Supplementary Material for: An asymptomatic patient with colonic leiomyoma

Subepithelial lesions (SELs) originating from muscularis mucosae of the colon are very rare findings on endoscopy. Appropriate management of SELs involves making a correct diagnosis and estimating their malignant potential. In this case study a 58-year-old Saudi man presented with a small, 8-mm sigmoid polyp during screening colonoscopy. The polyp was removed by hot snare polypectomy and sent to pathology lab. Report showed an unremarkable colonic mucosa and underlying well-circumscribed submucosal lesion composed of monotonous spindle cells. Immunohistochemical (IHC) analysis ruled out CD117- / DOG1-positive GIST tumor and confirmed the lesion as leiomyomatous polyp. Colonic leiomyomas are usually benign and often asymptomatic, and discovered during CRC screening procedures. Diagnosis is made on histology / IHC since endoscopically they might be indistinguishable from other SELs. Conventional polypectomy is an appropriate treatment for small colonic leiomyoma and these benign lesions typically do not recur.