In breast DLBCL, MYD88L265P (57.1%), CD79B mutation (42.9%), and CDKN2A/B loss (71.4%) were found at high frequencies, which were similar to the mutation patterns of DLBCL of immune‐privileged sites compared with DLBCL NOS. The gene discussed is CD79B; the disease is diffuse large B-cell lymphoma.