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. 2020 Jul 4;48:151562. doi: 10.1016/j.anndiagpath.2020.151562

Fig. 3.

Fig. 3

Immunohistochemical expression in lung of CK7 and CD34 in EPA versus LA or SS.

A–B. SARS-CoV-2 LA. The expression of CK7 (A) is still diffused and intense in the alveolar epithelium, but pneumocytes are often crowded in little unreadable aggregates, detached from the alveolar walls and poorly differentiable between type 1 and type 2. Numerous cellular debris are also stained affecting the legibility of the slide. Expression of CD34 in lung (B) allows the detection of numerous intraseptal vessels which are collapsed, difficult to distinguish and irregularly distributed, leaving doubt as to whether all this is an expression of the current illness or postmortem involution. C–D. Non SARS-CoV-2 LA. The number and characteristics of CK7-labelled epithelial cells are different from the sample shown in figure A; however, even this sample seems difficult to interpret given the extended detachment of pneumocytes, the variability in the intensity of cells positivity and the presence of colored cell debris. The expression of CD34 in the endothelium (D) allows a better morphological detail of the intraseptal vascular component. The capillaries are less collapsed than image B. E–F. SARS-CoV-2 EPA. The optimal preservation of the histological characteristics of the samples allows appreciating the histopathological features. In E the CK7 staining shows that the type 2 pneumocytes are widely magnified, clearly distinguishable from those of type 1 and minimally detached from the alveolar walls; the observed pattern is clearly different from image A, compared with those observable in surgical sample of patient not affected by SARS-Cov-2 (see image G). In F the CD34 staining shows the real distribution of the capillaries inside the alveolar septa which are still colonized by blood. G–H. CK7 (G) and CD34 (H) staining in SS of lung. (Digital histological slide; Nanozoomer S360, Hamamatsu; in the box at the bottom right of each image it is indicated the area of the sample highlighted in the image; the magnification of the image is indicated in the upper right corner.)