(Fibro) xanthogranulomatous cholecystitis is an uncommon lesion which may form a tumor-like mass in inflamed gallbladders. A few cases have been mistaken for neoplasms. In a review of 40 cases there were 26 associated with gallstones and nine with tumors of the biliary tract, six of which also had stones. Grossly the lesions are usually soft, are yellow to brown, and measure up to 2.5 cm. Microscopically, there are varying amounts of inflammation, xanthoma-like foam cells, and scarring. The lesions appear to result from ruptured Rokitansky-Aschoff sinuses with intramural extravasation of bile and subsequent xanthogranulomatous reaction.