Hi,
Tinea versicolor or pityriasis versicolor is a common skin
infection caused by the
yeast Malassezia furfur . This yeast is normally found on the human skin and only becomes troublesome under certain circumstances, such as a warm and humid environment.
Generally oval or irregularly-shaped spots of 1/4 to 1 inch in diameter, often merging together to form a larger patch, which commonly affect the back, underarm, upper arm, chest, lower legs, and neck.