DOI: 10.1148/rg.263055180
RadioGraphics 2006;26:941-946
© RSNA, 2006
Best Cases from the AFIP
Adenomyomatosis of the Gallbladder1
Alexis R. Boscak, MD,
Mahmoud Al-Hawary, MD and
Stephen R. Ramsburgh, MD
1 From the Departments of Radiology (A.R.B., M.A.H.) and Pathology (S.R.R.), University of Michigan, B1D502, 1500 E Medical Center Dr, Ann Arbor, MI 48109-0030. Received September 28, 2005; revision requested November 3 and received December 15; accepted December 15. All authors have no financial relationships to disclose.
Address correspondence to A.R.B. (e-mail: aboscak{at}med.umich.edu).
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History
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A 48-year-old man presented to the emergency department with acute onset of jaundice superimposed on 3 months of constant dull right upper quadrant pain accompanied by postprandial nausea and vomiting. Additional symptoms included generalized pruritus and fatigue. He described an unintentional loss of approximately 20 lb (9 kg) over the past few months. His medical history was limited to hepatitis C infection diagnosed 5 years previously, believed to have been contracted as a result of blood transfusion for trauma 20 years earlier. Because of recent insomnia, he had taken two over-the-counter diphenhydramine-acetaminophen tablets on each of the three evenings preceding presentation. He reported no recent change in his baseline alcohol consumption of one six-pack of beer per week.
The patient appeared well nourished and in no acute distress. Vital signs were normal, and he was afebrile. His skin and sclerae were icteric, and he had areas of excoriation on his back. He had no other visible stigmata of liver failure. His abdomen was nontender with no evidence of organomegaly or ascites. Laboratory evaluation revealed conjugated hyperbilirubinemia (total bilirubin level, 10 mg/dL [171 µmol/L]) with mildly elevated levels of transaminases and alkaline phosphatase. Amylase, lipase, and albumin values; results of a coagulation panel; and a complete blood cell count were within the normal range. Hepatobiliary disease was suspected, and ultrasonography (US) was performed.
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Imaging Findings
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US revealed an abnormally thick gallbladder wall containing multiple echogenic intramural foci with "comet tail" reverberation artifacts (Fig 1), as well as a questionably impacted calculus within the gallbladder neck. The biliary system was not dilated. There was no pericholecystic fluid. The sonographic Murphy sign (pain elicited by pressure over the gallbladder during scanning) was absent. Adenomyomatosis and cholelithiasis were diagnosed; cholecystitis was considered unlikely. No other sonographic abnormalities were identified.
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Figure 1a. Longitudinal (a) and transverse (b) US images show a thickened gallbladder wall and echogenic intramural foci with comet tail reverberation artifacts (arrow), indicative of cholesterol crystals within Rokitansky-Aschoff sinuses. The "comet tails" extend from the near wall into the anechoic lumen; echoes from the far wall are obscured by echogenic adjacent tissue.
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Figure 1b. Longitudinal (a) and transverse (b) US images show a thickened gallbladder wall and echogenic intramural foci with comet tail reverberation artifacts (arrow), indicative of cholesterol crystals within Rokitansky-Aschoff sinuses. The "comet tails" extend from the near wall into the anechoic lumen; echoes from the far wall are obscured by echogenic adjacent tissue.
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Because of high clinical suspicion of an obstructive process involving the common bile duct with concern about the possibility of pancreatic malignancy, additional imaging evaluation including abdominal computed tomography (CT) and magnetic resonance (MR) imaging was performed. Axial 2.5-mm-thick CT sections were obtained with helical scanning (pitch of 1.5, 365 mA, 120 kVp) and a 60-second delay after intravenous administration of a contrast material bolus at 3 mL/sec. The CT images demonstrated diffuse gallbladder wall thickening with mural enhancement (Fig 2). MR imaging was performed with a 1.5-T unit and included unenhanced T2-weighted images (repetition time msec/echo time msec = 9600/95) as well as gadolinium-enhanced T1-weighted images (5.2/2.4). The MR images demonstrated diffuse gallbladder wall thickening with mural enhancement and revealed multiple intramural cystic spaces, some of which contained signal voids consistent with calculi (Fig 3). The CT and MR imaging findings were considered confirmatory of the sonographic diagnoses of adenomyomatosis and cholelithiasis.
