I also had elevatedf RNP at last bloodwork. Suggests MCT as you say, but which one?? I had a mix up at the rheum - was told that other than the RNP everything was normal so no need to see her again. But then found out last month at PCP appt that I was supposed to go back after derm appt. Thinks I have psoriatic arthritis which she needed the psoriasis confirmed by the derm. Her office worker did not say I needed to come back; when I asked, she said "nope, you're good."
So longwinded way to say that I will be going back in Feb. and will ask more Q's about the RNP.