LYMPHOID BLAST CRISIS OF B-LINEAGE PHENOTYPE WITH MONOSOMY-7 IN A PATIENT WITH JUVENILE CHRONIC MYELOGENOUS LEUKEMIA (JCML)

We studied a patient with juvenile chronic myelogenous leukemia (JCML) whose terminal course was characterized by transformation to acute ly mphoblastic leukemia. Karyotypic studies identified monosomy 7 in leuk emic myelomonocytic marrow cells during the chronic phase and in the l ymphoblasts during the transformation phase. Our ability to sustain th e transformed lymphoblasts in culture allowed us to characterize them further. CD19, HLA-DR, and CD10 were present, consistent with a pre-B acute lymphoblastic leukemia phenotype. CD14 (My-4) and CD13 (My-7) we re negative. Rearrangement of immunoglobulin heavy- and light-chain ge nes identified monoclonal populations of cells of the B lineage. This case provides further evidence that JCML is a clonal disease of plurip otent stem-cell origin.