Among the more aggressive lymphomas arising from NK or γδ T cells, NK/T cell lymphoma, nasal type (NKTCL), hepatosplenic T cell lymphoma (HS-PTCL), and primary cutaneous and peripheral γδ T cell lymphomas (PC- γδ-PTCL and γδ-PTCL), STAT3 mutations have been reported in a small fraction of cases, including activating mutations in the SH2 domain [33,34,35,36]. This evidence concerns the gene STAT3 and mature T-cell and NK-cell non-Hodgkin lymphoma.