We describe the case of a young man with therapy-naive chronic myeloid leukemia who did not initially have any peripheral blood or bone marrow excess blasts but presented with extramedullary myeloid blast crises involving the central nervous system and multiple lymph nodes. Conventional cytogenetic tests were positive for t(9;22)(q34:q11) as well as for trisomy 8, 14 and 21 and del(16q). The patient’s peripheral blood and bone marrow were positive for the BCR-ABL oncogene when analyzed by fluorescence in situ hybridization and polymerase chain reaction. He achieved good clinical, radiological, cytogenetic and molecular response to acute myeloid leukemia induction chemotherapy combined with 16 doses of triple intrathecal chemotherapy and oral dasatinib (second-generation tyrosine kinase inhibitor) treatment. Due to his poor general condition, he was treated with 24 Gy of whole-brain radiation therapy, as allogeneic stem cell transplantation was not feasible. Although extramedullary CNS blast crises are usually associated with a very poor outcome, our patient remains in complete cytogenetic and molecular remission, on single-agent dasatinib, 4 years after the diagnosis with no current evidence of active extramedullary disease. This suggests that dasatinib has a role in controlling not only chronic-phase chronic myeloid leukemia, but also its CNS blast crisis.

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