CONGENITAL LUNG MALFORMATIONS

-What are congenital lung malformations?

Congenital lung malformations are a family of structural developmental abnormalities of the lung that arise from an error in the embryologic development of the lung. The lung normally develops from one kind of tissue that becomes the airways arising originally from the upper digestive system, and another kind of tissue that becomes the blood vessels and connective tissue of the lung. These two kinds of tissue must "communicate" clearly with each other to form a normal lung. Errors in communication can lead to one or more of these malformations.

-What are the categories of lung malformations?

-Congenital Cystic Adenomatoid Malformation (CCAM) - This malformation results in very disorganized lung tissue.  The air and blood spaces are poorly formed and do not communicate with the normal lung airways and blood vessels as they should. CCAM usually involves a single lobe of one lung but on rare occasion can be quite extensive and threaten the life of the fetus and/or baby.

-Pulmonary Sequestration - This malformation also has very disorganized air and blood spaces. It is usually located in, and limited to, one of the lower lobes.  A large abnormal blood vessel, typically arising from the aorta (the main artery bringing blood from the heart to the body), enters the sequestration.

-Bronchogenic Cyst - This malformation consists almost entirely of a dilated air space that becomes a large cyst that becomes filled with air and respiratory secretions. The cyst does not communicate with the normal airways, as it should. They can occur anywhere in the lungs or even behind the trachea in the middle of the chest.

-Congenital Lobar Emphysema - This malformation is thought to arise because of poor development of cartilage in the large airways.  The airways end up being very soft. This causes them to collapse and trap ever increasing amounts of air in the lung with each inspiration. They usually occur in the upper lobes on either side of the chest.

-How is the diagnosis made?

-Prenatal (before birth) - Many lung malformations are diagnosed on routine prenatal high-resolution ultrasound.  Lung malformations can be seen as early as 15-20 weeks gestation and are usually incidental findings. On rare occasion, particularly if the malformation is quite large, they can cause the fetus to look very swollen (fetal hydrops). This is a worrisome finding. Almost always, the only action needed if a lung malformation is identified is prenatal consultation with a pediatric surgeon comfortable and familiar with these types of diagnoses. These lung malformations are usually isolated findings, not genetic in origin, and not part of a syndrome.

 

-Postnatal (after birth) - Only those malformations large enough to cause symptoms will be diagnosed after birth because a well appearing child would have no reason to be evaluated any further. Newborn infants who are symptomatic from a large malformation will demonstrate hydrops (see above), heart failure, or respiratory failure. Older children can present with an infection in the malformation that looks like a lung abscess (bronchogenic cyst) or repeated pneumonia in the same location (pulmonary sequestration or CCAM).

In either case, the diagnostic evaluation is derived from a combination of chest x-rays, computerized axial tomography (CAT) scan (usually with intravenous contrast agents), or magnetic resonance imaging (MRI). Pulmonary function testing and echocardiography may compliment the evaluation.

• -What are the indications for surgical intervention?
• -Newborns with heart or respiratory failure
• -Older children with infection
• -Large malformations  that are not causing symptoms but are preventing the normal lung from growing properly
• -Smaller malformations that do not go away on examinations over time
• -Malignant potential - Congenital lung malformations, particularly CCAM, are associated with a very rare lung malignancy called pulmonary blastoma. The true incidence is not known, or even if very small malformations should be removed (as opposed to followed) to eliminate the remote risk of cancer. Whether or not surgery is indicated for all lung malformations is controversial, and the answer is not known. Recommendations in this regard are a matter of opinion.

What are the surgical procedures considered?

The type, extent, and location of the malformation generally dictate the amount of lung to be removed. Bronchogenic cysts are generally enucleated (shelled-out) from the lung. Lobar emphysema, CCAM, and sequestration usually require a single lobectomy but on occasion, the entire lung needs to be removed. Regardless of the type of resection, the remaining lung will grow and expand to fill the space and function quite well. Most children who have surgery for these malformations have normal heart and lung function.

-What should we do if we are told our child has a congenital lung malformation?

In our opinion you would benefit from consultation with a pediatric surgeon comfortable with these diagnoses and treatment.  If the diagnosis is made prenatally, he or she will work closely with an obstetrician trained in the management of "high risk" pregnancies.  Such obstetricians are available at both the Columbia campus and the Cornell campus of the New York Presbyterian Hospital.  This obstetrician will arrange for you to deliver your baby either in, or near, a children’s hospital with a full-service neonatal intensive care unit should your baby require those services.  If the diagnosis is made after birth, the team, in addition to a pediatric surgeon, should include a neonatologist for the newborn and a pulmonologist for the older child.