2729 An Unusual Location of a Mucosal Schwann Cell Hamartoma

Abstract

INTRODUCTION: Nerve sheath tumors are rarely found in the gastrointestinal tract andhave been seen only in association with inherited syndromes such as neurofibromatosis type I (NF-1), multiple endocrine neoplasia type 2B (MEN 2B) and Cowden syndrome. Mucosal Schwann cell hamartoma (MSCH) is a new entity described by Gibson et al. in 2009 and has mostly been described in the colorectal area. CASE DESCRIPTION/METHODS: A 59-year-old man with no pertinent past medical history visited the gastroenterology clinic as a scheduled appointment for a long-standing history of GERD. He denied any nausea, vomiting, early satiety, abdominal pain or unintentional weight loss. His diagnosis was made on a clinical basis, and for this reason, an EGD was recommended. The EGD showed no abnormalities and esophageal mucosa was not erythematous (Figure 1). Multiple biopsies were taken. Pathology results showed mucosal Schwann cell hamartoma features in the antral biopsies (Figure 2). DISCUSSION: The exact incidence of MSCH is not known but it is mostly seen in female patients. MSCH has specific histological characteristics: lack of circumscription, absence of peripheral lymphoid cuff, crypt entrapment and strong positive stain for S-100. It is important to differentiate it from other spindle cell tumors since this will affect the management, prognostication and monitoring of possible associated complications. Differential diagnosis includes gastrointestinal stromal tumors (GISTs), carcinoid tumor, leiomyoma, schwannoma, mucosal neuroma, neurofibroma and ganglioneuroma. GISTs are the most common spindle cell tumors in the GI tract, however they have immunoreactivity to C-KIT and CD 117. GI schwannomas are mostly found in the stomach, but these have peripheral lymphoid cuffs and Antoni-A and Antoni –B regions. MSCH presents as a polypoid lesion in the colon and patients are typically asymptomatic. However, they can also present with rectal bleeding when the tumor is located in the colorectal area. This tumor follows a benign course and there is no need for treatment or extraction. Given its recent discovery and rarity, there is only one case report in the literature describing gastric affectation of the MSCH tumors. We describe this case due its unusual location as this is the 2nd case in the literature describing gastric affectation. Furthermore, a correct histological characterization is recommended since it will be crucial for the management and prognostication of these patients.