Blast phase of chronic myeloid leukemia presenting lymphoid phenotype with a chronic phase of extremely short duration.

Chronic myeloid leukemia (CML) is generally diagnosed in the chronic phase. We have recently encountered two CML-blastic phase (BP) cases, a 71-year-old woman and a 74-year-old man, who resembled de novo acute leukemia. The complete blood count was normal at least 11 and 13 months before the presentation, respectively. The leukemic cells showed predominant lymphoid phenotype. The blasts and granulocytes were positive for BCR-ABL, indicative of CML-BP. Both patients were successfully treated with prednisone and vincristine, followed by Imatinib. Our cases indicate rare presentations of CML-BP with an extremely short chronic phase. Ph-positive de novo acute leukemia should be carefully distinguished from CML-BP.