ELECTRON MICROSCOPIC STUDY OF THE LUNGS OF DECEASED PATIENTS WITH COVID-19

Abstract

TYPE: Late Breaking Abstract TOPIC: Imaging PURPOSE: To visualize the ultrastructural pulmonary damage in patients deceased from SARS-CoV-2 infection. METHODS: An observational study was performed from March 15th 2020 to December 31st 2021 at the Fundación Jiménez Díaz (Spain). Epidemiological and analytical data were obtained. Ultrasound-guided post-mortem percutaneous biopsies were performed with a 33-mm 14G automatic gun, for their histological examination, and for electron microscopy observation. RESULTS: Five patients (80% women) were included. Mean age was 86 years (84-88); 60% had two medical conditions (HT, DM, obesity). The median length of hospitalization was three days (range 1-16). Percutaneous biopsies were performed at the bedside in the first hour after death. Diffuse alveolar damage was present in all patients, with increased alveolar wall thickness. Loss of lung structure and cell lysis and vacuolization were observed in endothelial cells and in pneumocytes of both types. In type II pneumocytes, images consistent with coronavirus viral particles included inside vesicles as well as extracellular particles close to membrane remnants, were identified. Although every patient received at least one prophylactic dose of heparin, 66% had a DD above 3,000 μg/L. Fibrin microthrombi, mainly in alveolar capillaries, were identified in all patients, with no signs of vasculitis. CONCLUSIONS: Pulmonary microthrombosis was observed in all patients, in spite of anticoagulant treatment. A more detailed study under EM showed frequent formation of hyaline membranes as well as severe cellular damage in both type II pneumocytes and endothelial cells. CLINICAL IMPLICATIONS: Microthrombosis seems to be present from the onset even in patients treated with anticoagulation. DISCLOSURE: No significant relationships. KEYWORD: Electron microscopic