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Paratracheal Air Cysts

General Considerations

  • Benign incidental finding on CT (rarely seen on chest radiographs)
  • 2.0% to 3.7% of the population
  • Most are probably tracheal diverticulum
    • On imaging, 35% have a narrow stalk to the trachea
    • Histology shows ciliated columnar epithelium

Clinical Findings

  • None
  • Not associated with either trauma or emphysema

Imaging Findings

  • Always located on the right posterior trachea at the level of the thoracic inlet (~T2)
  • Unilocular or multilocular air-filled cystic structures
  • 2-20 mm in diameter on axial plane
  • Frequently associated with contour abnormality of trachea
  • May or may not see connection to trachea

Differential Diagnosis

  • Herniated lung
    • Remains in continuity with the lung
  • Emphysematous blebs
  • Laryngocele
  • Mounier-Kuhn Syndrome
    • Also has tracheomegaly and bronchiectasis
  • Pneumomediastinum
    • Air usually encircles trachea


  • None required 

paratracheal air cyst

paratracheal air cyst

Paratracheal Air Cysts. Axial CT: There is a small pocket of air (blue and green arrows) located to the right and slightly posterolateral to the trachea (T) at the levels of C7-T2. Sagittal reconstruction: Multi located collections of air (red arrow) communicate with the posterior aspect of the trachea (T) by a thin stalk (yellow arrow).
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Buterbaugh JE, Erly WK. Paratracheal air cysts: a common finding on routine CT examinations of the cervical spine and neck that may mimic pneumomediastinum in patients with traumatic injuries. AJNR. 2008 Jun;29(6):1218-21


Goo JM, Im JG, Ahn JM, Moon WK, Chung JW, Park JH, Seo JB, Han MC. Right paratracheal air cysts in the thoracic inlet: clinical and radiologic significance. AJR. 1999 Jul;173(1):65-70