T-cell acute lymphoblastic leukemia with co-expression of CD56, CD34, CD117 and CD33: A case with poor prognosis.

T-cell acute lymphoblastic leukemia (ALL) is an aggressive hematological malignancy, accounting for ~25% of all adult cases of ALL. We herein report a case of T-cell ALL exhibiting aberrant CD34, CD56, CD33 and CD117 expression in addition to T-cell markers, which did not respond to induction treatment. A 55-year-old woman was admitted to our hospital with a sore throat unresponsive to medication for 1 month. The laboratory examination revealed pancytopenia and the peripheral blood smear examination revealed blast cells. On flow cytometric analysis, the blast cells were found to be positive for cytoplasmic CD3, CD2, CD5, CD7, CD34, CD56, CD33 and CD117, and negative for myeloperoxidase, CD13, CD11b, CD15, CD19, CD79a, CD22 and CD10. The patient was diagnosed with T-cell ALL according to the 2008 World Health Organisation classification. The patient did not respond to Hyper-cyclophosphamide, vincristine, adriamycin and dexamethasone (CVAD) course A treatment and succumbed to the disease during Hyper-CVAD course B treatment. To the best of our knowledge, this is the first report of aberrant co-expression of the natural killer cell marker CD56, myeloid cell markers CD117 and CD33 and stem cell marker CD34 in a patient with T-cell ALL. This appears to be associated with an unfavorable outcome, despite the use of intensive chemotherapy.