It is called vitaligo, my friend has it. She has to wear make up when she goes in public because unfortunately people stare. She is gorgeous and will make a great addition to my game. Thank you.
Vitiligo usually presents itself as regions where there are patches of skin that has no pigmentation. Based on her complexion, I would guess its chromosomal Mosaicism. Then again, I could be wrong.

I just remember learning about Mosaicism in my genetics class (I'm a bio major). I guess it could be either. I'm such a nerd.