Internal carotid artery aneurysm and Marfan's syndrome.

Aneurysms of the extracranial carotid artery are most commonly caused by atherosclerosis or trauma but may also have unusual causes, such as Marfan's syndrome. Although aneurysmal changes in the extracranial carotid vessels usually are due to extension of aortic dissection into the carotid system, isolated aneurysms may occasionally complicate Marfan's syndrome. The authors report a case of Marfan's syndrome in which the patient, a 45-year-old woman, presented with an asymptomatic mass in the right side of the neck at the level of the carotid bifurcation. An isolated internal carotid artery aneurysm was identified. The aneurysm was resected using an interposition vein graft over an outlying shunt. Histologic examination confirmed the typical cystic medial necrosis with loss of elastic fibres and an increase of mucoid material in the media. The patient's recovery was smooth and at 2-year follow-up there were no signs of recurrent aneurysm formation.