Abstract
Eosinophilic pneumonia is a known side effect of dupilumab; however, diffuse alveolar hemorrhage has not yet been reported in association with dupilumab. We herein report a case of diffuse alveolar hemorrhage caused by dupilumab. A 57-year-old man with severe asthma was unable to discontinue oral steroids and thus was prescribed dupilumab. The patient was admitted to the hospital four weeks after treatment because of suspected eosinophilic pneumonia. Bronchoscopy revealed diffuse alveolar hemorrhage characterized by hemosiderin-phagocytic macrophages in the bronchoalveolar lavage fluid without eosinophils. The steroid dosage improved the respiratory status and resolved the infiltrate shadow. Dupilumab may thus cause diffuse alveolar hemorrhage, which can be differentiated using bronchoscopy.