Coexistence of Eosinophilic Granulomatosis With Polyangiitis and Allergic Bronchopulmonary Aspergillosis: A Fascinating Relationship

Elevated eosinophil counts are associated with various diseases, including eosinophilic granulomatosis with polyangiitis (EGPA) and allergic bronchopulmonary aspergillosis (ABPA). EGPA is a rare small-vessel vasculitis characterized by asthma, eosinophilia, fleeting pulmonary infiltrates, and systemic manifestations. ABPA, initiated by immune reactions against in the airways, presents with poorly controlled asthma, wheezing, hemoptysis, productive cough, and systemic symptoms, which result in characteristic central bronchiectasis. Fleeting pulmonary opacities are common radiologic findings. We present a case of ABPA in a patient with a prior EGPA diagnosis under treatment with mepolizumab 300 mg monthly and review eight similar cases from the literature. In these cases, EGPA and ABPA diagnoses preceded each other or were concurrent. Treatment of the latter improved control of both diseases. IL-5 is pivotal in EGPA pathogenesis, and mepolizumab, targeting IL-5, has been effective in EGPA treatment. Our patient received mepolizumab for EGPA and continued it post-ABPA diagnosis, showing favorable outcomes. This suggests mepolizumab as a therapeutic link between EGPA and ABPA. Mepolizumab therapy holds promise for managing both EGPA and ABPA. Double-blind placebo-controlled studies are warranted to establish its efficacy and safety for ABPA, emphasizing the need for further research in this area.