Purpose: Although antenatal resolution of congenital cystic adenomatoid malformations (CCAMs) is well documented, complete spontaneous postnatal resolution is rare, its existence even questioned by some.
Methods: All cases of antenatally diagnosed CCAMs over 7 years were retrospectively reviewed. Inclusion criteria were the following: (1) antenatal diagnosis of CCAM, (2) persistence on postnatal imaging, and (3) subsequent spontaneous resolution on postnatal imaging.
Results: Of 56 antenatally diagnosed CCAMs, 2 patients were identified. Both had macrocystic lesions. In case 1, the CCAM that filled the hemithorax on antenatal ultrasound was smaller on postnatal chest radiograph and disappeared by age 37 months on computed tomography. Case 2 had significant reduction of the CCAM at birth (persistence of the lesion on initial radiographs and ultrasound was documented). By 5 months, the lesion was not evident on computed tomography. Neither case was associated with symptoms, polyhydramnios, hydrops, or other abnormalities.
Conclusions: In patients with an antenatal diagnosis of CCAM, spontaneous resolution may occur postnatally in 4% of cases. Significant reduction in CCAM size may portend possible disappearance and therefore warrants an observational period before resection.