Eosinophilic granulomatosis with polyangiitis: current status and future perspectives.

Eosinophilic granulomatosis with polyangiitis (EGPA) is a systemic vasculitis with hypereosinophilia that is preceded by asthma and chronic rhinosinusitis with nasal polyps. Since multiple organs may be involved in this disease, early treatment is required. In this regard, glucocorticoid (GC) therapy is often initiated before a definitive diagnosis is made. A biopsy of an injured organ is useful for a diagnosis but is not performed in all cases due to its invasiveness and, at times, diagnostic accuracy. Therefore, a comprehensive diagnosis is often made based on symptoms and clinical course of disease. However, it is sometimes difficult to distinguish EGPA from other hypereosinophilic diseases or vasculitides. In recent years, in addition to GC and immunosuppressive agents, anti-interleukin (IL)-5/IL-5 receptor alpha (IL-5Rα) antibodies targeting eosinophils have become increasingly important in the treatment of EGPA. However, accumulating data suggest that such anti-IL-5/IL-5Rα antibody therapy may have effects beyond those observed in eosinophils. This paper outlines the clinical features, diagnosis, pathogenesis, and current treatment of EGPA, a hypereosinophilic disease.