In dermatology, hyperpigmentation is the darkening of an area of skin or nails caused by increased melanin.
Hyperpigmentation may be caused by sun damage, inflammation,
or other skin injuries, including those related to acne vulgaris.
People with darker Asian, Mediterranean or African skin tones are also
more prone to hyperpigmentation, especially if they have excess sun
exposure.
Many forms of hyperpigmentation are caused by an excess
production of melanin.
Hyperpigmentation can be diffuse or focal,
affecting such areas as the face and the back of the hands. Melanin is
produced by melanocytes at the lower layer of the epidermis.
Melanin is a
class of pigment responsible for producing color in the body in places
such as the eyes, skin, and hair. As the body ages, melanocyte
distribution becomes less diffuse and its regulation less controlled by
the body.
UV light stimulates melanocyte activity, and where
concentrations of the cells are denser than surrounding areas,
hyperpigmentation is effected.
Hyperpigmentation is associated with a number of diseases or
conditions, including:
- Addison's disease and other sources of adrenal
insufficiency, in which hormones that stimulate melanin synthesis, such
as melanocyte-stimulating hormone (MSH), are frequently elevated.
- Cushing's disease or other excessive adrenocorticotropic
hormone (ACTH) production, because MSH production is a byproduct of ACTH
synthesis from proopiomelanocortin (POMC).
- Acanthosis nigricans – hyperpigmentation of intertriginous
areas associated with insulin resistance.
- Melasma, also known as ''chloasma'' – patchy
hyperpigmentation often found in pregnant women.
- Linea nigra – a hyperpigmented line found on the abdomen
during pregnancy.
- Peutz-Jeghers syndrome – an autosomal dominant disorder
characterized by hyperpigmented macules on the lips and oral mucosa and
gastrointestinal polyps.
- Certain chemicals such as salicylic acid, bleomycin, and
cisplatin.
- Smoker's melanosis
- Celiac disease
- Cronkite-Canada syndrome
- Porphyria
- Tinea fungal infections such as ringworm
- Haemochromatosis - a common but debilitating genetic
disorder characterized by the chronic accumulation of iron in the body.
- Powdered jet injections
Hyperpigmentation can sometimes be induced by dermatological
laser procedures.
Treatment of hyperpigmentation may include hydroquinone, kojic acid,
alpha hydroxy acids, azelaic acid, ascorbic acid, tretinoin (Retinol),
topical glucocorticoids, and licorice extract.
All treatments fail if
the affected area is exposed to the sun without adequate UVA/UVB
protection.
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"Hyperpigmentation"
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