Question: what is the least common cause of abdominal aortic aneurysm?
Answer: Less frequent causes of AAA include Marfan syndrome, Ehlers-Danlos syndrome, and collagen-vascular diseases. In fewer than 5% of cases, AAA is caused by mycotic aneurysm of hematogenous origin. In these cases, local invasion of the intima and media gives rise to abscess formation and aneurysmal dilation of the vessel.