Isolated primary schwannoma arising on the colon: report of two cases and review of the literature.

Primary schwannoma of the large intestine is an extremely rare neoplasm. Here, we report two cases of colonic schwannoma confirmed pathologically after laparoscopic resection. A 52-year-old female and a 59-year-old female were referred by their general practitioners to our coloproctologic clinic for further evaluation and management of colonic submucosal masses. Colonoscopies performed in our institution revealed round submucosal tumors with a smooth and intact mucosa in the mid-ascending and descending colon, respectively. Computed tomography (CT) scans showed an enhancing soft tissue mass measuring 2 × 2 cm in the right colon and well-defined soft tissue nodule measuring 1.5 × 1.7 cm in the proximal descending colon, respectively. We performed laparoscopic right hemicolectomy and segmental left colectomy under the preoperative impression of gastrointestinal stromal tumors. Two cases were both diagnosed to be benign schwannoma of the colon after immunohistochemical stains (S-100 (+), smooth muscle actin (-), CD117 (-), and CD34 (-)).