Consequently, the current WHO classification separates TFH-derived PTCL, previously classified as PTCL, NOS, based on the expression of at least two TFH-associated antigens (i.e. CD10, CD279/PD-1, Bcl-6, CXCL13, ICOS, SAP, or CXCR5) (4, 28). This evidence concerns the gene PDCD1 and mature T-cell and NK-cell non-Hodgkin lymphoma.