Insights into the pathophysiology of post-COVID lung disease from the perspective of histopathology.

Abstract

The COVID-19 pandemic has caused a broad range of respiratory complications. Among the spectrum of COVID-associated pulmonary conditions, severe bilateral pneumonitis that might progress to acute respiratory distress syndrome (ARDS) represents the most critical manifestation. A substantial proportion of survivors of severe COVID-19 continue to experience persistent respiratory symptoms and functional limitations. These findings are referred to as post-acute sequelae of COVID-19 (PASC). These residual post-COVID lung abnormalities are mechanistically linked to the structural changes of acute lung injury, but also to persistent systemic inflammatory signatures, and are reflected in a range of histopathological patterns, including pulmonary fibrosis, hyperinflammation, angiopathic and immunothrombotic tissue responses. This review focuses on the current knowledge of the pathogenesis and pathophysiology of post-COVID lung disease. We also schematically delineate the broad spectrum of post-COVID lung disease and explain the underlying pathomechanisms.