Psoriasis, pressure sore or callus?

I tried to post a picture but it was denied!

If it s a callous, a way to keep it from getting bigger is to provide your dog with somewhere soft to lay on. All my bog dogs have callouses on their elbows because they like to lay on the cold floor to keep cool (winter-loving dogs here). They do use the couch and the dog couch, but they get too warm after a while and move to the floor eventually. Other than that, I don't really have anything else to add. Hopefully someone will have better ideas for you.

Wally does the same when he gets warm :/