Congenital Pulmonary and Airway Malformations (CPAM)

Congenital pulmonary and airway malformation (CPAM) is a rare condition in which a fetus develops one or more abnormal growths of tissue (called lesions) on their lungs. CPAM can become serious if these lesions damage other vital organs, such as the heart or lungs.

Key Facts

  • CPAM lesions can be either fluid or solid-filled, and can change in size and appearance throughout a pregnancy. In most cases, they are not life-threatening.
  • CPAM lesions can sometimes shift organs in the chest. If they affect the heart, they may cause hydrops, an abnormal accumulation of fluid that may be a sign of heart failure.
  • Diagnosis can usually be made during pregnancy. If necessary, there are a variety of treatment options both before and after birth.


The causes of CPAM are currently not known. However, researchers do not believe there are any links between what a mother does or does not do during their pregnancy. It is also not a hereditary condition, meaning it usually does not recur within a family.


CPAM is classified into the following three types: 

  • Type 1: This type accounts for about two-thirds of cases. It’s characterized by a low number of large lesions. These lesions are usually found on just one lobe. In most cases, this type does not present any symptoms.
  • Type 2: This type accounts for about 15 to 20 percent of cases. It’s characterized by a high number of small lesions and is often associated with other congenital abnormalities, including those in the cardiac, skeletal, and nervous systems. Its symptoms will depend on the number and severity of the lesions.
  • Type 3: This type accounts for about 5 to 10 percent of cases. It’s characterized by a high number of large lesions, which can cause vital organs to shift in the chest. This may lead to the formation of hydrops, which is a sign of heart failure. This is the most serious type of CPAM.

In each type, CPAM causes one or more benign (noncancerous) lesions to grow on the lobes of the lungs. The following are some other possible symptoms:

  • Abnormal blood pressure
  • Acid reflux
  • Chest wall abnormalities
  • Difficulty breathing
  • Heart failure
  • Hydrops (abnormal accumulation of fluid)
  • Pulmonary hypoplasia (underdeveloped lungs)

In severe cases of CPAM, the mother can develop maternal mirror syndrome. This is when their condition mimics that of their fetus. Possible symptoms can appear similar to pre-eclampsia and may include the following:

  • High blood pressure
  • Protein in her urine
  • Pulmonary edema (fluid in lungs)
  • Swelling in hands or feet
  • Vomiting


In most cases, CPAM is detected during a routine prenatal ultrasound. Common signs include a bright mass on the chest of the fetus, displacement of the heart and/or diaphragm, and an absence of lung tissue. 

To confirm this diagnosis, doctors often use the following methods:

  • Fetal Echocardiogram: This is a type of ultrasound that measures the structure and function of the heart.
  • Magnetic Resonance Imaging (MRI): This is an imaging test that uses a magnetic field to give doctors a highly detailed view of the fetus’s chest and abdomen.


There are a variety of treatment options for CPAM. Choosing the best one depends on several factors, such as the size and number of lesions, whether they are solid or filled with fluid, and if hydrops or mirror syndrome has developed. In minor cases, no treatment may be necessary. In more severe cases, treatment can be given either before birth or after.

Before Birth (Prenatal)

The following are the most common prenatal treatment options for CPAM:

  • Steroid Treatment: Steroids often given during pregnancy, such as betamethasone, can help slow the growth of lesions, reduce their size, and prevent or reverse hydrops.
  • Thoracentesis: This minimally invasive procedure can drain large fluid-filled lesions. A needle is first inserted through the womb and into the lesions, then the fluid is drained. Surgeons may also use a shunt so that fluid can continually drain as it builds up.
  • Fetal Surgery: This procedure is used in severe cases of CPAM when steroid treatment is ineffective. It involves opening the womb (similar to a Cesarean section) and removing the lesions. Afterwards, the fetus is returned to the womb.
  • Early Delivery: If mirror syndrome is present, doctors may choose to deliver the baby early to protect the health of the mother.

After Birth

When CPAM is less severe, treatment can often be delayed until after birth. This will involve surgically removing lesions. The timing of this surgery depends on the severity of the baby’s symptoms, such as whether or not they have developed breathing problems. 

However, if a fetus has large lesions that will prevent normal breathing and make it less likely for them to survive birth, doctors may deliver them with an ex utero intrapartum treatment (EXIT). This involves delivering the baby by Cesarean, then removing any lesions while they are still connected to the placenta.


With proper treatment, the long-term prognosis for most infants with CPAM is excellent. Factors associated with better outcomes include the following:

  • Absence of hydrops
  • Less numerous and smaller lesions
  • No other abnormalities

Even when excising a lesion also means removing parts of a lung, the lung can often grow and make up for this absence. As a result, children with CPAM often don’t have limited lung function.

Without proper treatment, CPAM can result in significant health issues, including an increased risk of cancer.

Next Steps

Our Pediatric Surgery program is a leader in the diagnosis, treatment, and long-term care of CPAM. Our multidisciplinary team of surgeons and specialists can operate on unborn fetuses, provide treatment for newborns and mothers, and help identify and manage a range of ongoing complications.

Call us at (212) 342-8585 or use our online form to schedule an appointment.  

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