Tinea versicolor (also known as pityriasis versicolor) is a fungal infection that causes a skin rash. The rash is formed by many small spots that typically appear on the oily parts of the upper body, usually on the chest, back, and upper arms. The spots are flat and may be white, pink, red, tan, or brown. Each person's spots are usually the same color, either lighter or darker than the rest of the skin.