MORPHOLOGICAL EVOLUTION AND DIAGNOSIS OF BRONCHOPULMONARY DYSPLASIA IN VERY PRETERM INFANTS

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Bronchopulmonary dysplasia (BPD) remains one of the most common and severe diseases in very preterm infants, which can cause death. Since the first description of BPD in 1967, not only understanding of the disease’s nature, its definition, classification, epidemiology, features of the clinical course, diagnosis, prevention, treatment, and prognosis but the specific autopsy histopathological features have changed. The primarily reason for these is considered a change in the population of sick and dead infants as a result of improving clinical practice, increasing the survival rates of the most immature neonates, and reducing the incidence of severe BPD forms and the associated mortality.The BPD form that has been described initially is now called "old" BPD and is characterized by significant lung injury. In the smallest neonates, who were treated with exogenous surfactant, the histopathological signs of the disease changed, determining the need to modify the theoretical concept of BPD. The leading feature of the new BPD form was the disorder of lung development and formation, not their injury. Morphologically, this was manifested by a reduced number and simplified structure of acini, changes in the capillary structure with less obvious fibrosis of the lungs. Such morphometric methods as the radial alveolar count and the count of mean number of alveoli intercepts can be used for the histopathological diagnosis of a simplified lung structure. The use of these techniques helps to objectively assess lung growth retardation. Although the number of cases of "new" BPD currently prevails, some autopsies are still characterized by histopathological changes typical for the "old" form of the disease. A combination of classic and new features is also possible. When establishing a pathological diagnosis of BPD, it is essential to consider all specific histopathological changes that may indicate the presence and severity of the disease, as well as its role in thanatogenesis. This is important not only for the correct postmortem diagnosis of BPD, but also for the studying of various disease phenotypes.The article describes the main histopathological characteristic of various BPD forms, as well as methods of evaluating the simplified lung structure.