Rectal Mucosal Schwann-Cell Hamartoma: A CaseReport and Literature Review

Background: Mucosal Schwann cell hamartoma is a newly recognized disease entity that describes lesions which share some features but are distinct from schwannomas and neurofibromas. This mesenchymal lesion, consisting of a proliferation of Schwann cells in the lamina propria and a strong positivity for the S-100 protein, should be differentiated from other similar lesions because it exists solely in the intestines as a polypoid lesion. Here, we report on a case of Schwann cell hamartoma diagnosed on pathology of rectal polyp removed during colonoscopy Case presentation: Our patient is a 60 y/o male who presented for an outpatient colonoscopy to evaluate weight loss and intermittent hematochezia. Colonoscopy revealed sigmoid diverticulosis and a small 5 mm rectal polyp. The polyp was sessile and removed with a cold biopsy forceps. On pathology, the rectal polyp showed S-100 positivity and had benign bland spindle cell proliferation in the lamina propria, findings that were consistent with a diagnosis of Mucosal Schwann cell hamartoma. A follow up colonoscopy was recommended in 3 years. Conclusion: Mucosal Schwann cell hamartoma is considered a benign lesion and no reports of malignant transformation have been described. However, further follow up data is needed before making final recommendations. Our case report emphasizes this emerging disease and we propose close follow ups for possible malignant transformation. Key-words: Schwann Cell; Neuroma; Polyp; Hamartoma; Neurofibroma