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Fetal Lung Mass

Fetal Lung Mass Q&A

When an abnormal lung growth affects your baby before birth, figuring out the next steps can feel challenging. Dr. Mehra and his team will help you understand your baby’s condition while providing comprehensive care throughout your pregnancy and delivery.  Careful monitioring allows Dr. Mehra to identify the right time for fetal surgical intervention.  With the expertise to carry out such delicate proceures while your baby is still in the womb, Dr. Mehra provides your baby extra time to grow stronger before birth,  while coordinating a safe delivery and any necessary neonatal care.  

What is a fetal lung mass?

Fetal lung masses, or lesions, are abnormal growths of lung tissue that form in or near the lungs before a baby is born. Fetal lung masses are almost always benign (not cancerous), but they can put pressure on the developing lungs and heart.

In addition to affecting development, fetal lung masses can also cause other health problems before and after birth, including:

  • Hydrops fetalis
    • If the mass presses on the heart and major blood vessels, the heart can’t pump blood efficiently. Fluid can then build in the organs, causing the baby’s belly to swell and excess amniotic fluid to collect in the mother.
  • Pleural effusion
    • Large fetal lung masses can cause fluid to build up between the lungs and chest wall.
  • Neonatal pneumonia
    • If a fetal lung mass becomes infected, it can lead to pneumonia in newborns and infants.

Types of fetal lung masses:

The most common types of fetal lung masses are:

  • Congenital pulmonary airway malformation (CPAM)
    • The most common fetal lung masses, CPAMs are growths formed from fluid-filled pockets called cysts. The masses may contain a few large cysts or many small ones. CPAMs were formerly called congenital cystic adenomatoid malformations (CCAMs).
  • Bronchopulmonary sequestration (BPS)
    • A BPS is a solid growth that can form inside or outside a lung but isn’t connected to the baby’s airway. With a blood supply directly from the aorta, (largest artery), a BPS can grow quite large.
  • Hybrid lesion
    • This lung mass is a combination of a CPAM and a BPS, with features of both types of lesion. 
  • Bronchial atresia
    • Abnormal growths can partially or completely block a bronchus, a section of airway that branches off the trachea (windpipe) into the lungs.


What causes fetal lung masses? 

The causes of fetal lung masses are unknown. They aren’t inherited (passed down in families), so they’re not likely to happen again in another pregnancy.

What are the signs and symptoms of a fetal lung mass?

Usually, fetal lung masses don’t cause noticeable symptoms during pregnancy. Although your baby might show the effects at birth, signs of lung masses sometimes don’t appear for a few months.

How is a fetal lung mass diagnosed?

Doctors can often detect fetal lung masses in a routine ultrasound during pregnancy.  If a mass is suspected, more detailed imaging will be ordered to learn about the size, location and type of mass involved. If the mass isn’t discovered until after the baby is born, the same imaging is used, which may include:

Depending on the results of the tests listed above, you may also be referred to our genetics program for a consultation and evaluation.

What is the treatment for fetal lung mass?

As with many fetal diagnoses, careful monitoring is key.  In many cases, fetal lung masses begin to shrink and don’t require treatment until after birth. Ultimately, however,  treatment will be determined by the size and location of the mass, and it's affects on other vital organ systems.  Consistent prenatal scans will help Dr. Mehra and his team develop an appropriate treatment for any presenting concerns.

Prenatal treatment for fetal lung mass

If the mass begins to compress the heart or lungs, your baby may need treatment before birth. Treatment options during pregnancy include: 

  • Steroid medications
  • Cyst drainage
  • Shunt placement 
  • Fetal surgery 

Fetal lung mass treatment at birth

Our team is in the delivery room to support babies with fetal lung mass at birth. In cases where the mass may affect the baby's airway at birth, Dr. Mehra can perform a special procedure called EXIT (ex utero intrapartum treatment).

EXIT provids therapy while your baby is still attached to the placenta. It is an open surgery with a recovery of 3 to 4 days. 

Fetal lung mass treatment after birth

Your baby might not show any signs or symptoms at birth if the mass is small. Later in childhood, fetal lung masses can become infected, or in very few cases, turn cancerous. For those reasons, we usually plan surgery to remove the mass when your baby is 3 to 12 months old.  

Fetal lung mass follow-up care

After lung mass surgery, Dr. Mehra provides ongoing care to prevent lung infections and disease, and will partner with your pediatrician to enusre consistency in care. 

Contact our office today to learn more about management and treatment of fetal lung masses.