Sorry, typo -- it's lichen schlerosis, not schlerosos.
Check out "lichen schlerosos" online in a medical dictionary that shows pictures, and see if you can find some pictures on dark skin, and read the description. Maybe that's what's going on. The other thing that it might be is vitiligo, but I've never heard that it hits the pubic area more (or sooner) than other places on the body.