Antineutrophil Cytoplasmic Antibody (ANCA)-Positive Eosinophilic Granulomatosis With Polyangiitis Presenting With Refractory Asthma, Mononeuritis Multiplex, and Cutaneous Vasculitis: A Case Report.

Eosinophilic granulomatosis with polyangiitis (EGPA) is a rare antineutrophil cytoplasmic antibody (ANCA)-associated small-vessel vasculitis characterised by asthma, eosinophilia, and eosinophil-rich tissue inflammation. Early diagnosis is often difficult because initial features may resemble uncontrolled asthma or other eosinophilic lung diseases. We report a 66-year-old man with adult-onset asthma who presented with four months of progressive dyspnoea, constitutional symptoms, peripheral neuropathy, and cutaneous vasculitis. Investigations showed marked eosinophilia (19.1 × 10⁹/L), raised inflammatory markers, elevated creatine kinase and lactate dehydrogenase, and markedly elevated IgG4. Cross-sectional imaging showed calcified mediastinal and hilar lymph nodes without pulmonary infiltrates. Extensive infectious and haematological investigations were unrevealing. Anti-myeloperoxidase antibodies were positive, and skin biopsy confirmed small-vessel vasculitis with eosinophilic infiltration. A diagnosis of ANCA-positive EGPA was made. The patient was treated with high-dose corticosteroids, but symptom recurrence during steroid taper prompted escalation to intravenous cyclophosphamide for organ-threatening neurological involvement. This case highlights the importance of considering EGPA in patients with refractory asthma, eosinophilia, and systemic features even in the absence of pulmonary infiltrates. Early recognition and multidisciplinary management are essential to reduce irreversible organ damage.