Immunohistochemical classification of acute leukemias using peripheral blood smears.

Immunophenotypic classification of the acute leukemias (AcL) is of well documented value in those of lymphoid or uncertain origin and of increasing importance in those of nonlymphoid origin. Most of these studies have been performed on viable cell suspensions. To study the efficacy of a simpler immunohistochemical approach to the classification of the acute leukemias requiring only peripheral blood smears, 15 AcL (including three CGL-BC) were studied using an immunoalkaline phosphatase method and a panel of anti-lymphoid and anti-myeloid monoclonal antibodies. Routine cytochemistries were also performed (Sudan black, PAS). Using immunohistochemistry, five cases marked as common ALL (four were undifferentiated by cytochemistry, one ALL), eight cases as ANLL (all ANLL by cytochemistry) and two cases marked only with anti-HLA-DR (AUL by cytochemistry). These results show that immunophenotypic analysis of AUL, ALL and ANLL can be successfully performed even when only air dried peripheral blood smears are available.