CD163 and rheumatoid arthritis: Considering that the oligoarticular form of PsA might belong to the SpA concept, both the present study and previous reports of our group indicate similar differences between SpA and RA as those described between PsA and RA: higher lining layer thickness in RA, but more pronounced vascularity, presence of polymorphonuclear cells and presence of the CD163+ macrophage subset in SpA.[14,16,19].