Tinea Versicolor (Pityriasis Versicolor)

About tinea versicolor

Tinea versicolor is the fungal form of the yeast organism Pityrosporum ovale (the fungal form was previously known as Malssezia furfur until it was demonstrated that it was the hyphal form of Pityrosporum ovale.) It is a common fungal infection of the superficial layers of the stratum corneum. The lesions are round, have a fine scale, and can be white, pink or tan, with white being most frequently observed. They may become confluent. The neck, trunk, and upper arms are most often affected; the face and extremities are usually spared. The condition is usually asymptomatic, but may be associated with mild pruritus (itching). Patients usually seek care for cosmetic concerns. In winter months, the lesions appear darker that the surrounding skin, while in the summer months they typically appear as white spots. The lesions do not tan and therefore become more noticeable following sun exposure. There is also a hyperpigmented variety. Although immunosuppression can be a risk factor, most patients with the condition are otherwise in good health.

Is tinea versicolor contagious?

The yeast form of the organism is a frequent skin colonizer. It is only with conversion to the hyphal form that infection occurs. Conjugal cases are not common. Not everyone exposed to, or colonized by, the organism develops the disease. For unknown reasons, some individuals are susceptible.

With what can tinea versicolor be confused?

The differential diagnosis includes vitiligo and pityriasis alba. If the lesions are tan or pink with scale they may be confused with seborrheic dermatitis.

How is tinea versicolor diagnosed?

A KOH preparation of scraped scale is the mainstay of diagnosis. A “spaghettis and meatball” appearance of short hyphae and spores is characteristic. The organism cannot be cultured using typical fungal culture medium. Under Wood’s light examination the lesions will appear white but not “chalk white”.

How is tinea versicolor treated?

Topical selenium sulfide—found in anti-dandruff shampoos (e.g. Selsun)—is often effective when applied and left on for 10 minutes and then rinsed. When lesions are present, this should be repeated for three days, and then weekly for a month, though other regimens are possible (e.g. two times a week for 2-4 weeks). The entire area from the neck to the knees should be treated. Recurrence can be prevented with periodic application (e.g. every three months). Zinc pyrithione shampoo (Head & Shoulders), topical ketoconazole, and terbinafine spray (Lamisil) are also effective. A single 400 mg dose of oral ketoconazole (Nizoral) is very effective and easy to comply with.

What is the prognosis for tinea versicolor?

The tinea versicolor organism is eradicated rapidly with treatment, but pigmentation takes months to return to normal. The recurrence rate is high (approximately 50%), but prophylactic treatment with topical selenium sulfide or oral ketoconazole (400 mg every three months) can reduce this.

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