American Urological Association - Medial Fibrosis (with Aneurysms)


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Medial Fibrosis (with Aneurysms)

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  • Most common form of fibromuscular dysplasia, comprises 75% of cases
  • Predominantly affects young women and affects the distal 2/3 of the main renal artery.
  • Commonly bilateral.
  • Gross: alternating thickened and thinned arterial walls give rise to the characteristic "sausage-string" or "string of beads" appearance (especially as seen on angiography) (image A).
  • Histology: fibromuscular thickening of the media alternating with areas of thinning and loss of the internal elastic lamina (image B).
  • Medial dissection may occur in up to 10% of cases.