Very tuff decision to make. I had a Thymoma removed in '94 and again in '99 both split sternum and I can tell you it's no fun. At the time I did not have MG so removal had no affect on me, I ended up with MG anyway. Unless your symptoms are quite severe you might want to just let it be. Robotic removal though is less invasive and might be worth a shot. Tuff choices.
Al