Potential of ethenone (ketene) to contribute to electronic cigarette, or vaping, product use-associated lung injury

In 2019, the United States experienced an unprecedented outbreak of electronic cigarette (e-cigarette), or vaping, product use– associated lung injury (EVALI). Although reports of lipidladen macrophages in BAL fluid raised the possibility that EVALI represented exogenous lipoid pneumonia, case series that focused on histopathology found patterns of acute lung injury, including diffuse alveolar damage and organizing pneumonia, often with bronchiolitis. Thus, the available evidence to date suggests the outbreak is characterized by an airway-centered chemical pneumonitis rather than acute exogenous lipoid pneumonia.