Psoriasis and hereditary palmoplantar keratoderma complicated with a dermatophyte infection. Case report.

In a 29-year-old woman suffering from hereditary palmoplantar keratoderma of the Unna Thost variety, psoriasis appeared at an age of 28 years. The keratoderma on the soles was complicated with a dermatophyte infection, which made the differential diagnosis towards psoriasis difficult. Histopathologic examination of punch biopsy from the soles showed no conclusive signs of psoriasis. An increased thickness of the horny layer, which in PAS staining showed fungus hyphae, was found.