IRF4 and neoplasm: Similar to EBVMCU, large atypical EBV-positive lymphoid cells are characteristics of EBV-positive DLBCL, the high-grade B cell neoplasm, generally occurring in the elderly.3, 22Its neoplastic component is composed of a variable number of large, transformed cells/immunoblasts, and HRS-like cells, within the reactive mixed inflammatory infiltrate.23These tumor cells demonstrate positive immunoreactivity for CD20, CD30, and sometimes CD15,22and show an activated-B cell immunophenotype, being positive for IRF4/MUM1 and negative for CD10 and BCL6.23These findings are distinctly resembling EBVMCU.