🧵 Vasculitis is Not One Disease – It’s a Spectrum
It’s not a diagnosis.
It’s a mechanism.
From small-vessel purpura to large-vessel aneurysms, here’s how to recognize and reason through the vasculitis spectrum👇
@Amansharmapgi @DurgaPrasannaM1 @12VRavindran @Kanjivellam @IhabFathiSulima @DrAkhilX #MedTwitter

1️⃣ Start With the Vessel Size

🔹 Large vessel: aorta and branches
🔸 Medium vessel: muscular arteries
🔻 Small vessel: arterioles, venules, capillaries
Your clues lie in which organ is hit—and how. 

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2️⃣ Large Vessel: GCA & Takayasu

🧠 GCA: headache, jaw claudication, vision loss
💪 TAK: limb claudication, BP discrepancy
Both = aortitis
Treat early. Blindness or aneurysm waits for no one. 

3️⃣ Medium Vessel: PAN & Kawasaki

💥 PAN: HTN, mononeuritis multiplex, mesenteric ischemia
👶 Kawasaki: mucositis, rash, coronary aneurysms
Think ischemia, not inflammation. 

4️⃣ Small Vessel: The Chameleons

🔹 ANCA-associated (GPA, MPA, EGPA)
🔸 Immune complex (IgA, cryo, lupus)
These hit kidneys, lungs, skin, nerves
Clue = multisystem + rapidly evolving 

5️⃣ ANCA Isn’t a Diagnosis

c-ANCA → GPA
p-ANCA → MPA, EGPA
But:
✅ Can be ANCA-negative
❌ Not every positive ANCA = vasculitis
Use it wisely. 

6️⃣ Skin First? Look Beneath

Palpable purpura may be the tip of systemic small vessel vasculitis
🧪 Get UA
🔬 Biopsy if needed
Don’t call it “just a rash” 

7️⃣ The Pulmonary-Renal Syndrome

Cough + hematuria = 🔔 ring the vasculitis alarm
Think GPA, MPA, Goodpasture’s
This combo = emergency 

8️⃣ Rule Out Mimics

❌ Sepsis
❌ Endocarditis
❌ Drug rashes
❌ Cholesterol emboli
Vasculitis is a diagnosis of exclusion 

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9️⃣ Biopsy When You Can

Skin, nerve, kidney, temporal artery
A well-done biopsy can change management
🧠 Biopsy what’s active, not what’s easy 

🔟 Don’t Wait for All Clues

Vasculitis can evolve fast
Start treatment when the picture fits
You don’t need 100% certainty to save a kidney—or a life 

🧠 Final Take

Vasculitis is a syndrome, not a single disease.
⚡ Think anatomically.
⚖️ Rule out mimics.
🎯 Treat early when danger is clear. 

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