Vitiligo is an acquired skin disorder characterized by macules (patches) of depigmented (colorless) skin surrounded by areas of normal skin. It is not contagious and generally poses no medical problems.

The depigmented macules result from a complete absence of functional melanocytes (cells that produce melanin, the substance responsible for skin color). Melanin is produced in the epidermis, the top layer of skin. In addition to the skin, patches of hair, mucous membranes (e.g., inside the mouth) and sometimes the retina of the eye may also be affected.

The onset of vitiligo is usually gradual, with the appearance of a few spots. Often, light-skinned people do not notice these macules until spring or summer time, when increased sun exposure causes skin to tan. The loss of pigment may be rapid or gradual. Periods of pigment loss may be followed by periods of stability, a cycle that may continue indefinitely. There also appears to be a link between stress and illness and additional pigment loss.

There is no way to know how progressive a given case of vitiligo may be. In some cases, depigmentation may spread over the entire body. Color may return to the skin spontaneously, but this is rare and typically very limited.

Vitiligo is a relatively common disorder. According to the National Institutes of Health (NIH), it affects 2 to 5 million people in the United States and 40 to 50 million people worldwide. Men and women of all races are affected equally, although the condition is more pronounced in dark-skinned people due to the sharp contrast between affected and unaffected skin. Onset may occur at any time shortly after birth, but the average age of onset is about 20 years, with most cases beginning when patients are in their 20s or 30s. Onset after the age of 40 is very rare.