Congenital pulmonary airway malformation (CPAM) is a rare congenital birth defect that includes a cystic mass of abnormal lung tissue. A cystic mass is a noncancerous tumor that is filled with fluid or other material. This condition used to be referred to as congenital cystic adenomatoid malformation, or CCAM. In CPAM, the cystic mass does not function as normal lung tissue. Males have this condition slightly more often than females.