Fetal Lung Masses

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

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

We also treat other rare types of lung masses, including congenital lobar emphysema (CLE) lesion and pulmonary blastoma. In babies with the lungs becomes blocked or narrowed during fetal development. Pulmonary blastoma is a fetal type of lung cancer  that can look just like a CPAM and can only be diagnosed after removing the mass.

At the Cardinal Glennon St. Louis Fetal Care Institute, our leading team of fetal specialists, nurses, and surgeons work closely with mothers facing a diagnosis of a fetal lung mass.

In most cases, the mass is benign and can be easily managed after birth. We understand the anxiety and worry you may have and can help.

In the rare setting 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, whether that be open fetal surgery or a needle-based ultrasound-guided procedure.

How Are Lung Masses Diagnosed?

Fetal lung masses typically are detected during a routine ultrasound around 20 weeks of gestation. The mass will appear as a bright area of the lung on ultrasound, or may shift a baby’s heart to one side.

Once detected, MRI imaging can tell your doctor more about the nature and size of the mass. In some cases however, a lung mass may not be detected until after delivery.

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. Sometimes these problems must be managed before birth or at birth, but usually lung lesions can be managed 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:

  • Open fetal surgery to remove the mass
  • Draining a CPAM cyst using a special needle
  • Medication to stop the growth of the mass
  • Early delivery starting at 32 weeks of pregnancy

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. During this operation, the baby is delivered, but the placenta and umbilical cord remain attached, so we have time to see how the baby’s lungs function. If the lungs are very compromised, then the mass is removed just prior to birth to optimize expansion of the normal lung. Extracorporeal membrane oxygenation (ECMO) may  also be used as a backup in case the lungs need more time to function optimally. ECMO is a machine which functions just like the lungs, helping the body exchange vital gasses such as oxygen.


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

Lung Cancer

There are very few reports of babies having pulmonary blastoma, which is an extremely rare type of lung cancer. However, there are many 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 from the CPAM.

What Can I Expect After Surgery for a Lung Mass?

If your baby requires surgery after delivery, your baby will need to stay in our neonatal intensive care unit (NICU) for the first few days and will be connected to breathing tubes and other support wires. Depending on your baby’s condition, they may need to spend more time in the hospital. 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. 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). You can also email us and one of our trusted representatives will get back to you as soon as possible.

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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