Congenital pulmonary airway malformation (CPAM) is an early pregnancy (8-9 week) lung developmental abnormality that affects about 1 in every 4,000 babies annually and which affects males more than females. CPAM represents a mass within the lung that is most commonly suspected during pregnancy and detected by ultrasound.

Previously known as a CCAM (congenital cystic adenomatoid malformation), congenital pulmonary airway malformation (CPAM) is typically non-cancerous, not genetic in origin (so they do not typically recur in other pregnancies), and are not associated with chromosome abnormalities (e.g. Down syndrome). CPAM masses are usually in one lung only and they may have a solid, cystic or mixed solid-cystic appearance. CPAM masses may not complicate pregnancy, but they may complicate pregnancy if they are large or very cystic.

What are the risks?

The natural history for these masses is to grow up until 28 weeks after which they plateau or stop growing. If the mass becomes a sufficient size there are multiple risks to the pregnancy, fetus and newborn. These include development of polyhydramnios (too much amniotic fluid) due to the mass compressing the esophagus of the fetus in the chest preventing the normal swallowing of amniotic fluid that is needed to maintain a normal amniotic fluid level around the fetus.

Polyhydramnios can lead to uterine contractions, preterm labor, shortening of the cervix, rupture of membranes and preterm birth. In cases where these become symptomatic, a procedure called amnioreduction can be performed to reduce the amniotic fluid volume around the fetus.
Another pregnancy complication that can occur with a large CPAM is “fetal hydrops” which appears on fetal ultrasound as fluid accumulations in the chest, around the heart, in the abdomen and/or the skin. This hydrops reflects a problem with blood flow through the heart and/or heart function due to compression by the CPAM mass. Hydrops can be associated with development of maternal preeclampsia or Mirror syndrome, which may lead to the recommendation of a very early or even previable delivery for maternal health.

Treatment Options

Delivery of the baby is usually straightforward, occurs at 39 weeks if all has remained stable, and cesarean delivery is reserved for the usual obstetrical indications (e.g. breech presentation, failure to progress and fetal heart rate abnormalities). Babies with CPAM masses usually delivery vaginally and without problems. The newborn with a CPAM, especially the cystic type of CPAM, runs a real and significant risk of “air trapping” involving the breathing of air for the first time by the newborn baby and the trapping of air in the cystic structures of the CPAM that lead to expansion of the cysts, occasional lung collapse (pneumothorax) and respiratory distress of the newborn. These masses can also become infected with risk for pneumonia as the child grows and a small percentage of these tumors can become cancerous later in life. For these reasons, a CT scan and removal by a pediatric surgeon and their team is recommended around 3 months of age.

Of note, CPAM masses are not the only masses that can occur in the chest of a fetus and a detailed ultrasound by a maternal-fetal medicine specialist and in most cases a fetal MRI can help discern the type of mass that is suspected. Regardless of the type of mass, which is not completely known until removal and pathologic evaluation, pregnancies are treated and followed in similar fashion by frequent ultrasounds.

If the mass is small, delivery can occur at the patient’s primary delivery hospital with their primary OB provider. If the mass is large or cystic, delivery should be at a fetal and newborn care center and at a high-level hospital with extensive experience in fetal lung mass where there is the ability to do fetal procedures if necessary and the ability to provide more advance respiratory resuscitation and ventilation techniques.

*diagnostic information provided courtesy of our partners at Colorado Fetal Care Center

The Fetal Health Foundation is a parent-founded non profit helping families experiencing a fetal syndrome diagnosis.

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