Schwannoma of the Colon, a Rare Tumor Entity: A Case Report

Abstract

Schwannoma is a usually benign tumor derived from Schwann cells. It can be found throughout the body, particularly in the head, neck, and extremities.. However, colonic schwannoma is extremely rare. Since most colonic schwannomas are asymptomatic, it can be incidentally found during colonoscopy or imaging studies performed for other reasons. A preoperative diagnosis of schwannoma may be made with imaging studies, such as computed tomography (CT) and magnetic resonance imaging (MRI), but a preoperative diagnosis is very difficult, and most of the cases are diagnosed after pathologic examination. Immunohistochemical staining is the basis of a definite diagnosis, and it can differentiate schwannoma from other mesenchymal tumors. Here, we present a case of a schwannoma of the cecum, which was preoperatively misdiagnosed as a gastrointestinal stromal tumor (GIST). A 65-year-old woman was referred for the treatment of a submucosal mass in the cecum. Colonoscopy revealed a 2 cm round submucosal mass in the cecum and abdominopelvic CT showed an enhancing mass in the cecum without lymphadenopathy. With the presumed diagnosis of GIST, laparoscopic right hemicolectomy was performed. Pathologic reports showed that it was consistent with schwannoma, immunohistochemically positive for S100 protein and negative for CD117 (c-kit), CD34, and smooth muscle actin. This case represents an unusual case of a schwannoma in the cecum, which could not be preoperatively diagnosed. Although its preoperative diagnosis is difficult given its rarity, a schwannoma can be considered as one of the differential diagnoses of a submucosal colon mass.