In dermatology

Dermatology

Dermatology is the branch of medicine dealing with the skin and its diseases, a unique specialty with both medical and surgical aspects. A dermatologist takes care of diseases, in the widest sense, and some cosmetic problems of the skin, scalp, hair, and nails....

, hyperpigmentation is the darkening of an area of skin

Skin

-Dermis:The dermis is the layer of skin beneath the epidermis that consists of connective tissue and cushions the body from stress and strain. The dermis is tightly connected to the epidermis by a basement membrane. It also harbors many Mechanoreceptors that provide the sense of touch and heat...

 or nails

Nail (anatomy)

A nail is a horn-like envelope covering the dorsal aspect of the terminal phalanges of fingers and toes in humans, most non-human primates, and a few other mammals. Nails are similar to claws, which are found on numerous other animals....

 caused by increased melanin

Melanin

Melanin is a pigment that is ubiquitous in nature, being found in most organisms . In animals melanin pigments are derivatives of the amino acid tyrosine. The most common form of biological melanin is eumelanin, a brown-black polymer of dihydroxyindole carboxylic acids, and their reduced forms...

.

Causes

Hyperpigmentation may be caused by sun damage, inflammation

Inflammation

Inflammation is part of the complex biological response of vascular tissues to harmful stimuli, such as pathogens, damaged cells, or irritants. Inflammation is a protective attempt by the organism to remove the injurious stimuli and to initiate the healing process...

, or other skin injuries, including those related to acne vulgaris

Acne vulgaris

Acne vulgaris is a common human skin disease, characterized by areas of skin with seborrhea , comedones , papules , pustules , Nodules and possibly scarring...

. 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

Melanin

Melanin is a pigment that is ubiquitous in nature, being found in most organisms . In animals melanin pigments are derivatives of the amino acid tyrosine. The most common form of biological melanin is eumelanin, a brown-black polymer of dihydroxyindole carboxylic acids, and their reduced forms...

. Hyperpigmentation can be diffuse or focal, affecting such areas as the face and the back of the hands. Melanin

Melanin

Melanin is a pigment that is ubiquitous in nature, being found in most organisms . In animals melanin pigments are derivatives of the amino acid tyrosine. The most common form of biological melanin is eumelanin, a brown-black polymer of dihydroxyindole carboxylic acids, and their reduced forms...

 is produced by melanocytes at the lower layer of the epidermis. Melanin

Melanin

Melanin is a pigment that is ubiquitous in nature, being found in most organisms . In animals melanin pigments are derivatives of the amino acid tyrosine. The most common form of biological melanin is eumelanin, a brown-black polymer of dihydroxyindole carboxylic acids, and their reduced forms...

 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

Melanocyte

-External links: - "Eye: fovea, RPE" - "Integument: pigmented skin"...

 distribution becomes less diffuse and its regulation less controlled by the body. UV light stimulates melanocyte

Melanocyte

-External links: - "Eye: fovea, RPE" - "Integument: pigmented skin"...

 activity, and where concentrations of the cells are denser than surrounding areas, hyperpigmentation is effected. Can also be caused by using skin lightening lotions.

Hyperpigmentation is associated with a number of diseases or conditions, including:

• Addison's disease
  Addison's disease
  Addison’s disease is a rare, chronic endocrine disorder in which the adrenal glands do not produce sufficient steroid hormones...
  
   and other sources of adrenal insufficiency
  Adrenal insufficiency
  Adrenal insufficiency is a condition in which the adrenal glands, located above the kidneys, do not produce adequate amounts of steroid hormones , primarily cortisol, but may also include impaired aldosterone production which regulates sodium, potassium and water retention...
  
  , in which hormones that stimulate melanin synthesis, such as melanocyte-stimulating hormone
  Melanocyte-stimulating hormone
  The melanocyte-stimulating hormones are a class of peptide hormones that are produced by cells in the intermediate lobe of the pituitary gland...
  
   (MSH), are frequently elevated.
• Cushing's disease
  Cushing's disease
  Cushing's disease is a cause of Cushing's Syndrome characterised by increased secretion of adrenocorticotropic hormone from the anterior pituitary. This is most often as a result of a pituitary adenoma...
  
   or other excessive adrenocorticotropic hormone
  Adrenocorticotropic hormone
  Adrenocorticotropic hormone , also known as 'corticotropin', 'Adrenocorticotrophic hormone', is a polypeptide tropic hormone produced and secreted by the anterior pituitary gland. It is an important component of the hypothalamic-pituitary-adrenal axis and is often produced in response to biological...
  
