PDCD1 and lymphoma: PD1/PDL1 expression in lymphomas (Figures 1A,B) has been investigated by a variety of studies with mostly consistent results (27, 28); it can be demonstrated in up to a third of DLBCL, mainly of the activated B-cell type (59), and in PMBCL, in other lymphoma entities it is expressed in only a low percentage of cases (27).