March 20, 2011

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.

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