Rationale: Dysregulated immune function in rheumatoid arthritis (RA) might lead to the development of myelodysplastic syndrome (MDS). Serum interleukin-6 (IL-6) concentrations are increased in both RA and MDS patients.
Patient concerns: A 58-year-old woman presented with severe RA. During a recent 8-month period, the patient experienced swelling in multiple joints, dizziness, and severe anemia. The symptoms responded poorly to oral corticosteroids and methotrexate (MTX). Even treatment of the patient's anemia by transfusion of red blood cells was ineffective. Laboratory tests showed high levels of IL-6 (214.24 pg/mL).
Diagnoses: Combining her medical history with clinical and laboratory parameters, especially those obtained by bone marrow aspiration, a diagnosis of RA with MDS was made.
Interventions: MTX was discontinued and the patient was given tocilizumab intravenously at a dose of 8 mg/kg every 4 weeks and oral corticosteroids (15 mg/QD).
Outcomes: The patient's serological, physical, and pathological abnormalities improved significantly.
Lessons: We report a case of RA with MDS successfully treated with tocilizumab. To our knowledge, this is the first case of an RA patient with MDS that was successfully treated with tocilizumab. In addition, our case emphasizes that IL-6 plays a critical role in the pathogenesis of RA with MDS. Tocilizumab might be an effective treatment for RA with MDS, especially in those with high levels of IL-6, elevated C-reactive protein, and severe anemia.