Fig. 11.

Air collection in the intrathoracic extrapleural space of a 64-year-old woman. She has Sjögren’s syndrome and interstitial pneumonia. a A supine radiograph shows a linear opacity (black arrows) in the left peripheral lung field that resembles pneumothorax. Fascial webs (black arrowheads) are visible outside of the linear opacity; this finding proves that air does not exist in the pleural cavity but collects in the intrathoracic extrapleural space. The linear opacity is composed of both the visceral and parietal pleura. Pneumomediastinum and subcutaneous emphysema are also visible. b A coronal CT image clearly depicts fascial webs (black arrowheads) in the intrathoracic extrapleural space. The mixture of the visceral and parietal pleura (black arrows) is slightly wavier than the typical visceral line in pneumothorax