MYD88 , CD79B , and CARD11 gene mutations in CD5‐positive diffuse large B‐cell lymphoma

BACKGROUND CD5‐positive (CD5 + ) diffuse large B‐cell lymphoma (DLBCL) is characterized by frequent central nervous system recurrence and a predominant activated B‐cell‐like nature. Primary DLBCL in sanctuary sites (DLBCL‐SS) also demonstrates these features, and >70% of patients harbor myeloid differentiation primary response 88 ( MYD88 ) (L265P) and CD79B mutations. The objective of the current study was to elucidate a possible relationship between CD5 + DLBCL and DLBCL‐SS. METHODS MYD88, CD79B, CD79A , and caspase recruitment domain family member 11 ( CARD11 ) mutations were examined in samples from 40 patients with CD5 + DLBCL. Mutation analysis was performed by direct sequencing. RESULTS MYD88 and CD79B mutations were detected in 33% (13 patients) and 38% (15 patients), respectively, of the 40 patients with CD5 + DLBCL. Ten patients had these 2 gene mutations, and 1 had a CD79A mutation. One of 2 patients with testicular involvement had both MYD88 and CD79B mutations. The other patient had a MYD88 mutation alone. None of the 31 patients examined was found to have a CARD11 mutation. MYD88 and CD79B mutations were found to be associated with localized disease ( P  = .038 and P  = .003, respectively). Primary extranodal lymphoma was associated with higher frequencies of mutations in MYD88 or both MYD88 and CD79B ( P  = .008 and P  = .014, respectively). There was no significant difference in overall survival based on MYD88 and CD79B mutation status. CONCLUSIONS The incidence of MYD88 and CD79B mutations in patients with CD5 + DLBCL is lower than that in patients with DLBCL‐SS, suggesting that CD5 + DLBCL is not the same disease as DLBCL‐SS in terms of gene mutation status. CARD11 mutations are rare in patients with CD5 + DLBCL. Cancer 2017;123:1166–1173. © 2016 American Cancer Society .