D0459 - Endoscopic Mucosal Resection Ligation for Rectal Schwannoma: A Case Report

Rahul Karna, MD¹, Tabeer Rana, DO², Thayer Nasereddin, MD¹, Lisa K. Andersen, MD¹, Adam J. Kichler, DO, MEd^1
1Allegheny Health Network, Pittsburgh, PA; ²Allegheny General Hospital, Pittsburgh, PA

Introduction: Gastrointestinal (GI) schwannomas are a type of gastrointestinal autonomic nerve tumor related to the myenteric plexus. They are 2-6% of all mesenchymal tumors and 0.1% of all benign GI tumors. Treatment of rectal schwannomas is complete excision with negative microscopic surgical margins. Here, we describe a case of rectal schwannoma, initially suspicious for carcinoid tumor on endoscopic ultrasound, finally retrieved via ligation endoscopic mucosal resection.

Case Description/Methods: A 55-year-old male without any significant past medical history was referred for management of rectal sub-epithelial lesion on outpatient screening colonoscopy. On evaluation, a subepithelial nodule was found 10 cm proximal to the anus. Endoscopic ultrasound (EUS) using forward viewing scope showed a well circumscribed hypoechoic 8 mm x 6 mm round intramural lesion, with well-defined borders arising within the deep mucosa of the rectum suspicious for carcinoid tumor . No additional wall layers were involved. Subsequently, a ligation endoscopic mucosal resection (EMR-L) of the lesion was performed. Biopsy showed homogenous tumor cells containing eosinophilic cytoplasm arranged in a microcystic/reticular pattern and lacking the Antony A/Antony B areas and Verocay bodies, thus suggestive of non-microcystic/reticular Schwannomas. The resection margins were negative. The neoplastic cells were strongly and diffusely positive for SOX-10 and S-100. Biopsy specimen stained negative for AE1/AE3, DOG-1, CD34, CD117, SMA, BER-EP4, desmin, HMB45 and MelanA. Patient was diagnosed with benign microcystic/reticular Schwannoma based on immunohistochemical profile. Image shows endoscopic appearance of rectal subepithelial lesion pre-EMR (Figure A), EMR-ligation (Figure B) and post-procedure image of site of lesion (Figure C).

Discussion: The incidence of rectal neuroendocrine tumors is increasing likely due to aggressive screening, improved treatment modalities and surveillance techniques, approaches which have also increased overall life expectancy. Our patient presented with an incidental finding of rectal subepithelial mass on screening colonoscopy. Here, we describe a novel approach to management of rectal mass via EMR-L using a forward viewing EUS scope, which can be utilized for safe and effective resection of these lesions.



Disclosures:


Rahul Karna, MD¹, Tabeer Rana, DO², Thayer Nasereddin, MD¹, Lisa K. Andersen, MD¹, Adam J. Kichler, DO, MEd¹. D0459 - Endoscopic Mucosal Resection Ligation for Rectal Schwannoma: A Case Report, ACG 2022 Annual Scientific Meeting Abstracts. Charlotte, NC: American College of Gastroenterology.