Do fungi play a role in psoriatic nails?

Onychomycosis is the most common disease of the nails and constitutes about a half of all nail abnormalities. Some factors like increasing age, male sex, repeated nail damage, genetic predispositions and underlying conditions, such as diabetes, immunodeficiency or peripheral arterial disease may predispose to develop onychomycosis. It is also suggested that abnormalities in nail morphology are the predisposing factors to onychomycosis. Psoriasis is one of the most common reasons of disturbed nail morphology and the spectrum of nail changes in psoriasis is very wide. Thus, there were suggestions that dystrophic nails in psoriatic patients lose their natural preventing barrier and therefore are more predisposed to fungal infection. This paper summarizes the knowledge about prevalence of onychomycosis among psoriatic patients and contains a literature review concerning this problem. Most authors report that the prevalence of onychomycosis in psoriatic patients is not higher than that in control population. However, especially yeasts and maybe moulds, probably as concomitant pathogens, are more often isolated from psoriatic patients than from non-psoriatic population. In reasonable cases, the mycological examination is required, especially when the clinical picture of the nails suggests the presence of fungal infection. In these cases, antifungal treatment may be beneficial for psoriatic patients.