S4195 Granular Cell Tumors of the Gastrointestinal Tract: A Case Series of 3 Subepithelial Lesions Diagnosed and Treated via Advanced Endoscopic Techniques

Introduction: Granular cell tumors (GCTs) are rare, typically benign neoplasms of Schwann cell origin. While they most commonly occur in the skin and oral cavity, gastrointestinal (GI) involvement accounts for fewer than 10% of cases. Their subepithelial location can lead to diagnostic delays, as they may mimic other lesions such as neuroendocrine tumors or gastrointestinal stromal tumors. We present a case series of 3 patients with GI GCTs involving the periappendiceal region, cecum, and esophagus. Case Description/Methods: Case 1: A 41-year-old man presented with a five-year history of chronic diarrhea. Colonoscopy revealed a submucosal nodule near the appendiceal orifice. Initial mucosal biopsies were nondiagnostic. A repeat colonoscopy with endoscopic full-thickness resection (EFTR) was performed. Histopathology confirmed a granular cell tumor with negative margins. Immunohistochemical staining was positive for S100, neuron-specific enolase, and inhibin, consistent with Schwann cell origin. Case 2: A 36-year-old woman presented with generalized abdominal pain, chronic constipation, and reflux-like symptoms. Imaging and colonoscopy revealed a firm, 1 cm submucosal lesion in the cecum. Initial biopsies were nondiagnostic. Given concern for a neuroendocrine tumor, EFTR was performed. Histopathology confirmed a granular cell tumor with S100 positivity and negative margins. The patient experienced resolution of her symptoms and no recurrence on follow-up. Case 3: A 30-year-old man with persistent nausea and diarrhea underwent upper endoscopy, which revealed a submucosal nodule in the distal esophagus. Initial biopsies were inconclusive. Endoscopic ultrasound followed by mucosal resection was performed. Pathologic examination confirmed a 0.5 cm granular cell tumor with S100 positivity and negative margins. Discussion: GCTs of the GI tract are rare and often discovered incidentally. Their subepithelial location frequently renders superficial biopsies non-diagnostic, necessitating advanced endoscopic techniques such as EFTR or endoscopic ultrasound-guided resection for definitive diagnosis and management. Immunohistochemical staining—particularly for S100—is critical in confirming Schwann cell origin. Complete endoscopic resection with negative margins is typically curative. In this series, all 3 cases were successfully diagnosed and managed using advanced endoscopic approaches, with histopathologic confirmation of GCTs.