AB1044 CLINICAL AND IMMUNOLOGICAL FEATURES OF A SERIES OF PATIENTS WITH RHUPUS
Authors: F. Lozano Morillo, T. Almorza, P. Lavilla, M. Retuerto-Guerrero, B. A. Blanco Cáceres
Journal: Annals of the Rheumatic Diseases (2020)

Background: Since its first description in 1971 by Schur, many authors have discussed whether rhupus is an overlap syndrome between RA and SLE, a particular form of SLE with prominent and frequently erosive joint involvement,or if it is a distinct clinical and immunological entity. There are several published case series in medical literature describing the features of that uncommon syndrome that constitutes about 0.01-2% of all systemic rheumatic diseases. Objectives: To describe demographic, clinical and immunological features of a series of patients with rhupus syndrome and to compare them with previously reported series in the literature. Methods: Review of clinical records of patients attended in a Tertiary Care Rheumatology Unit that fulfil classification criteria for RA (either ACR 1987 or ACR/EULAR 2010) and SLE (either ACR 1997 or SLICC 2012). In addition, a manual search of patients with positivity for both anti-CCP (defined as &gt;3 UI/mL) and specific SLE antibodies (either anti-DNAds by IIF+- or anti-Sm by multiplex assay) was conducted. We excluded patients with known mixed connective tissue disease, drug-induced SLE as well as RA patients with anti-DNAds+ or anti-Sm+ without clinical features of SLE. Results: We identified 8 patients, all of them women (4 of Latin American origin, 3 Caucasians and 1 Arab) with a mean age at diagnosis of 35 years (range:19-63 years) and a mean duration of disease of 9 years (±10.5 years). RA and SLE were diagnosed simultaneously in 50% of cases (37.5% onset as RA and 12.5% as SLE, being the mean time between both diagnoses of 16.5 months in those cases). Immunological features of patients are summarized in Table 1. An erosive form of arthritis is present in 37.5%. As extra-articular involvement, 75% have skin lesions (photosensitivity, malar rash, oral ulcers and alopecia as major features) and 100% haematological alterations with lymphopenia (37.5% thrombopenia). Serositis (37.5%), renal (25% biopsy-proven lupus nephritis, 12.5% non-nephrotic proteinuria) and neurological (present only in one patient) involvement were less common findings. Most common therapies in our series were glucocorticoids (100% of cases, with a mean dose of 21.25 ± 13.5 mg/day at onset), antimalarials (87.5%) and methotrexate (87.5%). 50% of patients required biologic therapy (2 etanercept, 1 adalimumab, 1 rituximab) for inadequate disease control with conventional synthetic DMARDs. Conclusion: Prevalence of erosive arthritis in our patients is lower than previously reported, though as a limitation an imaging technique with a higher sensitivity for erosion detection than simple X-ray (such as US or MRI) was not available. Moreover, our series sample is small considering the low prevalence of this entity. The proportion of patients with simultaneous diagnosis of both RA and SLE is also higher (with a shorter interval between both diagnoses when this is not the case), so it is the proportion of patients receiving biologic therapy. The rest of clinical and immunological features were similar to previously described in other series. References: [1]Amezcua Guerra LM. Overlap between systemic lupus erythematosus and rheumatoid arthritis: is it real or just an illusion? J Rheumatol 2009; 36: 4-6. [2]Li J, Wu H, Huang X, Xu D, Zheng W, Zhao Y, et al. Clinical analysis of 56 patients with rhupus syndrome: manifestations and comparisons with systemic lupus erythematosus. Medicine 2014; 93(10). [3]Simón JA, Granados J, Cabiedes J, Ruiz Morales J, Alcocer Varela J. Clinical and immunogenetic characterization of Mexican patients with rhupus. Lupus 2002; 11: 287-292. [4]Tani C, D’Aniello D, Delle Sedie A, Carli L, Cagnoni M, Possemato N, et al. Rhupus syndrome: assessment of its prevalence and its clinical and instrumental characteristics in a prospective cohort of 103 SLE patients. Autoimmun Rev 2013; 12: 537-541. Disclosure of Interests: None declared