Fig. 3

Histopathological and immunohistochemical analyses. Panel (a) shows the Kaposi’s sarcoma–like morphology of the tumor. Angiogenic tumors were accompanied with spindle cells and sporadic inflammatory cell infiltrations. A few proliferating spindle cells and irregular cells were distributed inside and outside the neovessels, which presented with a deep dyed large nucleolus, a nuclear membrane coarsening with a distinct nucleolus, pleomorphism, and a few mitotic figures in the nuclei. Panels (b–e) show the immunohistochemistry results. The vessel walls showed positive staining for CD31, CD34, F8, and smooth muscle actin, which are specific markers for the endothelial cells of blood vessels (f, arrows). A few lymphocytes were confirmed by positive staining for CD3 and CD20 (g, h, arrows). The lesion was partly positive for Ki67 (about 5%), Leber congenital amaurosis (LCA), and CD99 (i–k, arrows). Individual cells were positive for myeloperoxidase(MPO) (l, arrow, ×10)