Our data are in line with Chu et al. and Gonzales-Gomez et al. [5,8] analyzing the DNA methylation of CDKN2B, DAPK1, GSTP1, MGMT, MLH1, RARB, THBS1, TIMP2, and TIMP3 in PCNSL by MSP (Additional file 8) further supporting the validity of our analysis. Here, MGMT is linked to primary central nervous system lymphoma.