Malassezia furfur is a fungus that can exist as both a yeast and as a mold (a dimorphic fungus). It is normally a harmless component of normal skin flora but that in some people causes tinea versicolor. Most affected people are healthy. Factors that may predispose to tinea versicolor include heat and humidity and immunosuppression due to corticosteroids, pregnancy, undernutrition, diabetes, or other disorders. Hypopigmentation in tinea versicolor is due to the inhibition of tyrosinase caused by M. furfur production of azelaic acid.
Symptoms and Signs of Tinea Versicolor
Tinea versicolor is asymptomatic. Classically, it causes the appearance of multiple tan, brown, salmon, pink, or white scaling patches on the trunk, neck, abdomen, and occasionally face. The lesions may coalesce. In light-skinned patients, the condition is often diagnosed in summer months because the lesions, which do not tan, become more obvious against tanned skin. Tinea versicolor is benign and is not considered contagious.
Diagnosis of Tinea Versicolor
Potassium hydroxide wet mount
Sometimes Wood light examination
Diagnosis of tinea versicolor is based on clinical appearance and by identification of hyphae and budding cells (“spaghetti and meatballs”) on potassium hydroxide wet mount of fine scale scrapings. Vitiligo with depigmented macules should also be considered.
A Wood light examination reveals golden-white fluorescence.
Treatment of Tinea Versicolor
Sometimes oral antifungals
Treatment of tinea versicolor is any topical antifungal drug. Examples include selenium sulfide shampoo 2.5% applied to the skin (in 10-minute applications daily for 1 week or 24-hour applications weekly for 1 month); topical azoles (eg, ketoconazole 2% daily for 2 weeks); and daily bathing with zinc pyrithione soap 2% or sulfur-salicylic shampoo 2% applied to the skin for 1 to 2 weeks.
Fluconazole 150 mg/week orally for 2 to 4 weeks is indicated for patients with extensive disease and those with frequent recurrences.
Hypopigmentation from tinea versicolor is reversible in months to years after the yeast has cleared.
Recurrence is almost universal after treatment because the causative organism is a normal skin inhabitant. Fastidious hygiene, regular use of zinc pyrithione soap, or once-monthly use of topical antifungal therapy lowers the likelihood of recurrence.
Although tinea versicolor can occur in immunosuppressed patients, most affected patients are healthy.
The disorder is frequently diagnosed in the summer because hypopigmented lesions become more obvious against tanned skin.
Try to confirm the diagnosis by finding hyphae and budding cells on potassium hydroxide wet mount of fine scale scrapings.
Treat with topical or oral antifungals.