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. This evidence concerns the gene CDKN2A and breast diffuse large B-cell lymphoma.