Is it actual circles or blotches/patches of lighter skin? If its blotches/patches and you tan in a tanning salon, it may be tinea versicolor and can be treated with prescription lotion. I had it on my back and its from dirty tanning beds and can be contagious. Hopefully this helps...

I looked at the pictures of the this and my problem doesnt look like this.and ive had them for a long time. recently they have been poping up more frequently and i cant seem to find anything on the internet that looks like what I have.