Help with Letter of Necessity for Insurance payment of Panniculectomy

I have a consultation for PS for my panniculectomy.  The PS wants a letter from my PCP documenting rashes, back pain etc.  I work for my PCP.  He wants me to write the letter, then he will sign it.  Does anyone have any tips or sample letters? I have Blue Sheild of California PPO. (They paid for my DS!)

Thank you very, very much.  I am so excited I can hardly contain it!

Sorry, I was approved first go round for my panniculectomy and didn't have to get a letter from my PCP.