|Year : 2018 | Volume
| Issue : 2 | Page : 76-79
A Rare Case of a Tracheal Bronchus
Ravi A Dosi1, Arpit Jain2, Prakash Joshi2, Satish Motiwale2, Ashwin Songara2
1 Department of Respiratory Diseases, Sri Aurbindo Medical College & PGI, Indore, Madhya Pradesh, India
2 Respiratory Medicine, Sri Aurbindo Medical College & PGI, Indore, Madhya Pradesh, India
|Date of Web Publication||10-Jul-2018|
C59 Jawahar Colony, Kampoo, Lashkar, Gwalior 474001, Madhya Pradesh
Source of Support: None, Conflict of Interest: None
Here, we report a case of the right tracheal bronchus that presented with a right upper and middle lobe consolidation and a mild pleural effusion. Bronchoscopy revealed a right upper lobe bronchus arising from trachea. On a high suspicion of pulmonary Koch’s, antitubercular drug was started to which she responded well and was cured.
Keywords: Bronchoscopy, pulmonary Koch’, s, tracheal bronchus
|How to cite this article:|
Dosi RA, Jain A, Joshi P, Motiwale S, Songara A. A Rare Case of a Tracheal Bronchus. J Assoc Chest Physicians 2018;6:76-9
| Introduction|| |
A tracheal bronchus (also known as a pig bronchus) is a rare anatomical variant, where an accessory bronchus originates directly from the supracarinal trachea. The term pig bronchus or bronchus suis is often a misnomer because it is a normal finding in sheep, swine, cattle, camels, goats, and giraffes, but it is a rare and usually incidental finding in humans. The term pig bronchus is used when the entire upper lobe is supplied by the separate bronchus. It originates more commonly from the right wall of the trachea, above the carina. Its incidence is estimated to be around 1% (range 0.1–2%).,
| Case Report|| |
A 19-year-old young female presented to us with chief complaints of low-grade fever and cough with expectoration for 2 months with acute chest pain on the right side. The vitals were as follows: her resting pulse rate was 102/min, blood pressure 112/74 mmHg, and respiratory rate 26/min thoracoabdomen, with saturation 97% on room air. The general examination was normal. Her respiratory system examination revealed coarse crepitations in the right infraclavicular area and infrascapular area, and the chest X-ray revealed heterogeneous infiltrates and consolidation on the right lung with mild pleural effusion [[Figure 1]a].
|Figure 1: (a) Patient presented with right whole lung consolidation and minimum pleural effusion. (b) Chest X-ray after the completion of treatment: consolidation gets resolved|
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Her blood examination showed normal hemogram. The result of her tuberculin skin test with 5 TU was positive, and the size of induration was 20 × 20 mm. Her morning sputum was negative for acid-fast bacilli (AFB) on three consecutive days. For further evaluation, bronchoscopy and contrast-enhanced computed topography were performed.
Bronchoscopy revealed a right upper lobe (RUL) bronchus arising from the trachea with inflamed mucosa and retained hemorrhagic secretion from it [Figure 2]. Broncho alveolar lavage (BAL) was negative for AFB and brush biopsy performed was suggestive of inflammatory pathology.
|Figure 2: Bronchoscopic view of tracheal bronchus. LMB = left main bronchus, RMB = right main bronchus, TB = tracheal bronchus approximately 2 cm above the main carina|
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Contrast-enhanced computed tomography of the chest suggests mild nodular pleural thickening on the right side with decreased volume of the right lung and subsegmental collapse and consolidation in the right upper and middle lobe with mediastinal lymphadenopathy, with the RUL bronchus originating from the trachea [[Figure 3]a and [Figure 3]b].
|Figure 3: (a) CECT chest showing the origin of tracheal bronchus with volume loss of the right lung and mild pleural effusion. (b) Supernumerary type of tracheal bronchus approximately 2 cm above the main carina|
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There are multiple, enlarged lymph nodes in the pretracheal, paratracheal, precarinal, and subcarinal regions. Few lymph nodes are showing peripheral enhancement, thus suggesting necrosis.
