Colonic perineurioma of the transverse colon: presentation of a rare neoplasm in an atypical location.

A 51-year-old male with previous medical history of dyslipidemia performed screening colonoscopy, which revealed a sessile polypoid lesion with a diameter of approximately 8 mm located at the proximal transverse colon, which was resected en bloc with a cold snare. Remarkably, histopathological examination revealed a proliferation of spindle cells in the lamina propria entrapping colonic crypts without evidence of nuclear pleomorphism, mitotic figures or necrosis. On immunohistochemistry, spindle cells were diffusely positive for glucose transporter-1 and negative for S100, DOG1, CD34 and smooth muscle actin. These features were consistent with a diagnosis of colonic perineurioma.