Pathology of Bronchopulmonary Dysplasia

Abstract

The pulmonary pathology of preterm infants has changed significantly over the past five decades, synchronously with modifications in perinatal and neonatal management. During the pre-surfactant era, mechanical ventilation of preterm infants was associated with a severe fibroproliferative and inflammatory pulmonary response. The resulting lung disease, now known as “classical” bronchopulmonary dysplasia (BPD), was characterized by variable interstitial fibrosis, alternating areas of atelectasis and overexpansion, and severe bronchovascular lesions. Major advances in clinical care, including the use of exogenous surfactant, antenatal glucocorticoids, and improved ventilation techniques, have resulted in survival at lower gestational ages and a significant modification of the BPD phenotype. Lungs of infants with “new” BPD (i.e., surfactant-treated, very preterm infants, usually <1000 g birth weight) show minimal airway lesions and interstitial fibrosis. Instead, “new” BPD is characterized by diffuse enlargement and simplification of the airspaces, associated with dysmorphic pulmonary microvascular growth. This chapter reviews the structural stages of lung development, the histopathologic patterns of preterm lung disease over the past half century, and the pulmonary pathology of long-term, adult BPD survivors.