Radiology Illustrated: Hepatobiliary and Pancreatic Radiology [Softcover reprint of the original 1st ed. 2014] 9783662523506, 3662523507

Table of contents :
Part 1. Liver.- Anomalies and Anatomic Variants of the Liver.- Diffuse Liver Disease.- Benign Tumors of the Liver.- Hepatocellular Carcinoma.- Other Malignant Tumors of the Liver.- Focal Hepatic Infections.- Hemodynamic and Perfusion Related Disorders.- Liver Transplantation.- Therapeutic Response Evaluation of HCC.- Trauma and Post-treatment Complications of the Liver.- Part 2. Biliary tract.- Anomalies and Anatomic Variants of the Biliary tract.- Cholangitis.- Cholecystitis.- Cholangiocarcinoma.- Tumors of the Gallbladder.- Trauma and Post-treatment Complications of the Biliary tract.- Part 3. Pancreas.- Anomalies and Anatomic Variants of the Pancreas.- Pancreatitis.- Cystic Tumors of the Pancreas.- Solid Tumors of the Pancreas.- Trauma and Post-treatment Complications of the Pancreas.- Part 4. Spleen.- Anomalies and Anatomic Variants of the spleen.- Diffuse Spleen Disease.- Benign Focal Lesions of the Spleen.- Malignant Focal Lesions of the Spleen.- Trauma and Post-treatment Complications of the spleen.

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Byung Ihn Choi Editor

Radiology Illustrated Hepatobiliary and Pancreatic Radiology

123

Byung Ihn Choi Editor

Radiology Illustrated: Hepatobiliary and Pancreatic Radiology

Editor Byung Ihn Choi Department of Radiology Seoul National University Hospital Seoul Republic of Korea

ISSN 2196-114X eISSN 2196-1158 ISBN 978-3-642-35824-1 ISBN 978-3-642-35825-8 DOI 10.1007/978-3-642-35825-8 Springer Heidelberg New York Dordrecht London

(eBook)

Library of Congress Control Number: 2013956429 © Springer-Verlag Berlin Heidelberg 2014 This work is subject to copyright. All rights are reserved by the Publisher, whether the whole or part of the material is concerned, specifically the rights of translation, reprinting, reuse of illustrations, recitation, broadcasting, reproduction on microfilms or in any other physical way, and transmission or information storage and retrieval, electronic adaptation, computer software, or by similar or dissimilar methodology now known or hereafter developed. Exempted from this legal reservation are brief excerpts in connection with reviews or scholarly analysis or material supplied specifically for the purpose of being entered and executed on a computer system, for exclusive use by the purchaser of the work. Duplication of this publication or parts thereof is permitted only under the provisions of the Copyright Law of the Publisher's location, in its current version, and permission for use must always be obtained from Springer. Permissions for use may be obtained through RightsLink at the Copyright Clearance Center. Violations are liable to prosecution under the respective Copyright Law. The use of general descriptive names, registered names, trademarks, service marks, etc. in this publication does not imply, even in the absence of a specific statement, that such names are exempt from the relevant protective laws and regulations and therefore free for general use. While the advice and information in this book are believed to be true and accurate at the date of publication, neither the authors nor the editors nor the publisher can accept any legal responsibility for any errors or omissions that may be made. The publisher makes no warranty, express or implied, with respect to the material contained herein. Printed on acid-free paper Springer is part of Springer Science+Business Media (www.springer.com)

Contents

Part I

Liver

1

Anomalies and Anatomic Variants of the Liver . . . . . . . . . . . . . . . . . . . . . . . . . . Ijin Joo and Ah Young Kim

3

2

Diffuse Liver Disease . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Jeong Hee Yoon and Jeong Min Lee

21

3

Benign Liver Tumors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Hassan Al Zahrani and Tae Kyoung Kim

75

4

Hepatocellular Carcinoma . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111 Jeong Min Lee and Byung Ihn Choi

5

Other Malignant Tumors of the Liver . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 169 Joon-Il Choi and Byung Ihn Choi

6

Focal Hepatic Infections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 233 Yoon Jin Lee and Young Hoon Kim

7

Hemodynamic and Perfusion-Related Disorders . . . . . . . . . . . . . . . . . . . . . . . . . 263 Su-Yuan Paul Chou and Hyun-Jung Jang

8

Liver Transplantation Imaging. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 303 Kyoung Won Kim

9

Therapeutic Response Evaluation of HCC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 335 Min Woo Lee

10

Trauma and Postoperative Changes of the Liver . . . . . . . . . . . . . . . . . . . . . . . . . 365 Eun Sun Lee and Cheong-Il Shin

Part II

Biliary Tract

11

Anomalies and Anatomic Variants of the Biliary Tract . . . . . . . . . . . . . . . . . . . . 393 Mi Hye Yu and Jung Hoon Kim

12

Cholangitis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 419 Hee Sun Park

13

Cholecystitis and Adenomyomatosis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 447 Jae Young Lee

14

Cholangiocarcinoma . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 471 Jin-Young Choi and Joon Koo Han

15

Tumors of the Gallbladder . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 501 Soo Jin Kim

xiii

xiv

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Contents

Trauma and Posttreatment Complications of the Biliary Tract . . . . . . . . . . . . . 539 Jeehyun Baek and Joon Koo Han

Part III

Pancreas

17

Anomalies and Anatomic Variants of the Pancreas . . . . . . . . . . . . . . . . . . . . . . . 567 Mi Hye Yu and Jung Hoon Kim

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Pancreatitis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 587 So Yeon Kim

19

Cystic Tumors of the Pancreas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 631 Se Hyung Kim

20

Solid Tumors in the Pancreas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 667 Suk Ki Jang and Jung Hoon Kim

21

Trauma and Post-treatment Complications of the Pancreas . . . . . . . . . . . . . . . . 703 Ji Hoon Park and Kyoung Ho Lee

Part IV

Spleen

22

Anomalies and Anatomic Variations of the Spleen. . . . . . . . . . . . . . . . . . . . . . . . 721 Ijin Joo and Ah Young Kim

23

Diffuse Spleen Diseases . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 739 Jong Seok Lee

24

Benign Focal Lesions of the Spleen . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 765 Yong Eun Chung

25

Malignant Focal Lesions of the Spleen. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 793 Jee Young Son and Hyunsik Woo

26

Trauma and Post-treatment Complications of the Spleen . . . . . . . . . . . . . . . . . . 807 Ji Hoon Park and Kyoung Ho Lee

Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 819

1

Anomalies and Anatomic Variants of the Liver Ijin Joo and Ah Young Kim

Contents 1.1 Agenesis and Hypoplasia of the Hepatic Lobe or Segment . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

4

1.2 Riedel’s Lobe . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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1.3 Accessory Hepatic Lobe. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

4

1.4 Accessory Fissure and Diaphragmatic Slip . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

4

1.5 Sliver of the Liver . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

5

1.6 Papillary Process of the Caudate Lobe . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

5

1.7 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

5

1.8 Illustrations: Anomalies and Anatomic Variants of the Liver . . . . . . . . . . . . . . . . . . . . . . . . . . .

6

Suggested Reading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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I. Joo Department of Radiology, Seoul National University Hospital, Seoul, Republic of Korea e-mail: [email protected] A.Y. Kim (*) Department of Radiology, University of Ulsan, Asan Medical Center, Seoul, Republic of Korea e-mail: [email protected] B.I. Choi (ed.), Radiology Illustrated: Hepatobiliary and Pancreatic Radiology, Radiology Illustrated, DOI 10.1007/978-3-642-35825-8_1, © Springer-Verlag Berlin Heidelberg 2014

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I. Joo and A.Y. Kim

Knowledge of the anomalies and anatomical variants of the liver is often of great importance because these may be misinterpreted as pathologic conditions. While congenital anomalies of the liver are rare, anatomic variants are relatively common. The congenital anomalies of the liver include agenesis or hypoplasia of the hepatic lobes or segments, Riedel’s lobe, and other accessory hepatic lobe. Anatomic variants contain accessory fissures and diaphragmatic slips, sliver of the liver, and variants related to papillary process of the caudate lobe.

1.1

Agenesis and Hypoplasia of the Hepatic Lobe or Segment

Agenesis and hypoplasia of hepatic lobes or segments are uncommon developmental anomalies. Agenesis is a condition of complete absence of hepatic lobes or segments, whereas hypoplasia is a condition which the size of a hepatic lobe or segment is relatively small but otherwise normal. The most commonly involved segments are the anterior segment of the right lobe and the medial segment (segment IV). Before making a diagnosis of agenesis or hypoplasia, it is important to exclude other causes of acquired atrophy of the hepatic lobes or segments, caused by cirrhosis, biliary obstruction, postsurgical resection, or rarely vascular compromise. In cases of agenesis, hepatic parenchyma as well as corresponding lobar or segmental vessels is absent, whereas at least one of those structures is detected in cases of acquired atrophy. Agenesis or hypoplasia of the hepatic lobes and segments may alter the normal topography of the upper abdomen, that is, change in position of adjacent organs such as the stomach, colon, or kidney.

1.2

Riedel’s Lobe

Riedel’s lobe is a downward, tongue-like projection from the anterior aspect of the right hepatic lobe. It is controversial whether Riedel’s lobe is congenital or acquired in origin. Awareness of Riedel’s lobe is clinically important since it is one of the causes of right-sided abdominal palpable masses on physical examination. However, correct diagnosis can be easily achieved by demonstrating of its connection with right hepatic lobe on imaging modalities. Riedel’s lobe is usually asymptomatic. However, it can give rise to symptoms such as acute or intermittent abdominal pain if it is complicated by torsion.

1.3

Accessory Hepatic Lobe

Accessory hepatic lobe is a rare congenital anomaly and occurs from an error in the formation of the endodermal caudal foregut in the third gestational week and segmentation of the hepatic bud. It is composed of normal hepatic tissue and contains its own hepatic vessels and bile ducts. Most cases of accessory lobes are attached to the inferior surface of the liver by either a normal hepatic parenchyma or a mesentery. Occasionally, they have been found around gallbladder fossa, gastrohepatic ligament, umbilicus, adrenal gland, pancreas, esophagus, and rarely the thoracic cavity. Accessory hepatic lobes can mimic soft tissue masses or lymph nodes, but they can be differentiated from other pathologic condition by means of identification of their continuity with main liver on imaging modalities using multiplanar reconstruction. Although most accessory lobes are usually asymptomatic and found incidentally, some pedunculated ones may undergo torsion of their vascular pedicles.

1.4

Accessory Fissure and Diaphragmatic Slip

In addition to the major hepatic fissures such as fissures for falciform ligament and ligamentum venosum, the liver may contain accessory and pseudoaccessory fissures. True accessory fissures result from inward folding of the peritoneum; therefore, ascites may extend into these fissures or peritoneal pathology can be appeared. Accessory fissures are rare but relatively common in the undersurface of the liver. The most common one is the inferior accessory fissure, which is located in the surface of posterior segment of the right lobe. Invagination of the diaphragmatic muscle fibers results in pseudoaccessory fissures, usually along the superior surface of the liver. They are common anatomic variants and more frequently seen in the right hepatic lobe. These diaphragmatic slips can mimic hepatic nodules. Differentiation of hepatic accessory or pseudoaccessory fissures from pathologic lesions may be achieved by a careful analysis of contours of the liver and diaphragm and by knowing the various findings of these variants. On CT scan, they can appear as hypoattenuated nodules in the peripheral portion of the liver. On ultrasound, they may be seen as echogenic nodular lesions in one plane. However, when scanning in the orthogonal plane, echogenic linear morphology may be revealed along the hepatic dome.

1

Anomalies and Anatomic Variants of the Liver

1.5

Sliver of the Liver

Leftward extension of the left lateral segment of the liver is referred to as “sliver of the liver.” It is a common anatomic variant and appears as a crescent density which wraps around the spleen in the left upper quadrant abdomen. Knowledge of imaging features of this variant is important to not to confuse this portion of the liver for a pathologic condition originating from the stomach or spleen. This potential misdiagnosis can be avoided by demonstration of continuity between the “sliver of the liver” and the remainder of the left hepatic lobe.

1.6

Papillary Process of the Caudate Lobe

The caudate lobe is a medial extension of the right hepatic lobe between inferior vena cava and the fissure for ligamentum venosum. Occasionally, it is divided inferiorly into two processes: papillary and caudate processes. The papillary process extends medially and to the left in the region of the lesser sac, while the caudate process extends posteriorly. Papillary process of the caudate lobe can appear separate from the liver on some sections of the axial images; therefore, it can mimic an enlarged periportal lymph node or a soft

5

tissue mass near the pancreas head. Serial axial images as well as multiplanar reformatted images are occasionally helpful for differentiating the papillary process form extrahepatic lesions.

1.7

Summary

1. Knowledge of the imaging features of anomalies and anatomic variants of the liver is important not to misinterpret these as pathologic conditions. Multiplanar reformatted images would be occasionally helpful to make correct diagnosis. 2. Riedel’s lobe is one of the possible causes of abdominal palpable mass, and it can undergo torsion. 3. Accessory fissure of the liver is most commonly found in the surface of posterior segment of the right lobe. 4. Diaphragmatic slips are common pseudoaccessory fissures in the hepatic dome which result from invagination of the diaphragm. 5. Leftward extension of the left lateral segment of the liver (sliver of the liver) is a common anatomic variant which may mimic perisplenic mass. 6. Papillary process of the caudate lobe can mimic an enlarged lymph node or a soft tissue mass on axial images.

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I. Joo and A.Y. Kim

1.8

Illustrations: Anomalies and Anatomic Variants of the Liver

1.8.1

Illustrations of Normal Segmental Anatomy of the Liver

a

b LL

LM

LM LL RA

RA

C RP RP

Fig. 1.1 Illustrations of normal segmental anatomy of the liver on cross-sectional images. (a, b) Segmental anatomy of the liver is usually determined by the portal vein branches and hepatic veins. Congenital anomalies such as agenesis and hypoplasia of hepatic lobes or segments

alter the normal morphology which can be appeared as absence and relatively small size of lobes or segments. RP right posterior segment, RA right anterior segment, LM left medial segment, LL left lateral segment, C caudate lobe

1

Anomalies and Anatomic Variants of the Liver

1.8.2

7

Agenesis of the Right Lobe of the Liver

a

b

*

Fig. 1.2 Agenesis of the right lobe of the liver. (a) Axial CT image at the level of left portal vein shows bifurcation of the segmental portal branches from the umbilical portion (arrowhead) of the left portal vein. Note the absence of the right hepatic lobe and hypertrophy of the

caudate lobe (asterisk). (b) CT image which is more caudal to (a) demonstrates the origination of the left portal vein (arrowhead); however, there is no vascular structure corresponding to right portal vein. Note the accessory fissure (arrow) in the left lateral segment

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I. Joo and A.Y. Kim

1.8.3

Agenesis of the Left Lateral Segment of the Liver

a

b

*

c

Fig. 1.3 Agenesis of the left lateral segment of the liver. (a) Axial contrast-enhanced CT reveals absence of left portal vein while right portal vein is present (arrow). (b) On the more cranial image, the left

lateral segment is absent while the medial segment is supplied by middle hepatic artery (arrow) and caudate lobe (asterisk) is present. (c) Topogram shows transverse and high-positioned stomach (arrows)

1

Anomalies and Anatomic Variants of the Liver

1.8.4

9

Hypoplasia of the Left Lateral Segment of the Liver a

b

Fig. 1.4 Hypoplasia of the left lateral segment of the liver. (a) Axial CT image shows the hypoplastic liver tissue of left lateral segment (arrow) which mimics an enhancing soft tissue mass or lymphadenopathy of the perigastric space. Notice the presence of left portal vein

c

(arrowhead). (b) More superior image and (c) coronal reformatted image show the small size of left lateral segment. (b) Notice the left hepatic vein (arrowhead)

10

1.8.5

I. Joo and A.Y. Kim

Hypoplasia of the Left Medial Segment of the Liver

a

b

* *

Fig. 1.5 Hypoplasia of the left medial segment of the liver. (a) CT shows the small medial segment (arrowhead) lying between the fissure for falciform ligament (arrow) and gallbladder (black asterisk). (a, b)

*

CT and topogram demonstrate that hepatic flexure colon (white asterisk) and omental fat fill the gap created by hypoplasia of the medial segment of the liver

1

Anomalies and Anatomic Variants of the Liver

1.8.6

11

Riedel’s Lobe: Ultrasound Findings

a

Fig. 1.6 Riedel’s lobe: ultrasound findings. (a) Ultrasound image which is scanned in an oblique coronal plane shows soft tissue (arrows) anterior to the right kidney. (b) Ultrasound image on a different plane in

b

the same individual reveals elongation of the right lobe (Riedel’s lobe) (arrow) which shows same echogenic texture with the other part of the liver

12

1.8.7 a

I. Joo and A.Y. Kim

Riedel’s Lobe: CT Findings b

Fig. 1.7 Riedel’s lobe: CT findings. (a, b) Axial CT images in a 28-year-old female show the inferior extension of the liver parenchyma (arrows) from the anterior portion of the right lobe which is located anteriorly to the right kidney and along the right paracolic

c

gutter. (c) Coronal reformatted CT image demonstrates the tongue-like downward elongation of the hepatic parenchyma (arrow), which is consistent with Riedel’s lobe

1

Anomalies and Anatomic Variants of the Liver

1.8.8

13

Accessory Lobe of the Liver with Mass

a

b

* Fig. 1.8 Accessory lobe of the liver with mass. (a) Arterial and (b) portal phase CT images of a 78-year-old female show hepatocellular carcinoma (asterisks) in the accessory hepatic lobe (arrows) which is

* attached to the left lateral superior segment (segment II). Portovenous shunt is detected in the segment II (arrowhead)

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1.8.9

I. Joo and A.Y. Kim

Diaphragmatic Slips: CT Findings

a

Fig. 1.9 Diaphragmatic slips: CT findings. (a) Axial and (b) coronal CT images in a 60-year-old female demonstrate the diaphragmatic invaginations (arrow and arrowheads) in the superior aspect of the liver

b

which result in pseudoaccessory fissures, “diaphragmatic slips.” Diaphragmatic slips can be seen as nodular density (arrow) in some sections of CT images; therefore, it may mimic hepatic nodule

1

Anomalies and Anatomic Variants of the Liver

1.8.10 Diaphragmatic Slips: Radiography and Ultrasound Findings a

b

Fig. 1.10 Diaphragmatic slips: radiography and ultrasound findings. (a) Diaphragmatic invagination in the liver causes lobulated soft tissue densities (arrowheads) along the right diaphragm on the chest radiography. These findings can be mistaken for soft tissue masses in the lung or pleura. (b) Ultrasound image in the same patient shows lobulation of the liver surface as well as echogenic lines (arrows) which are consistent with diaphragmatic slips

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I. Joo and A.Y. Kim

1.8.11 Accessory Fissure of the Liver a

b

Fig. 1.11 Accessory fissure of the liver. (a) Axial and (b) coronal CT images in a 37-year-old female show incidentally detected accessory fissure (arrows) of the liver which is located in the inferior surface of the right hepatic lobe

1

Anomalies and Anatomic Variants of the Liver

17

1.8.12 Accessory Fissure of the Liver with Loculated Fluid Collection a

Fig. 1.12 Accessory fissure of the liver with loculated fluid collection. (a) Preoperative CT image revealed slit-like accessory fissure (arrow) in the right hepatic lobe. (b) CT scan after pylorus-preserving pancre-

b

aticoduodenectomy in the same patient shows loculated ascites (arrow) in the accessory fissure of the liver

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I. Joo and A.Y. Kim

1.8.13 Sliver of the Liver a

b

* * * * c

* *

Fig. 1.13 Sliver of the liver. (a) Axial and (b) coronal CT images show the leftward extension of the left lobe of the liver (white asterisks) wrapping the spleen (black asterisks), which is a common anatomic variation, “sliver of the liver.” (c) Ultrasound image in a coronal plane

shows the sliver of the liver (white asterisk) around the spleen (black asterisk) which may be mistaken for a perisplenic pathologic condition

1

Anomalies and Anatomic Variants of the Liver

19

1.8.14 Papillary Process of the Caudate Lobe a

Fig. 1.14 Papillary process of the caudate lobe. (a) Axial CT scan at the level of main portal vein shows protruded papillary process of the caudate lobe (arrow) which mimics a periportal lymph node or an

b

exophytic pancreatic mass. (b) Coronal reformatted CT image reveals the inferior and medial extension of the papillary process of the caudate lobe (arrow)

20

Suggested Reading Auh YH, Rosen A, Rubenstein WA, et al. CT of the papillary process of the caudate lobe of the liver. AJR Am J Roentgenol. 1984; 142(3):535–8. Auh YH, Rubenstein WA, Zirinsky K, et al. Accessory fissures of the liver: CT and sonographic appearance. AJR Am J Roentgenol. 1984; 143(3):565–72. Auh YH, Lim JH, Kim KW, et al. Loculated fluid collections in hepatic fissures and recesses: CT appearance and potential pitfalls. Radiographics. 1994;14(3):529–40.

I. Joo and A.Y. Kim Dachman AH. Anomalies and anatomic variants of the spleen. In: Gore RM, Levine MS, editors. Textbook of gastrointestinal radiology. 3rd ed. Philadelphia: Saunders; 2008. Gallego C, Velasco M, Marcuello P, et al. Congenital and acquired anomalies of the portal venous system. Radiographics. 2002; 22(1):141–59. Kudo M. Riedel’s lobe of the liver and its clinical implication. Intern Med. 2000;39(2):87–8. Kostov DV, Kobakov GL. Accessory hepatic lobe. Surg Radiol Anat. 2011;33(9):819–22. Watson JR, Lee RE. Accessory lobe of the liver with Infarction. Arch Surg. 1964;88:490–3.

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Diffuse Liver Disease Jeong Hee Yoon and Jeong Min Lee

Contents 2.1 Radiologic Modalities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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2.2 Radiologic Findings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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2.3 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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2.4 Illustrations: Diffuse Liver Disease . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

28

Suggested Reading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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J.H. Yoon • J.M. Lee (*) Department of Radiology, Seoul National University Hospital, Seoul, Republic of South Korea e-mail: [email protected]; [email protected], [email protected] B.I. Choi (ed.), Radiology Illustrated: Hepatobiliary and Pancreatic Radiology, Radiology Illustrated, DOI 10.1007/978-3-642-35825-8_2, © Springer-Verlag Berlin Heidelberg 2014

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J.H. Yoon and J.M. Lee

Table 2.1 Diffuse liver disease depends on radiologic finding Attenuation change Low attenuation Fatty liver, steatohepatitis High attenuation Amiodarone, hemosiderosis, hemochromatosis, GSD, chronic arsenic poisoning, gold therapy, Wilson’s disease, shock liver Heterogeneous Uneven fatty liver, radiation hepatitis, sinusoidal attenuation obstruction syndrome Morphologic change Enlarged Acute hepatitis, alcoholic hepatitis, hematologic disease (lymphoma, leukemia), metabolic disease (Wilson’s disease, GSD) Shrunk Chronic hepatitis, liver cirrhosis, end stage of metabolic disease (Wilson’s disease, GSD) Contour deformity Liver cirrhosis, pseudocirrhosis by tumor, PVT change Multifocal hepatic lesions Hypervascular Multinodular HCC, diffuse hypervascular metastasis, focal nodular hyperplasia/nodular regenerating hyperplasia, peliosis, AP shunt Hypovascular Multiple regenerative nodules/dysplastic nodules, diffuse hypovascular metastasis, multiple myeloma, lymphoma, leukemia, sarcoidosis, candidiasis, eosinophilic abscess, extramedullary hematopoiesis (rare) Hypovascular, Biliary hamartoma, ADPKD, cystic metastasis cystic Other Multiple fat deposition Note: GSD glycogen storage disease, PVT portal vein thrombosis, HCC hepatocellular carcinoma, AP shunt arterioportal shunt, ADPKD autosomal dominant polycystic kidney disease

Since diffuse liver disease usually represents alternation of its metabolic pathway, cross sectional imaging studies may play a limited role in evaluating diffuse liver disease whereas they are crucial for detection and characterization of focal liver lesions. However, owing to imaging technology advances and use of tissue-specific contrast agents ultrasound (US), computed tomography (CT), and magnetic resonance (MR) imaging have been more frequently used for diagnosis of diffuse liver disease, determining the causes of the diffuse liver disease, assessing extent of the disease, and monitoring its progression. In this chapter, diffuse liver diseases are categorized into three categories based on their radiologic findings: (a) liver parenchymal attenuation changes, (b) morphological changes of the liver contour or size, and (c) multifocal or disseminated liver lesions (Table 2.1).

2.1

tive diagnostic tool for obese patients due to poor sonic window. On US, operators usually compare the echogenicity of the liver with that of right kidney to detect the presence of fatty liver. Increased echogenicity on US, however, is seen in not only fatty liver but also other types of diffuse liver diseases. CT is commonly used for evaluation of both focal and diffuse liver diseases. Non-contrast CT scan is useful for diagnosing fatty liver and hemochromatosis by comparing liver attenuation with splenic attenuation. On contrast-enhanced CT scans, the size and contour of the liver are easily assessed. With respect to diffuse liver diseases manifested as multifocal liver lesions, CT is a powerful tool for detection, characterization, and monitoring of those focal liver lesions. CT also has an advantage of surrounding organ evaluation. Owing to recent advances of CT techniques, high-resolution images can be achieved within a short time with lower radiation dose than before. MR imaging has also been used for evaluating various hepatic diseases since breath-hold imaging acquisition sequences and hepatocyte-specific contrast agents were developed. MR plays an important role for focal liver lesion evaluation, but recently it draws a lot of attention as an effective tool for evaluation of diffuse liver disease by virtue of its chemical shift imaging (CSI), MR spectroscopy, diffusion weighted imaging (DWI) and MR elastography (MRE). In addition, T2-weighted image (WI) and T2*-WI are useful for evaluation of hemochromatosis. The advent of hepatocyte-specific contrast agent (Gd-EOB-DTPA) helps in the evaluation of liver disease by providing hepatobiliary phase imaging. Recently, there have been attempts to predict liver function using Gd-EOB-DPTA enhanced MRI as well. Elastography is a tissue stiffness imaging, based on US or MR by measuring speed of sound across the tissue after vibrating a tissue. Instead of palpation for superficial organs, US based elastography (USE) such as transient elastography (TE), shear-wave elastography (SWE), acoustic radiation force impulse (ARFI) imaging, and MR elastography (MRE) are used for liver stiffness measurement. In MRE, mechanical waves are transmitted into the liver, and tissue stiffness is calculated by analyzing the propagation of shear waves using a motion-sensitive MR pulse sequence. In SWE, shear wave generated by push pulses from US probe is captured and tissue stiffness is calculated by measuring shear wave velocity. Liver stiffness values increase in advanced fibrosis. Since fibrosis itself is not clearly depicted on conventional imaging, elastography draws a lot of attention for fibrosis evaluation in the liver.

Radiologic Modalities

US is the first diagnostic modality of choice for diffuse liver disease. This is routinely performed in patients with predisposing factor of hepatocellular carcinomas (HCCs) for surveillance. It is also performed in patients with liver function test abnormality to exclude the possible biliary obstruction. US is easy to perform and safe to patients with contrast media hypersensitivity or nephropathy. Furthermore, it can avoid radiation hazard. However, US is dependent on operators as well as not an effec-

2.2

Radiologic Findings

2.2.1

Attenuation/Signal Intensity Changes of the Liver Parenchyma

2.2.1.1 Fatty Liver Fatty liver disease comprises a spectrum of conditions including simple hepatic steatosis and steatohepatitis of

2

Diffuse Liver Disease

various causes such as toxic, ischemic, and metabolic liver injuries. Among them, nonalcoholic fatty liver disease (NAFLD) is one of the most commonly encountered diffuse liver diseases in clinical field since rapid increase of obesity. The prevalence of NAFLD varies from 2.8 to 46 %, depending on sex, race, age, and underlying disease. Liver cirrhosis and accompanying HCCs may develop in late stage, although those are relatively less common in NAFLD than viral or alcohol-induced hepatitis. On US, normal liver parenchyma shows similar echogenicity with renal parenchymal echogenicity. Fatty liver shows higher echogenicity than the normal liver parenchyma. As fatty infiltration progresses, the interface between portal vein and liver parenchyma is obscured, and the diaphragm interface disappears. Although the liver parenchymal echogenicity tends to increase with fat accumulation, this is subjective and can be found in fibrosis and other diffuse liver diseases. CT is also helpful for diagnosing fatty liver; fatty liver shows decreased attenuation than spleen whereas normal liver parenchymal shows slightly higher attenuation (50–75 HU) than that of spleen. In severe fatty liver, intrahepatic vessels are brighter than liver parenchyma on non-contrast CT. Fat quantification using CT scan and liver attenuation index (difference of HU between liver and spleen on precontrast phase) showed higher accuracy to detect moderate to severe hepatic steatosis. On MR, CSI is effective for detecting small amount of fatty infiltration in the liver by providing in-phase and opposed-phase images. Normal liver shows higher signal intensity on both in- and opposed- phase images than that of spleen. There is no significant difference in hepatic parenchymal signal intensity on in- and opposed-phase images in normal liver, whereas fatty liver shows significant signal drop on opposed-phase image than on in-phase image. Besides of qualitative evaluation by comparing in- and opposed-phases, currently computational fat fraction map using a multi-echo gradient echo sequence with spectral modeling is available in many scanners. On fat fraction map, the fat amount can be measured quantitatively. MR spectroscopy is also useful for fat quantification in the liver, and it is known to provide the most accurate fat quantification result. The disadvantage of MR spectroscopy is that it samples only small portion of the liver whereas CSI can show the whole liver fat quantification.

2.2.1.2 NASH (Nonalcoholic Steatohepatitis) Up to 25 % of the NAFLD patients have been reported to develop nonalcoholic steatohepatitis (NASH). Differentiating NASH from simple hepatic steatosis is clinically important because NASH is reported to progress to cirrhosis in 18–39 % in 3.5–8.2 years. The diagnosis of NASH has been made by liver biopsy which is invasive and unsuitable for treatment monitoring. Instead of liver biopsy, other noninvasive diagnostic methods are performed. For hepatic fat quantification, previously mentioned CSI and MR spectroscopy are used. Elastography including TE, SWE, and MRE can be used to investigate combined hepatic fibrosis.

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2.2.1.3 Alcoholic Liver Disease Alcoholic liver disease is a spectrum which consists of three disease entities: fatty liver, alcoholic hepatitis, and cirrhosis. Alcoholic hepatitis and cirrhosis are progressive disease, whereas alcohol-induced fatty liver is reversible by abstinence. The liver may be enlarged early in the disease process, but it becomes atrophic as cirrhosis progresses. Since hepatitis or cirrhosis is superimposed on the alcohol-induced fatty liver, the liver shows increased echogenicity on US and decreased attenuation on non-contrast CT. On MR, the liver is also presented as fatty liver: signal drops on opposedphase image. In late stage of alcoholic liver disease, the liver shows contour deformity as well because of liver cirrhosis. In alcoholic liver cirrhosis, confluent fibrosis is known to be common than viral liver disease. 2.2.1.4 Chemotherapy-Associated Steatohepatitis (CASH) and Steatosis Since liver is the main metabolic pathway of various agents, clinical or subclinical hepatotoxicity is common during chemotherapy. Chemotherapy-associated steatohepatitis (CASH) and steatosis are common problems encountered during chemotherapy by various anticancer drugs: methotrexate, corticosteroids, L-asparaginase, tamoxifen, irinotecan, 5-fluorouracil (5-FU), etc. Among them, 5-FU and irinotecan provide high chance of steatohepatitis. US, CT, and MR findings are consistent with those of simple hepatic steatosis. In patients with liver metastasis, the liver parenchyma around the metastatic lesion can be saved from fat infiltration, probably due to reduced portal inflow in that area. Patients’ history of chemotherapy and underlying malignant diseases will be important information for differential diagnosis. 2.2.1.5 Amiodarone Amiodarone is an antiarrhythmic agent and its hepatotoxicity has been documented: it varies from asymptomatic mild elevation of serum transaminase levels to fatty liver or pseudoalcoholic cirrhosis. The cumulative dose of amiodarone is more important for predicting toxicity rather than daily dose. Amiodarone shows very distinctive features on CT because of its iodine contents. On non-contrast CT, the liver shows significantly high attenuation than normal liver parenchyma or adjacent organ such as spleen, which simulates hemochromatosis. 2.2.1.6 Hemosiderosis and Hemochromatosis Hemosiderosis is an increased iron deposition without parenchymal organ damage. Hemosiderosis is usually seen with body iron stores between 10 and 20 g, whereas normal iron in body is usually 2–6 g. With normal iron stores, iron is primarily in the reticuloendothelial cells of the bone marrow, liver, and spleen which have traceable amount. When iron deposition increases in the body, it is deposited in the liver,

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spleen, lymph nodes, pancreas, kidneys, heart, endocrine glands, and gastrointestinal tract. Hemochromatosis is an iron-overload disorder in which there is structural and functional impairment of the involved organs. Iron overload can be classified as two categories: primary and secondary. Primary hemochromatosis is an autosomal recessive genetic disorder characterized by abnormally increased iron absorption by the mucosa of the duodenum and jejunum. Consequently, plasma iron level increases and it is deposited in visceral organs including liver. Secondary hemochromatosis is nongenetic and it develops in the following conditions: exogenous increase by ingestion or multiple transfusions and chronic medical disease (liver disease, oncologic disease, myelodysplastic syndrome). The liver is the first organ to be damaged in hemochromatosis because liver contains up to 1/3 of the total body store of iron. Hepatomegaly is present in 95 % of symptomatic cases. Splenomegaly is present in nearly 50 % of cases. Primary and secondary hemochromatosis involve visceral organs in different ways. Primary hemochromatosis involves parenchymal cells in the liver, pancreas, heart, pituitary gland, thyroid, and synovium. Spleen is preserved. On the other hand, in secondary hemochromatosis, iron is accumulated in the liver and spleen which contain reticuloendothelial cells, and pancreas is saved. However, in far advanced stage of secondary hemochromatosis, excessive iron can be deposited in the pancreas. Organ damage and malignancy frequently occur in primary hemochromatosis whereas secondary hemochromatosis is less toxic. CT is the noninvasive diagnostic method of excess hepatic iron deposition. On CT scans, the liver demonstrates homogenously increased attenuation (75–135 HU), whereas the normal attenuation of the liver is 45–65 HU on non-contrast CT with 120 kVp. However, HU on CT scan can be changed by combined underlying disease, especially fatty infiltration, since fat reduces attenuation on precontrast phase. Since steatosis with hemochromatosis is not infrequent, it causes problem for diagnosis of hemochromatosis. Recently it is reported that dual-energy CT can differentiate hepatic iron from hepatic fat, but it is still on investigation. MR is the most sensitive imaging modality in the diagnosis of iron deposit. On MR, signal intensity dramatically reduces in the liver on T2-WI or T2*-WI, due to the large paramagnetic susceptibility of iron. In primary hemochromatosis, liver and pancreas show significant signal drop on T2-WI or T2*-WI, whereas in secondary hemochromatosis liver and spleen show signal drop on T2-WI or T2*-WI. On CSI, hemosiderosis or hemochromatosis shows opposite signal intensity with hepatic steatosis: hemosiderosis or hemochromatosis shows darker signal intensity on in-phase and higher signal intensity on opposed-phase images, whereas steatosis shows higher signal intensity on in-phase and signal drop on opposed-phase images.

J.H. Yoon and J.M. Lee

2.2.1.7 Glycogen Storage Disease Glycogen storage disease (GSD) is a heterogeneous group of disorders characterized by abnormal glycogen metabolism caused by different enzyme deficiency. The most common inherited disorder is type I GSD, in which glucose-6phosphatase in the liver and kidneys is insufficient and it causes excessive glycogen deposition in the hepatocytes and proximal renal tubules. Pathologically intracytoplasmic accumulations of glycogen and small amount of lipid are found. Hepatomegaly and nephromegaly are seen on imaging. On US, various degree of fatty liver is seen. On CT scan, density of the liver is increased due to glycogen storage. However, at the same time, fat accumulation lowers the hepatic parenchymal attenuation. Therefore, the final hepatic parenchymal attenuation depends on the degree of fat and glycogen accumulation ratio. In GSD, CT and MR may have a role for the evaluation of adenoma and HCC surveillance rather than GSD diagnosis: hepatic adenoma and HCC can occur in patients with GSD, and especially the presence of multiple hepatic adenomas (adenomatosis) suggests the possibility of GSD. 2.2.1.8 Hepatic Sinusoidal Injury Hepatic sinusoidal injury or sinusoidal obstruction syndrome (SOS) is a term in which small venules in the liver are obstructed and histologically presented as sinusoidal dilatation and congestion. It was first described as an insult by alkaloids, but after wide use of anticancer drugs, it usually accompanies with high-dose chemotherapy. Sinusoidal injury has a strong correlation with oxaliplatin use. Besides oxaliplatin, azathioprine, actinomycin D, dacarbazine, mithramycin, and 6-thioguanine are associated with hepatic sinusoidal injury. Clinical feature varies: no symptom or liver function test abnormality, weight gain, hepatomegaly, and ascites in advanced stage. Especially patients with hepatitis, steatohepatitis and systemic infection are at risk of SOS. On Doppler examination, portal flow is diminished or reversed, and engorged portal vein and portal vein thrombosis are seen. Resistive index of hepatic artery increases. Hepatic vein involvement is not essential to SOS because the main injury occurs at the level of hepatic sinusoids. On CT, it can be manifested as heterogeneous liver parenchymal enhancement. On hepatobiliary phase image of hepatocyte-specific contrast-enhanced MR, liver shows hypointense reticular or lace-like parenchymal enhancement which accompanies with coalescent hypointense lesions. Peliosis hepatis, nodular regenerative hyperplasia, and sinusoidal dilatation can be coincident. 2.2.1.9 Radiation Hepatitis Hepatic radiation is most often unintentional and occurs when the liver is unavoidably included in the treatment port for primary malignancies. Radiation hepatitis is a veno-occlusive

2

Diffuse Liver Disease

process as SOS, and mean hepatic dose which exceeds 37 Gy is prone to radiation hepatitis since tolerance radiation dose of the liver is 30–35 Gy. Radiation hepatitis occurs within 2–6 months after radiation therapy. On US, the regions of radiation injury are hypoechoic relative to the remainder of the liver. This is probably a result of localized hepatic congestion or edema. CT scans performed within several months of the radiation therapy show a sharply defined band of low attenuation along the treatment port, so-called straight border sign. The straight border sign is due to edema by sinusoidal obstruction and presinusoidal edema or fatty infiltration of the involved area. On the other hand, in patients with fatty infiltration of the liver, the irradiated area may show increased attenuation than the remaining liver. This may be attributed to loss of fat in the irradiated hepatocytes or regional edema. The initially sharp borders of the irradiated zone become more irregular and indistinct as peripheral areas of parenchyma regenerate. Eventually, the irradiated area may become atrophic. Radiation hepatitis on MR manifests as geographic areas of low signal intensity on T1-WI and high signal intensity on T2-WI secondary to increased water content as determined by proton spectroscopic imaging. Besides those MR findings, diffusion restriction images (DWI) is helpful to distinguish post-radiation change from tumor recurrence.

2.2.2

Size and Contour Changes of the Liver

2.2.2.1 Hepatitis Hepatitis is a general term for describing acute or chronic inflammation of the liver caused by various hepatic injuries including viral, fungal, bacterial, and exogenous toxic agents. It is reversible but sometimes progresses to chronic course. In acute hepatitis, the imaging findings are nonspecific. The main purpose of the imaging is to exclude other underlying diseases such as biliary obstruction, focal liver lesions, or chronic liver disease. On US, normal findings are more frequent than abnormal findings. In severe acute hepatitis, the liver and spleen are frequently enlarged. The parenchymal echogenicity may decrease than renal echogenicity, and portal venule wall can be prominent due to parenchymal edema. Gallbladder frequently shows wall edema. CT findings are also nonspecific: hepatomegaly, gallbladder wall edema, and periportal edema which are probably due to lymphedema are common finding. Lymph node enlargement in portal hilum and ascites may be seen. On contrast-enhanced CT scan, the liver parenchyma may show heterogeneous enhancement. In early stage of chronic hepatitis, morphologic change is not obvious and even US shows normal range of liver echogenicity, before fibrosis progresses. In advanced chronic hepatitis, however, liver shows increased and coarse parenchymal echogenicity and loss of mural definition of the

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portal veins on US due to inflammatory cell deposition and fibrotic tissue accumulation surrounding the lobules. In patients with chronic active hepatitis, lymph node enlargement is found in the porta hepatis, gastrohepatic ligament, and retroperitoneum. MR is reported to show homogeneously or heterogeneously increased signal intensity on T2-WI which suggests inflammation in the liver parenchyma. However, the main purpose of CT and MR is to monitor the disease progression to liver cirrhosis and to detect HCC. In advanced chronic liver disease, US plays a key role for evaluation of liver echogenicity which may help earliest detection of liver cirrhosis change, although the liver echogenicity on US is subjective and operator dependent. Therefore, elastography including TE, SWE, and MRE is performed, and TE and MRE have been widely validated. SWE and MRE have an advantage of providing elastogram than TE, which shows 1D value, in aspect of elasticity imaging.

2.2.2.2 Liver Cirrhosis Liver cirrhosis is the terminal stage of the chronic liver disease, which is characterized by advanced fibrosis and multiple regenerative or dysplastic nodules. Morphologic changes of the liver in cirrhosis are as follows: liver surface nodularity, enlarged left lateral segment and S1, atrophy of the right lobe and S4, prominence of the fissures, gallbladder fossa, and porta hepatis. Those atrophy/hypertrophy changes of the liver size are explained by hepatic perfusion change: blood flow to right portal vein is from superior mesenteric vein which contains metabolites and toxins, and blood flow to left portal vein is from spleen which contains insulin and glucagon. Regardless of causes, because of the overall volume decrease, the fissures, gallbladder fossa, and hilar space are widening. On US, decreased liver volume, surface nodularity, prominent fissures and gallbladder fossa, and coarse echogenicity are observed. Furthermore, multiple hyper- or hypoechoic small nodules, ascites, and splenomegaly are suggestive of liver cirrhosis. Surface nodularity is caused by regenerating nodules, and it is more clearly depicted in left lateral segment on CT and MR. CT is not sensitive to detect regenerative or dysplastic nodules than other two examinations. Hepatic circulation changes in chronic liver disease. Intrahepatic vascular resistance increases and portal perfusion decreases. Additionally, hepatic sinusoids are obliterated due to deposition of collagen in the extravascular Disse’s spaces. Consequently portal hypertension appears and portal vein dilatation is shown. Main portal vein diameter exceeds 13 mm; it is very specific for portal hypertension. But in advanced stage, the main portal vein shrinks due to decreased and hepatofugal portal flow. Left gastric, esophageal, paraesophageal, gastrorenal, splenorenal, paraumbilical, mesenteric, and hemorrhoidal veins are common portosystemic collaterals. Esophageal and gastric varices are

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carefully observed because they can cause massive hematemesis. Portal hypertension usually leads to splenomegaly, ascites, bowel wall edema (portal hypertensive colonopathy), and increased density in mesentery, lymph node enlargement. Portal hypertension also occurs after chronic portal vein thrombosis. Because of decreased portal flow, peripheral liver parenchyma is atrophied whereas central portion of the liver is relatively saved and compensatorily hypertrophied. At the same time, cavernous transformation is induced. The morphological change by chronic portal vein thrombosis without liver cirrhosis may be confused with liver cirrhosis, but it can be differentiated from liver cirrhosis in several aspects: no presence of surface nodularity, no left lateral segment hypertrophy, and no S4 atrophy. Confluent fibrosis is broad fibrosis of thick, mass-like appearance up to several centimeters. In 30 % of cirrhosis, confluent fibrosis is depicted on CT and MR and sometimes it mimics a neoplasm. Confluent fibrosis shows low attenuation on precontrast CT scan and iso- to hypoattenuation on contrast-enhanced CT scan and capsular retraction may be seen. Common spots are right anterior segment and left lateral segment. On MR, it shows low signal intensity on T1-WI and subtle high signal intensity on T2-WI. Unlike tumors, confluent fibrosis is usually geographic or wedge-shaped and radiates from the portal hilum to liver surface. On dynamic images, it shows persistent or delayed enhancement pattern which is a differential point from HCC. One thing to remind is that confluent fibrosis shows hypointensity on delayed phase. But its enhancement pattern is clearly different from HCC which shows arterial enhancement and portal washout and can distinguish it from HCC.

2.2.2.3 Wilson’s Disease Wilson’s disease is a rare, autosomal recessive inherited disorder of copper metabolism. It is a result of impaired biliary or urinary excretion of copper, excessive absorption of copper from the gastrointestinal tract, and deficient production of ceruloplasmin. The copper accumulates in the multiple organs including liver, basal ganglia, and cornea. Imaging findings are nonspecific in Wilson’s disease since the spectrum of hepatic injury by copper accumulation varies: fatty infiltration, acute hepatitis, chronic active hepatitis, cirrhosis, or massive liver necrosis. Hepatomegaly is the most common feature. In addition, fatty infiltration, chronic hepatitis and liver cirrhosis can be seen on US and CT, but these are indistinguishable from other causes. Copper deposition can increase liver attenuation on CT and may change liver signal intensity on MR by shortening T2-relaxation time, but it is not well demonstrated in vivo. Imaging is not useful for diagnosing Wilson’s disease or estimating copper amount but more useful for liver injury monitoring and surveillance for liver cirrhosis.

