Previous studies have shown that the neoplastic mononuclear stromal cells in GCTST are, at least in part, of osteoblastic lineage and express alkaline phosphatase (ALP), receptor activator of nuclear factor kappa B (RANK), runt-related transcription factor 2 (RUNX2), osteoprotegerin (OPG), and tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) [4,34]. This evidence concerns the gene RUNX2 and giant cell tumor of soft tissue.