The authors report a case of a 49-year-old male patient with leiomyosarcoma of the ascending colon. The patient presented with anemia and an abdominal mass, and the symptoms progressed until a final diagnosis was made nine months later. A plain abdominal x-ray showed the presence of gas outside the bowel, in the right hypochondrium. The double contrast barium enema showed a sublevel displacement of the hepatic flexure and diverticula. An abdominal ultrasound revealed a heterogeneous expansive lesion below the liver containing gas, and a computed tomography of the abdomen revealed an excavated mass below the liver containing liquid, that was not filled in by contrast medium. The patient was submitted to a right hemicolectomy with ileocoloanastomosis and the histopathological analysis of the excised material revealed a leiomyosarcoma of the ascending colon.

Keywords: Leiomyosarcoma, Large bowel, Computed tomography