Heat map from gene profiling studies depicting the two major molecular subgroups within PTCL-NOS in adults. Unique gene expression signatures identify the TBX21 and GATA3 subgroups of PTCL-NOS, which are associated with prognostic significance in adults, with worse survival associated with the GATA3 subgroup. A third, unclassifiable subgroup is also identified, highlighting the overall biological heterogeneity that characterizes PTCL-NOS. Adapted from Iqbal et al.³⁹