Congenital cystic adenomatoid malformation of the lung in adults.

Congenital cystic adenomatoid malformation of the lung presents mainly in neonates, is rare in children beyond infancy, and has not been reported in adults. Two adult males (aged 24 and 35) had congenital cystic adenomatoid malformation of the right and left lower lobes respectively. A third case, that of a 7-year-old girl, provided the link between the typical neonatal and these adult cases. All three lesions consisted of single or multiple macroscopic cysts, as well as a network of interconnecting spaces (the adenomatoid component). The lining varied from pseudostratified columnar ciliated, to simple mucinous and cuboidal epithelium. Abundant smooth muscle was present in two cases. Cartilage was absent in all three cases. The absence of inflammation is typical of the lesion in neonates. By contrast, all three of our patients had clinical and pathologic evidence of chronic inflammation. We postulate that congenital cystic adenomatoid malformation, when confined to a lobe or segment, may be clinically silent in infancy and may present as pneumonia associated with a cystic lesion on chest x-ray in childhood or later life.