Critical analysis and diagnostic usefulness of limited immunophenotyping of B-cell non-Hodgkin lymphomas by flow cytometry.

We report the sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of various immunophenotypes characteristic of each class of B-cell non-Hodgkin lymphoma (NHL) based on analysis of 352 morphologically well-characterized B-cell NHLs and 175 benign lymph nodes (LNs) using 2-color flow cytometry. All B-cell NHLs that exhibited a characteristic immunophenotype (except diffuse large B-cell lymphoma) had a high NPV. The immunophenotypes of small lymphocytic lymphoma and mantle cell lymphoma showed high specificity, but only small lymphocytic lymphoma also showed a high PPV. One third of follicular lymphomas coexpressed CD23 and CD10. Diffuse large B-cell NHL showed no consistent immunophenotype. About 90% of all benign LNs expressed no substantial amounts of CD5, CD10, or CD23. Most benign LNs also failed to express substantial amounts of immunoglobulin heavy chains. In contrast, about 90% of NHLs showed expression of 1 or 2 heavy chains. The expression pattern of immunoglobulin light chains was not found helpful in favoring one lymphoma type over another. The usefulness of each immunophenotype for each lymphoma group is of particular diagnostic importance in limited specimens, such as fine-needle aspiration biopsies, small core biopsies, body effusions, extranodal sites, and nodal tissues with various artifacts.