Among primary cTCL cases sequenced in the current analyses, we found that MET, KDR, STK11 and BRAF were the most frequent somatic mutations with SMAD4, TET2, PTEN, ATM, EGFR, JAK1, MYC, NOTCH1, SMO, TP53 and PLCG1 mutated less often. Here, SMAD4 is linked to primary cutaneous T-cell non-Hodgkin lymphoma.