Vanishing congenital lung malformations: What is the incidence of true regression?

BACKGROUND: A congenital lung malformation (CLM) that is diagnosed on prenatal ultrasound exam may subsequently become undetectable on later scans, a "vanishing" CLM. OBJECTIVE: The purpose of our study is to characterize the prenatal natural history and postnatal outcomes of "vanishing" lesions treated at our institution. METHODS: We performed a retrospective chart review of 107 patients diagnosed prenatally with CLM at our institution. Comparisons were made using Kruskal-Wallis or t-test for continuous variables and Fisher's exact test or Chi-Square test for categorical variables. Multivariable analysis using logistic regression was performed. RESULTS: Of the 104 patients, 59 (56.7%) had lesions that became sonographically undetectable on serial ultrasound scans. Patients with lesions that vanished prenatally tended to need less Neonatal Intensive Care Unit (NICU) admission at birth (persistent CLM: 54.8%vs vanished CLM: 28.8%), decreased need for supplemental O2 at birth (persistent CLM: 31.0%vs vanished CLM: 11.9%), and decreased delay in feeds (persistent CLM: 26.2%vs vanished CLM: 8.5%) compared to those with persistent CLM. After multivariate analysis controlling for maternal steroid administration and sex, admission to NICU maintained a slight statistical significance, with patients in the vanishing CLM group 2.5 times less likely to be admitted to the NICU. None of our patients whose lesions vanished prenatally required mechanical ventilation. Eighty-six patients underwent postnatal computed tomography (CT) chest. Only 2 patients had lesions that regressed on postnatal CT. CONCLUSION: Lesions that vanish on prenatal imaging may be associated with improved clinical outcomes. The rate of true regression at our institution was as low as 2.3%. [ABSTRACT FROM AUTHOR]