Idiopathic myointimal hyperplasia of mesenteric veins: Rare case of ischemic colitis mimicking inflammatory bowel disease.

Idiopathic myointimal hyperplasia of mesenteric veins (IMHMV) is a rare and poorly understood ischemic colitis that occurs in the rectosigmoid colon of predominantly young, previously healthy, male patients. A 76-year-old Japanese man presented to our hospital with a 1-year history of worsening diarrhea, lower abdominal pain, and weight loss (-6 kg). Laboratory evaluation revealed white blood cell count of 13,200/μL, C-reactive protein level of 2.0 mg/dL (normal range, 0.0-0.3), and negative results for stool culture (including Clostridium difficile). Colonoscopy showed circumferential and edematous narrowing of the sigmoid colon with deep longitude ulceration. Biopsy was done and examination of the specimen demonstrated no specific ischemia. The patient was treated with bowel rest, antibiotics, and i.v. fluids; however, his symptoms worsened. Finally, sigmoidectomy was carried out. Histological examination demonstrated significant myointimal hyperplasia of mesenteric veins leading to thickening and stenosis of the venous lumen. Therefore, the final diagnosis was IMHMV. Three months following sigmoidectomy, he was asymptomatic.