The authors further provided evidence that IL-13 promotes the proliferation of malignant T cells isolated from the blood of leukemic CTCL patients, suggesting that IL-25, TSLP and the general skewing toward a Th2-polarized inflammatory environment may fuel the malignant expansion indirectly by augmenting the levels of IL-13 (Geskin et al., 2015). Here, IL25 is linked to primary cutaneous T-cell non-Hodgkin lymphoma.