Tinea (or pityriasis) versicolor (TV) is a common fungal skin infection that causes the skin to turn a variety of colors (therefore “versicolor”). It is caused by Malassezia yeasts that live on human skin. Sebaceous skin glands release a fatty, oily substance that is called sebum through hair follicles. Sebum provides nutrients that are necessary for the yeasts to survive on the skin. Living in a hot, humid climate, sweating excessively, or having a weakened immune system allows the fungus to flourish. Tinea versicolor is most commonly seen in adolescents and young adults and can affect some families more than others, however it is not contagious. Because the fungus interferes with the function of melanocytes (skin cells that produce skin pigment), it can cause the affected skin areas to be lighter in shade than the surrounding unaffected skin. This is often more visible in the summer months due to sun exposure as sunlight stimulates melanocytes to make skin pigment (otherwise known as tanning). Typically, the chest and back are most affected by TV as those skin areas have the highest number of sebaceous glands, however TV can also occur on the upper arms, neck, and face. Skin infected by TV will have a blotchy, mottled appearance. Scales, or skin flakes, can also be seen with TV. Otherwise, the only other symptom of TV may be mild itchiness.
TV may be diagnosed by scraping the affected area of the skin and examining it under a microscope. The yeast cells have a round and long, narrow form often resembling, and therefore called, “spaghetti and meatballs.” Alternatively, scraping or stretching the skin may cause more flakes to form. This is called the evoked scale sign. Microscopic examination or looking for the evoked scale sign is often unnecessary as the appearance of the skin is usually enough to make the diagnosis. TV is notoriously difficult to treat, and relapses are common. Treatment usually starts with selenium sulfide shampoo (aka dandruff shampoo) as this causes the outermost portion of the skin to shed, thereby removing the fungus. This treatment is done daily for one week, however repeated treatment is often necessary. Topical antifungals like ketoconazole and zinc pyrithione are other common treatment options. Rarely, if the skin infection is widespread or resistant to other treatments, oral antifungals may be used, however, due to the risk to toxicity with oral antifungals, this is almost never advised. It is important to remember that it may take months for the skin to return to normal appearance after successful treatment. Often, the persistence of a blotchy skin pattern may be mistaken for failed treatment. Summertime relapses are common and, for those with frequent recurrences, monthly treatments may be necessary.
For more information, go to the American Academy of Dermatology website at www.aad.org
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