Possible role of interleukin-17 in the pathogenesis of lichen planus is studied by Shaker & Hassan.12 They found that the serum levels of IL-17 were significantly higher in patients compared with controls and IL-17 can contribute to the pathogenesis of lichen planus by enhancing T cell-mediated reactions and inducing production of chemokines and other cytokines. This evidence concerns the gene IL17A and lichen planus.