Tinea Versicolor

What Is It?

Many microorganisms are normally live on our skin, including a yeast called Pityrosporum orbiculare. The yeast lives in our pores. Under certain conditions, it can grow out of control and produce a rash called tinea versicolor, also called pityriasis versicolor.

Tinea versicolor is common year-round in the tropics and subtropics, and is seen in the summer months in more temperate climates, because the yeast grows best in hot and humid conditions. The rash occurs more often in teen-agers and young adults, and appears on the back, neck, upper chest, shoulders, armpits and upper arms. It is more likely to occur on oily skin.

It is not clear why some people get tinea versicolor, while others do not. The yeast grows slowly and normally is washed off the skin during normal cleansing.

Symptoms

The main symptom is a skin rash that consists of peeling, oval patches with sharply defined borders and pimple-like bumps. On dark-skinned people the patches can appear white or black. On light-skinned people they are usually pink or tan, sometimes with a reddish tint. The rash may be itchy, especially when a person is hot or sweaty.

The patches may be more obvious after skin has been exposed to the sun, because the patches do not tan. Sun exposure makes the condition worse.

Diagnosis

Your doctor can shine an ultraviolet light on the rash. If your skin is infected with P. orbiculare, the rash will glow under the light. Your doctor also can take skin scrapings from the lesions and examine them under the microscope to see if the yeast is present.

Expected Duration

The yeast responds well to treatment, but the changes in skin color may remain for several months, especially if you have spent time in the sun. Wearing a strong sunscreen and taking other precautions against sun exposure can minimize the difference in skin color between normal skin and skin affected by tinea versicolor.

Prevention

Because the yeast grows more readily in hot, humid conditions, keep your skin as dry and cool as possible. Tinea versicolor can be spread through skin-to-skin contact or by coming in contact with contaminated articles such as unwashed towels or bedding. Tinea versicolor is more common in people who have a suppressed immune system (for instance, people who are taking a corticosteroid medication such as prednisone for another health problem). It is also more common in women who are taking birth-control pills and pregnant women.