Although this study included limited number of patients representing various PTCLs subtypes, our results suggest that pY-STAT3 is frequently constitutively phosphorylated in PTCL, especially in ALCLs and AITLs, but this was associated with STAT3 mutations in only a fraction of PTCL samples. This evidence concerns the gene STAT3 and mature T-cell and NK-cell non-Hodgkin lymphoma.