Vasculitis

Vasculitis Basics - Vessel Villains

• Inflammation & necrosis of blood vessel walls, leading to impaired blood flow & organ damage.
• Classification (Chapel Hill Consensus Conference - CHCC):
  • Large-vessel vasculitis (LVV): Giant cell arteritis (GCA), Takayasu arteritis (TAK).
  • Medium-vessel vasculitis (MVV): Polyarteritis nodosa (PAN), Kawasaki disease (KD).
  • Small-vessel vasculitis (SVV):
    • ANCA-associated vasculitis (AAV): Microscopic polyangiitis (MPA), Granulomatosis with polyangiitis (GPA), Eosinophilic granulomatosis with polyangiitis (EGPA).
    • Immune complex SVV: IgA vasculitis (Henoch-Schönlein purpura), Cryoglobulinemic vasculitis.

⭐ The Chapel Hill Consensus Conference (CHCC) nomenclature is widely used for classifying vasculitides based on vessel size and etiology.

• Pathogenesis: Immune complex deposition, anti-neutrophil cytoplasmic antibodies (ANCAs), direct T-cell mediated injury. 📌 Mnemonic (ANCA): Anti-Neutrophil Cytoplasmic Antibodies target enzymes in neutrophils (MPO, PR3).

Clinical Clues - Skin Deep & More

• Cutaneous Manifestations:

  • Palpable purpura: Non-blanching, raised lesions; hallmark, often on lower extremities & dependent areas.

  ⭐ Palpable purpura, especially on lower extremities, is the most common cutaneous manifestation of small vessel vasculitis.

  • Livedo reticularis/racemosa: Net-like, violaceous pattern.
  • Nodules, papules, vesicles, bullae, ulcers, digital gangrene.
  • Urticarial vasculitis: Persistent wheals (>24h), often painful/burning, may leave pigmentation.

• Systemic Clues (Variable):

  • Constitutional: Fever, malaise, weight loss, arthralgia, myalgia.
  • Renal: Hematuria, proteinuria (e.g., IgA vasculitis, ANCA-associated vasculitis).
  • GI: Abdominal pain, melena (e.g., IgA vasculitis).
  • Pulmonary: Cough, hemoptysis, dyspnea (e.g., ANCA-associated vasculitis).
  • Neurological: Mononeuritis multiplex, peripheral neuropathy, headache, stroke.
  • Ocular: Episcleritis, uveitis, retinal vasculitis.

• 📌 Mnemonic (HSP features): "Henoch's Shönlein Purpura" - Hematuria, Stomach ache (abdominal pain), Palpable purpura, Arthritis (often Ankles/knees).

Diagnostic Drilldown - Finding the Fire

• Essential Labs:
  • CBC (anemia, thrombocytosis), ↑↑ESR/CRP.
  • Urinalysis (RBCs, casts, proteinuria).
  • Renal function (Creatinine), LFTs.
  • Hepatitis B/C serology, Cryoglobulins (check with purpura, arthralgia, weakness).
• ANCA (Key for Small Vessel Vasculitis):

  ⭐ A positive ANCA test is highly suggestive of certain small vessel vasculitides: c-ANCA/PR3 for GPA and p-ANCA/MPO for MPA and EGPA.

• Biopsy (Gold Standard):
  • Site: Skin (newest purpuric lesion for LCV), Kidney (pauci-immune GN in ANCA+), Nerve, Lung.
  • DIF: IgA deposition (IgA Vasculitis), C3.
• Targeted Imaging:
  • CXR/HRCT Chest (nodules, infiltrates, hemorrhage - GPA, EGPA, MPA).
  • Angiography (medium/large vessels: aneurysms, stenosis - PAN, Takayasu).
  • Doppler US (GCA: temporal artery 'halo sign').

High-Yield Syndromes - Rogues' Gallery

• Kawasaki Disease
  • Fever >5d + 📌 CRASH & Burn (Conjunctivitis, Rash, Adenopathy, Strawberry tongue, Hand/foot edema).
  • Risk: Coronary aneurysms.
  • Rx: IVIG 2g/kg + Aspirin (80-100mg/kg/d → 3-5mg/kg/d).

  ⭐ Kawasaki disease requires prompt treatment with IVIG and high-dose aspirin to prevent coronary artery aneurysms.

• Henoch-Schönlein Purpura (HSP) / IgA Vasculitis
  • Tetrad: Palpable purpura (buttocks/legs), Arthritis, Abd pain, Renal (IgA nephropathy).
  • Post-URI.
• Behçet's Disease
  • Recurrent oral & genital ulcers, uveitis.
  • Pathergy test (+). HLA-B51.
• Polyarteritis Nodosa (PAN)
  • Medium-vessel; spares lungs. Hep B assoc.
  • Livedo reticularis, nodules, renal (no GN), neuropathy. "Rosary bead" angiography.

High‑Yield Points - ⚡ Biggest Takeaways

• Palpable purpura: Hallmark of Leukocytoclastic Vasculitis (LCV).
• Henoch-Schönlein Purpura (HSP): IgA deposition, classic triad (purpura, arthritis, abdominal pain), often post-URI.
• Polyarteritis Nodosa (PAN): Associated with Hepatitis B, affects medium vessels; presents with nodules, livedo reticularis.
• GPA (Wegener’s): c-ANCA positive; involves upper/lower respiratory tract and kidneys.
• EGPA (Churg-Strauss): Asthma, eosinophilia, p-ANCA positive.
• Microscopic Polyangiitis (MPA): p-ANCA positive; causes pauci-immune glomerulonephritis and pulmonary capillaritis.