Overall, these data suggest that in PCNSL, putative endothelial cells lining the vascular wall are heterogeneous, and are formed by two cellular populations, expressing FVIII/ pStat3/CD133 (presumably originally they are vascular progenitor cells), as well as FVIII/CD20/CD133 (presumably originally they are tumor cells). Here, PROM1 is linked to neoplasm.