Congenital Pulmonary Airway Malformation

Congenital pulmonary airway malformation (CPAM) represents a spectrum of abnormally developed lung tissue arising from normal bronchial airways but lacking functional alveoli. The Stocker classification (types 0–4) correlates with bronchial tree location; type 1 (distal bronchi/proximal bronchioles) accounts for 60–70% of cases. Prenatal management hinges on the CPAM volume ratio (CVR = length×width×height×0.52/head circumference): CVR >1.6 predicts 75% hydrops risk, the strongest mortality indicator.[e4463-c5,e4463-c6] Maternal betamethasone (12 mg IM twice, 24 hours apart) is first-line therapy for high-risk lesions, resolving hydrops and reducing CVR in >50% of cases.[e4463-c7,e9333-c12] Refractory hydrops may require thoracoamniotic shunt (macrocystic) or open fetal lobectomy (microcystic <30 weeks).[e4463-c9,e9333-c13] Postnatally, most infants are asymptomatic; air trapping can cause rapid respiratory decompensation.[e4463-c13,e5319-c1] A 2021 multicenter study found 0% malignancy in 344 prenatally diagnosed lesions versus 8.7% in 177 postnatally diagnosed masses, suggesting distinct disease entities.[e5319-c8,e5319-c9] Pleuropulmonary blastoma (PPB) remains the primary malignancy concern; features suggesting higher PPB risk include multilobe/bilateral disease, pneumothorax, and DICER1 mutation, while prenatal diagnosis and feeding vessels confer very low risk.[e4463-c19,e4463-c20] Infection risk is estimated at 20–40% lifetime, complicating subsequent resection.[e307-c13,e643-c9] Thoracoscopic lobectomy at 3 months optimizes tissue planes and minimizes inflammation; operating earlier (1–3 months) yields shorter operative times (115 vs 163 minutes at 6–12 months) without increased complications in experienced hands.[e5319-c24,e5319-c26] Vascular control is paramount: dual-seal technique (two seals 4–5 mm apart, partial division to confirm hemostasis) prevents catastrophic hemorrhage; never take the pulmonary vein near the pericardium.[e307-c32,e4463-c30] The prenatal-versus-postnatal diagnosis dichotomy drives current management controversy: North American practice favors elective resection for all CPAMs, while European/Canadian centers increasingly observe prenatally diagnosed asymptomatic lesions given their negligible malignancy risk and low symptom development (0% symptomatic in one 10-year prospective cohort).[e5319-c3,e5319-c11]