGFR3, PIK3CA and RAS mutations have been detected in ~50% of LKs, providing support for this relationship (see Table 109.1)35. Because some of the lesions are related to “precancerous” actinic keratoses, the term lichenoid keratosis is preferred over the term benign lichenoid keratosis. Lesions are best referred to as lichenoid actinic keratosis when there is significant keratinocyte cytologic atypia or other classic features of an actinic keratosis, and as irritated SK when a lichenoid infiltrate is associated with other features of an SK. Increased numbers of Langerhans cells have been observed in the epidermis of LKs. This has led to the suggestion that the lichenoid infiltrate of lymphocytes is secondary to a stimulus from an unidentified epidermal antigen. This mechanism is similar to that proposed for lichen planus.

Clinical Features LKs occur primarily as solitary pink to red–brown, often scaly, papules ranging from 0.3 to 1.5 cm in diameter (Fig. 109.5A). An astute clinician can oftentimes suspect the diagnosis before the biopsy is performed.

B

Fig. 109.5 Lichenoid keratosis. A Pink, flat-topped papule in a fair-skinned individual. B A lichenoid infiltrate beneath the epidermis with formation of a few Civatte bodies. Focal compact hyperkeratosis is also present, as well as many intraepidermal lymphocytes. Because the basal layer is often obscured, a careful search for a melanocytic lesion, including lentigo maligna, is warranted.  

A, Courtesy, Jean L Bolognia, MD. B, Courtesy, Lorenzo Cerroni, MD.

LK most closely resembles Bowen disease or BCC, and for this reason, these lesions are frequently biopsied. They are usually asymptomatic, although occasionally patients complain of slight pruritus or stinging36. The most common sites are the forearm and upper chest, with less frequent occurrence on the shins (in women) and other chronically sun-exposed sites. Dermoscopic findings include light brown pseudonetworks due to residual solar lentigo and overlapping pinkish areas related to lichenoid inflammation. Annular granular structures and gray pseudonetworks are present in the early regressing stage, while blue-gray fine dots can be seen in the late regressing stage. Blue-gray dots or globules, representing melanophages, are also considered typical of an LK.

Pathology LK has a lichenoid infiltrate composed primarily of lymphocytes with scattered histiocytes (Fig. 109.5B). Eosinophils and plasma cells are sometimes present. All other elements of an interface dermatitis are observed, including basal vacuolar alteration, melanin incontinence, and colloid bodies. When melanin incontinence is prominent, the term pigmented lichenoid keratosis is sometimes used. Parakeratosis may be seen, unlike in typical lichen planus. Sometimes there is frank separation of the epidermis from the infiltrate in the dermis, giving rise to a subepidermal cleft or blister cavity. Basal cell proliferation is absent, and keratinocyte atypia is either mild or absent. Changes of a solar lentigo or macular SK are often present at the periphery of the specimen. Occasionally, the histopathologic findings in an LK may mimic mycosis fungoides due to the presence of Pautrier-like microabscesses, alignment of lymphocytes along the basal layer, and epidermotropism of the infiltrate. There is also an atrophic variant, and sometimes the lesion may mimic lupus erythematosus histopathologically37. LKs may undergo regression, and thus, histologically, they may be confused with other regressing tumors, especially melanoma. The

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18

regressed LK usually displays a loosely fibrotic papillary dermis with scattered lymphocytes and melanophages. Regressed melanoma typically has a dense band of melanophages with lymphocytes and dilated blood vessels; there is also usually a thin epidermis overlying effaced rete ridges. In states of partial regression, histologic clues to the proper diagnosis remain. The end stages of both tumors may not be distinguishable. Careful search for elements of superficial BCC is also advisable.

Differential Diagnosis Frequently cited clinical impressions include Bowen disease, actinic keratosis, BCC, irritated SK, melanoma (including amelanotic), and melanocytic nevus. Development of inflammation or color change within a pigmented lesion may lead the clinician to suspect an atypical melanocytic nevus or melanoma34. Even when a melanocytic neoplasm is not in the clinical differential diagnosis, the pathologist must take care to ensure that the lichenoid infiltrate is not obscuring melanoma in situ or even melanoma involving the superficial dermis, as the latter may become heavily inflamed. Multiple LKs may be misdiagnosed as a lichenoid drug eruption and can be a cause of pruritus in elderly patients37a. Histologically, LK resembles other conditions with a band-like inflammatory (lichenoid) reaction pattern, including lichen planus, “lichenoid” lupus erythematosus, and lichenoid fixed drug reactions. Clinical correlation is very useful in excluding these conditions, e.g. LK occurs as a single lesion in the vast majority of patients. While lichen planus may be virtually identical to LK histologically, there is usually more wedge-shaped hypergranulosis and less parakeratosis in lichen planus.

Treatment Once the diagnosis of LK is made, no further therapy is necessary. Any remaining lesion may be destroyed by any method.

DERMATOSIS PAPULOSA NIGRA

Fig. 109.6 Dermatosis papulosa nigra. Multiple hyperpigmented papules with typical location on the cheeks.  

However, an FGFR3 mutation was detected in two samples of DPN, supporting its relationship to SKs (see Table 109.1)39.

Clinical Features Pigmented papules are distributed symmetrically on the malar eminences and forehead. Less often, lesions are on the neck, chest and back. The papules usually appear during adolescence and gradually increase in size and number over time, peaking in the sixth decade.

Pathology Key features ■ Most common in individuals of African descent with darkly pigmented skin ■ Multiple hyperpigmented papules on the face ■ Considered to be a variant of SK ■ Cryotherapy can result in hypopigmentation; optimal treatment is scissor snip, curettage or electrodesiccation, when desired

Introduction Dermatosis papulosa nigra (DPN) presents as multiple, hyperpigmented, filiform to sessile, smooth-surfaced papules measuring from 1 to 5 mm. The lesions typically develop on the face of darkly pigmented individuals (Fig. 109.6).

History DPN was first described by Castellani in 1925 based on his observations during visits to Central America and Jamaica.

Epidemiology DPN has a strong familial predisposition and in selected populations, reported incidences in selected study populations have ranged from 10% to 75%. This variability in incidence may be a reflection of sampling, as more lightly pigmented African-Americans are affected less commonly38. In addition to those with African heritage, the condition has also been reported in Filipinos, Vietnamese, Europeans and Mexicans38. Women are twice as likely to be affected as men and rarely it occurs in children. DPN is not related to any systemic disease or syndrome.

Pathogenesis 1900

The cause of DPN is unknown. It tends to have an earlier age of onset than that of SKs, but otherwise is similar and probably is a variant of SK. Some authors view it as a variant of multiple acrochordons.

DPN is characterized by acanthosis, papillomatosis and hyperkeratosis in a pattern quite similar to the acanthotic type of SK. Horn pseudocysts, however, are not a common feature.

Differential Diagnosis The differential diagnosis of DPN includes primarily multiple SKs and acrochordons. Occasionally, verrucae, melanocytic nevi, adnexal tumors (e.g. trichoepitheliomas, fibrofolliculomas, tricholemmomas, basaloid follicular hamartomas, syringomas), and angiofibromas might be considered clinically (see Fig. 111.5).

Treatment Treatment of DPN is generally performed only for cosmetic purposes, although individual lesions may be troublesome. Care should be exercised to avoid treatments that may result in dyspigmentation, so initially it may be best to treat just a small number of lesions. Snip excision with scissors, curettage, and light electrodesiccation are the most common treatment modalities. Hypopigmentation after cryotherapy can be particularly problematic, since melanocytes are more sensitive to freeze damage than are keratinocytes.

STUCCO KERATOSIS Synonym:  ■ Keratosis alba

Key features ■ Gray–white papules ■ Typically on the lower extremities of older adults, especially the ankles ■ Lesions are “stuck on”, and when scraped off, there is minimal bleeding ■ Probably a variant of SK

Pathology

Stucco keratoses are discrete, gray–white papules that are hard and opaque, with the latter reflecting focal accumulations of cornified material. They are usually distributed symmetrically below the knee, especially on the ankle and dorsal aspect of the foot.

Stucco keratoses display prominent orthokeratotic hyperkeratosis and papillomatosis, often imparting a peaked “church spire” pattern. Acanthosis is usually present, but to a lesser degree than in some SKs. The granular layer may be thickened. Horn cysts are usually absent and cytologic atypia is not a feature.

History In 1958, Kocsard was the first to describe stucco keratoses and eight years later he coined the term stucco keratosis to reflect its “stuck-on” appearance. Although early accounts of stucco keratoses described elastotic changes in the upper dermis, this has been shown to represent solar elastosis.

Epidemiology There is no familial predilection for stucco keratoses. They can become more apparent during cold winter months, most likely due to lower humidity and drier skin. They occur primarily in middle-aged to elderly individuals and are usually first observed after 40 years of age. Men are four times more likely to be affected than women. Although precise epidemiologic data are lacking, most descriptions have been in Caucasians. There are no known associated diseases or syndromes.

Pathogenesis Histochemical studies suggest an acquired focal abnormality of keratin­ ization, and a PIK3CA mutation was detected in three of five samples of stucco keratoses39. There was a single case report of multiple HPV types within various keratoses detected by PCR, but the significance of this finding is unclear as HPV DNA is purported to be detectable in at least 20% of normal skin specimens40. Ultrastructural examination has revealed no viral particles41. Sun exposure has been proposed to be a factor in the formation of stucco keratoses, as most affected individuals have evidence of solar damage. However, this may be a reflection of the age and phototype of the patients. Heat and petroleum products such as tar have also been implicated, but none of these theories explain the distribution pattern.

Clinical Features Usually tens, but sometimes hundreds, of gray–white papules are present on the lower extremities of older adults (Fig. 109.7). They favor the ankles and dorsal feet but may extend to the thighs. Occasionally, stucco keratoses appear on the forearms. The lesions are usually small, measuring from 1 to 4 mm; rarely larger plaques are seen. The lesions may be scraped or flicked off the skin surface with a fingernail and there is usually minimal, if any, bleeding. A collarette of dry scale may remain. On occasion, brown, pink and deep yellow shades have been described.

Differential Diagnosis Stucco keratoses may resemble SKs, acrokeratosis verruciformis of Hopf, verruca plana, or epidermodysplasia verruciformis. SKs tend to be larger and pigmented with a surface that appears “greasy”, in contrast to stucco keratoses, which are smaller and have a dry, rough surface. Histologically, stucco keratoses resemble hyperkeratotic SKs and acrokeratosis verruciformis; all three may demonstrate papillomatosis and digitation, giving an appearance similar to “church spires”. As discussed below, the lesions of acrokeratosis verruciformis favor the dorsal aspects of the hands (as well as the feet).

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109 Benign Epidermal Tumors and Proliferations

Introduction

Treatment As with SKs, treatment is generally for cosmetic reasons, although symptomatic lesions may require removal. Curettage, or local destruction with cryosurgery or electrodesiccation, are the usual forms of treatment. Topical application of urea, lactic acid, or retinoids may reduce the hard scale, but the actual lesions persist.

POROKERATOSIS Key features ■ At least six clinical variants of porokeratosis are recognized ■ The prototype, porokeratosis of Mibelli, is a plaque that appears during infancy or childhood, usually on an extremity ■ Disseminated superficial actinic porokeratosis (DSAP) is the most common type, with multiple thin papules appearing in chronically sun-exposed skin of the extremities ■ Linear porokeratosis develops during infancy or childhood and follows the lines of Blaschko ■ Punctate porokeratosis appears during or after adolescence as 1–2 mm papules of the palms and soles ■ Porokeratosis palmaris et plantaris disseminata (PPPD) is a variation of punctate porokeratosis, with lesions also present on other areas of the body ■ Porokeratosis ptychotropica is a rare variant that favors the intergluteal cleft and buttocks ■ Some forms are inherited in an autosomal dominant fashion (e.g. DSAP) ■ A thread-like raised hyperkeratotic border is characteristic and its histologic correlate is the cornoid lamella, a thin column of parakeratosis ■ Development of SCC is possible but rare

Introduction Porokeratosis presents as a keratotic papule or plaque, often with an annular appearance due to its thread-like elevated border that expands centrifugally. The disorder was erroneously named porokeratosis because the column of parakeratosis, known as the cornoid lamella, was initially described as being present over a sweat pore, which of course is a fixed structure that cannot expand peripherally. At least six types of porokeratosis have been recognized (Table 109.2). There are reports of more than one type of porokeratosis developing in the same patient42 and in multiple members of an affected family43.

History Fig. 109.7 Stucco keratoses. Multiple gray–white keratotic papules, primarily on the ankle and dorsal foot.  

In 1893, Mibelli first described what is now considered classic porokeratosis: one to several discrete plaques that may occur anywhere on

1901

SECTION

Neoplasms of the Skin

18

CLINICAL VARIANTS OF POROKERATOSIS

Variant

Clinical features

Porokeratosis of Mibelli

Plaque that arises during infancy or childhood, usually on a distal extremity; often several cm in diameter

Disseminated superficial actinic porokeratosis (DSAP)

Pink to brown papules and plaques with peripheral scale; arise in sun-exposed sites, especially the extensor forearms and shins; usually measure from a few mm to 1 cm in diameter; in some patients, autosomal dominant inheritance

Linear porokeratosis

Streaks along the lines of Blaschko; arise during infancy or childhood; risk of development of squamous cell carcinoma

Punctate porokeratosis

Palmoplantar papules that measure 1–2 mm in diameter; arise during adolescence or adulthood

Porokeratosis palmaris et plantaris et disseminata (PPPD)

Palmoplantar papules in addition to involvement of the trunk, extremities, and even mucous membranes; onset during childhood or adolescence

Porokeratosis ptychotropica

Red to brown papules or plaques in the intergluteal cleft and on the buttocks; there may be coalescence of lesions centrally with scattered papules peripherally

Eruptive disseminated porokeratosis

Abrupt onset of numerous, widespread, inflamed keratoses; may be a sign of an associated malignancy in up to ~30% of patients

Table 109.2 Clinical variants of porokeratosis. Lesions that resemble porokeratosis are also seen in CDAGS syndrome: craniosynostosis and clavicular hypoplasia, delayed closure of the fontanelle, anal anomalies, genitourinary malformations, and skin eruption65.  

the skin or mucous membranes, usually appearing during infancy or childhood. That same year, Respighi reported a superficial and disseminated form of the disease while Chernosky defined disseminated superficial actinic porokeratosis (DSAP) nearly 70 years later. In the 1970s, porokeratosis palmaris et plantaris disseminata (PPPD) and punctate porokeratosis were described. Porokeratosis ptychotropica is the most recently recognized form.

Epidemiology Porokeratosis can be inherited as an autosomal dominant disorder, including DSAP and PPPD, but many cases appear to be sporadic. Porokeratosis of Mibelli affects boys more than girls, but DSAP is more common in women. Although PPPD is inherited in an autosomal dominant manner, it is twice as common in males than in females, perhaps reflecting an environmental factor. Given its relationship to sun exposure, DSAP is more common in Caucasians and is rare in blacks. Linear porokeratosis has been reported in monozygotic twins44, and it has been seen in families with other types of porokeratosis (see below)45.

Pathogenesis

1902

Although porokeratosis is thought to be a disorder of keratinization, the definitive pathogenesis remains unclear. There are multiple genetic loci for porokeratosis46, including 12q24 (POROK2; PPPD), 12q24 (POROK3; DSAP1; mutation in MVK), 15q25–q26 (POROK4; DSAP2)47, 1p31 (POROK5; DSAP3)48, 18p11 (POROK6; DSAP4), 16q24 (POROK7; DSAP; mutation in MVD), 20q13 (POROK8; DSAP; mutation in SLC17A9), and 1q22 (POROK9; DSAP; mutation in FDPS). Of note, POROK1 initially referred to porokeratosis of Mibelli, but now includes other variants such as linear porokeratosis, and it is associated with mutations in PMVK which encodes phosphomevalonate kinase. MVK encodes mevalonate kinase, which may play a role in calciuminduced keratinocyte differentiation and proliferation, and SLC17A9 encodes a vesicular nucleotide transporter49,50. There is ongoing debate regarding two other genes: SSH151 and SART352. An older hypothesis set forth by Reed proposes that lesions of porokeratosis represent an expanding mutant clone of keratinocytes. In

Reed’s view, the characteristic cornoid lamella, seen histologically, represents the border between normal epidermis and the mutant clone of cells. A dermal lymphocytic infiltrate beneath the cornoid lamella or in the central zone of the lesion is considered to represent an immunologic response. Supporting this theory is the finding of abnormal DNA ploidy in keratinocytes of porokeratosis. Triggering factors such as UVR exposure53 or immunosuppression due to AIDS54 or organ transplantation55 may induce porokeratosis in individuals who are genetically predisposed to developing abnormal clones of keratinocytes. A second, less accepted theory suggests that the dermal lymphocytic infiltrate may be directed against an unidentified epidermal antigen and that this population of inflammatory cells releases mediators that provide a mitotic stimulus for epidermal cells56.

Clinical Features Classic porokeratosis of Mibelli is a rare condition, appearing during infancy or childhood as an asymptomatic, small, brown to skincolored keratotic papule that gradually enlarges over a period of years to form a plaque that may measure several centimeters in diameter. There is a raised, sharply demarcated, keratotic, thready border with a longitudinal furrow (Fig. 109.8A). The center of the lesion may be hyperpigmented, hypopigmented, atrophic, and/or anhidrotic. Lesions may occur anywhere on the body, including mucous membranes57, but the extremities are most frequently involved. Multiple lesions may be present, but they are almost always regionally localized and unilateral. Disseminated superficial actinic porokeratosis (DSAP), also referred to as disseminated superficial porokeratosis, is actually more common than the Mibelli type. Small asymptomatic or mildly pruritic keratotic papules, usually ranging from 3 to 10 mm in diameter, appear during the third to fourth decades of life. They are typically skin-colored to tan–brown to pink–red in color. As the lesions progress, they expand radially, and the older, central area becomes atrophic while the welldemarcated border develops a thin, elevated, furrowed keratotic rim (Fig. 109.8B,C,D). Lesions occur in a more widespread pattern than other types of porokeratosis. Disseminated superficial porokeratosis usually involves the extremities bilaterally and symmetrically, sparing the palms, soles and mucous membranes, while the actinic form (DSAP) occurs exclusively in sun-exposed areas, most commonly the shins and extensor forearms. More widespread involvement may also occur, including the upper arms, upper trunk and thighs, but there is still sparing of non-sunexposed sites. As with idiopathic guttate hypomelanosis, facial sparing is characteristic. Some patients report that lesions of DSAP become more prominent and erythematous during the summer58, and there are reports of patients with psoriasis receiving UVB or PUVA treatments developing DSAP. DSAP may resemble and coexist with actinic keratoses, but, unlike actinic keratoses, DSAP almost always involves the legs and rarely the face whereas patients with actinic keratoses on the legs almost always have them on the face as well59. Rarely, DSAP has been reported in association with hepatitis C infection or systemic lupus erythematosus. Linear porokeratosis arises during infancy or childhood, and it consists of one or more plaques that are similar in appearance to classic porokeratosis; however, the plaques follow the lines of Blaschko, most commonly on the extremities (Fig. 109.8E). Some patients have both DSAP and linear porokeratosis with the latter representing loss-ofheterozygosity, i.e. type 2 mosaicism (see Fig. 62.2). PPPD is uncommon and individual lesions resemble those of porokeratosis of Mibelli except they are smaller and have a less pronounced keratotic border. They may be asymptomatic or pruritic, and generally arise during childhood or adolescence. As the name suggests, the palms and soles are initially affected, but any surface, including mucous membranes, may be involved. Punctate porokeratosis is the most difficult type to diagnosis clinically because of the small size of the lesions. It appears during adolescence or adulthood as small “seed-like” keratotic papules with a peripheral raised rim on the palms and/or soles60 (Fig. 109.8F). Clinically, it may resemble punctate keratoderma, Darier disease, Cowden syndrome and arsenical keratoses, but the presence of a cornoid lamella histologically narrows the differential diagnosis. This is because two

CHAPTER

A

B

C

D

E

F

Benign Epidermal Tumors and Proliferations

109

Fig. 109.8 Porokeratosis – clinical variants. A Porokeratosis of Mibelli on the hand of a child. B Actinic porokeratosis in a renal transplant patient with significant solar damage. Note the narrow, elevated rim. C, D Multiple lesions of disseminated superficial actinic porokeratosis (DSAP) with obvious peripheral keratotic rims; lesions can range in color from light brown to pink. E Several streaks of linear porokeratosis on the lower extremity. F Multiple keratotic papules of the plantar surface due to punctate porokeratosis. G Porokeratosis ptychotropica with pink to brown papules localized to the intergluteal cleft and buttocks. B, C, D, Courtesy, Jean L Bolognia, MD. F, Courtesy, Kalman Watsky, MD; G, Courtesy, César  

Cosme Álvarez Cuesta, MD.

G

palmoplantar disorders that also have parakeratotic columns – spiny keratoderma, where lesions resemble the spines of an old-fashioned music box, and porokeratotic eccrine ostial and dermal duct (PEODD) nevus – are easily discernible. Porokeratosis ptychotropica is an unusual variant in which pruritic, red to brown papules and plaques develop in the intergluteal cleft and on the buttocks (Fig. 109.8G)61. There may be coalescence of lesions centrally. Histopathologically, multiple cornoid lamellae are seen rather than a single peripheral cornoid lamella. Development of SCC within lesions of porokeratosis has been reported in all variants except punctate and ptychotropica. Lesions in older patients, those of longstanding duration, and linear variants all have higher rates of malignant degeneration. DSAP has the lowest risk of malignant change62. SCC generally appears as a papule or plaque arising in contiguity with the individual lesion of porokeratosis, leading to asymmetry. In the setting of immunosuppression, multiple lesions of porokeratosis can appear and they may attain a large size (see Fig. 109.8B)54,55.

Uncommon clinical variants of porokeratosis include a reticular form63 and a follicular variant64. In CDAGS (craniosynostosis and clavicular hypoplasia, delayed closure of the fontanelle, anal anomalies, genitourinary malformations, and skin eruption) syndrome, a very rare autosomal recessive disorder, patients develop erythematous plaques on the face and extremities that histologically resemble porokeratosis (see Table 109.2)65.

Pathology Identification of the cornoid lamella is the sine qua non for the histologic diagnosis of porokeratosis, although it may be seen in other conditions such as verruca vulgaris and actinic keratosis. It is characterized by a thin column of tightly packed parakeratotic cells extending from an invagination of the epidermis through the stratum corneum, often protruding above the surface of the adjacent skin (Fig. 109.9). Under the cornoid lamella, the granular layer is either absent or markedly attenuated, but it is of normal thickness in other areas of the lesion.

1903

SECTION

FLEGEL DISEASE

Neoplasms of the Skin

18

Synonym:  ■ Hyperkeratosis lenticularis perstans

Key features ■ Very rare disorder; possible autosomal dominant inheritance pattern ■ Multiple keratotic papules with a disc-like appearance in a symmetric distribution ■ Predilection for the dorsal aspect of the feet and the distal extremities of adults

Introduction Fig. 109.9 Porokeratosis – histologic features. The cornoid lamella, a narrow column of parakeratotic cells, is the typical histologic feature of porokeratosis. Note both the absence of the granular layer and the vacuolar change at the dermal–epidermal junction beneath the cornoid lamella.  

Dyskeratosis and pyknotic keratinocytes with perinuclear edema are present in the spinous layer beneath the cornoid lamella. The superficial portion of the cornoid lamella trails toward the center of the lesion in a pattern that has been likened to smoke coming out of a moving train as the “clone” of epidermal cells advances centrifugally. The cornoid lamella corresponds to the clinically observed raised keratotic border. The clinician should include this portion of the lesion in the biopsy to establish the diagnosis. Sometimes, cornoid lamellae are found in multiple locations throughout the lesion in addition to the periphery. Compared to classic porokeratosis of Mibelli, the invagination from which the cornoid lamella extends is less pronounced in variants. Corresponding to the less prominent border seen in DSAP, the cornoid lamella in DSAP often does not protrude above the surface of the adjacent stratum corneum. The epidermis in the central portion of a porokeratotic lesion may be normal, hyperplastic or atrophic, with effacement of rete ridges. The dermis contains lymphocytes that may be perivascular, localized beneath the cornoid lamella, or lichenoid in the central portion of the lesion.

Differential Diagnosis Porokeratosis can resemble other annular lesions (see Table 19.1) as well as actinic keratoses, but dermoscopy can assist in detection of the furrowed keratotic rim. Linear porokeratosis may be confused with other linear lesions such as inflammatory linear epidermal nevus, incontinentia pigmenti (stage II) and linear lichen planus (see Ch. 62), but none of these have a cornoid lamella. Although cornoid lamellae can be found in actinic keratoses, in the latter, partial epidermal cytologic atypia is invariably present. Verruca vulgaris often has mounds of parakeratosis that are sometimes identical to cornoid lamellae, but koilocytosis is usually present along with other histologic features of warts. Porokeratotic eccrine ostial and dermal duct nevus is a separate entity (see Ch. 111).

Treatment

1904

Cryotherapy58, topical 5-fluorouracil (5-FU)59, topical retinoids in combination with 5-FU, topical imiquimod, topical tacrolimus66, photodynamic therapy, shave excision, curettage, and depending upon circumstances, linear excision67, and dermabrasion68 have all been used with variable degrees of success. The abnormal clone of keratinocytes must be destroyed lest lesions recur. Porokeratosis is more difficult to eradicate than both actinic keratoses and SKs. In widespread or refractory lesions, administration of oral acitretin may be beneficial, although the disease will recur following its discontinuation69. Photoprotection should be recommended, especially for patients with DSAP and linear porokeratosis.

In 1958, Flegel described this rare disorder in which asymptomatic, disc-shaped, keratotic papules appear most commonly on the distal extremities of adults. The name hyperkeratosis lenticularis perstans refers to the disc or lens shape (lenticularis) of the papules and their persistent nature (perstans).

Epidemiology Flegel disease is possibly inherited in an autosomal dominant pattern, although it also develops sporadically. Lesions are usually not evident until mid to late adulthood, but they have been described in individuals as young as 13 years of age70,71. No racial predilection has been reported.

Pathogenesis By electron microscopy, lamellar granules (Odland bodies) have been shown to be either absent or altered72. The lipid byproducts within lamellar granules influence stratum corneum desquamation, and, if they are absent or abnormal, hyperkeratosis may develop.

Clinical Features In Flegel disease, numerous red-brown keratotic papules appear in a symmetric pattern (Fig. 109.10A). Lesions most commonly develop on the dorsal aspect of the feet and distal legs and arms, including the palms and soles. Involvement of the pinna and oral mucosa has also been described. Individual papules are small, typically measuring from 1 to 5 mm in diameter while lesions on the palms or soles often appear as fine pits. The papules have attached scale which may be more prominent at the peripheral margin. Removal of this scale can result in bleeding. Although lesions are usually asymptomatic, occasionally patients complain of pruritus. Flegel disease has reportedly been associated with endocrine disorders such as diabetes mellitus and hyperthyroidism73.

Pathology The papules consist of a discrete zone of ortho-hyperkeratosis, contrasting with the normal basket-weave cornified layer of the surrounding normal epidermis in most locations (Fig. 109.10B). There is often focal parakeratosis and hypogranulosis. The thin atrophic stratum spinosum is usually sharply indented or depressed at its lateral margins. A lichenoid infiltrate of lymphocytes is often present in the papillary dermis, along with dilated blood vessels74. A slight degree of hyperchromatism or nuclear infoldings, resembling Sézary cells, has been described in some cases of Flegel disease75.

Differential Diagnosis Stucco keratoses present as whitish-gray papules on the dorsal feet and legs, but histologically there is papillomatosis not atrophy of the epidermis. There is no inflammation unless lesions have become irritated. Perforating disorders have more prominent central keratotic plugs instead of disc-shaped hyperkeratosis, and there is a transepidermal elimination of connective tissue (see Ch. 96). With the exception of perforating granuloma annulare, perforating diseases rarely, if ever, occur on the palms or soles. DSAP typically occurs on the legs, but there is a keratotic rim due to the cornoid lamella. Although the dermal

Pathology There is hyperkeratosis, papillomatosis and acanthosis, often with hyperpigmentation. The hyperkeratosis may be quite prominent, and a “church spire” configuration, similar to that described for hyperkeratotic SK and stucco keratosis, is a frequent finding.

Differential Diagnosis Histologic features similar to those of SK include hyperkeratosis, papillomatosis and acanthosis as well as some degree of hyperpigmentation. Clinicopathologic correlation is necessary to distinguish between these disorders.

Treatment Treatment is similar to that described for SKs and stucco keratoses.

A

CHAPTER

109 Benign Epidermal Tumors and Proliferations

depressions on the palms and soles, as well as nail involvement. These observations are not surprising given that mutations in ATP2A2 can lead to Darier disease and acrokeratosis verruciformis (see Fig. 59.1).

CUTANEOUS HORN Synonym:  ■ Cornu cutaneum

Key features

B

Fig. 109.10 Flegel disease. A Multiple symmetric hyperpigmented keratotic papules are present on the shins. B Thinned and flattened epidermis with overlying marked hyperkeratosis and an underlying patchy lichenoid infiltrate within the papillary dermis.  

changes in Flegel disease may overlap with other lichenoid diseases (see Ch. 11), the clinical presentation allows differentiation. Without clinical correlation, cases with lymphocyte atypia could be misdiagnosed as cutaneous T-cell lymphoma.

Treatment Treatment of Flegel disease is problematic as lesions tend to resist all but destructive therapy. Application of topical 5-fluorouracil cream is moderately effective, although it may not be well tolerated because of irritation. Oral retinoids or PUVA in combination with oral retinoids or calcipotriene (calcipotriol) have yielded unsuccessful or inconsistent results.

ACROKERATOSIS VERRUCIFORMIS Key features ■ Multiple small, skin-colored, warty papules primarily on the dorsal aspect of the hands and feet ■ Rare autosomal dominant disorder of keratinization, often associated with Darier disease ■ “Church spire” hyperkeratosis, papillomatosis, and acanthosis

Clinical Features Acrokeratosis verruciformis of Hopf is a rare autosomal dominant disorder, and it is often recognized during early childhood. Multiple small, skin-colored, warty papules appear on the dorsal aspect of the hands and feet and less commonly on the extensor surfaces of the forearms and legs (see Fig. 59.14). It is often seen in patients with Darier disease, and patients with acrokeratosis verruciformis can have small, keratin-filled

■ Clinical term for a white to yellow, hard, keratotic conical lesion; the base may be a papule, plaque or nodule ■ Most commonly in sun-exposed areas and arising from a hyperkeratotic actinic keratosis ■ In situ or invasive SCC is present in up to 20% of lesions ■ Other common causes include verruca and SK

Clinical Features Cutaneous horn is a clinical term for a white to yellow, hard, keratotic conical lesion (Fig. 109.11A) whose base is a papule, plaque or nodule that ranges from a few millimeters to several centimeters in diameter. The histologic correlate is an abnormal accumulation of keratin in an elongated, vertically oriented column overlying an abnormality of the underlying spinous layer. Cutaneous horns may arise anywhere on the body, but favor sun-exposed sites. Men are affected more frequently than women. Individuals with a fair complexion and the elderly are particularly predisposed76.

Pathology A cutaneous horn consists of hyperkeratosis and parakeratosis associated with variable acanthosis (Fig. 109.11B), usually in association with the atypical keratinocytes of an actinic keratosis. Up to 20% of cutaneous horns arise in an in situ or invasive SCC76. Other lesions that may give rise to cutaneous horns include verrucae, SKs, and less commonly, other epithelial neoplasms, including those derived from follicular epithelium, especially tricholemmomas.

Treatment Shave excision with local destruction is the most common treatment. The former must be done deeply enough to allow the pathologist to evaluate the dermis beneath the horn in order to determine if there is an invasive SCC. An elliptical excision can be performed, especially if the base is nodular or indurated. Treatment of AKs and SCCs is outlined in Chapter 108. Cryotherapy alone may fail because the base may not be adequately treated unless the horn is pared first.

CLEAR CELL ACANTHOMA Synonym:  ■ Degos acanthoma

1905

SECTION

Neoplasms of the Skin

18

Fig. 109.12 Clear cell acanthoma. A Welldemarcated, dark red, shiny papule with a wafer-like collarette of scale. B Epidermal hyperplasia consisting of large pale keratinocytes. Note the sharp transition to normal skin. B, Courtesy,

Fig. 109.11 Cutaneous horn. A This cutaneous horn arose from an actinic keratosis. B Striking column of hyperkeratosis with hyperplasia of the underlying epidermis.





Lorenzo Cerroni, MD.

A

A

B

Key features ■ Uncommon, usually solitary, papule or plaque on the leg ■ Lesions are blanchable, erythematous, and discrete; they may have attached “wafer-like” scale at their periphery ■ Psoriasiform histology with well-demarcated zone containing clear to pale keratinocytes that stain positively with PAS

Introduction First described by Degos in 1962, clear cell acanthoma is an uncommon red papule or plaque, usually on the leg. It may be suspected by astute clinicians, but usually a biopsy is required to establish the diagnosis.

Epidemiology Clear cell acanthoma has no gender predilection and generally develops during middle-age, peaking in incidence by 50 to 60 years of age. It has not been described in children and neither an ethnic nor racial preference has been identified. Familial predisposition is rare, although there is one report of a French kinship with multiple affected family members having disseminated lesions77.

Pathogenesis

1906

The etiology of clear cell acanthoma is unknown. Although it was once thought to be induced by crude coal tar and UV light, there is no proof of a link with environmental trauma, drugs, toxic substances or viruses. Given its abundant clear cytoplasm, it was originally thought to exhibit eccrine differentiation, but immunohistochemical and ultrastructural findings are more consistent with tricholemmal differentiation or features of the interfollicular epidermis78,79. It may be regarded as a variant of SK in which there are abundant glycogen-containing keratinocytes80. Others have proposed that clear cell acanthoma may actually be a localized, nonspecific, reactive inflammatory dermatosis. Several benign hyperproliferative dermatoses, including psoriasis, share a cytokeratin staining pattern similar to that seen in clear cell acanthoma.

B

Furthermore, similarities in the histopathologic features between psoriasis and clear cell acanthoma suggest a common abnormality in the maturation of keratinocytes81. However, clear cell acanthomas do not develop following trauma and do not exhibit koebnerization, suggesting they are not simply a variant of localized psoriasis.

Clinical Features Clear cell acanthoma presents as an asymptomatic, erythematous, rounded papule or plaque that appears “stuck on”, similar to an SK (Fig. 109.12A)82. A “wafer-like” scale is often appreciated, especially at the periphery83. The majority of clear cell acanthomas are solitary and on the leg, but they may be found on the face, forearm, trunk and in the inguinal region. Occasionally they are slightly eroded and a serous exudate may be present on the surface. There is often prominent vascularity as in a pyogenic granuloma, but the erythema can be blanched with application of pressure. By dermoscopy, the looped blood vessels within the dermal papillae create red dots in lines. Clear cell acanthomas usually develop slowly, most often over a period of 2–10 years. They range in size from 0.3 to 2 cm in diameter, although rarely larger lesions have been reported, one of which had a diameter of 6 cm. Multiple lesions are also rare, with only about 26 cases reported in the English literature, and these acanthomas may be either few in number or numerous and widespread84. Disseminated forms have been categorized as either discrete (30 lesions)85. One patient developed ~400 lesions84 and another with eruptive acanthomas experienced spontaneous regression86. Clear cell acanthomas with cystic, pigmented or polypoid features have been described, but these are uncommon. They have also been noted to develop in areas of pre-existing dermatoses, within epidermal nevi, after trauma, and following insect bites. SCC in situ has been rarely documented in association with clear cell acanthoma.

CHAPTER

Pathology

109 Benign Epidermal Tumors and Proliferations

Clear cell acanthoma displays a zone of sharply demarcated, thickened epidermis with regular psoriasiform hyperplasia composed of enlarged pale keratinocytes (Fig. 109.12B). The epidermis is eroded and neutrophils extend from the papillary dermis into the stratum spinosum, aggregating in the overlying thin crust. The granular layer is diminished and the rete ridges are elongated. PAS stains the pale cytoplasm of the keratinocytes red. The material that stains with PAS is diastasesensitive, confirming it is glycogen. Electron microscopy also demonstrates abundant glycogen within the cytoplasm. The dermis contains dilated blood vessels and sparse perivascular lymphocytes.

Differential Diagnosis Clear cell acanthoma may be clinically confused with a pyogenic granuloma, traumatized hemangioma, inflamed SK or verruca, BCC, SCC, amelanotic melanoma, or psoriasis; dermoscopy can assist in establishing the diagnosis. Histologically, other clear cell neoplasms may occasionally cause confusion, although the overall psoriasiform pattern of a clear cell acanthoma usually allows for distinction. Tricholemmomas usually appear on the face and consist of an inwardly growing lobule of pale keratinocytes lacking other features of psoriasis. The sebocytes of sebaceous neoplasms have a multiloculated cytoplasm containing lipid instead of glycogen, and they stain positively for epithelial membrane antigen or adipophilin.

Fig. 109.13 Inverted follicular keratosis. An endophytic proliferation of keratinocytes with prominent squamous eddies is seen.  

Treatment Shave excision or curettage combined with electrofulguration is a common and adequate form of treatment. Most lesions do not recur.

INVERTED FOLLICULAR KERATOSIS Key features ■ Asymptomatic, firm, white–tan to pink papule ■ Typically solitary; most commonly on the face and neck of middle-aged and older adults ■ Benign endophytic variant of irritated SK ■ Histologically, squamous eddies and inflammation are common findings

History Helwig was the first to delineate the features of inverted follicular keratosis (IFK) in 1955.

Epidemiology IFK is seen most commonly in middle-aged to older Caucasian individuals. Men are affected twice as frequently as women.

several follicular canals that open to the surface. There may be inflammation. Squamous eddies are commonly seen.

Differential Diagnosis The clinical differential diagnosis of IFK includes verruca, SK, tricholemmoma and other follicular adnexal tumors, BCC, and SCC. Tricholemmoma has a predominance of clear cells, often with a palisade of basal cells and a thickened basement membrane. Rare mitotic figures may be appreciated in an IFK, but overt cellular atypia as in SCC is absent.

WARTY DYSKERATOMA Key features ■ Uncommon, usually solitary papule or nodule with a central keratotic plug ■ Favor the head and neck region ■ Acantholytic dyskeratosis at the base and sides of a cup-like epidermal invagination

Introduction

Pathogenesis

Usually found on the head or neck, warty dyskeratoma is an uncommon solitary papule or nodule with a comedo-like plug and acantholysis with dyskeratosis histologically.

In 1963, Duperrat and Mascaro proposed that the tumor was derived from the infundibulum of the hair follicle, although the cause is unclear.

History

Clinical Features IFK is typically an asymptomatic, firm, white–tan to pink papule. It is found on the face in approximately 85% of cases, in particular on the cheek and upper lip. Other sites within the head and neck region are also affected. IFKs are usually less than 1 cm in diameter, but rarely they may reach up to 8 cm. They are typically stable and persistent lesions, but may regress.

Pathology IFK exhibits an endophytic, somewhat bulbous proliferation of eosinophilic keratinocytes with basaloid or squamous differentiation (Fig. 109.13). The keratinocyte proliferation seems to surround one or

Helwig coined the term “isolated Darier’s disease” in 1954. Three years later, the lesion was given the name warty dyskeratoma to indicate its solitary verrucous nature.

Epidemiology Warty dyskeratomas are uncommon and demonstrate no genetic predisposition. They are more prevalent in men, usually appearing between the fifth and seventh decades of life. They occur more commonly in Caucasians87.

Pathogenesis The pathogenesis of the acantholytic dyskeratosis in warty dyskeratomas has not been elucidated, although abnormal adhesion of

1907

SECTION

Neoplasms of the Skin

18

keratinocytes has been demonstrated. Now that the gene responsible for Darier disease has been cloned, abnormalities in the function of its protein product could potentially be investigated in related entities like warty dyskeratoma.

Treatment

Clinical Features

ACANTHOLYTIC (DYSKERATOTIC) ACANTHOMA

Warty dyskeratoma presents as a solitary (rarely multiple), verrucous, often crusted, skin-colored to red–brown papule or nodule with a central pore containing a keratotic plug. They grow slowly and are located most commonly on the scalp, forehead, temple, cheek, nose or postauricular area. Lesions have been found beneath the nail plate and in the mouth, especially on the hard palate and alveolar ridge. Warty dyskeratomas typically range in size from several millimeters to 2 cm in diameter. Most warty dyskeratomas are asymptomatic, but patients may rarely complain of pruritus or burning. Bleeding and discharge of foul-smelling cornified material may occur. They have been reported to coexist with other skin lesions, including verruciform xanthoma, actinic keratosis, SCC, BCC, and adnexal carcinomas. Malignant degeneration in a warty dyskeratoma has not been reported87.

Pathology It is well circumscribed and usually involves at least one dilated folliculosebaceous unit. There is a central cup-like invagination lined with epithelium displaying acantholysis as well as individual cell necrosis, corps ronds, and grains, most closely resembling Darier disease (Fig. 109.14). The central crater is filled with cornified debris. Villous-like papillae, sometimes composed of only a single layer of basal cells, often project upward from the invaginated hyperplastic base.

Given its benign nature, treatment depends upon the clinical situation. Lesions are often biopsied to exclude the possibility of a malignancy.

Key features ■ Often a solitary papule on the trunk of adults; may present as multiple lesions in the genital area ■ Variant of a solitary keratosis with histopathologic findings of acantholysis, with or without dyskeratosis, in a hyperplastic epidermis with an overall flat architecture An acantholytic (dyskeratotic) acanthoma is usually a solitary papule on the trunk of adults, and biopsy is often performed to exclude a BCC. Occasionally, there are multiple lesions in the genital area. Histologically, there is acantholysis with or without dyskeratosis. Unlike warty dyskeratoma, there is neither a cup-shaped architecture nor an association with a hair follicle. In contrast to acantholytic actinic keratosis, there is no keratinocyte atypia.

EPIDERMOLYTIC ACANTHOMA Key features

Differential Diagnosis Warty dyskeratomas may resemble other epithelial neoplasms and proliferations such as a verruca, epidermal inclusion cyst, SK, hypertrophic actinic keratosis or SCC. Histologically, other conditions with suprabasilar acantholytic dyskeratosis must be excluded, such as Darier disease, Grover disease, Hailey–Hailey disease, acantholytic acanthoma, familial dyskeratotic comedones, acantholytic actinic keratosis, and acantholytic SCC. Most of these entities are quite different clinically.

■ Discrete keratotic papules in adults, with epidermolytic hyperkeratosis seen histologically ■ Two varieties: an isolated form and a disseminated form

Epidemiology Epidermolytic acanthomas may appear any time during adulthood. No particular race or gender is favored. There are no reports of familial cases.

Pathogenesis Because its clinical and histologic features may resemble those of verrucae, a viral origin was originally suspected, but HPV DNA has not been detected in the lesions88. Genetic mutations and exogenous factors such as UVR, other viruses89, and trauma90 have all been suggested as causes of acquired epidermolytic hyperkeratosis. Other theories include increased keratinocyte metabolic activity and aberrant keratin gene expression91.

Clinical Features The isolated form was initially described in 1970, while the disseminated form was described in 1973. Both forms present as pigmented keratotic papules that may resemble verrucae or SKs (Fig. 109.15A). Individual lesions are generally 1 cm or less in diameter. When isolated, they may appear on any body site. Discrete lesions, when in a cluster, are still categorized as the isolated variant. The disseminated form has a predilection for the trunk, especially the back92; it has also been reported in the genital region where it can mimic condylomata acuminata93. Lesions are usually asymptomatic, but they may be pruritic.

Pathology

Fig. 109.14 Warty dyskeratoma. A cup-shaped invagination with a central keratotic plug. The lower portion of the wall has multiple villi. The epithelium demonstrates acantholysis and dyskeratosis (inset). Courtesy, Lorenzo Cerroni, MD.  

1908

The histologic pattern of epidermolytic hyperkeratosis (Fig. 109.15B) consists of four components: clear spaces of varying size surrounding nuclei in the stratum spinosum and stratum granulosum indistinct cellular boundaries consisting of reticulated, lightly staining material a markedly thickened granular zone containing an increased number of small and large, irregularly shaped, basophilic keratohyaline-like bodies compact hyperkeratosis.

• • • •

CHAPTER

A

Benign Epidermal Tumors and Proliferations

109

A

B

Fig. 109.16 Large cell acanthoma. A Well-demarcated, thin, pink–brown plaque. B Slight epidermal hyperplasia with foci of enlarged keratinocytes centrally.  

B

Fig. 109.15 Solitary epidermolytic acanthoma. A Keratotic papulonodule on the chest. B Marked hyperkeratosis and epidermolytic hyperkeratosis within the underlying epidermis.  

History The basal layer is normal. Epidermolytic acanthomas generally demonstrate more papillomatosis than is typically seen in other conditions with the histologic pattern of epidermolytic hyperkeratosis. There is often a slight superficial perivascular lymphocytic infiltrate in the dermis.

Differential Diagnosis Clinically epidermolytic acanthomas resemble verrucae and SKs. Because they do not have a characteristic clinical appearance, the diagnosis is not usually made until after a biopsy is performed. Epidermolytic hyperkeratosis is a histologic finding common to several conditions, including epidermolytic ichthyosis (bullous congenital ichthyosiform erythroderma) as well as particular forms of epidermal nevi and palmoplantar keratoderma. It is seen incidentally in normal skin and in lesions such as follicular cysts, SKs, atypical nevi, actinic keratoses, and cutaneous horns92.

Treatment Treatment is not required as the lesions are benign. Destruction, shave excision or linear excision is successful, although recurrence may follow superficial removal.

LARGE CELL ACANTHOMA Key features ■ Skin-colored, hyperpigmented, or hypopigmented papule or plaque ■ Located on sun-exposed skin of older individuals ■ Likely a variant of solar lentigo or SK

Introduction Large cell acanthoma is a benign keratinocytic lesion that is asymptomatic and often ignored94. Some dermatopathologists make the diagnosis frequently, while others do not believe that this is a specific entity.

Pinkus first described the lesion in 1967 during a lecture on benign epidermal neoplasms in which he coined the term95.

Epidemiology Large cell acanthomas most commonly arise in sun-damaged skin of middle-aged to elderly individuals, with ages at diagnosis ranging from 30 to 90 years and a mean age in the mid-60s. Women have a slightly higher incidence and most affected patients are Caucasian95.

Pathogenesis The pathogenesis of large cell acanthoma is unknown. Genetic studies have demonstrated low-grade aneuploidy, a finding typically associated with malignancy. Nevertheless, large cell acanthoma has generally been considered to be clinically benign. Some investigators have proposed that it is a variant of Bowen disease96. Still others classify it as a variant of solar lentigo in a stage evolving into a reticulated SK or lichen planuslike keratosis97,98.

Clinical Features It typically presents as a solitary, sharply demarcated, skin-colored, hyperpigmented or hypopigmented papule or plaque (Fig. 109.16A). These acanthomas are most commonly located on the face or neck, including the eyelid, but can be extrafacial96. Rarely, multiple lesions are scattered on the extremities. As it is asymptomatic and often ignored, the time to diagnosis is quite variable, ranging from 3 months to 15 years94.

Pathology Histologically, large cell acanthomas are well demarcated, with uniformly large keratinocytes with abundant cytoplasm and enlarged nuclei (Fig. 109.16B). Mild cytologic atypia may be present. There is variable hyperkeratosis, epidermal rete ridge elongation, papillomatosis, and basal layer hyperpigmentation. Some lesions have minimal hyperkeratosis with flattened rete ridges and only small dermal papillae96.

Differential Diagnosis The differential diagnosis includes solar lentigo (histologically), SK, actinic keratosis, Bowen disease, and melanoma.

1909

SECTION

Neoplasms of the Skin

18

Treatment

Pathogenesis

Shave or simple excision as well as destruction are options.

Epidermal nevi are thought to originate from pluripotent cells in the basal layer of the embryonic epidermis. While mosaicism was thought to be responsible for most epidermal nevi (see Ch. 62), until recently only those nevi with associated epidermolytic hyperkeratosis or acantholytic dyskeratosis had been shown to be due to genetic mosaicism, i.e. mutations in KRT1 or KRT10 versus ATP2A2 being limited to involved epidermis. In 2006, mosaicism for activating mutations in the gene that encodes fibroblast growth factor receptor 3 (FGFR3) was demonstrated in “common” or keratinocytic epidermal nevi, that is, nevi with acanthosis, papillomatosis and hyperkeratosis101. Of note, similar germline mutations in FGFR3 lead to skeletal dysplasia syndromes associated with acanthosis nigricans. As with SKs, activating mutations in PIK3CA have also been detected in epidermal nevi (see Table 62.7)10. Lastly, mosaicism for RAS mutations (HRAS>NRAS>KRAS) has been observed in patients with keratinocytic epidermal nevi102,103, tying together the entities in Table 109.1. While these lesions are classically referred to as “epidermal” nevi, the hamartomatous process also involves at least some portion of the dermis, especially the papillary dermis. This is evident when treatment directed purely at destruction of the epidermis fails to eradicate the lesion, which invariably recurs unless there is ablation or destruction of the upper dermis.

EPIDERMAL NEVUS Synonyms:  ■ Nevus verrucosus



Verrucous nevus



Keratinocytic

nevus

Key features ■ Onset typically within the first year of life with “nevus” referring to a hamartoma of the epidermis and papillary dermis ■ Most commonly, hyperpigmented papillomatous papules and plaques appear in a linear array along the lines of Blaschko ■ In nevus unius lateris (unilateral) and ichthyosis hystrix (bilateral), there are multiple lesions in streaks and whorls ■ Patients with epidermal nevus syndrome have associated abnormalities, especially of the musculoskeletal and central nervous systems

Clinical Features

Introduction Within dermatology, the term nevus (plural, nevi) has three definitions: (1) a congenital lesion (birthmark) or lesion arising early in life; (2) a benign tumor of melanocytes; or (3) a hamartoma. The latter is a benign malformation with an excess or deficiency of structural elements normally found in the affected area, e.g. epidermis, connective tissue, adnexa. In most hamartomas, one element is predominant.

Epidemiology The incidence of epidermal nevus is estimated to be 1 in 1000 infants. The vast majority of epidermal nevi develop sporadically, although familial cases have been reported99,100. There is no gender predilection.

In a review of 131 patients with epidermal nevi, the age of onset ranged from birth to 14 years, with 80% occurring within the first year of life104. The lesions may occasionally become apparent during adulthood105. Epidermal nevi most commonly present as a single linear lesion, but sometimes multiple unilateral or bilateral linear plaques are seen (see Ch. 62). Most lesions consist of well-circumscribed, hyperpigmented, papillomatous papules or plaques that are usually asymptomatic (Fig. 109.17). The earliest lesions may be macular and confused with linear and whorled nevoid hypermelanosis. Rarely, epidermal nevi are hypopigmented. Once developed, the nevi may thicken and become more verrucous, especially over joints and in flexural areas such as the neck. Lesions occur most commonly on the trunk, extremities or Fig. 109.17 Epidermal nevi. A Obvious papillomatosis in a single thin linear plaque; this is the most common clinical presentation. B Larger sized verrucous hyperpigmented plaque.   C Multiple verrucous hyperpigmented plaques that clearly follow the lines of Blaschko. Note the midline demarcation. A, Courtesy, Julie V Schaffer, MD;  

B, Courtesy, Kalman Watsky, MD; C, Courtesy, Kathryn Schwarzenberger, MD.

A

C

1910

B

Pathology At least ten histologic patterns have been observed in epidermal nevi, and more than one may be present in the same lesion107,108. Virtually all are characterized by epidermal hyperplasia, hyperkeratosis, acanthosis, papillomatosis, and variable parakeratosis (Fig. 109.18). Other findings such as epidermolytic hyperkeratosis and focal acantholytic dyskeratosis may be prominent features. Inflammatory linear verrucous epidermal nevus (ILVEN) may have clinical and histologic features very similar to psoriasis (see the following section). Neoplasms such as BCC, SCC and keratoacanthoma may rarely develop in association with epidermal nevi. This malignant change occurs less commonly in epidermal nevi than in the closely related nevus sebaceus. Malignancy, when it does occur, typically develops after puberty109. Examples of BCC arising in epidermal and sebaceous nevi may actually be trichoblastomas, representing a manifestation of the hamartomatous nature of the neoplasm110–112.

Differential Diagnosis Nevus sebaceus, usually found on the head instead of the trunk or extremities, can be considered a subtype of epidermal nevus with additional hamartomatous components of sebaceous and apocrine glands accompanying the papillomatous epidermis (see Ch. 111). Organoid nevi combine features of both epidermal nevus and nevus sebaceus, with variation often depending upon anatomic site (e.g. head and neck versus trunk). Lichen striatus is an acquired lesion, has less papillomatosis and acanthosis as well as more dyskeratosis and spongiosis, and does not persist indefinitely. There are other nevoid conditions that are distributed along the lines of Blaschko and therefore may simulate epidermal nevi, depending on the type and degree of epidermal proliferation. Examples include porokeratotic eccrine ostial and dermal duct nevus, linear lichen planus, and X-linked dominant chondrodysplasia punctata. Small lesions must be distinguished from SKs, verrucae vulgares and psoriasis, especially if there is Koebner phenomena. The

histologic differential diagnosis also includes hyperkeratosis of the nipple.

Treatment Infants and children with epidermal nevi, particularly multiple or extensive lesions, require a thorough evaluation for systemic abnormalities in conjunction with a pediatrician (see Ch. 62). Full-thickness surgical excision is curative, but recurrence is common when only the epidermis is removed (e.g. by shave excision or curettage). Surgical excision of larger lesions can be complicated by hypertrophic scars or keloid formation113. Topical therapies such as corticosteroids, retinoic acid, tars, anthralin, 5-fluorouracil and podophyllin have all been used, but they are of limited benefit. Chronic therapy with oral retinoids has been reported to be effective at decreasing the thickness of systematized epidermal nevi, although it does not result in resolution. Laser ablation may also be undertaken, but to be effective, it must induce scarring and fibrosis of at least the papillary dermis. Therefore, this treatment is often not cosmetically acceptable to patients and test sites are recommended.

CHAPTER

109 Benign Epidermal Tumors and Proliferations

neck104 and their size and distribution are highly variable. Epidermal nevi follow the lines of Blaschko and may have an abrupt midline demarcation. Nevus verrucosus is a term used for localized lesions that have a warty appearance. Nevus unius lateris, first named in 1863 by von Baerensprung, is a variant in which there are extensive unilateral plaques, often involving the trunk. Ichthyosis hystrix (systematized epidermal nevus) is a variant with extensive bilateral involvement, also usually on the trunk106. Epidermal nevus syndrome, a concept proposed by Solomon and Esterly in 1968, is diagnosed when epidermal nevi occur in combination with other developmental anomalies (see Ch. 62). These abnormalities most commonly involve the central nervous or musculoskeletal systems. Excluding cutaneous manifestations, a study of 119 patients with epidermal nevi found that 33% had abnormalities in one organ system, 6% in two, 5% in three, and 5% in five or more. Several overgrowth syndromes can present with epidermal nevi, including Proteus, CLOVES, and PTEN hamartoma-tumor syndromes (see Chs 62 & 104).

INFLAMMATORY LINEAR VERRUCOUS EPIDERMAL NEVUS Synonym:  ■ Dermatitic epidermal nevus

Key features ■ ■ ■ ■ ■

Linear, psoriasiform papules or plaques, usually on one extremity 75% of nevi appear before the age of 5 years Four times more common in girls Usually persists for years despite attempts at treatment Histologically, psoriasiform hyperplasia with alternating parakeratosis and orthokeratosis

Introduction Inflammatory linear verrucous epidermal nevus (ILVEN) is a relatively rare, linear, psoriasiform plaque that usually presents during childhood.

History Altman and Mehregan are credited with the first description of ILVEN in 1971114.

Pathogenesis The definitive cause is unknown. As it bears some resemblance to psoriasis histologically, some hypothesize that the two conditions share a common pathogenesis115. Involucrin, a structural component of mature squamous epithelium, is expressed in increased amounts within the orthokeratotic epithelium of ILVEN, but is minimally expressed within keratinocytes underlying areas of parakeratosis. However, in psoriasis, involucrin is expressed in all layers of the epidermis except the basal layer116. While there are similarities to psoriasis, others propose that ILVEN represents a clonal dysregulation of keratinocyte growth115. Recently, a postzygotic mutation in GJA1 was detected in a case of ILVEN, suggesting that ILVEN may represent a mosaic form of erythrokeratodermia variabilis et progressiva116a.

Clinical Features

Fig. 109.18 Epidermal nevus – most common histologic pattern. Epidermal hyperplasia with papillomatosis and hyperkeratosis.  

ILVEN has a psoriasiform appearance and may be associated with significant pruritus. Scaly, erythematous papules coalesce to form a linear plaque, usually on a limb (Fig. 109.19A), although occasionally the trunk may be involved. Lesions are almost always unilateral. The left leg is reportedly more frequently affected than the right114. In 75% of patients, onset is before the age of 5 years. Isolated instances of adult onset have been reported117 and, rarely, there may be a familial

1911

SECTION

18

Fig. 109.19 Inflammatory linear verrucous epidermal nevus (ILVEN). A Linear erythematous scaly plaques on the medial aspect of the right thigh. Some of the lesions have a psoriasiform appearance. B Epidermal hyperplasia and broad zones of parakeratosis alternating with ortho-hyperkeratosis.

Neoplasms of the Skin



of family history are all features of ILVEN. Patients with linear (nevoid) psoriasis can have or develop classic plaques of psoriasis elsewhere. It has been suggested that ILVEN may be a forme fruste of CHILD syndrome because rarely, ipsilateral skeletal anomalies are seen in patients with ILVEN. Also, although large areas of ichthyosiform erythema characteristically involve one-half of the body with an affinity for skin folds (ptychotropism), patients with CHILD syndrome can have linear keratotic plaques along the lines of Blaschko that have an appearance similar to ILVEN. CHILD syndrome differs histologically from ILVEN in that it has features of verruciform xanthoma with elongated dermal papillae and cells with foamy cytoplasm in the upper papillary dermis120, as well as vacuoles within the cells of the lower stratum corneum ultrastructurally.

Treatment As with other epidermal nevi, ILVEN is difficult to treat. Treatments that are successful in psoriasis are only partially effective for ILVEN119. Surgical excision is effective but results in scarring. The pulsed dye laser has been used successfully in some cases. Its mechanism of action is thought to involve destruction of small blood vessels in the papillary dermis that supply the overlying epidermis121. Combination therapy with topical tretinoin and 5-fluorouracil creams has also been employed with beneficial results, but long-term success can only be achieved with maintenance therapy122. Topical synthetic derivatives of vitamin D3, such as calcipotriene, may also be partially effective123,124. There are anecdotal reports of improvement with TNF inhibitors. Arthritis in association with ILVEN, although rare, can lead to significant morbidity. Early recognition is critical. Treatment is the same as for psoriatic arthritis119.

A

NEVUS COMEDONICUS Synonyms:  ■ Comedo nevus ■ Comedonal nevus

Key features ■ Benign hamartoma, usually arising before the age of 10 years ■ Multiple grouped comedones in a linear array, most commonly on the face, trunk or neck ■ Histologically, epidermal invaginations containing keratin plugs and underdeveloped hair shafts

B

Introduction predisposition . ILVEN has a 4 : 1 female-to-male predominance. Most lesions spontaneously resolve by adulthood118. A possible association of ILVEN with arthritis has been described119.

Nevus comedonicus is a rare hamartoma of the folliculosebaceous unit resulting in numerous dilated, keratin-filled comedones.

Pathology

Kofmann, in 1895, was the first to delineate the features of nevus comedonicus. In 1914, White attempted to change the name to “nevus follicularis keratosis” as he thought the comedo-like lesions did not represent true comedones, as sebaceous glands were either rudimentary or absent in most cases.

100

The psoriasiform histology of ILVEN correlates with its psoriasiform clinical appearance. Epidermal rete ridges are elongated, and broad zones of parakeratosis without an underlying granular layer alternate abruptly with depressed regions of orthokeratosis and hypergranulosis (Fig. 109.19B). There is often exocytosis of lymphocytes and neutrophils into the spongiotic papillomatous epidermis and occasionally Munro microabscesses are seen.

Differential Diagnosis

1912

At least three other variants of epidermal nevi with inflammation have been described, including lichenoid epidermal nevus, psoriasis superimposed on an epidermal nevus, and epidermal nevi in congenital hemidysplasia with ichthyosiform nevus and limb defects (CHILD) syndrome (see Ch. 57). Lichenoid epidermal nevus is typically a verrucous plaque with a lichenoid lymphocytic dermal infiltrate. It is debatable whether lichenoid epidermal nevus truly represents linear lichen planus. The age of onset, distribution, lack of development of additional lesions of psoriasis over time, resistance to therapy, and lack

History

Epidemiology Approximately half of the cases of nevus comedonicus are evident at birth, with others appearing during childhood, usually before the age of 10 years. Onset in adulthood, albeit rare, is often associated with irritation or trauma. There is no racial or gender predilection. Although most cases arise sporadically, familial clustering has been reported125.

Pathogenesis Nevus comedonicus is thought to represent growth dysregulation affecting the mesodermal portion of the pilosebaceous unit. The epithelial-lined invaginations, incapable of forming mature terminal hairs and sebaceous glands, accumulate a soft cornified ostial product resulting in a comedo-like plug. In 1998, FGFR2 mutations were

Clinical Features There is usually a single circumscribed area (Fig. 109.20A) or linear streak composed of clusters of dilated follicular ostia that contain firm, darkly pigmented, cornified material. Occasionally, multiple linear plaques may be seen with midline demarcation. The overall size is variable and can range from a few centimeters in diameter to extensive lesions affecting half of the body. The site most commonly affected is the face, followed by the trunk, neck and upper extremity. These nevi may also arise in areas that are devoid of hair follicles such as the palms, soles and glans penis. When present on the elbows and knees, lesions can be verrucous in appearance. Inflammatory papules and cysts are often admixed with the comedones. Hormonal influences of puberty often worsen the condition. Development of SCC or keratoacanthoma within the nevus is exceedingly rare.

Pathology Nevus comedonicus consists of grouped undeveloped hair follicles, presenting as dilated invaginations filled with cornified debris devoid of hair shafts (Fig. 109.20B). Epidermolytic hyperkeratosis may sometimes be present in the follicular epithelium.

Differential Diagnosis Many skin conditions present with comedones, and these must be differentiated from nevus comedonicus. Infantile acne typically presents on the face between the ages of 3 and 24 months. The comedones, pustules and papules in this disorder are not linear, and they are selflimited. Chloracne is associated with exposure to toxins that lead to the formation of comedones, generally located on both sides of the face and commonly behind the ears. Familial dyskeratotic comedones is a rare autosomal dominant disorder in which comedones arise during childhood or adolescence and are widely scattered on the trunk and extremities without a linear configuration. Histologically, acantholytic dyskeratosis in the comedo wall is seen. The dilated pore nevus resembles nevus comedonicus clinically but differs histologically by containing dilated follicular cysts. Porokeratotic eccrine ostial and dermal duct nevi also may be confused with nevus comedonicus, especially when the latter involves the palms or soles. These lesions are comprised of dilated eccrine ducts containing parakeratotic debris. The keratinocyte cytoplasm is typically vacuolated and the granular layer is absent.

CHAPTER

109 Benign Epidermal Tumors and Proliferations

detected in lesional but not adjacent normal skin of an acneiform nevus referred to as the Munro acne nevus, providing evidence for genetic mosaicism126. In contrast to a classic nevus comedonicus, the Munro acne nevus tends to have pre-existing linear hypopigmentation, peripubertal onset of the acne lesions, and histopathologic findings of an atrophic comedonal wall with prominent associated sebaceous lobules. Of note, patients with Apert syndrome, sporadic or inherited in an autosomal dominant manner and due to mutations in FGFR2, may have comedones and severe cystic acne (see Table 62.7). More recently, mosaic activating mutations in the NIMA-related kinase 9 gene (NEK9) were identified in the affected skin of patients with classic nevus comedonicus126a.

Treatment As with other epidermal nevi, treatment of nevus comedonicus is problematic. Localized lesions can be surgically excised, although it is often difficult to excise larger lesions. Manual comedo extraction, dermabrasion, and the use of keratolytic agents (e.g. salicylic acid, tretinoin, ammonium lactate127) may be helpful, but they are not curative. Isotretinoin is not usually recommended owing to the long-term treatment required, but it may be beneficial in preventing cyst formation. Antibiotics may be necessary to treat secondary infections.

ACANTHOSIS NIGRICANS Acanthosis nigricans is discussed in detail in Chapter 53. Histologically, it may be misinterpreted as an SK, epidermal nevus, or confluent and reticulated papillomatosis, unless appropriate clinical correlation is provided.

NEVOID HYPERKERATOSIS OF THE NIPPLE AND AREOLA

A

This rare condition of unknown etiology affects women more frequently than men. It is usually bilateral, but can be unilateral. Progressive diffuse thickening of the skin of both areolas, which appears hyperpigmented, often begins after puberty. Histopathologically, there is irregular basaloid acanthosis with elongation and anastomosis of rete ridges, orthokeratotic hyperkeratosis, and hyperpigmentation of the basal layer, mimicking a seborrheic keratosis. Nevoid hyperkeratosis may become more evident during pregnancy and it may also occur in men receiving hormonal therapy. Although no uniformly effective treatment exists, there are case reports of improvement with topical retinoids, cryotherapy or radiofrequency ablation.

CONFLUENT AND RETICULATED PAPILLOMATOSIS

B

Fig. 109.20 Nevus comedonicus. A Numerous comedones within a circumscribed area on the right cheek. B Dilated infundibula filled with orthokeratotic keratin. Occasionally, the wall of the comedo will display epithelial hyperplasia (inset). A, Courtesy, Lorenzo Cerroni, MD.  

Synonym:  ■ Confluent and reticulated papillomatosis of Gougerot and Carteaud

1913

SECTION

Neoplasms of the Skin

18

Key features ■ Onset typically during puberty ■ Multiple brown, verrucous, thin papules or plaques in a confluent and/or reticulated pattern, most commonly on the central chest and upper abdomen ■ Oral minocycline is effective in approximately 50% of patients

History Confluent and reticulated papillomatosis of Gougerot and Carteaud (CARP) was first described in 1927.

Epidemiology The typical onset of CARP is during puberty. Young women are affected 2.5 times more frequently than young men, and blacks are twice as likely to have CARP as whites. Occurrence of CARP is mostly sporadic, although familial cases have been reported128.

Pathogenesis Some think CARP may be caused by an endocrine imbalance, especially insulin resistance, because of its association with conditions such as obesity, menstrual irregularities, and diabetes mellitus as well as pituitary and thyroid disorders. In addition, there is a clinical resemblance to acanthosis nigricans. However, most patients are otherwise healthy. Another hypothesis is that CARP is a disorder of keratinization. This theory arose because a number of patients have been successfully treated with topical and systemic retinoids129. An abnormal host response to Malassezia furfur has also been suggested, because this organism is sometimes prevalent within areas of involvement in its yeast (and, less often, hyphal) forms and because treatment with topical selenium sulfide has sometimes been successful130. The majority of cases, however, demonstrate no evidence of M. furfur proliferation.

Clinical Features The initial lesions of CARP are 1–2 mm papules, first appearing in the intermammary area or less frequently the interscapular or epigastric regions. Lesions rapidly enlarge to 4–5 mm and become brown, keratotic, verrucous papules, patches or thin plaques. The papules coalesce and become confluent centrally and reticulated peripherally (Fig. 109.21). There can be involvement of the neck, upper trunk, and other Fig. 109.21 Confluent and reticulated papillomatosis (CARP). Multiple thin hyperpigmented papules of the chest and neck that have become confluent centrally and assume a reticulated pattern peripherally.  

Courtesy, Lorenzo Cerroni, MD.

flexural areas. Oral lesions have not been reported. The eruption is asymptomatic or rarely, mildly pruritic.

Pathology There is hyperkeratosis, acanthosis and papillomatosis. Sparse superficial perivascular infiltrates of lymphocytes are also seen. A characteristic feature is the club-shaped, bulbous epidermal rete ridges that protrude slightly into the papillary dermis with pigment at their bases (“dirty feet”).

Differential Diagnosis CARP can clinically resemble acanthosis nigricans, tinea versicolor, and Darier disease. Acanthosis nigricans has thicker, more velvety plaques involving intertriginous areas; it also lacks the reticulated pattern of CARP. Acanthosis nigricans is most commonly associated with weight gain and disappears with weight loss; some authors refer to this form of the disease as pseudoacanthosis nigricans. Tinea versicolor may be related to CARP because of its brownish scale and association with M. furfur, but it is neither reticulated nor papillomatous. Occasionally, retention hyperkeratosis, also referred to as terra firma-forme, may be confused with CARP, but the former can be easily removed with an alcohol swab. Histologically, CARP may be misinterpreted as an SK, epidermal nevus, acanthosis nigricans, or other papillomatous epithelial proliferation, unless appropriate clinical information is provided.

Treatment Treatment of CARP is often frustrating because it may not respond to therapeutic interventions or recurs after cessation of therapy. No single agent has been uniformly successful at providing long-term resolution. Temporary improvement has been reported with the use of various oral antibiotics (e.g. tetracyclines) and oral retinoids (e.g. isotretinoin, acitretin)129,131 as well as topical salicylic acid, hydroquinone, tacrolimus132, antifungals (e.g. selenium sulfide)130, and 5-fluorouracil. Oral minocycline has been reported to be effective in ~50% of patients, with some reporting no recurrences, while others experienced disease-free intervals for up to 18 months133. Oral retinoids are no more successful than oral antibiotics at maintaining a disease-free state, and given their potential for causing hypertriglyceridemia and teratogenicity, they are generally considered to be second- or third-line agents.

CLEAR CELL PAPULOSIS Key features ■ Extremely rare condition, mainly described in Asian children ■ Hypopigmented macules and papules arranged along the milk lines ■ Histopathologically, large clear cells are scattered along the basal layer of the epidermis and within the malpighian layer

Epidemiology Clear cell papulosis (CCP) is an extremely rare condition that preferentially affects Chinese and other Asian children134.

Pathogenesis The pathogenesis of CCP is unknown. The arrangement of lesions along the so-called milk lines and the appearance of clear cells in lesional skin suggest a histogenetic relationship with Toker cells. Some authors have considered this process as the benign counterpart of extramammary Paget disease135.

Clinical Features 1914

CCP is characterized by multiple, asymptomatic, white macules or papules that are 2–10 mm in diameter and favor the anterior chest, abdomen and lumbar region. The lesions are often arranged along the milk lines. In rare cases, the face may be also involved.

Lesions of CCP are mildly acanthotic and have a slightly disorganized arrangement of epidermal keratinocytes. Numerous clear cells are scattered primarily along the basal layer of the epidermis, but also within its upper layers. These clear cells are larger than adjacent keratinocytes and have cytoplasmic vacuolization due to abundant mucin within their cytoplasm; the latter may be highlighted by PAS, mucicarmine, Alcian blue or colloidal iron stains. Immunohistochemically, clear cells of CCP express carcinoembryonic antigen, cytokeratins (CK7+, AE1/ AE3+, CAM5.2+), epithelial membrane antigen (EMA), and gross cystic disease fluid protein-15 (GCDFP-15), but are negative for expression of CD1a, S100 protein and HMB45134.

sclerosus, achromic verrucae plana, and confetti lesions of tuberous sclerosis (see Table 66.5). Histologically, CCP needs to be distinguished from extramammary Paget disease and pagetoid dyskeratosis. Neoplastic cells of extramammary Paget disease are more atypical and pleomorphic than those of CCP. Pagetoid dyskeratosis is a disorder of keratinization characterized by clear and pale eosinophilic keratinocytes scattered within the epidermis; it is an incidental histopathologic finding without any clinical significance.

Treatment CCP is a benign process and no treatment is necessary. Most patients experience at least a partial regression136.

Differential Diagnosis

Acknowledgment

Clinically, CCP should be differentiated from hypopigmented lesions of tinea versicolor, pityriasis lichenoides chronica, guttate lichen

The authors would like to acknowledge Raymond Barnhill for his contribution to the solar lentigo section of this chapter.

CHAPTER

109 Benign Epidermal Tumors and Proliferations

Pathology

REFERENCES 1. Hafner C, Stoehr R, van Oers JM, et al. FGFR3 and PIK3CA mutations are involved in the molecular pathogenesis of solar lentigo. Br J Dermatol 2009;160:546–51. 2. Bastiaens M, ter Huurne J, Gruis N, et al. The melanocortin-1-receptor gene is the major freckle gene. Hum Mol Genet 2001;10:1701–8. 3. Wang SQ, Rabinovitz H, Oliviero MC. Dermoscopic patterns of solar lentigines and seborrheic keratosis. In: Marghoob AA, Braun B, Kopf AW, editors. Atlas   of Dermoscopy. London: Taylor & Francis; 2005.   p. 60–71. 4. Rhodes AR, Harrist TJ, Momtaz TK. The PUVA-induced pigmented macule: a lentiginous proliferation of large, sometimes cytologically atypical, melanocytes.   J Am Acad Dermatol 1983;9:47–58. 4a.  Lassacher A, Worda M, Kaddu S, et al. T1799A BRAF mutation is common in PUVA lentigines. J Invest Dermatol 2006;126:1915–17. 5. Todd MM, Rallis TM, Gerwels JW, et al. A comparison of three lasers and liquid nitrogen in the treatment of solar lentigines. Arch Dermatol 2000;136:841–6. 6. Verhagen ARHB, Koten JW, Chaddah VK, Patel RI. Skin diseases in Kenya: a clinical and histopathological study of 3,168 patients. Arch Dermatol 1968;98:577–86. 7. Yeatman J, Kilkenny M, Marks R. The prevalence of seborrhoeic keratoses in an Australian population: does exposure to sunlight play a part in their frequency? Br J Dermatol 1997;137:411–14. 8. Nakamura H, Hirota S, Adachi S, et al. Clonal nature of seborrheic keratosis demonstrated by using the polymorphism of the human androgen receptor locus as a marker. J Invest Dermatol 2001;116:506–10. 9. Hafner C, Hartmann A, van Oers JMM, et al. FGFR3 mutations in seborrheic keratoses are already present in flat lesions and associated with age and localization. Mod Pathol 2007;20:895–903. 10. Hafner C, López-Knowles E, Luis NM, et al. Oncogenic PIK3CA mutations occur in epidermal nevi and seborrheic keratoses with a characteristic mutation pattern. Proc Natl Acad Sci USA 2007;104:13450–4. 10a.  Neel VA, Todorova K, Wang J, et al. Sustained Akt activity is required to maintain cell viability in seborrheic keratosis, a benign epithelial tumor. J Invest Dermatol 2016;136:696–705. 11. Pesce C, Scalora S. Apoptosis in the areas of squamous differentiation of irritated seborrheic keratosis. J Cutan Pathol 2000;27:121–3. 12. Leonardi C, Zhu W, Kinsey W, Penneys N. Seborrheic keratoses from the genital region may contain   human papillomavirus DNA. Arch Dermatol 1991;127:1203–6. 13. Garcia R, Bishop M. The rapid onset of seborrheic keratosis of the breast during pregnancy. J Assoc Mil Dermatol 1977;3:13–14. 14. Schwengle L, Rampen F. Eruptive seborrheic keratoses associated with erythrodermic pityriasis rubra pilaris: possible role of retinoid therapy. Acta Derm Venereol 1988;68:443–5. 15. Winkelmann R. Superficial spreading (and disappearing) seborrheic keratosis. Cutis 1999;63:235–7.

16. Díaz-Cascajo C, Reichel M, Sanchez J. Malignant neoplasms associated with seborrheic keratoses.   An analysis of 54 cases. Am J Dermatopathol 1996;18:278–82. 17. Rao B, Freeman R, Poulos E, et al. The relationship between basal cell epithelioma and seborrheic keratosis. A study of 60 cases. J Dermatol Surg Oncol 1994;20:761–4. 18. Zabel R, Vinson R, McCollough M. Malignant melanoma arising in a seborrheic keratosis. J Am Acad Dermatol 2000;42:831–3. 19. Sloan J, Jaworsky C. Clinical misdiagnosis of squamous cell carcinoma in situ as seborrheic keratosis.   A prospective study. J Dermatol Surg Oncol 1993;19:413–16. 20. Vielhauer V, Herzinger T, Korting HC. The sign of Leser-Trélat: a paraneoplastic cutaneous syndrome that facilitates early diagnosis of occult cancer.   Eur J Med Res 2000;5:512–16. 21. Heaphy MR Jr, Millns JL, Schroeter AL. The sign of Leser-Trélat in a case of adenocarcinoma of the lung.   J Am Acad Dermatol 2000;43:386–90. 22. Grob JJ, Rava MC, Gouvernet J, et al. The relation between seborrheic keratoses and malignant solid tumours. A case-control study. Acta Derm Venereol 1991;71:166–9. 23. Yeh J, Munn S, Plunkett T, et al. Coexistence of acanthosis nigricans and the sign of Leser-Trélat in a patient with gastric adenocarcinoma: a case report and literature review. J Am Acad Dermatol 2000;42:357–62. 24. Schwartz R. Sign of Leser-Trélat. J Am Acad Dermatol 1996;35:88–95. 25. Lindelof B, Sigurgeirsson B, Melander S. Seborrheic keratoses and cancer. J Am Acad Dermatol 1992;26:947–50. 26. Neuhaus IM, LeBoit PE, McCalmont TM. Seborrheic keratosis with basal clear cells: a distinctive microscopic mimic of melanoma in situ. J Am Acad Dermatol 2006;54:132–5. 27. Haspeslagh M, De Schepper S, De Wispelaere I, Degryse N. Seborrheic keratosis with basal clear cells: a peculiar microscopic mimic of melanoma in situ.   J Cutan Pathol 2013;40:768–9. 28. Blessing K, Evans AT, al-Nafussi A. Verrucous naevoid and keratotic malignant melanoma: a clinicopathological study of 20 cases. Histopathology 1993;23:453–8. 29. Mishima Y, Pinkus H. Benign mixed tumor of melanocytes and malpighian cells. Arch Dermatol 1960;81:539–50. 30. Simón P, Requena L, Sánchez Yus E. How rare is melanoacanthoma? Arch Dermatol 1991;127:583–4. 31. Tomich C, Zunt S. Melanoacanthosis (melanoacanthoma) of the oral mucosa. J Dermatol Surg Oncol 1990;16:231–6. 32. Li J, Ackerman AB. “Seborrheic keratoses” that contain human papillomavirus are condylomata acuminata. Am J Dermatopathol 1994;16:398–405. 33. Schueller W. Acrokeratosis verruciformis of Hopf. Arch Dermatol 1972;106:81–3. 34. Berger TG, Graham JH, Goette DK. Lichenoid benign keratosis. J Am Acad Dermatol 1984;11:635–8.

35. Groesser L, Herschberger E, Landthaler M, Hafner C. FGFR3, PIK3CA and RAS mutations in benign lichenoid keratosis. Br J Dermatol 2012;166:784–8. 36. Prieto VG, Casal M, McNutt NS. Lichen planus-like keratosis: a clinical and histologic reexamination.   Am J Surg Pathol 1993;17:259–63. 37. Morgan MB, Stevens GL, Switlyk S. Benign lichenoid keratosis. A clinical and pathologic reappraisal of 1040 cases. Am J Dermatopathol 2005;27:387–92. 37a.  Pitney L, Weedon D, Pitney M. Multiple lichen planus-like keratoses: Lichenoid drug eruption simulant and under-recognised cause of pruritic eruptions in the elderly. Australas J Dermatol 2016;57:54–6. 38. Grimes P, Arora S, Minus H, Kenney J. Dermatosis papulosa nigra. Cutis 1983;32:385–6, 392. 39. Hafner C, Landthaler M, Mentzel T, Vogt T. FGFR3 and PIK3CA mutations in stucco keratosis and dermatosis papulosa nigra. Br J Dermatol 2010;162:508–12. 40. Astori G, Lavergne D, Benton C, et al. Human papillomaviruses are commonly found in normal skin of immunocompetent hosts. J Invest Dermatol 1998;110:752–5. 41. Shall L, Marks R. Stucco keratoses. A clinicopathological study. Acta Derm Venereol 1991;71:258–61. 42. Dover JS, Phillips TJ, Burns DA. Disseminated superficial actinic porokeratosis: coexistence with other porokeratotic variants. Arch Dermatol 1986;122:887–9. 43. Lucker GP, Steiflen PM. The coexistence of linear and giant porokeratosis associated with Bowen’s disease. Dermatology 1994;189:78–80. 44. Guillot P. Porokeratose de Mibelli lineaire chez des jumelles monozygotes. Ann Dermatol Venereol 1991;118:519–24. 45. Commens CA, Shumack SP. Linear porokeratosis in two families with disseminated superficial actinic porokeratosis. Pediatr Dermatol 1987;4:209–14. 46. Porokeratosis 1, multiple types; POROK1. Online Mendelian Inheritance in Man 11-20-2015. . 47. Xia K, Deng H, Xia JH, et al. A novel locus (DSAP2) for disseminated superficial actinic porokeratosis maps to chromosome 15q25.1-26.1. Br J Dermatol 2002;147:650–4. 48. Liu P, Zhang S, Yao Q, et al. Identification of a genetic locus for autosomal dominant disseminated superficial actinic porokeratosis on chromosome 1p31.3-p31.1. Hum Genet 2008;123:507–13. 49. Zhang SQ, Jiang T, Li M, et al. Exome sequencing identifies MVK mutations in disseminated superficial actinic porokeratosis. Nat Genet 2012;44:1156–60. 50. Cui H, Li L, Wang W, et al. Exome sequencing identifies SCL17A9 pathogenic gene in two Chinese pedigrees with disseminated superficial actinic porokeratosis.   J Med Genet 2014;51:699–704. 51. Zhang Z, Niu Z, Yuan W, et al. Fine mapping and identification of a candidate gene SSH1 in disseminated superficial actinic porokeratosis. Hum Mutat 2004;24:438. 52. Zhang ZH, Niu ZM, Yuan WT, et al. A mutation in SART3 gene in Chinese pedigree with disseminated

1915

SECTION

Neoplasms of the Skin

18

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inflammatory aetiology? Br J Dermatol 2000;142:842–4. Degos R, Civatte J. Clear-cell acanthoma. Experience of 8 years. Br J Dermatol 1970;83:248–54. Fine R, Chernosky M. Clinical recognition of clear-cell acanthoma (Degos’). Arch Dermatol 1969;100:559–63. Innocenzi D, Barduagni F, Cerio R, et al. Disseminated eruptive clear cell acanthoma – a case report with review of the literature. Clin Exp Dermatol 1994;19:249–53. Naeyaert J, de Bersaques J, Geerts M, et al. Multiple clear cell acanthomas. A clinical, histological, and ultrastructural report. Arch Dermatol 1987;123:1670–3. García-Gavín J, González-Vilas D, Montero I, et al. Disseminated eruptive clear cell acanthoma with spontaneous regression: further evidence of an inflammatory origin? Am J Dermatopathol 2011;33:599–602. Tanay A, Mehregan A. Warty dyskeratoma. Dermatologica 1969;138:155–64. Leonardi C, Zhu W, Kinsey W, et al. Epidermolytic acanthoma does not contain human papillomavirus DNA. J Cutan Pathol 1991;18:103–5. Metzler G, Sonnichsen K. Disseminated epidermolytic acanthoma. Hautarzt 1997;48:740–2. Banky JP, Turner RJ, Hollowood K. Multiple scrotal epidermolytic acanthomas; secondary to trauma? Clin Exp Dermatol 2004;29:489–91. Hirone T, Fukushiro R. Disseminated epidermolytic acanthoma. Acta Derm Venereol 1973;53:393–402. Knipper JE, Hud JA, Cockerell CJ. Disseminated epidermolytic acanthoma. Am J Dermatopathol 1993;15:70–2. Bogale SR, Chan CS, McIntire H, Hsu S. Epidermolytic acanthoma of the scrotum: A rare mimicker of condyloma acuminatum. Dermatol Online J 2011;  17:6. Sanchez Yus E, de Diego V, Urrutia S. Large cell acanthoma. A cytologic variant of Bowen’s disease? Am J Dermatopathol 1988;10:197–208. Pinkus H. Epidermal mosaic in benign and precancerous neoplasia (with special reference to large-cell acanthoma). Acta Dermatol (Kyoto) 1970;65:75–81. Sanchez Yus E, del Rio E, Requena L. Large-cell acanthoma is a distinctive condition. Am J Dermatopathol 1992;14:140–8. Roewert H, Ackerman A. Large-cell acanthoma is a solar lentigo. Am J Dermatopathol 1992;14:122–32. Fraga GR, Amin SM. Large cell acanthoma: a variant of solar lentigo with cellular hypertrophy. J Cutan Pathol 2014;41:733–9. Meschia JF, Junkins E, Hofman KJ. Familial systematized epidermal nevus syndrome. Am J Med Genet 1992;44:664–7. Goldman K, Don P. Adult onset of inflammatory linear verrucous epidermal nevus in a mother and her daughter. Dermatology 1994;189:170–2. Hafner C, van Oers JMM, Vogt T, et al. Mosaicism of activating FGFR3 mutations in human skin causes epidermal nevi. J Clin Invest 2006;116:2201–6. Bourdeaut F, Hérault A, Gentien D, et al. Mosaicism for oncogenic G12D KRAS mutation associated with epidermal nevus, polycystic kidneys and rhabdomyosarcoma. J Med Genet 2010;47:  859–62. Toll A, Gantner S, et al. Keratinocytic epidermal nevi are associated with mosaic RAS mutations. J Med Genet 2012;49:249–53. Rogers M, McCrossin I, Commens C. Epidermal nevi and the epidermal nevus syndrome. A review of 131 cases. J Am Acad Dermatol 1989;20:476–88. Adams B, Mutasim D. Adult onset verrucous epidermal nevus. J Am Acad Dermatol 1999;41:824–6. Loff H, Bardenstein D, Levine M. Systematized epidermal nevi: case report and review of clinical manifestations. Ophthal Plast Reconstr Surg 1994;10:262–6. Su W. Histopathologic varieties of epidermal nevus. A study of 160 cases. Am J Dermatopathol 1982;4:161–70. Submoke S, Piamphongsant T. Clinicohistopathological study of epidermal naevi. Australas J Dermatol 1983;24:130–6. Solomon L, Esterly N. Epidermal and other congenital organoid nevi. Curr Probl Pediatr 1975;6:1–56. Willis D, Rapini RP, Chernosky ME. Linear basal cell nevus. Cutis 1990;46:493–4. Levin A, Amazon K, Rywlin A. A squamous cell carcinoma that developed in an epidermal nevus.

Report of a case and a review of the literature. Am J Dermatopathol 1984;6:51–5. 112. Braunstein B, Mackel S, Cooper P. Keratoacanthoma arising in a linear epidermal nevus. Arch Dermatol 1982;118:362–3. 113. Dellon AL, Luethke R, Wong L, Barnett N. Epidermal nevus: surgical treatment by partial-thickness skin excision. Ann Plast Surg 1992;28:292–6. 114. Altman J, Mehregan A. Inflammatory linear verrucose epidermal nevus. Arch Dermatol 1971;104:385–9. 115. Welch M, Smith K, Skelton H, et al. Immunohistochemical features in inflammatory linear verrucous epidermal nevi suggest a distinctive pattern of clonal dysregulation of growth. Military Medical Consortium for the Advancement of Retroviral Research. J Am Acad Dermatol 1993;29:242–8. 116. Ito M, Shimizu N, Fujiwara H, et al. Histopathogenesis of inflammatory linear verrucose epidermal naevus: histochemistry, immunohistochemistry and ultrastructure. Arch Dermatol Res 1991;283:491–9. 116a.  Umegaki-Arao N, Sasaki T, Fujita H, et al. Inflammatory Linear Verrucous Epidermal Nevus with a Postzygotic GJA1 Mutation Is a Mosaic Erythrokeratodermia Variabilis et Progressiva. J Invest Dermatol 2017;137:967–70. 117. Kawaguchi H, Takeuchi M, Ono H, et al. Adult onset of inflammatory linear verrucous epidermal nevus. J Dermatol 1999;26:599–602. 118. Morag C, Metzker A. Inflammatory linear verrucous epidermal nevus: report of seven new cases and review of the literature. Pediatr Dermatol 1985;3:15–18. 119. Al-Enezi S, Huber A, Krafchik B, et al. Inflammatory linear verrucous epidermal nevus and arthritis: a new association. J Pediatr 2001;138:602–4. 120. Happle R. How many epidermal nevus syndromes exist? A clinicogenetic classification. J Am Acad Dermatol 1991;25:550–6. 121. Altster T. Inflammatory linear verrucous epidermal nevus: successful treatment with the 585 nm flashlamp-pumped pulsed dye laser. J Am Acad Dermatol 1994;31:513–14. 122. Kim J, Chang M, Shwayder T. Topical tretinoin and 5-fluorouracil in the treatment of linear verrucous epidermal nevus. J Am Acad Dermatol 2000;43:129–32. 123. Gatti S, Carrozzo AM, Orlandi A, et al. Treatment of inflammatory linear verrucous epidermal naevus with calcipotriol. Br J Dermatol 1995;132:837–9. 124. Mitsuhashi Y, Katagiri Y, Kondo S. Treatment of inflammatory linear verrucous epidermal naevus with topical vitamin D3. Br J Dermatol 1997;136:134–5. 125. Patrizi A, Neri I, Fiorentini C, Marzaduri S. Nevus comedonicus syndrome: a new pediatric case. Pediatr Dermatol 1998;15:304–6. 126. Munro CS, Wilkie AO. Epidermal mosaicism producing localised acne: somatic mutation in FGFR2. Lancet 1998;352:704–5. 126a.  Levinsohn JL, Sugarman JL, Yale Center for Mendelian Genomics, et al. Somatic mutations in NEK9 cause nevus comedonicus. Am J Hum Genet 2016;98:1030–7. 127. Inoue Y, Miyamoto Y, Ono T. Two cases of nevus comedonicus: successful treatment of keratin plugs with a pore strip. J Am Acad Dermatol 2000;43:927–9. 128. Henning JP, de Wit RFE. Familial occurrence of confluent and reticulated papillomatosis. Arch Dermatol 1981;117:809–10. 129. Buynzeel-Koomen CAFM, de Wit RFE. Confluent and reticulated papillomatosis successfully treated with aromatic etretinate. Arch Dermatol 1984;120:1236–7. 130. Nordby AC, Mitchell AJ. Confluent and reticulated papillomatosis responsive to selenium sulfide.   Int J Dermatol 1986;25:194–9. 131. Lee MP, Stiller MJ, McClain SA, et al. Confluent and reticulated papillomatosis: response to high-dose oral isotretinoin therapy and reassessment of epidemiologic data. J Am Acad Dermatol 1994;31:327–31. 132. Tirado-Sánchez A, Ponce-Olivera RM. Tacrolimus in confluent and reticulated papillomatosis of Gougerot Carteaud. Int J Dermatol 2013;52:513–14. 133. Chang SN, Kim SC, Lee SH, Lee WS. Minocycline treatment for confluent and reticulated papillomatosis. Cutis 1996;57:454–7. 134. Kuo T-T, Chan H-L, Hsueh S. Clear cell papulosis of the skin. Am J Surg Pathol 1987;11:827–34. 135. Yu Y, Sukhatme S, Loo DS. Clear cell papulosis: a connection of clear cells to Toker cells or Paget disease. Arch Dermatol 2009;145:1066–8. 136. Tseng FW, Kuo TT, Lu PH, et al. Long-term follow-up study of clear cell papulosis. J Am Acad Dermatol 2010;63:266–73.

NEOPLASMS OF THE SKIN SECTION 18

Cysts Mary Seabury Stone

Chapter Contents Cysts with a lining of stratified squamous epithelium . . . . . . . 1917 Cysts lined with non-stratified squamous epithelium . . . . . . . 1924 Cysts without an epithelial lining . . . . . . . . . . . . . . . . . . . . 1927

Key features ■ Multiple types of cutaneous cysts have been described ■ Cutaneous cysts present as circumscribed dermal or subcutaneous papules or nodules ■ Histologic features of the cyst lining and the anatomic location determine the type of cyst ■ Cysts may be lined by either stratified squamous epithelium or non-stratified squamous epithelium; cystic structures without an epithelial lining are better classified as pseudocysts ■ Treatment of cysts, when indicated, is primarily surgical

below). These cysts derive from the follicular infundibulum, hence the synonym infundibular cysts (Fig. 110.3). They may be primary, or they may arise from disrupted follicular structures or traumatically implanted epithelium (hence the synonym epidermal “inclusion” cyst). As follicular disruption is important in the pathogenesis of many epidermoid cysts, multiple epidermoid cysts may occur in individuals with a history of significant acne vulgaris. Multiple cysts may also occur in the setting of Gardner syndrome (familial adenomatous polyposis) and in basal cell nevus syndrome1,2. Patients receiving BRAF inhibitors, both non-selective (e.g. sorafenib) and selective (e.g. vemurafenib) can develop multiple epidermoid cysts or milia, often on the face3. Multiple THE THREE MAIN CATEGORIES OF CUTANEOUS CYST

Category

Type

Most common location

Stratified squamous epithelium

Epidermoid (infundibular) cyst Milium Tricholemmal cyst Proliferating tricholemmal cyst Proliferating epidermoid (infundibular) cyst Vellus hair cyst Steatocystoma Cutaneous keratocyst Pigmented follicular cyst Dermoid cyst

Face; upper trunk

INTRODUCTION Cysts are common cutaneous lesions. Patients with cysts may present to clinicians because of medical or cosmetic concerns, or due to discomfort from mechanical irritation or inflammation of the cyst. The definitive diagnosis of a cyst requires histologic examination, as many other dermal and subcutaneous tumors can form cyst-like nodules. Cysts can be classified by anatomic location (as they may occur in virtually any organ of the body), by embryologic derivation, or by histologic features. As the histologic features determine the definitive diagnosis, that scheme will be used in this chapter, which is limited to cutaneous cysts. True cysts have an epithelial lining that may be composed of stratified squamous epithelium or other forms of epithelia. Some “pseudocysts” have no epithelial lining at all. Cutaneous cysts can be divided into three main categories based on the presence or absence and composition of the cyst wall (Table 110.1; Fig. 110.1). Many non-dermatologists refer to epidermoid and pilar cysts as “sebaceous cysts”, believing erroneously that the hydrated white keratinized contents of many epitheliallined cysts is of sebaceous origin. The only true sebaceous cyst is the steatocystoma. The term “sebaceous cyst” is best avoided.

Verrucous cyst

Ear pit cyst Pilonidal cyst Non-stratified squamous epithelium

Ciliated cyst of the vulva Median raphe cyst Omphalomesenteric duct cyst

Epidermoid Cyst inclusion cyst

Epidermoid cysts are the most common cutaneous cysts. They can occur anywhere on the skin, but are most common on the face and upper trunk. These lesions are well-demarcated, skin-colored to yellowish dermal nodules, and they may have a clinically visible punctum representing the follicle from which the cyst is derived (Fig. 110.2). Epidermoid cysts range from a few millimeters to several centimeters in diameter. Tiny superficial epidermoid cysts are known as milia (see

Hidrocystoma • Eccrine • Apocrine Bronchogenic cyst Thyroglossal duct cyst Branchial cleft cyst

Cutaneous ciliated cyst

CYSTS WITH A LINING OF STRATIFIED SQUAMOUS EPITHELIUM

Synonyms:  ■ Infundibular cyst ■ Epidermal cyst ■ Epidermal

110 

Absence of epithelium (pseudocysts)

Mucocele Digital mucous cyst (pseudocyst) Ganglion Pseudocyst of the auricle Cutaneous metaplastic synovial cyst (pseudocyst)

Face Scalp Scalp (favors elderly women) Pelvic (anogenital) Trunk (chest) Trunk; axillae; groin No characteristic location Face (men) Face along embryonic fusion planes, e.g. lateral eyebrow (infants) Face, upper trunk (HPV-infected epidermoid cysts) Preauricular Upper gluteal cleft; sacrococcygeal area Face (lower eyelid, cheek) Face (eyelid margin) Suprasternal notch (infants) Midline anterior neck Lateral neck; preauricular; mandibular (teenagers, young adults) Lower extremities (young women) Labia majora Ventral glans and penile shaft Umbilical; periumbilical Oral mucosa (lower labial) Dorsal aspect of distal phalanx of finger (occasionally toe) Wrist Scaphoid fossa of the ear (adult men) Sites of surgical trauma

Table 110.1 The three main categories of cutaneous cyst.  

