Cryptogenic organizing pneumonia after withdrawal of systemic corticosteroids for chronic eosinophilic pneumonia and severe asthma under benralizumab treatment

A 79-year-old woman with severe asthma developed chronic eosinophilic pneumonia (CEP). After CEP resolved with oral prednisolone at 30 mg/day, prednisolone was tapered and discontinued under introduction of benralizumab for her severe asthma. However, 8 weeks later, symptoms and bilateral patchy infiltrates on chest radiography appeared. Lymphocytosis without eosinophilia was seen in bronchoalveolar lavage fluids, and transbronchial biopsy indicated organizing pneumonia. Cryptogenic organizing pneumonia (COP) was diagnosed and resolved with prednisolone at 30 mg/day. Prednisolone was tapered to 3 mg/day without relapse of CEP or COP. This case suggests the overlap and similar pathogenesis of CEP and COP.