Cystic medial necrosis responsible for aortic dilatation and rupture is seen in

In Marfan syndrome, a connective tissue disorder of autosomal dominant inheritance, the basic biochemical abnormality is a mutation affecting fibrillin. Most serious, however, is the involvement of the cardiovascular system. Fragmentation of the elastic fibers in the tunica media of the aorta predisposes affected patients to aneurysmal dilation and aortic dissection. These changes, called cystic medionecrosis, are not specific for the Marfan syndrome. Similar lesions occur in hypertension and with ageing. Loss of medial support causes dilation of the aortic valve ring, giving rise to aortic incompetence.