I think it would be a cool idea to have scars and other disfigurements in the game that you would acquire after you create your character. So say you were attacked by someone with a knife and that cut you down your arm after you have healed and what have you there will be a scar there to tell the tale or say you were in a fire and you got burnt wherever you got burnt would have the blemish after you have been healed.
Now of course a lot of players wouldn't want their character to have this kind of deformity, so I think if you wanted to get rid of the disfigurement you could go to the hospital or clinic to have cosmetic surgery which is one way of keeping immersion and not breaking the fourth wall.