Nail psoriasis successfully treated with intralesional methotrexate: case report.

Psoriasis is a common, chronic disease which affects nearly 3% of the population. The lifetime incidence of nail involvement increases up to 80-90% for psoriatic patients. Nail psoriasis is considered a significant social problem. Many topical agents have been used for psoriatic nails with various side effects and some benefits; management is currently inconclusive. Methotrexate (MTX) is a folic acid analog, which irreversibly binds to dehydrofolate reductase and blocks deoxyribonucleic acid synthesis. It is considered a potential treatment option for rapidly growing cells and has an anti-inflammatory effect through inhibition of the polyamine pathway in autoimmune diseases. Intralesional MTX has been used successfully for various indications. We present a case successfully treated with low-dose intralesional MTX with no observed side effects in a 26-year-old female psoriatic patient suffering from nail dystrophy. In contrast, conventional topical and systemic therapies have various side effects, which limit their use. We conclude that intralesional MTX injection seems to be a safe and effective treatment option for nail psoriasis; however, large controlled studies are needed.