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Figure 2a. Axial CT images (a obtained superiorly to b) show a thickened gallbladder wall and abnormally intense mucosal enhancement. There are discrete hypoattenuating intramural lesions (arrow), which represent Rokitansky-Aschoff sinuses.
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Figure 2b. Axial CT images (a obtained superiorly to b) show a thickened gallbladder wall and abnormally intense mucosal enhancement. There are discrete hypoattenuating intramural lesions (arrow), which represent Rokitansky-Aschoff sinuses.
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Figure 3a. Axial unenhanced T2-weighted (a, b) and axial contrast-enhanced T1-weighted (c, d) MR images (a and c obtained superiorly to b and d, respectively) show a diffusely thickened gallbladder wall and intramural cavities, which are hyperintense on the T2-weighted images, hypointense on the T1-weighted images, and nonenhancing. The cavities represent Rokitansky-Aschoff sinuses containing fluid bile. Mineralized calculi are visualized as focal signal voids (arrow).
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Figure 3b. Axial unenhanced T2-weighted (a, b) and axial contrast-enhanced T1-weighted (c, d) MR images (a and c obtained superiorly to b and d, respectively) show a diffusely thickened gallbladder wall and intramural cavities, which are hyperintense on the T2-weighted images, hypointense on the T1-weighted images, and nonenhancing. The cavities represent Rokitansky-Aschoff sinuses containing fluid bile. Mineralized calculi are visualized as focal signal voids (arrow).
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Figure 3c. Axial unenhanced T2-weighted (a, b) and axial contrast-enhanced T1-weighted (c, d) MR images (a and c obtained superiorly to b and d, respectively) show a diffusely thickened gallbladder wall and intramural cavities, which are hyperintense on the T2-weighted images, hypointense on the T1-weighted images, and nonenhancing. The cavities represent Rokitansky-Aschoff sinuses containing fluid bile. Mineralized calculi are visualized as focal signal voids (arrow).
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Figure 3d. Axial unenhanced T2-weighted (a, b) and axial contrast-enhanced T1-weighted (c, d) MR images (a and c obtained superiorly to b and d, respectively) show a diffusely thickened gallbladder wall and intramural cavities, which are hyperintense on the T2-weighted images, hypointense on the T1-weighted images, and nonenhancing. The cavities represent Rokitansky-Aschoff sinuses containing fluid bile. Mineralized calculi are visualized as focal signal voids (arrow).
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MR imaging also revealed a bulky pancreatic head, enhancement of the distal common bile duct, and an enlarged peripancreatic lymph node. No pancreatic or peripancreatic abnormality was detected with CT. Endoscopic US demonstrated an ill-defined periampullary pancreatic head mass. Endoscopic retrograde cholangiopancreatography showed mild distal pancreaticobiliary tapering suggestive of stricture; a brushing specimen was obtained. Cytologic analysis revealed clusters of spindle cells suggestive of stromal tumor. Surgical resection was planned for suspected pancreatic malignancy.
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Pathologic Evaluation
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Pancreaticoduodenectomy and cholecystectomy with pancreaticojejunostomy, choledochojejunostomy, and gastrojejunostomy were performed 6 weeks after initial presentation. At laparotomy, no obvious pancreatic mass was identified, and resection margins were negative for malignancy at intraoperative frozen section analysis. No discrete lesion was detected within the resected portion of the pancreas at gross pathologic examination. The gallbladder was firm with velvety granular mucosa and contained numerous multifaceted intraluminal calculi. The gallbladder wall was diffusely thick, measuring up to almost 2 cm, and contained multiple pockets, many of which also contained calculi (Fig 4).
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Figure 4. Longitudinal gross section of the gall-bladder shows a diffusely thickened wall and multiple cystic intramural cavities. The cavities correspond to Rokitansky-Aschoff sinuses and are filled with calculi.
