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Overview of Skin Pigment

By Shinjita Das, MD, Instructor in Dermatology;Assistant in Dermatology, Harvard Medical School;Massachusetts General Hospital

Melanin is the brown pigment that produces the various shades and colors of human skin. Coloration (pigmentation) is determined by the amount of melanin in the skin. Without melanin, the skin would be pale white with shades of pink caused by blood flow through the skin. Fair-skinned people produce very little melanin, darker-skinned people produce moderate amounts, and very dark-skinned people produce the most. People with albinism have little or no melanin and thus their skin appears white or pale pink. Usually, melanin is fairly evenly distributed in the skin, but sometimes people have spots or patches of skin with more melanin. Examples of such spots include freckles, age spots (lentigines), and melasma.

Melanin is produced by specialized cells (melanocytes) that are scattered among the other cells in the top layer of the skin called the epidermis. After melanin is produced, it spreads into other nearby skin cells.

Pigment disorders

Pigment disorders can be widespread and affect many areas of skin, or they can be localized and affect only certain areas of the skin. The pigmentation changes they cause are called

  • Depigmentation

  • Hypopigmentation

  • Hyperpigmentation

Depigmentation is complete loss of pigment. The skin is white. Widespread depigmentation occurs in vitiligo.

Hypopigmentation is an abnormally low amount of melanin. The skin is lighter in color than normal. Widespread hypopigmentation of the skin occurs in albinism.

Hypopigmentation can be caused by

  • Previous injury to the skin, such as a blister, ulcer, burn, exposure to a chemical, or skin infection

  • Inflammatory conditions of the skin that have healed (such as atopic dermatitis or psoriasis)

  • Rare hereditary conditions

Hyperpigmentation is usually caused by an abnormally high amount of melanin, but sometimes it is caused by deposition of other pigmented substances that are not normally present in the skin. The skin is darker in color and sometimes is a different color than normal. Hyperpigmentation can be caused by

  • Disorders that cause inflammation

  • Drugs

  • Exposure to sunlight

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