First-trimester prenatal diagnosis of a thoracic cystic lesion associated with fetal skin edema.

An unusual case of chest cyst diagnosed at the end of the first trimester in a dizygotic twin pregnancy and managed conservatively is reported. Between 11 and 14 weeks of gestation, ultrasound revealed a relatively large echopoor lung cyst occupying the left side of the chest, displacing the mediastinum and the heart. This was associated with increased nuchal translucency thickness and generalized skin edema. Subsequent sonograms showed complete resolution of the cyst together with the skin edema. The fetuses were delivered at term and had an uncomplicated postnatal outcome. This case emphasizes the role of reduced venous return as a cause of early fetal hydrops. Diagnosis and follow-up of a congenital lung cyst from the end of the first trimester should enable early intervention to be made.