Skin color is determined by a pigment (melanin) made by specialized cells in the skin (melanocytes). The amount and type of melanin determines a person’s skin color.
Various shades and colors of human skin are created by the brown pigment, melanin. Without melanin, the skin would be pale white with varying 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.
What is the function of melanin?
Melanin gives color to the skin, hair, and iris of the eyes. Levels of melanin depend on race and amount of sunlight exposure.
Sun exposure increases melanin production to protect the skin against harmful ultraviolet rays. In addition, hormonal changes can affect melanin production.
Melanin is produced by specialized cells (melanocytes) that are interspersed among the other cells in the top layer of the skin, the epidermis. After melanin is produced, it spreads into other nearby skin cells.
An abnormally high amount of melanin (hyperpigmentation) 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 Addison disease, in pregnancy, or with hormonal contraceptive use.
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.
Diseases such as hemochromatosis or hemosiderosis or some drugs and chemicals that are applied to the skin, swallowed, or injected can cause skin darkening.
Drugs and chemicals that can cause skin darkening include amiodarone, hydroquinone, antimalarial drugs, tetracycline antibiotics, phenothiazines, and some cancer chemotherapy drugs, tricyclic antidepressants, and heavy metals.
A buildup of bilirubin (the main pigment in bile) causes the skin to turn yellow (jaundice). Hyperpigmentation can also develop after injuries or inflammation caused by disorders such as acne and lupus.
An abnormally low amount of melanin (hypopigmentation) 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.
What is melasma?
Melasma, more commonly known as the pregnancy mask, is thought to affect 5 – 6 million women in the USA, 50 to 75% of pregnant women in the USA and 80% of pregnant women in Mexico.
It can occur after exposure to the sun or hormonal changes (pregnancy, oral contraception, etc.), causing an increase of melanin in the skin (the substance that gives skin its color).
It is considered a chronic disease that can sometimes appear before pregnancy, disappear a few months after giving birth, reappear in subsequent pregnancies or last for several years.
Pigmentation usually affects the face and mainly the cheeks, forehead and upper lips.
How to treat melasma
The disease is generally treated with a combination of active ingredients for topical application; the most efficient being a triple combination drug, which must be used everyday, while applying a broad spectrum sunscreen several times a day.
What is vitiligo?
Vitiligo is an acquired skin disease characterized by circumscribed depigmented lesions. It may appear anytime from shortly after birth to old age and affects 1.3% of the population.
The onset can be precipitated by specific life events (physical injury, sunburn, emotional injury, illness, pregnancy). Both sexes are affected equally.
Lesions are uniformly milky-white, round, oval or linear in shape, vary in size and appear anywhere on the body, but mainly in areas of repeated trauma, pressure or friction (elbows, knees, fingers and toes).
Genetic, immunologic, environmental and stress factors are thought to be involved.
How to treat vitiligo
Vitiligo is a difficult disease to treat. When it is of limited extent, topical treatments can be used; but when a large surface of the body is affected, ultraviolet light (UV) therapy is recommended, alone or in combination with topical treatments.