I'm also MuSK positive X12 years and was refractory on CC, pred and IVIG. I had high dose cyclophosphamide (cytoxan) therapy in Nov. I am now symptom free. It is also referred to as an "immune system reboot."

Please examine the risk factors for PML with Rituxan. It is especially important since you've taken Cellcept.

My neuro also offers pulse doses of Cyclophasphamide if you don't want to go for the immune system reboot. That might also be an option for you.

Good luck.