Treatment of isolated nail psoriasis is difficult and often unsatisfactory. Information about the efficacy of systemic treatments on nail psoriasis is scarce because most studies on skin psoriasis do not focus on the nail changes. Nail involvement occurs in up to 78% of patients with psoriasis, is more common in patients with psoriatic arthritis, and may be the only sign of psoriasis. Nail psoriasis usually involves several nails, and both fingernails and toenails may be affected.

This open study involved 36 patients with moderate to severe psoriasis limited to the nails treated with low-dose acitretin from January 2005 through January 2007. The study was approved by the ethical committee of the Istituto Fisioterapici Ospitalieri, in Rome, Italy. The patients included 27 men and 9 women ranging in age from 28 to 67 years (mean age, 41 years).

Main Outcome Measures: Clinical evaluation, and Nail Psoriasis Severity Index (NAPSI) and modified NAPSI scores before therapy, every 2 months during therapy, and 6 months after treatment.

Results: The mean percentage of reduction of the NAPSI score after treatment was 41%; the mean percentage of reduction of the modified NAPSI score of the target nail was 50%. Clinical evaluation at 6 months showed complete or almost complete clearing of the nail lesions in 9 patients (25%), moderate improvement in 9 (25%), mild improvement in 12 (33%), and no improvement in 6 (11%).

Conclusion: Results from low-dose acitretin therapy show NAPSI score reductions comparable with those studies evaluating biologic drugs for nail psoriasis and suggest that low-dose systemic acitretin should be considered in the treatment of nail psoriasis.