Childhood biphenotypic leukemia: detection of mixed lymphoid and myeloid populations in bone marrow specimens.

In a retrospective study, consecutive bone marrow biopsies and smears from 104 children with leukemia were analyzed for expression of lymphoid and myeloid lineage-associated features. Eighty-six cases were diagnosed as acute lymphoblastic leukemia (ALL), 14 cases as acute non-lymphocytic leukemia (ANLL), and one case as chronic myelogenous leukemia (CML). Finally, three children were classified as biphenotypic leukemia demonstrating mixed populations of lymphoid and myeloid blast cells from the onset of the disease. Thus, leukemia with a dual phenotype was assessed in 2.9% of all cases examined. The recognition of bilineage origin even by conventional methods such as morphology, cytochemistry and marker studies may be important for the selection of an effective treatment.