If you put your hand over a torch you can still see a glow through your skin.
Therefore, you could have solar cells under the skin that absorb light and an LED panel that emits light through the skin.
Why? you ask, and well you might if not for the fact that this is the Halfbakery. Really, what
were you thinking asking such things?
Solar powered subdermal illumination is the fashion statement of the century.
Inspired by 'Micro trepanning'.