ABSTRACT
Flow cytometry (FC) plays a very important role in diagnosis, subclassication, and post-treatment monitoring of hematologic neoplasms [1-26]. FC results allow one to choose in a timely manner the most appropriate further testing (such as FISH or PCR) to establish the denite diagnosis and to further characterize the malignant process. Multiparameter FC measures simultaneously several surface and/or intracytoplasmic markers on a single cell, allowing for accurate phenotypic characterization of analyzed population(s). While no single marker permits a de- nite lineage assignment, analysis with panels of antibodies allows for separation of hematologic tumors into very precise subtypes with dierent prognosis and treatment requirements, as dened by current World Health Organization (WHO) classication of hematopoietic and lymphoid tumors [27]. FC analysis can precisely dierentiate between B-and T-cell malignancies, between mature (peripheral) and precursor tumors, and among the latter, determine the myeloid or lymphoid lineage. In acute leukemias, the role of FC is not limited to identication of blasts, but expands to determine the lineage and specic phenotype, which oen prompts additional testing for nal subclassication of leukemia. For example, blasts (or blast equivalents) with high side scatter (SSC), positive CD117, CD13, and CD33 and negative HLA-DR raise the possibility of acute promyelocytic leukemia (APL), which can be conrmed by testing for PML-RARA. Myeloblasts with aberrant co-expression of CD19 and CD56 suggest acute myeloid leukemia (AML) with t(8;21) and B-lymphoblasts with aberrant expression of CD13 or CD33 suggest either BCR-ABL1 or ETV6-RUNX1 rearrangements. Availability of new markers (antibodies), new uorochromes, and improvement in instrumentation increases accuracy of FC studies and allows for identi-cation of a minute abnormal population among the majority of benign cells, evaluates minimal residual disease (MRD), and also expands FC applications into such disorders as myelodysplastic syndromes, paroxysmal nocturnal hemoglobinuria (PNH), and myeloproliferative neoplasms [9,18,26,28-34].
