Copy number alterations and translocations at chromosome 9p24 have been described, involving the genes coding for programmed death ligand 1 (PD‐L1) and PD‐L2, suggesting that immune escape may also be involved in the pathogenesis of PCNSL, with potential benefit of programmed cell death 1 (PD‐1) blockade therapy (Chapuy et al., 2016). Here, PDCD1 is linked to primary central nervous system lymphoma.