Paraneoplastic inflammation of the large vessels is a rare complication of myelodysplastic syndrome (MDS), and patients with MDS and systemic vasculitis have a poor prognosis. We present a 66-year-old male with MDS and large vessel vasculitis treated with azacitidine. Azacitidine administration improved his clinical symptoms, high fever and thickening of the arterial wall, and he achieved a complete bone marrow remission. However, 1 year later he showed progression of MDS. For MDS with vasculitis, intensive therapy, the same as that given to the high-risk group, should be considered and azacitidine administration may represent an efficacious treatment.
