Myelomastocytic Blast Cell Crisis in Resistant Tyrosine Kinase Inhibitor Chronic Myelogenous Leukemia: Case Report and Review of Literature

We present the clinical case of a 29-year-old male with a diagnosis of chronic myeloid leukemia (CML) in high-risk chronic phase since February 2010. He started treatment with imatinib at a dose of 400 mg obtaining a hematologic response early but without reaching a cytogenetic response in month 18. Then, dasatinib was prescribed. The BCR-ABL transcription level of 58% was documented. It was decided to start treatment with nilotinib but in March 2017 we diagnosed a progression to blast crisis (BC) of myeloid origin with a bone marrow study that documented 72% of blasts with normal karyotype, also very striking, the concomitant skin infiltration, bone lesions of lytic type and hypercalcemia that required the use of zoledronic acid as an emergency. At the end of chemotherapy induction with 7 + 3 (seven days of cytarabine and three days of idarubicin) chemotherapy associated with bosutinib for 14 days and after several infectious complications, we documented a percentage of blasts by flow cytometry of 29% in the bone marrow and the existence of 46% of cells with basophilic characteristics versus mast cells. A basophilic transformation was suspected versus aggressive systemic mastocytosis with a clonal, nonmastocytic hematological disorder. Levels of serum tryptase and mutation D816V C KIT were requested, which were not possible to perform. Treatment with CLAG-M was proposed, however, the patient died early with hyperleukocytosis and severe thrombocytopenia with central nervous system bleeding.