This study identified promising diagnosis and/or prognosis marker candidates and potential target genes as hub genes (i.e., PDCD1LG2-001/201, HAVCR2-001, CD274-001, VITCN1-001/002, CD28-202, and LAG3-001/003) connecting the Th-1/Th-2 and checkpoint gene network in PCNSL. This evidence concerns the gene PDCD1LG2 and primary central nervous system lymphoma.