This is a common skin disease caused by an overgrowth of the yeast fungus called Pityrosporum orbiculare (Malassezia furfur).

Most adults have Pityrosporum orbiculare on their skin; however, in a few people its presence results in a harmless skin disease.

Pityrosporum orbiculare also plays a role in the development of cradle cap (seborrhoeic dermatitis).