PRDM1 and neoplasm: In this study, PRDM1 positive staining was observed in the nuclei of EN-NK/T-NT tumour cells and a quarter of EN-NK/T-NT cases (18/70, 25.71%) exhibited weak expression of PRDM1 (10% to ≤50% stained cells) harbouring weak to moderate intensity, and the remaining 52 cases were negative in PRDM1 staining.