1917

Cysts are common cutaneous lesions that typically present as discrete dermal or subcutaneous papules or nodules. Classification is based primarily on the histologic features of the cyst lining, and often they have characteristic anatomic locations. Cysts with a stratified squamous epithelial lining include epidermoid (infundibular) cysts, pilar (tricholemmal) cysts, steatocystomas, and dermoid cysts. Cysts with a non-stratified squamous epithelial lining include hidrocystomas, ciliated cysts, median raphe cysts, bronchogenic cysts, thyroglossal duct cysts, and branchial cleft cysts. Cystic lesions without an epithelial lining include mucoceles, digital mucous cysts and metaplastic synovial cysts, and they are better classified as “pseudocysts”. The clinical and histologic features of cutaneous cysts are discussed in this chapter.

cyst, epidermoid cyst, pilar cyst, milia, steatocystoma, dermoid cyst, eccrine hidrocystoma, apocrine hidrocystoma, mucocele, digital mucous cyst

CHAPTER

110 Cysts

ABSTRACT

non-print metadata KEYWORDS:

1917.e1

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18 Neoplasms of the Skin

APPROACH TO A CYST WITH STRATIFIED SQUAMOUS EPITHELIUM

Cyst with stratified squamous epithelium

Cyst wall with granular layer

+



+

Proliferation of epithelium into surrounding dermis; variable cellular atypia

+

Cyst wall with abrupt keratinization and absent granular layer

Eosinophilic cuticle

Contains hair, sebaceous lobules, eccrine glands, apocrine glands and/or smooth muscle



Sebaceous glands in cyst wall



+ Dermoid cyst

Proliferating epidermoid cyst

Discrete cyst with swollen and pale-staining cells

+

Cutaneous keratocyst

Steatocystoma

Broad anastomosing bands and nodules; cells with abundant eosinophilic cytoplasm; variable cytologic atypia ± horn pearls

Cyst contents

Laminated keratin

Laminated keratin and multiple vellus hairs

Keratin, hairs and granulation tissue

+ +

+

Epidermoid cyst

Milium*

Laminated keratin and pigmented hair shafts

+

+

+

+

+

Ear pit

Pilonidal cyst

Vellus hair cyst

Pigmented follicular cyst

+

Tricholemmal cyst

Proliferating tricholemmal cyst

+ Hybrid cyst

Fig. 110.1 Approach to a cyst with stratified squamous epithelium. *Diameter 1–2 mm.  

Fig. 110.2 Epidermoid cyst. Typical clinical appearance of an epidermoid cyst with a yellowish hue. Two pores are present in this example.  

acute and chronic granulomatous inflammation as well as variable fibrosis may be seen as evidence of prior rupture. In individuals with Gardner syndrome, some cysts have, as a characteristic feature, columns of pilomatricoma-like shadow cells projecting into the cyst cavity1. Infection of the cyst’s epithelium with human papillomavirus can lead to irregular acanthosis with a verrucous appearance of the cyst wall (“verrucous cyst”).

Treatment

scrotal cysts (Fig. 110.4) may lead to scrotal calcinosis via dystrophic calcification4. Non-inflamed epidermoid cysts are usually asymptomatic, but with pressure, cyst contents may be expressed that may have an objectionable odor. Rupture of the cyst wall can result in an intensely painful inflammatory reaction, and this is a common reason for presentation to a physician (Fig. 110.5). Development of a basal cell carcinoma (BCC) or squamous cell carcinoma (SCC) within an epidermoid cyst is a very rare event.

Pathology 1918

Histologic examination shows a cystic cavity filled with laminated keratin lined by a stratified squamous epithelium that includes a granular layer (Fig. 110.6). A surrounding inflammatory response with both

If treatment is desired, excision is curative. Removal may be accomplished by simple excision, or incision and expression of the cyst contents and wall through the surgical defect. If the entire cyst wall is not removed, the cyst may recur. Excision is preferred when the cyst is non-inflamed (“cold”). Inflamed epidermoid cysts may require incision and drainage, and occasionally, antibiotic therapy. Intralesional injections of triamcinolone may speed resolution of the inflammation.

Dilated Pore of Winer Dilated pore of Winer presents as a single dilated comedo, primarily occurring on the face of adults.

Pathology A dilated follicular opening, filled with keratinous debris and lined by squamous epithelium with a granular layer, is seen. The lining is acanthotic with finger-like projections pushing into the surrounding dermis.



PRIMARY CYSTS OF FOLLICULAR ORIGIN

From sebaceous duct: • Steatocystoma

110

Infundibulum Isthmus

From follicular infundibulum: • Epidermoid cyst • Milium • Pigmented follicular cyst • Vellus hair cyst

CHAPTER

Cysts

Fig. 110.5 Inflamed epidermoid cyst. Such painful inflammatory reactions to cyst rupture are a frequent cause for presentation to a physician.

From outer root sheath: • Tricholemmal cyst Inferior portion

Fig. 110.3 Primary cysts of follicular origin. Anatomic origin of cysts derived from the pilosebaceous unit. Adapted from Requena L, Sanchez Yus E. Follicular hybrid cysts. An  

expanded spectrum. Am J Dermatopathol. 1991;13:228–33.

Fig. 110.6 Histology of an epidermoid cyst. Laminated keratin within an epithelial-lined cyst in the dermis. The cyst wall shows epidermal keratinization including a granular layer (inset).  

Pilar Sheath Acanthoma Pilar sheath acanthoma, which presents as a papule with a central comedo-like opening, is discussed in Ch. 111. While pilar sheath acanthomas are not true cysts, some lesions may have a partly cystic architecture.

Treatment If treatment is desired, excision is curative.

Milium

Fig. 110.4 Multiple scrotal cysts. They may be associated with dystrophic calcification. Courtesy, Joyce Rico, MD.  

Differential diagnosis Although there is usually a more papular component, an obvious pore can be seen in a pilar sheath acanthoma, trichoepithelioma, and largepore BCC.

Treatment If treatment is desired, excision is curative.

Milia are small superficial cysts and are quite common, occurring in individuals of all ages. They may originate from the infundibulum of hair follicles or from eccrine ducts, and in the mouth from minor salivary gland ducts or from epithelium entrapped within embryologic fusion planes. Milia present as 1–2 mm, firm, white to yellow, subepidermal papules (Fig. 110.7). Between 40% and 50% of infants will have milia, most commonly on the face. Most milia in newborns will resolve spontaneously during the first 4 weeks of life. Milia in newborns may also occur on the hard palate (Bohn nodules) or on the gum margins (Epstein pearls). These also resolve spontaneously. Milia may occur as a primary phenomenon, especially on the face, or as secondary phenomena following blistering processes (e.g. porphyria cutanea tarda, epidermolysis bullosa acquisita) or superficial ulceration from trauma or cosmetic procedures. Milia may also occur in areas of topical corticosteroid-induced atrophy5 and in follicular mycosis fungoides.

1919

SECTION

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Fig. 110.7 Milia. Tiny (1–2 mm), white, dome-shaped papules on the face.

Fig. 110.8 Tricholemmal cyst versus proliferating tricholemmal cyst. A A trichilemmal cyst is a well circumscribed, mobile, mid dermal nodule with a smooth surface. B A proliferating tricholemmal cyst presenting as an enlarging cystic nodule in an elderly woman. Both types of cyst favor the scalp.

Neoplasms of the Skin



Milia en plaque is characterized by multiple milia within anerythematous edematous plaque, and the most common location is the postauricular area. Numerous milia in an infant may be a sign of oral– facial–digital syndrome type 1, an X-linked disorder that is lethal in males, in which milia are associated with facial and skull malformations, cleft lip and palate, a lobulated tongue, mental retardation and polycystic kidneys; the associated alopecia follows the lines of Blaschko on the scalp. Milia are also seen in the setting of a number of other syndromes, including the BCC-associated syndromes, Rombo syndrome and Bazex–Dupré–Christol syndrome, as well as atrichia with papular lesions, Loeys–Dietz syndrome, basaloid follicular hamartoma syndrome, Basan syndrome, and a subset of Brooke–Spiegler syndrome (Rasmussen syndrome).



$

Pathology Histologic features are those of a small epidermoid cyst with a stratified squamous epithelial lining that includes a granular layer. The cyst contents consist of laminated keratin.

Treatment Milia may be removed by incising the epidermis over the milium with a needle, scalpel or lancet and expressing the milium. The latter can be aided by the use of a comedo extractor. Laser ablation and electrodesiccation are also reported options. For multiple facial milia, topical retinoid therapy may be helpful in reducing the number of new milia and aiding in the ease of removal.

Tricholemmal Cyst Synonyms:   ■ Trichilemmal cyst ■



Pilar cyst



Wen

Isthmus–catagen cyst

Tricholemmal cysts are clinically indistinguishable from epidermoid cysts, but they are fourfold to fivefold less common. Ninety percent of tricholemmal cysts are located on the scalp (Fig. 110.8A). They may be solitary, but frequently are multiple, and they may be inherited as an autosomal dominant trait.

epidermoid cysts, and, therefore, the distinction between a tricholemmal cyst and an epidermoid cyst can often be correctly made at the time of excision.

Pathology

Proliferating Tricholemmal Cyst

The walls of tricholemmal cysts show keratinization analogous to that of the outer root sheath of the hair follicle at the isthmus and the sac surrounding catagen and telogen hairs (hence the synonym isthmus– catagen cyst). Tricholemmal cysts are lined by stratified squamous epithelial cells without visible intracellular bridges that become swollen and pale close to the cystic cavity and show abrupt keratinization without an intervening granular layer (Fig. 110.9). The cyst contents consist of homogeneous, eosinophilic, compact material that can contain foci of calcification. A foreign body giant cell response may surround the cyst if prior wall rupture has occurred.

Treatment 1920

%

Treatment is by excision. Tricholemmal cysts typically “deliver” themselves through an incision without rupture more easily than do

Synonyms:  ■ Proliferating trichilemmal cyst ■ Proliferating tricholemmal tumor ■ Proliferating pilar tumor follicular cystic neoplasm



Proliferating

A proliferating tricholemmal cyst classically occurs as a slow-growing nodule on the scalp (see Fig. 110.8B). Ninety percent occur on the scalp and ~85% occur in women, with a median age of 63 years6. Proliferating tricholemmal cysts vary in size from a few millimeters to up to 25 cm in diameter. These tumors generally behave in a benign fashion, although on occasion, aggressive local growth with recurrences and metastases has been observed6,7. Extremely rarely, spindle cell carcinomas may develop within a proliferating tricholemmal cyst8. Distant

CHAPTER

Cysts

110

Fig. 110.9 Histology of a tricholemmal cyst. The cyst wall shows swollen keratinocytes with abrupt keratinization without formation of a granular layer. Compact, eosinophilic keratin fills the cyst. Courtesy, Luis Requena, MD.  

metastases are rare in proliferating tricholemmal cysts, but over 30 such cases have been reported9.

Pathology The histologic features of a proliferating tricholemmal cyst consist of broad anastomosing bands and nodules of squamous epithelium (Fig. 110.10). The epithelium consists of a proliferation of cells with abundant eosinophilic cytoplasm; the cells undergo abrupt keratinization and form dense homogeneous keratin that fills cystic spaces. There may be areas of epidermoid keratinization with formation of horn pearls as well as areas of foreign body giant cell reaction. One-quarter of cases show an epidermal connection5. Cytologic atypia can vary markedly. Most tumors show well-circumscribed, pushing borders surrounded by compressed collagen. The lack of infiltrative growth into the surrounding stroma and abrupt tricholemmal keratinization helps to differentiate these cysts from SCC. Areas of marked atypia and infiltrative borders are features associated with a potential for aggressive behavior10.

Fig. 110.10 Histology of a proliferating tricholemmal cyst. Well-circumscribed nodules of squamous epithelium in the dermis. Within their central portions, abrupt keratinization is seen. Courtesy, Lorenzo Cerroni, MD.  

Treatment Treatment is by complete surgical excision.

Proliferating Epidermoid Cyst Synonyms:   ■ Proliferating epithelial cyst



Proliferating

infundibular cyst

Proliferating epidermoid cysts were first described in detail in 19956. Unlike proliferating tricholemmal cysts, proliferating epidermoid cysts are observed more commonly in men and only 20% occur on the scalp. They range in size from 0.4 to 15 cm. In the 30 patients reported by Sau et al.6 for whom follow-up was available, 20% of the cysts recurred, some multiple times, and one patient died of intractable local disease. None of the patients developed metastatic disease.

tricholemmal cysts. Degrees of cellularity and atypia are variable, and frank carcinomatous change with an infiltrative growth pattern may be seen.

Pathology

Treatment

Histologically, almost half of cases show an epidermal connection, usually with a narrow opening or connection to a dilated follicle. Most tumors show areas of typical epidermoid cyst wall. In addition, areas of squamous proliferation with squamous eddy formation are seen, with formation of a granular layer and production of loose laminated keratin. The epithelium tends to proliferate peripherally into the surrounding dermis, rather than centrally as seen in proliferating

Fig. 110.11 Eruptive vellus hair cysts. Pigmented small papules on the thigh of a young woman, a few of which are  

Treatment is by complete surgical excision.

Vellus Hair Cysts Vellus hair cysts, described by Esterly, Fretzin and Pinkus in 197711, most commonly present as numerous, small, dome-shaped papules, ranging from skin-colored to darkly pigmented (Fig. 110.11). These cysts are most commonly located on the trunk, and they may be

1921

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Neoplasms of the Skin

18

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Fig. 110.12 Histology of a vellus hair cyst. A cyst shows epidermoid keratinization of its wall as well as laminated keratin and several vellus hairs within its cavity (inset).  

inherited in an autosomal dominant pattern. Multiple lesions are known as “eruptive” vellus hair cysts; occasionally, solitary cysts are seen. Although some lesions may resolve via transepidermal elimination of cyst products, most lesions persist indefinitely. Vellus hair cysts may become inflamed, but in general, they are asymptomatic except for cosmetic concerns. Eruptive vellus hair cysts may be seen in conjunction with steatocystoma multiplex, and both types of cysts have been reported in the setting of pachyonychia congenita (most frequently PC-17; see Ch. 58). Since steatocystomas arise from the sebaceous duct and vellus hair cysts arise from the infundibulum, overlapping features may occur when there is cyst formation at the junction of the sebaceous duct and follicular epithelium.

%

Pathology Histologically, one sees a small cystic structure lined by stratified squamous epithelium with epidermoid (infundibular) keratinization. The cysts contain loose laminated keratin and numerous vellus hairs (Fig. 110.12). A follicle may be found entering the lower portion of the cyst. Visualization of the vellus hairs via microscopic examination of expressed cyst contents allows for a bedside diagnosis.

Treatment Vellus hair cysts may be treated by a number of modalities, including incision and drainage, needle evacuation, puncture followed by forcepsassisted extraction, topical retinoic or lactic acid, and laser ablation.

Steatocystoma

1922

Steatocystomas occur as single (steatocystoma simplex) or multiple (steatocystoma multiplex) lesions. They tend to be a few millimeters to a centimeter in diameter and appear as cysts within the dermis that drain oily fluid if punctured (Fig. 110.13A,B). Steatocystomas are most numerous on the chest and in the axillae and groin. There are unusual facial and acral variants as well as a rare congenital linear form. Steatocystomas persist indefinitely, and they are usually asymptomatic except for cosmetic concerns. Steatocystoma multiplex can be inherited as an autosomal dominant condition, and is due to mutations in the KRT17 gene. It may occur in

&

Fig. 110.13 Steatocystoma multiplex. A,B Numerous cystic papules on the trunk and multiple cystic nodules on the neck. C Histology of steatocystoma. The cyst wall is characterized by an undulated, thin stratified epithelium lacking a stratum granulosum and lined by an eosinophilic cuticle. A search may be required to identify small sebaceous lobules in or immediately adjacent to the cyst wall (inset). C, Courtesy, Lorenzo Cerroni, MD.  

Fig. 110.14 Ear pit.

association with eruptive vellus hair cysts and pachyonychia congenita, most frequently PC-17 (see Fig. 58.11)12,13.



110 Cysts

Courtesy, Julie V Schaffer, MD.

CHAPTER

Pathology Biopsy specimens show a dermal cyst lined by a thin stratified squamous epithelium without a granular layer. The epithelium is surmounted by a thin, irregular, corrugated eosinophilic cuticle (Fig. 110.13C). Small sebaceous lobules are found in or immediately adjacent to the cyst wall. Cysts with the typical corrugated eosinophilic lining of steatocystoma, but with no adjacent sebaceous glands, have been termed cutaneous keratocyst or sebaceous duct cyst.

Treatment Lesions can be excised or incised with removal of the cyst wall.

Cutaneous Keratocyst Synonyms:  ■ Sebaceous duct cyst ■ Isthmic-anagen cyst Cutaneous keratocysts have been reported primarily in patients with the basal cell nevus syndrome. Their clinical appearance is similar to epidermoid cysts and there is no characteristic clinical location.

Pathology These cysts have a stratified squamous epithelial wall without a granular layer and an eosinophilic cuticle, like a steatocystoma. However, no associated sebaceous lobules are seen14.

Follicular Hybrid Cyst

Ear Pit Synonyms:   ■ Preauricular cyst ■ Congenital auricular fistula ■

Preauricular fistula

Synonym:  ■ Hybrid cyst Follicular hybrid cysts are not distinctive clinically, but rather represent a histologic variant of cysts with a stratified squamous lining in which there is transition in the cyst wall between epidermoid keratinization and tricholemmal or matrical keratinization15,16. They were originally described by Brownstein16. Hybrid cysts with features of both an epidermoid cyst and a keratocyst have been associated with the nevoid BCC syndrome17.

Pigmented Follicular Cyst Pigmented follicular cysts, described by Mehregan and Medenica18, are usually solitary and occur primarily on the face of men. They are often deeply pigmented and may be confused clinically with a melanocytic nevus. Histologically, these cysts have a pore-like connection to the epidermis, are lined by stratified squamous epithelium that includes a granular layer, and contain pigmented hair shafts. The clinical presentation, epidermal connection, and pigmented terminal hair shafts rather than vellus hair shafts distinguish the pigmented follicular cyst from vellus hair cysts.

Dermoid Cyst Cutaneous dermoid cysts typically present in an infant along an embryonic fusion plane as a discrete, subcutaneous nodule (see Ch. 64). Dermoid cysts are usually 1–4 cm in diameter. The most common location is around the eyes.

Pathology Histologically, dermoid cysts are lined by stratified squamous epithelium that includes a granular layer. They contain other normal cutaneous structures such as hair, sebaceous lobules, eccrine glands, apocrine glands, and/or smooth muscle.

Ear pits are congenital defects, and they may present as a true cystic nodule or an invagination in the preauricular area (Fig. 110.14). During development, the ear is formed by the fusion of six tubercles: three each from the first two branchial arches. Preauricular cysts reflect defective embryologic fusion with epithelial entrapment. These defects are relatively common, occurring in approximately 0.5–1% of the normal population, and they may be transmitted in an autosomal dominant fashion19. Ear pits are usually unilateral and right-sided. Infection with tenderness and purulent drainage may prompt presentation to a physician. Although ear pits are usually not associated with other significant abnormalities, they can occur in conjunction with deafness or with deafness plus renal anomalies in the branchio-otic syndrome and branchio-oto-renal dysplasia, respectively. Ear pits are also seen in a number of other congenital syndromes that are characterized by major morphologic anomalies, including Treacher Collins syndrome, hemifacial microsomia (Goldenhar syndrome), and cat-eye syndrome20.

Pathology Histologically, preauricular pits or cysts are lined by stratified squamous epithelium with a granular layer.

Treatment If removal is desired, simple excision is curative. Although most ear pits are incidental findings, in a newborn, a physical examination to exclude one of the associated syndromes and an evaluation for hearing loss is indicated. Infected lesions may require antibiotic therapy.

Pilonidal Cyst Synonyms:  ■ Pilonidal sinus ■ Pilonidal disease ■ Barber’s interdigital pilonidal sinus (when located in the interdigital spaces)

Treatment Treatment is by excision. However, as the differential diagnosis includes neural heterotopias, imaging studies may be appropriate prior to excision in order to exclude a connection to the CNS (see Ch. 64).

Pilonidal cysts typically present as an inflamed, painful, cystic swelling in the upper gluteal cleft or sacrococcygeal area, but they have been described in other locations. They most commonly occur in Caucasians

1923

SECTION

18

Fig. 110.15 Apocrine hidrocystoma. A single, slightly bluish, translucent papule on the lower eyelid near the lateral canthus.

Fig. 110.16 Eccrine hidrocystomas. Numerous, tiny, translucent or bluish papules on the lower eyelid (A) or the cheek (B).

Neoplasms of the Skin



and in males who are hirsute21. Pilonidal cysts usually present clinically during the second decade of life. The etiology of pilonidal cysts and sinuses has been a controversial issue. Some authors have argued that they are congenital, essentially representing a dermoid cyst, whereas most authors now believe that the vast majority of lesions are acquired, representing a foreign body response to entrapped hair. A pilonidal cyst can be seen as part of the “follicular inclusion tetrad” which consists of acne conglobata, hidradenitis suppurativa, dissecting cellulitis (perifolliculitis capitis abscedens et suffodiens), and pilonidal cyst (see Ch. 38). Persistent exogenous hairs in the interdigital space of barbers or dog groomers may incite an encompassing epidermal proliferation, giving rise to a pilonidal cyst.



$

Pathology Histologic features are those of an epidermal-lined cyst or sinus tract. Cyst cavities contain hair and keratin debris and are surrounded by granulation tissue and mixed inflammation.

Treatment Treatment is surgical.

%

CYSTS LINED WITH NON-STRATIFIED SQUAMOUS EPITHELIUM Hidrocystoma Synonyms:  ■ Cystadenoma ■ Sudoriferous cyst ■ Moll gland cyst Hidrocystomas typically present as translucent, skin-colored to bluish cysts on the face, although they may occur in other sites. Hidrocystomas are traditionally divided into apocrine and eccrine hidrocystomas by histologic features, and as solitary (Smith type) or multiple(Robinson type). Hidrocystomas may be associated with specific syndromes of ectodermal dysplasia, including Schöpf–Schulz–Passarge syndrome. Apocrine hidrocystomas are usually solitary (Fig. 110.15), whereas eccrine hidrocystomas may be solitary or multiple and are occasionally quite numerous (Fig. 110.16). Eccrine hidrocystomas can enlarge with heat exposure or during the summer and regress with cooler temperatures. In general, eccrine hidrocystomas are thought to develop from cystic dilation of eccrine ducts due to retention of eccrine secretions, while apocrine hidrocystomas are thought to represent adenomas of apocrine sweat gland coils22. Apocrine hidrocystomas are sometimes referred to as cystadenomas, although it has been recommended that this term be reserved for lesions with true papillomatous projections histologically23. Lesions along the lower eyelid margin are also known as Moll gland cysts.

Pathology 1924

Histologically, apocrine hidrocystomas are unilocular to multilocular dermal cysts lined by two layers of epithelial cells that show luminal bulbous protrusions (“snouting”) and decapitation secretion (Fig.

Fig. 110.17 Histology of an apocrine hidrocystoma. A unilocular cyst whose wall shows typical apocrine decapitation secretion (inset).  

110.17). Similarly lined papillary projections may extend into the cyst lumen. Histologic features of eccrine hidrocystomas are those of a uniloculate cyst containing clear fluid, lined by two layers of cuboidal to flattened epithelium (Fig. 110.18). Hidrocystomas that appear by

Treatment Hidrocystomas may be removed by simple excision, including via Gradle scissors, or electrodesiccation. Multiple eccrine hidrocystomas may also be treated with daily application of topical 1% atropine in aqueous solution, although lesions reappear within days of discontinuing therapy24. Flattening after botulinum toxin A injections has been reported25.

Bronchogenic Cyst Cutaneous bronchogenic cysts are most commonly found in the suprasternal notch, and rarely they appear on the anterior neck or chin (see Fig. 64.2). A fistulous tract may connect to the epidermis. Rarely, they present as a pedunculated growth26. Bronchogenic cysts are solitary, and they are typically noted at birth. Malignant transformation is very

rare. They represent respiratory epithelium sequestered during embryologic development of the tracheobronchial tree.

Pathology Bronchogenic cysts are lined by pseudostratified, ciliated, columnar epithelium with interspersed goblet cells. The cyst wall often contains smooth muscle and mucous glands and rarely cartilage.

CHAPTER

110 Cysts

light microscopy to be eccrine include a subset of lesions that stain positively with milk fat globulin 1 and therefore are of apocrine origin22.

Treatment Treatment is by excision.

Thyroglossal Duct Cyst Thyroglossal duct cysts present as midline cystic nodules on the anterior neck in children or young adults (see Fig. 64.2). During development, the thyroid gland descends from the floor of the pharynx to the anterior neck. The tract it forms is known as the thyroglossal duct. Thyroglossal duct cysts arise from remnants of the thyroglossal duct. A tract connecting these cysts to the hyoid bone is frequently present, resulting in characteristic movement of the cyst with swallowing. Rarely, thyroid carcinoma may originate in a thyroglossal duct cyst27.

Pathology Histologically, thyroglossal duct cysts may be lined with cuboidal, columnar, or stratified squamous epithelium, and it may contain some ciliated columnar cells. The characteristic histologic feature is the presence of thyroid follicles, characterized by low cuboidal cells surrounding homogeneous pink material, in the cyst wall (Fig. 110.19).

Treatment Treatment is surgical, with excision of the cyst and any residual tract.

Branchial Cleft Cyst Synonyms:  ■ Lymphoepithelial cyst ■ Lateral cervical cyst Branchial cleft cysts occur in the preauricular area, mandibular region, or along the anterior border of the sternocleidomastoid muscle (see Fig. 64.2). The origin of these cysts is controversial. There are two major theories regarding their origin: they arise from branchial cleft remnants they represent cystic alteration of embryologic epithelium or tonsillar epithelium within cervical lymph nodes28. Branchial cleft cysts most commonly manifest during the second or third decade of life. Infection of these cysts is a frequent cause of presentation to a physician.

• • Fig. 110.18 Histology of an eccrine hidrocystoma. Two layers of flattened epithelium form the cell wall (inset).  

Fig. 110.19 Histology of a thyroglossal duct cyst. A The cyst is lined by ciliated columnar epithelium; some of the cells contain clear cytoplasm. B Thyroid follicles are present in the tissue surrounding the cyst; note the homogeneous colloid within the lumina.  

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1925

SECTION

Neoplasms of the Skin

18

Pathology

Treatment

Histologically, these cysts are lined by stratified squamous epithelium or by pseudostratified ciliated columnar epithelium, and they are surrounded by lymphoid tissue.

Excision is curative.

Treatment Treatment is by excision of the cyst and its associated tract after delineation of the extent of the lesion by CT or MRI29.

Cutaneous Ciliated Cyst and Ciliated Cyst of the Vulva Synonyms:   ■ Cutaneous müllerian cyst ■ Cutaneous ciliated cystadenoma



Paramesonephric mucinous cyst of the vulva

Cutaneous ciliated cysts are uncommon cysts that typically occur on the lower extremities of young women, although a few cases have been reported in men. They are usually a few centimeters in diameter and, on rupture, drain clear to amber fluid. The histogenesis of these cysts is controversial. Most authors have suggested a müllerian duct origin, hence the term cutaneous müllerian cyst. However, the few occurrences in men and the rare reports of ciliated cysts on the scalp have led to the alternative hypothesis that some cases represent ciliated metaplasia of eccrine glands30. Ciliated cysts of the vulva are müllerian heterotopias, and they are located most commonly on the labia majora. They usually measure between 1 and 3 cm in diameter.

Omphalomesenteric Duct Cyst Synonyms:  ■ Vitelline cyst ■ Omphalomesenteric duct remnant Omphalomesenteric duct cysts represent a developmental defect in the closure of the omphalomesenteric duct. The omphalomesenteric duct is the fetal connection between the midgut and the yolk sac. It is usually obliterated and loses its intestinal attachment by 6 weeks of gestation33. Remnants of this duct may occur anywhere along its course between the intestines and the umbilicus. The spectrum of defects resulting from this faulty closure includes Meckel diverticulum, umbilical– enteric fistulae, umbilical sinuses, and omphalomesenteric duct cysts (internal or external); the latter can present as an umbilical polyp (Fig. 110.21A).

Pathology These lesions are characterized histologically by ectopic gastrointestinal mucosa (Fig. 110.21B) and must be distinguished from umbilical metastases of gastrointestinal adenocarcinomas.

Differential diagnosis In postmenarcheal female patients, the possibility of cutaneous endometriosis should be considered.

Pathology Cutaneous ciliated cysts may be unilocular or multiloculated. The cyst wall is composed of simple cuboidal to columnar ciliated epithelium that may have papillary projections into the cyst lumen (Fig. 110.20).

Treatment Excision is curative.

Median Raphe Cyst Median raphe cysts are solitary and usually only a few millimeters in diameter, although they may extend over several centimeters linearly. They occur in young men on the ventral aspect of the penis, most commonly on or near the glans. These cysts are thought to develop from aberrant urethral epithelium, but do not connect to the urethra31.

Pathology Histologically, median raphe cysts are lined by stratified columnar epithelium (one to four cell layers thick) without a connection to the overlying epithelium. Occasionally, mucin-containing cells are seen in the lining. Very rarely, a ciliated lining has been observed32.

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B

Fig. 110.21 Omphalomesenteric duct cyst. A An umbilical pink papule in an infant. The clinical differential diagnosis includes an umbilical (pyogenic) granuloma and urachal cyst/remnant. B Histologically, ectopic gastrointestinal epithelium is seen; note the villi and goblet cells. B, Courtesy, Luis Requena, MD.  

1926

Fig. 110.20 Histology of a ciliated cyst of the vulva. The cyst wall is composed of columnar ciliated epithelium (inset).  

Management of omphalomesenteric duct cysts includes appropriate radiologic studies to exclude communication to the gastrointestinal tract prior to surgical excision.

Urachal Cyst The urachus is a tube connecting the fetal bladder to the umbilicus and it normally closes during development, resulting in a fibrous tract. A persistent urachus presents during infancy with urine leakage from the umbilicus. A urachal cyst results from an incomplete urachal duct remnant. Urachal cysts are rare, and they usually present as a painful umbilical mass due to secondary infection. The diagnosis can be established by ultrasound in the majority of patients34.

Pathology These cysts are characterized by a urothelial lining of cuboidal or columnar cells.

epithelial lining. The spaces are surrounded by chronic inflammation, mucin-containing macrophages, and granulation tissue. A salivary duct may be seen at the periphery of these findings. Adjacent minor salivary glands may show chronic inflammation and fibrosis. The mucinous material is sialomucin, and the latter contains both neutral and acid mucopolysaccharides, which stain with PAS (diastase-resistant) and with Alcian blue or colloidal iron, respectively. Histologically, a superficial mucocele shows a subepithelial vesicle filled with mucin and a surrounding sparse to moderate mixed inflammatory infiltrate. Salivary gland ducts are seen opening into the vesicle or immediately adjacent to the vesicle.

CHAPTER

110 Cysts

Treatment

Treatment Mucoceles may resolve spontaneously. If they do not, treatment options include excision, marsupialization, electrodesiccation, intralesional corticosteroid injection, or cryosurgery.

Digital Mucous Cyst (Pseudocyst)

Treatment Excision is recommended to prevent secondary infections as well as late development of adenocarcinoma34.

CYSTS WITHOUT AN EPITHELIAL LINING Mucocele Synonyms:  ■ Mucous cyst of oral mucosa



Ranula (when located on

the floor of the mouth)

Mucoceles most frequently develop on the lower labial mucosa, but they also occur on the floor of the mouth, buccal mucosa, and tongue. They appear as dome-shaped, mucosa-colored to bluish, translucent papules or nodules that range in size from a few millimeters to over a centimeter (Fig. 110.22). Mucoceles arise as a result of disruption of the ducts of minor salivary glands. This disruption leads to an accumulation of mucinous material, a reactive inflammatory response, and the development of surrounding granulation tissue. A variant of mucocele, superficial mucocele, presents as a clear tense vesicle that is a few millimeters in diameter. Superficial mucoceles are most commonly found on the retromolar pad, posterior buccal mucosa, and soft palate. These lesions are short-lived, asymptomatic, and recurrent. They may be confused clinically with an immunobullous or viral process.

Synonyms:  ■ Digital myxoid cyst ■ Cutaneous myxoid cyst Digital mucous cysts (pseudocysts) most commonly occur on the dorsal surface of the distal phalanx of the finger. Toe lesions are less commonly observed. A characteristic longitudinal depression in the nail plate may be seen distal to the cyst (Fig. 110.23). These cysts are skin-colored to bluish and drain clear gelatinous material when punctured. The etiology of digital mucous cysts is controversial, with some authors stating that they are degenerative in origin while others believe they extend from the distal interphalangeal joint space. A pedicle connecting the cyst to the adjacent joint space can usually be demonstrated35.

Pathology Histologically, clefts are seen in the dermis without an epithelial lining (Fig. 110.24). The clefts and the surrounding loose connective tissue contain abundant acid mucopolysaccharides, which can be highlighted by Alcian blue or colloidal iron stains.

Treatment Resolution may be seen after intralesional injection of corticosteroids, injection of sclerosing agents, or repeated puncture and drainage36. Surgical excision may give even higher success rates.

Ganglion

Pathology Biopsy specimens of mucoceles show one or several spaces within the connective tissue filled with mucinous material, but without an

Synonyms:  ■ Ganglion cyst ■ Synovial cyst

Fig. 110.23 Digital mucous cyst. A translucent papule on the dorsal distal phalanx of the finger causing a depression in the nail  

Fig. 110.22 Mucocele. A bluish translucent papule on the lower mucosal lip.  

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18

Fig. 110.26 Pseudocyst of the auricle. Erythematous firm nodule on the ear.

Neoplasms of the Skin



Fig. 110.24 Histology of a digital mucous cyst. A subepidermal cystic cavity is surrounded by mucin-rich dermis (inset). Note the prominent stratum lucidum of acral skin. Courtesy, Lorenzo Cerroni, MD.  

the rare disorder cystic ganglionosis, multiple lesions appear during childhood or adolescence. Ganglia are frequently attached to a tendon sheath or the joint capsule, but usually do not communicate with the joint space37,38. The mucin present within a ganglion is thought to be produced by local fibroblasts.

Pathology Myxoid change is seen within the connective tissue that ultimately forms cystic spaces. These spaces coalesce into a dominant cystic space lined by fibrous tissue (Fig. 110.25B), sometimes with a synovial lining.

Treatment Early lesions may respond to several weeks of compression therapy37. Other options include aspiration plus intralesional corticosteroid injection or excision. Recurrences are common, even with excisional therapy.

$

Pseudocyst of the Auricle Synonyms:  ■ Endochondral pseudocyst ■ Cystic chondromalacia ■

Intracartilaginous cyst

Pseudocyst of the auricle usually arises in the scaphoid fossa of the ear in middle-aged men. Lesions are usually unilateral. They present as a painless swelling (Fig. 110.26), and they tend to arise over the course of a few weeks. The etiology of pseudocyst of the auricle is unknown, but chronic trauma as well as a developmental defect have been suggested.

Pathology

%

Fig. 110.25 Ganglion (cyst) – clinical presentation and histologic features. A A skin-colored, compressible, subcutaneous nodule is present on the wrist (arrow), the most common location. B A cystic space of acral skin is surrounded by fibrous tissue. A, Courtesy, Jean L Bolognia, MD; B, Courtesy, Lorenzo Cerroni, MD.  

1928

Ganglia are soft cystic masses up to 4 cm in diameter that most commonly occur on the dorsal aspect of the wrist; they may also be found on the volar wrist or fingers, the dorsal aspect of the feet, or the knees (Fig. 110.25A). Ganglia rarely develop on the lateral elbow or anterior shoulder. They occur more commonly in women and may cause discomfort with activity, impairment of mobility, or cosmetic concerns. In

Biopsy specimens show a cavity within the auricular cartilage (without an epithelial lining) that contains clear fluid. Fibrous tissue and granulation tissue may be found in the cavity as well. The cartilage lining the cavity may show degenerative changes. No inflammation is seen within the cartilage, a feature that distinguishes a pseudocyst from relapsing polychondritis, which may be in the clinical differential diagnosis.

Treatment Treatment options include aspiration, with or without intralesional injection of corticosteroids, as well as incision and drainage with destruction of the cavity. Each of these modalities should be followed by pressure dressings38.

Cutaneous Metaplastic Synovial Cyst (Pseudocyst) Cutaneous metaplastic synovial cysts (pseudocysts) typically present as a solitary tender subcutaneous nodule, although multiple lesions have been reported39,39a. They occur primarily in areas of prior trauma,

Pathology A cystic cavity is seen within the dermis that is not lined by epithelium. The cavity may communicate with the overlying epidermis via fistulas.

Variably cellular villous structures mimicking hyperplastic synovium protrude into the cavity. These villi are covered with a fibrinous exudate. The base of the villi tends to merge with surrounding scar tissue.

Treatment

CHAPTER

110 Cysts

particularly prior surgical trauma. Frequently, the preoperative diagnosis is that of a suture granuloma.

Excision is curative.

REFERENCES 1. Cooper PH, Fechner RE. Pilomatricoma-like changes in the epidermal cysts of Gardner’s syndrome. J Am Acad Dermatol 1983;8:639–44. 2. Gorlin RJ. Nevoid basal cell carcinoma syndrome. Dermatol Clin 1995;13:113–25. 3. Boussemart L, Routier E, Mateus C, et al. Prospective study of cutaneous side-effects associated with the BRAF inhibitor vemurafenib: a study of 42 patients.   Ann Oncol 2013;24:1691–7. 4. Shah V, Shet T. Scrotal calcinosis results from calcification of cysts derived from hair follicles: a series of 20 cases evaluating the spectrum of changes resulting in scrotal calcinosis. Am J Dermatopathol 2007;29:172–5. 5. Langley RG, Walsh NM, Ross JB. Multiple eruptive milia: report of a case, review of the literature, and a classification. J Am Acad Dermatol 1997;37:353–6. 6. Sau P, Graham JH, Helwig EB. Proliferating epithelial cysts. Clinicopathological analysis of 96 cases. J Cutan Pathol 1995;22:394–406. 7. Satyaprakash AK, Sheehan DJ, Sangueza OP. Proliferating trichilemmal tumor: a review of the literature. Dermatol Surg 2007;33:1102–8. 8. Mori O, Hachisuka H, Sasai Y. Proliferating trichilemmal cyst with spindle cell carcinoma. Am J Dermatopathol 1990;12:479–84. 9. Lopez-Rios F, Rodriguez-Peralto JL, Aguilar A, et al. Proliferating trichilemmal cyst with focal invasion: report of a case and a review of the literature.   Am J Dermatopathol 2000;22:183–7. 10. Ye J, Nappi O, Swanson PE, et al. Proliferating pilar tumors: a clinicopathologic study of 76 cases with a proposal for definition of benign and malignant variants. Am J Clin Pathol 2004;122:566–74. 11. Esterly NB, Fretzin DF, Pinkus H. Eruptive vellus hair cysts. Arch Dermatol 1977;113:500–3. 12. Sharma VM, Stein SL. A novel mutation in K6b in pachyonychia congenita type 2. J Invest Dermatol 2007;127:2060–2. 13. McLean WH, Rugg EL, Lunny DP, et al. Keratin 16 and keratin 17 mutations cause pachyonychia congenita. Nat Genet 1995;9:273–8. 14. Cassarino DS, Linden KG, Barr RJ. Cutaneous keratocyst arising independently of the nevoid basal cell

15. 16. 17.

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20. 21. 22.

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25. 26.

carcinoma syndrome. Am J Dermatopathol 2005;27:177–8. Requena L, Sanchez Yus E. Follicular hybrid cysts. An expanded spectrum. Am J Dermatopathol 1991;13:228–33. Brownstein MH. Hybrid cyst: a combined epidermoid and trichilemmal cyst. J Am Acad Dermatol 1983;9:872–5. Tirado M, Stander S, Metze D. Histologic and immunohistochemical characteristics of cutaneous cysts in Goltz-Gorlin syndrome: Clues for differentiation of nonsyndromic cysts. Am J Dermatopathol 2014;36:892–8. Mehregan AH, Medenica M. Pigmented follicular cysts. J Cutan Pathol 1982;9:423–7. Scheinfeld NS, Silverberg NB, Weinberg JM. Nozad V. The preauricular sinus: a review of its clinical presentation, treatment, and associations. Pediatr Dermatol 2004;21:191–6. McKusick VA, editor. OMIMTM Online Mendelian Inheritance in Man. National Center for Biotechnology Information . da Silva JH. Pilonidal cyst: cause and treatment.   Dis Colon Rectum 2000;43:1146–56. de Viragh PA, Szeimies RM, Eckert F. Apocrine cystadenoma, apocrine hidrocystoma, and eccrine hidrocystoma: three distinct tumors defined by expression of keratins and human milk fat globulin 1.   J Cutan Pathol 1997;24:249–55. Sugiyama A, Sugiura M, Piris A, et al. Apocrine cystadenoma and apocrine hidrocystoma:   examination of 21 cases with emphasis on nomenclature according to proliferative features.   J Cutan Pathol 2007;34:912–17. Sanz-Sanchez T, Dauden E, Perez-Casas A, et al. Efficacy and safety of topical atropine in treatment of multiple eccrine hidrocystomas. Arch Dermatol 2001;137:  670–1. Woolery-Lloyd H, Rajpara V, Nijhawan RI. Treatment for multiple periorbital eccrine hidrocystomas: botulinum toxin A. J Drugs Dermatol 2009;8:71–3. Miller OF III, Tyler W. Cutaneous bronchogenic cyst with papilloma and sinus presentation. J Am Acad Dermatol 1984;11:367–71.

27. Dedivitis RA, Guimaraes AV. Papillary thyroid carcinoma in thyroglossal duct cyst. Int Surg 2000;85:198–201. 28. Golledge J, Ellis H. The aetiology of lateral cervical (branchial) cysts: past and present theories. J Laryngol Otol 1994;108:653–9. 29. Thaller SR, Bauer BS. Cysts and cyst-like lesions of the skin and subcutaneous tissue. Clin Plast Surg 1987;14:327–40. 30. Reserva JL, Carrigg AB, Schnebelen AM, et al. Cutaneous ciliated cyst of the scalp: a case report of   a cutaneous ciliated eccrine cyst and a brief review of the literature. Am J Dermatopathol 2014;3:679–82. 31. Asarch RG, Golitz E, Sausker WF, Kreye GM. Median raphe cysts of the penis. Arch Dermatol 1979;115:1084–6. 32. Fernandez Acenera MF, Garcia-Gonzales J. Median raphe cyst with ciliated cells: report of a case.   Am J Dermatopathol 2003;251:175–6. 33. Larralde de Luna M, Cicioni V, Herrera A, et al. Umbilical polyps. Pediatr Dermatol 1987;4:341–3. 34. Ekwueme KC, Parr NJ. Infected urachal cyst in an   adult: a case report and review of the literature.   Cases J 2009;2:6422. 35. de Berker D, Lawrence C. Ganglion of the distal interphalangeal joint (myxoid cyst): therapy by identification and repair of the leak of joint fluid.   Arch Dermatol 2001;137:607–10. 36. Park SE, Park EJ, Kim SS, et al. Treatment of digital mucous cysts with intralesional sodium tetradecyl sulfate injection. Dermatol Surg 2014;40:1249–54. 37. Soren A. Clinical and pathologic characteristics   and treatment of ganglia. Contemp Orthop 1995;31:34–8. 38. Secor CP, Farrell HA, Haydon RC III. Auricular endochondral pseudocysts: diagnosis and management. Plast Reconstr Surg 1999;103:1451–7. 39. Singh SR, Ma AS, Dixon A. Multiple cutaneous metaplastic synovial cysts. J Am Acad Dermatol 1999;41:330–2. 39a.  Fukuyama M, Sato Y, Hayakawa J, Ohyama M. Cutaneous metaplastic synovial cyst: case report and literature review from the dermatological point of view. Keio J Med 2017;66:9–13.

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SECTION 18 NEOPLASMS OF THE SKIN

111 

Adnexal Neoplasms Timothy H. McCalmont and Laura B. Pincus

Chapter Contents Neoplasms and proliferations with follicular differentiation . . . 1930 Neoplasms and proliferations with sebaceous  

Follicular lineage is also connoted by attributes such as matrical or outer sheath differentiation. In contrast, there are no specific attributes that permit recognition of eccrine or apocrine differentiation, although decapitation configuration at the luminal border can be considered suggestive of apocrine differentiation.

differentiation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1942 Neoplasms and proliferations with apocrine (or eccrine)   differentiation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1943 Neoplasms and proliferations with eccrine differentiation . . . . 1951

Key features ■ Terminology and classification of adnexal tumors has varied considerably according to different authorities ■ Adnexal neoplasms can differentiate toward the folliculosebaceous-apocrine unit or the eccrine apparatus ■ As a reflection of joint ontogeny, tumors often exhibit combinations of follicular, sebaceous and apocrine differentiation ■ Many adnexal tumors historically classified as eccrine are probably apocrine

1930

The nosology of adnexal neoplasms has been confused for decades, and a key problem has been the lack of a logical classification scheme. Postulated classifications and inferences regarding lineage have often been contradictory, a reflection of the fact that broad conclusions regarding lineage and classification were formerly based on enzyme histochemical attributes of dubious specificity1,2. The crucial principle to keep in mind when considering adnexal neoplasms is that the development of the eccrine apparatus is distinct from the folliculosebaceous-apocrine unit. Eccrine glands develop directly from embryonic epidermal anlage during early months of fetal development3. Follicles arise directly from the epidermis concurrently, but their development differs in that mesenchymal cells, precursors of the follicular papilla, descend jointly into the dermis with the developing follicle (See Ch. 2 and Fig. ���������� 2.4). ����������������������������������� Subsequently, sebaceous and apocrine glands and their ducts elaborate as secondary structures from bulges on the side of the developing follicle. These ontogenetic relationships reflect relationships observed repeatedly in clinical disease1. As one would expect from ontogeny, follicular, sebaceous and apocrine differentiation occur conjointly, and combinations of eccrine and folliculosebaceous differentiation probably do not exist. Both the differentiation of the tumor (Fig. 111.1) and the topography of adnexal structures offer insights into logical classification. There is striking variation in anatomic distribution among adnexal neoplasms, and some of these differences hold implications regarding lineage. Based on topography, it is nonsensical to pigeonhole spiradenoma, a tumor that commonly occurs within apocrine skin and rarely, if ever, develops within acral skin, as an eccrine tumor. In contrast, an acral predilection suggests that poroma is commonly of eccrine lineage4. Lastly, microscopy and morphology play a role in the assessment of lineage. For some lines of differentiation, the meaning ascribed to specific attributes is indisputable. Cells with coarsely vacuolated cytoplasm and scalloped nuclei signify sebaceous differentiation. Follicular differentiation is established by the presence of bulbar basaloid cells accompanied by mesenchymal cells resembling the follicular papilla.

NEOPLASMS AND PROLIFERATIONS WITH FOLLICULAR DIFFERENTIATION Follicular and Folliculosebaceous-Apocrine Hamartomas Hamartomas are benign proliferations composed of cellular elements, native to a site, in aberrant proportion. A congenital hamartoma, such as nevus sebaceus, is properly referred to as a nevus. Hamartomas can be acquired and present in a tumor-like fashion, although such lesions do not represent authentic neoplasms. Proliferations of the folliculosebaceous-apocrine unit are commonly hamartoma-like. The folliculosebaceous-apocrine unit incorporates follicular epithelial, follicular mesenchymal, and sebaceous and apocrine elements; thus its microscopically diverse progeny is not surprising. Many follicular proliferations that we consider neoplastic, such as trichoblastoma, have integral stroma, and thus the distinction between follicular hamartoma and follicular neoplasm is sometimes blurred.

Hair follicle nevus Introduction

Hair follicle nevi are authentic hamartomas, usually congenital, in which hairs and the follicles that ensheath them have abnormal morphology or size or are present in increased numbers.

Clinical features

Hair follicle nevus, also known as vellus hamartoma, presents as a small papule from which fine hairs protrude evenly from the surface. Lesions typically involve the face and commonly reside near the ear5. Accessory tragus overlaps with hair follicle nevus, and it has been suggested that the two entities are the same6. Nevus pilosus designates hamartomas characterized by closely set, non-vellus hairs.

Pathology

Microscopically, hair follicle nevi display a domed surface with an increase in normally formed vellus follicles. The configuration may resemble normal skin. Accessory tragi exhibit an identical pattern but are uniquely identifiable if deep subjacent hyaline cartilage is present and can be found. Nevus pilosus is characterized by closely set terminal follicles.

Treatment

No therapy is required. Excision can be considered for cosmesis. In the evaluation of a hair follicle nevus or accessory tragus in a small child, parents can be counseled that the relative size of the lesion will diminish with time. The child will grow disproportionately faster than the lesion.

Trichofolliculoma Introduction

Trichofolliculoma does not represent an authentic neoplasm. Rather, the term designates a group of follicular hamartomas in which fully formed follicular structures emanate from a central dilated infundibular space.

Adnexal neoplasms encompass both benign and malignant tumors with differentiation towards hair follicles as well as the ducts and secretory components of sebaceous, eccrine and apocrine glands. Those tumors with follicular differentiation can be further divided based upon the type of keratinization they display, e.g. infundibular, isthmic, germinative, matrical, or resembling the inner and outer root sheath. Because many of the adnexal neoplasms have ductal differentiation and eccrine ducts can be difficult to distinguish from apocrine ducts, it is often impossible to determine if a neoplasm is eccrine or apocrine in origin. In fact, many adnexal tumors previously considered to be of eccrine differentiation have been reclassified into the apocrine group. Most adnexal neoplasms are benign, but malignant variants of virtually every entity can be encountered, sometimes with deceptively mild morphologic features. Diagnosis and classification are based on accurate evaluation of clinicopathologic features.

adnexal neoplasms, adnexal tumors, hair follicle nevus, trichofolliculoma, fibrofolliculoma, perifollicular fibroma, trichodiscoma, nevus sebaceus, mixed tumor, chondroid syringoma, trichoblastoma, trichoepithelioma, desmoplastic trichoblastoma, desmoplastic trichoepithelioma, pilomatricoma, pilomatrical carcinoma, tricholemmoma, trichilemmoma, tumor of follicular infundibulum, infundibuloma, isthmicoma, trichoadenoma, sebaceous gland hyperplasia, sebaceous adenoma, sebaceoma, sebaceous epithelioma, sebaceous carcinoma, poroma

CHAPTER

111 Adnexal Neoplasms

ABSTRACT

non-print metadata KEYWORDS:

1930.e1

Fig. 111.1 The folliculosebaceousapocrine unit and eccrine sweat gland with examples of adnexal tumors that differentiate toward the hair follicle, sebaceous gland, apocrine gland, and eccrine gland. *Can show germinal differentiation. **Differentiation toward entire follicle. Courtesy,  

Christine, Ko, MD.

Acrosyringium • Poroma Infundibulum • Trichoepithelioma • Fibrofolliculoma/ trichodiscoma • Trichofolliculoma • Trichoadenoma • Nevus comedonicus

CHAPTER

111 Adnexal Neoplasms

FOLLICULOSEBACEOUS-APOCRINE UNIT AND ECCRINE SWEAT GLAND

*

Eccrine duct/gland • Syringoma • Hidradenoma • Mixed tumor • Hidrocystoma

Arrector pili muscle

**

Sebaceous gland • Sebaceous hyperplasia • Nevus sebaceus • Sebaceous adenoma • Sebaceoma • Sebaceous carcinoma

Isthmus • Tricholemmoma • Tumor of the follicular infundibulum • Proliferating tricholemmal tumor • Pilar sheath acanthoma

Germ/matrix • Basal cell carcinoma • Pilomatricoma • Trichoblastoma • Pilomatrical carcinoma

Hair follicle

Apocrine duct/gland • Syringoma • Poroma • Hidradenoma • Syringocystadenoma papilliferum • Mixed tumor • Hidradenoma papilliferum • Spiradenoma • Cylindroma • Tubular adenoma • Microcystic adnexal carcinoma • Hidrocystoma • Extramammary Paget disease • Mucinous carcinoma

Clinical features

Fig. 111.2 Trichofolliculoma. Wispy vellus hairs emerge from a skin-colored papule with a dilated central  

Trichofolliculoma presents as a papule or nodule involving the face, scalp or upper trunk. Many examples are not clinically distinctive. Sometimes, a central follicular ostium or punctum may be identifiable and it may harbor a small tuft of more lightly pigmented hairs (Fig. 111.2). Rarely, the clinical presentation will be as a large nodule or cyst or as multiple lesions in uncommon sites.

Pathology

Prototypically, a trichofolliculoma consists of a central cystic space with infundibular cornification and central orthokeratin. Sometimes, crosssections of hair shafts are identifiable within the cyst. Relatively welldeveloped and occasionally oddly formed vellus follicles protrude in radial fashion from the central structure (Fig. 111.3). The follicles usually display a bulb and papilla and exhibit inner and outer sheath and isthmic differentiation. The entire structure, including the central cyst and its associated radiating follicles, is enveloped by a vascularized fibrous (angiofibroma-like) stroma. The radiating follicles are frequently cut on tangent, thus creating considerable microscopic variation, and deeper sections through the tissue block sometimes are required for diagnosis. If the radiating follicles are accompanied by sebaceous glands, the hamartoma can be termed a sebaceous trichofolliculoma7. This diagnostic embellishment is not of any clinical import. The term folliculosebaceous cystic hamartoma has been applied to a group of nodular and cystic lesions described independently from trichofolliculoma8–10. Folliculosebaceous cystic hamartoma shows a central infundibular cyst from which follicular and sebaceous elements emanate, and the encompassing stroma may be fibrous or myxoid and often contains adipocytes. Rather than a unique entity, is seems likely that folliculosebaceous cystic hamartoma represents a large cystic sebaceous trichofolliculoma8.

Pilar sheath acanthoma is characterized by a cystically dilated follicular configuration that opens to the surface epithelium, much like trichofolliculoma. However, in pilar sheath acanthoma, the lobules of cells that radiate from the cystic dilation recapitulate only the follicular isthmus and outer sheath rather than forming full follicular structures. In addition, a pilar sheath acanthoma does not have the investing fibrous stroma of a trichofolliculoma.

Treatment

Trichofolliculoma is wholly benign and no treatment is needed. If a trichofolliculoma is discovered by biopsy, no further intervention is required.

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EVALUATION OF PATIENTS WITH BIRT–HOGG–DUBÉ SYNDROME (BHDS) Molecular genetic testing (FLCN) is recommended if patient is known to have BHDS or is suspected of having BHDS, including those who have one of the following: • ≥5 facial or truncal papules, at least one of which is confirmed histologically to be a fibrofolliculoma • Facial papules with a histologic diagnosis of angiofibroma (excluding individuals with tuberous sclerosis or MEN1) • Multiple and bilateral chromophobe, oncocytic, and/or hybrid renal tumors • A single chromophobe, oncocytic, and/or hybrid renal tumor and a family history of renal cancer (any of these cell types) • A family history of AD primary spontaneous pneumothorax but without a history of smoking or COPD Imaging studies for pulmonary and renal involvement: • Pulmonary: high-resolution CT scan of the chest to detect cysts • Renal: renal MRI scan (preferred) or abdominal/pelvic CT scan to detect tumors Suggested surveillance and recommendations: • Cutaneous: full body skin examination • Pulmonary: smoking cessation and judicious use of general anesthesia to reduce risk of pneumothorax • Renal: annual renal MRI scan (preferred) or abdominal/pelvic CT scan, but if no family history of renal tumors plus 2–3 negative annual scans, screening can be done every 2 years - Tumors 3 cm in diameter treated with surgical excision

Table 111.1 Evaluation of patients with Birt–Hogg–Dubé syndrome (BHDS). AD, autosomal dominant; COPD, chronic obstructive pulmonary disease; CT, computed tomography; MEN1, multiple endocrine neoplasia type 1.  

Adapted from Toro JR. Birt-Hogg-Dubé syndrome – GeneReviews® – NCBI Bookshelf; 2014 (www.ncbi.nlm.nih.gov).

Fig. 111.3 Trichofolliculoma. There is a central patulous follicular infundibulum, from which fully formed or nearly fully formed follicles radiate.  

Courtesy, Luis Requena, MD.

Multiple papules of the face and pinnae can also be seen in patients with familial multiple discoid fibromas, but there are no systemic manifestations or mutations in FLCN. Mutations have been detected in FNIP1, when encodes a folliculin interacting protein.

Pathology

Fibrofolliculoma, perifollicular fibroma, and trichodiscoma Introduction

Fibrofolliculoma represents an adnexal hamartoma that includes both follicular epithelial and mesenchymal elements. Perifollicular fibroma and trichodiscoma were described independently but probably represent purely mesenchymal proliferations on the same spectrum as fibrofolliculoma. Some authorities consider perifollicular fibroma to be related to angiofibroma.

Clinical features

1932

Fibrofolliculomas (Fig. 111.4A,B), perifollicular fibromas, and trichodiscomas are not clinically distinctive. All present as small, skin-colored to hypopigmented papules that involve the head and neck or upper trunk. The papules commonly present in multiplicity. In this context, strong consideration should be given to the possibility of the Birt–Hogg– Dubé syndrome (Fig. 111.5), an autosomal dominant disorder typified by multiple fibrofolliculomas, trichodiscomas, and acrochordon-like lesions. The major systemic manifestations are renal tumors, the majority of which are oncocytomas or renal cell carcinomas of the chromophobe or hybrid chromophobe–oncocytoma type, pulmonary cysts, and spontaneous pneumothoraces (Table 111.1). Colonic polyps and connective tissue nevi have also been reported in affected patients as have multiple primary cutaneous melanomas11. However, it has not yet been determined if there is a significant increased risk for melanoma compared to the general population. Heterozygous mutations in the tumor suppressor gene FLCN, which encodes folliculin, a protein involved in cell–cell adhesion, underlie this syndrome (see Table 111.1).

At low magnification, fibrofolliculoma displays slender strands of follicular mantle cells that emanate from a folliculosebaceous unit at the level of the isthmus (Fig. 111.4C). Usually, the strands are composed of cells with a slightly basaloid appearance, and sometimes, tiny integrated collections of mature sebocytes are identifiable. The epithelial component may assume a mitt-like morphology in some instances, encasing the vascularized fibrous stroma. Perifollicular fibroma consists almost exclusively of stroma that is identical to the stromal elements of fibrofolliculoma and angiofibroma. Lesions consist of spindled and stellate cells arrayed concentrically around follicles and distributed amongst thickened collagen bundles with a proportionate number of intervening small thin-walled vessels. Sometimes, a concurrent component of follicular epithelial hyperplasia is identifiable, although the epithelium tends to be inconspicuous in comparison to fibrofolliculoma. Trichodiscoma was thought by Pinkus to represent a unique proliferation with differentiation toward the haarscheibe (hair disk), which is probably a mythical structure. More recently, trichodiscomas have been interpreted as fibrofolliculomas or perifollicular fibromas with myxoid rather than fibrous stroma. Lastly, the so-called neurofollicular hamartoma is now considered to be a type of trichodiscoma.

Treatment

Fibrofolliculomas, perifollicular fibromas, and trichodiscomas are all benign and require no surgical treatment. Superficial electrodesiccation, laser ablation, or dermabrasion can be utilized to ameliorate multiple lesions. Unlike the angiofibromas of tuberous sclerosis, topical rapamycin did not result in cosmetic improvement in the fibrofolliculomas of Birt–Hogg–Dubé syndrome12.

CHAPTER

Adnexal Neoplasms

111

$

%

Fig. 111.4 Fibrofolliculomas in association with Birt–Hogg–Dubé syndrome – clinical and histopathologic findings. A Multiple, small, skin-colored to white papules on the ear. B Multiple smooth papules of the cheek that are skin-colored to relatively hypopigmented; they lack the telangiectasias of the background skin. C Strands of basaloid cells emanate from a folliculosebaceous unit and form a mitt-like configuration encasing delicate fibrous stroma. B,  

Courtesy, Barry Goldberg, MD.

&

Nevus sebaceus Introduction

Originally known as organoid nevus, nevus sebaceus is commonly thought of as a sebaceous lesion and historically has been the first entity discussed in chapters describing sebaceous tumors. In truth, nevus sebaceus is a non-neoplastic malformation that includes follicular, sebaceous and apocrine elements13 as well as epidermal hyperplasia.

Clinical features

Nevus sebaceus represents a classic nevus or congenital malformation. At birth, lesions are only slightly raised and subtly discernible. Nevus sebaceus involves the scalp or face commonly, the neck occasionally, and the trunk rarely. Lesions that are linear are distributed along the lines of Blaschko, although this may be difficult to appreciate if small in size. On the scalp, a nevus will remain hairless, or mostly so, as the infant’s hair grows normally around it. During childhood, the nevus thickens slightly and assumes a yellow or orange hue (Fig. 111.6). At adolescence, progressive thickening occurs and the surface becomes pebbly or verrucous. Especially when there is more extensive involvement with nevus sebaceus, the possibility of Schimmelpenning syndrome or phakomatosis pigmentokeratotica needs to be considered (see Table 62.7). In a study of 65 sebaceous nevi, postzygotic somatic mutations were detected in HRAS (95% of nevi) and KRAS (5%)14. Mosaicism for HRAS and KRAS mutations was also detected in individuals with Schimmelpenning syndrome. The more common mutations were shown to lead to activation of the MAPK and PI3K-Akt pathways (see Ch. 113). A syringocystadenoma papilliferum or trichoblastoma that arises within a nevus sebaceus carries the same HRAS mutation as the underlying nevus15.

Nevus sebaceus represents a fertile field for the development of secondary adnexal neoplasms, commonly benign but occasionally malignant16–18. Past generations of dermatologists were taught that secondary carcinoma develops in 10% or more of these lesions over time, although this figure was poorly substantiated. The vast majority of secondary proliferations represent benign follicular germinative (trichoblastoma-like) foci; the actual incidence of secondary basal cell carcinoma (BCC) is 20 cm in diameter (Fig. 112.1B). CALMs enlarge proportionately with overall body growth and then remain stable in size during adulthood. By dermoscopy, a homogenous brown patch is seen with perifollicular hypopigmentation; a faint reticular pattern may also be present. Compared with NF1, the CALMs of McCune–Albright syndrome are typically fewer in number, larger, and have a midline demarcation; they usually have a segmental distribution pattern or present as broad bands along the lines of Blaschko8. These CALMs favor the head, neck, trunk and buttocks. They also tend to be unilateral, often involving the same side as the bone lesions and situated in proximity. They can, however, be indistinguishable both clinically and histologically from the CALMs of neurofibromatosis. If present, superimposed lentigines (due to widespread “freckling” extending beyond the axillae) can point to NF1associated CALMs.

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Pathology

BECKER MELANOSIS (NEVUS)

Light microscopy shows a normally configured epidermis with a slightly increased melanin content in the basilar keratinocytes. The adnexal epithelium is spared of hyperpigmentation, and melanophages are rarely found in the dermis. In DOPA-stained epidermis from most patients with neurofibromatosis, the density of melanocytes is higher in both CALMs and normal adjacent skin, in comparison with healthy individuals. The melanocytic density in isolated CALMs of otherwise normal persons, however, is usually less than in surrounding skin. Melanin macroglobules (large pigment particles resulting from fusion of autophagosomes containing varying numbers of melanosomes) may be found in CALMs, but they are not specific for neurofibromatosis, as they are occasionally found in isolated CALMs (without any underlying disease) and occur in several other conditions such as simple lentigines, Becker melanosis, congenital melanocytic nevi, and sometimes even normal skin. By electron microscopy, the melanosomes are usually dispersed singly within melanocytes and are usually homogeneous, electron-dense, and ellipsoidal when fully melanized9.

Differential Diagnosis Hyperpigmented macules or patches that might be confused with CALMs include pigmentary mosaicism (segmental pigmentation disorder, linear nevoid hyperpigmentation), early nevus spilus (before the “speckles” have appeared), Becker melanosis (without obvious hypertrichosis), mastocytoma, mosaic (segmental) neurofibromatosis, and postinflammatory hyperpigmentation. Smaller lesions may resemble lentigines or acquired melanocytic nevi, while larger lesions may be confused with relatively flat congenital melanocytic nevi. Café-noir spots are hyperpigmented patches that have an even darker hue (relative to background skin) than CALMs and are seen in LEOPARD syndrome (Noonan syndrome with multiple lentigines) and the Carney complex.

Treatment CALMs have never been reported to undergo malignant change. Topical agents (e.g. hydroquinone) and sun protection will have no effect on CALMs. A variety of lasers have been used to treat CALMs, with variable success10. The risks of laser surgery include transient hyperpigmentation or hypopigmentation, slight scarring, permanent hyperpigmentation, incomplete clearance, and especially recurrence. Typically, between 1 and 14 treatments are required, and responses are difficult to predict. For instance, of 12 CALMs treated with a Q-switched ruby laser in one study, 50% developed repigmentation within 6 months. Responses to frequency-doubled Nd:YAG are also quite variable.

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Synonyms:  ■ Becker’s nevus ■ Becker’s pigmentary hamartoma ■

Nevoid melanosis

Key features ■ Unilateral, hyperpigmented, often hypertrichotic patch or slightly elevated plaque ■ Most commonly on the shoulder of male patients ■ Onset usually during adolescence

Epidemiology Becker melanosis has been observed in all races11. Although it is usually acquired, some cases are congenital. The lesions most often appear during the second and third decades of life and are six times more common in males than in females. Familial occurrence has been reported. In one study, the prevalence among 19 302 army recruits ages 17 to 26 years was 0.5%.

Pathogenesis The pathogenesis of Becker melanosis remains unclear. It is believed to be an organoid hamartoma of ectodermally and mesodermally derived tissues. An increase in androgen receptors and probable heightened sensitivity to androgens have been postulated. The latter characteristics would explain its onset during or after puberty, as well as its clinical and histologic manifestations, which include hypertrichosis, dermal thickening, acne, and hypertrophic sebaceous glands. Androgen stimulation could also explain the accentuated smooth muscle elements often found in the dermis of Becker melanosis12. Recently, postzygotic mutations in beta-actin were reported to be associated with Becker nevus and Becker nevus syndrome (see below)12a.

Clinical Features The onset of Becker melanosis is usually noted during the second or third decade of life, sometimes following intense sun exposure. Lesions are most often unilateral and usually involve an upper quadrant of the anterior or posterior chest (Fig. 112.2A,B). However, they have also been described on the face, neck, lower trunk, extremities, and buttocks (Fig. 112.2C)11. Normally, Becker melanosis appears as a single lesion, but multiple lesions have occasionally been observed. The diameter

%

Fig. 112.2 Becker melanosis (nevus). A Unilateral hyperpigmented patch of the upper chest with confluence centrally and an irregular broken-up border. Acneiform lesions were limited to the lesion in this prepubescent boy. B Unilateral, block-like configuration with hyperpigmentation and hypertrichosis; the patient had an underlying smooth muscle hamartoma. C Large patch of hyperpigmentation on the leg which is medium brown in color. Such lesions may be misdiagnosed as café-au-lait macules or congenital melanocytic nevi, especially when they do not occur on the upper trunk. A, Courtesy, Julie V Schaffer, MD; B, Courtesy, Edward Cowen, MD; C, Courtesy, Jean L Bolognia, MD.  

1956

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Pathology There is variable degree of acanthosis, hyperkeratosis, and sometimes mild papillomatosis11. Regular elongation of the rete ridges and hyperplasia of the pilosebaceous unit may be observed. The melanin content of the keratinocytes is increased, whereas the number of melanocytes is normal or only slightly increased, without nesting. Melanophages may be found in the papillary dermis. A concomitant smooth muscle hamartoma is often, but not invariably, present in the dermis.

Differential Diagnosis The differential diagnosis primarily includes CALM, congenital melanocytic nevus, plexiform neurofibroma, and congenital smooth muscle hamartoma. The latter tends to be smaller in size, but some authors consider Becker melanosis and congenital smooth muscle hamartoma to be two ends of a clinical spectrum (see Ch. 117). A congenital melanocytic nevus, plexiform neurofibroma, and congenital smooth muscle hamartoma can all have cutaneous hyperpigmentation plus hypertrichosis. By dermoscopy, Becker melanosis is less likely to have focal thickening of network lines, globules or homogeneous diffuse pigmentation, when compared to congenital nevi. The presence of multiple CALMs and axillary freckling can be helpful in establishing the diagnosis of neurofibromatosis, and unlike Becker melanosis, CALMs do not have corrugation on side-lighting. In an occasional patient, histologic evaluation is required to confirm the diagnosis, especially if the lesion is in an unusual location and there is an associated smooth muscle hamartoma.

CHAPTER

Key feature ■ Tan to dark brown or black macules due to exposure to UV radiation

Solar lentigines are common benign lesions resulting from chronic UVR exposure that results in epidermal hyperplasia with a variable proliferation of melanocytes. These lesions are found in >90% of the Caucasian population older than 60 years of age (Figs 112.3 & Fig. P1), but are also seen in Asians, especially on the face (see Ch. 87). The clinical differential diagnosis includes pigmented actinic keratosis, pigmented Bowen disease, and lentigo maligna as well as other benign pigmented lesions such as lentigo simplex, ephelis, small CALM, and junctional melanocytic nevus. Solar lentigines are discussed in detail in Chapter 109.

112 Benign Melanocytic Neoplasms

ranges from a few centimeters to >15 cm, and the most common configuration is block-like, although linear patterns have been reported. The hyperpigmentation varies from uniformly tan to dark brown and while the lesions are well demarcated, the margins are usually irregular. The center of the lesion may show slight thickening and corrugation of the skin. Hypertrichosis usually develops after the hyperpigmentation, and the hairs become coarser and darker with time (see Fig. 112.2B). Sometimes, the hypertrichosis is subtle and can only be appreciated by comparison with the contralateral side. The hypertrichosis and pigmentation may not overlap completely. After its initial appearance, Becker melanosis may enlarge slowly for a year or two but then remains stable in size. The color can fade with time, but hypertrichosis usually persists. Normally, Becker melanosis is asymptomatic, but some patients report pruritus. Firmness to palpation may point to an associated smooth muscle hamartoma. In some patients, perifollicular papules may be a sign of coexistent proliferation of the arrector pili muscle. Acneiform lesions strictly limited to the area of hyperpigmentation have also been reported. Becker melanosis is a benign lesion, and malignant transformation has not been reported. In contrast to the hyperplasia of the ectodermal and mesodermal tissues in Becker melanosis, developmental anomalies that are generally hypoplastic in nature have occasionally been associated with Becker melanosis. These abnormalities include hypoplasia of the ipsilateral breast, areola, nipple and arm, ipsilateral arm shortening, lumbar spina bifida, thoracic scoliosis and pectus carinatum, as well as enlargement of the ipsilateral foot. Accessory scrotum and supernumerary nipples have also been reported. In cases of Becker melanosis with associated abnormalities (also referred to as “Becker nevus syndrome”), the male : female ratio is reversed at 2 : 5 (in comparison to 6 : 1 in those without abnormalities)13.

LENTIGO SIMPLEX AND MUCOSAL MELANOTIC LESIONS Synonyms:

  Lentigo simplex: • simple lentigo • lentiginosis (if multiple)   Mucosal melanotic lesions: • mucosal melanotic macules • lentiginosis • melanosis ■  Anatomic subtypes: • oral melanotic macules • labial melanotic macules • genital lentiginosis • anogenital lentiginosis ■ ■

Key feature ■ A lentigo simplex is a brown macule with an early age of onset (as compared with a solar lentigo) and little or no relationship to sun exposure

Epidemiology The frequency of lentigo simplex in children and adults is unknown. Lentigines are found in all races and appear to occur equally in both sexes. Isolated lesions may be present at birth, more commonly in darkly pigmented than lightly pigmented newborns. These lentigines may increase in number during childhood or puberty. Sometimes they occur in an eruptive form called lentiginosis, with or without obvious precipitating factors. After melanocyte activation, lentigo simplex represents the next most common histology in matrix biopsies of longitudinal melanonychia (see Ch. 71). In darkly pigmented individuals, lentigo simplex is the most common histologic pattern for cutaneous pigmented lesions in acral sites.

Treatment Patients with Becker melanosis should be examined for possible soft tissue and bony abnormalities (see above). Electrolysis, waxing, camouflage makeup, and laser treatments may be recommended. The hyperpigmented component may respond to Q-switched ruby and frequency-doubled Nd:YAG laser therapy14, but recurrence rates are high. The hypertrichosis can be addressed, sometimes more successfully, with one of several lasers designed for this purpose (see Ch. 137).

SOLAR LENTIGINES Synonyms:  ■ Lentigo senilis ■ Liver spot ■ Old age spot ■ Senile freckle

Fig. 112.3 Solar lentigines. Numerous light brown macules, some of which have an irregular border, on chronically sun-exposed skin.  

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Oral melanotic macules are found primarily in adults over 40 years of age. Some authors report a slight female predilection, whereas others describe both sexes being affected equally. The most common sites are the vermilion border, followed by the gingiva, the buccal mucosa and the palate. Up to 30% of melanomas in the oral cavity of Caucasians are preceded by melanosis for several months or years. In Japanese patients, two-thirds of infiltrative oral melanomas arise in association with oral melanosis. The labial (lip) melanotic macule usually appears between the second and fourth decades of life and has a strong predilection for Caucasian women. The incidence of lentiginosis or melanosis of the female genital area is probably higher than reported. For example, 15% of 106 females between the ages of 16 and 42 years had genital “nevi”, and in a study of 100 random autopsies, three cases showed melanosis of the genitalia, and all three were elderly women. Most lesions are found on the labia minora, but they can also occur on the labia majora, the vaginal introitus, the cervix, the periurethral area, and the perineum as well as perianally. In general, lentiginosis and melanosis of the female genitalia are benign conditions; atypia is uncommon and progression to melanoma has rarely been observed14a. In a study of 10 000 men between 17 and 25 years of age, 14% were noted to have “pigmented nevi” of the genitalia15. It is uncertain what proportion represented penile lentiginosis or melanosis since no clinical descriptions or histologic studies were reported. In the literature, the ages of patients with penile lentiginosis or melanosis range from 15 to 75 years. The lesions occur on both the glans penis and penile shaft. Men can also develop lentigines perianally. The incidence of conjunctival melanosis is unknown, but it can be assumed that primary acquired melanosis is a precursor lesion of melanoma in this area, since a significant number of conjunctival melanomas are associated with it. Lentigo simplex occasionally develops within scars following excision of cutaneous melanoma as do pigmented streaks due to basilar hyperpigmentation; the latter favors individuals with numerous solar lentigines.

Clinical Features Lentigines simplex are light brown to black, homogeneously pigmented macules occurring anywhere on the body, including mucous membranes and palmoplantar skin, without any predilection for sun-exposed areas. They are well circumscribed, round or oval, have regular borders, and are usually BRAF • Lentigines present in infancy/early childhood • Café-noir macules • ECG changes (conduction defects, hypertrophic cardiomyopathy), ocular hypertelorism, pulmonary stenosis, abnormal genitalia, growth retardation and deafness

Head and neck (including oral mucosa) ± acral Peutz–Jeghers syndrome



Autosomal dominant inheritance; mapped to 4q21.1–q22.3 • Café-au-lait macules

Bandler syndrome*



LEOPARD syndrome (now referred to as Noonan syndrome with multiple lentigines)



Generalized lentigines



Deafness plus lentiginosis*



? Forme fruste of LEOPARD syndrome

Autosomal dominant inheritance; mutations in STK11 • Lentigines favor perioral region†, oral mucosa‡ and hands; longitudinal melanonychia • Multiple hamartomatous GI polyps • Pancreatic carcinoma; ovarian (adenoma malignum)/testicular tumors Autosomal dominant inheritance Distribution of lentigines similar to Peutz–Jeghers • GI bleeding with small intestine hemangiomas rather than polyps •

Table 112.2 Disorders associated with multiple lentigines. ECG, electrocardiogram; GI, gastrointestinal; LEOPARD, lentigines/ECG abnormalities/ocular hypertelorism/pulmonary stenosis/abnormalities of genitalia/retardation of growth/deafness syndrome. Adapted from Bolognia JL. Disorders of hypopigmentation and  

1958

Comments

Localized

hyperpigmentation. In: Harper J, Oranje A, Prose N (eds). Textbook of Pediatric Dermatology, 2nd edn. Oxford: Blackwell Science, 2006:997–1040.

CHAPTER

Disorder

Comments

Disorder

Comments

Carney complex (NAME/LAMB syndrome)



Autosomal dominant inheritance; mutations in PRKAR1A (second locus on 2p16) • Lentigines, mucocutaneous myxomas, blue nevi (including epithelioid) • Psammomatous melanotic schwannomas • Atrial myxoma • Myxoid mammary fibroadenomas • Pigmented nodular adrenocortical disease; testicular (calcifying Sertoli cell), thyroid, and pituitary tumors

Laugier–Hunziker syndrome



Hyperkeratosishyperpigmentation (Cantú) syndrome



Cowden disease



Centrofacial lentiginosis (neurodysraphic)

Autosomal dominant inheritance Lentigines in a butterfly distribution on the nose, cheeks > forehead, eyelids, upper lip • Onset in infancy; increase in number in childhood • Possibly associated with neuropsychiatric illness and osseous anomalies

Inherited patterned lentiginosis



Cronkhite–Canada syndrome



Arterial dissection plus lentiginosis



? Inheritance pattern Cutaneous lentigines with onset in childhood • Dissection of aortic, internal carotid and vertebral arteries

Gastrocutaneous syndrome*





Autosomal dominant inheritance; see Table 61.4 for details

Tay syndrome*



Pipkin syndrome*



? Autosomal recessive inheritance Growth retardation, intellectual disability; triangular face; cirrhosis; trident hands • Café-au-lait macules; premature canities; vitiligo •

Autosomal dominant inheritance Nystagmus; strabismus



Similar distribution of lentigines as in Peutz–Jeghers, including lips, oral mucosa and digits • Longitudinal melanonychia and genital melanosis Autosomal dominant inheritance Punctate palmoplantar keratoderma • Multiple small (1 mm) macules on the face, forearms, hands/feet •

Benign Melanocytic Neoplasms

112

DISORDERS ASSOCIATED WITH MULTIPLE LENTIGINES

Autosomal dominant inheritance; mutations in PTEN • Periorificial and acral pigmented macules (see Table 63.3) • •

Autosomal dominant inheritance African-Americans with light brown skin • Pigmented macules appear in early childhood • Present on central face and lips > buttocks, elbows, hands/feet • Rare oral mucosal involvement •

Typically affects older men Lentigines of buccal mucosa, face, hands/feet • Alopecia (diffuse, non-scarring), nail dystrophy, intestinal polyposis, diarrhea, malabsorption •

Genital Bannayan–Riley– Ruvalcaba syndrome

Autosomal dominant inheritance; mutations in PTEN • Penile > vulvar pigmented macules (see Table 63.3) •

“Photodistribution” Xeroderma pigmentosum

Autosomal recessive inheritance; mutations in genes encoding proteins that repair UV-induced DNA damage • Lentigines favor, but are not limited to, chronically sun-exposed sites • Multiple skin cancers •

Segmental Partial unilateral lentiginosis

Multiple lentigines in a segmental distribution • Café-au-lait macules in same distribution •

*† To date, observed in a single family May fade.

‡Persists.

Table 112.2 Disorders associated with multiple lentigines. (cont’d) NAME, nevi/atrial myxoma/myxoid neurofibroma/ephelides syndrome; LAMB, lentigines/atrial myxoma/mucocutaneous myxoma/blue nevi syndrome.  

In contrast to lentigo simplex occurring on the skin, lesions on mucous membranes can slowly increase in size over months to years, with or without changes in the degree of pigmentation. The relationship between acral or anogenital lentigines and acrolentiginous melanoma requires more investigation.

Special forms and associated syndromes Multiple lentigines may or may not be associated with other systemic manifestations. In LEOPARD syndrome (now referred to as Noonan syndrome with multiple lentigines), the acronym refers to: lentigines, electrocardiographic conduction defects, ocular hypertelorism,

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pulmonary stenosis, abnormalities of genitalia, retardation of growth, and deafness (see Table 112.2). Multiple lentigines are present at birth or appear during early infancy and may increase in number during childhood. The lesions are generalized, occurring in both sun-exposed and sun-protected sites, including genitalia, palms, and soles. The Carney complex is an autosomal dominant syndrome characterized by multiple lentigines and multiple neoplasias, including: myxomas of the skin, heart (atrial), and breast; psammomatous melanotic schwannomas; epithelioid blue nevi of skin and mucosae; growth hormone-producing pituitary adenomas; and testicular Sertoli cell tumors. Components of the Carney complex have been described previously as the NAME (nevi, atrial myxoma, myxoid neurofibroma, ephelides) and LAMB (lentigines, atrial myxoma, mucocutaneous myxoma, blue nevi) syndromes. Peutz–Jeghers syndrome is also an autosomal dominant disorder characterized by mucocutaneous lentigines which are present at birth or appear during childhood in combination with intestinal polyposis. The skin lesions have an acrofacial distribution pattern and favor the perioral region. Mucosal lesions may affect the palate, tongue, buccal mucosa, and conjunctivae. The major entity in the differential diagnosis is Laugier–Hunziker syndrome in which there are acromucosal lentigines and longitudinal melanonychia, but no consistent internal manifestations (Fig. 112.5). In partial unilateral lentiginosis, also referred to as segmental lentiginosis, there is unilateral clustering of lentigines, suggesting a developmental abnormality of melanocytes. The onset is often during childhood and the individual lentigines are well circumscribed, varying from 2 to 10 mm in diameter. There is no background hyperpigmentation (as in nevus spilus) and the lesion can expand in a wavefront-like manner. Patients with facial lesions may have ocular involvement and CALMs may also be present. Partial unilateral lentiginosis may be associated with mosaic (segmental) NF1.

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Fig. 112.5 Labial and acral lentigines in two patients with Laugier– Hunziker syndrome. A Multiple hyperpigmented macules on the lower lip and a few on the tongue; Peutz–Jeghers syndrome can have a similar clinical appearance.   B Numerous lentigines on the palms. B, Courtesy,  

Drs Tello Flores and Sánchez Félix.

Pathology Lentigo simplex exhibits increased numbers of melanocytes in the basal layer of elongated epidermal rete ridges. Increased melanin in the basal layer and sometimes even in the upper layers of the epidermis and stratum corneum is commonly observed. Melanophages and a mild inflammatory infiltrate are often present in the superficial dermis. Lesions on mucous membranes, including the lips, show acanthosis with or without elongation of the rete ridges (Fig. 112.6). Slight melanocytic hyperplasia is usually observed, but may be absent. Hyperkeratosis, telangiectasia, activated fibroblasts, and large dendritic melanocytes have been described in labial melanotic macules. Some acral and mucosal lesions have been reported to exhibit cytologic atypia of the melanocytes. Ultrastructurally, melanin macroglobules have been observed within the melanocytes, as well as in keratinocytes and melanophages. These are not specific for lentigo simplex, since they have been described in other pigmented lesions (see above).

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Differential Diagnosis The differential diagnosis of a solitary lentigo simplex consists primarily of a junctional melanocytic nevus, a relatively flat form of compound melanocytic nevus, solar lentigo, and ephelis. In some instances, cutaneous melanoma, pigmented spindle cell nevus, and cutaneous intracorneal hemorrhage might enter into the differential diagnosis. Although there is a continuum from simple lentigo to junctional melanocytic nevus, the simple lentigo is distinguished from melanocytic nevi by the absence of distorted skin markings when viewed with side-lighting, and a lentigo simplex is often smaller than a melanocytic nevus. That said, histopathologic examination may be required for discrimination as melanocytic nests are not found in lentigo simplex. Lentigo simplex is usually distinguished from a solar lentigo by its smaller size, symmetry, uniform pigmentation, and lack of relationship to sun-exposed sites. However, this clinical distinction may not be possible in some instances.

Treatment 1960

In general, there is no need to treat a benign-appearing lentigo simplex. Lesions on acral or mucous membranes should be evaluated carefully and, if clinically atypical, should be considered for biopsy to assess for melanocytic atypia. Patients with both generalized and localized

Fig. 112.6 Labial melanotic macule (lentigo) – histopathologic features. Hyperpigmented rete ridges are broader than in the typical lentigo. In addition to basilar hyperpigmentation and melanophages, a few dendritic processes of melanocytes are seen. Courtesy, Lorenzo Cerroni, MD.  



DERMAL MELANOCYTOSIS Synonyms:  ■ Congenital dermal melanocytosis: • Mongolian spot

Key features ■ Blue to blue–gray patch present at birth, whose primary location is lumbosacral ■ More common in Asians ■ Usually resolves during childhood ■ Sparse dendritic melanocytes in the deeper dermis

CHAPTER

112 Benign Melanocytic Neoplasms

Fig. 112.7 Dermal melanocytosis (Mongolian spots) in a child with neurofibromatosis 1. Surrounding each café-au-lait macule there is an absence of the characteristic blue discoloration.

lentiginosis should undergo investigation to exclude systemic disease (see Table 112.2).

Epidemiology Dermal melanocytosis is usually present at birth or appears within the first weeks of life; rarely, lesions appear after early childhood16,17. Both sexes seem to be affected equally. Dermal melanocytosis usually regresses during early childhood, but it can persist and was seen in 4% of 9996 Japanese males between 18 and 22 years of age. It occurs in all races, with a frequency in one study of 100% in Malaysians, 90–100% in Mongolians, Japanese, Chinese and Koreans, 87% in Bolivian Indians, 65% of blacks in Brazil, 17% of whites in Bolivia, but only 1.5% of whites in Brazil. The racial differences in the frequency of this abnormality suggest that genetic factors influence survival of dermal melanocytes (see Ch. 65). Microscopically, histologic findings consistent with dermal melanocytosis can be found in the presacral area of 100% of newborns, irrespective of race16.

Pathogenesis The blue color in dermal melanocytosis is secondary to melaninproducing melanocytes residing within the middle to lower dermis. Melanocytes appear in the dermis during the 10th week of gestation, and then either migrate into the epidermis or undergo cell death, except for melanocytes in the dermis of the scalp, extensor aspects of the distal extremities, and the sacral area. The latter is the most common site for dermal melanocytosis. The bluish coloration of dermal melanocytosis results from the Tyndall phenomenon: dermal pigmentation appears blue because of decreased reflectance of light in the longerwavelength region compared with the surrounding skin. Longer wavelengths, such as red, orange and yellow, are not reflected, compared with the shorter wavelengths of blue and violet, which are reflected17.

Clinical Features The classic location is the sacrococcygeal and lumbar regions and the buttocks, followed by the back (Fig. 112.7). Dermal melanocytosis may consist of a single or multiple patches and usually involves BRAF, RET > MET.  

Familial atypical mole and melanoma syndrome* BAP1 cancer syndrome – atypical epithelioid nevi/tumors, uveal melanomas, mesothelioma Carney complex (NAME/LAMB syndromes) – see Table 112.2 Turner syndrome – webbed neck, congenital lymphedema (partial or complete loss of X chromosome in females) Noonan syndrome (mutations in multiple genes including PTPN11, RAF1, KRAS, SOS1) > other RASopathies (e.g. LEOPARD [Noonan with multiple lentigines] syndrome, cardiofaciocutaneous syndrome, Costello syndrome; see Ch. 55) Ectrodactyly, ectodermal dysplasia, and cleft lip/palate syndrome (EEC syndrome; TP63 mutations) Goeminne syndrome – torticollis, keloids, cryptorchidism, and renal dysplasia Kuskokwim syndrome – congenital joint contractures, skeletal deformities (FKBP10 mutations) Mulvihill Smith syndrome – progeroid short stature with pigmented nevi Trichorhinophalangeal syndrome type II (Langer–Giedion syndrome) Tricho-odonto-onychial dysplasia

*OMIM designation is “Susceptibility to cutaneous melanoma”. Table 112.4 Genetic syndromes associated with numerous acquired melanocytic nevi. Adapted from ref 98.  

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18 Neoplasms of the Skin



$

%

D

Usually, blue nevi are solitary, but they may be multiple or agminated or may arise with a nevus spilus or plaque blue nevus. Concentric, target-like lesions (target blue nevi) have been described as well. Dermoscopically, a blue nevus is characterized by homogeneous blue–gray to blue–black pigmentation (see Ch. 0).

Cellular blue nevi Cellular blue nevi are blue to blue–gray or black nodules or plaques, generally 1 to 3 cm in diameter but sometimes larger (Fig. 112.10)24,25. Their surface is often smooth but sometimes irregular. The most common sites are the buttocks, sacrococcygeal area and scalp, followed by the face and feet. Congenital cellular blue nevi, some with satellite lesions, have been reported, as have benign or malignant cellular blue nevi arising within congenital melanocytic nevi. The ratio of common blue nevus to cellular nevus is at least 5 : 1.

Epithelioid blue nevi Epithelioid blue nevi were first reported as a feature of the Carney complex (see Table 112.2); however, they also may occur sporadically26. These lesions have a predilection for the trunk and extremities and rarely develop on orogenital mucosa. Histologically, they may be indistinguishable from pigmented epithelioid melanocytoma.

Pigmented epithelioid melanocytoma

1964

Fig. 112.9 Common blue nevi – clinical and histopathologic features. A Well-circumscribed, dark blue flat papule. B Dark blue–black papule in a patient with more darkly pigmented skin. C Blue papule with an irregular, micropapular surface. D,E Heavily pigmented, spindle-shaped melanocytes as well as melanophages within the dermis; the melanocytes are denser than in dermal melanocytosis or nevus of Ota. A–C, Courtesy, Julie V Schaffer, MD; D,E,

This somewhat controversial term has been proposed as one that unifies epithelioid blue nevi (described above) and lesions previously reported as “animal-type”, “melanophagic”, or “pigment synthesizing” melanomas. The latter are characterized by marked melanin production and a resemblance to certain melanizing tumors in animals27. The lesions seem to have a low-grade potential for regional metastases, but rarely for non-regional metastases; they almost never result in overt malignant behavior and death of patients. In one study, all eight epithelioid blue nevi that arose in patients with Carney complex (with

&

Courtesy, Lorenzo Cerroni, MD.

E

confirmed PRKAR1A mutations) showed loss of expression of protein kinase A regulatory subunit 1-α (the product of PRKAR1A) as did 28 (82%) of 34 sporadic pigmented epithelioid melanocytomas, suggesting a relationship28.

Malignant blue nevi (cutaneous melanoma arising in or having features of blue nevus) Malignant blue nevi are rare forms of cutaneous melanoma most commonly arising within cellular blue nevi29. They tend to show progressive enlargement, often measuring several centimeters in diameter, and have a multinodular or plaque-like appearance. The scalp is the most common site of occurrence and lymph nodes are the most common sites of metastasis. Malignant blue nevi can arise in a previously benign cellular blue nevus, in a nevus of Ota or Ito, or de novo.

Pathology The common or ordinary blue nevus is composed of elongated and often slightly wavy melanocytes with long, branching dendrites (Fig. 112.9D,E). The melanocytes, with their long axes parallel to the epidermis, lie grouped or in bundles in the upper and mid dermis. Occasionally, they extend into the subcutaneous tissue or approach the epidermis but do not alter it. Most of the melanocytes are filled with numerous fine melanin granules, often completely obscuring their nuclei as well as extending into their dendrites. Variable numbers of melanin-laden macrophages are also present. The amount of collagen is usually increased, giving the lesion a fibrotic appearance. Melanin content may be minimal in the hypopigmented variant. In a cellular blue nevus, one often observes deeply pigmented dendritic melanocytes (as in a common blue nevus) in addition to nests and fascicles of spindle-shaped cells with abundant pale cytoplasm containing little or no melanin (see Fig. 112.10B). The aggregates of spindle cells may be arranged in intersecting bundles extending in various directions, a disposition resembling the storiform pattern of

Differential Diagnosis The clinical differential diagnosis of a common blue nevus includes traumatic tattoo, combined nevus, vascular lesions including venous lake and angiokeratoma, sclerosing hemangioma, primary and metastatic melanoma, pigmented spindle cell nevus, atypical nevus, dermatofibroma, papular pigmented basal cell carcinoma, and glomus tumor. For cellular blue nevus, especially with satellitosis, malignant blue nevus needs to be considered, and when the lesion is on the face, nevus of Ota. Blue nevi also need to be distinguished from a cutaneous neurocristic hamartoma, a complex proliferation of nevus cells, Schwann cells, and pigmented dendritic and spindled cells. Histologically, epithelioid blue nevi and pigmented epithelioid melanocytomas must be differentiated from primary or metastatic melanoma as well as tumoral melanosis due to complete or almost complete regression of melanoma. Cellular blue nevi, especially those with atypical features, need to be distinguished from malignant blue nevi. Occasionally, cutaneous metastases of melanoma can simulate a blue nevus.

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112 Benign Melanocytic Neoplasms

neurofibroma. By electron microscopy, the spindle-shaped cells contain melanosomes with little or no melanization. However, melanin production within these cells and a transition to bipolar dendritic nevus cells have been documented. Penetration of rounded, well-defined cellular islands into the subcutaneous tissue is frequently noted in cellular blue nevi. Some of the cells may appear atypical, with nuclear pleomorphism accompanied by multinucleated giant cells, rare mitoses, and inflammatory infiltrates. Lastly, while there are classic histopathologic differences between common and cellular blue nevi, overlapping features are seen in some lesions. Occasionally, lymph nodes draining the anatomic site of a cellular blue nevus contain blue nevus cells. The foci, found either in the marginal sinuses or in the capsule, are usually small, discrete and peripherally located. They may result from passive transport or represent arrested migration from the neural crest. These “benign metastases” are found in 5% of the reported cases of cellular blue nevi. Atypical cellular blue nevi demonstrate one or more of the following features compared to conventional cellular blue nevi: larger size (>1–2 cm), asymmetry, ulceration, infiltrating features, cytologic atypia, mitoses, and necrosis30. Such lesions have been associated with lymph node metastases and evolution to frank melanoma. These lesions require further study since their biologic potential is difficult to predict. Epithelioid blue nevi and pigmented epithelioid melanocytomas are typified by dermal (and sometimes junctional) aggregates of enlarged epithelioid melanocytes often containing coarsely granular melanin pigment and prominent nucleoli. These cells are often admixed with heavily pigmented spindled and dendritic melanocytes as well as melanophages. Cytologic atypia and dermal mitoses may be present. Combined nevus is discussed later in the chapter.

Treatment Blue nevi that are recessive dystrophic > recessive simplex* • Bullae secondary to sulfur mustard (mustard gas) exposure * • •

Scarring processes Genital lichen sclerosus†



Systemic immunosuppression Chemotherapy, particularly for childhood hematologic malignancies*,†,‡ Allogeneic bone marrow transplantation‡ • Solid organ transplantation, particularly renal and with the use of azathioprine*,‡ • HIV infection/AIDS * • Chronic myelogenous leukemia * • TNF inhibitor therapy ,‡ * • Cyclosporine, azathioprine * • •

Increased hormone levels Pregnancy*,§ Growth hormone (increased size, not number, of nevi) • Addison disease * • Thyroid hormone * • α-Melanocyte stimulating hormone analogue (afamelanotide) * • •

Other Sorafenib, vemurafenib, sunitinib, encorafenib, radotinib, regorafenib, nilotinib* • Atopic dermatitis in children (conflicting results in different studies) • Postoperative fever * • Seizures or electroencephalographic abnormalities * •

*Eruptive nevi have been reported.

†An increased number of atypical nevi may also be seen. ‡Nevi have a predilection for the palms and soles. §Relative immunosuppression may also play a role; an increase in the size or number of nevi

has not been clearly demonstrated for pregnant women in general. Melanoma may grow at an accelerated pace during pregnancy.

Table 112.5 Triggers for the development and/or growth of melanocytic nevi. TNF, tumor necrosis factor. Adapted from Schaffer JV, Bolognia JL. The biology of  

melanocytic nevi. In: Nordlund JJ, Boissy RE, Hearing VJ, et al. (eds). The Pigmentary System: Physiology and Pathophysiology, 2nd edn. Oxford: Blackwell Publishing, 2006:1092–125.

of melanocytic nevi correlates with increased melanoma risk (see Ch. 113).

Melanocytic nevi associated with epidermolysis bullosa Distinctive melanocytic nevi termed “epidermolysis bullosa (EB) nevi” or “EB nevi” may develop at the sites of antecedent bullae or erosions primarily in patients with forms of EB that are recessively inherited (see Ch. 32)34. These nevi can have a strikingly large size (up to 3 cm) as well as asymmetry, border irregularity, dark color, and satellitosis. Their development may be related to repetitive disruption of the basement membrane zone with the promotion of nevus cell proliferation or the dispersion of nevus cells into the blister cavity with their subsequent proliferation in its floor. Although there are no reports of cutaneous melanoma developing at the sites of EB nevi, the former can occasionally arise within the setting of EB; thus longitudinal observation is warranted.

