CD79B and primary central nervous system lymphoma: In particular, constitutive activation of MYD88 and CD79B would initiate the signaling cascades of NF‐κβ; these are considered key mutations that promote lymphoma pathogenesis in immune‐privileged sites, because the frequencies of these mutations in PCNSL are higher than those in systemic malignant lymphoma.6, 7, 8, 9, 10, 11, 12, 13