Leiomyosarcoma of the rectum with sarcoid-like reaction--a case report.

A 57 year-old man was admitted to the hospital because of bloody stools. A barium enema and coloscopy disclosed a tumor of the rectum. The resected tumor was diagnosed as a leiomyosarcoma, histologically. Many epithelioid granulomas with Langhans type giant cells were found in the tumor, and there was no evidence suggestive of generalized sarcoidosis, tuberculosis or mycosis. Thus, the epithelioid granulomas seen in the leiomyosarcoma were interpreted as a sarcoid-like reaction. As far as could be determined, there has been no reported case of a sarcoid-like reaction associated with a leiomyosarcoma. The occurrence of the sarcoid-like reaction in the present case could be due to the reaction to the metabolites or a degenerative substance of the leiomyosarcoma, or to host resistance to the tumor itself.