   (ACTH) production, because MSH production is a byproduct of ACTH synthesis from proopiomelanocortin
  Proopiomelanocortin
  Pro-opiomelanocortin is a precursor polypeptide with 241 amino acid residues. POMC is synthesized from the 285-amino acid long polypeptide precursor, pre-pro-opiomelanocortin , by the removal of a 44-amino acid long signal peptide sequence during translation.The POMC gene is located on chromosome...
  
   (POMC).
• Acanthosis nigricans
  Acanthosis nigricans
  Acanthosis nigricans is a brown to black, poorly defined, velvety hyperpigmentation of the skin. It is usually found in body folds, such as the posterior and lateral folds of the neck, the axilla, groin, umbilicus, forehead, and other areas.-Causes:...
  
   – hyperpigmentation of intertriginous
  Intertriginous
  Intertriginous is a medical term used to define an area where two skin areas may touch or rub together. Examples of intertriginous areas are the axilla of the arm, the anogenital region, nares, skin folds of the breasts, and between digits...
  
   areas associated with insulin resistance
  Insulin resistance
  Insulin resistance is a physiological condition where the natural hormone insulin becomes less effective at lowering blood sugars. The resulting increase in blood glucose may raise levels outside the normal range and cause adverse health effects, depending on dietary conditions. Certain cell types...
  
  .
• Melasma
  Melasma
  Melasma is a tan or dark skin discoloration. Although it can affect anyone, melasma is particularly common in women, especially pregnant women and those who are taking oral or patch contraceptives or hormone replacement therapy medications...
  
  , also known as chloasma – patchy hyperpigmentation often found in pregnant women.
• Linea nigra – a hyperpigmented line found on the abdomen
  Abdomen
  In vertebrates such as mammals the abdomen constitutes the part of the body between the thorax and pelvis. The region enclosed by the abdomen is termed the abdominal cavity...
  
   during pregnancy
  Pregnancy
  Pregnancy refers to the fertilization and development of one or more offspring, known as a fetus or embryo, in a woman's uterus. In a pregnancy, there can be multiple gestations, as in the case of twins or triplets...
  
  .
• Peutz-Jeghers syndrome
  Peutz-Jeghers syndrome
  Peutz–Jeghers syndrome, also known as hereditary intestinal polyposis syndrome, is an autosomal dominant genetic disease characterized by the development of benign hamartomatous polyps in the gastrointestinal tract and hyperpigmented macules on the lips and oral mucosa...
  
   – an autosomal dominant disorder characterized by hyperpigmented macules on the lips and oral mucosa and gastrointestinal polyps
  Polyp (medicine)
  A polyp is an abnormal growth of tissue projecting from a mucous membrane. If it is attached to the surface by a narrow elongated stalk, it is said to be pedunculated. If no stalk is present, it is said to be sessile. Polyps are commonly found in the colon, stomach, nose, sinus, urinary bladder...
  
  .
• Exposure to certain chemicals such as salicylic acid
  Salicylic acid
  Salicylic acid is a monohydroxybenzoic acid, a type of phenolic acid and a beta hydroxy acid. This colorless crystalline organic acid is widely used in organic synthesis and functions as a plant hormone. It is derived from the metabolism of salicin...
  
  , bleomycin
  Bleomycin
  Bleomycin is a glycopeptide antibiotic produced by the bacterium Streptomyces verticillus. Bleomycin refers to a family of structurally related compounds. When used as an anticancer agent, the chemotherapeutical forms are primarily bleomycin A2 and B2. It works by causing breaks in DNA...
  
  , and cisplatin
  Cisplatin
  Cisplatin, cisplatinum, or cis-diamminedichloroplatinum is a chemotherapy drug. It is used to treat various types of cancers, including sarcomas, some carcinomas , lymphomas, and germ cell tumors...
  
  .
• Smoker's melanosis
  Smoker's melanosis
  Smoker's melanosis is characterized by flat, irregular hyperpigmentation of the connective tissue underlying the oral mucosa resulting from tobacco smoking. Basal cells and macrophages in the underlying connective tissue contain unusual amounts of melanin, which creates the darker pigmentation...
  
