CD68 and rheumatoid arthritis: Histology combined with RNA sequencing (RNA-seq) of synovial biopsies from early RA patients allowed defining of three different “pathotypes” of MP: lympho-myeloid (CD20 B cell aggregate rich), diffuse myeloid (CD68 rich in the lining or sub-lining layer but poor in B cells), and pauci-immune fibroid (paucity of immune-inflammatory cell infiltration) [35].