Rivellese F, et al. - Authors sought to establish the role of mast cells (MCs) in rheumatoid arthritis (RA) by analyzing their presence in the synovium of treatment-naive patients with early RA and their association and functional relationship with histological features of synovitis. Results showed that early RA patients are identified by synovial MCs, with a severe clinical form of synovitis characterized by the presence of ectopic lymphoid structures. Findings suggested an association of high synovial MC counts with local and systemic inflammation, autoantibody positivity, and high disease activity.