Heterotopic ossification within the gallbladder – First reported Australian case

INTRODUCTION: We report the rare and unusual case of heterotopic ossification within the gallbladder secondary to chronic calculi debris. Presentation of case. A 35-year-old female underwent routine laparoscopic cholecystectomy for recurrent intermittent right upper quadrant pain which had persisted for three months and was worse post prandial with associated nausea. Abdominal ultrasound prior to surgery was reported by a consultant radiologist as demonstrating a thin-walled gallbladder and cholelithiasis, without features of cholecystitis. At four-week review, she had recovered well with no concerns. The histopathology report revealed fibromuscular hyperplasia and patchy chronic inflammation. Rokitansky-Aschoff sinuses were present and cholesterosis was noted. Additionally, there was a focus of eroded mucosa showing adherent microlithiasis with an incidental focus of heterotopic ossification within the mucosa, there was no evidence of dysplasia or malignancy. DISCUSSION: Gallbladder heterotopic ossification is exceedingly rare, with few cases reported. To our knowledge this is the first reported case in Australia. CONCLUSION: In conclusion, we report the rare and unusual finding of heterotopic ossification of the gallbladder, and suspect that inflammation secondary to calculous debris initiated the ossification. Current technical limitations preclude diagnosis prior to surgery. Appropriate follow-up is unclear, but we feel a single report associated the finding with adenocarcinoma was sufficient to warrant follow-up.