Mixed phenotype acute leukemia of T/myeloid type with a prominent cellular heterogeneity and unique karyotypic aberration 45,XY, dic(11;17)

Introduction. A 26‐yr‐old male patient with mixed phenotype acute leukemia of T/myeloid type with prominent leukemic cell heterogeneity, and the presence of a so far unreported karyotype aberration in this type of acute leukemia 45,XY, dic(11;17)(11qter→11p11.2::17p11.2→17qter) is presented. Methods. Flow immunocytometry was performed by direct multicolor immunofluorescent technique on bone marrow aspirates. Cytogenetic analyses were performed using G‐banding method by direct preparation of unstimulated bone marrow cells and following 24 hours of culture in RPMI 1540 culture medium with 25% fetal calf serum at 37°C Results. The flow immunocytometry of bone marrow nucleated cells revealed the existance of three distinct blast cell populations with overlapping immunophenotypes. Predominant blast cell population had an early myeloid phenotype and aberrant expression of CD7 antigen (HLA‐DR⁺, CD34⁺, anti‐MPO⁺, CD117⁺, CD33⁺, CD13⁺, CD7^+low, cyCD3^?, TdT^?). The other two blast cell populations, smaller in cell diameter and less sizable in cell proportion, both shared the T‐lymphoid features. The patient was treated with ADE protocol (etoposide, cytarabine and doxorubicine). A complete remission was achieved and lasted 5 months. Conclusion. A case of MPAL with complex biological features, 45,XY, dic(11;17)(11qter→11p11.2::17p11.2→17qter) karyotype and an aggressive, therapy‐resistant clinical course, is presented.