Pediatric Psoriasis Comorbidities

Nicole W. Kittler, MD; Kelly M. Cordoro, MD

Disclosures

Skin Therapy Letter. 2020;25(5):1-6. 

In This Article

Psoriatic Arthritis

Juvenile psoriatic arthritis affects 5–40% (most estimate 10%) of children with psoriasis.[4] This constitutes a heterogeneous group with varying clinical features (Table 1); some have features similar to juvenile idiopathic arthritis (JIA),[5] while others resemble adult psoriatic arthritis. The average age of symptom onset is 8 years,[5] but there is a bimodal distribution. The first peak occurs around 2–3 years of life and resembles JIA, with a female predominance, antinuclear antibody (ANA) positivity and oligoarthritis (characterized by <4 affected joints) or polyarthritis, primarily affecting the small joints and wrist bones, and stronger association with chronic uveitis.[6] A second peak resembling spondyloarthritis occurs at 10–12 years and is characterized by a male predominance, axial predilection, enthesitis and HLA-B27 positivity.[4,6] Patients in both groups are often affected by dactylitis.

Pediatric psoriatic arthritis may present before the skin disease and can be insidious, posing a diagnostic challenge. Whereas adults tend to develop psoriasis 8.5 years prior to joint disease, 80% of children develop arthritis prior to the onset of skin findings.[4,7] While nail psoriasis is a predictor of psoriatic arthritis in children as in adults, it is a less frequent finding among pediatric patients with psoriatic arthritis compared to adults (37–57%).[5] Correlation between skin disease severity and arthritis is poor.[8] Children and adolescents with juvenile psoriatic arthritis are more likely to be obese (1 in 5) and overweight (1 in 3) compared to the general population; obese patients with juvenile psoriatic arthritis are also older at the onset of joint symptoms.[9]

Psoriatic arthritis may be underdiagnosed in children. The diagnosis is based on clinical and imaging features; unfortunately, there are no specific biomarkers. Two sets of diagnostic criteria exist for juvenile psoriatic arthritis: International League of Associations for Rheumatology (ILAR) and Classification for Psoriatic Arthritis (CASPAR). One study reported that 20% of patients meeting either CASPAR or ILAR criteria for psoriatic arthritis were not diagnosed as having psoriatic arthritis by their rheumatologists.[5] There is also on average a 1-year delay from symptom onset until first rheumatology appointment.[5]

While there are no validated screening tools for psoriatic arthritis in pediatric patients, children should undergo a directed review of systems (with emphasis on limp and morning stiffness) and exam evaluating for arthritis.[7] Outcomes for pediatric psoriatic arthritis are favorable, with ~60% of treated patients achieving remission within 2 years.[6] Younger age of onset and female sex are both associated with better outcomes.

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