Takahashi et al. implied that periostin together with TSLP play an important role in creating a Th2-dominant environment in the development of cutaneous T-cell lymphoma (CTCL), and reported that the levels of periostin and TSLP correlated with the level of IL-4 [13]. This evidence concerns the gene IL4 and primary cutaneous T-cell non-Hodgkin lymphoma.