I have lost 170 lbs and now have substantial loose skin particularly in the thigh. medicare is rejecting this although medically necessary?

Appeal: Medicare may deny things that really are necessary. Just have your doctor do an appeal, submitting all the reasons why this is necessary like frequent infections in the folds or that the excess is interfering with your ability to walk/sit (just because you don't like the skin, doesn't make it medically necessary). Usually when you document well, they pay.

Definitions: First, medicare won't pre-authorize any procedure. Either you had surgery and the bill submitted was denied or your doctor warned you it may not be covered and requested you sign an advanced beneficiary notification required by medicare informing you that if payment is denied you are responsible. What patients feel is medically necessary and what insurance does are often at odds.