Background: The analysis of diarrhoea can be a diagnostic challenge. We present a patient with chronic diarrhoea, caused by idiopathic myointimal hyperplasia of the mesenteric veins (IMHMV). IMHMV is a rare condition characterized by thickening of the vessel wall due to proliferation of smooth muscle cells in mesenteric veins, eventually causing intestinal ischemia.
Case description: A 62-year-old man visited the gastroenterologist because of frequent watery diarrhoea. Initial endoscopic evaluation demonstrated venous congestion and erythema of the left-sided colon. Subsequently, he developed bloody diarrhoea, where endoscopy now revealed ischemic characteristics. CT scans and biopsies showed neither an occlusion of large arteries or veins nor histological features of inflammatory bowel disease. Eventually, the patient presented with an acute abdomen. Left hemicolectomy was performed, which resulted in the diagnosis of IMHMV.
Conclusion: Prolonged diarrhoea, with a remarkable biphasic clinical and endoscopic presentation, without evidence of inflammatory bowel disease or occlusion of large arteries and veins, may be caused by IMHMV.