What Does Pink Mark On Upper Back Indicate?

My husband has a small (1 cm) mark on his upper back. It is pale pink in colour, but not raised or indented, and it feels the same as the rest of his skin. I think it started off as a spot, which I don't think I helped by messing with it. It hasn't got any bigger, and I have been putting Savlon on it every day, which if anything has reduced it slightly. But he has had it for a few months now. He says he can't feel it, it isn't sore or itchy. His back is quite freckly anyway. Any ideas?