Pityrosporum orbiculare, the yeast that causes tinea versicolor, is present in small numbers on normal skin; regular washing rids the skin of dead skin cells as well as excess yeast. But it can grow in great amounts ? during the summer months when humidity sky-rockets or when a person's immune system is weakened ? and interfere with the normal pigmentation of the skin; resulting in unsightly spots in both light and dark colors.

Teens and young adults, regardless of skin color, are the usual victims of tinea versicolor, and those with oily skin may be more prone to it than those with dry skin. In tropical countries, where humidity and temperature are persistently elevated, people of all ages can suffer from these spots all throughout the year.

Flat spots that range in color from white to pink to tan and brown appear over the upper arms, chest, back, neck and face. They vary greatly in size, from as small as four to five millimeters in diameter to large areas of confluence. Scaling may not be readily evident, but scales may easily be obtained by scraping the affected areas. A mild itch may be present, particularly if a person is sweating or feels hot. When the spots involve the neck or face, it can be very disconcerting.

If you think you have white spots or any discolorations of the skin, see a dermatologist. The appearance of the skin is often all that is required to clinch a diagnosis, but microscopic examination of the fine scales can be performed if necessary. When viewed under a special light or chemical preparation, the presence of the yeast can be confirmed.

Tinea versicolor responds to either topical or oral forms of treatment. Topical antifungal creams, ointments, or shampoos ? containing selenium sulfide, keteconazole, zinc-pyrithrone, imidazole, or other medications ? applied directly to affected areas once or twice daily have proven effective. Sulfur soap and salicyclic acid have also been used to rid skin of the yeast. Oral antifungals have been used to treat tinea versicolor resistant to topical applications. In both topical and oral forms of treatment, however, restoration of skin color should be expected several months after yeast has been destroyed. Consult your dermatologist before using any of these medications.

Recurrence is common and medicated cleansers may be needed to prevent relapses. Ask your dermatologist about them. To discourage overgrowth of fungus, keep skin dry and wear thin, loose clothing.