BCL6 and mature T-cell and NK-cell non-Hodgkin lymphoma: In their research, hypermethylation of the Bcl6 locus followed by Bcl-6 upregulation, combined with TET2 mutations, was thought to be the key event for lymphoma development which may result in biased Tfh differentiation and eventually contribute to AITL/PTCL development in patients.