The fallen lung sign (also known as CT fallen lung sign) describes the appearance of collapsed lung away from the mediastinum encountered with tracheobronchial injury (in particular those > 2 cm away from the carina). It is helpful to look for this rare but specific sign, in cases of unexplained persistant pneumothorax. It can be seen both on plain films and CT.
The sign was first described in a 1970 case report 2 as the lung falling away from the mediastinum when the bronchus is completely transected, and the vascular structures of the hilum remain intact.
- 1. Tack D, Defrance P, Delcour C et-al. The CT fallen-lung sign. Eur Radiol. 2000;10 (5): 719-21. doi:10.1007/s003300050992 - Pubmed citation
- 2. Kumpe DA, Oh KS, Wyman SM. A characteristic pulmonary finding in unilateral complete bronchial transection. Am J Roentgenol Radium Ther Nucl Med. 1971;110 (4): 704-6. Pubmed citation