Comparison of the СT patterns and pulmonary histology in patients with COVID-19

Aim. Compare radiological patterns of COVID-19 pneumonia with pulmonary histology in deceased patients. Materials and methods. The analysis of recent lifetime CT studies of deceased patients was performed with the identification of all existing and leading CT symptoms, including “ground glass”, “crazy paving”, consolidation, as well as the symptom complex (pattern) of organizing pneumonia. Based on the CT symptoms, we selected the target points for taking the specimens by 3-D reconstructions. At the autopsy the lungs were entirely fixed into the front and then marked on CT sections cut from 1 to 3 pieces that were placed in paraffin and processed according to the standard technique, stained with hematoxylin and eosin and fuchsin-facelina. The specimens were analyzed by identifying all available histology changes and selecting the leading one. Results. 45 targeted pieces of lung tissue were obtained from 14 deceased COVID-19 patients (7 men/ 7 women), with an average age of 77.1 ± 12.9 (49–90 years). In deceased patients with the presence of the "ground glass" symptom, in most cases (57.1%) revealed an increase in intra-alveolar cellularity, hyaline membranes, desquamation of the alveolar epithelium and infiltration of the interalveolar septum by lymphocytes, which corresponds to the exudative phase of diffuse alveolar damage (DAP). Mosaic histological changes with alternation of filled alveoli (intraalveolar edema, clusters of red blood cells, macrophages, lymphocytes) and air alveoli were detected from the areas of “crazy paving” zones. Several cases demonstrated interstitial edema and lymphoid infiltration of interalveolar partitions of different severity without their thickening. Areas of consolidation were histologically represented by extensive intraalveolar hemorrhages and / or typical zones of 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 DAP), as well as to distelectases. Conclusion. Comparison of CT patters and post-mortem pulmonary histology in COVID-19 deceased patients demonstrated that CT symptoms and patterns correspond to certain morphological changes of different phases of DAP.