With all investigation and clinical correlation, the diagnosis of pulmonary tuberculosis was made and the patient was started on HRZEQ consisting of isoniazid (300 mg), rifampin (600 mg), pyrazinamide (25 mg/kg), and ethambutol (15 mg/kg) levofloxocin 750 mg, to which she responded well and improved clinically and radiologically [[Figure 1]b].
| Discussion|| |
Normal tracheobronchial development is initiated at 24–26 days as a median bulge of the ventral wall of the pharynx that develops at the caudal end of the laryngotracheal groove. At 26–28 days, this bulge gives rise to the right and left lung buds. As the lung buds elongate, the trachea is separated from the esophagus by lateral in growth of the mesoderm, forming the tracheoesophageal septum. At 28–30 days, the lung buds elongate into primary bronchi; at 30–32 days, the five lobar bronchi appear as a monopodial outgrowth of the primary bronchi. All segmental bronchi are formed by 36 days. Three main embryogenic hypotheses have been formulated to explain the anomalous bronchi: the reduction, migration, and selection theories., Because of the embryogenic abnormality, the major bronchial abnormalities include the accessory cardiac bronchus (ACB) and the tracheal bronchus.
An ACB was defined by Brock in 1946 as a “supernumerary bronchus arising from the inner wall of the right main bronchus or intermediate bronchus opposite to the origin of the right upper lobe bronchus.” The bronchus progresses conically for 1–5 cm in a caudal direction toward the pericardium, paralleling the intermediate bronchus. Its prevalence is 0.3% (range 0.09–0.5%). It is lined by the normal bronchial mucosa and has cartilage within its wall, which distinguishes it from a diverticulum or acquired fistula. All ACBs are mostly asymptomatic and incidentally discovered, but cough or hemoptysis can result from superinfection, aspergilloma, or tumor.,,,
Modified nomenclature from Boyden and Kubik and Müntener is now used for the classification of aberrant bronchi with a reported prevalence of 0.1–2% in general population., The normal RUL bronchus is described as eparterial, because it arises above the right pulmonary artery. The normal left upper lobe bronchus is described as hyparterial, because it arises below the left pulmonary artery. An anomalous bronchus arising proximal to the origin of the upper lobe bronchus is called pre-eparterial on the right side and eparterial or prehyparterial on the left side. An anomalous bronchus arising distal to the origin of the upper lobe bronchus is called posteparterial on the right side and posthyparterial on the left side.
The tracheal bronchus is an aberrant, accessory, or ectopic bronchial branching, which originates from the right lateral wall of the trachea. It occurs as a result of an additional tracheal outgrowth early in the embryonic life, with an incidence which ranges from 0.1 to 2%. The most common ones of the abnormal tracheal origins is that of the RUL bronchus usually less than 2 cm above the carina, also referred to as bronchus suis with a prevalence of 0.1% in adults and 2% in children. An aberrant RUL bronchus arising from the trachea (tracheal bronchus) can be responsible for recurrent pneumonia in children.
The tracheal bronchus was initially described by Sandisfort in 1785. It is more common in males. The term tracheal bronchus is used to designate any bronchus which originates from the trachea above the level of the main carina. It is also called as Pig’s bronchus. This anomaly usually is diagnosed incidentally during bronchoscopy or bronchography performed for various respiratory problems. It can develop from any point above the main carina, but it occurs usually within the 2 cm range. The tracheal bronchus is mostly asymptomatic, but it may be associated with recurrent pneumonia, chronic bronchitis, bronchiectasis, and focal emphysematous change and pathologically classified into two types:
- Supernumerary: usual bronchial supply to the affected lung segment is concurrently present (when normal branching of the upper lobe is present). It is less common than the displaced type. It occurs early in the development, at about 29–30 days of the embryonic life, as the lobar bronchi start to differentiate.
- Displaced: usual bronchial supply to the affected lung segment is concurrently absent (when one branch of the upper lobe bronchus is missing). It is relatively more common than supernumerary type. Displaced bronchi are more likely to occur after 32 days of the embryonic life, as the bronchi elongate and branch further.
As in our case, it was the supernumerary bronchus that was present and it was coexisting with the normal RUL branching.
It can also be associated with other congenital anomalies such as Down’s syndrome, laryngeal web, rib and vertebral anomalies, tracheal stenosis, congenital heart disease, azygos lobe, partial anomalous pulmonary venous return, and displaced segmental arteries.
In patients with recurrent RUL disease and a tracheal bronchus, the surgical resection of the aberrant bronchus as well as the lobe it supplies is the treatment of choice.
| Conclusion|| |
This aberrant bronchus can be the reason for the multilobar involvement in an immunocompetent individual. Bronchoscopy has its importance when radiology and sputum microscopy do not point to a definite diagnosis. The value of bronchoscopy should not be underestimated.
It is important to identify the tracheal bronchus in the patients undergoing cardiac surgery with one lung ventilation, because serious hypoxia and atelectasis may occur if not diagnosed preoperatively.
Intubation is mostly difficult in these patients, so the diagnosis has its importance.
The tracheal bronchus can be responsible for recurrent pneumonia and morbidity in childhood.
Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3]