Rectal gastrointestinal stromal tumor as an incidental finding in a patient with rectal polyps.

A patient who was diagnosed as rectal polyps in the local hospital went to our hospital for surgical treatment. Abdominal CT demonstrated a large irregular extra-luminal tumor of at least 5 cm cross-section on the ventral side of the lower rectal wall. Intraoperatively, a large irregular extra-luminal tumor (about 5×4.5×4 cm) was found. Anterior resection with end colostomy and rectal stump (Hartmann's procedure) was performed. Postoperative histological examination showed simultaneous development of rectal GIST and polyps.