CPAM on chest radiograph in a newborn. Large cystic changes in the left lung, leading to a mediastinal shift to the right due to their mass effect. CPAMs are often identified during routine prenatal ultrasonography. Identifying characteristics on the sonogram include: an echogenic (bright) mass appearing in the chest of the fetus, displacement of the heart from its normal position, a flat or everted (pushed downward) diaphragm, or the absence of visible lung tissue. CPAMs are classified into three different types based largely on their gross appearance. Type I has a large (>2 cm) multiloculated cysts. Type II has smaller uniform cysts. Type III is not grossly cystic, referred to as the "adenomatoid" type. Microscopically, the lesions are not true cysts, but communicate with the surrounding parenchyma. Some lesions have an abnormal connection to a blood vessel from an aorta and are referred to as "hybrid lesions." Imaging<unk>  in a fetus, ultrasound at 19 weeks -sagittal. Stomach top right of image, heart displaced to bottom left of image (anatomically on the right side of fetus.)<unk>  in a fetus, ultrasound at 19 weeks - transverse. Stomach on left image; heart on right image: displaced to right by cystic mass The earliest point at which a CPAM can be detected is by prenatal ultrasound. The classic description is of an echogenic lung mass that gradually disappears over subsequent ultrasounds. The disappearance is due to the<unk>  becoming filled with fluid over the course of the gestation, allowing the ultrasound waves to penetrate it more easily and rendering it invisible on sonographic imaging. When a CPAM is rapidly growing, either solid or with a dominant cyst, they have a higher incidence of developing venous outflow obstruction, cardiac failure and ultimately hydrops fetalis. If hydrops is not present, the fetus has a 95% chance of survival. When hydrops is present, risk of fetal demise is much greater without in utero surgery to correct the pathophysiology. The greatest period of growth is during the end of the second trimester, between 20–26 weeks. A measure of mass volume divided by head circumference, termed cystic adenomatoid<unk>  volume ratio (CVR) has been developed to predict the risk of hydrops. The lung mass volume is determined using the formula (length × width × anteroposterior diameter ÷ 2), divided by head circumference. With a CVR greater than 1.6 being considered high risk. Fetuses with a CVR less than 1.6 and without a dominant cyst have less than a 3% risk of hydrops. After delivery, if the patient is symptomatic, resection is mandated. If the infant is asymptomatic, the need for resection is a subject of debate, though it is usually recommended. Development of recurrent infections, rhabdomyosarcoma, adenocarcinomas in situ within the lung<unk>  have been reported.
Congenital pulmonary airway malformation
Asphyxiating thoracic dysplasia
Tracheal agenesis
Anomalous pulmonary venous connection
Surfactant metabolism dysfunction
Congenital diaphragmatic hernia
Pulmonary hypoplasia
Patulous Eustachian tube