Sakakibara A, et al. - Experts sought to examine the diagnostic value of programmed death 1 ligand (PD-L1) immunohistochemistry by analyzing the lymphoproliferative disease cases sharing tumour and non-malignant Hodgkin–Reed-Sternberg (HRS)-like cells with and without Epstein–Barr virus (EBV). The presence of PD-L1 expression was found in more than 5% of tumour or non-malignant HRS-like cells in 100% of EBV+ classical (C) Hodgkin lymphoma (HL) and EBV-negative nodular sclerosis CHL; 40% of EBV+ diffuse large B cell lymphoma, not otherwise specified (DLBCL–NOS) and 4% of nodal peripheral T cell lymphoma of follicular helper T cell type (PTCL-TFH). It was inferred that the immunohistochemical evaluation of PD-L1 expression in tumour and non-malignant HRS-like large cells could be beneficial for determining either immune escape or immunodeficiency in their pathogenesis.