CD40LG and diffuse large B-cell lymphoma: Surface or cytoplasmic immunoglobulin (usually immunoglobulin M (IgM)) is expressed in 50–75% of DLBCL tumors as well2,3 (UpToDate 1, https://www.uptodate.com/contents/epidemiology-clinical-manifestations-pathologic-features-and-diagnosis-of-diffuse-large-b-cell-lymphoma).