Two major molecular subgroups within PTCL-NOS with biological and overall survival differences. (A) Bayesian predictor for the GATA3 and TBX21 subgroups was derived using cases from hierarchical cluster 1 and cluster 2. LOOCV was used for classification precision. (B) Overall survival (OS) analysis of molecularly-defined GATA3 and TBX21 subgroups showed significant difference in clinical outcome (P = .01). A subset of cases mentioned in the text lacked clinical outcome data and are not included in OS analysis. (C) Representative cases in the TBX21 subgroup (H&E) with TBX21 immunostain showed positivity ranging from 40% to 80% of cells, whereas positivity in the GATA3 subgroup was <10%. (D) Representative cases in GATA3 subgroup immunostained with GATA3 showing positivity ranging from 50% to 80% of cells, and were negative for TBX21.