PATHOLOGICAL FEATURES OF COVID-19 INFECTION: A POST-MORTEM APPROACH BASED ON AN EXTENSIVE AUTOPTIC SAMPLING PROTOCOL

Introduction: Coronavirus disease 19 (COVID-19) is caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) Due to the resultant serious public health crisis, the attention of the scientific community was turned towards COVID-19. Despite the importance of post-mortem studies in the understanding of pathophysiology, autopsies have been generally discouraged by government regulations. This study consists of the pathological analysis of samples of select organs obtained during autopsies of deceased COVID-19 subjects, performed by forensic pathologists of the Unit of Legal Medicine of Pavia. Aims: to describe COVID-19 pathology across different tissues to clarify the disease’s pathophysiology. Materials and methods: autoptic cases were selected based on the presence of SARS-CoV-2 infection. Lungs, kidneys, hearts, and brains from nine COVID-19 autopsies were compared by using antibodies against SARS-CoV-2, macrophages-microglia, T-lymphocytes, B-lymphocytes, and activated platelets. Alzheimer’s Disease pathology was also assessed. PCR techniques were used to verify the presence of viral RNA in brain. Results and discussion: we selected 9 COVID-19 cases. They had a short clinical course (0–32 days) and their mean age was 77.4 y/o. Hypoxic changes and inflammatory infiltrates were present across all tissues. The lymphocytic component in the lungs and kidneys was predominant over that of other tissues (p < 0.001), with a significantly greater presence of T-lymphocytes in the lungs (p = 0.020), which showed the greatest presence of viral antigens. The heart showed scant SARS-CoV-2 traces, foci of activated macrophages, and rare lymphocytes. The brain showed scarce SARS-CoV-2 traces, prominent microglial activation, and rare lymphocytes. The pons exhibited the highest microglial activation (p = 0.017). Microthrombosis was significantly higher in COVID-19 lungs (p = 0.023) compared with controls. The most characteristic pathological features of COVID-19 were an abundance of T-lymphocytes and microthrombosis in the lung and relevant microglial hyperactivation in the brainstem. Data obtained in this study could potentially offer a better understanding of how this recently identified pathology affects the human body and specific organs, with the goal of improving clinical management of affected patients and improving strategies for disease prevention.