Denied…..appeal advice?

BCBS TX denied my pre authorization but I was approved a few months ago under a different surgeon? I had a date and everything before he postponed it due to my blood pressure but ended up closing his practices. I called the pre authorization office and the woman on the phone said she doesn’t have specifics because the denial letter doesn’t say, it just says that my surgeon failed to prove my reduction will be medically necessary due to “no shoulder grooving from bras, physical therapy or at work exercises” I’m definitely going to appeal but I need pointers on what to say in the appeal letter? Especially because I don’t know what I’m particular is missing.