B-Lymphoid and myeloid lineages biphenotypic acute leukemia with t(8;21)(q22;q22).

By analyzing the characteristics of morphology, immune phenotype, chromosome karyotype and clinical manifestations of six cases of B-lymphoid and myeloid lineages biphenotypic acute leukemia (BAL) with t(8;21)(q22;q22), a new subgroup of BAL was reported. Bone marrow eosinophilia (more than 5%) and pseudo-Chediak abnormalities were not found. Auer rods were also not identified in four of six cases. Immunophenotype revealed B-lymphoid and myeloid lineages positive, together with frequent and high expression of CD34 and CD33, and weak expression of HLA-DR. In addition to t(8;21) chromosomal translocation, deletion of Y chromosome and complex chromosome abnormalities were also found. Chemotherapy for myeloid and lymphoid leukemia simultaneously produced good response in the patients. BAL with t(8; 21)(q22; q22) might be a new subgroup of BAL, and it was suggested that the leukemia clone with t(8;21)(q22;q22) might have originated from an early phase of hematopoiesis, and AML1/ETO fusion gene might be related to differentiation of B lymphocyte.