This article requires a subscription to view the full text. If you have a subscription you may use the login form below to view the article. Access to this article can also be purchased.
The Case
On day 2 after birth, a term male infant began having episodes of tachypnea and oxygen desaturation to 60% to 70% during feeding, which self-resolved after removing the nipple. A chest radiograph showed a hazy opacity in the right lower lung field. Physical examination revealed an unlabored breathing pattern with equal air entry in all lung fields. (Figure 1).
Right lung multicystic lesion.
Right lung cystic lesion, with possible feeding vessel (anterior view).
MRI repeated at 34 weeks’ gestation showed minimal regression of the mass, with continued multicystic appearance but no definitive mass effect (posterior view).
Prenatal and Birth Histories
Male infant born at 39 2/7 weeks’ gestation to a 32-year-old gravida 1 para 0 mother who had a history of hypothyroidism
Delivered via scheduled cesarean with vacuum assist
Cyanotic at delivery but cried immediately. Apgar scores of 8 and 9 at 1 and 5 minutes, respectively. Warmed, dried, and stimulated only with good response in color and tone
Birthweight: 3,280 g
Prenatal laboratory evaluation: blood type O, Rh-positive; antibody screen–negative; rapid plasma reagin nonreactive; rubella immune; positive for group B Streptococcus
Case Progression
The patient was not to have anything by mouth, but he continued to have frequent oxygen desaturation episodes without associated respiratory distress.
Differential Diagnosis
Focal pneumonia
Focal atelectasis
Bronchogenic cyst
Bronchopulmonary sequestration
Congenital pulmonary airway malformation
Congenital lobar emphysema
Congenital diaphragmatic hernia
Actual Diagnosis
Congenital Pulmonary Airway Malformation
Actual Diagnosis
The patient’s condition was identified prenatally by using fetal ultrasound at 19 weeks’ gestation. Fetal magnetic resonance imaging (MRI) performed at 24 weeks’ gestation revealed the congenital pulmonary airway malformation (CPAM) occupying the majority of the right lung with several cystic areas, lateral displacement of the mediastinum, and inferior displacement of the right diaphragm. There also was concern that a feeding vessel to the malformation might be present.
Postnatally, the infant was evaluated by pediatric surgery and pulmonology to determine the need for urgent removal of the malformation in the setting of oxygen desaturation episodes. As oxygen desaturation episodes slowly resolved and the patient remained on room air, surgical removal was deferred. The patient successfully underwent lobar resection at age 4 months by pediatric surgeons.
The Experts
Definition/Incidence
Congenital pulmonary airway malformation (CPAM) is a congenital anomaly in the development of the lower airway tracts affecting 1 per 11,000 to 1 per 35,000 live births, with a slight male predominance. The timing of insult to embryogenesis is unclear, but it has been suggested that it may occur between 5 weeks’ gestation and 22 weeks’ gestation.
The lesions, composed of nonfunctional cystic lung tissue, communicate directly with the tracheobronchial tree, whereas bronchopulmonary sequestrations do not. Although the blood supply is generally from normal pulmonary circulation, often a hybrid CPAM lesion may draw its own blood supply from a feeding vessel directly connected to the systemic circulation. These lesions most often (85%–95%) are unilateral and are only rarely bilateral.
Types
The Stocker classification system groups CPAM into major subtypes based on histopathology and a favorable versus unfavorable prognosis. However, these subtypes are not used as indications for treatment, and controversy continues regarding the nomenclature and classification of these malformations.
Type 1.
Type 1, the most common type, occurs in 50% to 65% of cases and is predominantly cystic. Lesions consist of multiple thin-walled cysts, lined with pseudostratified ciliated epithelium, and filled with air or fluid. These lesions generally present within the first week to month after birth and, with intervention, have an excellent outcome.
Type 2.
Type 2 lesions account for 10% to 40% of cases and consist of more numerous, smaller cysts, lined with columnar or cuboidal epithelium. These lesions frequently are associated with other congenital malformations, including cardiac or renal abnormalities.
Type 3.
Type 3 lesions account for 5% to 10% of cases. These lesions consist of small cystic lesions (generally less than 0.2 cm) or solid lesions that resemble immature lung without the presence of bronchioles. They commonly produce a mass effect, leading to pulmonary hypoplasia and fetal hydrops, and are symptomatic at birth with severe respiratory distress and cyanosis.
Type 4.
The type 4 lesions are a subclass previously included in the CPAM type 1 category. These lesions are made up of large thin-walled cysts, with nonciliated flattened epithelial cells.
Type 0.
Type 0 lesions are the least common, accounting for less than 5% of cases, and also are known as acinar dysplasia or agenesis. These lesions are incompatible with life and generally are associated with other cardiovascular abnormalities. Infants who have type 0 lesions generally live only a few hours after birth.
How to Diagnose
CPAMs often are detected during routine prenatal ultrasound, most commonly in the second trimester. As in this case, additional prenatal studies, including three-dimensional ultrasound and fetal MRI, may be used to further delineate the nature and size of the lesion. Color Doppler imaging may be beneficial to determine the presence or absence of a systemic feeding vessel.
Postnatally, previously undiagnosed infants may present with respiratory distress and cyanosis, prompting imaging studies, or many may remain asymptomatic until later in life when the lesions are discovered as an incidental finding on chest radiograph.
Treatment/Complications
The size of the lesion often dictates the severity of the associated morbidity and thus the timing of the intervention. In utero, a mass effect created by the malformation may cause polyhydramnios, nonimmune fetal hydrops, and severe pulmonary hypoplasia. Many fetal centers are performing in utero interventions in such cases with thoracentesis, placement of a thoracoamniotic shunt, injection of sclerosing agents, or open fetal surgery. However, optimal management guidelines have not been created. Respiratory distress at birth often can be a presenting symptom, with mediastinal shift, hyperinflation, left to right shunting, or pulmonary hypoplasia also present. Symptomatic lesions require immediate surgical intervention in the neonatal period.
Recommendations for management of CPAMs that are asymptomatic at birth remain controversial; however, most agree with elective surgical resection during infancy. Long-term risks of unresected CPAMs include recurrent infection and malignancy, particularly pleuropulmonary blastoma and rhabdomyosarcoma. In addition, there is some evidence of compensatory lung growth if the lesion is resected at an early age.
Prepared by
JoDee M. Anderson, MD, MEd, Division of Neonatal Medicine, Oregon Health & Science University, Portland, OR.
American Board of Pediatrics Neonatal-Perinatal Content Specifications
Recognize the clinical and imaging features of congenital malformations of the lung, including congenital pulmonary lymphangiectasia, and the cystic lung diseases, such as congenital lobar emphysema, cystic adenomatoid malformation, and mediastinal tumors.
Know the appropriate management for an infant who has congenital malformations of the lung, including congenital pulmonary lymphangiectasia, and cystic lung diseases, such as congenital lobar emphysema, cystic adenomatoid malformation, and mediastinal tumors.
- Copyright © 2013 by the American Academy of Pediatrics
Individual Login
Institutional Login
You may be able to gain access using your login credentials for your institution. Contact your librarian or administrator if you do not have a username and password.
Log in through your institution
Pay Per Article - You may access this article (from the computer you are currently using) for 2 days for US$25.00
Regain Access - You can regain access to a recent Pay per Article purchase if your access period has not yet expired.
In this issue
Jump to section
Related Articles
Cited By...
- No citing articles found.