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Findings: Chest x-ray: Perihilar and right upper lobe infiltrates. CT: Right upper lobe bronchus originating from trachea immediately above the carina. Consolidation with air bronchograms adjacent to the accessory bronchus.

Diagnosis: Tracheal bronchus

Discussion: Tracheal bronchus is a bronchial branch arising directly from the lateral wall of the trachea at any point above the carina. (Iannaccone). This is normal in other mammals but rare in humans. While the etiology is unknown, an association between ectopic mesenchyme and the trachea has been hypothesized. Although usually asymptomatic, it can impair drainage and cause respiratory distress, recurrent infections, persistent coughing, bleeding, or stridor. Due to the paucity of clinical symptoms, presentation in childhood is unusual unless there are associated anomalies. Associated conditions include: congenital tracheal hypoplasia or stenosis causing airway obstruction, lobar emphysema, pulmonary cysts, cardiovascular anomalies, nonobstructive bronchiectasis or atelectasis.

Tracheal bronchi are classified as displaced or supernumerary. The displaced type arises in an abnormal position and supplies one or more segments of the upper lobes. This type is more common and usually involves the apices. The supernumerary type is an accessory bronchus supplying the pulmonary parenchyma to an abnormal extent (Siegel). Tracheal bronchi are almost always found on the right, originating from the lateral wall of the trachea. Diagnosis can be made by bronchoscopy, conventional tomography, computerized tomography or MRI. MRI can best delineate vascular anomalies.

References:
1. Iannaccone G, Capocaccia P, Colloridi V, Roggini M.
Double Right Tracheal Bronchus. Pediatric Radiology 13:156-158, 1983.

2. Siegel MJ, Shackelford GD, Francis RJ, McAlister WH. Tracheal Bronchus,
Radiology 130:353-355, 1979.

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