Congenital Cystic Adenomatoid Malformation / CCAM / CPAM
Overview of Congenital Cystic Adenomatoid Malformation / CCAM / CPAM
Definition | Cause(s) | Incidence of CCAM | Diagnosis | Management of Pregnancy | Fetal Surgery and Intervention
Congenital Cystic Adenomatoid Malformation / CCAM (recently termed Congenital Pulmonary Airway Malformation / CPAM) of the lung is a relatively rare abnormality that appears on an ultrasound as a solid or cystic mass (tumor) of pulmonary tissue that has an abundance of bronchial structures (breathing channels).
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The cause of Congenital Cystic Adenomatoid Malformation / CCAM / CPAM is unknown. One theory holds that it is the result of bronchial structures failing to mature properly at approximately the fifth or sixth week of gestation, about the time the lungs begin to form. Another theory holds that CCAM / CPAM is due to an abnormal growth pattern of lung tissue that occurs as a result of bronchial obstruction. There is no known genetic cause for CCAM / CPAM, and no cases of recurrence in a sibling or offspring have been reported.
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Although Congenital Cystic Adenomatoid Malformation / CCAM / CPAM is increasingly being diagnosed in utero, the true incidence of this lesion is not known. CCAM / CPAM lesion is slightly more common in males than females.
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How is Congenital Cystic Adenomatoid Malformation / CCAM / CPAM Diagnosed?
Congenital Cystic Adenomatoid Malformation / CCAM / CPAM can be detected by a detailed ultrasound using color flow Doppler and by ultrafast fetal MRI to confirm the diagnosis and document size and location of the CCAM / CPAM. A fetal echocardiogram can rule out any associated structural heart abnormalities and assess the effect of the CCAM / CPAM on heart function.
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Congenital Cystic Adenomatoid Malformation / CCAM / CPAM should be followed at least weekly (twice weekly in high-risk CCAM / CPAMs) with ultrasound scans for measurement of CAM volume. The CAM volume has been shown to be predictive of outcome in fetuses with these malformations. Weekly ultrasound scans also are recommended to detect signs of hydrops (in utero heart failure) caused by the CCAM / CPAM. The development of hydrops in a fetus with a CCAM / CPAM is usually an indication for fetal surgery. Another sign of hydrops is placental swelling. If placental swelling develops as a result of the CCAM / CPAM, the mother is at risk to develop the "mirror syndrome," an unusual condition in which the mother’s health "mirrors" that of the sick fetus by developing swelling and high blood pressure. This condition calls for immediate delivery of the fetus because "mirror syndrome" is potentially life threatening for the mother.
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Fetal Interventions for
CCAM / CPAM
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The indications for fetal intervention depend on the type of lesion, whether solid or cystic, and the development of hydrops. Malformations with a large cyst can be treated by aspirating with a needle or by placing a specially designed catheter (called a thoracoamniotic shunt) to drain fluid from the cyst to outside the fetal chest.
The first uses of thoracoamniotic shunting in fetuses with Congenital Cystic Adenomatoid Malformation / CCAM / CPAM were reported in 1987. A more recent study found that shunting of malformations with a large cyst resulted in a 51 percent reduction of the CAM volume and resolved the hydrops over seven to ten days. Successful shunting prolonged pregnancy into the third trimester and seven of the ten fetuses treated with thoracoamniotic shunting survived. The authors concluded that a thoracoamniotic shunt should be considered as a treatment option for fetuses with a large cyst with hydrops or at high risk of developing pulmonary hypoplasia (underdeveloped lungs), and reaccumulation of the fluid after one to two needle aspirations of the cyst.
High risk CCAM / CPAMs (with a CVP of ≥1.6 or hydrops) should be treated with maternal steroids. We have found that in up to 50 percent of patients, the CCAM / CPAM will stop growing. This allows the baby to grow out of hydrops and for the lungs to develop.
In patients with large, solid CCAM / CPAM with associated hydrops that do not respond to steroids, open fetal surgery is indicated to remove the CCAM / CPAM. Cases in which the malformations are large but have not resulted in hydrops may require removal during an EXIT (ex utero intrapartum treatment) procedure at the time of delivery.
The EXIT procedure is a variation of Cesarean section which allows surgery to be performed on the baby while still connected to the placenta. The EXIT procedure is reserved for cases in which the CCAM / CPAM would interfere with the baby’s breathing after birth.
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Revised 1/05; 10/08
