A 29 year-old male with chronic myeloid leukemia developed blastic crisis with B-cell surface markers after the treatment with carboquone during 3 years and 6 months. On admission, he had fever, arthralgia and hepatosplenomegaly. His peripheral leukocyte count was 83,800/mm3 with 69.6% lymphoblasts. In the bone marrow, 91.1% of nucleated cells were lymphoblasts. Surface markers analysis showed that these blasts had Leu12, Leu 14, HLA-DR and CALLA, but not membranous μ chain. He responded well to the treatment with vincristine and prednisolone, and was discharged.
