Case Report: Rhupus (the Association of Systemic Lupus Erythematosus and Rheumatoid Arthritis): about 2 Cases

Introduction: The association of systemic lupus erythematosus and rheumatoid arthritis (rhupus) is a rare clinical condition. Throughout the world, 287 cases of Rhupus have been described. We report two new observations of two patients who presented predominantly distal erosive polyarthritis with positive anti-Sm antibodies in one case and SmRNP in the other case. Observations: Case 1: 37 years old patient, with a recent diagnosis of pulmonary tuberculosis. She has since 8 months an inflammatory, bilaterally and symmetrical polyarthralgia without deformation or ankylosing synovitis, associated with malar erythema without other abnormalities. Immunological tests showed: positive Rheumatoid factor at 158 IU/ml, positive Anti-CCP at 550 IU/ml, and positivity of antinuclear at 1/1280 nuclear fluorescence with a strong presence of anti-Sm >8 IU/ml. The diagnosis of rhupus was concluded, without serious visceral involvement. Case 2: A 28-year-old patient, married with 3 children, with bilateral, symmetrical, deforming and chronic polyarthritis affecting large and small joints, which had been evolving for over 5 years without cutaneous abnormality associated. Paraclinical investigations showed: a biological inflammatory syndrome. Immunology was positive, with rheumatoid factors at 78 IU/ml, anti-CCP at 561 IU/ml, antinuclear antibodies at 1/1280 with positive anti-SmRNP and anti-SSA/Ro52, and a positive direct Coombs test. Joint ultrasound revealed tenosynovitis of the extensors and common flexors of the fingers, erosions and synovitis of multiple PPIs. The diagnosis of rhupus was based on the presence of 10 ACR criteria for RA and 8 ACR/EULAR 2019 criteria for SLE. Conclusion: Rheumatoid arthritis is a rare autoimmune disease combining features of both systemic lupus erythematosus and rheumatoid arthritis in the same patient, often sequentially. Despite a growing number of case reports and series, a consensus on the classification of SLE arthritis is still lacking, and diagnostic criteria for rhupus do not exist. These cases of rhupus must be recognized, as the vital and/or functional prognosis may be different from SLE alone or isolated RA.