Paratracheal air cysts are not uncommon in routine thoracic imaging. They characteristically occur on the right side, in the region of the thoracic outlet.
They are present in approximately 3-4% of the population. They may be seen in children and adults with an increased female predilection 4.
They are thought to be a form of tracheal diverticulum. Their exact cause is unclear and may be either congenital or an acquired phenomenon. The cysts may be unilocular or multilocular and are often seen to communicate with the trachea.
Typically located on the right side at the level of the thoracic inlet. Most measure ~3-10 mm and are elongated in shape 5. Direct communication with the trachea may be in seen approximately one-third of cases.
Treatment and prognosis
These are an incidental finding and no treatment is required. The biggest point is to not mistake them for something more sinister.
Imaging differential considerations include:
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