[Pathogenetic left tracheal bronchus. A review of the literature in connection with four cases (author's transl)].

The so-called left "tracheal" bronchus is usually found to be a transposition of the segmental apicoposterior bronchus of the upper left lobe onto the terminal portion of the main trunk. This systematisation abnormality is less common on the left than on the right. In our experience, based on 1,500 bronchographs carried out on adults and children, we have discovered seven left "tracheal" bronchi four of them associated with an obstructive emphysema in the same area. Although this malformation is rarely encountered in the etiologies of interlobular or poly-segmental emphysemas in children, it does however appear that an upper left emphysema has two etiologies which are peculiar to it: segmental bronchial atresia and left "tracheal" bronchi. Why the left "tracheal" bronchi is more often pathogenetic in comparison with the right is open to speculation. As in many other examples of tracheo-bronchial compression for vascular reasons, the close contact between the hyperarterial ectopic bronchi and the left pulmonary artery seems, logically, to be the culprit.