paratracheal air cyst

Computertomographie
eines Trachealdivertikel an typischer Stelle rechts hinter der Trachea auf Höhe der oberen Thoraxapertur. Links axial, rechts schräg parasagittal. Man erkennt fein die Verbindung zur Trachea.
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Tracheozele
in der Computertomographie. Typische Lage nach rechts dorsal neben den Ösophagus (ebenfalls mit etwas Luft, was normal ist). Patient mit ausgeprägtem Emphysem bei COPD. Zufallsbefund.
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Trachealdivertikel
an typischer Stelle rechts dorsal auf Höhe der oberen Thoraxapertur
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Trachealdivertikel
an typischer Stelle mit nur als kleine Ausziehung sichtbarer Verbindung zum Tracheallumen. Daneben der normale Ösophagus.
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Imaging of
congenital lung diseases presenting in the adulthood: a pictorial review. Tracheal diverticula in a 61-year-old woman presenting with dyspnea. Axial (a) and coronal (b) CT images demonstrate a giant right-sided paratracheal cyst
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Paratracheal air cysts are not an uncommon incidental finding in routine thoracic imaging. They characteristically occur on the right side, in the region of the thoracic outlet.  Occasionally it may mimic pneumomediastinum, so-called pseudopneumomediastinum.

Terminology

Paratracheal air cysts encompass a number of entities including :

There is overlap in the use and description of the terms paratracheal air cyst and tracheal diverticulum in the literature that they often seem to be synonyms for the same entity .

Epidemiology 

They are present in 3-4% of the population. They may be seen in children and adults with an increased female predilection .

Pathology 

Their exact cause is unclear and may be either congenital or an acquired phenomenon. The acquired form is thought to be due to prolonged increased intraluminal pressure, e.g. due to a chronic cough, COPD.

The cysts may be unilocular or multilocular and do not communicate the trachea. A direct connection with the trachea is visible on CT in ~35% of cases , and the term tracheal diverticulum may be used.

Location

Paratracheal air cysts project posteriorly where the cartilage rings are deficient and usually lies to the right where there is no esophagus supporting the paratracheal tissue. They usually occur at the level of the thoracic inlet.

Associations

Radiographic features

CT

Typically located on the right side at the level of the thoracic inlet. Most measure 3-10 mm and are elongated in shape .

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.

Differential diagnosis

Imaging differential considerations include:

Complications

Although usually asymptomatic, it may accumulate respiratory secretions that become infected and lead to coughing or tracheobronchitis.

See also

Siehe auch:
und weiter:
Assoziationen und Differentialdiagnosen zu para-tracheal air cyst:
Bronchialdivertikel
 
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