Infected (Mycotic) Aortic Aneurysm

An axial CT image shows a saccular aneurysm (arrowheads) arising from the infrarenal abdominal aorta (arrow), with periaortic soft tissue attenuation and fat stranding. Infected aortic aneurysm was confirmed at surgery.

Facts

• It is a consequence of infectious aortitis with wall being weak and ruptured forming a false lumen or pseudoaneurysm
• Most common location = infrarenal aorta
• Most common causative agent = Salmonella
• Route of infection = hematogenous, contiguous seeding, traumatic/iatrogenic inoculation
• Mycotic = infection not confined only to fungus (use of mycotic aneurysm can be misleading)

Imaging

• Aneurysm mostly saccular
• Aneurysm size ranging from 1-10 cm
• Around aneurysm: gas, soft tissue stranding, fluid
• Can be confused with neoplasm, infected lymph nodes or hematoma

Reference:

Restrepo CS, Ocazionez D, Suri R, Vargas D. Aortitis: imaging spectrum of the infectious and inflammatory conditions of the aorta. RadioGraphics 2011;31:435-451.