# Gallbladder osseous metaplasia mimicking a focal lesion on ultrasound: a case report of a rare benign condition

## TL;DR

A rare benign gallbladder condition with bone-like tissue was mistaken for a more serious issue on ultrasound.

## Contribution

Reports a rare case of gallbladder osseous metaplasia associated with adenomyosis and chronic cholecystitis.

## Key findings

- Osseous metaplasia was identified in a patient with focal gallbladder wall thickening.
- No evidence of dysplasia or malignancy was found in pathological examination.
- The condition mimicked malignant or inflammatory processes on imaging.

## Abstract

Focal gallbladder wall thickening may raise suspicion for inflammatory, hyperplastic, or malignant processes. We report a rare case of chronic cholecystitis associated with adenomyosis and osseous metaplasia in a 43-year-old woman with multiple comorbidities. The patient presented with right upper quadrant abdominal pain. Ultrasonography revealed focal gallbladder wall thickening without calculi. She underwent uneventful laparoscopic cholecystectomy. Gross and microscopic pathological examination demonstrated chronic cholecystitis with mucosal hyperplasia, intramural diverticula consistent with adenomyosis, and areas of osseous metaplasia, with no evidence of dysplasia or malignancy. The postoperative course was uncomplicated. Awareness of such rare benign lesions is essential, as they may clinically and radiologically mimic more aggressive disease.