Pedal dermatophyte infection in psoriasis

Background Dermatophyte infections have been considered rare in psoriasis. However, there are data indicating that tinea unguium is as common or even more common in psoriasis compared with healthy controls. Tinea unguium is generally a secondary event to tinea pedis infection. Objectives To study the prevalence of tinea pedis and tinea unguium in psoriasis compared with a control group. Methods Consecutive psoriasis outpatients aged 18-64 years attending a department of dermatology were examined. Samples for direct microscopy and culture were taken from the interdigital spaces, soles and toenails. Consecutive patients without signs of psoriasis or atopic dermatitis seeking examination of moles constituted the control group. Results In total, 239 patients with psoriasis and 245 control patients were studied. The prevalence of tinea pedis was 8·8%[95% confidence interval (CI) ± 3·6%] in the psoriasis group and 7·8% (95% CI ± 3·4%) in the control group. The corresponding figures for prevalence of tinea unguium were 4·6% (95% CI ± 2·7%) and 2·4% (95% CI ± 1·9%), respectively. The differences found in the psoriasis vs. the control groups were not statistically significant. Conclusions This study does not support the hypothesis that the prevalence of tinea pedis and tinea unguium in patients with psoriasis differs from that in a normal population.