What Causes A Purple Ring On The Inside Of Wrist?

Almost a week ago, I noticed a slightly ovoid purple ring on the inside of my left wrist. There is no pain and it does not blanch with pressure. The purple coloration does not seem to be fading. I am on medications for RA, but have current labs that are all WNL. I am 51 years young, 5'2", 200#, S/P acromioplasty x5 months. What could this be? I have a photo, if there is a way to send it to you. Thanks, Michaela