Eosinophilic granulomatosis with polyangiitis: A comprehensive narrative review

Introduction. Eosinophilic granulomatosis with polyangiitis is a rare, systemic, immune-mediated vasculitis of small- to mediumsized blood vessels, characterised by eosinophil-rich inflammatory response, necrotising vasculitis, and granulomatous tissue reactions. Pathogenesis. The disease arises from a complex interplay of T helper 2- and T helper 1 cells mediated immunity, eosinophil activation, B-cell-autoantibody responses, and epithelialderived alarmins. Anti-neutrophil cytoplasmic antibodies positive (predominantly myeloperoxidase) patients exhibit a vasculitic phenotype, whereas anti-neutrophil cytoplasmic antibodies-negative patients show eosinophil-driven organ involvement. Key laboratory features include marked peripheral eosinophilia, elevated inflammatory markers, increased immunoglobulin E levels, and raised immunoglobulin G4 level. Clinical Presentation. The disease evolves through overlapping prodromal, eosinophilic, and vasculitic phases, producing variable organ involvement and a relapsing-remitting course. Heterogeneous presentation may obscure diagnosis and affect prognosis. Diagnosis and Differential Diagnosis. Diagnosis integrates clinical features, laboratory findings, and histopathologicy analysis. Differential diagnoses include other anti-neutrophil cytoplasmic antibody-associated vasculitides, hypereosinophilic syndromes, eosinophilic lung disorders, drug-induced reactions, parasitic infections, and immunoglobulin G4-related disease. Prognosis. Despite limited evidence, overall survival is generally favourable. Therapy. Management is guided by severity and prognostic factors. Glucocorticoids remain foundational, while biologics targeting interleukin-5, interleukin-4/ interleukin-13, anti-immunoglobulin E - as well as emerging approaches including B-cell depletion, alarmin inhibition, C5a receptor antagonism, and cellular therapies provide steroid-sparing options and improved disease control. Conclusion. Despite favorable survival, morbidity persists due to disease relapses, organspecific complications, and long-term immunosuppression. Advances in immunogenetics, molecular profiling, and targeted therapies support a precision-medicine approach, multidisciplinary care and individualised management to optimise patient outcomes in eosinophilic granulomatosis with polyangiitis.