What is congenital pulmonary airway malformation (CPAM) and how is it treated in newborns?

Congenital Pulmonary Airway Malformation (CPAM)

Definition and Pathophysiology

Congenital pulmonary airway malformation (CPAM) is a rare developmental lung malformation characterized by abnormal bronchial development and localized glandular overgrowth, occurring in approximately 1 in 25,000 to 35,000 births. 1

• CPAM represents a spectrum of cystic and non-cystic anomalies arising from failure of normal airway development during fetal life 2, 1
• The malformation is classified into 5 types (0-IV) based on the origin of affected pulmonary areas, cyst size, and appearance 2
• Most cases are now diagnosed prenatally via ultrasound, though some present in childhood or rarely in adulthood 2, 3
• CPAM receives arterial supply from the pulmonary artery, distinguishing it from pulmonary sequestration which receives systemic arterial supply 2

Clinical Presentation

Prenatal Presentation

• Large lesions cause mediastinal shift that impairs venous return and cardiac output 4
• Esophageal compression from mass effect results in polyhydramnios 4
• Hydrops fetalis develops in only 5% of CPAM cases but confers poor prognosis without treatment 4

Postnatal Presentation

• Respiratory distress at birth requiring immediate neonatal intensive care 5, 1
• Recurrent chest infections and pneumonia are the most common presentations 2, 3
• Pneumothorax, hemoptysis, or incidental radiographic findings may occur 2
• Tracheomalacia or bronchomalacia can complicate severe cases requiring pneumonectomy 5

Treatment Algorithm

Fetal Management (When Hydrops Develops)

For macrocystic CPAM with hydrops: perform fetal needle drainage or place thoracoamniotic shunt. 4

For microcystic CPAM with hydrops: administer maternal corticosteroids as first-line treatment (betamethasone 12.5 mg IM every 24 hours for 2 doses OR dexamethasone 6.25 mg IM every 12 hours for 4 doses). 4

• Fetal intervention should be performed at tertiary care centers with expertise in these procedures 4
• Corticosteroid therapy is currently recommended as first-line treatment for solid (microcystic) lesions 4
• In utero resection has been advocated for severe cases but is less commonly performed than medical management 4

Neonatal Management

Symptomatic CPAM requires prompt surgical resection, typically lobectomy, performed emergently on the first day of life if respiratory compromise is severe. 5, 1, 3

• Emergent pneumonectomy may be lifesaving for giant multilobar CPAM, though significant pulmonary hypertension should be anticipated 5
• Management options for severe cases include fetal surgical intervention, ex utero intrapartum treatment (EXIT), or expectant management 5
• Extracorporeal membrane oxygenation (ECMO) may be required for severe pulmonary hypertension and contralateral lung hypoplasia 5
• Prolonged intensive care unit stays are expected, with complications including pneumonia, ventilator dependence, and pulmonary hypertension 5

Asymptomatic CPAM Management

Early elective surgery is recommended for asymptomatic CPAM due to increasing infection rates over time that render delayed surgery more difficult, plus unknown but real malignancy risk. 3

• The postnatal management of asymptomatic CPAM remains controversial, but the trend favors early surgical intervention 3
• Increasing rate of infections over months to years makes delayed surgery technically more challenging 3
• Risk of malignant transformation (pleuropulmonary blastoma) exists, though exact incidence remains unknown 3
• Surveillance without surgery carries ongoing risks that accumulate over time 3

Diagnostic Approach

• Prenatal ultrasound identifies most cases, allowing for prenatal counseling and delivery planning 2, 3
• Postnatal chest radiography and computed tomography (CT) are reference standards for anatomic definition 6, 1
• Lung ultrasound can identify CPAM lesions (single large cystic lesion, multiple hypoechoic lesions, or consolidation) and may confirm antenatally diagnosed cases 6
• Histopathological examination post-resection is essential for accurate classification and definitive diagnosis 1, 3

Critical Pitfalls to Avoid

Do not use beta-agonist bronchodilators if tracheomalacia complicates CPAM, as they worsen dynamic airway collapse. 7, 8

• Differential diagnosis must exclude pulmonary sequestration, bronchogenic cyst, congenital lobar emphysema, pleuropulmonary blastoma, cystic bronchiectasis, and diaphragmatic hernia 2
• Families should be counseled that survival after pneumonectomy is achievable with adequate contralateral lung development 5
• Symptomatic tracheomalacia/bronchomalacia may require aortopexy or tracheotomy in severe cases 5
• Type 4 CPAM must be distinguished from type I pleuropulmonary blastoma using molecular and pathological analysis 3