Congenital cystic adenomatoid malformation
Encyclopedia
Congenital cystic adenomatoid malformation (CCAM) is a congenital disorder
similar to bronchopulmonary sequestration. In CCAM, usually an entire lobe of lung is replaced by a non-working cystic piece of abnormal lung tissue. This abnormal tissue will never function as normal lung tissue.
In most cases the outcome of a fetus with CCAM is very good. However in a rare few cases the cystic mass grows so large as to limit the growth of the surrounding lung and cause pressure against the heart. In these situations, the CCAM can be life-threatening for the fetus.
CCAMS are classified into three different types based largely on their
gross appearance. Type I has a large (>2 cm) multiloculated cysts. Type II has smaller uniform cysts. Type III is not grossly cystic, referred to as the "adenomatoid" type. Microscopically, the lesions are not true cysts, but communicate with the surrounding parenchyma
Very large cystic masses might pose a danger during birth because of the airway compression. In this situation, a special surgical type of delivery called the EXIT procedure
may be used.
In rare extreme cases, where fetus's heart is in danger, fetal surgery
can be performed to remove the CCAM. If non-immune hydrops fetalis develop, there is a near universal mortality of the fetus without intervention. Fetal surgery can improve the survival percentage up to 50-60%. Recently, several studies found that a single course of prenatal steroids (betamethasone) may increase survival in hydropic fetuses with microcystic CCAMs to 75-100%. These studies indicate that large, macrocystic lesions may be treated prenatally without surgical intervention.
Congenital disorder
A congenital disorder, or congenital disease, is a condition existing at birth and often before birth, or that develops during the first month of life , regardless of causation...
similar to bronchopulmonary sequestration. In CCAM, usually an entire lobe of lung is replaced by a non-working cystic piece of abnormal lung tissue. This abnormal tissue will never function as normal lung tissue.
In most cases the outcome of a fetus with CCAM is very good. However in a rare few cases the cystic mass grows so large as to limit the growth of the surrounding lung and cause pressure against the heart. In these situations, the CCAM can be life-threatening for the fetus.
Diagnosis
CCAMs are often identified during routine prenatal ultrasonography. Identifying characteristics on the sonogram include: an echogenic (bright) mass appearing in the chest of the fetus, displacement of the heart from its normal position, a flat or everted (pushed downward) diaphragm, or the absence of visible lung tissue.CCAMS are classified into three different types based largely on their
gross appearance. Type I has a large (>2 cm) multiloculated cysts. Type II has smaller uniform cysts. Type III is not grossly cystic, referred to as the "adenomatoid" type. Microscopically, the lesions are not true cysts, but communicate with the surrounding parenchyma
Treatment
In most cases, a fetus with CCAM is closely monitored during pregnancy and the CCAM is removed via surgery after birth. A few fetuses may develop fluid collections within the chest cavity and in those situations a Harrison catheter shunt can be used to drain the fluid into the amniotic fluid.Very large cystic masses might pose a danger during birth because of the airway compression. In this situation, a special surgical type of delivery called the EXIT procedure
EXIT procedure
The EXIT procedure, or ex utero intrapartum treatment procedure, is a specialized surgical delivery procedure used to deliver babies who have airway compression...
may be used.
In rare extreme cases, where fetus's heart is in danger, fetal surgery
Fetal surgery
Fetal surgery is any of a broad range of surgical techniques that are used to treat birth defects in fetuses who are still in the pregnant uterus.* Open fetal surgery involves completely opening the uterus to operate on the fetus....
can be performed to remove the CCAM. If non-immune hydrops fetalis develop, there is a near universal mortality of the fetus without intervention. Fetal surgery can improve the survival percentage up to 50-60%. Recently, several studies found that a single course of prenatal steroids (betamethasone) may increase survival in hydropic fetuses with microcystic CCAMs to 75-100%. These studies indicate that large, macrocystic lesions may be treated prenatally without surgical intervention.
External links
- Congenital Cystic Adenomatoid Malformation | Congenital Pulmonary Airway Malformation Radiology and Pathology