Schwannoma in the sigmoid colon: report of a case.

Schwann cell tumor occurring in the intestines is rare. A 68-year-old female came to our hospital because of hematemesis. Barium enema and colonoscopic examination revealed submucosal tumor in the sigmoid colon. Laboratory data showed mild anemia. No other abnormal finding was found in the blood chemistry. Tumor marker levels of carcinoembryonic antigen (CEA), CA19-9, alpha feto protein (AFP) and neuron specific enolase (NSE) were within normal limits. The exploratory laparotomy confirmed a large sigmoid colon tumor. She received sigmoid colectomy. The resected specimen was a submucosal tumor with central depression, measuring 4.7 x 3.5 x 3.0 cm in size. The cut surface of the tumor was yellowish hue with necrosis. Histological examination showed spindle-shaped tumor cells with palisading comma-shaped nuclei and the nuclear pleomorphism. Immunohistochemical examination revealed that the tumor was positive for S-100 protein staining, and negative for Actin and for H.H.F. staining. These findings showed that this tumor was of Schwann cell origin. We report here the case in detail of a schwannoma in the sigmoid colon.