D0110 - A Rare Case of Appendiceal Schwann Cell Hamartoma

Raj Shah, MD¹, Stuti Patel, MD², Jonathan Vasquez, MD³, Amar Mandalia, MD^3
1University of Central Florida HCA Healthcare GME, Kissimmee, FL; ²Trumbull Regional Medical Center, Warren, OH; ³Orlando VA Medical Center, Orlando, FL

Introduction: Mucosal Schwann cell hamartoma (MSCH) is a rare, benign, neurogenic tumor characterized by a disorganized proliferation of S100-positive Schwann cells in the lamina propria, predominantly in the rectosigmoid colon. Most often, it is an incidental finding in a routine colonoscopy. Here we present an infrequently encountered case of appendiceal orifice MSCH.

Case Description/Methods: A 53-year-old male with a past medical history of hypertension, obstructive sleep apnea, obesity, depression, and knee osteoarthritis presented for surveillance colonoscopy. Three years ago, the patient had two sessile polyps removed, and interval colonoscopy at three years was recommended due to poor preparation. Repeat colonoscopy showed a solitary 4 mm polyp at the appendiceal orifice (Fig. 1). Biopsy of the polyp showed spindle cell proliferation of Schwann cell phenotype located in the lamina propria without nuclear atypia, pleomorphism, or mitoses (Fig. 2). Immunohistochemical stains were positive for S100 (Fig. 3) and negative for Desmin, SMM-HC, CD117, and CD34 (Fig. 4a,b and c).

Discussion: Benign nerve cell tumors are commonly described in the skin and soft tissue, and involvement of the gastrointestinal tract has been increasingly identified in the last decade. It is a rare disease of the colonic mucosa, often diagnosed during screening colonoscopy. They have been described as polyps less than one cm, predominantly discovered in descending colon and middle-aged females. Very few cases of appendiceal MSCH and gallbladder MSCH have been reported. Gibson and Hornick coined the term MSCH in 2009 to distinguish it from true “neuromas” and “neurofibromas.” It is essential to accurately diagnose and distinguish it from other neuronal polyps - GIST, colorectal neurofibroma, mucosal neuromas, GI ganglioneuromas, mucosal perineurioma, inflammatory fibroid polyps, as some of these are associated with familial syndromes with worse outcomes and different management than MSCH. More studies are required to evaluate recurrences and long-term prognosis for MSCH. No association between MSCH and inherited syndromes or malignancies has been established. However, it should be considered an important differential diagnosis of incidental GI polyps and encourage clinicians to test for specific markers to rule out other causes and prevent aggressive or unnecessary treatments, thus reducing the burden on the health care resources.



Disclosures:


Raj Shah, MD¹, Stuti Patel, MD², Jonathan Vasquez, MD³, Amar Mandalia, MD³. D0110 - A Rare Case of Appendiceal Schwann Cell Hamartoma, ACG 2022 Annual Scientific Meeting Abstracts. Charlotte, NC: American College of Gastroenterology.