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Fetal Lung Masses

Fetal lung masses, or fetal lung lesions, are defects that develop in the lungs before a baby is born. Some masses may be related to another congenital defect, or a genetic condition, but in most cases the mass is isolated. It is unknown why a baby’s lung tissue doesn’t develop normally.

The team at the SSM Health Cardinal Glennon St. Louis Fetal Care Institute are experts in treating a range of fetal lung masses, including two of the most common types:

a graphic showing a baby with a mass near lung

Graphic shows a baby with CCAM/CCPAM. Lung tissue fills with fluid which causes a mass.

There are other rare types of lung masses that we can treat as well, including congenital lobar emphysema (CLE) and pulmonary blastoma. In babies with CLE, the lung mass forms large cysts that can compress the rest of the normal lung. Pulmonary blastoma is a very rare fetal lung cancer that prenatally presents like a CPAM. Doctors can only confirm this diagnosis after the mass is removed.

How Are Lung Masses Diagnosed And Managed During Pregnancy?

Fetal lung masses are typically detected during a routine ultrasound around 20 weeks of gestation. The mass may appear as a bright area of the lung on ultrasound.

After the initial ultrasound, our team at the Cardinal Glennon St. Louis Fetal Care Institute will perform a targeted prenatal ultrasound and, in some cases, a fetal MRI to determine the extent of the mass. During these tests, the mass is measured and inspected for blood vessels (feeding vessels), and your baby is screened for other anomalies. This gives us a complete picture of your baby.

Next, we will meet with you to review the findings from these tests and discuss the options, which may include prenatal interventions and surgery after birth. In most cases, fetal lung masses are benign and cause no symptoms, which means they do not require fetal interventions.

In the rare situation that intervention is required before birth, the Cardinal Glennon St. Louis Fetal Care Institute has the expertise to help your baby with the appropriate monitoring, treatment and intervention.

What Are the Treatments and Long-Term Effects of Lung Masses?

The vast majority of fetal masses are benign (not cancerous), but they can cause a variety of problems for a baby, even into childhood. Occasionally, these problems must be managed before birth or immediately at birth, but usually lung lesions can be managed months after birth in a safe, elective setting.

The major challenges facing a baby with a lung mass are:

Heart Problems

Both CPAM and BPS lesions can grow rapidly before birth, straining the baby’s heart and causing heart failure. Depending on the specific diagnosis, treatment options may include:

  • Medication to stop the growth of the mass
  • Draining a CPAM cyst using a special needle
  • Placing a shunt in the mass to help it continue to drain so that there is no or little re-accumulation of the fluid
  • Fetal surgery to remove the mass in rare situations

Pulmonary Hypoplasia (Small Lungs)

Sometimes the lung mass is so large it can prevent the development and normal function of the rest of the lung. If severe pulmonary hypoplasia is suspected, we may recommend a special delivery procedure called an EXIT procedure or extracorporeal membrane oxygenation (ECMO). Every lung mass is a unique situation that will require an individualized care and delivery plan.


In lung masses that are connected to the normal lung, infection can occur after birth. Bacteria can pass from the normal lung into the abnormal lung mass. Because the lung mass has abnormal airways, the bacteria and mucous cannot be cleared causing an infection. To prevent repeated infections, our pediatric surgeons often recommend removal of the mass after birth.

Lung Cancer

There are very few reports of babies having pulmonary blastoma, which is an extremely rare type of lung cancer. However, there are reports of lung cancer developing within a CPAM in early adulthood. In CPAM, the abnormally developed lung tissue may already have a genetic predisposition to form cancer. With chronic infection and inflammation, lung cancer can form. This is why many parents elect to remove the CPAM after birth, essentially preventing any chance of lung cancer development from the mass.

What Can I Expect After Surgery for a Lung Mass?

If your baby requires surgery after delivery, a stay in the Neonatal Intensive Care Unit (NICU) will be required.  Once your baby goes home, their outlook is usually good.  Most babies who have a fetal lung mass surgically removed grow into healthy children and adults.

We understand that a lung mass can be a scary diagnosis. While we can’t change the diagnosis, we can provide you with expert care and support, helping your baby get the most out of treatment and life. That’s why we’re available to help 24 hours a day, 7 days a week. For more information or to schedule an appointment, call us at 314-268-4037 or toll free at 877-SSM-FETL (877-776-3385).

Our team is here to develop a comprehensive treatment plan that puts you at ease and gives your baby the best start in life.

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