Promyelocytic blast crisis of chronic myelogenous leukemia. A rare subtype associated with disseminated intravascular coagulation.

Two patients with chronic myelogenous leukemia (CML) developed blast crisis that morphologically appeared to be the microgranular variant of acute promyelocytic leukemia. This represented 8% of CML patients developing blast crisis from 1984 to 1993. Cytogenetic studies revealed translocation 15;17 in addition to translocation 9;22 that had been documented at initial diagnosis. Both patients had evidence of disseminated intravascular coagulation at the onset or during treatment of blast crisis, which was not documented in any other patients with CML blast crisis. One patient died of sepsis during intensive chemotherapy. The second returned to a chronic phase of the disease after therapy. Although rare, a promyelocytic blast crisis of CML can occur which, as in de novo acute promyelocytic leukemia, has a propensity to produce disseminated intravascular coagulation.