PD-L1-expressing extranodal diffuse large B-cell lymphoma, NOS with and without PD-L1 3'-UTR structural variations.

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.