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Figure 4 Photomicrographs show: (A) Ramus intermedius stent; (B) non-intervened, diagonal branch of Case 1 patient. 1) Verhoeff tissue elastin stain, 2) Carstair’s fibrin stain, and 3) Sirius red collagen stain demonstrate: in A, severe in-stent restenosis and in B, diffuse cardiac allograft vasculopathy with similar-appearing intimal thickening consisting of fibrotic, collagen-rich, hypocellular matrix with adventitial thickening and fibrosis in both the stented and the non-intervened artery. 4) Immunohistochemical CD-68 staining (positive reaction color is brown) showing macrophage infiltration in both stented segment neointima (A) and non-intervened allograft vasculopathy (B). Photomicrographs (Verhoeff tissue elastin stain) of the circumflex artery stent (C) and non-intervened, marginal branch (D) of Case 2, and high-power view of the in-stent restenosis neointima (C’); both in-stent restenosis and marginal branch transplant vasculopathy demonstrate similar fibrotic hypocellular neointima proliferation.