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Overview of Pigmentation Disorders

By

Shinjita Das

, MD, Harvard Medical School

Last full review/revision Dec 2020| Content last modified Dec 2020
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Melanin is the brownish pigment responsible for the color of skin, hair, and the iris of the eyes. It is produced by melanocytes. Most people have similar numbers of melanocytes, and the wide range of color shades of human skin is due to the amount of melanin that is produced rather than the number of melanocytes. There are different subtypes of melanin, the main ones in the skin being

  • Eumelanin (brown and black types)

  • Pheomelanin, which has a reddish hue

Ultraviolet radiation, as in sunlight, stimulates melanin production, as do a number of pathologic processes. Other factors can interfere with melanin production.

Pigmentation disorders involve hypopigmentation, depigmentation, or hyperpigmentation. Areas may be focal or diffuse. In hypopigmentation, pigment is decreased, whereas in depigmentation, pigment is completely lost, leaving white skin.

Focal hypopigmentation is most commonly a consequence of

Focal hypopigmentation or depigmentation is also a feature of vitiligo Vitiligo Vitiligo is a loss of skin melanocytes that causes areas of skin depigmentation of varying sizes. Cause is unknown, but genetic and autoimmune factors are likely. Diagnosis is usually clear... read more Vitiligo (which may involve large areas of skin), leprosy Leprosy Leprosy is a chronic infection usually caused by the acid-fast bacilli Mycobacterium leprae, which has a unique tropism for peripheral nerves, skin, and mucous membranes of the upper respiratory... read more Leprosy , nutritional deficiencies (kwashiorkor Protein-energy undernutrition (PEU), previously called protein-energy malnutrition, is an energy deficit due to deficiency of all macronutrients. It commonly includes deficiencies of many micronutrients... read more ), genetic conditions (eg, tuberous sclerosis Tuberous Sclerosis Complex (TSC) Tuberous sclerosis complex is a dominantly inherited genetic disorder in which tumors (usually hamartomas) develop in multiple organs. Diagnosis requires specific clinical criteria and imaging... read more Tuberous Sclerosis Complex (TSC) , piebaldism, Waardenburg syndrome), morphea (localized scleroderma, in which skin is usually sclerotic), lichen sclerosus Lichen Sclerosus Lichen sclerosus is an inflammatory dermatosis of unknown cause, possibly autoimmune, that usually affects the anogenital area. The earliest signs are skin fragility, bruising, and sometimes... read more Lichen Sclerosus , pityriasis versicolor (or tinea versicolor Tinea Versicolor Tinea versicolor is skin infection with Malassezia furfur that manifests as multiple asymptomatic scaly patches varying in color from white to tan to brown to pink. Diagnosis is based on clinical... read more Tinea Versicolor ), idiopathic guttate hypomelanosis, progressive macular hypomelanosis, postinflammatory hypopigmentation, and pityriasis alba.

Diffuse hypopigmentation or depigmentation is most often caused by

Hyperpigmentation Hyperpigmentation Hyperpigmentation has multiple causes and may be focal or diffuse. Most cases are due to an increase in melanin production and deposition. (See also Overview of Pigmentation Disorders.) Focal... read more Hyperpigmentation typically occurs after inflammation resulting from various causes. This postinflammatory hyperpigmentation is usually focal in distribution. Hyperpigmentation may also be caused by a systemic disorder, drug, or cancer; in such cases, distribution is usually more diffuse.

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