A 35-year-old man was shot during an armed robbery. The bullet entry wound was in the right fourth intercostal space, above the nipple. A chest radiograph obtained on admission to the emergency room demonstrated complete collapse of the lung.
A further chest radiograph performed 20 minutes later demonstrated an air/fluid level in the pleural cavity (eFig. 3.117).
Three common pathological processes may occur in the pleural cavity.