Tracheal bronchus.

Tracheal bronchus is an aberrant bronchus that arises most often from the right tracheal wall above the carina and is the result of an additional tracheal outgrowth early in embryonic life. Its incidence ranges between 0.1 and 5%. This anomaly usually is diagnosed incidentally during bronchoscopy or bronchography performed for various respiratory problems. Occasionally, it represents the underlying etiology for chronic pulmonary disease such as emphysema, atelectasis, and persistent or recurrent pneumonia, especially if it involves the right upper lobe and reflects an abnormal pulmonary clearing mechanism. Tracheal bronchus may be associated with other bronchopulmonary anomalies, tracheal stenosis, or Down's syndrome. In the absence of clinical symptoms, a diagnosis of tracheal bronchus does not require any treatment. In patients with recurrent right upper lobe disease and a tracheal bronchus, therapy should include resection of the aberrant bronchus as well as the lobe it supplies.