Flow cytometric evaluation of B-cell lymphoid neoplasms

Evaluation of B-lymphocytes is one of the most well-established clinical applications of flow cytometric immunophenotyping. Using this technique, B-lymphocytes are recognized by expression of lineage-associated antigens; the profile of antigens expressed identifies B-cells at different stages of maturation and belonging to different biologic compartments; neoplastic B-cells can be distinguished from reactive B-cells by demonstration of immunoglobulin light chain restriction or phenotypic aberrancy; and the phenotype of the neoplastic cells can be used to identify one of the distinct disease entities recognized in the World Health Organization classification [1]. However, because of overlapping phenotypes, flow cytometric immunophenotyping is often used in conjunction with other studies as part of a multiparametric approach to the diagnosis of B-cell lymphoid neoplasms [1]. This article addresses general principles of the flow cytometric evaluation of B-cell lymphoid neoplasms, followed by discussion of how flow cytometric data can assist in determining a list of diagnostic possibilities and directing additional testing.