International Academy of Cosmetic Dermatology
Tinea versicolor (TV), also called pityriasis versicolor, is a superficial fungal infection, caused by the yeast Malassezia furfur or possibly M. globose. The organism seems to represent the mycelial phase of Pityrosporum ovale and P. orbiculare that are part of the normal skin flora. This may explain why TV can be treated but not cured, thus returning at irregular intervals for many years.
TV is characterized by oval to round to confluent patches of discoloration – white, red, or brown (i.e. versicolor) – and scale, usually found on the trunk but sometimes extending to the neck, face, arms, and even legs. The yeast contains decarboxylic acids which then compete competively to inhibit the dopa-tyrosinase reaction in the melanocytes, thus creating the characteristic discoloration. Another explanation has been the masking of the skin from sunlight by the furfuraceous scales.
TV is readily diagnosed by clinical observation. Occasionally, it can be confused with atopic dermatitis and rarely vitiligo. The diagnosis can be confirmed by performing a KOH scraping, where under the microscope the spaghetti and meatballs appearance of the hyphae and spores can be observed. A Wood’s light examination will show yellowish to yellow-greenish discoloration.
Management can be topical with selenium sulfide shampoo or foam applied for one to two weeks. Other treatments include the use of keratolytic preparations, such as low concentration salycilic acid solutions, and topical antifungal preparations, such as ketoconazole or clotrimazole cream, applied for one to two months. Systemic therapy involves oral ketoconazole, fluconazole, or itraconazole in various regimens, given from a few days to a week. In any case, the scale disappears within a month, but the pigmentation changes takes up to three months to return to normal.
Oumeish Y. Oumeish, MD, FRCP (Glasgow)