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Vasculitis for USMLE Step 2 & COMLEX-USA Level 2

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Overview of Vasculitis
    • Definition: Vasculitis refers to inflammation of blood vessels, leading to damage, narrowing, or occlusion, affecting blood flow and potentially causing organ damage.
    • Classification:
  • Large vessel vasculitis: Affects large arteries (e.g., giant cell arteritis, Takayasu arteritis).
  • Medium vessel vasculitis: Affects medium-sized arteries (e.g., polyarteritis nodosa, Kawasaki disease).
  • Small vessel vasculitis: Affects small arteries, capillaries, and venules (e.g., granulomatosis with polyangiitis, microscopic polyangiitis, Henoch-Schönlein purpura).
    • Etiology:
    • Often idiopathic but may be secondary to infections, autoimmune conditions, drugs, or malignancies.
Clinical Features
    • General Symptoms:
  • Systemic inflammation symptoms: Fever, fatigue, weight loss, and muscle aches.
  • Specific symptoms depend on the vessels and organs involved.
    • Large Vessel Vasculitis:
    • Giant cell arteritis: Headache, scalp tenderness, jaw claudication, vision loss.
    • Takayasu arteritis: Limb claudication, weak or absent pulses, blood pressure discrepancies between limbs.
    • Medium Vessel Vasculitis:
    • Polyarteritis nodosa (PAN): Hypertension, abdominal pain, kidney damage, mononeuritis multiplex.
    • Kawasaki disease: Fever, mucocutaneous inflammation, conjunctivitis, coronary artery aneurysms.
    • Small Vessel Vasculitis:
    • Granulomatosis with polyangiitis (GPA): Sinusitis, lung nodules, glomerulonephritis.
    • Microscopic polyangiitis (MPA): Pulmonary hemorrhage, renal failure.
    • Henoch-Schönlein purpura (HSP): Palpable purpura, joint pain, abdominal pain, renal involvement.
Diagnosis
    • Laboratory Tests:
  • Elevated inflammatory markers (ESR, CRP).
  • Autoantibodies: ANCA for GPA and MPA, elevated IgA for HSP.
  • Blood tests for anemia, leukocytosis, or kidney function (in renal involvement).
    • Imaging:
    • Angiography: Useful for medium and large vessel vasculitis to detect stenosis or aneurysms.
    • CT or MRI: To assess structural changes in blood vessels.
    • Biopsy:
  • Considered the gold standard for diagnosis, particularly in small vessel vasculitis.
Treatment
    • Corticosteroids:
  • High-dose corticosteroids are first-line treatment for most forms of vasculitis.
  • Tapering required once symptoms improve.
    • Immunosuppressive Agents:
  • Cyclophosphamide, methotrexate, azathioprine: Used in severe or refractory cases.
  • Rituximab: Preferred for ANCA-associated vasculitis (GPA, MPA).
    • Special Therapies:
    • IVIG: Important for Kawasaki disease to prevent coronary artery aneurysms.
    • Tocilizumab: Used in giant cell arteritis.
Essential Points
    • Vasculitis involves inflammation of blood vessels, classified by the size of the affected vessels.
    • Diagnosis involves clinical features, lab tests (e.g., ANCA), imaging, and biopsy when necessary.
    • Early recognition and treatment with corticosteroids and immunosuppressants are crucial to prevent irreversible organ damage.
    • Giant cell arteritis is a medical emergency due to the risk of blindness, while Kawasaki disease requires timely intervention to avoid coronary complications.