Vasculitis

Vasculitis: Classification & Pathogenesis - Vessel Vandals Intro

• Definition: "Vessel Vandals" - inflammation & damage to blood vessel walls (arteries, veins, capillaries), leading to tissue ischemia, organ damage, necrosis, or hemorrhage.
• Pathogenesis: Primarily immune-mediated mechanisms:
  • Immune complex deposition (Type III Hypersensitivity).
  • ANCA (Anti-Neutrophil Cytoplasmic Antibodies) targeting PR3 (c-ANCA) or MPO (p-ANCA).
  • Anti-Endothelial Cell Antibodies (AECA).
  • Autoreactive T-cells (granulomatous inflammation).
  • Less commonly: direct pathogen invasion.
• Classification (Dominant vessel size - CHCC 2012):

⭐ Systemic symptoms (fever, myalgia, arthralgia, malaise, weight loss) are common across many vasculitides.

Large Vessel Vasculitis: GCA & Takayasu - Aorta's Agony

• Giant Cell Arteritis (GCA)

  • Age >50 yrs. Affects temporal, ophthalmic arteries.
  • Sx: Headache, jaw claudication, visual loss, Polymyalgia Rheumatica (PMR).
  • Dx: ↑ ESR (>50 mm/hr), temporal artery biopsy (granulomas, giant cells).
  • Rx: Urgent high-dose steroids (prednisone 40-60 mg).
  • 

• Takayasu Arteritis

  • Age <40-50 yrs (young Asian women). "Pulseless disease".
  • Sx: ↓Pulses (BP diff >10 mmHg btw arms), claudication, bruits. Aortic arch syndrome.
  • Dx: ↑ ESR, angiography (CT/MR) shows stenosis/thickening.
  • Rx: Corticosteroids.
  • 📌 TakaYAsu: Young Asian.

⭐ GCA: Risk of irreversible blindness mandates immediate high-dose steroid therapy if suspected (e.g., new headache, visual sx, jaw claudication in elderly).

Medium Vessel Vasculitis: PAN & Kawasaki - Artery Afflictions

• Polyarteritis Nodosa (PAN)

  • Necrotizing vasculitis of medium-sized arteries; spares pulmonary circulation.
  • Associated with Hepatitis B (HBsAg) in ~30% cases.
  • Clinical: Fever, weight loss, myalgia, abdominal pain (mesenteric ischemia), hypertension (renal artery involvement), mononeuritis multiplex.
  • Pathology: Transmural inflammation, fibrinoid necrosis, "beads-on-a-string" appearance on angiography.
  • 📌 Mnemonic: Pulmonary Artery Not involved.

• Kawasaki Disease (Mucocutaneous Lymph Node Syndrome)

  • Typically affects children < 5 years.
  • Clinical: Fever >5 days, conjunctivitis, rash, adenopathy, strawberry tongue, hand-foot changes (edema, erythema, desquamation).
  • Major complication: Coronary artery aneurysms.
  • Treatment: IVIG and Aspirin.

⭐ Kawasaki Disease is the leading cause of acquired heart disease in children in developed countries; coronary artery aneurysms are a feared complication, treat with IVIG and high-dose aspirin initially, then low-dose aspirin for thromboprophylaxis.

Small Vessel Vasculitis: ANCA & Immune Complex - Capillary Crisis

Affects capillaries, venules, arterioles. Two types: ANCA-associated (AAV) & Immune Complex-mediated (ICV).

• ANCA-Associated Vasculitis (AAV): Pauci-immune (scant/no immune deposits).
  • Microscopic Polyangiitis (MPA): p-ANCA (MPO). Necrotizing GN, pulmonary capillaritis. No granulomas.
  • Granulomatosis with Polyangiitis (GPA): c-ANCA (PR3). Triad: URT, LRT (nodules, cavities), renal (RPGN). Necrotizing granulomas. 📌 C-ANCA, Cavities.
  • Eosinophilic GPA (EGPA): p-ANCA (MPO) in ~50%. Asthma, ↑eosinophils (>10% or >1500/μL), neuropathy. Eosinophilic granulomas.
• Immune Complex Vasculitis: Immune complex deposition.
  • IgA Vasculitis (HSP): Children. Palpable purpura (buttocks, lower limbs), arthralgia, abdominal pain, IgA nephropathy. Post-URI.
  • Cryoglobulinemic Vasculitis: HCV-linked. Meltzer's triad: purpura, arthralgia, weakness. Type II/III cryoglobulins.
  • Anti-GBM Disease (Goodpasture's): Abs to Type IV collagen (α3). Pulmonary hemorrhage, RPGN. Linear IgG IF.

Capillary Crisis (Pulmonary-Renal Syndrome):

• Diffuse Alveolar Hemorrhage (DAH) + Rapidly Progressive Glomerulonephritis (RPGN). Life-threatening.
• Seen in AAV (MPA, GPA), Anti-GBM disease.
• Rx: High-dose steroids, cyclophosphamide/rituximab, plasmapheresis.

⭐ GPA (Wegener's) is characterized by the triad of upper respiratory tract, lower respiratory tract, and renal involvement, often with c-ANCA (PR3-ANCA) positivity.

High‑Yield Points - ⚡ Biggest Takeaways

• Giant Cell Arteritis: Elderly, temporal artery, polymyalgia rheumatica, risk of blindness; prompt steroids.
• Takayasu Arteritis: "Pulseless disease", young females, granulomatous inflammation of aortic arch & branches.
• Kawasaki Disease: Children <5 yrs, coronary artery aneurysms risk; mucocutaneous signs, IVIG + aspirin.
• Polyarteritis Nodosa (PAN): Medium-vessel vasculitis, Hepatitis B link, renal/visceral arteries, spares lungs.
• ANCA-associated: GPA (c-ANCA): URT/LRT/Kidney granulomas; MPA (p-ANCA): Lung/Kidney, no granulomas; EGPA (p-ANCA): Asthma, eosinophilia.