  
• Celiac disease
• Cronkite-Canada syndrome
• Porphyria
  Porphyria
  Porphyrias are a group of inherited or acquired disorders of certain enzymes in the heme bio-synthetic pathway . They are broadly classified as acute porphyrias and cutaneous porphyrias, based on the site of the overproduction and accumulation of the porphyrins...
  
  
• Tinea
  Tinea
  Tinea is a general term used to describe skin mycoses. The term ringworm is even less precise, but is usually considered a synonym.It is sometimes equated with dermatophytosis, and it is true that most conditions identified as "tinea" are members of the imperfect fungi that make up the dermatophytes...
  
   fungal infections such as ringworm
• Haemochromatosis
  Haemochromatosis
  Haemochromatosis type 1 is a hereditary disease characterized by excessive intestinal absorption of dietary iron resulting in a pathological increase in total body iron stores. Humans, like most animals, have no means to excrete excess iron...
  
   - a common but debilitating genetic disorder characterized by the chronic accumulation of iron in the body.
• Mercury poisoning
  Mercury poisoning
  Mercury poisoning is a disease caused by exposure to mercury or its compounds. Mercury is a heavy metal occurring in several forms, all of which can produce toxic effects in high enough doses...
  
   - particularly cases of cutaneous exposure resulting from the topical application of mercurial ointments or skin-whitening creams.
• Aromatase deficiency
  Aromatase deficiency
  Aromatase deficiency is a condition resulting from insufficient production of the enzyme aromatase, which can lead to inappropriate virilization.One notable feature is that it can also affect the mother during gestation that resolves after birth...
  
  
• Nelson's syndrome
  Nelson's syndrome
  Nelson's syndrome is the rapid enlargement of a pituitary adenoma that occurs after the removal of both adrenal glands.-Pathophysiology:Removal of both adrenal glands, or bilateral adrenalectomy, is an operation for Cushing's syndrome...
  
  

Hyperpigmentation can sometimes be induced by dermatological laser

Laser

A laser is a device that emits light through a process of optical amplification based on the stimulated emission of photons. The term "laser" originated as an acronym for Light Amplification by Stimulated Emission of Radiation...

 procedures.

Treatment

Treatment of hyperpigmentation may include hydroquinone

Hydroquinone

Hydroquinone, also benzene-1,4-diol or quinol, is an aromatic organic compound that is a type of phenol, having the chemical formula C6H42. Its chemical structure, shown in the table at right, has two hydroxyl groups bonded to a benzene ring in a para position. It is a white granular solid...

, kojic acid

Kojic acid

Kojic acid is a chelation agent produced by several species of fungi, especially Aspergillus oryzae, which has the Japanese common name koji. Kojic acid is a by-product in the fermentation process of malting rice, for use in the manufacturing of sake, the Japanese rice wine...

, alpha hydroxy acids, azelaic acid

Azelaic acid

Azelaic acid is an organic compound with the formula 72. This saturated dicarboxylic acid exists as a white powder. It is found in wheat, rye, and barley. It is a component of a number of hair and skin conditioners.-Production:...

, ascorbic acid

Ascorbic acid

Ascorbic acid is a naturally occurring organic compound with antioxidant properties. It is a white solid, but impure samples can appear yellowish. It dissolves well in water to give mildly acidic solutions. Ascorbic acid is one form of vitamin C. The name is derived from a- and scorbutus , the...

, tretinoin

Tretinoin

Tretinoin is the acid form of vitamin A and is also known as all-trans retinoic acid or ATRA. It is a drug commonly used to treat acne vulgaris and keratosis pilaris. It is available as a cream or gel...

 (Retinol

Retinol

Retinol is one of the animal forms of vitamin A. It is a diterpenoid and an alcohol. It is convertible to other forms of vitamin A, and the retinyl ester derivative of the alcohol serves as the storage form of the vitamin in animals....

), topical glucocorticoid

Glucocorticoid

Glucocorticoids are a class of steroid hormones that bind to the glucocorticoid receptor , which is present in almost every vertebrate animal cell...

s, and licorice extract.

External links

Hyperpigmentation Treatment