The back commonly gets keloids (thickened scars.) These can follow surgery, minor trauma, or nothing at all. Your friend may recall a spocific
tickTick removal bite, or may just be assuming that's what did it. In any case, the persistence is what you'd expect from a keloid, and sometimes they do spread over time. Injections of cortisone can flatten them, but surgery only makes the scar worse. Unless it's bothersome, perhaps it's best to leave it alone.
Best.
Dr. Rockoff