A 51 y.o. woman with lupus comes in with abdominal pain and night sweats.

what do you see on her CT?

Our patient had a mycotic aneurysm of the abdominal aorta.  This is somewhat of a misnomer since the aneursyms can be caused by bacteria as well as fungi.  The term was coined by Osler to describe aneursyms associated with endocarditis. True aneurysms involve all three layers of the arterial wall while a pseudoaneursym is a collection of blood that has leaked out of the the artery and is confined by surrounding tissue.

Impaired immunity  was found in 70 per cent of patients with infected aneursyms  in one study. Arterial injury is also  a risk factor for an infected aneurysm as well as an infection predisposing to bacteremia like diverticulitis, UTI, or pneumonia. Preexisting atherosclerosis can also  lead to infected plaques.

Mycotic aneursyms are most commonly seen in the intracranial arteries but can occur anywhere and have been reported in the coronary arteries. Staph species and Salmonella re the most common causes of mycotic aneursyms. Syphilis  once caused up to 50 percent of infected aneursyms.  Tuberculosis is a rare cause as well.

mycotic aneursym of the LAD in a patient with neurofibromatosis

Our patient had a complicated repair of her aneurysm emergently. She required 60 minutes of aortic cross clamp time and her creatinine rose from  0 .78 to 2.8.  The L 11th rib was removed because the purulence extended up to the diaphragm, the aorta was replaced with a cryo aortic graft and the R renal artery, superior mesenteric artery and celiac arteries were reimplanted into the graft.  The L kidney was then reimplanted.  The large retroperitoneal abscess was drained and grew Strep pneumo.   She recovered with only a minor AKI and was discharged after 9 days on IV ceftriaxone. 

mycotic aneursyms often occur in the brain as in this 18 y.o. with endocarditis.

Osler W. The Gulstonian Lectures on Malignant Endocarditis. R Med J 1885;1:467.

Oderich G, Panneton J, Bower T, et al. Infected aortic aneursyms: aggressive presentation, complicated early outcome, but durable results. J Vasc Surg 2001;34:900.

Negishi K, Ono Y, Kurosawa K, et al. Infective endocarditis complicated by mycotic aneurysm of a coronary artery with a perforated mitral valvular aneurysm.  J Am Coc Echocardiogr. 2009;22(5):542.e1. E pub2009 Mar 9.

Sherif S, Tok O, Tskoylu O, et al.  Coronary artery aneuryms: a review of the epidemiology, pathophysiology, diagnosis and treatment. Font Cardiovasc Med 2017;4:24.