Figure 1.

Lung pathology in former COVID‐19 patients. Haematoxylin and eosin (H&E) staining showing characteristic pathological features of previous COVID patients (patient's code is at the top of each panel). Scale bars in all panels: 100 μm. (A) Diffuse alveolar damage (DAD) and parenchymal fibrosis. The pictures, taken from three different patients, show massive alveolar inflammation with almost complete occlusion of the alveolar lumen; delamination of pneumocytes, which appear grossly damaged and dystrophic; endoalveolar fibrin deposition; and fibrosis of the inter‐alveolar septa, which is massive in patient 183.21. (B) Thrombosis of a medium‐ (left) and small‐ (right) sized artery. The thrombotic artery on the left is surrounded by hyalin fibrotic tissue and flanked by congested small vessels. Thrombi are in different stages of organisation. (C) Perivascular inflammatory cap in a small thrombotic vessel. (D) Squamous metaplasia (pseudosyncytia) of the respiratory epithelium. Massive defoliation of the metaplasic alveolar cells, only a few of which maintain a cylindrical ciliated appearance. Massive congestion of the surrounding small vessels. (E) Presence of syncytial cells in two patients. In the upper panel, the syncytium is in the context of a delaminated alveolar structure and in proximity to an arteriole with a thickened wall and exfoliated endothelium.