Of the following cystic malformations of the tracheobronchial tree, which is most likely to be asymptomatic when discovered?

b. Extralobar pulmonary sequestration

Intralobar pulmonary sequestration and cystic adenomatoid malformations typically present with either neonatal respiratory distress or infection related to inadequate clearance of secretions. Given enough time, nearly all of these lesions will become infected. Congenital lobar emphysema is characterized by air-trapping within an otherwise normal lung. This typically presents with respiratory distress which ranges from mild to life-threatening. Hemodynamic instability requiring emergency thoracotomy is occasionally present.

Extralobar sequestration is typically a mass of disorganized pulmonary parenchymal tissue within its own investing pleura and outside of the normal lung parenchyma. This does not communicate with the normal tracheobronchial tree. Infection is rare and although hemorrhage, arterial venous shunting, mediastinal compression and occasional malignancy may occur, these lesions are typically asymptomatic and indeed often discovered via prenatal ultrasound. Excision is recommended for each of these lesions, typically involving a lobectomy.