Vasculitis for USMLE Step 3 & COMLEX-USA Level 3

• Definition: Vasculitis is inflammation of blood vessels, which can lead to vessel wall damage, thickening, narrowing, or aneurysm formation.

• Classification:
• Large vessel vasculitis: Involves large arteries (e.g., giant cell arteritis, Takayasu arteritis).
• Medium vessel vasculitis: Involves medium-sized arteries (e.g., polyarteritis nodosa, Kawasaki disease).
• Small vessel vasculitis: Involves small blood vessels like capillaries and arterioles (e.g., granulomatosis with polyangiitis, microscopic polyangiitis, Henoch-Schönlein purpura).

• Etiology:
• Idiopathic (most common).
• Secondary to infections, autoimmune diseases, drugs, or malignancy.

• Systemic Symptoms:
• Fever, weight loss, fatigue, and myalgias are common in vasculitis.
• Organ-specific symptoms depend on the type of vasculitis and the vessels involved.

• Large Vessel Vasculitis:
• Giant cell arteritis: Presents with headache, jaw claudication, scalp tenderness, visual disturbances.
• Takayasu arteritis: Pulseless disease, limb claudication, different blood pressure readings in arms.

• Medium Vessel Vasculitis:
• Polyarteritis nodosa (PAN): Abdominal pain, renal involvement, hypertension, mononeuritis multiplex.
• Kawasaki disease: Fever, conjunctivitis, rash, mucous membrane changes, coronary artery aneurysms.

• Small Vessel Vasculitis:
• Granulomatosis with polyangiitis (GPA): Upper respiratory tract involvement, lung and kidney disease.
• Microscopic polyangiitis (MPA): Glomerulonephritis, pulmonary hemorrhage.
• Henoch-Schönlein purpura (HSP): Palpable purpura, abdominal pain, arthritis, renal involvement.

Here is the formatted and revised version of your content:

• Laboratory Tests:
• Increased ESR and CRP, indicating inflammation.
• Autoantibodies:
• ANCA (for GPA and MPA).
• Anti-GBM (Goodpasture syndrome with RPGN).
• Elevated IgA (for HSP).
• ANA and rheumatoid factor (in some types of secondary vasculitis).
• Anemia of chronic disease, leukocytosis, and elevated creatinine in cases with renal involvement.

• Imaging:
• Angiography: Useful for medium and large vessel vasculitis (e.g., PAN, Takayasu arteritis).
• CT or MRI: To assess vessel inflammation or stenosis.

• Biopsy:
• Considered the gold standard for definitive diagnosis, especially in small vessel vasculitis.

• Corticosteroids:
• High-dose corticosteroids are the first-line treatment in most types of vasculitis.
• Gradual tapering based on clinical response.

• Immunosuppressive Therapy:
• Cyclophosphamide, methotrexate, and azathioprine: Commonly used for severe cases.
• Rituximab: Used in ANCA-associated vasculitis (GPA, MPA).

• Biologics:
• Tocilizumab: Used in giant cell arteritis.
• Intravenous immunoglobulin (IVIG): Important for Kawasaki disease to prevent coronary artery complications.

• Vasculitis can involve large, medium, or small vessels, with symptoms depending on the vessels and organs affected.
• Diagnosis involves clinical suspicion, laboratory markers (e.g., ANCA), imaging, and sometimes biopsy.
• Early treatment with corticosteroids and immunosuppressants is key to reducing morbidity and mortality.
• Giant cell arteritis is a medical emergency due to the risk of blindness, and Kawasaki disease requires prompt treatment to prevent coronary artery complications.