D) Non-typhoidal salmonella (NTS) aortitis

Non-typhoidal salmonella (NTS) is a common culprit in mycotic aneurysm. NTS aortitis is a well-described complication in older persons with atherosclerotic plaque. NTS causes about 40% of all infective aortitis and it is characterized by high morbidity and mortality. This patient’s presentation is thoroughly consistent with this diagnosis. Although endovascular repair has been reported, open surgery has generally been the approach. Iliac artery salmonella arteritis would be distinctly rare but has been reported. Medical management alone will be inadequate for either site.

Answer choice A: Descending aortic dissection from atherosclerosis, is incorrect. The most likely cause of the aneurysm and dissection is the salmonella infection.

Answer choice B: Mycotic aneurysm from a large vessel vasculitis, is incorrect. The most likely cause of the aneurysm and dissection is the salmonella infection.

Answer choice C: Myocarditis, is incorrect. Myocarditis typically presents with pleuritic chest pain, respiratory distress, and/or signs or symptoms of heart failure but would not show the findings described in the vignette. Although there is mild pleural effusion, the ejection fraction is normal for this patient and does not indicate any concern for myocarditis or heart failure.

Answer choice E: STEMI, is incorrect. Myocardial infarction can present similarly to an aortic dissection, especially if serum troponins are elevated; however the CT findings are notable for dissection in the distal descending aorta and the aneurysm at the superior mesenteric artery.

Key Learning Point

Non-typhoidal salmonella (NTS) can cause mycotic aneurysm by seeding in atherosclerotic plaques, and aortitis is a well-described complication of the infection.