My arms have always been like this, can someone explain what it is? [Pictures included]

Beauty Tips For Body Care I did create a post a few days back but I didn't get enough responses so I thought I'd ask again with better resolution pictures: I've always had these flat white/dark spots on my skin (high visible on my arms and also on on my chest area, although not so visible there). For years I thought this was KP but from the past post I created, it seems I'm wrong. Any idea on what else this could be? The other day when I was out with my friend wearing short sleeves, she commented that I tan (but it's not a tan, I never go tanning, that's just how my arms always look) unevenly so that's made me all the more insecure about my bare arms. If anyone has something similar and could recommend a possible treatment to reduce the appearance, I'd really appreciate it. Thanks! This is what it looks like: http://imgur.com/a/VDnyQ, http://imgur.com/a/0HIr6
Girls Blog 2015
Submitted by availableforhugs