Chapter 142 - Fibromuscular dysplasia Flashcards
Fibromuscular dysplasia definition
1) Nonatheromatous noninflammatory proliferative process
2) medium sized conduit (long) arteries most common (renal, ICA)
First description of FMD
1938 String of beads appearance
Epidemiology of FMD
1) women > 90%
2) age 20-60
3) 10% familial
4) caucasians 95%
FMD and renal stenosis key points
1) 2nd most common renal stenosis
2) most common renal HTN in children
FMD associations with other factors and conditions
1) smoking
2) estrogen
3) ACE polymorphism
4) phenochromocytoma
5) Marfan
6) Alport syndrome
7) Takayasu
Pathogenesis of FMD
1) Vasovasorum damage from motion
2) long arteries with less vasovasorum more likely
3) Right renal > left renal to be affected and have ptosis
Differential diagnosis of FMD
1) Neurofibromatosis 1
2) EDS4
3) Williams syndrome
4) vasculitis
Differentiating NF1 and FMD
NF1 has characteristic skin lesions
Differentiating EDS4 from FMD
1) acrogeric dysmorphism
2) skin elasticity
3) distal joint laxity
in EDS4
Differentiating williams syndrome from FMD
1) facial dysmorphism
2) supra-aortic stenosis
3) behaviour changes
in Williams
Angiographic classification of FMD
1) Multifocal string of beads
2) focal with single area of stenosis
Histopathologic scheme of FMD
1) Intima fibroplasia (5-10%)
2) medial fibroplasia (80-85%)
3) periarterial/adventitial fibroplasia (<1%)
Secondary events from dysplastic lesions in FMD
Aneurysm 17% (1/3 in renal)
Dissection 20% (1/5 in renal)
Medial fibroplasia of FMD subdivided classes
1) Medial fibroplasia
2) perimedial fibroplasia
3) medial hyperplasia
Intimal fibroplasia key points
1) young no gender difference
2) collagen deposition in intima
3) disrupted internal elastic lamina
4) focal ring-like stenosis
Medial fibroplasia key points
1) Age 20-70
2) female:male 5-9:1
3) thinned media alrternating with thickened fibromuscular ride with collagen
4) can have secondary intimal hyperplasia
5) string of beads with beads larger than native vessel
6) distal 2/3 of main renal and branches 25%
Perimedial fibroplasia key points
1) young female < 50
2) patchy collagen deposition
3) intact external elastic lamina
4) string of bead but diameter less than native
Adventitial fibroplasia
1) no gender difference
2) collage replace normal adventitia
3) unifocal to long stenosis
Multiple vascular bed rate in FMD
2 vascular bed: 35%
3 vascular bed: 22%
difference in FMD and atherosclerotic lesions affecting renal function
FMD is mainly RAAS driven
Atherosclerosis can also be inflammatory driven
FMD natural history from asymptomatic in 4 years
1) 25% get HTN
2) 40% get FMD progression angiographically (overestimate)
Percentage of secondary hypertension in all HTN
5%