CD163 and glioma: Regardless of the cellular subtypes comprising gliomas, a common theme in glioma disease progression is robust infiltration of immune cells within the tumor microenvironment, resembling a state of chronic inflammation, with CD68+ microglia and CD163+ bone marrow-derived macrophages being the most abundant immune cell types, and the greater the percentage of CD163+ cells, the poorer the prognosis [19,20].