Janus Kinase Inhibitors in Eosinophilic Granulomatosis With Polyangiitis: An International Case Series

First reported by Churg and Strauss in 1951,¹ eosinophilic granulomatosis with polyangiitis (EGPA) is a rare small vessel vasculitis histologically characterized by eosinophil-predominant granulomatous inflammation, tissue eosinophilia, and necrotizing vasculitis. Antineutrophil cytoplasmic antibodies (ANCA) are detectable in 30-40% of patients with EGPA,² typically associated with specific autoantibodies directed against myeloperoxidase (MPO). With heterogenous clinical presentations, no validated diagnostic criteria, and strong overlap with hypereosinophilic syndrome (HES), EGPA can be difficult to diagnose; however, there are a number of classification criteria with established sensitivity and specificity that can be adapted to clinical practice.³