Fluid-filled cystic adenomatoid malformation.

Two infants with congenital cystic adenomatoid malformation of the lung are described. The condition progressed from an unusual solid radiographic appearance to the more classical air-filled cystic appearance. The initial appearance is due to delayed emptying of the alveolar fluid either via the bronchi or the lymphatic and circulatory systems. After the fluid is removed, the typical air-filled cysts become apparent.