Congenital cystic adenomatoid malformation (CCAM) is a mass of abnormal cysts (bubble balls) lined by proliferating bronchial or cuboidal epithelium with intervening normal portions of lung.
About 25% of affected infants are stillbirths. 20% may have associated congenital abnormalities. Of the heart lesions, CCAM is most commonly associated with Tetralogy of Fallot (with cyanosis – bluish discolouration).
Of CCAMs diagnosed antenatally, up to 40% may show regression in size of the cysts as the pregnancy progresses.
It is understood that CCAM occurs when there is failure of interaction between endoderm and mesoderm (primary tissue layers) leading to an imbalance with increased cell proliferation and reduced cell death. This leads to abnormal development of the lung. It is also suggested that CCAM may include sequestration, bronchial atresia and lobar emphysema.
CCAMs present in 3 main ways: