TNFSF13B and synovial sarcoma: The principal pro-inflammatory cytokines identified in SS patients are the interferons α and γ (IFNα, IFN γ), interleukin 17 (IL-17), interleukin 7 (IL-7), Tumor necrosis factor α (TNF-α), interleukin 1β (IL-1β), and B-cell activating factor (BAFF) [41,42,43].