HDAC9 and primary cutaneous T-cell non-Hodgkin lymphoma: (I) Whereas trichostatin A (TSA) is an HDAC inhibitor used only in laboratory experiments because of its toxicity, vorinostat (suberoylanilide hydroxamic acid, SAHA) which has been already approved by United States Food and Drug Administration (FDA) as the first HDAC inhibitor, is utilized for the treatment of relapsed and refractory cutaneous T-cell lymphoma (CTCL).