We describe the case of a 53-year-old man who had been treated for childhood-onset bronchial asthma and atopic dermatitis. In April 20XX, the patient was referred to our hospital for sore throat, fever, and infiltrative shadows in both lungs that had persisted for three weeks. We performed bronchoscopy and lung biopsy, based on which we diagnosed chronic eosinophilic pneumonia (CEP).
High-dose steroid therapy caused the bilateral shadow to abate, and the patient was discharged 22 days after admission. During the gradual reduction of steroid dosage, we observed the aggravation of both asthma and atopic dermatitis. Significant improvement was seen in both diseases after commencing dupilumab treatment although CEP recurred owing to tapering of steroids. Our findings suggest that dupilumab is effective for both bronchial asthma and atopic dermatitis; however, the drug may be ineffective in the treatment of CEP.