Acute eosinophilic pneumonia associated with 2009 influenza A (H1N1)

Acute eosinophilic pneumonia (AEP) is a cause of acute respiratory failure, and differs from other eosinophilic pneumonias by its acute onset, presence of fever and acute hypoxaemia. Cases of 2009 influenza A (H1N1) virus infection have included rapidly progressive lower respiratory tract disease resulting in respiratory failure. We describe the case of a young patient who showed dyspnoea, fever and rapid radiological progression and was simultaneously diagnosed with AEP and 2009 influenza A (H1N1) infection, which was diagnosed by using bronchoalveolar lavage (BAL). We suggest that 2009 influenza A (H1N1) virus should be considered as a cause of AEP, and BAL can provide further information, especially in patients with severe lower respiratory disease.