Vasculitis questions on Step 1 love to test (1) vessel size, (2) key buzzwords, and (3) the one complication you can’t miss (vision loss, aneurysm rupture, coronary aneurysms, etc.). If you can quickly classify the vasculitis and attach the signature association, you’ll turn long stems into one-liners.
Big Picture: What Is Vasculitis?
Vasculitis = inflammation of blood vessel walls → lumen narrowing, thrombosis, ischemia, and sometimes aneurysm formation (from wall weakening).
Core pathophysiology themes (Step-friendly)
- Immune-mediated inflammation damages endothelium and vessel wall.
- Transmural inflammation can weaken the media → aneurysms (classically in medium-vessel disease).
- Ischemia downstream explains organ-specific findings (retina, kidneys, gut, extremities).
How Step 1 wants you to classify vasculitis
- Large vessel: Takayasu, Giant cell (temporal) arteritis
- Medium vessel: Polyarteritis nodosa (PAN), Kawasaki
(Small-vessel vasculitides exist too, but not today.)
One Table to Rule Them All (High Yield)
| Disorder | Vessel size | Classic patient | Key clinical clues | Most testable association | Major complication | First-line treatment |
|---|---|---|---|---|---|---|
| Takayasu arteritis | Large | Young woman (<40), often Asian | “Pulseless disease,” limb claudication, BP discrepancy, bruits | Granulomatous inflammation of aortic arch | HTN (renal artery stenosis), stroke | Glucocorticoids ± steroid-sparing immunosuppression |
| Giant cell arteritis (GCA) | Large | Older adult (>50) | Headache, scalp tenderness, jaw claudication, visual symptoms | Associated with polymyalgia rheumatica | Vision loss (ischemic optic neuropathy) | High-dose glucocorticoids immediately |
| Polyarteritis nodosa (PAN) | Medium | Middle-aged | Systemic + neuro + renal + GI pain | HBsAg association; spares lungs | Microaneurysms → hemorrhage; renal ischemia → HTN | Glucocorticoids + immunosuppressant; treat HBV if present |
| Kawasaki disease | Medium | Child (<5) | Fever ≥5 days + mucocutaneous findings | Coronary aneurysms | MI/sudden death | IVIG + aspirin |
Takayasu Arteritis (“Pulseless Disease”)
Definition
A large-vessel granulomatous vasculitis affecting the aorta and its major branches (especially the aortic arch).
Pathophysiology
- Granulomatous inflammation → vessel wall thickening + luminal narrowing
- Often involves subclavian and renal arteries
- Narrowing → ischemia; renal artery stenosis → secondary hypertension
Clinical presentation (buzzwords)
- Young woman (classically Asian) with:
- Decreased upper extremity pulses
- BP discrepancy between arms
- Bruits over subclavian/aorta
- Limb claudication
- Systemic inflammation: fever, malaise, weight loss
- Labs: ↑ ESR/CRP
Diagnosis
- Suggested by exam findings + inflammatory markers
- Confirm with vascular imaging (e.g., CTA/MRA/angiography): segmental narrowing of large vessels
Treatment (Step 1 level)
- Glucocorticoids first-line
- Consider steroid-sparing immunosuppression if refractory
HY association
- Renal artery stenosis → hypertension in a young patient with unequal pulses.
First Aid cross-reference: Cardiovascular → Vasculitides (Takayasu arteritis)
Giant Cell Arteritis (Temporal Arteritis)
Definition
A large-vessel granulomatous vasculitis involving branches of the carotid artery (especially the temporal artery).
Pathophysiology
- Granulomatous inflammation with giant cells
- Can involve the ophthalmic artery → optic nerve ischemia
Clinical presentation (classic Step stem)
- Age >50
- New headache
- Scalp tenderness (pain when combing hair)
- Jaw claudication (pain with chewing)
- Visual symptoms: transient vision loss, diplopia
- Exam: tender, nodular temporal artery (sometimes decreased pulsation)
- Labs: ↑ ESR, ↑ CRP (often very high)
Diagnosis
- Temporal artery biopsy: granulomatous inflammation with giant cells
- Key nuance: skip lesions → biopsy can be falsely negative
Treatment (do not miss)
- If suspected: start high-dose glucocorticoids immediately
- Do not wait for biopsy—vision loss can be permanent.
