The diagnosis of early psoriatic arthritis in an outpatient dermatological centre for psoriasis.

BACKGROUND Most of the data currently available on early psoriatic arthritis (EPsA) derive from studies performed in rheumatological settings. However, in recent years, there has been an increase in the amount of data from dermatologic centres. OBJECTIVES To describe the prevalence, clinical, laboratory and imaging characteristics of psoriatic patients with EPsA seen at a dermatological outpatient psoriasis centre. METHODS From January 2007 to May 2010, all patients with psoriasis who visited the psoriasis centre were asked about inflammatory joint involvement. A diagnosis of psoriatic arthritis was made on the basis of clinical, laboratory and imaging studies. The patients were diagnosed with early PsA (EPsA) if their inflammatory articular symptoms had been present for ≤ 1 year. RESULTS We diagnosed EPsA in 33 patients. Joint involvement was polyarticular (>5 joints involved) in 20 patients (60.6%) and oligoarticular (≤5 joints involved) in the remaining 13 patients. Quality of life due to skin involvement and the degree of functional impairment due to joint inflammation were only mildly affected, as measured by DLQI and HAQ, respectively. A direct correlation between the number of tender joints (ACR 68) and HAQ was found (r = 0.36; P = 0.04). Imaging studies showed that in spite of the absence of radiologic findings of peripheral joint damage, ultrasonography and contrast enhanced ultrasonography showed signs of articular inflammation in all patients. CONCLUSIONS A diagnosis of EPsA can be correctly performed in a dermatologic outpatient facility. To do so, a close collaboration among dermatologists, rheumatologists and radiologists is necessary.