Pathology of covid-19

ABSTRACT

In covid-19, the basic lesion is interstitial pneumonia presenting as diffuse alveolar damage. However, unlike DAD/ARDS from other causes, there are several rather specific histopathological features in the lung parenchyma, there is frequently a combination of all stages of DAD - acute, subacute, and chronic;platelet, and fibrin-rich thrombi are found in all types of pulmonary vessels - microcirculation, arteries, and veins, with formation of lung infarctions;the inflammation has a marked hemorrhagic character - alveolar bleeding;presence of atypical activated type II pneumocytes;unusual ("naked") megakaryocytes within the microvasculature;presence of virions in lung cells;and tendency to bacterial or fungal superinfection. In the heart, no specific, reproducible histopathology of covid-19 myocardial injury has been shown at autopsy and the rates of fatal myocarditis are low.