In the latest Case Record of the Massachusetts General Hospital, a 60-year-old man with abdominal pain had abdominal and thoracic aortic aneurysms suggestive of mycotic aneurysms. The abdominal aneurysm was resected. Cultures were negative; fever persisted. Six weeks later, chest pain developed and the thoracic aneurysm had enlarged.
Osler first used the term “mycotic aneurysm” in 1885 to describe aortic infection resulting from septic emboli caused by endocarditis. In contemporary practice, the terms “infected” and “mycotic” are used interchangeably, and they refer to any primary or secondary aortic infection.
• What are the most common organisms involved in mycotic aneurysms?
A variety of bacterial, treponemal, and fungal pathogens can cause infected aneurysms — most commonly staphylococcus, salmonella, and streptococcus species — but blood cultures of up to 25% of infected aneurysms are negative.
• What is the typical clinical presentation of a mycotic abdominal aortic aneurysm?
The clinical presentation often includes abdominal or back pain, fevers, chills, leukocytosis, elevated acute-phase reactants, and rupture of the aneurysm. The diagnosis is suggested by a saccular as opposed to fusiform shape of the aneurysm, rim enhancement, irregular wall thickening, disruption of mural calcium, periaortic fluid or gas, and rapid expansion on serial imaging.
Morning Report Questions
Q: What are the features of giant-cell arteritis associated aortitis?
A: The systemic immune-mediated conditions that lead to aortic aneurysms can be divided into granulomatous and nongranulomatous disorders. The granulomatous conditions are giant-cell arteritis, Takayasu’s arteritis, rheumatoid arthritis, and sarcoidosis. Patients with giant-cell arteritis have a risk of thoracic aortic aneurysm that is 17 times as high as age- and sex-matched controls and a risk of abdominal aortic aneurysm that is twice as high as that of controls. Giant-cell arteritis is unusual in patients of African and Afro-Caribbean ancestry. Most patients with giant-cell arteritis and aortitis also have diminished peripheral pulses, as well as bruits in the subclavian, carotid, or femoral arteries.
Q: What are inflammatory abdominal aortic aneurysms and IgG4-related aortitis?
A: The classic patient with an inflammatory abdominal aortic aneurysm is a middle-aged to elderly man with a history of smoking and the clinical triad of abdominal or back pain, an elevated erythrocyte sedimentation rate, and weight loss. Perianeurysmal and retroperitoneal fibrosis is frequently present. The duodenum, inferior vena cava, left renal vein, and ureters often adhere to the aneurysmal wall. In the past several years, a link has been established between IgG4-related disease and aneurysms in the abdominal and thoracic aortas. In patients with IgG4-related disease, other tissues and organs may be involved, including the salivary and lacrimal glands, the pancreas, retroperitoneal fibrosis, or a combination of these. It is likely that a clinically significant percentage of patients with diagnoses of isolated aortitis and inflammatory abdominal aortic aneurysm actually have IgG4-related disease. Serum IgG4 levels can be helpful in pointing to a diagnosis of IgG4-related disease, but both the sensitivity and specificity of serum IgG4 levels are suboptimal.