[Biphenotypic acute leukemia with Ph1 chromosome, M-BCR-, myeloperoxidase+, and CALLA+].

A 63 year-old woman was referred to our hospital because of fever and increased number of blasts in the bone marrow. On physical examination she had slight hepatomegaly but no splenomegaly. Laboratory tests disclosed a hemoglobin level of 8.5 g/dl; a WBC count of 13,200/microliter with 26% blasts; a platelet count of 51,000/microliter. A bone marrow aspirate was normocellular with 74% blasts and 37% blasts were stained positive for myeloperoxidase. Cell surface markers for HLA-DR, CD10, CD19, CD13, CD33 were positive. Karyotype analysis revealed 46, XX, t (9q+; 22q-) and 45XX, -7, t (9q+; 22q-). Southern analysis showed rearrangement of immunoglobulin heavy chain but not T cell receptor beta gene. Rearrangements in M-BCR were not detected with 5' or 3' bcr probes. After 2 courses of chemotherapy, blasts decreased to 7% with recovery of normal elements and 11 out of 20 metaphases of the bone marrow cells were normal karyotype. These findings suggest that this case was de novo Ph1 positive acute leukemia which demonstrated both lymphoid and myeloid features.