Pityriasis versicolor is a relatively common superficial skin disease caused by the yeast fungus Malassezia furfur. It most often occurs in places richer in sebaceous and sweat glands. Therefore, people who have more sebum production and sweat more are more susceptible to this disease. It is diagnosed based on the clinical appearance, but also by examination using a Wood's lamp, which is a lamp with a UVA emitter placed in a darkened room. The treatment consists in the use of antifungal, i.e. anti-yeast preparations.