In this SPTCL case with ARID1A mutation, the treatment of Chidamide on the basis of CHOP plus auto-HSCT achieved good results, indicating ARID1A may serve as a molecular biomarker for predicting the efficacy of Chidamide in the treatment of SPTCL. The gene discussed is ARID1A; the disease is subcutaneous panniculitis-like T-cell lymphoma.