Flow cytometric immunophenotypic characterization of pediatric and adult minimally differentiated acute myeloid leukemia (AML-MO)

We reviewed the clinicopathologic and immunophenotypic profiles of 7 pediat ric and 11 adult minimally differentiated acute myelogenous leukemias (AML- MO). We also compared and evaluated myeloperoxidase in leukemic blasts usin g standard cytochemical and polyclonal antibody immunohistochemical stains. No distinctive clinical findings were noted in either patient group; howev er, thrombocytopenia typically was more prominent in adults. Adult AML-MO a lso was associated with an immature myeloid profile (CD34+, terminal deoxyn ucleotidyl transferase positive, CD13+, and CD33+), in contrast with pediat ric AML-MO, which usually lacked terminal deoxynucleotidyl transferase or C D34 but expressed bright CD33 with weak or negative CD13. Coexpression of t he T-cell-associated antigen CD7 was observed in both groups. Antibody immu nohistochemical stains were more sensitive than cytochemical stains for det ection of myeloperoxidase activity and a useful adjunct for establishing a diagnosis of myeloid leukemia in paraffin-embedded marrow tissues.