Contributed by Humberto Trejo Bittar, MD and Miguel Reyes-Mugica, MD
The neonate was the product of an uneventful 39-4/7 week pregnancy with normal delivery and adequate initial Apgar scores. Soon after birth, the neonate developed cyanosis, left side pneumothorax and lung parenchymal abnormalities with opacity on x-ray. He expired at 12 days of age in the setting of progressive respiratory failure, pulmonary hypertension, and finally acute kidney failure. An autopsy revealed normal cardiac anatomy.
At low magnification, sections of the lung show multifocal vascular ectasia and hemorrhages (Figures 1 and 2). Examination of the pulmonary vascular bed demonstrates arteries with the expected thick tunica media. However, the most striking finding is the aberrant location of veins next to arteries and airways, some of them sharing the same adventitial sheets (Figures 3 and 4). The alveolar septa are thick and the capillaries are dilated, reduced in number and centrally located, far away from the alveolar epithelium (Figures 5, 6 and 7). There is arrested lung maturation characterized by immature lobular formation, enlargement of alveolar spaces, simplification of the acinar architecture and inconspicuous alveolar type-I pneumocytes with alveolar type-II pneumocyte hyperplasia (Figures 1, 2, 3, 4, 5, 6, 7 and 8). This histological pattern involves both lungs and is present in all the examined slides. There is no significant acute or chronic inflammation and minimal alveolar edema, with no hyaline membrane formation.