Background Psoriatic Juvenile Idiopathic Arthritis (PsJIA) is defined as JIA in the presence of psoriasis or two minor criteria: nail pits/onycholysis; dactylitis; first degree family history.¹ Previous studies have looked at the initial presentation of PsJIA, albeit in either a predominant rheumatology or dermatology setup, with mixed results.² Correct early classification of PsJIA is important because the prognosis may differ from other JIA subtypes, with a more protracted course and reduced rates of drug free remission.³ Early management demands particular attention, as the disease may be more aggressive. Moreover, recent evidence in adults has highlighted specific associated co-morbidities.⁴

Aim To study the presenting features of disease using a cohort of patients from a specialist PsJIA clinic.

Methods Retrospective case-note review of Children and Young People (CYP) under 18 years, attending a specialist PsJIA clinic of combined dermatology and paediatric rheumatology services at a paediatric tertiary centre over 2 years.

Results Twenty-one CYP were identified with PsJIA (76.2% female; mean age at diagnosis 13.3y). Nearly two-thirds (57%) presented initially with psoriasis, with a mean of 2.5y before the onset of arthritis. Conversely just under one-third (29%) were diagnosed with arthritis first, with a mean duration of 3.9y to classification of PsJIA sub-type. Just under one-third were diagnosed on the basis of minor criteria (table).

Discussion The majority of CYP presented with psoriasis, with symptoms of arthritis following within 2–3 years. Of those who initially presented with arthritis, there was an average of almost 4y before classification as PsJIA. This has implications for management and a change of prognosis, from a potentially limited disease course to one which is more likely to be long-term. It is interesting that scalp disease was a presenting skin feature in 85% of CYP with skin involvement. It is therefore imperative to enquire about scalp symptoms in all patients with JIA and involve early dermatology input where there is diagnostic uncertainty. Further large and long-term prospective studies are necessary to further evaluate this unique group of CYP with PsJIA.

References

• Petty RE, Southwood TR, Manners P, et al. International League of Associations for Rheumatology classification of juvenile idiopathic arthritis: second revision, Edmonton, 2001. J Rheumatol 2004; 31:390–392.

• Cassidy JT, Petty RE, Laxer RM, Lindsley CB, editors. Textbook of paediatric rheumatology. 6th ed. Philadelphia: Elsevier Saunders; 2011. p. 287

• Flatø B, Lien G, Smerdel-Ramoya A, Vinje O. Juvenile psoriatic arthritis: longterm outcome and differentiation from other subtypes of juvenile idiopathic arthritis. J Rheumatol. 2009 Mar;36(3):642–50.

• Jafri K, Bartels CM, Shin D, Gelfand JM, Ogdie A. Incidence and Management of Cardiovascular Risk Factors in Psoriatic Arthritis and Rheumatoid Arthritis: A Population-Based Study. Arthritis Care Res (Hoboken). 2016 Oct 1. doi: 10.1002/ acr.23094