PDCD1 and diffuse large B-cell lymphoma: In DLBCL, roles of PD-1 and PD-L1 expression remain obscure, as, depending on assessment method, target cells (TME or tumor cells), and used cutoff levels, some studies found high amounts of PD-1+ TILs or PD-L1 expression to be associated with poor outcomes, whereas other studies showed favorable or no prognostic impact on survival [12,13,14,15,16,17,18,19].