Tracheal Diverticula.

Extraluminal paratracheal air bubbles are occasionally seen on computed tomography (CT) studies that include the thoracic inlet (ie, CT of the neck, of the cervical spine, and of the chest). In most cases, these paratracheal air bubbles are tracheal diverticula (TD), sometimes also referred to as tracheal pouch, tracheocele, and tracheogenic cyst. TD are most commonly seen at the right posterolateral aspect of the upper trachea at the level T1-T3. Because of their typical location and appearance, they are easily recognized and should not be confused with pneumomediastinum or other causes of air bubbles in the same region. This article describes the prevalence, possible pathophysiology, and associated complications of TD and illustrates the spectrum of their appearance on CT.