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. 2022 Feb 9;9:778489. doi: 10.3389/fmed.2022.778489

Figure 1.

Figure 1

Representative histopathological findings in autopsies from the first wave. (A) Lung tissue with diffuse alveolar damage in the exudative phase (hematoxylin and eosin (H&E), magnification 13 x, arrow: hyaline membranes). (B) Lung tissue with diffuse alveolar damage in the proliferative phase, which is defined by the presence of organization of the intra-alveolar and interstitial exudate, infiltration with chronic inflammatory cells, and interstitial myofibroblastic reaction. Proliferation and reactive atypias of type II cells are also noted (H&E, magnification 20 x). Inset: reactive pneumocytes type II, magnification 40 x). (C) Lung tissue with diffuse alveolar damage in the proliferative phase, showing an excessive collagen deposition (H&E, magnification 20 x). (D) Lung arterioles with endotheliitis, which is defined by the presence of subendothelial mononuclear inflammatory infiltrates (arrows) and damage of the endothelium (H&E, magnification 25 x) (E) Double immunohistochemistry [red: CD31 (endothelial marker), brown: CD68 (monocytic/macrophage marker)] of another representative case with endotheliitis shows endotheliitis of a venule in the lung with endothelial damage (arrow) and detachment with an associated mononuclear infiltrate (arrowhead) (H&E, magnification 28 x).