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There was no evidence of malignant neoplasia at review of permanent microscopic sections. The final primary diagnosis was inflammatory pseudo-tumor of the pancreas. The incidental finding of adenomyomatosis of the gallbladder suspected at US, CT, and MR imaging was confirmed by the characteristic histopathologic appearance of muscular and epithelial hyperplasia contributing to mural thickening, with epithelial invaginations forming the pathognomonic intramural diverticula known as Rokitansky-Aschoff sinuses (Fig 5).
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Figure 5. Photomicrograph (original magnification, x20; hematoxylin-eosin stain) shows inspissated bile within a hypertrophied gland lined by benign epithelium that has herniated into the muscularis of the gall-bladder wall, inciting an inflammatory reaction. This appearance represents the pathognomonic Rokitansky-Aschoff sinus.
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Discussion
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This case is notable for its documentation of the findings of adenomyomatosis of the gallbladder at multimodality evaluation including US, CT, and MR imaging. Such an extensive work-up is not typically indicated in uncomplicated adenomyomatosis, but it was undertaken for our patient because of suspected pancreatic malignancy.
The findings suspicious for possible malignancy in this case were ultimately attributed to inflammatory pseudotumor of the pancreas, also termed inflammatory myofibroblastic tumor. This rare benign entity is microscopically characterized by an admixture of spindle cells and chronic inflammatory cells; the gross and imaging appearance may be difficult to differentiate from that of malignancy (1). There is no known association with adenomyomatosis of the gallbladder.
Adenomyomatosis, also termed adenomyomatous hyperplasia of the gallbladder, is a benign hyperplastic cholecystosis. It is a relatively common condition, identified in at least 5% of cholecystectomy specimens. There is no definite racial or sex predilection. Most diagnoses are made in patients in their 50s, but the age range is wide and case reports exist of pediatric adenomyomatosis. Adenomyomatosis is most often an incidental finding, has no intrinsic malignant potential, and usually requires no specific treatment. It frequently coexists with cholelithiasis, but no causative relationship has been proved. Adenomyomatosis occasionally produces abdominal pain, and in some cases cholecystectomy may be indicated for relief of symptoms.
The gallbladder wall is composed of four layers: mucosa, lamina propria, muscularis propria, and serosa; the gallbladder has no muscularis mucosa or submucosa. The wall thickening of adenomyomatosis involves hyperplasia of both mucosa and muscularis propria. Cholesterolosis, the other hyperplastic cholecystosis, consists of deposition of triglycerides and cholesterol esters within the lamina propria, producing a characteristic gross appearance known as "strawberry gallbladder." Cholesterol accumulation in adenomyomatosis is intraluminal, as cholesterol crystals precipitate in the bile trapped in Rokitansky-Aschoff sinuses, intramural diverticula lined by mucosal epithelium. Gallbladder wall thickening and intramural diverticula containing bile with cholesterol crystals, sludge, or calculi are the pathologic correlates of the distinctive multimodality imaging features of adenomyomatosis (2).
US is a primary modality for biliary imaging, and adenomyomatosis of the gallbladder is frequently identified at sonography. The nonspecific finding of gallbladder wall thickening is well demonstrated with US, as are sludge and calculi, when present. Echogenic intramural foci from which emanate V-shaped comet tail reverberation artifacts are highly specific for adenomyomatosis, representing the unique acoustic signature of cholesterol crystals within the lumina of Rokitansky-Aschoff sinuses (3).
Biliary sludge and calculi may be detected as high-attenuation intraluminal material at nonenhanced CT, but administration of intravenous contrast material is necessary for optimal CT evaluation of the gallbladder. Abnormal gallbladder wall thickening and enhancement are common but nonspecific CT features of adenomyomatosis. Rokitansky-Aschoff sinuses of sufficient size can be visualized; a CT "rosary sign" has been described, formed by enhancing epithelium within intramural diverticula surrounded by the relatively unenhanced hypertrophied gallbladder muscularis (4).
