Familial pulmonary lymphatic hypoplasia associated with fetal pleural effusions

Two siblings born with pleural effusions died of pulmonary insufficiency. The infant born with fetal hydrops at 30 weeks of gestational age lived 45 minutes. The lung weights were mildly hypoplastic on postmortem examination. The sibling, born at 37 weeks of gestational age lived 8 days. Postmortem lung weights were normal, but the infant had a congenital heart anomaly consisting of a complicated vascular ring. Morphometric analysis of both infants indicated relatively normal lungs except for interlobular septal lymphatic hypoplasia, apparently a specific, previously unrecognized cause of fetal pleural effusions.