Eosinophilic granulomatosis with polyangiitis complicated by pulmonary aspergillosis and misdiagnosed as allergic bronchopulmonary aspergillosis: a case report.

OBJECTIVES: To enhance the diagnostic and therapeutic awareness of eosinophilic granulomatosis with polyangiitis (EGPA) complicated by pulmonary aspergillosis. METHODS: We report a case of EGPA initially misdiagnosed as allergic bronchopulmonary aspergillosis (ABPA) in a 52-year-old female patient. RESULTS: The patient presented with intermittent wheezing for more than six months and had a history of sinusitis. An outside hospital diagnosed ABPA based on pulmonary opacities, bronchiectasis, and evidence of Aspergillus infection, but standard therapy proved ineffective. Upon admission, laboratory findings revealed a markedly elevated absolute peripheral blood eosinophil count (5.29 × 109/L) and positivity for MPO-ANCA and p-ANCA. Serum total IgE was 8.85 IU/mL, and specific IgE to Aspergillus fumigatus was <0.10 IU/mL, both of which were inconsistent with ABPA. Chest CT showed multiple bilateral patchy and nodular opacities with bronchiectasis. Bronchoalveolar lavage fluid targeted next-generation sequencing (tNGS) detected Aspergillus at the genus level (23 sequence reads, relative abundance 33.39%). The diagnosis was revised to EGPA complicated by pulmonary aspergillosis. The patient was treated with glucocorticoids combined with mepolizumab, supplemented with voriconazole. Following treatment, the patient's symptoms resolved, with near normalization of imaging findings and pulmonary function. After 10 months of follow-up, methylprednisolone was completely discontinued in December 2025, and at the last follow-up in May 2026, the patient had been off glucocorticoids for 5 months, with sustained remission and successful extension of the mepolizumab dosing interval to 8 weeks. CONCLUSION: For patients presenting with refractory asthma accompanied by eosinophilia and pulmonary opacities, EGPA should be highly suspected. Glucocorticoids combined with mepolizumab is effective. In patients achieving sustained remission, extending the mepolizumab dosing interval to 8 weeks may be a safe and effective long-term maintenance strategy in carefully selected patients, though this observation requires further validation in prospective studies.