대장용종의 골화생

초록

Heterotopic or metaplastic bone formation is a rare occurrence in the gastrointestinal tract that has been documented to occur in association with benign and malignant epithelial tumors, hamartomatous polyps in Peuts-Jeghers syndrome, and Barrett's esophagus. Heterotopic ossification occurring in adenocarcinoma is relatively common but there are only a few previous case reports of ossification in tubulovillous adenoma, a rectal tubular adenoma, a carcinoid tumor of the stomach, and a mucocele of the appendix. Histologically most ossification in malignant lesions occurs with tumoral necrosis and extracellular mucin, but in benign lesions it occurs without such associated findings. The pathogenesis of heterotopic ossification is unknown. There has been speculation that mucinous malignant tumor secrete an unknown substance that stimulate bone formation of the tumor necrosis provides a nudus for metaplastic ossification. However, this does not account for the ossification iccurring in benign polyps. We report a case of metaplastic ossificaiton occurring in tubulovillous adenoma of rectum. the patient was 17 year old man and suffered from intermittent abdominal pain for 4 years. He complained frequent diarrhea without constipation or hematochezia. Laboratory test and abdominal sonography were unremarkable. Endoscopic gastroduodenal examination was normal. Sigmoidoscopy showed an elevated polyp, about 1cm in size. Histology revealed tubulovillous adenoma with extracellular mucin, surface erosion, granulation tissue, and old and fresh hemorrhage. Small bone trabeculae surrounded by osteoblasts are seen in lamina propria below the adenomatous and hysplastic epithelium.