Sigmoid schwannoma: a rare case.

Schwannomas are rare tumors derived from the cells of Schwann that form the neural sheath. When located in the gastrointestinal tract, they constitute together with leiomyoma, leiomyoblastoma, and leiomyosarcoma, the gastrointestinal stromal tumors (GIST). Peripheral nerve sheath tumors represent 2-6% GIST with most common location, the stomach and the small intestine. Schwannomas of the colon and rectum are extremely rare and radical excision with wide margins is mandatory, due to their tendency to recur locally and become malignant, if left untreated. In the present study, we report a rare case of a sigmoid schwannoma, which was successfully treated in our department and reviewed the literature.