Prevalence of ultrasound and clinical findings suggestive of inflammatory arthritis in children with skin psoriasis

Abstract

Objective: To evaluate the prevalence of clinical and US (grey-scale and Doppler) abnormalities in joints, periarticular structures and nails of children affected by skin psoriasis (PsO).

Methods: We conducted a cross-sectional study including consecutive children affected by PsO. A systematic clinical and US evaluation of joints, entheses, tendons and nails were performed by independent examiners blinded to each other's assessment.

Results: A total of 57 children [26 girls (46%)] with a mean age of 9 years (s.d. 4) were divided into two groups, asymptomatic (Asy, 42 children) and symptomatic (Sy, 15 children), according to musculoskeletal pain. Differences were observed between the two groups in relation to age [9 years (s.d. 3) vs 11 years (s.d. 4), P < 0.05], PsO duration [2.4 years (s.d. 2.4) vs 5.4 years (s.d. 3.9), P < 0.001], systemic treatment [23 (54.8%) vs 2 [13.3%], P < 0.01], tender joint count [0 vs 12 children (80%), P < 0.001], swollen joint count [0 vs 3 children (20%), P < 0.01] and entheseal pain [0 vs 10 (66.7%), P < 0.001] in Asy and Sy children, respectively. US evaluation showed statistically significant differences between the Asy and Sy groups for the presence of US abnormalities [16/42 (38%) vs 12/15 (80%)], synovitis [1/42 (2%) vs 4/15 (25%)] and enthesitis [4/42 (9.5%) vs 5/15 (33%)]. Three children in the Sy group were classified with juvenile PsA (JPsA).

Conclusions: US abnormalities were higher in the Sy group, with synovitis and enthesitis as the most prevalent findings. Asy patients were more frequently under systemic treatment. US and a systematic clinical evaluation are useful tools for detecting subclinical JPsA in children with PsO and musculoskeletal symptoms.

Keywords: enthesitis; musculoskeletal ultrasound; nail; paediatric rheumatology; power Doppler; psoriasis; synovitis.