Can psoriatic arthritis have a positive rf factor? was diagnosed with seropositive ra. take methotrexate 1cc weekly and humira biweekly. have developed psoriasis on both elbows. blood work only showed rf +,elevated crp, high sed rate.could it be psa?

There are false positive RF in significant amounts. Yours could be a false positive or you could have both psoriasis and rheumatoid arthritis. PSA can elevate sed rate & CRP. Are your fingernails pitted? If you're female, I favor RA& psoriasis. If male, PSA. . However A rheumatologist is best to advise you.

It could. Best to see a Rheumatologist or an MD experienced in arthritis.