Melanocytic nevi associated with lichen sclerosus Occasionally, melanocytic nevi develop in sites of genital lichen sclerosus35. The lesions are often dark brown to black in color, irregular in



B,D,F, Courtesy, Lorenzo Cerroni, MD.

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112 Benign Melanocytic Neoplasms

Fig. 112.11 Common acquired melanocytic nevi – clinical and histopathologic features. A,B Junctional nevus – dark brown macule with lighter brown rim and regular nests of small, uniform nevomelanocytes at the dermal– epidermal junction. C,D Compound nevus – light to medium brown papule and both junctional and dermal nests of nevus cells. E,F Intradermal nevus – soft light pink papule and nests of nevus cells within the dermis.

outline, and can measure ≥6 mm. As a result, the possibility of melanoma is frequently considered and histologic distinction is not always simple.

Pathology

Fig. 112.12 Longitudinal melanonychia due to a benign melanocytic nevus of the nail matrix. Note the pseudo-Hutchinson sign. Courtesy, Julie V Schaffer, MD.  

Melanocytic nevi contain intraepidermal or dermal collections of nevus cells or both (Fig. 112.11B,D,F). The cells within the junctional nests have round, ovoid or fusiform shapes and are arranged in cohesive nests; with the exception of unusual amelanotic variants, these cells contain melanin. In the superficial dermis, the cells usually have epithelioid cell characteristics and contain amphophilic cytoplasm and, frequently, granular melanin. The nuclei have uniform chromatin with a slightly clumped texture. Deeper in the dermis, there is a diminished content of cytoplasm, such that the cells resemble lymphocytes. There may be a further transition to cells separated by fine connective tissue and assuming a spindled configuration, similar to fibroblasts or Schwann cells.

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EB nevi are best considered exaggerated variants of recurrent/ persistent melanocytic nevi (see below). Thus they usually exhibit asymmetry and considerable variation in the overall architecture of the nevus, including the junctional nests. Pagetoid melanocytosis and cytologic atypia may be present, as well as fibroplasia, a lymphocytic infiltrate, and melanophages. In melanocytic nevi associated with lichen sclerosus (LS), the features of a genital nevus are superimposed on the changes of LS, which can vary from subtle to obvious. Irregular and confluent junctional nests are often accompanied by cytologic atypia. The changes of LS may suggest regression, and if the inflammatory component is significant, it may hinder assessment of the nevus cells. Findings that favor a genital nevus (rather than melanoma) include a diameter 2–3 mitoses/mm2), especially deep; significant pagetoid spread; prominent confluence and high cellular density of melanocytes in the dermis; and lack of maturation. A grading protocol for atypical Spitz nevi in children and adolescents has been formulated (eTable 112.1)45. Studies utilizing comparative genomic hybridization and fluorescence in situ hybridization techniques have identified copy number increases of chromosome 11p, sometimes accompanied by HRAS mutations (HRAS is located on 11p), in subgroups of Spitz nevi46. Additional chromosomal abnormalities (e.g. gain of 1p) have been found in atypical Spitz tumors47. However, more studies are needed before the identification of such genetic alterations can be used to predict the biologic behavior of Spitz nevi. Malignant or metastasizing Spitz tumors are exceedingly rare lesions with features of atypical Spitz tumors plus a single regional lymph node metastasis, but no subsequent disease progression. Since such lesions are only rarely encountered, they have not been sufficiently studied to know their biologic nature and how (and if) they differ from conventional melanomas. Melanocytic nevi/tumors with BAP1 mutations (“Wiesner nevi”) were originally described in two families in which affected individuals had multiple pink nevi with epithelioid and atypical features histologically. These individuals were found to have inactivating germline mutations in BAP1, which encodes a ubiquitin carboxy-terminal hydrolase48. Subsequently, subsets of sporadically occurring atypical epithelioid cell tumors with similar histologic patterns were also found to harbor loss of or inactivating mutations in BAP149. Specifically, these nevi tend to have a biphasic configuration, with dermal nodular aggregates of large epithelioid melanocytes often associated with a conventional nevus component. In addition to this “combined” pattern, these nevi differ from typical Spitz tumors by the presence of lymphoid infiltrates and by being composed of epithelioid cells with abundant amphophilic cytoplasm, pleomorphic and vesicular nuclei, and enlarged nucleoli49. Although individuals harboring germline BAP1 mutations may have an increased risk of developing uveal and/or cutaneous melanoma, to date there is insufficient data to predict the clinical behavior of either their atypical epithelioid cell tumors or the sporadically occurring atypical nevi that harbor BAP1 mutations.

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Fig. 112.17 Spitz nevus – histopathologic features. A Dome-shaped with sharply demarcated and symmetric proliferation of spindled and epithelioid melanocytes at the dermal–epidermal junction and within the papillary dermis; there is also regular epidermal hyperplasia. B Nests of cohesive spindled and epithelioid melanocytes with clefts between the nests and the hyperplastic epidermis. Note a “Kamino body” (arrow). Courtesy, Lorenzo Cerroni, MD.  

reticular dermis in an inverted-wedge configuration. The closely apposed nests of cells within a uniformly hyperplastic epidermis often contribute to a so-called “raining-down” appearance (Fig. 112.17). Both mononuclear and multinucleate giant epithelioid cells are frequently observed. These cells extend into the subjacent dermis both as single cells and as nests or fascicles. In general, there is orderly infiltration of the dermal collagen by these nests or cells with so-called maturation, i.e. gradual diminution of nuclear and cellular sizes. The individual cells usually have abundant cytoplasm that stains slightly bluish or pink and nuclei with open chromatin patterns. Rather uniform nucleoli are usually also noted. Occasionally, bizarre cytologic features, necrotic cells, and mitotic figures are found within even the most banal lesions. Intraepidermal eosinophilic globules (Kamino bodies) are commonly found in Spitz nevi, but may occasionally be encountered in other melanocytic tumors including cutaneous melanoma.

Differential Diagnosis The clinical differential diagnosis of Spitz nevi is wide and includes other melanocytic nevi, particularly intradermal nevi, hemangiomas, pyogenic granulomas, verrucae, mollusca contagiosa, juvenile and adult xanthogranulomas, dermatofibromas, mastocytomas, and adnexal tumors. The fundamental diagnostic problem is the histologic differentiation of Spitz nevus from cutaneous melanoma. The latter distinction is one of the most difficult problems in all of pathology and at present is subjective, based on the experience of the pathologist, and the careful weighing of a number of clinical and histopathologic parameters summarized in Table 112.7.

Pathology

Treatment

Spitz nevi typically display striking nests of large epithelioid cells, spindle cells or both, usually extending from the epidermis into the

Because of the frequent diagnostic difficulty in classifying these lesions, histologic evaluation of the entire lesion is highly recommended.

ASSESSMENT OF ATYPICAL SPITZ TUMORS IN CHILDREN AND ADOLESCENTS FOR RISK FOR METASTASIS

Parameter

Score

Age (years) Pre-pubertal

0

Post-pubertal

1

Diameter (mm) 0–10

0

>10

1

Involvement of subcutaneous fat Absent

0

Present

2

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112 Benign Melanocytic Neoplasms

Online only content

Ulceration Absent

0

Present

2 2

Mitotic activity (per mm ) 0–5

0

6–8

2

≥9

5

eTable 112.1 Assessment of atypical Spitz tumors in children and adolescents for risk for metastasis. Total score and risk for metastasis: 0–2, low risk; 3–4, intermediate risk; 5–11, high risk.  

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Parameter

Spitz nevus

Melanoma

Age

Young age, especially prepubertal, favors a benign process

Exceedingly rare in pre-pubertal children; outnumber Spitz nevi in patients >30 years of age

Anatomic site

May occur anywhere, but favor the lower extremities and particularly in children the head and neck region

Most often on the trunk (back) in men and distal lower extremities in women; favor intermittently sun-exposed skin, but may occur anywhere

Size

Often 100 on the total skin surface) as well as the presence and number of atypical nevi, as defined by size (e.g. >5, 6, or 10 mm), irregular or illdefined borders, variation in color, macular component, etc. (Tables 112.8 & 112.9)54–60. Despite the seemingly logical conclusion that histopathologically atypical nevi should be associated with increased melanoma risk, relatively limited data thus far have shown such a relationship. Furthermore, studies examining the relationship between clinically atypical melanocytic nevi and histopathologically atypical melanocytic nevi have shown a poor correlation. Therefore, the “dysplastic” nevus cannot be considered a distinct clinicopathologic entity. At present, melanoma risk assessment of patients is based almost solely on gross morphologic parameters of nevi, i.e. total numbers of nevi on the skin surface and the presence and number of clinically atypical melanocytic nevi, along with other factors such as personal or family history of melanoma (see Ch. 113). The term “atypical melanocytic nevus” undoubtedly encompasses a large and heterogeneous group of nevi including: nevi with atypical clinical features, which have been termed simply “atypical nevi”; in general, these atypical nevi can simulate melanoma clinically; this group of nevi includes not only “atypical” or “dysplastic” nevi, but also some congenital and combined melanocytic nevi, as well as Spitz nevi and pigmented spindle cell nevi nevi with abnormal histopathologic features nevi with both abnormal clinical and histopathologic features nevi with histopathologic features that are equivocal or of unknown significance. The latter group of nevi may demonstrate findings that may be reactive or proliferative in nature rather than neoplastic54–63.

Clinical Features Atypical nevi occupy an intermediate position on a continuum with common nevi at one end and cutaneous melanoma at the other end, and, as a result, they overlap with both. No single feature is diagnostic of atypical melanocytic nevi; rather, a constellation of clinical and dermoscopic findings is required for their recognition (Figs 112.19 & P9). However, the greater the number of clinical abnormalities present, the greater is the likelihood that the lesion will prove to be histologically atypical, but there are many exceptions. The following gross morphologic features are commonly observed in atypical melanocytic nevi: Asymmetry: atypical melanocytic nevi often lack mirror-image symmetry. Greater asymmetry suggests greater likelihood of atypicality. Size: atypical melanocytic nevi may be of any size but generally range from 3 to 15 mm in greatest diameter. There is generally a positive correlation between increasing size and likelihood of architectural disorder and atypical features. Borders: atypical melanocytic nevi often exhibit irregular and ill-defined borders, but not typically the notched or scalloped borders of melanoma. Coloration: atypical melanocytic nevi often have many colors. They commonly exhibit irregularity of pigmentation with two or

• • • •

MELANOMA RISK ASSOCIATED WITH CLINICALLY ATYPICAL MELANOCYTIC NEVI: COMPARISON OF OCCURRENCE IN MELANOMA PATIENTS VERSUS CONTROLS

Study

Country

Definition

Melanoma patients (%)

Controls (%)

Relative risk

Roush et al. & Nordlund et al.

Australia

>5 mm, irregular border, and haphazard pigmentation

34

7

7.7

MacKie et al.

Scotland

>5 mm and either irregular pigmentation or inflammation

38

20

2.1–4.5*

Holly et al.

US

At least 3 of 6 criteria: ill-defined border, irregular border, irregular pigmentation, >5 mm, erythema, accentuated skin margins

55

17

3.8–6.3†

Halpern et al.

US

>4 mm, macular component, variegation of color, and irregular or indistinct border

39

7

8.8

Garbe et al.

Germany

At least 3 of 5 criteria: >5 mm, irregular margins, ill-defined border, color variation, macular and papular components

45

5

7

*† Relative risk for one or two atypical nevi, 2.1; for three or more atypical nevi, 4.5. Relative risk for one to five atypical nevi, 3.8; for six or more atypical nevi, 6.3.

Table 112.9 Melanoma risk associated with clinically atypical melanocytic nevi: comparison of occurrence in melanoma patients versus controls54–60.  

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Fig. 112.19 Atypical melanocytic nevi. A Although this “fried egg” nevus is at least 7 mm in size, it is symmetric and does not need to be excised. B “Eclipse” nevi, characterized by a tan center and brown rim, are commonly found on the scalp of children who go on to develop numerous melanocytic nevi. The associated dermoscopic patterns are those seen in benign melanocytic nevi. A,

Fig. 112.20 Atypical melanocytic nevi. A There is asymmetry as well as several shades of brown, simulating the clinical features seen in cutaneous melanoma.   B In addition to multiple atypical nevi, patients can have numerous banal nevi.

Neoplasms of the Skin



Courtesy, Jean L Bolognia, MD; B, Courtesy, Julie V Schaffer, MD.



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three shades of brown, e.g. tan, brown, and dark brown (Fig. 112.20A). They may also have areas that are pink, gray, brown– black, or skin-colored. Of note, some atypical melanocytic nevi present with fairly uniform coloration and an erythematous appearance. Atypical melanocytic nevi most frequently involve the trunk and also show a striking (though less common) predilection for the scalp and for doubly covered areas of the body (breasts in women and bathingtrunk area in men). Their numbers may range from one or two to hundreds (Fig. 112.20B). When multiple large lesions are present, their prominence is noteworthy, and while there may be variability, patients often have a “signature” nevus, clinically and histologically. Localized patterns such as linear tracts, clusters, or figurate arrays may also be seen in patients with numerous nevi. The overwhelming majority of atypical melanocytic nevi are clinically stable. However, there is definite evidence that some lesions eventuate in cutaneous melanoma. Progressive abnormalities in DNA content, cytogenetic alterations, and increased expression of melanocyteassociated antigens by immunohistochemistry have been correlated with progressive degrees of histologic atypia. Although these latter findings suggest a progression of atypical melanocytic nevi toward melanoma, atypical melanocytic nevi are not inevitable precursors to melanoma, and their presence can be viewed as a phenotypic marker of “an entire skin at risk”.

Fig. 112.21 Atypical melanocytic nevus – histopathologic features. Note confluent nests of melanocytes at the dermal–epidermal junction and scattered solitary melanocytes in the lower portion of the epidermis. Courtesy,  

Lorenzo Cerroni, MD.

Pathology

1974

Prototypic atypical melanocytic nevi are described as having several noteworthy architectural features (Fig. 112.21). Compared to ordinary nevi, these nevi are often larger (commonly >5 mm in diameter); are more poorly circumscribed; are slightly more asymmetric; are relatively flat, particularly at the peripheries of the lesion; and

often show heterogeneity. In atypical melanocytic nevi, the junctional nests frequently extend beyond the dermal component (the “shoulder” phenomenon). Of particular importance are abnormalities of the intraepidermal component. Architectural or organizational disorder occurs in two

Differential Diagnosis The differential diagnosis of pigmented lesions approximately 4 to 15 mm in size includes both melanocytic and keratinocytic lesions.

Among melanocytic proliferations, the principal diagnostic considerations are common acquired nevi, small congenital nevi, and cutaneous melanoma. The atypical melanocytic nevus is characterized by haphazard, irregular coloration, including hues of pink, tan, brown and even black, and irregularity in shape (features it shares with melanoma). The other nevic lesions either show symmetry and/or uniformity of coloration or, when irregularly colored, show orderly gradations or patterns of pigmentation. Dermoscopy may also play an important role in evaluating atypical melanocytic nevi (Fig. P5). Although atypical melanocytic nevi can clinically resemble melanoma, many of these lesions fall into one of the benign dermoscopic melanocytic patterns (see Fig. P9). The features employed to evaluate a melanocytic nevus include colors, symmetry, and organization. Benign melanocytic lesions tend to have few colors and are symmetric with regard to the distribution of colors and structures. Organization refers to the distribution of structures in a lesion. When these structures are symmetrically distributed and there are fewer than three colors (light brown, dark brown and black) noted, they create a pattern seen in many benign lesions. The most common benign patterns are reticular, globular, and homogeneous (see Fig. 0.38). In addition, there are the subset patterns of reticular– homogeneous, reticular–globular, and globular–homogeneous (see Fig. P9)62. Of particular note, a subset of atypical melanocytic nevi may demonstrate a “malignant” melanocytic dermoscopic pattern. These lesions often have many colors and are asymmetric and disorganized with respect to a non-uniform distribution of colors and structures. It is recommended that these lesions be biopsied. Finally, another subset of atypical melanocytic nevi is characterized by uncertain melanocytic dermoscopic patterns. Just as the clinical and histologic features of atypical melanocytic nevi are a continuum, so too are the features with dermoscopy. These lesions should either be serially monitored or undergo biopsy. Lichen planus-like keratoses, pigmented seborrheic keratoses, solar lentigines, pigmented actinic keratoses, pigmented Bowen disease, and basal cell carcinoma may exhibit pink, tan, brown, or dark brown coloration.

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112 Benign Melanocytic Neoplasms

patterns that are often present simultaneously to a varying extent. The first is lentiginous melanocytic proliferation that is almost always associated with elongated epidermal rete ridges. In general, the basilar melanocytes are concentrated in the lowermost portions of the rete ridges, and the frequency of basilar melanocytes varies greatly, e.g. from one melanocyte per one to two keratinocytes to the melanocytes replacing the basilar keratinocytes and resulting in a confluent, clustered, or multilayered cellular appearance. The second pattern includes nests of melanocytes irregularly disposed along and between the rete ridges in a more haphazard fashion, as compared to ordinary nevi. These nests vary in size and shape, are frequently elongated, commonly have their long axes oriented along the dermal–epidermal junction, and contain variable numbers of cells. Colliding nests of melanocytes frequently fuse or “bridge”. Dyscohesion of cells within these nests is also common; this feature contrasts with the cohesive appearance of junctional nests of melanocytes in ordinary nevi. Often, atypical nevi have a higher density or concentration of melanocytes in the intraepidermal component than do banal nevi, and this may be a helpful feature in their recognition. Atypical melanocytic nevi with the latter two patterns usually exhibit cytologic atypia of their melanocytes. Such change is discontinuous and variable, from only a small percentage of cells demonstrating nuclear atypia to most cells being atypical. Cytologic atypia often has a general correlation with the degree of architectural abnormality present in a particular lesion. Pleomorphism of the nuclei (i.e. variation in size, shape, and staining properties) is perhaps the most characteristic attribute of the nuclear changes in atypical melanocytic nevi. However, nuclear enlargement and hyperchromatism also occur. The cells are frequently typified by a perinuclear clear space resulting from cytoplasmic shrinkage, which is an artifact of tissue processing. Criteria for grading the degree of cytologic atypia and even architectural abnormality have been proposed, but there is currently no consensus. Atypical melanocytic nevi may also contain a proliferation of atypical epithelioid melanocytes that resembles the epithelioid melanocytes in some forms of melanoma. This is characterized by prominent junctional nests of cells that are predominantly epithelioid in appearance, with round nuclei and finely granular melanin in their cytoplasm. The cells may also be disposed singly along the dermal–epidermal junction, with occasional pagetoid spread. Epithelioid cell proliferation may occur in a normal epidermis or in a hyperplastic epidermis, but the normal rete ridge pattern is retained. Cytologically, the melanocytes are enlarged and have variable degrees of nuclear enlargement, pleomorphism, hyperchromatism and, occasionally, prominent nucleoli. When these cells are in nests, they show some dyscohesion, but on the whole fill the nests completely. Mixtures of these intraepidermal patterns are common. The dermal component of atypical melanocytic nevi may be composed of typical nevus cells, such as those in any acquired nevus, or of cells that may exhibit atypia. In addition to the abnormal proliferative patterns described above, other frequent alterations, in particular changes related to host response, characterize intermediate nevi. Two forms of collagenous change occur in the papillary dermis. Most common is a condensation of dense, acellular collagen around the elongated epidermal rete; this is known as concentric eosinophilic fibrosis. A less common pattern consists of delicately layered, or laminated, collagen subjacent to the rete tips with fibroblasts disposed along the laminated collagen fibers in a linear array. This pattern is referred to as lamellar fibroplasia. A mixture of the two collagen patterns is not uncommon. Lymphocytic infiltrates, which usually are distributed in a perivascular fashion and less commonly in a band-like pattern, are also frequently observed in atypical melanocytic nevi. Finally, atypical melanocytic nevi usually have prominent vascularity throughout the papillary dermis, which is secondary to dilation and hypertrophy of existing vascular channels, rather than significant angiogenesis. The histopathologic criteria for atypical melanocytic nevi are still evolving, and, as already mentioned, many questions relating to the histopathology of these lesions are still unanswered.

Treatment As within any area of medicine, the physician is first obliged to do no harm. Such an approach is particularly germane to patients with atypical melanocytic nevi, in order to avoid overly aggressive procedures, surgery, and follow-up. Common sense should prevail at all times and consideration given as to whether the intervention will have any impact on potentially reducing mortality from melanoma. Treatment depends upon several factors including: (1) whether the patient presents with one or a few nevi versus numerous nevi; (2) if the patient has a personal history of melanoma; and (3) whether there exists a familial setting of atypical melanocytic nevi and/or melanoma. A gradient of melanoma risk has been clearly established for these various subsets of patients. Melanoma risk is probably continuous and increases with progressive increases in numbers of nevi, clinical atypia of nevi, and personal and familial occurrence of atypical nevi and melanoma. Regardless of the risk group, any pigmented lesion suspicious for melanoma and any persistently and significantly changing lesion should, in the authors’ opinion, be excised completely with approximately 2 mm margins for histopathologic examination. Some authors have advocated “deep” shave excision (saucerization) for superficial lesions, as long as the base of the lesion is removed. As opposed to partial punch biopsy, the latter allows for assessment of the overall architecture of the lesion and leads to less sampling error. A helpful rule of thumb in following patients with many atypical melanocytic nevi is to search for lesions that clearly stand out as different from the patient’s other (baseline) nevi; such lesions should be examined carefully. It should be kept in mind that new nevi will continue to develop and nevi may enlarge and change with time, especially in young individuals. One must use common sense in assessing this normal evolution of nevi and not be overly aggressive in removing such nevi. It is not mandatory to remove clinically atypical nevi simply to confirm or exclude atypical melanocytic nevi histologically. An acceptable practice is to follow such patients on a regular schedule

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18

with a total body skin examination plus dermoscopy, baseline photography, and/or digital dermoscopy, as preferred by the clinician. The frequency of follow-up examinations is individualized and is based on the previously mentioned risk factors, i.e. numbers and clinical atypia of nevi, lesion stability, and personal and family history of melanoma. For patients having clinically suspicious lesions removed, narrow surgical margins are advised. If lesions are “severely” atypical, re-excision is recommended because of frequent overlap with melanoma in situ. For atypical melanocytic nevi with lesser degrees of atypia, the answer regarding whether to re-excise is controversial. With any melanocytic lesion, it is important to know if the lesion has been adequately sampled and also if the lesion was considered to be clinically atypical. In general, if lesions are “mildly” atypical, no re-excision is recommended, as long as no significant residuum of the nevus is clinically apparent. If lesions are “moderately” atypical, the decision to re-excise is particularly difficult. Studies show that dermatologists tend to re-excise moderately atypical lesions if a biopsy margin is positive64. Despite this propensity for re-excision, available data do not necessarily support re-excision of all moderately atypical nevi. Independent retrospective studies examining the utility of re-excision of moderately dysplastic nevi conclude that excision of these nevi rarely results in a change in diagnosis. In one study of 127 re-excisions of dysplastic nevi, only 2 cases resulted in a clinically significant diagnostic change and both cases were initially read as “moderately-to-severely” dysplastic; no re-excision of a “moderately” dysplastic nevus (52 cases) resulted in a change in diagnosis65. In a second larger study of 1809 mildly and moderately atypical nevi, 765 were found to have positive margins and of these 495 underwent re-excision. Of the 495 re-excisions, only a single case resulted in a clinically significant change66. Therefore, the current data may not support a blanket recommendation to re-excise all moderately atypical nevi even if there are positive margins. Unfortunately, the discussion of whether or not to re-excise dysplastic nevi is greatly confounded by the lack of a uniform grading system amongst pathologists67,68. Often this leaves dermatologists erring on the side of caution when it comes to this clinical decision. Therefore, even when no residual lesion is clinically obvious, re-excision of a dysplastic nevus might be considered, depending upon a number of factors: the initial degree of concern clinically, the site (easy or difficult to visualize by the patient), the size of the nevus (versus the size of the biopsy), the patient’s ability and interest in following the site, the patient’s prior personal and family history of melanoma, and the color (more inclined with amelanotic lesions as assessing residuum is more difficult). In general, follow-up of patients with multiple atypical nevi, especially in the context of a personal or family history of melanoma, should be every 3 to 12 months, depending on the clinical situation. One should consider documentation of nevi by body charts and clinical photography as judged appropriate, with periodic updating. The authors have found that individual photographs of the most atypical or difficult-to-follow nevi are particularly helpful. Additional tools such as dermoscopy and/or digital imaging devices may be useful diagnostic aids. Finally, individuals presenting with atypical melanocytic nevi should have a family history taken for the presence of atypical melanocytic nevi and/or melanoma. First-degree blood relatives should be examined both for documentation and to assess and potentially diminish their own risks of developing melanoma.

CONGENITAL MELANOCYTIC NEVUS Synonyms:

Congenital nevomelanocytic nevus Variants (based upon size): • Small congenital melanocytic nevus • Medium-sized congenital melanocytic nevus • Large congenital melanocytic nevus • Giant congenital melanocytic nevus ■ Large or giant congenital melanocytic nevus: • Bathing trunk nevus • Garment nevus ■ ■

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Key features ■ Small congenital nevi are 20 to 40 cm and >40 cm in diameter (in adults), respectively, have a significantly higher risk for developing melanoma than do ordinary nevi ■ Neurocutaneous melanosis occurs in patients with multiple medium-sized congenital nevi and those with large/giant congenital nevi, especially when in a posterior axial location along with satellite lesions

Introduction Congenital melanocytic nevi are melanocytic nevi present at birth69,70– 79 . They consist of proliferations of benign melanocytes that may be intraepidermal, dermal, or both. Rarely, lesions appear after birth or within 2 years which are not otherwise remarkably different from congenital nevi and are therefore referred to as tardive congenital nevus. Some congenital melanocytic nevi may be just a few millimeters in size and appear clinically indistinguishable from common acquired nevi. In general, congenital melanocytic nevi are classified as small, intermediate- or medium-sized, large, and giant, based upon their size in adults. For practical purposes, small congenital nevi are 20 to 40 cm, and giant congenital nevi are >40 cm80. A congenital nevus ≥9 cm on the scalp or ≥6 cm on the trunk in a newborn places the child in the latter two size categories and these lesions often cover large areas of the body such as the arm, scalp, or even the entire dorsal surface from the scalp to the feet. Some authors base the distinction between small, intermediate, and large/ giant congenital nevi on their ease of removal. In this scheme, small congenital nevi generally may be removed by simple excision, mediumsized nevi often require staged excisions for closure, and large/giant nevi often cannot be removed or require multiple staged excisions and/or tissue expanders for removal. Neurocutaneous melanosis, also referred to as neurocutaneous melanocytosis, is a rare congenital syndrome characterized by: (1) the presence of either a large/giant (>20 cm) congenital melanocytic nevus or multiple (more than three) usually smaller congenital melanocytic nevi (or both), in association with meningeal melanosis or melanoma; (2) an absence of cutaneous melanoma except in patients with histologically benign meningeal lesions; and (3) an absence of meningeal melanoma except in patients with histologically benign cutaneous lesions75–78.

Epidemiology Estimates of the incidence of congenital nevi are imprecise since distinctions between relatively “small” congenital melanocytic nevi and acquired nevi are not well defined and histologic patterns vary considerably among congenital melanocytic nevi. When histologic confirmation is a criterion, the incidence may be as low as 0.6%; series based on clinical criteria have found an incidence as high as 2.5%. Large/giant congenital nevi are rare, with an estimated incidence of 0.005% (1 in 20 000). Patients with large/giant nevi often have multiple smaller (satellite) nevi as well, with greater numbers correlating with an increased risk of neurocutaneous melanosis (see below). Familial aggregation of congenital nevi has occasionally been reported.

Pathogenesis The precise pathogenesis of congenital melanocytic nevi has not been established. In one study of 32 truly congenital nevi, no BRAF mutations were detected, but 81% (26/32) harbored mutations in NRAS81. An origin from neural crest stem cells that have migrated to the skin appears almost certain. Individual melanocytes begin to appear in fetal skin before 40 days’ gestation. Given the observation of congenital divided nevi of the eyelid and the fact that the eyelids open during the sixth month of gestation, it appears that congenital melanocytic nevi develop some time during this interval. Patients with a large/giant

Clinical Features Small and medium-sized congenital melanocytic nevi are usually round or oval and fairly symmetric (Fig. P6). These lesions are usually slightly raised at birth and may be tan in color. They may or may not have associated hypertrichosis (Fig. 112.23A), and perifollicular hypo- or hyperpigmentation may be seen. Some congenital melanocytic nevi have rugose or pebbly surfaces (Fig. 112.23B). Lesions that begin as slightly raised tend with age to become more elevated; color darkening and the assumption of a verrucous appearance are also common. After an initial darkening during the first year or so of life, some congenital melanocytic nevi may actually become lighter in color with aging,

Fig. 112.22 Congenital melanocytic nevi associated with neurocutaneous melanosis. A Multiple medium-sized nevi. The patient had 25–30 such lesions. This presentation is most commonly associated with neurocutaneous melanosis. B Giant congenital nevus in an axial location with numerous satellite nevi, some of which have hypertrichosis. This patient died of intractable ascites due to the migration of melanocytes from the brain to the peritoneal cavity via his VP shunt. In the perianal region, the nevus was softer and somewhat “spongy” due to neurotization. Courtesy,

including satellite lesions. In addition, congenital nevi can develop the halo phenomenon (see below), and occasionally, congenital nevi completely regress, even without forming a halo. As hamartomas, congenital nevi can exhibit asymmetry and variation in color, develop papules and nodules (e.g. proliferative nodules), and undergo change over time; however, histologic examination of any concerning areas is recommended (Table 112.10). Areas within congenital nevi can also undergo neurotization and develop compressible, boggy plaques or nodules (Fig. 112.24). The dermoscopic structures seen in congenital nevi may include the following: globules, diffuse background pigmentation (structureless),

Fig. 112.23 Mediumsized congenital melanocytic nevi. A Hypertrichosis and slight heterogeneity in pigmentation. B More marked heterogeneity in pigmentation and topography, reflecting the hamartomatous nature of congenital nevi. Courtesy, Julie V Schaffer,

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Benign Melanocytic Neoplasms

congenital nevus and/or multiple satellite lesions should be thought of as having a systemic disease (Fig. 112.22), as nevus cells can be found in sites beyond the skin and central nervous system (CNS), such as the retroperitoneum.

MD.

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Fig. 112.24 Several areas of “neurotization” within a giant congenital nevus. The edges of the boggy plaques or nodules are demarcated by arrowheads. This phenomenon should not be confused with how cells of acquired nevi can display a neuroid differentiation within conventional intradermal nevi, sometimes characterized by Schwann cell-like features.  

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milia-like cysts, hypertrichosis, hyphae-like structures, and perifollicular pigment changes. Congenital nevi have repeatable dermoscopic patterns. The most common patterns are the reticular, globular, reticular–globular (see Fig. P6), diffuse brown pigmentation, and multicomponent. The multicomponent pattern is often difficult to distinguish from melanoma and requires either monitoring or biopsy. Varying numbers of satellite congenital melanocytic nevi often accompany large/giant congenital melanocytic nevi (see Fig. 112.22B). In one study, at least 80% of patients with large/giant congenital melanocytic nevi had satellite congenital melanocytic nevi. Such lesions typically resemble small or medium-sized congenital melanocytic nevi. Of note, some patients present with multiple medium-sized congenital nevi in the absence of a large congenital nevus (see Fig. 112.22A), and these individuals are at greatest risk for neurocutaneous melanosis (up to 70% in one study).

MANAGEMENT OF CHILDREN WITH GIANT CONGENITAL MELANOCYTIC NEVI

Surgical excision versus long-term clinical examination Consider surgical excision of the nevus (staged and/or with tissue expanders), typically in children at least 6 months of age in order to avoid the period of highest general anesthesia risk • If not excised or partial excision, lifelong examination of the nevus (including palpation) every 6 to 12 months plus baseline photography • Histologic examination of enlarging firm papulonodules and new areas of induration or ulceration* •

MRI of head and spine for the detection of neurocutaneous melanosis† (NCM) and other CNS abnormalities‡ Risk factors for NCM - multiple satellite lesions (≥20)§ - giant/“garment” nevus (>40 cm projected adult size) - posterior axial location (in some but not all studies) • If no risk factors and no neurologic symptoms, MRI not necessary • If at least one risk factor but asymptomatic, MRI should be considered prior to 4–6 months of age for highest sensitivity • In asymptomatic patients with intermediate risk (e.g. 20 cm), all nevi had a posterior axial location (involving the head, neck, back, and/or buttocks); 31 of 33 patients had satellite nevi. In another study, 80% had posterior axis involvement and 55% had more than 20 satellite nevi. Neurocutaneous melanosis is divided into symptomatic and asymptomatic, i.e. noted on screening MRI (Fig. 112.25). Symptomatic neurocutaneous melanosis presents with signs and symptoms of increased intracranial pressure, often due to hydrocephalus or mass effect, and it is associated with a poor prognosis. By MRI, there are several presentations of neurocutaneous melanosis, including: (1) multiple obvious postgadolinium-enhancing masses; (2) diffusely thickened leptomeninges noted by gadolinium enhancement; and (3) focal areas of increased signal on T1-weighted images. The first two forms are associated with a poor prognosis. A variety of intracranial and intraspinal anomalies (e.g. Dandy–Walker malformation, extensive arachnoid cysts) can be seen in association with neurocutaneous melanocytosis82.

APPROACH TO THE PATIENT WITH MULTIPLE MEDIUM-SIZED CONGENITAL NEVI OR A LARGE/GIANT CONGENITAL NEVUS WITH MULTIPLE SATELLITES

Giant CMN with multiple satellite lesions (≥20) ---OR--Multiple medium-sized CMN (≥3 but usually 10–20+)

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• Neurologic history and examination • Discuss MRI of brain and spine, with and without gadolinium (most sensitive in first 6 months of life)

+ Exam + MRI

− Exam + MRI

+ Exam − MRI

− Exam − MRI

Symptomatic NCM (~4%)

Asymptomatic NCM (~5–24%)

Neurologic abnormalities of uncertain etiology (~4%)

No evidence of NCM (70–85%)

• Refer to pediatric neurologist +/− pediatric neurosurgeon who will repeat MRI as clinically indicated • Consider postponing aggressive surgical interventions for the CMN because of poor prognosis

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• Refer to pediatric neurologist • Repeat MRI if symptoms develop/ worsen or in ~6–12 months

• Serial neurologic exams & developmental assessment • Repeat MRI if symptoms develop

Fig. 112.25 Approach to the patient with multiple mediumsized congenital nevi or a large/giant congenital nevus with multiple satellites. *A relatively high percentage of these patients have NCM. CMN, congenital melanocytic nevus; NCM, neurocutaneous melanosis  

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Although all sizes of congenital melanocytic nevi may be associated with melanoma, historical estimates of melanoma risk have been exaggerated because of referral bias and misdiagnosing the atypical melanocytic proliferations that develop in congenital melanocytic nevi as melanoma. The potential risk is probably related to size of the congenital melanocytic nevi, i.e. the larger the nevus, the greater the risk. At present it is thought that the melanoma risk associated with small congenital melanocytic nevi is low and probably not much more than that associated with acquired nevi. A prospective study of 230 mediumsized congenital melanocytic nevi in 227 patients, followed on average for 6.7 years, failed to document the development of a single case of melanoma. Similarly, in a longitudinal cohort study of 265 patients with medium-sized congenital melanocytic nevi, none developed melanoma. Thus, in general, the latter studies suggest that medium- (and small-) sized congenital melanocytic nevi are not associated with significantly increased risk for melanoma. On the other hand, several studies have noted substantial melanoma risk linked to large or giant congenital melanocytic nevi. In the same cohort study referred to above, Swerdlow et al.69 estimated that patients with congenital melanocytic nevi >20 cm had a standardized morbidity ratio of 1224 for the development of melanoma. In a prospective study of 92 patients with large/giant congenital melanocytic nevi72, three patients developed melanoma in extracutaneous sites (brain, CNS, retroperitoneum) during follow-up averaging 5.4 years. The latter authors calculated the cumulative 5-year life-table risk for melanoma to be 4.5%. The standardized morbidity ratio, which was calculated to be 239, was highly significant. In a review of 289 patients with large/giant congenital melanocytic nevi culled from the world literature73, 34 patients (12%) developed primary cutaneous melanoma within their nevi. All of the patients developing these melanomas had congenital melanocytic nevi in an axial location, i.e. the head and neck and/or trunk. No melanomas were associated with an extremity or satellite congenital melanocytic nevus. The median age at diagnosis of melanoma was 4.6 years (range: birth to 52 years; average age: 13.2 years). Twenty-one patients developed primary CNS melanomas. All of the latter patients had neurocutaneous melanosis and large/giant congenital melanocytic nevi in a posterior axial location; the median age at diagnosis was 3 years (range: 1 month to 50 years; average age: 11.6 years). An additional 10 patients presented with metastatic melanoma with an unknown primary. All of the latter patients had axial congenital melanocytic nevi. A study based on a database of 1008 patients with large/giant congenital melanocytic nevi or multiple medium-sized congenital melanocytic nevi found a significantly lower risk than in previous publications: 2.9% developed cutaneous melanoma associated with 0.8% deaths79. More recently, a comprehensive review of 14 studies that examined the development of melanoma in patients with congenital melanocytic nevi reported an overall risk of melanoma of 0.7% (in those with congenital melanocytic nevi of all types), with a risk of 2.5% and 3.1% in large and garment nevi, respectively83. When a cutaneous melanoma develops in a relatively small congenital melanocytic nevus, it appears most commonly at the dermal– epidermal junction in a fashion similar to that of other conventional melanomas. However, cutaneous melanomas arising in larger congenital melanocytic nevi can develop within the dermis, subcutaneous fat, or even deeper, as a distinct nodule84. Rarely, other malignant tumors may arise in these lesions, including rhabdomyosarcomas, malignant peripheral nerve sheath tumors, fibrosarcomas, leiomyosarcomas, osteogenic sarcomas, and liposarcomas. Leptomeningeal melanomas can arise in patients with neurocutaneous melanosis and most commonly involve the frontal and temporal lobes. As expected, these melanomas have a very poor prognosis.

Benign Melanocytic Neoplasms

Melanoma

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Fig. 112.26 Congenital melanocytic nevus – histopathologic features. A Scanning view with complexes of nevus cells extending into the deep reticular dermis and down adnexal structures. Melanocytes surround a hair follicle (B), extend along eccrine sweat ducts (C), and surround and infiltrate an arrector pili muscle (D). Courtesy, Lorenzo Cerroni, MD.  

of the lower reticular dermis, subcutaneous fat, fascia, and even deeper (Fig. 112.26). It is characteristic to observe nevus cells in a single-cell array throughout the middle or lower reticular dermis and even extending into the septa of the subcutis. Especially helpful is the presence of nevus cells surrounding (cuffing) and within the walls of blood vessels, within adnexal structures such as hair follicles and sweat glands, and within cutaneous nerves, particularly when in the lower half of the reticular dermis. Specifically, nevus cells may be found in the papillae and epithelium of hair follicles, in the sebaceous glands, in arrector pili muscles, and in the eccrine ducts of the lower dermis. There is often maturation and diminished cellularity with increasing depth within the dermis. Uncommonly, congenital melanocytic nevi may show striking neural differentiation suggesting a peripheral nerve sheath tumor such as a neurofibroma. Structures resembling Meissner corpuscles, Verocay bodies, or neuroid tubules may be observed. Neurocutaneous melanosis is defined by the proliferation of benign “melanotic cells” (a term used to avoid a more precise designation such as melanocyte or melanoblast) in the meninges. This melanosis may involve the convexities and base of the brain, the ventral surfaces of the pons and medulla, and the upper cervical and lumbosacral spinal cord.

Differential Diagnosis

Patients with large/giant congenital nevi can also have urinary tract anomalies, obstruction of orifices by the nevus (e.g. perianal), and infiltration of lymph nodes and the mother’s placenta by nevus cells.

Although large/giant congenital melanocytic nevi are quite distinctive, occasionally they are confused with plexiform neurofibromas, as the latter can have both hyperpigmentation and hypertrichosis. The differential diagnosis of small congenital nevi includes congenital smooth muscle hamartoma, atypical nevus, and melanoma. For medium-sized congenital nevi, an additional entity to consider is Becker melanosis. Of course, the possibility of melanoma exists for any clinically atypical area (e.g. darkening, nodularity) within a congenital nevus. The distinction between melanoma and a proliferating nodule can be difficult, but the latter tends to blend with the associated congenital nevus and has only mild atypia and occasional mitoses. Neurocutaneous melanosis and meningeal melanocytomas can also be seen in association with nevus of Ota and phakomatosis pigmentovascularis.

Pathology

Treatment

In contrast to common acquired nevi, which are confined to the papillary and upper reticular dermis, congenital nevi may exhibit infiltration

The treatment of congenital melanocytic nevi is primarily related to two factors: their increased risk for progression to melanoma and their

Additional associated abnormalities

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cosmetically disfiguring appearance. The decision to remove a congenital nevus is individualized and based on melanoma risk, age of the individual, anatomic location (especially proximity to vital structures), presence or absence of neurocutaneous melanosis, anticipated cosmetic outcome, and complexity of removal. The routine excision of uniform-appearing small and medium-sized congenital nevi no longer seems justified due to the low melanoma risk. An acceptable alternative to surgical excision is baseline photography, education, and yearly examination. The treatment of large/giant congenital nevi is more problematic, since melanoma risk is present from birth. If such large/giant nevi are to be excised, most authorities recommend delaying the procedure for at least 6 months so as to decrease the risk from general anesthesia (see Table 112.10). Since the prognosis of patients with symptomatic neurocutaneous melanosis is so poor, initial staged excisions of large/ giant congenital melanocytic nevi should be delayed in such individuals. MRI of the CNS should be considered for neonates with either large/giant congenital melanocytic nevi with multiple satellite nevi (especially if ≥20) or multiple medium-sized congenital nevi, in order to screen for neurocutaneous melanosis. For patients with asymptomatic neurocutaneous melanosis, repeat scans and individualized care is indicated (see Fig. 112.25). In the past, dermabrasion was sometimes performed, resulting in a more lightly pigmented and less elevated congenital nevus. More recently, especially in Europe, repeat curettage performed during the first few weeks of life (when there is a cleavage plane in the upper dermis) has led to similar results. Scarring and prolonged healing in the case of large lesions are the drawbacks. Lasers (e.g. Q-switched ruby, Q-switched alexandrite) have also been used to treat congenital nevi, but recurrence of pigmentation is an issue as is persistence of nevus cells85. As mentioned previously, when melanoma supervenes in a large congenital nevus, it may involve the dermal or subcutaneous component and be difficult to detect early. Cutaneous melanoma arising in the smaller types of congenital melanocytic nevi usually begins in the epidermis and can be detected more readily.

NEVUS SPILUS Synonyms:  ■ Speckled lentiginous nevus ■ Zosteriform lentiginous

nevus

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Key features ■ Tan patch with superimposed “speckles” that develop over time ■ The darker macules and papules vary from lentigines to junctional and compound nevi to Spitz and blue nevi ■ Occasionally, atypical nevi and small and medium-sized congenital nevi are seen within a larger nevus spilus ■ There is a small risk of cutaneous melanoma

Epidemiology There is some controversy as to whether nevus spilus is congenital or acquired and this is explained in part by the initial appearance of a nevus spilus – a uniformly tan-colored, CALM-like patch that can be subtle clinically. There are several lines of evidence to suggest that nevus spilus is a type of congenital melanocytic nevus86. In one series, a nevus spilus was noted in ~2% of white adults. There is no gender predilection.

Pathogenesis A nevus spilus often has an oval shape, but it may have a block-like configuration or follow the lines of Blaschko (see Ch. 62); nevi in the latter patterns are sometimes referred to as zosteriform speckled lentiginous nevi and their configuration suggests a molecular event during embryogenesis. This type of nevus is thought to represent a localized “field defect” and has been likened to a garden of melanocytes in which any type of nevus can develop, simultaneously or sequentially86. Recently, activating mutations in HRAS were detected in all eight cases of nevus spilus that were examined87.

Clinical Features These lesions most commonly affect the trunk and extremities. The tan macular area typically ranges from 1 to 4 cm in diameter (Fig. 112.27A,B), but it may measure >20 cm and involve an entire extremity or half the trunk (Fig. 112.27C)86. Although the darker speckles are usually macules or papules that are 1–6 mm in diameter, larger lesions that resemble small and medium-sized congenital nevi are occasionally seen (Fig. 112.27D).

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Fig. 112.27 Nevus spilus (speckled lentiginous nevus) – range of presentations and comparison to agminated nevi. A,B A few versus numerous medium to dark brown macules and papules superimposed upon a tan patch. C Larger lesion of the lateral trunk with dark brown to black nevi of varying sizes; sometimes the tan background is subtle and not initially recognized. D The “speckles” can be larger and resemble small and medium-sized congenital nevi. The larger lesions were present at birth while the smaller nevi have appeared over time. E Agminated melanocytic nevi – grouped brown macules and papules in the absence of background hyperpigmentation (see also Fig. 112.16). B–E, Courtesy, Jean L Bolognia, MD.  

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Pathology The tan macule or patch of nevus spilus is characterized by lentiginous melanocytic hyperplasia associated with elongated epidermal rete ridges. The hyperpigmented macular foci are also characterized by lentiginous melanocytic hyperplasia or junctional nevi, whereas the papular foci represent compound, dermal, blue, Spitz, and/or atypical nevi. Histologic features associated with congenital melanocytic nevi can also be seen.

Differential Diagnosis Agminated nevi (junctional, compound > Spitz, blue) and partial unilateral lentiginosis represent the major entities in the differential diagnosis (Fig. 112.27E). However, neither has an associated tan patch as a background, and agminated nevi have less variation in the types of nevi present. Sometimes Wood’s lamp examination is required to make the distinction.

Treatment Because of reports of cutaneous melanoma developing within a nevus spilus, it seems advisable that patients be followed on a periodic basis (photography may be helpful). Individual pigmented lesions with atypical features or suspicious change should be evaluated histologically.

HALO NEVUS Synonyms:  ■ Leukoderma acquisitum centrifugum ■ Sutton’s nevus ■

Perinevoid vitiligo

Key features ■ White halo around a nevus ■ Most common on the trunk in teenagers with an increased number of nevi ■ Lymphocytes infiltrate the nevus

Epidemiology Halo nevi generally affect individuals under the age of 20 years. Although the mean age is ~15 years, these nevi have been noted to appear from the first to the fifth decade of life89. The overall incidence of halo nevi in individuals under age 20 is probably 6 months).

Treatment Establishing that a previous surgical procedure has occurred is integral to the diagnosis. Review of the previous biopsy specimen is mandatory if any atypicality is noted histologically. Clinical features that point to the need for a repeat biopsy are outlined above and histopathologic findings guide the need for further re-excision. For table on assessment of atypical Spitz tumors in children and adolescents for risk for metastasis plus online figures visit www .expertconsult .com

REFERENCES

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1. Bataille V, Snieder H, MacGregor AJ, Spector T. Genetics of risk factors for melanoma: an adult twin study of nevi and freckles. J Natl Cancer Inst 2000;92:457–63. 2. Bliss JM, Ford D, Swerdlow AJ, et al. Risk of cutaneous melanoma associated with pigmentation characteristics and freckling: systematic overview of 10 case-control studies. Int J Cancer 1995;62:367–76. 3. Rhodes AR, Albert LS, Barnhill RL, Weinstock MA. Sun-induced freckles in children and young adults: a correlation of clinical and histopathologic features. Cancer 1991;67:1990–2001. 4. Breathnach AS. Melanocyte distribution in forearm epidermis of freckled human subjects. J Invest Dermatol 1957;29:253–61. 5. Bastiaens M, ter Huurne J, Gruis N, et al. The melanocortin-1-receptor gene is the major freckle gene. Hum Mol Genet 2001;10:1701–8. 6. Landau M, Krafchik BR. The diagnostic value of café-au-lait macules. J Am Acad Dermatol 1999;40:877–90. 7. Korf BR. Diagnostic outcome in children with multiple café au lait spots. Pediatrics 1992;90:924–7. 8. Rieger E, Kofler R, Borkenstein M, et al. Melanotic macules following Blaschko’s lines in McCune-Albright syndrome. Br J Dermatol 1994;130:215–20. 9. Jimbow K, Szabo G, Fitzpatrick TB. Ultrastructure of giant pigment granules (macromelanosomes) in the cutaneous pigmented macules of neurofibromatosis. J Invest Dermatol 1973;61:300–9. 10. Carpo GB, Grevelink JM, Grevelink SV. Laser treatment of pigmented lesions in children. Semin Cutan Med Surg 1999;18:233–43. 11. Cohen PR. Becker’s nevus. Am Fam Physician 1988;37:221–6. 12. Danari R, Konig A, Salhi A, et al. Becker’s nevus syndrome revisited. J Am Acad Dermatol 2004;51:965–9. 12a.  Cai ED, Sun BK, Chiang A, et al. Postzygotic mutations in beta-actin are associated with Becker’s nevus and Becker’s nevus syndrome. J Invest Dermatol 2017;137:1795–8. 13. Glinick SE, Alper JC, Bogaars H, Brown JA. Becker’s melanosis: associated abnormalities. J Am Acad Dermatol 1983;9:509–14. 14. Tse Y, Levine VJ, McClain SA, Ashinoff R. The removal of cutaneous pigmented lesions with the Q-switched ruby laser and the Q-switched Nd: YAG laser: a comparative study. J Dermatol Surg Oncol 1994;20:795–800. 14a.  Haugh AM, Merkel EA, Zhang B, et al. A clinical, histologic, and follow-up study of genital melanosis in men and women. J Am Acad Dermatol 2017;76:836–40. 15. Barnhill RL, Albert LS, Shama SK, et al. Genital lentiginosis: a clinical and histopathologic study. J Am Acad Dermatol 1990;22:453–6.

16. Cordova A. The Mongolian spot. Clin Pediatr 1981;20:714–19. 17. Gilchrest BA, Fitzpatrick TB, Anderson RR, Parrish JA. Localization of melanin pigmentation in the skin with Wood’s lamp. Br J Dermatol 1977;96:245–8. 18. Hidano A, Kajima H, Ikeda S, et al. Natural history of nevus of Ota. Arch Dermatol 1967;95:187–95. 19. Van Raamsdonk CD, Griewank KG, Crosby MB, et al. Mutations in GNA11 in uveal melanoma. N Engl J Med 2010;363:2191–9. 20. Teekhasaenee C, Ritch R, Rutnin U, Leelawongs N. Ocular findings in oculodermal melanocytosis. Arch Ophthalmol 1990;108:1114–20. 21. Gerami P, Pouryazdanparast P, Venmula S, Bastian BC. Molecular analysis of a case of nevus of Ota showing progressive evolution to a melanoma with intermediate stages resembling cellular blue nevus. Am J Dermatopathol 2010;32:301–5. 22. Tse JY, Walls BE, Pomerantz H, et al. Melanoma arising in a nevus of Ito: novel genetic mutations and a review of the literature on cutaneous malignant transformation of dermal melanocytosis. J Cutan Pathol 2016;43:57–63. 23. Chan HH, Leung RS, Ying SY, et al. A retrospective analysis of complications in the treatment of nevus of Ota with the Q-switched alexandrite and Q-switched Nd: YAG lasers. Dermatol Surg 2000;26:1000–6. 24. Dorsey CS, Montgomery H. Blue nevus and its distinction from Mongolian spot and the nevus of Ota. J Invest Dermatol 1954;22:225–36. 25. Rodriguez HA, Ackerman LV. Cellular blue nevus. Clinicopathologic study of forty-five cases. Cancer 1968;21:393–405. 26. Carney JA, Ferreiro JA. The epithelioid blue nevus: a multicentric familial tumor with important associations, including cardiac myxoma and psammomatous melanotic schwannoma. Am J Surg Pathol 1996;20:259–72. 27. Zembowicz A, Carney JA, Mihm MC. Pigmented epithelioid melanocytoma: a low-grade melanocytic tumor with metastatic potential indistinguishable from animal-type melanoma and epithelioid blue nevus. Am J Surg Pathol 2004;28:31–40. 28. Zembowicz A, Knoepp SM, Bei T, et al. Loss of expression of protein kinase A regulatory subunit 1 alpha in pigmented epithelioid melanocytoma but not in melanoma or other melanocytic lesions. Am J Surg Pathol 2007;31:1764–75. 29. Goldenhersh MA, Savin RC, Barnhill RL, Stenn KS. Malignant blue nevus. J Am Acad Dermatol 1988;19:712–22. 30. Barnhill RL, Argenyi Z, Berwick M, et al. Atypical cellular blue nevi (cellular blue nevi with atypical features): lack of consensus for diagnosis and distinction from cellular

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blue nevi and malignant melanoma (“malignant blue nevus. Am J Surg Pathol 2008;32:36–44. Whiteman DC, Pavan WJ, Bastian BC. The melanomas: a synthesis of epidemiological, clinical, histopathological, genetic, and biological aspects, supporting distinct subtypes, causal pathways, and cells of origin. Pigment Cell Melanoma Res 2011;24:879–97. Zhu G, Duffy DL, Eldridge A, et al. A major quantitativetrait locus for mole density is linked to the familial melanoma gene CDKN2A: a maximum-likelihood combined linkage and association analysis in twins and their sibs. Am J Hum Genet 1999;65:483–92. Elder DE. Dysplastic naevi: an update. Histopathology 2010;56:112–20. Lanschuetzer CM, Laimer M, Nischler E, Hintner H. Epidermolysis bullosa nevi. Dermatol Clin 2010;28:179–83. Carlson JA, Mu XC, Slominski A, et al. Melanocytic proliferations associated with lichen sclerosus. Arch Dermatol 2002;138:77–87. Clark WH Jr, Hood AF, Tucker MA, Jampel RM. Atypical melanocytic nevi of the genital type with a discussion of reciprocal parenchymal-stromal interactions in the biology of neoplasia. Hum Pathol 1998;29:S1–24. Rongioletti F, Ball RA, Marcus R, Barnhill RL. Histopathological features of flexural melanocytic   nevi: a study of 40 cases. J Cutan Pathol 2000;27:  215–17. Gleason BC, Hirsch MS, Nucci MR, et al. Atypical genital nevi. A clinicopathologic analysis of 56 cases. Am J Surg Pathol 2008;32:51–7. Grin CM, Saida T. Pigmented nevi of the palms and soles. In: Marghoob AA, Braun B, Kopf AW, editors. Atlas of Dermoscopy. London: Taylor & Francis; 2005. p. 271–9. Boyd AS, Rapini RP. Acral melanocytic neoplasms: a histologic analysis of 158 lesions. J Am Acad Dermatol 1994;31:740–5. Weedon D, Little J. Spindle and epithelioid cell nevi in children and adults. A review of 211 cases of the Spitz nevus. Cancer 1977;40:217–25. Barr R, Morales R, Graham J. Desmoplastic nevus. A distinct histologic variant of mixed spindle and epithelioid cell nevus. Cancer 1980;46:557–64. Dawe RS, Wainwright NJ, Evans AT, Lowe JG. Multiple widespread eruptive Spitz naevi. Br J Dermatol 1998;138:872–4. Ludgate MW, Fullen DR, Lee J, et al. The atypical Spitz tumor of uncertain biologic potential. a series of 67 patients from a single institution. Cancer 2009;115:631–41. Spatz A, Calonje E, Handfield-Jones S, Barnhill RL. Spitz tumors in children: a grading system for risk stratification. Arch Dermatol 1999;135:282–9.

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eFig. 112.1 Solar lentigo – histopathologic features. Hyperpigmented elongated rete ridges as well as solar elastosis. Courtesy, Lorenzo Cerroni, MD.  

eFig. 112.4 Nevus of Ota – ocular involvement. Blue discoloration of the sclera. Courtesy, Jean L Bolognia, MD.  

eFig. 112.2 Café-noir lesion in a patient with Carney complex. When compared to uninvolved skin, café-noir lesions are a darker shade than CALMs.  

Courtesy, Jean L Bolognia, MD.

eFig. 112.5 Acral melanocytic nevus – histopathologic features. Proliferation of nevoid and epithelioid melanocytes within the epidermis and superficial dermis. Note the single melanocytes and small complexes of melanocytes within the upper layers of the epidermis. Courtesy, Lorenzo Cerroni, MD.  

eFig. 112.6 Spitz nevus. Red dome-shaped papule on the ear of a child. Courtesy, Ronald P  

Rapini, MD.

eFig. 112.3 Labial melanotic macule (lentigo) – histopathologic features. Hyperpigmented rete ridges are broader than in a typical lentigo. Basilar hyperpigmentation and melanophages are seen. Courtesy, Lorenzo Cerroni, MD.  

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eFig. 112.7 Spitz nevus. Pink symmetric papule in a child. Courtesy, Julie V Schaffer,  

MD.

eFig. 112.8 Epithelioid cell nevus/tumor associated with BAP1 loss – histopathologic features. There is a dermal proliferation of epithelioid melanocytes. The two insets show details of cellular morphology and of loss of BAP1 expression (note normal nuclear staining of keratinocytes within the epidermis). Courtesy, Lorenzo Cerroni, MD.  

FOLLOW-UP SCHEDULE AND PHOTOGRAPHY FOR CLINICALLY ATYPICAL MELANOCYTIC NEVI Patient with clinically atypical melanocytic nevi +

− Family history

Few atypical nevi

• Follow-up interval: 6–12 months • Baseline photos of atypical nevi

Numerous atypical nevi  personal history of melanoma • Follow-up interval: 3–6 months • Total body photos* • Photos of most atypical nevi

Few atypical nevi

• Follow-up interval: 12 months • Baseline photos of atypical nevi

Personal history of melanoma; few atypical nevi • Follow-up interval: 6 months • Baseline photos of most atypical nevi

Numerous atypical nevi

• Follow-up interval: 6 months • Total body photos* • Photos of most atypical nevi

eFig. 112.9 Follow-up schedule and photography for clinically atypical melanocytic nevi. *Advocated by some authors, but not standard of care.  

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eFig. 112.10 Small congenital melanocytic nevus. Note the hypertrichosis and slight heterogeneity in pigmentation, reflecting its hamartomatous nature.  

Courtesy, Lorenzo Cerroni, MD.

eFig. 112.11 Atypical melanocytic nevi with dermoscopic patterns often associated with melanoma. From top to bottom, schematic, normal illumination, and dermoscopy. Courtesy, the AAD dermoscopy group.  

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margin status of dysplastic nevi. Arch Dermatol 2012;148:259–60. Reddy KK, Farber MJ, Bhawan J, et al. Atyptical (dysplastic) nevi outcomes of surgical excision and association with melanoma. JAMA Dermatol 2013;149:928–34. Strazzula L, Vedak P, Hoang MP, et al. The utility of re-excising mildly and moderately dysplastic nevi: A retrospective analysis. J Am Acad Dermatol 2014;71:1071–6. Piepkorn MW, Barnhill RL, Elder DE, et al. The MPATH-Dx reporting schema for melanocytic proliferations   and melanoma. J Am Acad Dermatol 2014;70:  131–41. Lott JP, Elmore JG, Zhao GA, et al. International Melanoma Pathology Study Group. Evaluation of the Melanocytic Pathology Assessment Tool and Hierarchy for Diagnosis (MPATH-Dx) classification scheme for diagnosis of cutaneous melanocytic neoplasms: Results from the International Melanoma Pathology Study Group. J Am Acad Dermatol 2016;75:356–63. Swerdlow AJ, English JSC, Qiao Z. The risk of melanoma in patients with congenital nevi: a cohort study. J Am Acad Dermatol 1995;32:595–9. Barnhill RL, Fleischli M. Pathology of congenital melanocytic nevi in infants less than a year of age. J Am Acad Dermatol 1995;33:780–5. Sahin S, Levin L, Kopf AW, et al. Risk of melanoma in medium-sized congenital melanocytic nevi: a follow-up study. J Am Acad Dermatol 1998;39:428–33. Marghoob AA, Schoenbach SP, Kopf AW, et al. Large congenital melanocytic nevi and the risk for the development of malignant melanoma. A prospective study. Arch Dermatol 1996;132:170–5. DeDavid M, Orlow SJ, Provost N, et al. A study of large congenital melanocytic nevi and associated malignant melanomas: review of cases in the New York University Registry and the world literature. J Am Acad Dermatol 1997;36:409–15. Dawson HA, Atherton DJ, Mayou B. A prospective study of congenital melanocytic naevi: progress report and evaluation after 6 years. Br J Dermatol 1996;134:617–23. DeDavid M, Seth JO, Provost N, et al. Neurocutaneous melanosis: clinical features of large congenital melanocytic nevi in patients with manifest central nervous system melanosis. J Am Acad Dermatol 1996;35:529–38. Kadonaga JN, Frieden IJ. Neurocutaneous melanosis: definition and review of the literature. J Am Acad Dermatol 1991;24:747–55. Agero ALC, Benvenuto-Andrade C, Dusza SW, et al. Asymptomatic neurocutaneous melanocytosis in patients with large congenital melanocytic nevi: a study of cases from an Internet-based registry. J Am Acad Dermatol 2005;53:959–65. Lovett A, Maari C, Decarie JC, et al. Large congenital melanocytic nevi and neurocutaneous melanocytosis: one pediatric center’s experience. J Am Acad Dermatol 2009;61:766–74. Bett BJ. Large or multiple congenital melanocytic nevi: occurrence of cutaneous melanoma in 1008 persons. J Am Acad Dermatol 2005;52:793–7. Krengel S, Scope A, Dusza SW, et al. New recommendations for the categorization of cutaneous features of congenital melanocytic nevi. J Am Acad Dermatol 2013;68:441–51.

81. Bauer J, Curtin JA, Pinkel D, Bastian BC. Congenital melanocytic nevi frequently harbor NRAS mutations but no BRAF mutations. J Invest Dermatol 2007;127:179–82. 82. Ramaswamy V, Delaney H, Haque S, et al. Spectrum of central nervous system abnormalities in neurocutaneous melanocytosis. Dev Med Child Neurol 2012;54:563–8. 83. Krengel S, Hauschild A, Schäfer T. Melanoma risk in congenital melanocytic naevi: a systematic review. Br J Dermatol 2006;155:1–8. 84. Egan CL, Oliveria S, Elenitsas R, et al. Cutaneous melanoma risk and phenotypic changes in large congenital nevi: A follow-up study of 46 patients. J Am Acad Dermatol 1998;39:923–32. 85. Kishi K, Okabe K, Ninomiya R, et al. Early serial Q-switched ruby laser therapy for medium-sized to giant congenital melanocytic naevi. Br J Dermatol 2009;161:345–52. 86. Schaffer JV, Orlow SJ, Lazova R, Bolognia JL. Speckled lentiginous nevus: within the spectrum of congenital melanocytic nevi. Arch Dermatol 2001;137:172–8. 87. Sarin KY, McNIff JM, Kwok S, et al. Activating HRAS mutation in nevus spilus. J Invest Dermatol 2014;134:1766–8. 88. Abecassis S, Spatz A, Cazeneuve C, et al. Melanoma within naevus spilus: 5 cases. Ann Dermatol Venerol 2006;133:323–8. 89. Wayte DM, Helwig EB. Halo nevi. Cancer 1968;22:69–90. 90. Kolm I, Di Stefani A, Hofmann-Wellenhof R, et al. Dermoscopy patterns of halo nevi. Arch Dermatol 2006;142:1627–32. 91. Fletcher V, Sagebiel RW. The combined nevus: mixed patterns of benign melanocytic lesions must be differentiated from malignant melanomas. In: Ackerman AB, editor. Pathology of Malignant Melanoma. New York: Masson; 1981. p. 273–83. 92. Rogers GS, Advani H, Ackerman AB. A combined variant of Spitz’s nevi. How to differentiate them from malignant melanomas. Am J Dermatopathol 1985;7:61–78. 93. Pulitzer DR, Martin PC, Cohen AP, Reed RJ. Histologic classification of the combined nevus. Analysis of the variable expression of melanocytic nevi. Am J Surg Pathol 1991;15:1111–22. 94. Scolyer RA, Zhuang L, Palmer AA, et al. Combined naevus: a benign lesion frequently misdiagnosed both clinically and pathologically as melanoma. Pathology 2004;36:419–27. 95. Barnhill RL, Cerroni L, Cook M, et al. State of the art, nomenclature, and points of consensus and controversy concerning benign melanocytic lesions: outcome of an international workshop. Adv Anat Pathol 2010;17:73–90. 96. Park HK, Leonard DD, Arrington JH 3rd, Lund HZ. Recurrent melanocytic nevi: clinical and histologic review of 175 cases. J Am Acad Dermatol 1987;17:285–92. 97. Blum A, Hofmann-Wellenhof R, Marghoob AA, et al. Recurrent melanocytic nevi and melanomas in dermoscopy: results of a multicenter study of the International Dermoscopy Society. JAMA Dermatol 2014;150:138–45. 98. Marghoob AA, Orlow SJ, Kopf AW. Syndromes associated with melanocytic nevi. J Am Acad Dermatol 1993;29:373–88.

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46. Bastian BC, Wesselmann U, Pinkel D, Leboit PE. Molecular cytogenetic analysis of Spitz tumors shows clear differences to melanoma. J Invest Dermatol 1999;113:1065–9. 47. Raskin L, Ludgate M, Iyer RK, et al. Copy number variations and clinical outcome in atypical spitz tumors. Am J Surg Pathol 2011;35:243–52. 48. Wiesner T, Obernauf AC, Murali R, et al. Germline muations in BAP1 predispose to melanocytic tumors. Nature Genet 2011;43:1018–21. 49. Wiesner T, Murali R, Fried I, et al. A distinct subset of Atypical Spitz Tumors is characterized by BRAF mutation and loss of BAP1 expression. Am J Surg Pathol 2012;36:818–30. 50. Barnhill RL, Mihm MC Jr. The pigmented spindle cell naevus and its variants: distinction from melanoma. Br J Dermatol 1989;121:717–25. 51. Barnhill RL, Mihm MC Jr, Magro CM. Plexiform pigmented spindle cell naevus: a distinctive variant of plexiform melanocytic naevus. Histopathology 1991;18:243–7. 52. Hung T, Yang A, Mihm MC, Barnhill RL. The plexiform spindle cell nevus nevi and atypical variants: report of 128 cases. Hum Pathol 2014;45:2369–78. 53. Hung T, Yang A, Mihm MC, Barnhill RL. The plexiform spindle cell nevus nevi and atypical variants: report of 128 cases. Hum Pathol 2014;45:2369–78. 54. Roush GC, Nordlund JJ, Forget B, et al. Independence of dysplastic nevi from total nevi in determining risk for nonfamilial melanoma. Prev Med 1988;17:273–9. 55. Nordlund JJ, Kirkwood J, Forget BM, et al. Demographic study of clinically atypical (dysplastic) nevi in patients with melanoma and comparison subjects. Cancer Res 1985;45:1855–61. 56. MacKie RM, Freudenberger T, Aitchison TC. Personal risk-factor chart for cutaneous melanoma. Lancet 1989;2:487–90. 57. Holly EA, Kelly JW, Shpall SN, Chiu SH. Number of melanocytic nevi as a major risk factor for malignant melanoma. J Am Acad Dermatol 1987;17:459–68. 58. Halpern AC, Guerry D 4th, Elder DE, et al. Dysplastic nevi as risk markers of sporadic (nonfamilial) melanoma. A case-control study. Arch Dermatol 1991;127:995–9. 59. Garbe C, Buttner P, Weiss J, et al. Risk factors for developing cutaneous melanoma and criteria for identifying persons at risk: multicenter case-control study of the central malignant melanoma registry of the German Dermatological Society. J Invest Dermatol 1994;102:695–9. 60. Garbe C, Buttner P, Weiss J, et al. Associated factors in the prevalence of more than 50 common melanocytic nevi, atypical melanocytic nevi, and actinic lentigines: multicenter case-control study of the central malignant melanoma registry of the German Dermatological Society. J Invest Dermatol 1994;102:700–5. 61. Tucker MA, Halpern A, Holly EA, et al. Clinically recognized dysplastic nevi. A central risk factor for cutaneous melanoma. JAMA 1997;277:1439–44. 62. Hoffman-Wellenhof R, Blum A, Wolf IH, et al. Dermoscopic classification of atypical melanocytic nevi. Arch Dermatol 1992;137:1575–80. 63. Shors AR, Kim S, White E, et al. Dysplastic naevi with moderate to severe histological dysplasia: a risk factor for melanoma. Br J Dermatol 2006;155:988–93. 64. Duffy KL, Mann DJ, Petronic-Rosic V, Shea CR. Clinical decision making based on histopathologic grading and

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Fig. P1 Solar lentigines. Sharply demarcated, uniform, tan macules on sun-exposed skin. Dermoscopically, moth-eaten borders, fingerprinting, and a reticular pattern with thin lines, short and interrupted.

Fig. P2 Junctional nevus. Clinically, a brown macule with central hyperpigmentation. Dermoscopically, a uniform pigment network.

Fig. P3 Dermal nevus. A light tan, soft, raised papule. Dermoscopically, focal globular-like structures, whitish structureless areas, and fine comma vessels.

Fig. P4 Melanocytic nevus of acral skin. A brown macule on the sole of the foot. Dermoscopically, a lattice-like



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Fig. P5 Clinically atypical melanocytic nevus. The dermoscopy pattern is reticular–disorganized and can be seen with uncertain lesions.

Fig. P6 Medium-sized congenital nevus. Dermoscopically, a globular pattern with hyphae-like structures.

Fig. P7 Halo nevus. A depigmented macular halo surrounding a central dark brown papule. Dermoscopically, a symmetric white structureless area surrounding the remaining network of the nevus.

Fig. P8 Recurrent melanocytic nevus. A brown papule with areas of scarring. Dermoscopically, asymmetric pigmentation within the confines of the









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Fig. P9 Atypical melanocytic nevi with dermoscopic patterns commonly seen in benign melanocytic nevi. Courtesy, the AAD dermoscopy group.  

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NEOPLASMS OF THE SKIN SECTION 18

Melanoma Claus Garbe and Jürgen Bauer

Chapter Contents Molecular pathogenesis . . . . . . . . . . . . . . . . . . . . . . . . . . 1989 Host immune response to melanoma . . . . . . . . . . . . . . . . . 1991 Epidemiology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1991 Risk factors for cutaneous melanoma . . . . . . . . . . . . . . . . . 1992 Types of primary melanomas . . . . . . . . . . . . . . . . . . . . . . 1995 Other melanoma variants . . . . . . . . . . . . . . . . . . . . . . . . . 1997 Melanoma and pregnancy . . . . . . . . . . . . . . . . . . . . . . . . 1998 Childhood melanoma . . . . . . . . . . . . . . . . . . . . . . . . . . . 2000 Diagnosis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2000 Histopathology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2002 Staging . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2007 Prognosis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2008 Evaluation of a patient with suspected melanoma . . . . . . . . . 2009 Management . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2010 Melanoma surveillance . . . . . . . . . . . . . . . . . . . . . . . . . . 2016

Key features ■ Melanoma represents a malignant tumor that arises from melanocytes, and, due to its metastatic potential, leads to >90% of skin cancer deaths ■ The incidence rates of melanoma have increased over the past four decades by five- to seven-fold, whereas mortality rates began to stabilize in the early 1990s ■ In situ and early invasive cutaneous melanoma can be subtle in appearance but dermoscopy has led to an improvement in diagnostic accuracy ■ Early-stage melanomas are often curable by surgical excision ■ For metastatic melanoma, oral therapies that target mutant signaling pathways (e.g. BRAF and MEK inhibitors) and immunotherapies that act as checkpoint inhibitors (e.g. antiCTLA-4, -PD-1, and -PD-L1 antibodies) represent breakthrough treatments

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MOLECULAR PATHOGENESIS Cancer usually develops through a stepwise evolutionary process, with tumor progression involving both genetic instability and selective growth of cells with advantageous mutations. Additional contributing factors include genetic predisposition, mutagenic environmental events, and antitumor host response. There are also several hallmarks of cancer, including self-sufficiency with regard to growth signals, insensitivity to antigrowth signals, evasion of apoptosis, limitless replicative potential, sustained angiogenesis, and tissue invasion and metastasis. As depicted in Figs 107.2 and 107.3, this set of properties can be acquired by the activation of oncogenes or the inactivation of tumor suppressor genes via molecular mechanisms such as point mutations, deletions, and translocations as well as epigenetic mechanisms such as microRNA expression and promoter methylation. Genome-wide analysis of genetic aberrations has revolutionized our understanding of the complex interplay of signaling pathways3,4. In melanoma, initiating oncogenic events frequently affect genes involved in the mitogen-activated protein kinase (MAPK) and phosphoinositide 3-kinase (PI3K) signaling pathways such as BRAF, NRAS, and KIT (Figs 113.1 & 113.2). While these alterations may initially result in senescence, secondary genetic alterations, including amplification of CCND1 which encodes cyclin D1, deletion or mutation of CDKN2A which encodes both p16 and p14ARF, and/or mutation of TP53 which encodes p53, result in progression into a malignant tumor5. Early on in tumorigenesis, genetic instability predominates (e.g. via telomere attrition), but with time melanomas regain telomerase expression and as a result acquire unlimited replicative potential6. Nowadays, melanomas can be classified based upon molecular findings5,7, providing a rationale for targeted therapy (see below). As depicted in Fig. 113.1, melanomas from different body sites and from locations with different amounts of ultraviolet radiation (UVR) damage also differ with regard to frequencies of mutated oncogenes. For example, when melanomas arise within intermittently sun-exposed skin that does not have chronic sun-induced damage histologically, they are more likely to have BRAF mutations; these melanomas also carry a lower mutation burden and contain less UV-signature mutations. In comparison, melanomas from chronically sun-exposed skin are less likely to have BRAF mutations and contain a higher overall mutation burden as well as a higher percentage of UV-signature mutations8. These findings may be explained in part by direct induction of pyrimidine dimers by UVB in the latter group versus indirect mutagenesis by UVA and formation of free radicals in intermittently sun-exposed skin5. Patterns of changes in DNA copy number also vary in different body sites.

Cellular Signaling Pathways in Melanoma INTRODUCTION Melanoma is a malignant tumor that arises from melanocytes and is most commonly cutaneous in origin. It can also arise on mucosal surfaces (e.g. oral, conjunctival, vaginal) and within the uveal tract of the eye as well as the leptomeninges. Rising incidence rates of cutaneous melanoma have been observed worldwide over the past four decades in white populations1. While mortality rates increased slightly in the US and Europe during the 1970s and 1980s, a stabilization of mortality rates was observed in a number of countries during the 1990s, due primarily to the early detection of thinner cutaneous melanomas. Melanoma is also one of the most common forms of cancer in young adults2. It therefore represents a significant public health problem, especially with respect to years of life lost.

Genetic aberrations in melanoma frequently affect signaling pathways that play an essential role in normal melanocyte biology. As noted previously, discovery of specific sites of dysfunction within these pathways has led to the era of targeted therapies, e.g. the use of vemurafenib in patients with a somatic mutation in BRAF that leads to substitution of glutamic acid (E) for valine (V) at codon 600 (i.e. V600E) and subsequent activation of the mitogen-activated protein kinase (MAPK) pathway.

MAPK signaling The MAPK pathway regulates cellular proliferation, growth, and migration. Via this pathway, interactions between growth factors (mitogens) and receptor tyrosine kinases (RTKs) such as the KIT receptor on the cell surface eventually lead to changes in the activity of transcription factors and gene expression within the nucleus (see Fig. 113.2). Upon

1989

Melanoma is a malignant tumor that arises from melanocytes and is most commonly cutaneous in origin. However, it can also arise on mucosal surfaces or within the eye and leptomeninges. Due to its metastatic potential, melanoma leads to more than 90% of skin cancerrelated deaths. The incidence rates of melanoma have increased over the past four decades by five- to seven-fold, whereas mortality rates began to stabilize in the early 1990s, due primarily to the early detection of thinner cutaneous melanomas. In situ and early invasive cutaneous melanoma can be subtle in appearance but dermoscopy has led to an improvement in diagnostic accuracy. Early-stage melanomas are often curable by surgical excision. Sentinel node biopsy provides additional prognostic information and those with resected stage III disease can be offered adjuvant immunotherapy. For metastatic melanoma, oral therapies that target mutant signaling pathways (e.g. BRAF and MEK inhibitors) and immunotherapies that act as checkpoint inhibitors (e.g. anti-CTLA-4, -PD-1, and -PD-L1 antibodies) represent breakthrough treatments.

melanoma, cutaneous melanoma, melanoma risk factors, BRAF mutation, BRAF V600E, MAP kinase pathway, MAPK pathway, immune checkpoint inhibitors, melanoma targeted therapy, BRAF inhibitors, MEK inhibitors, melanoma and pregnancy, childhood melanoma, melanoma surveillance, sentinel lymph node biopsy, ipilimumab

CHAPTER

113 Melanoma

ABSTRACT

non-print metadata KEYWORDS:

1989.e1

SECTION

Neoplasms of The Skin

18

ligand binding, RTKs dimerize and become activated by autophosphorylation of intracellular tyrosine residues. The phosphorylation of tyrosine residues creates binding sites for adaptor proteins (e.g. GRB2, SOS) and initiates a signaling cascade that requires the GTPase activity of NRAS and the kinase activity of BRAF, MEK, and ERK. Phosphorylated ERK activates nuclear cyclin D1 and a complex between cyclin D1 and cyclin-dependent kinases 4 and 6 (CDK4/6) is formed that phosphorylates retinoblastoma tumor suppressor protein (Rb), resulting in release

GENETIC ABERRATIONS IN MUCOCUTANEOUS MELANOMAS

Aberrant (%)

100

KIT KIT and NRAS KIT and BRAF NRAS BRAF

PI3K signaling

50

0

Non-CSD

CSD

Acral

of E2F from the Rb–E2F complex. E2F represents a family of transcription factors that play an important role in the regulation of cell cycle progression (see Fig. 107.1). An important tumor suppressor is p16, encoded by CDKN2A. By binding to CDK4/6, p16 prevents the formation of the cyclin D1–CDK4/6 complex and as a result prevents Rb activation and E2F release. The key role of the MAPK pathway in melanoma is highlighted by the high frequency of mutations in the genes that encode its components, in particular BRAF and NRAS. With regard to RTKs, 30% to 40% of acral and mucosal melanomas as well as melanomas from chronically sun-exposed skin harbor activating mutations or copy number amplifications of KIT9. In addition, constitutively activating mutations are present in NRAS (15–20% of melanomas overall)7 and BRAF (50– 60%)10 (see Fig. 113.1). Of note, MAPK pathway activation in melanoma can also be induced by inherited mutations in CDKN2A which underlie familial melanoma11, as well as by acquired inactivating mutations and deletions of CDKN2A.

Mucosal

Fig. 113.1 Genetic aberrations in mucocutaneous melanomas. Of melanomas with somatic mutations in BRAF, at least 80% lead to substitution of glutamic acid (E) for valine (V) at codon 600, i.e. V600E. CSD, skin with chronic suninduced damage such as marked solar elastosis; non-CSD, skin without chronic sun-induced damage. From Curtin JA, Busam K, Pinkel D, Bastian BC. J Clin Oncol. 2006;24:4340–6.  

Phosphoinositide 3-kinases (PI3Ks) are enzymes that regulate cell growth, proliferation, differentiation, motility, and survival (see Fig. 113.2). PI3Ks are activated by RTKs and phosphorylate PIP2 (phosphatidylinositol 4,5-bisphosphate) to PIP3 (phosphatidylinositol 3,4,5-triphosphate). PIP3 then acts as a second messenger and AKT is activated via phosphorylation. It is important to note that by converting PIP3 back to PIP2, AKT activation can be inhibited by PTEN12. Activated phospho-AKT inhibits apoptosis by phosphorylating BAD which leads to its loss of pro-apoptotic function, enhances survival by increasing the transcription of survival genes, and accelerates cell growth via mTOR (see Fig. 113.2). PI3K signaling is activated in a high percentage of melanomas by multiple mechanisms. Frequent activating events include inactivation of the gene that encodes the inhibitor PTEN via mutations, deletions or promoter methylation13, activating mutations of NRAS7, and overexpression of AKT13. However, direct activation of the PI3K pathway by activating mutations in the genes that encode PI3K subunits occurs infrequently14.

Fig. 113.2 RAS–RAF–MEK–ERK (MAPK) and PI3K–AKT signaling pathways. The mitogenactivated protein kinase (MAPK) pathway (orange color), also referred to as the MAP kinase pathway, is physiologically activated by growth factor binding to receptor tyrosine kinases. The stimulus is relayed to the nucleus via the GTPase activity of NRAS and the kinase activity of BRAF, MEK, and ERK. Within the nucleus, this results in increased transcription of genes involved in cell growth, proliferation, and migration. The central role of this pathway in melanocytic neoplasia is highlighted by the fact that either NRAS or BRAF is mutated in ~80% of all cutaneous melanomas and melanocytic nevi. The PI3K–AKT pathway is another important regulator of cell survival, growth, and apoptosis (green color). A key inhibitor of this pathway is PTEN and inactivation of the gene that encodes PTEN via mutations, deletions, or promoter methylation also occurs in cutaneous melanomas. As a result, there is increased activity of the PI3K–AKT signaling pathway. Examples of farnesyltransferase inhibitors are tipifarnib and lonafarnib. BAD, BCL-2 associated agonist of cell death; CDK, cyclin-dependent kinase; E2F, transcription factor that controls transcription of cyclins; ERK, extracellular signal-regulated kinase; GDP, guanosine-5′-diphosphate; GRB2, growth factor receptor-bound protein 2, an adaptor protein that contains one Src homology 2 (SH2) domain and two SH3 domains; GTP, guanosine-5′-triphosphate; MEK, MAPK kinase; mTOR, mammalian target of rapamycin (aka sirolimus); p16, protein product of CDKN2A; PDK1, phosphoinositide-dependent kinase-1; PI3K, phosphoinositide 3-kinase; PIP2, phosphatidylinositol 4,5-bisphosphate; PIP3, phosphatidylinositol 3,4,5-  triphosphate; PTEN, phosphatase and tensin homolog; Rb, retinoblastoma protein; SOS, son of sevenless.  

RAS−RAF−MEK−ERK (MAPK) AND PI3K−AKT SIGNALING PATHWAYS Receptor tyrosine kinase (e.g. KIT)

Receptor tyrosine kinase (e.g. KIT)

Imatinib Dasatinib

Imatinib Dasatinib AKT PDK1

BAD Dabrafenib Encorafenib Vemurafenib

BRAF

MEK

PIP3

GRB2 SOS

NRAS GTP

NRAS GDP

GDP

GTP

Binimetinib Cobimetinib Trametinib

Idelalisib Alpelisib

PTEN

Palbociclib Rb mTOR Rb E2F

CDK4/6 E2F

cyclin D1 p16 see Fig. 107.1

1990

PIP2

Uprosertib Afuresertib

Farnesyltransferase inhibitors

cyclin D1

ERK

PI3K

Cell growth and proliferation

Sirolimus Temsirolimus Everolimus

As a group, WNT signaling proteins are involved in cellular processes such as differentiation, migration, proliferation, and stem cell maintenance (see Fig. 55.6). The role of WNT signaling in melanoma is complex, as WNT signaling is tightly regulated. In melanoma, mutations that stabilize β-catenin and increase intracellular β-catenin have been described. However, β-catenin and APC mutations are rare events in melanoma15,16. The controversial role of β-catenin signaling in melanoma is highlighted by the observation that gene silencing of β-catenin in melanoma cells slows their growth but promotes the formation of pulmonary metastases in mice17. In sum, WNT signaling can promote tumor growth by activating proliferation and cell migration, but it can also inhibit tumor growth by inducing cell differentiation and acting as a tumor suppressor18.

MC1R–MITF signaling The melanocortin 1 receptor (MC1R) is a G-protein-coupled receptor that is activated by melanocortins (ACTH, α-MSH; see Table 65.4). MC1R is one of the key receptors involved in regulating skin and hair color19. When bound to its ligands, MC1R activates adenylate cyclase and cAMP is formed as a second messenger (see Fig. 65.4). cAMP activates protein kinase A (PKA) and PKA activates the cAMP responseelement binding protein (CREB); the latter is a transcription factor that enhances expression of microphthalmia-associated transcription factor (MITF)20. MITF is also a transcription factor and it regulates expression of a number of melanocyte lineage-specific genes that encode enzymes of the melanin biosynthetic pathway (e.g. tyrosinase, tyrosinase-related proteins) as well as other genes such as CDK2, CDKN2A, and BCL2. MITF signaling is also tightly linked and regulated by MAPK and WNT signaling (see Fig. 65.4)21. MCIR variants have been associated with a red hair/fair skin phenotype, and independent of phenotype, have been found to be a risk factor for the development of cutaneous melanoma (see Fig. 65.14)22. In addition, MITF has been shown to be an oncogene amplified in melanoma23. However, MITF can also act as an antiproliferative transcription factor by inducing cell cycle arrest. Interestingly, mutant oncogenic BRAF can regulate MITF expression to ensure that its protein levels are compatible with proliferation and survival of melanoma cells24. Better understanding of the molecular mechanisms of melanoma development will hopefully translate into improvements in melanoma risk assessment, prevention, diagnosis, and molecularly targeted therapies.

HOST IMMUNE RESPONSE TO MELANOMA Clinical observations such as incomplete or complete regression of melanoma (Fig. 113.3), associated development of vitiligo-like depigmentation and halo nevi, and a higher incidence of melanoma in

Fig. 113.3 Cutaneous melanoma with regression. An asymmetric, irregularly pigmented melanocytic lesion. The central depigmented zone is due to tumor regression and histopathologically, fibrosis can be  

immunosuppressed patients point to the fact that melanoma is an immunogenic tumor. Numerous melanoma antigens recognized by autologous T cells or antibodies have been described including: (1) mutant tumor antigens (e.g. mutant p16 [CDKN2A]); (2) shared tumorspecific antigens of the cancer/testis family (e.g. MAGE-1, MAGE-3, NY-ESO-1); and (3) cell type-specific differentiation antigens (e.g. tyrosinase, PMEL17/gp100, MART-1/Melan-A). These proteins are processed and presented on the melanoma cell surface as MHC/peptide complexes. CD8+ cytotoxic T cells recognize these antigens and, if appropriately activated, are able to kill tumor cells. In addition to CD8+ T cells, CD4+ helper T cells as well as antibodies also play a critical role. Activation of melanoma-specific CD8+ T cells is dependent on the migration of tumor antigen-loaded dendritic cells to a draining lymph node. Here, melanoma antigens are presented to CD8+ T cells in the presence of a costimulatory signal provided by the binding of B7 on the antigen-presenting cell to CD28 on the T cell (see Ch. 4). Cytotoxic T lymphocyte-associated antigen-4 (CTLA-4) is an inhibitory homolog of CD28 that is upregulated following T-cell activation and acts as natural inhibitor of T-cell activation by removing the costimulatory signal. Programmed cell death protein 1 (PD-1) is another immuno-inhibitory receptor in the CD28 family (Fig. 128.9). The interaction of PD-1 with its ligands PD-L1 and PD-L2 promotes apoptosis of tumor antigenspecific T cells and reduces apoptosis in regulatory T cells. Recently, immunotherapy based upon CTLA-4, PD-1, and PD-L1 blockade has been introduced for the treatment of melanoma (see below). A variety of immune escape mechanisms may be found in advanced tumors, including melanoma. These include loss of tumor-specific antigens, loss of MHC class I molecules, and secretion of immunoinhibitory cytokines such as interleukin (IL)-10 and TGF-β. Downregulation of a melanoma-specific immune response might also involve naturally occurring CD4+/CD25+ regulatory T cells, inducible IL-10producing regulatory T cells, negative signals delivered via cell surface CTLA-4, or aberrant expression of PD-L125. Insights into mechanisms of melanoma-specific host immune responses and immune escape have led to improved immunotherapy in the form of checkpoint inhibitors and hopefully will lead to other more effective therapies, including vaccines.

CHAPTER

113 Melanoma

WNT signaling

EPIDEMIOLOGY Over the past several decades, the incidence rates of cutaneous melanoma have increased significantly (Fig. 113.4A). It develops primarily in Caucasian populations, with its incidence remaining very low amongst darkly pigmented populations of African, Asian, and Hispanic origin26. The annual increase in melanoma incidence varies depending upon the population, but in general it has been estimated to be between 3% and 7%. These estimates predict a doubling of rates every 10–20 years, making cutaneous melanoma the most rapidly increasing cancer in white populations. For example, in the state of Connecticut, over a period of six decades (1950 to 2007), the overall incidence rate rose greater than 17-fold in men (1.9 to 33.5 per 100 000) and more than nine-fold in women (2.6 to 25.3 per 100 000)27. Cohort studies from several countries indicate that the trend of increasing incidence rates will continue for at least the next two decades. Based upon data from the Surveillance Epidemiology and End Results (SEER) database, an estimated 76 380 men and women in the US were expected to be diagnosed with melanoma in 2016 and an estimated 10 130 were expected to die from melanoma that same year (seer.cancer. gov). In Europe, the highest incidence rates have been noted in Scandinavian countries, with the lowest incidence rates observed in Mediterranean countries. One explanation for this North–South gradient is a darker skin phototype (types III–IV) in Mediterranean populations. Worldwide, the highest incidence rates have been reported in Australia and New Zealand, with 39 (women) to 60 (men) cases per 100 000 inhabitants per year in Australia in 2016. Within Australia, the highest incidence rates have been found in northern equatorial regions such as Queensland28. Mortality rates from melanoma increased throughout the 1980s in most European countries, as well as in North America (Fig. 113.4B), Australia and New Zealand, then peaked in the early 1990s. Subsequently, trends have been less uniform, with mortality rates still rising

1991

SECTION

Genetic factors

40

Family history of cutaneous melanoma Lightly pigmented skin • Tendency to burn, inability to tan • Red hair color • DNA repair defects (e.g. xeroderma pigmentosum) •

White male White female

30



20

Environmental factors •

10

2020

2015

2010

2005

2000

1995

1990

1985

Year 6

Mortality rate per 100 000

1980

1975

A

5

Phenotypic expressions of gene/environment interactions Melanocytic nevi and solar lentigines: - Increased total number of acquired melanocytic nevi (MN) >100 MN, relative risk ~ 8–10-fold increased - Atypical melanocytic nevi (AMN) > 5 AMN, relative risk ~ 4–6-fold increased - Multiple solar lentigines (SL) Multiple SL, relative risk ~3–4-fold increased Relative risks (RR) are multiplicative: e.g. a person with >100 MN + >5 AMN + multiple SL has a relative risk ~ 10 × 5 × 3 = 150-fold • Personal history of cutaneous melanoma •

White male White female Black male Black female

4 3 2

Table 113.1 Risk factors for the development of cutaneous melanoma.  

1

2020

2015

2010

2005

2000

1995

1990

1985

1980

1975

0

B

Intense intermittent sun exposure Chronic sun exposure • Residence in equatorial latitudes • PUVA (possible) • Tanning bed use, especially under the age of 35 years • Iatrogenic or acquired immunosuppression •

0

Year

Fig. 113.4 Incidence rates and mortality rates for melanoma in the US per 100 000 inhabitants (1975–2010, projected to 2020). A,B While the incidence has increased significantly in white men and women over the past four decades, there has been a modest increase in mortality in white men. Data from  

www.cdc.gov/cancer/dcpc/research/articles/cancer_2020_incidence.htm or figures.htm.

in several European countries among middle-aged adults, but with more favorable trends in women and some stabilization in young adults; rates have remained relatively constant among men29. Vertical tumor thickness (Breslow depth) is the most important local prognostic factor in primary cutaneous melanoma. One explanation for the progressive reduction in mean tumor thickness that has occurred over the past several decades is more effective detection of melanoma at an earlier stage30,31. In Germany, there has been a trend towards diagnosing thinner melanomas since the 1980s, with the median tumor thickness decreasing from 1.81 mm (1980s) to 0.53 mm (2000). The percentages of in situ and Clark level II melanomas also increased30. Diagnosis of thinner tumors should translate into stable or decreasing mortality rates, despite the increase in incidence rates. The tumor thickness at the time of primary diagnosis is also agedependent32. In general, there are significantly fewer melanomas ≤1.0 mm in older age groups. As a corollary, the percentage of thick melanomas increases significantly with age and reaches 20% by age 80 years in both genders33.

RISK FACTORS FOR CUTANEOUS MELANOMA

1992

RISK FACTORS FOR THE DEVELOPMENT OF CUTANEOUS MELANOMA

INCIDENCE RATES AND MORTALITY RATES FOR MELANOMA IN THE US PER 100 000 INHABITANTS (1975–2010, PROJECTED TO 2020)

Incidence rate per 100 000

Neoplasms of The Skin

18

Recognition of risk factors for the development of melanoma is important from a public health and a clinical care perspective (Table 113.1). Identification of high-risk cohorts improves the efficiency and efficacy of public health efforts. Individual risk assessment influences clinical decision-making including the threshold for performing a biopsy, prevention counseling, and surveillance. Risk factors may be divided into three categories: (1) genetic factors; (2) phenotypic manifestations of gene–environment interactions; and (3) environmental factors.

Genetic Risk Factors Germline genetic mutations and polymorphisms can predispose individuals to melanoma. The genes involved range from the rare highpenetrance genes responsible for some familial clustering of melanoma to the very common pigmentation genes responsible for the relative propensity for fair-skinned individuals to develop melanoma34. The major high-penetrance susceptibility gene locus associated with familial melanoma is CDKN2A. Approximately 2% of cutaneous melanomas can be specifically attributed to pathogenic germline mutations in CDKN2A35. This locus encodes two distinct protein products, p16 and p14ARF, with the latter via an alternative reading frame, hence the designation ARF. p16 and p14ARF exert regulatory effects on cell cycle progression through the retinoblastoma protein (Rb) and p53 pathways, respectively (see Fig. 107.1)36,37. Germline CDKN2A mutations are observed in ~20% of familial melanoma kindreds (Fig. 113.5). The penetrance of CDKN2A mutations is modified by germline variants of other genes, including MC1R. In some families, carriers of germline CDKN2A mutations are also at increased risk of developing pancreatic cancer38. While assays for these CDKN2A mutations have been commercialized and have been advocated by some in the field, it is the recommendation of the International Melanoma Genetics Consortium that at present genetic testing for CDKN2A mutations be done only as part of research protocols39. However, other experts have suggested that individuals with three or more primary invasive melanomas or families with at least one invasive melanoma and two or more other diagnoses of invasive melanoma or pancreatic cancer among first- or seconddegree relatives (on the same side of the family) were appropriate candidates for referral for genetic consultation and possible testing35. Fig. 113.5 depicts the less common genes that when mutated can also lead to familial melanoma (e.g. CDK4, BAP1). It also emphasizes the high percentage of families for whom the genetic basis is unknown, a point that should be discussed with patients contemplating genetic screening40. Among pigmentation genes associated with an increased risk for developing melanoma, specific germline variants of the melanocortin 1 receptor (MC1R) gene have been found to correlate with melanoma risk above and beyond clinically apparent skin phenotype41. A strong association between MC1R as a susceptibility gene and the risk of developing BRAF-mutant melanomas has also been observed. While the risk of developing any cutaneous melanoma lies between 1.5-fold and

2% 0.

%

IP

25

F2 R

D

0.

TE

AC

XC TE 0.0 R 4% T PO 0.0 T1 4% 0. 5%

C

C

BA

D

P1

K4

1.

0.

0%

7%

FAMILIAL MELANOMA − SUSCEPTIBILITY GENES

113

The strongest independent risk factors for the development of cutaneous melanoma are those that reflect a combination of genetic susceptibility and environmental exposure: melanocytic nevi, atypical melanocytic nevi, ephelides, and solar lentigines. Both an increased number of common melanocytic nevi and the presence of atypical melanocytic nevi are independent risk factors for melanoma, as is the presence of solar lentigines. Acquired melanocytic nevi play a dual role as a risk factor: (1) they are indicators of UV exposure and DNA damage; and (2) they can be formal precursors of melanoma. However, remnants of benign melanocytic nevi are found in only a minority of melanomas45,46. Based on epidemiologic data, the risk of malignant transformation in an individual melanocytic nevus has been estimated to be one melanoma in hundreds of atypical nevi and one in thousands of common nevi47,48. Consequently, prophylactic removal of clinically unsuspicious melanocytic nevi is not justified.

