[Mixed blast crisis with the cytogenetic evidence of three clonal evolutions]

A 46-year-old man was diagnosed as having chronic myelogenous leukemia (CML) in chronic phase in Dec. 1985. In Dec. 1987, anemia and leukocytopenia progressed, and the percentage of blast cells increased in the bone marrow. The blast cells were lymphoblastoid and positive for TdT. It was treated as a lymphoid crisis with vincristine and prednisolone, and complete remission was achieved. However, the blasts (11%) were observed in the bone marrow in Mar. 1988, and the chromosomal analysis revealed 46, XY, t (2q-; 11q+), t (9q+; 22q-) in 13 out of 20 cells. In June, the percentage of the blasts increased again, but chromosomal analysis showed a different karyotype, 46, XY, t(2p-; 11p+), t(9q+; 22q-) which was observed in 9 out of 10 cells. Then, myeloblastoid cells increased rapidly in spite of the chemotherapy in Dec. 1988. The chromosomal analysis showed 46, XY, 2p-, 7q-, 9q+, 11p+, 22q- in all analyzed cells. The rearrangement of the bcr gene could be detected by the Southern blotting. The blasts were positive for CD7, CD11, CD13, CD33, CD36, CD41 and CD42, suggesting that the blasts had the surface phenotypes of both myeloid and megakaryocytoid-lineage. This is a case with the mixed blast crisis that changed from the lymphoid to the myelo-megakaryocytoid in nature, in which three clonal evolutions were observed during the clinical course.