Cystic medial necrosis (CMN) is a disease of large arteries, especially the aorta, caused by collagen linking defects leading to deposition of basophilic ground substance in the media, creating cyst-like lesions that weaken the artery wall. CMN is a known cause of aortic dissection, aortic aneurysm, and aortic rupture and is associated with connective tissue diseases such as Marfan syndrome, Ehlers-Danlos syndrome, and Turner syndrome. CMN is also related to hypertension. The incidence of CMN increases with age, and it is thought to be the cause of 1%-6% of thoracic aortic aneurysms. This condition does not typically affect children, although it can affect young as well as older adults.

Aortic aneurysms are typically asymptomatic and often found on CT scans as an incidental finding. Complications like aortic dissection or rupture present with acute onset of severe chest, back, or abdominal pain. A pulsatile mass can be felt in abdominal aortic aneurysms. The aneurysm can compress adjacent structures if rapidly expanding, leading to hoarseness, dysphagia, or wheezing. Hemodynamic instability with hypotension occurs in aortic rupture. Mortality is very high in a ruptured aortic aneurysm.