Congenital alveolar capillary dysplasia--an unusual cause of respiratory distress in the newborn.

The clinical and anatomical features of a patient with an unusual pulmonary malformation, is reported. The clinical course was consistent with the syndrome of persistent fetal circulation; morphologically, however, the patient was found to have a unique form of pulmonary dysplasia. Failure of formation and ingrowth of alveolar capillaries led to absence of normal air-blood barriers in this term infant. In addition anomalous veins were present in the bronchovascular bundles. Morphometric study indicated that the lungs were otherwise mature. This selective deficiency and dysplasia suggests that distal pulmonary epithelial and vascular development operate under separate control mechanisms.