Congenital Pulmonary Airway Malformation (CPAM), formerly called Congenital cystic adenomatoid malformation of lung (CCAM), is a congenital lung lesion in children as a result of an embryologic insult in early gestation (7th week of intrauterine life) causing maldevelopment of the terminal bronchiolar structures.
Incidence is 1:25,000–1:35,000 births and it represents up to 25 % of congenital lung abnormalities. There is increased cell proliferation but decreased apoptosis, resulting in adenomatoid proliferation of terminal respiratory bronchioles with intercommunicating cysts. The lesion is connected to the airway but a normal intrapulmonary bronchial system is missing. CPAM is classified on the basis of the cyst size (Type I: cysts 2–10 cm; Type II: cysts 0.5–2 cm; Type III: microcystic).
It may be diagnosed by prenatal ultrasound and can regress or increase in size. It may present ante-natally in exceptional cases (less than 1 %) as polyhydramnios or foetal
hydrops with foetal demise. At birth it may present as respiratory distress. Small CPAMs may remain asymptomatic and present later in life or are found incidentally. Associated (renal, intestinal, bony, cardiac) anomalies may be present in up to 25 % patients (usually in Type II). Except for cardiac anomalies, the other associated malformations worsen the prognosis.