Several HDAC inhibitors have demonstrated excellent inhibitory effects on tumor growth [10], for instance, panobinostat, a pan-HDAC inhibitor, hold great promise in several hematological malignancy including cutaneous T-cell lymphoma, Hodgkin lymphoma, and B-cell lymphoma in both preclinical study and clinical trials [11]. Here, HDAC9 is linked to primary cutaneous T-cell non-Hodgkin lymphoma.