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

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 longterm 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 a rise from transformation of a pluripotent precursor cell, which could differentiate to both myeloid and NK cell lineages. Copyright (C) 1996 Elsevier Science Ltd