Segmental colitis caused by idiopathic myointimal hyperplasia of mesenteric veins.

Diseases causing colonic ischemia may be mistaken with other causes of segmental colitis such as inflammatory bowel disease, especially in young patients. The authors present the case of a 47-year-old male with severe proctosigmoiditis. Assessment excluded infectious causes, thrombophilia and systemic vasculitis. The initial histological specimen was suggestive of inflammatory bowel disease and therapy was initiated with intravenous steroids and, at day 5, infliximab, with no response. The patient was proposed for surgery. Pathological examination of the surgical specimen revealed an idiopathic myointimal hyperplasia of mesenteric veins, a rare entity exhibiting necrotizing phlebitis with rapid progression to segmental necrosis in the rectosigmoid colon. In this paper the authors discuss the differential diagnosis of proctosigmoiditis in young ages and the approach to this exceptionally rare ischemic entity.