A Narrative Literature Review Comparing the Key Features of Musculoskeletal Involvement in Rheumatoid Arthritis and Systemic Lupus Erythematosus

Although the clinical approach to the management of musculoskeletal manifestations in systemic lupus erythematosus (SLE) is often similar to that of rheumatoid arthritis (RA), there are distinct differences in immunopathogenesis, structural and imaging phenotypes and therapeutic evidence. Additionally, there are few published comparisons of these diseases. The objective of this narrative literature review is to compare the immunopathogenesis, structural features, magnetic resonance imaging (MRI) and musculoskeletal ultrasound (MSUS) studies and management of joint manifestations in RA and SLE. We highlight the key similarities and differences between the two diseases. Overall, the literature evaluated indicates that synovitis and radiographical progression are the key features in RA, while inflammation without swelling, tendinitis and tenosynovitis are more prominent features in SLE. In addition, the importance of defining patients with RA by the presence or absence of autoantibodies and categorizing patients with SLE by synovitis detected by musculoskeletal ultrasound and by structural phenotype (non-deforming, non-erosive arthritis, Jaccoud's arthropathy and 'Rhupus') with respect to joint manifestations will also be discussed. An increased understanding of the joint manifestations in RA and SLE may inform evidence-based clinical decisions for both diseases.