HY associations
- Strong association with polymyalgia rheumatica:
- Proximal muscle pain + morning stiffness (shoulders/hips)
- Elevated ESR
- High-yield complication: irreversible vision loss
First Aid cross-reference: Cardiovascular → Vasculitides (Giant cell arteritis); Rheumatology → Polymyalgia rheumatica
Polyarteritis Nodosa (PAN)
Definition
A medium-vessel necrotizing vasculitis affecting multiple organs—classically kidneys and GI tract—with segmental transmural inflammation.
Pathophysiology (what Step 1 wants)
- Transmural necrotizing inflammation → weakened vessel wall → microaneurysms
- Immune complex–mediated in some cases
- Associated with Hepatitis B (classically HBsAg-positive)
- Spares the lungs (very testable)
Clinical presentation (pattern recognition)
Think: systemic illness + ischemia in multiple medium-vessel territories
- Renal: HTN, renal ischemia (but not classic glomerulonephritis pattern)
- GI: postprandial abdominal pain (“intestinal angina”), melena
- Neuro: mononeuritis multiplex, peripheral neuropathy
- Skin: livedo reticularis, nodules, ulcers
- Constitutional symptoms: fever, weight loss, myalgias
Diagnosis
- Labs: nonspecific inflammation; may have HBV markers
- Imaging: angiography can show “string of pearls” microaneurysms
- Biopsy: necrotizing vasculitis of medium arteries
Treatment (Step level)
- Glucocorticoids + immunosuppressant (e.g., cyclophosphamide in severe disease)
- If HBV-associated: add antiviral therapy and consider plasmapheresis in select cases
HY associations + pitfalls
- PAN spares the pulmonary circulation → no lung infarcts/hemorrhage
- Microaneurysms → risk of hemorrhage
- Renal involvement causes hypertension via ischemia/RAAS
First Aid cross-reference: Cardiovascular → Vasculitides (Polyarteritis nodosa); Microbiology/Immunology → Hepatitis B associations
Kawasaki Disease (Mucocutaneous Lymph Node Syndrome)
Definition
A medium-vessel vasculitis in children that classically targets the coronary arteries.
Pathophysiology
- Immune activation → vasculitis of medium vessels
- Coronary artery inflammation → coronary aneurysms and thrombosis risk
Clinical presentation (memorize the cluster)
Fever for ≥5 days + ≥4 of the following:
- Bilateral conjunctival injection (nonexudative)
- Oral mucosal changes: strawberry tongue, cracked lips
- Polymorphous rash
- Extremity changes: erythema/edema of hands/feet → later desquamation
- Cervical lymphadenopathy (often unilateral)
Diagnosis
- Clinical diagnosis
- Supportive findings: ↑ ESR/CRP, thrombocytosis (later), sterile pyuria
- Echo to evaluate for coronary involvement
Treatment (high yield)
- IVIG + aspirin
- IVIG reduces risk of coronary aneurysms
- Aspirin used despite typical pediatric cautions because benefit outweighs risk here (Step 1 expects this)
HY complication
- Coronary artery aneurysms → thrombosis → myocardial infarction in a child
First Aid cross-reference: Cardiovascular → Vasculitides (Kawasaki disease); Pediatrics
Rapid “Which Vasculitis Is This?” Exam Triage
If you see…
- Young woman + unequal arm BPs + bruits → Takayasu
- Older patient + headache + jaw claudication + vision symptoms + ↑ESR → GCA (treat immediately)
- HBsAg+ + systemic symptoms + neuropathy + renal/GI ischemia + no lung findings → PAN
- Child + fever ≥5 days + conjunctivitis + strawberry tongue + rash + LAD → Kawasaki (IVIG + aspirin)
Hypertension Tie-In (Why This Shows Up in “HTN & Vascular Disease”)
Vasculitides cause HTN mainly by renal hypoperfusion:
- Takayasu: renal artery stenosis from large-vessel inflammation → ↑ renin → secondary HTN
- PAN: renal medium-artery involvement → ischemia → ↑ renin → HTN
(GCA and Kawasaki are less “HTN-first” on Step 1, but vascular inflammation drives ischemic complications.)
Step 1 High-Yield Pearls (Commit These)
- GCA: start high-dose steroids now to prevent blindness; biopsy later (skip lesions).
- Takayasu: pulseless disease in young women; aortic arch branches; BP discrepancy.
- PAN: HBV association, spares lungs, microaneurysms (“string of pearls”), neuropathy + abdominal pain.
- Kawasaki: coronary aneurysms; treat with IVIG + aspirin.