Tracheal diverticula, also known as tracheoceles, are usually an incidental finding. Occasionally they may mimic pneumomediastinum, a so-called pseudopneumomediastinum.

Terminology

There is an overlap in the use and description of the terms paratracheal air cyst and a tracheal diverticulum in the literature such that they often seem to be synonyms for the same entity, which they are not ^1,5. 

Epidemiology

Associations

• chronic obstructive pulmonary disease (COPD): for acquired type ³

• tracheobronchomegaly: when multiple tracheal diverticula are present ⁵

Clinical presentation

Tracheal diverticula are typically asymptomatic but can occasionally present with chronic cough, stridor, dyspnoea, or recurrent infection ⁵. 

Pathology

Tracheal diverticula can be ⁵:

• congenital

• acquired

  • prolonged increased intraluminal pressure, e.g. chronic cough, COPD

  • tracheomalacia

  • iatrogenic, e.g. post-surgical

Location

A tracheal diverticulum projects posteriorly where the cartilage rings of the trachea are deficient and usually lies to the right where there is no oesophagus supporting the paratracheal tissue ⁶. The vast majority (97%) are located at the right posterolateral aspect of the trachea, approximately at the level of the thoracic inlet ⁵. A direct connection with the trachea may not always be appreciable on CT ⁵.  

Treatment and prognosis

Although usually asymptomatic, tracheal diverticula may accumulate respiratory secretions that become infected (and potentially abscess-forming) and lead to coughing or tracheobronchitis. 

History and etymology

In 1838, Rokitansky described three cases of tracheal diverticula for the first time ⁷.

Differential diagnosis

• paratracheal air cyst

• laryngocele

• pharyngocele

• Zenker diverticulum

• apical lung herniation

• apical paraseptal blebs