First Report of Mucosal Schwann Cell Harmatoma in The Caecum

Abstract

Background: Mucosal Schwann cell hamartomas of the colon are rare, and the available literature is scarce. Most reported cases are in the left colon, often presenting as small and solitary sessile polyps discovered during screening colonoscopy. We report the first case of a mucosal Schwann cell hamartoma in the caecum.

Case Report: A 71-year-old man with a background of diabetes mellitus, hypertension and hyperlipidaemia underwent colonoscopy for polyp surveillance due to a history of multiple tubular adenomas.  He also had a history of dyspepsia but was otherwise well. Colonoscopy revealed a 2mm NICE I caecal polyp adjacent to the appendiceal orifice within a small diverticulum. Attempts to lift the polyp out of the diverticulum with subcutaneous injection was unsuccessful, and it was removed with jumbo forceps biopsy. The rest of the colon was normal.

Results: Histopathology of the caecal polyp showed colonic mucosa with tubular crypts with superficial hyperplastic changes. The lamina propria was expanded and filled with a poorly circumscribed proliferation of bland spindle cells without forming specific patterns. The spindle cells were strongly positive for S100 staining with patchy axonal NF staining, and negative for CD117, DOG1, SMA, Desmin, HMB45, Melan A and EMA. Ki67 proliferation index was 1%, and there was no dysplasia or malignancy seen. These findings were consistent with a mucosal Schwann cell hamartoma.

 

C

B

C

Caecal Polyp

A.    H&E-stained section demonstrates a poorly circumscribed proliferation of bland spindle cells within the lamina propria, lacking specific architectural patterns.

B.     Immunohistochemical (IHC) staining for S100 shows strong positivity in the spindle cells

C.     IHC staining for neurofilament (NF) reveals patchy axonal positivity within the spindle cell population.

Conclusion: Mucosal Schwann cell hamartomas are rare lesions and can be seldom found in the caecum and right colon. They are considered benign and do not require routine surveillance after resection.

Bangladesh J Medicine 2026; Vol. 37, No. 2(1) Supplementation: 238