[Monocytic crisis in chronic myeloid leukemia: a case report]

We report a 17-year-old female with chronic myeloid leukemia (CML) who developed monocytic crisis. She was diagnosed as chronic phase of Ph1-chromosome positive CML at 14 years old. Three years after the diagnosis of the disease, she was admitted to the hospital because of low grade fever, lethargy and marked splenomegaly. Small dose of Ara-C relieved her symptoms and splenomegaly. Six months later, however, a marked leukocytosis over 70,000/microliters were observed, and the peripheral blood smear disclosed that about 80% of the leukocytes were relatively mature monocytoid cells. Chromosomal analysis revealed additional abnormalities (double Ph1, +8, +9, +19). Lysozyme levels in serum and urine were high and NAP score was elevated. These monocytoid cells expressed receptors for IgG-Fc and C3, phagocytic activity, and monocytoid antigens which were determined by monoclonal antibodies (MY4, Mo2, OKM5). Cytochemically, almost all of monocytoid cells were positive for peroxidase and naphthol-ASD-chloroacetate esterase (CAE), but the monocytoid cells positive for non-specific esterase were limited. These data suggested that this case was monocytic crisis in CML with proliferation of CAE positive monocytoid cells. Among several types of blast crisis, monocytic crisis is extremely rare condition. The definite monocytic crisis demonstrated by this case may support the hypothesis that target cells of CML are pluripotent hematopoietic precursors.