PDCD1 and mature T-cell and NK-cell non-Hodgkin lymphoma: Classical Hodgkin’s lymphoma (cHL) and peripheral T-cell lymphoma (PTCL) belong to different types of lymphoma, their prognosis is very different, programmed cell death receptor 1 (PD-1) and its ligand (PD-L1) have been studied in these 2 types of diseases.