WES of purified, neoplastic T‐cell (CD3+PD1+) demonstrated high concordance with whole tumor biopsies and validated the presence of TET2 and DNMT3A in tumor and non‐lymphoid cells, but other mutations (CD28, RHOAG17V, IDH2R172, PLCG1) in neoplastic cells. The gene discussed is TET2; the disease is neoplasm.