Keywords
ectopic bronchus - tracheal trifurcation - congenital lung disease
Introduction
“Tracheal trifurcation” with an ectopic bronchus or foregut fistula is exceedingly
rare. A “tracheal bronchus” is uniformly found within 2 cm of the carina supplying
the right upper lobe.[1] In children undergoing bronchoscopy for respiratory symptoms, an ectopic bronchus
was found in 2% of the cases.[2] These may be asymptomatic or associated with bronchiectasis, focal emphysema or
cystic lung malformations.[3] Implications at intubation, bronchoscopy, and surgery can be complex.[4]
Case Presentation
A 2-year-old girl suffered right lower lobe pneumonia. On resolution, she remained
symptomatic with a dry cough and reduced exercise tolerance. She had an antenatal
history of a right echogenic lung mass. Computed tomographic imaging at 3 months demonstrated
tracheal trifurcation at the carina with normal vascular anatomy ([Fig. 1]). Flexible bronchoscopy confirmed bronchomalacia of the ectopic bronchus ([Fig. 2]).
Fig. 1 Three-dimensional reconstruction of computed tomographic images showing the trifurcation
with an ectopic right lower lobe bronchus with a bronchomalacic portion (red arrow).
There was also a dilated bronchus (blue arrow) distal to an atretic apicoposterior
upper lobe bronchus.
Fig. 2 Image A was taken at initial bronchoscopy confirming the diagnosis of ectopic tracheal
bronchus that entered between the two main stem bronchi. Image B was taken following
recovery from pneumonia showing persistent pus containing Haemophilus influenzae.
At thoracotomy, a single artery supplied the lower lobe draining via its own inferior
pulmonary vein ([Fig. 3]). The right lower lobe was excised and histology confirmed bronchiectasis. Recovery
was uneventful and at 3-month follow-up exercise tolerance and energy levels had improved.
Fig. 3 Intraoperative photograph with the ectopic right lower lobe bronchus (white loop)
with its respective artery (red loop) and vein (blue loop).
Discussion
To our knowledge, the only previously reported case of an ectopic bronchus supplying
the right lower lobe (as opposed to the upper lobe) was associated with a sequestration.[5] A rare “bridging bronchus” crossing the mediastinum has previously been reported,
representing an origin of the right lower lobe bronchus from the left bronchial tree.[6]
The relationship between esophageal atresia and tracheal bronchus has been demonstrated
in the Adriamycin rat model, in which approximately one-fifth had a tracheal bronchus.[7] This corresponds with case reports of VACTERL children with tracheobronchial malformations[8] and highlights the need for comprehensive evaluation of the tracheobronchial tree
in esophageal atresia before repair is undertaken.[9] Although it is suspected that these malformations may carry an increased malignant
risk this has not been quantified in the literature. There have been multiple cases
of lung cancer (squamous cell carcinoma, adenocarcinoma, small cell carcinoma, and
bronchial carcinoid) associated with a tracheal bronchus, but these have generally
been in adults over 50 years of age with a history of smoking or other lung pathology.[10]
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