Heterotopic ossification of rectal adenocarcinoma: report of a case.

Heterotopic ossification of gastrointestinal tract tumors is rare. We report the case of a 67-year-old man with heterotopic ossification of a rectal adenocarcinoma. The patient presented with intermittent abdominal pain and frequent diarrhea, and colonoscopic examination showed a large polypoid tumor partially obstructing the rectal lumen. Abdominal computed tomography (CT) revealed a large tumor in the rectal lumen with calcified spots. We performed low anterior resection of the rectum, and histologic examination showed a well-differentiated adenocarcinoma with heterotopic ossification infiltrating the full thickness of the rectum. Local recurrence and liver metastases were found 2 months after surgery, and the patient died 3 months later. Such a rapidly progressive course of rectal adenocarcinoma with heterotopic ossification is very unusual.