J.H. Yoon and J.M. Lee

2.2.2.4 Amyloidosis Amyloids are proteolysis-resistant fibrils derived from monoclonal immunoglobulin light chains. In amyloidosis, amyloid accumulates in organs and replaces the normal tissue. Liver is the third commonly involved organ in abdomen that follows spleen and kidneys. Amyloids accumulate in Disse’s space. CT findings of amyloidosis are nonspecific. Hepatomegaly is the most common finding which can be seen in 75 % of cases. On CT, the regions in which amyloids accumulate may show variable-sized low attenuation. Delayed contrast enhancement may be seen in the involved areas because of vascular and sinusoidal infiltration. Concomitant abnormalities seen in the spleen are helpful in differentiating amyloid deposition from neoplasm and fatty infiltration. On MR, T2 signal intensities of the spleen and adrenal glands are significantly decreased, and the T2 signal intensity of the pancreas significantly increased, whereas minimal T2 signal change is seen in the liver.

2.2.3

Multifocal Hepatic Lesions

Diffuse liver disease can also be manifested as multifocal hepatic lesions including infectious, hemato-oncologic diseases as well as benign lesions.

2.2.3.1 Liver Cirrhosis-Related Nodules Since liver cirrhosis is characterized by fibrosis as well as hepatocellular nodules, multiple cirrhosis-related nodules are observed on US, CT, and MR: MR is the most sensitive tool for their detection and characterization. Those nodules are classified as regenerative nodules (benign), dysplastic (premalignant) and neoplastic nodules (malignant). In advanced stage of liver cirrhosis, those nodules sometimes manifest as multiple focal lesions and may obscure detection of HCC. Regenerative nodules are formed in response to exogenous stimuli, and they are not pathognomonic to liver cirrhosis. Regenerative nodules are less than 5 cm in most cases. A giant regenerative nodule (5 cm15 mm) between the pancreaticobiliary ductal union and ampulla of

b

Vater (b) C-P type: the perpendicular insertion of the common bile duct into the pancreatic duct. There is a long common channel (>15 mm) between the pancreaticobiliary ductal union and ampulla of Vater

11

Anomalies and Anatomic Variants of the Biliary Tract

11.7.15 APBDU, P-C Type

Fig. 11.15 APBDU, P-C type in a 64-year-old woman. MRCP reveals the long common channel (arrow) between the pancreatic duct and the common bile duct. Note the perpendicular insertion of the pancreatic duct into the common bile duct with an acute angle. The choledochal cyst (asterisk) of the common bile duct is associated

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11.7.16 APBDU, C-P Type a

Fig. 11.16 APBDU, C-P type with choledochal cyst in a 34-year-old woman. (a) MRCP shows the perpendicular insertion of the common bile duct into the pancreatic duct with long common channel (arrow). There is the fusiform dilatation (asterisk) of the common bile duct and

b

intrahepatic duct which suggests the type IVa choledochal cyst. (b) The surgical specimen shows the choledochal cyst (asterisk) of the common bile duct

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Anomalies and Anatomic Variants of the Biliary Tract

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11.7.17 APBDU with Gallbladder Cancer a

Fig. 11.17 APBDU with gallbladder cancer in a 55-year-old woman. (a) ERCP shows the long common channel (arrow) between the pancreatic duct and common bile duct. (b) Diffuse irregular wall thickening

b

with enhancement (arrowheads) of the gallbladder is shown on the coronal contrast-enhanced CT image, which is confirmed as gallbladder cancer

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11.7.18 APBDU with Choledochal Cyst, Gallbladder Cancer a

b

c

Fig. 11.18 APBDU, P-C type with choledochal cyst and gallbladder cancer in a 45-year-old woman. (a) Axial contrast-enhanced CT image shows the enhancing polypoid mass (arrow) in the gallbladder fundus with mild dimpling. (b) MRCP demonstrates the long common channel

(arrowhead) between the pancreatic duct and common bile duct with dilated common bile duct (asterisk). (c) The surgical specimen reveals the polypoid gallbladder cancer (arrow) with choledochal cyst of the common bile duct (asterisk)

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Anomalies and Anatomic Variants of the Biliary Tract

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11.7.19 Phrygian Cap of Gallbladder a

b

c

Fig. 11.19 Phrygian cap of the gallbladder in a 37-year-old man. (a, b) Both axial and coronal contrast-enhanced CT images show the folded gallbladder fundus (arrow), referred as Phrygian cap. (c) Axial

T2-weighted MR image also shows the folded gallbladder fundus with partial septum

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11.7.20 Bicameral Gallbladder a

b

c

Fig. 11.20 Bicameral gallbladder in a 52-year-old woman. (a, b) There are two separated chambers (asterisks) of the gallbladder on ultrasound. Small stones (arrow) are seen in the distal fundal chamber

of the gallbladder. (c) Axial contrast-enhanced CT image also shows the two chambers (asterisks) of the gallbladder with small gallbladder stones (arrow) in the distal chamber

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Anomalies and Anatomic Variants of the Biliary Tract

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11.7.21 Left-Sided Gallbladder a

c

Fig. 11.21 Left-sided gallbladder in a 54-year-old man. (a–c) The gallbladder (asterisk) is located at the inferior aspect of segment III and fissure for ligamentum teres (arrow), not at the gallbladder fossa on

b

d

contrast-enhanced CT images. (d) The segment IV of the liver is absent and the portal vein of the segment 8 (arrowhead) originates from left portal vein

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Suggested Reading Catalano OA, Sahani DV, Kalva SP, et al. MR imaging of the gallbladder: a pictorial essay. Radiographics. 2008;28(1):135–55. Chowbey PK, Wadhwa A, Sharma A, et al. Ectopic gallbladder: laparoscopic cholecystectomy. Surg Laparosc Endosc Percutan Tech. 2004;14(1):26–8. De Filippo M, Calabrese M, Quinto S, et al. Congenital anomalies and variations of the bile and pancreatic ducts: magnetic resonance cholangiopancreatography findings, epidemiology and clinical significance. La Radiologia Medica. 2008;113(6):841–59. Gore RM, et al. Anomalies and anatomic variants of the gallbladder and biliary tract. In: Gore RM, Levine MS, editors. Textbook of gastrointestinal radiology. 3rd ed. Philadelphia: Saunders; 2008. Hashimoto M, Itoh K, Takeda K, et al. Evaluation of biliary abnormalities with 64-channel multidetector CT. Radiographics. 2008;28(1): 119–34. Lamah M, Karanijia ND, Dickson GH. Anatomical variations of the extrahepatic biliary tree: review of the world literature. Clin Anat. 2001;14(3):167–72.

M.H. Yu and J.H. Kim Mortele KJ, Ros PR. Cystic focal liver lesions in the adult: differential CT and MR imaging features. Radiographics. 2001;21(4): 895–910. Mortelé KJ, Rocha TC, Streeter JL, et al. Multimodality imaging of pancreatic and biliary congenital anomalies1. Radiographics. 2006;26(3):715–31. Rizzo RJ, Szucs RA, Turner MA. Congenital abnormalities of the pancreas and biliary tree in adults. Radiographics. 1995;15(1): 49–68; quiz 147–148. Santiago I, Loureiro R, Curvo-Semedo L, et al. Congenital cystic lesions of the biliary tree. AJR Am J Roentgenol. 2012;198(4): 825–35. Taourel P, Bret PM, Reinhold C, et al. Anatomic variants of the biliary tree: diagnosis with MR cholangiopancreatography. Radiology. 1996;199(2):521–7. Yeh BM, Liu PS, Soto JA, et al. MR imaging and CT of the biliary tract. Radiographics. 2009;29(6):1669–88. Yu J, Turner MA, Fulcher AS, et al. Congenital anomalies and normal variants of the pancreaticobiliary tract and the pancreas in adults: part 1, biliary tract. AJR Am J Roentgenol. 2006;187(6): 1536–43.

Cholangitis

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Hee Sun Park

Contents 12.1 Primary Sclerosing Cholangitis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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12.2 Primary Biliary Cirrhosis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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12.3 Recurrent Pyogenic Cholangitis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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12.4 Obstructive Cholangitis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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12.5 Parasitic Infestation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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12.6 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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12.7 Illustrations: Cholangitis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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Suggested Reading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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H.S. Park Department of Radiology, Konkuk University Medical Center, Konkuk University School of Medicine, Seoul, Republic of South Korea e-mail: [email protected] B.I. Choi (ed.), Radiology Illustrated: Hepatobiliary and Pancreatic Radiology, Radiology Illustrated, DOI 10.1007/978-3-642-35825-8_12, © Springer-Verlag Berlin Heidelberg 2014

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12.1

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Primary Sclerosing Cholangitis

Primary sclerosing cholangitis (PSC) is a chronic cholestatic liver disease of unknown cause characterized by inflammation, fibrosis, and destruction of intrahepatic and extrahepatic bile ducts. It affects male patients more commonly than female patients. PSC is commonly associated with inflammatory bowel disease, particularly ulcerative colitis in more than half of the cases. PSC presents as jaundice in the fourth or fifth decades, and liver function tests reveal cholestasis with elevation of serum alkaline phosphatase. PSC usually goes through progressively downhill course and may be complicated by biliary cirrhosis and cholangiocarcinoma. PSC is characterized by fibrosing inflammation of the biliary tree, usually both intrahepatic and extrahepatic ducts. Histologic stage of PSC ranges from cholangitis and portal hepatitis to cirrhosis. On direct cholangiography, multiple segmental strictures involving both the intrahepatic and the extrahepatic bile ducts are the characteristic finding of PSC, and alternating strictures and dilatations result in the “beaded” appearance. Ductal dilatation is usually mild and proportionately less than the degree of stricture, because periductal inflammation and fibrosis impair ductal dilatation. As fibrosis progresses, obliteration of peripheral intrahepatic ducts may give the biliary tree a “pruned tree” appearance, and this usually indicates the development of cirrhosis. Sometimes small diverticular outpouchings of bile duct may be seen. Bile duct walls often show irregularity from a fine to coarse, shaggy, or nodular appearance. CT findings of PSC are similar to cholangiography findings and include segmental intrahepatic and extrahepatic bile duct dilatations with multifocal strictures. Ductal wall enhancement and periductal patchy enhancement can be seen. Intrahepatic duct stones are rarely seen. MRCP (magnetic resonance cholangiopancreatography) findings of PSC are similar to direct cholangiography findings and include multifocal segmental strictures alternating with mild bile duct dilatation. Ductal wall irregularities, diverticula, and stones can be seen. On MRI, hepatic parenchymal changes may accompany. T2-weighted images may reveal increased signal intensity in a peripheral wedge-shaped or fine reticular pattern, which is thought to be caused by extension of periductal inflammation to involve vascular and lymphatic channels. The most important differential diagnosis of PSC is cholangiocarcinoma. Hilar cholangiocarcinoma involving both intrahepatic and extrahepatic ducts has a similar cholangiographic appearance to PSC. Also, the ductal change from the underlying PSC can mask the presence of coexisting cholangiocarcinoma. Since cholangiocarcinoma causes more complete obstruction than fibrous strictures of PSC,

more marked biliary dilatation may suggest a diagnosis of cholangiocarcinoma. Secondary biliary cirrhosis that may be confused with PSC includes choledocholithiasis, ischemic bile duct injury, postoperative biliary stricture, and congenital biliary abnormalities. Ischemic bile duct injury is most common after liver transplantation and is sometimes occurred after transcatheter arterial chemoembolization for hepatocellular carcinoma. Biliary surgery may complicate mechanical stricture. Other radiologic mimics of PSC include AIDS cholangiopathy, primary biliary cirrhosis, recurrent pyogenic cholangitis, and autoimmune pancreatitis-related biliary stricture.

12.2

Primary Biliary Cirrhosis

Primary biliary cirrhosis (PBC) is a chronic cholestatic disease affecting small-to-medium intrahepatic ducts. It is thought to be autoimmune origin, which is characterized by inflammation and destruction of interlobular and septal bile duct leading to chronic cholestasis, cirrhosis, and hepatic failure. Majority of patients are female and age of onset is late fourth to sixth decade. The most common symptoms are slowly progressive pruritus due to cutaneous accumulation of bile salts. The clinical manifestations of cirrhosis and portal hypertension in PBC are similar to other causes of chronic liver disease, and hepatocellular carcinoma can occur. Serologic markers, especially antimitochondrial antibody, are frequently positive in PBC. Serum alkaline phosphatase levels are markedly elevated. On pathology, small duct destruction is accompanied by inflammatory cellular infiltrate and granuloma formation. For definitive diagnosis of PBC, antimitochondrial antibody positivity, elevated alkaline phosphatase, and characteristic histologic findings are required. CT and ultrasound usually reveal normal liver or hepatomegaly in the initial presentation. As disease progresses, the liver volume decreases with atrophy of right hepatic lobe and hypertrophy of caudate and left hepatic lobes. Fibrosis shows reticular pattern, and sometimes regenerating nodules intercalated by fibrous reticulations can be seen. Porta hepatis and portocaval lymphadenopathy are frequently observed. “Periportal halo sign” on MRI is known to be a specific finding for the diagnosis of end-stage PBC. It is seen as diffuse small rounded low signal intensity lesions on T1- and T2-weighted images, surrounding portal vein branches, without mass effect. Histologically the periportal halo sign corresponds to periportal hepatocellular parenchymal extinction encircled by regenerating nodules. Cholangiograms are usually normal in PBC but diffuse attenuation of bile ducts can be seen, and bile duct deformities are less severe than those of PSC and mainly confined to the intrahepatic ducts.

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12.3

Recurrent Pyogenic Cholangitis

Recurrent pyogenic cholangitis (RPC) is characterized by intrahepatic ductal pigmented stones commonly accompanied by recurrent gram-negative bacterial infections. RPC is also known as oriental cholangiohepatitis because this disease has a propensity to occur in the Asian populations. The cause of RPC is unclear, but associations with parasitic infestation such as clonorchiasis and ascariasis, portal bacteremia, and malnutrition have been suggested. The pattern of stone disease in RPC is different from conventional stone disease, which manifests as extrahepatic location and predominantly cholesterol stones originated from gallbladder. Right upper quadrant pain, fever, chills, and jaundice are the common clinical features, and natural history is characterized by wax and wane of cholangitis. Recurrent episodes of bile duct injury and cholestasis ultimately lead to biliary cirrhosis. RPC increases the risk of cholangiocarcinoma, with reported incidence rate of 5–6 %. Chronic bile duct irritations by intrahepatic calculi, bile stasis, and bacterial infections have been proposed as responsible carcinogenic factors. Cross-sectional imaging usually demonstrates dilated ducts containing stones and sludge. Lateral segment of left hepatic lobe and posterior segment of right hepatic lobe are more commonly involved than other hepatic segments. Parenchymal atrophy of involved hepatic segment, ductal wall enhancement and thickening, biliary strictures, hepatic abscess and biloma, segmental hepatic parenchymal enhancement, and pneumobilia are the findings of RPC. As the disease progresses to cirrhosis, atrophy of left lateral and right posterior hepatic segment along with hypertrophy of caudate lobe and left medial segment result in round liver configuration. Cholangiography findings of RPC include intrahepatic or extrahepatic duct stones as filling defect, dilatation of extrahepatic duct and central intrahepatic duct, ductal rigidity and straightening, increased or right-angle branching pattern, decrease in arborization, acute tapering of peripheral duct, luminal irregularity, and focal strictures. MRCP findings of RPC are similar to those of direct cholangiography, but advantageous to the case of missing duct by severe stricture. When cholangiocarcinoma occurs in patients with hepatolithiasis, periductal soft tissue density, higher ductal enhancement than normal duct on portal venous phase, ductal wall thickening, portal vein obliteration, and lymph node enlargement on CT images are significant findings for differentiating cancer from periductal fibrosis.

12.4

Obstructive Cholangitis

Complete or partial bile duct obstruction leads to bile stasis and predisposes to ascending cholangitis by bacterial infection. Patients present with right upper quadrant pain, fever,

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chills, and jaundice. Benign causes of biliary obstruction are choledocholithiasis, postoperative biliary stricture, or papillary stenosis and malignant cases are cholangiocarcinoma, pancreatic carcinoma, or malignant hilar lymphadenopathy. The role of imaging is to detect biliary dilatation and determine the cause and level of obstruction. On cross-sectional imaging of contrast enhancement, ductal wall thickening and enhancement, upstream duct dilatation, patchy periductal enhancement, as well as obstructive lesion per se are the findings of obstructive cholangiohepatitis. Hepatic abscess often complicate bacterial cholangitis.

12.4.1 Choledocholithiasis Choledocholitiasis is due to stones either primarily formed within the bile ducts or secondarily migrated from gallstones. Primary choledocholithiasis is usually secondary to underlying biliary tree abnormality such as biliary stricture or choledochal cyst. Most stones are cholesterol stones in the developed countries, while brown pigmented stones are formed in chronically infected bile ducts and lead to recurrent pyogenic cholangitis. Cholangiography is highly sensitive for detecting bile duct stones, which typically appear as smooth filling defects. CT has about 80 % sensitivity for biliary stones. Pure cholesterol stones are isodense to bile and thus radiolucent, which are not detectable by CT. On MRCP, stones appear as signal void within high signal intensity bile. MRI is highly sensitive and specific for the diagnosis of choledocholithiasis. Mirizzi syndrome, due to a stone impacted in the cystic duct or gallbladder neck exerting pressure on the common hepatic duct, usually presents as jaundice and cholangitis. Repeated attacks of inflammation may lead to stricture or pressure necrosis leading to cholecystocholedochal fistula formation.

12.5

Parasitic Infestation

12.5.1 Clonorchiasis Clonorchiasis is a trematodiasis caused by chronic infestation of liver flukes, Clonorchis sinensis. The eggs of C. sinensis are passed in human feces, and infestation occurs by ingestion of raw fish. The worms cause the obstruction of the bile flow within the biliary tree and trigger inflammatory cell infiltration. As disease progresses, periductal fibrosis, ductal epithelial hyperplasia, and cholangiocarcinoma can develop. On cholangiography, C. sinensis appears as ellipsoid filling defect measuring several millimeters in length in the intrahepatic duct. CT and ultrasound reveal diffuse and mild dilatation of intrahepatic ducts, particularly in the periphery of liver

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and without extrahepatic duct dilatation. Mild, uniform, and disproportionate dilatation of biliary tree from extrahepatic duct to the far peripheral ducts is typical finding of clonorchiasis. Clonorchiasis increases the risk of cholangiocarcinoma, and carcinoma in this setting tends to occur peripherally where the flukes are most concentrated. Clonorchiasis also can accompany biliary calculus, cholangiohepatitis, and hepatic abscess. Differential diagnosis of intrahepatic duct dilatation without extrahepatic duct dilatation includes intrahepatic calculi, RPC, sclerosing cholangitis, choledochal cyst, and intrahepatic metastasis. Intrahepatic calculi are seen as high density on noncontrast CT and accompany proportionate biliary tree dilatation. In RPC, ductal dilatation is usually irregular and shows segmental distribution due to strictures, paucity of peripheral intrahepatic duct (pruned tree appearance). In sclerosing cholangitis, bile ducts have a beaded and discontinuous appearance.

12.5.2 Ascariasis Ascaris lumbricoides is the most prevalent human helminth worldwide. The disease is transmitted by the ingestion of food contaminated with parasitic eggs, which eventually develop into adult worms within the gastrointestinal tract. The adult worms may remain within the intestines and occasionally enter the biliary system through the ampulla of Vater. Biliary colic and cholangitis may develop when worms obstruct the common duct. In severe cases, pyelophlebitis or hepatic abscesses may occur. Worms are seen as elongated longitudinal filling defects on cholangiography or thin

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tubular echogenic intramural lesions on ultrasound scans. MRCP shows intraductal worms as filling defect of linear low signal intensity.

12.6

Summary

1. Characteristic finding of primary sclerosing cholangitis is multiple intrahepatic and extrahepatic duct strictures intercalated with normal or dilated ductal segments, producing beaded appearance. 2. “Pruned tree” appearance of biliary tree on primary sclerosing cholangitis or recurrent pyogenic cholangitis is due to nonopacification of peripheral bile duct. 3. “Peripheral halo sign” in primary biliary cirrhosis indicates numerous small rounded lesions of low T1 and T2 signal intensity surrounding portal vein branches and suggesting end-stage disease. 4. Intrahepatic muddy calculi dominant in left lateral and right posterior hepatic segment, pruned tree appearance of biliary tree, and biliary cirrhosis feature are seen in recurrent pyogenic cholangitis. 5. Obstructive cholangitis is most commonly caused by choledocholithiasis. Proportionate bile duct dilatation, enhanced thickening of bile duct wall, and enhancement of periductal hepatic parenchyma are the characteristic radiologic findings. 6. In Clonorchiasis, CT and ultrasound reveal diffuse, minimal, or mild dilatation of intrahepatic ducts, particularly in the periphery of liver and without extrahepatic duct dilatation.

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12.7

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Illustrations: Cholangitis

12.7.1 Schematic Diagram of Morphologic Classification of Bile Duct Dilatation a

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Fig. 12.1 Schematic diagram of morphologic classification of bile duct dilatation. (a) In distal obstruction with malignancy or benign stricture, dilatation of whole upstream biliary tree shows proportionate nature, in which large ducts are more dilated than small ducts are. (b) In recurrent pyogenic cholangitis, dilatation of extrahepatic duct and central intrahepatic duct, ductal rigidity and straightening, increased or right-angle branching pattern, decrease in arborization, and acute tapering of peripheral duct are seen. Obliteration of peripheral intrahepatic

ducts shows pruned tree appearance. (c) In clonorchiasis, uniform, disproportionate dilatation of biliary tree from the central duct to the far peripheral ducts without extrahepatic duct dilatation. (d) In primary sclerosing cholangitis, multiple segmental strictures involving both the intrahepatic and the extrahepatic bile ducts are seen, with alternating strictures and dilatations produce the “beaded” appearance. Obliteration of peripheral intrahepatic ducts shows pruned tree appearance

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12.7.2 Primary Sclerosing Cholangitis a

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Fig. 12.2 Primary sclerosing cholangitis in a 42-year-old man. (a) Ultrasound shows mild intrahepatic duct dilatation. (b) Axial image of portal phase CT shows mild enhanced wall thickening of common hepatic duct (arrow) and proximal intrahepatic duct (arrowhead). (c). Coronal image of portal phase CT shows diffuse enhanced wall thickening of common duct (arrows). (d) Cholangiography obtained

from endoscopic retrograde cholangiography (ERC) shows multifocal strictures and dilatations of intrahepatic ducts (arrows) and multifocal narrowings of common bile duct (arrowheads).(e) Magnetic resonance cholangiopancreatography (MRCP) shows multiple strictures of intrahepatic ducts (arrows) and common hepatic duct (arrowhead)

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12.7.3 Primary Sclerosing Cholangitis a

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Fig. 12.3 Primary sclerosing cholangitis in a 45-year-old man. (a). Fat-suppressed T2-weighted MR image shows multifocal patchy high signal intensity areas of hepatic parenchyma (arrows). (b) Arterial phase dynamic MR image shows multifocal periductal patchy

enhancement (arrows) suggesting cholangiohepatitis. (c) MRCP shows multifocal strictures of intrahepatic ducts with minimal upstream ductal dilatation (arrows). Note the paucity of biliary trees suggestive of pruned tree appearance

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12.7.4 Primary Sclerosing Cholangitis a

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Fig. 12.4 Primary sclerosing cholangitis in a 52-year-old man. (a) Portal phase CT shows enhanced wall thickening with mild dilatation of intrahepatic ducts (arrows). (b) Fat-suppressed T2-weighted MR

shows periductal high signal intensities with mild dilatation of intrahepatic ducts (arrows). (c) MRCP shows multifocal strictures with dilatation of intrahepatic ducts with beaded appearance (arrowheads)

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12.7.5 Primary Biliary Cirrhosis a

Fig. 12.5 Primary biliary cirrhosis in a 62-year-old woman. (a). Fatsuppressed T1-weighted image shows numerous hepatic nodules intercalated by low signal intensity lacelike fibrosis. (b) Fat-suppressed

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T2-weighted image shows regenerated nodules as low signal intensity and intercalating fibrosis as high signal intensity (By the courtesy of Prof. Jin Young Choi, Yonsei University College of Medicine)

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12.7.6 Hepatolithiasis a

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Fig. 12.6 Hepatolithiasis in a 57-year-old man. (a) Ultrasound image shows elongated echogenic material (white arrows) having posterior acoustic shadowing (asterisk) in the left lateral intrahepatic duct with upstream ductal dilatation (black arrow). Air biliary gram is seen as linear strong high echogenic line (arrowheads). (b) Noncontrast CT shows high-density stone in the left lateral intrahepatic duct (white arrow) with upstream ductal dilatation (black arrow). Also note air biliary grams in the neighboring ducts (arrowheads). (c) Arterial phase CT

shows patchy periductal enhancement of hepatic parenchyma around intrahepatic duct stone (arrowheads). (d). T2-weighted MR shows intrahepatic duct stone as dark signal intensity (arrow) with upstream ductal dilatation as bright signal intensity (arrowhead). (e) MRCP shows intrahepatic duct stone as signal void (arrow) with upstream ductal dilatations (arrowheads). (f) Gross specimen of left lateral hepatic sectionectomy shows greenish intrahepatic duct stone (arrows) with upstream ductal thickening and dilatation (arrowheads)

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12.7.7 Recurrent Pyogenic Cholangitis a

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Fig. 12.7 Recurrent pyogenic cholangitis in a 66-year-old woman. (a) Contrast enhanced CT shows marked dilatation of both intrahepatic ducts (arrows). (b) More caudal scan reveals dilated common bile duct filled with air-bubble containing non-enhancing mass suggestive of muddy stone (arrow) with biliary obstruction. (c). Coronal image of CT shows muddy stone in the distal common bile duct (arrows) and dilated

both intrahepatic ducts with decreased arborization, suggestive of pruned tree appearance in recurrent pyogenic cholangitis. (d). Cholangiography obtained from ERC shows ductal stone as filling defect (asterisk) with intrahepatic duct dilatation (arrow) and missing duct of right hepatic lobe due to stricture (arrowhead). (e) Endoscopy shows muddy stone removed from distal common bile duct (asterisk)

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12.7.8 Recurrent Pyogenic Cholangitis a

Fig. 12.8 Recurrent pyogenic cholangitis in a 57-year-old woman. (a) Noncontrast CT shows high-density stones impacted in the left lateral intrahepatic duct (arrow) with segmental hepatic parenchymal atrophy. (b)

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Cholangiography obtained from ERC shows dilated left lateral intrahepatic duct with filling defect due to stones (arrow). Central intrahepatic ducts show acute tapering (arrowheads), suggestive of pruned tree appearance

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12.7.9 Recurrent Pyogenic Cholangitis

Fig. 12.9 Recurrent pyogenic cholangitis in a 68-year-old woman. (a) MRCP shows ductal rigidity and straightening, increased or right-angle branching pattern, and acute tapering of peripheral ducts (arrows), as well as focal strictures suggestive of recurrent pyogenic cholangitis

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12.7.10 Cholangiocarcinoma Having Recurrent Pyogenic Cholangitis a

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Fig. 12.10 Cholangiocarcinoma in a 71-year-old woman having recurrent pyogenic cholangitis. (a) Noncontrast CT shows stones in the intrahepatic duct (arrow). Right hepatic lobe is previously resected. (b) Portal phase CT shows infiltrative enhancing soft tissue along right hepatectomy resection margin with adjacent diaphragm invasion (arrows). Also note cirrhotic configuration of liver with hypertrophic caudate lobe (arrowhead). (c) More caudal scan reveals that the soft tissue infiltrates along inferior vena cava and suprarenal space (arrows).

(d) T2-weighted MR shows infiltrative tumor as high signal intensity (arrows). Intrahepatic duct is dilated due to recurrent pyogenic cholangitis (arrowhead). (e) MRCP shows multiple strictures (arrows) and acute tapering of intrahepatic duct (arrowhead) suggesting a feature of recurrent pyogenic cholangitis. (f) Diffusion-weighted MR with b = 400 shows the diffusion restriction of the infiltrative tumor along the resection margin (arrows). (g) FDG-PET-CT shows strong uptake of FDG by the tumor (arrow)

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Fig. 12.10 (continued)

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12.7.11 Cholangiocarcinoma Having Recurrent Pyogenic Cholangitis a

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Fig. 12.11 Cholangiocarcinoma in a 48-year-old woman having recurrent pyogenic cholangitis. (a) Left hemihepatectomy was previously done due to hepatolithiasis. Portal phase CT shows enhanced wall thickening of common hepatic duct (arrow). (b) Coronal image CT shows segmental enhanced thickening of common hepatic duct and its primary biliary confluence (arrows). (c) Cholangiography obtained from ERC shows segmental narrowing of common hepatic duct (arrows). (d) 7 months later,

portal phase CT shows increased extent of diffuse enhanced thickening of common duct (arrow) (e) Coronal images of CT show progressed narrowing of common hepatic duct (arrow) and obliteration of main portal vein (arrowhead) due to the tumor invasion. (f) MRCP shows nonvisualization of common duct due to tumor involvement (arrow). (g) Cholangiography obtained from ERC shows progressed narrowing of common hepatic duct (arrows) and proximal intrahepatic ducts (arrowheads)

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Fig. 12.11 (continued)

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12.7.12 Choledocholithiasis with Biliary Obstruction a

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Fig. 12.12 Choledocholithiasis with biliary obstruction in a 76-yearold woman. (a) Ultrasound shows echogenic lesion in the CBD (arrows) with upstream common bile duct dilatation (arrowhead). (b) Coronal image of portal phase CT shows high-density stones in the distal CBD

(arrows) with upstream bile duct dilatation (arrowhead). (c) Cholangiography obtained from ERC shows stones in the common duct as multifaceted filling defects (arrows)

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12.7.13 Choledocholithiasis with Biliary Obstruction a

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Fig. 12.13 Choledocholithiasis with biliary obstruction in a 73-year-old man. (a) Portal phase CT shows dilated common bile duct (arrowheads) without demonstrable radiopaque stone. Chronic calculous cholecystitis is accompanied (arrows). (b) More cranial scan reveals dilated proximal intrahepatic duct (arrowhead) with periductal enhancement

(arrowheads) suggestive of cholangiohepatitis. (c) MRCP shows round signal void in the mid-common bile duct (arrow) with upstream bile duct dilatation. (d) Cholangiography obtained from left percutaneous transhepatic biliary drainage tube (arrow) shows common bile duct stone as round filling defect (arrowhead) with upstream bile duct dilatation

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12.7.14 Mirizzi Syndrome a

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Fig. 12.14 Mirizzi syndrome in an 85-year-old man. (a) Portal phase CT shows diffuse intrahepatic duct dilatation (arrows). (b) More caudal scan reveals gallstone (arrow) and common bile duct dilatation (arrowhead). (c) Stone impacted in the gallbladder neck (arrow) compresses bile duct. (d) Coronal CT shows impacted radiolucent stone in the

gallbladder neck (asterisk) obstructs distal common bile duct with biliary obstruction (arrow). (e) Cholangiography obtained from ERC shows large stone impacted in the gallbladder neck as ovoid filling defect (asterisk) with biliary obstruction (arrow). Another gallstone is seen as radiopaque mass (arrowhead)

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12.7.15 Intrahepatic Mass-Forming Cholangiocarcinoma with Biliary Obstruction b

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Fig. 12.15 Intrahepatic mass-forming cholangiocarcinoma with biliary obstruction in a 75-year-old man. (a) Portal phase image of contrast-enhanced MR shows poorly enhancing mass (asterisk) in the left hepatic lobe with diffuse upstream intrahepatic duct dilatation (arrows). (b) T2-weighted MR shows high signal intensity mass in the

left hepatic lobe (asterisk) with diffuse upstream bile duct dilatation (arrows). (c) MRCP shows abrupt cutting of common hepatic duct by the tumor (arrow) with diffuse proportionate dilatation of upstream biliary tree. Arrowheads indicate undistended gallbladder and cystic duct

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12.7.16 Intrahepatic Mass-Forming Cholangiocarcinoma with Biliary Abscesses a

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Fig. 12.16 Intrahepatic mass-forming cholangiocarcinoma with biliary abscesses in a 75-year-old man (same patient as Fig. 12.14). (a) Portal phase CT shows multiple peripheral rim-enhancing cystic masses around dilated bile ducts (arrows) suggestive of biliary abscesses, which are caused by the cholangiocarcinoma in the central

portion of left hepatic lobe (asterisk). (b) Coronal images of portal phase CT show biliary abscess as irregular shape peripheral rimenhancing cystic mass in the liver (arrow), cholangiocarcinoma in the central portion of liver (asterisk), and upstream bile duct dilatation (arrowhead)

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12.7.17 Distal Common Bile Duct Cancer with Biliary Obstruction a

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Fig. 12.17 Distal common bile duct cancer with biliary obstruction in a 76-year-old woman. (a). Arterial phase image of contrast-enhanced MR shows diffuse intrahepatic duct dilatation (arrows) with patchy periductal enhancement (arrowheads) suggestive of cholangiohepatitis. (b) Coronal image of portal phase MR shows low signal intensity mass in the distal common bile duct (arrow) with marked upstream duct

dilatation (asterisk). (c) MRCP shows abrupt narrowing of distal common bile duct due to cancer (arrow) with marked upstream duct dilatation (asterisk) and proportionate dilatation of peripheral intrahepatic ducts (arrowheads). (d) Cholangiography obtained from ERC shows abrupt narrowing of distal CBD due to cancer (arrow) with upstream duct dilatation and deployment of plastic biliary stent (arrowhead)

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12.7.18 Benign Biliary Stricture After Living Donor Liver Transplantation a

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Fig. 12.18 Benign biliary stricture after living donor liver transplantation in a 49-year-old man. (a) T2-weighted MR shows fluid pocket along the resection margin of transplanted liver (asterisk). (b) MRCP shows tight stricture at the bile duct anastomosis site (arrow) with upstream

intrahepatic duct dilatation (arrowhead) and fluid pocket adjacent biliary stricture site, suggestive of biloma (asterisk). (c) Cholangiography obtained from ERC shows segmental stricture at the bile duct anastomosis site (arrow) with contrast media leakage forming biloma (asterisk)

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12.7.19 Clonorchiasis a

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Fig. 12.19 Clonorchiasis in a 54-year-old man. (a) Arterial phase CT shows diffuse mild dilatation of intrahepatic ducts in the peripheral portion with periductal patchy enhancement (arrows). (b) Portal phase CT

shows diffuse unproportionate dilatation of intrahepatic ducts at the peripheral portion (arrows). (c) Coronal phase CT image shows only mild dilatation of common bile duct (arrow) without obstructive lesion

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12.7.20 Cholangiocarcinoma with Clonorchiasis a

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Fig. 12.20 Cholangiocarcinoma with clonorchiasis in 75-year-old man. (a) Arterial phase CT shows diffuse mild dilatation of intrahepatic ducts in the peripheral portion (arrow) suggestive of clonorchiasis. Peripheral enhancing low density mass is noted in the posterior segment of right hepatic lobe (asterisk), which is cholangiocarcinoma. (b) Equilibrium phase CT shows ascites (asterisk) and peritoneal enhancing nodule (arrow) and necrotic lymph node (arrowhead) suggesting peritoneal seeding and lymph node metastasis of cholangiocarcinoma. (c) Portal phase image of dynamic MR shows diffuse peripheral intrahepatic

duct dilatation (arrows), lobulating mass with peripheral rim enhancement (asterisk), and peritoneal seeding nodules (arrowheads) with malignant ascites. (d) T2-weithed MR shows diffuse mild intrahepatic duct dilatation (arrows) and cholangiocarcinoma (asterisk). (e) Hepatobiliary phase of gadoxetic acid-enhanced MR image (20 min delay) shows tiny high signal intensity dots as biliary excretion of contrast media in the peripheral intrahepatic ducts (arrows) suggesting mild peripheral intrahepatic duct dilatation in clonorchiasis. Also note cholangiocarcinoma (asterisk) in the right posterior hepatic segment

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Suggested Reading Mazhar SM, Faria SC, Peterson MR, Sirlin CB. Cholestatic hepatic disorders. In: Sahani DV, Samir AE, editors. Abdominal imaging, vol. I. Maryland Heights: Saunders/Elsevier; 2011. p. 663–73. Michael C, Peter FH. Dilated bile ducts. In: Sahani DV, Samir AE, editors. Abdominal imaging. IIth ed. Maryland Heights: Saunders/ Elsevier; 2011. p. 871–3. Rao VA, Mehta UK, MacCarty RL. Inflammatory disorders of the biliary tract. In: Gore RM, Levin MS, editors. Textbook of gastrointestinal radiology, vol. II. 3rd ed. Philadelphia: Saunders/ Elsevier; 2008. p. 1489–504. Wiesner RH. Current concepts in primary sclerosing cholangitis. Mayo Clin Proc. 1994;69:969–82. De Groen PC, Gores GJ, LaRusso NF, et al. Biliary tract cancers. N Engl J Med. 1999;341:1368–78. Ito K, Mitchell DG, Outwater EK, et al. Primary sclerosing cholangitis; MR imaging features. AJR Am J Roentgenol. 1999;172:1527–33. MacCarty RL, LaRusso NF, May GR, et al. Cholangiocarcinoma complicating primary sclerosing cholangitis: cholangiographic appearances. Radiology. 1985;156:43–6. Matsui HO, Kadoya M, Takashima T, et al. Intrahepatic periportal abnormal intensity on MR images: an indication of various hepatobiliary disease. Radiology. 1989;171:335–8. Kaplan MM, Gershwin ME. Primary biliary cirrhosis. N Engl J Med. 2005;353:1261–73. Wenzel JS, Donohoe A, Ford KL, et al. Primary biliary cirrhosis: MR imaging findings and description of MR imaging periportal halo sign. AJR Am J Roentgenol. 2001;173:885–9.

445 Chan FL, Man SW, Leong LLY, et al. Evaluation of recurrent pyogenic cholangitis with CT: analysis of 50 patients. Radiology. 1989;170:165–9. Schulman A. Non-western patterns of biliary stones and the role of ascariasis. Radiology. 1987;162:425–30. Koga A, Ichimiya H, Yamaguchi K, et al. Hepatolithiasis associated with cholangiocarcinoma: possible etiologic significance. Cancer. 1985;55:2826–9. Lim JH, Ko YT, Lee DH, et al. Oriental cholangiohepatitis: sonographic findings in 68 cases. AJR Am J Roentgenol. 1990;155:511–14. Lim JH. Oriental cholangiohepatitis: pathologic, clinical and radiologic features. AJR Am J Roentgenol. 1991;157:1–8. Park HS, Lee JM, Kim SH, et al. CT differentiation of cholangiocarcinoma from periductal fibrosis in patients with hepatolithiasis. AJR Am J Roentgenol. 2006;187:445–53. Carpenter HA. Bacterial and parasitic cholangitis. Mayo Clin Proc. 1998;73:473–8. Choi BI, Park JH, Han MC, et al. CT findings of clonorchiasis. AJR Am J Roentgenol. 1989;152:281–4. Lim JH. Radiologic findings of clonorchiasis. AJR Am J Roentgenol. 1990;155:1001–8. Choi BI, Park JH, Kim YI, et al. Peripheral cholangiocarcinoma and clonorchiasis: CT findings. Radiology. 1988;169:149–53. Kubaska SM, Chew FS. Biliary ascariasis. AJR Am J Roentgenol. 1997;169:492. Hwang CM, Kim TK, Ha HK, et al. Biliary ascariasis: MR cholangiography findings in two cases. Korean J Radiol. 2001;2:175–8.

Cholecystitis and Adenomyomatosis

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Jae Young Lee

Contents 13.1 Acute Cholecystitis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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13.2 Chronic Cholecystitis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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13.3 Mirizzi Syndrome . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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13.4 Adenomyomatosis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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13.5 Cholesterolosis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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13.6 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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13.7 Illustrations: Cholecystitis and Adenomyomatosis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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Suggested Reading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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J.Y. Lee Department of Radiology, Seoul National University Hospital, Seoul, Republic of Korea e-mail: [email protected], [email protected] B.I. Choi (ed.), Radiology Illustrated: Hepatobiliary and Pancreatic Radiology, Radiology Illustrated, DOI 10.1007/978-3-642-35825-8_13, © Springer-Verlag Berlin Heidelberg 2014

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Cholecystitis means inflammation of the gallbladder. Cholecystitis can be divided into acute and chronic cholecystitis. Acute cholecystitis can have diverse complications such as gangrenous cholecystitis, hemorrhagic cholecystitis, emphysematous cholecystitis, and perforation in about 4–12 %. Chronic cholecystitis also can have complications including fistula such as cholecystoduodenal fistula and cholecystocolonic fistula, xanthogranulomatous cholecystitis that may simulate gallbladder cancer, and porcelain gallbladder that has increased risk of cancer. Adenomyomatosis of the gallbladder, a benign hyperplastic cholecystosis, appears as a diffuse or focal wall thickening so that it can mimic gallbladder cancer. Therefore, the radiologic differentiation is one of important subjects in the gallbladder. Mirizzi syndrome and cholesterolosis will be dealt with in this chapter.

13.1

Acute Cholecystitis

Acute cholecystitis is usually caused by gallbladder outlet obstruction. Acute calculous cholecystitis indicates the obstruction is caused by gallstones. Inflammation of the gallbladder wall starts from the mucosa and progresses to all layer unless it is treated. Typical clinical manifestation includes fever, right upper quadrant pain, leukocytosis, and Murphy sign. Imaging is usually necessary to make a confident diagnosis. Acute cholecystitis should be differentiated from other diseases such as peptic ulcer disease, liver abscess, pancreatitis, renal colic, and retrocolic appendicitis. CT features include distended gallbladder with thickened wall, pericholecystic inflammatory change, pericholecystic fluid, and transient hepatic attenuation difference in the gallbladder bed of the liver caused by reactive hyperemia.

13.1.1.2 Hemorrhagic Cholecystitis Hemorrhagic cholecystitis is a rare complication of acute cholecystitis and is usually associated with gallstones. Less commonly, it can occur in acute acalculous cholecystitis. Other causes of hemobilia that can present with blood in the gallbladder without associated cholecystitis include anticoagulation, biliary neoplasm, trauma including recent liver biopsy, and vascular disease. Hemorrhagic cholecystitis can simulate gallbladder carcinoma on US because blood clots can appear as clumps of echogenic material such as tumefactive sludge. 13.1.1.3 Emphysematous Cholecystitis Emphysematous cholecystitis is a severe complication of acute cholecystitis caused by gas-forming organisms. It has high morbidity (50 %) and high mortality (25 %). Predisposing factors include old age and diabetes mellitus. The organism commonly isolated in specimen cultures is Clostridium species. Diagnosis is made by imaging. CT is known to be the most sensitive tool to determine the presence of gas within the wall. 13.1.1.4 Perforation Gallbladder perforation occurs in 2–11 % of acute cholecystitis. Gallbladder perforation can happen within several days after the onset of acute cholecystitis. It is a rare but highly mortal disease. Its leading cause is vascular compromise and wall necrosis by luminal distension and subsequent rise in intraluminal pressure. The most common site of perforation is the fundus of the gallbladder because of its poor blood supply. Predisposing factors of perforation include malignancy, trauma, drugs, diabetes mellitus, and old age. Perforation manifests with generalized peritonitis, pericholecystic abscess, or fistulas such as bilio-colic fistula.

13.2

Chronic Cholecystitis

13.1.1 Complication of Acute Cholecystitis 13.1.1.1 Gangrenous Cholecystitis Gangrenous cholecystitis or necrotizing cholecystitis is a severe advanced complication of acute cholecystitis. Mural inflammation associated with marked distention of the gallbladder and increased tension of the wall leads to ischemic necrosis of the gallbladder wall with or without associated cystic artery thrombosis. The hallmark on imaging is the presence of striated or heterogeneous mural thickening which is frequently irregular, air in the gallbladder wall or lumen, the presence of detached mucosa in the lumen, pericholecystic fluid, and irregular or absent wall enhancement. Interestingly, sonographic Murphy sign is positive in only 33 % of patients with gangrenous cholecystitis in a report, probably due to denervation of the gallbladder wall.

Chronic cholecystitis results from wall damage by repeated attacks of inflammation for a long time, usually caused by gallstones and usually manifests as thickened wall and luminal contraction by fibrosis and scarring.

13.2.1 Chronic Cholecystitis-Related Complications 13.2.1.1 Fistula Fistula from the gallbladder is associated with gallstones in 90 % of cases. However, it can be also associated with peptic ulcer disease, abdominal trauma, Crohn’s disease, and malignancies of the biliary tract, bowel, and head of the pancreas. The duodenum is the most common site of cholecystoenteric

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Cholecystitis and Adenomyomatosis

fistulas, followed by the hepatic flexure of the colon. Rarely, the fistulas involve skin (cholecystocutaneous fistula), bronchial tree, stomach, and urinary tract. The presence of pneumobilia and an atrophic gallbladder adherent to neighboring organ is commonly observed in patients with cholecystoenteric fistulas. The fistulas are usually determined by the combined use of imaging modalities and by operative findings if any.

