<unk>  or pityriasis<unk>  is a common skin infection caused by the yeast Malassezia furfur (formerly termed Pityrosporum ovale).  This yeast is normally found on the human skin and only becomes troublesome under certain circumstances, such as a warm and humid environment.
The symptoms of this condition include:
Generally oval or irregularly-shaped spots of 1/4 to 1 inch in diameter, often merging together to form a larger patch
Occasional fine scaling of the skin producing a very superficial ash-like scale
Pale, dark tan, or pink in color, with a reddish undertone that can darken when the patient is overheated, such as in a hot shower or during/after exercise
Sharp border
These spots commonly affect the back, underarm, upper arm, chest, lower legs, and neck.  Occasionally it can also be present on the face.  The yeasts can often be seen under the microscope within the lesions and typically have a so called "spaghetti and meat ball appearance" as the round yeasts produce filaments.
In people with dark skin tones, pigmentary changes such as hypopigmentation (loss of color) are common, while in those with lighter skin color, hyperpigmentation (increase in skin color) are more common.  These discolorations have led to the term "sun fungus".
Tinea versicolor
Tinea faciei
Linea negra
Tinea corporis
Tinea barbae
Tinea manuum
Sycosis vulgaris
Onychomycosis