Hidden psoriatic arthritis in seronegative oligoarthritis: a 14-year follow-up study.

Out of a cohort of 64 patients with seronegative oligoarthritis (SO), 8 patients with HLA-B13, 5 with Bw16 and 3 with HLA-B17 were invited to participate in a 14-year check-up. Thirteen patients showed some features of psoriatic arthritis, including 5 with suspected skin or nail disease, 5 with a family history of psoriasis, 3 with DIP joint affliction, and 2 with aortic valve insufficiency. It is concluded that a quarter of the patients with SO may have hidden psoriatic arthritis.