A CASE OF MESOSIGMOID LEIOMYOSARCOMA

Abstract

A 51-year-old woman was admitted to the hospital because of abdominal distension. She had a neonatal head-sized hard mass in her lower abdomen. Abdominal computed tomography (CT) and magnetic resonance imaging (MRI) revealed a tumor 18×12cm in diameter in her pelvis. We diagnosed the case as mesenteric or ovarian tumor and performed a laparotomy. We found a firm tumor with uneven surface in the mesosigmoid, which looked like to penetrate the mesosigmoid from its ventral to dorsal and had no continuity to the uterus and intestine. The tumor was resected with a part of the sigmoid colon. The resected tumor was a whitish solid tumor with central necrosis, and 18×12×10cm in dimension. Histologically the tumor was diagnosed as mesosigmoid leiomyosarcoma. On immunochemical stainings, the tumor gave positive response for smooth muscle actin and negative for S-100. Although mesenteric leiomyosarcomas are rare, we should consider them for the patients with an almost silent abdominal mass.