I've been treated for PM for the past 6 years. I am on Prednisone and Methotryxate. Recently it has gotten worse and my RA doctor sent me for a muscle biopsy. The results of the biopsy came back with nothing at all wrong with my cuscles. My question is, the surgeon that did the biopsy said that it didn't matter where he took the biopsy since PM was systemic. I'm not sure that he was correct. He performed the biopsy on my anterior thigh muscle but my muscle weakness and pain is in my posterior thigh. My anterior muscle has never given me a problem.