Congenital masses of the lung: Changes in cross-sectional area during gestation

Purpose We assessed the growth of congenital masses of the lung during gestation using computer‐assisted planimetry. Methods The prenatal sonograms of 8 fetuses with congenital masses of the lung were reviewed. Results The cross‐sectional area of the mass and chest were measured on the same transverse image using computer‐assisted planimetry, and the percentage of the chest occupied by the mass was determined for each study. Four masses had pathologic features of type II congenital cystic adenomatoid malformation and intralobar sequestration (CCAM/ILS), 2 were type II CCAM, 1 was type I CCAM, and 1 was bronchial atresia with bronchiectasis. Four masses increased in cross‐sectional area during gestation, 1 decreased, 2 were essentially unchanged, and 1 showed an initial increase in cross‐sectional area followed by a decrease later in gestation. No consistent growth pattern was seen among masses with similar histologic characteristics. The percentage of the cross‐sectional area of the chest occupied by the mass decreased in 7 fetuses and was virtually unchanged in 1 during gestation. All the fetuses survived to term; the infants had an uncomplicated postnatal course and underwent surgical resection of the mass during the first year of life. Conclusions This study showed that in a fetus with a congenital mass of the lung and a favorable clinical outcome, growth of the chest exceeds any growth of the mass that may occur and masses with the same pathologic diagnosis have different patterns of growth in utero. © 1997 John Wiley & Sons, Inc. J Clin Ultrasound 25: 372–377, 1997.