13.2.1.2 Xanthogranulomatous Cholecystitis Xanthogranulomatous cholecystitis is an uncommon form of chronic cholecystitis, characterized by intense acute or chronic inflammation, severe proliferative fibrosis with formation of multiple yellow-brown intramural nodules, and foamy histiocytes. It can be clinically and radiologically confused with gallbladder carcinoma because the inflammatory process often extends into neighboring organs such as the liver, omentum, duodenum, and colon. Almost all patients have gallstones or biliary obstruction. The most frequent imaging finding is thickening of the gallbladder wall. Characteristically, xanthogranulomatous cholecystitis often shows hypoechoic or hypodense nodules or bands in the gallbladder wall. These characteristic intramural nodules represent abscess or xanthogranuloma.

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advantage of showing the extent of inflammation and differentiating from other gallbladder pathologies such as gallbladder cancer.

13.4

Adenomyomatosis, also termed adenomyomatosis hyperplasia, is a benign hyperplastic disease. It is relatively common, found in 2–5 % of all surgical specimen of the gallbladder. Adenomyomatosis is defined as epithelial proliferation and muscular hyperplasia with Rokitansky-Aschoff sinuses. Adenomyomatosis of the gallbladder is morphologically classified into three types: diffuse, segmental, and fundal. It may simulate gallbladder cancer because it appears as a diffuse or localized wall thickening. Typical imaging findings of adenomyomatosis are wall thickening with intramural cysts and echogenic intramural foci on US, enhancing epithelium within intramural diverticula surrounded by the relatively unenhanced hypertrophied gallbladder muscularis (Rosary sign) on CT, and the pearl necklace sign on MRCP images.

13.5 13.2.1.3 Porcelain Gallbladder Porcelain gallbladder is a rare complication of chronic cholecystitis, characterized by calcification of the gallbladder wall. It can be detected and diagnosed on an abdominal x-ray image as a pear-shaped calcified mass in the right upper quadrant. On ultrasound, it appears as curvilinear echogenic lesion with shadowing in gallbladder fossa. Most patients are asymptomatic, but surgery is recommended due to its high risk of gallbladder cancer especially when it has selective mucosal calcification or incomplete calcification.

Cholesterolosis

Cholesterolosis indicates aggregates of lipid-containing macrophages in the lamina propria of the gallbladder mucosa. On gross specimen, it is usually seen as yellow flecks against a dark green background (strawberry gallbladder). Most patients with cholesterolosis do not have any symptom. Cholesterolosis affects the gallbladder locally or generally. General form of cholesterolosis appears as mild thickening of mucosal layer. Localized form of cholesterolosis appears as small polyps.

13.6 13.3

Adenomyomatosis

Summary

Mirizzi Syndrome

Mirizzi syndrome is a form of obstructive jaundice, first reported by Mirizzi in 1948. It occurs in about 0.1–0.7 % of patients with gallstones. It is defined as narrowing of common hepatic duct by a gallstone or gallstones impacted in the neck of the gallbladder or cystic duct. Its symptoms are similar to those of cholecystitis or choledocholithiasis. Most patients with Mirizzi syndrome present with epigastric or right upper quadrant pain, jaundice, and elevated liver function tests. Typical imaging findings of Mirizzi syndrome are a contracted gallbladder, impacted stone(s) in the cystic duct, a dilated intrahepatic duct and common hepatic duct, and a normal-sized common bile duct. Even though ERCP is known to be the gold standard in the diagnosis of Mirizzi syndrome, MRCP also allows for an accurate diagnosis of Mirizzi syndrome with the additional

1. Imaging features of acute cholecystitis include distended gallbladder with thickened wall, increased mural blood flow, pericholecystic inflammatory change, pericholecystic fluid, and transient hepatic attenuation difference in gallbladder bed. 2. Complications of acute cholecystitis include gangrenous cholecystitis, hemorrhagic cholecystitis, emphysematous cholecystitis, and perforation. 3. Imaging features of gangrenous cholecystitis are the presence of striated or heterogeneous mural thickening, air in the gallbladder wall or lumen, the presence of detached mucosa in the lumen, pericholecystic fluid, and irregular or absent wall enhancement. 4. Hemorrhagic cholecystitis indicates cholecystitis with hemorrhage into the gallbladder, which can simulate gallbladder carcinoma on imaging.

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5. The diagnosis of emphysematous cholecystitis is made by the presence of air within the gallbladder wall or lumen on imaging. 6. Perforation of the gallbladder manifests with generalized peritonitis, pericholecystic abscess, or fistulas such as bilio-colic fistula. 7. Chronic cholecystitis usually manifests as thickened wall and luminal contraction by fibrosis and scarring. 8. The duodenum is the most common portion among cholecystoenteric fistulas, followed by the hepatic flexure of the colon, manifested as the presence of pneumobilia and an atrophic gallbladder adherent to neighboring organ. 9. The most characteristic imaging finding of xanthogranulomatous cholecystitis is the presence of hypoechoic or hypodense nodules or bands in the gallbladder wall.

J.Y. Lee

10. Porcelain gallbladder is characterized by wall calcification of the gallbladder wall with increased risk of gallbladder cancer 11. Typical imaging findings of adenomyomatosis are wall thickening with intramural cysts and echogenic intramural foci on ultrasound, enhancing epithelium within intramural diverticula surrounded by the relatively unenhanced hypertrophied gallbladder muscularis (Rosary sign) on CT, and the pearl necklace sign on MRCP images. 12. Mirizzi syndrome is defined as narrowing of common hepatic duct by a gallstone or gallstones impacted in the neck of the gallbladder or cystic duct.

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13.7

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Illustrations: Cholecystitis and Adenomyomatosis

13.7.1 Acute Cholecystitis with a Cystic Duct Stone a

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Fig. 13.1 Acute cholecystitis with a cystic duct stone. (a). A cystic duct stone (arrow) is well visualized on precontrast CT image. (b, c) Diffuse wall thickening with mild inner layer enhancement (arrows)

and pericholecystic fat infiltration (arrowhead) with distended lumen are seen on contrast-enhanced CT

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13.7.2 Gallbladder Wall Edema a

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Fig. 13.2 Gallbladder wall edema. (a, b). Diffuse wall thickening of the gallbladder with loose outer layer (arrows) and intact inner layer (arrowheads) is seen on ultrasound, which represents edema of the perimuscular connective tissue and intact mucosa. The lumen is not distended. (c, d) Contrast-enhanced CT and T2-weighted MR images

show diffuse wall edema (arrows) and intact inner layer (arrowheads). Gallbladder wall thickening can be caused by chronic cholecystitis, liver dysfunction, ascites, hypoproteinemia, heart failure, renal disease, multiple myeloma, and so on as well as acute cholecystitis

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13.7.3 Acute Gangrenous Cholecystitis a

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Fig. 13.3 Acute gangrenous cholecystitis. (a) Irregular gallbladder wall thickening (arrowheads) with detached mucosa (arrow) is seen on ultrasound. Echogenic sludge is seen (asterisk). (b). Deep ulceration (arrowheads) with loss of normal wall layer toward gallbladder bed is seen on ultrasound. (c) Striated wall thickening is seen (arrowheads).

(d) CT reveals a markedly distended gallbladder with detached mucosa (arrowhead) in the lumen. The gallbladder wall is diffusely thickened. Heterogeneous liver enhancement seen in right lobe of the liver may indicate the coexistence of cholangiohepatitis or reactive hyperemia

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13.7.4 Acute Hemorrhagic Cholecystitis a

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Fig. 13.4 Acute hemorrhagic cholecystitis. He was being treated by sunitinib malate for the treatment of metastatic renal cell carcinoma. Sunitinib malate can cause mild or serious bleeding as a side effect. He was presented with abdominal pain and melena. (a) Precontrast CT shows a distended gallbladder with high attenuation contents (arrow). (b) Arterial phase CT shows a focal thickening of the fundus with a

faint contrast extravasation (arrowhead). (c) Portal venous phase CT shows more extravasation of contrast media in the lumen, indicating intraluminal active bleeding (arrowhead). (d) Abundant amount of echogenic material (arrows) fills the fundus and body of the gallbladder

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13.7.5 Emphysematous Cholecystitis a

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Fig. 13.5 Emphysematous cholecystitis. (a) Air (arrows) exists in the lumen of the distended gallbladder on precontrast CT. (b) Intramural airs (arrow) are seen, strongly indicating emphysematous cholecystitis on precontrast CT

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13.7.6 Emphysematous Cholecystitis a

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Fig. 13.6 Emphysematous cholecystitis. (a) Curvilinear band with very bright echogenicity is seen in the gallbladder fossa. It generates dirty posterior shadowing which is typically seen from the air bubbles.

(b) Plain radiograph shows curvilinear gas density in the right upper quadrant (arrow), which represents gas within the gallbladder wall. (c) Precontrast CT shows air within the gallbladder wall (arrow)

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13.7.7 Gallbladder Perforation a

Fig. 13.7 Gallbladder perforation. (a) Distended gallbladder has a gallstone (arrow) and pericholecystic fat infiltration (arrowhead). Hyperemia appears in the adjacent liver. (b) A lentiform fluid collection anterior to the right lobe of the liver with mass effect is seen

b

(arrowhead). The fluid collection is in contact with the fundus (not shown). It indicates subcapsular biloma by perforation of the fundus of the gallbladder

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13.7.8 Gallbladder Perforation

Fig. 13.8 Gallbladder perforation. Perforation into gallbladder bed (arrowhead) is seen along with distended gallbladder

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13.7.9 Chronic Calculous Cholecystitis with Cholesterolosis a

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Fig. 13.9 Chronic calculous cholecystitis with cholesterolosis. (a, b) Arterial phase (a) and portal venous phase (b) images show mild thickening of whole gallbladder wall and slight contraction of the lumen (arrows). However, the presence of stone cannot be determined on these CT images. (c) Ultrasound also shows thickening of the gallbladder wall (arrow) and a large stone (asterisk). Arrowhead indicates

prominently hyperechoic and thickened mucosal layer, which most likely represents cholesterol deposition in mucosal layer (cholesterolosis). (d) On gross specimen, mucosal surface shows diffuse yellowish material deposition by cholesterol. It was confirmed as chronic cholecystitis with cholesterolosis

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13.7.10 Cholecystoduodenal Fistula Causing Gallstone Ileus a

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Fig. 13.10 Cholecystoduodenal fistula causing gallstone ileus. (a) On plain radiograph, markedly dilated small bowel loops are seen, indicating mechanical ileus. (b) Precontrast CT shows a large stone (arrow) within terminal ileum, obstructing small bowel loop. (c) Enhanced CT

shows irregular wall thickening of gallbladder containing air (arrows). (d. On coronal CT image, the gallbladder (arrowhead) is connected with adjacent duodenum (arrow), indicating the presence of cholecystoduodenal fistula

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13.7.11 Xanthogranulomatous Cholecystitis a

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Fig. 13.11 Xanthogranulomatous cholecystitis. This patient presented dyspepsia for 6 months. (a) Precontrast CT shows marked gallbladder wall thickening (arrows) with an impacted gallbladder neck stone (large arrowhead). An intramural stone is also seen (small arrowhead). (b) Contrast-enhanced arterial phase CT shows marked thickening of the gallbladder with multiple intramural low attenuated nodular lesions

(arrowheads), representing abscess or xanthoma. (c) Portal venous phase shows multiple intramural lesions with fluid attenuation (arrowheads) and an impacted stone (arrow) at the neck. (d) T2-weighted MR image shows diffuse thickening of the wall (arrow). The intramural lesions are not seen on MR image

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13.7.12 Porcelain Gallbladder a

Fig. 13.12 Porcelain gallbladder. (a) At gallbladder fossa, a highly echogenic curvilinear band (arrowheads) is seen. It has a clear posterior shadowing (asterisk) which is a differential point from emphysematous

b

cholecystitis (Fig. 13.6). (b) Plain radiograph clearly shows dense wall calcification of the gallbladder (arrows)

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13.7.13 Fundal Adenomyoma a

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Fig. 13.13 Fundal adenomyoma. (a) Focal wall thickening is seen at the fundus (arrowhead). (b) T2-weighted MR image shows very bright high signal intensity (arrowhead), indicative of the presence of

fluid-filled cavity within the wall. (c) MR cholangiopancreatography image shows a typical appearance of “pearl necklace sign” (arrowhead)

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13.7.14 Segmental Adenomyomatosis a

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Fig. 13.14 Segmental adenomyomatosis. (a) Annular narrowing with thickened wall (arrow) is seen at the gallbladder body. (b, c) T2-weighted MR images show that the thickened portion has intramural cystic cavities, a typical finding of “pearl necklace sign” (arrows)

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13.7.15 Diffuse Adenomyomatosis a

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Fig. 13.15 Diffuse adenomyomatosis. (a, b) Arterial phase (a) and portal venous phase (b) CT images show marked wall thickening with enhancing mucosa and intramural diverticula-like areas (arrowheads). (c) Ultrasound shows the presence of multiple intramural highly

echogenic materials (arrowheads) with comet tail artifact, most likely representing intramural cholesterol crystal and stones within Rokitansky-Aschoff sinuses. (d) Pathologic specimen shows multiple dark gray-colored stones (arrows) within thickened wall

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13.7.16 Diffuse Adenomyomatosis Involving the Fundus and Body of the Gallbladder a

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Fig. 13.16 Diffuse adenomyomatosis involving the fundus and body of the gallbladder. (a, b) Axial (a) and coronal (b) portal venous phase T1 weighted MR images show a marked wall thickening and markedly heterogeneous wall enhancement of the fundal chamber (arrows). (c) Heavily T2-weighted coronal MR image shows the presence of intramural cysts within the annular constriction segment of the gallbladder body (arrows). It also shows the presence of intramural cysts

(arrowheads) within thickened wall of the fundal chamber. (d) Ultrasound shows multiple intramural echogenic spots (arrows) with comet-tail artifacts within the annular constriction portion of the gallbladder body, typical finding of adenomyomatosis. (e) The echogenic spots generate color Doppler twinkling artifacts (arrows) on color Doppler ultrasound. (f) Echogenic spots (arrowheads) are also seen in the thickened wall of the fundal chamber

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13.7.17 Mirizzi Syndrome a

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Fig. 13.17 Mirizzi syndrome. (a, b). Portal venous phase CT images show dilated intrahepatic ducts (arrowhead) (a) and a stone (arrow) at the hilum (b). (c) The gallbladder has a mild wall thickening (arrow). (d) A focal indentation of common hepatic duct (arrow) is seen at the insertion site of cystic duct on MR cholangiopancreatography. (e) The

indentation (arrow) is also seen on endoscopic retrograde cholangiopancreatography. (f) A cystic stone (arrow) is located between cystic duct and common hepatic duct on ultrasound. (g) The cystic stone is surrounded by soft tissue (arrowheads), which was confirmed as xanthogranulomatous inflammatory change

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Fig. 13.17 (continued)

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Suggested Reading Ahlawat SK, Singhania R, Al-Kawas FH. Mirizzi syndrome. Curr Treat Options Gastroenterol. 2007;10:102–10. Bedirli A, Sakrak O, Sozuer EM, et al. Factors effecting the complications in the natural history of acute cholecystitis. Hepatogastroenterology. 2001;48:1275–8. Bennett GL, Balthazar EJ. Ultrasound and ct evaluation of emergent gallbladder pathology. Radiol Clin North Am. 2003;41:1203–16. Bennett GL, Rusinek H, Lisi V, et al. CT findings in acute gangrenous cholecystitis. AJR Am J Roentgenol. 2002;178:275–81. Boscak AR, Al-Hawary M, Ramsburgh SR. Best cases from the AFIP: adenomyomatosis of the gallbladder. Radiographics. 2006;26:941–6. Chun KA, Ha HK, Yu ES, et al. Xanthogranulomatous cholecystitis: CT features with emphasis on differentiation from gallbladder carcinoma. Radiology. 1997;203:93–7. Garcia-Sancho Tellez L, Rodriguez-Montes JA, Fernandez de Lis S, et al. Acute emphysematous cholecystitis: report of twenty cases. Hepatogastroenterology. 1999;46:2144–8. Gremmels JM, Kruskal JB, Parangi S, et al. Hemorrhagic cholecystitis simulating gallbladder carcinoma. J Ultrasound Med. 2004;23: 993–5. Haradome H, Ichikawa T, Sou H, et al. The pearl necklace sign: an imaging sign of adenomyomatosis of the gallbladder at MR cholangiopancreatography. Radiology. 2003;227:80–8. Ijaz S, Lidder S, Mohamid W, et al. Cholecystocutaneous fistula secondary to chronic calculous cholecystitis. Case Rep Gastroenterol. 2008;2:71–5. Isch JH, Finneran JC, Nahrwold DL. Perforation of the gallbladder. Am J Gastroenterol. 1971;55:451–8. Jeffrey RB, Laing FC, Wong W, et al. Gangrenous cholecystitis: diagnosis by ultrasound. Radiology. 1983;148:219–21. Jenkins M, Golding RH, Cooperberg PL. Sonography and computed tomography of hemorrhagic cholecystitis. AJR Am J Roentgenol. 1983;140:1197–8.

469 Kane RA, Jacobs R, Katz J, et al. Porcelain gallbladder: ultrasound and CT appearance. Radiology. 1984;152:137–41. Kim PN, Lee SH, Gong GY, et al. Xanthogranulomatous cholecystitis: radiologic findings with histologic correlation that focuses on intramural nodules. AJR Am J Roentgenol. 1999;172:949–53. Makino I, Yamaguchi T, Sato N, et al. Xanthogranulomatous cholecystitis mimicking gallbladder carcinoma with a false-positive result on fluorodeoxyglucose PET. World J Gastroenterol. 2009;15: 3691–3. Mentzer Jr RM, Golden GT, Chandler JG, et al. A comparative appraisal of emphysematous cholecystitis. Am J Surg. 1975;129:10–5. Morris BS, Balpande PR, Morani AC, et al. The CT appearances of gallbladder perforation. Br J Radiol. 2007;80:898–901. Noskin EA, Strauss AA, Strauss SF. Spontaneous internal biliary fistula: a review of the literature and report of two cases. Ann Surg. 1949;130:270–6. Owen CC, Bilhartz LE. Gallbladder polyps, cholesterolosis, adenomyomatosis, and acute acalculous cholecystitis. Semin Gastrointest Dis. 2003;14:178–88. Parra JA, Acinas O, Bueno J, et al. Xanthogranulomatous cholecystitis: clinical, sonographic, and CT findings in 26 patients. AJR Am J Roentgenol. 2000;174:979–83. Paulson EK. Acute cholecystitis: CT findings. Semin Ultrasound CT MR. 2000;21:56–63. Simeone JF, Brink JA, Mueller PR, et al. The sonographic diagnosis of acute gangrenous cholecystitis: importance of the murphy sign. AJR Am J Roentgenol. 1989;152:289–90. Williams I, Slavin G, Cox A, et al. Diverticular disease (adenomyomatosis) of the gallbladder: a radiological-pathological survey. Br J Radiol. 1986;59:29–34. Yamashita H, Chijiiwa K, Ogawa Y, et al. The internal biliary fistulareappraisal of incidence, type, diagnosis and management of 33 consecutive cases. HPB Surg. 1997;10:143–7. Zaliekas J, Munson JL. Complications of gallstones: the Mirizzi syndrome, gallstone ileus, gallstone pancreatitis, complications of “lost” gallstones. Surg Clin North Am. 2008;88:1345–68.

Cholangiocarcinoma

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Jin-Young Choi and Joon Koo Han

Contents 14.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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14.2 Demographic and Clinical Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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14.3 Pathology. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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14.4 CC Evaluation on Imaging . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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14.5 Staging and Evaluation of Resectability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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14.6 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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14.7 Illustrations: Cholangiocarcinoma . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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Suggested Reading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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J.-Y. Choi Department of Radiology, Yonsei University College of Medicine, Severance Hospital, Seoul, Republic of Korea e-mail: [email protected] J.K. Han (*) Department of Radiology, Seoul National University Hospital, Seoul, Republic of South Korea e-mail: [email protected] B.I. Choi (ed.), Radiology Illustrated: Hepatobiliary and Pancreatic Radiology, Radiology Illustrated, DOI 10.1007/978-3-642-35825-8_14, © Springer-Verlag Berlin Heidelberg 2014

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14.1

J.-Y. Choi and J.K. Han

Introduction

Bile duct cancer or cholangiocarcinoma (CC) is a malignant tumor arising from bile duct epithelium. Traditionally the tumor is classified into intrahepatic (10 %), hilar (50–60 %), and extrahepatic (20–30 %) types according to its location within the biliary tree. Intrahepatic CC arises from the bile ducts peripheral to the secondary bifurcation of the left or right hepatic duct. Extrahepatic CC refers to a malignant tumor occurring from the left or right hepatic duct to the ampulla. Hilar CC, or Klatskin tumor, is defined as tumors typically located at the confluence of the right and left ducts within the porta hepatis. Hilar CC has been considered either intrahepatic or extrahepatic: While epidemiologic studies reported that more than 90 % of hilar tumors were classified as intrahepatic, other researchers insisted that hilar tumor should be classified into a type of extrahepatic CC based on the anatomical location of the hilum and the similarity of the biologic behaviors to extrahepatic tumors. It is often regarded as a separate category, hilar or perihilar tumor, based on their topographic site of origin.

14.2

10–15 %. Many toxic and environmental factors such as thorotrast, dioxin, and polyvinyl chloride are implicated in the pathogenesis of CC. Intrahepatic mass-forming CC usually presents with nonspecific symptoms, such as anorexia and weight loss, or can be detected as incidental lesion by ultrasound examination. On the other hand, hilar or extrahepatic CC presents signs and symptoms related to the biliary obstruction.

14.3

Pathology

The Liver Cancer Study Group of Japan has proposed a classification based on macroscopic appearance and growth characteristics. CC can be classified into three types according to their morphology and growth pattern: the massforming type, the periductal infiltrative type, and the intraductal-growing type. The prognosis for mass-forming and periductal-infiltrating CC is generally unfavorable, whereas the prognosis for intraductal-growing CC is much better after surgical resection. The different biologic behavior of the tumors seems to be related to their locations and size at the time of diagnosis (Table 14.1).

Demographic and Clinical Features

The incidence of CC among the primary liver tumors is around 10–20 %. It generally occurs during the sixth and seventh decades of life. Most common etiologies of CC are liver fluke infestation (clonorchiasis), recurrent pyogenic cholangitis (hepatolithiasis), and chronic hepatitis B or C in Eastern population. A strong association between primary sclerosing cholangitis and CC is well recognized in Western population. In an endemic population, diffuse, mild peripheral IHD dilatation with normal CBD caliber is diagnostic of clonorchiasis, and an associated mass should raise a suspicion of CC. CC can develop in a congenital choledochal cyst, with a lifetime risk of

14.3.1 Mass-Forming CC Mass-forming CC is the most common type of intrahepatic CC. It arises from the mucosa of a branch of the bile ducts in the peripheral area of the liver, invading and penetrating the bile duct wall, and spreads between hepatocytes plates. It has a propensity to invade small adjacent portal branches in the form of venous tumoral thrombi. Macroscopically, massforming CC is characterized by a white, firm, homogeneous sclerotic mass with an irregular lobulated margin, typically in the absence of hemorrhage or necrosis. The viable tumor cells are usually located at the periphery of the tumor.

Table 14.1 Classification of cholangiocarcinoma according to growth characteristics Type Mass forming

Common location Intrahepatic

Periductal infiltrating

Hilar or extrahepatic

Intraductal growing

Intrahepatic or extrahepatic

Mode of spread Invading and penetrating the bile duct wall, spreading between hepatocytes plates

Typical imaging findings Infiltrative hepatic mass with capsular retraction or peripheral ductal dilatation Irregular rim-like enhancement around periphery of tumor on arterial phase and progressive enhancement on delayed phase images Spread along the bile duct Mural and periductal soft-tissue wall via the nerve and thickening or focal irregularities of perineural tissue the bile duct Frequently present with long Focal or diffuse ductal dilatation with range of mucosal spread multifocal papillary or sessile masses

Prognosis Unfavorable

Unfavorable

Favorable after surgical resection

14 Cholangiocarcinoma

Characteristically this tumor has a large central core of fibrotic tissue, due to the desmoplastic reaction induced by the neoplastic cells. Microscopically, CC represents an adenocarcinoma with its tubular or acinar-glandular structures.

14.3.2 Periductal-Infiltrating CC Periductal-infiltrating CC is the most common type of hilar CC. Arising from the mucosa of the intrahepatic or extrahepatic bile ducts, the tumor invades the wall and penetrates to the serosa. The tumor appears as a diffuse, firm, grays-white, annular thickening of the bile duct causing almost complete obstruction of the lumen. In contrast to mass-forming CC, infiltrating CC tends to spread along the bile duct wall via the nerve and perineural tissue of Glisson’s capsule toward the porta hepatis. Macroscopically, this neoplasm appears as elongated, spiculated, or branch-like annular thickening of the bile duct walls. Irregular narrowing of the involved bile ducts eventually results in the obstruction of the lumen.

14.3.3 Intraductal-Growing CC Intraductal-growing CC is a low-grade papillary adenocarcinoma, composed of innumerable frond-like infoldings of columnar epithelial cells and fibrovascular cores. The tumor cells are confined within the mucosal layer, spread superficially without invading the submucosal layer. The tumor cells are friable and may slough spontaneously from the walls of the bile ducts. The tumors are usually small, sessile, or polypoid, but sometimes a large mass may occlude an aneurysmally dilated bile duct. The biliary tract may be dilated diffusely in a lobar or segmental fashion. When an intraductal CC produces a large amount of mucin, it is called intraductal papillary mucinous neoplasm (IPMN) of the bile ducts.

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CC Evaluation on Imaging

14.4.1 Role of Imaging Surgical resection is the best available and potentially curative therapy for CC. Technical advances in diagnostic imaging allow better selection of surgical candidates. Ultrasonography accurately recognizes biliary tract dilatation and is helpful in depicting intraductal tumors. Crosssectional imaging such as CT and MRI are the primary tools used in the assessment of longitudinal and lateral spread of CC and determining respectability. MDCT is a widely used

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noninvasive examination for the staging of CC. MDCT is an excellent imaging technique for evaluating the soft-tissue extent of CC and its relation between the tumor and the hepatic vasculature. Recently, fusion imaging techniques have been introduced. It may display tumor itself as well as the surrounding vessels and demonstrate complex anatomic relationship of bile duct cancer. These techniques seem to have a potential to improve treatment planning with MDCT. MR imaging in combination with MRCP can be used as a sole imaging modality for evaluation of bile duct cancer. The roles of MRI combined with MRCP are (1) to differentiate benign from malignant causes of biliary stricture, (2) to determine resectability in patients with bile duct cancer, (3) to preoperatively stage, (4) and to differentiate between the different appearances of growth patterns. Direct cholangiography including ERCP and percutaneous transhepatic cholangiography (PTC) is still the standard of reference for biliary extent of the tumors. FDG-PET is valuable for detecting unsuspected distant metastases particularly in patients with peripheral CC because of the likelihood of distant metastases at the time of diagnosis and the high uptake in the peripheral type. Also, it has been reported that FDG-PET evaluates the lymph node metastases more accurately compared with CT.

14.4.2 Imaging Findings 14.4.2.1 Mass-Forming CC Mass-forming CC manifests as a solitary mass in the liver parenchyma with a nodular pattern. Lesions smaller than 3 cm tend to be homogeneously hypoechoic or isoechoic, whereas tumors larger than 3 cm are predominantly hyperechoic on US. A peripheral hypoechoic area or halo sign can be observed. However, it shows diverse echo patterns and may be hypo-, iso-, or hyperechoic and homogeneous or heterogeneous. Peripheral ductal dilatation is occasionally associated. Unenhanced CT scan may show a predominantly hypoattenuating mass. Calcification may be seen in the central portion of the lesions, especially in mucin-secreting tumors. Typical enhancement patterns on CT are marked hypoattenuation with thin, incomplete peripheral enhancement during arterial and portal venous phases and centripetal progression of enhancement over time. The morphology of peripheral CC on imaging as well as its histology is similar to that of metastatic adenocarcinoma, but CC is more likely to be solitary, large, with occasional association with peripheral ductal dilatation. The peripheral portion has viable cancer cells that show incomplete rim enhancement on arterial phase and peripheral washout. The central portion contains

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more fibrous stroma and shows mild centripetal progression and delayed or prolonged enhancement on dynamic CT or MR. Other common findings of CC include frequent capsular retraction because of desmoplastic reaction, marked hypoattenuation from mucin component, satellite nodules, extracapsular extension, lymphadenopathy, and vascular encasement within the mass. It has been reported that small (10 cells/high power fields) Absent Sixth to seventh decade Male > female IgG4-related disease

No (2 cm) cysts without central scarring or calcification, therefore making morphologic differentiation from mucinous cystadenoma difficult. Differential points of SOIA from MCN include lobulating outer margin. The VHL-associated serous adenoma appears as multiple serous cystic lesions distributed throughout the entire pancreas. Other organ involvement such as brain, retinal, and spinal cord hemangioblastomas; renal cysts and renal cell carcinoma; pheochromocytomas can be combined. Solid serous adenoma manifesting itself as a hypervascular solid lesion without cystic portion is radiologically confused with true solid tumors such as neuroendocrine tumors or solid pseudopapillary tumors. Serous cystadenocarcinoma is very rare and only less than 30 cases have been reported. Imaging findings of serous cystadenocarcinoma are similar to those of serous microcystic adenoma except gross evidence of invasiveness.

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Mucinous Cystic Neoplasm (MCN)

Mucinous cystic neoplasm (MCN) occurs almost exclusively in women, showing no communication with the pancreatic ductal system and composed of columnar, mucin-producing epithelium, supported by ovarian-type stroma. According to the grade of intraepithelial dysplasia, tumors may be classified as MCN with low- or intermediate-grade dysplasia, MCN with high-grade dysplasia, and MCN with an associated invasive carcinoma. Radiologically, MCN appears as a single lesion with unilocular or multilocular cysts as well as internal septa. The thickness of the cyst wall and fibrous septa is almost uniform and the outer contour is smoother than in SCN. In contrast to SCN, incidental calcifications appear rather peripherally in a linear, eggshell pattern. Hemorrhage within the cyst is indicative of this tumor. MCN generally exhibits no connection to the pancreatic duct and rather displaces the duct. Solid mural nodules, cyst dimensions of >6 cm, and peripheral calcification are well-accepted criteria for malignancy.

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Cystic Degeneration of Solid Pancreatic Tumor

Solid pancreatic tumors such as solid pseudopapillary neoplasm (SPN) and pancreatic ductal adenocarcinoma may undergo cystic degeneration, masking its originality as a solid tumor. SPT is found almost in young women with a

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mean age of 30 years. SPT consists largely of solid components alternating with pseudopapillary formations of tissue, supported by strands of vascular, hyaline tissue. Radiologically, it appears as a partial cystic mass surrounded by a thick, irregular, enhancing capsule. A 2–10 % of pancreatic NET may also show cystic change. A cystic form of NET tends to have favorable prognosis. Cystic feature of solid pancreatic tumors may result due to necrosis, hemorrhage, and degeneration of tumor cells.

19.6

Other Cystic Lesions

Non-epithelial cystic tumors such as lymphangioma can be rarely developed in the pancreas. In addition, nonneoplastic cystic lesions such as lymphoepithelial cyst and retention cyst may occur in the pancreas. Lymphoepithelial cyst is lined by mature squamous epithelium and surrounded by lymphoid tissue and is usually filled with keratinized material. Although lymphoepithelial cyst is categorized as a pancreatic cystic lesion, it is usually located at peripancreatic or extrapancreatic area because it is known to be developed from epithelial remnants in the lymph node outside of the pancreas. Radiologically, it shows a lobulated margin and has slightly hyperdense fluid due to keratinized material. A pancreatic retention cyst is defined as a segment of a pancreatic duct that is cystically dilated as a consequence of duct obstruction. Duct obstruction is caused by fibrous strictures, mucin plugs, calculi, tumors, or neoplastic epithelial proliferations such as PanIN. A retention cyst appears as a small cystic lesion communicating with the pancreatic duct as a consequence of duct obstruction. However, it cannot be confidently diagnosed preoperatively. Epidermoid cyst in intrapancreatic accessory spleen may also mimic cystic pancreatic tumors. However, typical location (pancreatic tail) and

enhancement pattern of remnant solid component which is the same or similar to that of the main spleen on CT or MRI can be important clues for differentiating from other cystic lesions.

19.7

Summary

1. Cystic pancreatic tumors and tumorlike lesions represent a wide spectrum of histopathology from purely benign to overly malignant. 2. The most important diagnostic strategy for accurate characterization of cystic pancreatic tumors is to differentiate non-mucinous cystic tumor from mucinous types of tumors. 3. The most common cystic pancreatic tumor is intraductal papillary mucinous neoplasms (IPMNs). 4. The most important diagnostic clue for IPMN is to detect communication between the lesion and pancreatic duct. 5. For IPMN, the risk of malignancy increases with older age, presence of symptoms, involvement of the main pancreatic duct, dilation of the main pancreatic duct over 10 mm, the presence of mural nodules, and size >3 cm for branch duct type IPMN. 6. Serous cystic neoplasm (SCN) can be further categorized into 5 different subtypes according to their macroscopic appearances: serous microcystic adenomas, serous oligocystic ill-defined adenoma, von Hippel-Lindau-associated serous cystic neoplasm, solid serous adenoma, and serous cystadenocarcinoma. 7. SCN tends to have a lobulating outer margin, while mucinous cystic neoplasm has a smooth outer margin. 8. Solid pseudopapillary neoplasm is the most common solid pancreatic tumor which can mimic cystic pancreatic tumor due to a tendency of cystic degeneration.

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Cystic Tumors of the Pancreas

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Illustrations: Cystic Tumors of the Pancreas

19.8.1 Schematic Diagrams of Cystic Pancreatic Lesions a

Unilocular

Oligolocular

Multilocular

b

Smooth outer margin

Lobulated outer margin Fig. 19.1 Classification of cystic pancreatic lesions. (a) According to the number of the cyst, cystic lesions can be subdivided by unilocular (one cyst), oligolocular (2–6 cysts), and multilocular (seven or more cysts) lesions. (b–d) Cystic lesions can be further classified based on other morphologic features such as outer contour (smooth vs lobulated in b), the presence of communication between the cyst and the pancre-

atic duct (c), and mural nodule (d). (e) Characteristic appearances of the cystic lesions such as honeycomb, pleomorphic, and clubbed fingerlike appearances are sometimes an important clue for the differentiation. (f) Cystic lesions can be associated with different patterns of pancreatic duct dilatation: diffuse, upstream, and downstream duct dilatation

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Communication with pancreatic duct

c

No

Yes

Yes

d

Mural nodule (–)

Mural nodule (+)

e

Honeycomb appearance with central scar

f

Pleomorphic

Clubbed finger-like

Pancreatic duct dilatation

Diffuse

Fig. 19.1 (continued)

Upstream

Downstream

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19.8.2 Schematic Diagrams of Morphologic Classification of Intraductal Papillary Mucinous Neoplasm

Main duct type

Branch duct type

Combined type

Fig. 19.2 Schematic diagram of morphologic classification of pancreatic intraductal papillary mucinous neoplasm. Intraductal papillary mucinous neoplasms are subcategorized clinically into main duct type, branch duct type, and combined type based on their location and morphology

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19.8.3 Intraductal Papillary Mucinous Neoplasm with Low-Grade Dysplasia: Branch Duct Type a

b

Fig. 19.3 Intraductal papillary mucinous neoplasm with low-grade dysplasia, branch duct type in a 55-year-old man. (a) Serial axial images on portal phase CT show a cystic lesion (arrows) with suspicious communication (arrowhead) to the pancreatic duct. (b) Coronal curved reformatted portal phase CT image clearly depicts the communication (arrowhead) between the cyst (arrow) and pancreatic duct. (c) T2-weighted MRI shows a pleomorphic nature of cysts within the lesion (arrow). (d) Precontrast (upper left), arterial (upper right), portal (lower left), and delayed (lower right) phase MR images well demon-

c

strate the lesion. No mural nodule or wall thickening is noted. (e, f) MR cholangiopancreatography (e) and endoscopic retrograde pancreatography (f) clearly depict a communication (arrowhead) between the lesion (arrow) and pancreatic duct (asterisk). (g) Distal pancreatectomy specimen shows a mild dilatation of the main pancreatic duct (asterisk), and final pathology reveals the diagnosis of intraductal papillary mucinous neoplasm with low-grade dysplasia, branch duct type. Main duct involvement is not demonstrated on pathology

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d

e

f

* *

g

*

Fig. 19.3 (continued)

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19.8.4 Intraductal Papillary Mucinous Neoplasm with Intermediate-Grade Dysplasia: Branch Duct Type a

b

c

Fig. 19.4 Intraductal papillary mucinous neoplasm with intermediategrade dysplasia: branch duct type. (a, b) Axial (a) and coronal reformatted (b) portal phase CT images demonstrate a lobulated cystic lesion (arrow) in the uncinate process of the pancreas. Note a communication (arrowhead) between the lesion and pancreatic duct. (c) T2-weighted MR image also shows a cystic lesion (arrow) with ductal communication (arrowhead). Note a pleomorphic appearance of the lesion. (d) Precontrast (upper left), arterial (upper right), portal (lower left), and delayed (lower right) phase MR images well demonstrate the

lesion. (e, f) MR cholangiopancreatography (e) and endoscopic retrograde pancreatography (f) clearly depict a communication (arrowhead) between the lesion (asterisk) and pancreatic duct (arrow). (g) Cut section of specimen from the pylorus-preserving pancreaticoduodenectomy shows a direct communication between the cystic lesion (arrows) and the pancreatic duct (arrowheads). Microscopy confirmed the diagnosis of intraductal papillary mucinous neoplasm with intermediategrade dysplasia at the branch pancreatic duct

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d

e

f

* g

Fig. 19.4 (continued)

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19.8.5 Intraductal Papillary Mucinous Neoplasm with Low-Grade Dysplasia: Main Duct Type a

b

Fig. 19.5 Intraductal papillary mucinous neoplasm with low-grade dysplasia: main duct type in a 73-year-old man. (a) Arterial (left) and portal (right) phase CT images demonstrate a focally dilated main pancreatic duct (arrows) at the tail of the pancreas. (b, c) Precontrast (left), arterial (middle), and portal (right) phase gadolinium-enhanced MR (b) and MR cholangiopancreatography (c) images also show a focally

dilated main duct (arrows) at the pancreatic tail. No mural nodule or ductal wall thickening is noted. (d) Specimen of distal pancreatectomy shows a dilated main pancreatic duct (arrow), and final pathologic diagnosis was intraductal papillary mucinous neoplasm with low-grade dysplasia: main duct type

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c

Fig. 19.5 (continued)

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19.8.6 Intraductal Papillary Mucinous Neoplasm with Intermediate-Grade Dysplasia: Main Duct Type a

b

c

d

e

f

Fig. 19.6 Intraductal papillary mucinous neoplasm with intermediategrade dysplasia: main duct type in a 65-year-old man. (a–c) Pancreatic (a) and portal (b) phase axial CT and pancreatic phase coronal reformatted (c) CT images demonstrate diffuse dilatation of the main pancreatic duct (arrows). There is an elongated mural nodule (arrowhead) within the dilated duct. (d, e) Axial T2-weighted (d) MR and MR cholangiopancreatography (e) images also depict diffuse dilatation of the

main pancreatic duct (arrows) and inner mural nodule (arrowhead). (f) Gross specimen obtained after Whipple’s operation reveals diffuse dilatation of the main pancreatic duct (arrows) with intraductal mural nodule (arrowhead). Microscopic examination reveals the diagnosis of intraductal papillary mucinous neoplasm with intermediate-grade dysplasia: main duct type

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19.8.7 Invasive Intraductal Papillary Mucinous Carcinoma: Combined Main and Branch Duct Type a

b

Fig. 19.7 Invasive intraductal papillary mucinous carcinoma: combined main and branch duct type in a 74-year- old man. (a–c) Serial axial images of portal phase CT (a) coronal curved reformatted pancreatic phase CT (b) and coronal axial portal phase MR (c) images show a large cystic mass (arrows) with multiple enhancing papillary nodules in the head of the pancreas. Main pancreatic duct (arrowheads) is also dilated. (d) T2-weighted coronal MR image clearly depicts a large cystic mass (arrows) with papillary mural nodules in the pancreatic head.

c

Note a pleomorphic appearance of cysts within the lesion. (e) On MR cholangiopancreatography, a communication (asterisk) between the lesion (arrows) and main pancreatic duct (arrowheads) is clearly visualized. (f) On a photograph of gross specimen, the cystic mass is filled with papillary mural nodules. Final pathologic diagnosis was invasive intraductal papillary mucinous carcinoma arising from the branch pancreatic duct. And main duct involvement by the tumor is also confirmed

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e

*

f

Fig. 19.7 (continued)

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19.8.8 Ruptured Intraductal Papillary Mucinous Neoplasm a

b

*

*

c

d

*

*

e

Fig. 19.8 Ruptured intraductal papillary mucinous carcinoma in a 68-year-old woman. (a, b) Portal phase axial (a) and coronal curved reformatted (b) CT images demonstrate a large cystic lesion (asterisk) with suspicious communication to the main pancreatic duct (arrowheads). (c) Endoscopic US clearly demonstrates the communication (arrowhead) between the cyst (asterisk) and the duct. (d, e) On follow-

f

up CT taken 4 months later, the size of the lesion (asterisk) decreases and newly appeared small amount of ascites (arrowheads in e) is noted around the pancreatic tail. (f) Distal pancreatectomy confirms the diagnosis of ruptured intraductal papillary mucinous carcinoma (arrows) in the pancreatic tail

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19.8.9 Serous Cystadenoma: Microcystic Type a

b

c

d

e

f

Fig. 19.9 Serous microcystic adenoma in a 48-year-old woman. (a, b) Precontrast (a) and portal (b) phase axial CT images show a large honeycomb-like mass (arrows) in the body of the pancreas. Small calcific foci (arrowheads) are noted at the central portion of the lesion. (c) T2-weighted MRI demonstrates a bright intensity of the lesion (arrows), confirming the cystic nature of the lesion. Mild dilatation of upstream pancreatic duct (arrowhead) is visualized due to mass effect by the

lesion. (d, e) Precontrast axial (d) and portal (e) phase coronal T1-weighted MR images depict the enhancement of the fine septa within the lesion (arrows). Note central scar tissue (arrowhead, e) in the mass. (f) Distal pancreatectomy specimen shows a spongelike cystic mass (arrows) with central scar (asterisk). Pathology confirmed the diagnosis of serous microcystic adenoma

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19.8.10 Serous Cystadenoma: Oligocystic Ill-Defined Type a

b

c

d

e

Fig. 19.10 Serous oligocystic adenoma in a 52-year-old man. (a, b) Coronal curved reformatted. CT (a) and T2-weighted axial MR (b) images show a lobulating cystic lesion (arrows) containing approximately six locules at the head of the pancreas. (c) Portal phase T1-weighted MRI demonstrates the subtle enhancement of the septa within the cyst. (d) MR cholangiopancreatography well depicts the

lobulating outer margin of the cyst. No pancreatic duct dilatation or communication to the lesion is demonstrated. (e) Gross specimen obtained after pylorus-preserving pancreaticoduodenectomy shows an oligocystic lesion in the pancreatic head. Microscopic diagnosis was serous oligocystic adenoma

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19.8.11 Serous Cystadenoma: Solid Type a

b

c

d

e

Fig. 19.11 Solid serous adenoma in an 83-year-old woman. (a–c) Precontrast (a), arterial (b), and portal (c) phase CT images demonstrate a strongly enhancing solid mass (arrows) in the uncinate process of the pancreas. (d) T2-weighted MRI shows an intermediate highintensity mass (arrows) in the pancreas. (e) MR cholangiopancreatography demonstrates a non-cystic mass (asterisk) in the pancreatic head with mild bile duct (arrow) and upstream pancreatic duct (arrowheads)

dilatation. (f) On dynamic gadolinium-enhanced T1-weighted MRI, the lesion also shows a strong enhancement (asterisk) on both arterial (middle) and portal (right) phases compared to precontrast (left) image. Tentative preoperative diagnosis for the lesion was pancreatic neuroendocrine tumor. (g) Gross specimen obtained after pylorus-preserving pancreaticoduodenectomy shows a brownish solid mass (arrows) in the pancreatic head. Microscopic diagnosis was solid serous adenoma

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f

*

g

Fig. 19.11 (continued)

*

*

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19.8.12 von Hippel-Lindau Disease Associated Serous a b Cystadenoma

*

*

*

c

Fig. 19.12 Multiple serous cystadenoma associated with von HippelLindau disease in a 34-year-old man. (a, b) On coronal (a) and axial (b) arterial phase CT, the entire pancreas (arrows) is replaced by numerous cystic lesions. Three hypervascular renal cell carcinomas (asterisk) are

also demonstrated in both kidneys. Note a small enhancing hemangioblastoma (arrowhead) in the spinal cord. (c) Vertebral arteriography demonstrates several hemangioblastomas (arrowheads) in the cerebellum

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19.8.13 Mucinous Cystic Neoplasm with Low-Grade Dysplasia a

b

c

d

e

f

g

Fig. 19.13 Mucinous cystic neoplasm with low-grade dysplasia in a 58-year-old woman. (a–d) Precontrast (a, c) and portal phase (b, d) CT and MR images depict a round oligocystic lesion (arrow) with smooth margin at the pancreatic tail. Note fine septa (arrowhead) within the lesion. (e) Fat-saturated T2-weighted HASTE coronal MR image clearly demonstrates fine septa (arrowhead) within the cyst (arrow). (f)

On MR cholangiopancreatography, there is no communication between the cyst (arrows) and pancreatic duct (arrowhead). (g) Cut section of gross specimen of distal pancreatectomy shows an oligocystic lesion (arrows), and final pathology confirmed the diagnosis of mucinous cystic neoplasm with low-grade dysplasia. Ovarian stroma is demonstrated on microscopic examination

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19.8.14 Mucinous Cystic Neoplasm with Intermediate-Grade Dysplasia a

b

c

Fig. 19.14 Mucinous cystic neoplasm with intermediate-grade dysplasia in a 30-year-old woman. (a–c) Precontrast axial (a), portal phase coronal (b) CT, and T2-weighted MR (c) images demonstrate a 15 cm large multilocular cystic lesion (arrows) in the tail of the pancreas. The lesion has a smooth outer margin and multiple thick septa and calcifications. (d) On T1-weigthed MRI, the lesion has multicystic locules containing fluid contents with different signal intensities on precontrast

image (upper left). After gadolinium administration, the wall and septa are well enhanced on arterial (upper right), portal (lower left), and delayed (lower right) phase images. (e) Gross specimen obtained after distal pancreatectomy shows a multilocular cystic lesion (arrows) in the pancreas. Final pathologic diagnosis was mucinous cystic neoplasm with intermediate-grade dysplasia

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Cystic Tumors of the Pancreas

d

e

Fig. 19.14 (continued)

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19.8.15 Mucinous Cystic Neoplasm with an Associated Invasive Carcinoma a

b

* *

c

d

*

e

f

*

Fig. 19.15 Mucinous cystic neoplasm with an associated invasive carcinoma in a 47-year-old woman. (a, b) On axial (a) and coronal (b) portal phase CT images, a large lobulating cystic lesion (arrows) is demonstrated in the tail of the pancreas (arrowheads). Note central enhancing solid component (asterisk) within the lesion. (c) On precontrast T1-weighted MRI, the lesion contains fluid with different signal intensities including high signal intensity suggesting hemorrhage. (d–f) Arterial (d), portal (e), and delayed (f) phase MR images also show

*

multicystic nature of the lesion (arrows) in the pancreatic tail (arrowheads). Central enhancing solid portion (asterisk) is also well depicted on MRI. (g) T2-weighted MRI shows multiple fluid-fluid levels within the locules of the lesion (arrows), which suggest intracystic hemorrhage. (h) Gross specimen of distal pancreatectomy reveals a multilocular cystic mass (arrows) in the pancreatic tail, directly invading to the spleen (S). Final pathologic diagnosis was mucinous cystic neoplasm with an associated invasive carcinoma

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g

657

f

s

Fig. 19.15 (continued)

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19.8.16 Solid Pseudopapillary Neoplasm, Cystic a

b

c

d

Fig. 19.16 Solid pseudopapillary neoplasm with cystic degeneration in a 16-year-old man. (a, b) Precontrast axial (a) and portal phase coronal (b) CT images demonstrate a 7 cm cystic mass (arrows) in the tail of the pancreas. (c) On T2-weighted MRI, the lesion (arrows) shows bright high signal intensity with dirty internal debris and irregularly thick wall. (d) On precontrast T1-weighted MRI, the lesion (arrows)

shows bright signal intensity suggesting internal hemorrhage. (e, f) Arterial (e) and portal phase (f) MR images show a peripheral rim-like enhancement of the lesion (arrows). (g) Distal pancreatectomy specimen demonstrates a well-encapsulated mass (arrows) with extensive internal hemorrhage. Final pathology reveals the diagnosis of solid pseudopapillary neoplasm

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Cystic Tumors of the Pancreas

e

g

Fig. 19.16 (continued)

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19.8.17 Pancreatic Neuroendocrine Tumor Grade 1, Cystic a

c

b

Fig. 19.17 Pancreatic neuroendocrine tumor grade 1 with cystic degeneration in a 43-year-old man. (a) On endoscopic US, a 1.5 cm cystic lesion (arrow) with thick wall is noted in the pancreatic tail. (b) Precontrast (left), arterial (middle), and portal (right) phase CT images demonstrate a cystic lesion (arrows) with subtle wall enhancement. (c) T2-weighted MRI clearly depicts the cystic nature of the lesion (arrow).

