Severe asthma with viral infection can develop into eosinophilic granulomatosis with polyangiitis

Asthma is common in eosinophilic granulomatosis with polyangiitis (EGPA), and the annual incidence of EGPA in patients with asthma is much higher compared with the general population, and the trigger factor for this is unknown. We report a case of a 19-year-old male with a background of severe asthma who presented with eosinophilic lung infiltration after viral infection, which progressed to clinical EGPA. The diagnosis of EGPA was supported by an initial clinical presentation of recurrent cough and wheezing accompanied by a red rash, followed by peripheral eosinophilia, a high eosinophil percentage in bronchoalveolar lavage fluid (BALF), and migratory pulmonary eosinophilic infiltrates. Lung biopsy showed blood vessels with extravascular eosinophils. The patient responded well to high-dose glucocorticoids and cyclophosphamide, and symptoms and biochemical markers improved. Our literature review identified few reports on the triggers of EGPA, which highlights that viral infection may be a risk factor for asthma that progresses to EGPA.