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An ANCA-associated vasculitis (along with granulomatosis with polyangiitis and microscopic polyangiitis)
However, the presence of antineutrophil cytoplasmic antibody (ANCA) occurs in < 50% of patients (usually anti-myeloperoxidase [MPO] antibody)
Previously called Churg-Strauss syndrome
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Peripheral eosinophilia and vasculitis
Laboratory work-up for unexplained eosinophilia should include
Eosinophilic infiltrates on tissue samples
Strongly suggest the diagnosis of eosinophilic granulomatosis with polyangiitis
Diagnosis even more likely if accompanied by vasculitis (purpura, glomerulonephritis, vasculitic ulcers, mononeuritis multiplex)
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Corticosteroids remain first-line treatment
Azathioprine or methotrexate for mild to moderate disease
Mepolizumab, an interleukin (IL)-5 inhibitor
Food and Drug Administration-approved for the treatment of eosinophilic granulomatosis with polyangiitis
However, it has not been studied for severe life- or organ-threatening vasculitic disease manifestations (which generally require cyclophosphamide)
Rituximab may be considered as an option for patients with refractory disease