The myeloid leukemias are a heterogeneous group of diseases characterized by infiltration of the blood, bone marrow, and other tissues by neoplastic cells of the hematopoietic system. In 2006 the estimated number of new myeloid leukemia cases in the United States was 16,430. These leukemias comprise a spectrum of malignancies that, untreated, range from rapidly fatal to slowly growing. Based on their untreated course, the myeloid leukemias have traditionally been designated acute or chronic.
