Epidermal hyperpigmentation in non-syndromic solitary cafe-au-lait macules may be associated with increased secretion of endothelin-1 by lesional keratinocytes.

To clarify the mechanism of accentuated melanisation in non-syndromic solitary cafe-au-lait macules we used an enzyme-linked immunosorbent assay (ELISA) to measure the concentration of melanogenic cytokines secreted by cultured keratinocytes and fibroblasts derived from the skins of the macules and compared them with those derived from normal people. Endothelin-1 (ET-1) was significantly increased in cultured keratinocytes in the macules compared with the normals. In contrast, the secretion of other cytokines secreted by keratinocytes or fibroblasts did not differ between the groups. It may be that the increased secretion of ET-1 by epidermal keratinocytes has a role in the accentuated epidermal melanisation seen in non-syndromic macules.