Osseous Metaplasia of the Gallbladder: Report of Two Cases

Abstract

Osseous metaplasia is rarely seen in the gastrointestinal tract. Its occurrence in the gallbladder is even more rare; only 7 cases have been reported thus far. Two additional cases are described herein: one was an incidental finding and the other simulated an intramural gallstone in a chronically inflamed, calculi-containing gallbladder. The patients were a 32-year-old man and a 52-year-old man who presented with abdominal pain. Ultrasonography revealed small gallstones in 1 patient. Laparoscopic cholecystectomies were performed and histologies were consistent with chronic cholecystitis and cholelithiasis with intramucosal bone formations. One of the patients also had an adenomyoma in the fundus. Osseous metaplasia of the gallbladder is a rare event. It is mostly incidental and although its etiology and clinical significance are unknown, it may mimic a gallstone, which could affect treatment options. The pathogenesis could be osteogenic stimulation as a result of the inflammatory process.