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(Congenital Cystic Adenomatoid Malformation (CCAM) and Bronchopulmonary Sequestration (BPS))

During routine ultrasound evaluating the fetal anatomy, occasionally a fetus is found to have an abnormal growth (mass) in the lungs. Most of the time the prognosis is excellent, but it may require a few extra steps in your natal plan. However, it’s still important to know your options if your baby shows signs of having either complication during a high-frequency ultrasound. Here’s what to know about the two most common types of lung masses that can develop during pregnancy.

What is a lung mass?

A lung mass or malformation is a lump of tissue or lesion that develops on the lung, usually on a single lobe. There’s no known cause. The two most common types of fetal lung masses are called CCAM (Congenital Cystic Adenomatoid Malformation) and BPS (Bronchopulmonary Sequestration). CCAM affects only about one in 25,000 pregnancies, and BPS is even more rare. Most lesions stop growing around 26 weeks gestation, but some continue to grow.

Congenital Cystic Adenomatoid Malformation (CCAM)

What is CCAM?

Congenital cystic adenomatoid malformation (CCAM, sometimes called CPAM for congenital pulmonary adenomatoid malformation) is a non-cancerous mass developed from abnormal lung tissue and is the most common fetal lung mass. CCAMs occur sporadically and is not considered a hereditary condition and, for the mothers, there is no known recurring risk for future children.

What are the risks?

CCAMs are detected through ultrasounds, seen in the chest and located in one lobe (section) of the lung. These can be either microcystic (containing fluid filled cysts smaller than 5mm) or macrocystic (containing fluid filled cysts bigger than 5 mm) in size and can change in size over time. Based on the size of the CCAM, the heart may be displaced and may lead to fetal hydrops (a form of heart failure in fetuses), poor swallowing, and polyhydramnios (increased amniotic fluid).

When CCAM is diagnosed prenatally, most masses are stable in size or decrease over time. So, as the fetus continues to grow, the shifting heart often is naturally resolved, and the prognosis is excellent, even with larger CCAMs. Therefore, all that is required is close monitoring with serial ultrasounds. However, if fetal hydrops is present, mortality is very high if left untreated.

Fetal hydrops refers to a critical condition and is diagnosed by finding an abnormal accumulation of fluid in two or more fetal compartments. There are many causes of hydrops, but in the case of CCAM it would normally be due to fetal heart failure from compression by the CCAM.  If fetal hydrops develops early in gestation, various procedures including percutaneous cyst drainage or shunt placement can be attempted. If it develops later in pregnancy, delivery after steroids is generally recommended with coordinated ex-utero intrapartum (EXIT) procedure.

After delivery, infants are at an increased risk of lung infections. Because of this, many CCAMs are removed surgically after birth.

Bronchopulmonary Sequestration (BPS)

What is BPS?

Bronchopulmonary sequestration (BPS) is the second most common fetal lung mass and refers to lung tissue that doesn’t connect to the tracheobronchial tree or pulmonary arteries. On ultrasound, it appears like a solid lung mass with blood supply directly from the aorta. BPS frequently have cysts, (especially in lesions that are hybrid with CCAM, which can occur). The mass is generally 90% located on the left side, with 10 to 15% located below the diaphragm. The cysts are generally small-to-moderate in size and rarely fill the entire chest area. Over time, they often decrease in size.

What are the risks?

If BPS is isolated, the prognosis is excellent. However, if other anomalies like fetal hydrops are present, it results in a poor expected outcome. Rarely, this is associated with hydrothorax, or a condition of having fluid in the pleural cavity around the lungs. In hydrothorax cases, this may require in-utero shunting. After birth, some babies undergo a surgical removal of the BPS; however, small lesions without symptoms may not require removal.

What if my baby has CCAM or BPS?

Overall, the majority of women whose fetuses are diagnosed with CCAM or BPS will deliver healthy babies. However, your baby may or may not need surgery to remove the mass, so the overall prognosis is therefore very good. All these pregnancies require is close monitoring, and in some cases, intervention during pregnancy.

If the lung malformation needs removal, you should meet with a pediatric surgeon to discuss your baby’s options. Although most masses don’t cause breathing problems in the first few months of life, they can cause complications as your baby grows up. This can include recurrent pneumonia and, in very rare cases, malignant transformation. Lung surgery is often performed between three and six months of birth and has a high success rate. Once recovered, many children have normal lung function with no restrictions, and your child’s lungs can grow to compensate for the lost tissue if applicable.

Schedule an Appointment

Navigating a diagnosis of CCAM or BPS can feel overwhelming, so it’s important to partner with our award-winning team of maternal fetal medicine specialists to learn more. To schedule an appointment or learn more about our high-frequency ultrasound services, we invite you to call or fill out our online form.

Carnegie Imaging for Women blogs are intended for educational purposes only and do not replace certified professional care. Medical conditions vary and change frequently. Please ask your doctor any questions you may have regarding your condition to receive a proper diagnosis or risk analysis. Thank you!