Your problem is in your head.
The psychologist is interested in the mental state that makes you cut yourself. Your scars are of more interest to a surgeon. Many psychologists would hve looked at them anyway to get an impression how bad it was.
Some psychologists might see the showing of the scars as a "game" between them and the patient, a game with roles such as "poor little me, see how I cut myself" versus "Oh, how terrible your scars are". Psychologists with this view might refuse to see your scars in order to avoid getting drawn into this "game". Psychologists with this viewpoint think that it is very important to avoid games between patient and psychologist, because such games would make real communication on the real issues more difficult.