Right paratracheal air cyst (tracheal diverticulum).

Paratracheal air cysts are collections of air adjacent to the trachea. These lesions are usually an incidental finding at routine chest computed tomography (CT) scan, and their frequency is probably underestimated, because almost all patients are asymptomatic.1 Differential diagnosis of paratracheal air cysts includes tracheal diverticulum, pharyngocele, laryngocele, Zenker diverticulum, apical lung hernia, blebs and bulla, and pneumomediastinum.1-4 We present here a case of chronic obstructive pulmonary disease (COPD) with incidental finding of a large tracheal diverticulum.