IL17A and primary cutaneous T-cell non-Hodgkin lymphoma: As the CTCL progresses, the tumor microenvironment is associated with increasing expression of TH2 TFs and cytokines (e.g. GATA-3, IL-4, IL-5, and IL-13) and declining levels of TH1 and TH17 associated TFs and cytokines (e.g. T-bet, RORγt, IL-12, IL-17 and IFN-γ) (201–207).