For a while I have had a discoloration on the underside of my forearms and upper arms, not sure where it came from. Sometimes kind of itches. I am attaching a picture I took of my right arm (don't worry it is not gross or anything)


http://imgur.com/RikepGQ


Any idea what it could be? I have tried looking it up although it is difficult to describe and I have not really found anything anyway. Thanks!