A study of pulmonary ligament arteries. Relationship to intralobar pulmonary sequestration.

Intralobar pulmonary sequestration (ILS) has generally been considered a congenital malformation, mainly because of the presence of one or more systemic arteries to the sequestered portion of lung. We performed a study of the pulmonary ligaments in children without congenital pulmonary or vascular disease that demonstrated systemic arteries in ten of 11 cases, with as many as five arteries present in a single case. These arteries arose from the thoracic aorta, contributed to the esophageal plexus, and traversed the pulmonary ligament to ramify in the visceral pleura. A sequence of events including bronchial obstruction, pneumonia, pulmonary artery occlusion, pleuritis, and parasitization of pulmonary ligament (or diaphragmatic) arteries leading to the "creation" of an ILS is proposed.