A case of leiomyosarcoma in the descending mesocolon

Abstract

A 39-year-old woman was admitted due to the presence of a left lower abdominal mass. Abdominal computed tomography (CT) and magnetic resonance imaging (MRI) showed a well-defined and irregular tumor with internal heterogeneity, which was 9×7cm in size. Barium enema examination revealed that the middle descending colon was displaced ventrally. A tumor of the retroperitoneum or the descending mesocolon was diagnosed, and a laparotomy was performed. Although the tumor adhered to the descending colon, the descending mesocolon, and the retroperitoneum, it was possible to decorticate it from the fascia of the retroperitoneum. Therefore, the tumor was diagnosed as arising the descending mesocolon. The tumor was resected along with a part of the descending colon. On pathology, dense fusiform cells with nuclear atypicality were noted ; on immunohistochemistry, α-SMA and vimentin were positive, but CD-34, c-kit, and S-100 were negative. Therefore, a leiomyosarcoma was diagnosed. The patient's course has been uneventful during 10 months of follow-up after surgery. This case is the first report of a mesenteric leiomyosarcoma arising in the descending mesocolon. Although mesenteric leiomyosarcomas have a poor prognosis, curative resections should performed if it in possible.