Acute eosinophilic pneumonia following heat-not-burn cigarette smoking.

A 20-year-old man was admitted with acute respiratory failure. He had started smoking 20 heat-not-burn cigarettes (HC) per day 6 months previously, then purchased a second device for smoking HC to increase smoking to 40 cigarettes per day 2 weeks before hospitalization. Acute eosinophilic pneumonia (AEP) was diagnosed based on medical history, chest high-resolution computed tomographic findings, and bronchoalveolar lavage fluid eosinophilia. On starting treatment with prednisolone, the patient exhibited complete recovery. A relationship between cigarette smoking and AEP has been suggested. HC were released in September 2015 in Japan, Italy, and Switzerland. HC attract attention as a cigarette generating less harmful substances than a conventional cigarette. We herein report the first case of AEP caused by smoking HC. HC are expected to spread around the world. In the same way as a conventional cigarette, HC should be recognized as a potential cause of AEP.