[Cytogenetic feature of acute biphenotypic leukemia]

Since the diagnostic criterion of acute biphenotypic leukemia(BAL) was recommended by European Group for the Immunological Characteristics of Leukemia (EGIL) in 1995, the reports on cytogenetic feature of BAL can be seen in homeland and outside, but the case numbers in the reports were low. This study was designed to explore the cytogenetic feature of BAL.

The FAB subsets of fifty-six BAL cases were established by morphology/cytochemistry; and surface immunophenotyping was performed by flow cytometry using a broad panel of lymphoid- and myeloid-associated monoclonal antibodies through directly immunofluorescence technique; karyotype analysis was carried out by reverse heating giemsa (RHG).

The data from our study showed that the cytogenetic feature of BAL possess a certain degrees of heterogeneity. In all cases, 44.4% were normal karyotype, 55.6% were clonal chromosome aberration. In clonal chromosome aberration, Ph chromosome abnormality occurred 23.2% and in matched AML controls was 0%. Ph chromosome abnormality occurred 39.3% in group of coexpression of myeloid and B lymphoid lineage; Ph chromosome aberration occurred 0% in group of coexpression of myeloid and T-lymphoid lineage. The other associated clonal chromosome aberrations were t (8; 21), t (15; 17), t (9; 22), inv (16), and not associated clonal chromosome aberration were t (12; 17), t (14; 15), t (3; 6), +21, complex aberration, etc.

The generalized abnormality of t (9; 22) in BAL indicate that the blast cells of BAL were derived from earlier hematopoietic stem/progenitor cell.