Eosinophilic granulomatosis with polyangiitis

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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 phases: 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.

A multisystem disease characterized by necrotizing granulomatous vasculitis with eosinophilia; that most commonly involves the lungs and the skin; can also affect the renal, cardiovascular, gastrointestinal, central, and peripheral nervous systems ^[2]

Most cases are idiopathic.

• Prodromal phase ^[3]
  • Severe allergic asthma attacks (chief concern) ^[3]
  • Allergic rhinitis/sinusitis
• Eosinophilic phase
  • Lung disease
  • Pericarditis
  • Gastrointestinal involvement: bleeding, ischemia, perforation ^[4]
• Vasculitic phase
  • Skin nodules, palpable purpura
  • Mononeuritis multiplex (loss of motor and sensory function with wrist or foot drop), symmetric or asymmetric polyneuropathy
  • Pauci-immune glomerulonephritis

Constitutional symptoms 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. ^[3]

Eosinophilic granulomatosis with polyangiitis (Churg-Strauss syndrome): pANCA and polyneuropathy (foot or wrist drop), allergic rhinitis/sinusitis/asthma, vasculitis, eosinophilia, and skin nodules

EGPA is primarily a clinical diagnosis supported by imaging and histopathological studies.

Laboratory studies ^[3][5][6][7]

• Inflammatory markers: ↑ ESR, ↑ CRP
• CBC: peripheral blood eosinophilia (> 1500 cells/mcL or > 10% of the leukocyte count) ^[3]
• Serology
  • ANCA; present in ∼ 40%: of those, MPO-ANCA in 74–90% ^[6][7]
  • ↑ IgE and ↑ IgG4 levels ^[7]
  • Toxocara, Aspergillus, and HIV: Consider for differential diagnosis. ^[6]

Negative ANCA does not rule out EGPA.

Imaging studies ^[3][7]

• High-resolution CT chest
  • Indication: Obtain for all patients to assess for lung involvement.
  • Findings ^[3]
    • Shifting pulmonary infiltrates
    • Ground-glass opacities
    • Bronchial wall thickening
    • Bronchiectasis
• 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. ^[5]

Biopsy

• Indications: confirmatory test ^[3][6]
• Findings
  • Necrotizing vasculitis (eosinophilic infiltration with fibrinoid necrosis)
  • Extravascular necrotizing granulomas
  • Extravascular tissue eosinophilia

General principles ^[5][6][8]

• 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. ^[8]

Management of EGPA is based on disease severity, taking into account the presence of organ- and/or life-threatening manifestations (e.g., alveolar hemorrhage, glomerulonephritis, limb ischemia). ^[5]

Pharmacotherapy ^[5]

• Induction of remission: for patients with active disease
  • Nonsevere disease
    • Oral glucocorticoids: e.g., prednisone ^[5]
    • PLUS a glucocorticoid-sparing agent: e.g., mepolizumab (preferred), methotrexate, OR mycophenolate mofetil
  • Severe disease
    • High-dose glucocorticoids: e.g., methylprednisolone pulses OR prednisone
    • PLUS a glucocorticoid-sparing agent: e.g., rituximab (preferred) OR cyclophosphamide
• Maintenance of remission: indicated for patients who presented with severe disease
  • Slowly taper glucocorticoids to the minimum effective dose. ^[5]
  • Glucocorticoid-sparing agents: e.g., rituximab (preferred), methotrexate, OR azathioprine

Supportive care

• Prevent complications of glucocorticoid therapy.
• Monitor for adverse effects of immunosuppressants.
• Consider pneumocystis pneumonia prophylaxis.