28 FEB 2014
An abnormally high amount of melanin (hyper pigmentation) may affect large areas of the body or small patches. When exposed to sunlight, melanocytes produce increased amounts of melanin, causing the skin to darken, or tan. In some fair-skinned people, certain melanocytes produce more melanin than others in response to sunlight. This uneven melanin production results in spots of pigmentation known as freckles. A tendency to freckle runs in families. Increased amounts of melanin can be produced in response to hormonal changes such as those that may take place, in pregnancy etc. Some cases of skin darkening, however, are not related to increased melanin at all, but rather to abnormal pigments that make their way into the skin Hyper pigmentation can also develop after injuries or inflammation caused by disorders such as acne and lupus.
An abnormally low amount of melanin (hypo pigmentation) may affect large areas of the body or small patches. Decreased melanin usually results from a previous injury to the skin, such as a blister, ulcer, burn, exposure to a chemical, or skin infection. Sometimes pigment loss results from an inflammatory condition of the skin or, in rare instances, is hereditary.