Colonic polypoid arteriovenous malformation - An unexpected cause of hematochezia

A 70-year-old male was admitted with severe haematochezia and lipothymia. His medical history was relevant for coronary artery disease and radiation proctopathy. During hospitalization, was hemodynamically stable with persistent haematochezia. Laboratory examination revealed continuous haemoglobin fall, despite erythrocyte reposition, with administration of 11 units since admission. Colonoscopy showed an 8mm fibrinous lesion with an adherent clot, at 40 cm from the anal verge. During exploration, a heavy spurting haemorrhage developed, with haemostasis being achieved with 4 clips, followed by site tattoo. Considering the risk of severe bleeding relapse in a high-risk patient, the patient underwent emergent Hartmann type colectomy. Histopathology report revealed a vascular lesion with arterial and venous vessels, protruding through the submucosa, muscular and subserosa, with a focal mucosal erosion, without neoplastic disease, compatible with an arteriovenous malformation (AVM).