Rhupus: a systematic literature review

"Rhupus" or "rhupus syndrome" is a poorly described and underdiagnosed disease in which features of both rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE) appear in the same patient, most often sequentially. The SLE-related involvement is usually mild, dominated by hematological abnormalities and skin, serosal and renal involvement. The natural history of rhupus arthritis follows an RA-like pattern and can progress towards typical inflammatory erosions, deformations and disability. Despite the lack of consensus on the definition of rhupus and on its place in the spectrum of autoimmunity, a growing number of studies are pointing towards a true overlap between RA and SLE. However, the inclusion criteria employed in the literature during the last 4 decades are heterogeneous, making the already rare cohorts and case reports difficult to analyze. Because of this heterogeneity and due to the rarity of the disease, the prevalence, pathophysiology and natural history as well as the radiological and immunological profiles of rhupus are poorly described. Moreover, since there is no validated therapeutic strategy, treatment is based on clinicians' experience and on the results of a few studies. We herein present a systematic literature review to analyze the clinical and laboratory data of all reported rhupus patients and to provide up-to-date information about recent advances in the understanding of the pathophysiological mechanisms, diagnostic tools and treatment options.