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Hepatobiliary and pancreatic: Adenomyomatosis of the gallbladder with abscess formation

Adenomyomatosis is a disease of the gallbladder characterized by epithelial proliferation, hypertrophy of the muscularis externa and outpouching of the mucosa into the thickened muscle layer resulting in the formation of Rokitansky-Aschoff sinuses. The disorder may involve the whole of the gallbladder, a segment of gallbladder (often the mid-portion) or a localized area (usually the fundus). The disorder is more common in women than in men (ratio 3:1) and increases in prevalence with advancing age. At least 50% of patients have coexisting gallstones. In resected gallbladder specimens, the frequency of adenomyomatosis is debated but appears to range between 1% and 9%. This variation may reflect the application of different pathological criteria in different studies. The cause of adenomyomatosis remains unclear but may involve increases in intraluminal pressure because of an obstructing calculus or a narrow cystic duct. There are also reports of an association with an anomalous pancreaticobiliary ductal junction. Thus far, there is no persuasive evidence of an association between adenomyomatosis and gallbladder cancer. In the patient described below, adenomyomatosis appeared to be responsible for the development of a small abscess in the gallbladder wall. This may be the first report of this complication in the medical literature. The patient was a 78-year-old woman with primary biliary cirrhosis (Scheuer stage 4) who was admitted to hospital because of abnormalities on abdominal imaging. Changes on a contrastenhanced computed tomography (CT) scan are shown in Figure 1. The left panel shows a spherical lesion in the fundus of the gallbladder (arrowhead) while the right panel shows a more heterogeneous lesion with some enhancement by contrast (arrow). With magnetic resonance imaging, cystic structures were shown within the gallbladder lesion and these structures had high signal intensity on T2-weighted images. Serum levels of inflammatory markers and tumor markers including carbohydrate antigen 19.9 were within the reference range. The patient was treated by cholecystectomy because of the possibility of a malignant polyp. A macroscopic examination of the resected specimen showed a round tumor with apparently normal mucosa and a central dimple. Histological evaluation revealed adenomyomatosis with abscess formation but no malignancy (Figure 2). An inflammatory cell infiltrate, largely composed of neutrophils, was observed in the thickened gallbladder wall and in the Rokitansky-Aschoff sinuses (right panel).