(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. Fortunately, most of the time the prognosis is excellent. The two most common types of fetal lung masses are called CCAM and BPS.
Congenital Cystic Adenomatoid Malformation (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 for the mothers, there is no known recurrence risk for future children.
CCAMs are detected through ultrasounds, seen in the chest located in one lobe (section) of the lung. These can be either microcystic (containing fluid filled cysts less than 5mm) or macrocystic (containing fluid filled cysts more 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 done 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 a coordinated ex-utero intrapartum (EXIT) procedure.
After delivery, infants are at an increased risk of lung infections. Based on this, many CCAMs are removed surgically after birth.
Bronchopulmonary Sequestration (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 location 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.
If BPS is isolated, the prognosis is excellent. However, if other anomalies or fetal hydrops is 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.
Overall, the majority of women whose fetuses are diagnosed with CCAM or BPS will deliver healthy babies who may or may not need surgery to remove the mass. The overall prognosis is therefore very good. All these pregnancies require close monitoring, and in some cases, intervention during pregnancy.
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!