The visibility of the scars would be slightly distracting, I would want to know more about your story and what you had been through, but especially if you were the first therapist I'd ever seen I probably wouldn't have a clue whether it was ok to ask about them or not.

They might concern me - because scars are a visible hallmark of the suffering, and if you were somebody I was feeling drawn to as we built the therapy relationship I would feel deeply sad about the pain responsible for the scars, and for a few sessions as I said I might find myself distracted thinking about them, but I would not leave a therapist because of scars. Nope. I think I would learn to not see them all the time, the same way with anyone you grow familiar with, their personal physical features stop being so obvious.

If they were fresh marks and it was obvious the person was still self harming, then I would leave. Reluctantly, if I otherwise liked you a lot.