[Acute leukemia of ambiguous lineage with monosomy 7 and Philadelphia chromosome]

A 67-year-old female was admitted with a diagnosis of acute leukemia. Immature blasts did not show cytoplasmic granules and were POX(-), ES(-), and PAS(+). Flow cytometry of leukemic cells demonstrated positivity for CD7, CD10, CD19, CD13, CD34, HLA-DR, and coexpression of CD7 and CD34, CD10 and HLA-DR, and CD19 and CD13. Cytogenetic analysis demonstrated -7 and t(9;22)(q34;q11.2), and genomic studies demonstrated minor BCR/ABL chimeric mRNA and rearrangements of IgH and TCR. These findings indicated the clonal proliferation of leukemic blasts that expressed a mixed phenotype. Acute leukemia of ambiguous lineage was diagnosed, although the significance of the specificity of lineage markers remains unclear. The differential diagnosis included CML and B-ALL. The patient was treated according to Ph+ALL. However, the hematological response was poor, with persistent residual blasts and severe pancytopenia. The subsequent administration of imatinib mesylate led to a complication of heart failure, and the patient died on the 19th hospital day.