Clonal evolution of chronic lymphocytic leukemia to acute lymphoblastic leukemia.

A 38-year-old white man was diagnosed with B-cell chronic lymphocytic/prolymphocytic leukemia (CLL/PLL). The disease was unresponsive to a variety of chemotherapeutic regimes. One year after diagnosis, L3 blasts appeared in peripheral blood associated with more aggressive course. There was no change in the B-cell phenotype at that time, but cytogenetic analysis revealed the appearance of t(8;22)(q24;q11) and -21 superimposed on the original karyotype: 46,XY,+3,der(3)t(3;17)(p11;q12), t(11;14)(q13;q32),-17. These results indicate that the lymphoblastic transformation in our case emerged from the pre-existing B-lymphocytic clone.