Pathomorphology of lymph nodes in patients with severe SARS-CoV-2 infection observed in Primorsky Krai

Abstract

Introduction. When studying COVID-19 pathology, considerable attention is paid to the damage to the respiratory and cardiovascular systems, which are associated with the manifestation of the infection. Data on changes in the organs of the lymphatic system are yet scarce. To date, COVID-19 is sure to cause the dysfunction of the immune system; however, information about the damage to the lymph nodes is ambiguous. The aim of the study was to characterize morphological changes in the hilar lymph nodes of patients who died from a new coronavirus infection COVID-19 in Vladivostok in 2021. Materials and methods. A morphological study of the lymph nodes was performed in 20 patients who died from the new coronavirus infection, diagnosed in vivo using a PCR test. The controls were patients who did not have diseases of the hematopoietic and lymphoid tissue in their medical histories but who died a violent death. The material for histological examination was processed according to generally accepted methods. Results. In all patients, we identified lymphadenopathy with hypoplasia of lymphoid tissue of varying severity. In the cortex, lymphatic follicles were detected, mainly without light (germinal) centers, as well as follicles with a pronounced rarefaction of cells and exposure to the reticular stroma, with no visualization of the paracortical zone. According to the severity of reactive changes in the T- and B-dependent zones of the lymph nodes, we distinguished two types of lymphadenopathy: 1) mixed follicular type; 2) follicular involution with lymphoid depletion. Conclusion. Pathological changes in the hilar lymph nodes of the lungs in patients who died from COVID-19 indicated immunosuppressive effects of the SARS-CoV-2. The pathologic changes in lymph nodes manifested with lymphocytic depletion in T- and B-dependent zones. This indicates a deficiency of cellular and humoral immunity in moderate and severe COVID-19. Keywords: coronavirus infection, COVID-19, pathomorphology, lymph nodes, lymphocytic depletion, immunodeficiency