Prenatally Diagnosed Congenital Lung Lesions:
Advances in medical technology are enabling physicians to detect problems at earlier and earlier stages of fetal development. Abnormalities of the developing lungs can be detected as early as four months gestation, enabling babies to receive treatment well before debilitating or dangerous symptoms develop.
In approximately one out of 30,000 pregnancies, a problem during development of the respiratory system leads to a birth defect in the lungs. This defect may manifest as one of three kinds of lesions:
- Congenital cystic adenomatoid malformations, or CCAM, cysts that replace some of the normal lung tissue;
- Bronchopulmonary sequestration, or BPS, in which abnormal lung tissue forms, and is nourished by extra blood vessels extending from the aorta; and
- "Hybrid" lesions, which may contain cysts and extra blood vessels.
Not all lung lesions result in symptoms, according to Keith A. Kuenzler, MD, Director, Minimally Invasive Pediatric Surgery at Morgan Stanley Children's Hospital of NewYork-Presbyterian/Columbia University Medical Center (MSCHONY/CUMC). "It used to be that we would discover these lesions on X-rays or CT scans during the workup of children who had multiple bouts of pneumonia or difficulty breathing. Now, prenatal ultrasound has become so advanced that we find them long before any symptoms develop."
A percentage of prenatally detected lung lesions completely disappear on their own. In very rare cases, they may cause a fatal circulation problem in utero, known as hydrops fetalis. Some do not cause significant symptoms, but many do lead to recurrent lung infections, says Dr. Kuenzler. "These lesions take up space that the growing lung should occupy. While some are small, others may grow to take up half the chest." There is also an association between cystic lung lesions and unusual forms of lung cancer, although this risk is far lower than the risk of infection.
Obstetricians at MSCHONY's Center for Prenatal Pediatrics are often able to detect lung lesions at 15-25 weeks gestation. Except in the rare cases where dangerous circulation problems exist, babies with lung lesions are born normally, and after four months they undergo a CT scan. Lesions that persist are excised by removing the implicated lung lobe in its entirety. Surgery is performed between six and nine months of age, when the risks from anesthesia are reduced.
For the past two years, these operations have been performed at MSCHONY/Columbia with minimally invasive techniques, using three- and five-millimeter incisions and tiny instruments. This highly advanced technology allows the least tissue trauma, minimal scarring, and a very short recovery. Patients are discharged home the day following surgery, as opposed to the five days required for the larger, traditional open chest incision.
In Europe, physicians leave such lesions alone if a child is not experiencing any symptoms. In the U.S. however, these lesions are usually removed prophylactically. One important reason for this difference is reluctance to expose children to repeated CT. "We have the option of treating or observing such lung lesions, but following them requires repeated CT scans. Each CT scan produces the radiation equivalent of 100-150 X-rays, and no one knows the long-term effects of that much exposure," says Dr. Kuenzler. "It may also mean continuous anxiety for families over the course of years." As a result, most surgeons in the U.S. recommend surgical removal during the baby's first year.