Description
IRF4 / MUM1 is expressed in the nuclei and cytoplasm of plasma cells and a small percentage of germinal center (GC) B cells mainly located in the "light zone". Its morphologic spectrum ranged from that of centrocyte to that of a plasmablast/plasma cell, and it displayed a phenotype (MUM1+/Bcl-6 /Ki67 ) different from that of most GC B cells (MUM1 /Bcl-6+/Ki67+) and mantle B cells (MUM1 /Bcl-6 /Ki67 )