Somatic FGFR3 mutations have been reported in various cancers such as urothelial carcinoma. Evidence is growing that these mutations are also involved in the pathogenesis of benign acanthotic skin tumors such as epidermal nevi and seborrheic keratoses. The report by Hernandez et al. strongly supports this concept. However, further studies are required for a better pathogenetic understanding of FGFR3 related tumors in urothelium and skin.