Abstract
We reported a case of Ph1-positive acute leukemia whose blast cells had both lymphoid and myeloid phenotype. The leukocyte count of peripheral blood was 33.4 × 104/cmm. Seventy- one percent of the cells were blasts with myeloid appearance (FAB, M2 type). Bone marrow was occupied with 71.8% blasts cytochemically positive for myeloperoxidase. Cytogenetic marker was Ph1 chromosome. Surface markers analysis revealed that the blast cells were positive for Ia, CD 19 (B4), CD10 (CALLA), CD33 (My9). J5 and My9 were simultaneously expressed on the same blast cells by two-color flowcytometry. In addition, rearrangement of heavy chain of immunoglobulin gene was detected. This acute leukemia was considered to occur at the level of uncommitted multipotential progenitor cell of both lymphoid and myeloid cells. He was treated with doxorubicin, vincristine, L-asparaginase, and prednisolone, and obtained complete remission.
