Pulmonary Sequestration

Pulmonary sequestration is a congenital malformation in which a portion of lung tissue has no normal communication with the tracheobronchial tree and receives its blood supply from an anomalous systemic artery. The tissue is therefore isolated from normal airway clearance, while its systemic arterial supply exposes it to higher pressure than ordinary pulmonary circulation. That combination explains the clinical pattern. Poor drainage allows secretions and infection to recur in the same area. The high-pressure feeding artery creates a risk for hemoptysis, which may become life-threatening if the vessel ruptures. Two anatomic patterns are described. Intralobar sequestration lies within the pleural covering of an existing lobe and more often presents later with repeated focal pneumonia. Extralobar sequestration has its own pleural covering and is more often identified in infancy; associated congenital abnormalities may be present. The distinction helps anticipate age and presentation, but the decisive diagnostic issue is the anomalous systemic arterial supply.