Osseous Metaplasia of the gallbladder: report of two cases

Abstract

O sseous metaplasia, which is also known as heterotopic bone, heterotopic ossification, bone metaplasia, is rarely reported in gallbladder and its clinical significance is unknown. The exact mechanism of bone formation in the various parts of the body is not clear but it can be related with some conditions like phleboliths, benign neoplasm and malignancies, epithelial tissues of gastric mucosa, seminal vesicle mucosa, osteoinduction by chronic inflammation and postoperative abdominal scars.[1] Stromal fibroblastic proliferation, chronic and active inflammation may play a role in its formation in the gallbladder mucosa. Here we report two cases with the review of the literature. Case ReportCase 1 A 37-year-old male presented to the department of internal medicine with right upper quadrant pain continuing for 5 days. He was afebrile at presentation, with stable vital signs. Physical examination demonstrated a positive Murphy sign. Laboratory findings were unremarkable for whole blood count, liver function tests, sedimentation, ASO and CRP. Ultrasonography revealed small gallbladder stones. A laparoscopic cholecystectomy was performed with an uneventful postoperative course. The excised gallbladder measured 7 x 2.5 x 2 cm with three black intraluminal 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.