Evolutional change of karyotype with t(8;9)(p22;p24) and HLA-DR immunophenotype in relapsed acute myeloid leukemia.

The rare recurrent translocation of (8;9)(p22;p24) with PCM1-JAK2 fusion was recently characterized in diverse hematological malignancies. Most of them are atypical chronic myeloid leukemia (CML) or other myeloproliferative disorders (MPD), and are predominantly in the male. We report a female patient with acute myeloid leukemia (AML) initially presenting with normal karyotype and negative HLA-DR expression who achieved complete remission after standard chemotherapy. The disease relapsed 7 months later with cytogenetic change of t(8;9)(p22;p24). Flow cytometry analysis showed evolutional change of immunophenotype from negative to positive HLA-DR expression and fluorescence in situ hybridization (FISH) analysis demonstrated a PCM1-JAK2 fusion gene. We speculate that the cytogenetic change of t(8;9)(p22;p24) may induce HLA-DR immunophenotypic switch and a coordination of the two evolutional changes may play a role in leukemic cell progression.