Common melanocytic nevi

Other 2.6%

CDKN2A 19.4%

CHAPTER

Phenotypic Risk Factors Reflecting Gene/ Environment Interactions

Melanoma

3-fold for individuals with MC1R variants, the risk of developing BRAFmutant melanomas was as high as 17-fold for those with two MC1R germline variants42,43. In addition to MC1R, single nucleotide polymorphisms in the tyrosinase (TYR) gene, the tyrosinase-related protein 1 (TYRP1) gene, and the SLC45A2 gene are significantly associated with melanoma risk (see Ch. 65)44.

MITF^ 1.0%

Unknown 77%

Fig. 113.5 Familial melanoma – susceptibility genes. Germline CDKN2A mutations are observed in ~20% of familial melanoma kindreds. Note the significant percentage of families for whom the genetic basis is unknown, a point that should be discussed with patients contemplating genetic screening. Patients with mutations in CDKN2A (p16), CDKN2A (p14), MITF, and POT1 can also develop pancreatic carcinoma, neural tumors, renal cell carcinoma, and gliomas, respectively, while those with BAP1 mutations can develop uveal melanoma, mesothelioma, renal cell carcinoma, cholangiocarcinoma, and basal cell carcinoma (at an early age). ACD*, adrenocortical dysplasia protein homolog; BAP1, BRCA1 associated protein 1; CDK4, cyclin-dependent kinase 4; CXC, CXC motif chemokine; MITF, microphthalmia-associated transcription factor; POT1*, protection of telomeres 1; TERF2IP*, telomeric repeat binding factor 2 interacting protein; TERT, telomerase reverse transcriptase (mutations in promoter). *Component of shelterin (see Fig. 67.22). ^Population attributable fraction. Adapted from Potrony M, Badenas C, Agulilaera P, et al. Update in genetic  

susceptibility in melanoma. Ann Transl Med. 2015;3:210.

Although performed on populations from different regions and with varying skin phototypes, studies have consistently reported a continuous and almost linear increase in melanoma risk with greater numbers of common melanocytic nevi (Fig. 113.6). Also, light-skinned populations have higher melanocytic nevus counts than do darker-skinned populations. For those with >50 common melanocytic nevi, the relative melanoma risk has ranged from 6.9 in southern Spain49 to 53.9 in Scotland50. Nonetheless, the dose-dependent relationship between number of common melanocytic nevi and risk of cutaneous melanoma holds true for all Caucasian populations. The association of increased nevus counts and melanoma risk is strongest for superficial spreading melanoma and nodular melanoma, in contrast to lentigo maligna melanoma which is highly correlated with skin type and hair color50,51. This suggests there are additional genetic susceptibility factors and molecular mechanisms involved in the formation of melanoma in chronically versus intermittently sunexposed skin (see Fig. 113.1). Melanoma at a particular anatomic site is more strongly related to the number of melanocytic nevi within that respective site than to the number of nevi in other body sites49,50, highlighting the key role of local mutagenic effects of UV radiation in addition to genetic susceptibility.

COMMON MELANOCYTIC NEVI AS MELANOMA RISK INDICATORS

18 Holly et al. 1987

Relative risk of developing melanoma

16

Grob et al. 1990

Garbe et al. 1994

Tucker et al. 1997

Bataille et al. 1994

Gandini et al. 2005

14 12 10 8 6 4 2

61−80

81−100

41−60

16−40

0−15

>100

50−99

0−24

101−120

Number of common melanocytic nevi (total body counts)

25−49

>100

50−99

25−49

5−9

10−24

0−4

>100

51−100

11−50

0−10

>120

41−80

81−120

21−40

11−20

0−10

>100

51−100

26−50

11−25

0−10

0

Fig. 113.6 Common melanocytic nevi as melanoma risk indicators. Relative risk of developing melanoma for a given number of common melanocytic nevi (total body counts) as determined by five epidemiologic studies and one meta-analysis (Gandini et al.). Melanoma risk increases almost linearly with the number of common melanocytic nevi, rendering common nevi valuable as risk indicators.  

1993

SECTION

Neoplasms of The Skin

18

Atypical melanocytic nevi 52

Since the original description of BK-mole syndrome in 1978 , several definitions of atypical melanocytic nevi as well as the atypical mole syndrome have been published. In general, a diagnosis of atypical melanocytic nevi is based upon the presence of at least three of the following criteria: (1) diameter ≥5 mm; (2) ill-defined borders; (3) an irregular margin; (4) varying shades within the lesion; and (5) the simultaneous presence of papular and macular components53. A relative risk of up to 500-fold for developing cutaneous melanoma has been described for specific subgroups of the atypical mole syndrome54. However, sporadic atypical melanocytic nevi are often diagnosed in “normal” individuals outside of the setting of the atypical mole syndrome. One possible explanation for the range of estimates of risk is the use of different definitions of clinically “atypical” melanocytic nevi by various investigators. Several studies have found clinically atypical nevi to be associated with increased melanoma risk outside of the context of familial melanoma (Fig. 113.7). The maximum reported relative risk for developing melanoma was as high as 32-fold when there were 10 or more atypical melanocytic nevi55. The consistency of these findings among multiple studies and across geographic locations supports the significance of atypical melanocytic nevi as an independent risk marker for sporadic melanoma. In contrast to the continuous increase in melanoma risk with greater numbers of common melanocytic nevi, for atypical melanocytic nevi a threshold level of five or more such lesions was associated with a clearly higher relative risk in several studies; however, there was no significant increase in the risk beyond this number53. This finding suggests that at least five atypical melanocytic nevi are needed to establish the diagnosis of atypical mole syndrome. In patients with familial melanoma, atypical melanocytic nevi are an indicator of a markedly elevated melanoma risk56,57.

Ephelides and solar lentigines Ephelides (freckles) have been reported to be a risk factor independent of numbers of common melanocytic nevi. The independence of freckling and common melanocytic nevi indicates that these cutaneous findings represent separate host characteristics, both of which are related to sun exposure58. Additional studies found that solar lentigines

were a risk factor for the development of cutaneous melanoma, independent of the number of common melanocytic nevi53.

Environmental Risk Factors Ultraviolet radiation It is widely believed that the total risk for developing melanoma is determined by the interplay between genetic factors and exposure to UVR. Approximately 80% of cutaneous melanomas develop in intermittently sun-exposed regions, and both intermittent sun exposure and sunburn history have been identified as risk factors in epidemiologic studies1,59. The role of sunlight in melanoma development has been a matter of debate for decades, in part because the etiologic role of sunlight is far less clear than in other tumors such as cutaneous squamous cell carcinoma (SCC)60,61. Also, melanoma is clearly a multi-factorial disease and forcing an all-or-none stance regarding sun exposure represents an erroneous oversimplification. That said, the following clinical and epidemiologic features have raised doubts regarding the impact of sunlight on melanoma development: With the exception of lentigo maligna melanoma, the anatomic distribution of melanoma does not closely match sites of greatest cumulative sun exposure as in cutaneous SCC. Melanoma most commonly develops in middle-aged adults, not the elderly with the greatest cumulative sun exposure. In most of the reported case–control studies, neither greater cumulative sun exposure during adulthood nor sunburns during the preceding years were associated with an elevation in melanoma risk. Initial indications of an etiologic role for sunlight came from the observation that melanoma incidence was increased in white populations living closest to the equator. This was most striking when melanoma incidence and mortality rates in Europe versus Australia were compared, with both variables being 5–10 times higher in Australia62. Furthermore, case–control studies demonstrated that melanoma risk was closely associated with the number of melanocytic nevi and with the occurrence of sunburns in childhood58,63,64. Interestingly, sunburns during childhood and adolescence significantly elevated the risk for melanoma development, but additional sunburns during adulthood did not contribute to any further risk elevation. This was in agreement

• • •

Holly et al. 1987

Grob et al. 1990

Garbe et al. 1994

Bataille et al. 1994

Tucker et al. 1997

Gandini et al. 2005

0

35

0

ATYPICAL MELANOCYTIC NEVI AS MELANOMA RISK INDICATORS

Relative risk of developing melanoma

30

25

20

15

10

5

5

4

3

2

1

5−9 >10

1

2−4

>4

1

2−3

0

≥5

0

1−4

>2

1

0

≥6

0

1−5

0

Number of atypical melanocytic nevi (total body counts)

Fig. 113.7 Atypical melanocytic nevi as melanoma risk indicators. Relative risk of developing melanoma for a given number of atypical melanocytic nevi (total body counts) as determined by five epidemiologic studies and one meta-analysis (Gandini et al.). An elevated risk is associated with relatively small numbers of atypical nevi. The relative risk as indicated by the number of atypical nevi is independent from the total number of melanocytic nevi, and it is related in a multiplicative fashion to the risk based on the total number of nevi. In other words, the individual risk for developing melanoma is calculated by multiplying the risk related to the total number of nevi times that due to the number of atypical nevi (see Table 113.1).  

1994

clothing, hats) and reducing UVR exposure (e.g. shade coverings, limiting outdoor activities between the hours of 10:00 AM and 4:00 PM).

TYPES OF PRIMARY MELANOMAS Until the 1960s, melanoma was regarded as a large black nodule that, as a rule, metastasized and caused death. Therefore, the recognition of early-stage melanoma has been a major advancement. Four major subtypes (growth patterns) of primary cutaneous melanoma have been described77 (Table 113.2). These different growth patterns characterize the early phase of development, but do not predict the prognosis.

CHAPTER

113 Melanoma

with previous findings that melanoma risk is mainly acquired during childhood. The total number of melanocytic nevi has been identified as the most important risk factor for cutaneous melanoma, and as the number of melanocytic nevi increases, the melanoma risk increases nearly linearly (see Fig. 113.6). Therefore, to gain more insight into the relationship between sun exposure and nevus development, epidemiologic studies have been performed in young children. With exposure to intense UVR, children in Australia developed melanocytic nevi early in life and in large numbers65; of note, duration of sun exposure was a stronger risk factor than the occurrence of sunburns. In a study of 1812 German nursery school children, high nevus counts in children were preferentially associated with the number of weeks on sunny holidays and with outdoor activities at home that were linked to moderate sun exposure66,67. These findings suggested that sunburns were not required and that moderate sun exposure appeared to be sufficient for the induction of melanocytic nevi in children. A possible explanation for the differences in the epidemiology of melanoma as compared with non-melanoma skin cancer involves apoptosis68. After exposure to UVR, the most severely damaged keratinocytes undergo apoptosis (sunburn cells), with the less damaged keratinocytes upregulating their DNA-repair capacities and undergoing nearly perfect DNA repair. As a result, the development of nonmelanoma skin cancer would favor elderly adults. In contrast, melanocytes do not undergo apoptosis as readily. Their function is to provide protective melanin to the surviving cells and so they are retained within the epidermis, even with damage. In addition, some UVR-induced mutations are thought to enable melanocytes to proliferate and give rise to junctional nevi. Subsequently, melanoma could arise in anatomic sites with intermittent sun exposure, with the sites of melanoma development reflecting the distribution pattern of melanocytic nevi69,70. This hypothesis might also explain why melanomas tend to develop in a younger age group (i.e. middle-aged adults). Both UVB and UVA radiation are thought to be associated with the development of cutaneous melanoma, with UVB believed to be the stronger risk factor. Data supporting UVB as a causative factor come from: (1) animal studies in which UVB was shown to induce melanoma in susceptible mice and in xenografted human skin engineered to express melanocytic growth factors71,72; and (2) the fact that there is a higher incidence of cutaneous melanoma in equatorial regions where UVB is most intense. Data implicating UVA in the development of cutaneous melanoma derive from: (1) animal studies in which UVA was shown to initiate melanoma (fish) and melanocytic hyperplasia (pigmented opossums)73,74; and (2) epidemiological studies showing an increased incidence of melanoma developing in users of tanning beds and perhaps recipients of PUVA. In 2009, the World Health Organization (WHO) International Agency for Research on Cancer (IARC) categorized tanning beds as a human carcinogen. Of note, exposure to tanning beds before the age of 35 years has a statistically significant association with melanoma development.

Superficial Spreading Melanoma Superficial spreading melanoma (SSM) is the most common type of cutaneous melanoma in fair-skinned individuals (Fig. 113.8) and it is diagnosed most frequently between the ages of 40 and 60 years. It accounts for ~60–70% of all melanomas and occurs at any site, but is most frequently seen on the trunk of men and the legs of women. It begins as an asymptomatic brown to black macule with color variations and irregular, notched borders (Fig. 113.9). SSM can arise de novo or in a pre-existing nevus (Fig. 113.10). When in situ, the melanoma is usually macular with an irregular outline and variable pigmentation (Fig. 113.11). SSMs may have a diameter ≤5 mm (Fig. 113.12). After a typically slow horizontal (radial) growth phase limited to the epidermis or focally within the papillary dermis, a more rapid vertically oriented growth phase, which presents clinically with the development of a papule or nodule, can then occur. In up to two-thirds of tumors, regression (visible as gray, hypo- or depigmentation) of part of the lesion is observed, reflecting the interaction of the host immune system with the progressing tumor. About half of SSMs arise in a pre-existing

DIFFERENT TYPES OF PRIMARY CUTANEOUS MELANOMA

Clinico-histopathologic subtype

Abbreviation

Percentage

Median age

Superficial spreading melanoma

SSM

57.4%

51 years

Nodular melanoma

NM

21.4%

56 years

Lentigo maligna melanoma

LMM

8.8%

68 years

Acral lentiginous melanoma

ALM

4%

63 years

Unclassifiable melanoma

UCM

3.5%

54 years

5%

54 years

Others

Table 113.2 Different types of primary cutaneous melanoma. Data from the  

German Central Malignant Melanoma Registry (N = 30 015).

Sun protection With regard to sun protection, there is a significant misunderstanding by the public that avoidance of sunburns and use of sunscreens is sufficient to prevent skin cancer. It is well established that suberythemal doses of UVR cause DNA mutations. Chronic irradiation with 10–20% of the minimal erythema dose of UVB induced DNA damage in mouse skin and this damage persisted in the dermis and epidermis for several weeks following discontinuation75. Therefore, low-dose UVB exposure in a repeated fashion could cause skin cancer. Regular use of sunscreen has been shown to decrease the development of actinic keratoses and cutaneous SCCs, but evidence regarding its ability to prevent cutaneous melanoma has been controversial to non-existent, until the past decade (see Ch. 132). In 2010, a randomized sunscreen trial in Australia found that the regular application of SPF 15+ sunscreen in 1621 adults over 5 years reduced the incidence of new primary cutaneous melanoma, even 10 years after completion of the trial. Whether or not the regular use of sunscreen in children, when sun exposure is thought to be critical for the development of cutaneous melanoma, will be beneficial is less clear76. There are additional sun-protective measures that should be encouraged, including physical means of blocking the sun (e.g. non-transparent

Fig. 113.8 Longstanding superficial spreading melanoma. Note asymmetry, irregular borders, variation in colors, scar-like regression zones, and an inferior pink papule, indicating vertical growth phase.  

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A

B

E

F

C

D

Fig. 113.9 Superficial spreading melanomas. Clinically, all of these lesions demonstrate asymmetry due to variation in color and irregularity in outline. Breslow depths for A, C, E were 30 genes. With one diagnostic panel that examined 23 genes, including those involved in tumor immunity, 90% sensitivity and 91% specificity were reported125. While identification of additional genes whose expression is discriminatory is anticipated, lesions with an intermediate genetic profile have been described126 such that achieving complete discrimination is unlikely. As with uveal melanomas (see above), GEP is now being applied to cutaneous melanomas in an attempt to predict risk of metastasis, dividing tumors into those that are low-risk (class 1) versus high-risk (class 2). In patients with a

STAGING Prior staging systems categorized melanoma into local, regional or distant disease, which strongly correlates with survival. The present tumor–node–metastases (TNM) staging system was introduced by the

American Joint Committee on Cancer (AJCC) in 2000, and then revised in 2009 and 2017 (Table 113.9)127,128. The two main factors that determine the T classification are: (1) Breslow depth; and (2) histopathologic evidence of ulceration. The N classification reflects the extent of tumor within the regional lymph node basin. The most important prognostic factors in the N classification are: (1) the number of metastatic lymph nodes; (2) whether the lymph node involvement is clinically occult versus clinically detectable; and (3) the presence or absence of satellite, in-transit, and microsatellite metastases. The M classification refers to metastatic disease and is based on two important features: (1) the anatomic site of the distant metastases; and (2) the serum lactate dehydrogenase (LDH) level.

CHAPTER

113 Melanoma

negative sentinel lymph node biopsy, GEP of the primary tumor may identify those still at risk for developing metastatic disease. Next generation sequencing has also been used to further characterize the genomic landscape of multiple tumors, including melanoma (see Ch. 3)126a. This method allows for the analysis of hundreds of genes in a single study and can potentially point to new therapeutic targets.

AJCC MELANOMA TNM CLASSIFICATION – 2017

Definition of primary tumor (T) T category

Thickness

Ulceration status

TX (primary tumor thickness cannot be assessed^)

NA

NA

T0 (no evidence of primary tumor^^)

NA

NA

Tis (melanoma in situ)

NA

NA

T1

≤1.0 mm

Unknown or unspecified

  T1a

1.0–2.0 mm

Without ulceration

  T2b

>1.0–2.0 mm

With ulceration

T3

>2.0–4.0 mm

Unknown or unspecified

  T3a

>2.0–4.0 mm

Without ulceration

  T3b

>2.0–4.0 mm

With ulceration

T4

>4.0 mm

Unknown or unspecified

  T4a

>4.0 mm

Without ulceration

  T4b

>4.0 mm

With ulceration

Definition of regional lymph node (N) Extent of regional lymph node and/or lymphatic metastasis N category

Presence of in-transit, satellite, and/or microsatellite metastases*

Number of tumor-involved regional lymph nodes

NX

Regional nodes not assessed^^^

No

N0

No regional metastases detected

No

N1

One tumor-involved node – or – in-transit, satellite, and/or microsatellite metastases with no tumor-involved nodes

  N1a

One clinically occult (i.e. detected by SLN biopsy)

No

  N1b

One clinically detected

No

  N1c

No regional lymph node disease

Yes

N2

Two or three tumor-involved nodes – or – in-transit, satellite, and/or microsatellite metastases with one tumor-involved node

  N2a

Two or three clinically occult (i.e. detected by SLN biopsy)

No

  N2b

Two or three, at least one of which was clinically detected

No

  N2c

One clinically occult or clinically detected

Yes

N3

Four or more tumor-involved nodes – or – in-transit, satellite, and/or microsatellite metastases with two or more tumor-involved nodes – or – any number of matted nodes without or with in-transit, satellite, and/or microsatellite metastases

  N3a

Four or more clinically occult (i.e. detected by SLN biopsy)

No

  N3b

Four or more, at least one of which was clinically detected, or presence of any number of matted nodes

No

  N3c

Two or more clinically occult or clinically detected and/or presence of any number of matted nodes

Yes

Table 113.9 AJCC melanoma TNM classification – 2017. Histologic evaluation of lymph nodes must include at least one immunohistochemical marker (e.g. HMB45, MART-1/Melan-A). NA, not applicable; SLN, sentinel lymph node. Adapted from: AJCC Cancer Staging Manual. American Joint Committee on Cancer, 8th edn. Springer, 2017:563–85.  

Continued

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AJCC MELANOMA TNM CLASSIFICATION – 2017

Definition of distant metastasis (M) M criteria Anatomic site

LDH level**

M0

No evidence of distant metastasis

NA

M1

Evidence of distant metastases

  M1a

Distant metastasis to skin, soft tissue including muscle, and/or nonregional lymph node

M category

   M1a(0)    M1a(1)

Not recorded or unspecified Not elevated Elevated

  M1b

Distant metastasis to lung with or without M1a sites of disease

Not recorded or unspecified

   M1b(0)

Not elevated

   M1b(1)

Elevated

  M1c

Distant metastasis to non-CNS visceral sites with or without M1a or M1b sites of disease

   M1c(0)    M1c(1)

Not recorded or unspecified Not elevated Elevated

  M1d

Distant metastasis to CNS with or without M1a, M1b or M1c sites of disease

   M1d(0)

Not recorded or unspecified Not elevated

   M1d(1)

Elevated ^For example, diagnosis by curettage. ^^For example, unknown primary or completely regressed melanoma. ^^^For example, SLN biopsy not performed or regional nodes previously removed for another reason; exception: pathological N category is not required for T1 melanomas, use cN. *In-transit metastases are >2 cm from the primary tumor but not beyond the regional lymph nodes, while satellite lesions are within 2 cm of the primary. Satellite lesions can be detected clinically or microscopically; the latter are referred to as microsatellite metastases. **Suffixes for M category: (0) LDH not elevated, (1) LDH elevated. No suffix is used if LDH is not recorded or is unspecified.

Table 113.9 AJCC melanoma TNM classification – 2017. (cont’d) LDH, lactic dehydrogenase.  

COMPARISON OF SURVIVAL CURVES IN FOUR STAGES OF MELANOMA

PROGNOSIS

1.0 0.9

Stage I

0.8

Survival rate

0.7 0.6 Stage II

0.5

Stage III

0.4 0.3 0.2

Stage IV

0.1 0 0

1

2

3

4

5

6 7 8 9 Survival (years)

10 11 12 13 14 20

Fig. 113.29 Comparison of survival curves in four stages of melanoma. Based upon 2009 AJCC melanoma TNM classification and prior to advent of targeted therapy or immunotherapy. Redrawn from Balch CM. Melanoma of the skin. In: Edge SB, Byrd DR,  



Compton CC, et al. (eds). AJCC Cancer Staging Manual, 7th edn. New York: Springer Verlag, 2009.

2008

nodal and/or intralymphatic metastases. Stage IV represents distant metastases.

When the T, N, M classifications are combined, placement into one of the four stages in the current AJCC staging system can be accomplished (Table 113.10) and then treatment can be determined and survival predicted (Fig. 113.29). Stage 0 represents melanoma in situ. Stages I and II represent localized disease, but a distinction is often made between low-risk stage IA patients (Breslow depth 1 mm with ulceration). Stage III represents regional

The prognosis of a patient with melanoma depends upon the stage at diagnosis. Prognosis for patients with localized primary cutaneous melanoma and no nodal or distant metastases (stage I or II) is generally favorable. Patients with stage IA melanoma have a 10-year survival expectancy of >95%, whereas patients with thick (>4 mm) melanoma and ulceration (T4b) have a 10-year survival rate of ~50%. In addition to the microstaging variables discussed above, clinical variables with prognostic significance in stage I/II disease include sex, age, and anatomic site129 (Table 113.11). For example, women with stage I/II disease tend to have a better survival rate than men. Location of the primary melanoma on the trunk, head or neck portends a poorer prognosis than when located on the extremities. Stage III melanoma patients are a heterogeneous group with respect to their risk for distant metastases and melanoma-specific mortality. The 5-year survival rates range from 70% for patients with nonulcerated melanomas and a single nodal micrometastasis (T1–4N1aM0), to a low of ~40% for patients with ulcerated primary melanomas plus four or more lymph nodes with metastases (at least one of which is clinically detectable; T1–4N3bM0). Major prognostic factors in this group are the number of metastatic lymph nodes and the tumor burden. Tumor burden is reflected by whether the nodal metastases are clinically occult (micrometastases, as detected by sentinel lymph node biopsy) or clinically palpable (macrometastases). In stage IV patients, the major prognostic factor is the site of distant metastases, with a poorer prognosis for visceral than for non-visceral (e.g. skin, subcutaneous, and distant lymph node) metastases. Prior to the advent of targeted and immunotherapies, the median survival time for stage IV patients was 9 months, and the estimated 5-year survival rate was 10% when the serum LDH level was abnormally elevated. Variables that influence survival are initial site of metastasis, disease-

CHAPTER

Survival (%)* 0 IA

97

Clinical staging†

Pathologic staging‡

T

N

M

T

N

M

Tis

N0

M0

Tis

N0

M0

T1a

N0

M0

Tla

N0

M0

T1b IB

93

T1b

MELANOMA – MAJOR INDEPENDENT PROGNOSTIC FACTORS FOR SURVIVAL IN MULTIVARIATE ANALYSES

Prognostic factor

Commentary

Tumor thickness

≤1 mm, low risk; >1 mm, higher risk

Ulceration

Worse prognosis with ulceration

Mitotic rate

Worse prognosis with ≥1 mitoses/mm2

Age

Worse prognosis with older age

Sex

Men have poorer prognosis (only for localized disease)

Anatomic site

Trunk, head and neck associated with poorer prognosis than extremities

N0

M0

T2a

N0

M0

N0

M0

T2b

N0

M0

N0

M0

Number of involved lymph nodes

Cut-off points: 1, 2–3, 4 or more lymph nodes (see Table 113.9)

T4b

N0

M0

Regional lymph node tumor burden

Clinically detectable (palpable) nodal metastases with poorer prognosis than clinically occult (microscopic) nodal metastases

IIIB

T0

N1b, N1c

M0

Site of distant metastases

IIIC

T0

N2b, N2c, N3b or N3c

M0

Visceral metastases associated with poorer prognosis than non-visceral metastases (skin, subcutaneous, distant lymph nodes)

T2a IIA IIB IIC

82

T2b

79

T3a

68

T3b

71

T4a

53

T4b

N0

M0

Any T, Tis

≥N1

M0

III§

T3a N0

M0

T3b T4a

IIIA

78

T1a/b–T2a

N1a or N2a

M0

IIIB

59

T1a/b–T2a

N1b/c or N2b

M0

T2b/T3a

N1a–N2b

T1a–T3a

N2c or N3a/b/c

T3b/T4a

Any N ≥ N1

T4b

N1a–N2c

IIIC

40

IIID IV

9–27¶

Any T

Any N

M1

113 Melanoma

AJCC STAGE GROUPINGS FOR CUTANEOUS MELANOMA – 2017

Table 113.11 Melanoma – major independent prognostic factors for survival in multivariate analyses.  

M0

T4b

N3a/b/c

M0

Any T, Tis

Any N

M1

*Approximate 5-year survival (%), adapted from Balch et al.127; based upon 2009 AJCC

melanoma TNM classification and prior to advent of targeted therapy or immunotherapy. †Clinical staging includes microstaging of the primary melanoma and clinical/radiologic evaluation for metastases. By convention, it should be used after complete excision of the primary melanoma with clinical assessment for regional and distant metastases. ‡Pathologic staging includes microstaging of the primary melanoma and pathologic information about the regional lymph nodes after partial or complete lymphadenectomy. Pathologic stage 0 or stage IA patients are the exception. §There are no stage III subgroups for clinical staging. ¶Higher survival rate associated with normal serum LDH levels and lower rate with elevated LDH levels.

Table 113.10 AJCC stage groupings for cutaneous melanoma – 2017. Adapted  

from AJCC Cancer Staging Manual. American Joint Committee on Cancer, 8th edn. Springer, 2017:563–85.

free interval before distant metastases, and stage of disease preceding distant metastases.

EVALUATION OF A PATIENT WITH SUSPECTED MELANOMA Medical History A thorough medical history should be taken, focusing especially on risk factors for the development of melanoma (see above), such as a personal or family history of melanoma, skin phototype I/II, extensive tanning bed use or PUVA treatment, childhood history of sunburns, genetic syndromes with skin cancer predisposition (e.g. xeroderma pigmentosum), and iatrogenic or acquired immunosuppression (e.g. solid organ transplant recipients, HIV infection). A detailed history of the specific lesion in question should be obtained. Was the lesion present at birth? Did the lesion develop in a pre-existing mole? Did it change in size or shape? Did it change in color or ulcerate? Was there itching or bleeding? What is the time course of change? Are there systemic symptoms such as weight loss, fatigue, headache or cough? Other family members

should be screened if either melanoma or atypical melanocytic nevi are present. All individuals at risk should be educated about the clinical features of melanoma and about sun protection measures.

Skin Investigation and Clinical Diagnosis A total body skin examination (TBSE) has to be performed. An estimation of the total number of melanocytic nevi and of the number of clinically atypical melanocytic nevi should be noted, as well as the presence of congenital nevi. Atypical pigmented lesions should be examined by dermoscopy. Any lesion suspected of being melanoma should undergo biopsy. Excisional biopsy with narrow 1–2 mm margins is the preferred method of biopsy, as it prevents sampling error (e.g. missing a focus of melanoma arising in a precursor benign lesion) and enables the pathologist to assess the overall architecture of the lesion and accurately microstage the tumor. Superficial shave biopsies should be avoided, but deeper saucerization biopsies may be used for flat lesions or if the clinical suspicion of cutaneous melanoma is not high. The specimen should be sent to an individual experienced in the diagnosis of melanocytic tumors. A second opinion is sometimes necessary for difficult cases. Clinical examination of lymph node basins should also be routinely performed.

Laboratory Investigations and Imaging The evidence-based clinical practice guidelines (2008) for the management of melanoma in Australia and New Zealand had the following recommendation: following the diagnosis of localized primary cutaneous melanoma (stages I, II), routine laboratory investigations and imaging (e.g. chest radiography) are not required for asymptomatic patients. Additional investigators noted that such tests have limited, if any, value in the initial evaluation of asymptomatic patients with primary cutaneous melanoma 4 mm or less in thickness130. An American Academy of Dermatology task force recommended that initial imaging studies and blood work should be optional and most appropriately directed based on findings of a thorough medical history and physical examination131. In a study involving more than 200 asymptomatic patients with localized melanomas initially examined with chest radiography, the true-positive radiograph rate for lung metastases was 0%, with a false-positive rate of 7%130. A simple and effective examination technique which was first introduced in Europe is lymph node ultrasound132. The scar of the primary

2009

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cutaneous melanoma, the lymphatic drainage areas, and the regional lymph node basin are examined by ultrasound with a 7.5–10 MHz probe. In one-third of patients, metastases can be detected before they become palpable with this technique. In some European countries, lymph node ultrasound is recommended for staging and follow-up of patients with melanomas >1 mm in thickness133. Serum markers for metastatic melanoma have been examined and the two most frequently employed markers are protein S100B and melanoma inhibitory activity (MIA). Comparative studies found a higher diagnostic sensitivity for protein S100B than for MIA134. A large US study found that for patients with surgically resected high-risk melanoma, a high baseline or increasing serum S100B level was an independent prognostic marker of risk for mortality135. Primarily in Europe, protein S100B is currently the most widely used serum marker for the detection of melanoma metastasis, both at the time of staging and in conjunction with surveillance examinations, in patients with elevated risk for recurrence133. Of note, detection of circulating melanoma cells in the blood by tyrosinase/MART-1 reverse transcription polymerase chain reaction (RT-PCR) was found by several investigators to have no predictive value. Investigation of stage III/IV melanoma patients may include radiologic investigations such as CT of the chest, abdomen and pelvis and CT or MRI of the brain as well as positron emission tomography (PET)CT (Table 113.12). For routine examinations and staging, CT remains the imaging technique of choice. Whereas CT is the most sensitive technique for the detection of lung metastases, intra-abdominal and soft tissue metastases are better detected by MRI, and the latter is often chosen for special clinical situations such as deciding on the operability of soft tissue metastases136. A significant advance in imaging for metastasis detection is PET scanning using 18F-fluorodeoxyglucose (FDG). It is based on the assumption that melanoma metastases have a higher metabolic rate than does normal tissue and utilize more glucose. PET is now being combined with CT technology and whole body PET-CT

SYMPTOMS AND DIAGNOSTIC TESTS FOR METASTATIC MELANOMA

Metastatic site (TNM)

Symptoms

Diagnostic tests*

Skin, soft tissue metastasis (TxNxM1a), in-transit metastasis (TxN1–3cM0)

Papules or nodules that vary in color from skin-toned to pink–red to blue, brown or black; secondary ulceration or bleeding

Histopathologic examination

Brain metastasis (TxNxM1d)

Headache, nausea, seizures, focal weakness, visual disturbance, paresthesias

MRI, CT or PET-CT

Lung metastasis (TxNxM1b)

Chest pain, dyspnea, cough, hemoptysis

Chest radiograph, CT or PET-CT

Gastrointestinal or liver metastasis (TxNxM1c)



Bone metastasis (TxNxM1c)

GI: abdominal pain, signs of anemia (e.g. fatigue, chest pain), vomiting, constipation, melena



CBC, CT or PET-CT; colonoscopy



Liver: abdominal pain, jaundice



Pain, spontaneous fractures

Bone scan or PET-CT

Liver function tests, LDH; CT, PET-CT or MRI

*Always include a thorough medical history and physical examination as well as complete blood count (CBC) and blood chemistry including lactate dehydrogenase (LDH). Special procedures such as detection of soluble melanoma markers (e.g. S100, melanoma inhibitory activity [MIA] protein) are performed at selected melanoma referral centers, especially in Europe.

Table 113.12 Symptoms and diagnostic tests for metastatic melanoma. CT, computed tomography; MRI, magnetic resonance imaging; PET, positron emission tomography.  

2010

is the most sensitive technique for the detection of melanoma metastasis137. As PET-CT is an expensive examination technique, it should not be used indiscriminately.

MANAGEMENT Management of the Primary Melanoma (Stage I and II) Following histologic diagnosis, the primary cutaneous melanoma site should be re-excised with an appropriate margin determined by the Breslow depth (Table 113.13). The rationale for excisional margins is based on the capacity of melanoma cells to migrate away from the tumor origin, i.e. melanoma may extend wider or deeper than is visibly apparent. The major goal is to prevent local recurrence or persistent disease. Excisional margins for primary cutaneous melanoma have changed remarkably over the past several decades. Until the 1980s, melanoma was often excised with a margin of 5 cm, independent of its tumor thickness. A WHO randomized trial demonstrated that 1 cm excisional margins were safe and effective for melanomas with a Breslow depth 1.5–2 cm in diameter) or treated by Mohs micrographic surgery or radiotherapy; postoperative topical imiquimod is often used

≤1 mm

1.0

1.01–2 mm

1.0–2.0

Mohs micrographic surgery may be considered for facial melanomas

>2 mm

2.0

Comments

Table 113.13 Surgical treatment of primary cutaneous melanoma. Evidence from available randomized trials is insufficient to address the optimal margins for the excision of primary cutaneous melanoma, but multiple expert international committees have produced fairly consistent guidelines, as summarized here. Of note, further investigative efforts will likely alter the standards of care over time. Adapted from Sladden MJ, et al. Surgical excision margins for  

primary cutaneous melanoma. Cochrane Database Syst Rev. 2009;(4):CD004855.

Local Recurrences Local recurrence is defined as any recurrence within 2 cm of the scar from the primary melanoma excision (Figs 113.30 & 113.31). Recurrence results from extension of the primary tumor or intralymphatic spread. The overall risk of local recurrence is ~4% and is increased in thicker or ulcerated tumors as well as melanomas located on the head and neck or distal lower extremity146. Local recurrence is strongly associated with the development of in-transit, regional, and distant metastases but it is not an independent prognostic indicator of survival in multivariate analysis146. There is evidence that patients with local recurrence, satellites, and in-transit metastases have similar

Fig. 113.30 Local recurrences of cutaneous melanoma. A Recurrent lentigo maligna along the upper lateral margin of the excision of the chin; inked lesion on the central upper lip is an actinic keratosis.   B Recurrent in situ acral lentiginous melanoma at the 10 o’clock position on the split-thickness skin graft. C Amelanotic nodular recurrence of a desmoplastic melanoma within the skin graft.  

A

Courtesy, Jean L Bolognia, MD.

outcomes147. There is no evidence that patient survival is adversely affected if local recurrence results from incomplete excision of the primary melanoma (i.e. persistent disease), provided that the residual tumor is in situ or in a radial growth phase, is promptly re-excised, and there is no distant disease at the time of re-excision148.

Management of Regional Metastatic Melanoma (Stage III)

CHAPTER

113 Melanoma

developed and followed for a median of 4.8 years, 16 (18%) relapsed; a greater number of lesional melanocytes was associated with an increased risk of local recurrence144. A recent systematic review found that at least 60 applications of imiquimod at a frequency of 6–7 times per week led to the greatest odds of complete clinical and histologic clearance145.

Metastatic spread of melanoma is primarily regional in about 70% of patients, i.e. confined to the site of the primary melanoma and its draining lymph nodes. For example, metastasis may manifest as a clinically occult lymph node micrometastasis, as a rapidly growing clinically evident lymph node macrometastasis, or as in-transit metastasis.

Elective lymph node dissection and sentinel lymph node biopsy Approximately 20% of patients with a cutaneous melanoma >1 mm in depth, plus no evidence (clinically or radiologically) of detectable nodal disease at presentation, will have microscopic lymph node involvement149. On the basis of a presumed migration of melanoma cells in an orderly fashion towards the draining lymph node, surgical resection of regional lymph nodes in all patients with intermediate- and high-risk tumors was previously recommended and was referred to as “elective lymph node dissection (ELND)”. However, four multicenter, randomized, prospective trials in patients with primary melanoma did not show a survival benefit for patients treated with ELND plus wide re-excision as compared to wide re-excision alone150–153. As a consequence, a less traumatic procedure to identify regional metastatic disease was introduced, called the sentinel lymph node biopsy (SLNB). SLNB is based on the finding that the cutaneous site of the melanoma drains to one or more lymph node basins and particularly to one (or two but rarely more) lymph node, the sentinel node, which is the first site of deposition of metastatic cells. The draining lymph node basins for a given melanoma site and the approximate location of the sentinel node within that basin are identified and marked on the overlying skin preoperatively during lymphoscintigraphy performed in the nuclear medicine department. Intraoperatively, typically in conjunction with the wide local excision, technetium sulfur colloid and blue dye are

B

A

B

C

D

Fig. 113.31 Local recurrences of cutaneous melanoma. A Recurrent lentigo maligna on the lower leg; note the depressed scar due to repeated excisions.   B By dermoscopy, an asymmetric pattern with multiple colors, ranging from light brown to dark blue-gray. C Recurrent acral lentiginous melanoma of the nail unit. The lentiginous types of melanoma have a propensity to recur.   D By dermoscopy, an asymmetric pattern with an atypical network inferiorly and multiple colors including blue-gray and gray-white.  

C

2011

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injected into the skin surrounding the melanoma biopsy site. A small incision is made at the previously marked site overlying the sentinel node and a hand-held gamma counter and visual inspection are used to identify the “hot, blue” sentinel node(s), which is selectively biopsied and examined by serial sectioning using H&E stains combined with immunohistochemistry (e.g. MART-1/Melan-A, HMB45, S100). If melanoma micrometastasis is identified, then a complete regional lymph node dissection has normally been recommended. However, the therapeutic benefit of complete lymphadenectomy following a positive sentinel node(s) has been questioned as often the remainder of the lymph nodes have no evidence of metastasis. In a large multicenter trial that compared complete lymphadenectomy versus observation with lymph node ultrasound examinations in patients with lymph node micrometastasis, the melanoma-specific survival at a mean of three years was similar153a. Nonsentinel-node metastases, identified in 11.5% of the patients in the dissection group, were a strong predictor of risk of recurrence, and lymphedema developed in 24.1% of patients in the dissection group and 6.3% of those in the observation group. Sentinel lymph node biopsy has become a standard procedure in the staging and prognostication of primary cutaneous melanoma ≥1 mm in thickness. Numerous publications have identified the status of the sentinel lymph node as a strong prognostic factor for survival and recurrence154,155, and the AJCC included it in their last two staging systems for cutaneous melanoma (see Tables 113.9 & 113.10)127. In 2006, the randomized Multicenter Selective Lymphadenectomy Trial (MSLT-1) confirmed the prognostic value of SLNB, and found improved disease-free survival for the SLNB group and improved survival for SLNB-positive patients who underwent complete lymphadenectomy as compared to patients in the control group who developed macroscopic nodal metastasis. However, there was no difference in overall survival when those who had a SLNB were compared to those who did not undergo SLNB, i.e. when the two study arms were compared156. More recent analysis of 10-year survival rates from this MSLT-1 trial largely confirmed the results of the initial analysis. For patients with intermediate-thickness melanomas and nodal metastases, biopsy-based management improved the 10-year rate of distant disease-free survival (HR = 0.62) and the 10-year rate of melanoma-specific survival (HR = 0.56)157. Thus, SLNB contributes to improvement of survival for a subset of melanoma patients with regional lymph node involvement. For those patients with a histologically negative but RT-PCR-positive SLN, there was no overall survival benefit from a complete lymphadenectomy158. There are basically four reasons to proceed with a SLNB in a person with a primary cutaneous melanoma >1 mm thick who has no clinically involved lymph nodes: (1) to obtain the most complete and accurate diagnostic and staging information possible for a patient who desires such data; (2) to obtain additional information regarding risk of recurrence by undergoing complete lymph node dissection if there is evidence of micrometastases; (3) to offer adjuvant therapy (e.g. ipilimumab); and (4) to gain entry into a clinical trial for new adjuvant therapies. Reasons not to proceed with SLNB include: (1) the patient is not interested in a possible complete lymphadenectomy or adjuvant therapy; and (2) he or she is content not knowing whether micrometastases exist.

Skin satellite and in-transit metastases

2012

Satellite and in-transit metastases are recurrences that generally occur in the lymphatic vessels more proximally relative to the primary cutaneous melanoma and toward the regional lymph nodes. Patients generally have a poorer prognosis with frequent development of distant metastasis. However, occasionally, despite the development of numerous in-transit metastases, the disease remains localized to a lower extremity for years. The goal of treatment is maintenance of local control. The treatment of choice for skin metastases is surgical, but systemic therapies should be considered if numerous or extensive lesions are not amenable to surgery. For multiple lesions on a limb, isolated limb perfusion with melphalan, with or without tumor necrosis factor (TNF), has palliative value159,160. In stage III patients with satellite/in-transit metastases, the procedure may be curative, as indicated by reported 5- and 10-year survival rates of 40% and 30%, respectively. Alternative

Fig. 113.32 Intralesional interleukin-2 (IL-2) treatment. A Multiple in-transit metastases were treated with intralesional low-dose IL-2 for 6 weeks. B Complete remission after 1 year, which persisted during the follow-up period of 7 years.  

A

B

options include cryotherapy, laser therapy, and experimental approaches such as intralesional/topical IL-2 (Fig. 113.32), electrochemotherapy, miltefosine, interferon-α, and imiquimod161.

Clinically identified lymph node metastases If lymph node metastasis is diagnosed clinically or by imaging techniques, complete lymph node dissection is considered standard therapy, which consists of an anatomically complete dissection of the involved nodal basin133,140. The extent of complete lymph node dissection is often modified according to the anatomic area of lymph node involvement, e.g. in the setting of inguinal lymphadenopathy, a deep groin dissection is recommended if the PET or pelvic CT scan reveals iliac and/or obturator lymphadenopathy. As more effective therapies become available, these recommendations may be revised.

Adjuvant therapy The goal of adjuvant therapy is the elimination of clinically unapparent micrometastases. The major target population for adjuvant therapy is patients with resected high-risk stage II or III melanoma. Some trials have also targeted resected stage IV patients. A number of postsurgical adjuvant approaches have been tested, including systemic chemotherapy and immunotherapy using microbial agents such as bacille Calmette–Guérin (BCG) or Corynebacterium parvum. None of these approaches were successful in randomized controlled trials. Patients may choose to enroll in clinical trials as currently only ipilimumab (for stage III) and IFN-α (for stage III and high-risk stage II) are approved for adjuvant treatment of melanoma. IFN-α is a type I member of the interferon family of proteins and has pleiotropic functions including induction of MHC class I expression, activation of natural killer (NK) cells, and the maturation of dendritic cells; some of its activities may have direct or indirect antitumor effects162. It is important to distinguish high-dose IFN-α therapy with the aim of reaching maximally tolerated dosage (20 MIU/m2 intravenously 5 days per week during the initiation phase, followed by 10 MIU/m2 subcutaneously three times per week) from low-dose IFN-α therapy which is much better tolerated in terms of side effects (typically 3 MIU subcutaneously three times per week). Pegylated IFN-α is also FDAapproved, which because of its prolonged half-life is given once weekly (Table 113.14). High-dose IFN-α has demonstrated an improvement in relapse-free and overall survival compared to controls in two studies (ECOG 1684 and ECOG 1694). However, a beneficial effect on overall survival was not seen in a third high-dose IFN-α study (ECOG 1690). Toxicities from high-dose IFN-α include constitutional (flu-like) symptoms and

Schedule

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Duration

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3 million IU sc

Days 1, 3 & 5 every week

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− Initiation

20 million IU/m2 IV rapid infusion

Days 1–5 every week

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Micrometastases in sentinel nodes and ulceration of the primary tumor were unequivocally associated with increased benefit in two large adjuvant IFN-α trials of the EORTC170,172. Therefore, patients fulfilling these specific criteria can be offered adjuvant IFN-α treatment. Ipilimumab, 10 mg/kg every 3 weeks for 4 doses then every 3 months for up to 3 years, is also approved as an adjuvant therapy for patients with stage III disease. In a randomized trial involving 951 patients, in which patients with in-transit or lymph node micrometastases (15 years), which is unpredictable but does occur; and (4) the increased risk of other cutaneous and noncutaneous malignancies. Most stage I/II cutaneous melanomas will present with locoregional recurrence, while stage III/IV patients most often present with systemic

metastases. The latter group is also typically followed by an oncologist. Recommendations for the frequency of dermatologic visits varies internationally and amongst practitioners. As 90% of all recurrences occur during the first 5 years following primary diagnosis (with the greatest risk in the first 2 years), most experts recommend dermatologic visits one to four times per year for 2 years after diagnosis (depending on risk factors and frequency of oncologic visits) and then every 6 to 12 months thereafter for life. The frequency is also influenced by the number of melanocytic nevi, common and atypical, and the number of primary cutaneous melanomas. Dermatologic visits should include: (1) updates on the medical history; (2) review of systems (e.g. any new or changing lesions; new “lumps or bumps”, weight loss, fatigue, headache or cough); (3) TBSE; (4) examination and palpation of the melanoma scar/excision site and surrounding area for local recurrences or in-transit metastases; (5) examination of lymph nodes; and (6) laboratory and radiologic tests as indicated by signs and symptoms. Patients should be counseled to adhere to sun-protective measures; perform skin self-examinations at home; and to take an oral vitamin D supplement. Family members should also be encouraged to undergo TBSEs. Although there has been an ongoing debate regarding the value of follow-up examinations206, a review of the literature on early detection and on resection of melanoma metastases demonstrates the following207: For in-transit metastases and regional lymph node metastases, the tumor volume of the metastatic nodules at the time of diagnosis has prognostic significance. Either the number of nodes involved or the diameter of the largest node has demonstrated prognostic importance. Therefore, early detection appears to affect the cure rate in stage III disease. With distant metastases, surgical resection of all recognizable metastases (if possible) prolongs survival. Therefore, early detection of melanoma metastases may contribute to prolongation of survival. In a prospective follow-up study of more than 2000 patients, recurrences were classified as diagnosed in either an early or a late phase of development, and patients diagnosed in an early phase had significantly more favorable odds of recurrence-free and overall survival than those in a late phase208,209. Lastly, doubts regarding early detection of metastases having a beneficial effect on patient survival arose in an era of minimally effective systemic therapies.

• •

For additional online figures visit www.expertconsult.com

REFERENCES

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1. Garbe C, Leiter U. Melanoma epidemiology and trends. Clin Dermatol 2009;27:3–9. 2. Siegel RL, Miller KD, Jemal A. Cancer statistics, 2017. CA Cancer J Clin 2017;67:7–30. 3. Pleasance ED, Cheetham RK, Stephens PJ, et al. A comprehensive catalogue of somatic mutations from a human cancer genome. Nature 2010;463:191–6. 4. Hodis E, Watson IR, Kryukov GV, et al. A landscape of driver mutations in melanoma. Cell 2012;150:251–63. 5. Bastian BC. The molecular pathology of melanoma: an integrated taxonomy of melanocytic neoplasia. Annu Rev Pathol 2014;9:239–71. 6. Horn S, Figl A, Rachakonda PS, et al. TERT promoter mutations in familial and sporadic melanoma. Science 2013;339:959–61. 7. Curtin JA, Fridlyand J, Kageshita T, et al. Distinct sets of genetic alterations in melanoma. N Engl J Med 2005;353:2135–47. 8. Krauthammer M, Kong Y, Ha BH, et al. Exome sequencing identifies recurrent somatic RAC1 mutations in melanoma. Nat Genet 2012;44:1006–14. 9. Curtin JA, Busam K, Pinkel D, Bastian BC. Somatic activation of KIT in distinct subtypes of melanoma. J Clin Oncol 2006;24:4340–6. 10. Davies H, Bignell GR, Cox C, et al. Mutations of the BRAF gene in human cancer. Nature 2002;417:949–54. 11. Meyle KD, Guldberg P. Genetic risk factors for melanoma. Hum Genet 2009;126:499–510. 12. Salmena L, Carracedo A, Pandolfi PP. Tenets of PTEN tumor suppression. Cell 2008;133:403–14.

13. Madhunapantula SV, Robertson GP. The PTEN-AKT3 signaling cascade as a therapeutic target in melanoma. Pigment Cell Melanoma Res 2009;22:400–19. 14. Curtin JA, Stark MS, Pinkel D, et al. PI3-kinase subunits are infrequent somatic targets in melanoma. J Invest Dermatol 2006;126:1660–3. 15. Worm J, Christensen C, Gronbaek K, et al. Genetic and epigenetic alterations of the APC gene in malignant melanoma. Oncogene 2004;23:5215–26. 16. Reifenberger J, Knobbe CB, Wolter M, et al. Molecular genetic analysis of malignant melanomas for aberrations of the WNT signaling pathway genes CTNNB1, APC, ICAT and BTRC. Int J Cancer 2002;100:549–56. 17. Takahashi Y, Nishikawa M, Suehara T, et al. Gene silencing of beta-catenin in melanoma cells retards their growth but promotes the formation of pulmonary metastasis in mice. Int J Cancer 2008;123:2315–20. 18. O’Connell MP, Weeraratna AT. Hear the Wnt Ror: how melanoma cells adjust to changes in Wnt. Pigment Cell Melanoma Res 2009;22:724–39. 19. Lin JY, Fisher DE. Melanocyte biology and skin pigmentation. Nature 2007;445:843–50. 20. Widlund HR, Fisher DE. Microphthalamia-associated transcription factor: a critical regulator of pigment cell development and survival. Oncogene 2003;22:3035–41. 21. Cheli Y, Ohanna M, Ballotti R, Bertolotto C. Fifteen-year quest for microphthalmia-associated transcription

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factor target genes. Pigment Cell Melanoma Res 2010;23:27–40. Valverde P, Healy E, Jackson I, et al. Variants of the melanocyte-stimulating hormone receptor gene are associated with red hair and fair skin in humans. Nat Genet 1995;11:328–30. Garraway LA, Widlund HR, Rubin MA, et al. Integrative genomic analyses identify MITF as a lineage survival oncogene amplified in malignant melanoma. Nature 2005;436:117–22. Wellbrock C, Rana S, Paterson H, et al. Oncogenic BRAF regulates melanoma proliferation through the lineage specific factor MITF. PLoSOne 2008;3:e2734. Antony PA, Restifo NP. CD4+CD25+ T regulatory cells, immunotherapy of cancer, and interleukin-2. J Immunother 2005;28:120–8. MacKie RM, Hauschild A, Eggermont AM. Epidemiology of invasive cutaneous melanoma. Ann Oncol 2009;20(Suppl. 6):vi1–7. Geller AC, Clapp RW, Sober AJ, et al. Melanoma epidemic: an analysis of six decades of data from the Connecticut Tumor Registry. J Clin Oncol 2013;31:4172–8. Whiteman DC, Bray CA, Siskind V, et al. Changes in the incidence of cutaneous melanoma in the west of Scotland and Queensland, Australia: hope for health promotion? Eur J Cancer Prev 2008;17:243–50. Bosetti C, La Vecchia C, Naldi L, et al. Mortality from cutaneous malignant melanoma in Europe. Has the epidemic levelled off? Melanoma Res 2004;14:301–9.

eFig. 113.2 Early superficial spreading melanomas. All of these lesions demonstrate asymmetry due to variation in color and irregularity in outline. In addition, there is pink discoloration in C. A, B were less than 0.5 mm in thickness and C was 0.8 mm. A, Courtesy, Kalman  

WNT/β-CATENIN SIGNALING PATHWAY

WNT LRP Frizzled

A

DSH

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Watsky MD; B, C, Courtesy, Jean L Bolognia, MD.

APC β-Catenin

TCF/LEF

Target genes

B

Gene expression leading to cell proliferation, differentiation, migration and adhesion Nucleus

eFig. 113.1 WNT/β-catenin signaling pathway. When extracellular WNT binds to the Frizzled/LRP receptor complex, the cytosolic protein dishevelled (DSH) is activated and can inhibit the “destruction complex”. The latter complex contains the adenomatous polyposis coli (APC) tumor suppressor protein and it can phosphorylate β-catenin. Phosphorylated β-catenin becomes ubiquitinated and then is targeted by the proteosome for destruction. Therefore, when DSH is activated by WNT binding, β-catenin is not phosphorylated and it accumulates and is translocated to the nucleus. There, it induces the transcription of target genes via the T-cell factor/lymphoid enhancer factor (TCF/LEF) family of transcription factors. LRP, low-density lipoprotein-receptor-related protein.  

C

eFig. 113.3 Nodular melanoma (NM). Rapidly growing black nodule that was >15 mm in diameter on the back of a male  

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eFig. 113.4 Lentigo maligna melanoma (LMM). A A pigmented lesion on the dorsal nose, with irregular borders, light to dark brown pigmentation and marked asymmetry.   B Dermoscopy demonstrating annular structures corresponding to follicular openings surrounded by melanoma cells (“circle in a circle”).

Neoplasms of The Skin



A

eFig. 113.5 Lentigo maligna. Large-sized brown patch with mild variation in color representing lentigo maligna.  

eFig. 113.7 A more advanced lentigo maligna melanoma on the ear (A) (Breslow depth = 0.86 mm), with corresponding dermoscopy (B).  

B

A

eFig. 113.6 Dermoscopy of lentigo maligna melanoma (Breslow depth = 0.45 mm). There is asymmetric pigmentation of the follicular openings and annular granular structures. Corresponds to Fig. 113.15A.  

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eFig. 113.8 Acral lentiginous melanoma.  

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Courtesy, Kalman Watsky, MD.

eFig. 113.9 Conjunctival melanoma.  

eFig. 113.10 Illustration of dermoscopy. This pair of images illustrates the clinical appearance (A), and the same lesion viewed with dermoscopy (B). Greater detail can be appreciated at 10- to 20-fold magnification. This lesion is an early invasive melanoma with sharp demarcation, asymmetry, and a central blue–whitish veil.  

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eFig. 113.12 Superficial spreading (“conventional”) melanoma – histopathologic features. Irregular intraepidermal nests and confluent dermal complexes of atypical melanocytes. Some of the atypical melanocytes have prominent nucleoli and one mitosis can be seen (inset). Courtesy, Lorenzo Cerroni, MD.  

B

eFig. 113.13 Acral lentiginous melanoma – histopathologic features. Atypical pigmented melanocytes arranged in irregular nests and as solitary units involve all layers of the epidermis and are also visible within the horny layer.  

Courtesy, Lorenzo Cerroni, MD.

C

eFig. 113.11 Dermoscopic appearance of superficial spreading cutaneous melanomas. A Striking asymmetry and streaks at the periphery. The latter have also been called radial streaming and pseudopods. B Streaks and blue–whitish veil. C Streaks, blue–whitish veil, and irregular blotches.  

eFig. 113.14 Melanoma in situ with extensive involvement of hair follicles. Large, confluent complexes of melanocytes are within the epidermis and the epithelium of several hair follicles. Seemingly intradermal complexes are likely still connected to the hair follicles, but the connection may not be visible in some sections. Courtesy, Lorenzo Cerroni, MD.  

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30. Buettner PG, Leiter U, Eigentler TK, Garbe C. Development of prognostic factors and survival in cutaneous melanoma over 25 years: an analysis of the Central Malignant Melanoma Registry of the German Dermatological Society. Cancer 2005;103:616–24. 31. Swetter SM, Soon S, Harrington CR, Chen SC. Effect of health care delivery models on melanoma thickness and stage in a university-based referral center: an observational pilot study. Arch Dermatol 2007;143:30–6. 32. Wellbrock C. Melanoma and the microenvironment – age matters. N Engl J Med 2016;375:696–8. 33. Lasithiotakis K, Leiter U, Meier F, et al. Age and gender are significant independent predictors of survival in primary cutaneous melanoma. Cancer 2008;112:1795–804. 34. Hayward NK. Genetics of melanoma predisposition. Oncogene 2003;22:3053–62. 35. Leachman SA, Carucci J, Kohlmann W, et al. Selection criteria for genetic assessment of patients with   familial melanoma. J Am Acad Dermatol 2009;61:677. e1–14. 36. Sharpless E, Chin L. The INK4a/ARF locus and melanoma. Oncogene 2003;22:3092–8. 37. Yang G, Rajadurai A, Tsao H. Recurrent patterns of dual RB and p53 pathway inactivation in melanoma. J Invest Dermatol 2005;125:1242–51. 38. Goldstein AM, Chan M, Harland M, et al. Features associated with germline CDKN2A mutations: a GenoMEL study of melanoma-prone families from three continents. J Med Genet 2007;44:99–106. 39. Hansen CB, Wadge LM, Lowstuter K, et al. Clinical germline genetic testing for melanoma. Lancet Oncol 2004;5:314–19. 40. Potrony M, Badenas C, Aguilera P, et al. Update in genetic susceptibility in melanoma. Ann Transl Med 2015;3:210. 41. Landi MT, Kanetsky PA, Tsang S, et al. MC1R, ASIP, and DNA repair in sporadic and familial melanoma in a Mediterranean population. J Natl Cancer Inst 2005;97:998–1007. 42. Fargnoli MC, Pike K, Pfeiffer RM, et al. MC1R variants increase risk of melanomas harboring BRAF mutations. J Invest Dermatol 2008;128:2485–90. 43. Landi MT, Bauer J, Pfeiffer RM, et al. MC1R germline variants confer risk for BRAF-mutant melanoma. Science 2006;313:521–2. 44. Bishop DT, Demenais F, Iles MM, et al. Genome-wide association study identifies three loci associated with melanoma risk. Nat Genet 2009;41:920–5. 45. Stolz W, Schmoeckel C, Landthaler M, Braun-Falco O. Association of early malignant melanoma with nevocytic nevi. Cancer 1989;63:550–5. 46. Stadler R, Garbe C. Nevus associated malignant melanomas–diagnostic validation and prognosis. Hautarzt 1991;42:424–9. 47. Bauer J, Garbe C. Risk estimation for malignant transformation of melanocytic nevi. Arch Dermatol 2004;140:127. 48. Tsao H, Bevona C, Goggins W, Quinn T. The transformation rate of moles (melanocytic nevi) into cutaneous melanoma. A populationbased estimate. Arch Dermatol 2003;139:282–8. 49. Rodenas JM, Delgado-Rodriguez M, Farinas-Alvarez C, et al. Melanocytic nevi and risk of cutaneous malignant melanoma in southern Spain. Am J Epidemiol 1997;145:1020–9. 50. Swerdlow AJ, English J, MacKie RM, et al. Benign melanocytic naevi as a risk factor for malignant melanoma. Br Med J (Clin Res Ed) 1986;292:1555–9. 51. Weiss J, Bertz J, Jung EG. Malignant melanoma in southern Germany: different predictive value of risk factors for melanoma subtypes. Dermatologica 1991;183:109–13. 52. Clark WH Jr, Reimer RR, Greene M, et al. Origin of familial malignant melanomas from heritable melanocytic lesions. ‘The B-K mole syndrome. Arch Dermatol 1978;114:732–8. 53. Garbe C, Buttner P, Weiss J, et al. Risk factors for developing cutaneous melanoma and criteria for identifying persons at risk: multicenter case-control study of the Central Malignant Melanoma Registry of the German Dermatological Society. J Invest Dermatol 1994;102:695–9. 54. Kraemer KH, Tucker M, Tarone R, et al. Risk of cutaneous melanoma in dysplastic nevus syndrome types A and B. N Engl J Med 1986;315:1615–16. 55. Tucker MA, Halpern A, Holly EA, et al. Clinically recognized dysplastic nevi. A central risk factor for cutaneous melanoma. JAMA 1997;277:1439–44.

2017

SECTION

Neoplasms of The Skin

18

2018

dermatological practice. Arch Dermatol 2005;141:434–8. 107. Grob JJ, Bonerandi JJ. The ‘ugly duckling’ sign: identification of the common characteristics of nevi in an individual as a basis for melanoma screening. Arch Dermatol 1998;134:103–4. 108. Scope A, Dusza SW, Halpern AC, et al. The “ugly duckling” sign: agreement between observers. Arch Dermatol 2008;144:58–64. 109. Kittler H, Guitera P, Riedl E, et al. Identification of clinically featureless incipient melanoma using sequential dermoscopy imaging. Arch Dermatol 2006;142:1113–19. 110. Cerroni L, Kerl H. Simulators of malignant melanoma of the skin. Eur J Dermatol 1998;8:388–96. 111. Kittler H, Pehamberger H, Wolff K, Binder M. Diagnostic accuracy of dermoscopy. Lancet Oncol 2002;3:159–65. 112. Braun RP, Thomas L, Kolm I, et al. The furrow ink test: a clue for the dermoscopic diagnosis of acral melanoma vs nevus. Arch Dermatol 2008;144:1618–20. 113. Phan A, Dalle S, Touzet S, et al. Dermoscopic features of acral lentiginous melanoma in a large series of 110 cases in a white population. Br J Dermatol 2010;162:765–71. 114. Ronger S, Touzet S, Ligeron C, et al. Dermoscopic examination of nail pigmentation. Arch Dermatol 2002;138:1327–33. 115. Menzies SW, Kreusch J, Byth K, et al. Dermoscopic evaluation of amelanotic and hypomelanotic melanoma. Arch Dermatol 2008;144:1120–7. 116. CRC Melanoma Pathology Panel. A nationwide survey of observer variation in the diagnosis of thin cutaneous malignant melanoma including the MIN terminology. J Clin Pathol 1997;50:202–5. 117. Clemente C, Cook M, Ruiter D, Mihm M. Histopathologic diagnosis of melanoma. World Health Organization Melanoma Programme Publications. Trezzano SN: Milan; 2001. 118. Cochran AJ, Bailly C, Cook M, et al. Recommendations for the reporting of tissues removed as part of the surgical treatment of cutaneous melanoma. The Association of Directors of Anatomic and Surgical Pathology. Am J Clin Pathol 1998;110:719–22. 119. de Wit NJ, van Muijen GN, Ruiter DJ. Immunohistochemistry in melanocytic proliferative lesions. Histopathology 2004;44:517–41. 120. Bauer J, Bastian BC. Distinguishing melanocytic nevi from melanoma by DNA copy number changes: comparative genomic hybridization as a research and diagnostic tool. Dermatol Ther 2006;19:40–9. 121. Held L, Eigentler TK, Metzler G, et al. Proliferative activity, chromosomal aberrations, and tumor-specific mutations in the differential diagnosis between blue nevi and melanoma. Am J Pathol 2013;182:640–5. 122. Gerami P, Mafee M, Lurtsbarapa T, et al. Sensitivity of fluorescence in situ hybridization for melanoma diagnosis using RREB1, MYB, Cep6, and 11q13 probes in melanoma subtypes. Arch Dermatol 2010;146:273–8. 123. Gerami P, Scolyer RA, Xu X, et al. Risk assessment for atypical spitzoid melanocytic neoplasms using FISH to identify chromosomal copy number aberrations. Am J Surg Pathol 2013;37:676–84. 124. Minca EC, Al-Rohil RN, Wang M, et al. Comparison between melanoma gene expression score and fluorescence in situ hybridization for the classification of melanocytic lesions. Mod Pathol 2016;29:  832–43. 125. Clarke LE, Warf MB, Flake DD II, et al. Clinical validation of a gene expression signature that differentiates benign nevi from malignant melanoma. J Cut Pathol 2015;42:244–52. 126. Shain H, Yeh I, Kovalyshyn I, et al. The genetic evolution of melanoma from precursor lesions. N Engl J Med 2015;373:1926–36. 126a.  Siroy AE, Boland GM, Milton DR, et al. Beyond BRAF(V600): clinical mutation panel testing by next-generation sequencing in advanced melanoma. J Invest Dermatol 2015;135:508–15. 127. Balch CM, Gershenwald JE, Soong SJ, et al. Final version of 2009 AJCC melanoma staging and classification. J Clin Oncol 2009;27:6199–206. 128. AJCC Cancer Staging Manual. American Joint Committee on Cancer. 8th ed. New York: Springer; 2017. p. 563–85. 129. Garbe C, Buttner P, Bertz J, et al. Primary cutaneous melanoma. Identification of prognostic groups and estimation of individual prognosis for 5093 patients. Cancer 1995;75:2484–91.

130. Wang TS, Johnson TM, Cascade PN, et al. Evaluation of staging chest radiographs and serum lactate dehydrogenase for localized melanoma. J Am Acad Dermatol 2004;51:399–405. 131. Bichakjian CK, Halpern AC, Johnson TM, et al. Guidelines of care for the management of primary cutaneous melanoma. American Academy of Dermatology. J Am Acad Dermatol 2011;65:  1032–47. 132. Blum A, Schlagenhauff B, Stroebel W, et al. Ultrasound examination of regional lymph nodes significantly improves early detection of locoregional metastases during the follow-up of patients with cutaneous melanoma: results of a prospective study of 1288 patients. Cancer 2000;88:2534–9. 133. Garbe C, Peris K, Hauschild A, et al. Diagnosis and treatment of melanoma: European consensus-based interdisciplinary guideline. Eur J Cancer 2010;46:270–83. 134. Garbe C, Leiter U, Ellwanger U, et al. Diagnostic value and prognostic significance of protein S-100beta, melanoma-inhibitory activity, and tyrosinase/MART-1 reverse transcription-polymerase chain reaction in the follow-up of high-risk melanoma patients. Cancer 2003;97:1737–45. 135. Tarhini AA, Stuckert J, Lee S, et al. Prognostic significance of serum S100B protein in high-risk surgically resected melanoma patients participating in Intergroup Trial ECOG 1694. J Clin Oncol 2009;27:38–44. 136. Muller-Horvat C, Radny P, Eigentler TK, et al. Prospective comparison of the impact on treatment decisions of whole-body magnetic resonance imaging and computed tomography in patients with metastatic malignant melanoma. Eur J Cancer 2006;42:342–50. 137. Pfannenberg C, Aschoff P, Schanz S, et al. Prospective comparison of (18)F-fluorodeoxyglucose positron emission tomography/computed tomography and whole-body magnetic resonance imaging in staging of advanced malignant melanoma. Eur J Cancer 2007;43:557–64. 138. Veronesi U, Cascinelli N, Adamus J, et al. Thin stage I primary cutaneous malignant melanoma. Comparison of excision with margins of 1 or 3 cm. N Engl J Med 1988;318:1159–62. 139. Balch CM, Soong SJ, Smith T, et al. Long-term results of a prospective surgical trial comparing 2 cm vs. 4 cm excision margins for 740 patients with 1-4 mm melanomas. Ann Surg Oncol 2001;8:101–8. 140. Guidelines Working P. Clinical Practice Guidelines for the Management of Melanoma in Australia and New Zealand. Sydney & Auckland: www.cancer.org.au/ skincancerguides; 2008. 141. Ross MI. Excision of primary melanoma. In: Balch CM, Houghton AN, Sober AJ, Soong SJ, et al., editors. Cutaneous melanoma. 5th ed. St Louis: CRC Press; 2009. p. 251–74. 142. Temple CL, Arlette JP. Mohs micrographic surgery in the treatment of lentigo maligna and melanoma. J Surg Oncol 2006;94:287–92. 143. Ly L, Kelly JW, O’Keefe R, et al. Efficacy of imiquimod cream, 5%, for lentigo maligna after complete excision: a study of 43 patients. Arch Dermatol 2011;147:1191–5. 144. Gautschi M, Oberholzer PA, Baumgartner M, et al. Prognostic markers in lentigo maligna patients treated with imiquimod cream: a long-term follow-up study. J Am Acad Dermatol 2016;74:81–7. 145. Tio D, van der Woude J, Prinsen CA, et al. A systematic review on the role of imiquimod in lentigo maligna and lentigo maligna melanoma: need for standardization of treatment schedule and outcome measures. J Eur Acad Dermatol Venereol 2017;31:  616–24. 146.  Tanabe K, Reintgen DS, Balch CM. Local recurrences of melanoma and their management. In: Balch CM, Houghton AN, Sober AJ, et al., editors. Cutaneous melanoma. 5th ed. St Louis: CRC Press; 2009.   p. 323–35. 147.  Balch CM, Gershenwald JE, Soong S-J, et al. Melanoma staging and classification. In: Balch CM, Houghton AN, Sober AJ, et al., editors. Cutaneous melanoma. 5th ed. St Louis: CRC Press; 2009. p. 65–85. 148. Kanzler MH, Mraz-Gernhard S. Primary cutaneous malignant melanoma and its precursor lesions: diagnostic and therapeutic overview. J Am Acad Dermatol 2001;45:260–76. 149. Mraz-Gernhard S, Sagebiel RW, Kashani-Sabet M, et al. Prediction of sentinel lymph node micrometastasis by

histological features in primary cutaneous malignant melanoma. Arch Dermatol 1998;134:983–7. 150. Veronesi U, Adamus J, Bandiera DC, et al. Delayed regional lymph node dissection in stage I melanoma of the skin of the lower extremities. Cancer 1982;49:2420–30. 151. Veronesi U, Adamus J, Bandiera DC, et al. Inefficacy of immediate node dissection in stage 1 melanoma of the limbs. N Engl J Med 1977;297:627–30. 152. Sim FH, Taylor WF, Pritchard DJ, Soule EH. Lymphadenectomy in the management of stage I malignant melanoma: a prospective randomized study. Mayo Clin Proc 1986;61:697–705. 153. Balch CM, Soong SJ, Bartolucci AA, et al. Efficacy of an elective regional lymph node dissection of 1 to 4 mm thick melanomas for patients 60 years of age and younger. Ann Surg 1996;224:255–63. 153a.  Faries MB, Thompson JF, Cochran AJ, et al. Completion dissection or observation for sentinelnode metastasis in melanoma. N Engl J Med 2017;376:2211–22. 154. Leiter U, Buettner PG, Bohnenberger K, et al. Sentinel lymph node dissection in primary melanoma reduces subsequent regional lymph node metastasis as well as distant metastasis after nodal involvement. Ann Surg Oncol 2010;17:129–37. 155. Kettlewell S, Moyes C, Bray C, et al. Value of sentinel node status as a prognostic factor in melanoma: prospective observational study. BMJ 2006;332:1423. 156. Morton DL, Thompson JF, Cochran AJ, et al. Sentinel-node biopsy or nodal observation in melanoma. N Engl J Med 2006;355:1307–17. 157. Morton DL, Thompson JF, Cochran AJ, et al. Final trial report of sentinel-node biopsy versus nodal observation in melanoma. N Engl J Med 2014;370:599–609. 158. McMasters K, Egger ME, Edwards MJ. Final results of the Sunbelt Melanoma Trial: a multi-institutional prospective randomized phase III study evaluating the role of adjuvant high-dose interferon alfa-2b and completion lymph node dissection for patients staged by sentinel lymph node biopsy. J Clin Oncol 2016;34:1079–86. 159. Lienard D, Eggermont AM, Koops HS, et al. Isolated limb perfusion with tumour necrosis factor-alpha and melphalan with or without interferon-gamma for the treatment of in-transit melanoma metastases: a multicentre randomized phase II study. Melanoma Res 1999;9:491–502. 160. Alexander HR Jr, Fraker DL, Bartlett DL, et al. Analysis of factors influencing outcome in patients with in-transit malignant melanoma undergoing isolated limb perfusion using modern treatment parameters. J Clin Oncol 2010;28:114–18. 161. Hoekstra HJ. The European approach to in-transit melanoma lesions. Int J Hyperthermia 2008;24:227–37. 162. Kirkwood JM. Adjuvant interferon in the treatment of melanoma. Br J Cancer 2000;82:1755–6. 163. Pehamberger H, Soyer HP, Steiner A, et al. Adjuvant interferon alfa-2a treatment in resected primary stage II cutaneous melanoma. Austrian Malignant Melanoma Cooperative Group. J Clin Oncol 1998;16:1425–9. 164. Grob JJ, Dreno B, de la Salmonière P, et al. Randomised trial of interferon alpha-2a as adjuvant therapy in resected primary melanoma thicker than 1.5 mm without clinically detectable node metastases. French Cooperative Group on Melanoma. Lancet 1998;351:1905–10. 165. Garbe C, Radny P, Linse R, et al. Adjuvant low-dose interferon α2a with or without dacarbazine compared with surgery alone: a prospective-randomized phase III DeCOG trial in melanoma patients with regional lymph node metastasis. Ann Oncol 2008;19:  1195–201. 166. Wheatley K, Ives NJ, Eggermont A, et al. Interferon-α as adjuvant therapy for melanoma: an individual patient data meta-analysis of randomised trials. J Clin Oncol 2007;25:8526. 167. Kirkwood JM, Ibrahim JG, Sondak VK, et al. High- and low-dose interferon alfa-2b in high-risk melanoma: first analysis of intergroup trial E1690/S9111/C9190. J Clin Oncol 2000;18:2444–58. 168. Hauschild A, Weichenthal M, Rass K, et al. Prospective randomized multicenter adjuvant dermatologic cooperative oncology group trial of low-dose interferon alfa-2b with or without a modified high-dose interferon alfa-2b induction phase in patients with lymph node-negative melanoma. J Clin Oncol 2009;27:3496–502.

182. Larkin J, Ascierto PA, Dreno B, et al. Combined vemurafenib and cobimetinib in BRAF-mutated melanoma. N Engl J Med 2014;371:1867–76. 183. Long GV, Stroyakovskiy D, Gogas H, et al. Combined BRAF and MEK inhibition versus BRAF inhibition alone in melanoma. N Engl J Med 2014;371:1877–88. 184. Tawbi H, Nimmagadda N. Targeted therapy in melanoma. Biologics 2009;3:475–84. 184a.  Kalinsky K, Lee S, Rubin KM, et al. A phase 2 trial of dasatinib in patients with locally advanced or stage IV mucosal, acral, or vulvovaginal melanoma: A trial of the ECOG-ACRIN Cancer Research Group (E2607). Cancer 2017;123:2688–97. 184b.  Guo J, Carvajal RD, Dummer R, et al. Efficacy and safety of nilotinib in patients with KIT-mutated metastatic or inoperable melanoma: final results from the global, single-arm, phase II TEAM trial. Ann Oncol 2017;28:1380–7. 184c.  Guo J, Si L, Kong Y, et al. Phase II, open-label, single-arm trial of imatinib mesylate in patients with metastatic melanoma harboring c-Kit mutation or amplification. J Clin Oncol 2011;29:2904–9. 185. Drake CG, Lipson EJ, Brahmer JR. Breathing new life into immunotherapy: review of melanoma, lung and kidney cancer. Nat Rev Clin Oncol 2014;11:24–37. 186. Hodi FS, O’Day SJ, McDermott DF, et al. Improved survival with ipilimumab in patients with metastatic melanoma. N Engl J Med 2010;363:711–23. 187. Robert C, Thomas L, Bondarenko I, et al. Ipilimumab plus dacarbazine for previously untreated metastatic melanoma. N Engl J Med 2011;364:2517–26. 188. Sarnaik AA, Weber JS. Recent advances using anti-CTLA-4 for the treatment of melanoma. Cancer J 2009;15:169–73. 189. Postow MA, Chesney J, Pavlick AC, et al. Nivolumab and ipilimumab versus ipilimumab in untreated melanoma. N Engl J Med 2015;372:2006–17. 190. Robert C, Long GV, Brady B, et al. Nivolumab in Previously Untreated Melanoma without BRAF Mutation. N Engl J Med 2015;372:320–30. 191. Larkin J, Chiarion-Sileni V, Gonzalez R, et al. Combined nivolumab and ipilimumab or monotherapy in untreated melanoma. N Engl J Med 2015;373:23–34. 192. Robert C, Schachter J, Long GV, et al. Pembrolizumab versus ipilimumab in advanced melanoma. N Engl J Med 2015;372:2521–32. 193. Hua C, Boussemart L, Mateus C, et al. Association of vitiligo with tumor response in patients with metastatic melanoma treated with pembrolizumab. JAMA Dermatol 2016;152:45–51. 194. Petrella T, Quirt I, Verma S, et al. Single-agent interleukin-2 in the treatment of metastatic melanoma: a systematic review. Cancer Treat Rev 2007;33:484–96. 195. Tarhini AA, Agarwala SS. Interleukin-2 for the treatment of melanoma. Curr Opin Investig Drugs 2005;6:1234–9.

196. Schwartzentruber DJ, Lawson D, Richards J, et al. A phase III multi-institutional randomized study of immunization with the gp100:209-217(210M) peptide followed by high-dose IL-2 compared with high-dose IL-2 alone in patients with metastatic melanoma. J Clin Oncol 2009;27:18S. 197. Lens M. The role of vaccine therapy in the treatment of melanoma. Expert Opin Biol Ther 2008;8:315–23. 198. Kirkwood JM, Lee S, Moschos SJ, et al. Immunogenicity and antitumor effects of vaccination with peptide vaccine+/-granulocyte-monocyte colony-stimulating factor and/or IFN-alpha2b in advanced metastatic melanoma: Eastern Cooperative Oncology Group Phase II Trial E1696. Clin Cancer Res 2009;15:1443–51. 199. Andtbacka HI, Kaufman HL, Collichio F, et al. Talimogene laherparepvec improves durable response rated in patients with advanced melanoma. J Clin Oncol 2015;33:2780–8. 200. Dudley ME, Wunderlich JR, Yang JC, et al. Adoptive cell transfer therapy following non-myeloablative but lymphodepleting chemotherapy for the treatment of patients with refractory metastatic melanoma. J Clin Oncol 2005;23:2346–57. 201.  Besser MJ, Shapira-Frommer R, Treves AJ, et al. Clinical responses in a phase II study using adoptive transfer of short-term cultured tumor infiltration lymphocytes in metastatic melanoma patients. Clin Cancer Res 2010;16:2646–55. 202. Jilaveanu LB, Aziz SA, Kluger HM. Chemotherapy and biologic therapies for melanoma: do they work? Clin Dermatol 2009;27:614–25. 203. Yang AS, Chapman PB. The history and future of chemotherapy for melanoma. Hematol Oncol Clin North Am 2009;23:583–97, x. 204. Middleton MR, Grob JJ, Aaronson N, et al. Randomized phase III study of temozolomide versus dacarbazine in the treatment of patients with advanced metastatic malignant melanoma. J Clin Oncol 2000;18:158–66. 205. Quirt I, Verma S, Petrella T, et al. Temozolomide for the treatment of metastatic melanoma: a systematic review. Oncologist 2007;12:1114–23. 206. Francken AB, Bastiaannet E, Hoekstra HJ. Follow-up in patients with localised primary cutaneous melanoma. Lancet Oncol 2005;6:608–21. 207. Garbe C. A rational approach to the follow-up of melanoma patients. Recent Results Cancer Res 2002;160:205–15. 208. Leiter U, Buettner PG, Eigentler TK, et al. Is detection of melanoma metastasis during surveillance in an early phase of development associated with a survival benefit? Melanoma Res 2010;20:240–6. 209. Garbe C, Paul A, Kohler-Spath H, et al. Prospective evaluation of a follow-up schedule in cutaneous melanoma patients: recommendations for an effective follow-up strategy. J Clin Oncol 2003;21:520–9.

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169. Hauschild A, Weichenthal M, Rass K, et al. Efficacy of low-dose interferon α2a 18 versus 60 months of treatment in patients with primary melanoma of >= 1.5 mm tumor thickness: results of a randomized phase III DeCOG trial. J Clin Oncol 2010;28:841–6. 170. Eggermont AM, Suciu S, Santinami M, et al. Adjuvant therapy with pegylated interferon alfa-2b versus observation alone in resected stage III melanoma: final results of EORTC 18991, a randomised phase III trial. Lancet 2008;372:117–26. 171. Grob JJ, Jouary T, Dreno B, et al. Adjuvant therapy with pegylated interferon alfa-2b (36 months) versus low-dose interferon alfa-2b (18 months) in melanoma patients without macrometastatic nodes: an open-label, randomised, phase 3 European Association for Dermato-Oncology (EADO) study. Eur J Cancer 2013;49:166–74. 172. Eggermont AM, Suciu S, Mackie R, et al. Post-surgery adjuvant therapy with intermediate doses of interferon alfa 2b versus observation in patients with stage IIb/III melanoma (EORTC 18952): randomised controlled trial. Lancet 2005;366:1189–96. 173. Eggermont AMM, Chiarion-Sileni V, Grob J-J, et al. Prolonged survival in Stage III melanoma with ipilimumab adjuvant therapy. N Engl J Med 2016;375:1845–55. 173a.  Ugurel S, Röhmel J, Ascierto PA, et al. Survival of patients with advanced metastatic melanoma: the impact of novel therapies-update 2017. Eur J Cancer 2017;83:247–57. 174. Neuman HB, Patel A, Ishill N, et al. A single-institution validation of the AJCC staging system for stage IV melanoma. Ann Surg Oncol 2008;15:2034–41. 175. Young SE, Martinez SR, Essner R. The role of surgery in treatment of stage IV melanoma. J Surg Oncol 2006;94:344–51. 176. Staudt M, Lasithiotakis K, Leiter U, et al. Determinants of survival in patients with brain metastases from cutaneous melanoma. Br J Cancer 2010;102:1213–18. 177. Schild SE. Role of radiation therapy in the treatment of melanoma. Expert Rev Anticancer Ther 2009;9:583–6. 178. Burmeister BH, Henderson MA, Ainslie J, et al. Adjuvant radiotherapy versus observation alone for patients at risk of lymph-node field relapse after therapeutic lymphadenectomy for melanoma: a randomised trial. Lancet Oncol 2012;13:589–97. 179. Samlowski WE, Watson GA, Wang M, et al. Multimodality treatment of melanoma brain metastases incorporating stereotactic radiosurgery (SRS). Cancer 2007;109:1855–62. 180. Chapman PB, Hauschild A, Robert C, et al. Improved survival with vemurafenib in melanoma with BRAF V600E mutation. N Engl J Med 2011;364:2507–16. 181. Hauschild A, Grob JJ, Demidov LV, et al. Dabrafenib in BRAF-mutated metastatic melanoma: a multicentre, open-label, phase 3 randomised controlled trial. Lancet 2012;380:358–65.

2019

SECTION 18 NEOPLASMS OF THE SKIN

114 

Vascular Neoplasms and   Neoplastic-Like Proliferations Paula E. North

Chapter Contents Benign vascular neoplasms, neoplastic-like conditions, and   reactive hyperplasias . . . . . . . . . . . . . . . . . . . . . . . . . . . 2020 Borderline and low-grade malignant vascular neoplasms . . . . 2035

■ Secondary forms are associated with venous malformations and other vascular anomalies prone to thrombosis ■ Rare forms are extravascular, probably arising within hematomas ■ Thought to represent an unusual, exuberant response of endothelial cells to organizing thrombus

Malignant vascular neoplasms . . . . . . . . . . . . . . . . . . . . . 2041 Perivascular neoplasms and neoplastic-like proliferations . . . . 2044

Introduction

INTRODUCTION In this chapter we use the term neoplasm synonymously with tumor in a general, albeit imperfect1, sense, consistent with its common usage: an abnormal proliferation (“new growth”) of cells that appears to be relatively autonomous (i.e. not reactive). Of note, common infantile hemangiomas are discussed separately (see Ch. 103) as are telangiectatic lesions (see Ch. 106) and vascular malformations (see Ch. 104); however, in some patients, vascular malformations may be associated with a number of the cellular vascular proliferations discussed herein. The chapter also includes a review of vascular lesions that were previously designated as vascular tumors (angiomas) but have since been reclassified as distinctive vascular malformations, e.g. glomu­ venous malformation (previously “glomangioma”), verrucous venulocapillary malformation (previously verrucous “hemangioma”). In addition, several entities with established or suspected features of reactive processes that mimic neoplasms are discussed as is Kaposi sarcoma, a virus-associated process of as-yet-uncertain position on the hyperplasia–neoplasia spectrum, but with an associated mortality rate. Two benign vascular proliferations of more seemingly straightforward infectious etiology (bacillary angiomatosis and verruga peruana) are covered elsewhere (see Ch. 74). With these caveats in mind, a broad working classification of vascular neoplasms and neoplastic-like conditions is presented in Table 114.1. Selected vascular neoplasms and neoplastic-like proliferations with their associated syndromes and characteristic laboratory findings are outlined in Fig. 114.1.

BENIGN VASCULAR NEOPLASMS AND REACTIVE HYPERPLASIAS Intravascular Papillary Endothelial Hyperplasia (PEH) Synonyms:  ■ Masson’s pseudoangiosarcoma ■ Masson’s tumor

Key features

2020

■ Not a specific disease entity, but rather a distinct histopathological pattern that can be confused with angiosarcoma ■ The primary or “pure” form is not associated with a pre-existing vascular anomaly and appears as a solitary, slowly growing, often painful nodule located within a dilated dermal, subcutaneous, or submucosal vein

Masson first described this process in 1923 in hemorrhoidal veins, terming it hemangio-endotheliome vegetant intravasculaire, and interpreted it as a neoplastic process mimicking angiosarcoma. In 1932, Henschen re-interpreted the process as reactive, and in 1971 Kauffman and Stout noted its occurrence not only in thrombosed vessels but also in a hematoma, further demonstrating the potential for confusion with soft tissue angiosarcoma. A lymphatic vessel counterpart of Masson’s lesion was reported in 1979 in a cystic lymphatic malformation2.

Epidemiology Papillary endothelial hyperplasia (PEH) shows a slight female predominance, most pronounced for the rare extravascular examples3. Although lesions can occur at any age, most are in adults, with an average age of 34 years. A history of trauma is elicited in a small minority of patients3.

Pathogenesis Areas of papillary endothelial hyperplasia can, in most cases, be seen to merge with definitive thrombus material, in support of the notion that they represent an unusual form of thrombus organization.

Clinical features Primary lesions of superficial tissues appear as solitary, firm masses, often with red or blue discoloration of the overlying skin or mucosa. The history is typically one of slow growth over a period of several months or years. These occur most commonly within veins of the head and neck and, interestingly, the fingers, but they may also arise elsewhere3. In a study of 314 cases, 56% were of the primary form, 40% were associated with other vascular lesions, and 4% appeared extravascularly3. Clinical features of the secondary forms are those of the underlying vascular anomaly.

Pathology Intravascular examples may be limited to the confines of a single thinwalled vein or may arise, often multifocally, within pre-existing vascular lesions such as venous malformations, glomuvenous malformations, spindle cell hemangiomas, and pyogenic granulomas (Fig. 114.2). Foci of intravascular PEH are extremely common in venous malformations and serve to distinguish these low-flow lesions from high-flow arteriovenous malformations. Rarely, the involved vessel wall is ruptured, allowing the proliferative vascular process to spill out into the adjacent stroma. Extravascular examples that on serial sectioning show no evidence of a surrounding blood vessel wall may have arisen within an organizing hematoma3. Early lesions show growth of endothelial sprouts into fibrinous thrombus material, dividing it into papillary fronds lined by a single layer of plump endothelial cells with minimal mitotic activity and no

In this chapter the term neoplasm is used synonymously with tumor in a general, albeit imperfect, sense, consistent with its common usage: an abnormal proliferation (“new growth”) of cells that appears to be relatively autonomous (i.e. not reactive). Of note, common infantile hemangiomas are discussed separately (see Ch. 103) as are telangiectatic lesions (see Ch. 106) and vascular malformations (see Ch. 104); however, in some patients, vascular malformations may be associated with a number of the cellular vascular proliferations discussed herein. The chapter also includes a review of vascular lesions that were previously designated as vascular tumors (angiomas) but have since been reclassified as distinctive vascular malformations, e.g. glomuvenous malformation (previously “glomangioma”), verrucous venulocapillary malformation (previously verrucous “hemangioma”). In addition, several entities with established or suspected features of reactive processes that mimic neoplasms are discussed as is Kaposi sarcoma, a virus-associated process of as-yet-uncertain position on the hyperplasia– neoplasia spectrum, but with an associated mortality rate. Two benign vascular proliferations of more seemingly straightforward infectious etiology (bacillary angiomatosis and verruga peruana) are covered elsewhere (see Ch. 74). With these caveats in mind, a broad working classification of vascular neoplasms and neoplastic-like conditions is presented.

vascular tumors, vascular malformations, hemangioma, angioendotheliomatosis, angiokeratoma, hemangioendothelioma, angiosarcoma, Kasabach–Merritt phenomenon, Kaposi sarcoma, glomus tumor, hemangiopericytoma, intravascular papillary endothelial hyperplasia, reactive angioendotheliomatosis, intravascular reactive angioendotheliomatosis, diffuse dermal angiomatosi, hobnail lymphatic malformation, hobnail hemangioma, targetoid hemosiderotic hemangioma, cherry angioma, sinusoidal hemangioma, tufted angioma, multifocal lymphangioendotheliomatosis with thrombocytopenia, glomeruloid hemangioma, microvenular hemangioma, epithelioid hemangioma, angiolymphoid hyperplasia with eosinophilia, pyogenic granuloma, lobular capillary hemangioma, spindle cell hemangioma, kaposiform hemangioendothelioma, Dabska-type hemangioendothelioma, papillary intralymphatic angioendothelioma, retiform hemangioendothelioma, glomuvenous malformation, glomangiosarcoma

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114 Vascular Neoplasms and Neoplastic-Like Proliferations

ABSTRACT

non-print metadata KEYWORDS:

2020.e1

Reactive conditions Intravascular papillary endothelial hyperplasia Reactive angioendotheliomatosis - Intravascular reactive angioendotheliomatosis - Diffuse dermal angiomatosis • Eruptive pseudoangiomatosis (self-limited exanthem of bright-red angioma-like lesions, originally described in children) • Pseudo-Kaposi sarcoma (acroangiodermatitis of Mali, Stewart–Bluefarb syndrome) • •

Telangiectasias (see Ch. 106) Angiokeratoma (exception is angiokeratoma circumscriptum, which represents a capillary/lymphatic or capillary malformation) Generalized essential telangiectasia • Cutaneous collagenous vasculopathy • Unilateral nevoid telangiectasia • Hereditary hemorrhagic telangiectasia • Hereditary benign telangiectasia • Cutis marmorata telangiectatica congenita • Angioma serpiginosum • Spider nevus • Venous lake • •

Vascular malformations (see Tables 104.2 & 104.5 for associated mutated genes) Capillary malformation (CM), includes subtypes nevus simplex, port-wine stain, reticulated CM, and geographic CM (see Ch. 104) Venous malformation • Lymphatic malformation (microcystic and macrocystic) • Mixed capillary/venous/lymphatic malformation • Arteriovenous malformation • Capillary malformation-arteriovenous malformation (CM-AVM) • Targetoid hemosiderotic lymphatic malformation (previously classified as hobnail “hemangioma” or targetoid hemosiderotic “hemangioma”) • Verrucous venulocapillary malformation (previously classified as verrucous “hemangioma”) • •

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114 Vascular Neoplasms and Neoplastic-Like Proliferations

A WORKING CLASSIFICATION OF CUTANEOUS VASCULAR ANOMALIES

Benign vascular neoplasms and neoplastic-like proliferations Infantile hemangioma (see Ch. 103 for details) Congenital hemangioma (includes non-involuting congenital hemangioma [NICH], rapidly involuting congenital hemangioma [RICH], and partially involuting congenital hemangioma; see Ch. 103 for details and mutated genes) • Pyogenic granuloma (lobular capillary hemangioma) * • Cherry angioma • Tufted angioma (likely a superficial form of kaposiform hemangioendothelioma) • Glomeruloid hemangioma * • Microvenular hemangioma * • Epithelioid hemangioma (angiolymphoid hyperplasia with eosinophilia [ALHE]) * • Multifocal lymphangioendotheliomatosis with thrombocytopenia# • Sinusoidal hemangioma ** • Spindle cell hemangioma *** • Epithelioid angiomatous nodule (debate as to whether it is a variant of epithelioid hemangioma) • Papillary hemangioma • Acquired elastotic hemangioma (capillary-like appearance in association with solar elastosis) • Cutaneous pseudoangiomatous stromal hyperplasia (primarily encountered in the breast) • Post-radiation atypical vascular lesions of the skin • •

Borderline and low-grade malignant vascular neoplasms Kaposiform hemangioendothelioma (KHE) Papillary intralymphatic angioendothelioma (PILA) (Dabska-type hemangioendothelioma, Dabska tumor) • Retiform hemangioendothelioma (RHE) • Epithelioid sarcoma-like hemangioendothelioma (pseudomyogenic hemangioendothelioma) • Kaposi sarcoma • •

Malignant vascular neoplasms Epithelioid hemangioendothelioma (EHE)† Angiosarcoma

• •

Perivascular neoplasms and neoplastic-like proliferations Glomus tumor (proper) Glomuvenous malformation (“glomangioma”) • Glomangiosarcoma • Infantile-type hemangiopericytoma/myofibromatosis • Adult-type hemangiopericytoma • Glomangiopericytoma • Myopericytoma • PEComa (perivascular epithelioid cell tumor)†† • •

#Not clear if a multifocal vascular neoplasm or malformation.

*Also viewed as a reactive condition. **Likely a sinusoidal pattern of intravascular endothelial hyperplasia within a pre-existing low-flow vascular malformation. Also viewed as a vascular malformation. *** † Reclassified by the WHO as a malignant, rather than intermediate or borderline, vascular tumor.

††A spectrum of mesenchymal tumors that includes clear cell “sugar” tumor of the lung, angiomyolipoma, lymphangiomyomatosis, clear cell myomelanocytic tumor, and the rare cutaneous tumors

with a similar morphology and phenotype.

Table 114.1 A working classification of cutaneous vascular anomalies. Entities covered in this chapter are in bold italics.  

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SELECTED VASCULAR NEOPLASMS AND NEOPLASTIC-LIKE PROLIFERATIONS − ASSOCIATED SYNDROMES AND LABORATORY FINDINGS

Glomeruloid hemangioma

Adults, trunk and extremities

Glomeruloid-like structures, PAS-positive globules

Epithelioid hemangioma

Adults, scalp region

Cobblestone endothelial cells, eosinophils, lymphocytes

Tufted hemangioma

Children and young adults, trunk and neck

Cannonball pattern

POEMS syndrome, Castleman disease

SPEP, IFE of serum and urine, endocrine tests

Eosinophilia

Kasabach−Merritt phenomenon Kaposiform hemangioendothelioma

Kaposi sarcoma

Less than 2 years old, any location

Adults, face and trunk if HIV-associated; legs if non-HIV-associated

Thrombocytopenia

Slit-like lumina

Slit-like lumina

HHV-8, HIV

Fig. 114.1 Selected vascular neoplasms and neoplastic-like proliferations – associated syndromes and laboratory findings. IFE, immunofixation electrophoresis; SPEP, serum protein electrophoresis; HHV-8, human herpesvirus 8; HIV, human immunodeficiency virus; PAS, periodic acid-Schiff stain.  

Treatment Surgical excision is usually curative. Local recurrences may occur when the lesion is superimposed on a vascular malformation that may generate new foci of endothelial hyperplasia.

Reactive Angioendotheliomatosis Key features ■ Rare, self-limited process occurring exclusively in the skin and characterized histologically by a dense proliferation of small capillaries ■ The most common form is predominantly intravascular, resulting in luminal obliteration of pre-existing dermal vessels; many of these patients have vaso-occlusive disorders or systemic infections ■ Should be distinguished from intravascular large cell lymphoma (B or NK/T), an angiotropic lymphoma erroneously termed malignant angioendotheliomatosis prior to the advent of discriminating immunohistochemistry

Fig. 114.2 Histology of papillary endothelial hyperplasia (PEH). Hyperplastic endothelial cells line stromal papillae formed within organizing thrombus material. Complex networks of recanalizing thrombus may mimic angiosarcoma (inset).  

significant cytologic atypia (Fig. 114.2, inset). The early fibrin cores of the papillae become collagenized and hyalinized with time, and the endothelial lining becomes thin and attenuated. Lesional papillae may fuse to form an anastomosing meshwork of vessels separated by connective tissue stroma that mimics angiosarcoma. However, the relatively high mitotic rate, striking pleomorphism, and necrosis that characterize angiosarcoma are lacking4.

Differential diagnosis 2022

The clinical appearance of these lesions is nonspecific, and diagnosis relies on microscopic examination. The most important consideration for the pathologist is well-differentiated angiosarcoma.

