Acute eosinophilic pneumonia associated with the inhalation of phosgene gas under the presence of cigarette smoking

Cigarette smoking has been thought to be a cause of some cases of acute eosinophilic pneumonia (AEP). However, it is not understood why such patients do not show any apparent symptoms for several weeks from the beginning of smoking to the onset of the illness. Here, we describe a case of AEP that may suggest that an irritant like toxic gas may be necessary for the development of AEP under the presence of smoking habit. The diagnosis of AEP was made by close examinations including chest computed tomography, bronchoalveolar lavage fluid (BALF) and transbronchial lung biopsy. Even after the patient's symptoms completely improved, both the total count of eosinophils and the concentration of eosinophilic cationic protein (ECP) in BALF were still elevated. A smoking provocation test revealed a tiny recurrence of ground-glass opacity in both lung fields, but he did not show any symptoms of AEP again. Concerning this case, it is suggested that cigarette smoking initiated the continuous eosinophil accumulation to the lungs and the inhalation of phosgene gas promoted the development of AEP. We suggest that not only cigarette smoking but also an additional irritant such as toxic gas might be necessary for the development of cigarette smoking-related AEP.