Malignant T cells from CTCL lesions show a strong type 2 T helper (Th2) bias characterized by the production of Th2 cytokines (Il-4, IL-5, IL-10, IL-13) and the low production of Th1 cytokines (IFNγ, TNFα, and IL-2) [9,14]. Here, IL4 is linked to primary cutaneous T-cell non-Hodgkin lymphoma.