Abstract
There is a clear association between myelodysplastic syndrome (MDS)/chronic myelomonocytic leukemia (CMML) and autoimmune manifestations such as vasculitis. It is not clear if autoimmune manifestations in myelodysplastic syndrome are a cause or consequence. We describe two patients with polyarteritis nodosa and large vessel vasculitis, as presenting symptom of a myelodysplastic syndrome with excess blasts type 2 and chronic myelomonocytic leukemia respectively. Immunosuppressive treatment resulted in amelioration of the vasculitis with improvement of the myelodysplastic features in the first patient and rapid evolution to acute myeloid leukemia in the other patient. The association between MDS/CMML and autoimmune manifestations, such as vasculitis, emphasizes the role of autoimmunity in the clinical features and even pathogenesis of MDS/CMML.