Osseous Metaplasia in a Colon Polyp

Osseous metaplasia occurring in colorectal neoplasia is extremely rare. The incidence, severity, morbidity and mortality are poorly documented in the literature. A 44-year-old male presented for colonoscopy due to a report of bright red blood per rectum. During the colonoscopy, a 5mm sigmoid polyp was removed with snare electrocoagulation. Histology showed osseous metaplasia embedded within a hyperplastic colon polyp. Eleven cases have now been described in the literature of osseous metaplasia in benign colorectal neoplasia. Osseous metaplasia is predominately found in left colon lesions as 64% of cases occurred in the rectum and sigmoid. Isolated cases have been found in the ileum, jejunum, stomach and esophagus. This is the first case of osseous metaplasia in a hyperplastic polyp of the sigmoid colon. Osseous metaplasia is a rare finding in colorectal polyps with undetermined clinical significance.