A 30 mm mucosal Schwann cell amartoma of the right colon mimicking a G-Type LST

A 55-year-old male underwent a screening colonoscopy for first grade family history of colorectal cancer.He was found to have at splenic flexure a 30 mm laterally spreading tumour(LST) with micronodular appearence like a granular-type LST,translucent surface and regular submucosal vascularization. Suspecting an adenoma without signs of deep invasion, a piecemeal hot-snare mucosectomy was started. However,only some fragments of the lesion were resected and sent for hystological examination,due to scarce lifting of the lesion after submucosal injection.After colonoscopy the patient complained severe abdominal pain and distention:a CT scan revealed a colonic microperforation, that was managed conservatively. The hystological diagnosis was mucosal Schwann cell amartoma(MSCH). Owing to its benign nature, a complete endoscopic removal was not indicated and only a 1-y follow-up colonscopy was programmed.MSCH of the colon are rare findings first described in 2009 [1], usually asymptomatic and detected incidentally.They can mimic mucosal polyps and are usually identified only after hystological examination. They are characterized by diffuse cellular proliferation of S-100+spindle cells in the lamina propria entrapping the colonic crypts [2]. MSCH were found also in other GI sites, and differ from other neural origin lesions found in patients with inherited syndromes (Cowden syndrome, NF-1, MEN-2B). Owing to their bening nature, they do not require surveillance, even if their clinical significance is still not established [3].To our knowledge,this is the largest colonic MSCH described in literature and it is the first time a known MSCH is left on-site,as both the complete removal could be hazardous and the surgical resection is not advisable.

Conflicts of Interest

Authors do not have any conflict of interest to disclose.

• References

• 1 Klair J.S., Girotra M., Agarwal A., Aduli F.. Mucosal Schwann cell hamartoma: just benign or more?. Int J Colorectal Dis 2014; 29 pp 1597-1598
• 2 Altaf F, Javed N, Ghazanfar H, Dev A.. Schwann Cell Hamartoma Presenting as a Colonic Polyp: A Rare Case Report With a Literature Review Cureus. 2024; 16 (4) e57674 doi:10.7759/cureus.57674. PMID: 38707060; PMCID: PMC11070221.
• 3 Gibson JA, Hornick JL.. Mucosal Schwann cell “hamartoma”: clinicopathologic study of 26 neural colorectal polyps distinct from neurofibromas and mucosal neuromas. The Am J Surg Pathol 2009; 33: 781-787

Publication History

Article published online:
27 March 2025