(d) Precontrast (left), arterial (middle), and portal (right) phase MR images well demonstrate a strong and persistent enhancement of the cyst wall (arrows). (e) Distal pancreatectomy specimen demonstrates a thick-walled cystic lesion (arrows) in the pancreas. Microscopic diagnosis was neuroendocrine tumor grade 1

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d

e

Fig. 19.17 (continued)

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19.8.18 Lymphoepithelial Cyst

Fig. 19.18 Lymphoepithelial cyst in a 52-year-old man. Portal phase coronal CT image shows a multilocular cystic lesion (arrows) with a lobulated margin in the body of the pancreas. The lesion is closely abutting against the pancreas, but the center of the lesion seems to be extrapancreatic. Aspiration biopsy suggests a diagnosis of lymphoepithelial cyst

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19.8.19 Retention Cyst a

b

Fig. 19.19 Retention cyst in a 62-year-old woman. (a, b) Precontrast (left), arterial (middle), and portal (right) phase CT (a) and MR (b) images show a lobulating unilocular cystic lesion (arrows) in the body of the pancreas. No definite enhancing wall or mural nodule is depicted. (c) On T2-weighted coronal MR image, there is no definite communication between the lesion (arrow) and the main pancreatic duct (arrowhead). (d) On three-dimensional transverse US image, however, the

communication between the cystic lesion (asterisk) and the pancreatic duct (arrowhead) is suspected. (e) Microphotograph (original magnification, ×100) obtained after central pancreatectomy reveals that the lesion is lined by single columnar epithelial cells with focal micropapillary cellular projection and mild cytologic atypia. There is no ovarian stroma. Final pathologic diagnosis was retention cyst associated with pancreatic intraepithelial neoplasm (PanIN), grade 1

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*

e

Fig. 19.19 (continued)

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Cystic Tumors of the Pancreas

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19.8.20 Epidermoid Cyst in Intrapancreatic Accessory Spleen c

a

b

* s

s

Fig. 19.20 Epidermoid cyst in intrapancreatic accessory spleen in a 57-year-old woman. (a) Endoscopic US image shows a cystic lesion (arrows) containing internal debris. (b) Precontrast (upper left), arterial (upper right), portal (lower left), and delayed (lower right) CT images demonstrate a cystic lesion (asterisk) at the pancreatic tail. Solid component (arrowheads), which was later revealed to be an intrapancreatic

s

accessory spleen (S), shows the same attenuation to the spleen on all phases. (c) Gross specimen of distal pancreatectomy shows a multiseptated cyst (arrows) in the pancreatic tail. Note rim-like solid component around the cystic lesion, suggesting remnant accessory spleen. Final pathology was epidermoid cyst in intrapancreatic accessory spleen

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Suggested Reading Adsay NV, Conlon KC, Zee SY, et al. Intraductal papillary-mucinous neoplasms of the pancreas: an analysis of in situ and invasive carcinomas in 28 patients. Cancer. 2002;94:62–77. Buerke B, Domagk D, Heindel W, et al. Diagnostic and radiological management of cystic pancreatic lesions: important features for radiologists. Clin Radiol. 2012;67:727–37. Capella C, Solcia E, Kloppel G. Tumours of the exocrine pancreas. In: Hamilton SR, Aaltonen LA, editors. Pathology and genetics of tumours of the digestive system. Lyon: WHO Classification of Tumours/IARC Press; 2000. Goh BK, Tan YM, Chung YF, et al. Non-neoplastic cystic and cysticlike lesions of the pancreas: may mimic pancreatic cystic neoplasms. ANZ J Surg. 2006;76:325–31. Khalid A, Brugge W. ACG practice guidelines for the diagnosis and management of neoplastic pancreatic cysts. Am J Gastroenterol. 2007;102:2339–49.

S.H. Kim Kim SH, Lee JM, Han JK, et al. Intrapancreatic accessory spleen: findings on MR Imaging, CT, US and scintigraphy, and the pathologic analysis. Korean J Radiol. 2008;9:162–74. Kim SY, Lee JM, Kim SH, et al. Macrocystic neoplasms of the pancreas: CT differentiation of serous oligocystic adenoma from mucinous cystadenoma and intraductal papillary mucinous tumor. AJR Am J Roentgenol. 2006;187:1192–8. Kim WH, Lee JY, Park HS, et al. Lymphoepithelial cyst of the pancreas: comparison of CT findings with other pancreatic cystic lesions. Abdom Imaging. 2012. doi:10.1007/s00261-012-9910-6. King JC, Ng TT, White SC, et al. Pancreatic serous cystadenocarcinoma: a case report and review of the literature. J Gastrointest Surg. 2009;13:1864–8. Kosmahl M, Pauser U, Peters K, et al. Cystic neoplasms of the pancreas and tumor-like lesions with cystic features: a review of 418 cases and a classification proposal. Virchows Arch. 2004;445:168–78. Sun HY, Kim SH, Kim MA, et al. CT imaging spectrum of pancreatic serous tumors: based on new pathologic classification. Eur J Radiol. 2010;75:e45–55.

Solid Tumors in the Pancreas

20

Suk Ki Jang and Jung Hoon Kim

Contents 20.1

Ductal Adenocarcinoma . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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20.2

Ductal Adenocarcinoma Variants . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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20.3

Acinar Cell Carcinoma . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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20.4

Pancreatoblastoma . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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20.5

Solid Pseudopapillary Neoplasm (SPN) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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20.6

Pancreatic Neuroendocrine Neoplasms (PNETs) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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20.7

Mesenchymal Tumors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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Lymphoma . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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20.9

Metastasis to the Pancreas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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20.10 Intrapancreatic Accessory Spleen (IPAS) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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20.11 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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20.12 Illustrations: Solid Tumors of the Pancreas. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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Suggested Reading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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S.K. Jang • J.H. Kim (*) Department of Radiology, Seoul National University Hospital, Seoul, Republic of South Korea e-mail: [email protected]; [email protected] B.I. Choi (ed.), Radiology Illustrated: Hepatobiliary and Pancreatic Radiology, Radiology Illustrated, DOI 10.1007/978-3-642-35825-8_20, © Springer-Verlag Berlin Heidelberg 2014

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Table 20.1 Histologic classification of pancreatic solid tumors and tumorlike lesions Epithelial tumors

Ductal adenocarcinoma Ductal adenocarcinoma variants Adenosquamous carcinoma Colloid carcinoma (mucinous noncystic carcinoma) Hepatoid carcinoma Medullary carcinoma Signet-ring-cell carcinoma Undifferentiated carcinoma with osteoclast-like giant cell Acinar cell carcinoma Pancreatoblastoma SPN Neuroendocrine tumor Non-epithelial Mesenchymal tumors tumors Lipoma Lymphangioma Schwannoma Solitary fibrous tumor Perivascular epithelial-cell neoplasm Ewing sarcoma Desmoplastic small-round-cell tumors Lymphoma Metastasis Others IPAS SPN solid pseudopapillary neoplasm, IPAS intrapancreatic accessory spleen

Solid tumors of the pancreas can have a broad spectrum of diseases (Table 20.1). Most pancreatic solid tumors are ductal adenocarcinomas. Each of the other tumors comprises only a small portion of the total number of pancreatic solid tumors, although as these tumors include some of the most treatable pancreatic tumors, their correct diagnosis is extremely important. Most pancreatic solid tumors can be accurately diagnosed using common imaging and clinical findings, although some exceptions occur because of rare tumors or unusual findings regarding common pancreatic tumors. In this situation, an accurate diagnosis can be challenging, and a multimodality imaging approach is, therefore, often helpful. In this chapter, we review tumors of the pancreas in terms of the relevant clinical information and key radiologic features that allow confident lesion characterization and differentiation from other disease entities.

20.1

Ductal Adenocarcinoma

Pancreatic ductal adenocarcinoma is the most common type of malignant pancreatic neoplasm, accounting for over 90 % of all pancreatic tumors. Most patients are old age, and males are more often affected than females. Although pancreatic ductal adenocarcinoma is a common malignancy worldwide,

it still has a poor prognosis. As it is characterized by rapid local growth, it frequently invades surrounding structures and is responsible for the early creation of distant metastases. Surgical resection currently offers the only possibility of a cure or long-term patient survival. However, less than 20 % of patients with pancreatic ductal adenocarcinoma are candidates for radical surgery. Therefore, accurate detection and staging are essential in order to ensure the appropriate selection of patients who will benefit from the surgery and to prevent unnecessary surgeries in patients with unresectable disease.

20.1.1 Common Imaging Findings on CT The most common gross appearance of ductal adenocarcinoma is a focal solid mass without significant necrosis or hemorrhage. It is scirrhous and hypovascular with an associated, marked desmoplastic response as well as local infiltration. Dynamic contrast-enhanced CT is the established technique for evaluating pancreatic ductal adenocarcinoma. Arterial phase imaging performed 20–40 s after contrast agent injection allows optimal visualization of the tumor and peripancreatic arteries. Maximum contrast between the hypoattenuating tumor and the normal pancreas yields optimal tumor conspicuity in the arterial phase. Portal phase imaging performed 55–70 s after injection is optimal for detecting metastatic disease to the liver and for assessing the peripancreatic veins. The CT findings depend on the tumor location. The presence and location of a mass may be inferred from secondary signs such as the mass effect, dilatation of the bile duct and/ or pancreatic duct, and vascular invasion. Tumors in the pancreatic head may cause dilatation of both the bile duct and the pancreatic duct and with atrophy of the upstream pancreas, whereas tumors in the pancreatic body may cause upstream pancreatic duct dilatation with atrophy of the pancreas. Occasionally, tumors in the pancreatic head may cause dilatation of the bile duct without dilatation of the pancreatic duct. Tumors in the pancreatic tail and uncinate appear only as a hypoattenuating mass without dilatation of the pancreatic duct. Cystic–necrotic degeneration, an uncommon feature of ductal adenocarcinoma, is present in some of these patients. Vascular invasion of the superior mesenteric artery, superior mesenteric vein, celiac artery, and portal vein was estimated using the tumor-to-vessel contiguity defined as direct tumor-to-vessel contact in more than 50 % of the vessel circumference and with complete obliteration of the fat plane. Other features suggesting vascular invasion include vessel deformity, thrombosis, and the development of collateral vessels. The “teardrop sign” refers to an alteration of the superior mesenteric vein from its normally round shape to a teardrop shape seen on axial images and secondary to tumor infiltration or peritumoral fibrosis.

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20.1.2 Image Findings on MRI No pancreatic mass is visualized in some patients as the tumor may appear as isoattenuating on CT. In this condition, MRI is helpful for making the correct diagnosis of pancreatic cancer. Owing to the desmoplastic nature of ductal adenocarcinoma, the signal intensity of the tumor is slightly reduced compared with that of normal pancreatic tissue on conventional and fat-suppressed, T1-weighted images. The signal intensity varies on T2-weighted images depending on the degree of desmoplastic reaction, hemorrhage, necrosis, and associated inflammatory change. Dynamic gadolinium-enhanced MR imaging can further aid in the identification of tumor foci by increasing the conspicuity of the non-enhancing tumor relative to the normally enhancing pancreas, as seen on early post-contrast images. MR imaging is superior for detecting small tumors and metastases.

20.2

Ductal Adenocarcinoma Variants

Ductal adenocarcinoma variants include neoplasms characterized by a specific histologic pattern different from that of conventional pancreatic ductal adenocarcinoma. It has been estimated that these variants account for less than 10 % of all pancreatic ductal adenocarcinomas.

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correct diagnosis based on the preoperative images. The imaging features of the other ductal adenocarcinoma variants, including hepatoid carcinoma, medullary carcinoma, signetring-cell carcinoma, and undifferentiated carcinoma with osteoclast-like giant cells, have been less well characterized.

20.3

Acinar Cell Carcinoma

Acinar cell carcinoma is a very rare malignant tumor. Although most pancreatic cancers are not metabolically active, acinar cell carcinoma may systemically secrete pancreatic enzymes, resulting in subcutaneous fat necrosis and lytic bone lesions. The pathogenesis of fat necrosis is still unknown, although it is believed to be associated with high levels of serum lipase produced by the neoplasm, and thus causing fat necrosis in tissue. Acinar cell carcinomas are solid tumors which are typically larger than adenocarcinomas. Frequently encapsulated, acinar cell carcinomas have moderate vascularity. They are not usually hemorrhagic, but may have central necrosis. MR imaging shows a welldelineated, nonspecific mass that is hypo- or isointense to normal pancreatic tissue on T1-weighted images and slightly hyperintense on T2-weighted images. Central necrosis may result in high signal intensity on T2-weighted images and low signal intensity on T1-weighted images. Because the lesions are not hypervascular, the use of gadolinium enhancement would be helpful only for differentiating normally enhancing pancreatic tissue from non-enhancing tumor.

20.2.1 Colloid Carcinoma One of most characteristic variants of pancreatic ductal adenocarcinoma is colloid carcinoma. Colloid carcinomas, also called mucinous noncystic adenocarcinomas, are a distinct subtype of pancreatic adenocarcinoma with unique histologic and clinical characteristics that distinguish this subtype from ordinary ductal adenocarcinoma. Pathologically, colloid carcinomas of the pancreas are characterized by dissecting lakes of abundant stromal mucin with a scant amount of malignant cells floating in the center, and they have a better prognosis than ductal adenocarcinoma. Colloid carcinomas of the pancreas show very high signal intensity on T2-weighted images and various signal intensities on T1-weighted images. On dynamic imaging, they showed progressive, delayed, peripheral, and internal spongelike or mesh-like enhancement of the intervening stroma and poorly enhancing mucin pools.

20.2.2 Adenosquamous Carcinoma Adenosquamous carcinoma is characterized by mucinproducing glandular elements and an admixed squamous component. A cytologic diagnosis of malignancy is usually straightforward, although it may be difficult to make a

20.4

Pancreatoblastoma

Pancreatoblastoma is the most common pancreatic tumor seen in young children. Most patients are between 1 and 8 years of age. Pancreatoblastoma has a predilection for male patients. The serum a-fetoprotein level is elevated in one in four cases. It is typically slow-growing and generally manifests as an asymptomatic large mass. Metastases may occur in the liver, lymph nodes, lung, bone, posterior mediastinum, peritoneum, and omentum. In some cases, pancreatoblastoma may appear as a circumscribed, lobulated mass with solid and cystic components or calcification. Despite its size, this tumor rarely causes biliary or duodenal obstruction as it has a soft, gelatinous consistency. Arterial encasement and venous invasion have been observed. On US, the mass appears heterogeneous with hypoechoic cystic spaces and intervening hyperechoic internal septa. Occasionally, a hypoechoic solid mass is seen. On CT, pancreatoblastoma generally manifests as a multiloculated, inhomogeneous mass with enhancing septa. Calcifications have a rim-like or clustered configuration. The tumor has low to intermediate signal intensity on T1-weighted MR images and high signal intensity on T2-weighted images, and it shows mild contrast enhancement.

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20.5

S.K. Jang and J.H. Kim

Solid Pseudopapillary Neoplasm (SPN)

SPN is a rare pancreatic tumor. It is most common in females and young adults. It most commonly occurs in the pancreatic tail, followed closely appearance by the pancreatic head. The lesions are considered to have low-grade malignant potential, and the treatment of choice is resection. SPN is typically a large, slow-growing, well-encapsulated mass. SPN has a tendency to displace rather than to invade surrounding structures and rarely causes obstruction of the bile duct or pancreatic duct. On gross examination, this large tumor is typically solid with cystic areas. It has a thick, fibrous capsule, and, with increasing size, necrosis and cystic degeneration are seen. The solid areas consist of sheets of epithelial cells, whereas the papillary regions consist of a fibrovascular core lined with cuboidal or columnar epithelial cells. Typical SPN appears as a round, encapsulated mass with variably attenuating components including varying amounts of necrosis, hemorrhage, and cystic changes. The lesions demonstrate peripheral heterogeneous enhancement during the arterial phase and progressive nonuniform enhancement thereafter, with enhancement generally being less than that of the normal pancreas. Peripheral calcifications can also be seen. The presence of cystic regions within the mass is the result of hemorrhagic necrosis. The pseudocapsule, composed of compressed pancreatic tissue and reactive fibrosis, has low attenuation on CT and low signal intensity on T1and T2-weighted MR imaging. Internal hemorrhagic and cystic degeneration is the hallmark of SPN due to the fragile vascular network of the tumor. These imaging features are best seen on MR imaging. Subacute hemorrhage may appear hyperintense on T1-weighted images and has variable signal intensity on T2-weighted images, whereas chronic hemorrhage is hypointense on both sequences. A fluid–fluid or fluid–debris level and peripheral calcification are detected in some of the cases.

20.6

neurofibromatosis type 1. They are classified as functioning or nonfunctioning according to their associated clinical symptoms, and insulinoma, gastrinoma, and glucagonoma are the most common functioning PNETs. PNETs are also classified according to the number of the mitotic count and the percentage of the Ki67 index: NET grade 1 (mitotic count 20 % Ki-67 index). On imaging, PNETs typically appear as well-defined, hypervascular masses, a finding indicative of their rich capillary network. Cystic change, calcification, and necrosis are common in large tumors which are associated with a poorer prognosis and a higher prevalence of local and vascular invasion and metastases than smaller tumors. The frequency of metastatic disease at the time of diagnosis has been reported to be as high as 60–80 %. Even when metastases are present, many well-differentiated PNETs have an indolent course. NECs are rare and have an infiltrative appearance; patients with such tumors have a poor prognosis. NEC may show features of local spread, vascular invasion, lymph node involvement, and organ metastases. On MR imaging, PNETs generally have low signal intensity on T1-weighted images and intermediate to high signal intensity on T2-weighted images. PNETs have a rich vascular supply and therefore enhance substantially during the arterial phase, thus enhancing more rapidly and intensely than the normal pancreas. Homogeneous enhancement is typical for small tumors, whereas larger lesions tend to show heterogeneous enhancement which can be ringlike. During the portal phase, tumors may be either hyper-, iso-, or hypoenhancing relative to the normal pancreas. Some tumors demonstrate atypical delayed enhancement and are best seen on portal phase imaging. Metastases to lymph nodes and solid organs, such as the liver, may have an enhancement pattern similar to that of the primary tumor. It is important to differentiate PNETs from other tumors of the pancreas, particularly adenocarcinoma, as the prognoses and treatment options differ.

Pancreatic Neuroendocrine Neoplasms (PNETs) 20.7

PNET is traditionally considered as a rare disease. However, in recent years the diagnosed incidence of PNET has increased due to improved detection methods. PNETs constitute a heterogeneous group of tumors that originate from neuroendocrine cells and which have significant behavioral differences. PNETs occur with an equal frequency in men and women. PNETs are found with equal frequency throughout the pancreas. Most are sporadic, although some are associated with familial syndromes such as multiple endocrine neoplasia type 1, von Hippel–Lindau syndrome, and

Mesenchymal Tumors

Although the great majority of pancreatic neoplasms arise from pancreatic epithelial cells, mesenchymal tumors, while rare, can be derived from non-epithelial cells, including the connective, lymphatic, vascular, and neuronal tissue of the pancreas. Mesenchymal tumors are classified according to their histologic origin, including lipoma, schwannoma, solitary fibrous tumor, perivascular epithelial-cell neoplasm, sarcoma, desmoplastic small-round-cell tumors, and lymphangioma.

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Solid Tumors in the Pancreas

20.7.1 Lipoma In some cases, cross-sectional imaging can offer a specific diagnosis of mesenchymal tumors. Lipomas of the pancreas are very rare. CT findings for a pancreatic lipoma include homogenous distribution of fat density with no central or peripheral contrast enhancement, Hounsfield units of −80 to −120, and a sharp demarcation with no evidence of intra- and extrapancreatic adjacent structure infiltration. Other than lipoma of the pancreas, fatty lesions in the pancreas include focal fatty infiltration of the pancreas, teratoma, and liposarcoma. A probable diagnosis of lipoma can be made if a lesion is purely fat, contains no solid areas, and is small. Most researchers believe that histology is not absolutely necessary in order to confirm the diagnosis of pancreatic lipoma because radiologic features are nearly diagnostic. However, a well-differentiated lipogenic liposarcoma can mimic a benign lesion due to the homogeneity of fat and the sharply defined margins seen on imaging.

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There are two morphologic patterns of pancreatic lymphoma, i.e., a focal well-circumscribed form and a diffuse form. The lymphomatous structure is typically homogeneous, hypodense, and hypovascular. Necrotic or hemorrhagic changes are rare, and calcifications are usually rare. Biliary ductal dilatation is a less frequent complication than that seen in epithelial neoplasms. Secondary pancreatitis is uncommon. It typically has uniform low attenuation on CT. On MR imaging, it has low signal intensity on T1-weighted images and slightly higher signal intensity than the pancreas on T2-weighted images; it also shows obscure contrast enhancement. The diffuse form is infiltrative, leading to glandular enlargement and poor definition, features which can simulate the appearance of acute pancreatitis. This form has low signal intensity on T1- and T2-weighted MR images and shows homogeneous contrast enhancement, although there are sometimes small foci of reduced or absent enhancement.

20.9

Metastasis to the Pancreas

20.7.2 Schwannoma Pancreatic schwannoma is a rare neoplasm that originates from Schwann cells. Schwannomas are neurogenic neoplasms derived from Schwann cells of the sheaths of the peripheral nerves. Schwannomas often contain various patterns of solid and cystic components within a tumor. The preoperative diagnosis of a pancreatic schwannoma is difficult to make, and they are often confused with other pancreatic tumors such as endocrine tumors, solid pseudopapillary neoplasms, and mucinous cystic neoplasms. The most characteristic CT feature is the presence of a low-density and/or cystic portion within the tumor. The MRI findings usually showed hypointensity on T1-weighted images and hyperintensity on T2-weighted images, and most tumors were gradually enhanced on T1-weighted images after Gd-DTPA administration.

20.8

Lymphoma

Pancreatic lymphoma is most commonly a B-cell subtype of non-Hodgkin’s lymphoma and is classified as either primary or secondary. Secondary lymphoma is the dominant form and results from direct extension from peripancreatic lymphadenopathy. Primary pancreatic lymphoma is rare. It is more common in middle-aged patients and in immunocompromised patients. As pancreatic lymphoma can potentially be cured, it is important to initially make a correct diagnosis. Primary pancreatic lymphoma is often bulky and encases the vasculature but does not occlude it. Ductal dilatation and cystic changes are rare.

Metastasis to the pancreas is an uncommon occurrence accounting. Metastases to the pancreas are most frequently from renal cell carcinoma (RCC) and lung carcinoma, followed by breast carcinoma, colorectal carcinoma, and melanoma, and most of these patients are asymptomatic. The prognosis is generally more favorable than that for pancreatic adenocarcinoma. Surgery is an option for patients who have had a long, disease-free interval between the resection of their primary carcinoma and the development of pancreatic metastases or whose metastases are confined to the pancreas. There are three, morphologic patterns of involvement: solitary, multifocal, and diffuse. The solitary form is generally well marginated. Masses may be hypo- or hyperechoic on US and hypo- or isoattenuating on unenhanced CT. Cystic masses have also been reported. Metastases typically have low signal intensity on T1-weighted MR images and high signal intensity on T2-weighted images. On contrastenhanced CT and MR imaging, the appearance of pancreatic metastases closely resemble that of primary carcinoma. Pancreatic metastases show either peripheral enhancement or homogeneous enhancement, and these features are related to the lesions’ blood supply. Metastases from RCC are generally well-defined, hypervascular lesions with a central, hypoenhancing necrotic portion with poor perfusion. The primary differential consideration for pancreatic metastases from hypervascular primary tumors such as RCC is the PNET as the imaging appearance of these two entities can be very similar, and both manifest as hypervascular discrete masses which can exhibit cystic–necrotic degeneration. However, hypovascular metastases from the lung, breast, and

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colon are common, and the main differential consideration regarding these lesions is pancreatic adenocarcinoma. In most cases, a past medical history of malignancy allows the correct diagnosis.

S.K. Jang and J.H. Kim

3.

4.

20.10 Intrapancreatic Accessory Spleen (IPAS) IPAS is a benign lesion, although its appearance can be confused with that of true pancreatic neoplasms, particularly PNET or SPN. Pancreatic tail is the common location of accessory spleen. It is typically a small, well-defined, ovoid mass situated in the pancreatic tail and with characteristics similar to those of the spleen on unenhanced and contrastenhanced imaging. Because the spleen generally appears denser than the pancreas on all dynamic CT phases, IPAS generally shows greater enhancement than the pancreas. Relative to the pancreas, IPAS has lower signal intensity on T1-weighted MR images and higher signal intensity on T2-weighted images. The characteristic zebra-striped, splenic enhancement pattern seen during the arterial phase is also seen in IPAS. This is a useful criterion for differentiating IPAS from hypervascular neoplasms such as NETs and metastases. A definitive diagnosis is made with scintigraphy using either technetium 99 m (99 mTc)-labeled damaged red blood cells or technetium 99 mTc–sulfur colloid.

5. 6.

7.

8.

9.

10.

20.11 Summary 11. 1. Pancreatic ductal adenocarcinoma is the most common type of malignant pancreatic neoplasm, accounting for over 90 % of all pancreatic tumors. 2. The CT findings of pancreatic ductal adenocarcinoma depend on the tumor location, and MRI is helpful for

12.

making the correct diagnosis of isoattenuating pancreatic cancer on CT. Vascular invasion is defined as direct tumor-to-vessel contact in more than 50 % of the vessel circumference and with complete obliteration of the fat plane. Colloid carcinomas, also called mucinous noncystic adenocarcinomas, of the pancreas show very high signal intensity on T2-weighted images and progressive, delayed, and internal spongelike or mesh-like enhancement. Acinar cell carcinoma may systemically secrete pancreatic enzymes, resulting in subcutaneous fat necrosis. Solid pseudopapillary neoplasm is typically a round, encapsulated mass with variably attenuating components including varying amounts of necrosis, hemorrhage, and cystic changes. Pancreatic neuroendocrine neoplasms are classified as functioning or nonfunctioning according to their associated clinical symptoms and three grades according to the number of the mitotic count and the percentage of the Ki67 index. Pancreatic neuroendocrine neoplasms typically appear as well-defined, hypervascular masses with cystic change, calcification, and necrosis. Pancreatic lipoma typically appears as homogenous distribution of fat density, Hounsfield units of −80 to −120, and a sharp demarcation with no evidence of adjacent structure infiltration. Pancreatic lymphoma is typically homogeneous, hypodense, and hypovascular without calcifications, necrosis, and hemorrhage. Metastases to the pancreas are most frequently from renal cell carcinoma, and it shows well-defined hypervascular lesions. Intrapancreatic accessory spleen is a benign lesion, although its appearance can be confused with that of true pancreatic neoplasms, particularly PNET or SPN.

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20.12 Illustrations: Solid Tumors of the Pancreas 20.12.1 Schematic Diagrams of Pancreatic Ductal Adenocarcinoma According to Its Location

a

b

c

d

e

Fig. 20.1 Schematic diagrams of pancreatic ductal adenocarcinoma according to its location. (a) Pancreatic ductal adenocarcinoma of the head shows dilatation of both bile duct and pancreatic duct (doubleduct sign) with atrophy of the upstream pancreas. (b) Pancreatic ductal adenocarcinoma of the body shows upstream pancreatic duct dilatation

with atrophy of the pancreas. (c, d) Pancreatic ductal adenocarcinoma of the tail and uncinate shows only mass without dilatation of bile duct or pancreatic duct. (e) Pancreatic ductal adenocarcinoma of the head shows dilatation of the bile duct without dilatation of pancreatic duct

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20.12.2 Pancreatic Ductal Adenocarcinoma of the Head a

b

c

d

e

f

Fig. 20.2 Pancreatic ductal adenocarcinoma of the head. (a, b) Portal phase axial CT images demonstrate a hypoattenuating mass in the head (arrows) and dilatation of pancreatic duct (arrowheads). (c) MR cholangiopancreatography clearly depicts dilatation of both bile duct and pancreatic duct (double-duct sign). (d, e) Precontrast axial (d) and portal (e) phase coronal T1-weighted MR images depict the hypo-signal

intensity mass in the head (arrowheads). After gadolinium administration, this mass is mildly enhanced on portal phase (arrowheads) with dilatation of pancreatic duct (arrow). (f) Cut section of specimen from pylorus-preserving pancreaticoduodenectomy shows ill-defined scirrhous carcinoma of the head of the pancreas (arrows)

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20.12.3 Pancreatic Ductal Adenocarcinoma of the Uncinate: Unresectable Case a

b

c

d

Fig. 20.3 Unresectable pancreatic ductal adenocarcinoma of the uncinate. (a, b) Pancreatic phase axial CT images demonstrate a hypoattenuating mass in the pancreatic uncinate (arrowheads) and direct invasion of the superior mesenteric artery and superior mesenteric vein (arrows). CT images demonstrate direct tumor-to-vessel contact more

than 50 % of the vessel circumference with complete obliteration of the fat plane. (c) Portal phase coronal CT image demonstrates the tumor encasing the superior mesenteric artery (arrowheads). (d) On endoscopic US, a low echoic mass (arrows) is noted in the pancreatic uncinate

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20.12.4 Pancreatic Ductal Adenocarcinoma of the Tail a

b

c

d

e

Fig. 20.4 Pancreatic ductal adenocarcinoma of the tail. (a, b) Pancreatic (a) and portal (b) phase axial CT images demonstrate a hypoattenuating mass in the pancreatic tail (arrows) without pancreatic duct dilatation. (c, d) Precontrast (c) and arterial (d) phase MR images

well demonstrate the hypointense mass in the pancreatic tail (arrows). (e) Cut section of specimen from distal pancreatectomy shows yellow to white carcinoma of the tail of the pancreas

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20.12.5 Pancreatic Ductal Adenocarcinoma with Bile Duct Dilatation a

b

c

d

e

Fig. 20.5 Pancreatic ductal adenocarcinoma with bile duct dilatation. (a) Pancreatic phase axial CT image demonstrates a hypoattenuating mass in the head (arrowheads). (b) MR cholangiopancreatography clearly depicts dilatation of bile duct due to pancreatic head mass (arrow) without dilatation of pancreatic duct. The tumors in the pancreatic head may cause dilatation of the bile duct without dilatation of

pancreatic duct. (c, d) Precontrast axial (c) and portal (d) phase coronal T1-weighted MR images depict the hypo-signal intensity mass in the head (arrowheads). After gadolinium administration, this mass is mildly enhanced on portal phase (arrowheads). (e) Cut section of specimen shows white scirrhous carcinoma of the head of the pancreas (arrows)

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20.12.6 Pancreatic Ductal Adenocarcinoma of the Body: Isoattenuating Tumor a

b

c

d

e

Fig. 20.6 Isoattenuating pancreatic ductal adenocarcinoma of the body. (a, b) Coronal curved reformatted pancreatic phase (a) and portal phase (b) CT images show dilated pancreatic duct (arrowheads); however pancreatic mass is not visualized in the CT. (c) Precontrast T1-weighted MR image well demonstrate the hypo-signal intensity mass in the pancreatic head (arrowheads). (d) T2-weighted MR image

also shows slightly hyper-signal intensity mass in the pancreatic head (arrowheads). In this case, MRI is helpful for correct diagnosis for pancreatic cancer. (e) Cut section of specimen from pylorus-preserving pancreaticoduodenectomy shows poorly defined white scirrhous carcinoma in the head of the pancreas (arrows)

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Solid Tumors in the Pancreas

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20.12.7 Pancreatic Ductal Adenocarcinoma with Cystic Lesions

a

b

c

Fig. 20.7 Pancreatic ductal adenocarcinoma with cystic lesions. (a, b) Pancreatic phase axial CT images demonstrate a hypoattenuating mass in the pancreatic body (arrows). Mass is extending to retropancreatic area and directly invading of the celiac artery (arrows). The upstream

main pancreatic duct is also dilated (arrowheads). (c) Portal phase coronal CT image demonstrates two cystic lesions in the superior portion of pancreatic ductal adenocarcinoma (arrows). Cysts can be combined in some cases of pancreatic ductal adenocarcinoma

680

S.K. Jang and J.H. Kim

20.12.8 Pancreatic Ductal Adenocarcinoma of the Tail with Multiple Metastases a

b

c

Fig. 20.8 Pancreatic ductal adenocarcinoma of the tail with multiple metastases. (a) Pancreatic phase axial CT image demonstrates a large hypoattenuating mass in the pancreatic tail (arrows). Multiple hepatic metastases are noted (arrowheads). (b) Pancreatic phase coronal CT image demonstrates mass direct invasion of the celiac artery and

superior mesenteric artery (arrowheads). (c) Pancreatic phase coronal CT image demonstrates multiple metastatic nodules in the mesentery (arrowheads) and small amount of ascites (arrows). These findings suggest peritoneal seeding of the pancreatic ductal adenocarcinoma

20

Solid Tumors in the Pancreas

681

20.12.9 Pancreatic Ductal Adenocarcinoma Variants: Colloid Carcinomas (Mucinous Noncystic Adenocarcinomas) a

b

c

d

e

Fig. 20.9 Pancreatic ductal adenocarcinoma variants: colloid carcinomas (mucinous noncystic adenocarcinomas). (a) Coronal curved reformatted pancreatic phase CT image shows a hypoattenuating mass in the head (arrows) with small calcifications (arrowhead). (b) MR cholangiopancreatography clearly depicts dilatation of bile duct and pancreatic duct due to pancreatic head mass. (c) T2-weighted coronal MR image shows high signal intensity mass (arrows) with small hypointense foci

(arrowheads) in the pancreatic head. Diffuse dilatation of pancreatic duct is also noted. (d) Portal phase coronal T1-weighted MR image depicts peripheral and internal mesh-like enhancement (arrows). (e) Cut section of specimen shows large well-demarcated mass of the pancreas of the head (arrows), which shows the glistening cut surface due to extracellular stromal mucin pool containing suspended neoplastic cells

682

S.K. Jang and J.H. Kim

20.12.10 Pancreatic Ductal Adenocarcinoma Variants: Adenosquamous Carcinoma a

b

c

d

e

Fig. 20.10 Pancreatic ductal adenocarcinoma variants: adenosquamous carcinoma. (a) Pancreatic phase axial CT image demonstrates a hypoattenuating mass in the pancreatic head (arrows). CT image demonstrates direct tumor-to-superior mesenteric vein contact almost 50 % of the vessel circumference with obliteration of the fat plane (arrowhead). (b) T2-weighted MR image also shows slightly hyper-signal intensity mass in the pancreatic head (arrows). (c, d) Precontrast axial (c) and portal (d) phase axial T1-weighted MR images depict the

hypo-signal intensity mass in the head (arrows). After gadolinium administration, this mass is well enhanced on portal phase (arrows). MR demonstrates tumor direct invasion of the superior mesenteric vein (arrowhead). (e) Cut section of specimen shows well-defined white mass in the head of the pancreas (arrows). He underwent segmental resection of the SMV and anastomosis due to direct invasion form the pancreatic adenosquamous carcinoma

20

Solid Tumors in the Pancreas

683

20.12.11 Pancreatic Ductal Adenocarcinoma Variants: Undifferentiated Carcinoma with Osteoclast-Like Giant Cells a

b

c

d

Fig. 20.11 Pancreatic ductal adenocarcinoma variants: undifferentiated carcinoma with osteoclast-like giant cells. (a, b) Pancreatic (a) phase axial and portal (b) phase coronal CT images demonstrate a heterogeneously enhancing hypoattenuating mass in the head of pancreas (arrows). (c) MR cholangiopancreatography depicts mild dilatation of bile duct and pancreatic duct due to pancreatic head mass. (d) T2-weighted coronal MR image shows a heterogeneous slightly high signal intensity mass (arrowheads) in the pancreatic head. (e, f)

Precontrast axial (e) and portal (f) phase coronal T1-weighted MR images depict the heterogeneous slightly hyper-signal intensity mass in the head (arrows). After gadolinium administration, this mass is mild enhanced on portal phase (arrowheads). (g) Endoscopic US clearly demonstrates the solid mass with internal cystic changes (arrows). (h) Cut section of specimen shows well-defined yellow to white mass in the head of the pancreas (arrows) containing large portion of hemorrhage and necrosis (arrowheads)

684

S.K. Jang and J.H. Kim

e

f

g

h

Fig. 20.11 (continued)

20

Solid Tumors in the Pancreas

685

20.12.12 Acinar Cell Carcinoma a

b

c

d

e

f

Fig. 20.12 Acinar cell carcinoma. (a) Pancreatic phase axial CT image demonstrates a mild enhancing mass in the head of pancreas (arrows). (b) MR cholangiopancreatography depicts dilatation of both bile duct and pancreatic duct (double-duct sign) due to pancreatic head mass (arrows). (c) T2-weighted axial MR image shows a heterogeneous slightly hyper-signal intensity mass (arrows) in the pancreatic

head. (d, e, f) Precontrast (d), arterial (e), and portal (f) phase axial T1-weighted MR images depict the hypo-signal intensity mass in the head (arrows). After gadolinium administration, this mass is mild enhanced on arterial and portal phase (arrows). (g) Cut section of specimen shows well-defined white mass in the head of the pancreas (arrows) containing small portion of hemorrhage and necrosis (arrowheads)

686

g

Fig. 20.12 (continued)

S.K. Jang and J.H. Kim

20

Solid Tumors in the Pancreas

687

20.12.13 Pancreatoblastoma a

b

c

d

Fig. 20.13 Pancreatoblastoma. (a) Transabdominal US image demonstrates mass in the pancreas (arrows) with small calcifications (arrowhead). (b) Transabdominal US image shows large hypoechoic masses in the right lobe of the liver (arrows). (c, d) Portal phase axial CT

images demonstrate a heterogeneous enhancing large mass in the body and tail of pancreas (arrows). Multiple hepatic metastases are noted (arrowheads)

688

S.K. Jang and J.H. Kim

20.12.14 Solid Pseudopapillary Neoplasm a

b

c

d

e

f

Fig. 20.14 Solid pseudopapillary neoplasm. (a, b) Coronal curved reformatted pancreatic (a) phase and portal (b) phase coronal CT images demonstrate a mild enhancing mass in the head of pancreas. This mass shows a peripheral rim-like enhancement (arrows). Pancreatic duct dilation is not noted. (c) T2-weighted axial MR image shows hyper-signal intensity mass (arrows) in the pancreatic head. (d, e) Precontrast (d) and portal (e) phase axial T1-weighted MR

images depict the hypo-signal intensity mass in the head (arrows). After gadolinium administration, this mass is mildly enhanced on portal phase (arrows). (f) Cut section of specimen from pylorus-preserving pancreaticoduodenectomy shows well-demarcated mass (arrows) in the head of pancreas. The mass contains brown to yellow solid area and zone of hemorrhage and necrosis (arrowheads)

20

Solid Tumors in the Pancreas

689

20.12.15 Solid Pseudopapillary Neoplasm in a Male Patient a

b

c

d

e

∗

Fig. 20.15 Solid pseudopapillary neoplasm in a male patient. (a–c) Precontrast (a), pancreatic (b), and portal (c) phase axial CT images depict the hypoattenuating mass in the head of pancreas (arrows) with calcifications (arrowhead). After enhancement, this mass shows a peripheral rim-like enhancement (arrows). Pancreatic duct dilation is

not noted. (d) Endoscopic US clearly demonstrates the low echoic mass in the head of pancreas (arrows) with calcifications (arrowhead). (e) Cut section of specimen shows well-demarcated yellow to white mass in the head of pancreas. The mass contains hemorrhage portions (arrowheads) and cystic degeneration area (asterisk)

690

S.K. Jang and J.H. Kim

20.12.16 Pancreatic Neuroendocrine Neoplasm in von Hippel–Lindau Disease a

b

c

d

e

f

∗

Fig. 20.16 Pancreatic neuroendocrine neoplasm in von Hippel–Lindau disease. (a, b) Coronal curved reformatted pancreatic (a) phase and portal (b) phase CT images demonstrate a small well-enhancing nodule in the head of pancreas (arrows) with cystic change in the center of nodule (arrowhead). (c) MR cholangiopancreatography depicts entire pancreas is replaced by numerous cystic lesions (arrows). (d, e)

Precontrast (d) and arterial (e) phase axial T1-weighted MR images depict the hypo-signal intensity mass in the head of pancreas (arrowheads). After gadolinium administration, this nodule is well enhanced on arterial phase (arrowheads). (f) Cut section of specimen shows welldefined yellow nodule in the head of pancreas (arrows) containing small portion of cystic degeneration (asterisk)

20

Solid Tumors in the Pancreas

691

20.12.17 Pancreatic Neuroendocrine Neoplasm: Insulinoma a

b

c

d

e

f

Fig. 20.17 Pancreatic neuroendocrine neoplasm: insulinoma. He had a history of symptoms of hypoglycemia including headache, irritability, and dizziness. (a, b) Pancreatic (a) and portal (b) phase axial CT images demonstrate a small well-enhancing nodule in the head of pancreas (arrowheads). (c) T2-weighted axial MR image shows high signal intensity mass (arrows) with small cystic changes (arrowhead). (d–f)

Precontrast (d), arterial (e), and portal (f) phase axial T1-weighted MR images depict the hypo-signal intensity mass in the head of pancreas (arrowheads). After gadolinium administration, this mass is well enhanced (arrowheads). (g) Cut section of specimen shows welldemarcated brown to yellow solid mass in the head of pancreas (arrows) with small cystic degeneration (arrowhead)

692

g

Fig. 20.17 (continued)

S.K. Jang and J.H. Kim

20

Solid Tumors in the Pancreas

693

20.12.18 Pancreatic Neuroendocrine Neoplasm: Grade 2 with Cystic Change a

b

*

*

d

c

*

Fig. 20.18 Pancreatic neuroendocrine neoplasm: grade 2 with cystic change. (a, b) Coronal curved reformatted pancreatic (a) phase and portal (b) phase CT images demonstrate a well-circumscribed strongly enhancing mass in the head of pancreas (arrows) with large cystic change in the center of mass (asterisk). (c) Endoscopic US clearly

*

demonstrates the solid mass in the head of pancreas (arrows). There is large cystic lesion (asterisk) and some debris in the center of mass. (d) Cut section of specimen shows well-demarcated yellow solid mass with large cystic degeneration in the center of mass (asterisk)

694

S.K. Jang and J.H. Kim

20.12.19 Pancreatic Neuroendocrine Carcinoma with Hepatic Metastases a

b

c

d

Fig. 20.19 Pancreatic neuroendocrine carcinoma with hepatic metastases. (a–c) pancreatic (a, b) phase axial and portal (c) phase coronal CT images demonstrate a hypoattenuating mass in the head of pancreas (arrows). Multiple hepatic metastases are noted (arrowheads). (d) FDG-PET scan demonstrates a pancreatic mass with intense FDG uptake (arrow). Hepatic metastases also show intense

FDG uptake (arrowheads). (e, f) Portal (e) and hepatobiliary (f) phase axial T1-weighted MR images after gadoxetic acid administration depict well-enhancing mass in the pancreatic head (arrows) and multiple hepatic metastases (arrows). (g) Diffusion-weighted image (b-800 s/mm2) shows multiple hepatic metastases with hyper-signal intensity (arrows)

20

Solid Tumors in the Pancreas

e

g

Fig. 20.19 (continued)

695

f

696

S.K. Jang and J.H. Kim

20.12.20 Pancreatic Lipoma

a

b

Fig. 20.20 Pancreatic lipoma. (a, b) Precontrast (a) axial and portal (b) phase coronal CT images demonstrate a well-demarcated mass in the head of pancreas (arrows) with homogenous distribution of fat density. There is no definite enhancement. This mass measures −110 Hounsfield units

20

Solid Tumors in the Pancreas

697

20.12.21 Pancreatic Schwannoma a

b

c

d

e

f

Fig. 20.21 Pancreatic schwannoma. (a) Pancreatic phase axial CT image demonstrates a mildly enhancing mass in the head of pancreas (arrows). (b) T2-weighted axial MR image shows hyper-signal intensity mass in the head of pancreas (arrows). (c, d) Precontrast (c) and portal (d) phase axial T1-weighted MR images depict the hypo-signal

intensity mass in the head (arrows). After gadolinium administration, this mass is mildly enhanced (arrows). (e) Endoscopic US clearly demonstrates the solid mass (arrows) with internal small cystic lesions (arrowhead) in the head of pancreas. (f) Cut section of specimen shows well-defined white to yellow mass in the head of the pancreas (arrows)

698

S.K. Jang and J.H. Kim

20.12.22 Pancreatic Lymphoma a

b

c

d

e

f

Fig. 20.22 Pancreatic lymphoma. (a, b) Coronal pancreatic (a) phase and portal (b) phase CT images demonstrate diffuse mass-like enlargement of pancreas head (arrows). Patent gastroduodenal artery is noted (arrowhead). (c) T2-weighted axial MR image shows hyper-signal intensity mass in the head of pancreas (arrows). (d) T1-weighted MR

images depict the hypo-signal intensity mass in the head of pancreas (arrows). (e) Endoscopic US clearly demonstrates the homogeneous slightly low echoic mass in the head of pancreas (arrows). (f) FDGPET scan demonstrates multiple intense FDG uptakes in the entire body

20

Solid Tumors in the Pancreas

699

20.12.23 Metastasis to the Pancreas from Renal Cell Carcinoma

a

b

c

Fig. 20.23 Metastasis to the pancreas from renal cell carcinoma. The patients had a history of right nephrectomy due to renal cell carcinoma. (a, b) Coronal curved reformatted pancreatic (a) phase and portal (b) phase CT images demonstrate a well-circumscribed strongly enhancing

mass in the head of pancreas (arrows) with mild pancreatic duct dilatation due to extrinsic compression. (c) Cut section of specimen shows well-demarcated yellow to white solid mass in the head of pancreas. There is no definite pancreatic duct invasion

700

S.K. Jang and J.H. Kim

20.12.24 Intrapancreatic Accessory Spleen

a

b

c

Fig. 20.24 Intrapancreatic accessory spleen. (a, b) Axial pancreatic (a) phase and portal (b) phase CT images demonstrate well-defined mass in the pancreatic tail (arrows). This mass shows heterogeneous enhancement on the pancreatic phase and homogeneous enhancement

on the portal phase. These enhancement patterns are similar to those of the spleen. (c) Technetium 99 m (99 mTc)-labeled damaged red blood cell scan demonstrates focal uptake in the pancreatic tail (arrow)

20

Solid Tumors in the Pancreas

Suggested Reading Alzahrani MA, Schmulewitz N, Grewal S, et al. Metastases to the pancreas: the experience of a high volume center and a review of the literature. J Surg Oncol. 2012;105(2):156–61. Bosman FT, Carneiro F, Hruban RH, et al. WHO classification of tumours of the digestive system: World Health Organization. Lyon: IARC Press; 2010. Coakley FV, Hanley-Knutson K, Mongan J, et al. Pancreatic imaging mimics: part 1, imaging mimics of pancreatic adenocarcinoma. AJR Am J Roentgenol. 2012;199(2):301–8. Cooper JA. Solid pseudopapillary tumor of the pancreas. Radiographics. 2006;26(4):1210. Gupta A, Subhas G, Mittal VK, et al. Pancreatic schwannoma: literature review. J Surg Educ. 2009;66(3):168–73.

