It may be congenital or acquired. The acquired form is thought to be due to prolonged increased intraluminal pressure, e.g. due to a chronic cough.
It projects posteriorly where the cartilage rings are deficient and usually lies to the right where there is no oesophagus supporting the paratracheal tissue. Typically located in the right posterolateral tracheal wall about the level of the thoracic inlet. A direct connection with the trachea is often visible on CT.
- chronic obstructive pulmonary disease (COPD) 3: for acquired type
Although usually asymptomatic, it may accumulate respiratory secretions that become infected and lead to coughing or tracheobronchitis.
The differential diagnosis of a paratracheal air cyst also includes an oesophageal diverticulum and an apical bleb or bulla, e.g.
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