Lung pathology in COVID-19

The series of autopsies reported since the beginning of the pandemic have highlighted several patterns of lung damage, both isolated and combined. The factors influencing the occurrence of these different tissue responses to viral aggression by SARS-CoV-2 have not yet been determined. In asymptomatic patients or patients with respiratory symptoms who were not ventilated, lymphocyte pneumonia associated with type II pneumocyte atypical hyperplasia and a few hyaline membranes or focal lesions of acute fibrinous pneumonia have been observed. In critically ill patients, the most frequent pattern is diffuse alveolar damage with interstitial lymphoid infiltration, type II pneumocyte atypia and, very often, capillary or arteriolar microthromboses and/or endothelitis. The precise description of these lesions, which is becoming more and more consensual, makes it possible to understand the favourable effects of corticosteroid therapy in seriously ill patients and the evolution under ventilation towards fibrosis.Copyright © ERS 2021.