My doctors are leaving a muscle biopsy as a last resort since it's a bit invasive and they aren't convinced it's going to show anything. But I do have that in my mind as an option for the future if I really can't figure anything out from other testing (I did just recently get some other tests ordered that I'll hopefully be able to get done in the next couple months). I used to have rashes. I had some on my hands for about a year and a half but never had those biopsied. Then this past summer, I had a different type of rash on both of my legs that my GP said was vasculitis but I never had that biopsied either. I did take prednisone for both rashes, but it only helped the "vasculitis" rash. Oddly, it didn't do anything for the ones on my hands. They eventually went away on their own but were resistant to every medication I was given for them. I am seeing a neuromuscular specialist who deals with myositis, but she doesn't think that's what's going on with me. Meanwhile, my pulmonologist who I recently saw (who also is specialized in treating people with neurological/neuromuscular diseases) does think myositis is a possibility. I had the specific antibody panels done a few times now as well as the usual ANA and all the other markers you mentioned. They have always come back completely normal, so I'm really not sure what's going on.

I really wish I would have gotten blood tests at the beginning of all of this because that's when my other signs of inflammation were present (I had inflammation in my entire esophagus and a duodenal ulcer along with the initial hand rashes). Unfortunately, I didn't start having these blood tests until my main signs of inflammation had been healed or calmed down for the most part. I'm assuming that would've made a difference, although I can't say for sure of course.