Anomalous left pulmonary artery without sling formation.

A case of aberrant left pulmonary artery originating from the right pulmonary artery resembling pulmonary artery sling malformation, but without true sling formation, is presented. Anomalous left pulmonary artery was accompanied with long-segment proximal tracheal stenosis and other congenital malformations typically associated with PAS complex. The anomalous pulmonary artery passed anterior to the trachea; therefore, no true sling was formed. Because no airway compression by the aberrant left pulmonary artery was detected, the proximal tracheal stenosis was thought to be primary.