From Anti-Neutrophil Cytoplasmic Antibody-Negative to Positive: Eosinophilic Granulomatosis with Polyangiitis Under Benralizumab After Steroid Cessation.

Background: Eosinophilic granulomatosis with polyangiitis (EGPA) is a rare systemic vasculitis characterized by asthma, eosinophilia, and small- to medium-vessels inflammation. Case Report: We present the case of a 28-year-old woman with severe eosinophilic asthma, chronic rhinosinusitis with nasal polyposis, and recurrent pruritic skin lesions. She was diagnosed with EGPA based on the presence of asthma, peripheral eosinophilia, histopathologically confirmed vasculitis, and sinus-related involvement. Long-term corticosteroid therapy resulted in adverse effects, necessitating a transition to mepolizumab and subsequently to benralizumab. Although systemic corticosteroids were successfully discontinued under benralizumab therapy, the patient developed pruritic papular-plaque skin lesions in the eighth month of treatment. Laboratory evaluation revealed new-onset perinuclear anti-neutrophil cytoplasmic antibody (p-ANCA) positivity despite normal eosinophil counts. Conclusion: This case highlights the importance of close ANCA monitoring and increased awareness of skin manifestations in patients treated with benralizumab in whom systemic corticosteroids can be discontinued.