MR imaging readily demonstrates gallbladder wall thickening and reveals Rokitansky-Aschoff sinuses as intramural lesions that are hyperintense on T2-weighted images, hypointense on T1-weighted images, and nonenhancing (5). MR cholangiopancreatography can show an appearance similar to the classic appearance of adenomyomatosis on the now infrequently obtained oral cholecystogram, on which intramural diverticula may be opacified by intraluminal contrast material, if patent and of sufficient size. The "pearl necklace sign" alludes to the characteristically curvilinear arrangement of multiple rounded hyperintense intraluminal cavities visualized at T2-weighted MR imaging and MR cholangiopancreatography of adenomyomatosis (6). Intraluminal calculi may appear as signal voids due to their mineral content, as in this case. Identification of abnormal enhancement requires a multiphasic MR imaging protocol with intravenous contrast material.
Although the imaging features of adenomyomatosis can be distinctive enough to allow confident diagnosis, findings such as gallbladder wall thickening and enhancement are somewhat non-specific. Therefore, the radiologic differential diagnosis may include other benign gallbladder conditions, such as polyposis, papillomatosis, adenoma, and cystadenoma, as well as malignancies such as gallbladder adenocarcinoma, cholangiocarcinoma, hepatocellular carcinoma, and meta-static cancer.
Gallbladder involvement by adenomyomatous hyperplasia is variable in extent and location, with heterogeneous imaging appearances corresponding to diffuse, segmental, and focal adenomyomatosis. Diffuse or generalized adenomyomatosis consists of widespread gallbladder involvement. Segmental or annular adenomyomatosis appears as limited circumferential gallbladder wall involvement with luminal narrowing, typically within the gallbladder body, which may produce a characteristic hourglass configuration. Focal or localized adenomyomatosis is most common, manifesting as crescentic to rounded gallbladder wall thickening, usually at the fundus. Exclusion of malignancy may be most problematic in segmental and focal cases; in fact, focal adenomyomatosis may appear as a discrete mass, known as an adenomyoma. Metabolic characterization with fluorine 18 fluorodeoxyglucose positron emission tomography may be a useful adjunct in problematic cases (7).
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Conclusions
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Adenomyomatosis is a relatively common benign gallbladder abnormality with distinctive gross and histopathologic features corresponding to relatively specific findings at multimodality imaging. Surgical resection may be indicated in symptomatic cases and when nonspecific findings present a diagnostic dilemma.
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Footnotes
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Editor’s Note.—Everyone who has taken the course in radiologic pathology at the Armed Forces Institute of Pathology (AFIP) remembers bringing beautifully illustrated cases for accession to the Institute. In recent years, the staff of the Department of Radiologic Pathology has judged the "best cases" by organ system, and recognition is given to the winners on the last day of the class. With each issue of RadioGraphics, one or more of these cases are published, written by the winning resident. Radiologic-pathologic correlation is emphasized, and the causes of the imaging signs of various diseases are illustrated.
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References
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- To’o KJ, Raman SS, Yu NC, et al. Pancreatic and peripancreatic diseases mimicking primary pancreatic neoplasia. RadioGraphics 2005;25:949–965.[Abstract/Free Full Text]
- Levy AD, Murakata LA, Abbott RM, Rohrmann CA. Benign tumors and tumorlike lesions of the gallbladder and extrahepatic bile ducts: radiologic-pathologic correlation. RadioGraphics 2002;22: 387–413.[Abstract/Free Full Text]
- Hwang JI, Chou YH, Tsay SH, et al. Radiologic and pathologic correlation of adenomyomatosis of the gallbladder. Abdom Imaging 1998;23:73–77.[CrossRef][Medline]
- Chao C, Hsiao HC, Wu CS, Wang KC. Computed tomographic finding in adenomyomatosis of the gallbladder. J Formos Med Assoc 1992;91:467–469.[Medline]
- Kim MJ, Oh YT, Park YN, et al. Gallbladder adenomyomatosis: findings on MRI. Abdom Imaging 1999;24:410–413.[CrossRef][Medline]
- 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;227:80–88.[Abstract/Free Full Text]
- Koh T, Taniguchi H, Kunishima S, Yamagishi H. Possibility of differential diagnosis of small polypoid lesions in the gallbladder using FDG-PET. Clin Positron Imaging 2000;3:213–218.[CrossRef][Medline]
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History
Imaging Findings
