Occurs in 10-22 per 100,000 people yearly, most common in children under 10. Characterized by immune complex-mediated vasculitis with purpura, abdominal pain, and arthritis. IgA immune complexes deposit in small vessels, causing petechiae and purpura
Granulomatous vasculitis affecting aorta and its branches. Strong female predominance (9:1) and Asian population prevalence. Typical age of onset is 15-30 years. Geographic concurrence with tuberculosis suggests possible link
HSP is a small-vessel vasculitis affecting children under 10 years. Most cases resolve without treatment, but 15-40% have recurrence. Incidence is approximately 20/100,000 children under 17 yearly
Vasculitis is a group of disorders destroying blood vessels through inflammation. Primary cause is leukocyte migration and damage. Can be primary systemic, secondary, or single-organ
Fibrinoid necrosis is a blood vessel lesion characterized by endothelial damage and protein leakage. Affected vessels appear pinkish and structureless due to fibrin accumulation. Term "fibrinoid necrosis" is considered a misnomer due to masking of true necrosis
ANCA are autoantibodies targeting neutrophil proteins. Two main types: MPO-targeting (pANCA) and PR3-targeting (cANCA). Two main types: indirect immunofluorescence and ELISA assays