Morphological assessment of the lungs in post-COVID-19 syndrome: analysis of autopsy material

Abstract

The aim was to reveal the morphological features of the lungs in post-COVID-19 syndrome. Materials and methods: The material of the study was autopsy material – fragments of the lung tissue from 96 deceased (59 men and 37 women). During the lifetime, all patients had in anamnesis COVID-19 of varying severity, and after the treatment of this infection, they had various manifestations of respiratory failure until death. The average duration of the post-COVID-19 period was 148.6±9.5 days. Based on the severity of COVID-19 in anamnesis, all cases were divided into three groups. Group 1 included 39 cases with mild COVID-19 in anamnesis. Group 2 included 24 cases with moderate severity of COVID-19 in an¬amnesis. Group 3 included 33 cases with severe COVID-19 in anamnesis. Histological, histochemical, morphometric and statistical research methods were used. Results: Morphological features of the lungs in post-COVID-19 syndrome were the presence of pneumosclerosis; focal-diffuse immune cells infiltration; emphysematous and atelectatic changes; degenerative-desquamatic changes in the alveolar epithelium; metaplastic changes of connective tissue; dystrophic calcification; dystrophic, metaplastic and dysplastic changes in the epithelial layer of bronchial tree; hemodynamic disorders. Pneumosclerosis, focal-diffuse immune cells infiltration, alterative changes in the alveolar epithelium, emphysematous and atelectatic changes, hemodynamic disorders increased with an increase the severity of COVID-19. Metaplastic changes of connective tissue, dystrophic calcification, dystrophic, metaplastic and dysplastic changes in epithelial layer of bronchial tree did not depend on the severity of the infection. Conclusions: The changes identified by the authors help to explain pulmonary manifestations of post-COVID-19 syndrome. They should be the basis for the oncological alertness formation among doctors, the development of rehabilitation and treatment measures for such category of patients.