P2594 - Multiple Mucosal Schwann Cell Hamartomas Found on Screening Colonoscopy

Leen Raddaoui, MD¹, Zeina Bani Hani, MBBS², Robert S.. Gordon, DO, MS³, Jana A. Malhas, MD⁴, Achint K. Singh, DO⁵, Sydney Struck, PA, MPH², Marie L. Borum, MD, EdD, MPH, FACG⁶
1George Washington University Hospital, Washington, DC; 2George Washington University, Washington, DC; 3George Washington University School of Medicine and Health Sciences, Arlington, WA; 4School of Medicine, The University of Jordan, Amman, 'Amman, Jordan; 5George Washington University Hospital, Arlington, VA; 6Division of Gastroenterology and Liver Disease, Department of Medicine, George Washington University School of Medicine and Health Sciences, Washington, DC

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 100 cases of MSCH in the literature, with
fewer than 5 reporting multiple colonic MSCHs. We reports 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. (Figure 1) All of the polyps were Schwann cell hamartomas confirmed by p</span>ositive 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. 


Figure: Multiple sigmoid polyps

Disclosures:
Leen Raddaoui indicated no relevant financial relationships.
Zeina Bani Hani indicated no relevant financial relationships.
Robert Gordon indicated no relevant financial relationships.
Jana Malhas indicated no relevant financial relationships.
Achint Singh indicated no relevant financial relationships.
Sydney Struck indicated no relevant financial relationships.
Marie Borum indicated no relevant financial relationships.

Leen Raddaoui, MD¹, Zeina Bani Hani, MBBS², Robert S.. Gordon, DO, MS³, Jana A. Malhas, MD⁴, Achint K. Singh, DO⁵, Sydney Struck, PA, MPH², Marie L. Borum, MD, EdD, MPH, FACG⁶. P2594 - Multiple Mucosal Schwann Cell Hamartomas Found on Screening Colonoscopy, ACG 2025 Annual Scientific Meeting Abstracts. Phoenix, AZ: American College of Gastroenterology.