RADIOLOGY: HEPATOBILIARY: Case# 32798: CONGENITAL HEPATIC AVM. 35 year old male with vague right upper quadrant abdominal pain. There is significant dilatation of the celiac and hepatic arteries. The hepatic artery leads to a large enhancing mass in the left hepatic lobe. The main, left, and right portal veins are dilated as well. Arteriovenous malformations (AVMs) can occur anywhere in the body. An AVM is an abnormal communication betwen the arterial and venous systems without a normal intervening capillary network. The result is increased blood supply through the AVM with enlarged arteries and dilated draining veins.