The fungus depigments the skin as it grows and the disease appears as many little light patches perhaps an eight to a quarter inch in diameter on the affected upper body areas. A tan just makes the depigmentation stand out more, so it seems to be a disease of the summer months, but it isn't. It's caused when fungal spores from the hair fall on the upper body and germinate on the skin. The light areas of skin will gradually fill back in with normal skin pigment. That has been the standard treatment, but it is often pretty unpopular with the patients.
Selenium sulfide smells rather like rotten eggs and is drying and irritating.