LEIOMYOSARCOMA OF THE COLON

Gastrointestinal stromal tumors are the most common mesenchymal tumors of the digestive tract. Leiomyosarcomas of the gastrointestinal tract are rare mesenchymal neoplasms which grossly and histologically resemble gastrointestinal stromal tumors. They may be differentiated from gastrointestinal stromal tumors by using immunohistochemistry and they are typically positive for a smooth muscle actin and desmin and negative for c-kit, CD34 and DOG1.1. They often express calponin and h-caldesmon. We present a case of a 59-year-old male with anemia, weight loss, intermittent abdominal pain and right abdominal mass. Colonoscopy revealed an exophytic ulcerated neoplastic mass in the ascending colon and abdominal computed tomography scan showed an ill-defined heterogeneous tumor mass which surrounded almost the whole ascending colon. The patient underwent right hemicolectomy and partial resection of ileum. Histopathological examination revealed a leiomyosarcoma composed of atypical spindle cells positive for a smooth muscle actin, desmin and vimentin, and negative for c-kit, CD34, S100 and neuron specific enolase. The patient is alive 8 months after the operation, undergoing chemotherapy. We have concluded that the multimodal approach comprising chemotherapy and complete surgical resection controls the leiomyosarcomas.