S3941 Multiple Mucosal Schwann Cell Hamartomas Found on Screening Colonoscopy

Introduction: Mucosal Schwann cell harmartomas (MSCHs) are rare neurogenic lesions of the gastrointestinal tract. These lesions are typically identified in the distal colon with most found during screening colonoscopy. Although classified as benign mesenchymal neoplasms, MSCHs can mimic malignant or premalignant lesions, such as gastrointestinal stromal tumors or adenomatous polyps, making their identification critical. There are less than 100 cases of MSCH in the literature, with fewer than 5 reporting multiple colonic MSCHs. We report a rare case of an individual with multiple MSCHs, emphasizing the importance of recognizing the variations in presentation of this unusual lesion. Case Description/Methods: A 46-year-old man with hypertension underwent a screening colonoscopy. He had no gastrointestinal symptoms. His family history was significant bladder cancer (paternal grandmother), prostate cancer (father) and colon polyps of uncertain histology (maternal grandmother). His exam was unremarkable. His colonoscopy revealed 4 sessile ascending colon polyps (3-5 mm), 4 sessile descending colon polyps (3-mm), 7 sessile sigmoid colon polyps (3-5 mm) which were removed. All of the polyps were Schwann cell hamartomas confirmed by positive spindle cell immunoperoxidase staining for S100. Discussion: This case highlights the importance of recognizing that multiple mucosa Schwann cell hamartomas can occur. MSCHs rare lesions which are typically asymptomatic and have not been found to be associated with inherited syndromes or malignancies. Endoscopic ultrasound can assist in confirming the diagnosis by demonstrating that the lesions are limited to the lamina propria of the gastrointestinal tract, differentiating it from lesions arising from the submucosa. MSCHs are considered benign. It is critical to distinguish these lesions from clinically significant gastrointestinal lesions to avoid unnecessary surgical intervention. However, emerging data and additional research is needed to determine potential clinical implications and development of guidelines for long-term management.