In 1999, Maniotis [50] et al. presented the term VM to explain the unique ability of extremely aggressive PAS (periodic acid–Schiff) positive and CD31 negative uveal melanoma tumor cells to form tubular structures and three-dimensionally patterned networks in cellular media, which “mimic” primitive vasculogenic networks formed by dedifferentiation of tumor cells. This evidence concerns the gene PECAM1 and neoplasm.