Coexistence of two anatomical bronchial variances.

1 of 3 DESCRIPTION A 70-year-old man with mediastinal lymphadenopathy was referred to our centre for endobronchial ultrasound with transbronchial needle aspiration. During the bronchoscopic examination, two separate anatomical bronchial variances were observed: a supernumerary ‘true’ tracheal bronchus branching off from the distal right lateral wall of the trachea ( fi gure 1A ) and a displaced aberrant ‘tracheal’ bronchus arising from the distal lateral wall of the left main stem bronchus ( fi gure 1B ). There was a normal right upper lobe bronchus but the upper division truncus of the left upper lobe bronchus was absent. CT imaging and reconstructed images of the right and left tracheal bronchi are shown in fi gure 2A,B . The term tracheal bronchus encompasses a variety of bronchial anomalies originating from the trachea or main bronchi and involving the upper lobes. These bronchi are considered supernumerary rather than displaced when they coexist with a normal type branching of the upper lobe bronchi. Anomalous bronchi are considered displaced when an aberrant bronchus is present and one branch of the upper lobe bronchus is missing. 1 Normal upper lobe bronchi originate above the pulmonary artery (eparterial) on the right and below the pulmonary artery (hyparterial) on the left side. Based on their relative locations to the pulmonary artery, anomalous bronchi arising proximal to the origin of the normal upper lobes are called preeparterial on the right and prehyparterial on the left side whereas, anomalous bronchi arising distal to the origin of the upper lobe bronchi are termed posteparterial on the right and posthyparterial on the left side 1 ( fi gure 3 ). The prevalence of tracheal bronchus ranges from 0.1% to 3% on the right and 0.3%–1% on the left. 2