Introduction Angioendotheliomatosis has historically been considered to be a single disease entity, divided into benign and malignant variants. As such, the large pleomorphic cells found within blood vessels in malignant angioendotheliomatosis were thought to be transformed endothelial cells. However, immunohistochemical studies have convincingly demonstrated that these cells are neoplastic lymphocytes. Accordingly, malignant angioendotheliomatosis has been renamed intravascular large cell lymphoma (B or NK/T) (see Ch. 119). The benign form is a true angioendotheliomatosis and is considered reactive.

Epidemiology Reactive angioendotheliomatosis is rare and although it can occur at any age, the age of onset often reflects that of any associated systemic disorder. While many cases are idiopathic, this vascular proliferation is associated with systemic disorders such as bacterial endocarditis, monoclonal gammopathies (including type I cryoglobulinemia),

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114 Vascular Neoplasms and Neoplastic-Like Proliferations

antiphospholipid syndrome, renal transplantation, hepatic disease, and rheumatoid arthritis. The diffuse dermal angiomatosis variant occurs most commonly on the leg or the breast5 and is associated with atherosclerosis, cigarette smoking, and large pendulous breasts.

Pathogenesis Reactive angioendotheliomatosis is a benign self-limited process. Its frequent association with various systemic conditions has led some investigators to propose that the capillary proliferation may be caused by a circulating angiogenic factor6. However, the fact that many of the disorders associated with this process cause vascular occlusion or tissue ischemia suggests that a local, hypoxia-induced increase in vascular endothelial growth factor (VEGF) may be playing a role. In addition, immunological factors may contribute to the proliferative process.

Clinical features Although erythematous nodules or plaques, often with superimposed petechiae or ecchymoses, are the characteristic primary lesions, the spectrum ranges from erythematous macules to tumor-like masses. Sites of involvement can vary, but the most common is the lower extremities. Focal ulceration may be evident, especially in the diffuse dermal angiomatosis variant (see Fig. 105.20).

A

Pathology In this predominantly dermal, but also occasionally subcutaneous, process, there is a poorly marginated proliferation of closely packed capillaries lined by plump endothelial cells rimmed by small numbers of pericytes. The pattern of proliferation is highly variable both within and between lesions and is typically described as diffuse and/or lobular7. Focally, more dilated capillaries may be present and foci of hemosiderin deposition, fibrin microthrombi, and/or mild chronic inflammation are relatively common. Immunohistochemical positivity for endothelial markers such as CD31 and von Willebrand factor, and focally for pericyte/smooth muscle-associated actins, confirms the cellular composition. Cytologic atypia is absent and mitotic figures are rare to absent. The capillary lumina are small and may be occluded by fibrin thrombi and bulging endothelial cells (Fig. 114.3A). In many cases, the proliferating capillaries appear to be contained within a larger, pre-existing vessel, obliterating its lumen, but sometimes the proliferation extends directly between collagen bundles (Fig. 114.3B). Cases associated with cryoglobulinemia typically show intraluminal and intracellular eosinophilic globules, but this finding can also be seen in the absence of cryoglobulinemia.

Differential diagnosis The clinical differential diagnosis includes vascular tumors (e.g. Kaposi sarcoma, angiosarcoma) as well as other causes of ulceration (see Fig. 105.1). Histologically, one must consider other forms of intravascular endothelial proliferation, including intravascular pyogenic granuloma, papillary intralymphatic angioendothelioma, and intravascular PEH. Intralymphatic histiocytosis can be distinguished by the presence of CD68-positive histiocytes within dilated lymphatic vessels.

Treatment Evaluation for known associated systemic disorders is important because lesions may regress upon resolution of the underlying condition, e.g. revascularization of an ischemic limb. In case reports, oral isotretinoin has led to improvement, possibly due to its antiangiogenic properties8.

Angiokeratomas Key features ■ Small, dark, vascular, and variably keratotic lesions that result from dilation of superficial vessels ■ Angiokeratoma circumscriptum is a capillary–lymphatic or capillary malformation ■ Angiokeratoma corporis diffusum results from several lysosomal storage disorders and is associated with systemic manifestations

B

Fig. 114.3 Reactive angioendotheliomatosis. A Intravascular variant with proliferation of grouped capillaries along the course of a dermal blood vessel. The endothelial cells lack atypia and within several capillaries there is an intraluminal proliferation of endothelial cells admixed with erythrocytes occluding the lumina. B Diffuse dermal angiomatosis variant with proliferation of hyperplastic endothelial cells without atypical features infiltrating the dermis and forming small vascular lumina. A, Courtesy, Heinz Kutzner, MD; B, Courtesy,  

Lorenzo Cerroni, MD.

Introduction Angiokeratomas are well-circumscribed vascular lesions consisting of superficial vascular ectasia and hyperkeratosis. Five variants have been recognized. With the exception of angiokeratoma circumscriptum (which represents a capillary–lymphatic or capillary malformation), angiokeratomas result from ectatic dilation of pre-existing vessels in the papillary dermis.

Clinical features Solitary or multiple angiokeratomas

Most commonly, they present as a small, warty, black papule on the lower extremities, but may occur anywhere on the body (Fig. 114.4). The lesions are thought to result from injury to or chronic irritation of the wall of a venule in the papillary dermis. Solitary lesions may be confused with melanoma due to their dark color. Dermoscopy will readily distinguish between these two entities (see Ch. 0).

Angiokeratomas of the scrotum and vulva Synonym:  ■ Angiokeratoma of Fordyce

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Fig. 114.4 Solitary angiokeratoma. Because of their dark color, these lesions may resemble cutaneous melanoma. Dermoscopy will readily distinguish between these two entities.

Fig. 114.6 Angiokeratoma circumscriptum. These grouped red–violet papules had been present since childhood.

NEOPLASMS OF THE SKIN





Courtesy, Jean L Bolognia, MD.

Courtesy, Jean L Bolognia, MD.

papules and nodules that often become confluent. They occur on the trunk, arms or legs and are unilateral in most patients. There is a female predominance.

Pathology Marked dilatation of the papillary dermal vessels is seen in association with an acanthotic, variably hyperkeratotic epidermis. Elongated rete ridges may partially or completely enclose vascular channels, and a collarette may be present at the margin of the lesions. In Fabry disease, vacuoles can be detected within endothelial cells and pericytes. The amount of glycolipid is small and may be difficult to detect in routinely prepared sections. However, the deposits stain positively with PAS and anti-GB3 antibody. They can also be demonstrated by electron microscopy. Fig. 114.5 Scrotal angiokeratomas. These lesions typically arise along superficial vessels.  

These angiokeratomas may arise in the second or third decade but are most commonly seen in older age groups. The lesions are red–purple to black in color, may be single or multiple, and arise along superficial vessels (Fig. 114.5). In some patients, they may be associated with thrombophlebitis, varicoceles, and inguinal hernias. Vulvar lesions may be associated with vulvar varicosities, hemorrhoids, oral contraceptive use, or increased venous pressure during pregnancy.

Angiokeratoma corporis diffusum

This disorder is characterized by the development of multiple, often clustered angiokeratomas, usually in a bathing trunk distribution. Lesions vary in number (from only a few to numerous) and usually begin to appear during late childhood or adolescence. X-linked recessive Fabry disease is the best-known entity with this clinical presentation and results from a deficiency of the lysosomal enzyme α-galactosidase A (see Ch. 63). This leads to the accumulation of the neutral glycolipid ceramide trihexidose within lysosomes of multiple cell types. Other enzyme deficiencies associated with angiokeratoma corporis diffusum are outlined in Table 63.7.

Angiokeratoma of Mibelli

Lesions usually develop between the ages of 10 and 15 years and are most commonly situated on the dorsal and lateral aspects of the fingers and toes. They may also occur on the dorsa of the hands and feet and rarely on the elbows and knees. Angiokeratoma of Mibelli may be associated with chilblains and acrocyanosis. In rare instances, ulceration of the fingertips can occur. There is a familial predisposition and the disorder may be transmitted in an autosomal dominant fashion with variable penetrance.

Angiokeratoma circumscriptum 2024

This entity usually develops during infancy or childhood as either a plaque of multiple discrete papules (Fig. 114.6) or hyperkeratotic

Differential diagnosis Clinically, angiokeratomas should be distinguished from other vascular lesions as well as acral pseudolymphomatous angiokeratomas (see Ch. 121). Darkly colored or thrombosed angiokeratomas may resemble cutaneous melanoma.

Treatment Patients may request removal for cosmetic reasons. This may be achieved by shave excision, diathermy or laser therapy, the choice of which would largely depend on the size of the lesion.

Targetoid Hemosiderotic Lymphatic Malformation (Hobnail “Hemangioma”) Synonyms:  ■ Targetoid hemosiderotic hemangioma ■ Superficial hemosiderotic lymphovascular malformation ■ Hobnail lymphatic malformation

Key features ■ Uncommon acquired vascular lesion that usually presents as a red–blue or brown papule, most commonly on the extremities and often with a history of local trauma ■ The papule is sometimes surrounded by a pale ring and then an ecchymotic halo ■ Biphasic pattern of dilated, thin-walled vessels with hobnail endothelial cells in the superficial dermis, transitioning to smaller, slit-like vessels in the deeper dermis ■ Lesional endothelial cells strongly express the lymphoendothelial marker podoplanin and have minimal expression of CD34, consistent with lymphatic differentiation

The original description in 1988 coined the term targetoid hemosiderotic hemangioma to emphasize the targetoid clinical appearance and hemosiderin deposition. Since then it has become apparent that only a minority of these lesions have an ecchymotic halo and hemosiderin deposition is variable. The term hobnail hemangioma was proposed to encompass lesions with the characteristic biphasic growth pattern and marked hobnail endothelial morphology, with or without a targetoid clinical appearance and/or marked hemosiderin deposition9,10. A benign clinical course has been observed in the over 100 cases that have been reported to date10,11. Recently, this “hemangioma” was reclassified as a targetoid hemosiderotic lymphatic malformation (THLM)12.

Epidemiology There is no gender predilection10. In a series of 62 patients, their ages ranged from 6 to 72 years (median, 32 years)11.

Pathogenesis This vascular anomaly was thought to represent the benign end of a spectrum of vascular tumors that have hobnail endothelial cells and which includes papillary intralymphatic angioendothelioma (PILA) and retiform hemangioendothelioma (see Table 114.1)9. However, the endothelial cells of THLM and PILA, but not retiform hemangioendothelioma, stain positively for several markers of lymphatic differentiation11,13. In addition, the endothelial cells of THLM are generally negative for Wilms tumor-1 and have a low Ki-67 proliferation index. The latter explains its reclassification as a vascular malformation based upon International Society for the Study of Vascular Anomalies (ISSVA)sanctioned restriction of the suffix “angioma” to intrinsically proliferative vascular tumors12. Trauma may stimulate the appearance of a THLM, with microshunts between small lesional blood vessels and adjacent lesional lymphatic vessels explaining the presence of erythrocytes within lymphatic vessels and hemosiderin deposits13.

Clinical features Most lesions are asymptomatic, solitary, well-circumscribed, red–blue to brown papules that are initially 2 to 3 mm in diameter and then slowly increase in size. In some cases, the papule is surrounded by a thin pale ring and then an ecchymotic halo (Fig. 114.7). The ecchymotic ring may fade and eventually disappear over time, and some lesions undergo cycles of spontaneous regression and recurrence. Favored sites, in decreasing order of frequency, are the lower extremities, upper extremities, back, buttock/hip, and chest wall. Lesions have also been reported on the tongue and gingiva10.

slit-like vessels stain positively for the lymphoendothelial markers VEGF-3 and podoplanin (see Ch. 102), but show little, if any, reactivity for the blood vascular marker CD3411,13.

Differential diagnosis The clinical differential diagnosis includes melanocytic nevus, sclerosing hemangioma, and benign vascular neoplasms and proliferations in Table 114.110. Histopathologically, it must be distinguished from patchstage and lymphangioma-like variants of Kaposi sarcoma, welldifferentiated angiosarcoma, retiform hemangioendothelioma, PILA, and microcystic lymphatic malformation.

Treatment Treatment consists of simple excision. Longitudinal evaluation of 35 patients, ranging from 1 to 4 years, revealed no local recurrence or systemic metastasis11.

Verrucous Venulocapillary Malformation (Verrucous “Hemangioma”) Synonym:  ■ Verrucous venous malformation

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114 Vascular Neoplasms and Neoplastic-Like Proliferations

Introduction and history

Key features ■ Rare congenital vascular anomaly that has been reclassified as a vascular malformation ■ Somatic missense mutations in mitogen-activated protein kinase kinase kinase 3 gene (MAP3K3) detected in some lesions ■ Isolated, grouped, or confluent red-to-purple papules with reactive hyperkeratosis; often darkens with age ■ Most commonly occurs on the distal extremity and can be complicated by ulceration and bleeding but not local tissue hypertrophy ■ Histologically, dilated capillaries and venules are present within the papillary and investing dermis and subcutis but not the reticular dermis

Pathology There is a biphasic histologic pattern, consisting of: (1) dilated, thinwalled vessels containing small numbers of red blood cells and lined by prominent hobnail endothelial cells within the superficial dermis (Fig. 114.8); and (2) smaller, more slit-like vessels that dissect between collagen bundles in deeper portions of the dermis. Extravasated red blood cells and hemosiderin deposits are common, but may be absent. Although the superficial vessels occasionally have delicate intraluminal papillary fronds, the more complex, multilayered endothelial tufts of PILA are lacking. The endothelial cells of both the dilated and the Fig. 114.7 Targetoid hemosiderotic lymphatic malformation (hobnail “hemangioma”). Note the target-like appearance. Courtesy,  

Ronald P Rapini, MD.

Fig. 114.8 Histology of targetoid hemosiderotic lymphatic malformation (hobnail “hemangioma”). Dilated superficial dermal vessels lined by hobnailed endothelial cells, merging with smaller slit-like vessels in the lower dermis.  

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Introduction and history This rare, but increasingly well-recognized, vascular anomaly was originally thought to be a “hemangioma”, but has since been reclassified as a vascular malformation. The debate arose in part because these lesions may show evidence of cellular proliferation during their evolution14. Mulliken and colleagues recommended use of the term verrucous venous malformation15 while others prefer the designation verrucous venulocapillary malformation, congruent with the predominant component vessels.

Epidemiology There are no gender, racial or ethnic predilections.

Pathogenesis Somatic missense mutations in the mitogen-activated protein kinase kinase kinase 3 gene (MAP3K3) were detected in 6 of 10 verrucous venulocapillary malformations15. The mutant allele frequencies ranged from 6–19% in affected tissue and these mutations were not found in unaffected tissue or other types of vascular anomalies. Of note, studies in MAP3K3 knockout mice had previously implicated MAP3K3 in vascular development.

A

Clinical features Verrucous venulocapillary malformations are congenital and present as isolated, grouped or confluent red-to-purple papules. The vast majority occur on the distal extremities, particularly the leg (Fig. 114.9A); the trunk is a rare location16. They progressively darken and become hyperkeratotic during childhood, often increasingly complicated by ulceration, bleeding, and scarring. They do not regress and are not associated with local tissue hypertrophy or other developmental anomalies.

Pathology Features can vary with age, in particular the appearance of secondary orthohyperkeratosis and verrucous hyperplasia, but consistently there are dilated capillaries and venules (without a smooth muscle layer) within the papillary dermis and occasionally the investing dermis around adnexae. There is sparing of the reticular dermis, with the dilated blood vessels reappearing in the subcutis, where they are usually smaller in caliber, often grouped, and sometimes have intraluminal thrombi (Fig. 114.9B). The superficial dermal vessels are usually the most obviously dilated with expansion of the dermal papillae (Fig. 114.9C). Endothelial cells consistently express markers of blood vascular differentiation, including CD31 and CD34. Focal positivity for lymphatic endothelial markers, e.g. Prox1, podoplanin, has been observed in some, but not all, studies17,18. Mitotic activity is very low. Many verrucous venulocapillary malformations have light, focal immunoreactivity for GLUT1, in contrast to the intense endothelial GLUT1 positivity seen in infantile hemangiomas19,20; staining for CD15 and indolamine 2,3 deoxygenase is negative (personal observation).

B

Differential diagnosis and treatment The differential diagnosis includes other venous malformations (see Ch. 104) and infantile hemangiomas. Therapeutic options include surgical excision and treatment of the superficial component with pulsed dye, long-pulsed Nd:YAG, and/or carbon dioxide lasers.

Pyogenic Granuloma

C

Fig. 114.9 Verrucous venulocapillary malformation (verrucous “hemangioma”) – clinical and histologic features. A Linear array of purple plaques on the thigh; the thicker portions of the plaques are darker in color with overlying scale. B Ectatic venules and capillaries infiltrate the subcutis. C Ectatic capillaries and venules expand the papillary dermis; note the hyperkeratosis. A, Courtesy, Julie V Schaffer, MD.  

Synonyms:  ■ Lobular capillary hemangioma ■ Granuloma

pyogenicum ■ Tumor of pregnancy ■ Eruptive hemangioma ■ Granulation tissue-type hemangioma

Key features

2026

■ Rapidly growing, friable, red papule or polyp of skin or mucosa that frequently ulcerates; most common in children and young adults ■ Those arising on the gingiva of pregnant women (granuloma gravidarum) are considered a separate subgroup, but are histologically indistinguishable

■ Consist of lobules of small capillaries set in a fibromyxoid matrix, often distinctly exophytic and bounded by collarettes of hyperplastic epithelium ■ Occasionally found in subcutaneous or intravascular locations ■ Neither infectious in etiology nor granulomatous histologically; often considered a reactive vascular hyperplasia rather than a neoplasm



A

B

C

Introduction and history

Fig. 114.11 Histology of pyogenic granuloma. Proliferating capillaries are often grouped into lobules by dense fibrous bands, hence the synonym lobular capillary hemangioma. The lesion is often clutched by an epithelial  

Poncet and Dor are credited with the initial description in 1897, and they believed the cause was a Botryomyces infection. The term granuloma pyogenicum was coined in 1904 by Hartzell to describe four similar cases that he thought represented a nonspecific granulation tissue-type response to any type of pyogenic agent21. Although the etiology of these common lesions remains uncertain, the term pyogenic granuloma is clearly a misnomer. There is no evidence to implicate any infectious agent, and the histologic appearance is not granulomatous.

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114 Vascular Neoplasms and Neoplastic-Like Proliferations

Fig. 114.10 Pyogenic granuloma. A Eroded pink–red papulonodule with a narrow base on the scalp.   B Pedunculated papule on the finger. C Grouped red papules on the lip. The latter two are both common sites. By dermoscopy, red homogeneous areas are intersected by white lines (see  Ch. 0). A, Courtesy, Julie V Schaffer, MD.

Epidemiology Pyogenic granulomas can develop at any age but are more common in children and young adults. There may be a slight male predominance, but no racial or familial predisposition. Gingival lesions are relatively common during pregnancy (see Ch. 27).

Pathogenesis Pyogenic granulomas exhibit a number of clinical features suggestive of reactive neovascularization, including a common association with a pre-existing injury or irritation, limited capacity for growth, and a propensity for multiple eruptions that may be localized or disseminated. The occasional eruption of pyogenic granulomas within existing portwine stains22 and other vascular malformations suggests that abnormalities in blood flow may be etiologically important in some cases.

Clinical features The lesion presents as a solitary red papule or polyp that grows rapidly over the course of several weeks or months, stabilizes, and then may decrease in size (Fig. 114.10). Its final size is rarely >1 cm, and it may persist indefinitely if not removed. Approximately one-third develop following minor trauma. In one series of 289 cases, the most common sites, in decreasing order of frequency, were the gingiva, fingers, lips, face, and tongue23. They are extremely friable, frequently ulcerate, and may bleed profusely with minor trauma. Multiple satellite lesions occasionally develop near a primary pyogenic granuloma, usually after destruction of that lesion24. Rarely, pyogenic granulomas arise within the subcutis, develop intravascularly, or erupt in a disseminated fashion25. Pyogenic granulomas have been reported in association with systemic retinoids26, indinavir, and BRAF and EGFR inhibitors, but in some cases this may represent excessive granulation tissue.

Pathology The quintessential lesion is a well-circumscribed, exophytic, sometimes pedunculated, proliferation of small capillaries, often arranged in a lobular pattern (Fig. 114.11). Lesional capillaries are lined by flattened to slightly plump endothelial cells, rimmed by pericytes, and surrounded by a variably edematous fibromyxoid interstitial stroma containing fibroblasts. Endothelial and stromal cell mitotic activity is highly variable and depends on the stage of growth; a scant infiltrate of lymphocytes, plasma cells, and mast cells may be present. Capillary lumina within the lobules vary from small and angular to branching and ectatic, and foci of thrombosis and intravascular PEH may be present. A few larger vessels with smooth muscle walls, usually venous (but often including a small ascending arterial feeder), are frequently present at the base of the lesion. Thick, intervening bands of dense fibrous tissue sharply define the lobularity and help distinguish pyogenic granuloma from other lobular forms of capillary proliferation such as infantile hemangioma.

The lateral margins are often defined by prominent epithelial “collarettes” resulting from peripheral adnexal hyperplasia or, in some cases, from downward growth of rete ridges, bridged by flattened epidermis. The histology of many early lesions is altered by ulceration and secondary inflammatory changes, leading to an appearance similar to granulation tissue, with radially oriented capillaries, fibrin deposition, and a loss of lobularity. Intravascular and subcutaneous forms demonstrate features similar to superficial lesions, but without the inflammatory complications. Late-stage lesions are characterized by increased intralobular and interlobular fibrosis, as well as quiescent, flattened capillary endothelia.

Differential diagnosis The diagnosis of pyogenic granuloma can be made clinically if the red, bleeding papule is coupled with the characteristic location and history. Otherwise they can be easily confused with amelanotic melanoma and, in the immunosuppressed patient, bacillary angiomatosis or Kaposi sarcoma. Glomus tumors, hemangiomas, and irritated melanocytic nevi and warts can all mimic pyogenic granulomas. Histologic confirmation is always helpful in cases where the diagnosis is in question.

Treatment Shave excision followed by electrosurgery of the base under local anesthesia is sufficient for most lesions. Patients and parents should be alerted to the possibility of recurrence after removal. Excision with suturing may result in less postoperative bleeding and a lower recurrence rate. Pulsed dye laser has also been shown to be a safe and effective treatment for small pyogenic granulomas and may be particularly useful in children27. There is a report of successful sclerotherapy in nine patients using monoethanolamine oleate, with inconspicuous scar formation and no recurrence28.

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SECTION

NEOPLASMS OF THE SKIN

18

Cherry Angioma Synonyms:  ■ Cherry hemangioma ■ Senile angioma ■ Campbell–De Morgan spot

Key features ■ Bright red, dome-shaped to polypoid papules up to several millimeters in diameter that begin appearing during adult life, most commonly on the trunk and upper extremities ■ A common, benign lesion found in most individuals by the age of 60 years, often in large numbers ■ Consist of dilated, congested capillaries and postcapillary venules within the papillary dermis

Introduction and history Cherry angiomas are the most common of the acquired cutaneous vascular proliferations. They can be unattractive and rarely when eruptive herald an underlying systemic abnormality.

Epidemiology Both sexes are affected equally. Although they may occasionally develop during adolescence, cherry hemangiomas usually first appear during the third decade of life or later, and then increase in number over time. Most people over 60 years of age have one or more such lesions.

Pathogenesis An increased number of cherry angiomas often appear during pregnancy and may involute in the postpartum period, suggesting that hormonal factors may be important in their pathogenesis. Two women with hundreds of eruptive cherry hemangiomas, both of whom had increased serum levels of prolactin, have also been reported29. Most angiomas that appear in the setting of POEMS syndrome are cherry angiomas, often in association with glomeruloid hemangiomas.

Clinical features Cherry angiomas are round to oval, bright red to purple, dome-shaped papules ranging in size from barely visible to several millimeters in diameter (Fig. 114.12). Well-developed lesions may be polypoid. They most commonly develop on the trunk and proximal extremities and are rare on the hands, feet, and face. It is not unusual for elderly adults to have 50–100 cherry angiomas on their trunk. Rarely, a segmental distribution pattern, possibly reflecting mosaicism, is seen.

Patients are usually aware of the benign nature of these extremely common lesions and bring them to a physician’s attention only when concerned about their appearance. They are generally asymptomatic, but may occasionally bleed when traumatized.

Pathology Histologically, congested, ectatic capillaries and postcapillary venules are seen within the papillary dermis and superficial reticular dermis (Fig. 114.12, inset). Early lesions are characterized by small lumina and plump endothelial cells. With maturation, the vessels dilate and the endothelial cell cytoplasm flattens, often producing slightly hobnailed nuclei. Vessel diameter decreases with descent into the reticular dermis. There is loss of epidermal ridges centrally and peripherally adnexal epithelial collarettes are seen.

Differential diagnosis The distinctive clinical and dermoscopic findings (see Ch. 0) limit other diagnostic considerations. Glomeruloid hemangiomas, although similar in clinical appearance, can be distinguished histologically. Tiny cherry angiomas may resemble petechiae.

Treatment Patients may request removal of cosmetically undesirable or chronically traumatized cherry angiomas. This can be accomplished by shave excision, electrodesiccation or laser ablation, and recurrences are unusual.

Tufted Angioma Synonyms:  ■ Acquired tufted angioma ■ Angioblastoma of

Nakagawa ■ Tufted hemangioma ■ Hypertrophic hemangioma ■ Progressive capillary hemangioma

Key features ■ Usually presents as an acquired lesion in children and young adults, but may be congenital ■ Inhomogeneous pink to red patches and plaques with superimposed papules that spread slowly, often to involve large areas, then stabilize; rarely completely regress ■ Most commonly located on neck or trunk ■ When congenital can be associated with Kasabach–Merritt phenomenon ■ Generally thought to represent a mild superficial form of kaposiform hemangioendothelioma ■ Characterized histologically by tightly packed tufts of tiny capillaries distributed within the dermis and subcutis in a “cannonball” pattern; foci of spindled endothelial cells may also be present

Introduction Tufted angioma has often been lumped erroneously with infantile hemangioma under the generic term “capillary hemangioma”. However, a distinction is important given its association with Kasabach–Merritt phenomenon in some infants. In older children and adults, it may clinically mimic Kaposi sarcoma. Current opinion is that tufted angioma falls within a spectrum shared by kaposiform hemangioendothelioma (KHE), with the latter usually having deeper involvement of soft tissues.

History Fig. 114.12 Cherry angioma. Multiple compressible red papules. Histologically, congested capillaries and postcapillary venules expand the papillary dermis (inset). Courtesy, Jean L Bolognia, MD.  

2028

Tufted angioma was first described in 1989 by Wilson-Jones and Orkin30. Apparently identical lesions had been described many years previously as angioblastoma31 and progressive capillary hemangioma32. The association of tufted angioma with Kasabach–Merritt phenomenon, shared by KHE, is now widely recognized33.

Most lesions occur in young adults and children, many during the first year of life. Over 50% present before 5 years of age30, and ~15% are congenital30. Rarely, lesions appear late in life34. Although one family with several affected family members has been reported35, the vast majority of cases are sporadic.

KHE are typically absent in tufted angioma38. Of note, the endothelial cells of tufted angioma do not immunoreact for infantile hemangiomaassociated antigens such as GLUT1 and Lewis Y antigen20. Ultrastructural studies have demonstrated classical Weibel–Palade bodies. In cases associated with Kasabach–Merritt phenomenon, platelet trapping has been confirmed with CD61 immunoreaction41.

Differential diagnosis

Pathogenesis

Tufted angiomas appear as mottled red patches or plaques with superimposed angiomatous papules, typically on the neck, trunk or shoulders, that grow slowly by lateral extension over a period of 5 months to 10 years30 (Fig. 114.13). Occasionally, lesions have an associated growth of lanugo hair or port-wine-like stain39. Platelet trapping (Kasabach–Merritt phenomenon) may develop in congenital cases, although less commonly than in KHE. Lesions eventually stabilize in size, then may persist unchanged, shrink, or leave a fibrotic residuum. Rarely, complete spontaneous regression has been observed39. Occasionally lesions are painful, and exacerbations of pain may occur during periods of uncontrolled platelet trapping40.

Congenital/early infantile tufted angiomas must be differentiated from infantile hemangiomas, the most common tumors of infancy (see Ch. 103). The latter are positive for placental capillary-associated endothelial markers (e.g. GLUT1) and show more rapid growth (without lateral extension) during the first year of life, followed by spontaneous, slow involution20. Infantile hemangiomas are transiently positive for the lymphatic-associated marker LYVE-1 early in their course, presumably as an expression of their embryonic, cardinal vein-type endothelial phenotype42, but lack other lymphatic markers such as podoplanin and Prox142,43. Other entities that may mimic the clinical appearance of tufted angioma include pyogenic granuloma arising within a vascular malformation and Kaposi sarcoma. Pyogenic granuloma can be distinguished histologically by its characteristic edematous stroma, granulation tissue-type changes, lack of association with lymphatic markers, and generally larger, more loosely packed lesional vessels. Kaposi sarcoma differs in its lack of tufting, presence of a plasma cell infiltrate, and prominence of fascicles of spindle cells forming slit-like spaces. KHE, although overlapping in histology and likely synonymous in pathogenesis, is traditionally described as a more bulky, deeply seated lesion that tends to infiltrate across multiple tissue planes and has more prominent spindled endothelial cells38.

Pathology

Treatment

Tufted angiomas, as originally described in the dermatology literature, are characterized by multiple discrete lobules of capillaries set within the dermis and often the subcutis in a so-called “cannonball” pattern (Fig. 114.14). Borders of the area of tissue involvement are poorly defined. The dermal collagen and subcutis separating capillary lobules may be histologically normal, but are often fibrotic. The lobules are composed of tiny capillaries with pinpoint lumina, occasionally containing fibrin microthrombi, that are tightly packed together without intervening stroma and frequently bulge into peripherally placed thin-walled vessels (Fig. 114.14, inset). Mitotic figures are rare. Endothelial cells may be focally spindled, but less prominently than in KHE. The sweeping spindled cell fascicles and epithelioid nodules of

Complete surgical excision is the treatment of choice for small tufted angiomas, but recurrence is common. Use of the pulsed dye laser has been ineffective40,44, although the argon tunable dye laser with its higher risk of scarring has been used successfully. Both aggravation and improvement have been reported with the Nd:YAG laser. Historically, high-dose systemic corticosteroids were sometimes employed45, even though they are generally ineffective. Interferon-α may produce partial regression, but its use has declined given the risk of permanent spastic diplegia in infants (see Ch. 103)44. For patients with tufted angioma/ KHE who develop Kasabach–Merritt phenomenon, first-line therapy consists of vincristine plus prednisone46 or sirolimus (rapamycin)47. Aspirin may also help to control the platelet interaction, pain, and growth of tufted angiomas40.

Tufted angioma and KHE have a significant degree of overlap in histologic features, with resection specimens of KHE often demonstrating dermal changes that would have been interpreted in small biopsy specimens as tufted angioma. In light of the virtually exclusive association of these two entities with Kasabach–Merritt phenomenon, this histologic overlap suggests that tufted angioma may represent a more superficial, milder form of KHE (see KHE section for further discussion of pathogenesis)33,36–38.

Clinical features

CHAPTER

114 Vascular Neoplasms and Neoplastic-Like Proliferations

Epidemiology

Fig. 114.13 Tufted angioma. A Mottled red patches and superimposed papules are typical clinical features. B Pink-red to violet plaque in an   infant that is broken up into smaller papules.    

B, Courtesy, Julie V. Schaffer, MD.

A

Fig. 114.14 Histology of tufted angioma. Within the dermis, there is typically a cannonball distribution of dense capillary lobules (inset). Courtesy, Luis Requena,  

B

MD.

2029

SECTION

NEOPLASMS OF THE SKIN

18

Glomeruloid Hemangioma Key features ■ A histologically distinct type of hemangioma that occurs in patients with POEMS syndrome ■ In POEMS syndrome, presents as multiple, firm, angiomatous papules or plaques scattered primarily on the trunk and proximal extremities ■ Characterized histologically by nests of capillaries within dilated dermal vessels, resembling renal glomeruli ■ May be induced by increased circulating levels of VEGF

Introduction and history The term glomeruloid hemangioma was coined by Chan et al.48 in 1990 to describe a distinctive vascular proliferation that occurs in patients with POEMS syndrome (polyneuropathy, organomegaly, endocrinopathy, monoclonal gammopathy, and skin lesions). Although the majority of patients with POEMS syndrome have an underlying plasma cell dyscrasia, this lesion occurs more commonly in those with multicentric Castleman disease. There is some overlap with reactive angioendotheliomatosis, but glomeruloid hemangioma is discussed separately because of its highly distinctive histologic features and well-recognized clinical association.

Clinical features The reported incidences of angiomas in patients with POEMS syndrome range from 25% to 45%. These appear as multiple, firm, domeshaped, red to purple papules or plaques ranging in diameter from a few millimeters to a few centimeters; they are scattered predominantly over the trunk and proximal extremities (see Ch. 53). Additional cutaneous manifestations of POEMS syndrome are outlined in Table 114.2,

POEMS SYNDROME – CLINICAL CRITERIA, CUTANEOUS FINDINGS AND ASSOCIATED VASCULAR LESIONS

Diagnostic criteria Monoclonal plasmaproliferative disorder – and – Sensorimotor polyneuropathy plus at least one other major criterion and one minor criterion Major criteria

as are the types of vascular lesions that occur in these patients. True glomeruloid hemangiomas appear to be fairly specific for POEMS syndrome, and rarely they may appear years prior to recognition of the syndrome49. In addition, there are reports of a solitary variant that is not associated with POEMS syndrome.

Pathogenesis Glomeruloid hemangiomas are thought to be reactive, rather than neoplastic. Patients with POEMS syndrome often have increased circulating levels of VEGF50 such that this elevation represents a major diagnostic criterion (see Table 114.2). Most cases of POEMS syndrome associated with multicentric Castleman disease (~90%) have evidence of human herpesvirus-8 (HHV-8) infection by PCR. It is suspected that viral interleukin (IL)-6 produced by the HHV-8 may indirectly promote angiogenesis by inducing VEGF expression51.

Pathology Most of the angiomas seen in patients with POEMS syndrome are found upon histologic examination to be consistent with common cherry angiomas, with numerous dilated dermal capillaries lined by flattened endothelial cells (see above). Only a few demonstrate the distinctive features of glomeruloid hemangioma. These consist of dilated dermal vessels filled by small, well-formed capillary loops that lead to structures reminiscent of renal glomeruli (Fig. 114.15). The capillaries comprising these glomeruloid formations are lined by flat endothelial cells surrounded by an outer layer of pericytes and are separated by a scant stroma containing large cells with lightly eosinophilic cytoplasm and multiple eosinophilic globules. The latter are PAS-positive, diastase-resistant, and immunopositive for polytypic immunoglobulin, presumably derived from the associated paraprotein48. Of note, these interstitial, immunoglobulin-containing cells are of endothelial derivation. Lastly, since many POEMS syndrome patients have both cherry angiomas and glomeruloid hemangiomas, and the cherry angiomas may display focal glomeruloid formation, it is likely that these two histologic subsets reflect different stages of the same process48.

Differential diagnosis The clinical differential diagnosis includes other vascular proliferations and tumors (see Table 114.1) while the histologic differential diagnosis of glomeruloid hemangioma is essentially that described above for reactive angioendotheliomatosis. A more recently described entity, papillary hemangioma, also enters the histologic differential diagnosis52. The latter is characterized by intravascular papillary growths of capillaries,

Sclerotic bone lesions Castleman disease • Increased circulating levels of VEGF • •

Minor criteria Extravascular volume overload (peripheral edema, pleural effusions, ascites) • Thrombocytosis or polycythemia • Papilledema • Organomegaly (hepatosplenomegaly) or lymphadenopathy • Endocrinopathy (e.g. adrenal, pituitary, gonadal, parathyroid) • Skin changes (characteristic) •

Cutaneous findings More common: diffuse hyperpigmentation, induration, hypertrichosis, hyperhidrosis • Less common: clubbing, livedo reticularis, acrocyanosis, flushing, acquired facial lipoatrophy, leukonychia •

Types of vascular lesions Cherry hemangiomas Glomeruloid hemangiomas • Other: reactive angioendotheliomatosis, intravascular papillary endothelial hyperplasia, lobular capillary hemangiomas, microvenular hemangiomas • •

Table 114.2 POEMS syndrome – clinical criteria, cutaneous findings and associated vascular lesions. Patients with AESOP (adenopathy and extensive skin patch overlying a plasmacytoma) syndrome may fulfill the criteria for POEMS syndrome. VEGF, vascular endothelial growth factor.  

2030

Fig. 114.15 Histology of a glomeruloid hemangioma in a patient with POEMS syndrome. Dilated dermal vessels are filled with congeries of small capillaries reminiscent of renal  

Treatment Treatment is not required, although shave excision, cryosurgery, electrodesiccation, or pulsed dye laser surgery will remove the vascular tumors.

Microvenular Hemangioma Synonym:  ■ Microcapillary hemangioma

Differential diagnosis The major histologic differential diagnostic consideration for these acquired lesions is patch-stage Kaposi sarcoma. Kaposi sarcoma differs by the presence of delicate lymphatic-like vessels, plasma cells, eosinophilic globules, interstitial fascicles of spindle cells, and positivity for HHV-8.

Treatment Surgical excision has been effective in reported cases.

Epithelioid Hemangioma Synonyms:  ■ Angiolymphoid hyperplasia with eosinophilia (AHE) Pseudopyogenic granuloma ■ Inflammatory angiomatous nodule Papular angioplasia ■ Inflammatory arteriovenous hemangioma ■ Intravenous atypical vascular proliferation ■ Nodular angioblastic hyperplasia with eosinophilia and lymphofolliculosis ■ Histiocytoid hemangioma ■ ■

Key features ■ An uncommon, acquired, slowly growing, benign vascular tumor of young to middle-aged adults ■ Presents as a small, usually solitary, sharply circumscribed red papulonodule or plaque on the trunk or extremities, with a predilection for the forearms ■ Consists of small branching capillaries and venules with collapsed lumina and conspicuous pericytes infiltrating the full thickness of the reticular dermis ■ May be subject to hormonal influences in some women

Introduction and history Microvenular hemangioma was first described by that name in 1991 by Hunt, Santa Cruz and Barr53, although cases reported as microcapillary hemangiomas are probably identical.

Epidemiology

■ Benign angiomatous nodules or plaques, often multiple and grouped; usually located in the head and neck region, especially around the ears ■ May be painful, pruritic or pulsatile, and often recur after excision ■ Characterized histologically by proliferations of capillary-sized vessels with epithelioid endothelial cells surrounding larger, thick-walled vessels, accompanied by eosinophils and lymphocytes ■ Associated with arteriovenous shunts and sometimes trauma ■ Kimura disease now thought to be a separate clinicopathological entity

Introduction and history Epithelioid hemangioma was initially described as angiolymphoid hyperplasia with eosinophilia (AHE) in 1969 by Wells and Whimster and subsequently referred to as histiocytoid hemangioma54,55. Although originally thought to be a late stage of Kimura disease, it is now generally accepted that these represent two separate entities56.

Pathogenesis

Epidemiology

Microvenular hemangiomas have been noted in patients with POEMS syndrome29, suggesting that these lesions, like glomeruloid hemangiomas, may be of reactive etiology. Observations that some microvenular hemangiomas affecting women present in association with pregnancy or oral contraceptive use arguably suggest a hormonal influence.

Epithelioid hemangioma occurs in young to middle-aged adults without gender or ethnic predilection. Previous reports of a female predominance are not supported by more recent series. A history of trauma can be elicited in some patients57.

Microvenular hemangioma typically presents as a solitary, purple to red, slowly enlarging papule, plaque or small nodule on the trunk or extremities (rarely the face). Multiple lesions have occasionally been observed. There appears to be a particular predilection for the forearms, and most lesions are 3 months of age77, should include magnetic resonance imaging (MRI), a complete blood cell count, coagulation studies to detect coexistent KMP, and, if not prohibited by severe thrombocytopenia, biopsy for histopathologic diagnosis. By MRI, KHE is usually

Introduction and history Kaposiform hemangioendothelioma (KHE) was described as such by Zukerberg et al.37 in 1993, although equivalent lesions had been previously reported as “hemangioma with Kaposi’s sarcoma-like features”75 and “Kaposi-like infantile hemangioendothelioma”76. Many lesions of this type were previously misdiagnosed as infantile hemangioma.

Epidemiology Most tumors present in children 2 cm but ≤5 cm T3, primary tumor >5 cm T4, primary tumor invades fascia, muscle, cartilage, or bone

cNx, regional lymph nodes cannot be clinically assessed (e.g. previously removed for another reason, body habitus) cN0, no regional lymph node metastasis by clinical or radiological evaluation cN1, clinically detected regional nodal metastasis cN2, in-transit metastasis without lymph node metastasis cN3, in-transit metastasis with lymph node metastasis

M pNx, regional lymph nodes cannot be assessed (e.g. previously removed for another reason) or not removed for pathological evaluation pN0, no regional lymph node metastasis detected on pathological evaluation pNIa(sn), clinically occult nodal metastasis identified only by sentinel lymph node biopsy pNIa, clinically occult regional lymph node metastasis following lymph node dissection pNib, clinically or radiologically detected regional lymph node metastasis, pathologically confirmed pN2, in-transit metastasis without lymph node metastasis pN3, in-transit metastasis with lymph node metastasis

M0, no distant metastasis Ml, distant metastasis MIa, metastasis to distant skin, distant subcutaneous tissue, or distant lymph nodes Mlb, metastasis to lung Mlc, metastasis to all other distant sites

*†Clinical staging is defined by microstaging of the primary Merkel cell carcinoma (MCC) with clinical and/or radiological evaluation for metastasis.

Pathological staging is defined by microstaging of the primary MCC and pathological nodal evaluation of the regional lymph node basin with sentinel lymph node biopsy or complete lymphadenectomy or pathologic confirmation of distant metastasis.

Table 115.6 Merkel cell carcinoma – 8th AJCC staging system. From Harms KL, Healy MA, Nghiem P, et al. Analysis of prognostic factors from 9387 Merkel cell carcinoma cases forms the basis for  

the new 8th edition AJCC staging system. Ann Surg Oncol. 2016;23:3564–71.

in high load within normal skin. For prognostication, increased p63 expression may portend a clinically aggressive behavior76, and a sheetlike pattern of nodal involvement may be associated with poorer overall survival. Merkel cell carcinomas negative for CK20 and for Merkel cell polyomavirus seem to have a more aggressive behavior70a,76a.

Differential Diagnosis Common clinical diagnoses are BCC, SCC, amelanotic melanoma, and adnexal tumor. Due to the violaceous, sometimes hemorrhagic, appearance of some tumors, the differential diagnosis also includes pyogenic granuloma, abscess, angiosarcoma, and lymphoma. Histologically, there is a broad spectrum of small, round, blue cell tumors of diverse histogenesis that can be confused with PNECS73. These include metastatic neuroendocrine carcinoma of the lung (small cell or oat cell carcinoma), poorly differentiated eccrine carcinoma, lymphoma, metastatic neuroblastoma, primary peripheral primitive neuroectodermal tumor, Ewing sarcoma, melanoma, and poorly differentiated SCC72,73.

Treatment

2062

Surgery is the primary approach and sentinel lymph node biopsy (SLNB) has been recommended to assist in treatment decisions and for prognosis77,78 (Fig. 115.19). As in melanoma, there is a false negative rate with SLNB and in one review of SLNB in patients with Merkel cell carcinoma, the rate was 17%79.

Due to the aggressive nature of this tumor, adjuvant chemotherapy and radiation therapy (RT) have often been administered80. In a recent analysis, patients with localized disease (stages I and II) had a significantly better overall survival with surgery plus adjuvant RT as compared to surgery alone, but in those with nodal metastases (stage III), neither adjuvant RT nor chemotherapy improved overall survival81. Additionally, in the setting of a negative SLNB, adjuvant regional RT was found to have no effect on regional recurrence79. In a phase II trial of the anti-PD-1 antibody pembrolizumab (2 mg/ kg every 3 weeks) in patients with advanced Merkel cell carcinoma, an objective response rate (RR) of 56% was observed; the RR was 62% in virus-positive tumors and 44% in virus-negative tumors82,82a. In 2017, avelumab, an anti-PD-L1 antibody (see Fig. 128.9), was approved by the FDA for the treatment of Merkel cell carcinoma.

HETEROTOPIC NEURAL TISSUE OF THE SKIN These rare lesions develop from embryologically misplaced neural tissue within the skin.

Heterotopic Neuroglial Tissue Synonyms:  ■ Nasal glioma ■ Brain-like heterotopia ■ Glial hamartoma

■ ■ ■ ■

Rare, benign, congenital lesion Most common near the root of the nose, but can be intranasal Solitary, firm, smooth, skin-colored to red–purple papulonodule Microscopically, lobulated neuroglial tissue

The term “nasal glioma” was introduced by Schmidt in 1900.

Epidemiology These tumors are rare and usually manifest at the time of birth.

Pathogenesis A nasal glioma is the result of embryologic displacement of brain tissue, usually along the cranial closure lines and without apparent communication with underlying structures83. It has a predilection for the perinasal area; therefore, it is commonly referred to as a nasal glioma. As this is not a true neoplasm, the term is misleading84.

Clinical features Nasal gliomas are firm, smooth-surfaced, skin-colored to red–violet papulonodules that may have obvious telangiectasias and range in size from 1 to 3 cm. Approximately 60% are located on the bridge of the nose (Fig. 115.20), with the remainder usually located intranasally or in both locations84,85.

Pathology In a nasal glioma, an ill-defined, non-encapsulated neuropil-like mass is seen within the dermis and subcutis. The neuropil-like tissue is composed of nests and strands of pale-staining, finely vacuolated or fibrillary matrix in which various types of astrocytes can be found83. Gemistocytic astrocytes, with polygonal, eosinophilic cytoplasm and eccentric nuclei, as well as multinucleated giant cells, are relatively common. Mature neurons are present in variable numbers84. Occasionally, residual meningoendothelial cells, ependymal cells, choroid plexuslike structures, and pigmented cells can be identified85. No mitotic activity or aggressive growth pattern has been described.

$

CHAPTER

115 Neural and Neuroendocrine Neoplasms (Other than Neurofibromatosis)

Key features

History

Differential diagnosis Clinically, the lesion must be differentiated from other facial midline lesions (see Ch. 64)84,86 as well as an infantile hemangioma, dermoid cyst, and nasal polyp (see Table 64.1).

Treatment Most cutaneous neural malformations can be effectively treated by excision. Cranial imaging is recommended before these lesions are biopsied or removed87, because nasal gliomas can communicate with the intracranial space, and therefore cerebrospinal fluid leakage and subsequent meningoencephalitis and other neurologic damage may occur after biopsy84.

%

Heterotopic Meningeal Tissue Synonym:  ■ Rudimentary meningocele

Key features ■ Rare disorder that usually presents in neonates and infants and favors the scalp, forehead, and dorsal midline ■ Soft to firm, skin-colored nodule, often with partial alopecia and/or the “hair collar” sign when on the scalp ■ Can be associated with other developmental anomalies ■ Histologically, solid nests and strands, whorls of epithelioid or spindle cells, and psammoma bodies &

History

Fig. 115.18 Primary neuroendocrine carcinoma of the skin (Merkel cell carcinoma). A Nodular infiltrate of basaloid cells with focally small “trabecular” structures within the entire dermis and superficial subcutis. B Small, round to ovoid basaloid cells with vesicular nuclei and small nucleoli; note several necrotic (apoptotic) cells and a mitotic figure (arrow). C Immunohistochemical stain for cytokeratin 20 demonstrates a characteristic perinuclear dot pattern.  

Courtesy, Lorenzo Cerroni, MD.

The concept of rudimentary meningocele was introduced by Lopez et al.88.

Epidemiology Meningeal heterotopias are rare lesions, usually apparent at or shortly after birth88.

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SECTION

18 Neoplasms of the Skin

PRIMARY CUTANEOUS MERKEL CELL CARCINOMA (MCC): SIMPLIFIED EVALUATION AND TREATMENT

• See NCCN guidelines and www.merkelcell.org/ for further information, including surveillance guidance

Biopsy of primary lesion shows MCC#

Baseline imaging studies in most patients

*

**

Nodes clinically negative

Nodes clinically positive

Sentinel lymph node biopsy (SLNB) and excision of primary site

SLNB negative

Fine needle aspiration, core biopsy, or excisional biopsy of lymph node^^ plus excision of primary site

SLNB positive

***

Radiotherapy to primary site ± draining lymph node basin^

Positive lymph node

Negative lymph node

Consider PET-CT or CT scan of chest, abdomen and pelvis if not already performed

Scan negative

#

Consider baseline Merkel cell polyomavirus serology for prognostic significance and to track disease No pathologically enlarged nodes on physical examination and by imaging study Pathologically enlarged nodes on physical examination or by imaging study Radiotherapy is indicated in most patients (usually 40–50 Gy); the exception is for low-risk disease, e.g. primary ≤1 cm and site an extremity or trunk, no lymphovascular invasion, negative surgical margins, and patient not immunosuppressed ^ Consider radiation therapy to the nodal basin in highrisk patients ^^ Consider excisional biopsy primarily or after negative needle/core biopsy to exclude false-negative biopsy result

* ** ***

Scan positive for distant disease

Radiotherapy to primary site Completion lymphadenectomy and/or radiotherapy to draining lymph node basin

• Clinical trial preferred, if available • Immune checkpoint inhibitors, e.g. anti-PD-1 or -PD-L1 antibody (avelumab), if immunocompetent and no active • autoimmune disease Consider the following therapies alone or in combination: Radiation Surgery Chemotherapy, e.g. etoposide + carboplatin; pazopanib and octreotide useful alternatives

***

to Radiotherapy primary site ± draining lymph node basin^

Fig. 115.19 Primary cutaneous Merkel cell carcinoma (MCC): simplified evaluation and treatment algorithm. NCCN, National Comprehensive Cancer Network; PET, positron emission tomography. Courtesy, Paul Nghiem, MD PhD. Based upon: Gupta SG, Wang LC, Penas PF, et al. Sentinel lymph node biopsy for evaluation and treatment of patients with Merkel cell  

carcinoma: The Dana-Farber experience and meta-analysis of the literature. Arch Dermatol. 2006;142:685–90.

Fig. 115.20 Nasal glioma in a newborn. Pink to violet soft  

Pathogenesis Rudimentary meningoceles are thought to result from herniation of the meningeal lining into the skin and subcutaneous tissues during embryologic development, usually with no residual communication with the CNS (see Ch. 64)89. Although these lesions are sometimes classified as type I cutaneous meningiomas88, considering their non-neoplastic nature, they are better classified as rudimentary meningoceles89.

Clinical features Rudimentary meningoceles most commonly present on the scalp of neonates and infants at the sites of cranial closure. Less often they occur on the forehead (midline) or overlie the spine. Skin-colored papules or nodules on the scalp are often associated with alopecia and/ or the “hair collar” sign90.

Pathology 2064

A rudimentary meningocele is an ill-defined mass of cavernous, pseudovascular spaces embedded in a markedly collagenous stroma89,91. The spaces may be lined by elongated meningoendothelial cells characterized by eosinophilic cytoplasm, round or ovoid nuclei, and a fine

Differential diagnosis In neonates and infants, rudimentary meningoceles must be distinguished from “atretic” meningoceles (an intermediate form with an intracranial connection), membranous aplasia cutis congenita, heterotopic brain tissue, dermoid cysts, and infantile hemangiomas. Histologically, the differential diagnosis includes type II and type III meningiomas which usually develop on the scalp of adults, either along the course of a cranial nerve (type II) or as a cutaneous “metastasis” or direct extension of a primary meningioma of the arachnoid lining (type III)88,90,92. Within the deep dermis or subcutis, there is a multinodular mass, often with an infiltrative growth pattern93–95. The cells may show a variable degree of differentiation, and in the most common form, the spindle cells have a concentric, whorl-like arrangement93; psammoma bodies are often present93–95. Mitotic figures are rare in type II and variably increased in type III. Clinically, these nodular tumors may have associated alopecia and can resemble an epidermoid or pilar cyst, adnexal tumor or cutaneous metastasis. They may occur in the setting of neurofibromatosis (types I and II)96.

Treatment As with heterotopic neuroglial tissue (nasal glioma), imaging studies are required prior to biopsy or excision. The latter is performed primarily by neurosurgeons.

PRIMITIVE NEUROECTODERMAL TUMORS Synonyms:  ■ Neuroblastoma (primary or metastatic) ■

Neuroepithelioma ■ Ganglioneuroma

Key features ■ The third most common malignant neoplasm in children ■ Cutaneous metastases (children) are seen more frequently than primary cutaneous tumors (adults) ■ Cutaneous metastases present as multiple, blue to purple dermal nodules in association with elevated serum and urine catecholamines ■ Histologically, small, round, blue cells in a nested or infiltrative growth pattern, with formation of Homer Wright rosettes ■ Prognosis depends on the patient’s age, clinical stage, and specific genetic abnormalities (e.g. MYCN oncogene amplification)

Epidemiology Neuroblastoma is the third most commonly observed childhood malignancy, and cutaneous metastases are frequent3. Most neuroblastomas develop as sporadic tumors, although familial cases have been reported. Primary cutaneous PNETs are tumors of adulthood (mean age, 40 years) and are exceedingly rare3.

Pathogenesis PNETs of the skin either represent metastases from a PNET of the adrenals and/or ganglionic chain (traditionally designated as neuroblastomas) or develop de novo from heterotopic neural crest cells3. In the latter case, they are referred to as peripheral PNETs or as peripheral neuroblastomas. More recently, studies have implicated the anaplastic lymphoma kinase gene in the tumorigenesis of many familial and some sporadic cases of neuroblastoma. In addition, DNA ploidy and specific genetic abnormalities, such as MYCN oncogene amplification or aberrations of chromosomes 11q or 1p, influence prognosis99.

Clinical Features In children, the cutaneous metastases of neuroblastoma often manifest as multiple, blue to purple, dermal papules or nodules that resemble the “blueberry muffin” lesions seen with congenital infections or hematologic disorders4 (see Ch. 121). These nodules may blanch upon stroking and develop an erythematous halo100,101. Serum and urine catecholamine levels are typically elevated. In children, complete spontaneous regression has been described in stage IV-S neuroblastoma, including cutaneous metastases102. In adults, PNETs are rapidly growing dermal or subcutaneous nodules that favor the trunk or head. Ulceration is common. These highly aggressive neoplasms have an almost invariably fatal outcome102a.

CHAPTER

115 Neural and Neuroendocrine Neoplasms (Other than Neurofibromatosis)

chromatin pattern. Similar cells dissect or wrap around collagen fibers, producing “collagen bodies”. No significant cytologic atypia or mitotic activity is present. Focal calcification and psammoma bodies (eosinophilic laminated and whorled structures with variable calcification) may occur.

Pathology In metastatic neuroblastoma, an ill-defined or infiltrative mass is present in the dermis and/or the subcutis. However, when smaller and more superficial, deposits are more defined. The tumor mass is composed of atypical, small, dark cells with scant cytoplasm3,97. The cells have larger nuclei than mature lymphocytes (with a coarse chromatin pattern) and they form irregular nests, cords, or poorly cohesive sheets. Rosette formation, by concentrically arranged tumor cells in double or multiple circles, is common. The center of the rosettes contains converging fine fibrillary material characteristic of Homer Wright-type rosettes3 (Fig. 115.21). Mitotic activity is high, and abnormal mitoses are abundant. Extensive areas of necrosis and hemorrhage are common.

Introduction Neuroblastic–ganglionic tumors are derived from the germinal neuroepithelium and/or from the neural crest. They display a wide spectrum of clinicopathologic features based on their relative degree of differentiation, ranging from very primitive neuroectodermal tumors to more mature forms such as neuroblastomas.

History The concept of neuroectodermal tumors was introduced by Stout in 1918. Since then, different terms have been used for tumors with cytologically similar features, reflecting the controversy regarding this entity. Dehner performed a comprehensive review of the nosology of this diverse group of lesions, suggesting the term “primitive neuroectodermal tumors” (PNET)97. This concept was then further expanded following the recognition that PNET and extraosseous Ewing sarcoma can have similar immunohistochemical and chromosomal abnormalities (e.g. translocations involving EWSR1), and therefore nowadays they are considered within the same neoplastic spectrum98.

Fig. 115.21 Cutaneous neuroblastoma. The tumor is composed of small cells with small, round to ovoid nuclei that can be arranged in rosettes. The fibrillary material in the center of Homer Wright-type rosettes is characteristic. In the upper mid-portion of the figure there is a large area of necrosis. Courtesy, Lorenzo  

Cerroni, MD.

2065

SECTION

Neoplasms of the Skin

18

As the tumor differentiates, the relative proportion of neuroblastoma components decreases, and the ganglioneuromatous elements increase. Eventually, the tumor may become a ganglioneuroma102. Immunohistochemically, the cells react variably with neural and neuroendocrine markers, depending on their state of differentiation. These markers include neuron-specific enolase, S100 protein, neurofilaments, synaptophysin, chromogranin, and CD99 (see Ch. 0)99. Primary cutaneous PNETs have similar histopathologic features to those of the classic neuroblastoma, but ganglionic or neuromatous differentiation is not characteristic. These two tumors also share major immunohistochemical features. However, MIC-2(013) is commonly expressed by PNETs, but not by neuroblastomas, facilitating their distinction99,103–105.

Differential Diagnosis In children, the clinical differential diagnosis includes other types of cutaneous metastasis, extramedullary hematopoiesis, and mastocytosis, whereas in adults it includes adnexal tumors, lymphoma, and soft

tissue sarcomas. Histologically, both metastatic neuroblastoma and primary cutaneous PNET must be differentiated from other small, round, blue cell tumors that form rosettes and may involve the skin104,105 (see Merkel cell carcinoma).

Treatment The effective treatment of neuroblastoma requires an interdisciplinary team that includes oncologists, surgeons, and radiation therapists. The overall prognosis of localized tumor involvement has improved with combined surgical excision, multiagent chemotherapy, differentiating agents (e.g. 13-cis-retinoic acid), immunotherapy (e.g. dinutuximab), hematopoietic stem cell transplantation, and radiopharmaceuticals99. Important prognostic factors include the age, stage, histologic differentiation, specific genetic abnormalities (e.g. MYCN oncogene amplification, 11q aberration), and response to initial chemotherapy3. For a table on tumors and tumor-like conditions of ectopic and hetero­ topic neural tissue involving the skin visit www.expertconsult.com

REFERENCES

2066

1. Argenyi ZB. Recent developments in cutaneous neural neoplasms. J Cutan Pathol 1993;20:97–108. 2. Scheithauer BW, Woodruff JM, Erlandson RA. Tumors of the peripheral nervous system. In: Atlas of Tumor Pathology, 3rd series, Fascicle 24. Washington, DC: Armed Forces Institute of Pathology; 1999. p. 1–415. 3. Enzinger FM, Weiss SW. Benign tumors of peripheral nerves. In: Soft Tissue Tumors. 4th ed. St. Louis: Mosby; 2001. p. 1111–207. 4. Reed RJ, Fine RM, Meltzer HD. Palisaded, encapsulated neuromas of the skin. Arch Dermatol 1972;106:865–70. 5. Lundborg G. Nerve regeneration and repair: a review. Acta Orthop Scand 1987;58:145–69. 6. Argenyi ZB, Santa Cruz D, Bromley C. Comparative light-microscopic and immunohistochemical study of traumatic and palisaded, encapsulated neuromas of the skin. Am J Dermatopathol 1992;14:504–10. 7. Matthews GJ, Osterholm JL. Painful traumatic neuromas. Surg Clin North Am 1972;51:1313–24. 8. Burtner DD, Goodman M. Traumatic neuroma of the nose. Arch Otolaryngol 1972;103:108–9. 9. Shapiro L, Juklin EA, Brownstein HM. Rudimentary polydactyly. Arch Dermatol 1973;108:223–5. 10. Dakin MC, Leppard B, Theaker JM. The palisaded, encapsulated neuroma (solitary circumscribed neuroma). Histopathology 1992;20:405–10. 11. Argenyi ZB. Immunohistochemical characterization of palisaded encapsulated neuroma. J Cutan Pathol 1990;17:329–35. 12. Argenyi ZB, Cooper PH, Santa Cuz D. Plexiform and other unusual variants of palisaded encapsulated neuroma. J Cutan Pathol 1993;20:34–9. 13. Argenyi ZB. Newly recognized neural neoplasms relevant to the dermatopathologist. Dermatol Clin 1992;10:219–34. 14. Requena L, Grosshans E, Kutzner H, et al. Epithelial sheath neuroma; a new entity. Am J Surg Pathol 2000;24:190–6. 15. Stout AP. The peripheral manifestations of specific nerve sheath tumor (neurilemoma). Am J Cancer 1935;24:751–96. 16. Izumi AK, Rosato FE, Wood MG. Von Recklinghausen’s disease associated with multiple neurilemomas. Arch Dermatol 1971;104:172–6. 17. Shishiba T, Niimura M, Ohtsuka F, et al. Multiple cutaneous neurilemomas as a skin manifestation of neurilemmomatosis. J Am Acad Dermatol 1984;10:744–54. 18. Purcell SM, Dixon SL. Schwannomatosis: an unusual variant of neurofibromatosis or a distinct clinical entity? Arch Dermatol 1989;125:390–3. 19. Reith JD, Goldblum JR. Multiple cutaneous plexiform schwannomas: report of a case and review of the literature with particular reference to the association with types 1 and 2 neurofibromatosis and schwannomatosis. Arch Pathol Lab Med 1996;120:399–401. 20. Hulsebos TJM, Plomp AS, Wolterman RA, et al. Germline mutations of INII/SMARCB1 in familial schwannomatosis. Am J Hum Genet 2007;80:805–10. 21. Sainz J, Huynh PD, Figueroa K, et al. Mutations of the neurofibromatosis type 2 gene and lack of the gene

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product in vestibular schwannomas. Hum Mol Genet 1994;3:885–91. Begnami MD, Palau M, Rushing EJ, et al. Evaluation of NF2 gene deletion in sporadic schwannomas, meningiomas, and ependymomas by chromogenic in situ hybridization. Hum Pathol 2007;38:1345–50. Das Gupta TK, Brasfield RD, Strong EW, et al. Benign solitary schwannomas (neurilemomas). Cancer 1969;24:355–66. Whitaker WG, Droulias C. Benign encapsulated neurilemoma: a report of 76 cases. Am Surg 1976;42:675–8. Jacobs RL, Barmada R. Neurilemoma: a review of the literature with six case reports. Arch Surg 1971;102:181–6. Vilanova JR, Burgos-Bretones JJ, Alvarez JA, et al. Benign schwannomas: a histopathological and morphometric study. Pathology 1982;137:281–6. Dahl I, Hagmar B, Idvall I. Benign solitary neurilemoma (schwannoma): a correlative cytological and histological study of 28 cases. Acta Pathol Microbiol Immunol Scand A 1984;92:91–101. Argenyi ZB, Balogh K, Abraham AA. Degenerative (“ancient”) changes in benign cutaneous schwannoma: a light microscopic, histochemical and immunohistochemical study. J Cutan Pathol 1993;20:148–53. Berg JC, Schethauer BW, Spinner RJ, et al. Plexiform schwannoma: a clinicopathologic overview with emphasis on the head and neck region. Hum Pathol 2008;39:633–40. Kao GF, Laskin WB, Olsen TG. Solitary cutaneous plexiform neurilemmoma (schwannoma): a clinicopathologic, immunohistochemical and ultrastructural study of 11 cases. Mod Pathol 1986;2:20–6. Argenyi ZB, Goodenberger ME, Strauss JS. Congenital neural hamartoma (“fascicular schwannoma”): a light microscopic, immunohistochemical, and ultrastructural study. Am J Dermatopathol 1990;12:283–93. Woodruff JM, Susin M, Godwin TA, et al. Cellular schwannoma: a variety of schwannoma sometimes mistaken for a malignant tumor. Am J Surg Pathol 1981;5:733–44. Carney JA. Psammomatous melanotic schwannoma. A distinctive, heritable tumor with specific associations, including cardiac myxoma and the Cushing syndrome. Am J Surg Pathol 1990;14:206–22. Riccardi VM. Neurofibromatosis: the importance of localized or otherwise atypical forms. Arch Dermatol 1987;123:882–3. Lassmann H, Jurecka W, Lassmann W, et al. Different types of benign nerve sheath tumors: light microscopy, electron microscopy, and autoradiography. Virchows Arch A Pathol Anat Histol 1977;375:197–210. Megahed M. Histopathological variants of neurofibroma. A study of 114 lesions. Am J Dermatopathol 1994;16:486–95. Lin BT, Weiss LM, Medeiros LJ. Neurofibroma and cellular neurofibroma with atypia: a report of 14 tumors. Am J Surg Pathol 1997;21:1443–9.

38. Argenyi ZB, LeBoit PE, Santa Cruz D, et al. Nerve sheath myxoma (neurothekeoma) of the skin: light microscopic and immunohistochemical reappraisal of the cellular variant. J Cutan Pathol 1993;20:294–303. 39. Argenyi ZB, Kutzner H, Seaba MM. Ultrastructural spectrum of cutaneous nerve sheath myxoma/cellular neurothekeoma. J Cutan Pathol 1995;22:137–45. 40. Fetsch JF, Laskin WB, Hallman JR, et al. Neurothekeoma: an analysis of 178 tumors with detailed immunohistochemical data and long-term patient follow-up information. Am J Surg Pathol 2007;31:1103–14. 41. Angervall L, Kindblom LG, Haglid K. Dermal nerve sheath myxoma. A light and electron microscopic, histochemical and immunohistochemical study. Cancer 1984;53:1752–9. 42. Aronson PJ, Fretzin DF, Potter BS. Neurothekeoma of Gallagher and Helwig (dermal nerve sheath myxoma variant): report of a case with electron microscopic and immunohistochemical studies. J Cutan Pathol 1985;12:506–19. 43. Barnhill RL, Mihm MC Jr. Cellular neurothekeoma. A distinctive variant of neurothekeoma mimicking nevomelanocytic tumors. Am J Surg Pathol 1990;14:113–20. 44. Barnhill RL, Dickersin GR, Nickeleit V, et al. Studies on the cellular origin of neurothekeoma: clinical, light microscopic, immunohistochemical and ultrastructural observations. J Am Acad Dermatol 1991;25:80–8. 45. Hornick JL, Fletcher CD. Cellular neurothekeoma: detailed characterization in a series of 133 cases. Am J Surg Pathol 2007;31:329–40. 46. Fletcher CD, Chan JK, McKee PH. Dermal nerve sheath myxoma: a study of three cases. Histopathology 1986;10:135–45. 47. Busam KJ, Mentzel T, Colpaert C, et al. Atypical or worrisome features in cellular neurothekeoma. A study of 10 cases. Am J Surg Pathol 1998;22:1067–  72. 48. Plaza JA, Torres-Cabala C, Evans H, et al. Immunohistochemical expression of S100A6 in cellular neurothekeoma: clinicopathologic and immunohistochemical analysis of 31 cases. Am J Dermatopathol 2009;31:419–22. 49. Abrikossoff A. Myomas originating from transversely striated voluntary musculature. Virchows Arch Pathol Anat 1926;260:215–33. 50. Abenoza P, Sibley RK. Granular cell myoma and schwannoma: fine structural and immunohistochemical study. Ultrastruct Pathol 1987;11:19–28. 51. Bedetti CD, Martinez AJ, Beckford NS, May M. Granular cell tumor arising in myelinated peripheral nerves. Light and electron microscopy and immunoperoxidase study. Virchows Arch 1983;402:175–83. 52. Fisher ER, Wechsler H. Granular cell myoblastoma – a misnomer. Electron-microscopic and histochemical evidence concerning its Schwann cell derivation and nature (granular cell schwannoma). Cancer 1962;15:936–54. 53. Raju GC, O’Reilly AP. Immunohistochemical study of granular cell tumour. Pathology 1987;19:402–6.

Online only content

CHAPTER

Nasal glioma*

Rudimentary meningocele

Cutaneous meningioma (Types II and III)

Peripheral neuroblastoma

Incidence

Rare

Rare

Extremely rare

Extremely rare

Age

Neonates

Neonates or infants

Usually adults

Late adulthood

Location

Most commonly near the root of the nose but can be intranasal

Scalp, forehead, paravertebral area

Scalp

Head and trunk

Size

1.0–3.0 cm

0.5–3.0 cm

0.5–4.0 cm

0.5–5.0 cm

Clinical appearance

Firm, smooth, skin-colored to red–purple nodule

Soft to firm nodule, often with alopecia or the “hair collar” sign; occasionally cystic; blue–red hue common

Soft to firm nodule, often with alopecia

Soft, skin-colored to red, often ulcerated nodule

Clinical differential diagnosis

Infantile hemangioma, nasal polyp, juvenile xanthogranuloma, dermoid cyst

Membranous aplasia cutis, heterotopic brain tissue, dermoid cyst, infantile hemangioma

Epidermoid or pilar cyst, adnexal tumors, cutaneous metastasis

Adnexal tumors, lymphoma, soft tissue sarcoma, cutaneous metastasis

Associations

Intracranial connection in ~20% (“atretic” encephalocele)

An intracranial connection may be present (“atretic” meningocele)

May be associated with neurofibromatosis (types I and II)

NA

Other

NA

NA

Metastasis of CNS meningioma must be excluded

Metastasis of ganglionic or adrenal neuroblastoma and extension of olfactory neuroblastoma must be excluded, especially in children

Histopathologic features

Lobulated neural tissue (glial cells, astrocytes, rarely true neurons)

Cystic or cavernous spaces, scattered meningothelial cells, pseudovascular pattern, psammoma bodies

Solid nests and strands, whorls of epithelioid or spindle cells, psammoma bodies

Rosette-like (Homer Wright-type) structures of small, round, blue cells, extensive infiltration and necrosis

Biologic course

Benign

Benign

Locally aggressive and destructive

Extremely malignant with widespread metastases

115 Neural and Neuroendocrine Neoplasms (Other than Neurofibromatosis)

TUMORS AND TUMOR-LIKE CONDITIONS OF ECTOPIC AND HETEROTOPIC NEURAL TISSUE INVOLVING THE SKIN

*Heterotopic brain tissue can also be located in the midline scalp, orbit, lip, and oropharynx. eTable 115.1 Tumors and tumor-like conditions of ectopic and heterotopic neural tissue involving the skin.  

2066.e1

of Unusual Malignant Cutaneous Tumors. New York: Marcel Dekker; 1985. p. 107–72. 73. Cheuk W, Kwan MY, Suster S, Chan JK. Immunostaining for thyroid transcription factor 1 and cytokeratin 20 aids the distinction of small cell carcinoma from Merkel cell carcinoma, but not pulmonary from extrapulmonary small cell carcinomas. Arch Pathol Lab Med 2001;125:228–31. 74. LeBoit PE, Crutcher WA, Shapiro PE. Pagetoid intraepidermal spread in Merkel cell (primary neuroendocrine) carcinoma of the skin. Am J Surg Pathol 1992;16:584–92. 75. Duncavage EJ, Le BM, Wang D, Pfeifer JD. Merkel cell polyomavirus: a specific marker for Merkel cell carcinoma in histologically similar tumors. Am J Surg Pathol 2009;33:1771–7. 76. Asioli S, Righi A, Volante M, et al. p63 expression as a new prognostic marker in Merkel cell carcinoma. Cancer 2007;110:640–7. 76a.  González-Vela MD, Curiel-Olmo S, Derdak S, et al. Shared oncogenic pathways Implicated in both virus-positive and UV-Induced Merkel cell carcinomas. J Invest Dermatol 2017;137:197–206. 77. Duker I, Starz H, Bachter D, Balda BR. Prognostic and therapeutic implications of sentinel lymphonodectomy and S-staging in Merkel cell carcinoma. Dermatology 2001;202:225–9. 78. Gupta SG, Wang LC, Penas LC, et al. Sentinel lymph node biopsy for evaluation and treatment of patients with Merkel cell carcinoma: the Dana-Farber experience and meta-analysis of the literature. Arch Dermatol 2006;142:771–4. 79. Gunaratne DA, Howle JR, Veness MJ. Sentinel lymph node biopsy in Merkel cell carcinoma: a 15-year institutional experience and statistical analysis of 721 reported cases. Br J Dermatol 2016;174:272–81. 80. Medina-Franco H, Urist MM, Fiveash J, et al. Multimodality treatment of Merkel cell carcinoma: case series and literature review of 1024 cases. Ann Surg Oncol 2001;8:204–8. 81. Bhatia S, Storer BE, Iver JG, et al. Adjuvant radiation therapy and chemotherapy in Merkel cell carcinoma: survival analyses of 6908 cases from the National Cancer Data Base. J Natl Cancer Inst 2016;108. 82. Nghiem PT, Bhatia S, Lipson EJ, et al. PD-1 blockade with pembrolizumab in advanced Merkel-cell carcinoma. N Engl J Med 2016;374:2542–52. 82a.  Hauschild A, Schadendorf D. Checkpoint inhibitors: a new standard of care for advanced Merkel cell carcinoma? Lancet Oncol 2016;17:1337–9. 83. Patterson K, Kapur S, Chandra RS. Nasal gliomas” and related brain heterotopias: a pathologist’s perspective. Pediatr Pathol 1986;5:353–62. 84. Yeoh GPS, Bale PM, de Silva M. Nasal cerebral heterotopia: the so-called nasal glioma or sequestered encephalocele and its variants. Pediatr Pathol 1989;9:531–49. 85. Orkin M, Fisher I. Heterotopic brain tissue (heterotopic neural rest): case report with review of related anomalies. Arch Dermatol 1966;94:699–708. 86. Fletcher CDM, Carpenter G, McKee PH. Nasal glioma: a rarity. Am J Dermatopathol 1986;8:341–6. 87. Kennard CD, Rasmussen JE. Congenital midline nasal masses: diagnosis and management. J Dermatol Surg Oncol 1990;16:1025–36. 88. Lopez DA, Silvers DN, Helwig EB. Cutaneous meningiomas: a clinicopathologic study. Cancer 1974;34:728–44. 89. Sibley DA, Cooper PH. Rudimentary meningocele: a variant of “primary cutaneous meningioma. J Cutan Pathol 1989;16:72–80.

90. Berry AD III, Patterson W. Meningoceles, meningomyeloceles, and encephaloceles: a neuro-dermatopathologic study of 132 cases. J Cutan Pathol 1991;18:164–77. 91. Marrogi AJ, Swanson PE, Kyriakos M, et al. Rudimentary meningocele of the skin: clinicopathologic features and differential diagnosis. J Cutan Pathol 1991;18:178–88. 92. Argenyi ZB. Cutaneous neural heterotopias and related tumors relevant for the dermatopathologist. Semin Diagn Pathol 1996;13:60–71. 93. Nochomovitz LE, Jannotta F, Orenstein JM. Meningioma of the scalp: light and electron microscopic observations. Arch Pathol Lab Med 1985;109:92–5. 94. Theaker JM, Fleming KA. Meningioma of the scalp: a case report with immunohistological features. J Cutan Pathol 1987;14:49–53. 95. Gelli MC, Pasquinelli G, Martinelli G, et al. Cutaneous meningioma: histochemical, immunohistochemical and ultrastructural investigation. Histopathology 1993;23:576–8. 96. Argenyi ZB, Thielberg MD, Hayes CM, Whitaker DC. Primary cutaneous meningioma associated with von Recklinghausen disease. J Cutan Pathol 1994;21:549–56. 97. Dehner LP. Peripheral and central primitive neuroectodermal tumors: a nosologic concept seeking a consensus. Arch Pathol Lab Med 1986;110:997–1005. 98. Dehner LP. Primitive neuroectodermal turmor and Ewing’s sarcoma. Am J Surg Pathol 1993;17:1–13. 99. Mueller S, Matthay KK. Neuroblastoma: biology and staging. Curr Oncol Rep 2009;11:431–8. 100. Shown TE, Durfee MF. Blueberry muffin baby: neonatal neuroblastoma with subcutaneous metastases. J Urol 1970;104:193–5. 101. Hawthorne HC, Nelson JS, Witzelben CL, et al. Blanching subcutaneous nodules in neonatal neuroblastoma. J Pediatr 1970;77:297–300. 102. Ahmed AA, Zhang L, Reddivalla N, Hetherington M. Neuroblastoma in children: Update on clinicopathologic and genetic prognostic factors. Pediatr Hematol Oncol 2017;29:1–21. 102a.  Esiashvili N, Goodman M, Ward K, et al. Neuroblastoma in adults: Incidence and survival analysis based on SEER data. Pediatr Blood Cancer 2007;49:41–6. 103. Argenyi ZB, Bergfeld WF, McMahon JT, et al. Primitive neuroectodermal tumor in the skin with features of neuroblastoma in an adult patient. J Cutan Pathol 1986;13:420–30. 104. Nguyen AV, Argenyi ZB. Cutaneous neuroblastoma: peripheral neuroblastoma. Am J Dermatopathol 1993;15:7–14. 105. Banerjee SS, Agbamu DA, Eyden BP, Harris M. Clinicopathological characteristics of peripheral primitive neuroectodermal tumour of skin and subcutaneous tissue. Histopathology 1997;31:355–66. 106. Macarenco RS, Ellinger F, Oliveira AM. Perineuroma. A distinctive and underrecognized peripheral nerve sheath neoplasm. Arch Pathol Lab Med 2007;131:625–36. 107. Fetsch JF, Miettinen M. Sclerosing perineurioma: a clinicopathologic study of 19 cases of a distinctive soft tissue lesion with a predilection for the fingers and palms of young adults. Am J Surg Pathol 1997;21:1433–42.

CHAPTER

115 Neural and Neuroendocrine Neoplasms (Other than Neurofibromatosis)

54. Filie AC, Lage JM, Azumi N. Immunoreactivity of S-100 protein, alpha-1 antitrypsin, and CD68 in adult and congenital granular cell tumors. Mod Pathol 1996;9:888–92. 55. Mentzel T, Wadden C, Fletcher CD. Granular cell change in smooth muscle tumors of skin and soft tissue. Histopathology 1994;24:223–31. 56. Lee J, Bhawan J, Wax F, Farber J. Plexiform granular cell tumor. A report of two cases. Am J Dermatopathol 1994;16:537–41. 57. Simsir A, Osborne BM, Greenebaum E. Malignant granular cell tumor: a case report and review of the recent literature. Hum Pathol 1996;27:853–8. 58. Fanburg-Smith JC, Meis-Kindblom JM, Fante R, Kindblom LG. Malignant granular cell tumor of soft tissue. Diagnostic criteria and clinicopathologic correlation. Am J Surg Pathol 1998;22:779–94. 59. Apisarnthanarax P. Granular cell tumor. An analysis of 16 cases and review of the literature. J Am Acad Dermatol 1981;5:171–82. 60. Suster S, Rosen LB, Sanchez JL. Granular cell leiomyosarcoma of the skin. Am J Dermatopathol 1988;10:234–9. 61. Erlandson RA, Woodruff JM. Peripheral nerve sheath tumors: an electron microscopic study of 43 cases. Cancer 1982;49:273–87. 62. Wanebo JE, Malik JM, Vandenberg SE, et al. Malignant peripheral nerve sheath tumors: a clinicopathologic study of 28 cases. Cancer 1993;71:1247–53. 63. Berner JM, Sorlie T, Mertens F, et al. Chromosome band 9p21 is frequently altered in malignant peripheral nerve sheath tumors: studies of CDKN2A and other genes in the pRB pathway. Genes Chromosomes Cancer 1999;26:151–60. 64. Wick MR, Swanson PE, Scheithauer BW, et al. Malignant peripheral nerve sheath tumor: an immunohistochemical study of cases. Am J Clin Pathol 1987;87:425–33. 65. Prieto-Granada CN, Wiesner T, Messina JL, et al. Loss of H3K27me3 expression is a highly sensitive marker for sporadic and radiation-induced MPNST. Am J Surg Pathol 2016;40:479–89. 66. Toker C. Trabecular carcinoma of the skin. Arch Dermatol 1972;105:107–10. 67. Sibley RK, Dehner LP, Rosai J. Primary neuroendocrine (Merkel cell?) carcinoma of the skin. I. Am J Surg Pathol 1985;9:95–108. 68. Ratner D, Nelson BR, Brown MD, et al. Merkel cell carcinoma. J Am Acad Dermatol 1993;29:143–56. 68a.  Schadendorf D, Lebbe C, Hausen A, et al. Merkel cell carcinoma: Epidemiology, prognosis, therapy and unmet medical needs. Eur J Cancer 2017;71:53–69. 69. Feng H, Shuda M, Chang Y, Moore PS. Clonal integration of a polyomavirus in human Merkel cell carcinoma. Science 2008;319:1096–100. 70. Kassem A, Schöpflin A, Diaz C, et al. Frequent detection of Merkel cell polyomavirus in human Merkel cell carcinomas and identification of a unique deletion in the VP1 gene. Cancer Res 2008;68: 5009–13. 70a.  Harms PW, Collie AM, Hovelson DH, et al. Next generation sequencing of cytokeratin 20-negative Merkel cell carcinoma reveals ultraviolet-signature mutations and recurrent TP53 and RB1 inactivation. Mod Pathol 2016;29:240–8. 71. Harms KL, Healy MA, Nghiem P, et al. Analysis of prognostic factors from 9387 Merkel cell carcinoma cases forms the basis for the new 8th edition AJCC staging system. Ann Surg Oncol 2016;23:3564–71. 72. Wick MR, Scheithauer BW. Primary neuroendocrine carcinoma of the skin. In: Wick MR, editor. Pathology

2067

SECTION 18 NEOPLASMS OF THE SKIN

116 

Fibrous and Fibrohistiocytic Proliferations of the Skin and Tendons Heinz H. Kutzner, Hideko Kamino, Vijaya B. Reddy and John Pui

Chapter Contents Skin tags . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2068 Cutaneous angiofibroma . . . . . . . . . . . . . . . . . . . . . . . . . 2068

SKIN TAGS Synonyms:  ■ Acrochordons ■ Fibroepithelial polyps ■ Soft fibromas

Dermatofibroma . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2069 Acral fibrokeratoma . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2070 Superficial acral fibromyxoma . . . . . . . . . . . . . . . . . . . . . . 2071 Sclerotic fibroma of the skin . . . . . . . . . . . . . . . . . . . . . . . 2071 Pleomorphic fibroma of the skin . . . . . . . . . . . . . . . . . . . . 2071 Multinucleate cell angiohistiocytoma . . . . . . . . . . . . . . . . . 2073

Skin tags are very common, presenting as soft, skin-colored to slightly hyperpigmented, pedunculated papules that favor the neck, axilla and groin (Fig. 116.1). Skin tags are usually asymptomatic, but can become painful secondary to irritation or infarction.

Dermatomyofibroma . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2074

Epidemiology

Giant cell tumor of tendon sheath . . . . . . . . . . . . . . . . . . . 2075

Men and women are equally affected, and close to 50% of all individuals have at least one skin tag1. Although skin tags were once thought to be associated with colonic polyps, more recent studies have not confirmed this relationship2. Skin tags have also been reported as a cutaneous marker for diabetes mellitus3.

Fibroma of tendon sheath . . . . . . . . . . . . . . . . . . . . . . . . 2075 Nodular fasciitis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2076 Connective tissue nevus . . . . . . . . . . . . . . . . . . . . . . . . . 2076 Infantile digital fibroma . . . . . . . . . . . . . . . . . . . . . . . . . . 2077 Infantile myofibromatosis . . . . . . . . . . . . . . . . . . . . . . . . . 2077 Cutaneous adult myofibroma . . . . . . . . . . . . . . . . . . . . . . 2078 Calcifying aponeurotic fibroma . . . . . . . . . . . . . . . . . . . . . 2078 Fibrous hamartoma of infancy . . . . . . . . . . . . . . . . . . . . . . 2078 Fibromatoses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2079 Plexiform fibrohistiocytic tumor . . . . . . . . . . . . . . . . . . . . . 2080

Pathology Histologically, skin tags are polypoid with loose to dense collagenous stroma and thin-walled blood vessels. In Birt–Hogg–Dubé syndrome and Cowden syndrome, patients can have typical skin tags, but sometimes the “skin tags” represent fibrofolliculomas, trichodiscomas or perifollicular fibromas, versus sclerotic fibromas, respectively4.

Atypical fibroxanthoma . . . . . . . . . . . . . . . . . . . . . . . . . . 2080

Treatment

Dermatofibrosarcoma protuberans . . . . . . . . . . . . . . . . . . 2081

Unless irritated or infarcted, skin tags are more of a cosmetic issue than a clinical concern and can be removed by scissor excision.

Giant cell fibroblastoma . . . . . . . . . . . . . . . . . . . . . . . . . . 2082 Fibrosarcoma . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2082 Epithelioid sarcoma . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2083

Key features

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Clinical Features

■ Fibrous and fibrohistiocytic proliferations of the skin and tendons are common lesions that include both neoplastic and “reactive” processes ■ Common benign fibrous and fibrohistiocytic proliferations, some of their atypical variants that could be misdiagnosed as malignant tumors, and corresponding malignant neoplasms are reviewed ■ These tumors are composed of fibroblasts, myofibroblasts, histiocytes, dermal dendritic cells, collagen fibers, elastic fibers and connective tissue mucin, each present in variable proportions depending upon the particular lesion ■ Immunohistochemical stains are helpful in identifying CD34+ fibroblasts, α-smooth muscle actin-positive myofibroblasts and factor XIIIa-positive dermal dendritic cells, as well as CD68-positive histiocytes and macrophages ■ For some tumors (e.g. DFSP, nodular fasciitis), RT-PCR and fluorescent in situ hybridization (FISH) can detect distinct translocations and fusion genes, allowing for more precise diagnoses

CUTANEOUS ANGIOFIBROMA Synonyms:  ■ Fibrous papule ■ Pearly penile papule ■ Ungual fibroma ■ Fibrous papule of the nose

Cutaneous angiofibroma is a descriptive term for a group of lesions with different clinical presentations and implications, but similar histologic findings.

Clinical Features Fibrous papules are solitary, dome-shaped and shiny, skin-colored to reddish papules located on the face of adults, most commonly on the nose (Fig. 116.2)5. Clinically, they can mimic small intradermal melanocytic nevi, basal cell carcinomas (BCCs), or adnexal tumors. By dermoscopy, a white color is often seen. Pearly penile papules are pearly, white, dome-shaped, closely aggregated small papules located on the glans penis, commonly in a multilayered and circumferential manner on the corona (Fig. 116.3). They are found in up to 30% of young postpubertal adults, and are more common in uncircumcised men6. They can be mistaken for condylomata acuminata or hypertrophied sebaceous glands. Multiple facial angiofibromas are seen in tuberous sclerosis (TS), multiple endocrine neoplasia type 1, Birt–Hogg–Dubé syndrome7, and

Fibrous and fibrohistiocytic proliferations of the skin and tendons comprise a heterogeneous group of both benign and malignant mesenchymal tumors. Predominant tumor cells are CD34+ fibroblasts, α-smooth muscle actin-positive myofibroblasts and factor XIIIa-positive dermal dendritic cells, in conjunction with CD68+ histiocytes and macrophages. Recent advances in immunohistochemistry and molecular pathology (FISH, RT-PCR) allow precise histopathologic classification and diagnosis. Diagnostically relevant translocations and fusion genes can be found in dermatofibrosarcoma protuberans (DFSP) and its morphological variant giant cell fibroblastoma, as well as in nodular fasciitis. Of note, the latter has been reclassified as a “transient neoplasia”. Remarkable is the metastatic potential of a small subgroup of fibrous histiocytomas which so far elude precise clinicopathologic characterization. Epithelioid sarcoma, a perfect clinicopathologic imitator of granulomatous or epithelial proliferations, can be identified immunohistochemically by its distinct loss of the tumor suppressor gene SMARCB1/INI1.

skin tags, acrochordons, cutaneous angiofibroma, dermatofibroma, fibrous histiocytoma, acral fibrokeratoma, superficial acral fibromyxoma, sclerotic fibroma of the skin, pleomorphic fibroma of the skin, epithelioid fibrous histiocytoma, multinucleate cell angiohistiocytoma, dermatomyofibroma, giant cell tumor of tendon sheath, fibroma of tendon sheath, nodular fasciitis, connective tissue nevus, fibroblastic connective tissue nevus, infantile digital fibroma, infantile myofibromatosis, cutaneous adult myofibroma, calcifying aponeurotic fibroma, fibrous hamartoma of infancy, fibromatoses, plexiform fibrohistiocytic tumor, atypical fibroxanthoma, AFX, dermatofibrosarcoma protuberans, DFSP, giant cell fibroblastoma, fibrosarcoma, epithelioid sarcoma, pleomorphic dermal sarcoma, COL1A1-PDGFB fusion gene, SMARCB1/INI1

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116 Fibrous and Fibrohistiocytic Proliferations of the Skin and Tendons

ABSTRACT

non-print metadata KEYWORDS:

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Pathology All angiofibromas are dome-shaped lesions composed of a dermal proliferation of plump or stellate fibroblasts in a collagenous stroma with an increase in the number of thin-walled, dilated blood vessels (Fig. 116.4). The collagen fibers can be arranged in a concentric fashion around hair follicles and blood vessels (a variant known as perifollicular fibroma). Elastic fibers are decreased in number. Some fibroblasts can be multinucleated. Granular and clear-cell variants have been described.

DERMATOFIBROMA Fig. 116.1 Multiple skin tags in the axilla. The lesions are skin-colored, soft and pedunculated.  

Synonyms:  ■ Fibrous histiocytoma ■ Benign fibrous histiocytoma

Fibroma simplex ■ Sclerosing hemangioma ■ Nodular subepidermal fibrosis ■ Histiocytoma ■ Dermal dendrocytoma ■

Clinical Features

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116 Fibrous and Fibrohistiocytic Proliferations of the Skin and Tendons

rarely, neurofibromatosis type 2. They are usually distributed bilaterally on the cheeks, nasolabial folds, nose and chin. In TS, facial angiofibromas usually appear during early to mid childhood. Patients with TS can also have multiple ungual angiofibromas. Both facial (≥3) and ungual (≥2) angiofibromas represent major diagnostic criteria for TS (see Table 61.8).

Dermatofibromas are seen primarily in adults and favor the lower extremities. They are firm, minimally elevated to dome-shaped papules that usually measure from a few millimeters to 1 cm in diameter, but occasionally are up to 2 cm in size. The lesions are commonly hyperpigmented (Fig. 116.5). On palpation, they may seem attached to the subcutaneous tissue; pinching the lesion gently usually results in apparent downward movement of the tumor, also known as the “dimple sign”. By dermoscopy, a central white scar-like patch or white network surrounded by a delicate pigment network is most commonly observed (see Ch. 0). Although some dermatofibromas are thought to arise at sites of trauma or arthropod bites, their precise etiology is not known. Multiple eruptive dermatofibromas have been observed in patients with autoimmune disorders (e.g. lupus erythematosus) and atopic dermatitis and in the setting of immunosuppression (e.g. HIV infection)8. Clinically, dermatofibromas can be confused with cysts or melanocytic nevi, especially those with fibrosis. In the case of larger lesions, the possibility of dermatofibrosarcoma protuberans (DFSP), which is less well defined and multilobed, may be considered. Fig. 116.2 Fibrous papule of the nose. A smooth, dome-shaped, skin-colored papule.

Pathology

Fig. 116.3 Pearly penile papules. Multiple small white papules along the corona of the glans penis. Note the multilayered distribution. Courtesy, Kalman

Fig. 116.4 Angiofibroma. A dome-shaped silhouette with a densely packed collagenous stroma and a diffuse array of fusiform and stellate fibroblasts is seen. These features plus dilated postcapillary venules are characteristic of an angiofibroma.



Dermatofibromas are characterized by a nodular dermal proliferation, predominantly of spindle-shaped fibroblasts and myofibroblasts





Watsky, MD.

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Fig. 116.5 Dermatofibroma. Hyperpigmented firm papule on the lower extremity. Courtesy, Jean L  

Bolognia, MD.

Fig. 116.7 Dermatofibroma. Thick “entrapped” collagen bundles at the outer margin of a cellular proliferation of small fusiform cells is typical of a dermatofibroma.  

Fig. 116.6 Dermatofibroma. There is a nodular proliferation of spindled fibroblasts and histiocytes in the reticular dermis, with hyperplasia and hyperpigmentation of the overlying epidermis. Extension into the subcutaneous tissue occurs in a radial pattern through the connective tissue septa (arrows).  

actin. The histologic differential diagnosis includes keloid, scar, connective tissue nevus, dermatomyofibroma, DFSP (CD34-positive), and nodular Kaposi sarcoma. Of note, dermatofibromas may show CD34 positivity at the periphery while the center is usually CD34-negative, in contrast to DFSP which is homogeneously CD34-positive. Whether dermatofibromas are reactive or neoplastic has been an area of controversy for a long time. The recent detection of clonality in a subset of fibrous histiocytomas in addition to a large size, mitotic activity and/or high recurrence rate in some dermatofibromas and the very rare metastatic potential suggest that fibrous histiocytoma is a tumor rather than a reactive inflammatory process14–18.

Treatment Dermatofibromas may be biopsied or excised to exclude a melanocytic proliferation, a fibrosed cyst or other mesenchymal neoplasm. Undisturbed, dermatofibromas usually persist, but with time may undergo partial regression, especially centrally.

Variants of Dermatofibroma The many clinical and histologic variants of dermatofibroma are listed in Table 116.1 and key features of selected variants are outlined in Table 116.2.

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arranged as short intersecting fascicles (Fig. 116.6). The fibroblasts and myofibroblasts have plump oval nuclei with small nucleoli; mitoses may be present. There may be a component of mono- or multinucleated histiocytes with vacuolated (xanthomatous) cytoplasm (hence the synonym benign fibrous histiocytoma). “Keloidal” collagen bundles, which are refractile with polarized light, are seen at the periphery (Fig. 116.7); the presence of peripheral “entrapped” collagen bundles is considered a classic hallmark of dermatofibroma. Hemorrhage into a dermatofibroma (sclerosing hemangioma) explains the common finding of hemosiderin. The overlying epidermis is usually hyperplastic. Sometimes there are aggregates of basaloid cells with follicular differentiation emanating from the epidermis (follicular and basaloid “induction”), which may be confused with a superficial BCC. There are, however, a few reported cases of true BCCs evolving within longstanding dermatofibromas9. Histologic variants of dermatofibroma are listed in Table 116.1. Positive immunohistochemical reactions for vimentin, factor XIIIa10–12, stromelysin-313, muscle-specific actin and CD68, as well as a negative reaction for CD34, support a diagnosis of dermatofibroma. Evolving cellular dermatofibromas may stain strongly for α-smooth muscle

ACRAL FIBROKERATOMA Synonym:  ■ Acquired digital fibrokeratoma

Clinical Features These uncommon lesions present as a solitary, skin-colored to pink, slightly keratotic, exophytic papulonodule with a collarette of elevated skin (Fig. 116.10). Acquired fibrokeratomas usually occur in middleaged adults and the most common site is the finger19. Clinically, they can resemble a supernumerary digit (see Ch. 64), ungual fibroma, or verruca.

Pathology Acral fibrokeratomas are composed of thick collagen bundles surrounded by blood vessels, oriented perpendicularly to the epidermis (Fig. 116.10, inset)20. The histopathologic differential diagnosis includes ungual fibroma and supernumerary digit21.

