Unusual roentgenographic presentation of a congenital cystic malformation of the lung.

We describe here an infant with a large, solitary, fluid-filled lung cyst and hyperinflation of adjacent lung tissue in the same lobe. The combination of a fluid-filled cyst and ectatic emphysema in the same lobe suggests bronchial collapse and airway obstruction as a contributory mechanism for this unusual roentgenographic presentation of a congenital cystic malformation of the lung.