701 Lewis RB, Lattin Jr GE, Paal E, et al. Pancreatic endocrine tumors: radiologic- clinicopathologic correlation. Radiographics. 2010; 30(6):1445–64. Low G, Panu A, Millo N, et al. Multimodality imaging of neoplastic and nonneoplastic solid lesions of the pancreas. Radiographics. 2011;31(4):993–1015. Megibow AJ. Unusual solid pancreatic tumors. Radiol Clin North Am. 2012;50(3):499–513. Raman SP, Hruban RH, Cameron JL, et al. Pancreatic imaging mimics: part 2, pancreatic neuroendocrine tumors and their mimics. AJR Am J Roentgenol. 2012;199(2):309–18. Tamm EP, Balachandran A, Bhosale PR, et al. Imaging of pancreatic adenocarcinoma: update on staging/resectability. Radiol Clin North Am. 2012;50(3):407–28. Yoon MA, Lee JM, Kim SH, et al. MRI features of pancreatic colloid carcinoma. AJR Am J Roentgenol. 2009;193(4):W308–W13.

Trauma and Post-treatment Complications of the Pancreas

21

Ji Hoon Park and Kyoung Ho Lee

Contents 21.1 Traumatic Pancreas Injury . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

704

21.2 Post-treatment Complication . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

705

21.3 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

705

21.4 Illustrations: Trauma and Post-treatment Complications of the Pancreas . . . . . . . . . . . . . . .

706

Suggested Reading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

717

J.H. Park • K.H. Lee (*) Department of Radiology, Seoul National University Bundang Hospital, Seongnam-Si, Republic of Korea e-mail: [email protected], [email protected] B.I. Choi (ed.), Radiology Illustrated: Hepatobiliary and Pancreatic Radiology, Radiology Illustrated, DOI 10.1007/978-3-642-35825-8_21, © Springer-Verlag Berlin Heidelberg 2014

703

704

21.1

J.H. Park and K.H. Lee

Traumatic Pancreas Injury

Blunt traumatic injury to the pancreas is uncommon, accounting for less than 2 % of all cases of blunt abdominal trauma. Diagnosis and accurate grading of pancreatic injury is important, as the presence of pancreatic ductal injury mandates operative intervention, and delayed recognition of ductal injury frequently results in significant morbidity such as necrotizing pancreatitis or pseudocyst formation and a patient’s death. When a definitive diagnosis is delayed for more than 24 h, up to 40 % of patients are at risk of death, as opposed to about 10 % of those patients operated on within 24 h. The pancreas is a retroperitoneal organ, lies across the midline, and has fixed position anterior to the upper lumbar vertebral bodies. Although the retroperitoneal location of the pancreas protects it from most instances of blunt abdominal trauma, severe anterior–posterior force vectors compressing the pancreas against the spine may cause life-threatening pancreatic injury. These injuries often result from the steering wheel in a motor vehicle accident in adults, from bicycle handlebar in children, and from child abuse in infants. Minor causes include a misplaced seat belt, a direct blow, and a fall. Blunt pancreatic injury is more common in children and young adults because they have a thinner layer of retroperitoneal fat that might allow more intense transmission of energy. Two-thirds of blunt pancreatic injuries occur in the pancreatic body, and the remainder occurs equally in the head, neck, and tail. The more rigid and brittle nature of the pancreatic duct than the pancreatic vessels, the capsule, and the parenchyma enables the ductal injury without any visible signs of bleeding or capsular ruptures. Since coexisting injuries can affect various organs adjacent to the pancreas, careful examination should be accompanied for injuries of the second and the third portions of duodenum, liver, and bile duct as well as pancreatic head or uncinate process especially in right upper quadrant trauma. In left upper quadrant trauma, injuries can affect the spleen, stomach, small bowel, and left kidney as well as pancreatic body or tail which is located left of the superior mesenteric artery.

21.1.1 Imaging Technique for Pancreas Injury As CT is the most preferred method for the evaluation of blunt abdominal trauma, it is frequently the first imaging modality that can assess the pancreatic injury. The reported sensitivity and specificity of CT in detecting pancreatic injury is variable, which is associated with limited quality of the related studies. Although recent advent of MDCT and use of thinner collimation was thought to have further

Table 21.1 CT findings indicative of pancreatic injury Active pancreatic bleeding Pancreatic laceration or facture Pancreatic contusion or hematoma Focal or diffuse enlargement or edema of the gland Low or heterogeneous pancreatic attenuation Dilatation or discontinuity of the pancreatic duct Edema and stranding of peripancreatic fat Thickening of the anterior pararenal fascia Fluid in the lesser sac, transverse mesocolon, and anterior and posterior pararenal spaces or surrounding the SMA Pseudocyst or abscess Fluid between the posterior pancreas and splenic vein Injuries to adjacent structures Free intraperitoneal fluid SMA superior mesenteric artery

improvement, the diagnostic performance of CT in detecting pancreatic trauma is still on debate. CT findings suggestive of pancreatic injury are summarized in Table 21.1. Since most CT findings of pancreatic injury are time-dependent phenomena, the initial CT findings can be subtle, or even normal relative to other solid organ injuries. Therefore, repeated scan in 12–24 h should always be considered if there is a suspicion for pancreatic injury. Conventionally, ERCP has been regarded as the gold standard in the evaluation of pancreatic duct. However, due to the invasive nature of ERCP, it is not widely accepted as an appropriate screening test for pancreatic trauma. MRCP has been reported as attractive alternative modality to evaluate the patency of pancreatic duct. Some investigators demonstrated that the use of secretin stimulation improved the delineation of ductal morphologic features on MRCP; therefore it could provide additional useful information about duct integrity. However, the exact usefulness of MRCP in acute pancreatic injury has not yet been established since most studies on the topic had limitations of small sample size and retrospective nature. More experience and studies are required to confirm the usefulness of MRCP in acute pancreatic injury.

21.1.1.1 Grading of Pancreatic Injury Among various classification systems proposed for pancreatic injury, a grading scale proposed by the American Association for the Surgery of Trauma (AAST) is the most widely accepted (see Table 21.2). This scheme addresses the significance of more complex injuries to the pancreas according to the location of the injury and the integrity of the ampulla and main pancreatic duct. It also enables to correlate with other organ injury scales which allow the prediction of a patient’s prognosis.

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Trauma and Post-treatment Complications of the Pancreas

Table 21.2 American Association for the Surgery of Trauma pancreatic injury scale Gradea I II

Type of injury Hematoma Laceration Hematoma Laceration

III

Laceration

IV

Laceration

V

Laceration

Description of injury Minor contusion without duct injury Superficial laceration without duct injury Major contusion without duct injury or tissue loss Major laceration without duct injury or tissue loss Distal transection or parenchymal injury with duct injury Proximal (to right of SMV) transection or parenchymal injury involving ampulla Massive disruption of pancreatic head

a

Advance one grade for multiple injuries up to grade III. SMV superior mesenteric vein

21.1.2 Differential Diagnosis: Pseudopancreatitis Several studies have been published to report an abnormal CT finding of intra- and peripancreatic fluid in patients without clinical and laboratory evidence of pancreatic injury, pancreatitis, or pancreatic disease. The reported causes of this phenomenon comprise severe trauma of extremities, major burn injury, and hypovolemic shock. Although the exact mechanism of pseudopancreatitis was not well known, a hypothesis was proposed that it might be a consequence of mild ischemic pancreatic injury caused by hypovolemic shock and followed by overhydration.

21.2

705

pancreatic fistula runs a benign course, it potentially leads to postoperative mortality if it results in retroperitoneal sepsis with abscess formation and/or destruction of the surrounding tissues and blood vessels. A fluid collection seen on CT around the pancreaticojejunostomy site and in the pancreatic bed and depiction of air bubbles in the fluid are known to be feasible findings for diagnosing pancreatic fistula. Since pancreatic leakage is basically a clinical diagnosis of persistent drainage of amylase-rich fluid, clinico-radiologic correlation should always be followed when there is a suspicion of pancreatic leakage. Delayed gastric emptying is also a common complication of which incidence ranges from 20 to 60 % of patients. It is notable that delayed gastric emptying is closely associated with other postoperative pathologic conditions such as pancreatic fistula and postoperative acute pancreatitis. However, the radiologic evaluation of postoperative delayed gastric emptying has not been well established in the literature.

21.2.2 Post-procedural Complication Several diagnostic and therapeutic procedures might cause complications in the pancreas. Acute pancreatitis is one of the most common complications of ERCP. Although ultrasonography-guided percutaneous or endoscopic biopsy has been established as a feasible and safe method to confirm the unresectable pancreatic cancer, it can also result in complications such as fever, hemorrhage, acute pancreatitis, and pseudocyst formation.

Post-treatment Complication 21.3

Summary

21.2.1 Post-operative Complication For the past two decades, with technical advances and centralization of care, pancreatic surgery has progressed into a safe procedure with mortality rates of less than 5 %. However, postoperative complication rate with reported range from 30 to 50 % is still considerable. Pancreatic surgery has similar complications which confront to other major abdominal surgery, e.g., anastomotic leakage, intra-abdominal abscess, wound infection/dehiscence, hemorrhage, and medical complications such as cardiac problems, cerebrovascular accidents, respiratory distress, and renal and hepatic dysfunction. Common and relatively specific complications that attend pancreatic surgery include pancreatic fistula and delayed gastric emptying. Pancreatic fistula occurs in 5–30 % of patients undergoing pancreaticoduodenectomy. This wide range is probably due to different definitions used. Although most

1. Blunt traumatic pancreatic trauma is uncommon accounting for less than 2 % of all cases of blunt abdominal trauma. 2. Since coexisting injuries can affect various organs adjacent to the pancreas, careful examination should be accompanied for injuries. 3. The diagnostic performance of CT in detecting pancreatic trauma is still on debate. 4. Repeated scan in 12–24 h should always be considered if there is a suspicion for pancreatic injury. 5. ERCP is the gold standard in the evaluation of pancreatic duct. 6. MRCP might be useful in the evaluation of acute pancreatic injury although more experience and studies are required. 7. As various iatrogenic procedures might affect the pancreas, radiologists should always concern the possibility of the pancreatic injury in image interpretation.

706

21.4

J.H. Park and K.H. Lee

Illustrations: Trauma and Post-treatment Complications of the Pancreas

21.4.1 Pancreatic Contusion

a

c

Fig. 21.1 Pancreatic contusion in a 28-year-old male. (a) Contrastenhanced axial CT shows hypoattenuating area (arrowheads) at the pancreas. (b) T2-weighted axial MR image taken 2 days later shows edema in and around the pancreatic body and tail (arrows). (c) On

b

d

endoscopic retrograde cholangiopancreatography, there is no evidence of leakage from or disruption of the pancreatic duct (arrows). (d) On follow-up contrast-enhanced axial CT 4 months later, previous abnormal findings disappeared

21

Trauma and Post-treatment Complications of the Pancreas

707

21.4.2 Pancreatic Laceration with Hematoma

a

b

Fig. 21.2 Pancreatic laceration with hematoma in an 18-year-old male. (a) On precontrast axial CT, there is a round hematoma (arrows) at the pancreatic head. (b) Contrast-enhanced axial CT reveals lacerations in the pancreas (arrowhead) and the liver (curved arrow)

708

21.4.3 Pancreatic Transection

Fig. 21.3 Pancreatic transection in a 10-year-old male. Contrastenhanced axial CT shows a well-demarcated low-attenuating defect at the junction of the pancreatic body and tail (arrows)

J.H. Park and K.H. Lee

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Trauma and Post-treatment Complications of the Pancreas

709

21.4.4 Pancreatic Transection with Hemoperitoneum

a

b

Fig. 21.4 Pancreatic transection with hemoperitoneum in a 45-year-old male. (a, b) Precontrast (a) and contrast-enhanced (b) axial CT images show a hematoma filling a defect of the pancreas (arrowheads) and hemoperitoneum (asterisks)

710

J.H. Park and K.H. Lee

21.4.5 Pseudocyst

a

Fig. 21.5 Pseudocyst in a 38-year-old male who presented with abdominal pain worsening for 2 weeks following abdominal trauma. (a) Contrast-enhanced axial CT image shows a pseudocyst (arrows) at

b

the pancreatic body. (b) T2-weighted MR cholangiopancreatography shows the pancreatic pseudocyst and dilatation of the upstream pancreatic duct (arrows)

21

Trauma and Post-treatment Complications of the Pancreas

711

21.4.6 Pancreatic Duct Injury with Pancreatic Ascites

a

b

c

d

Fig. 21.6 Pancreatic duct injury with pancreatic ascites in a 46-yearold male. (a–c) Contrast-enhanced axial (a, b) and coronal (c) CT images show swelling of the pancreatic head (arrows), dilatation of the upstream pancreatic duct (curved arrow), and ascites (asterisks). (d)

Endoscopic retrograde cholangiopancreatography shows extravasation of contrast material (arrows) suggesting disruption of the pancreatic duct

712

J.H. Park and K.H. Lee

21.4.7 Penetrating Pancreatic Trauma

a

Fig. 21.7 Penetrating pancreatic trauma in a 21-year-old female. (a, b) Contrast-enhanced axial (a) and coronal (b) CT images show multiple pseudoaneurysms or extravasation (arrowheads) at the pancreatic body.

b

There are multiple hepatic lacerations (curved arrows) and hemoperitoneum (asterisks)

21

Trauma and Post-treatment Complications of the Pancreas

21.4.8 Pancreatic Fistula

Fig. 21.8 Pancreatic fistula in a 65-year-old female who underwent pylorus-preserving pancreatoduodenectomy. Contrast-enhanced axial CT image shows a small fluid collection (arrows) around the pancreatojejunostomy. A high amylase level in the drain fluid confirmed the diagnosis of the pancreatic fistula

713

714

J.H. Park and K.H. Lee

21.4.9 Duodenal Perforation Following Endoscopic Retrograde Cholangiopancreatography

a

Fig. 21.9 Duodenal perforation following endoscopic retrograde cholangiopancreatography in a 38-year-old male. (a, b) Contrast-enhanced axial (a) and coronal (b) CT images show diffuse wall thickening of the

b

duodenum (arrows), retroperitoneal fluid around the duodenum (asterisks), and pneumoperitoneum (curved arrows)

21

Trauma and Post-treatment Complications of the Pancreas

715

21.4.10 Pseudocyst

a

b

c

Fig. 21.10 Pseudocyst in a 62-year-old male. (a) Contrast-enhanced axial CT shows a 2.5 cm hyperattenuating mass (arrows) at the pancreatic body. (b) Biopsy was performed for the mass under the guidance of endoscopic ultrasonography. (c) Fifteen days later, he visited the emer-

gency department with epigastric pain. Contrast-enhanced coronal CT image shows a large cystic mass in the stomach, representing a pancreatic pseudocyst (arrow)

716

21.4.11 Pseudopancreatitis

Fig. 21.11 Pseudopancreatitis in an 81-year-old female. Contrastenhanced axial CT image taken immediately after the cardiopulmonary resuscitation due to cardiac arrest shows peripancreatic edema (arrows)

J.H. Park and K.H. Lee

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Trauma and Post-treatment Complications of the Pancreas

Suggested Reading Bradley EL, Young Jr PR, Chang MC, et al. Diagnosis and initial management of blunt pancreatic trauma: guidelines from a multiinstitutional review. Ann Surg. 1998;227:861–9. Brook OR, Fischer D, Militianu D, et al. Pseudopancreatitis in trauma patients. AJR Am J Roentgenol. 2009;193:W193–6. Bruno O, Brancatelli G, Sauvanet A, et al. Utility of CT in the diagnosis of pancreatic fistula after pancreaticoduodenectomy in patients with soft pancreas. AJR Am J Roentgenol. 2009;193:W175–80. Chapman VM, Rhea JT, Sacknoff R, et al. CT of nontraumatic abdominal fluid collections after initial fluid resuscitation of patients with major burns. AJR Am J Roentgenol. 2004;182:1493–6. Cirillo RL, Koniaris LG. Detecting blunt pancreatic injuries. J Gastrointest Surg. 2002;6:587–98. Drake LM, Anis M, Lawrence C. Accuracy of magnetic resonance cholangiopancreatography in identifying pancreatic duct disruption. J Clin Gastroenterol. 2012;46:696–9. Fragulidis GP, Arkadopoulos N, Vassiliou I, et al. Pancreatic leakage after pancreaticoduodenectomy: the impact of the isolated jejunal loop length and anastomotic technique of the pancreatic stump. Pancreas. 2009;38:e177–82. Fulcher AS, Turner MA, Yelon JA, et al. Magnetic resonance cholangiopancreatography (MRCP) in the assessment of pancreatic duct trauma and its sequelae: preliminary findings. J Trauma. 2000;48:1001–7. Gillams AR, Kurzawinski T, Lees WR. Diagnosis of duct disruption and assessment of pancreatic leak with dynamic secretin-stimulated MR cholangiopancreatography. AJR Am J Roentgenol. 2006;186: 499–506. Gomez MA, Besson M, Scotto B, et al. MR imaging in the evaluation of blunt pancreatic trauma. J Radiol. 2004;85:414–7. Gore RM, Levine MS. Textbook of gastrointestinal radiology. Philadelphia: Saunders; 2007. Hashimoto M, Koga M, Ishiyama K, et al. CT features of pancreatic fistula after pancreaticoduodenectomy. AJR Am J Roentgenol. 2007;188:W323–7. Heitsch RC, Knutson CO, Fulton RL, et al. Delineation of critical factors in the treatment of pancreatic trauma. Surgery. 1976;80: 523–9. Ho C-K, Kleeff J, Friess H, et al. Complications of pancreatic surgery. HPB. 2005;7:99–108. Kao LS, Bulger EM, Parks DL, et al. Predictors of morbidity after traumatic pancreatic injury. J Trauma. 2003;55:898–905. Lee WJ, Foo NP, Lin HJ, et al. The efficacy of four-slice helical CT in evaluating pancreatic trauma: a single institution experience. J Trauma Manag Outcomes. 2011;5:1. Leppaniemi AK, Haapiainen RK. Risk factors of delayed diagnosis of pancreatic trauma. Eur J Surg. 1999;165:1134–7. Linsenmaier U, Wirth S, Reiser M, et al. Diagnosis and classification of pancreatic and duodenal injuries in emergency radiology. Radiographics. 2008;28:1591–602. Lucas CE. Diagnosis and treatment of pancreatic and duodenal injury. Surg Clin North Am. 1977;57:49–65.

717 Lucas CE, Ledgerwood AM. Factors influencing outcome after blunt duodenal injury. J Trauma. 1975;15:839–46. Madiba TE, Mokoena TR. Favourable prognosis after surgical drainage of gunshot, stab or blunt trauma of the pancreas. Br J Surg. 1995;82:1236–9. Matos C, Metens T, Deviere J, et al. Pancreatic duct: morphologic and functional evaluation with dynamic MR pancreatography after secretin stimulation. Radiology. 1997;203:435–41. Matsubara J, Okusaka T, Morizane C, et al. Ultrasound-guided percutaneous pancreatic tumor biopsy in pancreatic cancer: a comparison with metastatic liver tumor biopsy, including sensitivity, specificity, and complications. J Gastroenterol. 2008;43:225–32. Moore EE, Cogbill TH, Malangoni MA, et al. Organ injury scaling, II: pancreas, duodenum, small bowel, colon, and rectum. J Trauma. 1990;30:1427–9. Nirula R, Velmahos GC, Demetriades D. Magnetic resonance cholangiopancreatography in pancreatic trauma: a new diagnostic modality? J Trauma. 1999;47:585–7. Oniscu GC, Parks RW, James Garden O. Classification of liver and pancreatic trauma. HPB. 2006;8:4–9. Paspulati RM. Multidetector CT of the pancreas. Radiol Clin North Am. 2005;43:999–1020, viii. Phelan HA, Velmahos GC, Jurkovich GJ, et al. An evaluation of multidetector computed tomography in detecting pancreatic injury: results of a multicenter AAST study. J Trauma. 2009;66:641–6; discussion 646–647. Raty S, Sand J, Lantto E, et al. Postoperative acute pancreatitis as a major determinant of postoperative delayed gastric emptying after pancreaticoduodenectomy. J Gastrointest Surg. 2006;10:1131–9. Ryan MF, Hamilton PA, Sarrazin J, et al. The halo sign and peripancreatic fluid: useful CT signs of hypovolaemic shock complex in adults. Clin Radiol. 2005;60:599–607. Scollay JM, Yip VS, Garden OJ, et al. A population-based study of pancreatic trauma in Scotland. World J Surg. 2006;30:2136–41. Shanmuganathan K. Multi-detector row CT imaging of blunt abdominal trauma. Semin Ultrasound CT MR. 2004;25:180–204. Smego DR, Richardson JD, Flint LM. Determinants of outcome in pancreatic trauma. J Trauma. 1985;25:771–6. Soto JA, Alvarez O, Munera F, et al. Traumatic disruption of the pancreatic duct: diagnosis with MR pancreatography. AJR Am J Roentgenol. 2001;176:175–8. Takishima T, Hirata M, Kataoka Y, et al. Pancreatographic classification of pancreatic ductal injuries caused by blunt injury to the pancreas. J Trauma. 2000;48:745–51; discussion 751–742. Teh SH, Sheppard BC, Mullins RJ, et al. Diagnosis and management of blunt pancreatic ductal injury in the era of high-resolution computed axial tomography. Am J Surg. 2007;193:641–3; discussion 643. Venkatesh SK, Wan JM. CT of blunt pancreatic trauma: a pictorial essay. Eur J Radiol. 2008;67:311–20. Wilson RH, Moorehead RJ. Current management of trauma to the pancreas. Br J Surg. 1991;78:1196–202. Yang L, Zhang XM, Xu XX, et al. MR imaging for blunt pancreatic injury. Eur J Radiol. 2010;75:e97–101.

Part IV Spleen

Anomalies and Anatomic Variations of the Spleen

22

Ijin Joo and Ah Young Kim

Contents 22.1 Splenic Lobulation, Notch, and Cleft . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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22.2 Accessory Spleen . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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22.3 Wandering Spleen . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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22.4 Asplenia and Polysplenia . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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22.5 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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22.6 Illustrations: Anomalies and Anatomic Variations of the Spleen . . . . . . . . . . . . . . . . . . . . . . .

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Suggested Reading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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I. Joo Department of Radiology, Seoul National University Hospital, Seoul, Republic of South Korea e-mail: [email protected] A.Y. Kim (*) Department of Radiology, University of Ulsan, Asan Medical Center, Seoul, Republic of South Korea e-mail: [email protected] B.I. Choi (ed.), Radiology Illustrated: Hepatobiliary and Pancreatic Radiology, Radiology Illustrated, DOI 10.1007/978-3-642-35825-8_22, © Springer-Verlag Berlin Heidelberg 2014

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The spleen develops within the dorsal mesogastrium and rotates to the left, becoming fixed in the left subphrenic location by peritoneal reflections, and it usually develops as one fused mass of tissue. There is a wide spectrum of congenital anomalies and anatomic variations of the spleen, ranging from common conditions such as splenic lobulation and accessory spleen to rare conditions such as wandering spleen and asplenia/polysplenia.

infarction. And also the abdominal or pelvic location of the spleen increases the risk of traumatic injury. Imaging findings are absence of the spleen in the normal position and a soft tissue mass resembling the spleen located in other peritoneal cavity. The most common location of the wandering spleen is in the left mid-abdomen. Sequential images may demonstrate a change in splenic location.

22.4 22.1

The spleen is lobulated in the fetal period, but the lobules usually disappear before birth. However, splenic lobulations can persist after fetal life and are seen usually along the medial part of the spleen. Prominent splenic lobules may mimic neoplasms of kidney or adrenal gland. Splenic notches and clefts are remnants of the grooves that originally separated the fetal lobules. As the notches and clefts can be sharp and deep as 2 or 3 cm in depth, they may be misinterpreted as splenic laceration in patients with abdominal trauma.

22.2

Accessory Spleen

Accessory spleen refers to an ectopic splenic tissue of congenital origin. One or more accessory spleens are found about 10–30 % of general population. Common locations of accessory spleens are in or near the splenic hilum and ligaments, but they can be found anywhere in the peritoneal cavity. Especially, up to 16 % of accessory spleens are located in or near the pancreas tail. Most cases of accessory spleens are asymptomatic and are found incidentally at surgery or radiologic examination. Accessory spleens can mimic submucosal gastric mass, pancreatic neoplasm such as neuroendocrine tumor, and lymphadenopathy. On imaging studies such as nuclear scintigraphy, ultrasound, CT, or MRI, accessory spleens without complications show the same tissue texture and enhancement pattern with normal spleen which makes it possible to interpret the lesions as accessory spleens. However, any conditions which may affect the spleen, such as neoplasm, infection, or infarction, can be seen also in the accessory spleen. These pathologic conditions in the accessory spleen result in different imaging features from normal spleen and make correct diagnosis difficult.

22.3

Asplenia and Polysplenia

Splenic Lobulation, Notch, and Cleft

Wandering Spleen

Wandering spleen is a condition caused by ligamentous laxity which causes splenic hypermobility and, subsequently, a more caudal location of the spleen from its normal site in the left upper quadrant abdomen. This is a rare condition with the incidence of less than 0.2 %. Its long pedicle renders the spleen hypermobile, predisposing it to torsion with

Situs ambiguous or heterotaxy refers to an abnormal arrangement of body organs, and it results from failure of development of the embryo to establish normal left-right asymmetry. Anatomy in situs ambiguous is different from the orderly arrangement in either the typical anatomy (situs solitus) or the mirror image of it (situs inversus). Cardiopulmonary abnormalities are frequently associated with both asplenia and polysplenia syndromes which cause high mortality: 80 % in asplenia and 50–60 % in polysplenia. The spleen is almost always affected in situs ambiguous which appears as absence (asplenia) or multiplicity of spleens (polysplenia), and there is syndromic clustering of the malformations corresponding to the types of splenic abnormality. In asplenia syndrome (i.e., right isomerism, bilateral right-sidedness), the liver may be symmetric, there is no visible distinct splenic contour, the abdominal aorta and inferior vena cava are on the same side, and both lungs are bilaterally trilobed. Polysplenia syndrome (i.e., left isomerism, bilateral left-sidedness) can be characterized by midline liver, multiple spleens located in the right and left upper quadrants, intrahepatic interruption of the inferior vena cava with continuation of the azygos vein, and bilateral bilobed lungs. The anatomic structures may be evaluated with chest radiography, ultrasound, CT, and MR imaging which are useful in demonstrating abnormalities of morphology and location of the internal organs.

22.5

Summary

1. Anatomical variations of the spleen range from common conditions, such as splenic lobulation and accessory spleen, to rare conditions such as wandering spleen and asplenia/polysplenia. 2. Splenic notches and clefts may mimic splenic laceration in patients with abdominal trauma. 3. Accessory spleens are usually located in or near the splenic hilum and the pancreas tail. 4. Accessory spleens show the same tissue texture and enhancement pattern with normal spleen on imaging studies. 5. The wandering spleen can be predisposed to torsion. 6. Asplenia (right isomerism) and polysplenia syndromes (left isomerism) are congenital abnormalities of organ arrangement, and they are frequently combined with fatal cardiopulmonary diseases.

22

Anomalies and Anatomic Variations of the Spleen

22.6

Illustrations: Anomalies and Anatomic Variations of the Spleen

22.6.1 Splenic Lobulations: Medial Part

Fig. 22.1 Splenic lobulations. Contrast-enhanced transverse CT image shows typical lobulations along the medial border of the spleen (arrowheads)

723

724

22.6.2 Splenic Lobulations: Lateral Part

Fig. 22.2 Splenic lobulations in a less common location. Contrastenhanced transverse CT image shows lobulated contour of the spleen along the lateral border (arrowheads)

I. Joo and A.Y. Kim

22

Anomalies and Anatomic Variations of the Spleen

22.6.3 Prominent Splenic Lobule Extending Medially

Fig. 22.3 Prominent splenic lobule extending medially. A lobule from the posterior pole of the spleen (arrowhead) is located superior to the upper pole of the left kidney which may be mistaken for a retroperitoneal soft tissue tumor

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22.6.4 Splenic Lobule Mimicking a Gastric Subepithelial Tumor a

b

c

d

Fig. 22.4 Splenic lobule mimicking a gastric subepithelial tumor. (a) Three-dimensional CT gastrography shows an indentation (arrowheads) of the gastric fundus which can mimic a subepithelial tumor or an extraluminal mass. (b–d) Contrast-enhanced transverse (b), sagittal

(c), and coronal (d) CT images reveal extrinsic compression of the gastric wall by a splenic lobule at superomedial aspect of the spleen (arrowheads)

22

Anomalies and Anatomic Variations of the Spleen

727

22.6.5 Splenic Cleft: Superior Border a

b

Fig. 22.5 Splenic cleft. (a) Contrast-enhanced transverse CT image demonstrates a prominent cleft (arrowhead) between lobules of the spleen. (b) Contrast-enhanced coronal CT image shows the sharp and thin cleft at the superior border of the spleen (arrowhead)

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22.6.6 Splenic Cleft: Inferior Border a

b

Fig. 22.6 Splenic cleft. (a, b) Contrast-enhanced transverse (a) and coronal (b) CT images demonstrate a prominent cleft (arrowheads) on the superior border of the spleen, which may be erroneously interpreted as a splenic laceration in trauma patients

22

Anomalies and Anatomic Variations of the Spleen

729

22.6.7 Accessory Spleen at the Splenic Hilum a

Fig. 22.7 Accessory spleen at the splenic hilum. (a) Gray-scale ultrasound image of the left upper quadrant shows an accessory spleen (arrowhead) in its common location, at the splenic hilum.

b

The echogenicity of the accessory spleen is the same as that of the spleen. (b) Contrast-enhanced transverse CT in the same patient shows the spherical accessory spleen (arrowhead) at the splenic hilum

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22.6.8 Accessory Spleen Located Posterior to the Spleen a

Fig. 22.8 Accessory spleen located posterior to the spleen. (a, b) Contrast-enhanced transverse CT shows an oval soft tissue mass (arrowheads) at posterior aspect to the spleen. The attenuation of the

b

accessory spleen is identical to that of splenic tissue both in arterial (a) and portal phases (b)

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Anomalies and Anatomic Variations of the Spleen

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22.6.9 Intrapancreatic Accessory Spleen with Typical Imaging Features a

b

c

d

e

f

Fig. 22.9 Intrapancreatic accessory spleen with typical imaging features. (a, b) On contrast-enhanced dynamic CT scans including precontrast (a), arterial (b), and portal (c) phases, an accessory spleen in the pancreas tail (arrowheads) shows typical enhancement pattern which is identical to that of the spleen (asterisk) during all phases. (b) Note the inhomogeneous enhancement within the accessory spleen on the

arterial phase image, which is same to zebra-striped enhancement of the spleen. (d–f) On MRI of the same patient, the accessory spleen (arrowheads) also shows identical signal intensity to the spleen (asterisk) both in T2-weighted (d) and T1-weighted (e) images and also in the diffusion-weighted image (f) (B value = 500 s/mm2)

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22.6.10 Intrapancreatic Spleen a

b

c

d

Fig. 22.10 Intrapancreatic spleen detected incidentally on routine checkup. (a, b) Precontrast (a) and contrast-enhanced (b) transverse CT images show a well-enhancing soft tissue mass (arrowheads) in the pancreas tail which mimics a hypervascular pancreas tumor such as a neuroendocrine tumor. (c) Note the absence of the normal spleen in the

left upper quadrant, just below the left diaphragm. This patient has not undergone any surgery such as splenectomy. (d) Coronal image of techetium-99m-labeled heat-damaged red blood cell scintigraphy reveals hot uptake (arrowhead) at the intrapancreatic spleen

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Anomalies and Anatomic Variations of the Spleen

733

22.6.11 Intrahepatic Accessory Spleen a

b

c

Fig. 22.11 Intrahepatic accessory spleen. (a, b) Contrast-enhanced arterial (a) and portal (b) phase transverse CT images show a hypervascular mass in segment VI of the liver, which may be mistaken for a

hypervascular liver tumor such as a hepatocellular carcinoma or an adenoma. (c) Photography of surgical specimen shows yellowish soft tissue mass (arrowheads) which is confirmed as an accessory spleen

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22.6.12 Wandering Spleen

a

* b

c

*

Fig. 22.12 Wandering spleen. (a–c) Contrast-enhanced transverse (a), coronal (b), and sagittal (c) CT images revealed the spleen (asterisk) is located in the left mid-abdomen. Note the absence of spleen in the left

*

upper quadrant. (c) Sagittal reformatted CT shows a more caudal location of the spleen (asterisk) from its normal site in the left upper quadrant and a more cranial location of the left kidney

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Anomalies and Anatomic Variations of the Spleen

735

22.6.13 Asplenia a

b

c

Fig. 22.13 Asplenia. (a) CT in a 0-day-old neonate with asplenia shows right isomerism with bilateral superior vena cava (arrows) and right-sided aortic arch (arrowhead). (b) Minimum intensity projection

CT image demonstrates right bronchial isomerism. (c) Contrastenhanced transverse CT scan through the upper abdomen shows midline liver and the stomach on the right (arrowhead)

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22.6.14 Polysplenia a

Fig. 22.14 Polysplenia. (a) Contrast-enhanced transverse CT shows absence of intrahepatic inferior vena cava and a dilated azygos vein (arrow), and multiple splenic masses in the left upper quadrant (arrow-

b

heads). (b) Contrast-enhanced transverse CT of lung window setting at the pulmonary artery level shows bilateral hyparterial bronchi (Morphologic left bronchi) (arrowheads)

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Suggested Reading Dachman AH. Anomalies and anatomic variants of the spleen. In: Gore RM, Levine MS, editors. Textbook of gastrointestinal radiology. 3rd ed. Philadelphia: Saunders; 2008. Applegate KE, Goske MJ, Pierce G, Murphy D. Situs revisited: imaging of the heterotaxy syndrome. Radiographics. 1999;19(4): 837–52; discussion 853–834. Gayer G, Zissin R, Apter S, Atar E, Portnoy O, Itzchak Y. CT findings in congenital anomalies of the spleen. Br J Radiol. 2001;74(884): 767–72.

737 Mortele KJ, Mortele B, Silverman SG. CT features of the accessory spleen. AJR Am J Roentgenol. 2004;183(6):1653–7. Elsayes KM, Narra VR, Mukundan G, Lewis Jr JS, Menias CO, Heiken JP. MR imaging of the spleen: spectrum of abnormalities. Radiographics. 2005;25(4):967–82. Gayer G, Hertz M, Strauss S, Zissin R. Congenital anomalies of the spleen. Semin Ultrasound CT MRI. 2006;27(5):358–3697. Kim SH, Lee JM, Han JK, et al. Intrapancreatic accessory spleen: findings on MR Imaging, CT, US and scintigraphy, and the pathologic analysis. Korean J Radiol. 2008;9(2):162–74.

Diffuse Spleen Diseases

23

Jong Seok Lee

Contents 23.1 Splenomegaly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

740

23.2 Infection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

740

23.3 Miscellaneous . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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23.4 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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23.5 Illustrations: Diffuse Spleen Diseases. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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Suggested Reading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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J.S. Lee Department of Radiology, University of Ulsan, Asan Medical Center, Seoul, Republic of South Korea e-mail: [email protected] B.I. Choi (ed.), Radiology Illustrated: Hepatobiliary and Pancreatic Radiology, Radiology Illustrated, DOI 10.1007/978-3-642-35825-8_23, © Springer-Verlag Berlin Heidelberg 2014

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Diffuse splenic diseases show nonspecific imaging findings in general, although some diseases may have distinct findings. Clinical findings and secondary findings outside the spleen also provide important clues for the differential diagnosis. Various causes for splenomegaly, infectious diseases, and other conditions which may diffusely involve the spleen are discussed in this chapter.

23.1

Splenomegaly

Splenomegaly is an enlargement of the spleen. There are many causes of diffuse splenomegaly. There are many ways of classification, but etiology-based categorization is widely used (Table 23.1). Because the imaging findings of splenomegaly are quite similar, the clinical findings such as past medical history and laboratory findings are important for differential diagnosis.

Table 23.1 Common causes of diffuse splenomegaly Congestive splenomegaly Liver cirrhosis Portal hypertension Hepatic vein obstruction Splenic vein obstruction Infectious and inflammatory diseases Infectious mononucleosis Acquired immunodeficiency syndrome (AIDS) Viral hepatitis Typhoid fever Tuberculosis Malaria Sarcoidosis Hyperplastic splenomegaly Spherocytosis Thalassemia Hemoglobinopathy Infiltrative diseases Leukemia Lymphoma Myeloproliferative disease Extramedullary hematopoiesis Storage disease Neoplasm Hemangiomatosis Lymphangiomatosis Peliosis

23.1.1 Congestive Splenomegaly In congestive splenomegaly, an obstruction of portal venous outflow from the spleen leads to an increase in the amount of red pulp. The main cause of congestive splenomegaly is liver cirrhosis. Other causes including hepatic vein obstruction such as membranous obstruction of inferior vena cava (MOIVC) or isolated splenic vein obstruction can cause congestive splenomegaly. Secondary findings can help to differentiate the cause. Splenomegaly with liver surface nodularity suggests the diagnosis of liver cirrhosis. Splenomegaly with multiple subcutaneous venous collaterals may suggest MOIVC. Splenomegaly associated with pancreatic mass is suggestive for isolated splenic vein occlusion.

23.1.2 Hyperplastic Splenomegaly Hyperplastic splenomegaly results from the normal sequestration of increased amount of the abnormal blood cells which are degenerated in the spleen.

23.1.3 Infectious and Inflammatory Disease Inflammatory splenomegaly is caused by increased reticuloendothelial cell and lymphoid cell proliferation from an increased antigen clearance and antibody production. Abscess formation in the spleen, due to filtered encapsulated organisms, can cause infectious splenomegaly.

23.1.4 Infiltrative Splenomegaly Infiltrative lesions such as tumor cells (in the case of leukemia and lymphoma), metabolites (in the case of Gaucher’s disease and amyloidosis), and blood cell producing cells (in the case of extramedullary hematopoiesis) can cause splenomegaly.

23.2

Infection

23.2.1 Malaria Malaria is a protozoan disease associated with infected Anopheles mosquito. CT findings of splenic involvement of malaria include splenomegaly, decreased splenic

23 Diffuse Spleen Diseases

enhancement, and lack of mottled striped enhancement during the arterial phase. The complications of malaria include spontaneous splenic rupture and splenic infarction.

23.2.2 Tuberculosis Splenic involvement is usually in the miliary form. Miliary tuberculosis appears as irregular low-density masses in the spleen. Secondary finding including necrotic lymph nodes, high-density ascites, and nodular peritoneal thickening may be helpful. In the later phase, the splenic lesion turns into calcified granuloma.

23.2.3 Brucellosis Fever, night sweats, fatigue, anorexia, myalgia, and arthralgia are common symptoms of brucellosis. Hepatosplenomegaly, abscess formation, subcapsular hematoma formation, and splenic rupture are findings of splenic involvement of brucellosis. The respiratory involvement can help suggest the diagnosis.

23.2.4 Salmonella Infection The spleen is one of the most common sites of Salmonella infections, and the manifestations can range from nonspecific organomegaly to an abscess formation and splenic rupture.

23.2.5 Aspergillosis Splenic involvement of aspergillosis includes diffuse or multifocal wedge-shaped low-density areas or disseminated lowdensity nodules in the spleen due to the angioinvasiveness of the organism.

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23.3

Miscellaneous

23.3.1 Extramedullary Hematopoiesis Extramedullary hematopoiesis is a compensation of bone marrow dysfunction to make blood cells. It mainly affects the liver and spleen. The signal intensity of the lesion depends on the time of lesion, i.e., the time of iron component. In the active stage, the lesion shows intermediate signal intensity on T1-weighted image, high signal intensity on T2-weighted image with some enhancement after contrast media injection. In the late stage, the lesion may show low signal intensity on T1- and T2-weighted images without definite enhancement. On dual-echo gradient MR, the lesion shows low signal intensity in the in phase of MR due to the presence of iron.

