[A Case of Schwannoma in the Ascending Colon].

A 69-year-old man who was diagnosed with a submucosal tumor in the ascending colon by colonoscopy in X-7 year was presented. The endoscopic biopsy showed normal mucosa, and he had been followed up. During follow-up, computed tomography and colonoscopy performed in X year showed an enlargement of the tumor. Positron emission tomography-computed tomography showed intense FDG uptake. Malignant tumor was suspected, and laparoscopic-assisted right hemicolectomy was performed. The histopathological diagnosis showed spindle-shaped tumor cells proliferating in a fascicular manner. Immunohistochemical staining was positive for S-100 protein and negative for CD34, c-kit, and desmin, and schwannoma was diagnosed. Schwannomas are tumors derived from Schwann cells and therefore rarely develop in the gastrointestinal tract. Careful preoperative diagnosis is important because they do not normally metastasize or undergo malignant transformation.