A Granular Cell Tumor of the Rectum: A Case Report and Review of the Literature.

A granular cell tumor (GCT) is an uncommon mesenchymal lesion that rarely occurs in the colon and the rectum. We describe the case of 51-year-old man with a 2-cm-sized rectal GCT 10 cm above the anal verge that was incidentally detected after a screening colonoscopy. Preoperative radiologic studies demonstrated a suspicious submucosal rectal mass with mesorectal fat infiltration, but without circumferential resection margin threatening, extramural vessel invasion, and regional lymph-node enlargement. The tumor was resected by using a transanal endoscopic operation (TEO) without immediate postoperative complications. The final pathology revealed that the tumor consisted of a GCT that had invaded the subserosa with clear margins. It had no other risk factors for malignancy according to Fanburg-Smith criteria. We systematically reviewed the English literature by using PubMed and Google Scholar. This report may be the first documented case in the literature to describe a TEO for a GCT that had invaded the subserosa in the rectum.