Bridging bronchus in an infant demonstrated by direct coronal computed tomography and three-dimensional rendering display.

Bridging bronchus is a rare anomaly in which the right lower lobe bronchus arises from the left main bronchus and bridges the lower mediastinum. The first reported case was diagnosed at autopsy in 1976. The second reported case was diagnosed by bronchography confirmed at autopsy in 1980. We describe a 9-month-old infant with such an anomaly. Our patient presented with cough, shortness of breath, and rhinorrhea with no fever or sputum production. The physical examination revealed only coarse breath sound and chest retraction with no other abnormalities. Chest radiography showed decreased lung volume and shifting of the mediastinum to the left. Diagnosis of this anomaly was not possible with computed tomography (CT) axial imaging. Direct coronal CT and 3D rendering with the surface-shaded display technique showed a small right upper lobe bronchus and proximal stenotic left main bronchus, with the intermediate bronchus originating from the left main bronchus and crossing the midline to enter the contralateral lung.