Fungal Infections and Nail Psoriasis: An Update

The relationship between psoriasis and onychomycosis is controversial, and the exact nature of this association remains to be clearly elucidated. In healthy nails, the compact nail plate acts as a barrier, preventing any infection. In psoriatic nails, the nail plate involvement, together with abnormalities in the blood capillaries, may lead to decreased natural defenses against microorganisms. Moreover, onycholysis (detachment of the nail plate) induces a humid environment that may favor fungal proliferation. Treatment with immunosuppressive drugs may additionally enhance onychomycosis. In this comprehensive review, we present data regarding the incidence and pathogenic action of dermatophytes and other fungi in the development of fungal infection in psoriatic nails.