Definition:

Eosinophilic granulomatosis with polyangiitis (EGPA) is a systemic vasculitic disorder of unknown etiology that affects small-to-medium-size blood vessels. This disease has been called Churg-Strauss syndrome (CSS) for many years, and renamed eosinophilic granulomatosis with polyangiitis (EGPA) in 2012. EGPA is characterized by asthma, hypereosinophilia, and extravascular eosinophilic granulomas. Clinically, three phases may be distinguished. The prodromal phase may persist for many years, consisting of asthma possibly associated with allergic rhinitis and often complicated by recurrent rhinosinusitis and nasal polyps. The second phase is characterized by peripheral blood eosinophilia or eosinophilic tissue infiltrates. The third phase is dominated by manifestations resulting from systemic vasculitis. Vasculitis commonly affects the skin, nerves, gastrointestinal tract, and heart. It can be serious and life-threatening. EGPA pathogenesis is not well known. The disease is probably the result of a complex interaction in which genetically and environmental factors lead to an inflammatory response whose principal players are eosinophils, T, and B lymphocytes. HLA-DRB1 and DRB4 alleles and IL10.2 haplotype of the IL-10 promoter gene are the most studied genetic determinants. A combination of high-dose corticosteroids and cyclophosphamide is still the gold standard for the treatment of severe cases, but the use of biological agents such as rituximab or mepolizumab seems to be a promising therapeutic alternative.