Transcriptomic profiling and immuno-histological characterization of synovial biopsies in juvenile idiopathic arthritis (JIA) suggest two broad categories, with significant overlap with rheumatoid arthritis (RA).

T cell infiltration and thicker, M1-like macrophage rich synovial lining, and (ii) those with an M2-like macrophage transcriptomic signature, greater M2/M1-like macrophage ratios and thinner, M2-like macrophage rich synovial lining. Synovial features were not significantly associated with clinical parameters, likely due to group size and heterogeneity.