Metachronous leiomyosarcoma in colostomy after abdominoperineal resection for rectal carcinoma.

Leiomyosarcoma of the colon is a rare neoplasm. It is widely known that primary malignant lesions may present either simultaneously (synchronous tumor) or at different times (metachronous tumor). The incidence of metachronous colonic mucosal carcinoma is generally considered to range from 3 to 5%. Metachronous leiomyosarcoma in colostomy 4 years after abdominoperineal resection for rectal carcinoma is unusual and we have found no reports on this in the literature. The clinical symptoms, diagnostic features, and mode of treatment are discussed.