Case Report: Benralizumab-induced remission in adolescent-onset ANCA-positive eosinophilic granulomatosis with polyangiitis.

Eosinophilic granulomatosis with polyangiitis (EGPA) is a rare antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis characterized by asthma, eosinophilia, and multi-organ involvement. Adolescent-onset disease is uncommon, and evidence guiding biologic therapy in this population remains limited. We report the case of an 18-year-old female with a history of chronic rhinosinusitis and eosinophilic asthma who presented with worsening asthma control, arthralgia, and peripheral eosinophilia (4, 600 cells/μL), with palpable purpura developing during hospitalization. Chest radiography was initially unremarkable, but chest computed tomography revealed peripheral ground-glass opacities and consolidations. Further workup demonstrated eosinophil-rich perivascular infiltrates with karyorrhectic debris without necrotizing vasculitis on skin biopsy, and high-titer anti-myeloperoxidase (anti-MPO) antibodies >200 RU/mL on immunologic testing. The diagnosis of EGPA was established according to the 2022 ACR/EULAR classification criteria with a total score of 10. Initial treatment with high-dose corticosteroids resulted in partial improvement, but the disease relapsed during tapering, indicating corticosteroid dependence. Benralizumab was subsequently introduced, leading to rapid eosinophil depletion, improved pulmonary function, successful corticosteroid reduction, and prompt clinical remission. At 12-month follow-up, the patient remained in complete remission, with normalized pulmonary function, no evidence of new organ involvement, and a marked decline in anti-MPO antibody titers. This case highlights the importance of considering EGPA in adolescents presenting with difficult-to-control eosinophilic asthma and systemic manifestations, and demonstrates that benralizumab can achieve stable, long-term remission with successful corticosteroid reduction even in ANCA-positive disease.