IRF4 and diffuse large B-cell lymphoma: The t(14;18) often seen in systemic follicular lymphomas and part of systemic diffuse large B-cell lymphoma (DLBCL) is absent.6 In contrast, PCLBCL, leg type, has a B-cell phenotype (CD20+, CD79a+), but is MUM-1/IRF4+ and FOX-P1+.