Imaging description

Adenomyomatosis (or diverticular disease of the gallbladder) is an acquired hyperplastic condition characterized by excessive proliferation of surface epithelium with deepened invaginations or diverticula (so-called Rokitansky-Aschoff sinuses) extending into the thickened muscular layer of the gallbladder wall [1]. Adenomyomatosis of the gallbladder results in focal or diffuse wall thickening that contains small cyst-like spaces at cross-sectional imaging (Figure 24.1). These cyst-like spaces may give rise to the “pearl necklace” sign at T2-weighted MRI (Figure 24.2) [2]. The condition has a predilection for the gallbladder fundus (Figure 24.3). The central gallbladder may also be affected, resulting in a relatively typical “hourglass” configuration (Figure 24.4).

Importance

Gallbladder wall thickening may suggest the diagnosis of gallbladder cancer, resulting in unnecessary workup or even surgery. The “compartmentalization” of the gallbladder in the hourglass type of adenomyomatosis may result in failure to identify the distal compartment at ultrasound (Figure 24.5) or contribute to incomplete cholecystectomy when only the distal half of the gallbladder is removed at surgery (Figure 24.6).

Typical clinical scenario

Depending on the series, adenomyomatosis is seen in 1 to 8.7% of cholecystectomy specimens [3–5]; this wide range may reflect population differences or variability in the rigorousness of pathological diagnostic criteria and assessment. Adenomyomatosis is usually associated with gallstones [4], in which case treatment of the gallstones determines clinical management. The appropriate treatment strategy for acalculous adenomyomatosis is not well established.