Osseous Metaplasia in Juvenile Polyps: Report of Four Cases and Review of Literature.

There are occasional reports of osseous metaplasia (OM) occurring in gastrointestinal polyps. We report 4 cases occurring in juvenile retention polyps. Four juvenile retention polyps presented with rectal bleeding. Microscopically there was osseous metaplasia in addition to the typical surface ulceration and granulation tissue appearance. Osseous metaplasia was only detected on histopathologic examination of the resected polyps. Although the clinical significance is not established, OM suggests that the polyps have been present for a longer period of time.