What is Congenital Pulmonary Airway Malformation?
Congenital pulmonary airway malformation (CPAM), along with conditions like bronchogenic cyst and pulmonary sequestration, falls under the broader category known as ‘congenital thoracic malformations’. CPAM is quite rare, but it is the most common birth defect of the lungs. The malformation occurs due to irregularities during the embryo’s development and can happen at different stages of lung growth, causing abnormal formation of the bronchial tubes.
Thanks to technological advances, CPAM is often detected before birth and managed by a pediatric surgeon early on. Babies with CPAM can vary in how severely they are affected. Some might not show any symptoms until later in life, while others may struggle with breathing difficulties shortly after birth.
What Causes Congenital Pulmonary Airway Malformation?
Congenital pulmonary airway malformation occurs when lung development does not progress properly during the embryonic stage. A number of genes could play a role in this fault, including the thyroid transcription factor gene (Nkx2), sex-determining region Y- box 2 gene (Sox2), Hox gene (Hoxb-5), Ying Yang 1 gene (Yy1), fatty acid-binding protein-7 gene (FABP-7), and others.
These genes are connected to cell growth or cell death, leading to different types of malformed airways under the congenital pulmonary airway malformation classification. This can mean some people experience different types of this condition than others.
Risk Factors and Frequency for Congenital Pulmonary Airway Malformation
Congenital cystic lung disease is relatively rare, but almost 95% of cases are due to a condition called congenital pulmonary airway malformation, also known as CPAM. This disease is found in about 1 out of 10,000 to 35,000 births. Studies indicate that it commonly affects male infants. It’s important to note that these malformations are usually random and do not result from genetic tendencies (except for Type 4). Additionally, no links have been found between CPAM and certain factors in a mother’s health.
- 95% of congenital cystic lung disease cases are due to congenital pulmonary airway malformation (CPAM).
- CPAM occurs in approximately 1 in 10,000 to 1 in 35,000 births.
- The disease is more common in male infants.
- Generally, these malformations occur by chance, without any genetic predisposition (except for Type 4).
- No link has been established with a mother’s health or other maternal factors.
Signs and Symptoms of Congenital Pulmonary Airway Malformation
Congenital pulmonary airway malformation, or CPAM, can present differently in different kids. Some babies may show symptoms at birth, while others don’t have any symptoms during infancy or even until they are older. The use of prenatal ultrasound scans has helped diagnose more cases of CPAM before birth, which has led to a decrease in the number of babies showing symptoms when they’re born. But it’s important to note that even if a newborn doesn’t have symptoms, they could still face complications like respiratory infections or cancer later in life. On the other hand, those who do have symptoms often experience breathing difficulties that worsen as the malformation gets bigger and starts to affect surrounding airways. The specific characteristics of the malformation can also influence how it affects the child.
Here’s a brief rundown of the different types of CPAM:
- Type 0: Life-threatening due to extremely limited gas exchange.
- Type 1: Causes increased effort to breathe, rapid breathing, and possible bluish skin color.
- Type 2: Similar to Type 1 but often comes along with other birth defects (like missing kidneys, heart defects, or a hole in the diaphragm).
- Type 3: Can take over the whole lung and possibly cause fetal hydrops (a serious condition in which excessive fluid builds up in two or more fetal compartments) due to underdeveloped lungs.
- Type 4: Often presents as a collapsed lung, and also similar to Type 1. Carries a small risk of infection, cancer, air leak, or bleeding.
Testing for Congenital Pulmonary Airway Malformation
Congenital pulmonary airway malformation, or CPAM, is a common lung abnormality that’s often spotted before a baby is born. During a prenatal check-up, your doctor might use fetal ultrasound to detect this condition. The ultrasound can classify the malformation as either “microcystic” or “macrocystic,” based on the size of the abnormal air pockets in the lung.
If your doctor needs even more information about the malformation, an MRI might be the next step. This can help differentiate CPAM from other conditions like a bronchopulmonary sequestration, an abnormal mass of lung tissue, or congenital diaphragmatic hernia, a birth defect in the diaphragm.
If CPAM is detected during pregnancy, a baby’s first chest x-ray should happen soon after they are born. CPAM is most commonly discovered in the second trimester of pregnancy. If an infant is showing symptoms of CPAM after they’re born, an MRI or CT scan can provide more details about the lung’s condition.
Even if a baby isn’t showing symptoms, their doctor might recommend a CT scan or MRI, especially if the chest x-ray shows large malformations, cysts in both lungs, or a pneumothorax, a condition where air leaks outside of the lung. If a baby doesn’t show any of these signs, they should have an MRI or CT scan by six months of age.
Even if a baby’s chest x-ray looks normal, an MRI or CT scan should be performed, particularly for infants without symptoms. CPAM types 1 and 4 typically show up on a chest x-ray as one or two big air-filled cysts. Type 2 appears as multiple smaller air-filled cysts, making the x-ray look “bubbly”. Type 3 will look like a solid mass on an x-ray, and it can affect the space between the lungs, an area known as the mediastinum.
