A Woman with Abdominal Pain and Aortic Dilatation

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Posted by Carla Rothaus

What is the typical morphology of a mycotic aneurysm?

The management of infectious aortitis, particularly cases associated with abscess and thrombus, includes prompt surgical intervention, débridement of infected tissue, and avoidance of glucocorticoids and other immunosuppressive agents. Read the NEJM Case Records of the Massachusetts General Hospital here.

Clinical Pearls

Q: Are mycotic aneurysms a common cause of aortic aneurysms?

A: Mycotic aneurysms, which are most frequently caused by degeneration of the aortic wall by staphylococcus or salmonella, account for less than 1% of aortic aneurysms. They typically occur in men older than 50 years of age who have coexisting conditions, such as atherosclerosis, diabetes, congenital vascular abnormalities, or a history of trauma to the aorta.

Q: What is the typical morphology of a mycotic aneurysm?

A: The mechanistic basis for mycotic aneurysms is thought to be infiltration of neutrophils and subsequent activation of lytic enzymes, which results in the distinctive saccular appearance of the aneurysm noted nearly universally in patients with this condition.


Morning Report Questions

Q: What is the usual pathogenesis of a mycotic aneurysm?

A: Mycotic aneurysms are infrequently caused by primary infection of the aorta. Infection of the aorta typically requires both inoculation by an offending pathogen and the presence of an underlying vascular abnormality or graft material. This is probably the reason that infectious aortitis is a rare diagnosis in persons younger than 50 years of age. Septic emboli involving peripheral vessels are not uncommon, occurring in approximately 10% of patients with endocarditis; however, aortitis is an extremely rare complication of this condition. 

Q: What are some of the features of Takayasu’s arteritis?

A: Takayasu’s arteritis affects the ascending and descending aorta and can cause rapid dilation radially. The most frequently reported symptoms are low-grade fever and malaise. Takayasu’s arteritis can occur in both men and women but typically occurs in women younger than 40 years of age. Although the prevalence is highest among Asian women, Takayasu’s arteritis is known to occur in White women, as well. The American College of Rheumatology classification system for Takayasu’s arteritis consists of the following six criteria: onset at younger than 40 years of age, claudication of an arm or leg, a decreased pulse in the brachial artery, a difference in the systolic blood pressure between the two arms of more than 10 mm Hg, a bruit over the subclavian arteries or the aorta, and arteriographic evidence of narrowing or occlusion of the entire aorta, its primary branches, or large arteries in the proximal arms or legs. The presence of three or more of these six criteria is associated with a sensitivity of 90.5% and a specificity of 97.8%.

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