Solitary schwannoma of the colon: Report of two cases

Some patients with gastrointestinal schwannoma (GIS) have been previously r eported in the literature. However, GIS of the colon is quite rare. In addi tion, it is sometimes difficult to differentiate neurogenic tumors from oth er soft tissue tumors. We herein describe two cases of schwannoma of the co lon, while also reviewing the relevant Japanese literature. The first case, a 73-year-old woman underwent a sigmoidectomy with lymph node dissection f ollowing the diagnosis of submucosal tumor. In the second case, a submucosa l tumor was located in the cecum of a 44-year-old man. An endoscopic tumor resection was performed in the second case. The resected tumors measured 3. 6 and 1.0 cm in maximal diameter, respectively. Microscopically, the tumors consisted predominantly of spindle-shaped cells that proliferated in an in terlaced fashion. Mitosis was rarely seen in these tumors. Immunohistochemi cally, the tumor cells were strongly positive for S-100 protein, weakly pos itive for glial fibrillary acidic protein, and negative for CD34, alpha -sm ooth-muscle actin, and cytokeratin (CAM 5.2) in both cases. The tumors in t he two cases were both diagnosed to be benign schwannoma of the colon. In g eneral, schwannoma of the gastrointestinal tract is considered to be benign and should therefore be distinguished from other spindle-cell tumors or ma lignancies. Once diagnosed as schwannoma, extensive surgery should be avoid ed. Actually, such patients tend to show a good postoperative course with n o evidence of recurrence.