A child case of CD34+, CD33−, HLA-DR−, CD7+, CD56+ stem cell leukemia with thymic involvement

Abstract It has been reported that the CD56 + /CD7 + /CD3 − phenotype of natural killer (NK) cells develop from the CD34 + /HLA-DR − bone marrow (BM) mononuclear cell population in long-term BM culture (LTBMC). An HLA-DR − /CD33 + /CD56 + /CD16 − myeloid/natural killer cell acute leukemia has been described. We report here a 7-year-old boy who developed stem cell acute leukemia with superior vena cava syndrome secondary to thymic involvement. Surface marker analyses revealed that the leukemia cells showed CD34 + /HLA-DR − /CD33 − /CD7 + /CD56 + phenotype. When stimulated with phorbol ester in vitro the leukemic cells morphologically differentiated to myeloid cells developing CD13, CD15 and CD56 antigens. Our results suggest that CD34 + /HLA-DR − /CD7 + /CD56 + stem cell leukemia may arise from transformation of a pluripotent precursor cell, which could differentiate to both myeloid and NK cell lineages.