Sun-induced freckling: ephelides and solar lentigines.

Freckles, the lay term for ephelides and lentigines, are important pigmentation characteristics observed in humans. Both are affected by sunlight; ephelides are largely genetically determined but induced by sunlight, whereas lentigines are induced by sun exposure and photodamage of the skin. However, despite being commonly observed, we know very little about them. Here, we review the current status of knowledge about freckles and propose a model for their formation.