Citation, DOI & article data
A tracheal bronchus (with some variations also known as a pig bronchus) is an anatomical variant where an accessory bronchus originates directly from the supracarinal trachea. The latter term (pig bronchus or bronchus suis) is often given when the entire upper lobe (usually right side) is supplied by this bronchus 5.
However, this term is used in some literature to encompass a wider spectrum of abnormalities including accessory bronchi originating from either the trachea or main bronchi.
Incidence is estimated at ~1% (range 0.1-2%), and there is a marked right sided predilection 1-2,5.
Often incidentally discovered and most patients are asymptomatic. Occasionally patients may have a recurrent (right) upper lobe pneumonia due to focal emphysematous change.
Tracheal bronchi arise from the right lateral wall of the trachea usually at a distance of <2 cm from the level of the carina 5.
They can be classified into two main types:
- supernumerary: usual bronchial supply to affected lung segment is concurrently present
- displaced: usual bronchial supply to affected lung segment is concurrently absent
CT is the best modality for assessing the anatomy and allows direct visualisation and orientation of the anomalous bronchus. Coronal multi-planar reconstructions in "lung window" settings are the most helpful and is best in depicting this anomaly.
History and etymology
It was initially described by Sandifort in 1785 2.
- 1. Shih FC, Lee WJ, Lin HJ. Tracheal bronchus. CMAJ. 2009;180 (7): 783. doi:10.1503/cmaj.080280 - Free text at pubmed - Pubmed citation
- 2. Ghaye B, Szapiro D, Fanchamps JM et-al. Congenital bronchial abnormalities revisited. Radiographics. 21 (1): 105-19. Radiographics (full text) - Pubmed citation
- 3. Harris JH. Clinical significance of tracheal bronchus. AJR Am J Roentgenol. 1983;141 (3): 623. AJR Am J Roentgenol (citation) - Pubmed citation
- 4. Gower WA, Mcgrath-morrow SA, Macdonald KD et-al. Tracheal bronchus in a 6-month-old infant identified by CT with three-dimensional airway reconstruction. Thorax. 2008;63 (1): 93-4. doi:10.1136/thx.2006.071100 - Pubmed citation
- 5. Müller NL, Silva CI. Imaging of the chest. (2008) ISBN:141604048X. Read it at Google Books - Find it at Amazon
- 6. https://onlinelibrary.wiley.com/doi/pdf/10.1111/1754-9485.21_12785