Acute Eosinophilic Pneumonia Induced by Switching from Conventional Cigarette Smoking to Heated Tobacco Product Smoking.

Acute eosinophilic pneumonia (AEP) is an acute respiratory illness with diffuse pulmonary infiltrates and pulmonary eosinophilia. While the etiology of AEP remains unclear, a relationship between cigarette smoking and AEP onset has been suggested. The use of heated tobacco products (HTPs) has been growing, but the impact of these products on our health is not fully understood. We herein report a case of AEP that developed after switching from conventional cigarette to HTP smoking. The patient's condition improved after the cessation of HTP smoking and corticosteroid treatment initiation. In cases of AEP, physicians should consider HTPs use as a possible cause.