Fig. 6.

Luminal collection of mixed lymphoid cells along the right ventricular septum of an acutely ill COVID-19 patient.

A A large mass of leukocytes consisting of predominantly neutrophils (myeloperoxidase (MPO)), with rare macrophage, CD8, and CD4 positive T cells. Rare, focal SARS-CoV-2 replicating (CoV-19S) strand positive cell (yellow arrow) was detected within the mass and focally within the surrounding myocardium via RNAscope®. IL-6 was detected within the mass and surrounding endocardium and myocardium (brown). CD61-positive cells (brown) were interspersed diffusely throughout the inflammatory cell mass. B Graphical representation of C4D, IL-6, caspase-3 expression quantified in Aperio ImageScope software. Sample size were as followed: normal (n = 10); CMC (n = 14); viral myocarditis (n = 12: AAV2 (n = 3); CVB3 (n = 3); Inf B (n = 3); HCV (n = 3)); COVID (n = 21). *denotes statistical significance relative to normal control heart tissue (p < 0.05).