Tinea versicolor differs from the other tineas, as it is not caused by dermatophyte, but rather by a skin yeast known as pityrosporum. This yeast normally lives in the pores in a dormant state. However, under the right circumstances where heat, sweating, and friction are present, the yeast can begin to grow actively out onto the surface of the skin. There, it forms numerous small round scaly patches that gradually join to form larger areas. In many cases, the growing yeast produces a chemical that temporarily stops the pigment cells from working. The result is small round areas that will not tan, leaving the patient covered with “white spots.”
Treatment of limited cases can be done with topical antifungal creams. In years past, sulfur-based shampoos were used to treat the rash. Now, short courses of oral medications are often used, as they are much faster, more effective, and easier than shampooing.