Recurrent arthritis as an unexpected side effect associated with azacitidine in a patient with myelodysplastic syndrome.

Introduction: Hypomethylating agents have confirmed efficacy for myelodysplastic syndrome and acute myeloid leukemia and are widely used. Although arthralgia is common side effect associated with hypomethylating agents, arthritis has not been reported previously.
Case Report: We present the first recorded patient with arthritis after azacitidine treatment. The patient we presented here had severe cytopenias requiring transfusion with erythrocyte and platelet suspensions, and a complete hematological response was obtained for myelodysplastic syndrome after three cycles of azacitidine (AZA) treatment. However, interestingly, after each AZA treatment cycle, the patient had recurrent attacks of arthritis.
Management and Outcomes: The episodes of arthritis were possibly acute flares of pre-existing crystal-induced arthritis, as exhibited with azacitidine treatments and were managed effectively with nonsteroidal anti-inflammatory drugs.
Discussion: Because it is a rare condition, clinicians should not overlook AZA as a possible cause of arthritis exacerbations when arthritis of unknown etiology develops in patients treated with AZA.