Giant circumflex coronary artery aneurysm associated with cystic medial necrosis in a non-Marfan patient.

Giant coronary artery aneurysm is rare, and its cause and natural history has not been clearly delineated. We present a patient without Marfan syndrome who had a giant coronary artery aneurysm of the circumflex coronary artery. After the surgical resection, the underlying pathology of the aneurysm was thought to be associated with cystic medial necrosis of arterial wall because of its progressive enlargement.