Plastic Surgery Appeals - Has anyone had any luck? Tips?

So my abdominoplasty and panniculectomy was approved and covered by my Highmark BCBS insurance, but they denied my brachioplasty (arm lift). I've got tons of medical notes documenting PCP doctor's visits, medications tried for the breakdown and irritation of skin, limitation of movement, my PCP wrote a very convincing letter about why this was a medical necessity and I submitted my surgeon's pictures. I was pretty certain the appeal would be approved. But it wasn't. I was pretty upset. So I'm gearing up to do what the denial letter suggested, and that is to take it to a third level appeal, which would be an outside party evaluating the request.

Has anyone had ANY luck getting appeals approved? What am I missing? What else could I include? Would a letter from my therapist saying it causes me anxiety and depression help? Paying out of pocket with 4 kiddos and 2 of them headed off to college within the next year is just not an option.

PS (sorry for cross-posting in the plastic surgery forum....I'm just desperate for something that can help me get this approved.)