This condition is an exceedingly rare but quite striking form of primary pulmonary hypoplasia with arrest of lung development at an immature stage that varies from case to case. Almost all affected infants have been female. They are born at or near term, and usually appear to be normally developed. They develop respiratory distress rapidly after birth and die within a few hours because they cannot be adequately oxygenated or ventilated. At autopsy, the lungs are usually somewhat small, about 50% of predicted volume and weight. Sometimes other minor abnormalities are found at autopsy. Two familial cases have been described.

The pathogenesis of this developmental abnormality is unknown, but an abnormality in epithelial/mesenchymal interaction has been postulated. Whether the cases with somewhat later developmental arrest have a similar pathogenesis is unclear. Some of these infants have a somewhat longer course, but they usually die of respiratory failure within 1 month. It can be difficult to separate these cases from those with acquired abnormalities related to prolonged and extensive therapeutic support.