Saito A, et al. - In this cross-sectional analysis, researchers focused on the characterization of radiological and clinical characteristics of pleural thickening on chest X-rays. They analyzed 28,727 chest X-rays obtained from annual health examinations and found that the most common abnormal radiological finding was pleural thickening. The area of the lung where pleural thickening mostly occurred (92.2%) was the apex, especially on the right side; thus, it was defined as a pulmonary apical cap. Males vs females and current smokers or ex-smokers compared with never smokers more commonly developed pleural thickening. With age, an increase in the prevalence was noted, ranging from 1.8% in teenagers to 9.8% in adults aged 60 years and older. An obvious link of pleural thickening with greater height and lower body weight and body mass index is suggestive of a possible predisposition to pleural thickening in tall subjects with thin body shape. Disproportionate perfusion, ventilation, or mechanical forces in the lungs could account for pleural thickening.