In the previous studies, we found anionic surfactants such as sodium laurate (SL) and/or sodium dodecly sulfate (SDS) exert actions on epidermal keratinocytes rather than mast cells to give rise to histamine production and skin itching by increasing the expression of the 53-kDa active form of l-histidine decarboxylase (HDC). This evidence concerns the gene HDC and neoplasm.