Congenital Cystic Adenomatoid Malformation (CCAM)
diagram of congenital
What is a congenital cystic adenomatoid malformation (CCAM)?
A CCAM is a lung mass composed of overgrown lung tissue. It may be solid in nature, cystic, or a combination. The blood supply is derived from the normal lung circulation. It may affect any lobe of the lung. The incidence of CCAM is approximately 1 in 25,000 pregnancies. The cause is unknown.
Microcystic CCAM's consist of many small cysts and macrocystic CCAM's consist of fewer large cysts. Some CCAM's decrease in size or disappear during gestation. The majority will grow during gestation but the growth plateaus at 25 to 26 weeks and the baby's normal lungs grow around the lesion. However, some CCAM's continue to grow during gestation and may cause fetal distress.
What testing is recommended during the pregnancy?
Serial ultrasounds are scheduled to monitor the size of the CCAM during gestation and detect any fetal problems. A CCAM-volume-ratio (CVR) will be calculated to help predict problems during pregnancy. The chromosomes are usually normal in babies with CCAM. A fetal echocardiogram is recommended to assess heart structure and function. In select patients with a large CCAM, a fetal MRI may be performed to define the lesion and assess lung volumes.
Are there special considerations for the delivery?
In general, a vaginal delivery is recommended unless there are obstetric indications for a Cesarean delivery. However, a baby with a very large CCAM who had problems during fetal life may require an EXIT Procedure. All babies with a CCAM should be delivered at a center with a neonatal intensive care unit and pediatric surgical services. Babies that have a large CCAM with concern for pulmonary hypoplasia (small lungs) should deliver in a center capable of ECMO support.
Is there fetal treatment for CCAM?
The majority of babies with a CCAM will not have fetal problems and do not require fetal intervention. Open fetal surgery is reserved for the rare patients with an isolated large microcystic CCAM that is causing hydrops. In this situation, the CCAM is surgically removed and the baby is returned to the womb to continue the pregnancy. If there is a large CCAM with a dominant cyst that is causing hydrops, a minimally invasive thoracoamniotic shunt may be placed. Some CCAM patients may benefit from the use of maternal steroids.
What is the treatment for a CCAM?
CCAM's are surgically removed due to the risk of infection and rare malignant transformation later in life. The timing of surgery depends on the baby's symptoms after birth. If the baby has no breathing problems, only a chest x-ray is obtained. Asymptomatic babies are discharged home and seen in outpatient clinics for follow-up. A CT scan of the chest is scheduled to identify the location of the CCAM. Surgery is performed within the first year of life. In some cases, a minimally invasive thoracoscopic procedure (using a telescope and tiny incision) may be performed to remove the CCAM. Usually, one entire lobe of the lung is removed (lobectomy). Lung function after surgery is usually excellent.
If the baby has breathing problems at birth, the CCAM is excised urgently. In babies with very large CCAMs causing pulmonary hypoplasia and pulmonary hypertension, mechanical ventilation and ECMO support may be required.
Are there other health problems that are more common among babies with CCAM?
The majority of babies with an isolated CCAM do well after the mass is removed. The remaining lung on the affected side continues to grow until the child is about 6 years of age. Rare patients with a giant CCAM may have small lungs and subsequent chronic lung disease.
Can this happen again with another pregnancy?
This condition is a rare condition that has no known genetic cause. CCAMs are typically random (sporadic) birth defects and not associated with specific genetic syndromes or a significant risk for chromosomal anomalies. With the diagnosis of a syndrome or chromosome anomaly, the chance this would happen again is very low. Your doctor and a genetic counselor will review the risk in your family.