My face is like that too, I think it's because I wash and exfoliate my face and not my body. I do wear a shade darker in makeup (I"m a Golden medium but I wear a Medium Tan). That way my face color matches the rest of my body a bit better.
I have a friend who is black, except for her feet, which are usually completely white unless she's been in the sun. Its quite freaky, I call her WhiteFoot lol. Its really just a genetic twist when it all comes down to it. Nothing you can really do for it other than getting lots of sun.