Cigarette smoking-induced acute eosinophilic pneumonia showing tolerance in broncho-alveolar lavage findings.

A 19-year-old man was admitted due to acute respiratory failure. He had started cigarette smoking (CS) about three weeks prior to onset. Multiple nodular shadows and patchy infiltrations were found on chest computed tomography. His respiratory state improved promptly by intravenous methylprednisolone. He resumed CS soon after discharge without any symptoms. We suspected CS-induced acute eosinophilic pneumonia and performed broncho-alveolar lavage (BAL) about one month after onset. The proportion of eosinophils in BAL fluid was 72%. A second BAL was performed about 18 months after onset and BAL fluid included no eosinophils, despite the fact that he had continued CS.