Concerned about this legion on my knuckle? Possibly dermatomyositis?

[MariaDixonnn]

I have had this.. thing on my hand for two and a half years now. Previously I thought it was just from picking at it when I was younger. I used to tell people it was a scar from a cheer stunt that never went away. I got curious on the internet earlier and found a condition called dermatomyositis. But mine is only on my right middle knuckle, while the images of this condition are multiple legions. Anyone who knows what they are talking about want to give me any advice?? Anything is appreciated. Thanks!! Here is a picture.. Also, please ignore the twitter account, it is my sisters.

https://twitter.com/#!/AR_loves_JDB/stat...36/photo/1

[Landlord]

You would have manny other systems of DM by now, not just this. You do need to see a doctor about it though. Not DM, but not normal either.