What Causes Discolouration On Upper Thigh?

My niece noticed something wrong with my leg. I just figured she was pointing out the cellulose. Wrong. When I looked in the mirror I saw a huge bruise-like discoloration on the side of my upper right thigh. I've fractured this leg-- in second grade. The bruise doesn't hurt. I'm 24 years old. I don't remember ever bruising before.