I had this problem for a while. I had grease burns all over my right shoulder, it freaked me out so much I thought maybe it was really skin cancer! lol It wasn't, I found online that you mix baking soda, sugar and honey together, rub it over the area for about two minutes to exfoliate it, and you do this a few times a week. The dead skin just sloughs off and it works quickly and mine had been there for about a year. They also said to put lemon juice on it to brighten the area. Should work, haven't tried it yet.
http://www.ehow.com/how_5558837_rid-marks-skin.html
