TBX21 and peripheral T-cell lymphoma, not otherwise specified: In peripheral T-cell lymphoma, not otherwise specified, (PTCL, NOS) two molecular subtypes have been identified with the help of gene expression profiling studies: PTCL-GATA3 and PTCL-TBX21, characterized by overexpression of the transcription factors TBX21 or GATA3 [6].