Congenital Cystic Adenomatoid Malformation (CCAM) is a condition in which abnormal tissue grows as cysts in a fetus's lungs. The cysts are benign (non-cancerous), however the condition can be life-threatening to the fetus and the mother if complications develop. CCAM cysts can be either fluid-filled or solid and typically grow in one lobe, usually on one side of the lungs, although cysts can be present in both. CCAM cysts can be microcystic (many tiny cysts) or macrocystic (several large cysts). The cysts are classified by their size and type with Type I and II being smaller and fluid-filled and Type III as solid and larger. Most fetuses with CCAM do well and do not require intervention. However, up to 10% develop heart failure (hydrops) from the cysts which can cause pre-eclampsia symptoms in the mother and be life-threatening to both fetus and mother. When hydrops develops, fetal intervention to reduce the size of the cysts or open fetal surgery to remove CCAM cysts is necessary. Fetuses diagnosed with CCAMs are cared for before and after delivery at Sanford's Fetal Care Center and Newborn Intensive Care Units where our specialists provide close monitoring and required procedures.
The cause of CCAM is unknown. It is not genetic and there are no known cases of recurrence in siblings or offspring. CCAM is thought to be the caused by the failure of bronchial structures to develop properly when the lungs begin to grow at the fifth and sixth weeks of gestation. It is slightly more common in males than females.
Most cases of CCAM are diagnosed during a routine prenatal ultrasound. The mass is seen on the screen, and in some cases the fetus's heart may be shifted to the opposite side of the chest. An amniocentesis may be performed for genetic testing to rule out other conditions. Congenital Cystic Adenomatoid Malformation is diagnosed by color flow Doppler ultrasound and ultrafast fetal MRI. Fetal echocardiogram is used to rule out any associated heart abnormalities and assess the effect of CCAM on the fetus's heart function.
Most fetuses with CCAM do not show symptoms and are carried to full term. They are delivered at an NICU and, if doing well, go home with the mother. CCAM babies with no complications may still need surgery within their first six months to remove the abnormal lung tissue and make way for normal lung development. Babies who have CCAM removed before or after birth usually do well. Their expected overall lung development is normal.
In less than 10% of cases, fetuses with CCAM develop heart failure (hydrops) due to pressure of the cyst on the heart or blood vessels or extra fluid volume. Hydrops is fatal in 100% of fetuses who are not treated. Additionally, mothers may develop “mirror syndrome” where their body mirrors the illness of the fetus, causing dangerous pre-eclampsia symptoms of high blood pressure, edema (fluid retention) and protein in the urine. Pre-eclampsia is life-threatening to the mother and requires the baby be delivered immediately.
You will undergo a series of ultrasounds. If the cysts are small and no signs of hydrops are present, your physician will likely recommend a watch and wait approach. You will most likely have weekly ultrasounds, although some women require ultrasounds every other day, to monitor the cysts and the fetus's heart. Congenital Cystic Adenomatoid Malformations cysts often stop growing around gestation week 25 and may shrink as the fetus undergoes rapid growth. Fetuses who are doing well at 25 weeks gestation historically have a very low risk of developing hydrops after that point. If hydrops is present or develops, your physician will discuss treatment options with you.
CCAM does not require treatment unless complications develop in the fetus. The most typical complication is heart failure (hydrops). Hydrops symptoms include fluid in the fetus's abdomen, extra fluid in the skin or scalp and fluid around the heart and lungs. It is an indication that the fetus's heart cannot keep up with blood flow demands and, without treatment, will be fatal. Hydrops can be mild to severe. If hydrops isn't too severe, and the mother's health allows, your physician may recommend intervention to reduce the fluid in the cysts. This is performed as a needle intervention where fluid is drained from the cyst. If fluid reoccurs, a shunt may be inserted to continuously drain the fluid from the cyst to outside the fetus's lung wall.
Solid or very large cysts that cause hydrops may require open fetal surgery to remove the cyst before or at delivery. Open fetal surgery is a modified type of cesarean where physicians make an incision in the uterus, exposing the fetus's chest and perform surgery to remove the cysts. The fetus is then returned to the womb and the uterus closed and the pregnancy carried out until term. CCAM fetuses who have open fetal surgery have an increased survival rate of 50 – 80 percent. However, it places the mother at a high risk for preterm labor and complications. Fetuses with very large cysts may need a specialized delivery procedure called EXIT (ex utero intrapartum treatment) which is a modified cesarean section that allows physicians to perform surgery on the fetus while the fetus is still connected to the placenta, then deliver the baby. Babies with CCAM are cared for in the NICU following delivery.
Additionally, fetuses with microcystic CCAMs may undergo steroid treatment during pregnancy to stop the growth of the cysts and prevent or reverse hydrops. Researchers are studying whether steroids will prevent hydrops in fetuses with large microcystic CCAMs.
Talk to your Sanford Health Fetal Care Center physician to learn more about Congenital Cystic Adenomatoid Malformations and CCAM diagnosis and treatment.