A case of giant leiomyosarcoma of the rectum.

A 63 year-old-man was admitted to our hospital with the chief complaint of dyschezia. Digital examination revealed a large solid mass on the posterior wall of the rectum. Endoscopically, the tumor was covered by an intact mucosal layer. Under the diagnosis of rectal leiomyosarcoma, abdominoperineal resection of the rectum was performed. The tumor was 10 x 9 x 8 cm in size, and its cross section showed a gray-white tumor with central necrosis. Microscopically, the large tumor of the rectum was mainly located in the proper muscle layer and adventitia, and showed cellular proliferation of spindle-shaped and mild pleomorphic stromal cells, arranged in interlacing fashion, and focal necrosis. The histologic findings support the diagnosis of leiomyosarcoma. Leiomyosarcoma of the rectum is a relatively uncommon disease. We report our case with reference to the literature.