Promyelocytic blast crisis in chronic granulocytic leukemia with 15;17 translocation.

A patient with Philadelphia chromosome Ph1-positive chronic granulocytic leukemia (CGL) developed an acute transformation associated with a hemorrhagic diathesis and bone marrow infiltration by hypergranular promyelocytes and blasts. Cytogenetic analysis of bone marrow metaphase cells at transformation showed a t(15;17) superimposed upon the Ph1-positive cell line. These findings suggest a critical relationship between the t(15;17) and arrest of myeloid leukemic cell differentiation at the promyelocyte stage.