TY - JOUR T1 - Discussion: Clinical features, epidemiology, classification criteria, and quality of life in psoriasis and psoriatic arthritis JF - Annals of the Rheumatic Diseases JO - Ann Rheum Dis SP - ii24 LP - ii25 DO - 10.1136/ard.2004.030767 VL - 64 IS - suppl 2 AU - D D Gladman Y1 - 2005/03/01 UR - http://ard.bmj.com/content/64/suppl_2/ii24.abstract N2 - Are people going to be convinced that the multi/poly arthritis with time is still psoriatic arthritis and not a seronegative rheumatoid that has evolved? This is an important issue. It highlights the difficulty in differentiating psoriatic arthritis (PsA) from seronegative rheumatoid arthritis (RA). Generally, the oligoarticular presentation is identified as a feature of PsA, but PsA does evolve from oligoarticular to polyarticular over time. It is just as important to consider the joints involved as the extent of joint involvement. Generally, the differentiation between PsA and RA is more difficult early in the course, before the more classic changes such as pencil in cup are evident. Later in the disease the radiological features are quite helpful. In the future, magnetic resonance imaging (MRI) and ultrasound may provide early clues. How does one define symmetry in PsA? The issue of symmetry has caused confusion in describing the clinical patterns. PsA is considered to be less symmetrical than RA. It clearly tends to be more asymmetrical at presentation due to the oligoarticular onset of psoriatic arthritis. However, as joints accrue over time, it may become more symmetrical. It has been shown that symmetry is indeed a function of the number of … ER -