Possible causes of patchy skin discoloration include changes in melanin, the chemicals in the skin responsible for color, bacterial or other infections, or changes in the blood vessels, according to MedlinePlus. Generally, such changes are cosmetic and do not cause other physical health problems, but they often cause mental stress.
Genetics, heat, sun exposure, hormonal changes or injury often affects the production of melanin, according to MedlinePlus. Sun or ultraviolet light exposure causes the pigments in the skin to darken, especially in fair-skinned individuals. Exposure to ultraviolet light from any source also increases the chances of skin cancer.
Vitiligo is a condition where white patches develop on the skin, according to WebMD. The condition affects any part of the body, and people with the condition often have white patches in several locations. Vitiligo is due to a loss of melanin in the affected areas. It affects up to 5 million Americans or roughly 2 percent of the population.
The skin sometimes returns to the normal color. However, if the discoloration remains, MedlinePlus indicates use of skin bleaching products help to reduce the patchiness of the skin. Cosmetics are also useful in helping to even the skin tone. While these products do not offer a cure for the underlying condition, they often help the individual reduce his mental stress related to the condition.