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Lung Cancer in “True Tracheal Bronchus”: A Rare Coincidence

Sindhwani, Girish MD*; Rawat, Jagdish MD*; Gupta, Meenu MD; Chandra, Smita MD

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Journal of Bronchology & Interventional Pulmonology: October 2012 - Volume 19 - Issue 4 - p 340-342
doi: 10.1097/LBR.0b013e31826ba8f2

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.

CASE REPORT

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.

FIGURE 1
FIGURE 1:
Computed tomography sections of chest showing right upper lobe collapse and a small tracheal bronchus originating just above the carina.
FIGURE 2
FIGURE 2:
Bronchoscopy view just above the carina showing intermediate bronchus opening directly into the trachea and an indentation of compressed tracheal bronchus.

DISCUSSION

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.

CONCLUSIONS

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.

REFERENCES

1. Boyden EA. The distribution of bronchi in gross anomalies of the right upper lobe, particularly lobes subdivided by azygos vein and those containing pre-eparterial bronchi. Radiology. 1952;58:797–807
2. Foster-Carter AF. Broncho-pulmonary abnormalities. Br J Tuberc. 1946;40:111–124
3. Serdar S, Ekrem S, Engin P, et al. Upper lobectomy for lung cancer with true tracheal bronchus: a unique presentation. Arch Bronconeumol. 2010;46:332–334
4. Okubo K, Ueno Y, Isobe J. Upper sleeve lobectomy for lung cancer with tracheal bronchus. J Thorac Cardiovasc Surg. 2000;120:1011–1012
5. Ho K, Ulualp SO, Swischuk L. Left tracheal bronchus in an infant with laryngeal cleft. J Bronchol Intervent Pulmonol. 2009;16:52–54
Keywords:

tracheal bronchus; bronchoscopy; lung cancer; pig bronchus

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