Clinical variants Hyperpigmented nodular dermatofibroma Nonpigmented dermatofibroma • Delled (“atrophic”) dermatofibroma • Giant dermatofibroma • Subcutaneous dermatofibroma • Multiple grouped dermatofibromas • Disseminated multiple dermatofibromas • Unusual locations for dermatofibromas: face, finger, subungual, palmoplantar, scalp • Ankle-type dermatofibroma (lipidized fibrous histiocytoma) • Erosive and ulcerated dermatofibroma • Pedunculated or polypoid dermatofibroma • Hyperkeratotic dermatofibroma • Annular hemosiderotic dermatofibroma • Multinodular hemosiderotic dermatofibroma • Dermatofibroma with satellitosis • •

Histopathologic variants Cellular dermatofibroma (fibrous histiocytoma) Poorly cellular dermatofibroma (fibrous, hyalinizing, and keloidal dermatofibromas) • Dermatofibroma with prominent vascular component (sclerosing “hemangioma”) • Aneurysmal fibrous histiocytoma (hemorrhagic or hemosiderotic dermatofibroma) • Dermatofibroma mimicking hemangiopericytoma • Xanthomatous dermatofibroma • Cholesterotic dermatofibroma • Lichenoid, erosive, and ulcerated dermatofibroma • Myxoid dermatofibroma • Delled (“atrophic”) dermatofibroma • Subcutaneous dermatofibroma • Combined dermatofibroma • Dermatofibroma with atypical cells (with “monster” cells or pseudosarcomatous dermatofibroma) • Dermatofibroma with osteoclast-like giant cells • Dermatofibroma with calcification or metaplastic ossification • Palisading dermatofibroma • Granular cell dermatofibroma • Clear cell dermatofibroma • Signet-ring cell dermatofibroma • Balloon cell dermatofibroma • Epithelioid cell fibrous histiocytoma • Dermatofibroma with lymphoid follicles • Dermatofibroma with eosinophilic infiltrate • Dermatofibroma with elastophagocytosis • Dermatofibroma with follicular and/or sebaceous induction • Dermatofibroma with myofibroblastic differentiation • Dermatofibroma with proliferation of nerve fibers • Adenodermatofibroma • Metastasizing fibrous histiocytoma • •

Table 116.1 Clinical and histopathologic variants of dermatofibroma/fibrous histiocytoma. Entities in italics are reviewed in Table 116.2. Adapted from Requena L,  

Kutzner H. Cutaneous soft tissue tumors. Philadelphia: Wolters Kluwer, 2014.

SUPERFICIAL ACRAL FIBROMYXOMA Synonyms:  ■ Acral fibromyxoma ■ Digital fibromyxoma ■ Cellular digital fibroma

Clinical Features Superficial acral fibromyxoma is a rare tumor of acral sites first described in 200122. There is a 2 : 1 male : female ratio, with a broad range for age of onset23–26. The tumor presents as a slowly enlarging, often painful mass, attaining an average size of 2 cm. It usually develops on the toes

Pathology Superficial acral fibromyxomas are located within the dermis with extension into the subcutis. There are non-encapsulated, poorly marginated masses composed of spindled to stellate cells arranged in a vague storiform or loosely fascicular growth pattern (Fig. 116.11). The stroma is myxoid to fibromyxoid with prominent blood vessels and frequent mast cells. Most tumors have alternating areas of fibrous and myxoid stroma23. Minimal cellular atypia is common, and occasionally scattered larger cells with so-called “degenerative change” are present23. Mitotic figures are rare. Significant pleomorphism, neural/perineural infiltration, and necrosis are not seen. In cases involving the nail bed, there is often papillary hyperplasia of the nail bed epithelium27. The majority of these tumors stain strongly for CD34 and frequently for CD99 and CD1024, with focal expression of epithelial membrane antigen, nestin, desmin, and α-smooth muscle actin23,27. The histologic differential diagnosis includes cellular fibroma, myxoid neurofibroma, superficial angiomyxoma, and DFSP.

Treatment These tumors follow a benign course, with the minority (~25%) recurring after complete excision23. Neither malignant transformation nor metastasis has been reported23.

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116 Fibrous and Fibrohistiocytic Proliferations of the Skin and Tendons

CLINICAL AND HISTOPATHOLOGIC VARIANTS OF DERMATOFIBROMA/FIBROUS HISTIOCYTOMA

or fingers, with two-thirds of tumors occurring close to or involving the nail bed23–25; 3% of tumors invade adjacent bone23,26. Less common sites include the palm or heel27. The clinical differential diagnosis includes ungual fibroma, verruca, and giant cell tumor of the tendon sheath.

SCLEROTIC FIBROMA OF THE SKIN Clinical Features This distinct, very collagenous variant of fibroma was originally reported as a component of Cowden syndrome (PTEN hamartoma tumor syndrome). However, a sporadic solitary form has also been described28. In Cowden syndrome, the sclerotic fibromas can be solitary or multiple. They appear on the skin and/or mucous membranes as pearly papules or nodules that measure from a few to up to 10 mm in diameter.

Pathology Sclerotic fibromas are well-circumscribed, dome-shaped, dermal hypocellular nodules composed predominantly of sclerotic thick collagen bundles. The bundles are arranged as short intersecting stacks in a parallel arrangement and are separated by spaces containing connective tissue mucin (plywood-like or whorl-like pattern; Fig. 116.12). Between the collagen bundles, there are thin spindled cells. The spindle cells react positively for vimentin, muscle-specific actin, and CD3429. Positivity for CD34 may result in the misdiagnosis of early DFSP.

PLEOMORPHIC FIBROMA OF THE SKIN Clinical Features This unusual variant of a fibroma was described by Kamino et al.30 in 1989. Pleomorphic fibromas of the skin usually present in adults, with a slight preponderance in women. They favor the extremities and appear as asymptomatic, solitary, skin-colored, dome-shaped or polypoid papules which measure from a few millimeters to nearly 2 cm in diameter. Clinically, they resemble skin tags, neurofibromas, or intradermal melanocytic nevi. Treatment is simple excision, and to date there have been no reports of recurrence.

Pathology Pleomorphic fibromas are polypoid or dome-shaped, well-circumscribed dermal lesions characterized by low cellularity with a predominance of thick collagen bundles in a haphazard array. There are scattered spindled cells and irregularly shaped multinucleated cells with scanty cytoplasm, indistinct cellular borders, and large pleomorphic and hyperchromatic nuclei (Fig. 116.13). Some of the multinucleated cells have multilobed nuclei. Mitotic figures are rare.

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HISTOLOGIC VARIANTS OF DERMATOFIBROMA/FIBROUS HISTIOCYTOMA

Variant

Clinical features

Histopathologic features

DDx/Comments

Epithelioid fibrous histiocytoma (epithelioid cell histiocytoma)e1,e2

Firm, sessile or polypoid papules or nodules 0.5–1.5 cm in diameter

Dome-shaped or polypoid dermal nodules with peripheral adnexal collarettes Monomorphous population of large, stellate and triangular, epithelioid cells with eosinophilic cytoplasm & oval nuclei with small nucleoli; some cells have 2 or more nuclei; no nesting of cells Rare mitotic figures Cells separated by delicate collagen fibers & variable amounts of mucin Proliferation of small blood vessels can be seen

When vascular in appearance, pyogenic granuloma or sclerosing hemangioma ALK rearrangement and overexpression

Lipidized fibrous histiocytoma (“ankle-type” fibrous histiocytoma)e3

Striking predilection for the lower extremity, in particular the ankle

Large foam cells and interspersed siderophages predominate Focally, features of an ordinary fibrous histiocytoma (e.g. peripheral “entrapped” dermal collagen) can be seen

Prognosis excellent

Fibrous histiocytoma of the facee4

Dermal/subcutaneous plaque

Predominance of distinct cellular fascicles & bundles of spindle-shaped tumor cells plus classic features of a fibrous histiocytoma Often extend into the subcutaneous fat and deeper soft tissues, including striated muscle

Compared to classic fibrous histiocytomas located elsewhere, excised with wider margins because of diffuse infiltration, involvement of deeper tissues, and increased rate of local recurrences

Deep dermatofibroma (extending into subcutaneous tissue)88

Usually on the trunk and proximal extremities 1–2 cm in diameter

Similar features to common DF, but extension of dermal components into subcutis Extension via two patterns: (1) ~70% of cases – vertical or horizontal fashion, predominantly along septa which become wedge-shaped (see Fig. 116.6) (2) ~30% of cases – well-circumscribed base with smooth deep margin

Clinically, may resemble lipoma or DFSP Histologically, absence of the multilayered & “honeycomb” patterns characteristic of DFSP

Aneurysmal fibrous histiocytoma (hemorrhagic or hemosiderotic dermatofibroma)e5

Large size and nodular or dome-shaped with a history of recent rapid growth

Large blood-filled spaces rimmed by densely aggregated siderophages but without the typical endothelial lining of vascular structures (pseudovascular spaces; hemorrhagic pseudocysts; Fig. 116.8) Extravasation of erythrocytes Sheets of large histiocytes & brown, Prussian blue-positive siderophages interspersed with small capillaries without endothelial atypia Siderophages may be multi-nucleated Also conventional features of histiocyte-rich fibrous histiocytoma

Clinically and histologically may be confused with malignant vascular tumors or angiomatoid fibrous histiocytoma IHC staining with the endothelial marker CD31 may lead to confusion as also stains phagocytic histiocytes and siderophages

Dermatofibroma with atypical cells (with “monster” cells or pseudosarcomatous dermatofibroma)e6–e11,17

Middle-aged adults Slightly >1 cm in diameter

Architectural pattern & components of a common DF plus atypical mono- and multinucleated cells with large pleomorphic and hyperchromatic nuclei, some of which have prominent nucleoli (Fig. 116.9) Cells have abundant vacuolated cytoplasm, often with hemosiderin deposits Rare mitotic figures and no atypical mitoses

Current recommendation is to treat with clinical caution If in addition to features of a DF with atypical cells, there are numerous mitoses and many of the mitoses are atypical, then the tumor should be labeled a low-grade superficial cutaneous sarcoma or atypical fibrohistiocytic tumor with a genuine, but exceeding low, metastatic potential

Metastasizing fibrous histiocytomae6–e11,17,18

Metastases are welldocumented but exceedingly rare

To date, no specific histologic feature predicts metastatic behavior Warning signs – large primary tumor, extension into subcutis with infiltrative peripheral borders, high proliferation rate (Ki67) & mitotic activity, & multiple recurrences Includes aneurysmal, cellular, and atypical fibrous histiocytomas

Cytogenetic aberrations detected via aCGH may reflect a biologic continuum with 0 in common fibrous histiocytomas to some in atypical fibrous histiocytomas to many in malignant fibrous histocytomas/sarcomas In metastasizing fibrous histiocytomas, genetic aberrations were seen in 2 to 3 chromosomes

Table 116.2 Histologic variants of dermatofibroma/fibrous histiocytoma. aCGH, array comparative genomic hybridization; ALK, anaplastic lymphoma kinase; DDx, differential diagnosis; DF, dermatofibroma; DFSP, dermatofibrosarcoma protuberans; IHC, immunohistochemical.  

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Fig. 116.10 Acral fibrokeratoma. A light pink exophytic papule arising from the dorsal surface of the finger. Histologically, there is a digitated fibrovascular core with vertically arranged collagen bundles lined by epidermal hyperplasia; note the thick stratum corneum (inset).  

Fig. 116.8 “Aneurysmal” dermatofibroma. There are multiple blood-filled spaces and lacunae without an endothelial lining amidst a cellular proliferation replete with siderophages and foamy macrophages (inset).  

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Fig. 116.11 Superficial acral fibromyxoma. The lesion is composed of spindled and stellate cells arranged in a loose storiform pattern with a myxoid collagenous matrix. Courtesy, Shane Meehan, MD.  

Fig. 116.9 Dermatofibroma with atypical cells (“monster” cells). There are histiocyte-like cells with large hyperchromatic (inset) and pleomorphic nuclei as well as scattered fibroblasts. Mitoses are not present.  

The spindle-shaped cells and the irregularly shaped, multinucleated cells are positive for vimentin and CD3431, and the spindle-shaped cells react positively for muscle-specific actin. The differential diagnosis includes dermatofibroma with atypical cells, atypical fibroxanthoma, and neurofibroma with atypical cells. Superficial variants of pleomorphic lipoma or cutaneous atypical lipomatous tumor (ALT) have similar histologic features as pleomorphic fibroma albeit with larger numbers of entrapped adipocytes as well as occasional lipoblasts in ALT.

MULTINUCLEATE CELL ANGIOHISTIOCYTOMA Clinical Features The typical clinical presentation of multinucleate cell angiohistiocytomas is that of slowly growing, multiple, discrete but grouped, red to

Fig. 116.12 Sclerotic fibroma. The collagen bundles in this hypocellular tumor are arranged in short parallel bundles, leading to a laminated or “plywood” appearance.  

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Fig. 116.15 Multinucleate cell angiohistiocytoma. There is a proliferation of dilated blood vessels with a sparse inflammatory infiltrate, an increase in fibroblasts, and the presence of stellate and angulated giant cells (inset). Resemblance to an incipient, richly vascularized dermatofibroma is striking.  

Fig. 116.13 Pleomorphic fibroma. There are delicate interwoven collagen bundles with a few interspersed large mononucleated and multinucleated atypical fibroblasts. The stroma is dominated by mesenchymal mucin.  

Fig. 116.14 Multinucleate cell angiohistiocytoma. Red–brown macules and papules on the dorsum of the hand.  

Fig. 116.16 Dermatomyofibroma. The myofibroblasts are arranged in long intersecting fascicles that are parallel to the skin surface.  

violaceous papules, usually on the lower extremities or the dorsal aspect of the hands (Fig. 116.14). The lesions may be unilateral or bilateral, and typically affect women over 40 years of age32. A generalized form has also been described33. Clinically, lesions may resemble Kaposi sarcoma, granuloma annulare, or sarcoidosis.

Pathology These lesions are composed of a proliferation of dilated capillaries and small venules in the superficial to mid dermis within thickened collagen bundles (Fig. 116.15). The characteristic cell is a multinucleated giant cell, sometimes with peripheral palisading of the nuclei within eosinophilic cytoplasm (Fig. 116.15, inset). The histopathologic differential diagnosis includes dermatofibroma, angiofibroma, hemangioma, and interstitial granuloma annulare.

Treatment These lesions are benign. If left untreated, most cases progress slowly without evidence of spontaneous resolution.

DERMATOMYOFIBROMA 2074

This tumor was described as plaque-like dermal fibromatosis in 1991 by Hügel34 and as dermatomyofibroma by Kamino et al.35. It is a benign fibroblastic/myofibroblastic dermal neoplasm36.

Clinical Features Dermatomyofibromas most commonly occur in young women and favor the shoulder area, axilla, upper arm, and neck. Occasionally, these tumors arise during childhood. They are asymptomatic, wellcircumscribed, oval or annular, skin-colored to red–brown plaques that have a smooth surface and measure 1–2 cm in diameter.

Pathology Dermatomyofibromas are well-circumscribed plaques involving the reticular dermis and the upper portion of the subcutaneous septae; they are composed of well-defined, long fascicles of spindle-shaped cells parallel to the skin surface (Fig. 116.16). The cells have a very uniform appearance, with elongated nuclei having rounded or pointed ends and one or two small nucleoli. There is no evidence of nuclear atypia, and mitoses are rare. The cells are separated by thin collagen fibers and elastic fibers are preserved. The fascicles, spindle-shaped cells, collagen fibers and elastic fibers may have a wavy appearance. The adnexal structures are spared. With Verhoeff–van Gieson stain, the elastic fibers appear slightly increased in number. The spindle-shaped cells react positively for

colony-stimulating factor-1 and COL6A3 at 2q37 encoding collagen type VI α-338–40. This fusion leads to an overexpression of CSF1, which attracts large numbers of macrophages to the tumor site. The histologic differential diagnosis includes epithelioid sarcoma, synovial sarcoma, and deep dermatofibroma.

Treatment

This tumor is benign, with a local recurrence rate of 30%. It can be treated by simple excision37.

The treatment is simple excision. Recurrence is uncommon even when marginally or incompletely excised36.

Treatment

FIBROMA OF TENDON SHEATH

GIANT CELL TUMOR OF TENDON SHEATH Synonym:  ■ Tenosynovial fibroma Synonyms:  ■ Tenosynovial giant cell tumor (localized type) ■

Localized nodular tenosynovitis ■ Giant cell synovioma

Clinical Features This tumor usually presents as a firm nodule on the hand or finger (Fig. 116.17), but can also occur on the toes and other periarticular sites. It is typically slow growing and fixed to subcutaneous structures without attachment to the overlying skin, except on the distal fingers and toes. Although usually asymptomatic, there can be pain, numbness or stiffness of the affected digit. Giant cell tumor of tendon sheath is the most common tumor of the hand and can present at any age, but usually appears in adults 30 to 50 years of age and is more common in women than in men37.

Pathology These tumors have a lobular outline and are attached to the tendon sheath. They have a biphasic appearance, with moderately cellular areas of rounded to polygonal cells blending into hypocellular collagen­ ized areas with spindle cells. The characteristic multinucleated giant cells are scattered throughout the tumor in variable densities. These cells have eosinophilic cytoplasm and from a few to 50 nuclei (Fig. 116.18). There are also both large and small mononucleated histiocytes with abundant vacuolated cytoplasm containing variable amounts of hemosiderin deposits. Stromal clefts, mitotic figures, and, rarely, vascular involvement may be observed. By immunohistochemistry, the larger mononuclear cells express clusterin and occasionally desmin while the smaller histiocyte-like cells are positive for CD68, CD163, and CD45. Remarkably, there is always a focal leukocyte common antigen (LCA)-positive lymphocytic infiltrate. Cytogenetically, this tumor has characteristic translocations, in particular t(1;2)(p13;q37) which fuses two genes – CSF1 at 1p13 encoding

Clinical Features This benign tumor presents as a small subcutaneous nodule. It is most frequently found on the hands and feet, with the most common site of involvement being the thumb. While usually asymptomatic, there can be limitation in the range of motion of involved joints41. This fibroma usually presents in those 20 to 50 years of age. Men develop these tumors three times more often than women. The clinical differential diagnosis includes giant cell tumor of tendon sheath, neuroma, ganglion cyst, rheumatoid nodule, and subcutaneous granuloma annulare.

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116 Fibrous and Fibrohistiocytic Proliferations of the Skin and Tendons

vimentin and are variably positive for muscle-specific actin; staining for desmin, factor XIIIa, and CD34 is negative. These results support a fibroblastic/myofibroblastic differentiation rather than smooth muscle differentiation34–36. On electron microscopy, the myofibroblasts contain prominent rough endoplasmic reticulum and intracytoplasmic myofilaments35. The histologic differential diagnosis includes dermatofibroma and fibroblastic connective tissue nevus.

Pathology The tumor has a well-circumscribed lobular appearance and is attached to a tendon sheath. It is composed of dense hyalinized collagen with scattered spindle-shaped fibroblasts/myofibroblasts and stromal clefts. There are characteristic elongated slit-like vessels as well as occasional giant cells and foci of myxoid change. Tumor cells stain focally for α-smooth muscle actin. Cytogenetically, fibroma of tendon sheath may harbor distinct translocations, in particular t(2;11)(q31–32;q12) and t(9;11)(p24;q13–14)42.

Treatment This tumor is benign, with a recurrence rate of ~25%. Some authors believe that this tumor may represent a sclerotic end-stage of giant cell tumor of tendon sheath43.

Fig. 116.18 Giant cell tumor of tendon sheath. The tumor is composed of sheets of epithelioid histiocytes with a variable number of the characteristic multinucleated osteoclast-like giant cells. Some of the histiocytes may have pale foamy cytoplasm. Courtesy, Jacqueline M Wharton, MD.  

Fig. 116.17 Giant cell tumor of tendon sheath. A skin-colored nodule on the lateral aspect of the index finger.  

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NODULAR FASCIITIS

Treatment

Synonyms:  ■ Benign nodular (pseudosarcomatous) fasciitis ■ ■

Subcutaneous pseudosarcomatous fibromatosis Pseudosarcomatous fasciitis

Nodular fasciitis is treated with a conservative excision. The recurrence rate is ~1%51.

CONNECTIVE TISSUE NEVUS Synonyms/variants:  ■ Collagenoma ■ Elastoma ■ Shagreen patch

Clinical Features Nodular fasciitis is a benign transient tumor (“transient neoplasia”)44 that occurs in young to middle-aged adults. It presents as a rapidly growing (but self-limited) subcutaneous nodule measuring from 1 to 5 cm in diameter, and the upper extremity is the most common site. In children, the head and neck region is the most frequent location45. Clinicopathologic variants include intradermal nodular fasciitis, intravascular fasciitis, and cranial fasciitis46–48. The latter variant develops predominantly in infants 25% of mast cells in bone marrow samples or extracutaneous tissues are spindle-shaped or otherwise atypical 2. Expression of CD25 and/or CD2 by extracutaneous mast cells (often determined by bone marrow flow cytometry) 3. Presence of activating KIT codon 816 mutation in blood, bone marrow, or extracutaneous tissues 4. Serum total tryptase level persistently >20 ng/ml (unless there is an associated clonal myeloid disorder, in which case this parameter is not valid)

Table 118.2 WHO criteria for the diagnosis of systemic mastocytosis.  

express CD2 and/or CD25 (not expressed by normal bone marrow mast cells) and have KIT mutations in exon 17 (codon 816 > 815). Progression of ISM to more severe forms of SM appears to be limited. In a study of 145 adults with ISM, the cumulative probabilities of disease progression to aggressive SM at 10 and 25 years were 1.7% and 8.4%, respectively42. Progression to aggressive forms of mastocytosis is associated with KIT mutations in bone marrow mesenchymal stem cells, leading to involvement of additional cell types of lymphocytic or myeloid lineage42,48a. Compared to individuals with ISM, patients with the smoldering SM (SSM) subtype have increased disease burden manifesting as “B” findings – e.g. hepatosplenomegaly, lymphadenopathy, serum tryptase levels >200 ng/ml. The overall prognosis for SSM patients is unknown, but they have the potential to progress to aggressive SM48. Patients with SM-associated clonal hematological non-mast celllineage disease (SM-AHNMD) usually do not have cutaneous lesions,

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but they may have liver, spleen, and/or lymph node involvement, in addition to the associated hematologic disorder (see Table 118.2). The overall prognosis of SM-AHNMD patients depends upon the severity of the hematologic disease39,49. Patients with aggressive SM have organ dysfunction secondary to mast cell infiltrates, notably in the liver (e.g. ascites, portal hypertension), bone (pain, pathologic fractures), gastrointestinal tract (malabsorption), and spleen (hypersplenism). They also develop cytopenias, leukocytoses (eosinophilia, basophilia, monocytosis), and thrombocytosis as a reflection of bone marrow involvement and abnormal myelopoiesis. The serum tryptase level is often high, reflecting a significantly increased total body mast cell burden. The overall prognosis appears to be dependent upon the response to treatment39,49, and in one study, the median survival was 3.5 years (Fig. 118.10)49. Mast cell leukemia (MCL) is rare. Diagnosis requires the peripheral blood nucleated cell population to be composed of ≥10% mast cells, and bone marrow smears to contain ≥20% mast cells40,42,48. However, because mature mast cells are rarely observed in the peripheral blood of normal individuals, their presence should raise the suspicion of MCL. Most patients do not have cutaneous lesions but frequently experience recurrent fever, weight loss, abdominal pain, diarrhea, nausea, and vomiting. Multiorgan failure, including the bone marrow, often occurs over weeks to a few months. Prognosis is extremely poor, with an expected survival of a year or less from the time of diagnosis33,39,49. With the detection of mutations in KIT and other genes, an alternative classification for childhood, adult-onset, and familial mastocytosis may become more clinically relevant. Highly sensitive quantitative PCR-based methods have permitted detection of codon 816 KIT mutations in other cell types within the bone marrow and peripheral blood, and their presence in progenitor cell populations is associated with more aggressive forms of mastocytosis50,51. In a study of 39 SM patients with a codon 816 KIT mutation, additional mutation(s) in other genes such as TET2, SRSF2, ASXL1, RUNX1, and CBL were found in 25% of those with ISM/SSM and 89% of those with more advanced forms of SM. These additional mutations were associated

SURVIVAL OF SYSTEMIC MASTOCYTOSIS PATIENTS

ISM (n=159) ASM (n=41) SM-AHNMD (n=138) MCL (n=4) Expected US survival

100

Survival

80

60

40

20

0 0

10

20 Years from diagnosis

30

Fig. 118.10 Survival of systemic mastocytosis patients. The life expectancy of patients with indolent systemic mastocytosis (ISM) was not significantly different from the age- and sex-matched US population from the appropriate time period, and leukemic transformation rarely occurred. Based upon these data, the authors recommended that, in general, therapy for ISM should be symptom-directed with avoidance of potentially leukemogenic and immunosuppressive therapies. ASM, aggressive systemic mastocytosis; SM-AHNMD, systemic mastocytosis with associated clonal hematological non-mast cell-lineage disease; MCL, mast cell leukemia. From Lim K-H, Tefferi A, Lasho  

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TL, et al. Systemic mastocytosis in 342 consecutive adults: survival studies and prognostic factors. Blood. 2009;113:5727–36.

with decreased overall survival25. Interestingly, patients with familial disease often lack KIT mutations in codons 815 and 81618. The overall prognosis of familial disease appears to be good but is less well defined. An approach to the initial evaluation of a patient with cutaneous mastocytosis is presented in Fig. 118.11. A thorough history is crucial, with inquiries into disease duration and progression as well as factors that provoke symptoms.

PATHOLOGY Direct Studies The diagnosis of mastocytosis is established by demonstrating characteristic mast cells in one or more organs. For patients with cutaneous lesions, mast cell infiltrates can be demonstrated in a biopsy of lesional skin (Fig. 118.12). Eosinophils are also commonly found within the dermis, and, especially in UP lesions, hyperpigmentation of the basal layer of the epidermis and a few melanophages in the upper dermis are common findings. Special stains, such as toluidine blue, Leder, and Giemsa, or monoclonal antibodies that recognize CD117 (KIT) or tryptase are helpful for identifying tissue mast cells (Fig. 118.13). Mast cell densities in mastocytomas and childhood UP are 150-fold and 40-fold higher than in normal skin, respectively, and are therefore relatively easy to identify. In nodular, papular, and macular lesions (including TMEP) of mastocytosis, mast cells have been quantified using a morphometric technique and shown to have densities of 63.2% (± 8.2% SEM), 16.1% (± 4.8% SEM), and 3.5% (± 1.8% SEM), respectively, compared to 0.4% (± 0.1% SEM) in normal skin31. The mast cells in mastocytosis have a rounded, cuboidal, or fusiform appearance; in general, mast cells tend to get more rounded or cuboidal in larger complexes of cells. In adult mastocytosis with cutaneous lesions that contain only borderline numbers of mast cells, molecular diagnostic studies for KIT mutations may help to confirm the diagnosis. Immunohistochemical staining for CD117 (KIT) can also prove helpful in establishing the diagnosis in subtle forms of mastocytosis38,52. Biopsy specimens of normal-appearing skin from patients with mastocytosis have normal concentrations of mast cells, and thus are not helpful in establishing the diagnosis31. A biopsy of the bone marrow or GI tract may be indicated for patients without skin lesions in whom the diagnosis of SM is a possibility. Increased mast cell numbers in association with variable numbers of eosinophils are observed in these tissue specimens. In addition, the combination of monoclonal antibodies against CD117 (KIT) and tryptase may be useful for identifying atypical mast cells in various tissues39,53. Analysis of peripheral blood samples for the KIT D816V mutation has nearly 100% specificity and reported sensitivities of >90% and ~75% in systemic and cutaneous mastocytosis patients, respectively53.

Indirect Studies Detection of circulating mast cell mediators and/or their metabolites can offer indirect evidence of mastocytosis. Two forms (α and β) of mast cell tryptase have been identified54. Serum α-tryptase levels are elevated in patients with SM, regardless of whether or not they are experiencing acute symptoms, and therefore may be useful in assessing total body mast cell burden. However, β-tryptase is often detected both in mastocytosis patients and in patients without mastocytosis who are experiencing anaphylactic symptoms. Total (α and β) serum tryptase levels have been correlated with the extent of mast cell disease. In one study, half of those patients with total serum tryptase levels between 20 and 75 ng/ml had evidence of SM, whereas all patients with levels >75 ng/ ml had systemic involvement54. Of note, a total serum tryptase level >20 ng/ml represents one of the minor criteria for SM48 (see Table 118.2). Urinary excretion of histamine, MeImAA (1,4-methylimidazole acetic acid [histamine’s major metabolite that is more persistently elevated]), and PGD2M (major prostaglandin D2 metabolite) are historical markers of mastocytosis disease burden55. However, they have low sensitivity and specificity and are currently not used for diagnosis. Plasma levels of IL-6 are also elevated in patients with mastocytosis, correlating with severity of bone marrow pathology, organomegaly, and extent of skin involvement56.



INITIAL EVALUATION OF THE PATIENT WITH CUTANEOUS MASTOCYTOSIS

History

Gastrointestinal symptoms

Inquire about constitutional (e.g. fever, malaise, weight loss) and other systemic symptoms (see Fig. 118.3)

Examine for lymphadenopathy and hepatosplenomegaly

+

Bone pain or history of fracture

Examination

+

*

Laboratory studies

• CBC with manual differential • Serum tryptase level • Liver function tests (LFTs) • Consider KIT gene analysis

Further evaluation as indicated (e.g. barium study or endoscopy)

+

Radiographic skeletal survey or bone scan

Ultrasonography or CT scan; consider liver biopsy

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118 Mastocytosis

Fig. 118.11 Initial evaluation of the patient with cutaneous mastocytosis. A proposed scheme for the diagnosis of mastocytosis of the skin requires one major criterion – typical skin lesions clinically – plus one or two minor criteria. The minor criteria are: (1) monomorphic mast cell infiltrate that consists of either large aggregates of tryptase-positive mast cells (>15 cells/cluster) or scattered mast cells exceeding 20 cells per microscopic high power field (40×); and (2) detection of an activating KIT mutation in lesional skin.

Abnormal

Abnormal LFTs

**

Abnormal CBC or tryptase level

Eosinophilia

Consider bone marrow biopsy

+

Screen peripheral blood or bone marrow sample for the FIP1L1-PDGFRA fusion gene

usually needed for children with a mastocytoma and considered by some to be optional for other pediatric * Not patients, especially if asymptomatic. KIT analysis can also be done on paraffin-embedded skin biopsy specimens. groups recommend in all adult mastocytosis patients, especially if extensive skin disease or persistently ** Some elevated/rising serum tryptase levels. Assessment of bone marrow should include tryptase staining, mast cell immunophenotyping (e.g. CD2, CD25), cytogenetic studies (e.g. for an associated hematologic malignancy), and KIT analysis.

Fig. 118.12 Cutaneous mastocytosis – histologic features. Mast cells within the dermis have a rounded or cuboidal appearance. Granules are seen within the amphophilic cytoplasm (inset). Courtesy, Lorenzo Cerroni, MD.  

DIFFERENTIAL DIAGNOSIS The lesions of childhood and adult mastocytosis are so characteristic that they are only occasionally confused with other skin disorders. Childhood lesions of UP may spontaneously urticate and thus may be mistaken for urticaria. However, lesions of urticaria last only a few hours and do not have the associated hyperpigmentation seen in UP. Some childhood mastocytosis patients may develop bullae. Therefore, the differential diagnosis for blisters in these children includes bullous arthropod bites, bullous impetigo, herpes simplex viral infection, linear IgA bullous dermatosis and, less often, other autoimmune bullous dermatoses. In addition, children with diffuse cutaneous mastocytosis

may develop widespread blisters early in their course, which may be mistaken for epidermolysis bullosa or toxic epidermal necrolysis. Demonstration of increased mast cells in either the blister fluid or skin biopsy of the mastocytosis patient helps to establish the correct diagnosis. Nodular scabies has occasionally been misdiagnosed as mastocytosis. Lastly, if mast cells are not readily detected due to the presence of other leukocytes within the dermis, the patient may be misdiagnosed as having a histiocytic disorder or vasculitis57. Skin lesions of adult mastocytosis patients may at first glance appear as lentigines or melanocytic nevi, but mastocytosis lesions usually have an associated erythema. Mastocytomas in children may be confused with café-au-lait macules, arthropod bites, Spitz or congenital melanocytic nevi, pseudolymphomas, and juvenile xanthogranulomas. Mast cell activation syndrome is characterized by symptoms of mast cell mediator release without evidence of mast cell proliferation, including a lack of cutaneous lesions of mastocytosis. Serum tryptase levels are normal or only slightly elevated, and improvement occurs with antihistamines and leukotriene inhibitors. Of note, the term mast cell activation disorders is sometimes used to encompass the various forms of mastocytosis58.

TREATMENT Treatment of patients with mastocytosis is directed primarily at alleviating symptoms, since there is no cure for this disorder. Many patients with CM and ISM have few, if any, symptoms, and therefore require little or no therapy. Mastocytosis patients should be cautioned to avoid potential mast cell degranulating agents and environmental triggers (Table 118.3). Systemic anesthetic agents that have been directly or indirectly implicated in precipitating anaphylactoid reactions in mastocytosis patients are listed in Table 118.3. In contrast to systemic anesthetics, local injections of lidocaine can be used safely in these patients, and fentanyl, midazolam, propofol, sufentanil, remifentanil, ketamine, desflurane, sevoflurane, cisatracurium, pancuronium, and vecuronium bromide are safe alternative systemic anesthetics for patients with mastocytosis. It has been recommended that mastocytosis patients

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Fig. 118.13 Special stains to detect dermal mast cells. A The Leder method utilizes naphthol AS-D chloroacetate esterase and the mast cell granules appear red. B With the Giemsa stain, the mast cell granules stain metachromatically purple. Immunohistochemical staining with monoclonal antibodies that recognize CD117/KIT receptor (C) or tryptase (D) can also be employed. A,B, Courtesy, Lorenzo

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Cerroni, MD; C,D, Courtesy, Antonio Subtil, MD.

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undergoing general anesthesia be monitored postoperatively for at least 24 hours, since delayed anaphylaxis can occur59,60. Antihistamines are often helpful in controlling the symptoms associated with mastocytosis. The second-generation antihistamines cetirizine, loratadine, and fexofenadine are preferred because they have longer half-lives and more specific antagonism of the H1 receptor (see Table 18.4). Use of multiple agents and higher than standard doses are often required for symptom control. For example, the authors recommend fexofenadine 360 mg in the morning and up to 40 mg of cetirizine at night for control of histamine-related symptoms in adults. In some instances, the addition of an H2 antagonist (e.g. cimetidine, ranitidine, famotidine, nizatidine) may prove beneficial, especially in patients with gastric acid hypersecretion. Oral cromolyn sodium (disodium cromoglycate; 400–800 mg/day), a mast cell stabilizer with poor oral absorption, may alleviate GI manifestations and (to a lesser degree) cutaneous and CNS symptoms associated with mastocytosis. Use of topical cromolyn for cutaneous mastocytosis has also been described. Omalizumab, a humanized murine monoclonal antibody to IgE approved for the treatment of asthma and chronic urticaria, has also been reported to have benefit for symptomatic adult-onset mastocytosis recalcitrant to antihistamine therapy2,3,61. Psoralen plus UVA (PUVA) or narrowband ultraviolet B therapy given up to four times a week may help to control pruritus and cutaneous whealing in patients with mastocytosis62,63. While this treatment can

reduce skin mast cell histamine content, it does not eliminate the mast cell infiltrates. Potent topical corticosteroids, especially under occlusion for 6 weeks or more, may eliminate pruritus and cutaneous whealing as well as reduce the number of lesional skin mast cells, but this can also lead to skin atrophy64. Intralesional injections of triamcinolone acetonide have also been successful in clearing mast cell infiltrates in the skin of mastocytosis patients. Anecdotal reports also describe improvement of cutaneous mastocytomas with application of topical calcineurin inhibitors. In SM patients, relief of cutaneous and GI symptoms with prednisone alone or in combination with cyclosporine has been described65. Some patients with severe mastocytosis experience recurrent, lifethreatening episodes of hypotension following mast cell mediator release, and therefore should be provided with a premeasured epinephrine (adrenaline) preparation (e.g. EpiPen®, Auvi-Q®) for emergency use. In some instances, these patients may experience additional similar attacks within hours of the initial event; prednisone 20–40 mg/ day for 2–4 days may suppress these recurrent reactions. Interferon-α-2b has been used with limited success in patients with aggressive forms of mastocytosis66. Of the various chemotherapeutic agents that have been tried for severe mastocytosis, intravenous cladribine (2-chlorodeoxyadenosine [2-CDA]) has been shown to effectively eliminate skin lesions and markedly reduce the number of bone marrow mast cells in patients with advanced SM, including those with the D816 KIT mutation. Because the latter patients do not typically respond

Avoidance of potential mast cell stimuli Physical Friction Exercise Heat (e.g. hot bath) or cold (e.g. swimming) Dietary Hot beverages Spicy foods Alcohol Medications Aspirin Nonsteroidal anti-inflammatory drugs Narcotics (e.g. morphine, codeine) Anticholinergics (e.g. scopolamine) Dextromethorphan (a cough suppressant) Polymyxin B sulfate Some systemic anesthetics, including lidocaine*, d-tubocurarine, metocurine, etomidate, thiopental, succinylcholine hydrochloride (suxamethonium chloride), enflurane, isoflurane (see text for alternatives) Iodine-based radiographic dyes Dextran (in some IV solutions)

Local therapy for symptom control Potent and superpotent topical corticosteroids, including under occlusion (2) Topical calcineurin inhibitors (3) Intralesional corticosteroids (3)

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118 Mastocytosis

THERAPEUTIC LADDER FOR MASTOCYTOSIS

to imatinib mesylate (see below), the 2-CDA represents first-line therapy4,5. For patients with SM-AHNMD, chemotherapy should be directed at the associated hematologic disorder. Local radiation therapy with ~20–40 Gy over a 7–14-day period may benefit patients with bone pain67. Splenectomy may be indicated for mastocytosis patients with hypersplenism who experience significant cytopenia, and it appears to improve survival in patients with more aggressive disease68. Nonmyeloablative allogeneic hematopoietic stem cell transplantation can be performed for life-threatening disease69. Imatinib mesylate is a tyrosine kinase inhibitor that blocks KIT and PDGF receptors, as well as the BCR-ABL oncoprotein associated with chronic myelogenous leukemia. However, the active site for imatinib within the KIT receptor is proximal to the location affected by the common codon 816 mutations (see Fig. 118.2); the latter lead to amino acid changes that are thought to hamper the binding ability of imatinib to KIT and thereby prevent a therapeutic response to this agent6. On the other hand, imatinib may alleviate the signs and symptoms of mastocytosis in patients with other KIT mutations (e.g. del419, K509I, F522C, V560G; see Fig. 118.2)7,8,70, in addition to those with the FIP1L1-PDGFRA fusion gene who are D816-negative9. Dasatinib, nilotinib, and midostaurin are multitargeted tyrosine kinase inhibitors capable of limiting proliferation and promoting apoptosis of D816Vexpressing mast cells70. Midostaurin has response rates of ~60% in patients with aggressive SM and is FDA-approved for this indication71. However, overall, tyrosine kinase inhibitors have not been effective for the long-term management of advanced SM, supporting a pathogenic role of mutations in genes other than KIT. In the future, treatment of advanced mastocytosis will likely include a combination of drugs directed at specific mutations. For additional online figures visit www.expertconsult.com

Systemic therapy for symptom control Oral antihistamines (1) Oral cromolyn sodium (1) Omalizumab (3) Oral PUVA [psoralens plus ultraviolet A] (2) Narrowband ultraviolet B (3) Oral corticosteroids (3) UVA1 (3) Pre-measured epinephrine with auto-injector (EpiPen®, Auvi-Q®) (3)

Systemic therapy for aggressive/severe mastocytosis Interferon-α-2b (2; limited success) Cladribine (2) Imatinib mesylate (1) Midostaurin, dasatinib, nilotinib (2)

*Local injections are safe. Table 118.3 Therapeutic ladder for mastocytosis. Key to evidence-based support: (1) prospective controlled trial; (2) retrospective study or large case series; (3) small case series or individual case reports.  

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eFig. 118.1 Mastocytomas in infants. A Note the leathery appearance of the skin and erosions.   B Subtle tan papule on the scalp. C Darker brown plaque. B, Courtesy, Antonio Torrelo, MD; C, Courtesy, Joyce Rico,  

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eFig. 118.2 Cutaneous mastocytosis with multiple lesions (“urticaria pigmentosa”) in children. A–D Variable numbers of tan to brown macules, papules, and plaques are evident. B, C Courtesy, Antonio Torrelo, MD; D, Courtesy, Julie V Schaffer, MD.  

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eFig. 118.3 Diffuse cutaneous mastocytosis. Leathery, infiltrated skin with multiple erosions.  

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eFig. 118.4 Adult cutaneous mastocytosis. Multiple small (A) and (B) larger, confluent red–brown papules and plaques.  

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mastocytosis. Proc Natl Acad Sci USA 1999;96:  1609–14. Bodemer C, Hermine O, Palmerini F, et al. Pediatric mastocytosis is a clonal disease associated with D816V and other activating c-KIT mutations. J Invest Dermatol 2010;130:804–15. Wang HJ, Lin ZM, Zhang J, et al. A new germline mutation in KIT associated with diffuse cutaneous mastocytosis in a Chinese family. Clin Exp Dermatol 2014;39:146–9. Chan EC, Bai Y, Kirshenbaum AS, et al. Mastocytosis associated with a rare germline KIT K509I mutation displays a well-differentiated mast cell phenotype.   J Allergy Clin Immunol 2014;134:178–87. Yang Y, Letard S, Borge L, et al. Pediatric mastocytosisassociated KIT extracellular domain mutations exhibit different functional and signaling properties compared with KIT-phosphotransferase domain mutations. Blood 2010;116:1114–23. Zappulla JP, Dubreuil P, Desbois S, et al. Mastocytosis in mice expressing human Kit receptor with the activating Asp816Val mutation. J Exp Med 2005;202:1635–41. Damaj G, Joris M, Chandesris O, et al. ASXL1 but not TET2 mutations adversely impact overall survival of patients suffering systemic mastocytosis with associated clonal hematologic non-mast-cell diseases. PLoS ONE 2014;9:e85362. Schwaab J, Schnittger S, Sotlar K, et al. Comprehensive mutational profiling in advanced systemic mastocytosis. Blood 2013;122:2460–6. Heide R, Tank B, Oranje AP. Mastocytosis in childhood. Pediatr Dermatol 2002;19:375–81. Wiechers T, Rabenhorst A, Schick T, et al. Large maculopapular cutaneous lesions are associated with favorable outcome in childhood-onset mastocytosis. J Allergy Clin Immunol 2015;136:1581–90. Lange M, Niedoszytko M, Nedoszytko B, et al. Diffuse cutaneous mastocytosis: analysis of 10 cases and a brief review of the literature. J Eur Acad Dermatol Venereol 2012;26:1565–71. Kasprowicz S, Chan IJ, Wall DJ, Tharp MD. Nodular mastocytosis. J Am Acad Dermatol 2006;55:347–9. Álvarez-Twose I, Jara-Acevedo M, Morgado JM, et al. Clinical, immunophenotypic, and molecular characteristics of well-differentiated systemic mastocytosis. J Allergy Clin Immunol 2016;137:168–78. Kasper CS, Tharp MD. Quantification of cutaneous mast cells using morphometric point counting and a conjugated avidin stain. J Am Acad Dermatol 1987;16:326–31. Lanternier F, Cohen-Akenine A, Palmerini F, et al. Phenotypic and genotypic characteristics of mastocytosis according to the age of onset. PLoS ONE 2008;3:e1906. Travis WD, Li CY, Bergstralh EJ, et al. Systemic mast cell disease. Analysis of 58 cases and literature review. Medicine (Baltimore) 1988;67:345–68. Andrew SM, Freemont AJ. Skeletal mastocytosis. J Clin Pathol 1993;46:1033–5. Linkhart TA, Linkhart SG, MacCharles DC, et al. Interleukin-6 messenger RNA expression and interleukin-6 protein secretion in cells isolated from normal human bone: regulation by interleukin-1. J Bone Miner Res 1991;6:1285–94. Rossini M, Zanotti R, Viapiana O, et al. Bone involvement and osteoporosis in mastocytosis. Immunol Allergy Clin North Am 2014;34:383–96. Teodosio C, Mayado A, Sánchez-Muñoz L, et al. The immunophenotype of mast cells and its utility in the

diagnostic work-up of systemic mastocytosis. J Leukoc Biol 2015;97:49–59. 38. Valent P, Akin C, Escribano L, et al. Standards and standardization in mastocytosis: consensus statements on diagnostics, treatment recommendations and response criteria. Eur J Clin Invest 2007;37:435–53. 39. Pardanani A. Systemic mastocytosis in adults: 2017 update on diagnosis, risk stratification and management. Am J Hematol 2016;91:1147–59. 40. Parker RI. Hematologic aspects of mastocytosis: I: Bone marrow pathology in adult and pediatric systemic mast cell disease. J Invest Dermatol 1991;96:47S–51S. 41. Metcalfe DD. The liver, spleen, and lymph nodes in mastocytosis. J Invest Dermatol 1991;96:45S–46S, discussion 46S, 60S–65S. 42. Escribano L, Alvarez-Twose I, Sanchez-Munoz L, et al. Prognosis in adult indolent systemic mastocytosis: a long-term study of the Spanish Network on Mastocytosis in a series of 145 patients. J Allergy Clin Immunol 2009;124:514–21. 43. Travis WD, Li CY. Pathology of the lymph node and spleen in systemic mast cell disease. Mod Pathol 1988;1:4–14. 44. Doyle LA, Sepehr GJ, Hamilton MJ, et al. A clinicopathologic study of 24 cases of systemic mastocytosis involving the gastrointestinal tract and assessment of mucosal mast cell density in irritable bowel syndrome and asymptomatic patients. Am J Surg Pathol 2014;38:832–43. 45. Sokol H, Georgin-Lavialle S, Canioni D, et al. Gastrointestinal manifestations in mastocytosis: a study of 83 patients. J Allergy Clin Immunol 2013;132:866–73, e1–3. 46. Hartmann K, Wardelmann E, Ma Y, et al. Novel germline mutation of KIT associated with familial gastrointestinal stromal tumors and mastocytosis. Gastroenterology 2005;129:1042–6. 47. Rogers MP, Bloomingdale K, Murawski BJ, et al. Mixed organic brain syndrome as a manifestation of systemic mastocytosis. Psychosom Med 1986;48:437–47. 48. Horny H, Akin C, Metcalfe D, et al. Mastocytosis (mast cell disease). In: Swerdlow SH, Campo E, Harris NL, et al., editors. World Health Organization (WHO) Classification of Tumors. Pathology & Genetics. Tumours of Hematopoietic and Lymphoid Tissues Lyon. France: IARC Press; 2008. p. 54–63. 48a.  Garcia-Montero AC, Jara-Acevedo M, Alvarez-Twose I, et al. KIT D816V-mutated bone marrow mesenchymal stem cells in indolent systemic mastocytosis are associated with disease progression. Blood 2016;127:761–8. 49. Lim KH, Tefferi A, Lasho TL, et al. Systemic mastocytosis in 342 consecutive adults: survival studies and prognostic factors. Blood 2009;113:5727–36. 50. Erben P, Schwaab J, Metzgeroth G, et al. The KIT D816V expressed allele burden for diagnosis and disease monitoring of systemic mastocytosis. Ann Hematol 2014;93:81–8. 51. Kristensen T, Broesby-Olsen S, Vestergaard H, et al; Mastocytosis Centre Odense University Hospital. Serum tryptase correlates with the KIT D816V mutation burden in adults with indolent systemic mastocytosis. Eur J Haematol 2013;91:106–11. 52. Lee HW, Jeong YI, Choi JC, et al. Two cases of telangiectasia macularis eruptiva perstans demonstrated by immunohistochemistry for c-kit (CD 117). J Dermatol 2005;32:817–20. 53. Kristensen T, Vestergaard H, Bindslev-Jensen C, et al; Mastocytosis Centre Odense University Hospital

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66. 67. 68. 69. 70. 71.

(MastOUH). Sensitive KIT D816V mutation analysis of blood as a diagnostic test in mastocytosis. Am J Hematol 2014;89:493–8. Schwartz LB, Sakai K, Bradford TR, et al. The alpha form of human tryptase is the predominant type present in blood at baseline in normal subjects and is elevated in those with systemic mastocytosis. J Clin Invest 1995;96:2702–10. Morrow JD, Guzzo C, Lazarus G, et al. Improved diagnosis of mastocytosis by measurement of the major urinary metabolite of prostaglandin D2. J Invest Dermatol 1995;104:937–40. Theoharides TC, Boucher W, Spear K. Serum interleukin-6 reflects disease severity and osteoporosis in mastocytosis patients. Int Arch Allergy Immunol 2002;128:344–50. Dunst KM, Huemer GM, Zelger BG, Zelger B. A new variant of mastocytosis: report of three cases clinicopathologically mimicking histiocytic and vasculitic disorders. Br J Dermatol 2005;153:  642–6. Frieri M, Patel R, Celestin J. Mast cell activation syndrome: a review. Curr Allergy Asthma Rep 2013;13:27–32. Borgeat A, Ruetsch YA. Anesthesia in a patient with malignant systemic mastocytosis using a total intravenous anesthetic technique. Anesth Analg 1998;86:442–4. Konrad FM, Schroeder TH. Anaesthesia in patients   with mastocytosis. Acta Anaesthesiol Scand 2009;53:270–1. Bell MC, Jackson DJ. Prevention of anaphylaxis related to mast cell activation syndrome with omalizumab. Ann Allergy Asthma Immunol 2012;108:383–4. Kolde G, Frosch PJ, Czarnetzki BM. Response of cutaneous mast cells to PUVA in patients with urticaria pigmentosa: histomorphometric, ultrastructural, and biochemical investigations. J Invest Dermatol 1984;83:175–8. Brazzelli V, Grassi S, Merante S, et al. Narrow-band UVB phototherapy and psoralen-ultraviolet A photochemotherapy in the treatment of cutaneous mastocytosis: a study in 20 patients. Photodermatol Photoimmunol Photomed 2016;32:238–46. Barton J, Lavker RM, Schechter NM, Lazarus GS. Treatment of urticaria pigmentosa with corticosteroids. Arch Dermatol 1985;121:1516–23. Kurosawa M, Amano H, Kanbe N, et al. Response to cyclosporin and low-dose methylprednisolone in aggressive systemic mastocytosis. J Allergy Clin Immunol 1999;103:S412–20. Butterfield JH. Response of severe systemic mastocytosis to interferon alpha. Br J Dermatol 1998;138:489–95. Johnstone PA, Mican JM, Metcalfe DD, et al. Radiotherapy of refractory bone pain due to systemic mast cell disease. Am J Clin Oncol 1994;17:328–30. Friedman B, Darling G, Norton J, et al. Splenectomy in the management of systemic mast cell disease. Surgery 1990;107:94–100. Ustun C, Reiter A, Scott BL, et al. Hematopoietic stem-cell transplantation for advanced systemic mastocytosis. J Clin Oncol 2014;32:3264–74. El-Agamy DS. Targeting c-kit in the therapy of mast cell disorders: current update. Eur J Pharmacol 2012;690:1–3. Gotlib J, Kluin-Nelemans HC, George TI, et al. Efficacy and safety of midostaurin in advanced systemic mastocytosis. N Engl J Med 2016;374:2530–41.

NEOPLASMS OF THE SKIN SECTION 18

B-Cell Lymphomas of the Skin Lorenzo Cerroni

Synonyms:  ■ Cutaneous B-cell lymphomas ■ Skin-associated

CLASSIFICATION OF B-CELL LYMPHOMAS WITH PRIMARY CUTANEOUS MANIFESTATIONS

lymphoid tissue (SALT)-related B-cell lymphomas

Key features ■ Cutaneous B-cell lymphomas represent a group of lymphomas whose primary site is the skin; they are derived from B lymphocytes in different stages of differentiation. The skin can also be the site of secondary involvement by extracutaneous (usually nodal) B-cell lymphomas ■ Most primary cutaneous B-cell lymphomas (>80%) are low-grade malignancies, and they are characterized by indolent behavior and a good prognosis ■ Precise classification can be achieved only after a complete synthesis of clinical, histopathologic, immunophenotypic, and molecular features. The WHO-EORTC and WHO classifications provide the basis for a consistent classification of patients ■ Treatment options for low-grade types include primarily “watchful waiting” and local radiotherapy; when solitary lesions are present, surgical excision is an option. Systemic or intralesional anti-CD20 antibody may be used in some patients, while systemic chemotherapy is only required in patients with high-grade tumors

INTRODUCTION Although B-cell lymphomas represent the majority of non-Hodgkin lymphomas (NHLs) arising within lymph nodes, they represent a minority of the NHLs whose primary site is the skin. In the classification of cutaneous lymphomas published by the World Health Organization (WHO) and the European Organization for Research and Treatment of Cancer (EORTC) Cutaneous Lymphoma Project Group (Table 119.1), B-cell lymphomas represented 22.5% of all cutaneous lymphomas1. The WHO-EORTC classification has been integrated with only minor changes into the WHO Classification of Tumours of Haematopoietic and Lymphoid Tissues published in 2008 and updated in 2016 (see Table 119.1)2,3. Primary cutaneous lymphomas are defined as malignant lymphomas confined to the skin at presentation after complete staging procedures1,4. In general, most patients with primary cutaneous B-cell lymphoma (pCBCL) are diagnosed by dermatologists, as extracutaneous symptoms and signs are observed only very rarely at the onset of the disease. Consequently, dermatologists should be conversant with the clinicopathologic features of this group of diseases, in order to be able to establish the diagnosis in its early stages. Additionally, as aggressive treatment modalities are needed only in selected cases, these patients should be managed primarily by dermatologists with special expertise in cutaneous lymphomas.

HISTORY In the past, cutaneous B-cell lymphomas were thought to be invariably secondary, that is, due to dissemination of extracutaneous (usually nodal) B-cell lymphomas to the skin. In the 1980s, it was recognized that B-cell lymphomas whose primary site is the skin, i.e. pCBCLs, represent a distinct group of extranodal lymphomas4. The widespread use of immunohistochemical and molecular genetic techniques that can establish clonality, in particular the detection of rearrangements of immunoglobulin genes by PCR (utilizing routine biopsy samples), has shown that some of the cases previously classified as cutaneous B-cell

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WHO-EORTC 2005

WHO 2008/2016

Primary cutaneous follicle center lymphoma • Primary cutaneous marginal zone B-cell lymphoma*





Primary cutaneous diffuse large B-cell lymphoma, leg type • Primary cutaneous diffuse large B-cell lymphoma, other • Intravascular diffuse large B-cell lymphoma •

Primary cutaneous follicle center lymphoma • Extranodal marginal zone lymphoma of mucosa-associated lymphoid tissue – MALT lymphoma • Primary cutaneous diffuse large B-cell lymphoma, leg type • Diffuse large B-cell lymphoma, NOS • Intravascular diffuse large B-cell lymphoma

*Includes cases previously designated as primary cutaneous immunocytoma and primary cutaneous plasmacytoma.

Table 119.1 Classification of B-cell lymphomas with primary cutaneous manifestations – WHO-EORTC 2005 and WHO 2008/2016. NOS, not otherwise specified.  

pseudolymphomas harbor a monoclonal population of lymphocytes, thus representing low-grade malignant B-cell lymphomas of the skin4,5.

EPIDEMIOLOGY For the past several decades, the incidence of pCBCL had been rising, but now appears to have stabilized6. pCBCLs may occur more frequently in specific regions of the world. For example, analysis of data from four academic centers in the US showed that they represented only 4.5% of all the cases of primary cutaneous lymphoma registered in those centers7. In contrast, pCBCL represented 22.5% of all the cases of primary cutaneous lymphoma in the Dutch and Austrian registries for cutaneous lymphomas1. Regional variations have also been observed with regard to the incidence of specific types of pCBCL. In the two largest series published to date, the relative frequencies of follicle center lymphoma and marginal zone lymphoma varied considerably. Follicle center lymphoma represented 71% of all pCBCLs in the Netherlands, but only 41% in Graz; conversely, marginal zone lymphoma represented 42% of all cases of pCBCL in Graz, but only 10% in the Netherlands. On the other hand, the relative frequency of the third most common type of pCBCL, the diffuse large B-cell lymphoma, leg type, was similar in the two series (~15%), indicating that, in these two series, differences in the relative frequencies were confined to B-cell lymphomas characterized by an indolent behavior. This suggests that these variations may be due, at least in part, to a different classification of patients in different centers. In addition to differences in diagnostic and classification standards, true regional variations in the incidence of special types of pCBCL may be due to the presence of different etiologic factors. For example, the association between pCBCL and infection with specific Borrelia species in endemic areas has been known for many years (see below and Ch. 74). This association may explain, in part, regional differences in the incidence of pCBCLs, but the relatively low percentage of such cases (even in countries with endemic Borrelia infections) suggests that other etiologies are also involved in regional variations. pCBCL affects adults of both sexes. With the exception of precursor B lymphoblastic lymphoma/leukemia (which only rarely represents an

2113

Primary cutaneous B-cell lymphomas (pCBCLs) are classified into 3 main categories: primary cutaneous marginal zone B-cell lymphoma (PCMZL), primary cutaneous follicle center lymphoma (PCFCL), and primary cutaneous diffuse large B-cell lymphoma, leg type (DLBCLLT). Detection of monoclonal expression of immunoglobulin light chains (kappa or lambda) is a key diagnostic feature for PCMZL. PCFCL presents with clustered papules and tumors on the head and neck or trunk. Histology shows a follicular, mixed, or diffuse infiltrate of centrocytes and centroblasts. DLBCLLT presents with solitary or multiple plaques and tumors, most often located only on the leg(s). Histology shows a proliferation of large B lymphocytes positive for Bcl-2 and MUM-1, allowing differentiation from diffuse cases of PCFCL. Treatment options for low-grade pCBCLs include primarily “watchful waiting” and local radiotherapy; solitary lesions may be excised surgically. Anti-CD20 antibody may be used in some patients, while systemic chemotherapy is usually only required in patients with high-grade aggressive tumors.

cutaneous B-cell lymphoma, primary cutaneous marginal zone B-cell lymphoma, cutaneous marginal zone B-cell lymphoma, primary cutaneous follicle center lymphoma, cutaneous extranodal marginal zone lymphoma of mucosal-associated lymphoid tissue (MALT), cutaneous follicle center lymphoma, primary cutaneous diffuse large B-cell lymphoma, leg type, cutaneous diffuse large B-cell lymphoma, leg type, intravascular diffuse large B-cell lymphoma, cutaneous B lymphoblastic lymphoma

CHAPTER

119 B-Cell Lymphomas of the Skin

ABSTRACT

non-print metadata KEYWORDS:

2113.e1

SECTION

Neoplasms of the Skin

18

example of true pCBCL), CBCLs are uncommon in children and adolescents.

ETIOLOGY AND PATHOGENESIS The pathogenesis of pCBCL is unknown. In contrast to the many nodal B-cell lymphomas that have been linked to specific genetic alterations (e.g. nodal follicular lymphomas and interchromosomal 14;18 translocations), there are relatively limited data on the specific genetic features of pCBCLs, especially for low-grade subtypes (for details see below). Some similarities to the clinicopathologic features observed in B-cell lymphomas arising in the gastric mucosa (so-called mucosa-associated lymphoid tissue [MALT] lymphomas) led to the hypothesis that pCBCLs are caused by longstanding antigenic stimulation, possibly due to chronic infection with specific microorganisms. In fact, it has been long established that MALT lymphomas originating in the stomach are linked to chronic antigenic stimulation due to infection with Helicobacter pylori. As previously mentioned, Borrelia spp. are thought to play an etiologic role in a minority of cases of pCBCL, particularly in Europe. In patients from a region in Austria with endemic Borrelia infections, specific DNA sequences of Borrelia were detected in 18% of all cases of pCBCL8; similar findings have been reported from Scotland9. At present, no other microorganism has been convincingly linked to the development of pCBCL. However, it should be noted that pCBCLs have been described in immunosuppressed patients, including those with AIDS and solid organ transplant recipients, and reversible pCBCLs have been observed in patients undergoing therapy with methotrexate (in particular those with rheumatoid arthritis), thus suggesting that immune dysregulation may play a role in the development of this disease10–12.

CLINICAL FEATURES In the WHO-EORTC 2005 and WHO 2008/2016 classification schemes, pCBCLs have been divided into four major types (see Table 119.1)1. Follicle center lymphoma and marginal zone B-cell lymphoma are characterized by an indolent clinical behavior, whereas diffuse large B-cell lymphoma, leg type, and intravascular diffuse large B-cell lymphoma have an aggressive clinical behavior. It must be emphasized that, in addition to pCBCLs, the skin can be a site of secondary involvement for practically all types of extracutaneous (usually nodal) B-cell lymphomas and leukemias. Consequently, complete staging should be performed in all patients with a confirmed diagnosis of B-cell lymphoma involving the skin. This includes a complete blood examination, flow cytometry of peripheral blood, CT examination of the chest, abdomen and pelvis, and, if possible, positron emission tomography (PET). Internationally, bone marrow biopsy (with flow cytometry of the aspirate) is still recommended in follicle center lymphoma, diffuse large B-cell lymphoma, leg type, and intravascular diffuse large B-cell lymphoma, but seems to be of limited value in cutaneous marginal zone lymphoma13. In fact, the need for extensive staging investigations in patients with a confirmed diagnosis of cutaneous marginal zone lymphoma is questionable. Likewise, extensive radiologic imaging seems to be superfluous in the follow-up of patients with indolent types of pCBCL confined to the skin14. A recommended staging evaluation for patients with CBCL is summarized in Table 119.2.

Primary Cutaneous Follicle Center Lymphoma

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Primary cutaneous follicle center lymphoma (PCFCL) is defined as a neoplastic proliferation of germinal center cells confined to the skin. It represents a common subtype of pCBCL. Clinically, patients present with solitary or grouped, pink- to plumcolored papules, plaques or tumors, which, especially on the trunk, can be surrounded by patches of erythema (Figs 119.1 & 119.2)15. The term Crosti’s lymphoma has been used to denote those patients with a peripheral patch of erythema. Ulceration is uncommon. Occasionally patients present with miliary and/or agminated small papules that can have an acneiform appearance16. Preferential locations are the scalp and forehead or the back. The skin lesions are usually asymptomatic, and, as a rule, B symptoms (i.e. fever, night sweats, weight loss) are rare. The serum level of lactate dehydrogenase (LDH), which is a powerful prognostic factor in systemic lymphomas, is within normal limits.

RECOMMENDED STAGING INVESTIGATIONS FOR PATIENTS WITH A CONFIRMED DIAGNOSIS OF B-CELL LYMPHOMA INVOLVING THE SKIN

History and physical examination Presence/absence of “B” symptoms, including fever, night sweats, weight loss, malaise • Complete lymph node examination • Palpation of abdomen for hepatosplenomegaly • Examination of oral cavity • History of organ transplantation and/or other immune suppression (e.g. HIV, iatrogenic, congenital) •

Laboratory studies Complete blood count with differential and platelet count Comprehensive serum chemistries including LDH • Flow cytometry of peripheral blood mononuclear cells * • •

Imaging studies Ultrasound of abdomen and superficial lymph nodes Whole-body PET/CT scan or whole-body CT scan*

• •

Additional studies as clinically indicated Bone marrow biopsy** Excisional biopsy of enlarged lymph nodes or other suspicious lesions • PCR analysis for Borrelia spp. DNA in patients from endemic areas (Europe) or travelers to endemic areas • •

*Not required in primary cutaneous marginal zone B-cell lymphoma **While recommended for follicle center lymphoma and all types of large B-cell lymphoma, in the US bone marrow biopsy has been replaced by PET scan as the latter is a more sensitive test.

Table 119.2 Recommended staging investigations for patients with a confirmed diagnosis of B-cell lymphoma involving the skin. CT, computed tomography; HIV, human immunodeficiency virus; LDH, lactate dehydrogenase; PCR, polymerase chain reaction; PET, positron emission tomography.  

Fig. 119.1 Cutaneous follicle center lymphoma. Prominent pink–violet nodule on the lateral forehead with a few telangiectasias. The nodule is surrounded by papules and large infiltrated plaques.  

The prognosis is favorable1,17. Recurrences are observed in up to 50% of patients, but dissemination to lymph nodes or internal organs is rare.

Primary Cutaneous Marginal Zone   B-Cell Lymphoma (Extranodal Marginal Zone Lymphoma of the Mucosa-Associated Lymphoid Tissue - MALT Lymphoma) Primary cutaneous marginal zone B-cell lymphoma (PCMZL) has been recognized as a distinct variant of low-grade malignant pCBCL5,18. In the WHO classification of 2008/20162,3, it has been grouped with other extranodal marginal zone lymphomas of mucosa-associated lymphoid tissue (i.e. MALT lymphomas). Of note, cases classified in the past as

CHAPTER

B-Cell Lymphomas of the Skin

119

Fig. 119.2 Cutaneous follicle center lymphoma. Large nodule on the upper back. Note the surrounding erythematous papules, patches, and plaques (Crosti’s lymphoma).  

Fig. 119.4 Cutaneous marginal zone B-cell lymphoma. Two thick pink–violet plaques on the foot, one of which has a flat surface. Molecular analysis revealed Borrelia DNA within the infiltrate. In the past, these tumors, which demonstrated prominent lymphoplasmacytic differentiation histologically, were classified as cutaneous immunocytomas.  

Fig. 119.5 Cutaneous diffuse large B-cell lymphoma, leg type. Multiple coalescing red–brown papulonodules and plaques on the lower leg.  

Fig. 119.3 Cutaneous marginal zone B-cell lymphoma. Two wellcircumscribed, erythematous nodules on the shoulder.  

primary cutaneous immunocytoma or primary cutaneous plasmacytoma represent examples of PCMZL with prominent lymphoplasmacytic or plasmacytic differentiation, respectively, and the terms cutaneous immunocytoma and cutaneous plasmacytoma are not used in the WHO-EORTC and WHO 2008/2016 classification schemes1,2,3. Clinically, patients present with recurrent pink–violet to red–brown papules, plaques, and nodules that favor the extremities (upper > lower) or trunk (Figs 119.3 & 119.4). Generalized lesions can be observed in a small number of patients. Ulceration rarely occurs and skin lesions are usually asymptomatic. As a rule, B symptoms (i.e. fever, night sweats, weight loss) are not present. The serum level of LDH is within normal limits. In some instances, resolution of lesions may be accompanied by secondary anetoderma due to loss of elastic fibers in the area of the tumor infiltrate. The prognosis of PCMZL is excellent. In a study of 32 patients with PCMZL, none of them developed lymph node or internal involvement during a mean follow-up of more than 4 years5. Of note, PCMZL can arise in areas affected by acrodermatitis chronica atrophicans and it may be linked to infection by Borrelia spp. more frequently than are other types of pCBCL, particularly in Europe8.

Primary Cutaneous Diffuse Large B-Cell Lymphoma, Leg Type Primary cutaneous diffuse large B-cell lymphoma, leg type (DLBCLLT), represents a form of pCBCL that is characterized by a predominance of large round cells (centroblasts, immunoblasts) positive for Bcl-2, MUM-1 (multiple myeloma oncogene 1 or interferon regulatory factor 4 [expressed by post germinal center B cells and plasma cells]), and FOX-P11. It occurs almost exclusively in elderly patients, predominantly women.

Clinically, patients present with solitary or clustered, erythematous to red–brown nodules, located primarily on the distal aspect of one leg (Fig. 119.5). In some patients, lesions may arise on both lower extremities contemporaneously or within a short interval of time. Ulceration may occur. Small erythematous papules can be seen adjacent to larger nodules. It must be emphasized that in ~20% of patients, tumors with similar morphologic and phenotypic features can arise in areas other than the lower extremities, but the designation DLBCLLT is still applied19. The prognosis of DLBCLLT is less favorable than that of other types of pCBCL, with an estimated disease-specific 5-year survival rate of 40–50%1. Molecular data revealed that 9p21 deletions, possibly due to loss-of-function of CDKN2A (encodes p16 and p14ARF), are associated with a worse prognosis20,21. It must be stressed that some patients with nodal large B-cell lymphoma can present with secondary cutaneous lesions located exclusively on the legs, underlying the need for complete staging investigations before a diagnosis of DLBCLLT can be established. The addition of PET scans to CT studies is a useful way of discovering evidence of systemic disease.

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SECTION

Neoplasms of the Skin

18

Intravascular Diffuse Large B-Cell Lymphoma Intravascular diffuse large B-cell lymphoma (IVDLBCL) is a rare malignant proliferation of large B lymphocytes within blood vessels4. Most patients have a B-cell phenotype, but a T-cell variant has been reported. In occasional patients, the skin may be the only affected site, although more often there is systemic involvement (including the CNS) from the onset. Clinically, patients present with indurated, erythematous or violaceous patches and plaques, preferentially located on the trunk and thighs and often with prominent telangiectasias. The clinical appearance is not typical of cutaneous lymphoma, and it may sometimes suggest a diagnosis of panniculitis or vascular tumors. Interestingly, in several patients, IVDLBCL was observed to be confined to cherry angioma lesions. The prognosis of IVDLBCL is poor, and the disease usually runs an aggressive course22.

Precursor B Lymphoblastic Lymphoma/Leukemia B-cell lymphoblastic lymphomas/leukemias are malignant proliferations of precursor B lymphocytes. Reports of patients whose primary site is the skin have been rare. It should be emphasized, however, that all patients should be assumed to have, and treated for, systemic disease, even in the absence of documented systemic involvement at the time of presentation. In contrast to the other cutaneous B-cell lymphomas, this disease shows a clear-cut predilection for children and young adults23. Clinically, patients present with solitary large erythematous tumors, commonly located on the head and neck. Patients with primary skin disease often have asymptomatic lesions of a few weeks’ duration. Those with secondary skin lesions may have systemic symptoms, e.g. weight loss, fever, fatigue, night sweats. The serum level of LDH is often elevated, reflecting the aggressive, and often systemic, nature of the disease. The disease is highly aggressive, and the prognosis of untreated patients is poor.

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Other Cutaneous B-Cell Lymphomas Rare cases of pCBCL do not fit within the subtypes reviewed above. They are therefore placed in the category of primary cutaneous large B-cell lymphoma, other (WHO-EORTC classification)1. In the WHO 2008/2016 classification, these patients are divided amongst several categories, including (but not limited to) large B-cell lymphomas arising in the setting of immune suppression, plasmablastic lymphoma, and diffuse large B-cell lymphoma, not otherwise specified (NOS)2,3. Plasmablastic lymphoma is a rare lymphoma that usually arises within the oral cavity in patients with severe immunosuppression, especially HIVrelated4, but can also be observed in immunocompetent patients. It is often associated with infection by EBV.

%

Fig. 119.6 Cutaneous follicle center lymphoma, diffuse type. A Diffuse infiltrate without a follicular pattern. B Centroblasts (arrow) and medium- and large-sized centrocytes (cleaved cells; arrowheads) predominate.  

PATHOLOGY In addition to routine histology and immunohistochemical phenotyping, which when combined are sufficient for the diagnosis of most cases of pCBCL, PCR and fluorescence in situ hybridization (FISH) can also be performed. These latter tests detect rearrangements in immunoglobulin genes, e.g. IGH (encodes the heavy chain), as well as specific chromosomal translocations.

Primary Cutaneous Follicle Center Lymphoma

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In PCFCL, nodular or diffuse infiltrates are seen within the entire dermis, often extending into the subcutaneous fat (Fig. 119.6A)4. The epidermis is usually spared. A clear-cut follicular pattern with formation of neoplastic germinal centers was observed in only a minority of cases (25%) in the series from Graz (Fig. 119.7)17. However, a higher percentage of cases may show at least some follicular architecture. In those with a follicular pattern, the neoplastic follicles show morphologic features of malignancy, including the presence of a reduced or absent mantle zone, the lack of tingible body macrophages, and a monomorphism of the follicles – so-called “dark” and “clear” areas are no longer recognizable (see Fig. 119.7 [inset])17. In both the follicular and diffuse variants, centrocytes (small to large, cleaved follicle center cells) predominate within the neoplastic infiltrate (Fig. 119.6B) and are admixed with a variable number of centroblasts (large, non-cleaved follicle center cells with prominent nucleoli), immunoblasts, small lymphocytes, histiocytes, and, in some cases, eosinophils and plasma cells. In contrast to nodal FCLs, grading is not used

Fig. 119.7 Cutaneous follicle center lymphoma, follicular type. Neoplastic follicles with a monomorphous morphology (lack of polarization). Note the absence of dark and clear areas within the central portion of the follicle (inset).  

for the classification of PCFCL. On a cytomorphologic basis, some cases of PCFCL with a diffuse pattern of growth and a predominance of large centrocytes have the appearance of a large cell lymphoma, but the prognosis of these cases is similar to that of lesions without the large

CHAPTER

*

B-Cell Lymphomas of the Skin

119 *

$

B

Fig. 119.8 Cutaneous marginal zone B-cell lymphoma. A Small nodules of reactive lymphocytes (dark areas), some of which have reactive germinal centers (arrows). The nodules are surrounded by neoplastic marginal zone cells, lymphoplasmacytoid cells, and plasma cells (clear areas [*]). B Monotypic expression of λ immunoglobulin light chain within the neoplastic population of cells (in the clear areas). C MIB-1 staining shows marked proliferation within a germinal center in a reactive lymphoid follicle and increased proliferation of neoplastic cells in the perifollicular area.  

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cell morphology1,19. Patients with a monotonous proliferation of centroblasts and/or immunoblasts should be classified as having diffuse large B-cell lymphoma. An accompanying infiltrate of small T lymphocytes and histiocytes/macrophages is usually present, and, in some instances, these cells can be predominant. In addition to cases characterized by numerous large cells, morphologic variants of PCFCL include those with a predominant spindle cell morphology, which can simulate sarcomas or other spindle cell tumors histopathologically, thus representing a diagnostic pitfall24. Lesions in which a few B-cell blasts are admixed with numerous T lymphocytes have been classified as “T-cell/histiocyte-rich B-cell lymphomas”, and in the skin probably represent another rare morphologic variant of PCFCL4. Of note, when there is nodal involvement with this latter morphologic variant, it is classified as a large B-cell lymphoma. The tumor cells express B-cell-associated antigens (CD20, CD79a, PAX-5); they are CD5− and CD43− (see Table 0.13 for the specificities of CD markers). When follicles are present, they are characterized by an irregular network of CD21+ follicular dendritic cells. Bcl-6 (a marker of germinal center cells and other lymphoid cells) is positive in virtually all cases, irrespective of the pattern of growth. In most cases with a follicular growth pattern, and in a minority of those with a diffuse growth pattern, neoplastic cells also stain positively for CD10. The presence of small clusters of Bcl-6+ cells outside the follicles is considered strongly suggestive of a diagnosis of PCFCL16. In the vast majority of cases, staining for the protein product of BCL-2 (Bcl-2) yields negative results within neoplastic follicles, representing a major difference from follicular lymphomas arising within lymph nodes25. A useful, though somewhat counterintuitive, distinguishing immunohistochemical feature is the lower degree of proliferative activity within malignant follicles as detected by the anti-Ki-67

antibody (expressed by proliferating cells), in contrast to the strong Ki67-positivity in reactive follicles17,26. In cases with large cell morphology (predominance of large cleaved cells), immunohistochemical staining for MUM-1 is either negative or is positive in a minority of neoplastic cells (in contrast to strong expression of MUM-1 by DLBCLLT; see below)1,19. The interchromosomal 14;18 translocation, typically found in nodal follicular lymphomas, is present in a minority of PCFCLs25. Therefore, the presence of the 14;18 translocation and/ or expression of Bcl-2 should raise suspicion that the patient has a systemic lymphoma involving the skin. Analysis of the genes that encode the joining segment (JH) and other regions of the immunoglobulin heavy chain (IGH) reveals the presence of a monoclonal rearrangement in the majority of patients (60–70%). When gene expression in PCFCLs was analyzed via cDNA microarrays, a germinal center cell signature pattern was observed. Analysis of morphologic, immunohistochemical, and molecular data suggests that follicular lymphomas originating in the lymph nodes and the skin, although characterized by a similar morphologic pattern, have different pathogenic mechanisms.

Primary Cutaneous Marginal Zone B-Cell Lymphoma (Extranodal Marginal Zone Lymphoma of the Mucosa-Associated Lymphoid Tissue – MALT Lymphoma) Histology of PCMZL shows a patchy, nodular or diffuse infiltrate involving the dermis and subcutaneous fat. The epidermis is spared. A characteristic pattern can be observed at scanning magnification (Fig. 119.8A): nodular infiltrates (sometimes containing reactive germinal

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Fig. 119.9 Cutaneous marginal zone B-cell lymphoma – spectrum of cell types. A Admixture of marginal zone cells, plasmacytoid cells, and plasma cells. B Predominance of lymphoplasmacytoid cells (formerly classified as cutaneous immunocytoma; note an intranuclear eosinophilic inclusion [Dutcher body, arrow]). C Predominance of plasma cells (formerly classified as cutaneous plasmacytoma). D Predominance of large blastoid cells similar to plasmablasts.  

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centers) are surrounded by a pale-staining population of small- to medium-sized cells with indented nuclei, inconspicuous nucleoli, and abundant pale cytoplasm – variously described as marginal zone cells, centrocyte-like cells, or monocytoid B cells (Fig. 119.9A)4,5. In addition, plasma cells (at the margins of the infiltrate), lymphoplasmacytoid cells, small lymphocytes, and occasional large blasts are observed. Eosinophils are also a common finding. In some patients, there may be a granulomatous reaction with epithelioid and giant cells. Cases with a predominance of lymphoplasmacytoid lymphocytes were once classified as cutaneous immunocytomas, but are now considered variants of PCMZL. PAS-positive intranuclear inclusions (Dutcher bodies) are sometimes observed and represent a valuable clue to the diagnosis (Fig. 119.9B). Occasionally, the predominant cell type is a plasma cell (Fig. 119.9C), and although such cases used to be classified as primary cutaneous plasmacytomas, they are now also considered to be variants of PCMZL1. Finally, rare cases are characterized by the predominance of large blastoid cells resembling plasmablasts (Fig. 119.9D)27. The centrocyte-like cells stain positively for CD20, CD79a, Fc receptor-like 4 (FCRL4/IRTA1)27a, and Bcl-2; they are negative for CD5, CD10, and Bcl-6. In the overwhelming majority of cases, intracytoplasmic monotypic expression of immunoglobulin light chains (either κ or λ, but not both) can be observed (Fig. 119.10). The monoclonal population of B lymphocytes is often characteristically arranged at the periphery of the cellular aggregates (Fig. 119.8B). Staining for proliferation markers also shows increased positivity at the periphery of the nodules (as well as in reactive germinal centers) (Fig. 119.8C). IgG4 expression is observed in a minority of cases with plasmacytic differentiation but

PATTERN OF IMMUNOGLOBULIN LIGHT CHAIN EXPRESSION

*

Monoclonal (neoplastic)

Polyclonal (reactive)

or

Often ranges from κ 50:50 to 25:75 λ Also referred to as monotypic (defined as 10:1 ratio)

*

Fig. 119.10 Pattern of immunoglobulin light chain expression. Detection of monoclonal expression of immunoglobulin light chains (κ or λ) is a key diagnostic feature for primary cutaneous marginal zone B-cell lymphoma. Monoclonality is defined as a ≥10 : 1 ratio.  

is not associated with systemic IgG4-related disease28. Monoclonal rearrangement of IGH can be detected in the majority of cases (60–80%). PCMZLs express class-switched immunoglobulins, e.g. the same clone can switch from IgM to IgG or IgA29. Although the B lymphocyte changes antibody production from one class to another, the cell retains

and/or p16 (CDKN2B, CDKN2A), resulting in decreased expression of these proteins, has been observed in some patients. 9p21 deletions, possibly leading to loss-of-function of CDKN2A, are associated with a worse prognosis20. A worse prognosis has also been noted in patients whose tumors have MYD88 mutations. Genetic data obtained by FISH or microarray chip technologies have confirmed that DLBCLLTs show clear molecular differences from PCFCL, diffuse type, confirming the need of classifying these cases separately32,33. The molecular profile of DLBCLLT is similar to that observed in diffuse large B-cell lymphomas of the lymph nodes, with the signature pattern of an activated B lymphocyte34.

Primary Cutaneous Diffuse Large B-Cell Lymphoma, Leg Type

IVDLBCL is characterized by a proliferation of large atypical lymphocytes that fills dilated blood vessels within the dermis and subcutaneous tissues (Fig. 119.14A). The malignant cells are large with scanty cytoplasm and often have prominent nucleoli. They are positive for B-cell-associated markers (Fig. 119.14B) as well as for Bcl-2, MUM-1 and FOX-P1. Staining with endothelial cell-related antibodies (e.g. CD31, CD34) highlights the characteristic intravascular location of the cells (Fig. 119.14C). Molecular analysis shows monoclonal rearrangement of IGH. The genetic profile is similar to that observed in diffuse large B-cell lymphomas, activated B cell type.

In DLBCLLT, a dense diffuse infiltrate is seen within the dermis and subcutis. The infiltrate usually involves the entire papillary dermis extending to the dermal–epidermal junction. Involvement of the epidermis by clusters of large atypical cells, simulating the Pautrier microabscesses found in cutaneous T-cell lymphoma, can be observed in some cases (B-cell epidermotropism), representing a potential diagnostic pitfall4. The neoplastic infiltrate consists predominantly of immunoblasts (large round cells with abundant cytoplasm and prominent nucleoli) and centroblasts (Fig. 119.11). Of note, cases of pCBCLs with a predominance of large cleaved cells (i.e. large centrocytes) are classified among the PCFCLs (see above)1. Reactive small lymphocytes are usually few in number, and mitoses are frequent. The common finding of immunoglobulin gene hypermutations is evidence that DLBCLLT is a large cell lymphoma, representing post germinal center lymphocytes that originated from lymphocytes of the germinal center. Neoplastic cells are positive for B-cell markers (CD20, CD79a, PAX-5, IgM), but there can be (partial) loss of antigen expression. Bcl-2, MUM-1 (see above), FOX-P1, and MYC are expressed by neoplastic cells in most patients1,19,31a. These markers are useful in the differential diagnosis of DLBCLLT from PCFCL, diffuse type; in the latter, Bcl-2, MUM-1, and FOX-P1 are usually either negative or expressed by a small minority of cells (Fig. 119.12). The tumors demonstrate monoclonal rearrangement of IGH. The interchromosomal 14;18 translocation is not present. An algorithmic approach to the diagnosis of cutaneous diffuse large B-cell lymphomas is provided in Fig. 119.13. The differential expression of lymphoid markers in various types of diffuse large B-cell lymphoma with cutaneous involvement is summarized in Table 119.3. Rare cases of otherwise typical cutaneous DLBCLLT show expression of CD30 by neoplastic cells19. In nodal diffuse large B-cell lymphomas, CD30 expression was associated with a better prognosis, but data on DLBCLLT are lacking. Hypermethylation of the genes that encode p15

Intravascular Diffuse Large B-Cell Lymphoma

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119 B-Cell Lymphomas of the Skin

affinity for the same antigen. PCMZLs are also characterized by aberrant somatic hypermutations allowing binding to different antigens30. A minority of PCMZLs express IgM, but this is associated with a higher frequency of extracutaneous dissemination. A particular translocation, t(14;18)(q32;21), that involves IGH and MALT1 has been detected in a subset of PCMZL (~30%) as well as MALT lymphomas arising in organs other than the skin. In gene expression studies utilizing cDNA microarrays, PCMZLs had a plasma cell signature pattern. Other genetic aberrations include trisomy 3 (with upregulation of FOXP1) and rarely an 11;18 or a 3;14 translocation31. However, in more than 50% of patients, no molecular abnormalities have been found.

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Fig. 119.12 Immunohistochemical staining with anti-Bcl-2 and anti-MUM-1 antibodies. Staining with anti-Bcl-2 antibody shows negativity (except for reactive small lymphocytes) in follicle center lymphoma, diffuse type (A) and positivity of most tumor cells in diffuse large B-cell lymphoma, leg type (B). Anti-MUM-1 antibody stains virtually all the tumor cells in primary cutaneous diffuse large B-cell lymphoma, leg type (C) while only a minority of cells are positive in primary cutaneous follicle center lymphoma, diffuse type (D).  

Fig. 119.11 Cutaneous diffuse large B-cell lymphoma, leg type. Within the entire dermis, there is a dense, diffuse lymphoid infiltrate. Large cells with a round morphology (mainly immunoblasts) predominate (inset).  

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IMMUNOHISTOCHEMICAL MARKER EXPRESSION IN PRIMARY AND SECONDARY CUTANEOUS LARGE B-CELL LYMPHOMAS WITH OVERLAP IN ROUTINE HISTOPATHOLOGIC FINDINGS

Immunohistochemical marker expression Bcl-2

Bcl-6

CD10

CD5

MUM-1

Cyclin D1

TdT

EBER-1

Follicle center lymphoma, diffuse



+

−/+





Marginal zone lymphoma, blastoid

+















Diffuse large B-cell lymphoma, leg type

+

+/−





+







Primary cutaneous lymphomas −





Systemic lymphomas with secondary skin involvement EBV+ DLBCL

+/−

−/+

−/+



+





+

Nodal DLBCL

+

+/−

+/−

−/+

+/−







Mantle cell lymphoma, blastic

+

−/+



+

−/+

+





CLL/SLL → Richter syndrome

+/−





+









Burkitt lymphoma



+

+









+

B lymphoblastic lymphoma

+



+







+



+/−, majority of cases positive; −/+, majority of cases negative.

Table 119.3 Immunohistochemical marker expression in primary and secondary cutaneous large B-cell lymphomas with overlap in routine histopathologic findings. As to be expected, there can be phenotypic overlap amongst these entities. All stain positively for CD20. The most helpful stains are shaded. CLL/SLL, B-cell chronic lymphocytic leukemia/small lymphocytic lymphoma; DLBCL, diffuse large B-cell lymphoma; EBV, Epstein–Barr virus.  

Precursor B Lymphoblastic Lymphoma/Leukemia Histologically, precursor B lymphoblastic lymphoma/leukemia shows a monomorphous proliferation of medium-sized cells with scanty cytoplasm and round or convoluted nuclei with fine chromatin (Fig. 119.15). A “starry sky” pattern is commonly seen at low power, due to the presence of macrophages with inclusion bodies (“tingible bodies”). Another characteristic feature is the arrangement of neoplastic cells in a “mosaicstone” pattern. Mitoses and necrotic cells are abundant. It must be stressed that histologic features alone do not allow differentiation of lymphoblastic lymphomas of B-cell phenotype from those of T-cell lineage. Immunohistology demonstrates positive staining for TdT (terminal deoxynucleotidyl transferase; present on precursor T and B cells), PAX-5, CD10, and the cytoplasmic µ-chain of immunoglobulins, and in most cases, CD20 and CD79a. CD20 is negative in the pre-pre-Bcell variant, which is CD34+. Molecular analyses usually show a monoclonal rearrangement of IGH and a polyclonal pattern for T-cell receptor genes (TCR), but a lack of rearrangement of IGH or monoclonal rearrangement of both TCR and IGH may be observed.

Other Cutaneous B-Cell Lymphomas Plasmablastic lymphoma is characterized by a proliferation of plasmablasts with large eccentric nuclei, abundant cytoplasm, and prominent nucleoli. While the tumor cells may appear lymphoid, they stain like plasma cells. They are positive for CD38, CD138 and MUM-1, but negative for CD20; they express monotypic immunoglobulin light chains. In situ hybridization for EBV (EBER-1) is positive in the vast majority of cases.

APPROACH TO THE DIAGNOSIS OF CUTANEOUS LARGE B-CELL LYMPHOMAS

Predominant cell type

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Large cleaved cells

Location of cells

Primary cutaneous follicle center lymphoma, diffuse type

In the dermis and/or subcutis

Intravascular

Intravascular large B-cell lymphoma

DIFFERENTIAL DIAGNOSIS Although differential diagnoses of pCBCLs vary according to the type of lymphoma, in general they include inflammatory processes that may simulate malignant lymphomas clinically and/or histopathologically, referred to as cutaneous lymphoid hyperplasia, lymphocytoma cutis or “pseudolymphoma” (see Ch. 121). It must be emphasized that a definitive diagnosis of pCBCL can be reached only after careful examination of the clinical, histopathologic, immunophenotypic and molecular features; in some cases, only repeated examination of the patient and sequential biopsy specimens will allow the correct classification4,26. A schematic diagram with examples of the use of immunohistochemical stains and PCR in the differential diagnosis of pCBCLs is presented in Fig. 119.16. Patients for whom no definitive diagnosis can be established at the time of presentation should provisionally be classified as having

Large round cells

Immunophenotype

Bcl-2+

Bcl-2–

Diffuse large B-cell lymphoma, leg type

Diffuse large B-cell lymphoma, other

Fig. 119.13 Approach to the diagnosis of cutaneous large B-cell lymphomas. In most patients with primary cutaneous diffuse large B-cell lymphoma, leg type, the neoplastic cells strongly express MUM-1 and FOX-P1 (as well as Bcl-2), whereas in primary cutaneous follicle center lymphoma, diffuse type, these stains are usually either negative or expressed by a small minority of cells (see Fig. 119.12).  

“cutaneous atypical lymphoid proliferation of B-cell lineage”, and they should be re-examined at regular intervals4. A complete staging investigation does not belong in the diagnostic evaluation of these patients; that is, patients without a definitive diagnosis of CBCL should not be screened for extracutaneous disease until the diagnosis is established with certainty4. In contrast, once the diagnosis of CBCL has been



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119 B-Cell Lymphomas of the Skin

Fig. 119.14 Cutaneous diffuse intravascular   large B-cell lymphoma. A Intravascular proliferation of medium- to large-sized atypical lymphocytes.   B Positive immunohisto­ chemical staining of neoplastic cells for CD20.   C Intravascular location of neoplastic cells highlighted by staining for endothelial cells (CD31).

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Fig. 119.15 Precursor B lymphoblastic lymphoma/leukemia. Medium-sized blasts with the characteristic “mosaic-stone” linear arrangement.  

established, complete staging is mandatory, as clinicopathologic features alone do not allow the differentiation of primary from secondary cutaneous B-cell lymphomas (see Table 119.2). A diagnostic algorithm for evaluation of patients at first presentation is provided in Fig. 119.17.

In the following section, the major differential diagnoses of each of the main types of pCBCL are outlined separately, as they differ according to the lymphoma type. PCFCL with a follicular pattern of growth should be differentiated from B-cell pseudolymphomas with prominent germinal centers, such as Borrelia-induced lymphocytoma cutis (cutaneous lymphoid hyperplasia)17,35. Lymphocytoma cutis can be triggered by a number of stimuli, including arthropod bites, vaccinations, tattoos and drugs, and it has a predilection for particular body sites such as the earlobes, nipples, and scrotum35. Clinically, lesions are usually solitary and relatively small. Although histologically a follicular pattern is almost always observed, germinal centers in lymphocytoma cutis are reactive, and they are accompanied by inflammatory infiltrates with small lymphocytes, plasma cells, and often eosinophils4,35. The germinal centers in Borreliainduced lymphocytoma cutis are often devoid of a clear-cut mantle, but they are characterized by the presence of many tingible body macrophages, “clear” and “dark” areas, and a normal (high) proliferation rate35. Rare cases of cutaneous PCMZL can have a prominent presence of reactive germinal centers, and they should be differentiated from the follicular type of PCFCL. In these cases, so-called follicular colonization by neoplastic marginal zone cells can indeed cause significant problems in histopathologic differential diagnosis, similar to what happens in B-cell lymphomas of the MALT type. However, the overall architecture of the infiltrate, the presence of a population of monoclonal plasma cells belonging to the neoplastic clone, and the negativity of neoplastic cells for CD10 and Bcl-6 usually allow the diagnosis of cutaneous PCMZL to be established.

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EXAMPLES OF THE USE OF IMMUNOHISTOCHEMICAL STAINS AND PCR IN THE DIFFERENTIAL DIAGNOSIS OF CUTANEOUS B-CELL LYMPHOMAS

Primary cutaneous follicle center lymphoma vs Cutaneous lymphoid hyperplasia/pseudolymphoma Strong MIB-1 staining within lymph follicles (detects Ki-67 antigen in proliferating cells) Clusters of Bcl-6+ cells outside follicles

Favors cutaneous lymphoid hyperplasia/ pseudolymphoma

Fig. 119.16 Examples of the use of immunohistochemical stains and PCR in the differential diagnosis of cutaneous B-cell lymphomas. This represents a simplification and is intended to assist dermatologists in their interpretation of pathology reports. CD20+/CD5+ infiltrates are also seen in secondary skin involvement from mantle cell lymphoma, but in contrast to CLL, mantle cell lymphoma is also positive for cyclin D1 and negative for CD23 (see Table 119.3).  

Favors primary cutaneous follicle center lymphoma

Primary cutaneous follicle center lymphoma vs Secondary skin involvement from nodal follicular lymphoma

+ Bcl-2 follicular cells

Favors systemic lymphoma

+ 14;18 translocation (by PCR or FISH)

Favors systemic lymphoma

Primary cutaneous follicle center lymphoma vs Primary cutaneous marginal zone B-cell lymphoma Bcl-6+ cells in clusters outside lymph follicles

Favors primary cutaneous follicle center lymphoma

Monoclonal (κ+ or λ+) plasma cells at periphery of nodules

Favors primary cutaneous marginal zone B-cell lymphoma

Primary cutaneous marginal zone B-cell lymphoma vs Cutaneous involvement from B-cell CLL

+ CD5 in CD20+ B lymphocytes

Favors cutaneous B-cell CLL

Primary cutaneous follicle center lymphoma vs Primary cutaneous diffuse large B-cell lymphoma, leg type (DLBCLLT)

+ Bcl-2 in neoplastic cells

Favors DLBCLLT

+ MUM-1 in neoplastic cells

Favors DLBCLLT

CLL, chronic lymphocytic leukemia; FISH, fluorescent in situ hybridization; PCR, polymerase chain reaction

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As mentioned previously, secondary cutaneous involvement by primary extracutaneous follicular lymphomas has morphologic and phenotypic features similar or identical to those observed in primary cutaneous B-cell lymphoma, except for the usual positivity of neoplastic cells for Bcl-2 in secondary cutaneous lesions. Consequently, the occurrence of a cutaneous follicular lymphoma with clear-cut positivity for Bcl-2 within neoplastic follicles should be considered as a hint (although exceptions can be encountered) for the diagnosis of secondary skin lesions of nodal lymphoma. The differential diagnosis of PCMZL consists primarily of reactive processes and other types of low-grade pCBCL. Benign, reactive processes do not have monotypic restriction of immunoglobulin light chain expression, in contrast to what is observed in the great majority of cases of PCMZL. PCFCL, diffuse type, can be differentiated from PCMZL by the architectural pattern and cytomorphology, with the former being characterized by a diffuse infiltrate of B lymphocytes with a predominance of centrocytes and centroblasts. Moreover, in contrast to PCMZL, neoplastic cells in PCFCL express Bcl-6. PCMZL should also be distinguished from secondary cutaneous lesions of B-cell chronic lymphocytic leukemia (B-CLL), a condition in which neoplastic B lymphocytes display positivity for CD20, CD23 and CD43, and usually for CD5. Helpful diagnostic features are: (1) the absence, in B-CLL, of plasma cells belonging to the neoplastic clone; and (2) the positivity for CD5 observed in most cases of cutaneous B-CLL, but practically never in PCMZL. CD20+/CD5+ infiltrates are also seen in secondary skin involvement from mantle cell lymphoma, but in contrast to CLL, mantle cell lymphoma is usually positive for cyclin D1 and negative for CD23 (rare cases of mantle cell lymphoma that are negative for cyclin D1 are positive for SOX11).

