Layden JE, Ghinai I, Pray I, et al. - Experts sought to present pulmonary illness related to e-cigarette use in Illinois and Wisconsin. They determined case-patients as persons who reported the use of e-cigarette devices and related products in the 90 days before symptom onset and had pulmonary infiltrates on imaging and whose illnesses were not attributed to other causes. They performed medical record abstraction and case-patient interviews with the use of standardized tools. A total of 98 case-patients were included, 79% of whom were male; the median age of the patients was 21 years. This initial cluster of illnesses represents an emerging clinical syndrome or syndromes although the definitive substance or substances contributing to injury have not been ascertained. Further study is required to define the pathophysiology and to distinguish the definitive causes.