Answer:
Tracheal bronchus ( bronchus suis)
Findings:
Imaging reveals a tracheal bronchus that aerates apical segment of right upper lobe. One can see focal areas of bronchiectatis and fibrotic parenchymal bands in right upper lobe. Note is made of the presence of azygos fissure, which is an associated feature in subset of this condition.
Discussion:
Tracheal bronchi are common anomalies, present in about 0.1% of the population. A tracheal bronchus usually arises from the right tracheal wall, at or within 2 cm of the tracheal bifurcation. It supplies a variable portion of the medial or apical right upper lobe, most often the apical segment.
The anomalous bronchus can arise anywhere from the carina to the cricoid cartilage, but most frequently within 2 cm of the carina.
Tracheal bronchi are classified as being either “displaced” or “supernumerary.”
A displaced bronchus is an anomalous cephalad location of the right upper lobe bronchus or any of its segments, most commonly the apical. If the entire right upper lobe takes off from the trachea the right main bronchus is the bronchus intermedius, feeding the right middle and lower lobes, and the malformation is called “true tracheal bronchus” or “bronchus sui” (“pig bronchus,” because that is the normal morphology in pigs).
If the anomalous bronchus is the take-off of the apical segment of the right upper lobe,the right main bronchus will be normal looking,but the right upper lobe will not have its trifurcation. Instead there will be a bifurcation, corresponding to the anterior and posterior segments. That variant is called “apical tracheal bronchus,” which has been described in patients who have an azygos lobe. In that situation the apical segment will have its own displaced bronchus and its own pleural investment.
Supernumerary bronchus is less common than displaced bronchus and can coexist with normal right upper-lobe branching. Supernumerary tracheal bronchus aerates either normal lung parenchyma, a cyst, (rarely) ends in a blind pouch, called a “trachea diverticulum.”
The majority of patients with tracheal bronchi are asymptomatic and do not require any medical intervention. In the case of recurrent pneumonia complicated by bronchiectasis surgical resection of the anomalous lobe or segment is the treatment of choice.
With adults the main implication of a tracheal bronchus is during endotracheal intubation: an endotracheal tube can occlude the lumen of the tracheal bronchus, resulting in atelectasis of the involved lobe or segment, post-obstructive pneumonia, or even respiratory failure.
References:
Tracheal Bronchus - Respiratory Care • September 2004 Vol 49 No 9-Naim Y Aoun MD, Eduardo Velez MD, Lawrence A Kenney MD, and Edwin E Trayner MD
Contributed By:
Dr. Karunakaran M. Kalathi MD, Dr. Arun Chelladurai MD
Consultant Radiologists, Aarthi Scans, Thirunelveli, Tamilnadu, India
Tracheal bronchus ( bronchus suis)
Findings:
Imaging reveals a tracheal bronchus that aerates apical segment of right upper lobe. One can see focal areas of bronchiectatis and fibrotic parenchymal bands in right upper lobe. Note is made of the presence of azygos fissure, which is an associated feature in subset of this condition.
Discussion:
Tracheal bronchi are common anomalies, present in about 0.1% of the population. A tracheal bronchus usually arises from the right tracheal wall, at or within 2 cm of the tracheal bifurcation. It supplies a variable portion of the medial or apical right upper lobe, most often the apical segment.
The anomalous bronchus can arise anywhere from the carina to the cricoid cartilage, but most frequently within 2 cm of the carina.
Tracheal bronchi are classified as being either “displaced” or “supernumerary.”
A displaced bronchus is an anomalous cephalad location of the right upper lobe bronchus or any of its segments, most commonly the apical. If the entire right upper lobe takes off from the trachea the right main bronchus is the bronchus intermedius, feeding the right middle and lower lobes, and the malformation is called “true tracheal bronchus” or “bronchus sui” (“pig bronchus,” because that is the normal morphology in pigs).
If the anomalous bronchus is the take-off of the apical segment of the right upper lobe,the right main bronchus will be normal looking,but the right upper lobe will not have its trifurcation. Instead there will be a bifurcation, corresponding to the anterior and posterior segments. That variant is called “apical tracheal bronchus,” which has been described in patients who have an azygos lobe. In that situation the apical segment will have its own displaced bronchus and its own pleural investment.
Supernumerary bronchus is less common than displaced bronchus and can coexist with normal right upper-lobe branching. Supernumerary tracheal bronchus aerates either normal lung parenchyma, a cyst, (rarely) ends in a blind pouch, called a “trachea diverticulum.”
The majority of patients with tracheal bronchi are asymptomatic and do not require any medical intervention. In the case of recurrent pneumonia complicated by bronchiectasis surgical resection of the anomalous lobe or segment is the treatment of choice.
With adults the main implication of a tracheal bronchus is during endotracheal intubation: an endotracheal tube can occlude the lumen of the tracheal bronchus, resulting in atelectasis of the involved lobe or segment, post-obstructive pneumonia, or even respiratory failure.
References:
Tracheal Bronchus - Respiratory Care • September 2004 Vol 49 No 9-Naim Y Aoun MD, Eduardo Velez MD, Lawrence A Kenney MD, and Edwin E Trayner MD
Contributed By:
Dr. Karunakaran M. Kalathi MD, Dr. Arun Chelladurai MD
Consultant Radiologists, Aarthi Scans, Thirunelveli, Tamilnadu, India