2022 年 62 巻 2 号 p. 106-113
Immune evasion mediated by PD-L1 plays an important role in the development of B-cell malignancies. However, PD-L1 expression is infrequently observed in tumor cells of extranodal diffuse large B-cell lymphoma, not otherwise specified (DLBCL, NOS). Other than copy number alterations, PD-L1 is aberrantly upregulated by structural variations in the 3′-UTR of PD-L1. We report four cases with PD-L1 expression on tumor cells, including two with structural variations in the 3′-UTR of PD-L1 and two without. Our report demonstrates the presence of a small number of “immune evasion-type” extranodal DLBCL, NOS cases.