23.3.2 Gamna-Gandy body Gamna-Gandy bodies are found in about 10 % of patients with splenomegaly. They consist of fibrous tissue with hemosiderin and probably are associated with small perivascular hemorrhages. They show low signal intensity on T1- and T2-weighted images owing to hemosiderin components.

23.4

Summary

1. Some splenic diseases show discrete image finding, but mainly the imaging findings of the splenic diseases are overlapped and indistinct. 2. Ancillary findings and clinical histories are very important to differentiate diffuse splenic diseases.

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23.5

J.S. Lee

Illustrations: Diffuse Spleen Diseases

23.5.1 Congestive Splenomegaly 23.5.1.1 Splenomegaly with Liver Cirrhosis

a

Fig. 23.1 Splenomegaly with liver cirrhosis in a 49-year-old male. (a, b) Contrast-enhanced CT images in portal phase (a) and equilibrium phase (b) show the enlarged spleen (arrow) and surface nodularity of

b

the liver (arrowhead). During portal phase, the spleen still shows socalled zebra-type heterogeneous enhancement. On equilibrium phase image, spleen shows homogeneous enhancement

23 Diffuse Spleen Diseases

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23.5.1.2 Splenomegaly Associated with Alcoholic Liver Cirrhosis

a

b

c

Fig. 23.2 Splenomegaly associated with alcoholic liver cirrhosis in a 57-year-old male. (a) Contrast-enhanced CT image in arterial phase shows inhomogeneous hepatic enhancement with splenomegaly. Note

preserved zebra-like splenic enhancement. (b, c) On portal (b) and equilibrium phase (c) transverse CT, the spleen shows more homogenous enhancement. Note the inhomogeneous hepatic enhancement

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23.5.1.3 Splenomegaly Associated with Splenic Vein Occlusion

a

b

Fig. 23.3 Splenomegaly associated with the splenic vein occlusion in a 50-year-old female. (a) Contrast-enhanced CT image in portal phase shows a low-attenuating pancreatic cancer in the pancreas tail (arrow)

which is encasing the splenic artery and vein. (b) On maximal intensity projection CT image, occlusion of the splenic vein (curved arrow) and multiple collateral vessels (arrowhead). Also note the splenomegaly

23 Diffuse Spleen Diseases

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23.5.1.4 Splenomegaly with Obstruction of Inferior Vena Cava

a

b

c

Fig. 23.4 Splenomegaly with obstruction of the inferior vena cava (IVC) in a 56-year-old female. (a) Precontrast transverse CT shows calcifications in the wall of the IVC (arrow). (b, c) Contrast-enhanced transverse CT images in portal phase show low-attenuating thrombus in

the right hepatic vein (curved arrow) with liver cirrhosis, splenomegaly, and ascites. Note multiple collateral vessels in the abdominal cavity and wall (arrowheads)

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23.5.2 Hyperplastic Splenomegaly 23.5.2.1 Splenomegaly Associated with Spherocytosis

Fig. 23.5 Splenomegaly associated with spherocytosis in a 15-yearold female. Contrast-enhanced CT image shows diffuse splenomegaly without focal lesion. Note the smooth surface of the liver without ascites and collateral vessels

J.S. Lee

23 Diffuse Spleen Diseases

23.5.2.2 Splenomegaly Associated with Polycythemia Vera

Fig. 23.6 Splenomegaly associated with polycythemia vera in a 40-year-old female. Contrast-enhanced CT image shows mild splenomegaly without focal lesion. Note no other positive finding

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23.5.3 Infiltrative Splenomegaly 23.5.3.1 Splenomegaly Associated with Gaucher’s Disease

a

b

c

Fig. 23.7 Splenomegaly associated with Gaucher’s disease in an 8-year-old female. (a) Initial contrast-enhanced CT image shows hepatosplenomegaly with a small low-attenuating nodule in the spleen (arrow). (b) Follow-up contrast-enhanced CT image 8 years later shows

persistent hepatosplenomegaly with multiple low-attenuating masses in the spleen (arrowheads), which are collections of Gaucher cells with or without dilated sinusoid filled with blood. (c) Note the size of the spleen in the coronal image

23 Diffuse Spleen Diseases

23.5.3.2 Splenomegaly Associated with Sarcoidosis

Y

Fig. 23.8 Splenomegaly associated with sarcoidosis in a 35-year-old female. Contrast-enhanced CT image shows splenomegaly associated with tiny low-density nodules in the liver and the spleen (arrowheads) which are representing noncaseating necrosis

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23.5.3.3 Splenomegaly Associated with Amyloidosis

a

b

c

Fig. 23.9 Splenomegaly associated with amyloidosis in a 40-year-old female. (a) Precontrast transverse CT image shows mild splenomegaly with inhomogeneous attenuation of the spleen. (b, c) Contrast-enhanced

transverse CT images show inhomogeneous splenic enhancement associated with ascites and bilateral pleural effusion. Note mild small bowel wall thickening (arrow) with mesenteric haziness

23 Diffuse Spleen Diseases

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23.5.4 Splenic Inflammation 23.5.4.1 Splenic Abscess

a

b

c

Fig. 23.10 Splenic abscess in a 35-year-old male. (a) Contrastenhanced transverse CT image shows a thick-walled cystic lesion with internal septa in the spleen (arrow). Note layered enhancement of the cyst wall and reactive ascites. (b) On 1-week follow-up after drain

catheter insertion, contrast-enhanced CT image (b) shows much decreased abscess cavity (arrowhead). (c) In a gross specimen, the thick-walled cystic lesion (curved arrow) with some hemorrhagic components is noted

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23.5.4.2 Tuberculosis

a

Fig. 23.11 Tuberculosis in a 35-year-old male. (a, b) Contrastenhanced transverse CT images show multiple low-attenuating masses (arrowheads) in the spleen, which are caseation necrosis. Note

b

low-attenuating mass-like lesion in the right diaphragm representing another infection focus (arrow)

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23.5.4.3 Calcified Tuberculosis

a

Fig. 23.12 Calcified tuberculosis in a 33-year-old female. (a) Grayscale ultrasound image shows dense hyperechoic lesions in the spleen (arrowheads). (b) Contrast-enhanced transverse CT image shows dense

b

calcified lesions in the spleen (arrows). Long-standing tuberculomas of caseation necrosis turn to calcified granulomas

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23.5.4.4 Tuberculosis Associated with Acquired Immunodeficiency Syndrome (AIDS)

a

Fig. 23.13 Tuberculosis associated with acquired immunodeficiency syndrome (AIDS) in a 35-year-old male. (a, b) Contrast-enhanced transverse CT images show low-attenuating lesion in the spleen

b

(arrow). Note multiple necrotic lymph nodes in the hepatoduodenal ligament (arrowheads) and periportal edema (curved arrow) associated with AIDS

23 Diffuse Spleen Diseases

23.5.4.5 Malaria

Fig. 23.14 Malaria in a 35-year-old male. Contrast-enhanced CT image shows nonspecific splenic enlargement. Sometimes malaria can cause massive splenomegaly and spontaneous splenic rupture

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23.5.4.6 Salmonella Infection

a

b

Fig. 23.15 Salmonella in a 43-year-old male. (a, b) Contrast-enhanced CT images show borderline splenomegaly, mild dilatation of small bowel (arrows), and reactive lymph nodes in the mesentery (arrowheads)

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23.5.4.7 Aspergillosis

a

Fig. 23.16 Aspergillus in a 27-year-old male with acute myelocytic leukemia. (a) Contrast-enhanced transverse CT shows a low-attenuating mass-like lesion (arrow) in the splenic hilum. Note small amount of

b

left pleural effusion. (b) On 1-week follow-up contrast-enhanced transverse CT, there is a communication between the splenic abscess and the stomach (arrowhead). Note air-fluid level in the splenic abscess

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23.5.4.8 Brucellosis

a

b

c

Fig. 23.17 Brucellosis in a 48-year-old male. (a–c) Contrast-enhanced transverse CT images show mild splenomegaly, periportal edema (arrow), edematous gallbladder wall thickening (curved arrow),

bilateral pleural effusion, and atelectases. Note reactive lymph nodes in the hepatoduodenal ligament and mesentery (arrowhead)

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23.5.5 Miscellaneous 23.5.5.1 Hemochromatosis

a

b

c

d

e

Fig. 23.18 Hemochromatosis in a 35-year-old male with repeated transfusion. (a, b) Note the signal drop of the spleen in in-phase MR (b) compared with opposed-phase MR (a). (c) On T2-weighted MR image, the spleen shows slightly high signal intensity compared to the liver, but

the difference is smaller than normal. (d) Diffusion-weighted MR image (b = 1,000, d) shows mild hyperintensity of the spleen which is slightly lower than normal spleen. (e) On contrast-enhanced MR image shows no abnormal signal change of the spleen

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23.5.5.2 Extramedullary Hematopoiesis

a

b

Fig. 23.19 Extramedullary hematopoiesis in a 37-year-old male. (a) Contrast-enhanced transverse CT shows multiple low-attenuating lesions in the spleen (arrows). (b) Note dark reddish color of the lesion in pathologic specimen

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23.5.5.3 Extramedullary Hematopoiesis

a

b

c

Fig. 23.20 Extramedullary hematopoiesis in a 44-year-old male. (a, b) Opposed-phase (a) and in-phase MR (b) images show multiple low-signal-intensity masses in the spleen. The signal intensity of the

mass is lower in in-phase MR compared to opposed-phase MR according to iron deposition in the mass. (c) On T2-weighed MR image, the masses show lower signal intensity than normal splenic parenchyma

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23.5.5.4 Gamna-Gandy Body

a

b

c

d

Fig. 23.21 Gamna-Gandy body in a 58-year-old female with liver cirrhosis. (a–c) In-phase (a), opposed-phase (b), and T2-weighted (c) MR images show disseminated dark signal intensity lesions in the spleen

according to the hemosiderin deposition in the spleen. (d) Gray-scale ultrasound image shows disseminated high-signal-intensity lesions in the spleen with underlying massive splenomegaly

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Suggested Reading

Burrill J, Williams CJ, Bain G, Conder G, Hine AL, Misra RR. Tuberculosis: a radiologic review. Radiographics. 2007;27(5): 1255–73. Wang CW, Yu CY, Peng YJ, Wang CY, Chang WC, Huang GS. Focal extramedullary haematopoiesis of the spleen: unusual MR appearance with pathological correlation. Br J Radiol. 2008;81(968): e211–e4. Jang JY, Kwon JH, Kim MJ, Rho BH, Lee MY. CT findings of malarial spleens. J Korean Soc Radiol. 2009;61(4):241–7. Pozo AL, Godfrey EM, Bowles KM. Splenomegaly: investigation, diagnosis and management. Blood Rev. 2009;23(3):105–11. Eruz ED, Birengel S, Azap A, Bozkurt GY (2011) A case of brucellosis presenting with multiple hypodense splenic lesions and bilateral pleural effusions. Case Rep Med: article ID 61454612 Yeom SK, Kim HJ, Byun JH, Kim AY, Lee MG, Ha HK. Abdominal aspergillosis: CT findings. Eur J Radiol. 2011;77(3):478–82. Hennedige T, Bindl DS, Bhasin A, Venkatesh SK. Spectrum of imaging findings in Salmonella infections. AJR Am J Roentgenol. 2012;198(6):W534–W9.

Warshauer DM, Lee JK. Imaging manifestations of abdominal sarcoidosis. AJR Am J Roentgenol. 2004;182(1):15–28. Sagoh T, Itoh K, Togashi K, Shibata T, Nishimura K, Minami S, Asato R, Noma S, Fujisawa I, Yamashita K. Gamna-Gandy bodies of the spleen: evaluation with MR imaging. Radiology. 1989;172(3):685–7. Poll LW, Koch JA, vom Dahl S, Sarbia M, Häussinger D, Mödder U. Gaucher disease of the spleen: CT and MR findings. Abdom Imaging. 2000;25(3):286–9. Georgiades CS, Neyman EG, Barish MA, Fishman EK. Amyloidosis: review and CT manifestations. Radiographics. 2004;24(2):405–16. Elsayes KM, Narra VR, Mukundan G, Lewis Jr JS, Menias CO, Heiken JP. MR imaging of the spleen: spectrum of abnormalities. Radiographics. 2005;25(4):967–82.

Benign Focal Lesions of the Spleen

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Yong Eun Chung

Contents 24.1

Hemangioma . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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24.2

Hamartoma . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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24.3

Lymphangioma . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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24.4

Littoral Cell Angioma . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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24.5

Sclerosing Angiomatoid Nodular Transformation (SANT) . . . . . . . . . . . . . . . . . . . . . . . . . . .

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24.6

Inflammatory Myofibroblastic Tumor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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24.7

Extramedullary Hematopoiesis. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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24.8

Pseudocyst, Epidermoid Cyst, and Echinococcal Cyst . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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24.9

Abscess (Bacterial, Mycobacterial, and Fungal) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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24.10 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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24.11 Illustrations: Benign Focal Lesions of the Spleen . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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Suggested Reading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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Y.E. Chung Department of Radiology, Yonsei University College of Medicine, Severance Hospital, Seoul, Republic of South Korea e-mail: [email protected] B.I. Choi (ed.), Radiology Illustrated: Hepatobiliary and Pancreatic Radiology, Radiology Illustrated, DOI 10.1007/978-3-642-35825-8_24, © Springer-Verlag Berlin Heidelberg 2014

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Benign focal lesions of the spleen can be categorized into benign tumor, cystic lesion, and infectious lesion. The most common benign tumor of the spleen is hemangioma, followed by hamartoma and lymphangioma. They often present as single lesions, but infrequently multiple lesions such as hemangiomatosis or lymphangiomatosis can be detected. They are usually found incidentally during imaging evaluation for various reasons because they usually do not make symptoms or clinically relevant signs. However, they infrequently cause symptoms by compressing adjacent organs, due to associated changes of splenic function such as anemia or thrombocytopenia, and also they rarely need emergent interventional or surgical intervention due to hemorrhage or rupture. Littoral cell angioma and sclerosing angiomatoid nodular transformation are recently defined benign spleenspecific disease entities. Although they can be presented with typical imaging findings, it is not easy to correctly diagnose because of its low incidence. Pseudocyst consists of approximately 90 % of non-parasite-related splenic cystic lesions. Epidermoid cyst which is a true cyst of congenital origin accounts for the rest of nonparasitic splenic cystic lesions. Echinococcal cyst may present with typical imaging findings, but it is rare outside the endemic area of echinococcus infection. Infectious disease can be accompanied with clinical symptoms such as fever, and medical history of the patient may be helpful for differentiating them from tumorous lesions. In daily practice, the radiologist is requested to make a differential diagnosis of focal splenic lesions: whether the lesion is benign or malignant and furthermore what the specific diagnosis is. If the incidental splenic lesion manifests with typical imaging findings, the differential diagnosis may be possible. But in many cases, it is not enough to make a differential diagnosis based solely on imaging findings, and clinical information such as previous history of extrasplenic malignancy, immune status (i.e., immunocompetent or immunocompromised), and changes in size of the focal lesion on follow-up imaging should be reviewed carefully. If there is any suspicious finding, recommendation of biopsy is feasible because a recent meta-analysis showed that splenic biopsy is not as dangerous as it has been thought, and the complication rate is similar to that of liver biopsy. In this chapter, we will review the pathophysiology, key microscopic findings, and typical imaging findings of benign focal lesions of the spleen.

24.1

Hemangioma

Hemangioma is the most common benign tumor in the spleen. Hemangioma is usually asymptomatic and found incidentally during imaging study for evaluation of other diseases. It can grow slowly and result in symptoms such as palpable mass in the left upper quadrant, hemorrhage, rupture, anemia, and thrombocytopenia. Rarely, it may

be associated with systemic angiomatosis such as Klippel-Trénaunay-Weber, Turner, Kasabach-Merritt-like, and Beckwith-Wiedemann syndromes. Microscopically, it consists of blood-filled space lined by endothelium. The size of the blood-filled space can be various which manifest from large (cavernous hemangioma) to very small (capillary hemangioma), although, cavernous hemangioma is more common. Capillary hemangiomas tend to manifest as solid masses, whereas cavernous hemangiomas are often accompanied with cystic components. Thrombosis, fibrosis, infarctions can be seen within the blood-filled space. Central punctuate calcifications are more commonly accompanied in solid hemangiomas, whereas peripheral curvilinear calcifications are frequently noted in cystic hemangiomas. On plain radiography, mass shadows and calcifications, if present, can be seen in the left upper quadrant in cases of sufficiently large hemangiomas. On ultrasonography (US), hemangioma manifests as a predominantly hyper-echoic mass or solid and cystic (complex) lesion and may be intrapancreatic or pedunculated. Calcifications can be noted as hyper-echoic foci with posterior shadowing. On noncontrast computed tomography (CT), hemangioma presents as low- to iso-attenuating well-defined mass. After contrast enhancement, small solid capillary hemangioma shows homogenous-marked enhancement. In cavernous hemangiomas with cystic component, enhancement is only seen in the solid component and sometimes shows discrete, mottled heterogeneous enhancement rather than typical central fill-in enhancement. On magnetic resonance (MR) imaging, hemangioma shows iso- to low signal intensity on T1-weighted image and high signal intensity on T2-weighted image. After administration of contrast media, the enhancement pattern is similar to that of CT. In both contrast-enhanced CT and MR imaging, typical peripheral globular enhancement which is clearly seen in hepatic hemangioma is often not evident. Predominantly solid hemangiomas should be differentiated from other solid splenic lesions such as hamartoma, metastasis, lymphoma, and angiosarcoma. Differential diagnosis of complex (solid and cystic) hemangiomas includes lymphangioma, hamartoma, and metastasis.

24.2

Hamartoma

Hamartoma is one of the vascular origin tumors in the spleen. As other benign splenic focal lesions, hamartoma is usually found incidentally without symptoms. If the hamartoma is large, palpable mass can be felt in the left upper quadrant and rarely can cause spontaneous rupture and hemorrhage. The origin of hamartoma is controversial, and malformed congenital lesion or reactive hyperplasia due to previous trauma is considered theories. Sometimes, hamartoma is related to other neoplastic diseases or tuberous sclerosis. Histologically, it consists of disorganized vascular channels with endothelial lining. Splenic red pulp-like stroma or fibrotic codes with or

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Benign Focal Lesions of the Spleen

without white pulp components exist within the lesion. Cystic change and rarely calcification can be also accompanied. On US, hamartoma manifests as a well-defined hyperechoic mass. On Doppler US, plenty of blood flow can be detected. On noncontrast CT, hamartoma usually appears iso- to hypo-attenuating compared to adjacent normal spleen, and after contrast media administration, it shows heterogeneous diffuse enhancement. Sometimes when the attenuation of the hamartoma is similar to the adjacent spleen on nonand post-contrast CT images, it may not be detected on CT. On MR, hamartoma commonly presents as iso-signal intensity on T1-weighted image and iso- to high signal intensity on T2-weighted image. On contrast-enhanced MR images, it demonstrates diffuse and heterogeneous enhancement in early phase and more uniform enhancement in delayed phase.

24.3

Lymphangioma

Lymphangioma is a relatively rare benign lesion in the spleen and is more frequently found in children. It can manifest as single or multiple lesions and are even associated with diffuse systematic lymphangiomatosis involving the liver, lung, retroperitoneum, and mediastinum. Most lymphangiomas do not present with clinical symptoms, but it can grow slowly causing symptoms mainly due to compression of adjacent organs, including left upper quadrant pain, palpable mass, nausea, vomiting, and hypertension. Microscopically, lymphangioma consists of variable-sized dilated lymphatic spaces lined by endothelium, filled with proteinaceous fluid. It can be divided into capillary, cavernous, and cystic lymphangiomas, based on the size of the cystic space. The most common type is cystic lymphangioma. On US, lymphangioma presents as well-defined unilocular or multiseptated cystic lesion. On Doppler US, splenic vessels can be detected in the cystic wall. CT shows a unilocular or multilocular low-attenuating, discrete lesion without enhancement. Peripheral curvilinear calcifications, which are a suggestive finding of lymphangioma, can be clearly noted on CT. On MR, lymphangioma often shows low signal intensity on T1-weighted image and heterogeneous high signal intensity on T2-weighted image with lowsignal-intensity internal septa. With internal hemorrhage or protein-rich fluid, the cystic component of lymphangioma may appear as iso- or hyperintense on T1-weighted image. After contrast enhancement, the cystic component of lymphangioma does not show any enhancement, while the internal septa shows enhancement. In rare cases, diffuse and prolonged enhancement during dynamic contrast MR is seen, possibly due to relatively small portion of cystic component and abundant intervening fibrous stroma. Asymptomatic lymphangioma does not need treatment. Symptomatic lymphangioma can be treated with less invasive methods such as percutaneous aspiration, sclerotherapy, or with partial or total splenectomy.

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24.4

Littoral Cell Angioma

Littoral cell angioma, which is originated from littoral cells, is a distinct disease entity of the spleen. They often manifest as multiple similar-sized nodules in the spleen, although cases of a single nodular lesion was also reported. Littoral cell angioma is usually diagnosed during evaluation of hypersplenism-related symptoms, and almost all patients have splenomegaly. Microscopically, littoral cell angioma is composed of anastomosing vascular channels of varying sizes, lined by tall or flat endothelial cells. Papillary fronds may protrude within the vascular channel. It has been thought as a benign lesion, but few cases with metastasis or histological evidence of malignancy have been reported. Imaging findings on US are nonspecific. They appear as multiple nodular lesions with variable echoes. The focal lesions may even be imperceptible and be seen only as heterogeneous echo texture. On CT, littoral cell angiomas manifest as iso-attenuating nodular lesions in noncontrast images and low-attenuating lesions in portal venous phase images. Infrequently, the nodular lesions appear iso-attenuating compared to adjacent normal spleen on delayed phase images, resulting in difficulty to percept the lesions. On MR, they have low signal intensity on T1-weighted images and high signal intensity on T2-weighted images. Infrequently, they show low signal intensity both on T1-weighted image and T2-weighted image, probably due to dense hemosiderin deposition within the cystic spaces. The differential diagnosis should include diseases which can present as multiple nodular lesions such as metastasis, lymphoma, angiosarcoma, hemangioma, tuberculosis, and fungal infection.

24.5

Sclerosing Angiomatoid Nodular Transformation (SANT)

SANT is a rare splenic tumor which is predominantly found in middle-aged women. Most patients are asymptomatic, but some present with abdominal pain, discomfort, or splenomegaly. The pathogenesis of SANT is still not known, although it has been thought that SANT comes from altered nodular hyperplasia of normal splenic red pulp framed with nonneoplastic fibrous stroma, resulting from vascular or inflammatory injury. Macroscopically, SANT appears as multiple angiomatoid nodules separated by fibrotic stroma. Microscopically, it consists of various vascular spaces lined by plump endothelial cells. In contrast to other vascular lesions such as hemangioma or littoral cell angioma, SANT is composed of three different vascular structures including capillaries, sinusoids, and small veins separated by fibrous stroma. On US, SANT presents as a heterogeneous nodular mass accompanied with rich flow signals on Doppler US. On CT, SANT appears as a well-defined solitary low-attenuating mass on noncontrast images with progressive centripetal

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enhancement in radiating pattern, which can be described as “spoke-wheel” appearance on contrast-enhanced CT images. In delayed phase, it presents as iso- or occasionally highattenuating mass compared to normal adjacent spleen. Necrosis, cystic change, or calcification is rarely accompanied. On T1-weighted MR images, SANT appears as a lowto iso-signal-intensity lesion. SANT shows heterogeneous low signal intensity on T2-weighted image, and similar enhancement pattern to that of CT is seen, probably due to dense fibrosis within the tumor. On dual-echo T1-weighted images, SANT shows heterogeneous low signal intensity on out-of-phase image, as a result of iron deposition within the angiomatoid nodules. On PET/CT, increased various levels of 18F-FDG uptake can be seen, and it can also grow on follow-up imaging, which makes it hard to differentiate it from primary or metastatic malignant lesions. Differential diagnosis includes other vascular lesions such as hemangioma, hamartoma, hemangioendothelioma, inflammatory myofibroblastic tumor, lymphoma, angiosarcoma, and metastasis.

marrow. Infrequently, it can be also developed due to vascular endothelial growth factors (VEGF) excreted by tumor. EMH in the spleen is shown as a well-defined mass, either solitary or multiple, with almost always accompanying splenomegaly. On US, EMH presents as well-circumscribed, iso- or hyper-echoic lesions, sometimes accompanied with low-echoic area within the lesion. On CT, EMH appears as low-attenuating mass on noncontrast images and shows no or slight enhancement after administration of contrast media. On MR, EMH manifests various signal intensities depending on the activity of hematopoiesis. Active EMH presents with intermediate signal intensity on T1-weighted image, high signal intensity on T2-weighted image, and slight enhancement on contrast-enhanced T1-weighted image, whereas inactive EMH shows low signal intensity on both T1- and T2-weighted images due to iron deposition or high signal intensity on both images due to fatty infiltration.

24.8 24.6

Inflammatory Myofibroblastic Tumor

Inflammatory myofibroblastic tumor (IMT) is an uncommon benign lesion which can be found in various organs. Splenic IMT is rarely found and present frequently as a solitary lesion but rarely as multiple well-defined nodular masses. Although IMT is histologically benign, it is thought to be potentially malignant because it can grow rapidly, invade adjacent structures, and show relatively high recurrence rate after resection. Although theories such as response to infectious or immunologic stimulus have been suggested, the etiology of IMT is still unknown. Microscopically, IMT consist of polymorphous inflammatory cell of histiocytes, plasma cells, and lymphocytes in fibroblastic stroma. On US, IMT appears as hypo-echoic well-circumscribed mass. On CT, it presents as a low-attenuating mass, occasionally with calcifications in noncontrast CT images and progressive delayed enhancement on contrast-enhanced images. On MR, IMT demonstrates low signal intensity on T1-weighted image, heterogeneous high signal intensity on T2-weighted image, and progressive enhancement on contrast-enhanced T1-weighted image.

24.7

Extramedullary Hematopoiesis

Extramedullary hematopoiesis (EMH) is defined as production of red blood cells in the extramedullary areas in the liver, spleen, lymph nodes, and paraspinal areas. EMH can be developed as a compensatory reaction to reduction of normally functioning red blood cells either due to massive destruction such as congenital hemolytic anemia or due to reduced production or function of red blood cells including myelodysplastic syndrome or infiltrative disease of the bone

Pseudocyst, Epidermoid Cyst, and Echinococcal Cyst

Cystic lesions in the spleen can be categorized as pseudocyst and true cysts depending on the presence or absence of lining epithelium. Pseudocyst consists of dense fibrotic wall without lining epithelium and may develop due to trauma or postinflammatory sequelae. Epidermoid cyst is a true cyst lined by stratified squamous epithelium. Only about one tenth of the non-parasite-related cyst is epidermoid cyst. Two third of epidermoid cysts are found within the spleen, whereas the others are found in the accessory spleen located in the pancreas. There is female predominance in cases of splenic epidermoid cysts, whereas the sex ratio is similar in intrapancreatic accessory spleens. Most patients do not have symptoms, and only less than 15 % of the patients have complications such as infection, rupture, or hemorrhage. These cystic lesions have common imaging findings. They manifest as well-demarcated anechoic or hypo-echoic lesions on US, non-enhancing low-attenuating lesions on CT, and high signal intensity lesions on T2-weighted MR images. Calcification can be accompanied more commonly in pseudocysts, whereas internal septation and trabeculation is relatively common in epidermoid cyst. In epidermoid cysts, internal echoes within the cyst can be seen, which might be due to cholesterol crystal or debris of previous hemorrhage. Echinococcal or hydatid cysts are one of the clinical manifestations of Echinococcus infection. The most common site of echinococcal cyst is the liver, followed by lung. Splenic echinococcal cyst is usually accompanied with systemic dissemination, and isolated splenic echinococcal cyst is very rare. Microscopically, the wall of echinococcal cyst consists of three layers: the thickest outermost layer or pericyst which works as a protective wall, the middle thin acellular laminated layer, and the innermost germinal layer. On US,

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Benign Focal Lesions of the Spleen

echinococcal cysts manifest differently depending on the stage of the disease. In active stage, echinococcal cysts appear either as pure cyst or cyst with septations (wheel-like appearance) or daughter cysts (rosette-like appearance). In transitional stage, echinococcal cysts have floating membrane within the cyst (water-lily sign). In the final inactive stage, thick calcified wall is accompanied. On CT, echinococcal cyst appears as a non-enhancing cystic lesion with/ without internal septation or daughter cyst. Calcified wall in inactive stage is well visualized on CT. On MR, echinococcal cyst shows high signal intensity on T2-weighted images with low-signal-intensity internal septation.

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and each represents fibrosis, inflammation, and necrosis, respectively. Other specific finding is bulls-eye appearance which consists of outer hypo-echoic ring (fibrosis) and central hyper-echoic area (inflammatory cell infiltration). After treatment, multifocal calcification can be seen as hyperechoic foci with posterior shadowing. On CT, similar to mycobacterial infection, multiple small low-attenuating lesions can be seen. On MR, fungal abscess appears as multifocal low-signal-intensity lesions both on T1-weighted image and T2-weighted image.

24.10 Summary 24.9

Abscess (Bacterial, Mycobacterial, and Fungal)

Most bacterial abscesses come from hematogenous spread, followed by superinfection of preexisting infarction or trauma. Splenic bacterial abscess is developed mainly in immunocompromised patients. Bacterial abscess usually manifests as a solitary lesion, whereas mycobacterial or fungal abscess appears as multifocal small lesions. On US, bacterial abscess appears as clustered cystic lesions or anechoic to hypo-echoic lesions with septation and internal debris. On CT, it is seen as a low-attenuating lesion with irregular margins on noncontrast images and occasionally enhance peripherally due to capsular formation on contrast-enhanced CT images. Internal septation or debris is often noted, and intralesional gas can be detected if gas-forming bacterial infection is accompanied. On MR, abscess shows low signal intensity on T1-weighted images and intermediate or high signal intensity on T2-weighted images. The enhancement pattern on MR is similar to that of CT. Mycobacterial abscess is caused by tuberculosis or Mycobacterium avium/intracellulare infection. It appears as multiple anechoic or hypo-echoic small lesions with either well- or ill-defined margin on US. On CT, mycobacterial abscess appears as multiple small low-attenuating lesions with poor enhancement. It is often difficult to differentiate these from other diseases which manifest as multiple small nodular lesions in the spleen such as fungal infection or metastasis. Detection of associated findings of mycobacterial infection such as mild splenomegaly, lymphadenopathy, ascites with peritoneal thickening, and absence of extrasplenic primary malignancy can be helpful for the differential diagnosis. Fungal infection in the spleen commonly occurs in immunocompromised patients. The most common causative organisms are Candida, Aspergillus, and Cryptococcus. Fungal abscess appears as multiple small nodular lesions on US and CT. Calcifications can be accompanied after treatment. On US, fungal abscess can appear as “wheelwithin-a-wheel” appearance, i.e., peripheral hyper-echoic ring, middle hypo-echoic ring, and inner hyper-echoic area,

1. Most of benign focal lesions of the spleen except infectious diseases are found incidentally. 2. It is not easy to differentiate between benign focal lesions from malignant lesions because benign focal lesions can also be newly seen or grow during imaging follow-up. 3. For the differential diagnosis of focal splenic lesions, both imaging findings and clinical assessment of the patient history are needed. 4. If firm differential diagnosis is not possible, splenic biopsy is feasible without significant increase of complication risk. 5. The most common benign focal lesion is hemangioma which often does not manifest typical peripheral globular central fill-in enhancement in the spleen. 6. Hamartoma consists of normal splenic red pulp and may be imperceptible in noncontrast CT or MR imaging. Increased blood flow signal on Doppler US may be helpful for diagnosis. 7. Predominantly cystic lesions with peripheral curvilinear calcifications are suggestive findings of lymphangioma. 8. Littoral cell angioma is a distinct disease entity of the spleen which present with multiple nodular lesions in the spleen. 9. Sclerosing angiomatoid nodular transformation (SANT) is a recently introduced, spleen-specific disease. On contrast-enhanced CT or MR, SANT demonstrates progressive centripetal enhancement in radiating pattern, which can be described as “spoke-wheel” appearance. 10. Inflammatory myofibroblastic tumor shows progressive delayed enhancement on contrast-enhanced imaging studies. 11. Extramedullary hematopoiesis may be included in the differential diagnosis when there is a non- or slightly enhancing lesion in the spleen in patients with massive red blood cell destruction or reduced red blood cell number/function. 12. Clinical history such as previous splenic trauma, infection or inflammation of the spleen, and trip to echinococcus endemic areas, is helpful for the differential diagnosis of cystic splenic lesions.

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24.11 Illustrations: Benign Focal Lesions of the Spleen 24.11.1 Cavernous Hemangioma, Predominantly Cystic a

b

c

Fig. 24.1 Cavernous hemangioma in a 69-year-old male. This lesion was found incidentally during evaluation of a gastric submucosal tumor. (a) Noncontrast transverse CT image shows a multiloculated low-attenuating lesion in the spleen. (b) On portal venous phase transverse CT image, the multiloculated cystic lesion does not show any

enhancement except internal septation (arrowheads). A lobulated nodular lesion is seen abutting the stomach upper body, which was confirmed as gastrointestinal submucosal tumor (arrow). (c) Photograph of gross specimen shows a multiloculated cystic lesion which was diagnosed as cavernous hemangioma

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24.11.2 Growing Hemangioma a

b

c

d

e

Fig. 24.2 Growing hemangioma in a 54-year-old female who underwent low anterior resection due to rectal cancer. (a) Serial follow-up of portal venous phase transverse CT images are shown. The left image was taken for preoperative evaluation of rectal cancer. There was no evidence of focal lesion in the spleen. The middle image was taken 2 years after the operation. A tiny low-attenuating lesion has newly developed in the spleen (arrowhead). The right image was taken

2.5 years after the operation. The low-attenuating lesion in the spleen has increased in size. On follow-up MR images taken 3 years after the operation, the splenic lesion shows further increase in its size. The lesion shows high signal intensity on T2-weighted image (b), low SI on T1-weighted image (c), and progressive centripetal enhancement on contrast-enhanced arterial (d) and delayed (e) phase T1-weighted images

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24.11.3 Cavernous Hemangioma. Predominantly Solid a

b

c

d

e

f

Fig. 24.3 Incidentally found splenic mass in a 39-year-old male. (a) Noncontrast transverse CT image shows an iso-attenuating focal splenic lesion compared to the adjacent spleen, resulting in difficulty of perception of the lesion (arrowheads). Portal venous (b) and delayed phase (c) transverse CT images show a well-defined mass with progressive homogeneous enhancement (d) T2-weighted transverse MR image shows a well-defined heterogeneous signal-intensity lesion in the

spleen. (e) On precontrast T1-weighted transverse MR image, the lesion is seen as iso-signal intensity compared to the spleen. On dynamic contrast-enhanced portal venous (f) and equilibrium (g) phase transverse MR images, the lesion shows progressive enhancement. (h) Photograph of gross specimen shows small blood-filled spaces within the lesion which was confirmed as a cavernous hemangioma

24

Benign Focal Lesions of the Spleen

g

Fig. 24.3 (continued)

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h

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Y.E. Chung

24.11.4 Ruptured Splenic Hemangioma a

b

c

Fig. 24.4 Ruptured splenic hemangioma in a 43-year-old female. She presented with left frank pain to the emergency department. (a) Noncontrast transverse CT image demonstrates high-attenuating fluid in the perisplenic area (arrowheads). The spleen shows heterogeneous attenuation. (b) On contrast-enhanced transverse CT image, multiple

low-attenuating lesions are noted in the spleen. Extravasation of contrast media is detected at the posterolateral aspect of the spleen (arrowhead), suggestive of active bleeding. (c) On photograph of a gross specimen, multiple cavernous hemangiomas were confirmed in the spleen

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24.11.5 Hamartoma a

b

c

d

Fig. 24.5 Splenic hamartoma in a 37-year-old male. He underwent left nephrectomy due to nephroblastoma when he was 6 years old. (a) On gray-scale ultrasonography, a nodular mass with heterogeneous echogenicity is noted in the spleen (arrowheads). (b) On noncontrast CT, splenic lesion is iso- to slightly low attenuated compared to the spleen. (c, d) On arterial (c) and portal venous (d) phase transverse CT

images, the lesion shows progressive heterogeneous enhancement. Focal poorly enhancing area is noted within the lesion, suggestive of cystic change (arrowhead). (e) On photography of a gross specimen, a well-defined reddish nodular lesion is noted. The final diagnosis is a splenic hamartoma

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e

Fig. 24.5 (continued)

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24.11.6 Lymphangioma a

b

c

d

e

Fig. 24.6 Lymphangioma in a 61-year-old male. (a) On gray-scale ultrasonography, a heterogeneous hyper-echoic lesion is seen in the subcapsular area of the spleen (arrow).(b) Noncontrast transverse CT image shows two low-attenuating lesions in the spleen (arrowheads).

(c, d) The lesions do not show any enhancement on contrast-enhanced arterial (c) and portal venous (d) phase images. (e) A gross specimen obtained after splenectomy shows a multiloculated nodular lesion composed with small dilated lymphatic spaces (arrowheads)

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24.11.7 Sclerosing Angiomatoid Nodular Transformation a

b

c

d

AP

PVP

Fig. 24.7 Sclerosing angiomatoid nodular transformation (SANT) in a 74-year-old male. (a) On ultrasonography, SANT appears as a wellcircumscribed heterogeneous low-echoic nodular lesion (arrow) with blood flow signals on Doppler ultrasonography (arrowheads). (b) On noncontrast transverse CT image, a well-defined nodular lesion is noted in the spleen (arrow). (c) Dynamic contrast-enhanced arterial (Left) and portal venous (Right) phase CT images show progressive-enhancing nodular lesion in the spleen. (d) On dual-echo T1-weighted MR image,

In phase

Out of phase

SANT shows low signal intensity on in-phase image (arrowheads). (e) On dynamic contrast-enhanced MR images, SANT presents with progressive centripetal enhancement in radiating pattern (spoke-wheel appearance: arrowheads). (f) T2-weighted transverse MR image shows heterogeneous low-signal-intensity nodular lesion in the spleen. (g) On 18 F-FDG PET scan, the splenic mass shows moderate increased 18FFDG uptake (arrow). (h) On photograph of a gross specimen, the mass appears as a pale yellowish solid lesion with multifocal hemorrhage

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e

Pre

f

h

Fig. 24.7 (continued)

AP

Delay

HBP

g

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24.11.8 Sclerosing Angiomatoid Nodular Transformation a

b

c

Fig. 24.8 Incidentally found sclerosing angiomatoid nodular transformation (SANT) in a 43-year-old female. (a) On contrast-enhanced transverse CT image, a small subcentimeter low-attenuating lesion is seen in the spleen (arrow). (b) Follow-up CT after 6 months, the focal

splenic lesion has increased in size (arrow). Under suspicion of malignancy, laparoscopic splenectomy was performed, and the lesion turned out to be a SANT. (c) On photograph of a gross specimen, the lesion appeared as a coalescent red-brown mass with dense fibrotic stroma

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24.11.9 Inflammatory Myofibroblastic Tumor a

b

AP

PVP

c

Fig. 24.9 Inflammatory myofibroblastic tumor (IMT) in a 67-year-old female. Splenic IMT was incidentally found for evaluation of lower abdominal pain. (a) On noncontrast transverse CT image, a slightly low-attenuating mass with calcification is seen in the spleen (arrowheads). (b) On dynamic contrast-enhanced arterial (left) and portal venous phase transverse CT (right) images, the splenic mass shows progressive delayed enhancement. (c) T2-weighted MR image

demonstrates heterogeneous low signal intensity in the lesion (arrows). (d) On dynamic contrast-enhanced MR images, the splenic mass shows progressive enhancement similar to the enhancement pattern of dynamic contrast-enhanced CT. (e) On 18F-FDG PET scan, increased 18 F-FDG uptake is noted in the splenic mass. (f) A splenectomy specimen shows a firm to hard well-demarcated, but nonencapsulated, nodular white lesion in the spleen

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d

Pre

e

Fig. 24.9 (continued)

AP

Delay

HBP

f

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Benign Focal Lesions of the Spleen

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24.11.10 Extramedullary Hematopoiesis a

c

b

d

e

Fig. 24.10 Extramedullary hematopoiesis of the spleen in a 71-yearold male. He underwent segmental resection of the small bowel due to a gastrointestinal stromal tumor. (a) Contrast-enhanced transverse CT image taken 1 year after the operation shows a well-defined small low-attenuating lesion in the spleen (arrowhead). (b–d) On CT scans obtained 2 years later, the splenic mass increased in size. On noncontrast transverse CT image (b), the mass shows iso-attenuation

compared to the spleen. On arterial (c) and portal venous (d) phase transverse CT images, the splenic mass shows slightly delayed enhancement. (e) T2-weighted transverse MR image shows a low-signal-intensity nodular lesion in the spleen (arrowhead). (f) The mass shows progressive and persistent enhancement on dynamic contrast-enhanced T1-weighted MR images. (g) Photograph of a gross specimen shows mass-forming extramedullary hematopoiesis (arrow)

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f

Pre

g

Fig. 24.10 (continued)

AP

Delay

HBP

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24.11.11 Pseudocyst a

b

c

Fig. 24.11 Pseudocyst in a 50-year-old female. (a) Noncontrast transverse CT image demonstrates a well-defined low-attenuating lesion in the spleen. (b) On contrast-enhanced portal venous phase transverse CT

image, a well-defined non-enhancing lesion is seen in the spleen. There is no internal septation or calcification. (c) A gross specimen obtained after splenectomy shows a unilocular cystic lesion

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24.11.12 Pseudocyst a

b

c

Fig. 24.12 Pseudocyst in a 38-year-old female. He underwent total thyroidectomy due to thyroid cancer 1 year ago. (a) On endoscopic ultrasonography, a multiseptated cystic lesion is noted in the spleen. Some of the cystic chambers show internal echogenicity (arrowheads). (b) Noncontrast transverse CT image demonstrates well-demarcated low-attenuating lesion in the spleen. There is no calcification. (c) On

contrast-enhanced portal venous phase image, a smoothly lobulated mass in the spleen is seen. The lesion has homogeneous low attenuation, and the internal septa which were seen in endoscopic ultrasonography are not shown. Splenectomy was performed and the lesion was confirmed as a pseudocyst with thick fibrous capsule

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24.11.13 Epidermoid Cyst a

b

c

d

e

Fig. 24.13 Epidermoid cyst in a 24-year-old female. (a) Noncontrast transverse CT image demonstrates well-defined low-attenuating lesion in the spleen. Focal calcification is noted in the cystic wall (arrowhead). (b) On contrast-enhanced portal venous phase transverse CT image, the cystic lesion does not show any enhancement. (c) On contrast-enhanced arterial phase T1-weighted MR image, the cystic lesion does not show

any enhancement. There is no evidence of internal septation. (d) On T2-weighted MR image, the cystic lesion shows high signal intensity. A thin linear septum is suspected in the peripheral portion of the cystic lesion (arrowhead). (e) Splenectomy specimen showed a unilocular cystic lesion which was confirmed as an epidermoid cyst

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24.11.14 Epidermoid Cyst a

b

c

Fig. 24.14 Epidermoid cyst in a 25-year-old female. This lesion was incidentally found during evaluation of pelvic inflammatory disease. (a) Noncontrast transverse CT image shows a lobulated low-attenuating lesion in the spleen. (b) Contrast-enhanced transverse CT image

demonstrates a lobulated cystic lesion with internal septa. (c) A gross specimen obtained after splenectomy shows a multilocular cystic lesion in the spleen. The final diagnosis was an epidermoid cyst

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24.11.15 Bacterial Abscess a

b

c

d

Fig. 24.15 Splenic abscess in a 52-year-old male. He underwent cardiac surgery due to tetralogy of Fallot when he was a child. He was referred for abdominal ultrasonography for left frank pain and fever. (a) On gray-scale ultrasonography, a heterogeneous low-echoic lesion in the inferior aspect of the spleen (arrowheads) is seen. (b) On contrastenhanced transverse CT image, an ill-defined low-attenuating lesion with necrotic change is noted in the spleen. A splenic abscess was

suspected and antibiotic therapy was started immediately. (c) On follow-up contrast-enhanced transverse CT 1 week after start of antibiotic treatment, splenic abscess has increased in size and internal necrosis also has progressed. After follow-up CT scan, percutaneous drainage catheter was inserted for treatment. (d) Contrast-enhanced transverse CT image 1 month later demonstrates the decreased extent of the splenic abscess

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24.11.16 Mycobacterial Abscess a

b

c

d

Fig. 24.16 Mycobacterial abscess in a 27-year-old female. (a) On chest CT, tree-in-bud appearance is noted in both lobes of lung, suggestive of active tuberculosis. (b) On gray-scale ultrasonography, multiple small low-echoic lesions are detected in the spleen (arrowheads). (c) Contrast-enhanced transverse CT image demonstrates multiple

low-attenuating lesions in the spleen. (d) Noncontrast transverse CT image, which was taken 5 months after initiation of antituberculosis medication, shows multifocal calcifications in the spleen probably as a result of inflammatory sequelae of tuberculosis

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Benign Focal Lesions of the Spleen

24.11.17 Fungal Abscess

Fig. 24.17 Fungal abscess in a 20-year-old female. She was diagnosed as lymphoma and had received chemotherapy for 10 months. She was referred for abdominal CT for fever-focus evaluation. On contrastenhanced CT image, innumerable low-attenuating lesions are detected in the spleen. Several peripherally enhancing low-attenuating nodular lesions are also seen in the liver (arrowheads). Under the guidance of ultrasonography, biopsy was performed at the spleen, and candidiasis was confirmed

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Suggested Reading Akhan O, Koroglu M. Hydatid disease of the spleen. Semin Ultrasound CT MR. 2007;28(1):28–34. Lee H, Maeda K. Hamartoma of the spleen. Arch Pathol Lab Med. 2009;133(1):147–51. Warshauer DM, Hall HL. Solitary splenic lesions. Semin Ultrasound CT MR. 2006;27(5):370–88. Ros PR, Moser Jr RP, Dachman AH, Murari PJ, Olmsted WW. Hemangioma of the spleen: radiologic pathologic correlation in ten cases. Radiology. 1987;162(1 Pt 1):73–7. Falk S, Stutte HJ, Frizzera G. Littoral cell angioma. A novel splenic vascular lesion demonstrating histiocytic differentiation. Am J Surg Pathol. 1991;15(11):1023–33. Safran D, Welch J, Rezuke W. Inflammatory pseudotumors of the spleen. Arch Surg. 1991;126(7):904–8. Shirkhoda A, Freeman J, Armin AR, Cacciarelli AA, Morden R. Imaging features of splenic epidermoid cyst with pathologic correlation. Abdom Imaging. 1995;20(5):449–51. Ferrozzi F, Bova D, Draghi F, Garlaschi G. CT findings in primary vascular tumors of the spleen. AJR Am J Roentgenol. 1996; 166(5):1097–101. Irie H, Honda H, Kaneko K, Kuroiwa T, Fukuya T, Yoshimitsu K, Aibe H, Hirakata R, Horie Y, Maeda T, et al. Inflammatory pseudotumors of the spleen: CT and MRI findings. J Comput Assist Tomogr. 1996;20(2):244–8. Ramani M, Reinhold C, Semelka RC, Siegelman ES, Liang L, Ascher SM, Brown JJ, Eisen RN, Bret PM. Splenic hemangiomas and hamartomas: MR imaging characteristics of 28 lesions. Radiology. 1997;202(1):166–72. Tsitouridis J, Stamos S, Hassapopoulou E, Tsitouridis K, Nikolopoulos P. Extramedullary paraspinal hematopoiesis in thalassemia: CT and MRI evaluation. Eur J Radiol. 1999;30(1): 33–8. Polat P, Kantarci M, Alper F, Suma S, Koruyucu MB, Okur A. Hydatid disease from head to toe. Radiographics. 2003;23(2): 475–94; quiz 536–477. Solomou EG, Patriarheas GV, Mpadra FA, Karamouzis MV, Dimopoulos I. Asymptomatic adult cystic lymphangioma of the spleen: case report and review of the literature. Magn Reson Imaging. 2003;21(1):81–4. Takayama A, Nakashima O, Kobayashi K, Kojiro M. Splenic lymphangioma with papillary endothelial proliferation: a case report and review of the literature. Pathol Int. 2003;53(7):483–8. Abbott RM, Levy AD, Aguilera NS, Gorospe L, Thompson WM. From the archives of the AFIP: primary vascular neoplasms of

Y.E. Chung the spleen: radiologic-pathologic correlation. Radiographics. 2004;24(4):1137–63. Levy AD, Abbott RM, Abbondanzo SL. Littoral cell angioma of the spleen: CT features with clinicopathologic comparison. Radiology. 2004;230(2):485–90. Martel M, Cheuk W, Lombardi L, Lifschitz-Mercer B, Chan JK, Rosai J. Sclerosing angiomatoid nodular transformation (SANT): report of 25 cases of a distinctive benign splenic lesion. Am J Surg Pathol. 2004;28(10):1268–79. Kamaya A, Weinstein S, Desser TS. Multiple lesions of the spleen: differential diagnosis of cystic and solid lesions. Semin Ultrasound CT MR. 2006;27(5):389–403. Chang WC, Liou CH, Kao HW, Hsu CC, Chen CY, Yu CY. Solitary lymphangioma of the spleen: dynamic MR findings with pathological correlation. Br J Radiol. 2007;80(949):e4–e6. Tatli S, Cizginer S, Wieczorek TJ, Ashley SW, Silverman SG. Solitary littoral cell angioma of the spleen: computed tomography and magnetic resonance imaging features. J Comput Assist Tomogr. 2008;32(5):772–5. Huynh MQ, Barth P, Sohlbach K, Neubauer A, Gorg C. B-mode ultrasound and contrast-enhanced ultrasound pattern of focal extramedullary hematopoiesis of the spleen in a patient with myeloproliferative disease. Ultraschall Med. 2009;30(3):297–9. Subhawong TK, Subhawong AP, Kamel I. Sclerosing angiomatoid nodular transformation of the spleen: multimodality imaging findings and pathologic correlate. J Comput Assist Tomogr. 2010;34(2): 206–9. Hudson JB, Murad FM, Kunkel JE, Collins BT. Endoscopic ultrasound guided fine-needle aspiration of a splenic hemangioma with extramedullary hematopoiesis. Diagn Cytopathol. 2011. doi:10.1002/ dc.21862. McInnes MD, Kielar AZ, Macdonald DB. Percutaneous image-guided biopsy of the spleen: systematic review and meta-analysis of the complication rate and diagnostic accuracy. Radiology. 2011;260(3): 699–708. Chen YY, Shyr YM, Wang SE. Epidermoid cyst of the spleen. J Gastrointest Surg. 2012;17(3):555–61. Kim HJ, Kim KW, Yu ES, Byun JH, Lee SS, Kim JH, Lee JS. Sclerosing angiomatoid nodular transformation of the spleen: clinical and radiologic characteristics. Acta Radiol. 2012;53(7):701–6. Krl EA, Orhan D, Haliloglu M, Karnak I. Invasive inflammatory myofibroblastic tumor of the spleen treated with partial splenectomy in a child. J Pediatr Hematol Oncol. 2012;34(4):e131–e3. Raman SP, Singhi A, Horton KM, Hruban RH, Fishman EK. Sclerosing angiomatoid nodular transformation of the spleen (SANT): multimodality imaging appearance of five cases with radiology-pathology correlation. Abdom Imaging. 2013;38(4): 827–34.

