Eosinophilic Granulomatosis with Polyangiitis

Eosinophilic granulomatosis with polyangiitis (EGPA, formerly Churg-Strauss syndrome) is an ANCA-associated small vessel vasculitis characterized by the triad of asthma + peripheral eosinophilia + systemic vasculitis. EGPA progresses through three phases: (1) prodromal/allergic phase (years): late-onset asthma, allergic rhinitis, sinusitis; (2) eosinophilic phase: peripheral eosinophilia with eosinophilic organ infiltration (lungs, GI, heart); (3) vasculitic phase: small vessel vasculitis with granulomatous inflammation affecting multiple organs. ANCA (usually p-ANCA/MPO) is positive in only 40-60% of EGPA patients — ANCA-positive EGPA tends to have more vasculitic features (glomerulonephritis, mononeuritis multiplex, purpura), while ANCA-negative EGPA tends to have more cardiomyopathy and eosinophilic organ infiltration. Cardiac involvement (eosinophilic myocarditis, cardiomyopathy) is the leading cause of death.