The feeling of having being cut or otherwise injured were it would end up bleeding but there is no wound.... Feeling of scar anywhere on/in the body with out actually having a wound.
Try running your nail over some skin,(DO NOT CUT YOUR SKIN WITH YOUR NAIL), the feeling you have where you ran your nail is bout the same feeling of a ghost scar but an actual ghost scar lasts. Running your nail over your skin should fade fairly quickly.