Hans's algorithm and MYD88^L265P mutation may affect prognosis of primary central nervous system B-cell lymphoma

Primary central nervous system (CNS) lymphomas account for 1.9-3% of all brain tumors, with the majority being histologically classified as primary large B-cell lymphoma of the CNS (PCNS-LBCL). PCNS-LBCL is characterized by mature germinal center-exit B cells, and most cases of this phenotype are classified as activated B-cell-like phenotype according to gene expression profiling, or as non-germinal center B-cell-like phenotype (non-GCB type) according to Hans's algorithm. Genetically, PCNS-LBCL often shows mutations in MYD88^L265P and CD79B^Y196, and is similar to MCD or C5 in genetic subtypes. Therefore, we here investigated the clinicopathological and molecular characteristics of primary CNS B-cell lymphomas (PCNSBLs), focusing on the differences in the frequency of MYD88^L265P and CD79B^Y196 mutations, as well as the prognosis between GCB and non-GCB types. Forty-two patients with PCNSBLs were included in this study, with 12 (28.6%) classified as GCB type and 30 (71.4%) as non-GCB type. There were no significant differences between the two types in gender, tumor location, or frequency of MYD88^L265P and CD79B^Y196 mutations. Even after consideration of the confounding of age and the presence of R-MPV therapy, the GCB type PCNSBLs tended to exhibit better prognosis. Overall survival tended to be better in those with the GCB/MYD88^L265P mutation (-) group, followed by the GCB/MYD88^L265P mutation (+) group, and the non-GCB type. We speculate that Hans's algorithm and MYD88^L265P mutation may have potential prognostic value for PCNSBLs.