ALVEOLAR CAPILLARY DYSPLASIA WITH AND WITHOUT MISALIGNMENT OF THE VEINS. 1604

Abstract

Alveolar capillary dysplasia (ACD) has assumed clinical importance because of the associated pulmonary hypertension that fails to respond to ECMO. We present two term infants with ACD and congenital heart disease who both failed ECMO therapy. The lungs were filled and fixed postmortem with 10% formalin at 24 cm H2O pressure. Tissue blocks from the left lung were later fixed with glutaraldehyde, cut 1 mm thick and stained with toluidine blue to assess alveolar capillary density. Regular 5-μm sections were stained with hematoxylin and eosin for lung histology. The two infants had pulmonary lobules with round, immature air spaces, lined by cuboidal epithelium separated by hypocapillarized thickened walls (ACD). One infant also had small malpositioned veins accompanying small pulmonary arteries (misalignment of the pulmonary veins; MPV), cortriatrium, and a hypoplastic left heart. The other had no MPV, pulmonary lymphangiectasia, right lung isomerism, and double outlet right ventricle. In conclusion, ACD may occur with and without MPV, possibly depending upon the stage of development during which the abnormality occurs. Eighty-five percent of infants with ACD have additional congenital abnormalities. ACD with and without MPV should be suspected in those newborns with persistent pulmonary hypertension, especially when congenital abnormalities are present.