[Undifferentiated pleomorphic sarcoma detected in the descending colon: report of a case].

Undifferentiated pleomorphic sarcoma was a well-known tumor that usually involves the soft tissues. However, in the alimentary tract, it was seldom reported. A 55-year-old man was admitted to our hospital with lower abdominal pain. Endoscopic examination showed a protruding tumor occupied the lumen of the descending colon. Because of the colon obstruction by the tumor, a left hemicolectomy with en bloc lymph node dissection was performed. Main occupied lesion of the tumor was mesenterium and submucosa, with no epithelial dysplasia. Also, dissemination of the tumor was recognized in the mesenterium and greater omentum. Based on histological and immunohistological studies, the tumor was diagnosed as undifferentiated pleomorphic sarcoma.