Early psoriatic arthritis: the clinical spectrum

To characterize the clinical pattern of early psoriatic arthritis (PsA).

We studied 47 consecutive patients: 29 had definite PsA and 18 had the "sine psoriasis" subset. Inclusion criteria were articular and/or entheseal involvement of < or =12 weeks' duration and the exclusive use, before enrollment, of nonsteroidal antiinflammatory drugs to control articular symptoms. All patients underwent clinical examination, blood tests, total-body bone scintigraphy, articular ultrasonography, and radiography of clinically involved joints and/or entheses.

On the basis of clinical examination, early PsA was an oligo-enthesoarthritis in over 75% of patients studied. In contrast, the number of joints and/or entheses showing increased tracer uptake on bone scintigraphy was 3 times greater, compared to the clinical evidence (p < 0.001). Articular ultrasonography confirmed the inflammatory involvement of synovium and/or entheses in all articular sites active at time of bone scintigraphy, but silent at clinical examination. In addition, 7 patients showed the occurrence of joint and/or entheseal erosions on standard radiography.

Bone scintigraphy yields a more accurate evaluation of entheso-articular involvement and distribution in patients with early PsA. Our results suggest that clinical oligo-enthesoarthritic presentation of early PsA might represent in most cases a polyarticular condition that is at increased risk for clinical progression. These findings have a significant influence on the clinical decision-making process in patients with early PsA.