[Covid-19 - radiologic and histologic features]

We here describe the current knowledge about the radiologic and histologic pulmonary features of covid-19, caused by SARS-CoV-2, and present lung histology from a case with fatal disease. Initial findings on computed tomography (CT) typically include peripheral multifocal bilateral ground-glass opacities, and correspondingly microscopic alveolar edema. This is followed by peripheral consolidations with air bronchogram and perilobular pattern on CT, signs of organizing pneumonia, corresponding to loose (potentially reversible) fibrosis. The posterior parts of the lungs and the lower lobes are typically more markedly affected. In severe disease with acute respiratory distress syndrome, thickened interlobular septa and crazy paving pattern appear on CT, which corresponds to histologic diffuse alveolar damage with, depending on the stage of the disease, features such as edema, hyaline membranes, reactive epithelium, inflammation, and fibrosis.