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 1,5.
Tracheal diverticula are typically asymptomatic but can occasionally present with chronic cough, stridor, dyspnea or recurrent infection 5.
Tracheal diverticula can be 5:
- prolonged increase intraluminal pressure, e.g. chronic cough, COPD
- iatrogenic, e.g. post-surgical
It projects posteriorly where the cartilage rings are deficient and usually lies to the right where there is no esophagus supporting the paratracheal tissue. The vast majority (97%) are located to the right posterolateral aspect of the trachea, about the level of the thoracic inlet 5. A direct connection with the trachea may not always be shown on CT 5.
- chronic obstructive pulmonary disease (COPD): for acquired type 3
- tracheobronchomegaly: when multiple tracheal diverticula are present 5
Although usually asymptomatic, it may accumulate respiratory secretions that become infected (and potentially abscess-forming) and lead to coughing or tracheobronchitis.
- 1. 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 Am J Neuroradiol. 2008;29 (6): 1218-21. doi:10.3174/ajnr.A1058 - Pubmed citation
- 2. Goo JM, Im JG, Ahn JM et-al. Right paratracheal air cysts in the thoracic inlet: clinical and radiologic significance. AJR Am J Roentgenol. 1999;173 (1): 65-70. AJR Am J Roentgenol (abstract) - Pubmed citation
- 3. Webb EM, Elicker BM, Webb WR. Using CT to diagnose nonneoplastic tracheal abnormalities: appearance of the tracheal wall. AJR Am J Roentgenol. 2000;174 (5): 1315-21. AJR Am J Roentgenol (full text) - Pubmed citation
- 4. Higuchi T, Takahashi N, Shiotani M et-al. Characteristics and CT features of subcarinal air collections/main bronchial diverticula. Eur Radiol. 2010;20 (1): 95-9. doi:10.1007/s00330-009-1526-z - Pubmed citation
- 5. Tanrivermis SA, Tanrivermis EM, Tanrivermis SD, Tanrivermis CC. The diseases of airway-tracheal diverticulum: a review of the literature. (2016) Journal of Thoracic Disease. 8 (10): E1163-E1167. doi:10.21037/jtd.2016.10.92 - Pubmed