Mucosal Schwann Cell Hamartoma in sigmoid colon – A rare case report and review of literature

Abstract

Mucosal Schwann Cell Hamartoma (MSCH) of the gastrointestinal (GI) tract is an incidental finding by screening colonoscopy, rarely reported in the English literature since first described in 2009. We diagnosed a case of sigmoid colon MSCH in a 60-year-old female without a family history or medical history of Neurofibromatosis Type 1 (NF1, von Recklinghausen’s disease), neuronal lesion, MEN2, or other syndromes. The endoscopic exam revealed a 4 mm sessile polyp with no erosion or ulceration. Histologically, the lesion was composed of uniform bland spindle cells with entrapped normal colonic crypts. The lesional cells showed strongly diffuse positivity for S-100, negative for smooth muscle actin (SMA), c-Kit (CD117), CD34, epithelial membrane antigen (EMA), and CD68. In this article, we summarized the epidemiology, clinical and colonoscopic findings, histological features and immunohistochemistry (IHC) patterns of this specific entity and its mimics. Keywords: Mucosal Schwann Cell Hamartoma (MSCH), Colorectal polyp, S-100, Differential diagnosis