Extralobar pulmonary sequestration with an unusual venous drainage to the portal vein: preoperative diagnosis and excision by video-assisted thoracoscopy.

Pulmonary sequestration is an uncommon congenital malformation of the lung that can be classified as intralobar or extralobar (ELS). Approximately 90% of ELS occur in the left hemithorax. Approximately 10% of ELS may present below the diaphragm. Both types of sequestrations are characterized by pulmonary tissue that does not communicate with the bronchial tree. The arterial blood supply to 80% ELS is through a direct branch of the thoracic or abdominal aorta, in 15% via another systemic artery and 5% from the pulmonary artery. The venous drainage of ELS is variable, predominantly into the systemic circulation (via the azygos vein, hemiazygos vein, or inferior vena cava). Approximately 25% drain completely or partially through the pulmonary veins. We report an extremely rare case of ELS with unusual venous drainage to the portal vein.