Osseous metaplasia in an inflammatory polyp of the anal canal – a case report and a review of literature

Abstract

Introduction Osseous metaplasia is a heterotopic formation of bone and its appearance in benign gastrointestinal polyps is exceedingly rare. The mechanism responsible for this type of metaplasia is not fully understood, however it seems to be an innocent rare phenomenon.

Case outline We present a case of a 31-year-old male with mesenchimal osseal metaplasia in a large inflamatory polyp measuring 57 × 23 × 20 mm in diameter, located in the anal canal region.

Conclusion According to our knowledge, this is the largest gastrointestinal polyp with osseous metaplasia described so far. Although a rare phenomenon, there are certain characteristics of this disease, so we conducted a literature review and summarized these characteristics.

Keywords: osseous metaplasia; gastrointestinal polyps; inflamatory polyps