Diffuse leiomyosarcomatosis of the colon.

Smooth muscle cell tumors of the large bowel excluding the rectum are extremely rare. The case of a 30-year-old patient, who had ulcerative colitis for 5 years, is reported. Because of uncontrollable bleeding a proctocolectomy was performed. Along the whole colon the authors found more than 50 polypous tumors with a diameter up to 5 cm. Histologically all of these tumors were classified as leiomyosarcomas. The authors believe this to be the first reported case of multicentric leiomyosarcoma of the colon and of such a tumor associated with a history of ulcerative colitis.