CD19 and lymphoma: Indeed, in addition to a predominant polyclonal B‐cell population, flow cytometric analysis (Figure 1G) revealed the presence of two cell populations with different immunophenotypes: a population of high side scatter (SSC), CD19+, CD20+, CD22+, CD15+dim, CD30+dim, CD45+ cells (blue population) and a few CD19‐, CD20‐, CD15+dim, CD30+bright, CD45‐ cells (red population). Findings raised a differential diagnosis between unclassifiable B‐cell lymphoma with characteristics intermediate between DLBCL and classical Hodgkin lymphoma (CHL) versus composite lymphoma (CL) associating DLBCL with CHL.