PCMZL with prominent plasma cell differentiation must be differentiated from reactive plasma cell proliferations and from inflammatory pseudotumors (plasma cell granulomas). In reactive conditions, plasma cells are not atypical, and they display a polyclonal pattern of immunoglobulin light chain expression. Besides inflammatory pseudotumors, reactive skin diseases with a predominance of plasma cells are very rare, with the exception of lesions arising on mucosal surfaces, spirochetal infections (e.g. syphilis, pinta, yaws, acrodermatitis chronica atrophicans), and cutaneous and systemic plasmacytosis. The latter disorder usually displays a polyclonal pattern of immunoglobulin light chain expression, but rarely monoclonality has been reported36. A silver stain (e.g. Warthin–Starry) or immunohistochemical staining for Treponema pallidum can help to highlight the microorganisms in cases of syphilis (see Fig. 0.33). The rare entity pretibial lymphoplasmacytic plaque in children is characterized by a polyclonal pattern of the plasma cells. DLBCLLT must be differentiated from a number of entities, including cutaneous involvement from systemic lymphomas as well as specific infiltrates of acute myelogenous leukemia and non-lymphoid tumors (e.g. solid organ metastases; see Ch. 122). The clinicopathologic pattern together with phenotypic and molecular features allow correct classification of these lesions in most instances. In order to avoid diagnostic errors, detailed immunophenotyping is mandatory in all cases of cutaneous lymphoma, especially in those showing medium- to largesized cell morphology. The differential diagnosis of IVDLBCL is not a problem in typical cases. The large number of atypical cells within blood vessels is patho­ gnomonic of this condition. Distinction between T- and B-cell types cannot be achieved on morphologic grounds alone. Rare cases of intralymphatic anaplastic large T-cell lymphoma (ALCL) are characterized

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119 B-Cell Lymphomas of the Skin

EVALUATION OF THE PATIENT WITH A SUSPECTED DIAGNOSIS OF CUTANEOUS B-CELL LYMPHOMA

Patient presenting with lesion(s) clinically suspicious for cutaneous B-cell lymphoma or patient presenting with other clinical diagnosis

Biopsy Histopathologic features diagnostic of cutaneous B-cell lymphoma

Histopathologic features suggestive of cutaneous B-cell lymphoma but non-diagnostic

Immunohistology and molecular biology

Immunohistology and molecular biology

Clinicopathologic correlation

Diagnostic category of cutaneous B-cell lymphoma

Aberrant phenotype and/or monoclonality

Normal phenotype and/or polyclonality

Reassessment of clinicopathologic features

Pseudolymphoma

Cutaneous B-cell lymphoma

Atypical lymphoid proliferation

Biopsy of other lesions if present; follow-up at short intervals

Staging



%

+

Primary cutaneous B-cell lymphoma

Secondary skin involvement of extracutaneous B-cell non-Hodgkin lymphoma

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Fig. 119.17 Evaluation of the patient with a suspected diagnosis of cutaneous B-cell lymphoma. A Algorithm outlining approach to the patient. B, C Positron emission tomography (PET) scans in a 66-year-old patient with stage IV B-cell non-Hodgkin lymphoma. He had a 1-year history of a cutaneous nodule of the scalp that was originally diagnosed as an epidermoid inclusion cyst. Biopsy of the nodule showed a diffuse large B-cell lymphoma (CD10+, CD20+, variably Bcl-2+, MUM-1−) and a PET-CT scan was performed for staging. There is evidence of widespread disease involving multiple lymph node basins in the dedicated (MIP) image (B) as well as a scalp lesion in a PET-CT fusion image (C; arrow). B,C, Courtesy, Dennis Cooper, MD.  

by a proliferation of neoplastic CD30+ T cells within lymphatic vessels. This disorder represents a variant of ALCL and has similar phenotypic and prognostic features37. IVDLBCL should also be distinguished from reactive disorders characterized by an intravascular proliferation of atypical cells, in particular intralymphatic histiocytosis (IH) and benign intralymphatic proliferation of T-cell lymphoid blasts (BIPTCLB). IH occurs in association with chronic cutaneous infections and systemic disorders such as rheumatoid arthritis and other autoimmune connective tissue diseases. Within the dermis, lymphatic vessels that stain positively for podoplanin contain intraluminal collections of histiocytes (CD68+, CD20−, CD3−). Of note, focal areas of IH can be an incidental finding. BIPTCLB is a rare entity observed in a wide range of cutaneous and extracutaneous disorders from pyogenic granuloma to appendicitis. As in IH, the lymphatic vessels are affected. Cases of precursor B lymphoblastic lymphoma/leukemia should be differentiated from other cutaneous lymphomas/leukemias and from non-lymphoid tumors such as Ewing sarcoma and small cell lung carcinoma. Positivity for TdT represents the most important immunohistochemical feature for the diagnosis of cutaneous lymphoblastic lymphoma. Histologic features of cutaneous lesions do not allow the

differentiation of T-cell from B-cell lymphoblastic lymphomas, thus emphasizing the importance of complete immunophenotypic and genotypic analyses.

TREATMENT The most appropriate treatment modality for patients with a pCBCL is selected after exact classification of the lymphoma, analysis of results of staging investigations, and consideration of the overall condition of the patient4. Those patients with secondary cutaneous lesions of extracutaneous B-cell lymphoma should be treated in a hemato-oncologic, not dermatologic, setting4. Before reviewing the major therapeutic strategies, it must be emphasized that many patients with low-grade pCBCL can be managed conservatively with a so-called watchful-waiting strategy, similar to what is often adopted for indolent B-cell lymphomas and leukemias at extracutaneous sites4,38. Follow-up examinations in these patients should be performed at least every 6 months or at the onset of new lesions and/or new symptoms, in order to treat the patient as soon as

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it is necessary. Many patients managed conservatively with a watchfulwaiting strategy experience a prolonged course and long survival, and they do not need aggressive treatment. For cosmesis and sometimes psychological benefit, intralesional triamcinolone can be injected into the papulonodules. Most patients with pCBCLs that are low-grade (PCFCL, PCMZL) and who have a solitary or few lesions can be treated by local radiotherapy, simple surgical excision, or surgical excision followed by radiotherapy of the surgical field4,38,39. It has been reported that recurrences are less frequently seen in patients treated by radiotherapy with wide margins (about 10–20 cm beyond clinically apparent lesions); this approach seems to be justified for so-called Crosti’s lymphoma, a type of PCFCL arising on the back, in which erythematous nodules, papules and patches surrounding the tumor represent specific infiltrates that can extend far beyond the main bulk of the lesion40. Radiotherapy with wide margins, however, does not seem to be justified for lesions other than Crosti’s lymphoma, as margins of about 3–5 cm usually suffice (depending on the size of the lesion). Surgical excision with narrow margins is a valuable therapeutic modality for patients with solitary well-circumscribed lesions and in the author’s opinion represents the treatment of choice for PCMZL. In these patients, relapse rates do not seem to be higher than in patients treated with more time-intensive modalities such as local radiotherapy. A few reports have appeared in which low-grade pCBCLs were treated with systemic antibiotics, achieving a complete resolution in at least a percentage of the patients41. This type of treatment is conceptually analogous to that adopted for Helicobacter pylori-associated MALT lymphomas of the stomach, which in their early stages can be cured by eradication of H. pylori infection. Complete response to antibiotic therapy has been observed in some patients with Borrelia-associated pCBCL. Although not yet corroborated by adequate data, antibiotic treatment of patients with pCBCLs should be considered before more aggressive therapeutic options are employed, particularly in European countries endemic for Borrelia infections. It is important to treat patients at the onset of the disease, because, in later stages, lesions may no longer be sensitive to systemic antibiotics. PCR analysis of Borrelia DNA is a rapid test that should be performed in all patients with pCBCL from endemic areas, in order to identify those who would more likely benefit from early antibiotic treatment. Another treatment modality for low-grade pCBCL is subcutaneous or intralesional interferon, particularly interferon-α-2a. Although some favorable results have been reported, it appears that treatment with interferon is associated with a complete response in about 50% of patients. Therapy with interferon should be considered for patients presenting with multiple lesions at different body sites, such that local radiotherapy becomes difficult to administer. Intralesional or systemic injection of anti-CD20 monoclonal antibody (rituximab) has been used to induce tumor reduction in patients with indolent pCBCLs42,43. Intralesional administration should be considered in patients presenting with a few, localized lesions. Therapy with intravenous rituximab represents a valid alternative to established treatments, especially in patients who present with disseminated skin lesions or relapse after radiotherapy. Rituximab can also be administered in combination with other treatment modalities for pCBCLs with more aggressive behavior (e.g. DLBCLLT). More recently, additional anti-CD20 antibodies have been introduced, e.g. ofatumumab, obinutuzumab. Patients with DLBCLLT and a limited number of patients with disseminated lesions of PCFCL, diffuse type, need more aggressive treatment modalities (e.g. systemic chemotherapy plus rituximab)44. The regimen used most frequently is cyclophosphamide, doxorubicin, vincristine and prednisone (CHOP) plus rituximab, and it represents the standard of care for DLBCLLT. In the absence of signs of transformation into high-grade lymphoma, aggressive treatment is not indicated in patients with PCMZL. In the setting of significant comorbidities, rituximab alone or in combination with local radiotherapy may be administered. Systemic chemotherapy plus rituximab is the treatment of choice for patients with IVDLBCL, regardless of results of staging investigations. As with DLBCLLT, the addition of rituximab to anthracycline-based chemotherapy significantly improves outcome45. Finally, patients with precursor B lymphoblastic lymphoma/leukemia should be treated with aggressive modalities (chemotherapy plus rituximab; hematopoietic stem cell transplantation) by a hematologist.

PLASMA CELL DYSCRASIAS, INCLUDING MULTIPLE MYELOMA A plasma cell dyscrasia represents a clonal proliferation of plasma cells and it can lead to a monoclonal gammopathy composed of intact immunoglobulins, isolated light chains (15% of patients) or, rarely, isolated heavy chains. The term plasma cell dyscrasia encompasses a number of entities, including monoclonal gammopathy of undetermined significance (MGUS; serum paraprotein osteosclerotic]) to include patients with ≥60% bone marrow plasmacytosis, >1 lytic lesion on total body MRI (or PET-CT), or a ratio of involved : uninvolved free light chains of ≥100 : 1. Of note, the level of circulating monoclonal protein associated with several of the skin disorders listed in Table 119.4 may be so low as to fall below the detection limit of a serum protein electrophoresis or an IgA paraprotein may not be detected because it falls within and is obscured by the β band. As a result, the more sensitive serum immunofixation electrophoresis (IFE) is required to detect an intact immunoglobulin (e.g. IgG, IgA) paraprotein. In diagnosing patients with systemic amyloidosis whose cutaneous amyloid deposits are composed of light chains, the serum free light chain (SFLC) ratio is much more sensitive than even the serum IFE. In addition, because light chains are rapidly excreted into the urine, a urine IFE in addition to SFLC assay is necessary to exclude a light chain-producing plasma cell dyscrasia.

Histopathology In specific skin lesions (see Table 119.4), diffuse infiltration of the dermis by atypical plasma cells or lymphoplasmacytoid cells is present, usually with several mitoses. Multinucleated plasma cells may be found. The infiltrating cells can be difficult to recognize as plasma cells, and CD45 and CD20 are negative in the vast majority of cases. Neoplastic plasma cells can be stained with CD38 and CD138, and they express monotypic immunoglobulins. Intracytoplasmic eosinophilic inclusions (Russell bodies) are often present; the cells are called Mott cells when these bodies form grape-like clusters. PAS-positive eosinophilic inclusions in the nucleus (Dutcher bodies) can also be observed. These are thought to be immunoglobulin or glycoprotein accumulations, and they can be found in other neoplastic conditions in which plasma cells are prevalent (e.g. plasma cell-rich PCMZL; see Fig. 119.9B).

Differential Diagnosis The differential diagnosis of PCMZL with prominent plasma cell differentiation (formerly called cutaneous plasmacytoma) is discussed above. Cutaneous Waldenström macroglobulinemia has histologic features similar to PCMZL with prominent lymphoplasmacytic differentiation (formerly called cutaneous immunocytoma)46, except that direct immunofluorescence demonstrates monoclonal IgM within and around the infiltrating cells. Immunofixation electrophoresis of the serum detects the circulating monoclonal protein as IgM.

CUTANEOUS AND SYSTEMIC PLASMACYTOSIS In cutaneous and systemic plasmacytosis, an entity most commonly seen in Asians, red–brown to violet–brown papules or nodules favor the back but can be widely disseminated. Patients with the systemic form also have lymphadenopathy and occasionally have involvement of the lung, liver, spleen or kidneys. The associated hypergammaglobulinemia is polyclonal as are the infiltrating plasma cells. Histologically, there are variably large aggregates of polyclonal plasma cells in the dermis, usually admixed with an inflammatory infiltrate and sometimes with reactive germinal centers. The findings may overlap with those of plasma cell-rich Castleman disease. For additional online figures visit www.expertconsult.com

eFig. 119.1 Cutaneous diffuse large B-cell lymphoma, leg type. Multiple red–brown tumors on the lower leg.

eFig. 119.2 Cutaneous follicle center lymphoma. Large ulcerated tumors on the scalp surrounded by infiltrated erythematous nodules and plaques.





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119 B-Cell Lymphomas of the Skin

Online only content

eFig. 119.4 Cutaneous marginal zone B-cell lymphoma. Domeshaped erythematous nodule with smooth surface. The surrounding area shows features of acrodermatitis chronica atrophicans. This tumor, which demonstrated prominent lymphoplasmacytic differentiation histologically, was classified as cutaneous immunocytoma in the past.  

eFig. 119.5 Cutaneous diffuse large B-cell lymphoma, leg type. Multiple red–brown papulonodules and tumor on the lower leg.  

eFig. 119.3 Cutaneous follicle center lymphoma. Large ulcerated tumor on the back. Note surrounding erythematous papules, patches and plaques (Crosti’s lymphoma).  

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CUTANEOUS CONDITIONS ASSOCIATED WITH MONOCLONAL GAMMOPATHY

B-Cell Lymphomas of the Skin

Proliferation of lymphoplasmacytic cells in the skin

119

Extramedullary cutaneous plasmacytoma* Cutaneous Waldenström macroglobulinemia†

• •

Deposition of the monoclonal protein in the skin, by definition Primary systemic amyloidosis (light chains) Cryoglobulinemic occlusive vasculopathy (type I cryoglobulins‡) • Hyperkeratotic spicules (follicular > non-follicular) • Crystal-storing histiocytosis • Crystalglobulinemia • IgM storage papules (cutaneous macroglobulinosis)† • Subepidermal bullous dermatosis associated with IgM gammopathy† • •

Deposition of the monoclonal protein in the skin frequently observed Plasma cell dyscrasia-associated acquired cutis laxa, acral or generalized (amyloid and/or IgG) Plasma cell dyscrasia-associated reactive angioendotheliomatosis (type I cryoglobulins or amyloid)

• •

Almost always associated with monoclonal gammopathy Scleromyxedema POEMS syndrome§ • AESOP syndrome – adenopathy and extensive skin patch overlying a plasmacytoma; may coexist with POEMS syndrome§ • Schnitzler syndrome • Necrobiotic xanthogranuloma • •

Frequently associated with monoclonal gammopathy Normolipemic plane xanthoma Scleredema (type 2) • Angioedema secondary to acquired C1 esterase inhibitor deficiency • Clarkson syndrome (idiopathic systemic capillary leak syndrome) • •

Significant association with monoclonal gammopathy, primarily IgA (at least 15% of cases) Erythema elevatum diutinum Subcorneal pustular dermatosis (SPD) and SPD-type IgA pemphigus • Pyoderma gangrenosum • •

Occasionally associated with monoclonal gammopathy Sweet syndrome Cutaneous small vessel vasculitis‡, including adult IgA vasculitis with monoclonal IgA gammopathy • Xanthoma disseminatum • Epidermolysis bullosa acquisita • Paraneoplastic pemphigus • Atypical scleroderma¶ • •

*†In the current WHO-EORTC classification (see Table 119.1), primary cutaneous plasmacytoma is classified as primary cutaneous marginal zone B-cell lymphoma.

IgM monoclonal gammopathy is present by definition; in Schnitzler syndrome, IgG gammopathy has occasionally been observed; Waldenström macroglobulinemia is due to a lymphoplasmacytic lymphoma. ‡Cryoglobulinemic vasculitis can occur secondary to type II cryoglobulins. §Polyneuropathy (P), organomegaly (O), endocrinopathy (E), M-protein (M), skin changes (S; see Ch. 53 for list of skin changes); diagnosis requires monoclonal plasmaproliferative disorder & neuropathy + one other major criterion (sclerotic bone lesions, Castleman disease, increased serum VEGF levels) and one minor criterion (extravascular volume overload, papilledema, O, E, S, thrombocytosis/polycythemia). ¶Possible association; sclerodermoid changes can also occur in the setting of primary systemic amyloidosis.

Table 119.4 Cutaneous conditions associated with monoclonal gammopathy.  

REFERENCES 1. Willemze R, Jaffe ES, Burg G, et al. WHO-EORTC classification for cutaneous lymphomas. Blood 2005;105:3768–85. 2. Swerdlow SH, Campo E, Harris NL, editors.   WHO classification of tumours of haematopoietic and lymphoid tissues. Lyon: IARC Press; 2008. 3. Swerdlow SH, Campo E, Pileri SA, et al. The 2016 revision of the World Health Organization (WHO) classification of lymphoid neoplasms. Blood 2016;127:2375–90. 4. Cerroni L. Skin lymphoma – the illustrated guide. 4th ed. Oxford: Wiley-Blackwell; 2014. 5. Cerroni L, Signoretti S, Höfler G, et al. Primary cutaneous marginal zone B-cell lymphoma: a recently described entity of low-grade malignant cutaneous B-cell lymphoma. Am J Surg Pathol 1997;21:  1307–15. 6. Korgavkar K, Weinstock MA. Changing incidence trends of cutaneous B-cell lymphoma. J Invest Dermatol 2014;134:840–2.

7. Zackheim HS, Vonderheid EC, Ramsay DL, et al. Relative frequency of various forms of primary cutaneous lymphomas. J Am Acad Dermatol 2000;43:793–6. 8. Cerroni L, Zöchling N, Pütz B, Kerl H. Infection by Borrelia burgdorferi and cutaneous B-cell lymphoma. J Cutan Pathol 1997;24:457–61. 9. Goodlad JR, Davidson MM, Hollowood K, et al. Primary cutaneous B-cell lymphoma and Borrelia burgdorferi infection in patients from the highlands of Scotland. Am J Surg Pathol 2000;24:1279–85. 10. Seçkin D, Barete S, Euvrard S, et al. Primary cutaneous posttransplant lymphoproliferative disorders in solid organ transplant recipients: a multicenter European case series. Am J Transplant 2013;13:2146–53. 11. Beylot-Barry M, Vergier B, Masquelier B, et al. The spectrum of cutaneous lymphomas in HIV infection. A study of 21 cases. Am J Surg Pathol 1999;23:1208–16. 12. Koens L, Senff NJ, Vermeer MH, et al. Methotrexateassociated B-cell lymphoproliferative disorders presenting in the skin: a clinicopathologic and

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immunophenotypical study of 10 cases. Am J Surg Pathol 2014;38:999–1006. Senff NJ, Kluin-Nelemans JC, Willemze R. Results of bone marrow examination in 275 patients with histological features that suggest an indolent type of cutaneous B-cell lymphoma. Br J Haematol 2008;142:52–6. Terhorst D, Mestel DS, Humme D, et al. Evaluation of different methods in the follow-up of patients with indolent types of primary cutaneous lymphomas. Br J Dermatol 2012;166:1295–300. Berti E, Alessi E, Caputo R, et al. Reticulohistiocytoma of the dorsum. J Am Acad Dermatol 1988;19:259–72. Massone C, Fink-Puches R, Laimer M, et al. Miliary and agminated-type primary cutaneous follicle center lymphoma: report of 18 cases. J Am Acad Dermatol 2011;65:749–55. Cerroni L, Arzberger E, Pütz B, et al. Primary cutaneous follicle center cell lymphoma with follicular growth pattern. Blood 2000;95:3922–8.

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18. Bailey EM, Ferry JA, Harris NL, et al. Marginal zone lymphoma (low-grade B-cell lymphoma of mucosaassociated lymphoid tissue type) of skin and subcutaneous tissue. A study of 15 patients. Am J Surg Pathol 1996;20:1011–23. 19. Kodama K, Massone C, Chott A, et al. Primary cutaneous large B-cell lymphomas: clinicopathologic features, classification, and prognostic factors in a large series of patients. Blood 2005;106:2491–7. 20. Senff NJ, Zoutman WH, Vermeer MH, et al. Finemapping chromosomal loss at 9p21: correlation with prognosis in primary cutaneous diffuse large B-cell lymphoma, leg type. J Invest Dermatol 2009;129:1149–55. 21. Dijkman R, Tensen CP, Jordanova ES, et al. Array-based comparative genomic hybridization analysis reveals recurrent chromosomal alterations and prognostic parameters in primary cutaneous large B-cell lymphoma. J Clin Oncol 2006;24:296–305. 22. Fonkem E, Lok E, Robison D, et al. The natural history of intravascular lymphomatosis. Cancer Med 2014;3:1010–24. 23. Lee WJ, Moon HR, Won CH, et al. Precursor B- or T-lymphoblastic lymphoma presenting with cutaneous involvement: a series of 13 cases including 7 cases of cutaneous T-lymphoblastic lymphoma. J Am Acad Dermatol 2014;70:318–25. 24. Cerroni L, El-Shabrawi-Caelen L, Fink-Puches R, et al. Cutaneous spindle-cell B-cell lymphoma. A morphologic variant of cutaneous large B-cell lymphoma. Am J Dermatopathol 2000;22:299–304. 25. Cerroni L, Volkenandt M, Rieger E, et al. bcl-2 protein expression and correlation with the interchromosomal 14;18 translocation in cutaneous lymphomas and pseudolymphomas. J Invest Dermatol 1994;102:  231–5. 26. Leinweber B, Colli C, Chott A, et al. Differential diagnosis of cutaneous infiltrates of B lymphocytes with follicular growth pattern. Am J Dermatopathol 2004;26:4–13. 27. Magro CM, Yang A, Fraga G. Blastic marginal zone lymphoma: a clinical and pathological study of 8 cases and review of the literature. Am J Dermatopathol 2013;35:319–26.

27a.  Ikeda JI, Kohara M, Tsuruta Y, et al. Immunohistochemical analysis of the novel marginal zone B-cell marker IRTA1 in malignant lymphoma. Hum Pathol 2017;59:70–9. 28. Brenner I, Roth S, Puppe B, et al. Primary cutaneous marginal zone lymphomas with plasmacytic differentiation show frequent IgG4 expression. Mod Pathol 2013;26:1568–76. 29. van Maldegem F, van Dijk R, Wormhoudt TAM, et al. The majority of cutaneous marginal zone B-cell lymphomas expresses class-switched immunoglobulins and develops in a T-helper type 2 inflammatory environment. Blood 2008;112:3355–61. 30. Deutsch AJA, Frühwirth M, Aigelsreiter A, et al. Primary cutaneous marginal zone B-cell lymphomas are targeted by aberrant somatic hypermutation. J Invest Dermatol 2009;129:476–9. 31. Rinaldi A, Mian M, Chigrinova E, et al. Genome-wide DNA profiling of marginal zone lymphomas identifies subtype-specific lesions with an impact on the clinical outcome. Blood 2011;117:1595–604. 31a.  Lucioni M, Berti E, Arcaini L, et al. Primary cutaneous B-cell lymphoma other than marginal zone: clinicopathologic analysis of 161 cases: Comparison with current classification and definition of prognostic markers. Cancer Med 2016;5:2740–55. 32. Wiesner T, Streubel B, Huber D, et al. Genetic aberrations in primary cutaneous large B-cell lymphoma. A fluorescence in situ hybridization study of 25 cases. Am J Surg Pathol 2005;29:666–73. 33. Hoefnagel JJ, Dijkman R, Basso K, et al. Distinct types of primary cutaneous large B-cell lymphoma identified by gene expression profiling. Blood 2005;105:3671–8. 34. Pham-Ledard A, Prochazkova-Carlotti M, Andrique L, et al. Multiple genetic alterations in primary cutaneous large B-cell lymphoma, leg type support a common lymphomagenesis with activated B-cell-like diffuse large B-cell lymphoma. Mod Pathol 2014;27:402–11. 35. Colli C, Leinweber B, Müllegger R, et al. Borrelia burgdorferi-associated lymphocytoma cutis: clinicopathologic, immunophenotypic, and molecular study of 106 cases. J Cutan Pathol 2004;31:232–40. 36. Honda R, Cerroni L, Tanikawa A, et al. Cutaneous plasmacytosis: report of 6 cases with or without

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systemic involvement. J Am Acad Dermatol 2013;68:978–85. Ferrara G, Ena L, Cota C, Cerroni L. Intralymphatic spread is a common finding in cutaneous CD30+ lymphoproliferative disorders. Am J Surg Pathol 2015;39:1511–17. Senff NJ, Noordijk EM, Kim YH, et al. European Organization for Research and Treatment of Cancer   and International Society for Cutaneous Lymphoma consensus recommendations for the management   of cutaneous B-cell lymphomas. Blood 2008;112:  1600–9. Senff NJ, Hoefnagel JJ, Neelis KJ, et al. Results of radiotherapy in 153 primary cutaneous B-cell lymphomas classified according to the WHO-EORTC classification. Arch Dermatol 2007;143:1520–6. Gulia A, Saggini A, Wiesner T, et al. Clinicopathologic features of early lesions of primary cutaneous follicle center lymphoma, diffuse type: implications for early diagnosis and treatment. J Am Acad Dermatol 2011;65:991–1000. Kiesewetter B, Raderer M. Antibiotic therapy in nongastrointestinal MALT lymphoma: a review of the literature. Blood 2013;122:1350–7. Fink-Puches R, Wolf IH, Zalaudek I, et al. Treatment of primary cutaneous B-cell lymphoma with rituximab. J Am Acad Dermatol 2005;52:847–53. Brandenburg A, Humme D, Terhorst D, et al. Long-term outcome of intravenous therapy with rituximab in patients with primary cutaneous B-cell lymphomas. Br J Dermatol 2013;169:1126–32. Bekkenk MW, Vermeer MH, Geerts ML, et al. Treatment of multifocal primary cutaneous B-cell lymphoma: a clinical follow-up study of 29 patients. J Clin Oncol 1999;17:2471–8. Ferreri AJM, Dognini GP, Bairey O, et al. The addition of rituximab to anthracycline-based chemotherapy significantly improves outcome in “Western” patients with intravascular large B-cell lymphoma. Br J Haematol 2008;143:253–7. Spicknall KE, Dubas LE, Mutasim DF. Cutaneous macroglobulinosis with monotypic plasma cells: a specific manifestation of Waldenström macroglobulinemia. J Cutan Pathol 2013;40:440–4.

NEOPLASMS OF THE SKIN SECTION 18

Cutaneous T-Cell Lymphoma Rein Willemze

Chapter Contents Mycosis fungoides . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2131 Variants of mycosis fungoides . . . . . . . . . . . . . . . . . . . . . . 2135 Sézary syndrome . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2137 Adult T-cell leukemia/lymphoma . . . . . . . . . . . . . . . . . . . . 2139 Primary cutaneous CD30-positive lymphoproliferative   disorders . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2139 Subcutaneous panniculitis-like T-cell lymphoma . . . . . . . . . . 2143 Extranodal NK/T-cell lymphoma, nasal type . . . . . . . . . . . . . 2144 Primary cutaneous CD8-positive aggressive epidermotropic   cytotoxic T-cell lymphoma . . . . . . . . . . . . . . . . . . . . . . . 2144 Primary cutaneous gamma/delta T-cell lymphoma . . . . . . . . 2145 Primary cutaneous CD4-positive small/medium T-cell lymphoproliferative disorder . . . . . . . . . . . . . . . . . . . . . . 2145 Primary cutaneous peripheral T-cell lymphoma, NOS . . . . . . . 2145

Introduction The term cutaneous T-cell lymphoma (CTCL) describes a heterogeneous group of neoplasms of skin-homing T cells that show considerable variation in clinical presentation, histologic appearance, immunophenotype, and prognosis. CTCLs represent approximately 75–80% of all primary cutaneous lymphomas, whereas primary cutaneous B-cell lymphomas (CBCLs) account for approximately 20–25%1. For many years, mycosis fungoides (MF) and Sézary syndrome (SS) were the only known types of CTCL. Over the past three decades, based on a combination of clinical, histologic and immunophenotypical criteria, new types of CTCL and CBCL have been defined and new classifications for the group of primary cutaneous lymphomas have been formulated1–4. A major advantage in the management of primary cutaneous lymphomas compared with lymphomas arising at other sites is that the former can be seen and can be biopsied easily, giving the dermatologist the unique opportunity to correlate the clinical appearance and clinical behavior with histologic, immunophenotypical, and genetic aspects of these conditions. Hence, the dermatologist can play a key role in the diagnosis, classification, and treatment of these diseases.

History In 1806, a French physician, Jean Louis Alibert, was the first to describe a patient with MF. This case was designated pian fungoïde in his atlas, but in 1835 it was renamed mycosis fungoïde because of the resemblance of some skin tumors to mushrooms. In 1870, Bazin described the natural progression from a nonspecific premycotic phase to plaque lesions and finally to tumors, which probably represents one of the first descriptions of the “multistep model” in the development of a malignancy. In 1885, Vidal and Brocq used the term “mycosis fungoides d’emblée” for patients presenting with skin tumors not preceded by patches or plaques. It has now become clear that such cases represent another type of CTCL or a CBCL. The erythrodermic form of MF was described in 1892 by Besnier and Hallopeau. These early descriptions of the major clinical forms of MF were followed by descriptions of Sézary syndrome by Sézary and Bouvrain in 1938, pagetoid reticulosis by Woringer and Kolopp in 1939, and lymphomatoid papulosis (LyP) by Macaulay in 1968.

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Thus, in the early 1970s, MF and some related conditions were the only types of cutaneous lymphoma that had been rather well described. Reports on cutaneous lymphomas other than MF/SS, commonly designated in the past as malignant reticulosis or reticulum cell sarcoma, were few. Moreover, they were firmly believed to represent skin manifestations of a systemic lymphoma and treated as such.

The CTCL concept In 1968, Lutzner and Jordan described the ultrastructural features of the circulating atypical cells in SS. Characteristically, the nuclei of these cells had deep and narrow indentations, giving them a cerebriform appearance. Three years later, similar cells were found in the skin and lymph nodes of patients with MF. In 1975, based on the observation that the neoplastic cells in MF, SS, and related conditions not only had the same morphology but also a common T-cell phenotype, the term “CTCL” was suggested for this group of diseases5. Within a short time, this term gained wide acceptance, particularly in the US. The introduction of the CTCL concept can be considered as a landmark in the history of this group of diseases. However, a major disadvantage has been that in many subsequent studies, distinction was no longer made between MF, SS, and other T-cell neoplasms, entities which may vary considerably in clinical presentation and clinical behavior.

The concept of primary cutaneous lymphomas At about the same time that the CTCL concept was introduced, several European groups started to classify cutaneous lymphomas according to the criteria of the Kiel classification, a system used by hematopathologists for the categorization of nodal lymphomas. It was then determined that many types of CBCL and CTCL (other than classic MF and SS) can present in the skin without any evidence of extracutaneous disease at the time of diagnosis. It appeared that these primary cutaneous lymphomas often have a completely different clinical behavior and prognosis when compared to morphologically similar lymphomas arising within lymph nodes, and therefore require different types of treatment1. In addition, differences in the presence of specific chromosomal translocations and in the expression of oncogenes, viral sequences or antigens (e.g. EBV), and adhesion receptors involved in tissue-related lymphocyte homing were found. Such differences underscored that primary cutaneous lymphomas represent a distinct group and may explain, at least in part, their different clinical behavior. For instance, the observation that the neoplastic T cells in most CTCLs express cutaneous lymphocyte antigen (CLA) and the CC-chemokine receptors 4 (CCR4) and 10 (CCR10) indicates that they are the neoplastic counterparts of normal skinhoming T cells, and this explains why these CTCLs present in the skin. Perhaps most importantly, it appeared that different types of CTCL and CBCL with different clinical behaviors and different therapeutic requirements may have an identical histologic appearance. This implies that histologic features should always be combined with clinical and immunophenotypical data, before a definite diagnosis (classification) is made. Over the past two decades, such an approach resulted in the delineation of several new types of CTCL and CBCL, and it formed the basis of the European Organization for Research and Treatment of Cancer (EORTC) classification for primary cutaneous lymphomas1.

EORTC, WHO and WHO-EORTC classification schemes The EORTC classification scheme was the first one that was specifically designed for the group of primary cutaneous lymphomas. It contained a limited number of well-defined types of CTCL and CBCL, which together accounted for >95% of all primary cutaneous lymphomas, in

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The term cutaneous T-cell lymphoma (CTCL) describes a heterogeneous group of neoplasms of skin-homing T cells that show considerable variation in clinical presentation, histologic appearance, immunophenotype and prognosis. CTCLs represent approximately 75–80% of all primary cutaneous lymphomas, whereas primary cutaneous B-cell lymphomas (CBCLs) account for approximately 20–25%. For many years, mycosis fungoides (MF) and Sézary syndrome (SS) were the only known types of CTCL. Over the past two to three decades, based on a combination of clinical, histologic, immunophenotypical and genetic criteria, new types of CTCL have been defined and included in new classifications for (primary cutaneous) malignant lymphomas, such as the WHO-EORTC classification for cutaneous lymphomas and the fourth edition of the WHO classification for malignant lymphomas (2008, updated in 2016). In these classifications, three main categories of CTCL can be distinguished: (1) the group of classic CTCL, which includes MF, variants or subtypes of MF, and SS; (2) the group of primary cutaneous CD30-positive lymphoproliferative disorders (CD30+ LPD), which includes lymphomatoid papulosis and cutaneous anaplastic large cell lymphoma; and (3) a group of rare, often aggressive cutaneous T/NK-cell lymphomas, including subcutaneous panniculitislike T-cell lymphoma, extranodal NK/T-cell lymphoma, nasal type, and cutaneous peripheral T-cell lymphoma (PTCL), NOS (not otherwise specified). In this latter group, aggressive epidermotropic CD8-positive CTCL, cutaneous gamma/delta T-cell lymphoma, primary cutaneous CD4-positive small-medium pleomorphic T-cell lymphoproliferative disorder and primary cutaneous acral CD8-positive lymphoma (added in the 2016 update of the WHO classification) have been separated out as rare subtypes of PTCL, NOS. Classification according to the WHO-EORTC classification or WHO 2008/2016 classification is the most important prognostic factor and a prerequisite for adequate management and treatment of these conditions. This chapter describes the characteristic features, differential diagnosis, management and treatment, and prognostic factors of these different types of CTCL.

cutaneous T-cell lymphoma, mycosis fungoides, Sézary syndrome, primary cutaneous CD30-positive lymphoproliferative disorders, subcutaneous panniculitis-like T-cell lymphoma, adult T-cell leukemia/lymphoma, extranodal NK/T-cell lymphoma (nasal type), primary cutaneous CD8-positive aggressive epidermotropic cytotoxic T-cell lymphoma, primary cutaneous gamma/delta T-cell lymphoma, primary cutaneous CD4-positive small/medium T-cell lymphoproliferative disorder, primary cutaneous acral CD8-positive T-cell lymphoma, folliculotropic mycosis fungoides, pagetoid reticulosis, granulomatous slack skin

CHAPTER

120 Cutaneous T-Cell Lymphoma

ABSTRACT

non-print metadata KEYWORDS:

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addition to some provisional entities, which were not yet fully defined clinically. A distinction was made between cutaneous lymphomas with indolent, intermediate, or aggressive clinical behavior. By including well-defined and recognizable disease entities, this classification provided the clinician with detailed information on staging, preferred mode of treatment, clinical behavior and prognosis, serving as a useful guide to optimal management and treatment. The third edition of the World Health Organization (WHO) classification for malignant lymphomas adopted the most common types of CTCL from the EORTC classification, but there was controversy with regard to the categorization of some rare types of CTCL2. In addition, the WHO classification contained new entities not yet included in the EORTC scheme. In 2004, representatives from both organizations reached an agreement on a new classification scheme for the group of cutaneous lymphomas: the WHO-EORTC classification3. Importantly, the fourth edition of the WHO classification for malignant lymphomas, published in 2008 (updated in 2016) and used by pathologists and hematologists worldwide, has adopted the terminology and definitions of the WHO-EORTC classification; therefore, it now includes all the types of CTCL and CBCL included in previous classifications of primary cutaneous lymphomas4. The frequency and survival of patients with the different types of CTCL recognized in the WHO-EORTC classification are presented in Table 120.1. Following a description of practical guidelines for diagnosis, classification and staging, relevant features of the different types of CTCL included in this classification are presented.

WHO-EORTC CLASSIFICATION FOR CUTANEOUS T-CELL LYMPHOMAS

Frequency (%)*

5-year survival rate (%)*

Mycosis fungoides (MF)

54

88

Mycosis fungoides variants • Folliculotropic MF • Pagetoid reticulosis • Granulomatous slack skin

6 1

isotretinoin), pityriasis rubra pilaris (acitretin and isotretinoin), cutaneous T-cell lymphoma (bexarotene), and chronic hand eczema (alitretinoin) ■ Systemic retinoid therapy requires careful patient selection and monitoring due to associated teratogenicity and other potential toxicities; laboratory abnormalities (e.g. hypertriglyceridemia, elevated transaminases); ocular, musculoskeletal, and (primarily for bexarotene) endocrinologic or hematologic adverse effects

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been formulated and has efficacy similar to that of topical tretinoin for acne. In 1999, the US Food and Drug Administration (FDA) approved 9-cis-retinoic acid (9-cis-RA; alitretinoin) 0.1% gel for the topical treatment of cutaneous Kaposi sarcoma. To date, oral alitretinoin has been approved outside of the US to treat severe, recalcitrant hand eczema. In 1972, Bollag developed two aromatic retinoids: etretinate and its free acid metabolite, acitretin. Both had a therapeutic index ten times more favorable than that of tretinoin in the chemically induced rodent papilloma test model. Etretinate and acitretin represent secondgeneration retinoids, and their development constituted a breakthrough in the systemic treatment of psoriasis and disorders of cornification. A major advance in understanding the molecular pharmacologic features and mechanisms of action of retinoids came with the discovery of nuclear receptors known as retinoic acid receptors (RARs) and retinoid X receptors (RXRs). This allowed the development of new retinoids that target specific retinoid receptors. Third-generation retinoids include topical adapalene (acne), topical tazarotene (psoriasis and acne), and oral as well as topical bexarotene (cutaneous T-cell lymphoma [CTCL]). Lastly, topical retinol and retinaldehyde, the precursors of retinoic acid, are included in cosmeceutical products.

MECHANISM OF ACTION Retinoids are involved in the regulation of diverse biologic functions (Table 126.1). They affect cellular growth, differentiation and morphogenesis; inhibit tumor promotion and malignant cell growth; exert immunomodulatory actions; and alter cellular cohesiveness4.

INTRODUCTION

Vitamin A Metabolism

Vitamin A (retinol) and related compounds with either structural (retinol derivative) or functional (vitamin A activity) similarities are known as retinoids (Fig. 126.1). The importance of retinoids in cutaneous biology was first appreciated early in the twentieth century by Wolbach1, who observed that vitamin A-deficient animals manifested altered keratinization, such as epidermal hyperkeratosis and squamous metaplasia of mucous membranes as well as certain precancerous conditions. The anti-keratinizing properties of vitamin A led von Stuettgen and Bollag to administer topical and systemic retinoids to treat disorders of cornification. In initial clinical trials with oral vitamin A, tolerable doses were ineffective but higher, potentially effective doses were too toxic. Because of this narrow therapeutic window, a program was launched to engineer synthetic retinoids with higher therapeutic activity and lower toxicity. Parallel to efforts with systemic agents, a growing interest in topical retinoids emerged. All-trans-retinoic acid (at-RA; tretinoin), a naturally occurring metabolite of retinol (see Fig. 126.1), was the first retinoid to be synthesized. Orally, it did not have significant advantages over vitamin A, and, as a result, the primary dermatologic focus became its topical use, especially for acne vulgaris and photoaging. However, oral tretinoin is an important component of therapeutic regimens for acute promyelocytic leukemia, where its ability to promote cellular differentiation is utilized. Initially synthesized in 1955, 13-cis-retinoic acid (13-cis-RA; isotretinoin) was first studied clinically almost two decades later. Its use was delayed by concerns regarding its teratogenicity, which were amplified because of the thalidomide tragedy. Results of isotretinoin treatment of psoriasis were equivocal, and etretinate was subsequently found to be more effective. In the mid to late 1970s, Peck and colleagues2,3 described the effectiveness of oral isotretinoin in the treatment of lamellar ichthyosis and other disorders of cornification as well as its ability to produce complete responses with prolonged remissions in patients with treatment-resistant nodulocystic acne. Topical isotretinoin has also

Vitamin A (retinol) must be acquired through the diet and is ingested as retinyl esters and provitamin A carotenoids; of the latter, betacarotene is particularly efficient in its ability to be converted to vitamin A. Within the intestinal lumen, retinyl esters are hydrolyzed to retinol, which is then absorbed and stored in the liver in the ester form (especially retinyl palmitate; Fig. 126.2). Retinol and its esters represent the main dietary source, as well as transport and storage form, of vitamin A. Once inside the bloodstream, after release of the retinyl ester (storage form) from the liver, retinol is transported bound to a complex of retinol-binding protein (RBP) and transthyretin. The uptake of retinol from the RBP–transthyretin complex to target cells is mediated by STRA6 (stimulated by retinoic acid 6), a dimeric transmembrane protein that acts as an RBP–retinol receptor5,6. The cellular pathway leading to conversion of retinol to at-RA, the biologically active ligand that binds to nuclear receptors, consists of a two-step process (see Figs 126.1 & 126.2). Retinol (vitamin A alcohol) is first reversibly oxidized to retinaldehyde (vitamin A aldehyde), which is then irreversibly converted to retinoic acid (vitamin A acid). Cellular RBP (CRBP-I) facilitates these enzymatic reactions by delivering retinol to appropriate enzymes. Two additional intracellular carriers, cellular retinoic acid-binding proteins (CRABP-I and CRABP-II), are thought to function in transporting retinoic acid to the nucleus as well as buffering the level of free at-RA in the cell. The latter is accomplished by sequestering at-RA and by promoting metabolism of at-RA by cytochrome P450 enzymes belonging to the CYP26 family (e.g. CYP26A1). CRABP-I regulates the metabolic fate of its ligands by directly affecting the activities of RA-metabolizing cytochrome P450 enzymes, while CRABP-II markedly stimulates the RA-induced transcriptional activity of RAR through protein–protein interactions7,8. Intracellularly, retinoic acid is found in both all-trans and 9-cis configurations (see Fig. 126.2). Physiologically, at-RA is the predominant

Retinoids are analogs of vitamin A that exert multiple effects on cellular differentiation and proliferation, the immune system, and embryonic development. A thorough understanding of their mechanisms of action, formulations, administration, and potential adverse effects enables dermatologists to effectively and safely treat patients with a variety of cutaneous disorders. Topical retinoids are used to treat a number of conditions including acne, photoaging, and psoriasis, with skin irritation representing a limiting factor. Oral retinoids are the most effective drugs available for severe acne (isotretinoin) and many disorders of cornification (acitretin and isotretinoin), and they are also helpful in the management of inflammatory and neoplastic skin diseases; careful patient selection and monitoring are required due to their teratogenicity and other potential toxicities.

vitamin A, retinoids, retinol, retinaldehyde, retinoic acid, isotretinoin (13-cis-retinoic acid), alitretinoin (9-cis-retinoic acid), acitretin, bexarotene, tazarotene, adapalene, tretinoin (all-trans-retinoic acid)

CHAPTER

126 Retinoids

ABSTRACT

non-print metadata KEYWORDS:

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CHAPTER

126 Retinoids

CHEMISTRY OF RETINOIDS Biosynthesis of retinoic acid from retinol (vitamin A) H3C

CH3

CH3

CH3

H3C

CH2OH

CH3

CH3

CH3

H3C

CHO

CH3

CH3

CH3

CO2H

CH3

Retinaldehyde*

Retinol* (vitamin A)

CH3

CH3

All-trans-retinoic acid* (tretinoin)

Chemical structure of retinoids H3C

CH3

CH3

CH3

CH3

HO

H3C

CH3

O

CH3

CH3

CH3O

CH3

13-cis-retinoic acid* (isotretinoin)

CH3

H3C

CH3

COOH

CH3

CH3 COOC2H5

H2C H3CO

Acitretin

H3C

Etretinate

COOH

9-cis-retinoic acid* (alitretinoin) O

O

* Naturally occurring retinoids

OCH2CH3

OH

First-generation retinoids Second-generation retinoids Third-generation retinoids

CH3

H 3C

CH3O

CH3

H3C

CH3

CH2

N

S

Adapalene

H3C

Tazarotene

CH3

COOH

Bexarotene

Fig. 126.1 Chemistry of retinoids.  

BIOLOGIC FUNCTIONS OF RETINOIDS

Functions of vitamin A (retinol)* Embryonic growth Morphogenesis • Differentiation and maintenance of epithelial tissues • Reproduction (retinol) • Visual function (retinaldehyde) • •

Biologic effects of retinoids Modulation of proliferation and differentiation Anti-keratinization • Alteration of cellular cohesiveness • Anti-acne and antiseborrheic effects • Immunologic and anti-inflammatory effects • Tumor prevention and therapy • Induction of apoptosis • Effects on extracellular matrix components • •

*Retinoic acid can substitute for retinol with regard to growth, morphogenesis, and epithelial differentiation; it cannot substitute completely for retinol in reproductive function, nor can it replace retinaldehyde in the visual system.

Table 126.1 Biologic functions of retinoids.  

retinoic acid form, and only a very small fraction is isomerized into 13-cis-RA. at-RA is the primary active ligand that binds to the three known nuclear RARs, which mediate, at least in part, the molecular and cellular effects of retinoic acid.

Retinoid Receptors Retinoids exert most of their physiologic effects on DNA transcription by binding to two distinct families of nuclear receptors, RARs and RXRs. These receptor families belong to a superfamily of nuclear receptors that act as ligand-activated transcription factors and include the

steroid, vitamin D3, and thyroid hormone receptors as well as peroxisome proliferator-activated receptors (PPARs). The RAR and RXR receptor families each contain three receptor isotypes (α, β and γ) encoded by different genes. at-RA (tretinoin) binds only to RARs, whereas 9-cis-RA (alitretinoin) binds both to RARs and RXRs (Table 126.2). RARs function as heterodimers with RXRs, whereas RXRs may also act as homodimers or participate in the formation of heterodimers with a variety of other nuclear receptors, including vitamin D3, thyroid hormone, and PPARs. Such heterodimers provide a mechanism for cross-talk between nuclear hormone signaling pathways. Dimers of retinoid receptors (RAR/RXR or RXR/RXR) are localized to the nucleus and bind, even in the unliganded state, to specific DNA regulatory sequences called retinoid hormone response elements (RAREs) in the promoter regions of retinoid-responsive genes (see Fig. 126.2). Unliganded receptors bind to co-repressor molecules and repress transcription. However, when the receptor binds its ligand, it undergoes a conformational change resulting in the release of co-repressors and recruitment of co-activators. These molecules include histone acetylases that change the conformation of chromatin and allow access to DNA by transcriptional machinery. The retinoid–receptor complex thereby modulates the transcription of specific sets of genes, and it is likely that many of the differentiation-inducing actions of retinoids are mediated by this mechanism. In addition to direct upregulation of gene transcription via binding of retinoid–receptor complexes to RAREs, retinoids can have indirect effects on gene transcription that result from the downregulation of genes that do not contain RAREs in their promoter region. The retinoid–receptor complex is thought to antagonize transcription factors such as activator protein-1 (AP1) and nuclear factor-interleukin-6 (NFIL6) by competing for the same set of required co-activator proteins, thereby leading to decreased expression of AP1 and NF-IL6-responsive genes; expression of the latter genes promotes cellular proliferation and inflammation. The antiproliferative and anti-inflammatory actions of retinoids are believed to be mediated by this type of indirect negative gene regulation. In particular, retinoic acid has important roles in

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SECTION

Medical Therapy

19

METABOLISM AND MECHANISM OF ACTION OF NATURAL RETINOIDS

Retinyl esters β-Carotene (diet)

Chylomicrons−RE Lipoproteins−RE

Intestinal lumen (hydrolysis to retinol)

Lymphatic vessels Bloodstream

Esterification to RE in intestinal mucosa

Retinol−RBP−transthyretin complex (systemic circulation)

STRA6 receptor for retinol−RBP Keratinocyte

Liver (storage)

ARAT/LRAT Retinol−CRBP REH RE Retinaldehyde (vision)

All-trans-RA−CRABP (tretinoin)

Polar derivatives (biological activity?)

13-cis-RA

9-cis-RA Co-activators

VDR TR PPAR

Gene Differentiation transcription Proliferation Immune RNA responses RAR RXR polymerase II Inflammatory

Hormone response element Retinoid-responsive genes Nucleus

Fig. 126.2 Metabolism and mechanism of action of natural retinoids. ARAT, acyl-CoA:retinol acyl transferase; CRABP, cellular retinoic acid-binding protein; CRBP, cellular retinol-binding protein; LRAT, lecithin:retinol acyl transferase; PPAR, peroxisome proliferator-activated receptor; RA, retinoic acid; RAR, retinoic acid receptor; RBP, retinol-binding protein; RE, retinyl esters; REH, retinyl ester hydrolase; RXR, retinoid X receptor; STRA6, stimulated by retinoic acid 6; TR, thyroid receptor; VDR, vitamin D3 receptor.  

oxidative stress can also lead to lowered retinoid levels in the skin9. There has been an ongoing debate regarding possible generation of reactive oxygen species upon the interaction of UVA radiation with retinyl esters (e.g. retinyl palmitate) present in cosmetics and sunscreens, but the theoretical potential for photocarcinogenicity has not been shown to be clinically relevant.

Synthetic Retinoids Three generations of synthetic retinoids have been developed (see Fig. 126.1). The first-generation non-aromatic retinoids (tretinoin, isotretinoin, alitretinoin) are produced by chemically modifying the polar end group and the polyene side chain of vitamin A. Second-generation mono-aromatic retinoids (etretinate, acitretin) are formed by replacing the cyclic moiety of vitamin A with different substituted and unsubstituted ring systems. The third-generation poly-aromatic retinoids (adapalene, bexarotene, tazarotene), called arotinoids, are produced by cyclization of the polyene side chain. Commercially available retinoids differ not only in their spectrum of clinical efficacy but also in their observed toxicity and pharmacokinetics. Each retinoid should be investigated as a unique drug, and the lack of disease response to one retinoid does not necessarily signify unresponsiveness to other retinoids. The oral bioavailability of all retinoids is considerably enhanced when administrated with food, especially with a fatty meal, due to their lipophilic properties. Retinoid metabolism is predominantly hepatic; it involves oxidation and chain shortening to biologically inactive and polar metabolites, facilitating biliary and/or renal elimination. The oxidative metabolism is induced by the retinoids themselves and possibly also by other agents known to stimulate hepatic cytochrome P450 isoforms. Table 126.2 summarizes the key pharmacologic features and nuclear binding profiles of retinoids used in dermatology.

Adapalene Adapalene is a photostable, rigid, and highly lipophilic synthetic retinoid with higher affinity for RAR-β/γ than for RAR-α. Since RAR-β is not expressed in keratinocytes, RAR-γ is the primary target receptor for adapalene in the epidermis. Adapalene does not bind to cellular retinoic acid-binding proteins (CRABPs) but does induce expression of CRABP-II. Its lipophilic properties may contribute to better pilosebaceous uptake and anti-acne activity. Given its negligible transdermal absorption, the teratogenic risks of topical adapalene appear to be minimal. While adapalene affects the cellular differentiation, keratinization, and inflammatory processes that are abnormal in acne, it has no sebostatic effect.

Tazarotene inhibiting IL6-driven induction of proinflammatory Th17 cells and in promoting differentiation of anti-inflammatory regulatory T cells. The anti-inflammatory effects of at-RA (tretinoin) have also been associated with its ability to regulate the expression and activation of Toll-like receptors (TLRs), especially TLR2. The biologic relevance of nongenomic effects of retinoids (e.g. phosphorylation, membrane effects) remains under investigation. The existence of several types and varied distributions of receptors, dimers, hormone response elements, and regulatory proteins shows that retinoid action is mediated via multiple pathways and results in a complex process of activation or inhibition of a large set of coordinately regulated genes However, the exact mechanism of retinoid action in many dermatologic conditions is still unknown, and, so far, the nuclear receptor concept does not fully explain the biologic diversity of retinoid effects.

Retinoids in the Skin

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Vitamin A and its bioactive metabolites play a major role in promoting the keratinocyte differentiation that occurs from the epidermal basal layer to the stratum corneum9. Retinyl esters and retinol are the major retinoids found in the skin, with the former reaching a concentration of >1000 pmol/g in the epidermis. Epidermal retinoids can absorb UVB radiation and have ~2–3% of the UVB-filtering capacity of the melanin in phototype II/III skin9,10. The UVB absorption process results in dramatic depletion of epidermal retinoids, which can be prevented by application of topical retinoids11,12. Nutritional deficiency, aging, and

Tazarotene is a prodrug that is rapidly converted by cutaneous esterases to its free carboxylic acid (tazarotenic acid), which is the active metabolite. It has a higher affinity for RAR-β/γ than for RAR-α and no affinity for RXR. Because of its rapid metabolism, systemic exposure is low. Tazarotene appears to modulate the pathogenesis of psoriasis by regulating expression of retinoid responsive genes, including those involved in cell proliferation, cell differentiation, and inflammation.

Acitretin Acitretin is the major metabolite and the pharmacologically active form of etretinate. Although acitretin and etretinate are equally effective, acitretin has much more rapid elimination. Etretinate is approximately 50 times more lipophilic than acitretin and binds strongly to plasma proteins, particularly lipoproteins and albumin. Etretinate is stored in adipose tissue (including subcutaneous fat), from which it is released slowly, with a long terminal half-life of up to 120 days. Under identical conditions, acitretin carries a negatively charged group that makes it much less lipophilic than etretinate. As a result, acitretin does not accumulate in adipose tissue and is eliminated from the body more rapidly, with a half-life of 2 days. The major serious adverse effect of oral retinoids is teratogenicity, and, therefore, the length of time that these drugs are present in the body is of great importance. Re-esterification of acitretin to etretinate may occur when acitretin is taken simultaneously with alcohol. This finding prompted the manufacturer to extend the time of contraception for female patients with childbearing potential taking acitretin to 2 years after its discontinuation, as it is for etretinate. The FDA advises

CHAPTER

126

KEY PHARMACOLOGIC FEATURES AND NUCLEAR BINDING PROFILE OF RETINOIDS

Retinoid

Type

Nuclear receptor binding affinity Elimination half-life

RAR

Retinoids

Systemic absorption or bioavailability* (% dose)

RXR

Metabolism

Excretion

α

β

γ

α

β

γ

Topical retinoids* Tretinoin** (all-transretinoic acid)

Natural (1st generation)

30% of the body surface area is not recommended. Calcipotriene is the US Adopted Name (USAN) and calcipotriol is the International Nonproprietary Name (INN).  

face and in intertriginous areas. Allergic contact dermatitis has been described with calcipotriene. The systemic effects of vitamin D and its analogues include releasing calcium from the bone, increasing renal tubular reabsorption and intestinal absorption of calcium, and decreasing parathyroid hormone release. Use of excessive amounts of topical vitamin D analogues can lead to hypercalcemia and hypercalciuria. Parathyroid hormone levels should be monitored if use exceeds recommended amounts (see Table 129.9). Patients with renal disease and those receiving medications that can increase the serum calcium level (e.g. thiazide diuretics, high doses of oral vitamin D) may be at increased risk of developing hypercalcemia.

Use in pregnancy Calcipotriene and calcitriol are pregnancy category C.

MISCELLANEOUS AGENTS Topical Sirolimus (Rapamycin) Introduction, dosages, and indications Sirolimus (rapamycin) is a mammalian target of rapamycin (mTOR) inhibitor with antiproliferative and immunomodulatory effects. Uses of systemic sirolimus include rejection prophylaxis and probable reduction of cutaneous SCC risk in solid organ transplant recipients; prophylaxis and treatment of GVHD; and treatment of lymphangioleiomyomatosis and other tumors associated with tuberous sclerosis complex (TSC; see Ch. 61), Kaposi sarcoma, kaposiform hemangioendothelioma, and lymphatic malformations51. Topical sirolimus has been utilized to treat angiofibromas, other TSC-related skin lesions, port-wine stains (together with pulsed dye laser therapy), and psoriasis52–59. Topical application of sirolimus 0.1–1% ointment, gel, cream, or solution (compounded or Rapamune® 1 mg/ml[0.1%]) once or twice daily to the facial angiofibromas of TSC usually leads to flattening and reduced erythema within 3 months, with better results in children than adults53–58.

Mechanism of action Sirolimus binds to the FK506 binding protein FKBP12, forming a complex that inhibits mTOR (see Fig. 61.11). This leads to reduced proliferation and protein synthesis of T lymphocytes and other immune cells as well as decreased vascular endothelial growth factor (VEGF) production.

Side effects Local skin irritation is more common with a gel or solution formulation than with an ointment53,54. Little to no systemic absorption has been observed with topical therapy54–58.

Diclofenac Sodium Diclofenac sodium 3% in a gel vehicle containing hyaluronic acid is FDA-approved for treatment of AKs. This NSAID inhibits cyclooxygenase (COX)-2 and (to a lesser degree) COX-1. Its mechanism of action against AKs is thought to involve induction of apoptosis, alteration of cellular proliferation, and inhibition of angiogenesis. Twice-daily application for 60–90 days results in AK clearance rates of up to 30–50%, with potential side effects including irritant, allergic, and photoallergic contact dermatitis. Diclofenac is pregnancy category B.

CHAPTER

129 Other Topical Medications

Use in pregnancy

Ingenol Mebutate Ingenol mebutate, a diterpene ester from the Euphorbia peplus plant, is FDA-approved as a topical treatment for AKs60–62. Application of ingenol mebutate 0.015% or 0.05% gel to areas with AKs on the face/ scalp or trunk/extremities, respectively, once daily for 2–3 consecutive days leads to a clearance rate of ~40%. This agent induces cell death in proliferating keratinocytes via disruption of the plasma membrane and mitochondria; it also triggers an inflammatory response that eradicates residual tumor cells60–62. Erythema, scaling, and crusting develop in most patients60; less frequently, swelling, vesiculation, ulceration, and dyspigmentation occur. Ingenol mebutate is pregnancy category C.

Tar Introduction and indications Topical tar has served as a skin-directed therapy for >2000 years, since the Greek physician Dioscorides applied “asphalt” to manage several cutaneous diseases63. Among the various types of tar (e.g. wood, bituminous [shale], petroleum, coal), coal tar is most often used as a dermatologic treatment. Currently, tar is utilized primarily in the management of psoriasis and several forms of dermatitis (e.g. seborrheic, nummular, atopic), most commonly in conjunction with other therapeutic modalities. The classic Goeckerman regimen employs topical tar in combination with UVB radiation for the treatment of psoriasis64.

Dosages Coal tar in concentrations of 0.5% to 10% is available or can be compounded in a broad range of vehicles, including ointment, lotion, gel, foam, solution, oil, shampoo, and soap. Liquor carbonis detergens is a distillate of crude coal tar that is typically used in concentrations of 3–10%.

Mechanism of action Coal tar is thought to suppress DNA synthesis, which may lead to normalization of epidermal differentiation in conditions such as psoriasis63. It appears to have anti-inflammatory, antimicrobial, and antipruritic effects. In animal studies, tar has been found to decrease sebum secretion. Coal tar (but not other forms of tar) has a photosensitizing effect in the 330–550 nm range of the UVA and visible light spectra63.

Side effects The unpleasant odor, messiness, and staining potential of topical tar limit its use. Acneiform eruptions, folliculitis, and irritant contact dermatitis (including pustules within plaques of psoriasis) may occur at application sites, and “tar smarts” can develop following exposure to UVA radiation. Ever since Sir Percivall Pott described an increased risk of scrotal cancer in chimney sweepers in 1775, tar has been implicated as a potential carcinogen63. However, the evidence that topical tar formulations used in the treatment of skin disease result in an increased risk of skin cancer is inconclusive.

Use in pregnancy Coal tar is pregnancy category C.

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19

Anthralin

Mechanism of action

Medical Therapy

SECTION

Introduction, dosages, and indications Anthralin, the synthetic form of the chrysarobin found in the bark of the South American araroba tree, has been used to treat dermatologic conditions for >80 years65. It is available in 0.5% and 1% creams. Although no longer commonly used for psoriasis, short-contact anthralin therapy, with gradual increases in the application time ± concentration, continues to be employed to treat alopecia areata via induction of an irritant effect (Table 129.10)65.

Podophyllin and podophyllotoxin act by arresting mitosis through reversible binding to tubulin.

Mechanism of action Anthralin induces a brisk inflammatory response at sites of application, which may result from generation of extracellular oxygen free radicals65. Inhibition of mitochondrial respiration and cell growth are thought to reduce keratinocyte proliferation and lead to antipsoriatic effects.

Side effects Use of anthralin is limited by irritation at application sites (depending on the concentration and contact time) and staining of skin, clothing, and household items (e.g. bed sheets, furniture). Staining and irritation can be ameliorated by application of triethanolamine 10% cream to treatment sites after removal of the anthralin-containing product.

Use in pregnancy Anthralin is pregnancy category C.

Podophyllin and Podophyllotoxin Introduction, dosages, and indications Podophyllin resin is a crude extract from the May apple plant (Podophyllum peltatum or Podophyllum emodi) that has been employed for decades to treat condylomata acuminata. However, the concentration of its most active ingredient is not standardized in the 10–25% solutions that are applied in the physician’s office weekly and washed off 1 to 4 hours later66. In contrast, podophyllotoxin is available in a stable and standardized 0.5% solution and gel as well as a 0.15% cream. These compounds lack the mutagens that are found in podophyllin and can be applied by the patient, usually twice daily for three consecutive days each week for 4–6 weeks. Reported clearance rates for condylomata acuminata range from 30–60% with podophyllin and from 45–75% with podophyllotoxin66.

SAMPLE PROTOCOL FOR SHORT-CONTACT ANTHRALIN THERAPY FOR ALOPECIA AREATA Anthralin 0.5% cream is applied sparingly to affected areas of the scalp daily, followed by washing with shampoo/soap and water • An initial application time of 10 minutes is increased in 10-minute increments every 4–5 days until slight irritation (e.g. erythema, scaling, pruritus) occurs • If excessive irritation develops, treatment is withheld for several days and resumed at the last tolerated application time • If there is no irritation with a 60-minute contact time, 1% anthralin is applied for 10 minutes and application times increased as above • If there is no irritation with 1% anthralin applied for 60 minutes, overnight application is considered • Initial responses are typically seen within 12 weeks; cosmetically acceptable responses require a mean of 24 weeks •

Additional information Brownish staining of treated areas of the scalp and hair is expected To prevent staining of clothing, bedding and furniture, patients should wash their hands thoroughly after applying anthralin and avoid touching fabrics with their scalp until it has been washed off • Avoid getting anthralin into the eyes; do not apply to eyelids or eyelashes • Special care should be taken in sensitive areas (areas of scalp near the ears, eyebrows) • •

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Table 129.10 Sample protocol for short-contact anthralin therapy for alopecia areata. Courtesy, Julie V Schaffer, MD, and Jean L Bolognia, MD.  

Side effects Common adverse effects associated with both podophyllin and podophyllotoxin include burning, erythema, and skin breakdown at application sites. The extent of irritation may be reduced by application of petrolatum to unaffected surrounding skin. Because of its percutaneous absorption, application of large amounts of podophyllin can result in systemic toxicity (see Table 129.6).

Use in pregnancy Use of podophyllin during pregnancy is contraindicated due to its teratogenic effects. However, podophyllotoxin is pregnancy category C.

Cantharidin Introduction, dosages, and indications Cantharidin is a vesicant derived from “blister beetles” in the Coleoptera order and Meloidae family. It has been used since the 1950s to treat warts and molluscum contagiosum. Although cantharidin met the safety requirements outlined by the Food, Drug, and Cosmetic Act of 1938, it lost its FDA approval in 1962 when its manufacturers failed to submit required efficacy data67. A 0.7% concentration of cantharidin is currently available in a film-forming collodion vehicle; another formulation (primarily used for warts) combines 1% cantharidin with 2% podophyllin and 30% salicylic acid. A thin film of cantharidin is typically applied to lesions in the office. After drying, occlusion may be used. The residual film is washed off thoroughly with soap and water or rubbing alcohol by the patient (or a parent) 2 to 6 hours after application. Blisters typically form over the next 12–24 hours, followed by superficial erosions; healing of treated areas (with temporary residual erythema) occurs over a period of 4–7 days67. Benefits of cantharidin use include painless application (particularly advantageous in young children) and a lack of scarring.

Mechanism of action Cantharidin acts via release of neutral serine proteases that cause desmosomal plaque degeneration, leading to detachment of desmosomes from tonofilaments; resultant acantholysis is intraepidermal and therefore non-scarring67.

Side effects The blisters and erosions that form after cantharidin treatment can be painful or pruritic, and postinflammatory hypopigmentation may take several months to resolve. Use of cantharidin to treat warts occasionally results in a “doughnut wart” due to clearance in the center but not at the periphery of the lesion. Cantharidin poisoning has been described following ingestion, with sequelae including blistering and erosions in the mouth and gastrointestinal tract as well as dysuria, hematuria, and renal failure. Standard in-office application of cantharidin, however, does not generally cause systemic effects.

Sulfur Introduction Sulfur, a yellow non-metallic element, has been employed as a treatment for seborrheic dermatitis, rosacea, acne, tinea versicolor, and scabies. Sulfur is typically used in concentrations of 2–10%, often in combination with a second agent, e.g. 2% sulfur plus 2% salicylic acid in shampoos (for seborrheic dermatitis) or 5% sulfur plus 10% sodium sulfacetamide in a cream, suspension, or gel (for rosacea, acne, and seborrheic dermatitis; see Ch. 127). Application of 5–10% sulfur ointment to the entire body for 2–3 consecutive nights represents a classic scabies treatment; however, it is inferior to topical permethrin therapy.

Mechanism of action Sulfur has antibacterial, antifungal, and keratolytic properties.

CHAPTER

An offensive odor similar to that of rotten eggs limits the use of sulfur in the absence of masking fragrances. Side effects are generally mild and include dryness and pruritus.

Contraindications Topical sulfur is contraindicated in patients with a sensitivity to sulfur.

Use in pregnancy Topical sulfur (5–10%) has been used to treat scabies in young infants and pregnant or lactating women, but safety data are lacking.

Azelaic Acid Introduction and indications Azelaic acid, a naturally occurring dicarboxylic acid, is used in the treatment of rosacea, acne, melasma, and postinflammatory hyperpigmentation.

Mechanism of action Azelaic acid inhibits the production of free radical oxygen by neutrophils. This reduces oxidative tissue injury at sites of inflammation and decreases melanin production. Studies have also demonstrated selective cytotoxic and antiproliferative effects on hyperactive and abnormally proliferating melanocytes, with little effect on normal melanocytes. It may act as a competitive inhibitor of tyrosinase, further explaining its skin-lightening effects68,69. In addition, azelaic acid has antimicrobial activity against Propionibacterium acnes and Staphylococcus epidermidis as well as moderate anticomedogenic properties via modification of epidermal keratinization.

SAMPLE PROTOCOL FOR TOPICAL IMMUNOTHERAPY WITH SQUARIC ACID DIBUTYL ESTER FOR CUTANEOUS WARTS Sensitize with a 2% SADBE solution in acetone applied to a small (e.g. 2 cm × 2 cm) area on the inner aspect of the upper arm or medial thigh; cover with a dressing and do not wash for 24 hours • After 1 week (2 weeks if the initial reaction was severe), apply 0.2% SADBE solution to non-facial warts; cover with a light dressing and wash after 12–24 hours • Apply approximately twice weekly to warts; can increase or decrease the length of time between treatments depending on the duration of the reaction, with repeat application once the erythematous/eczematous reaction has subsided • If there is no inflammation or response of the warts after 2–4 weeks, increase the concentration to 0.5% (and subsequently to 1% and 2% as needed); decrease concentration (e.g. from 0.2% to 0.1%) and/or amount applied if excessive inflammation, e.g. more than mild erythema and pruritus • Responses are usually seen within 3 months, with complete clearance in 60–80% of patients after a mean of 6–8 weeks •

129 Other Topical Medications

Side effects

Additional information The acetone solution should be applied using a cotton-tip applicator SADBE should be refrigerated and protected from light • Side effects include severe or widespread eczematous reactions (which can be treated with topical or, if required, systemic corticosteroids), lymphadenopathy, and postinflammatory pigment alterations (especially in patients with darkly pigmented skin) • •

Table 129.11 Sample protocol for topical immunotherapy with squaric acid dibutyl ester (SADBE) for cutaneous warts. This is not an FDA-approved medication.  

Dosages Azelaic acid, available in a 20% cream and 15% gel, is applied twice daily.

TRADITIONAL TOPICAL MEDICATIONS

Agent

Components

Classic uses

1-2-3 paste

Burow’s solution, petrolatum, zinc oxide

In the diaper area as a protective barrier to treat and prevent irritant dermatitis Hand eczema, erosions, ulcerations

Aqueous silver nitrate 10% solution*

Silver nitrate

Small recalcitrant ulcerations Excess granulation tissue, bleeding – silver nitrate applicators (“sticks”)

Black cat*

Acetone, collodion, crude coal tar

Psoriasis, lichen simplex chronicus, nummular eczema, hypertrophic lichen planus

Burow’s solution

Aluminum acetate

Weeping, macerated, and/or (super)infected skin conditions, especially in intertriginous and acral sites (e.g. acute allergic contact dermatitis, tinea pedis/cruris, candidiasis)

Calamine lotion

Zinc oxide, ferric oxide, glycerin, bentonite magma, calcium hydroxide solution (lime water)

Acute and subacute pruritic dermatoses, especially acute allergic contact dermatitis

Castellani’s paint (carbol fuchsin)

Phenol, resorcinol, basic fuchsin (without the latter in colorless version)

Fissures, primarily on digits in the setting of chronic hand dermatitis Cutaneous candidiasis, tinea pedis/cruris, pustular dermatoses of the hands and feet

Chrysarobin*

Chrysarobin, chloroform

Chronic paronychia

Fluffy tannic acid powder*

Fluffy tannic acid, bentonite, kaolin

Hyperhidrosis, contact dermatitis of the hands/feet

Gentian violet solution

Gentian violet

Candidiasis, tinea pedis/cruris

P&S® liquid

Mineral oil, glycerin, phenol

Psoriasis/sebopsoriasis with excessive hyperkeratosis (especially of the scalp)

Potassium permanganate

KMnO4

Weeping, macerated, and/or (super)infected skin conditions, especially in intertriginous and acral sites (e.g. tinea cruris/pedis, candidiasis)

Schamberg’s lotion*

Menthol, phenol, zinc oxide, calcium hydroxide solution, olive oil

Acute and subacute pruritic dermatoses

Whitfield’s ointment

Benzoic acid (6%), salicylic acid (3%)

Tinea pedis

*Primarily of historical interest. Table 129.12 Traditional topical medications.  

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SECTION

Medical Therapy

19

Side effects Azelaic acid may cause mild to moderate irritant contact dermatitis (e.g. dryness, peeling, erythema), which often subsides after 2 to 4 weeks of treatment.

Use in pregnancy

EXAMPLES OF NEWER PRESCRIPTION BARRIER-REPAIR/ MOISTURIZING AGENTS

Agent

Active ingredients

Atopiclair®/

Glycyrrhetinic acid (licorice root), Vitis vinifera (grape vine) extract, Butyrospermum parkii (shea butter), hyaluronic acid, telmesteine

Pruclair™ cream

Azelaic acid is pregnancy category B.

Topical Immunotherapy A sample protocol for topical immunotherapy with squaric acid dibutyl ester (SADBE) for cutaneous warts is outlined in Table 129.11, and a protocol for SADBE or diphencyprone for alopecia areata is presented in Table 69.7.

The Old and the New Topical agents of historical interest are presented in Table 129.12. Many newer barrier-repair creams and moisturizers have purported benefit in the management of various dermatoses, such as atopic dermatitis and irritant contact dermatitis; examples of these agents and their active ingredients are listed in Table 129.13.

Eletone® cream

70% oil (mineral oil, white petrolatum) dispersed in 30% water

EpiCeram® emulsion

3 : 1 : 1 molar ratio of ceramide, cholesterol and free fatty acids (e.g. capric, linoleic, palmitic acids)

Hylatopic® (Plus) emollient foam cream, and lotion

Theobroma grandiflorum seed butter, hyaluronic acid, ceramide (latter in “Plus” version)

MimyX®/PruMyx™ cream

Palmitamide monoethanolamine, palm glycerides, hydrogenated lecithin, squalane, olive oil

Neosalus® foam

Dimethicone, stearic acid

Promiseb™ cream

Glycyrrhetinic acid, Vitis vinifera extract, Butyrospermum parkii, piroctone olamine, hydrogenated castor oil, telmesteine

Tetrix™ cream

Aluminum magnesium hydroxide stearate, cyclomethicone, dimethicone, hexyl laurate

For additional online figures visit www.expertconsult.com

Table 129.13 Examples of newer prescription barrier-repair/moisturizing agents. These agents are FDA-approved as “medical devices” and available by prescription. Over-the-counter barrier-repair moisturizers containing ceramides or “pseudoceramides” and filaggrin breakdown products are also available.  

REFERENCES

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1. Long CC, Finlay AY. The finger-tip unit–a new practical measure. Clin Exp Dermatol 1991;16:444–7. 2. Hercogova J. Topical anti-itch therapy. Dermatol Ther 2005;18:341–3. 3. Draelos ZD. Skin lightening preparations and the hydroquinone controversy. Dermatol Ther 2007;20:308–13. 4. Torok HM, Jones T, Rich P, et al. Hydroquinone 4%, tretinoin 0.05%, fluocinolone acetonide 0.01%: a safe and efficacious 12-month treatment for melasma. Cutis 2005;75:57–62. 5. Dorsey CS. Dermatitic and pigmentary reactions to monobenzyl ether of hydroquinone: report of two cases. Arch Dermatol 1960;81:245–8. 6. Price VH. Treatment of hair loss. N Engl J Med 1999;341:964–73. 7. Messenger AG, Rundegren J. Minoxidil: mechanisms   of action on hair growth. Br J Dermatol 2004;150:  186–94. 8. Smith S, Fagien S, Whitcup SM, et al. Eyelash growth in subjects treated with bimatoprost: a multicenter, randomized, double-masked, vehicle-controlled, parallel-group study. J Am Acad Dermatol 2012;66:801–6. 9. Yoelin S, Walt JG, Earl M. Safety, effectiveness, and subjective experience with topical bimatoprost 0.03% for eyelash growth. Dermatol Surg 2010;36:638–49. 10. Tosti A, Pazzaglia M, Voudouris S, Tosti G. Hypertrichosis of the eyelashes caused by bimatoprost. J Am Acad Dermatol 2004;51:S149–50. 11. Schweiger ES, Pinchover L, Bernstein RM. Topical bimatoprost for the treatment of eyebrow hypotrichosis. J Drugs Dermatol 2012;11:106–8. 12. Beer KR, Julius H, Dunn M, Wilson F. Treatment of eyebrow hypotrichosis using bimatoprost: a randomized, double-blind, vehicle-controlled pilot study. Dermatol Surg 2013;39:1079–87. 13. Cohen JL. Enhancing the growth of natural eyelashes: the mechanism of bimatoprost-induced eyelash growth. Dermatol Surg 2010;36:1361–71. 14. Wolf JE Jr, Shander D, Huber F, et al. Randomized, double-blind clinical evaluation of the efficacy and safety of topical eflornithine HCl 13.9% cream in the treatment of women with facial hair. Int J Dermatol 2007;46:94–8.

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26. Desai T, Chen CL, Desai A, Kirby W. Basic pharmacology of topical imiquimod, 5-fluorouracil, and diclofenac for the dermatologic surgeon. Dermatol Surg 2012;38:97–103. 27. Imbertson LM, Beaurline JM, Couture AM, et al. Cytokine induction in hairless mouse and rat skin after topical application of the immune response modifiers imiquimod and S-28463. J Invest Dermatol 1998;110:734–9. 28. Vaccaro M, Barbuzza O, Guarneri B. Erosive pustular dermatosis of the scalp following treatment with topical imiquimod for actinic keratosis. Arch Dermatol 2009;145:1340–1. 29. Eichenfield LF, Tom WL, Berger TG, et al. Guidelines of care for the management of atopic dermatitis: section 2. Management and treatment of atopic dermatitis with topical therapies. J Am Acad Dermatol 2014;71:116–32. 30. Carroll CL, Fleischer AB Jr. Tacrolimus ointment: the treatment of atopic dermatitis and other inflammatory cutaneous disease. Expert Opin Pharmacother 2004;5:2127–37. 31. Callen J, Chamlin S, Eichenfield LF, et al. A systematic review of the safety of topical therapies for atopic dermatitis. Br J Dermatol 2007;156:203–21. 32. Tennis P, Gelfand JM, Rothman KJ. Evaluation of cancer risk related to atopic dermatitis and use of topical calcineurin inhibitors. Br J Dermatol 2011;165:465–73. 33. Luger T, Boguniewicz M, Carr W, et al. Pimecrolimus in atopic dermatitis: consensus on safety and the need to allow use in infants. Pediatr Allergy Immunol 2015;26:306–15. 34. Legendre L, Barnetche T, Mazereeuw-Hautier J, et al. Risk of lymphoma in patients with atopic dermatitis and the role of topical treatment: a systematic review and meta-analysis. J Am Acad Dermatol 2015;72:992–1002. 35. Thomson MA, Hamburger J, Stewart DG, Lewis HM. Treatment of erosive oral lichen planus with topical tacrolimus. J Dermatolog Treat 2004;15:308–14. 36. Remitz A, Reitamo S. Long-term safety of tacrolimus ointment in atopic dermatitis. Expert Opin Drug Saf 2009;8:501–6. 37. Yan AC, Honig PJ, Ming ME, et al. The safety and efficacy of pimecrolimus, 1%, cream for the treatment

eFig. 129.3 Calcipotriene CALCIPOTRIENE, A VITAMIN D3 ANALOGUE (calcipotriol), a vitamin D3 analogue.  

H

H

HO

OH

CHAPTER

129 Other Topical Medications

Online only content

OH

eFig. 129.1 Reaction to topical 5-fluorouracil. Inflammation with erythema and crusting at sites of actinic keratoses on the forehead.  

CALCITRIOL (1,25-DIHYDROXYVITAMIN D3) THE ACTIVE FORM OF VITAMIN D3 H3C H3C

eFig. 129.2 Calcitriol (1,25-dihydroxyvitamin D3), the active form of vitamin D3.  

CH3 CH3

OH

CH2 HO

OH

2276.e1

52. Ormerod AD, Shah SA, Copeland P, et al. Treatment of psoriasis with topical sirolimus: preclinical development and a randomized, double-blind trial. Br J Dermatol 2005;152:758–64. 53. Tu J, Foster RS, Bint LJ, Halbert AR. Topical rapamycin for angiofibromas in paediatric patients with tuberous sclerosis: follow up of a pilot study and promising future directions. Australas J Dermatol 2014;55:63–9. 54. Haemel AK, O’Brian AL, Teng JM. Topical rapamycin: a novel approach to facial angiofibromas in tuberous sclerosis. Arch Dermatol 2010;146:715–18. 55. Foster RS, Bint LJ, Halbert AR. Topical 0.1% rapamycin for angiofibromas in paediatric patients with tuberous sclerosis: a pilot study of four patients. Australas J Dermatol 2012;53:52–6. 56. DeKlotz CM, Ogram AE, Singh S, et al. Dramatic improvement of facial angiofibromas in tuberous sclerosis with topical rapamycin: optimizing a treatment protocol. Arch Dermatol 2011;147:1116–17. 57. Mutizwa MM, Berk DR, Anadkat MJ. Treatment of facial angiofibromas with topical application of oral rapamycin solution (1mgmL(-1) ) in two patients with tuberous sclerosis. Br J Dermatol 2011;165:922–3. 58. Wataya-Kaneda M, Nakamura A, Tanaka M, et al. Efficacy and safety of topical sirolimus therapy for facial angiofibromas in the tuberous sclerosis complex : a randomized clinical trial. JAMA Dermatol 2017;153:39–48. 59. Marqués L, Núñez-Córdoba JM, Aguado L, et al. Topical rapamycin combined with pulsed dye laser in the treatment of capillary vascular malformations in Sturge-Weber syndrome: phase II, randomized, double-blind, intraindividual placebo-controlled clinical trial. J Am Acad Dermatol 2015;72:151–8. 60. Anderson L, Schmieder GJ, Werschler WP, et al. Randomized, double-blind, double-dummy, vehiclecontrolled study of ingenol mebutate gel 0.025% and 0.05% for actinic keratosis. J Am Acad Dermatol 2009;60:934–43. 61. Ogbourne SM, Suhrbier A, Jones B, et al. Antitumor activity of 3-ingenyl angelate: plasma membrane and mitochondrial disruption and necrotic cell death. Cancer Res 2004;64:2833–9. 62. Berman B, Goldenberg G, Hanke CW, et al. Efficacy and safety of ingenol mebutate 0.015% gel after cryosurgery of actinic keratosis: 12-month results. J Drugs Dermatol 2014;13:741–7. 63. Paghdal KV, Schwartz RA. Topical tar: back to the future. J Am Acad Dermatol 2009;61:294–302. 64. Goeckerman WH. Treatment of psoriasis. Continued observations on the use of crude coal tar and ultraviolet light. Arch Dermatol Syph 1931;24:446–50. 65. Harris DR. Old wine in new bottles: the revival of anthralin. Cutis 1998;62:201–3. 66. Rivera A, Tyring SK. Therapy of cutaneous human Papillomavirus infections. Dermatol Ther 2004;17:441–8. 67. Moed L, Shwayder TA, Chang MW. Cantharidin revisited: a blistering defense of an ancient medicine. Arch Dermatol 2001;137:1357–60. 68. Gillbro JM, Olsson MJ. The melanogenesis and mechanisms of skin-lightening agents–existing and new approaches. Int J Cosmet Sci 2011;33:210–21. 69. Roos TC, Alam M, Roos S, et al. Pharmacotherapy of ectoparasitic infections. Drugs 2001;61:1067–88.

70. Stuetz A, Baumann K, Grassberger M, et al. Discovery of topical calcineurin inhibitors and pharmacological profile of pimecrolimus. Int Arch Allergy Immunol 2006;141:199–212. 71. Yosipovitch G, Maibach HI. Effect of topical pramoxine on experimentally induced pruritus in humans. J Am Acad Dermatol 1997;37:278–80. 72. Young TA, Patel TS, Camacho F, et al. A pramoxinebased anti-itch lotion is more effective than a control lotion for the treatment of uremic pruritus in adult hemodialysis patients. J Dermatolog Treat 2009;20:76–81. 73. McKemy DD, Neuhausser WM, Julius D. Identification of a cold receptor reveals a general role for TRP channels in thermosensation. Nature 2002;416:52–8. 74. Peier AM, Moqrich A, Hergarden AC, et al. A TRP channel that senses cold stimuli and menthol. Cell 2002;108:705–15. 75. Patel T, Ishiuji Y, Yosipovitch G. Menthol: a refreshing look at this ancient compound. J Am Acad Dermatol 2007;57:873–8. 76. Lynn B. Capsaicin: actions on nociceptive C-fibres and therapeutic potential. Pain 1990;41:61–9. 77. Caterina MJ, Schumacher MA, Tominaga M, et al. The capsaicin receptor: a heat-activated ion channel in the pain pathway. Nature 1997;389:816–24. 78. Mason L, Moore RA, Derry S, et al. Systematic review of topical capsaicin for the treatment of chronic pain. BMJ 2004;328:991. 79. Drake LA, Millikan LE, Doxepin Study Group. The antipruritic effect of 5% doxepin cream in patients with eczematous dermatitis. Arch Dermatol 1995;131:1403–8. 80. Drake LA, Fallon JD, Sober A. Relief of pruritus in patients with atopic dermatitis after treatment with topical doxepin cream. The Doxepin Study Group. J Am Acad Dermatol 1994;31:613–16. 81. Taylor JS, Praditsuwan P, Handel D, Kuffner G. Allergic contact dermatitis from doxepin cream. One-year patch test clinic experience. Arch Dermatol 1996;132:515–18. 82. Loden M. Urea-containing moisturizers influence barrier properties of normal skin. Arch Dermatol Res 1996;288:103–7. 83. Hellgren L, Larsson K. On the effect of urea on human epidermis. Dermatologica 1974;149:289–93. 84. Hessel A, Cruz-Ramon JC. Agents used for treatment of hyperkeratosis. In: Wolverton SE, editor. Comprehensive Drug Therapy. 2nd ed. Philadelphia: Saunders; 2007. 85. Lin AN, Nakatsui T. Salicylic acid revisited. Int J Dermatol 1998;37:335–42. 86. Imayama S, Ueda S, Isoda M. Histologic changes in the skin of hairless mice following peeling with salicylic acid. Arch Dermatol 2000;136:1390–5. 87. Van Scott EJ, Yu RJ. Hyperkeratinization, corneocyte cohesion, and alpha hydroxy acids. J Am Acad Dermatol 1984;11:867–79. 88. Smith WP. Epidermal and dermal effects of topical lactic acid. J Am Acad Dermatol 1996;35:388–91. 89. Van Scott EJ, Yu RJ. Control of keratinization with alpha-hydroxy acids and related compounds. I. Topical treatment of ichthyotic disorders. Arch Dermatol 1974;110:586–90.

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of Netherton syndrome: results from an exploratory study. Arch Dermatol 2010;146:57–62. 38. Longley DB, Harkin DP, Johnston PG. 5-fluorouracil: mechanisms of action and clinical strategies. Nat Rev Cancer 2003;3:330–8. 39. Tsai EY, Zackheim H, Kim YH. Topical and intralesional chemotherapeutic agents. In: Wolverton SE, editor. Comprehensive Dermatologic Drug Therapy. 2nd ed. Philadelphia: Saunders; 2007. 40. Sachs DL, Kang S, Hammerberg C, et al. Topical fluorouracil for actinic keratoses and photoaging: a clinical and molecular analysis. Arch Dermatol 2009;145:659–66. 40a.  Talpur R, Venkatarajan S, Duvic M. Mechlorethamine gel for the topical treatment of stage IA and IB mycosis fungoides-type cutaneous T-cell lymphoma. Expert Rev Clin Pharmacol 2014;7:591–7. 40b.  Lessin SR, Duvic M, Guitart J, et al. Topical chemotherapy in cutaneous T-cell lymphoma: positive results of a randomized, controlled, multicenter trial testing the efficacy and safety of a novel mechlorethamine, 0.02%, gel in mycosis fungoides. JAMA Dermatol 2013;149:25–32. 41. Berthelot C, Rivera A, Duvic M. Skin directed therapy for mycosis fungoides: a review. J Drugs Dermatol 2008;7:655–66. 42. Zackheim HS. Treatment of mycosis fungoides with topical nitrosourea compounds. Arch Dermatol 1972;106:177–82. 43. Zackheim HS, Epstein EH Jr, Crain WR. Topical carmustine (BCNU) for cutaneous T cell lymphoma: a 15-year experience in 143 patients. J Am Acad Dermatol 1990;22:802–10. 44. Zackheim HS, Feldmann RJ, Lindsay C, Maibach HI. Percutaneous absorption of 1,3-bis (2-chloroethyl)-Initrosourea (BCNU, carmustine) in mycosis fungoides. Br J Dermatol 1977;97:65–7. 45. Helfrich YSD, Kang S. Topical vitamin D3. In: Wolverton SE, editor. Comprehensive Drug Therapy. 2nd ed. Philadelphia: Saunders; 2007. 46. Ashcroft DM, Po AL, Williams HC, Griffiths CE. Systematic review of comparative efficacy and tolerability of calcipotriol in treating chronic plaque psoriasis. BMJ 2000;320:963–7. 47. Lebwohl M, Siskin SB, Epinette W, et al. A multicenter trial of calcipotriene ointment and halobetasol ointment compared with either agent alone for the treatment of psoriasis. J Am Acad Dermatol 1996;35:268–9. 48. Kircik L. Efficacy and safety of topical calcitriol 3 microg/g ointment, a new topical therapy for chronic plaque psoriasis. J Drugs Dermatol 2009;8:s9–16. 49. Lebwohl M, Menter A, Weiss J, et al. Calcitriol 3 microg/g ointment in the management of mild to moderate plaque type psoriasis: results from 2 placebo-controlled, multicenter, randomized double-blind, clinical studies. J Drugs Dermatol 2007;6:428–35. 50. Veien NK, Bjerke JR, Rossmann-Ringdahl I, Jakobsen HB. Once daily treatment of psoriasis with tacalcitol compared with twice daily treatment with calcipotriol. A double-blind trial. Br J Dermatol 1997;137:581–6. 51. Paghdal KV, Schwartz RA. Sirolimus (rapamycin): from the soil of Easter Island to a bright future. J Am Acad Dermatol 2007;57:1046–50.

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SECTION 19 MEDICAL THERAPY

130 

Other Systemic Drugs Mary P. Maiberger, Julia R. Nunley and Stephen E. Wolverton

Chapter Contents Antimalarials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2280 Apremilast . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2283 Azathioprine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2285 Bleomycin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2286 Clofazimine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2286 Colchicine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2286 Cyclophosphamide . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2286 Cyclosporine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2287 Dapsone . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2288 Hydroxyurea . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2289 Leukotriene (LT) inhibitors . . . . . . . . . . . . . . . . . . . . . . . . 2289 Methotrexate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2290 Mycophenolate mofetil and mycophenolate sodium . . . . . . . 2292 Saturated solution of potassium iodide (SSKI) . . . . . . . . . . . . 2293 Sirolimus (rapamycin) and tacrolimus . . . . . . . . . . . . . . . . . 2293 Thalidomide and its derivatives . . . . . . . . . . . . . . . . . . . . . 2293

INTRODUCTION

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This chapter is designed to be a broad overview of selected systemic therapies for dermatologic diseases. It provides an historical perspective for each drug, a discussion of its mechanism of action and side effects, and touches briefly on indications and clinical use. This information should serve as a starting point, allowing the reader to readily compare and contrast treatment options. It is not a substitute for the in-depth knowledge and experience necessary to implement these therapies, nor is it a complete library of systemic drugs used in dermatology. A number of systemic medications are reviewed in other chapters (Table 130.1) and will not be discussed here. Systemic drugs used in dermatology may be subdivided into broad categories, such as immunosuppressive, cytotoxic, and antiproliferative (Table 130.2). Drugs in a single category act in a relatively similar fashion and generally have similar important side effects. For example, immunosuppressive drugs suppress the body’s ability to recognize or eliminate infections and neoplastic cells. Patients may be at increased risk for opportunistic infections and selected lymphoproliferative malignancies as well as squamous cell carcinomas. Given this increased risk for infection, patients with either an active infection or one that may reactivate (e.g. tuberculosis, hepatitis B viral infection) should be cautiously given these drugs. Most of the drugs discussed herein lack Food and Drug Administration (FDA) approval for dermatologic indications. However, in most instances, their use is based on the mechanism of action of the drug and the presumed pathogenesis of the disease, although in some instances, it is based upon anecdotal observations. When choosing therapy for a patient, certain broad general principles apply. First, the physician should be aware of all common therapeutic modalities available that are likely to yield optimal results. Certain systemic medications will not be utilized frequently enough for a given clinician to become comfortable with their use; therefore, patients requiring more specialized drugs should be referred to colleagues experienced with their use. Patients should be advised of all reasonable therapeutic choices as well as the risk–benefit profile of each modality. Non-compliance

is a relative contraindication for all medications discussed in this chapter. Prior to initiation of several of these medications, based upon potential side effects, the patient should have a complete history and physical examination, with specific emphasis on organ systems that may be affected by the particular drug. Tuberculin skin testing and/or interferongamma release assays (IGRAs; e.g. QuantiFERON®-TB Gold test, T-SPOT®.TB) should be performed prior to using some of the immunosuppressive medications, specifically corticosteroids (particularly when a prolonged course is anticipated) and biologic immunomodulators (see Ch. 128). Suggested screening for hepatitis B and C viruses is outlined in Table 128.8. Consultation with appropriate generalists or specialists in selected situations may be required prior to initiating therapy as well as for periodic screening for treatment complications. Table 130.3 outlines suggested monitoring guidelines for systemic medications discussed in this chapter. These tests may need to be performed more frequently in high-risk patients or in patients with abnormal results. Additionally, each outpatient visit should include an appropriate review of systems and physical examination. The use of each drug during pregnancy and lactation is reviewed. Wherever possible, this has been referenced with the ninth edition of Drugs in Pregnancy and Lactation by Briggs and colleagues. Additionally, in 2015, under the Pregnancy and Lactation Labeling Rule (PLLR), the FDA abolished the letter rating system for drug safety in pregnant women and during lactation; the letters are to be replaced with narrative-based labeling1. Drugs approved prior to 2015 have three years to comply with the new format while drugs approved thereafter must comply from the onset. This text will, when possible, include both when applicable. In general, one should be circumspect in prescribing systemic medications to women of childbearing potential. It is not adequate to merely ask the patient if she is utilizing birth control; the patient must be made acutely aware of the risks associated with medication use during pregnancy and risks of continuing therapy if she becomes pregnant. The prescribing physician also needs to be aware

SYSTEMIC MEDICATIONS COVERED IN OTHER CHAPTERS Antihistamines

Ch. 18

Antimicrobials

Ch. 127

Biologic immunomodulators, including rituximab, secukinumab, TNF-α inhibitors, ustekinumab

Ch. 128

Cytokines, including G-CSF, GM-CSF, interferons

Ch. 128

Glucocorticosteroids

Ch. 125

Interleukin (IL)-1 and IL-1R antagonists, including anakinra, canakinumab, rilonacept

Chs 45 & 128

Intravenous immunoglobulin (IVIg)

Ch. 128

Ivermectin

Ch. 84

JAK inhibitors, e.g. tofacitinib

Ch. 128

Psoralens

Ch. 134

Psychotropic agents, including pimozide, atypical antipsychotic agents

Ch. 7

Retinoids, including acitretin, bexarotene, isotretinoin

Chs 8, 36 & 126

Spironolactone

Ch. 36

Table 130.1 Systemic medications covered in other chapters. IL-1R, interleukin-1 receptor; G-CSF, granulocyte colony-stimulating factor; GM-CSF, granulocyte–macrophage colony-stimulating factor; JAK, Janus kinase.  

This chapter reviews systemic medications commonly used in dermatology that are not discussed elsewhere in this text. For each drug, a historical overview is provided followed by the mechanism of action, dosages, side effects, indications, contraindications, pregnancy considerations, and drug interactions. Systemic drugs used in dermatology may be subdivided into broad categories, such as immunosuppressive, cytotoxic, and antiproliferative. Medications covered include antimalarials, apremilast, azathioprine, bleomycin, clofazimine, colchicine, cyclophosphamide, cyclosporine, dapsone, hydroxyurea, leukotriene inhibitors, methotrexate, mycophenolate mofetil, saturated solution of potassium iodide, sirolimus (rapamycin), tacrolimus, and thalidomide. Information contained in this chapter is meant to serve as a springboard for the reader. It allows for a comparison of various systemic medications, taking into account side effects and contraindications. However, this chapter is merely a starting point as it is not a substitute for the in-depth knowledge and experience necessary to implement these systemic therapies, nor is it a complete library of systemic drugs used in dermatology.

mechanism of action, medication side effects, use in pregnancy and lactation, drug interactions, dosages, indications and contraindications of systemic dermatology, antimalarials, apremilast, azathioprine, bleomycin, clofazimine, colchicine, cyclophosphamide, cyclosporine, dapsone, hydroxyurea, leukotriene inhibitors, methotrexate, mycophenolate mofetil, saturated solution of potassium iodide (SSKI), sirolimus (rapamycin), tacrolimus, thalidomide

CHAPTER

130 medications

in

Other Systemic Drugs

ABSTRACT

non-print metadata KEYWORDS:

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CHAPTER

Immunosuppressive/Anti-inflammatory

Cytotoxic

Antiproliferative

Miscellaneous

Apremilast Azathioprine Mycophenolate mofetil Cyclosporine Tacrolimus Thalidomide

Cyclophosphamide Bleomycin

Methotrexate* Hydroxyurea

Dapsone Antimalarials Saturated solution of potassium iodide (SSKI)

*Also immunosuppressive/anti-inflammatory.

130 Other Systemic Drugs

CATEGORIES OF SYSTEMIC DRUGS USED IN DERMATOLOGY BASED UPON MECHANISM OF ACTION

Table 130.2 Categories of systemic drugs used in dermatology based upon mechanism of action.  

MONITORING GUIDELINES FOR SYSTEMIC MEDICATIONS

Drug

Initial screening

Follow-up monitoring

Special considerations

Antimalarials

Ocular: Slit lamp and fundoscopic examination: assessment of visual acuity and visual field testing Laboratory: CBC CMP G6PD (selected cases)

Ocular: Repeat testing every 6 months for 1 year and then yearly versus recent AAO guidelines4 – baseline examination within the first year of use then annual screening after 5 years of continuous therapy, unless high-risk patient or symptoms arise (see Table 130.4) Laboratory: CBC monthly for 3 months, then every 4–6 months CMP after 1 and 3 months, then every 4–6 months

G6PD testing before antimalarial therapy is controversial and is probably most important with the use of primaquine Urine or serum porphyrins should be measured when porphyria is clinically suspected Retinopathy risk is greatest for those on treatment for at least 5 years (especially with chloroquine) and if maximum daily safe maintenance dose has been exceeded

Azathioprine

CBC with PLT count CMP UA Consider pregnancy test for women of childbearing potential TPMT level, if available Tuberculin skin testing/IGRAs (should be considered depending on clinical situation)

CBC with PLT count every 2 weeks for 2 months, then every 2–3 months if stable AST/ALT every 2 weeks for 2 months, then every 2–3 months if stable

25% dose reduction is necessary if GFR 10–50 ml/ min; 50% dose reduction if GFR 2.3 mg/kg/day based upon real body weight)

Total cumulative dose

>1000 g

>460 g

Risk factors Dosing risk

130 Other Systemic Drugs

Fig. 130.1 Hydroxychloroquineinduced porphyria cutanea tarda (PCT). While low doses of antimalarials (e.g. 100–200 mg of hydroxychloroquine   2–3 times per week) can be used in the management of PCT, higher doses, such as those used to treat cutaneous LE, can lead to flares of PCT. This patient developed skin fragility and bullous lesions six weeks   after beginning hydroxychloroquine for rheumatoid arthritis. The eruption resolved with discontinuation of the medication.

