Bcl-6 and c-Myc are rarely co-expressed in adult diffuse large B-cell lymphoma

Bcl-6 is expressed in germinal centre derived B-cell non-Hodgkin lymphomas including diffuse large B-cell lymphoma (DLBCL) and is likely to play a major role in driving proliferation of a subset of DLBCLs, especially those of germinal centre B-cell subtype, but the role of c-Myc, which is important for proliferation in various lineages is not known. We used the highly standardised staining conditions of a tissue microarray to characterise co- expression of c-Myc and Bcl-6 in DLBCL. We carried out immunohistochemistry of 73 arrayed cases. The majority (62/ 73) did not express c-Myc, but 11 cases (15%) showed nuclear staining. 5/ 53 ( 9%) of Bcl-6 expressing cases co-expressed c-Myc, whereas a much higher proportion, 6/ 20 (30%), of Bcl-6 negative cases were positive for c- Myc. Overall survival of c-Myc expressing cases was the same as those that had absent expression. There was no significant correlation between c- Myc expression and DLBCL subtype (germinal centre or non- germinal centre subtypes).