fallen lung sign

(redirected from Ptotic Lung Sign)
The drooping of the lung on a chest film or CT to the dependent part of chest, due to a fracture of the bronchus

fallen lung sign

The radiologic appearance of traumatic transection or rupture of the trachea or a main stem bronchus, consisting of a collapsed lung that seems to dangle from the hilum by only its vascular attachments. Pneumothorax, pneumomediastinum, and subcutaneous emphysema are sometimes seen with tracheobronchial tears.
See also: sign