Congenital Cystic Adenomatoid Malformation

A congenital cystic adenomatoid malformation (CCAM) is a benign (non-cancerous) mass of abnormal lung tissue usually located on one lobe (section) of the lung. CCAMs occur with equal frequency on both lungs. There are two major types of CCAMs:

• Type I is distinguished by one or more large cysts (a closed sac that main contain air, fluids or semi-solid material).
• Type II has both solid regions and cysts.

Here at Boston Children’s Hospital, we care for infants with CCAM in a special area of the hospital known as the Neonatal Intensive Care Unit (NICU). The NICU combines advanced technology and trained health care professionals to provide specialized care for the tiniest patients.

A CCAM is caused by overgrowth of abnormal lung tissue that may form fluid-filled cysts. The cysts prevent the tissue from functioning as normal lung tissue.

Yes, a CCAM can often be detected during a routine prenatal ultrasound, when doctors can see the location and size of the growth, which appears as a bright mass. The fetus’ heart may be shifted to the opposite side of her chest, and her normal lung tissue may be difficult to see on the side where the mass is located. Magnetic resonance imaging (MRI) may also be used to see the mass.

In most cases, the fetus will do well and the mother will carry the baby to term without a problem. If your doctor suspects a CCAM, you will undergo a series of ultrasounds between your 20th to 30th week of pregnancy to see if it continues to grow. During that time, the fetus will grow rapidly, and the mass may appear smaller or unchanged. The CCAM may also shrink and even disappear during the third trimester of pregnancy.

However, in a small number of cases, the mass may grow to be life-threatening to the fetus. As it grows, there is the chance that it might compress blood vessels, making the heart have to pump harder to circulate blood, and possibly leading to heart failure (hydrops).

CCAM is often treated when the fetus develops hydrops or impending hydrops. Your doctor can monitor this closely by ultrasound. Signs of hydrops may include the following symptoms in the fetus:

• Ascites (fluid in the abdomen)
• Edema (extra fluid) of the skin and scalp
• Pleural or pericardial effusion (fluid around the heart and lungs)

Our doctors will also be paying close attention to the mother's health. As the fetus develops hydrops, the mother may show symptoms of preeclampsia (a condition marked by high blood pressure and protein in the urine). If the mother is ill and the hydrops gets too severe, doctors may not be able to perform surgery.

If the fetus develops hydrops that isn’t too severe (or hydrops development seems imminent) and the mother’s health allows, prenatal intervention will be offered sometime prior to 28 weeks gestation. The procedure involved depends on the type of CCAM.

• If the mass is cystic in appearance, then it usually can be drained percutaneously (with a needle and a drain).
• If the fluid reaccumulates, a shunt (a method of redirecting fluid from one part of the body to another, where it can be absorbed) can be placed to continuously drain the cyst.

Sometimes when the mass is solid — and even sometimes when it is cystic — it will need to be removed during open fetal surgery. This procedure usually occurs prior to 28 weeks of pregnancy. During the procedure:

1. The mother is placed under general anesthesia.
2. The uterus is surgically opened.
3. The fetus is partially taken out of the uterus and the mass is removed.
4. The fetus is returned to the uterus, which is then closed.
5. The mother and fetus are monitored closely after the procedure.

There is a risk for preterm labor when an incision is made in the uterus, but medications are available to help control the contractions. For more information, see our fetal surgery page.

We recommend that all babies with a CCAM, even those who underwent prenatal surgery, be delivered at a hospital with a Neonatal Intensive Care Unit (NICU). Often babies will have no symptoms after birth. When this happens, an X-ray will be performed and the baby will go home with mother.

When the baby is around 3 months old, she will have a special X-ray called a CT scan, which produces a three-dimensional image of her lung and the growth.

Sometimes, babies have difficulties breathing after birth and require oxygen and assistance with breathing. Doctors may place a breathing tube and the baby will undergo an operation to remove the mass. After surgery, the baby will stay in the hospital for about a week.

We will schedule surgery to remove the CCAM when the baby is 3 to 6 months old. The hospital stay is usually about three to five days, and your pediatric surgeon will continue to see the baby after she is discharged from the hospital.

Babies who have the CCAM removed either before or after birth usually do well afterwards. Babies’ lungs continue to grow until the child is 9 years old, leaving plenty of time for the development of normal healthy lungs.