Hyperdiploid acute myeloid leukemia. Relationship between blast size and karyotype demonstrated by fluorescence in situ hybridization.

Hyperdiploidy is a rare finding in acute myeloid leukemia (AML), and the cases described so far showed characteristic large and bizarre blasts. We further demonstrate this morphologic/karyotypic relationship in a case of hyperdiploid AML by fluorescence in situ hybridization. Together with previous observations, we propose that in myeloid leukemias, increase in DNA content is accompanied by a corresponding increase in blast size. If large and bizarre blasts are shown on morphologic analysis, polyploid metaphases on cytogenetic preparations should also be analyzed, as they may be derived from these cells.