TNF and musculoskeletal system disorder: However, it is important to note that the resident cells in the skin and joints differ significantly, and the clinical manifestations of musculoskeletal disorders and skin lesions exhibit substantial variation among individuals.33,36,37 Despite the common involvement of tumor necrosis factor (TNF) and the interleukin (IL)-23–IL-17 axis in the pathogenesis of both Ps and PsA, monotherapy targeting IL-17 or IL-23 has demonstrated high efficacy in Ps but not in PsA.