The retrotracheal left pulmonary artery: A rare vascular malformation.

The retrotracheal left pulmonary artery, also known as "left pulmonary artery sling," is a rare vascular malformation in which the left pulmonary artery (LPA) arises from the posterior aspect of the right pulmonary artery (RPA) and reaches the left pulmonary hilum by passing between the trachea and the esophagus, giving rise to the appearance of a sling, hence the name "sling." This vascular anomaly can be associated with other cardiac malformations or abnormalities of the tracheobronchial tree.We present the case of a 4-month-old female infant who presented with laryngeal stridor. She underwent a chest X-ray, which was normal, but thoracic CT angiography revealed an aberrant LPA originating from RPA with a retrotracheal course. This case underscores the critical role of imaging in confirming the diagnosis and guiding patient management.