Lung cancer in "true tracheal bronchus": a rare coincidence.

Tracheal bronchus is a rare congenital anomaly (incidence ranging from 0.1% to 2%) of bronchial tree in which an aberrant bronchus originates in trachea anywhere above carina, but usually within 2 cm of carina. Cancer within the bronchial anomaly is further uncommon. A subtype of tracheal bronchus, known as "true tracheal bronchus" or "pig bronchus" is a condition in which right upper lobe (RUL) bronchus is absent and the RUL is ventilated by the aberrant tracheal bronchus. We present a case of true tracheal bronchus with malignancy of the affected RUL. To the best of our knowledge, in world literature, this is the second case of true tracheal bronchus affected by lung cancer.