Malignant Focal Lesions of the Spleen

25

Jee Young Son and Hyunsik Woo

Contents 25.1

Angiosarcoma . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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25.2

Lymphoma . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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25.3

Metastasis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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25.4

Summary. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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25.5

Illustrations: Malignant Focal Lesions of the Spleen . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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Suggested Reading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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J.Y. Son • H. Woo (*) Department of Radiology, Seoul National University Hospital, Seoul, Republic of Korea e-mail: [email protected]; [email protected] B.I. Choi (ed.), Radiology Illustrated: Hepatobiliary and Pancreatic Radiology, Radiology Illustrated, DOI 10.1007/978-3-642-35825-8_25, © Springer-Verlag Berlin Heidelberg 2014

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Malignant tumors of the spleen are uncommon, and primary splenic malignancies are extremely rare. The most common splenic malignancy is probably lymphoma, and it is usually a secondary involvement of systemic lymphoma. Primary splenic angiosarcoma is the second most common primary malignant tumor of the spleen following lymphoma. Spleen is an infrequent site for metastatic disease and usually appear late in the course of disseminated cancer. Radiologic findings are usually nonspecific, making correct diagnosis harder. Therefore, consideration of clinical findings and situation is mandatory for differential diagnosis.

25.1

Angiosarcoma

Angiosarcoma is a malignancy of vascular origin and is characterized by masses of endothelial cells with cellular atypia and anaplasia. Primary splenic angiosarcoma is rare, but it is the second most common primary malignant tumor of the spleen following lymphoma. It is found more frequently in older patients with no gender predilection. Unlike angiosarcomas of the liver, association with exposure to thorium dioxide (Thorotrast), arsenic, or vinyl chloride has not been documented. Symptoms and findings at initial presentation include abdominal pain, splenomegaly, and hemoperitoneum due to spontaneous rupture, anemia, and thrombocytopenia. The tumor commonly metastasizes to the liver, lung, and lymph nodes. Prognosis of angiosarcoma is poor with a mean survival time usually less than a year. CT images may demonstrate an enlarged spleen with hypoattenuating lesions on noncontrast CT. Areas of high attenuation on noncontrast CT image may represent acute hemorrhage or hemosiderin deposits. Contrast enhancement of angiosarcoma may be similar to that of hepatic cavernous hemangioma, although the pattern of enhancement is variable. MRI findings show general features of vascular tumors and hemorrhagic masses. The signal intensities on both T1and T2-weighted images may vary, depending on the age of hemorrhage and presence of necrosis. Areas of low signal intensity on MRI represent siderotic nodules. Tumor usually enhances intensely after contrast media injection and may show fill-in pattern of enhancement similar to hemangioma.

25.2

Lymphoma

Lymphoma is probably the most common splenic malignancy and is usually a secondary involvement of systemic lymphoma. Primary splenic lymphomas are rare, and most of them are non-Hodgkin’s lymphomas. The most common

finding is splenomegaly, but it may be absent in up to onethird of lymphoma patients. There are two patterns of splenic involvement of lymphoma. In case of diffuse involvement or infiltration, enhanced CT image can show diffuse or infiltrative areas of poor enhancement. US may depict inhomogeneity of parenchymal echogenicity, but may not show any radiological abnormalities. Splenic lymphoma can also appear as focal lesions, showing masses or nodules of heterogeneous low echogenicity on US, low attenuation on noncontrast CT image, and poor enhancement after contrast media injection. MRI findings are nonspecific and similar to those of metastases from other primary malignancies. Typically, splenic lymphomas are hypointense or nearly isointense on T1-weighted images and hyperintense on T2-weighted images. Splenic lymphomas can be better depicted with contrast enhancement as lymphoma shows poor enhancement in contrast to background parenchymal enhancement of the spleen.

25.3

Metastasis

Spleen is an infrequent site for metastatic disease, although the frequency of splenic metastases may have been underestimated as they are often asymptomatic and usually appear late in the course of disseminated cancer. Solitary metastases to the spleen are rare. Common primary malignancies of splenic metastases are breast, lung, colorectal, ovarian, and gastric carcinomas and malignant melanomas. Solitary splenic metastasis occurs most often in ovarian carcinomas. Radiologic findings are nonspecific and similar to those of metastases of other organs. Splenic metastases are typically presented as lesions of low echogenicity on US, low attenuation on portal phase CT image, low signal intensity on T1-weighted MRI, and high signal intensity on T2-weighted MRI. MRI is more accurate for the detection of splenic metastases with hemorrhage or necrosis.

25.4

Summary

1. Malignant focal lesions in the spleen are rare and usually show nonspecific radiologic findings. 2. The most common splenic malignancy is probably lymphoma, followed by splenic angiosarcoma. 3. Splenic metastasis are uncommon and usually appear late in the course of disseminated cancer. 4. Splenic angiosarcomas show radiologic features of vascular tumors and hemorrhagic masses. 5. Splenic lymphomas and metastases show usual radiologic features of metastatic lesions of other organs.

25

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25.5

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25.5.1 Splenic Angiosarcoma with Spontaneous Rupture a

b

Fig. 25.1 Splenic angiosarcoma with spontaneous rupture in a 41-year-old male. (a) Noncontrast transverse CT image shows acute hematoma (short arrow) in the perisplenic space and hemoperitoneum in the perihepatic space (long arrow). A large mass lesion is also noted

in the spleen. The portion of high attenuation (arrowheads) in the tumor suggests intratumoral hemorrhage. (b) Arterial (left) and portal (right) phase transverse CT images show peripheral enhancement of the mass (arrowheads)

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25.5.2 Splenic Angiosarcoma Involving Whole Spleen

Arterial

Portal

Delayed

Coronal MPR

Fig. 25.2 Splenic angiosarcoma in a 33-year-old female. Dynamic contrast-enhanced transverse CT images demonstrate a heterogeneously enhancing mass-like lesion replacing nearly whole portion of the enlarged spleen

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Malignant Focal Lesions of the Spleen

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25.5.3 Splenic Angiosarcoma: MR Finding a

b

Fig. 25.3 Splenic angiosarcoma in a 63-year-old male. (a) T2-weighted transverse MRI (left) shows multiple masses (arrowheads) of variable signal intensities in the spleen. A bright dot (arrow) on fat-saturated T1-weighted transverse MRI (right) suggests intratumoral hemorrhage. (b) Contrast-enhanced portal phase T1-weighted transverse MRI

(left and middle) clearly depict multiple splenic masses (arrowheads). Delayed phase (right) T1-weighted transverse MRI taken at 20 min after contrast media injection shows a delayed fill-in enhancement pattern of the masses

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25.5.4 Splenic Lymphoma with Diffuse Involvement

Fig. 25.4 A 72-year-old female with diffuse large B-cell lymphoma. Splenomegaly with diffuse low attenuation is noted both on arterial (left) and portal (right) phase CT images. There is no discernible focal lesion in the spleen

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Malignant Focal Lesions of the Spleen

799

25.5.5 Splenic Lymphoma Appeared as a Focal Mass a

b

Fig. 25.5 A 77-year-old female with diffuse large B-cell lymphoma. (a) Contrast-enhanced transverse CT image demonstrates a 2.5 cm hypoattenuating mass (arrow) in the spleen. (b) The lesion (arrows) shows heterogeneous high signal intensity on T2-weighted transverse

MRI (left), slightly low signal intensity on fat-saturated T1-weighted transverse MRI (middle), and poor enhancement after gadolinium injection (right). Note better visualization of the lesion on the enhanced image

800

J.Y. Son and H. Woo

25.5.6 Splenic Metastasis of Nasopharyngeal Carcinoma: CT and US Findings a

b

Fig. 25.6 Splenic metastasis of nasopharyngeal carcinoma in a 37-year-old male. (a) Contrast-enhanced transverse CT image shows a 2.5 cm hypoattenuating mass (arrow) in the spleen. (b) On grayscale US, the lesion appears as a hypoechoic lesion (arrow)

25

Malignant Focal Lesions of the Spleen

801

25.5.7 Splenic Metastasis of Endometrial Adenocarcinoma: CT and MRI Findings a

b

Fig. 25.7 Splenic metastasis of endometrial adenocarcinoma in a 59-year-old female. (a) Arterial (left) and portal (right) phase transverse CT images demonstrate a 3 cm heterogeneously and poorly enhancing mass (arrows) in the spleen. (b) The lesion (arrows) shows heterogeneous high signal intensity on T2-weighted transverse MRI

(left) and heterogeneous low signal intensity on T1-weighted transverse MRI (right). (c) Arterial (left) and portal (right) phases of enhanced MRI depict heterogeneous enhancement of the lesion, which is similar to that on the enhanced CT images

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J.Y. Son and H. Woo

c

Fig. 25.7 (continued)

25

Malignant Focal Lesions of the Spleen

803

25.5.8 Splenic Metastasis of Hepatocellular Carcinoma: CT and MRI Findings a

b

Fig. 25.8 Splenic metastasis of hepatocellular carcinoma in a 56-yearold male. (a) Arterial (left) and portal (right) phase CT images show a 2 cm poorly enhancing mass lesion (arrows) in the spleen. (b) Liver MRI taken on 1 month after CT. The diameter of the lesion (arrows) has increased from 2 to 3 cm. T2-weighted transverse MRI (left) shows heterogeneous signal intensity, and T1-weighted transverse MRI (right) shows nearly same signal intensity with that of the spleen. (c) With contrast media enhancement using Primovist, the lesion (arrows) is

poorly enhancing on the dynamic phases and demonstrates mild high signal intensity (arrowhead) on the hepatobiliary phase. This high signal intensity on the hepatobiliary phase is thought to be correlated with the hepatocellular nature of the metastatic lesion. Note that this splenic metastasis of hepatocellular carcinoma does not show typical enhancement patterns of hepatic hepatocellular carcinoma such as arterial hypervascularity and delayed washout

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c

Fig. 25.8 (continued)

Arterial

Portal

Equilibrium

Hepatobiliary

25

Malignant Focal Lesions of the Spleen

Suggested Reading Giovagnoni A, Giorgi C, Goteri G. Tumours of the spleen. Cancer Imaging. 2005;5(1):73–7. Morgenstern L, Rosenberg J, Geller SA. Tumors of the spleen. World J Surg. 1985;9(3):468–76. Freeman JL, Jafri SZ, Roberts JL, et al. CT of congenital and acquired abnormalities of the spleen. Radiographics. 1993;13(3):597–610. Saboo SS, Krajewski KM, O’Regan KN, et al. Spleen in haematological malignancies: spectrum of imaging findings. Br J Radiol. 2012;85(1009):81–92. doi:10.1259/bjr/31542964. Epub 2011 Nov 17. Abbott RM, Levy AD, Aguilera NS, et al. From the archives of the AFIP: primary vascular neoplasms of the spleen: radiologicpathologic correlation. Radiographics. 2004;24(4):1137–63.

805 Vrachliotis TG, Bennett WF, Vaswani KK, et al. Primary angiosarcoma of the spleen–CT, MR, and sonographic characteristics: report of two cases. Abdom Imaging. 2000;25(3):283–5. Hamid KS, Rodriguez JA, Lairmore TC. Primary splenic angiosarcoma. JSLS. 2010;14(3):431–5. doi:10.4293/1086808 10X12924466006521. Neuhauser TS, Derringer GA, Thompson LD, et al. Splenic angiosarcoma: a clinicopathologic and immunophenotypic study of 28 cases. Mod Pathol. 2000;13(9):978–87. Lam KY, Tang V. Metastatic tumors to the spleen: a 25-year clinicopathologic study. Arch Pathol Lab Med. 2000;124(4):526–30.

Trauma and Post-treatment Complications of the Spleen

26

Ji Hoon Park and Kyoung Ho Lee

Contents 26.1

Splenic Trauma . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

808

26.2

Post-treatment Complication . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

808

26.3

Summary. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

809

26.4

Illustrations: Trauma and Post-treatment Complications of the Spleen . . . . . . . . . . . . . . . . .

810

Suggested Reading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

817

J.H. Park • K.H. Lee (*) Department of Radiology, Seoul National University Bundang Hospital, Seongnam-Si, Republic of Korea e-mail: [email protected]; [email protected] B.I. Choi (ed.), Radiology Illustrated: Hepatobiliary and Pancreatic Radiology, Radiology Illustrated, DOI 10.1007/978-3-642-35825-8_26, © Springer-Verlag Berlin Heidelberg 2014

807

808

J.H. Park and K.H. Lee

The spleen is relatively fragile organ due to its complex ligamentous attachments, minimally mobile vascular pedicle, and spongy parenchymal consistency constrained by a thin fibrous capsule. Despite the fact that it is at least partially protected by the ribcage, inspiratory excursion may inferiorly displace the spleen to a more exposed subcostal position. The retroperitoneum and the diaphragm provide inflexible surfaces against which the spleen may be compressed. Isolated splenic injuries have been known to rarely result in mortality. However, in more recent studies, mortality rates following all causes of splenic trauma have been reported up to 10 %. In a retrospective study from a single center, isolated splenic injury consisted about 10 % of possibly survivable injuries. Splenic injury accounts for 25 % of all solid abdominal organ injuries. It may arise from a variety of mechanisms, grossly divided into penetrating trauma, blunt trauma, and iatrogenic injury.

26.1

more common than intraparenchymal hematomas in trauma patients, appear crescentic in shape between the splenic parenchyma and capsule and may exert a mass effect. Active extravasation or pseudoaneurysm is the most acute finding in splenic trauma, and it appears as irregular or linear hyperattenuation which is similar to the attenuation of adjacent vascular structures. It may be located at the splenic parenchyma and subcapsular space, or within the peritoneal cavity. Arteriovenous fistulas of the splenic vasculature may be difficult to distinguish from pseudoaneurysms due to its similar appearance on CT. Ultrasonography has certain advantages over CT that it can be performed at the bedside, and it does not use ionizing radiation. However, due to the usual limitations of ultrasound in the left upper quadrant, the accuracy of ultrasonography in the assessment of splenic injury is relatively lower than that of CT. Therefore, the major role of ultrasonography is for the postoperative patient and for long-term follow-up of patients treated conservatively.

Splenic Trauma

The most common cause of blunt splenic trauma is motor vehicle collisions which causes both decelerating force exerted by the seat belt and direct compression of the abdomen by the steering wheel or dashboard. Considering the complex injury mechanism of motor vehicle accidents, it is not surprising that high levels of concomitant injuries occur in patients with blunt splenic trauma.

26.1.1 Imaging Technique Computed tomography (CT) before and during the arterial and delayed phase of intravenous contrast enhancement has become the gold standard for the diagnosis of splenic trauma. It plays a key role in selecting patients with splenic vascular injury who may be treated with transcatheter therapy and potentially improves the success rate of nonsurgical management. The CT findings of splenic injury include contusion, hematoma, laceration, and extravasation of contrast and associated vascular injuries. Splenic contusions appear as illdefined areas of hypoattenuation, while splenic lacerations are well-defined, linear, or branching hypoattenuations. Congenital splenic clefts are common causes that can be mistaken for lacerations. Although they are sometimes very difficult to differentiate from lacerations, splenic clefts are usually located along the medial surface of the spleen while most lacerations originate from the lateral surface. Location wise, the splenic hematoma can be subcapsular, intraparenchymal, and perisplenic. Regardless of its location, hematomas are hyperattenuating relative to normal splenic parenchyma on noncontrast scan. Subcapsular hematomas,

26.1.2 Grading of Splenic Injury A splenic injury scale was proposed by the American Association for the Surgery of Trauma (AAST), and it had been widely used in multiple trauma centers (see Table 26.1). Similar CT-based grading systems were proposed to reflect the AAST scale. However, several studies have shown that the traditional AAST injury grade and the CT-based injury grading system derived from it are unreliable predictors of patient outcome. Marmery et al. proposed a new grading system that specifically incorporates the findings of active bleeding or splenic vascular injury, including pseudoaneurysm and arteriovenous fistula, and suggested that it is more helpful for triage of patients who need splenic arteriography and surgery.

26.2

Post-treatment Complication

26.2.1 Post-operative Complication It has been reported that up to 40 % of all splenectomies are performed for iatrogenic injury. Excessive traction, injudicious use of retractors, and direct trauma during operations are typical mechanisms of injury. Splenic injury may occur in left hemicolectomy, open anti-reflux procedures, left nephrectomy, gastrectomy, and during exposure and reconstruction of the proximal abdominal aorta and its branches. The risk of injury to the spleen is higher in patients who have previously undergone abdominal surgery, in the elderly, and in obese patients.

26 Trauma and Post-treatment Complications of the Spleen

809

Table 26.1 American Association for the Surgery of Trauma (AAST) splenic injury scale Gradea I II

Injury type Hematoma Laceration Hematoma Laceration

III

Hematoma

IV

Laceration Laceration

V

Laceration Vascular

Description of injury Subcapsular, 25 % of spleen) Completely shattered spleen Hilar vascular injury with devascularized spleen

a

Advance one grade for multiple injuries up to grade III

26.2.2 Post-procedural Complication

26.3

Summary

Splenic injury is a rare complication of colonoscopy. However, given the increasing use of colonoscopy, it is worthy to be aware of this rare but potentially fatal complication of colonoscopy. Splenic injury might also inadvertently occur during percutaneous nephrolithotomy. Ultrasound guidance during the procedure significantly reduces the risk of splenic injury. Cross-sectional imaging might be helpful in planning subcostal puncture by clarification of structures adjacent to the kidney. The possibility of splenic injury should be an immediate consideration in the event of hemodynamic instability after left-sided percutaneous nephrolithotomy.

1. Splenic injury accounts for 25 % of all solid abdominal organ injuries. 2. Computed tomography is the gold standard for the diagnosis of splenic trauma. 3. The major role of ultrasonography in splenic trauma is for the postoperative patient and for long-term follow-up of patients treated conservatively. 4. Splenic injury may occur in a variety of operative procedures. 5. Splenic injury is a rare complication of colonoscopy and percutaneous nephrolithotomy.

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26.4

J.H. Park and K.H. Lee

Illustrations: Trauma and Post-treatment Complications of the Spleen

26.4.1 Splenic Contusion

Fig. 26.1 Splenic contusion in a 48-year-old male. Contrast-enhanced transverse CT shows a focal low-attenuating lesion (arrow) in the spleen. The lesion has disappeared on follow-up CT

26 Trauma and Post-treatment Complications of the Spleen

26.4.2 Subcapsular Hematoma

Fig. 26.2 Subcapsular hematoma in a 33-year-old male. Contrastenhanced transverse CT shows a crescentic hypoattenuating lesion (arrows) at the medial surface of the spleen

811

812

26.4.3 Splenic Laceration

Fig. 26.3 Splenic laceration in a 17-year-old male who was involved in a traffic accident. Contrast-enhanced transverse CT shows a linear hypoattenuating lesion extending to the splenic hilum (arrows). Although the laceration involved splenic hilum, there is no evidence of injury in the splenic vascular pedicle. He did not show hemodynamic instability and recovered uneventfully with conservative treatment

J.H. Park and K.H. Lee

26 Trauma and Post-treatment Complications of the Spleen

26.4.4 Splenic Infarction

Fig. 26.4 Splenic infarction in a four-year-old male. At contrastenhanced transverse CT image, low-attenuating area is noted at the superoposterior part of the spleen (arrows)

813

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26.4.5 Splenic Hematoma and Active Bleeding a

b

c

Fig. 26.5 Splenic hematoma and active bleeding in a 34-year-old female who attempted suicide. (a) Precontrast transverse CT image shows hemoperitoneum (asterisks) and a splenic hematoma (arrows).

(b, c) Arterial (b) and portal venous phase (c) transverse CT images show hemoperitoneum (asterisks) and extravasation of contrast agent (arrowheads), representing active bleeding

26 Trauma and Post-treatment Complications of the Spleen

815

26.4.6 Splenic Rupture a

b

c

Fig. 26.6 Splenic rupture in a 35-year-old female who was involved in a motorcycle accident. (a) Contrast-enhanced coronal CT image shows a pseudoaneurysm (arrow) in the spleen. (b, c) Angiography clearly

shows the pseudoaneurysm (arrows) (b), which was treated by coil embolization (curved arrows) (c)

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26.4.7 Post-operative Complication a

Fig. 26.7 Postoperative complication in a 53-year-old male who underwent total gastrectomy. Postoperative CT was performed for persistent abdominal pain and fever. (a) Contrast-enhanced transverse CT

b

shows segmental splenic infarction (arrows). (b) Contrast-enhanced transverse CT image 4 months later shows atrophy of the infarcted area (arrows)

26 Trauma and Post-treatment Complications of the Spleen

Suggested Reading Boscak A, Shanmuganathan K. Splenic trauma: what is new? Radiol Clin North Am. 2012;50:105–22. Cassar K, Munro A. Iatrogenic splenic injury. J R Coll Surg Edinb. 2002;47:731–41. Wilson RH, Moorehead RJ. Management of splenic trauma. Injury. 1992;23:5–9. Becker CD, Spring P, Glattli A, et al. Blunt splenic trauma in adults: can CT findings be used to determine the need for surgery? AJR Am J Roentgenol. 1994;162:343–7. Kohn JS, Clark DE, Isler RJ, et al. Is computed tomographic grading of splenic injury useful in the nonsurgical management of blunt trauma? J Trauma. 1994;36:385–9; discussion 390. Sutyak JP, Chiu WC, D’Amelio LF, et al. Computed tomography is inaccurate in estimating the severity of adult splenic injury. J Trauma. 1995;39:514–8. Davis KA, Fabian TC, Croce MA, et al. Improved success in nonoperative management of blunt splenic injuries: embolization of splenic artery pseudoaneurysms. J Trauma. 1998;44:1008–13; discussion 1013–1005. Robert M, Maubon A, Roux JO, et al. Direct percutaneous approach to the upper pole of the kidney: MRI anatomy with assessment of the visceral risk. J Endourol. 1999;13:17–20. Shanmuganathan K, Mirvis SE, Boyd-Kranis R, et al. Nonsurgical management of blunt splenic injury: use of CT criteria to select patients for splenic arteriography and potential endovascular therapy. Radiology. 2000;217:75–82. Prowda JC, Trevisan SG, Lev-Toaff AS. Splenic injury after colonoscopy: conservative management using CT. AJR Am J Roentgenol. 2005;185:708–10. Cadeddu M, Garnett A, Al-Anezi K, et al. Management of spleen injuries in the adult trauma population: a ten-year experience. Can J Surg. 2006;49:386–90.

817 Rajani RR, Claridge JA, Yowler CJ, et al. Improved outcome of adult blunt splenic injury: a cohort analysis. Surgery. 2006;140:625–31; discussion 631–622. Watson GA, Rosengart MR, Zenati MS, et al. Nonoperative management of severe blunt splenic injury: are we getting better? J Trauma. 2006;61:1113–8; discussion 1118–1119. Anderson SW, Varghese JC, Lucey BC, et al. Blunt splenic trauma: delayed-phase CT for differentiation of active hemorrhage from contained vascular injury in patients. Radiology. 2007;243:88–95. Gore RM, Levine MS, editors. Textbook of gastrointestinal radiology. 3rd ed. Philadelphia: Saunders; 2007. MacLeod JB, Cohn SM, Johnson EW, et al. Trauma deaths in the first hour: are they all unsalvageable injuries? Am J Surg. 2007;193:195–9. Marmery H, Shanmuganathan K, Alexander MT, et al. Optimization of selection for nonoperative management of blunt splenic injury: comparison of MDCT grading systems. AJR Am J Roentgenol. 2007;189:1421–7. Merran S, Karila-Cohen P, Servois V. CT anatomy of the normal spleen: variants and pitfalls. J Radiol. 2007;88:549–58. Michel MS, Trojan L, Rassweiler JJ. Complications in percutaneous nephrolithotomy. Eur Urol. 2007;51:899–906; discussion 906. Desai AC, Jain S, Benway BM, et al. Splenic injury during percutaneous nephrolithotomy: a case report with novel management technique. J Endourol. 2010;24:541–5. Theodoropoulos J, Krecioch P, Myrick S, et al. Delayed presentation of a splenic injury after colonoscopy: a diagnostic challenge. Int J Colorectal Dis. 2010;25:1033–4. Clark TJ, Cardoza S, Kanth N. Splenic trauma: pictorial review of contrast-enhanced CT findings. Emerg Radiol. 2011;18:227–34.

Index

A Abdominal radiography chronic pancreatitis, 590 hepatic echinococcal disease, 237 Abernethy syndrome. See Congenital intrahepatic portosystemic shunt Accessory fissure complications, 4 CT images, 16 with loculated fluid collection, 17 Accessory hepatic lobe complications, 4 with mass, 13 Accessory spleens asymptomatic, 722 intrahepatic, 733 intrapancreatic, 731 pathologic conditions, 722 posterior location, 730 splenic hilum, 729 Acinar cell carcinoma, 669, 685–686 Acquired immunodeficiency syndrome, tuberculosis associated with, 754 Acute cellular rejection, 307–308, 332 Acute cholecystitis complication of, 448 with cystic duct stone, 451 gallbladder, 524 Acute gangrenous cholecystitis, 453 Acute hemorrhagic cholecystitis, 454 Acute hepatitis CT findings, 42 imaging findings, 25 Acute necrotic collection (ANC), 589, 599 Acute necrotizing pancreatitis with ANC, 599 infected walled-off necrosis, 601 pancreas parenchyma, 600 Acute pancreatitis abdominal pain, 588 acute interstitial pancreatitis, 596–598 Atlanta classification, 588 CECT, 588 complications of, 589 diagnosis of, 588 gallstones and alcohol consumption, 588 grades of severity, 589, 590 MRI, 588 pseudoaneurysm from splenic artery, 602 types of, 589 Acute peripancreatic fluid collection (APFC), 597, 598 Acute thrombosis, 287

Adenomas benign GB tumors, 505 hepatocellular (see Hepatocellular adenoma (HCA)) Adenomatous polyps, 536 Adenomyomatosis diffuse, 465–466 gallbladder, 527 segmental, 464 Adenomyomatous hyperplasia, 525–526. See also Adenomyomatosis Adenosquamous carcinoma, 669, 682 Adipose atrophy. See Fatty replacement, of pancreas Agenesis, hepatic lobe/segment, 4 left lateral segment, 8 right lobe, 7 AIP. See Autoimmune pancreatitis (AIP) Alcoholic liver disease, 23 Alcohol-induced liver cirrhosis CT findings, 33 splenomegaly associated with, 743 Amebic liver abscess, 252 clinical feature, 236 computed tomography, 236 E. histolytica, 235 MRI, 236 pathogenesis, 235 ultrasonography, 236 American Association for the Surgery of Trauma (AAST) active arterial bleeding, 375 extensive parenchymal disruption, 376 intraparenchymal hematoma, active bleeding, 374 liver organ injury scale, 370 parenchymal laceration, 374 small intraparenchymal laceration and hematoma, 372 small laceration, 372 subcapsular hematoma, 371, 373 superficial laceration, 371 American Association for the Surgery of Trauma pancreatic injury scale, 704, 705 American Association for the Surgery of Trauma (AAST) splenic injury scale, 808, 809 American Joint Committe on Cancer (AJCC), 475 Amiodarone, 23 Amiodarone-induced hepatic attenuation change, 34 Ampullary cancer, 490 Amyloidosis clinical finding, 26 CT findings, 51 splenomegaly associated with, 750 Anastomotic leak, 541 Anastomotic stricture, 556–557 ANC. See Acute necrotic collection (ANC) Anchovy paste, 235

B.I. Choi (ed.), Radiology Illustrated: Hepatobiliary and Pancreatic Radiology, Radiology Illustrated, DOI 10.1007/978-3-642-35825-8, © Springer-Verlag Berlin Heidelberg 2014

819

820 Angiomyolipoma (AML), 79, 107 Angiosarcoma, 172–173 Annular pancreas, 576–577 computed tomography, 569 definition, 569 ERCP, 569 MRI, 569 prevalence, 569 Anomalies and anatomic variants, liver. See Liver, anomalies and anatomic variants Anomalous pancreaticobiliary ductal union (APBDU) choledochal cyst, 414 (see also Choledochal cyst) C-P type, 395, 412 with gallbladder cancer, 413–414 P-C type, 395, 410–411 prevalence, 395 Apparent diffusion coefficient (ADC), 591 Arterial active bleeding, 367, 375 Arterial pseudoaneurysms, 367 Arterioportal shunt fatty sparing, 272 hemangioma with, 270 Arterioportal shunt (APS), 264 Ascariasis, 422 Aspergillosis, 741, 757 Asplenia, 722, 735 Atlanta classification, acute pancreatitis, 588 Attenuation/signal intensity changes, of liver parenchyma alcoholic liver disease, 23 amiodarone, 23 chemotherapy-associated steatohepatitis (CASH) and steatosis, 23 fatty liver disease, 22–23 glycogen storage disease (GSD), 24 hemosiderosis and hemochromatosis, 23–24 hepatic radiation is, 24–25 hepatic sinusoidal injury, 24 NASH (nonalcoholic steatohepatitis), 23 Autoimmune pancreatitis (AIP), 592 diagnostic criteria of, 593 ductal changes, 594 extrapancreatic organ involvement, 623–625 18F-fluorodeoxyglucose uptake, 594 granulocyte epithelial lesions, 593 imaging findings of, 593–595 incidence and clinical symptoms of, 593 parenchymal involvement of, 594 type 1 AIP, 593 diffuse type, 618–620 focal type, 621–622 IgG4-related disease, 594 typical pathology, 616 type 2 AIP diffuse type, 626–627 focal type, 628 granulocyte epithelial lesions, 593 typical pathology, 617 vascular involvement, 594 Automated CT volumetry, 309 Autosomal dominant polycystic kidney disease, 70

B Bacterial abscess, 769, 789. See also Pyogenic hepatic abscess Benign focal splenic lesions bacterial abscess, 769, 789 differential diagnosis of, 766

Index echinococcal cyst, 768–769 EMH, 768, 783–784 epidermoid cyst, 768, 787, 788 fungal abscess, 769, 791 hamartoma in male patient, 775–776 MRI and CT, 767 origin of, 766 ultrasonography, 767 hemangioma (see Hemangioma, benign focal splenic lesions) IMT, 768, 781–782 littoral cell angioma, 767 lymphangioma, 767 mycobacterial abscess, 769, 790 pseudocyst, 768, 785, 786 SANT computed tomography, 767–768 in female patient, 780 in male patient, 778–779 MRI, 768 vascular structures, 767 Benign liver tumors angiomyolipoma (AML), 79, 107 biliary cystadenoma, 78, 106 biliary hamartoma MRI, 105 properties, 78 focal nodular hyperplasia CT, 91 diagnosis, 77 with interval growth, 93 with interval regression, 94 MR imaging, 92 ultrasound, 90 visualization, 77 hemangioma hypoechoic, 80–81 imaging feature, 76 with interval growth, 87 with interval regression, 88 in liver cirrhosis, 85 MR imaging, 82 rapid-filling with arterioportal shunt, 83 sclerosed, 89 slow-filling in fatty liver, 86 slow-filling with arterioportal shunt, 84 hemorrhagic cyst, 102 hepatic cysts imaging feature, 78 peribiliary, 78 hepatocellular adenoma CEUS, 77 clinical and prognostic features, 78 with hemorrhage, 99 inflammatory, 101 MR imaging, 96 multiple adenomas, 98 small steatotic, 97 with subcapsular hematoma and hemorrhage, 100 T1-WI, 78 large regenerative nodule in hereditary hemorrhagic telangiectasia, 95 properties, 77 peribiliary cysts, 104 polycystic liver disease, 103 schwannoma, 79, 108

Index Bicameral gallbladder, 416 Bile duct cancer. See Cholangiocarcinoma (CC) Bile duct injury bile leak, 540 biliary obstruction and stricture, 540–541 cholecystectomy, 540 post-biliary-enteric anastomosis, 541 postcholecystectomy class A, 546 class B, 547–548 class D, 549 class E2, 550 remnant cystic duct, 541 Strasberg classification, 544 Bile leak anastomosis, 541 hepatobiliary contrast agent, 553–554 imaging, 540 IVC-duodenal fistula, 555 Biliary cast syndrome, 307, 331 Biliary cystadenocarcinoma, 171–172 CT scan, 195 US image, 196 Biliary cystadenoma, 78, 106 Biliary hamartoma MRI, 105 properties, 78 USG, CT and MR findings, 69 Biliary obstruction cholecystectomy, 540 choledocholithiasis, 436–437 distal common bile duct cancer, 441 intrahepatic mass-forming cholangiocarcinoma, 439 Biliary stricture, 540–541 Biliary tract. See also Biliary tree bile duct injury bile leak, 540 biliary obstruction and stricture, 540–541 cholecystectomy, 540, 545 post-biliary-enteric anastomosis, 541 remnant cystic duct, 541 Strasberg classification, 544 bile juice, 540 biloma, 551–552 cadaveric donor liver transplantation anastomotic stricture, 556–557 bilateral multifocal stricture of intrahepatic ducts, 559 confluence stricture, 558 diffuse necrosis of intrahepatic ducts, 560 ischemic injury of bile duct, 561 cholangiography, 545 PTBD, 563 RFA, 541 TACE procedure, 541 trauma-related bile duct injury, 540, 543 Biliary tree APBDU, 395 biliary anatomic variants, 394 choledochal cyst symptoms, 394 type I fusiform dilatation, 405 type II diverticulum, 406 type IV intra and extrahepatic duct cysts, 407 type V Caroli disease, 408–409 gallbladder, 395–396 inadvertent complications, 394

821 low-lying cystic duct, 403 normal bile duct anatomy, 397 pruned tree appearance, 422 right anterior duct drains, 402 right posterior duct drains bile duct directly, 401 left hepatic duct, 398 right anterior duct, right side, 399 trifurcation, 400 Bilomas blunt liver trauma, 367–369 central lobectomy and hepaticojejunostomy, 552 percutaneous cholecystostomy, 562 right hemihepatectomy, 551 Bismuth-Corlette classification system type I, 482–483 type IIIA, 486 type IIIB, 484 type IV, 485, 498 Blunt splenic trauma, 808 Branch duct type IPMN, 633, 637 Breast angiosarcoma, 218 Brucellosis infection, 741, 758 Budd-Chiari syndrome (BCS) acute hepatic vein obstruction, 265–266 chronic hepatic vein (HV) thrombosis, 288 inferior vena cava obstruction, 266, 291

C Cadaveric donor liver transplantation anastomotic stricture, 556–557 bilateral multifocal stricture of intrahepatic ducts, 559 confluence stricture, 558 diffuse necrosis of intrahepatic ducts, 560 ischemic injury of bile duct, 561 Calcified metastases, 221–222 Calcified tuberculosis, 753 Capillary hemangioma, 766 Caroli disease, 395, 408–409 Caudate lobe, papillary process, 5, 19 Cavernous hemangioma, 766, 770, 772–773 cystic, 770 solid, 772–773 CC. See Cholangiocarcinoma (CC) CECT. See Contrast-enhanced computed tomography (CECT) Chemoembolization, HCC with drug-eluting bead, 361 iodized oil, 356, 358 ischemic biliopathy, 360 MR images, 357–358 Chemotherapy-associated steatohepatitis (CASH) and steatosis, 23 Chemotherapy-induced hepatic sinusoidal injury MR findings, 40 Cholangiocarcinoma (CC). See also Intrahepatic cholangiocarcinoma abundant fibrous stroma, 476 ampullary cancer, 490 autoimmune pancreatitis, biliary involvement, 496 benign bile duct stricture, 497 bile duct cancer, 487 Bismuth-Corlette classification system type I, 482–483 type IIIA, 486 type IIIB, 484 type IV, 485, 498

822 Cholangiocarcinoma (CC) (cont.) choledochal cyst, 495 classification, 472 demographic and clinical features, 472 extrahepatic CC, 475 HCC, 493–494 imaging, role, 473 intraductal-growing CC IPMN, 473 MRI, 475 staging, 475 ultrasound and CT, 475 intraductal papillary mucinous tumor, 491–492 intrahepatic mass-forming CC, 478–479 mass-forming CC calcification, 473 CT scan, 473 HCCs, 474 MRI, 474 viable tumor cells, 472 morphology, 477 para-aortic lymph node metastasis, 488 periductal-infiltratin CC Glisson’s capsule, 473 MDCT, 474 postprocessing techniques, 474 periductal-infiltrating hilar, 480 peritoneal carcinomatosis and pelvic bone metastasis, 489 resectability, 475 Cholangitis benign biliary stricture, 442 bile duct dilatation, 423 cholangiocarcinoma, 432–435 choledocholithiasis, 436–437 clonorchiasis, 443–444 distal common bile duct cancer, 441 hepatolithiasis, 428 intrahepatic mass-forming cholangiocarcinoma, 439–440 Mirizzi syndrome, 438 obstructive, 421 parasitic infestation, 421–422 PBC, 420, 427 PSC, 420, 424–426 RPC, 421, 429–431 Cholecystectomy, bile duct injury. See Bile duct injury Cholecystitis. See also specific cholecystitis acute cholecystitis, 448 acute gangrenous, 453 acute hemorrhagic, 454 chronic calculous cholecystitis with cholesterolosis, 459 chronic cholecystitis, 448–449 duodenum, 450 emphysematous, 455–456 fundal adenomyoma, 463 gallbladder diffuse adenomyomatosis, 466 perforation, 457–458 porcelain, 462 wall edema, 452 gallstone ileus, 460 Mirizzi syndrome, 449 xanthogranulomatous, 451 Cholecystoduodenal fistula, 460 Choledochal cyst. See also Biliary tree symptoms, 394 type I fusiform dilatation, 405

Index type II diverticulum, 406 type IV intra and extrahepatic duct cysts, 407 types, 395 type V Caroli disease, 408–409 Choledocholitiasis, 421 Cholesterolosis, 459 Cholesterol polyps, 505, 537 Chronic calculous cholecystitis, 459 Chronic cholecystitis fistula, 448–449 gallbladder cancer, 525–526 porcelain gallbladder, 449 xanthogranulomatous cholecystitis, 449 Chronic ductopenic rejection, 308 Chronic hepatic vein (HV) thrombosis, 288 Chronic hepatitis, 25 Chronic pancreatitis abdominal radiography, 590 causes of, 590 CECT, 590–591 clinical symptoms, 590 definition, 590 ductal changes, 603, 604 ERCP, 591 EUS, 591 inflammatory mass, 610 MRCP, 591 MRI, 591 pancreas adenocarcinoma, 611 parenchymal changes, 605–606 pseudoaneurysm, 607 superimposed acute pancreatitis, 609 transabdominal US, 590 venous thrombosis, 608 Chronic passive hepatic congestion, 293 Cirrhotic nodules dysplastic nodule (DN), 114–115, 136–137, 150–151 regenerative nodule (RN), 114, 148–149 Clonorchiasis, 421–422 Clonorchis sinensis, 421 Colloid carcinomas, 669, 681 Colon cancer, hemorrhagic metastases from, 211 Colorectal cancer bile duct invasion, 226 hypovascular metastases from, 213–214 Computed tomography (CT) accessory fissure, 16 acute hepatitis, 42 alcohol-induced liver cirrhosis, 33 amebic liver abscess, 236 amyloidosis, 51 annular pancreas, 569 benign focal splenic lesions bacterial abscess, 769 echinococcal cyst, 769 EMH, 768 epidermoid cyst, 768 fungal abscess, 769 hamartoma, 767 hemangioma, 766 IMT, 768 littoral cell angioma, 767 lymphangioma, 767 mycobacterial abscess, 769 SANT, 767–768

