Eosinophilic granulomatosis with polyangiitis (EGPA) is an ANCA-associated vasculitis of small vessels characterized by necrotizing granulomatous vasculitis with eosinophilia. It most commonly involves the lungs and skin. Clinical features are often divided into three phrases: a prodromal phase (i.e., severe allergic asthma attacks, allergic rhinitis/sinusitis), an eosinophilic phase (e.g., pericarditis, gastrointestinal involvement), and a vasculitic phase (e.g., cutaneous nodules, palpable purpura, mononeuritis multiplex); constitutional symptoms are often also present. Laboratory studies typically reveal peripheral blood eosinophilia, MPO-ANCAs, and increased IgE levels. High-resolution CT chest and echocardiogram are required to assess for pulmonary and cardiac involvement. Biopsy of the affected tissue is required to confirm the diagnosis; findings include necrotizing vasculitis (eosinophilic infiltration with fibrinoid necrosis). Management typically involves immunosuppressive agents (e.g., glucocorticoids). Plasmapheresis may be indicated in patients with rapidly progressive renal failure or pulmonary hemorrhage.
Most cases are idiopathic.
- Prodromal phase 
- Eosinophilic phase
- Vasculitic phase
are often present in all phases. Features from all three phases may be present at the same time and do not necessarily follow a specific order. 
Laboratory studies 
- Inflammatory markers: ↑ ESR, ↑ CRP
- CBC: peripheral blood eosinophilia (> 1500 cells/mcL or > 10% of the leukocyte count) 
Negative ANCA does not rule out EGPA.
Imaging studies 
- High-resolution CT chest
- Echocardiogram: Obtain for all patients to assess for cardiac involvement.
Cardiac involvement affects treatment decisions and is the main cause of death in patients with EGPA. 
- Indications: confirmatory test 
General principles 
- Consult rheumatology and other specialties (e.g., nephrology, pulmonology) as required.
- Goal of pharmacotherapy (e.g., glucocorticoids PLUS cyclophosphamide) is induction of remission
- Plasmapheresis is only considered for patients with rapidly progressive renal failure or pulmonary hemorrhage. 
Induction of remission: for patients with active disease
- Nonsevere disease
- Severe disease
- Maintenance of remission: indicated for patients who presented with severe disease
- Monitor for .
- Consider .