Single Rhupus syndrome in a young man complicated by class IV lupus nephritis and pleural effusion: complete remission with cyclosporine-based therapy: a case report.

backgroundRhupus syndrome, the coexistence of rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE), is an uncommon overlap disorder. Severe SLE-type organ involvement-particularly class IV lupus nephritis and clinically significant serositis-has been reported less frequently than in isolated SLE, and optimal immunosuppressive strategies in patients with concurrent renal and hematologic disease remain poorly defined. CASE PRESENTATION: We describe a 28-year-old Arab man who presented with fatigue, weakness, knee effusion, and laboratory evidence of autoimmune hemolytic anemia with leukopenia and thrombocytopenia. Serologic evaluation revealed antinuclear antibodies, anti-double-stranded DNA antibodies, hypocomplementemia (low C3/C4), positive rheumatoid factor, and anti-cyclic citrullinated peptide antibodies, supporting an RA-SLE overlap. Urinalysis demonstrated proteinuria and microscopic hematuria, and kidney biopsy confirmed ISN/RPS class IV-G (A/C) diffuse lupus nephritis with full-house immunofluorescence. The patient initially improved on oral prednisolone, hydroxychloroquine, and mycophenolate mofetil but subsequently re-presented with orthopnea, severe fatigue, and fever. Imaging showed a large unilateral pleural effusion; pleural fluid was repeatedly exudative with negative microbiologic studies, and thoracoscopic biopsies demonstrated nonspecific chronic pleuritis, consistent with lupus pleuritis. Treatment was escalated with intravenous methylprednisolone pulses and intensified oral corticosteroids, although background therapy was continued. Cyclosporine was added primarily to address immune cytopenias in the setting of bone-marrow hypocellularity (approximately 20-40%) with preserved trilineage maturation and no evidence of abnormal or monoclonal proliferation. Clinical, hematologic, and renal remission was observed following treatment escalation, although causality cannot be inferred from a single case.

conclusionThis case illustrates that Rhupus syndrome may present with aggressive SLE-type organ involvement, including class IV lupus nephritis, pleural effusion, and immune cytopenias. In this patient, remission was observed after treatment escalation with a cyclosporine-based regimen; however, this should be interpreted as an observed association rather than evidence of causality or generalizable efficacy. Cyclosporine may represent a feasible immunomodulatory option in selected high-risk patients, provided careful monitoring for toxicity, particularly in the setting of lupus nephritis.