Ruphus: a rare and difficult-to-manage syndrome

Introduction: Rhupus syndrome is a rare coexistence of two immune-mediated rheumatic diseases, Rheumatoid Arthritis (RA) and Systemic Lupus Erythematosus (SLE). There is a combination of clinical and laboratory aspects of these, one of the overlaps being uncommon and sporadically documented. The prevalence of Rhupus syndrome has been estimated at about 0.01% to 2% of patients with rheumatic diseases. It was defined as erosive symmetric polyarthritis accompanied by SLE symptoms, in the presence of anti-dsDNA, anti-Sm and rheumatoid factor (RF) with or without anti-CCP. Having associated rheumatic diseases makes the diagnosis more difficult and challenging. Despite the coexistence of two pathologies, one disease usually has greater clinical expression, and treatment is more targeted towards it. Regarding treatment, one of the commonly associated side effects is pharmacodermia. Among pharmacodermias, Erythema Multiforme (EM) is one of the most life-threatening cutaneous drug reactions related to a number of drugs. Objectives: To report the case of a patient with RHUPUS Syndrome, who presented with MS in the upper and lower limbs and abdomen, associated with the use of Hydroxychloroquine, in addition to emphasizing the importance of diagnosing overlapping rheumatic diseases and the difficulty of managing them. Method: This is a descriptive study, the information was obtained through the review of the medical record and interview with the patient. Results: A 24-year-old woman reported symmetrical polyarthritis of the wrists, fingers, elbows, knees and feet for 1 year. She denied other complaints. Physical examination: malar rash, arthritis of the right knee. Positive shake of hands and feet. Previous use of methotrexate, leflunomide and azathioprine, without any improvement of the condition. At the time of consultation, she was taking tofacitinib 5mg every 12 hours and prednisone 5mg/d, with partial improvement of initial symptoms. The patient had a blood count with leukopenia (less than 4,000), low C4, increased ESR and CRP, high reacting RF and anti-CCP, fine speckled nuclear FAN (1/320), anti-DNAds and anti-Sm reactors. US power Doppler of the right hand with diffuse synovitis of the carpal bones and erosions in the styloid process. ECHO: mild pericardial effusion and EF 75%. She was then diagnosed with RHUPUS syndrome and started on hydroxychloroquine 400mg/d. After 4 days, the patient evolved with erythematous rash in lower and upper limbs and abdomen after the introduction of medication, in addition to dysphagia. In this case, the diagnosis of MS was based on clinical presentation and therapeutic evidence, with complete remission of lesions after drug discontinuation. At the moment, the patient is taking upadacitinib 15mg/d, without corticotherapy and asymptomatic. Upadacitinib was chosen because the patient showed partial improvement of initial symptoms only with tofacitinib; both are oral Janus kinase inhibitors (anti-JAK). Conclusion: This study showed the diagnostic difficulty of RHUPUS syndrome as well as the challenges regarding treatment. In this case, the patient presented with MS, which resolved after discontinuation of the medication, as well as complete remission of the rheumatologic manifestations related to RHUPUS syndrome, after initiation of upadacitinib.