Adventitial cystic disease of the popliteal artery.

Adventitial cystic disease (ACD) is a vascular disorder most commonly affecting the popliteal artery. ACD is an uncommon and often misdiagnosed cause of lower extremity intermittent claudication that is usually acute in onset and of longer duration than claudication associated with atherosclerosis. We present two cases of ACD affecting the popliteal artery.