Activity of single-agent decitabine in atypical chronic myeloid leukemia.

Atypical chronic myeloid leukemia is a rare entity that presents diagnostic and therapeutic challenges. Traditionally utilized therapeutic agents such as hydroxyurea or interferon result in a median survival of approximately two years, thus warranting identification of better options. We report a 49-year-old Caucasian female, who presented with extreme leukocytosis (white blood cells of 148,300/µL) with left shift, severe anemia, and thrombocytopenia. Following a diagnosis of atypical chronic myeloid leukemia, she was started on intravenous decitabine. She subsequently developed paraneoplastic vasculitis of large arteries, which responded to high-dose glucocorticoid. Decitabine therapy resulted in an excellent hematologic response, transfusion independence, and successful transition to an allogeneic peripheral stem cell transplantation. However, the patient subsequently succumbed to the complications of acute graft-versus-host-disease. This case illustrates an association between atypical chronic myeloid leukemia and steroid-responsive paraneoplastic vasculitis and highlights the single-agent disease activity of decitabine in atypical chronic myeloid leukemia, which may be utilized as a bridging therapy to allogeneic stem cell transplantation.