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The Tracheal Bronchus: A Malformation Far from being Anecdotal

1Service de pneumologie et d’allergologie pédiatrique-CRCM, HoÌ‚pital Robert-Debré, France
2Unité de pneumologie et Allergologie Infantile, CHU Estaing, Clermont-Ferrand, France
3UFR de médecine et des professions paramédicales, université Clermont-Auvergne, France

We report four observations of tracheal bronchus in children which illustrate the variants of these anomalies which can sometimes have long-term consequences.
 

Case 1: This is a 6 months old infant with CDG syndrome and being examined for unexplained coughing episodes. Bronchoscopy identifies a tracheal bronchus that begins near the carina and ends in a cul de sac (Figure 1A).
 

Case 2: This 3-year-old boy is referred to the pulmonology consultation for two episodes of pneumonia 6 months apart associated with a chronic cough. Endoscopy shows the birth of a tracheal bronchus just above the carina which results in two segments (Figure 1B,C).
Case 3: This 9-month-old girl with no specific history presented with two laryngitis and episodes of spastic cough. Bronchoscopy finds a lateral orifice at a distance from the carina giving rise to a bronchial orifice (Figure 1D,E).

 

Case 4: This 7-year-old girl presents with a polymalformative syndrome associating a delay in acquisitions, congenital heart disease (atrioventricular duct) and recurrent respiratory infections. In addition to the existence of a tracheal stenosis (Figure 2A,B), the endoscopy shows an atypia of bronchial distribution with a bronchial division halfway up the trachea (Figure 2C), below a pseudo-carina (Figure 2D) and a provision on the right with an intermediate bronchus, a middle lobe and superior lobe orifice (Figure 2E). This malformation is better known under the name of “bridging bronchus”.
 

The tracheal bronchus are malformations found in 2 to 5% of people [1-3]. Their classification, known since 1955 [4], has recently been modified with the help of the tomodensitometric examination [3]. There are four different anatomic types: (I) the most common is the displaced bronchus in which one or two of the upper lobe segments are aerated by the tracheal bronchus; (II) a supernumerary accessory bronchus which arises from the right lateral tracheal wall in addition to the normal right upper lobe bronchi; (III) a right upper lobe bronchus with three normal bronchial segments that arises above the carina and (IV) a rudimentary tracheal bronchus presenting as a blind out pouching from the right lateral tracheal wall. The notion of a bridge bronchus (BB) is more recent and sometimes mistakenly recognized for a classic tracheal bronchus [5,6]. The BB represents an aberrant bronchus that originates from the left main stem bronchus, crossing (‘‘bridging’’) the mediastinum to supply the right medium and/or lower lobes. It originates from a pseudocarina at a lower level than the normal right main stem bronchus which arises at the level of a normal bifurcation.

Usually these malformations are discovered by chance during an endoscopy performed for various reasons. In the observations we have reported, chronic cough was an indication as was the occurrence of recurrent pneumonia. Most of the time these malformations are well tolerated. However, they can be complicated by recurrent pulmonary infections, especially if the opening of bronchial division emerging from the trachea has a reduced caliber. A few cases of cancerization have also been described [7]. It is with general anesthesia with intubation that they can be dangerous. A bronchus abnormally originating directly from the trachea is exposed to additional risks during tracheal intubation, such as lobar or segmental atelectasis due to luminal occlusion by the tube or respiratory failure due to inadvertent intubation of the tracheal bronchus. In thoracic surgery with selective exclusion of a lung, it is therefore essential to use endoscopic intubation in patients with this anomaly [8].

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