Index biliary cystadenocarcinoma, 195 diaphragmatic slip, 14 diffuse hepatic metastasis, 63–64 diffuse liver disease, 22 eosinophilic abscess, 61 extramedullary hematopoiesis, 67, 68 fatty replacement of pancreas, 570 focal eosinophilic liver disease, 238 focal nodular hyperplasia like nodules, 65 fulminant hepatitis, 32 glycogen storage disease, 39 hepatic candidiasis, 238 hepatic echinococcal disease, 237 hepatic steatosis, 28 liver cirrhosis, 47 liver transplantation, 304 local tumor progression, 346 mass-forming cholangiocarcinoma, 473 multinodular fat deposition, 72 multinodular hepatocellular carcinoma, 66 multiple collaterals, 49 pancreatic ductal adenocarcinoma, 668 peliosis, 62 pyogenic hepatic abscess, 234–235 radiation hepatitis, 41 Riedel’s lobe, 12 splenic angiosarcoma, 794 splenic injury, 808 splenic lymphoma, 794 traumatic pancreas injury, 704 Confluent hepatic fibrosis, 26, 50 characteristics, 115–116 typical appearance, 153 Congenital intrahepatic portosystemic shunt, 299, 300 Congenital pancreatic cysts, 570 Congestive splenomegaly with alcoholic liver cirrhosis, 743 cause of, 740 with inferior vena cava obstruction, 745 with liver cirrhosis, 742 with splenic vein occlusion, 744 Contrast-enhanced computed tomography (CECT) acute pancreatitis, 588 Bismuth-Corlette type IIIA CC, 486 chronic pancreatitis, 590–591 groove pancreatitis, 592 polypoid mass, 509 wall thickening, 508 Contusion, 366 Cystic duct biliary tree, 394 MRCP, 405 stone, 451 Cystic metastases, 208–210 Cystic pancreatic tumors characteristic shapes of, 632 epidermoid cyst in intrapancreatic accessory spleen, 634, 665 histologic classification of, 632, 635–636 IPMN, 632–633 microcystic and macrocystic lesions, 632 mucinous cystic neoplasm, 633 multilocular cyst, 632 non-epithelial cystic tumors, 634 nonneoplastic cystic lesions, 634 oligolocular cyst, 632

823 retention cyst, 634, 663–664 serous cystic neoplasm, 633 solid tumors, cystic degeneration of, 633–634 unilocular cyst, 632

D Delayed hemorrhage, 367, 379 Diaphragmatic slip accessory fissure and, 4 CT findings, 14 radiography and ultrasound findings, 15 Diffuse adenomyomatosis, 465–466 Diffuse fatty replacement, 582 Diffuse hepatic metastasis, 63–64 Diffuse large B-cell lymphoma, 227, 798, 799 Diffuse liver disease attenuation/signal intensity changes of liver parenchyma alcoholic liver disease, 23 amiodarone, 23 chemotherapy-associated steatohepatitis (CASH) and steatosis, 23 fatty liver disease, 22–23 glycogen storage disease (GSD), 24 hemosiderosis and hemochromatosis, 23–24 hepatic radiation is, 24–25 hepatic sinusoidal injury, 24 NASH (nonalcoholic steatohepatitis), 23 multifocal hepatic lesions liver cirrhosis-related nodules, 26–27 lymphoma, 27 multiple myeloma, 27 sarcoidosis, 27 radiologic modalities, 22 size and contour changes amyloidosis, 26 hepatitis, 25 liver cirrhosis, 25–26 Wilson’s disease, 26 Diffuse splenic diseases aspergillosis infection, 741, 757 brucellosis infection, 741, 758 extramedullary hematopoiesis, 741, 760–761 Gamna-Gandy bodies, 741, 762 hemochromatosis, 759 malaria, 740–741, 755 Salmonella infection, 741, 756 splenomegaly (see Splenomegaly) tuberculosis, 752 with acquired immunodeficiency syndrome, 754 calcified, 753 miliary, 741 Doppler ultrasound (US) diffuse adenomyomatosis, 466 HA problems, 307 hemangioma, 76 hemorrhagic cyst, 102 liver transplantation (LT), 325 Dorsal pancreatic agenesis, 569–570 Ductal adenocarcinoma, 632, 633 Duct of Santorini, 568 Duct of Wirsung, 568 Duodenal perforation, 714 Dysplastic nodules (DNs) hepatocellular carcinoma, 114–115, 136–137, 150–151 liver cirrhosis related, 26, 54–55

824 E Echinococcal cysts, 768–769 Echinococcus granulosus, 236 Echinococcus multilocularis, 236 Ectopic pancreas definition, 569 diagnostic feature, 569 in duodenum, 579, 580 in ileum, 579 in stomach, 578 Elastography, 22 Embryonal sarcoma, undifferentiated, 200 EMH. See Extramedullary hematopoiesis (EMH) Emphysematous cholecystitis, 448, 455–456 Endometrial adenocarcinoma, 801–802 Endoscopic retrograde cholangiopancreatography (ERCP) anastomotic stricture, 541 annular pancreas, 569 bile leak, 540 chronic pancreatitis, 591 pancreatic divisum, 568 stone formation, 541 traumatic injury of bile duct, 543 traumatic pancreas injury, 704 Endoscopic ultrasound (EUS) chronic pancreatitis, 591 gallbladder cancer, 502 Entamoeba histolytica, 235 Eosinophilic abscess, 61 Epidermoid cyst benign focal splenic lesions, 768, 787, 788 in intrapancreatic accessory spleen, 634, 665 Epithelioid hemangioendothelioma with confluent pattern, 198 with discrete nodules, 199 histopathology, 172 imaging, 172 non-contrast CT, 197 ERCP. See Endoscopic retrograde cholangiopancreatography (ERCP) Escherichia coli, 234 European Association for the Study of the Liver (EASL), 337 Extramedullary hematopoiesis (EMH) CT findings, 67, 68 definition, 768 diffuse splenic diseases, 741, 760–761 in male patient, 783–784 MR findings, 68

F Fascioliasis, 258 Fat necrosis, 669 Fatty liver disease, 22–23 Fatty metamorphosis, HCC with, 138–139 Fatty replacement, of pancreas, 570 18 F-fluorodeoxyglucose positron emission tomography (FDG PET), 473 Fibrolamellar HCC, 145–146 Fibrosis mimicking cholangiocarcinoma, 497 Focal eosinophilic liver disease computed tomography, 238 eosinophilic abscess, 238, 257 eosinophilic granuloma, 238 focal eosinophilic infiltration, 238 MRI, 238 ultrasonography, 238

Index Focal fat deposition, of pancreas, 583 Focal hepatic infections amebic liver abscess, 252 clinical feature, 236 computed tomography, 236 E. histolytica, 235 MRI, 236 pathogenesis, 235 ultrasonography, 236 candidiasis, 237–238, 256 fascioliasis, 258 focal eosinophilic liver disease, 238, 257 hepatocellular carcinoma, 237, 238, 260 hydatid cysts, 253 ectocyst, 236 endocyst, 236 pericyst, 236 rupture into bile duct, 254 metastasis, 238, 261 parasitic infection echinococcal disease, 236–237 schistosomiasis, 237, 255 pyogenic hepatic abscess (see Pyogenic hepatic abscess) tuberculosis, 259 Focal nodular hyperplasia (FNH) CT, 91 diagnosis, 77 hepatocellular carcinoma, 157–158, 162 with interval growth, 93 with interval regression, 94 like nodules, 65 MR imaging, 92 ultrasound, 90 visualization, 77 Fulminant hepatitis, 32 Fundal adenomyoma, 463 Fungal abscess, 769, 791

G Gallbladder (GB) benign gallbladder polyp, 536–537 benign neoplasms, 505 biliary tree APBDU, 413–414 bicameral, 416 left-sided, 417 MRCP, 396 Phrygian cap, 396, 415 carcinoma manifesting mass replacing gallbladder, 510 polypoid mass, 509 wall thickening, 508 cholecystitis (see also Cholecystitis) diffuse adenomyomatosis, 466 perforation, 457–458 porcelain, 462 wall edema, 452 differential diagnosis acute cholecystitis, 524 adenomyomatosis, 527 adenomyomatous hyperplasia, 525–526 chronic complicated cholecystitis, 525–526 focal fat deposition, gallbladder bed, 528–529 xanthogranulomatous cholecystitis, 504, 521–523 dysplasia and carcinoma, Tis stage, 511 focal/diffuse mural thickening, 502

Index hematogenous gallbladder metastases, 506 large mass obscuring/replacing, 502–503 malignant neoplasms adenosquamous carcinoma, 534 diffuse wall-thickening type, 533 focal/segmental wall-thickening type, 532 metastatic tumor, 531–533 neuroendocrine carcinoma, 535 polypoid type, 531 morphologic classification, 507 polypoid intraluminal mass, 502 radiologic tools, 502 stones/sludge, 530 TNM staging T1a stage, 503, 512 T1b stage, 503, 513 T2 stage, 503, 514 T3 stage, 503, 515 T4 stage, 503, 516 tumor spread direct invasion, liver, 503–504, 517 hematogenous spread, liver and lung, 504, 519 lymphatic spread to regional lymph nodes, 504, 518 peritoneum metastasis, 504, 520 Gallstone ileus, 460 Gamna-Gandy bodies, 741, 762 Gangrenous cholecystitis, 448 Gastric cancer, hypovascular metastases from, 212 Gastrointestinal tumor, cystic metastases of, 208 Gaucher’s disease, splenomegaly associated with, 748 Glycogen storage disease (GSD) clinical findings, 24 CT findings, 39 Granulocyte epithelial lesions (GELs), 593 Groove pancreatitis causes and clinical symptoms, 592 CECT, 592 differential diagnosis of, 592 duodenal biopsies, 592 groove cancer, 614–615 in male patient, 612, 613 MRCP, 592 MRI, 592 Growing hemangioma, 771

H Hamartoma, benign focal splenic lesions in male patient, 775–776 MRI and CT, 767 origin of, 766 ultrasonography, 767 HCC. See Hepatocellular carcinomas (HCCs) HELLP syndrome, 266, 296 Hemangioma benign focal splenic lesions capillary, 766 cavernous, 766, 770, 772–773 computed tomography, 766 growing, 771 magnetic resonance imaging, 766 plain radiography, 766 ruptured splenic, 774 symptoms, 766 ultrasonography, 766 benign liver tumors hypoechoic, 80–81

825 imaging feature, 76 with interval growth, 87 with interval regression, 88 in liver cirrhosis, 85 MR imaging, 82 rapid-filling with arterioportal shunt, 83 sclerosed, 89 slow-filling in fatty liver, 86 slow-filling with arterioportal shunt, 84 in cirrhotic liver atypical appearance, 155–156 typical appearance, 154 Hematomas, splenic injury and active bleeding, 814 subcapsular, 808, 811 Hemobilia, 378 Hemochromatosis clinical features, 24 diffuse splenic diseases, 759 MR, 35 primary, 37 secondary, 38 Hemodynamic and perfusion-related disorders acute thrombosis, 287 arterioportal shunt fatty sparing, 272 hemangioma with, 270 chronic passive hepatic congestion, 293 congenital intrahepatic portosystemic shunt, 300 hepatic artery inflow alteration hepatic infarction, 265 non-portal venous supply, 265 hepatic circulation, 264 hepatic infarction, 276 hepatocellular carcinoma, 292 hyperplastic nodules with perinodular ring, 301 infiltrative hepatocellular carcinoma lobar, 275 with regional involvement, 274 left gastric vein, 284 non-portal venous supply, 281 outflow abnormality Budd-Chiari syndrome, 265–266 passive hepatic congestion, 266 sinusoidal occlusive disease, 266 pancreaticoduodenal vein, 283 portal biliopathy, 280 portal venous inflow alteration arterioportal shunt, 264 zonal perfusion, 264–265, 277–279 right gastric vein, 282 sinusoidal occlusive disease, 294–295 transient hepatic attenuation difference from arterioportal fistula, 273 diagram of, 269 hepatocellular carcinoma with, 271 portal vein thrombosis causing, 286 with superior vena cava obstruction, 285 vascular disorders congenital vascular malformation, 267 HELLP syndrome, 266, 296 vena cava, membranous obstruction of, 289–290 zonal perfusion changes, 277 Hemorrhage delayed, 367 liver transplantation, 305

826 Hemorrhagic cholecystitis, 448 Hemorrhagic cyst, 102 Hemosiderosis, 23–24, 36 Hepatic abscess, 367 Hepatic adenoma, 159 Hepatic angiomyolipoma, 160–161 Hepatic artery inflow alteration hepatic infarction, 265 non-portal venous supply, 265 Hepatic artery pseudoaneurysm, 321 Hepatic candidiasis characterization, 237 computed tomography, 238 MRI, 238 pathogenesis and clinical feature, 237–238 percutaneous needle biopsy, 238 ultrasonography, 238 USG and CT findings, 60 Hepatic circulation, 264, 268 Hepatic cysts imaging feature, 78 peribiliary, 78 Hepatic echinococcal disease abdominal plain radiographs, 237 clinical features, 236–237 computed tomography, 237 E. granulosus, 236 E. multilocularis, 236 hydatid cyst (see Hydatid cysts) MRI, 237 water lily sign, 237 Hepatic fibrosis characteristics, 115–116 contrast media-enhanced MR, 45 elastography findings, 44 with portal hypertension, 48 typical appearance, 153 USG and CT findings, 43 Hepatic infarction, 276 Hepatic lobe/segment agenesis and hypoplasia, 4 left lateral segment, 8 right lobe, 7 Hepatic radiation is, 24–25 Hepatic sinusoidal injury chemotherapy-induced, 40 clinical features, 24 Hepatic steatosis, 310 CT and MR findings, 28 illustration of, 35 ultrasound (USG), 28 uneven hepatic steatosis, 29 Hepatic vein lacerations, 367 Hepatitis, 25 acute, 42 chronic, 25 radiation, 41 Hepatoblastoma, 173–174, 203 Hepatocellular adenoma (HCA) CEUS, 77 clinical and prognostic features, 78 with hemorrhage, 99 inflammatory, 101 MR imaging, 96 multiple adenomas, 98 small steatotic, 97

Index with subcapsular hematoma and hemorrhage, 100 T1-WI, 78 Hepatocellular carcinomas (HCCs) advanced nodular-type, 123–124 arterially enhancing pseudolesions, 115 atypical arterial hyperenhancement, 134 atypical imaging features, 113–114 benign arterially enhancing tumors, 116 with bile duct invasion, 141, 493–494 carcinogenesis, 117 chemoembolization with drug-eluting bead, 361 iodized oil, 356, 358 ischemic biliopathy, 360 MR images, 357–358 cholangiocarcinoma, 147, 186, 192–194, 474 cirrhotic nodules dysplastic nodule (DN), 114–115, 136–137, 150–151 regenerative nodule (RN), 114, 148–149 clear cell-type, 142 confluent hepatic fibrosis characteristics, 115–116 typical appearance, 153 with corona enhancement, 129 diffuse-type, 126 discordant enhancement, 133–134 enhancement pattern and pseudocapsule, 122 ethanol ablation, 337 with fatty metamorphosis, 138–139 fibrolamellar, 145–146 focal nodular hyperplasia, 157–158, 162 hepatic abscess, 260 hepatic adenoma, 159 hepatic angiomyolipoma, 160–161 heterogeneously enhancing, 130 hypervascular metastases characteristics, 116 from pancreatic cancer, 166 indistinctly nodular type, 120–121 intrahepatic cholangiocarcinoma atypical enhancement, 164–165 mass-forming, 116 typical enhancement, 163 intranodular blood supply changes, 127 large nodular-type with pseudocapsule, 128 management of, 336 mass-forming CCs, 474 massive-type, 125 mosaic appearance and a peripheral capsule, 131 mRECIST branch duct type, 341 combined assessment, 337 measurement methods, 340 vs. RECIST, 337, 339 nodule in nodule appearance, 140 percutaneous ethanol ablation, 354–355 with portal vein thrombosis, 132 with pseudocapsule, 128 RECIST 1.0 and 1.1, 336 RFA ablation zone, 342 abscess/infected biloma, 351–352 benign periablational enhancement, 343 involution of, 344

Index local tumor progression, 346–349 massive bleeding, 353 mistargeting, 350 MR findings, 345 scirrhous-type, 143–144 small hemangioma in cirrhotic liver atypical appearance, 155–156 typical appearance, 154 small progressive, 118–119 with sorafenib, 363 splenic metastasis, 803–804 with TARE, 362 transient hepatic attenuation difference, 152 and tumor thrombus, 141 typical imaging features, 112–113 variants, 114 WHO, 336 Hepatolithiasis, 428 Hereditary hemorrhagic telangiectasia (HHT), 95. See also Osler-Weber-Rendu syndrome (OWR) Heterotaxy, 722 Heterotopic pancreas. See Ectopic pancreas High-resolution ultrasound (HRUS) gallbladder dysplasia and carcinoma, 511 GB stone, 527 Hilar cholangiocarcinoma choledochal cyst, 495 para-aortic lymph node metastasis, 488 pelvic bone metastasis, 489 periductal-infiltrating CC, 473 peritoneal carcinomatosis, 489 Hydatid cysts, 253. See also Echinococcal cysts ectocyst, 236 endocyst, 236 pericyst, 236 rupture into bile duct, 254 Hydatid disease. See Hepatic echinococcal disease Hyperechoic metastases, 207 Hyperplastic nodules with perinodular ring, 301 Hyperplastic splenomegaly, 740 with polycythemia vera, 747 with spherocytosis, 746 Hypervascular metastases, 217–219 characteristics, 116 from pancreatic cancer, 166 Hypervascular metastasis from breast angiosarcoma, 218 from pancreatic neuroendocrine tumor, 217 from renal cell carcinoma, 218 Hypoechoic hemangioma, 80–81 Hypoechoic metastases, 204 Hypoplasia hepatic lobe/segment left lateral segment, 9 left medial segment, 10 pancreas agenesis, 569–570 Hypovascular metastases colorectal cancer, 213–214 gastric cancer, 212 Iatrogenic injury, 712 Idiopathic duct-centric pancreatitis (IDCP), 593 IMT. See Inflammatory myofibroblastic tumor (IMT) Inferior vena cava (IVC) LDLT, 306 MDCT, 307 stenosis, 323

827 Inferior vena cava obstruction, 745 Infiltrative hepatocellular carcinoma lobar, 275 with regional involvement, 274 Infiltrative splenomegaly, 740 with amyloidosis, 750 with Gaucher’s disease, 748 with sarcoidosis, 749 Inflammatory myofibroblastic tumor (IMT), 768, 781–782 Inflammatory splenomegaly, 740 Intermediate-grade dysplasia IPMN branch duct type, 640–641 main duct type, 644 mucinous cystic neoplasm, 654–655 International Consensus Diagnostic Criteria for AIP (2010), 593 Intraductal-growing cholangiocarcinoma IPMN, 473 MRI, 475 staging, 475 ultrasound and CT, 475 Intraductal papillary mucinous neoplasm (IPMN), 473 of bile ducts, 190–191 characterization of, 632 combined type, 637, 645–646 HCC, 341 with intermediate-grade dysplasia branch duct type, 640–641 main duct type, 644 with low-grade dysplasia branch duct type, 638–639 main duct type, 642–643 malignancy risk, 633 ruptured, 647 WHO classification of, 632–633 Intraductal papillary mucinous tumor, 491–492 Intrahepatic accessory spleens, 733 Intrahepatic cholangiocarcinoma atypical enhancement, 164–165 hepatocellular carcinoma, 186, 192–194 intraductal growth type, 171, 188–189 intraductal papillary mucinous neoplasm, 190–191 mass-forming type, 170–171 capsular retraction, 183–184 with diffuse dilatation of biliary tree, 185 MRI findings, 181–182 typical enhancement pattern, 179–180 periductal infiltrative-type, 187 peripheral infiltrative type, 171 types, 178 typical enhancement, 163 Intrahepatic mass-forming cholangiocarcinoma, 478–479 Intraoperative cholangiography, 314 Intraoperative ultrasound (IOUS), 305 Intrapancreatic accessory spleen (IPAS), 672, 700, 731 Intrapancreatic spleen, 732 Intraparenchymal hematomas, 366 Invasive Klebsiella pneumoniae liver abscess syndrome, 251 IPMN. See Intraductal papillary mucinous neoplasm (IPMN) Ischemic bile duct injury, 420 Ischemic biliopathy, 360

K Ki67 index, 670 Klebsiella pneumoniae, hepatic abscess, 234 Knife stabbings, 368

828 L Laceration, 366 Large regenerative nodule in hereditary hemorrhagic telangiectasia, 95 properties, 77 Leiomyosarcoma, 173 Leukemic liver, 58 Lipomatosis. See Fatty replacement, of pancreas Liver contrast media-enhanced MR, 46 leukemic involvement, 58 lymphoma involvement, 57 multiple myeloma, 59 sarcoidosis in, 56 segmental anatomy, 6 Liver, anomalies and anatomic variants accessory fissure CT images, 16 with loculated fluid collection, 17 accessory hepatic lobe, 4 with mass, 13 agenesis, hepatic lobe/segment, 4 left lateral segment, 8 right lobe, 7 caudate lobe, papillary process, 5, 19 diaphragmatic slip accessory fissure and, 4 CT findings, 14 radiography and ultrasound findings, 15 hypoplasia, hepatic lobe/segment, 4 left lateral segment, 9 left medial segment, 10 Riedel’s lobe, 4 CT findings, 12 ultrasound findings, 11 sliver of the liver, 5, 18 Liver cirrhosis (LC), 25–26 CT findings, 47 dysplastic nodules (DNs), 54–55 infarcted RNs, 53 regenerative nodules (RNs), 52 related nodules, 26–27 splenomegaly associated with, 742 Liver resection diagrams of, 383 types, 368 Liver transplantation (LT) acute cellular rejection, 332 anastomotic bile duct stricture, 329 anastomotic bile leak, 327 automated CT volumetry, 309 biliary anatomy, 313 biliary cast syndrome, 331 bleeding, 316–317 Doppler and CT evaluation, 325 HCC, 336 hepatic artery pseudoaneurysm, 321 hepatic artery stenosis/thrombosis, 318–320 hepatic steatosis, 310 hepatic vein stenosis, 324 intraoperative cholangiography, 314 intraoperative imaging, 305 intraoperative ultrasound, 315 IVC stenosis, 323 LDLT, 304 middle hepatic vein tributary, 326

Index nonanastomotic bile duct stricture, 330 nonanastomotic bile leak, 328 nonanastomotic stricture, 541 OLT, 304 portal vein stenosis, 322 postoperative complications bile duct, 307 bleeding, 305 hepatic artery, 305–306 inferior vena cava, 306–307 nonvascular and nonbiliary, 307–308 portal vein, 306 preoperative imaging for live liver donors, 304–305 for recipients, 304 PTLD, 333 vascular anatomy, 311–312 Liver trauma AAST, 368 (see also American Association for the Surgery of Trauma (AAST)) bilomas, 367–368 delayed hemorrhage, 367, 379 grading of, 367, 370 hemobilia, 378 hepatic abscess, 367 hepatic herniation, 377 iatrogenic injury, 368, 381–382 MDCT (see Multidetector computed tomography (MDCT)) partial hepatectomy gauze packing, 388 infected biloma, 387 peripheral bile duct dilatation, 387 postoperative fluids, 384 postoperative hematoma, 386 surgical clips, 385 penetrating injury, 368, 380 postoperative change biliary complications, 369 early postoperative period, 368 late postoperative period, 368–369 liver resections, 368, 383 vascular complications, 369 Living donor liver transplantation (LDLT) benign biliary stricture, 442 biliary strictures, 307 HA stenosis, 306 HA thrombosis, 306 vs. OLT, 304 Low-grade dysplasia IPMN branch duct type, 638–639 main duct type, 642–643 mucinous cystic neoplasm, 653 Lymphangioma, 634, 767, 777 Lymphangitic metastases, 224 Lymphoepithelial cyst, 634, 662 Lymphoma, 27, 57, 176–177 Lymphoplasmacytic sclerosing pancreatitis (LPSP), 593

M Macrocystic adenomas, 633 Macrocystic lesions, 632 Magnetic resonance cholangiopancreatography (MRCP) cholangiocarcinoma, 473 cholangitis, 420

Index chronic pancreatitis, 591 gallbladder, 396 groove pancreatitis, 592 liver transplantation, 304–305 low-lying cystic duct, 403 pancreatic divisum, 568–569 right posterior duct, 398–399 traumatic pancreas injury, 704 trifurcation, 400 type I fusiform dilatation, 405 type II diverticulum, 406 type IV intra and extrahepatic duct cysts, 407 type V Caroli disease, 408–409 Magnetic resonance imaging (MRI) acute pancreatitis, 588 amebic liver abscess, 236 annular pancreas, 569 benign focal splenic lesions bacterial abscess, 769 echinococcal cyst, 769 EMH, 768 epidermoid cyst, 768 fungal abscess, 769 hamartoma, 767 hemangioma, 766 IMT, 768 littoral cell angioma, 767 lymphangioma, 767 SANT, 768 bile leak, 553–554 chronic pancreatitis, 591 eosinophilic abscess, 61 extramedullary hematopoiesis, 68 fatty replacement of pancreas, 570 flat wall-thickening type, 504 focal eosinophilic liver disease, 238 focal nodular hyperplasia like nodules, 65 groove pancreatitis, 592 hepatic candidiasis, 238 hepatic echinococcal disease, 237 hepatic steatosis, 28 liver transplantation, 304 pancreatic ductal adenocarcinoma, 669 peliosis, 62 polypoid mass, 512 pyogenic hepatic abscess, 235 Main duct type IPMN, 633, 637 Malaria, 740–741, 755 Malignant fibrous histiocytoma, 202 Malignant focal lesions, of spleen angiosarcoma, 794–797 lymphoma, 794, 798, 799 metastasis, 800–804 Malignant neoplasms adenosquamous carcinoma, 534 diffuse wall-thickening type, 533 focal/segmental wall-thickening type, 532 metastatic tumor, 531–533 neuroendocrine carcinoma, 535 polypoid type, 531 Malignant tumors of liver biliary cystadenocarcinoma, 171–172 CT scan, 195 US image, 196 diffuse large B-cell lymphoma, 227 epithelioid hemangioendothelioma

829 with confluent pattern, 198 with discrete nodules, 199 histopathology, 172 imaging, 172 non-contrast CT, 197 hepatoblastoma, 173–174, 203 intrahepatic cholangiocarcinoma hepatocellular carcinoma, 186, 192–194 intraductal growth type, 171, 188–189 intraductal papillary mucinous neoplasm, 190–191 mass-forming type, 170–171 periductal infiltrative-type, 187 peripheral infiltrative type, 171 types, 178 lymphoma, 176–177 malignant fibrous histiocytoma, 202 metastases bile duct invasion, 226 calcified, 221–222 computed tomography, 175 conspicuity of, 220 cystic, 208–210 diffuse and infiltrative, 223 EOB cloud of, 215–216 hemorrhagic, 211 hyperechoic, 207 hypervascular, 217–219 hypoechoic, 204 hypovascular, 212 lymphangitic, 224 magnetic resonance imaging, 176, 206 ultrasound, 174–175, 205 non-Hodgkin’s lymphoma diffuse involvement of, 229 hepatic involvement, 228 plasmacytoma, 177, 230 pseudocirrhosis, 225 ruptured angiosarcoma, 201 sarcomas angiosarcoma, 172–173 leiomyosarcoma, 173 undifferentiated embryonal sarcoma (UES), 173, 200 Mass-forming cholangiocarcinoma calcification, 473 CT scan, 473 HCCs, 474 MRI, 474 viable tumor cells, 472 MCN. See Mucinous cystic neoplasm (MCN) MDCT. See Multidetector computed tomography (MDCT) Mechanical obstruction of inferior vena cava (MOIVC), 740 Membranous obstruction of inferior vena cava (MOVC), 265 Memorial Sloan-Kettering Cancer Center (MSKCC), 475 Metastases bile duct invasion, 226 calcified, 221–222 computed tomography, 175 conspicuity of, 220 cystic, 208–210 diffuse and infiltrative, 223 EOB cloud of, 215–216 focal hepatic infections, 238, 261 hemorrhagic, 211 hyperechoic, 207 hypervascular, 217–219 hypoechoic, 204

830 Metastases (cont.) hypovascular, 212 lymphangitic, 224 magnetic resonance imaging, 176, 206 pancreatic solid tumor morphologic patterns, 671 primary differential consideration, 671–672 from renal cell carcinoma, 671, 699 ultrasound, 174–175, 205 Microcystic adenomas. See Serous cystic neoplasm (SCN) Microcystic lesions, 632 Miliary tuberculosis, 741 Mirizzi syndrome choledocholithiasis, 421 ERCP, 449 MRCP, 449 portal venous phase CT, 467–468 remnant cystic duct, 541 Modified RECIST (mRECIST) branch duct type, 341 combined assessment, 337 measurement methods, 340 vs. RECIST, 337, 339 MRCP. See Magnetic resonance cholangiopancreatography (MRCP) MRI. See Magnetic resonance imaging (MRI) Mucinous cystic neoplasm (MCN), 633 with associated invasive carcinoma, 656–657 with intermediate-grade dysplasia, 654–655 with low-grade dysplasia, 653 Mucinous noncystic adenocarcinomas. See Colloid carcinomas Multidetector computed tomography (MDCT) active bleeding, 369 for blunt liver trauma, 366 cholangiocarcinoma, 473 contusion and hematomas, 366 laceration, 366, 369 liver transplantation, 304 traumatic pancreas injury, 704 vascular injuries, 367 Multifocal hepatic lesions liver cirrhosis-related nodules, 26–27 lymphoma, 27 multiple myeloma, 27 sarcoidosis, 27 Multilocular pancreatic cyst, 632 Multinodular fat deposition CT findings, 72 USG and CT findings, 71 Multinodular hepatocellular carcinoma, 66 Multiple myeloma, 27, 59 Mycobacterial abscess, 769, 790

N NASH (nonalcoholic steatohepatitis), 23 Nasopharyngeal carcinoma, 800 NET. See Neuroendocrine tumor (NET) Neuroendocrine tumor (NET), 632, 634 grade 1 with cystic degeneration, 660–661 Nonalcoholic fatty liver disease (NAFLD), 23 Nonalcoholic steatohepatitis (NASH), 23 CT, MR, US elastography, 30 USG and CT findings, 31 Nonanastomotic stricture, 541 Non-Hodgkin’s lymphoma diffuse involvement of, 229 hepatic involvement, 228

Index Non-portal venous supply, 281 Normal pancreatic duct anatomy, 571, 572

O Obstructive cholangitis, 421 Oligolocular pancreatic cyst, 632 Oriental cholangiohepatitis. See Recurrent pyogenic cholangitis (RPC) Orthotopic LT (OLT), 304 Osler-Weber-Rendu syndrome (OWR), 266, 297–298 Outflow abnormality Budd-Chiari syndrome, 265–266 passive hepatic congestion, 266 sinusoidal occlusive disease (SOD), 266

P Pancreas, anomalies and anatomic variants annular pancreas, 576–577 computed tomography, 569 definition, 569 ERCP, 569 MRI, 569 prevalence, 569 congenital pancreatic cysts, 570 diffuse fatty replacement, 582 dorsal pancreatic agenesis, 569–570 duct of Santorini, 568 duct of Wirsung, 568 ectopic pancreas definition, 569 diagnostic feature, 569 in duodenum, 579, 580 in ileum, 579 in stomach, 578 embryologic development, 568 fatty replacement, 570 focal fat deposition, 583 hypoplasia, 569–570 normal pancreatic duct anatomy, 571, 572 pancreatic divisum ERCP, 568 in female patient, 573 in male patient, 574, 575 MRCP, 568–569 uncinate process, 568 uneven fatty infiltration, 584 Pancreatic contusion, 706 Pancreatic divisum ERCP, 568 in female patient, 573 in male patient, 574, 575 MRCP, 568–569 Pancreatic ductal adenocarcinoma adenosquamous carcinoma, 669, 682 with bile duct dilatation, 677 of body, isoattenuating tumor, 678 colloid carcinomas, 669, 681 CT, 668 with cystic lesions, 679 desmoplastic nature of, 669 of head, 674 and location, 673 MRI, 669 with multiple metastases, 680

Index pancreaticoblastoma, 669 surgical resection, 668 of tail, 676 teardrop sign, 668 tumor-to-vessel contiguity, 668 of uncinate, 675 undifferentiated carcinoma with osteoclast-like giant cells, 669, 683–684 variants, 669 vascular invasion, 668 Pancreatic fistula, 705, 713 Pancreatic intraepithelial neoplasia (PanIN), 633, 634 Pancreatic laceration with hematoma, 707 Pancreatic lipoma, 696 Pancreatic lymphoma, 698 Pancreatic neuroendocrine neoplasm functioning, 670 grade 2 with cystic change, 693 with hepatic metastases, 694–695 insulinoma, 691–692 Ki67 index, 670 mitotic count, 670 nonfunctioning, 670 in von Hippel-Lindau disease, 690 Pancreatic neuroendocrine tumor, 217 Pancreaticoblastoma, 669, 687 Pancreaticoduodenal vein, 283 Pancreatic schwannoma, 697 Pancreatic solid tumor acinar cell carcinoma, 669, 685–686 ductal adenocarcinoma (see Pancreatic ductal adenocarcinoma) histologic classification of, 668 IPAS, 672, 700 lipomas, 671, 696 mesenchymal tumors, 670–671 metastasis morphologic patterns, 671 primary differential consideration, 671–672 from renal cell carcinoma, 671, 699 pancreatic lymphoma, 671, 698 PNETs (see Pancreatic neuroendocrine neoplasm) schwannoma, 671, 697 SPN (see Solid pseudopapillary neoplasm (SPN)) Pancreatic transection, 708, 709 Pancreatitis acute pancreatitis abdominal pain, 588 acute interstitial pancreatitis, 596–598 Atlanta classification, 588 CECT, 588 complications of, 589 diagnosis of, 588 gallstones and alcohol consumption, 588 grades of severity, 589, 590 MRI, 588 pseudoaneurysm from splenic artery, 602 types of, 589 AIP (see Autoimmune pancreatitis (AIP)) groove pancreatitis causes and clinical symptoms, 592 CECT, 592 differential diagnosis of, 592 duodenal biopsies, 592 groove cancer, 614–615 in male patient, 612, 613 MRCP, 592 MRI, 592

831 Papillary process, caudate lobe, 5 Paraduodenal pancreatitis. See Groove pancreatitis Parasitic infection echinococcal disease, 236–237 schistosomiasis, 237, 255 Partial hepatectomy gauze packing, 388 infected biloma, 387 peripheral bile duct dilatation, 387 postoperative fluids, 384 postoperative hematoma, 386 surgical clips, 385 Peliosis, 62 Penetrating pancreatic trauma, 712 Percutaneous ethanol ablation, 354–355 Percutaneous transhepatic biliary drainage (PTBD), 563 Peribiliary hepatic cysts, 78, 104 Periductal-infiltratin cholangiocarcinoma Glisson’s capsule, 473 MDCT, 474 postprocessing techniques, 474 Periductal-infiltrating hilar cholangiocarcinom, 480 Phrygian cap, 396, 415 Plasmacytoma, 177, 230 Polycystic liver disease, 103 Polycythemia vera, 747 Polypoid intraluminal mass, 502 Polysplenia, 722, 736 Portal biliopathy, 280 Portal hypertension, hepatic fibrosis with, 48 Portal vein stenosis, 306 Portal vein thrombosis, 132, 306 Portal venous inflow alteration arterioportal shunt (APS), 264 zonal perfusion, 264–265, 277–279 Posttransplantation lymphoproliferative disease (PTLD), 308, 333 Primary biliary cirrhosis (PBC), 420 Primary sclerosing cholangitis (PSC), 420 Pseudoaccessory fissures, 4 Pseudoaneurysm, 607 Pseudocirrhosis, 225 Pseudocyst, 710, 715, 768, 785, 786 Pseudopancreatitis, 705, 716 Pyogenic hepatic abscess acute appendicitis, 245 with acute cholecystitis, 242 with biliary obstruction, 247 biliary route, 234 clinical feature, 234 with cluster sign, 235, 240 computed tomography, 234–235 direct extension route, 234 double target sign, 235, 241 E. coli, 234 with gas, 243 hepatic arterial route, 234 K. pneumoniae, 234 microabscesses associated with biliary obstruction, 250 MRI, 235 pathogenesis, 234 portal venous route, 234 from septicemia, 244 of small size, 248–249 traumatic route, 234 ultrasonography, 234, 239 with venous thrombosis, 246

832 R Radiation hepatitis, 41 Radiofrequency ablation (RFA) ablation zone, 342 abscess/infected biloma, 351–352 benign periablational enhancement, 343 bile duct injury, 541 involution of, 344 local tumor progression arterial enhancing lesion, 347 CT findings of, 346 MR images, 348–349 massive bleeding, 353 mistargeting, 350 MR findings, 345 RECIST 1.1, 338 Recurrent pyogenic cholangitis (RPC), 421 Regenerative nodule (RN) hepatocellular carcinoma, 114, 148–149 liver cirrhosis related, 26, 52 Remnant cystic duct, 541 Renal cell carcinoma, 218 Retention cyst, pancreatic tumors, 634, 663–664 Retrohepatic vena cava laceration, 367 Riedel’s lobe, 4 CT findings, 12 ultrasound findings, 11 Ruptured angiosarcoma, 201 Ruptured intraductal papillary mucinous neoplasm, 647 Ruptured splenic hemangioma, 774

S Salmonella infection, 741, 756 SANT. See Sclerosing angiomatoid nodular transformation (SANT) Sarcoidosis, 27 in liver, 56 splenomegaly associated with, 749 Sarcomas angiosarcoma, 172–173 leiomyosarcoma, 173 ruptured angiosarcoma, 201 undifferentiated embryonal sarcoma (UES), 173 Schistosoma haematobium, 237 Schistosoma japonicum, 237 Schistosoma mansoni, 237 Schistosomiasis, 237, 255 Schwannoma, 79, 108 Scirrhous-type HCC, 143–144 Sclerosed hemangioma, 89 Sclerosing angiomatoid nodular transformation (SANT) computed tomography, 767–768 in female patient, 780 in male patient, 778–779 MRI, 768 vascular structures, 767 Segmental adenomyomatosis, 464 Serous cystadenocarcinoma, 633 Serous cystic neoplasm (SCN), 633 Serous microcystic adenomas, 633, 648 oligocystic ill-defined type, 649 solid type, 650–651 Serous oligocystic ill-defined adenoma (SOIA), 633 Serum a-fetoprotein level, 669 Siderotic nodules, 26

Index Sinusoidal obstruction syndrome (SOS), 24. See also Hepatic sinusoidal injury Sinusoidal occlusive disease (SOD), 266, 294–295 Situs ambiguous, 722 Size and contour changes amyloidosis, 26 hepatitis, 25 liver cirrhosis, 25–26 Wilson’s disease, 26 Sliver of the liver, 5, 18 Solid pancreatic tumors, cystic degeneration of, 633–634 Solid pseudopapillary neoplasm (SPN) with cystic degeneration, 658–659 description, 670 gadolinium administration, 688 in male patient, 689 mass enhancement, 688 pseudocapsule, 670 Solid serous adenoma, 633 Sorafenib, 363 Spherocytosis, splenomegaly associated with, 746 Spleen. See also Diffuse splenic diseases anomalies and anatomic variations accessory spleens (see Accessory spleens) asplenia, 722, 735 intrapancreatic spleen, 732 polysplenia, 722, 736 situs ambiguous/heterotaxy, 722 splenic clefts, 722, 727, 728 splenic lobulations, 722, 723, 725, 726 splenic notches, 722 wandering spleen, 722, 734 benign focal lesions (see Benign focal splenic lesions) malignant focal lesions angiosarcoma, 794–797 lymphoma, 794, 798, 799 metastasis, 800–804 Splenic abscess, 751 Splenic angiosarcoma CT images, 794 involving whole spleen, 796 MRI findings, 794, 797 with spontaneous rupture, 795 Splenic clefts, 722 inferior border, 728 superior border, 727 Splenic contusions, 808, 810 Splenic infarction, 813 Splenic injury AAST scale, 808, 809 computed tomography, 808 hematomas and active bleeding, 814 subcapsular, 808, 811 post-operative complication, 808, 816 post-procedural complication, 809 splenic contusions, 808, 810 splenic infarction, 813 splenic laceration, 808, 812 splenic rupture, 815 subcapsular hematomas, 808, 811 Splenic laceration, 808, 812 Splenic lobulations, 722, 725 gastric subepithelial tumor, 726 lateral part, 723 medial part, 723

Index Splenic lymphoma CT image, 794 with diffuse involvement, 798 focal mass, 799 MRI finding, 794 Splenic metastasis, 794 of endometrial adenocarcinoma, 801–802 of hepatocellular carcinoma, 803–804 of nasopharyngeal carcinoma, 800 Splenic notches, 722 Splenic rupture, 815 Splenic vein occlusion, 744 Splenomegaly congestive with alcoholic liver cirrhosis, 743 cause of, 740 with inferior vena cava obstruction, 745 with liver cirrhosis, 742 with splenic vein occlusion, 744 etiology-based categorization, 740 hyperplastic splenomegaly, 740 with polycythemia vera, 747 with spherocytosis, 746 infiltrative splenomegaly, 740 with amyloidosis, 750 with Gaucher’s disease, 748 with sarcoidosis, 749 inflammatory, 740 splenic abscess, 751 SPN. See Solid pseudopapillary neoplasm (SPN) Squamous cell carcinoma, of uterine cervix, 224 Strasberg classification, 544 Subcapsular hematomas, 366, 808, 811 Sunitinib malate, 454

T Tardus parvus waveform, 306 Teardrop sign, 668 TNM staging system T1a stage, 503, 512 T1b stage, 503, 513 T2 stage, 503, 514 T3 stage, 503, 515 T4 stage, 503, 516 Todani type I fusiform dilatation, 395, 405 Todani type II diverticulum, 395, 406 Todani type III choledochocele, 395 Todani type IV intra and extrahepatic duct cysts, 395, 407 Todani type V Caroli disease, 395, 408–409 Transabdominal US acute pancreatitis, 588 chronic pancreatitis, 590 Transarterial radioembolization (TARE), 362 Transcatheter arterial chemoembolization (TACE), 336, 541 Transient hepatic attenuation difference from arterioportal fistula, 273 diagram of, 269 hepatocellular carcinoma with, 271 portal vein thrombosis causing, 286 with superior vena cava obstruction, 285 Traumatic pancreas injury blunt traumatic injury, 704 CT findings, 704 delayed gastric emptying, 705 differential diagnosis, 705

833 ERCP, 704 grading of, 704, 705 MDCT, 704 MRCP, 704 pancreatic fistula, 705 post-operative complication, 705 post-procedural complication, 705 pseudopancreatitis, 705 T staging system, 475 T-tubes, 307 Tuberculosis diffuse splenic diseases, 752 with acquired immunodeficiency syndrome, 754 calcified, 753 miliary, 741 focal hepatic infections, 259 Tumor spread, gallbladder direct invasion, liver, 503–504, 517 hematogenous spread, liver and lung, 504, 519 lymphatic spread to regional lymph nodes, 504, 518 peritoneum metastasis, 504, 520 Type 1 autoimmune pancreatitis, 593 diffuse type, 618–620 focal type, 621–622 IgG4-related disease, 594 typical pathology, 616 Type 2 autoimmune pancreatitis diffuse type, 626–627 focal type, 628 granulocyte epithelial lesions, 593 typical pathology, 617

U Ultrasonography (US) amebic liver abscess, 236 benign focal splenic lesions bacterial abscess, 769 echinococcal cyst, 768–769 EMH, 768 epidermoid cyst, 768 fungal abscess, 769 hamartoma, 767 hemangioma, 766 IMT, 768 littoral cell angioma, 767 lymphangioma, 767 biliary hamartoma, 69 focal eosinophilic liver disease, 238 hepatic candidiasis, 60, 238 hepatic fibrosis, 43 multinodular fat deposition, 71 nonalcoholic steatohepatitis, 31 pyogenic hepatic abscess, 234, 239 Uncinate process, 568 Undifferentiated carcinoma with osteoclast-like giant cells, 669, 683–684 Undifferentiated embryonal sarcoma (UES), 173, 200 Unilocular pancreatic cyst, 632

V Vascular disorders congenital vascular malformation, 267 HA, 305–306

834 Vascular disorders (cont.) HELLP syndrome, 266, 296 IVC, 306–307 MDCT, 305 PV thrombosis, 306 Vascular extravasation, 367 Vena cava, membranous obstruction of, 289–290 Venous thrombosis, 608 von Hippel-Lindau (VHL) disease associated cystic neoplasm, 633 with pancreatic cyst, 570, 585 von Meyenburg complexes. See Biliary hamartoma

Index W Walled-off necrosis (WON), 589, 600, 601 Wandering spleen, 722, 734 Wilson’s disease, 26

X Xanthogranulomatous cholecystitis, 449, 451

Z Zebra-striped splenic enhancement pattern, 672 Zonal perfusion changes, 264–265, 277–279