Cytogenetic and ultrastructural features of de novo acute promyelocytic leukemia; The university of Chicago experience (1973-1978)

Of seven patients with de novo acute promyelocytic leukemia (APL) seen at the University of Chicago in a 6-year period, six had sufficient karyotypes to analyze. All six patients had the 15;17 translocation chromosome present in their leukemic cells. Four patients had typical hypergranular APL, but two patients required confirmation by transmission electron microscopy. In these two cases, the distribution of the granules was similar to the hypergranular type, but the granules were smaller than 250 nm, therefore below the limits of light microscopy resolution. Four of the six patients had clinical evidence of disseminated intravascular coagulation. It is important to make the diagnosis of APL initially as specific therapeutic choices exist.