Fibromuscular Dysplasia
Vascular Surgery
Illness script · Vascular Surgery
Fibromuscular Dysplasia
Non-inflammatory, non-atherosclerotic disease of medium-sized arteries causing stenosis, aneurysm, and dissection, most often in renal and carotid arteries.
This illness script for Fibromuscular Dysplasia covers predisposing factors, classic presentation, mechanism, workup, management, and the clinical pivots that separate it from look-alikes—written for USMLE Step 1 and clerkship reasoning.
01
Predisposing factors
- Young to middle-aged women (~90% female), peak diagnosis 40–60 years
- Smoking — strongest modifiable risk factor
- Multiparity and oral contraceptive use (hormonal influence)
- Connective tissue disorders (Ehlers-Danlos syndrome, Marfan syndrome)
- Family history present in ~7–11% of cases
- Mechanical stress on arterial wall (renal ptosis, vessel tortuosity)
02
Presentation
- Renovascular hypertension: young woman with severe, difficult-to-control BP
- Abdominal/flank bruit in the absence of atherosclerotic risk factors
- Headache, pulsatile tinnitus, neck pain from carotid/vertebral involvement
- TIA or ischemic stroke (spontaneous carotid/vertebral dissection)
- Often discovered incidentally on cross-sectional imaging
- Renal artery FMD affects distal 2/3 of vessel (vs. proximal ostial in atherosclerosis)
03
Pathophysiology
- Non-inflammatory fibromuscular proliferation of the arterial media (medial fibroplasia ~80% of cases)
- Alternating areas of stenosis and aneurysmal dilation produce the 'string of beads' pattern
- Renal arteries involved in 60–75%; carotid/vertebral arteries second most common
- Weakened arterial wall predisposes to spontaneous dissection and aneurysm formation
04
Diagnostics
- Duplex ultrasound: first-line screening for renal artery FMD
- CTA or MRA: preferred non-invasive cross-sectional imaging for diagnosis and planning
- Catheter-based angiography: gold standard — classic 'string of beads' appearance
- Intimal FMD subtype shows smooth focal stenosis, mimicking atherosclerosis (pitfall)
- Elevated plasma renin activity supports renal artery FMD diagnosis
05
Management
- Renal artery FMD: percutaneous transluminal angioplasty (PTA) — first-line definitive treatment; stenting reserved for PTA failure
- Cerebrovascular FMD: antiplatelet therapy (aspirin); revascularization if symptomatic or dissection present
- ACE inhibitors/ARBs for interim BP control; monitor renal function
- Surgical revascularization if endovascular approach fails or anatomy unsuitable
- Smoking cessation and annual surveillance imaging recommended
06
Clinical pivots
How to separate this script from the look-alikes that show up on exams and on the wards.
Atherosclerotic renal artery stenosis
FMD affects young women with no cardiovascular risk factors and involves distal renal artery; atherosclerosis affects older men at the ostium/proximal vessel.
Takayasu arteritis
Takayasu is inflammatory (elevated ESR/CRP, constitutional symptoms) and affects the aorta and proximal branches; FMD is non-inflammatory and mid-to-distal.
Spontaneous coronary artery dissection (SCAD)
SCAD presents as acute MI in young women; FMD is the underlying predisposing arteriopathy — screen FMD patients for SCAD and vice versa.
Polyarteritis nodosa
PAN is necrotizing vasculitis with systemic inflammation, affects medium arteries without the 'string of beads' pattern, and is ANCA-negative but hepatitis B-associated.
Keep reading
Full library- EpiglottitisAcute, life-threatening supraglottic inflammation causing rapid airway obstruction; classically Haemophilus influenzae type b in children, now more common in adults.
- Giant Cell ArteritisLarge-vessel granulomatous vasculitis of the aorta and its branches, classically affecting the temporal artery in patients >50.
Educational use only. This illness script is a study framework, not medical advice. Confirm decisions with current guidelines and your clinical supervisors.