Pneumomediastinum. Thirty-four-year-old male with chest pain after vigorous cough. Axial CT image shows moderate pneumomediastinum (long arrow) caused by Macklin effect. Subpleural gas (short arrow) caused by alveolar rupture in the setting of increased intrathoracic pressure with air dissecting along the subpleural interstitium, interlobular septa, peribronchovascular interstitial sheaths, and eventually into the mediastinum (Macklin effect). While this mimics EP, there is a lack of inflammatory changes and hydropneumothorax commonly associated with esophageal perforation