Nail dystrophies, scalp and intergluteal/perianal psoriatic lesions: risk factors for psoriatic arthritis in mild skin psoriasis?

Abstract AIM: In the literature, clinical features of psoriasis associated with psoriatic arthritis (PsA) onset have not been clarified, even if high Psoriasis Area and Severity Index (PASI) was found to be directly related with PsA. METHODS: The study was conducted between November 2008 and April 2009 on consecutive psoriatic outpatients referred to a service of dermatological consultations, on indication of other hospital specialists. Participants were affected by mild skin psoriasis, in particular with nail dystrophies and/or scalp and/or intergluteal/perianal lesions. The questionnaire provided by the Classification of Psoriatic Arthritis (CASPAR) study group was proposed to all patients and we added a question about the time of psoriasis onset. RESULTS: Eighty-seven subjects (34 males and 53 females) aged between 18 and 91 years (mean age 48 years) with such psoriatic features were recruited. Other 30 refused to take part to the study. Forty-seven per cent of these participants were found to suffer from PsA, in particular 83% of those with nail and scalp psoriasis, 40% of subjects with intergluteal/perianal involvement and 37% of patients with just scalp lesions. We present the first exploratory and observational study focused on a population with mild skin psoriasis, in order to evaluate if nail dystrophies, scalp or intergluteal/perianal psoriatic lesions might be indicative of a higher risk of PsA even in cases with mild skin psoriasis. CONCLUSION: Nail psoriasis is probably a suggestive feature of joint involvement. The scalp psoriasis, as well as intergluteal/perianal psoriatic lesions, is likely to be less associated to PsA, but may be an important comorbidity factor for the development of PsA. Further investigations in a larger population are encouraged to assess a potential link between PsA, site-specific and mild skin psoriasis.