Single step immunophenotyping of acute leukemias not classifiable by standard morphology and cytochemistry: a practical approach.

BACKGROUND: Immunophenotyping is at present a useful aid and often an essential step for correct diagnosis of acute leukemia and for this purpose some investigators have proposed several immunomarker panels. This approach is particularly important in the differential diagnosis of acute leukemias not classifiable by standard morphology and cytochemistry. METHODS: We have tested peripheral blood and/or bone marrow samples from 125 patients not classifiable by FAB criteria. In all the cases, the reactivities of the same panel of 17 monoclonal antibodies were analyzed by flow cytometry, using both single and double fluorescent labeling. RESULTS: Of the 125 patients investigated, 75 (60%) were classifiable as ALL, 58 as B-lineage ALL and 17 as T-lineage ALL; 33 (26.4%) as AML, of which 2 M7; 6 (4.8%) as biphenotypic and 11 (8.8%) as immunophenotypically undifferentiated. CONCLUSIONS: From a critical analysis of our cases and a review of the literature, we suggest that a panel of 9 monoclonal antibodies (CD2, CD5, CD7, CD10, CD19, CD20, CD13, CD33, CD41), is sufficient for reliable, rapid and reasonably low cost typing of acute leukemia, useful for an immediate therapeutic decision.