A 71-year-old man with fever and blood cultures growing Salmonella species develops a rapidly expanding, tender pulsatile mass in the left groin two weeks after an episode of gastroenteritis. CT shows a 4 cm aneurysm of the common femoral artery with surrounding stranding. What is the most likely pathogenesis?

• A Degeneration of the arterial media from longstanding hypertension
• B Congenital defect in the tunica media at an arterial bifurcation
• C Infection of the vessel wall with weakening and destruction of the media, usually at a preexisting atherosclerotic focus ✓
• D Granulomatous inflammation of the vasa vasorum with elastic fiber loss

Explanation

This is a mycotic aneurysm, a misnomer since most are bacterial. Organisms such as Salmonella seed the vessel wall during bacteremia, often lodging at preexisting atherosclerotic intimal damage, and destroy the media, producing rapid enlargement and a tendency to rupture. Fever plus a pulsatile mass after documented bacteremia is the classic presentation. Congenital berry aneurysms occur at intracranial bifurcations, and vasa vasorum granulomatous inflammation describes syphilitic aortitis, neither of which fits this scenario.

Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.