Treatment Options for Congenital Pulmonary Airway Malformation
If a congenital pulmonary airway malformation (CPAM) is spotted before birth, medical professionals can manage it if there’s a chance of the fetus developing a condition known as ‘fetal hydrops’. In such situations, treatment options may include surgery on the fetus, the use of steroids, or draining fluids to avoid risk to the fetus. After birth, if a baby shows signs of breathing problems, surgery to remove the CPAM is the recommended treatment.
Also, surgery is advised if the CPAM covers more than a fifth of one side of the chest, if there are cysts in both lungs or multiple cysts in one lung, if there’s a pneumothorax (air leakage from the lungs) linked with the CPAM, or if there’s a family history of a rare type of lung tumor called pleuropulmonary blastoma.
In older children with minor symptoms, surgery is often done to avoid repeated infections or potential risks of cancer, especially if the type 4 form of CPAM is confirmed.
When it comes to patients who show no symptoms, there’s a debate about the best course of action. Some suggest preventively removing the CPAM, while others propose monitoring the patient for any symptoms. Both approaches are acceptable, giving doctors the room to choose the most appropriate approach based on the specific patient’s situation, and after discussing the pros and cons of each option with the family.
What else can Congenital Pulmonary Airway Malformation be?
When a baby is suspected to have a birth defect known as congenital pulmonary airway malformation (CPAM), doctors need to rule out a similar condition called bronchopulmonary sequestration (BPS). Both these conditions can be detected while the baby is still in the womb using ultrasound scans. They may show up as a clearly visible, uniform and solid lump. The key distinction between BPS and CPAM lies in their respective connections and blood supplies. BPS is not connected to the airway tree (tracheobronchial tree), and its blood comes from the body’s main blood circulation via a unique blood vessel. Conversely, CPAM is linked to the pulmonary circulation.
In addition to BPS, doctors should also consider other possibilities when diagnosing CPAM. These may include a congenital diaphragmatic hernia, bronchogenic cyst, congenital lobar emphysema, and pneumatoceles. These are all conditions that appear as anomalies in the lungs or diaphragm of the unborn child.
What to expect with Congenital Pulmonary Airway Malformation
The overall outlook for congenital pulmonary airway malformation, a birth defect affecting the lungs, is generally very good when diagnosed before birth. It has even been reported in a number of cases that the condition has improved on its own during pregnancy.
If the baby develops a condition called fetal hydrops, which is when abnormal amounts of fluid build up in two or more body areas, survival rates can decrease. However, surgery can significantly help to improve survival rates, and has often proven to cure the condition in newborns.
Nonetheless, there is evidence to suggest that a wait-and-see approach can be just as successful in certain situations.
According to the Stocker classification, which classifies the condition into different types, Type 1 tends to have the best outlook. The prognosis for Type 2 depends on the severity of any associated anomalies. Type 3 can often lead to severe complications like high blood pressure in the lungs because of an underdeveloped lobe in the lungs. The outlook for Type 4 is excellent with surgery, but this type is strongly linked to a rare type of lung tumor called pleuropulmonary blastoma.
Possible Complications When Diagnosed with Congenital Pulmonary Airway Malformation
In the early years of life of a child born with congenital pulmonary airway malformation (CPAM), infection is the most common complication, particularly if a surgical resection is not performed. Another complication that can occur is a type of lung cancer known as pleuropulmonary blastoma (PPB). Factors that can increase the risk of developing PPB include having type 4 CPAM, having cystic lesions in multiple or both lungs, having a family history of PPB, and having a lung collapse, also known as pneumothorax. Additionally, there is a link between type 1 CPAM and bronchoalveolar carcinoma, a type of lung cancer. A child with type 3 CPAM has the risk of pulmonary hypoplasia, or underdeveloped lungs, which can lead to high blood pressure in the lungs. The situation may be particularly severe if the CPAM is so large that it takes up an entire lung lobe or an entire lung itself.
Common complications associated with CPAM:
- Infection, especially if surgical resection is not performed
- A type of lung cancer known as pleuropulmonary blastoma (PPB)
- Risk factors for developing PPB include: having type 4 CPAM, having cystic lesions in multiple or both lungs, having a family history of PPB, and having a lung collapse
- A link between type 1 CPAM and bronchoalveolar carcinoma, a type of lung cancer
- The risk of underdeveloped lungs (pulmonary hypoplasia), which can lead to high blood pressure in the lungs in children with type 3 CPAM
Preventing Congenital Pulmonary Airway Malformation
If a baby is diagnosed with a birth defect known as congenital pulmonary airway malformation, it’s crucial for the parents and patient to understand what this means for the baby’s future, how the disease usually progresses, and potential complications. Thanks to advances in medical technology, this condition can often be identified before the baby is born. This gives families the opportunity to learn about it and prepare ahead of time for the treatment journey.
Working with a team of different healthcare professionals can provide a smoother transition from care during the pregnancy to care after the baby is born. This comprehensive approach can help families feel more supported and well-equipped to manage their baby’s medical needs.