A case of gastrointestinal stromal tumor of the rectum

A 70-year-old man consulted us because of right lower abdominal pain. Diagnostic imaging revealed a submucosal tumor with central ulceration in the left anterior wall of the lower rectum. Transanal needle biopsy was performed, and the specimen was histologically diagnosed as mesenchymal tumor. A Miles operation was performed following the diagnosis, and histological examination of the resected specimen showed the tumor to be composed of interlacing fascicles of spindle shaped cells. Immunohistochemical testing was negative for desmin and mucle-actin, and positive for vimentin, CD34, neuro-specific enolase (NSE), and c-kit, compatible with gastrointestinal stromal tumor (GIST).