Tinea manuum misdiagnosed as psoriasis vulgaris: A case of tinea incognito

Abstract

Tinea incognito is a dermatophyte infection with altered clinical appearance which is usually caused by the use of immunosuppressive agents such as topical corticosteroids. Hereby, we present a 59-year-old Caucasian male patient with tinea manuum on the dorsum of his left hand. The lesion was formerly misdiagnosed as psoriasis vulgaris and treated with topical corticosteroids. However, the symptoms were worsened. Moreover, new papules and pustules appeared within the lesion. The past medical history was remarkable for psoriasis vulgaris and he had an erythematous and squamous plaque on his lower back resembling psoriasis vulgaris. In order to reach a definitive diagnosis, the skin lesion on the dorsum of the patient’s left hand was examined by light microscopy after the application of 10% potassium hydroxide solution. Detection of septate hyphae confirmed dermatophytosis. The lesion was completely healed with oral terbinafine 250 mg daily for four weeks. Dermatophyte infections in early stages may be misdiagnosed as psoriasis vulgaris and thus, prolonged use of corticosteroids can lead to tinea incognito. Therefore, cutaneous lesions unresponsive to topical corticosteroid treatment should be evaluated with microscopic examination and fungal culture to confirm a suspected dermatophyte infection. Past medical history can provide useful information but a complete dermatological examination should be performed before the final diagnosis is made.

Keywords

• Tinea manuum; Tinea incognito; Psoriasis vulgaris