Sandifort first described tracheal bronchus in 1785.Tracheal bronchus is a rare congenital anomaly wherein an aberrant bronchus originates from trachea anywhere above the carina, but usually within 2 cm of the carina.1 It may ventilate one of the segments of right upper lobe (RUL, displaced tracheal bronchus) or an aberrant lung tissue (supernumerary tracheal bronchus). Sometimes, it may ventilate the whole RUL, when it is known as “true tracheal bronchus” or “bronchus sui” (“pig bronchus,” which is normal morphology in pigs).2 In world literature, only 1 case of lung cancer affecting true tracheal bronchus has been reported.3 We are reporting the second such case in the world and the first from India.
A 45-year-old man, with a 30-pack year smoking history, presented with a 3-month history of generalized body aches. On routine investigations, his chest skiagram showed RUL collapse. Chest computed tomography (CT) scan (Fig. 1) confirmed collapsed RUL with a tracheal bronchus opening just above the carina. The tracheal bronchus could not be traced further after its origin, where it ended up in the opacity corresponding to RUL collapse. Lytic lesions, probably metastatic, were noted in D6 and D7 vertebrae. Bronchoscopy was performed, which revealed that the intermediate bronchus was opening directly into trachea in place of right main bronchus and a tracheal bronchus (true tracheal bronchus) was seen just above the carina (Fig. 2) (Supplementary Digital Content 1, http://links.lww.com/LBR/A86). This bronchus was totally occluded by a seemingly peribronchial compression and could not be negotiated in. Bronchial brush smears and transbronchial needle aspirates were taken from this bronchus, which revealed a poorly differentiated non–small cell lung cancer. The lung cancer stage was T3N0M1. Patient was subjected to chemotherapy by paclitaxil and carboplatin along with radiotherapy (total dose of 20 Gy/5#). He was planned for further chemotherapy.
We report a case of true tracheal bronchus with non–small cell carcinoma. Tracheal bronchus is a rare anomaly in which a supernumerary bronchus arises above the carina, which generally ventilates an accessory lobe (tracheal lobe), but rarely, it may ventilate RUL directly, when it is known as “true tracheal bronchus” or “pig bronchus” (a normal morphology in pigs).1,2 Sometimes the tracheal bronchus ends up in a sac known as tracheal diverticulum.
Tracheal bronchi are generally clinically insignificant and are incidental findings. However, they may cause recurrent pneumonia, chronic atelectasis, bronchiectasis, persistent cough, hemoptysis, or lung masses.4,5 Another clinical significance of this anomaly is possibility of its accidental intubation causing pneumothorax and inadequate ventilation.5
Tracheal bronchus can be visualized on CT and can be confirmed by flexible or rigid bronchoscopy. In our patient, we found a tracheal bronchus on the CT, which was confirmed by flexible bronchoscopy. There was absence of normal RUL bronchus and the intermediate bronchus directly opened in trachea in place of right main bronchus.
Lung cancer associated with tracheal bronchus is rare. Literature shows only 10 cases of surgically resected and confirmed cases of lung cancer in tracheal bronchus. Moreover, lung cancer associated with a true tracheal bronchus has been reported in only 1 case.3 The present case is the second such case in world literature and the first from India.
The knowledge about tracheal bronchus is important for pulmonologists, thoracic surgeons, and anesthesiologists. As the incidence of this anomaly is very low, it is difficult to comment on the susceptibility of tracheal bronchus for lung cancer; however, this combination of entities should be kept in mind.
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2. Foster-Carter AF. Broncho-pulmonary abnormalities. Br J Tuberc. 1946;40:111–124
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