Other risk factors History of retinopathy or maculopathy

History of retinopathy or maculopathy

Ocular





Systemic



Renal or hepatic dysfunction • Use of tamoxifen



Age





Elderly

Renal or hepatic dysfunction Elderly

Types of retinopathy

used in patients with porphyria cutanea tarda, in order to minimize the risk of a toxic reaction (e.g. hepatotoxicity) in addition to a marked increase in urinary uroporphyrin output and flare of cutaneous disease (Fig. 130.1). If no response is noted after 3–4 months, the specific antimalarial has failed and should be discontinued; however, a different antimalarial can be tried. In patients with porphyria cutanea tarda, the antimalarial can slowly be increased to daily dosing if necessary and if laboratory monitoring of transaminases allows. Monitoring guidelines are outlined in Table 130.3 and in the next section.

Major Side Effects Antimalarials are highly concentrated in the iris and choroid, reaching levels 480 000 times that of plasma3. However, irreversible retinopathy rarely occurs when dosages remain within the recommended range and patients are monitored by an ophthalmologist experienced with the ocular effects of antimalarials (Table 130.4). As noted in Table 130.4, the risk of retinopathy is much less with hydroxychloroquine than with chloroquine. Because of the risk of dose-related ocular toxicity, referral to an ophthalmologist is necessary for a baseline examination. The revised American Academy of Ophthalmology (AAO) guidelines recommend this baseline examination be performed within the first year of antimalarial use. With the exception of higher risk individuals (e.g. the elderly, history of maculopathy) and those patients with symptoms, annual screening then begins after five years of continuous use4. This is in distinction to previous guidelines in which screening was performed every 6–12 months. The basis for the revised guidelines is the negligible risk of retinopathy during the first five years of therapy with commonly employed doses (see Table 130.4)5. Of note, recent data regarding longterm usage suggest a significant potential for retinopathy after 10 years of continuous therapy6. Up to one-third of patients who receive antimalarials for over 4 months will develop a blue–gray to black hyperpigmentation on their shins (Fig. 130.2), face, palate and/or nail beds (Table 130.5). The discoloration fades after cessation of therapy, but may take months to years to resolve completely. Reversible bleaching of the hair roots (achromotrichia) occurs in up to 10% of patients, presumably due to interference with melanosomal function. Another 10–20% may develop an exanthem, ranging from urticaria to lichenoid reactions to exfoliative erythroderma. Of interest, morbilliform and urticarial exanthems have been observed with greater frequency in individuals with dermatomyositis as compared to those with LE. Antimalarials have been reported to worsen psoriasis in some patients, even though in the past they were commonly used to treat

Reversible ocular toxicity: • Corneal deposits leading to blurred vision, halos of colors around lights • Loss of accommodation/ diplopia • Premaculopathy: no visual symptoms or loss of visual acuity, central and paracentral scotomata



Observed in 5% of patients • Often reversible with discontinuation of therapy



Observed in 90% of patients • Often reversible with discontinuation of therapy

Irreversible ocular toxicity (true retinopathy): • “Bull’s eye” pigment deposition • Central scotomata • Changes in visual acuity



Incidence of 0.5% after 6 years of treatment • If develops, suspend treatment



Incidence can reach 1% after 5 years of treatment • If develops, suspend treatment

Table 130.4 Risk factors and types of retinopathy associated with antimalarial therapy. The ocular examination should include white 10-2 threshold testing (automated visual field testing) plus one or more of the following, if available: spectral domain optical coherence tomography, multifocal electroretinogram, or fundus autofluorescence. Adapted from references  

2a, 4, 5 and 43.

Fig. 130.2 Areas of blue–gray discoloration due to chloroquine.  

psoriatic arthritis. Psoriatic patients traveling to malaria-endemic areas may take these drugs prophylactically. Laboratory abnormalities do not commonly occur, but it is the practice of the authors to monitor patients as outlined in Table 130.3. An overdose of antimalarials can be fatal, and although pediatric usage is

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SIDE EFFECTS OF SYSTEMIC DRUGS USED IN DERMATOLOGY

Drug

Common

Uncommon

Rare

Antimalarials

Derm: blue–gray to black discoloration; yellowing from quinacrine

Derm: bleaching of hair roots, exanthem (e.g. urticarial, lichenoid) GI: nausea, vomiting, elevated liver enzymes Neuro: irritability, nervousness

Heme: pancytopenia, hemolysis (G6PDdeficient, primarily with non-dermatologic antimalarials) Ophtho: reversible (early) and irreversible retinopathy, vision changes (see Table 130.4)

Apremilast

GI: nausea, diarrhea ENT: nasopharyngitis Metabolic: weight loss

Neuro: headaches

Psych: depression and suicidal ideation

Azathioprine

Derm: non-melanoma skin cancers (NMSC) Heme: leukopenia, thrombocytopenia, immunosuppression

GI: nausea, vomiting ID: opportunistic infections

Heme: pancytopenia GI: pancreatitis, hepatitis Malignancy: lymphoma, cutaneous and gynecologic SCC Hypersensitivity syndrome

Cyclophosphamide

GI: nausea, vomiting GU: sterility (higher doses or long-term administration) Heme: leukopenia

Derm: diffuse hyperpigmentation, alopecia GU: dysuria, hemorrhagic cystitis, amenorrhea, azoospermia, sterility (with lower doses) Heme: anemia, thrombocytopenia ID: opportunistic infections

GI: hemorrhagic colitis, hepatotoxicity Heme: aplastic anemia Malignancy: bladder (esp. chronic oral administration), lymphoma, acute leukemia Pulmonary: pneumonitis, interstitial fibrosis Anaphylaxis

Cyclosporine

Cardiac: hypertension Derm: NMSC GU: renal dysfunction* Metabolic: hyperlipidemia Neuro: headache, tremor

Derm: hypertrichosis, gingival hyperplasia, sebaceous hyperplasia GI: nausea, diarrhea Neuro: paresthesia, hyperesthesia Metabolic: hyperkalemia†, hypomagnesemia, hyperuricemia

Derm: trichodysplasia spinulosa/viralassociated trichodysplasia ID: infections (unless combined with other immunosuppressives) Musculoskeletal: myalgias, myositis GI: hepatotoxicity Malignancy: lymphoma Pulmonary: dyspnea, bronchospasm

Dapsone

Heme: hemolysis, methemoglobinemia

GI: dyspepsia, anorexia

Heme: agranulocytosis Neuro: peripheral neuropathy Dapsone hypersensitivity syndrome

Hydroxyurea

Heme: anemia, megaloblastic changes

Derm: leg ulcers, alopecia Heme: leukopenia

Derm: hyperpigmentation, dermatomyositis-like lesions, NMSC GI: hepatitis GU: renal dysfunction Heme: thrombocytopenia Malignancies: acute leukemia

Methotrexate

Heme: leukopenia

Derm: photosensitivity, alopecia, oral ulcers GI: elevated liver enzymes, nausea, vomiting, anorexia, cirrhosis Heme: thrombocytopenia

Derm: necrosis of psoriatic plaques, accelerated rheumatoid (cutaneous) nodulosis Heme: pancytopenia, lymphoproliferative disorder (primarily in patients with RA) ID: infections Pulmonary: pneumonitis, fibrosis

Mycophenolate mofetil

GI: diarrhea, cramps, nausea, vomiting

Heme: anemia, leukopenia, thrombocytopenia ID: opportunistic infections

GU: dysuria, sterile pyuria Neuro: insomnia, dizziness, tinnitus

Saturated solution of potassium iodide (SSKI)

Derm: acneiform eruption GI: nausea, vomiting, diarrhea, abdominal pain Metabolic: reversible hypothyroidism

Derm: iododerma Metabolic: hyperkalemia

Cardiac: CHF, pulmonary edema Derm: flare of dermatitis herpetiformis GI: salivary gland enlargement Metabolic: irreversible hyperthyroidism, goiter, “iodism” Hypersensitivity reactions

Tacrolimus

Cardiac: hypertension Derm: NMSC GU: renal dysfunction* Neuro: paresthesias

ID: infections Metabolic: hyperkalemia†, hypomagnesemia

Derm: trichodysplasia spinulosa/viralassociated trichodysplasia Metabolic: diabetes mellitus, hyperuricemia Malignancy: lymphoma

Thalidomide

Derm: xerosis, pruritus GI: constipation Neuro: peripheral neuropathy, sedation Ob/Gyn: fetal abnormalities, amenorrhea

Cardiac: peripheral edema GI: xerostomia, increased appetite Gyn: primary ovarian failure Heme: thromboses Psych: headache, mood changes

Derm: exfoliative erythroderma, TEN Heme: leukopenia Hypersensitivity reaction (in HIV+)

*† Not permanent during short-term treatment if guidelines are followed. Especially when used in conjunction with ACE inhibitors.

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Table 130.5 Side effects of systemic drugs used in dermatology. CHF, congestive heart failure; Derm, dermatologic; G6PD, glucose-6-phosphate dehydrogenase; ENT, ear, nose and throat; GI, gastrointestinal; GU, genitourinary; Gyn, gynecologic; Heme, hematologic; ID, infectious diseases; Neuro, neurologic; Ob/Gyn, obstetrical/gynecologic; Ophtho, ophthalmologic; Psych, psychiatric; RA, rheumatoid arthritis; SCC, squamous cell carcinoma; TEN, toxic epidermal necrolysis.  

Indications The most common dermatologic use for antimalarials is as second-line therapy for cutaneous LE, after topical or intralesional corticosteroids. Antimalarials are especially useful in patients with widespread discoid lesions and in those with the annular or papulosquamous lesions of subacute cutaneous LE (SCLE). Antimalarial use has also been credited with fewer thromboembolic events in patients with systemic LE (SLE)2. Additional cutaneous disorders that may respond to antimalarial therapy are listed in Table 130.67.

Contraindications The only true contraindication is hypersensitivity to the drug. Caution should be used in patients with severe blood dyscrasias or hepatic disorders, because bone marrow suppression and hepatitis can occasionally occur. Should ophthalmologic changes of pre-maculopathy develop, an alternative medication should be considered. Ocular changes at this stage are potentially reversible, but could progress if the drug were continued.

Use in Pregnancy and Lactation Chloroquine is thought to be safe for treatment and prophylaxis of malaria during pregnancy; however, there have been anecdotal reports of an increase in birth defects in pregnant women being treated for SLE. Hydroxychloroquine is thought to be safer during pregnancy. Although excreted into breast milk, standard doses of either drug are not harmful to breastfed infants and are approved by the American Academy of Pediatrics for use during lactation8.

CHAPTER

Drug Interactions Cimetidine may increase circulating levels of antimalarials, and antimalarials may increase digoxin levels. Kaolin and magnesium trisilicate, over-the-counter gastrointestinal drugs, decrease absorption of antimalarials. The most significant potential interaction is the additive risk of retinal toxicity when chloroquine and hydroxychloroquine are used concomitantly. Combined therapy consisting of chloroquine or hydroxychloroquine plus quinacrine is acceptable. In patients with LE, cigarette smoking has been associated with decreased efficacy of antimalarials. Whether this represents a “drug– drug” interaction or decreased compliance (as a manifestation of highrisk behavior) is unknown.

130 Other Systemic Drugs

safe and effective, patients should be warned to keep the drug out of the reach of small children.

APREMILAST A novel, small-molecule inhibitor of phosphodiesterase 4, apremilast (Otezla®) works intracellularly to reduce the production of proinflammatory mediators and increase those that are anti-inflammatory (see below). When administered orally, apremilast is 70–75% bioavailable, with peak plasma concentrations observed at ~2.5 hours. Nearly 70% of the drug is bound to plasma proteins, and it is metabolized by cytochrome P450 (CYP) enzymes, predominately CYP3A4 (see Ch. 131); this is followed by glucuronidation and non-CYP-mediated hydrolysis. Apremilast has a terminal elimination half-life of 6–9 hours and is excreted in the urine and feces.

Mechanism of Action Apremilast inhibits phosphodiesterase 4, which is an intracellular enzyme that degrades cAMP and represents the predominant phosphodiesterase in keratinocytes, dendritic cells, monocytes, and neutrophils. Increasing intracellular cAMP levels activates protein kinase A,

CUTANEOUS DISORDERS THAT CAN BE TREATED WITH SPECIFIC SYSTEMIC DRUGS

Antimalarials

Azathioprine

CTX

Cyclosporine

Dapsone

Methotrexate

MMF

SSKI

Thalidomide

Dermato­ myositis# • Discoid lupus erythematosus (LE)* • GVHD (chronic) • Lichen planus and its variants, e.g. lichen planopilaris • LE tumidus • Lupus panniculitis • Polymorphic light eruption • Porphyria cutanea tarda† • Sarcoidosis • Subacute cutaneous LE • Livedoid vasculopathy • Anti­ phospholipid antibody syndrome • Morphea



Atopic dermatitis • Chronic actinic dermatitis • Behçet disease • Bullous pemphigoid • Dermato­ myositis • Mucous membrane (cicatricial) pemphigoid • Oral lichen planus • Pemphigus



Cutaneous T-cell lymphoma* • Mucous membrane (cicatricial) pemphigoid • Pemphigus • Systemic LE (renal) • Systemic sclerosis (pulmonary) • Systemic vasculitides, including granulomatosis with polyangiitis (Wegener granulomatosis), polyarteritis nodosa, eosinophilic granulomatosis with polyangiitis (Churg–Strauss syndrome)



Atopic dermatitis • Behçet disease • Chronic actinic dermatitis • Dermato­ myositis (pulmonary) • GVHD (acute) • Psoriasis * • Pyoderma gangrenosum • Stevens– Johnson syndrome/ toxic epidermal necrolysis • Urticaria



Behçet disease • Bullous eruption of SLE • Cutaneous small vessel vasculitis • Dermatitis herpetiformis* • Erythema elevatum diutinum • Leprosy • Linear IgA bullous dermatosis • Mucous membrane (cicatricial) pemphigoid



Bullous pemphigoid • Cutaneous T-cell lymphoma • Cutaneous LE • Dermato­ myositis • Langerhans cell histiocytosis • Lymphomatoid papulosis • Palmoplantar pustulosis • Pityriasis rubra pilaris • Pityriasis lichenoides et varioliformis acuta • Psoriasis * • Systemic sclerosis



Cutaneous LE • Dermato­ myositis • GVHD (acute and chronic) • Oral lichen planus • Pemphigus • Systemic sclerosis (pulmonary)



Erythema nodosum • Sporotri­ chosis





Actinic prurigo • Aphthous stomatitis • Behçet disease • Erythema nodosum leprosum • GVHD (chronic) • Prurigo nodularis • Subacute cutaneous and discoid LE

#Cutaneous drug reactions more common than in other autoimmune connective tissue diseases.

*† FDA-approved dermatologic conditions. Low-dose.

Table 130.6 Cutaneous disorders that can be treated with specific systemic drugs. Their use is based on double-blind controlled trials or large clinical series. CTX, cyclophosphamide; MMF, mycophenolate mofetil; SSKI, saturated solution of potassium iodide.  

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leading to enhanced expression of several transcription factors including cAMP-response element binding protein (CREB), while inhibiting others such as nuclear factor kappa B (NF-κB). By inhibiting phosphodiesterase 4 and increasing intracellular cAMP levels, apremilast has multiple downstream effects: it decreases the production of inflammatory mediators such as TNF-α, IFN-γ, and interleukins (IL)-2, -12, and -23; it increases the production of anti-inflammatory mediators including IL-10; and it inhibits natural killer responses (Fig. 130.3)9.

Dosages

Indications Apremilast is FDA-approved for adult patients with active psoriatic arthritis and moderate to severe plaque psoriasis. The ESTEEM trial reported that a significantly greater proportion of patients receiving apremilast (30 mg BID) achieved Psoriasis Area and Severity Index (PASI)-75 (33.1%) and PASI-50 (58.7%) at week 16 compared with placebo (5.3% and 17.0%); quality of life measures and nail and scalp psoriasis were similarly improved10,11. It is currently being investigated for other inflammatory skin diseases including discoid LE, lichen planus, granulomatous dermatoses, and atopic dermatitis.

The recommended dosage for psoriatic arthritis and psoriasis is 30 mg twice daily. In order to reduce gastrointestinal symptoms, an upward titration of the dose by 10 mg/day is recommended, starting with an initial dose of 10 mg/day. Apremilast is available in 10, 20 and 30 mg tablets. For individuals with severe renal impairment, the recommended maximum daily dose is 30 mg; there is no dosing adjustment for hepatic impairment.

Contraindications

Major Side Effects

Apremilast was formerly pregnancy category C. However, it has not been evaluated in well-controlled studies involving pregnant women and should only be used during pregnancy if the potential benefit justifies the potential risk. It is not known whether apremilast or its metabolites are present in human milk.

The most common side effects are gastrointestinal, especially nausea and diarrhea, and they are most evident during the first 15 days of administration and gradually resolve over several weeks. Headache and nasopharyngitis are additional potential side effects. Because depression, including suicidal ideation, can be observed in up to 1% of patients, patients with a history of depression should be monitored closely. Loss of ~5–10% of body weight occurs in ~10% of patients. No laboratory monitoring is recommended, but serial measurements of weight can be performed.

Apremilast is contraindicated in patients with known hypersensitivity to the drug or its components. Dosing should be adjusted for renal failure (see above). Relative contraindications include a history of depression or suicidal ideation.

Use in Pregnancy and Lactation

Drug Interactions Coadministration of apremilast with potent CYP450 inducers including rifampin, phenobarbital, carbamazepine, and phenytoin may significantly diminish apremilast levels and should be avoided (see Ch. 131).

MECHANISM OF ACTION OF APREMILAST Growth factor TNF

Adenylate cyclase + P IκB

IκB kinase

γ

G protein-coupled receptor

α

Ub Ub Ub

Apremilast

IκB

ATP NF–κB

Inactive

β

↑ cAMP

PDE-4

AMP

PPKAR1A PKA

Active PKA

Nucleus NF–κB Gene(s) κB Site

CREB Because of inhibition, ↓ TNF-α, ↓ IL-23, ↓ IFN-γ Gene expression leading to ↑ IL-10

Fig. 130.3 Mechanism of action of apremilast. Apremilast specifically inhibits phosphodiesterase 4 (PDE-4) thereby resulting in increased intracellular cAMP levels. This leads to activation of protein kinase A (PKA), which in turn phosphorylates the transcription factor cAMP response element binding protein (CREB). Binding of CREB acts to increase the expression of anti-inflammatory mediators, e.g. interleukin (IL)-10. Increased intracellular cAMP levels also inhibit nuclear factor kappa B (NF-κB) leading to decreased expression of inflammatory mediators, e.g. tumor necrosis factor-alpha (TNF-α), IL-23, interferon-γ (IFN-γ). ATP, adenosine triphosphate; α, α subunit of the stimulatory G protein; Ub, ubiquitin. Adapted from Schafer, P. Apremilast – mechanism of action and application to psoriasis and psoriatic arthritis. Biochem  

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Azathioprine was developed in 1959 from its parent drug 6mercaptopurine (6-MP). After its anti-inflammatory and immunosuppressive effects were noted, dermatologists began to utilize azathioprine for the treatment of inflammatory diseases. With its moderately potent immunosuppressive and anti-inflammatory effects, azathioprine has a reasonable risk–benefit profile. However, it should be reserved for serious, life-threatening or recalcitrant dermatoses after other therapies have failed. Azathioprine (Imuran®, Azasan®, Azamun™) has an 88% bioavailability. Immediately after absorption, it is converted to 6-MP and subsequently processed through three different, competing pathways (Fig. 130.4). When 6-MP is catabolized via two of these metabolic pathways, by either xanthine oxidase or thiopurine methyltransferase (TPMT), inactive metabolites result. Active metabolites, such as the purine analogue thioguanine monophosphate and others, are produced from the third and only anabolic pathway via hypoxanthine-guanine phosphoribosyl transferase (HGPRT)12. Should either the xanthine oxidase or TPMT catabolic pathway be blocked, more 6-MP will be shunted through the anabolic HGPRT pathway, leading to more active metabolites; excessive immunosuppression and pancytopenia may result12. The TPMT pathway is interesting because the enzyme can have variable activity based upon genetic polymorphisms. Three distinct phenotypes exist, and ethnicity may factor into the frequency of certain alleles. Encoded at the 6p22.3 locus, the TPMT activity trait is inherited in an autosomal co-dominant manner13. Overall, 89% of Caucasians are homozygous for the high-activity allele and have relatively elevated levels, 11% are heterozygotes and have moderate activity, and 1/300 is homozygous for one of the seven low-activity alleles and has low TPMT activity. Red blood cell (RBC) TPMT activity mirrors systemic activity, and a test for RBC TPMT activity has been developed. Although TPMT activity may vary somewhat between different laboratories and within different batches of the same test kit, knowledge of baseline TPMT activity is clinically useful in the majority of patients who will receive azathioprine. However, vigilance in monitoring for pancytopenia will also identify those with low TMPT activity who will require dose reduction. Likewise, patients with high TMPT activity may need higher doses. Although decreased xanthine oxidase activity is rarely due to genetic polymorphisms, this enzyme is inhibited by the medications allopurinol and febuxostat (see Fig. 130.4). Azathioprine dosage should be decreased by 75% in patients receiving allopurinol or febuxostat.

Mechanism of Action

amino or hydroxyl group, it contains a thiol moiety. Incorporation of 6-thioguanine into DNA and RNA inhibits purine metabolism and cell division. 6–Thioguanine has other activities which are not well understood, such as suppression of T-cell function and B-cell antibody production14. It also decreases the number of Langerhans cells in the skin and inhibits their ability to present antigens15.

Dosages Available in 25, 50, 75 and 100 mg tablets, empiric dosing is generally started at 50 mg/day and increased to a maximum of 2.5 mg/kg/day according to clinical efficacy and careful monitoring. Maximum doses based on baseline TPMT determination are outlined in Table 130.7. In either case, renal insufficiency dictates dose reduction (see Table 130.3). Baseline evaluation should include a complete medication history because of adverse effects when azathioprine is used concomitantly with allopurinol, febuxostat, captopril or warfarin (see below). Monitoring guidelines are outlined in Table 130.3.

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130 Other Systemic Drugs

AZATHIOPRINE

Major Side Effects Major side effects are related to the immunosuppressive effects of azathioprine (see Table 130.5). Pancytopenia occurs rarely, particularly when doses are based on TPMT activity. Patients may be at increased risk for malignancies, especially lymphoproliferative disorders and squamous cell carcinomas of the skin and female genitourinary tract, and should be monitored accordingly. Factors influencing a patient’s malignancy risk include degree and duration of immunosuppression, skin phototype, and existing comorbidities. Azathioprine may rarely cause a life-threatening hypersensitivity reaction. It most commonly develops during the first month of therapy and when there is concurrent use of either cyclosporine or methotrexate. The cutaneous eruption is typically morbilliform with areas of confluence. Other components of the syndrome include fever, respiratory

MAXIMUM DOSE OF AZATHIOPRINE AS DETERMINED BY BASELINE TPMT ACTIVITY

TPMT level

Maximum dose of AZA

19 U

Up to 2.5 mg/kg/day

Table 130.7 Maximum dose of azathioprine as determined by baseline TPMT activity. Doses are based upon actual weight. AZA, azathioprine; TPMT, thiopurine methyltransferase; U, units.  

6–Thioguanine, the active metabolite of azathioprine, is a purine analogue similar in structure to both adenine and guanine. Instead of an

Fig. 130.4 Metabolic pathway for azathioprine. Either decreased activity of TPMT or inhibition of xanthine oxidase by allopurinol or febuxostat can lead to shunting of 6-mercaptopurine to the HGPRT pathway. As a result of this shunting, there is an increase in active metabolites and an increased risk of toxicity. Adapted from Wolverton SE. Comprehensive  

METABOLIC PATHWAY FOR AZATHIOPRINE

Azathioprine

Dermatologic Drug Therapy, 3rd edn. Philadelphia: Saunders, 2013.

6-Mercaptopurine

Hypoxanthine-guanine phosphoribosyl transferase (HGPRT)

Thiopurine methyltransferase (TPMT)

Xanthine oxidase

Active metabolites (6-Thioguanine)

Inactive metabolites

Inactive metabolites

Allopurinol Febuxostat

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SECTION

Medical Therapy

19

and gastrointestinal distress, hepatotoxicity, and possible cardiovascular collapse. This hypersensitivity reaction represents an absolute contraindication as re-exposure may lead to cardiovascular collapse.

Indications Although azathioprine has FDA approval for non-dermatologic uses only, dermatologists have been using this drug for decades to treat severe dermatologic conditions, most often as a corticosteroid-sparing agent in the treatment of immunobullous diseases and various subtypes of cutaneous vasculitis (see Table 130.6)14,16. It is inexpensive and has moderate immunosuppressive and anti-inflammatory effects. Clinical benefit of the drug may not be apparent until it has been administered for at least 4 to 6 weeks.

Contraindications Absolute contraindications to azathioprine therapy include history of a hypersensitivity reaction, as re-challenge may prove fatal. Active serious infection and pregnancy are relative contraindications. Concomitant use of allopurinol or febuxostat requires dose reduction of azathioprine (see above) or selection of an alternative medication.

Use in Pregnancy and Lactation Azathioprine was formerly pregnancy category D and is associated with preterm delivery, low-birth-weight infants, sporadic anomalies, and hematologic toxicities. Even though it is considered relatively safe for use in transplant patients who become pregnant, for dermatologic purposes it should not be prescribed during pregnancy. There are limited data regarding risk to breastfed infants, but based upon several small series, its use is probably allowable during breastfeeding8.

Drug Interactions Inhibition of xanthine oxidase by allopurinol or febuxostat (see Fig. 130.4) increases the risk of pancytopenia in azathioprine-treated patients. Captopril may increase the risk of leukopenia. Azathioprine can decrease the effectiveness of warfarin and pancuronium, necessitating larger doses of these drugs. Since azathioprine may decrease the effectiveness of intrauterine contraceptive devices, alternative birth control methods should be employed.

COLCHICINE The dosage, uses and side effects are outlined in Table 130.10.

CYCLOPHOSPHAMIDE Cyclophosphamide (Cytoxan®) was derived from mechlorethamine (nitrogen mustard) in 1958; the latter was combined with phosphoric

CLOFAZIMINE Drug properties: riminophenazine dye (red color) Mechanism of action: disrupts cell membranes (activation of phospholipase A2 leads to generation of membrane-destabilizing lysophospholipids); enhances superoxide production; inhibits neutrophil motility and lymphocyte proliferation Dermatologic use: treatment of multibacillary leprosy, other infections (mycobacterial, malacoplakia, rhinoscleroma), and inflammatory skin diseases including neutrophilic dermatoses (pyoderma gangrenosum, Sweet syndrome), granuloma faciale, orofacial granulomatosis, erythema dyschromicum perstans, and discoid LE Dosage: 50–400 mg orally daily*; avoid long-term administration of >200 mg daily; see Table 75.5 for leprosy regimens Side effects: discoloration of skin† (red to red–brown diffusely, bluish to violet–brown in lesional sites), cornea/conjunctiva, and body fluids (urine, sweat, tears); xerosis/ichthyosis; gastrointestinal symptoms (abdominal pain, nausea, vomiting, diarrhea); ocular irritation; elevated hepatic enzymes; crystal deposition-related enteropathy (rarely); cardiac arrhythmias (rarely; associated with electrolyte disturbances) Monitoring guidelines: baseline electrolyte panel; periodic LFTs if daily doses >100 mg; periodic evaluation for GI side effects and skin discoloration Contraindications: prior hypersensitivity reaction Pregnancy and lactation: for dermatologic disorders, should be avoided during pregnancy (formerly category C) and lactation (concentrated in breast milk)

*† Larger doses are usually divided into two to four times daily. Due to deposits of drug within fat and macrophages.

Table 130.9 Clofazimine. LE, lupus erythematosus; LFTs, liver function tests.  

BLEOMYCIN COLCHICINE

The dosage, uses and side effects are outlined in Table 130.8.

CLOFAZIMINE The dosage, uses and side effects are outlined in Table 130.9.

BLEOMYCIN Source: Streptomyces verticillus Mechanism of action: inhibits DNA synthesis in infected keratinocytes, but no direct effect on the human papillomavirus Dermatologic use: intralesional treatment of therapy-resistant verrucae vulgaris; 65–80% of lesions clear after 1 to 2 injections Dosage: 0.1 to 0.3 ml of 1 U/ml (of saline) injected into targeted lesions, with maximum total dose per treatment = 2 ml; repeated every 3 to 6 weeks until resolution; given its rapid degradation and expense, newly constituted solution should be divided into glass vials and can be stored at 2–8°C for ~3 months Side effects of intralesional administration: injection is extremely painful (local or regional anesthesia may be required); pain and burning postinjection for 2–3 days; Raynaud phenomenon occasionally; nail dystrophy; flagellate dermatitis (above recommended total dose); no systemic toxicity with recommended total dose Contraindications: pregnancy, immunosuppression, vascular compromise Pregnancy and lactation: not recommended; formerly pregnancy prescribing category D

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Table 130.8 Bleomycin.  

Source: alkaloid from Colchicum autumnale (autumn crocus) Mechanism of action: prevents microtubule assembly, resulting in mitotic arrest at metaphase and inhibition of cellular motility; decreases neutrophil chemotaxis, adhesion and degranulation Dermatologic use: treatment of neutrophilic dermatoses (Behçet disease, Sweet syndrome), cutaneous small vessel vasculitis, neutrophil-rich autoimmune bullous diseases (EBA, linear IgA bullous dermatosis), and aphthous stomatitis Dosage: 0.5 or 0.6 mg orally two to three times daily; drug must be shielded from light (degraded by UVR) Side effects: commonly, gastrointestinal symptoms (diarrhea, abdominal pain, nausea, vomiting; dose-related); occasionally, alopecia, peripheral neuropathy, myopathy, and bone marrow suppression (with prolonged therapy*); multiorgan failure with acute overdose† Monitoring guidelines: baseline CBC with PLT, CMP, and UA; repeat CBC with PLT monthly for first several months then every 3–6 months Contraindications: prior hypersensitivity reaction; severe renal, hepatic, gastrointestinal or cardiac disease; blood dyscrasias Pregnancy and lactation: for dermatologic disorders, should be avoided during pregnancy (formerly category C); excreted in breast milk, but use during lactation allowed per AAP recommendations

*† Particularly in patients with renal insufficiency.

A toxic epidermal necrolysis-like reaction has been described.

Table 130.10 Colchicine. In patients with renal or hepatic impairment on colchicine, P-glycoprotein and strong CYP3A4 inhibitors should be avoided. AAP, American Academy of Pediatrics; CBC, complete blood count with differential; CMP, comprehensive metabolic panel (includes liver function tests); EBA, epidermolysis bullosa acquisita; PLT, platelet count; UA, urinalysis; UVR, ultraviolet radiation.  

membrane (cicatricial) pemphigoid, especially when there is rapidly progressive or severe ocular involvement.

Mechanism of Action

Use in Pregnancy and Lactation

Cyclophosphamide is an alkylating agent that functions in a cell cycleindependent fashion. Although its major effect is suppression of B-cell function, it also suppresses T-cell function (especially of regulatory T cells). Clearly, the T-cell effects are greatest if the drug is given prior to antigen presentation. Cyclophosphamide crosses the nuclear membrane, covalently binds with DNA, and inhibits the synthesis of guanine, cytosine and adenine. Cytotoxicity occurs by several mechanisms: (1) DNA cross-linking with various proteins or other DNA strands; (2) G-C → A-T substitution; and (3) depurination resulting in chain scission. These mechanisms can overwhelm the DNA repair mechanisms, inducing cell death17.

Dosages Cyclophosphamide is available in 25 and 50 mg tablets. Doses range from 1 to 3 mg/kg/day, either as a single morning dose or in equally divided doses. Dermatologic diseases seldom require more than 2 to 2.5 mg/kg/day of cyclophosphamide. Dose reduction is necessary in patients with hepatic or renal dysfunction. Because of the risk of hemorrhagic cystitis, patients should be advised to always consume plenty of fluids. A monthly intravenous infusion (pulse) of 500 to 1000 mg has been used to treat a number of rheumatologic disorders, including severe SLE. Prior to prescribing cyclophosphamide, patients should have a documented white blood count (WBC) of >4500/mm3 and a granulocyte count of >1500/mm3. If the counts are lower and there is no alternative drug, then consultation with a hematologist is recommended. Laboratory monitoring guidelines are outlined in Table 130.3. Of note, it is not necessary to induce significant myelosuppression in order to achieve immunosuppression18.

Major Side Effects The most common side effects from cyclophosphamide treatment are hematologic and gastrointestinal (see Table 130.5). Dermatologic side effects include anagen effluvium (5–30%, typically reversible), pigmented bands of the teeth (irreversible), diffuse hyperpigmentation, transverse ridging of nails, acral erythema, and, rarely, Stevens–Johnson syndrome. Up to 40% of patients have hemorrhagic cystitis, presumably from the acrolein metabolite, which is associated with a 10-fold increase in the risk for transitional cell carcinoma of the bladder. This risk is greater in patients who receive chronic “low-dose” cyclophosphamide (as traditionally given for dermatologic diseases) than in those exposed to brief courses of high-dose pulse therapy (as given for systemic lymphomas and SLE). Immunosuppression is significant, especially in patients concomitantly receiving systemic corticosteroid therapy. Infection and malignancy risks are real with appropriate monitoring recommended. Long-term or high-dose therapy may be associated with infertility in either sex14.

Indications Although cyclophosphamide is only FDA-approved for use in advanced mycosis fungoides and hematopoietic malignancies, it can be useful in treating a number of severe cutaneous diseases. Cyclophosphamide is regularly used to treat systemic vasculitides, including granulomatosis with polyangiitis (Wegener granulomatosis), polyarteritis nodosa, microscopic polyangiitis, and eosinophilic granulomatosis with polyangiitis (Churg–Strauss syndrome)18. It can also be employed as a corticosteroid-sparing agent in a variety of severe mucocutaneous diseases or as monotherapy after corticosteroids are discontinued. In particular, cyclophosphamide plus corticosteroids are used to treat mucous

Contraindications Absolute contraindications are pregnancy, lactation, depressed bone marrow function, and hypersensitivity to the drug. Cyclophosphamideallergic patients may have cross-reactions with chlorambucil or mechlorethamine. Relative contraindications include active infections and significantly impaired hepatic or renal function.

CHAPTER

130 Other Systemic Drugs

acid in an effort to make an inert drug capable of entering and releasing active mechlorethamine within target cells17. It has ~75% oral bioavailability, peaks in the plasma at about 1 hour, and crosses the blood–brain barrier. Cyclophosphamide itself is inactive, but it is metabolized by CYP enzymes into the active metabolite 4-hydroxy-cyclophosphamide (nornitrogen mustard, t 12 3.3 hours), which may then be converted into the other active metabolite phosphoramide mustard (t 12 9 hours). Metabolites are excreted primarily via the kidney (50%). The inactive metabolite acrolein is believed to cause hemorrhagic cystitis and associated transitional cell carcinoma of the bladder18.

Cyclophosphamide is a first-trimester teratogen and is immunosuppressive in breastfed infants. It was formerly pregnancy prescribing category D and should not be used during pregnancy or lactation8.

Drug Interactions Allopurinol, cimetidine, and chloramphenicol may elevate cyclophosphamide drug levels and produce toxicity (via CYP450 interactions), whereas barbiturates may enhance conversion to inactive metabolites. Digoxin absorption may be decreased. Cyclophosphamide may enhance the effect of succinylcholine, increase the cardiotoxicity of doxorubicin, and cause additive immunosuppressive and carcinogenic effects with other immunosuppressive drugs. Unpredictable effects can be seen when used with the inhalation anesthetics halothane and nitrous oxide.

CYCLOSPORINE Cyclosporine, a cyclic peptide of 11 amino acids, was isolated from the soil fungus Tolypocladium inflatum in 1970 and was found to have clinical immunosuppressive effects in 1976. In 1979, during a rheumatoid arthritis trial, it was discovered that cyclosporine improved cutaneous psoriasis in patients with psoriatic arthritis. Two forms are available, the original preparation (Sandimmune®) and a predigested microemulsion (Neoral®) that is more completely and consistently absorbed. The latter is available as capsules (25 and 100 mg) or as an oral solution (100 mg/ml)19. The solution can be mixed in orange juice or apple juice, but grapefruit juice should be avoided because it alters cyclosporine’s metabolism (see Fig. 131.4). Bioavailability of the microemulsion is not known, but it yields 40–106% higher peak blood levels than the original formulation. Cyclosporine is both metabolized by the CYP3A4 pathway and is a CYP3A4 inhibitor; primary excretion is via bile and feces. Only 6% of cyclosporine is excreted unchanged in the urine. Drug levels (11-hour trough level) can be measured but the therapeutic range is relatively wide; determinations are helpful when drug–drug interactions or noncompliance are a concern.

Mechanism of Action T-cell receptor activation causes release of intracellular calcium that in turn binds calmodulin and activates calcineurin (see Ch. 128). This calcineurin complex dephosphorylates the nuclear factor of activated T cells (NFATc) which is present within the cytoplasm, allowing it to migrate into the nucleus and bind with its intranuclear counterpart NFATn. This complex is a transcription factor for inflammatory cytokines such as IL-2. IL-2 receptors are also upregulated as a result of this process. Cyclosporine binds to cyclophilin, a member of the family of intracytoplasmic proteins called immunophilins. This complex blocks the dephosphorylation of NFATc and the subsequent upregulation of IL-2 and IL-2 receptors, resulting in a reduction of CD4+ and CD8+ (cytotoxic) T cells in the epidermis14,19.

Dosages Cyclosporine is best used on a short-term basis (25% over baseline, the value should be rechecked within 2 weeks. If it returns to 25% above baseline, therapy should be discontinued until the serum creatinine is within 10% of the baseline value. At that time, restarting therapy may be considered, but at a significantly lower dose.

Major Side Effects Cyclosporine is associated with a wide variety of adverse effects, including hypertension, renal dysfunction, hyperlipidemia, hyperkalemia, hyperuricemia, hypomagnesemia, hypertrichosis, and gingival hyperplasia (see Table 130.5). Most of the side effects associated with short-term therapy are reversible upon discontinuation of the drug. A quarter of all psoriasis patients on cyclosporine will develop hypertension, which is usually mild and manageable; calcium channel blockers of the dihydropyridine class are the recommended first-line antihypertensive agents. A direct vasoconstrictive effect of cyclosporine on the kidney vasculature is responsible for the development of hypertension short-term23. Hypertension due to cyclosporine is both time- and dose-related. Modern, conservative dosing guidelines have prevented significant kidney damage in the vast majority of patients on short-term therapy. However, renal interstitial fibrosis has been demonstrated histologically even in the absence of abnormal laboratory tests in patients on appropriate dosing and monitoring regimens. Renal biopsy specimens from patients on long-term treatment demonstrate irreversible changes including renal tubular atrophy, arteriolar hyalinosis, glomerular obsolescence, and interstitial fibrosis24,25. In fact, all patients on cyclosporine for >2 years were shown to have some of these abnormalities. Although transplant recipients on high doses and prolonged courses of cyclosporine have an increased risk of certain malignancies (e.g. lymphoma, cutaneous squamous cell carcinoma), patients with skin diseases on cyclosporine for less than 2 years and on lower “dermatologic” doses have not been observed to have a similar risk.

Indications

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Cyclosporine can be beneficial for patients with psoriasis who have failed or cannot tolerate other therapies and for those with widespread, inflammatory disease (see Ch. 8). In fact, cyclosporine has FDA approval for three “types” of psoriasis: (1) severe; (2) recalcitrant; and (3) disabling. Patients with plaque-type psoriasis may also benefit from cyclosporine in rotating or sequential regimens with other modalities. The use of cyclosporine in atopic dermatitis has been examined, and a high percentage of patients improve with therapy; unfortunately, most relapse within 4 weeks of discontinuation. Cyclosporine efficacy has been established in patients with severe pyoderma gangrenosum; however, some clinicians prefer cyclosporine for idiopathic pyoderma gangrenosum only, arguing that when there is a known underlying cause, therapy is best aimed at the latter (e.g. inflammatory bowel disease, myelodysplasia). Very short-term cyclosporine has been used for Stevens-Johnson syndrome and toxic epidermal necrolysis, with

some promising results25a. Most other uses of cyclosporine are based upon anecdotal evidence26.

Contraindications Absolute contraindications include significant renal impairment, uncontrolled hypertension, and hypersensitivity to cyclosporine. Relative contraindications include age 64 years, controlled hypertension, and medication usage that may interfere with cyclosporine metabolism or worsen renal function. Caution is necessary if used in patients with significant infections, recent live-virus vaccinations (see Table 128.10) or immunodeficiency syndromes, or in combination with methotrexate, phototherapy or other immunosuppressive drugs.

Use in Pregnancy and Lactation Cyclosporine is not teratogenic and was formerly classified as pregnancy prescribing category C. Use during pregnancy should be considered only in exceptional patients for whom the potential benefits dramatically outweigh the risks. Cyclosporine is excreted into breast milk and should not be used during lactation, due to risks of immunosuppression and possible carcinogenesis in the breastfed infant8.

Drug Interactions Drugs that interact with cyclosporine are discussed in Chapter 131. The clinician should review the patient’s medication list for potential interactions using the following guidelines. In general, drugs that inhibit the CYP3A4 pathway will increase cyclosporine levels, while inducers of the 3A4 pathway will decrease the effectiveness of cyclosporine, due to lower serum levels. Some drugs will potentiate renal toxicity, such as nonsteroidal anti-inflammatory drugs (NSAIDs), aminoglycosides, amphotericin B, and miscellaneous antibiotics (vancomycin, trimethoprim–sulfamethoxazole). Cyclosporine will reduce the renal clearance of digoxin, lovastatin, and prednisolone. Increased risk of hyperkalemia occurs with concurrent use of angiotensin-converting enzyme (ACE) inhibitors, potassium supplements, and potassiumsparing diuretics.

DAPSONE Dapsone is a sulfone drug, and sulfones are related to the sulfonamide family (see Ch. 21). Sulfonamides were initially derived from coal tar in the early 1900s for use as fabric dyes. Medically, they were first demonstrated to be effective against streptococcal infections. Synthesized in 1908, dapsone was shown to be effective against tuberculosis and leprosy. During the first half of the twentieth century, the related drugs sulfapyridine and sulfoxone were used to treat dermatitis herpetiformis (DH). However, since 1953, dapsone (the parent compound of sulfoxone) has been the mainstay of treatment for DH. Due to its activity in neutrophil-mediated dermatoses, dapsone has also proven useful in the treatment of several forms of autoimmune bullous diseases and vasculitis syndromes. Dapsone is 80% orally bioavailable, peaks in the serum between 2 and 6 hours post-administration, and has a half-life of 24–30 hours. Being highly lipophilic, it has excellent cell penetration. Dapsone and its major metabolite monoacetyldapsone are strongly protein-bound and undergo enterohepatic recirculation. Thus, dapsone may be found in the bloodstream up to 1 month following a single dose27. Dapsone is metabolized by N-acetylation and N-hydroxylation in the liver27,28. Acetylation yields monoacetyldapsone, which is then de-acetylated to dapsone, yielding an equilibrium between dapsone and monoacetyldapsone. Hydroxylation via CYP enzymes produces N-hydroxy-dapsone, the metabolite which is believed to be responsible for the majority of dapsone side effects. Both dapsone and N-hydroxydapsone undergo glucuronidation in the liver, which results in more water-soluble compounds that are rapidly excreted in the urine27.

Mechanism of Action Dapsone is clinically most useful in the treatment of dermatologic diseases involving neutrophilic infiltrates. Researchers have demonstrated that dapsone inhibits neutrophil myeloperoxidase, thus reducing damage from the neutrophil respiratory burst mediated by this enzyme. Furthermore, dapsone has been shown to inhibit neutrophil

Dosages Dapsone is available in 25 and 100 mg tablets. The initial dose is often 50 mg/day in a single dose. Most conditions require 50–200 mg/day for adequate control of symptoms; rarely are dosages up to 300 mg/day required. In those with DH who respond to dapsone, rapid resolution of symptoms (within 48 hours) is usually noted; conversely, symptoms flare relatively rapidly after discontinuing therapy. Patients must be strictly warned against self-adjustment of the dosage, due to dosedependent side effects. Because of potential adverse effects, any cardiopulmonary or neurologic symptoms should be assessed prior to therapy. Documentation of peripheral motor nerve function may occasionally be necessary before or during therapy. Table 130.3 outlines monitoring guidelines for therapy. The clinician must be aware of all signs and symptoms associated with methemoglobinemia and peripheral neuropathy to ensure proper monitoring.

Major Side Effects Serious systemic side effects of dapsone may be idiosyncratic or pharmacologic. The pharmacologic and dose-dependent adverse effects include methemoglobinemia and hemolytic anemia (see Table 130.5). Agranulocytosis, peripheral motor neuropathy, and dapsone hypersensitivity are idiosyncratic reactions; however, patients on higher daily doses or long-term therapy may be more likely to develop a peripheral motor neuropathy. Although rare, dapsone hypersensitivity syndrome may be fatal. Patients present with fever, hepatitis, and a generalized cutaneous eruption. Cutaneous reactions range from an exanthematous eruption to toxic epidermal necrolysis (TEN). Liver failure has occurred in patients with the dapsone hypersensitivity syndrome29, and hypothyroidism may develop following resolution of the acute eruption. Thus, there is significant overlap with DRESS syndrome.

Indications Dapsone works well in a number of neutrophilic dermatoses and immunobullous diseases. Although only FDA-approved for DH, dapsone is very useful in linear IgA bullous dermatosis, bullous eruption of SLE, erythema elevatum diutinum, and perhaps cutaneous small vessel vasculitis27,28. It is also a key component of combination therapy for leprosy.

Contraindications The absolute contraindication to dapsone therapy is prior hypersensitivity to dapsone. Relative contraindications include a low glucose-6phosphate dehydrogenase (G6PD) level, significant cardiopulmonary disease, and allergy to sulfonamide antibiotics (because of possible cross-reactivity). In patients with low G6PD levels, there is an increased risk for oxidative stress of the dapsone metabolites on RBCs. Those with significant cardiopulmonary disease may not tolerate the methemoglobinemia and hemolysis induced by dapsone.

Use in Pregnancy and Lactation Dapsone does not appear to present a major risk to the fetus; however, it was formerly a pregnancy prescribing category C drug and should only be used during pregnancy if the benefits clearly outweigh the risks. There have been publications reporting its use in pregnant patients with leprosy. Dapsone is found in breast milk and can cause hemolytic anemia in breastfed infants; however, it is approved by the American Academy of Pediatrics for use during lactation when required, as in patients with leprosy8.

Drug Interactions Drugs that may increase dapsone levels (and side effects) are probenecid (via decreased renal clearance), trimethoprim, and other

folate antagonists such as methotrexate. Sulfonamides and hydroxychloroquine increase the oxidative stress on RBCs and may worsen hemolysis. Dapsone levels may be reduced by activated charcoal, paraaminobenzoic acid (PABA), and rifampin. Although cimetidine can increase absolute levels of dapsone, the former leads to a reduction in the more toxic hydroxylamine metabolite, and thus the end result is a lower level of methemoglobin.

HYDROXYUREA

CHAPTER

130 Other Systemic Drugs

chemotaxis to N-formyl-methionyl-leucyl-phenylalanine (fMLP) and to interfere with the CD11b/CD18-mediated neutrophil binding that induces chemoattractant signal transduction. IgA adherence is also inhibited. It is of clinical interest that dapsone also inhibits eosinophil myeloperoxidase activity, and thus may be efficacious in diseases in which eosinophils have a central role in pathogenesis, such as eosinophilic cellulitis28.

The dosage, uses, and side effects are outlined in Table 130.11.

LEUKOTRIENE (LT) INHIBITORS Initially identified as the slow-reacting substance of anaphylaxis, leukotrienes play a key role in systemic and cutaneous inflammatory reactions30. Primarily used for the treatment of asthma, leukotriene inhibitors have been explored in a myriad of dermatologic conditions, including atopic dermatitis, urticaria, autoimmune bullous diseases, and Sjögren–Larsson syndrome30. These inhibitors include montelukast (Singulair®), zafirlukast (Accolate®), and pranlukast (Ultair®), which block LTC4, LTD4 and LTE4, as well as zileuton (Zyflo CR®) which inhibits 5-lipoxygenase. Originating from arachidonic acid, LTA4 is metabolized by divergent pathways to either LTB4 or to the cysteinyl leukotrienes LTC4, LTD4 and LTE4 (Fig. 130.6). LTB4 mediates its effect through the BLT receptor(s), triggering chemotaxis of neutrophils, eosinophils, and monocytes. By binding with cysteinyl leukotriene receptors, LTC4, LTD4 and LTE4 cause bronchoconstriction, increased vascular permeability, smooth muscle contraction, mucus secretion, and edema30. Leukotrienes and leukotriene receptors are widely distributed throughout the body, but their concentration and relative importance are organand cell type-specific. Leukotriene inhibitors abrogate the biologic effects of these mediators (Table 130.12).

HYDROXYUREA ®

Formulation: Hydrea ; 100% bioavailable; renal excretion: 80%; accumulates preferentially in leukocytes > erythrocytes; can cross blood–brain barrier Mechanism of action: inhibits M2 subunit of ribonucleotide reductase thereby blocking DNA synthesis; cells are arrested in G2 phase and unable to repair UV- and ionizing radiation-induced damage; also causes gene hypomethylation, inducing differentiation and normalization of psoriatic skin; resistance may arise via increased levels of ribonucleotide reductase or alteration of the enzyme Dermatologic use: maintenance therapy of psoriasis after control with another drug or phototherapy; ineffective in psoriatic arthritis; lymphocytic hypereosinophilic syndrome unresponsive to corticosteroids Dosage: 20–30 mg/kg/day in divided doses, with a maximum of 2 g/day; average dose: 1–2 g/day Side effects: megaloblastosis (all patients), with 10–35% developing anemia (see Table 130.5); rarely, leukopenia, thrombocytopenia, or transient reversible hepatitis with an acute “flu-like” syndrome; ulcers of the distal lower extremity (Fig. 130.5A); diffuse cutaneous hyperpigmentation and mucosal pigmentation (Fig. 130.5B); dermatomyositis-like eruption on dorsal hands Monitoring guidelines: baseline CBC with PLT, CMP, UA, and pregnancy test for women of childbearing potential then CBC with PLT weekly until stable and then monthly; CMP and UA monthly until stable then every 3–6 months; a drop in HGB of 1–2 g should be expected; discontinue hydroxyurea if: HGB declines by more than 3 g, WBC drops to siro), hyperlipidemia, posterior reversible encephalopathy syndrome (PRES; tacro > CSA or siro); tacrolimus: hyperkalemia (esp. in conjunction with ACE inhibitors) Monitoring guidelines: see those for CSA (see Table 130.3); lower dose or discontinue treatment if serum creatinine rises by >30% of baseline Contraindications: uncontrolled hypertension, significant renal impairment, prior hypersensitivity reaction to drug; see contraindications for cyclosporine; tacrolimus: for parenteral administration, allergy to HCO-60 (polyoxyl 60 hydrogenated castor oil that is used as a surfactant) Pregnancy and lactation: for dermatologic disorders, should be avoided during pregnancy (formerly category C) and lactation (concentrated in breast milk) Drug interactions: other renal-toxic drugs

Table 130.16 Sirolimus (rapamycin; Rapamune®) and tacrolimus (Prograf®). There is significantly less hypertrichosis as compared to cyclosporine. CSA, cyclosporine; siro, sirolimus; tacro, tacrolimus.  

subsequently tapered to 25–50 mg/day after a clinical effect is seen, usually within 2 weeks. Acute cutaneous lesions of SLE have up to a 90% resolution rate, but require higher doses and longer treatment periods before results are noted. For some patients, intermittent courses of thalidomide (for 2–3 months) can be used to clear lesions, with antimalarials given concomitantly and as maintenance therapy.

Major Side Effects A single dose of thalidomide during the first 21–36 days of gestation yields a 100% incidence of birth defects (see Table 130.5). Sedation is by far the most common adverse side effect and may necessitate nighttime dosing and gradual titration of the dose. Constipation is also common. Permanent nerve damage (primarily sensory neuropathy) can develop and is more common with long-term therapy. Measurements of sensory nerve action potential amplitudes (SNAP) may be indicated before and/or during therapy. Amenorrhea and primary ovarian failure may occur. Severe leukopenia, exfoliative erythroderma, and TEN are rare consequences of thalidomide treatment. A hypersensitivity reaction specific to HIV-positive patients has been described. Common dermatologic side effects include brittle fingernails, xerosis, pruritus, and red palms. Peripheral edema can develop occasionally. Vascular thromboses are unusual unless the patient is receiving concomitant corticosteroids.

Indications 2294

Thalidomide is FDA-approved and 99% effective for ENL (type II leprosy reaction) although it has no effect on type I leprosy reactions. A

Fig. 130.8 Viral-associated trichodysplasia in a renal transplant recipient receiving tacrolimus, mycophenolate mofetil and prednisone. Numerous skin- to pink-colored folliculocentric papules, many with central spiny excrescences, developed on the nose and cheeks. This disorder is most commonly seen in the setting of immunosuppression due to systemic calcineurin inhibitors. Courtesy, Mark Kirchhof, MD, and Sheila Au, MD.  

variety of off-label uses of thalidomide have emerged over the years (see Table 130.6)42. Although HIV-associated mucosal ulceration, as well as aphthae associated with neutrophilic dermatoses (including Behçet disease), respond rapidly to thalidomide, ulcerations relapse quickly when the drug is discontinued. Curiously, the highest rate of peripheral neuropathy has been observed in prurigo nodularis patients42. Given the minimal risk for associated neuropathy, lenalidomide has been used to treat severe, refractory cutaneous LE and prurigo nodularis; it has also shown some promise in patients with scleromyxedema. Pomalidomide is currently being investigated for sclerotic skin disorders. The cost of these analogues, however, may limit their use.

Contraindications Absolute contraindications to thalidomide therapy include sensitivity to the drug, pregnancy, and a pre-existing peripheral neuropathy. Women of childbearing potential must agree to use highly effective methods of birth control (e.g. two reliable forms of contraception simultaneously). Men taking thalidomide who have female partners of childbearing potential must wear condoms (even if they have had a vasectomy) while their partners use an additional form of birth control (either oral or barrier). Relative contraindications include significant hepatic or renal disease, a history of neurologic disease, congestive heart failure, hypertension, constipation, and hypothyroidism. In patients with a predisposing condition (e.g. antiphospholipid antibodies, myeloma), there can be an increased risk of thromboses. Individuals receiving antimalarials should continue to do so, because these drugs have been reported to inhibit platelet aggregation and adhesion.

Use in Pregnancy and Lactation Thalidomide was formerly pregnancy prescribing category X and should not be used in pregnant women8. It is also wise to avoid thalidomide in nursing mothers.

Drug Interactions Thalidomide may amplify the sedative effects of alcohol, barbiturates, chlorpromazine, and reserpine. Any drug that significantly induces the CYP3A4 enzymes may decrease the effectiveness of hormonal contraception, increasing the potential of pregnancy and, thus, teratogenicity. For additional online figure visit www.expertconsult.com

non-print metadata

CHAPTER

Other Systemic Drugs

130

Baseline

Week 16

PASI-85

PASI-69

eFig. 130.1  Response of plaque psoriasis to apremilast. Courtesy, J. Mark Jackson, MD.

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1. US Food and Drug Administration. Content and format of labeling for human prescription drug and biological products; requirements for pregnancy and lactation labeling. Fed Regist 2014;79:72064–103. 1a.  Callen JP, Camisa C. Antimalarial agents. In:   Wolverton SE, editor. Comprehensive Dermatologic Drug Therapy. 3rd ed. Philadelphia: WB Saunders; 2013. p. 241–51. 2. Wozniacka A, Carter A, McCauliffe DP. Antimalarials in cutaneous lupus erythematosus: mechanisms of therapeutic benefit. Lupus 2002;11:71–81. 2a.  Marmor MF, Kellner U, Lai TYY, et al. Recommendations on screening for chloroquine and hydroxychloroquine retinopathy (2016 Revision). Ophthalmology 2016;123:1386–94. 3. Weiss JS. Antimalarial medications in dermatology. Dermatol Clin 1991;9:377–85. 4. Marmor MF, Kellner U, Lai TYY, et al. Revised recommendations on screening for chloroquine and hydroxychloroquine retinopathy: a report by the American Academy of Ophthalmology. Ophthalmology 2011;118:415–22. 5. Mavrikakis I, Sfikakis PP, Mavrikakis E, et al. The incidence of irreversible retinal toxicity in patients treated with hydroxychloroquine: a reappraisal. Ophthalmology 2003;110:1321–6. 6. Melles RB, Marmor MF. The risk of toxic retinopathy in patients on long-term hydroxychloroquine therapy. JAMA Ophthalmol 2014;132:1453–60. 7. Kalia S, Dutz JP. New concepts in antimalarial use and mode of action in dermatology. Dermatol Ther 2007;20:160–74. 8. Briggs GG, Freeman RK, Yaffe SJ. Drugs in Pregnancy and Lactation. 9th ed. Philadelphia: Lippincott Williams & Wilkins; 2011. 9. Schafer P. Apremilast mechanism of action and application to psoriasis and psoriatic arthritis. Biochem Pharmacol 2012;83:1583–90. 10. Papp K, Reich K, Leonardi CL, et al. Apremilast, an oral phosphodiesterase 4 (PDE4) inhibitor, in patients with moderate to severe plaque psoriasis: Results of a phase III, randomized, controlled trial (Efficacy and Safety Trial Evaluating the Effects of Apremilast in Psoriasis [ESTEEM] 1). J Am Acad Dermatol 2015;73:37–49. 11. Rich P, Gooderham M, Bachelez H, et al. Apremilast, an oral phosphodiesterase 4 inhibitor, in patients with difficult-to-treat nail and scalp psoriasis: Results of 2 phase III randomized, controlled trials (ESTEEM 1 and ESTEEM 2). J Am Acad Dermatol 2016;74:134–42. 12. Badalamenti S, Kerdel FA. Azathioprine. In:   Wolverton SE, editor. Comprehensive Dermatologic

Drug Therapy. 3rd ed. Philadelphia: WB Saunders; 2013. p. 182–9. 13. Patel A, Swerlick R, McCall C. Azathioprine in dermatology: the past, the present, and the future.   J Am Acad Dermatol 2006;55:369–89. 14. Stern DK, Tripp JM, Ho VC, Lebwohl M. The use of systemic immune moderators in dermatology: an update. Dermatol Clin 2005;23:259–300. 15. Liu H, Wong C. In vitro immunosuppressive effects of methotrexate and azathioprine on Langerhans cells. Arch Dermatol 1997;289:94–7. 16. Wise M, Callen JP. Azathioprine: a guide for the management of dermatology patients. Dermatol Ther 2007;20:206–15. 17. Ahmed AR, Hombal SM. Cyclophosphamide, a review on relevant pharmacology and clinical uses. J Am Acad Dermatol 1984;11:1115–26. 18. High WA. Cytotoxic agents. In: Wolverton SE, editor. Comprehensive Dermatologic Drug Therapy. 3rd ed. Philadelphia: WB Saunders; 2013. p. 212–27. 19. Bhutani T, Lee CS, Koo JYM. Cyclosporine. In:   Wolverton SE, editor. Comprehensive Dermatologic Drug Therapy. 3rd ed. Philadelphia: WB Saunders; 2013. p. 199–211. 20. Dutz JP, Ho VC. Immunosuppressive agents in dermatology, an update. Dermatol Ther 1998;16:235–51. 21. Koo J, Lee J. Cyclosporine, what clinicians need to know. Psoriasis 1995;13:897–907. 22. Amor KT, Ryan C, Menter A. The use of cyclosporine in dermatology Part I and II. J Am Acad Dermatol 2010;63:925–72. 23. Grossman RM, Chevret S, Abi-Rached J, et al. Long-term safety of cyclosporin in the treatment of psoriasis.   Arch Dermatol 1996;132:623–9. 24. Zachariae H. Renal toxicity of long-term cyclosporin. Scand J Rheumatol 1999;28:65–8. 25. Luke RG. Mechanism of cyclosporine-induced hypertension. Am J Hypertension 1991;4:  468–71. 25a.  Zimmermann S, Sekula P, Venhoff M, et al. Systemic immunomodulating therapies for Stevens-Johnson syndrome and toxic epidermal necrolysis: A systematic review and meta-analysis. JAMA Dermatol 2017;153:514–22. 26. Madan V, Griffiths CEM. Systemic ciclosporin and tacrolimus in dermatology. Dermatol Ther 2007;20:239–50. 27. Wolf R, Tuzun B, Tuzun Y. Dapsone: unapproved uses or indications. Clin Dermatol 2000;18:37–53.

28. Edhegard K, Hall RP. Dapsone. In: Wolverton SE, editor. Comprehensive Dermatologic Drug Therapy. 3rd ed. Philadelphia: WB Saunders; 2013. p. 228–40. 29. Coleman MD. Dapsone: modes of action, toxicity and possible strategies for increasing patient tolerance.   Br J Dermatol 1993;129:507–13. 30. Wedi B, Kapp A. Pathophysiological role of leukotrienes in dermatologic diseases: potential therapeutic implications. Biodrugs 2001;15:729–43. 31. Bangert CA, Costner MI. Methotrexate in dermatology. Dermatol Ther 2007;20:216–28. 32. Olsen EA. The mechanism of action of methotrexate. Rheum Dis Clin North Am 1997;23:739–55. 33. Kalb RE, Strober V, Weinstein G, Lebwohl M. Methotrexate and psoriasis: 2009 National Psoriasis Foundation Consensus Conference. J Am Acad Dermatol 2009;60:824–37. 34. Schmeltzer PA, Talwalkar JA. Noninvasive tools to assess hepatic fibrosis: ready for prime time? Gastroenterol Clin North Am 2011;40:507–21. 35. Orvis AK, Wesson SK, Breza TS Jr, et al. Mycophenolate mofetil in dermatology. J Am Acad Dermatol 2009;60:183–99. 36. Neff RT, Hurst FP, Falta EM, et al. Progressive multifocal leukoencephalopathy and use of mycophenolate mofetil after kidney transplantation. Transplantation 2008;86:1474–8. 37. Perez-Aytes A, Ledo A, Boso V, et al. In utero exposure to mycophenolate mofetil: a characteristic phenotype? Am J Med Genet A 2008;146A:1–7. 38. Ang GS, Simpson SA, Reddy AR. Mycophenolate mofetil embryopathy may be dose and timing dependent. Am J Med Genet A 2008;146A:1963–6. 39. Powell RJ, Gardner-Medwin JMM. Guideline for the clinical use and dispensing of thalidomide. Postgrad Med J 1994;70:901–4. 40. Davis LS, LeBlanc KG, Knable AL, Owen CE. Miscellaneous systemic drugs. In: Wolverton SE, editor. Comprehensive Dermatologic Drug Therapy. 3rd ed. Philadelphia: WB Saunders; 2013. p. 424–43. 41. Kotla V, Goel S, Nischal S, et al. Mechanism of action of lenalidomide in hematological malignancies. J Hematol Oncol 2009;2:36. 42. Faver IR, Guerra SG, Su WP, el-Azhary R. Thalidomide for dermatology: a review of clinical uses and adverse effects. Int J Dermatol 2005;44:61–7. 43. Rodriguez-Caruncho R, Bielsa Marsol I. Antimalarials in dermatology: mechanism of action, indications, and side effects. Actas Dermosifiliogr 2014;105:243–52.

130 Other Systemic Drugs

REFERENCES

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SECTION 19 MEDICAL THERAPY

131 

Drug Interactions Lori E. Shapiro, Sandra R. Knowles and Neil H. Shear

Chapter Contents Putting interactions into perspective . . . . . . . . . . . . . . . . . 2296 Assessment of risk in the clinical outcome of drug   interactions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2296 Levels of evidence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2297 Absorption . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2297 Distribution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2299 Drug biotransformation . . . . . . . . . . . . . . . . . . . . . . . . . . 2300 The confusing world of drug interactions . . . . . . . . . . . . . . 2301 How to minimize the risk of drug–drug interactions . . . . . . . 2304

INTRODUCTION There are two concerns in drug safety: drug reactions and drug interactions. When multiple medications are prescribed, drug interactions become an important safety and efficacy consideration for patients and physicians alike1. Non-prescription drugs, as well as herbal or alternative medicines and foods (such as grapefruit juice), may also be implicated in interactions with drug therapy. It is difficult to obtain precise rates of incidence and prevalence, as specific diagnostic codes for drug interactions are lacking2. Drug interactions are known to be responsible for up to 2.8% of hospital admissions3,4. It has been estimated that adverse drug outcomes occur about once every 100 patient days3,5. Although it is impossible to remember all potential drug interactions, knowledge of the interactive properties of drugs can help reduce the risk of serious adverse outcomes. Moreover, it is the responsibility of physicians to counsel patients regarding drug interactions6. Unfortunately, even when serious new drug interactions are recognized and reported, physicians, pharmacists and patients are often unaware that there is a risk7.

PUTTING INTERACTIONS INTO PERSPECTIVE

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Prescribing drugs with the potential for a deleterious interaction increases the risk of, but need not lead to, an adverse outcome. Many drug–drug interactions are susceptible to control by dose adjustment. Some interactions can even be exploited for a therapeutic advantage, e.g. coadministration of erythromycin to increase cyclosporine levels as a means of reducing costs associated with the latter. While most drugs are associated with interactions, many do not produce significant outcomes8. In fact, not all listed or reported drug interactions are actually clinically significant. Whereas some have little clinical relevance, others are clearly defined as contraindications on the basis of substantiation of risk, potential severity, and frequency of occurrence. Still others can be successfully managed by dosage adjustment and monitoring. In one study that examined the occurrence of drug interactions, based upon adverse events reported during large clinical trials9, the authors concluded that serious adverse drug reactions (ADRs) secondary to drug–drug interactions were infrequent; however, drug– drug interactions that involved selected drugs with a narrow therapeutic index (which elicited life-threatening undesired effects) did occur. Drug– drug interactions are the most common cause of medication errors in high-income countries, with a prevalence of 20–40%, especially due to polypharmacy in the elderly10. Thus, for most drug interactions, it is necessary to assess each patient situation individually.

ASSESSMENT OF RISK IN THE CLINICAL OUTCOME OF DRUG INTERACTIONS The clinical importance of specific drug interactions is often either over- or underestimated, as these assessments are largely based on clinical experience in using a particular drug combination11. The clinical outcome of most drug interactions is highly situational, as most patients who receive drugs with the potential for interactions do not develop adverse effects. Emphasis should be placed on those factors that increase or decrease the risk to a given patient. In order to prevent or detect drug interactions, the physician needs to identify risk factors in each individual patient. That said, some patient groups are more likely than others to develop adverse events caused by drug interactions. Identified risk factors are listed in Table 131.1 and are grouped by category12. The elderly frequently experience drug interactions because of the physiologic changes that accompany the aging process and the types of drugs that older patients tend to receive13. Polypharmacy, which is common in the elderly, makes them particularly susceptible. In addition, medications may impair pathways of drug elimination by interfering with drug metabolism, thereby increasing the likelihood of adverse drug reactions. Alterations due to advanced age, including changes in drug–protein binding and drug distribution within tissue, may also promote drug interactions. Of note, most adverse metabolic drug interactions occur when an inhibitor or inducer is begun in a patient who previously had stable levels of a substrate drug. HIV-infected patients also have a high rate of adverse drug reactions14. In some instances, this may relate to phenotypic changes in drug metabolism, which can vary with progression of the underlying HIV infection15. The latter can alter enzyme function, with resultant changes in drug metabolism and a higher rate of adverse reactions in these patients. A major source of interindividual differences in drug metabolism is genetic polymorphisms, which are inherited and can result in significant variations in the activity of drug-metabolizing enzymes. For example, the genes encoding cytochrome P450 (CYP) isoforms are highly polymorphic (see Table 131.13). In some cases, it is actually possible to determine an individual’s genotype16. Further details on genetic polymorphisms are discussed later in the chapter. Interactions with other drugs can predispose a patient to the development of certain types of ADR. For example, coadministration of valproic acid increases the risk of severe cutaneous adverse reactions to lamotrigine17, and allopurinol increases the risk of exanthematous eruptions to antibiotics such as amoxicillin. A disease state itself may directly affect the likelihood of an ADR. For example, active infection with Epstein–Barr virus or cytomegalovirus also increases the risk of exanthematous eruptions to amoxicillin. The basis of these interactions is unknown but may represent a combination of factors, including alterations in drug metabolism, drug detoxification, antioxidant defenses, and immune reactivity18. The disease state may also dictate the way in which a drug is prescribed, and this will subsequently affect the outcome. When a drug has more than one therapeutic action, an interacting drug may affect the action of the first drug when it is used to treat one disease but not when it is used to treat the first disease. This is known as pharmacologic selectivity. An example of intrinsic effects of disease states would be when epinephrine (adrenaline) is given to patients receiving non-cardioselective β-adrenergic blockers (but who do not have anaphylaxis) and this results in hypertension. In contrast, the same β-blockers inhibit the pressor response to epinephrine when the latter is given to patients with anaphylaxis19.

Interactions between or amongst multiple therapies may lead to increased toxicity, decreased efficacy, or both. Knowledge of the interactive properties of drugs can help prevent serious adverse drug interactions. Non-prescription drugs, herbal or alternative medicines, and foods (e.g. grapefruit juice) may also be implicated in drug interactions. Prediction of drug interactions is possible when those agents likely to produce alterations in drug metabolism via inhibition or induction of the cytochrome P450 (CYP) system are recognized. The CYP enzymes are the most important drug-metabolizing enzymes. They are present in the endoplasmic reticulum of many types of cells, but are at highest concentration in hepatocytes. Fortunately, the metabolism of most drugs can be accounted for by a relatively small subset of the CYP isoforms. It is thought that over 90% of human drug oxidation can be attributed to six enzymes (isoforms): CYP1A2, 2C9/10, 2C19, 2D6, 2E1, and 3A4. One-third to one-half of drug metabolism can be attributed to CYP3A4. Knowledge of the substrates, inhibitors, and inducers of these enzymes assists in predicting clinically significant drug interactions. The isoform CYP2D6 is involved in about one-fourth of all drug metabolism. The concept that most drug oxidation reactions are catalyzed primarily by a small number of CYP enzymes is important in that approaches to identifying drug–drug interactions become more feasible, both in vitro and in vivo. Knowledge of the interactive potential of various drugs can help prevent serious adverse drug interactions. Drug interactions primarily involve an “object drug” (“bullet”, substrate) that is the drug affected by the interaction and “precipitant drug” (“accomplice”, inhibitor, inducer), which is the drug causing the interaction. The most important “precipitant” drugs interfere with drug absorption, distribution, metabolism, and elimination. Foods, such as grapefruit juice, are also important precipitants. Many of these drug combinations can be administered safely with appropriate dosage adjustments or by substitution with another member of the drug class with less potential for drug–drug interactions. The clinical importance of specific drug interactions is often either overestimated or underestimated, as these assessments are largely based on clinical experience in using the particular drug combination. The clinical outcome of most drug interactions is highly situational, and most patients who receive drugs with the potential for interactions do not develop adverse effects. Emphasis should be placed on those factors that increase or decrease the risk for a given patient. While it is clearly not possible for individual clinicians to remember all drug interactions, it is important to understand how to use the drug interaction information provided by electronic medical record programs, PubMed, Micromedex® Drug Reference, books, and other sources.

drug interactions, drug absorption, drug distribution, drug metabolism, cytochrome P450, CYP3A4, P-glycoprotein, cytochrome P450 inhibition, cytochrome P450 induction, genetic polymorphisms

CHAPTER

131 Drug Interactions

ABSTRACT

non-print metadata KEYWORDS:

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Multiple medications, i.e. polypharmacy Demographic risk factors – Female gender – Extremes of age – very young and elderly • Major organ dysfunction, especially in the setting of multiple medical problems – Liver dysfunction – Renal insufficiency * – Congestive heart failure • Metabolic and endocrine risk factors – Obesity – Hypothyroidism – Hypoproteinemia • Pharmacogenetic risk factors – Slow acetylator phenotype – Reduced thiopurine methyltransferase (TPMT) activity – Other genetic polymorphisms (see text and Table 131.13) • Other medical issues – Hypothermia – Hypotension – Dehydration • •

*May be underestimated in elderly patients. Table 131.1 Patient risk factors for drug interactions13.  

An example of a dose-dependent drug interaction is the concomitant use of nonsteroidal anti-inflammatory drugs (NSAIDs) and methotrexate. Available evidence indicates that the risk of this combination is considerably greater in patients receiving high-dose methotrexate as cancer chemotherapy than it is in patients receiving lower weekly dosages for psoriasis20. This is because the distribution of the drug is not very important mechanistically in determining drug interactions, but changes in drug elimination are. When larger doses of methotrexate (as used in cancer therapy) are given in combination with an NSAID, reduced drug elimination via the kidneys becomes an important issue, increasing the risk of methotrexate toxicity. Gender-related differences in pharmacokinetics may cause variations in drug absorption, gastric emptying, and distribution based on percentage of adipose tissue21. Gender-related differences in receptor density and sensitivity, enzyme activity (CYP2D6), and underlying disease activities also contribute to pharmacokinetic variation. The effect of obesity on metabolism is cytochrome-specific. For example, obesity decreases the activity of CYP3A4 and increases the activity of CYP2E1. Certain medications are clearly more likely to be involved in drug interactions. More specifically, clinically significant interactions occur more frequently with drugs that have a narrow margin of safety, i.e. a narrow therapeutic window. Drugs with the potential for such serious interactions include warfarin and cyclosporine. When prescribing a new medication that could potentially interact with warfarin, it is prudent to have the patient’s international normalized ratio (INR) measured within 2–3 days of administration of the new drug. Medication-related factors that contribute to clinical risk include the dose, route of administration and duration of administration of the precipitant drug (the drug that causes the interaction) as well as the sequence of administration of the interacting drugs. Most metabolic drug interactions are dose-related. That is, as the dose of the precipitant drug is increased, the magnitude of its effect on the object drug tends to increase. Thus, the dose of the precipitant drug is often an important determinant of risk. However, the dose of the object drug may also affect the risk of an adverse drug interaction. For example, a patient who takes small doses of an object drug with serum concentrations at the lower end of the target range is at a lesser risk when an enzymeinhibiting precipitant drug is added, than would be a patient taking large doses of the same object drug. Lastly the bioavailability of either drug may have an impact. The route of administration is an important risk factor for some non-metabolic drug interactions, such as when one drug binds to another in the gastrointestinal (GI) tract. However, the route of administration can also be important for metabolic drug interactions, especially when the drug undergoes extensive first-pass metabolism in the gut wall and liver by CYP3A4 or P-glycoprotein (see below).

CHAPTER

131 Drug Interactions

PATIENT RISK FACTORS FOR DRUG INTERACTIONS

Most drug interactions also have a typical time course over which the effects develop. For example, giving rifampin, a typical inducer of CYP3A4, for only a few days is unlikely to have much effect on substrates of CYP3A4, as induction of an enzyme takes weeks to occur. In summary, there is pharmacodynamic and pharmacokinetic variability between people, as well as host variability in terms of disease state. Overall, this variability contributes to confusion, as tables and lists that outline potentially interacting medications vary amongst different sources. One reason is that various levels of evidence exist for many of these drugs in terms of their ability to contribute to/cause drug interactions. This is outlined in more detail in the next section.

LEVELS OF EVIDENCE Drug interaction literature is often confusing due to poorly substantiated claims22. This confusion occurs as a result of inaccurate or cursory evaluations of published cases or inappropriate extrapolations from the literature. Metabolic drug interactions are a major source of potential clinical problems, but their investigation during drug development is often incomplete. In vitro studies give very accurate data on the interactions of drugs with selective CYP isozymes, but their interpretation in the clinical context is difficult. Although in vitro systems have been developed to test the effects of certain drugs on the metabolism of other drugs, these systems may not accurately predict the effect in patients receiving drugs with complex metabolism. Also, problems with the detection of adverse events after a drug has been released arise mainly because such events are rare. It takes a surveillance system with a high degree of sensitivity to detect such problems23. Furthermore, most in vivo and in vitro studies of drug interactions evaluate two-drug regimens, and the results may not apply to the multidrug regimens used clinically. This is especially true for a regimen consisting of three or more drugs with opposing effects on CYP3A4 metabolism. The lack of studies of multiple drug interactions provides little assistance to the prescribing physician, who is left to rely on adverse events or treatment failure to demonstrate whether an interaction has occurred. In addition, the design of in vivo studies is sometimes poor (choice of prototype substrate, doses, schedule of administration, number of volunteers), with the risk of minimizing the real potential for interaction. To link in vitro and in vivo studies, several authors have suggested using extrapolation techniques, based on the comparison of in vitro inhibition data with the active in vivo concentrations of the inhibitor. However, the lack of knowledge with regard to one or several important parameters, such as the role of metabolites and intrahepatocyte accumulation, often limits the ability to make safe and accurate predictions. The uncertainty and inaccuracy of predicting the extent and duration of in vivo drug interactions currently stems from a lack of definitive models by which to assess likely substrate and inhibitor concentrations at the active site of metabolism. Additional issues contributing to the uncertainty of predicting drug interactions include assumptions of the contribution of presystemic drug extraction and the effect of inhibitors on the processes involved. As a consequence, these methods are useful for complementing in vivo studies and helping to design clinically relevant in vivo studies, but in the foreseeable future they will not totally replace in vivo investigations.

ABSORPTION Interactions that alter the absorption of drugs often lead to dramatic changes in plasma drug concentrations. Drug interactions within the GI tract can result in decreased absorption. This reduces the bioavailability or the amount of drug available to the systemic circulation and results in subtherapeutic serum concentrations. The underlying mechanisms of most drug interactions that alter GI absorption involve: (1) the formation of drug complexes that reduce absorption; (2) alterations in gastric pH; and/or (3) changes in GI motility that alter transit time24. Common drugs that form complexes with other drugs include antacids, sucralfate, and bile acid sequestrants (e.g. cholestyramine, colestipol, colesevelam) (Table 131.2). A significant interaction occurs between multivalent cations – such as calcium, aluminum, iron and magnesium – and tetracyclines or fluoroquinolone antibiotics. For example, there is an 85% reduction in the absorption of ciprofloxacin

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SECTION

Medical Therapy

19

DRUG INTERACTIONS THAT REDUCE THE EFFICACY OF SUBSTRATES

Mechanism

Substrate/parent drug

Reduced GI absorption

Itraconazole Ketoconazole^

Rapid

Dapsone Mycophenolate mofetil Calcineurin inhibitors   Cyclosporine   Tacrolimus Oral contraceptives Corticosteroids   Dexamethasone   Methylprednisolone   Prednisone Warfarin

Anticonvulsants   Carbamazepine   Phenytoin   Phenobarbital Antituberculous agents   Isoniazid Rifampin Dexamethasone Griseofulvin

1–2 weeks

Epinephrine Cyproheptadine

β-Blockers SSRI antidepressants Fluoxetine Paroxetine

Tetracycline Bisphosphonates

Antagonistic effects

Time course

Antacids* Didanosine H2 antihistamines Proton pump inhibitors Sucralfate Antacids* Iron Sucralfate Divalent cations   Calcium   Magnesium   Iron Didanosine Iron Antacids*

Fluoroquinolones

Induction of CYP3A4†

Concomitant drugs

MYCOPHENOLATE METABOLISM Mycophenolate mofetil (MMF)

Antacids and iron

Tacrolimus (?)

Hydrolyzation

MMF

Glucuronyl transferase

Mycophenolic acid (MPA)

May reduce MMF absorption

MPA

MPAG

Active MPA molecule

Absorption through gut wall

Bile excretion of inactive Gut bacteria remove metabolite glucuronide chain MPA Cyclosporine

Fig. 131.1 Mycophenolate metabolism. Mycophenolate is hydrolyzed to mycophenolic acid (MPA). Following glucuronidation in the liver, inactive MPA glucuronide (MPAG) is excreted into the gut via bile acid secretion. In the gut, bacteria remove the glucuronide chain to produce MPA, the active molecule, which is then reabsorbed through the gut wall. Cyclosporine impairs MPA enterohepatic recirculation by inhibiting biliary excretion of MPAG (thereby decreasing MPA levels), whereas tacrolimus may inhibit UDP-glucuronyl transferase (thereby increasing MPA levels).  

^Has been withdrawn by the European Medicines Agency and per the US FDA, it is no

longer indicated for Candida or dermatophyte infections or as first-line therapy for chromomycosis or dimorphic fungal infections. *† Often contain aluminum hydroxide, magnesium hydroxide and/or calcium carbonate. Also A5, A7.

Table 131.2 Drug interactions that reduce the efficacy of substrates. In addition, bile acid sequestrants (e.g. cholestyramine, colestipol, colesevelam) dramatically reduce GI absorption of furosemide and thiazide diuretics. GI, gastrointestinal; SSRI, selective serotonin reuptake inhibitors.  

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when ingested 5–10 minutes after a dose of an aluminum hydroxide/ magnesium hydroxide antacid25. These interactions can be easily avoided by administering the fluoroquinolone at least 2 hours before or 6 hours after the antacid or iron. Alendronate, as well as other bisphosphonates prescribed for the prevention and treatment of osteoporosis, forms complexes with cations and several other drugs, thereby further decreasing their already low oral absorption. Once-weekly dosing reduces the opportunity for bisphosphonate-related interactions. When mycophenolate mofetil and iron preparations were administered concomitantly, a significant decrease in mycophenolate mofetil absorption was observed (Fig. 131.1)26. Drugs that increase gastric pH, such as proton pump inhibitors, antacids and H2 antihistamines, may reduce the absorption of drugs such as itraconazole, posaconazole and ketoconazole, which are best absorbed in an acidic environment27. Although itraconazole is best absorbed when the gastric pH is low, its administration with food is more important for achieving high plasma concentrations28. Of note, the absorption of fluconazole is unaffected by variations in gastric pH. Similarly, the coadministration of drugs that can increase gastric pH (see above) with atazanavir and raltegravir are not recommended. Drugs that affect GI motility, such as anticholinergic agents, may decrease the rate of absorption but not the extent of absorption. An overall reduction in drug absorption has more clinical significance29. Some drugs may interfere with the enterohepatic recirculation of a substrate drug. When the substrate is excreted into the GI tract, a

second drug can bind to it and prevent its reabsorption back into the systemic circulation. The bound substrate drug is excreted in the feces, thereby effectively shortening its half-life. An example of this is the concurrent administration of warfarin and bile acid sequestrants (e.g. cholestyramine, colestipol, colesevelam) in which the half-life of warfarin is shortened.

P-glycoprotein (PGP) Membrane-bound transport systems may also determine drug disposition30. These transporters are found in multiple tissues and actively pump drug molecules either out of cells (efflux) or into cells (uptake). PGP is an ATP-dependent plasma membrane glycoprotein belonging to the superfamily of ATP-binding cassette transporters that functions primarily as an efflux pump (Fig. 131.2)31. Other transporters include the organic anion and organic cation transporters. In humans, the multidrug resistance (MDR) genes, including MDR1, encode membrane glycoproteins that function as drug transporters and hence affect both drug absorption and elimination. High levels of PGP are found in superficial columnar epithelial cells of the small intestine, the apical surface of epithelial cells in the proximal tubules of the kidney, and in the biliary canalicular membrane of hepatocytes. PGP is also detected in high concentrations in the endothelial cells of the capillaries of the blood–brain barrier, testes, uterus and placenta. An understanding of the physiologic regulation of these transporter proteins is key to designing strategies for improving the therapeutic efficacy of drugs that serve as their substrates (Table 131.3). These membrane-bound transport systems appear to have developed as a mechanism for protecting the body from harmful substances. It appears that PGP acts as a pump whereby the efflux of drugs from the cell membrane or cytoplasm is powered by the energy from ATP hydrolysis. For example, the aminoglycoside antibiotics amikacin and tobramycin are not effectively delivered orally, perhaps because of active efflux from the brush border cells of the small intestine by the PGP pump. The most remarkable property of PGP is its ability to transport a diverse array of compounds that do not appear to share obvious structural characteristics. The range of substrates, inhibitors, and inducers of PGP is vast and expanding (Tables 131.3 & 131.4).

CHAPTER

Antimicrobials

131

INHIBITORS OF P-GLYCOPROTEIN

HIV protease inhibitors

Cardiac agents

Antimicrobials

Psychotropic agents

Cardiac agents

Ciprofloxacin

Indinavir

Amiodarone

Clarithromycin

Amitriptyline

Amiodarone

Erythromycin

Nelfinavir

Atorvastatin

Erythromycin

Chlorpromazine

Carvedilol

Ivermectin

Ritonavir

Digoxin

Itraconazole

Desipramine

Diltiazem

Other quinolones

Saquinavir

Diltiazem

Ivermectin

Disulfiram

Dipyridamole

Rifampin

Antiemetics

Lovastatin

Ketoconazole

Doxepin

Felodipine

Anticancer agents

Domperidone

Nadolol

Mefloquine

Fluphenazine

Nicardipine

Actinomycin D

Ondansetron

Pravastatin

Ofloxacin

Haloperidol

Nifedipine

Daunorubicin

Rheumatologic agents

Propranolol

Posaconazole

Imipramine

Propranolol

Docetaxel

Colchicine

Quinidine

Rifampin

Steroid hormones

Verapamil

Doxorubicin

Methotrexate

Timolol

Voriconazole

Progesterone

Miscellaneous

Etoposide

Quinine

Verapamil

Immunosuppressives

Testosterone

Grapefruit juice

Mitomycin C

Immunosuppressives

Miscellaneous

Cyclosporine Tacrolimus

Paclitaxel

Cyclosporine

Cimetidine

Vinblastine

Tacrolimus

Lidocaine

Vincristine

Orange juice isoflavones Ritonavir Tamoxifen

Loperamide Terfenadine*

Drug Interactions

P-GLYCOPROTEIN SUBSTRATES

Table 131.4 Inhibitors of P-glycoprotein.  

*Historical. Table 131.3 P-glycoprotein substrates.  

Fig. 131.2 P-glycoprotein. This is an ATP-dependent plasma membrane glycoprotein that functions as a drug transporter and hence affects both drug absorption and elimination.  

P-GLYCOPROTEIN

Courtesy, Ian Worpole.

suggested that the reason newer antihistamines do not cause sedation is that PGP activity acts as a barrier to CNS penetration. This would suggest that PGP inhibitors (see Table 131.4) could interact with and allow increased cerebral concentrations of these antihistamines, with an attendant increase in sedation33. Evidence also suggests that intestinal PGP plays a significant role in the first-pass elimination of cyclosporine, probably by being a ratelimiting step in absorption. Intestinal CYP3A4 is thought to play a lesser role34. However, the overlap of tissue distribution and substrate specificity of CYP3A4 and PGP in the intestinal wall makes it difficult to define the precise mechanisms of some drug interactions and to predict the plasma concentrations of certain drug combinations. Moreover, the involvement of CYP3A4 and PGP in drug interactions is not always complementary.

DISTRIBUTION

Because PGP blocks absorption in the gut, these glycoproteins should be considered part of the “first-pass effect”. In fact, PGP can “set up” or act as “gatekeepers” for later cytochrome P450 actions. Although the inhibition and induction of intestinal CYP3A enzymes from metabolic processes result in direct changes in drug absorption, the inhibition and induction of PGP primarily affects the rate of drug absorption32. If one drug is a substrate of both PGP and CYP3A4 (which are found in close proximity in the intestinal wall), and a second drug is added that is an inhibitor of both PGP and CYP3A4 (e.g. erythromycin, ketoconazole), then a greater amount of the first drug will be absorbed. Because CYP3A4 is inhibited, higher levels of unmetabolized drug will enter the blood. The effect of PGP blockade is to “open the gates” so that the later actions of CYP3A4 inhibition will be increased. PGP is an important component of the blood–brain barrier and an active PGP will prevent drugs from entering the brain. It has been

Drugs that are highly protein bound (>90%) may cause interactions based on alterations in distribution. When one drug displaces another from plasma protein-binding sites, the free serum concentration of the displaced drug is increased and its pharmacologic effect increases. However, the unbound fraction of the drug is not only more available to sites of action but is also more readily eliminated. Any enhanced pharmacologic effect occurs only transiently because of a compensatory increase in elimination, and the effect of displacement interactions is then negligible. Therefore, interactions involving drug displacement from binding proteins tend to be self-limiting35. Typically, the pharmacologic activity of the displaced drug is increased for a few days. This is followed by a return of the pharmacologic response back to the previous unbound serum concentration, even if the concomitant therapy is continued. Therefore, it is safe to say that if a patient does not manifest an adverse event from the combination therapy in the first week or so of administration, an adverse event probably will not occur. In practice, protein-binding displacement interactions do not produce clinically important changes in drug response unless the drug also has a limited distribution in the body, is slowly eliminated, or has a low therapeutic index29. For this reason, protein-binding displacement interactions may assume greater importance when the displacing drug also reduces the elimination of the substrate drug. Good examples of this principle are the interactions between NSAIDs and methotrexate (Table 131.5).

2299

SECTION

Medical Therapy

19

DRUG INTERACTIONS THAT INCREASE RISK OF SUBSTRATE DRUG TOXICITY

Mechanism

Substrate

Interactive drugs

Time course

Competitive inhibition of CYP3A4*

Cyclosporine Everolimus Sirolimus Tacrolimus Dapsone H1 antihistamines Macrolides Erythromycin HMG-CoA reductase inhibitors Lovastatin Simvastatin Metoprolol Phenytoin Pimozide Quinidine Triazolam Warfarin

Antidepressants Fluoxetine Nefazodone Azole antifungals Itraconazole Ketoconazole^ Posaconazole Voriconazole Fluconazole (high doses) Grapefruit juice HIV-1 protease inhibitors Indinavir Ritonavir Macrolides Clarithromycin Erythromycin Quinine Diltiazem Cimetidine

Rapid

Reduced metabolic clearance

Azathioprine

Allopurinol Febuxostat Salicylates

Rapid

Methotrexate

Variable

Displacement from plasma proteins

Methotrexate

NSAIDs Salicylates Sulfonamides

Rapid

Reduced renal elimination

Methotrexate

NSAIDs Penicillins Probenecid Salicylates Sulfonamides

Rapid

Synergy

Methotrexate

Retinoids Sulfonamides Tetracyclines Alcohol Monoamine oxidase inhibitors

Variable

Retinoids Acitretin Serotonin reuptake inhibitors

Variable Variable

*^Also A5 and A7.

Has been withdrawn by the European Medicines Agency and per the US FDA, it is no longer indicated for Candida or dermatophyte infections or as first-line therapy for chromomycosis or dimorphic fungal infections.

Table 131.5 Drug interactions that increase risk of substrate drug toxicity2,3. Sulfonamides are inhibitors of anionic tubular secretion of methotrexate. NSAIDs, nonsteroidal anti-inflammatory drugs.  

Medications that are most susceptible to interactions based on changes in drug distribution involving displacement from binding proteins include warfarin, sulfonamides and phenytoin13.

DRUG BIOTRANSFORMATION Cytochrome P450 Enzymes

2300

After their administration, drugs are metabolized through a series of reactions to enhance their hydrophilicity and to facilitate excretion. These drug biotransformation reactions are broadly grouped into two phases, I and II. Phase I reactions involve intramolecular changes such as oxidation, reduction and hydrolysis that make the drug more polar and therefore more readily eliminated. Phase II reactions are conjugation reactions in which an endogenous substance combines with the functional group derived from phase I reactions to produce a highly polar drug conjugate that can be even more readily eliminated. These reactions involve glucuronidation and sulfation. The cytochrome P450 (CYP) enzymes are the major drug-metabolizing enzymes (Fig. 131.3). They are present in the endoplasmic reticulum of many cells but their highest concentrations are found in hepatocytes36. CYP enzymes are also present in the crypt cells of the GI tract, with the highest concentrations found in the enterocytes at the tips of the villi; their presence accounts for the first-pass metabolism of many

drugs. These heme-containing proteins are encoded by a gene superfamily, with the encoded isoforms exhibiting distinct but overlapping substrate specificities and isoform-specific regulatory and pharmacogenetic properties37. The nomenclature employs a three-tier classification consisting of the family (40% homology in amino acid sequence), the subfamily (~75% homology), and the individual protein (e.g. CYP2D6). An increased understanding of CYP drug metabolism has solved much of the mystery behind drug interactions. While there are approximately 60 genes that encode CYP isoforms, over 90% of drug oxidation can be attributed to six main cytochromes: CYP1A2, 2C9, 2C19, 2D6, 2E1 and 3A438. The metabolism of a drug by a specific isoenzyme indicates that it is a substrate for that enzyme. Whether enzyme inhibition or induction occurs is an entirely separate issue. Many drugs serve only as substrates and produce no significant enzyme inhibition or induction. It is entirely possible for a drug to be a substrate for one enzyme and inhibit or induce another enzyme that is not involved with its own metabolism. Therefore, drug interactions are more aptly termed drug–protein–drug (food) interactions. These are affected by: genetics (polymorphic genes cause particular enzymes to be less effective, 2D6 being an example); drugs (a drug may inhibit or induce a cytochrome, or interfere in the chemical pathway of another drug, e.g. itraconazole reduces cyclosporine metabolism by inhibiting CYP3A4); chemicals (dioxin is an inducer of CYP3A4 while a food such as grapefruit juice is an inhibitor of CYP3A4); and the environment (cigarette smoke is

Fig. 131.3 Cytochrome P450 enzyme superfamily.  

1

2

3

4

5

7

11

17 19 21

3A 1B

1A

2A 2B 2C 2D 2E 2F

4B 4B1

2E1 2F1 1A1

21A 4A

1B1

26

4F

11A

27

A1

B1

131 Drug Interactions

CYTOCHROME P450 ENZYME SUPERFAMILY

CHAPTER

B2

11B

11A1

4A9 4A11

1A2

11B1 11B2

2A6 2A7

3A3 3A4 3A5 3A5P 3A7

2B6 2B7P

2D6

2C8

2C18 2C19

2C9

2D7P 2D8P

4F2 4F3

21A1P

21A2

Cytochromes of particular importance in dermatology

an inducer of CYP1A2). Deciding what is clinically relevant is a challenging, relatively new field of investigation. Drug metabolism is investigated even before human exposure. With recombinant human CYP enzymes, it is possible to determine the metabolic pathways, potential genetic polymorphisms, ability to induce or inhibit drug metabolism, and possible drug interactions. Although there are limitations to the information gleaned from in vitro studies, nonetheless this information can be used to guide more expensive in vivo studies. However, using in vitro tests that focus on cytochrome enzymes alone to predict clinical interactions may not always be reliable for a variety of reasons. First, it is not always possible to know the therapeutic concentration of a new drug and its primary metabolites in specific tissues30. Second, there are a large number of pathways and interactions, and it is impossible to test them all even in an in vitro system. Third, the demonstration of an in vitro effect does not tell physicians whether that effect is likely to occur in clinical practice, i.e. the clinical significance of an in vitro interaction is unknown. Fourth, the underlying disease state may contribute to the development of a drug interaction and this would be unaccounted for by in vitro studies alone. Until clinical data demonstrate the presence or absence of a clinically significant interaction, dosage adjustments are premature39.

THE CONFUSING WORLD OF DRUG INTERACTIONS Why does it take so long to learn about interactions? Some drugs come to market and their various interactions are not realized for several years. One reason is that drugs are prescribed on the basis of indications that may have their own adverse effects on patient outcome. Also, studies in healthy volunteers are not sufficient to determine the contribution of underlying diseases to the development of interactions. The latter are affected by genetics, drugs, chemicals, the underlying health status of the patient, the therapeutic index