The Unique Immunophenotype of Double-Hit Lymphomas

Abstract

We read with interest the article “‘Double-Hit’ Mature B-Cell Lymphomas Show a Common Immunophenotype by Flow Cytometry That Includes Decreased CD20 Expression” by Wu et al.¹ We have similarly noticed distinct immunophenotypes, in addition to decreased CD20 expression, in double-hit lymphomas (DHLs) analyzed by flow cytometry at our institution. Because few data exist in the literature,^2,3 we chose to test the specificity of this distinct immunophenotype by comparing the immunophenotypic characteristics of patients with DHL with those of patients with Burkitt lymphoma (BL) and CD10+ diffuse large B-cell lymphoma (DLBCL) by using 4-color flow cytometry with the following antigens: CD5, CD10, CD19, CD20, CD22, CD23, CD38, FMC-7, and surface monoclonal and polyclonal κ and λ light chains, when possible. Antigen expression patterns were compared with those of normal, polytypic B cells. Decreased expression encompassed negative, dim, and partial patterns, with antigen positivity defined as more than 20% expression compared with an isotypic control threshold.