Skin Pigmentation Disorders
Skin pigmentation disorders are conditions that cause the skin to appear lighter or darker than normal, or blotchy and discolored.
Skin pigmentation disorders occur because the body produces either too much or too little melanin, a pigment that creates hair, skin, and eye color. Melanin protects the body by absorbing ultraviolet light.
In hypopigmentation means the body does not produces enough melanin. Albinism, for example, is an inherited condition that causes a lack of pigment. So people with albinism typically have light skin, white or pale yellow hair, and light blue or gray eyes. Another condition called vitilgo, creates smooth, depigmented white spots on the skin. Vitilgo affects nearly 2% of the population, but it strikes people between 10 and 30 years old more often, and is more evident in people with darker skin.
In hyperpigmentation, the body produces too much melanin, causing skin to become darker than usual. Lichen simplex chronicus is a skin disorder with severe itching that causes thick, dark patches of skin to develop. Lamellar ichthyosis (fish scale disease) is an inherited disease that also is characterized by darkened, scaly, dry patches of skin.
Hyperpigmentation also occurs in melasma, a dark mask-like discoloration that covers the cheeks and bridge of the nose. Melasma can occur during the end of pregnancy. People with the autoimmune disease (when immune cells, which attack invaders, become abnormally programed to kill self cells inside the body) systemic lupus also may develop a similar butterfly-shaped mask on their faces. In addition, many people have moles, freckles, age spots, and birthmarks, ranging from red or brown to bluish-black, covering various parts of their bodies.
Causes and symptoms
Scientists are still studying the reasons why skin pigmentation disorders occur. In some cases there are tangible causes, such as sun exposure, drug reactions or genetic inheritance. In other cases, it is not as clear.
Albinism is an inherited recessive trait. Albinism has many different forms, but most people who have this condition have pale skin, hair, and eyes. Melanin also creates eye color, and serves as a filter that prevents too much light from entering the eye. Since they lack melanin in their eyes, many people with albinism also have visual impairment. With little skin pigmentation, they also sunburn easily and are more prone to skin cancer.
The hypopigmentation spots associated with vitilgo sometimes form where a person has been cut or injured. Research has shown that the light patches associated with vitilgo do not contain melanocytes, the type of skin cells that create melanin. Some scientists believe vitilgo may be caused by an autoimmune disorder. It also has been linked to other conditions such as hyperthyroidism (too much thyroid hormone) and Addison's Disease, which affects the adrenal gland.
Hyperpigmentation can be caused by many factors, from too much sunbathing to drug reactions or poor nutrition. Wounds and scars also can develop darker patches of skin. A psychological syndrome gives people with lichen simplex chronicus to develop a compulsive need to scratch, which causes dark, leathery skin to form. This can lead to permanent scarring and infection if untreated. Scientists believe lamellar ichthyosis is caused by genetics.
The mask caused by melasma may be related to pregnancy hormones, and usually disappears after a woman gives birth. Birthmarks, moles, and aging spots usually are harmless. Some moles, however, can change in size, color, texture, or start bleeding, which could indicate possible skin cancer.
Diagnostic tests vary for different types of skin pigmentation disorders. Physicians usually can diagnose albinism by looking carefully at a person's hair, skin, and eyes. They may order blood tests and eye exams as well. A visual exam also is enough to diagnose vitilgo.
For most hyperpigmentation disorders, doctors can make a diagnosis by looking at a person's appearance. To detect conditions like lichen simplex chronicus or lamellar ichthyosis, or skin cancer they may also do a biopsy, to remove some of the affected skin for further study under a microscope. Some physicians also use a wood's lamp, or black light test, to diagnose skin conditions. Affected areas would absorb the ultraviolet light and stand out with flourescent colors in the darkened room.
For albinism, health care providers advise people to cover up, use sunscreen and avoid excess sunlight to prevent skin cancer. People with albinism also must wear protective sunglasses and, in some cases, prescription corrective lenses. Surgery may be necessary to correct visual impairments.
To treat vitilgo, physicians may prescribe a combination of photo-sensitive medications like trimethylpsoralen and ultraviolet light therapy to darken the spots. If the person has depigmented patches covering more than 50% of the body, doctors also may be able to use skin bleaching agents like monobenzone to give the skin a lighter, more uniform appearance. Other options include cosmetic concealers and skin grafting.
Skin-lightening creams are available for hyperpigmentation disorders. Doctors also advise staying out of the sun. Counseling with a dietitian may help in cases caused by poor nutrition. For lichen simplex chronicus, doctors could prescribe antihistamines and topical steroid creams to stop the itching. If a mole or birthmark appears suspicious, physicians often will surgically remove it to prevent skin cancer.
Most skin pigmentation disorders do not affect a person's health, only the outward appearance.
In most cases, doctors will recommend using sunscreen and avoiding too much sun exposure.
Levine, Norman. Pigmentation and Pigmentary Disorders. CRC Press, 1993.
Wilson, Tracy. "The Paler Side of Beauty." Heart and Soul 6, no. 1 (February, 1999): 30-33.
American Academy of Dermatology. 1350 I St. NW, Washington, DC, 20005-4355. (202) 842-3555. <http://www.aad.org>.
National Organization for Albinism and Hypopigmentation (NOAH), 1530 Locust St., #29, Philadelphia, PA, 19102-4415. (800) 473-2310. <http://www.albinism.org>.
National Weather Service. "Ultraviolet Light Index." <http://www.nws.noaa.gov/pa/secnews/uv/index.html>.
Melanin—A pigment that creates hair, skin and eye color. Melanin also protects the body by absorbing ultraviolet light.
Melanocytes—The type of skin cells that create melanin.
Albinism—An inherited condition that causes a lack of pigment. People with albinism typically have light skin, white or pale yellow hair and light blue or gray eyes
Hypopigmentation—A skin condition that occurs when the body has too little melanin, or pigment.
Hyperpigmentation—A skin condition that occurs when the body has too much melanin, or pigment.
Lichen simplex chronicus—A skin disorder with severe itching that causes thick, dark patches of skin to develop.
Vitilgo—A skin disorder that creates smooth, depigmented white spots on the skin.
Lamellar ichthyosis—Also called fish scale disease, this inherited condition is characterized by darkened, scaly, dry patches of skin.
Melasma—A dark mask-like discoloration that covers the cheeks and bridge of the nose. Also called "the mask of pregnancy."