Aortic Aneurysm

 

Epidemiology and Etiology:

    • >50 years (except rarely)
    • M > F
    • Causes:
      • 2 most important:
        • Atherosclerosis (destruction of media by plaque)
        • Cystic medial degeneration of the arterial media

·         may be caused by a connection tissue abnormality (ex. Marfan’s)

·         younger patients

·         idiopathic

·         hypertension

·         bicuspid aortic valve

      • Trauma
      • Congenital defects
        • Marfans
      • Infections (mycotic aneurysm)
        • Embolism from infective endocarditis
        • Direct extension from adjacent process
        • Syphilis
        • Salmonella

 

Common sites:

    • Atherosclerotic aneurysms:
      • Abdominal aorta (AAA) – most common
        • Usually below renals and above bifurcation
      • Common iliac
      • Arch
      • Descending thoracic aorta

 

Gross features:

    • Granular mural thrombi often
    • Saccular:
      • Spherical
      • 5-20cm
      • often partially or completely filled with thrombus
    • fusiform:
      • involving a long segment of the artery
      • up to 20cm diameter

 

Histologic features:

    •  inflammatory aortic aneurysm:
      • dense periaortic fibrosis with abundant inflammatory reaction
        • lymphocytes
        • plasma cells
        • many macrophages
        • giant cells often

 

Immunophenotype:

Marker:

Sensitivity:

Specificity:

 

 

 

 

Molecular features:

    •  

 

Other features:

    • risk of rupture (peritoneal, retroperitoneal, pleural, retropleural)
      • <4cm – zero risk
      • 5-6cm – 10% / year risk
      • >6cm – 25% / year risk
    • may affect origins of renal arteries and SMA / IMA, vertebral branches supplying the spinal cord
    • may become infected from bacteremia
      • Salmonella gastroenteritis
    • may embolize
    • may compress adjacent structures (ureter, vertebrae)

 

References:

    • Robbins 2005