A Targeted Study of Pulmonary Pathology and Chest Computed Tomography (CT) Findings in COVID-19

Introduction. In the context of the COVID-19 pandemic, one of the most important diagnostic methods is highresolution computed tomography of the lungs (HRCT), which is highly sensitive for diagnostics of viral pneumonia. Because of a variety of radiological changes in the lungs at different periods of the disease, it became necessary to compare the changes detected by HRCT with morphological features of the disease. The aim of the research is to compare the HRCT patterns and histological changes in the lungs in the deceased with COVID-19. Material and methods. We analyzed 45 pieces from 14 deceased with COVID-19 (7 men/7 women), with an average age of 77.1 ± 12.9 (49-90 years), which underwent HRCT no more than 5 days before death. On the fixed whole lungs, tissue sites were selected, according to the target localization selected by HRCT with 3- D reconstruction. The leading HRCT patterns such as 'ground glass' opacities, “crazy paving”, consolidation, and symptoms typical for organizing pneumonia were the points of interest. We performed routine hematoxylineosin stains for histopathologic evaluation. Results. “Ground glass” opacities in the majority of cases (57.1%) corresponded to an acute phase of diffuse alveolar damage (DAD) (intraalveolar edema, hyaline membranes, cellularity, interstitial infiltration). Mosaic histological changes with alternation of filled alveoli (intraalveolar edema, clusters of red blood cells, macrophages, lymphocytes, fibrin) and aerated alveoli were detected in the areas of “crazy paving” zones. Areas of consolidation were histologically represented by extensive intraalveolar hemorrhages and/or hemorrhagic infarcts in 45.5% of cases. Perilobular consolidation, subpleural cords, symptoms of “halo” and “reverse halo”, which we considered as part of the symptom complex of organizing pneumonia in 43% of cases morphologically corresponded to organizing pneumonia (the proliferative phase of DAD) and to distelectases. Conclusion. Herein, we established the correspondence of DAD histology phases with/ or without pulmonary intravascular coagulopathy to the main HRCT-patterns of viral pneumonia. The results obtained can be used to determine therapeutic tactics at different phases of viral pneumonia in COVID- 19.