I (and I suspect others) have faced difficulties in getting diagnosed because of ambiguities in our medical histories that can lead away from a dx of PsA. I am HLA B27 negative. On top of that, I have been positive for rheumatoid factor since my 30s. No skin involvement until very recently, and then very mild. Everything else, especially my overwhelming family history and asymmetrical inflammation, point to PsA.
I'm just wondering whether anyone else here is RF positive.
Thirty years ago I registered an RF of 300+. But nothing else. (My aches went away when I started an anti-depressant, so they just decided the reading was an anomaly.) Osteo (now being questioned) in my forties. Two knee replacements in my fifties. And now I have extensive erosions in my mid foot. No problems with my forefoot. RF is still 300+, so they thought it was RA. Anti-CCP came back negative. Then the rheumatologist looked at my nails. Psoriasis. No other skin involvement.
So yes, I'm in the RF+ club! When's our first meeting? LOL