Acanthosis nigricans - Pictures - Treatment - Causes

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Acanthosis nigricans (AN) is a hyperpigmentation disorder (see images) of the skin. Obesity is one of the major causes of acanthosis nigricans.

The treatment of acanthosis nigricans is directed towards the underlying causes for the resolution of the condition.

Acanthosis nigricans signs, symptoms and diagnosis

• This skin disorder is identifiable by the development of symmetrical, poorly defined, velvety hyperpigmentation of the skin.
• Usually, intertriginous (folds and crease) areas of skin like underarms, groins, sides of the neck, folds under the breasts and ano-genetal regions are affected.
• The skin color of the affected area may range from light brown to black.
• Acanthosis nigricans can begin at any age.
• Papillomatosis (finger-like growths) and skin tags are observed in and around the affected skin.
• In acanthosis nigricans, there is hyperkeratosis and hyperplasia of stratum basale and stratum spinosum.

• There is visible diffused thickening of epidermal layer of skin.
• In children the benign hereditary AN or insulin resistant AN are often noticed.
• Occasionally mucocutaneous areas of the body may get affected.
• Diabetics are often affected by acanthosis nigricans.
• Individuals of African descent are also often affected.
• Generalized form covering a greater areas of the skin is seen in very rare cases.
• A skin biopsy of the affected skin usually shows hyperkeratosis, hyperplasia and papillomatosis.
• The affected skin may get infected and lesions may appear making the skin sensitive to touch.
  If the symptoms are observed on areas which are not normally affected like palms, soles, lips and mucous membranes, there is the possibility of hidden cancer.

Acanthosis nigricans causes

The causes of developing acanthosis nigricans disorder are many.
The foremost cause is obesity and related endocrine disorders.
Many diabetics have been found to face this problem.
Hypothyroidism, a disorder of thyroid glands, decreases the production thyroid hormone and is one of the causes.
Deficiency of adrenal gland produced hormones is known to cause AN.
Pituitary gland disorders also cause acanthosis nigricans.
The intake of hormonal pills, including oral contraceptives, is known to trigger the lesions.
Gastrointestinal, genital or urinary tract cancers may trigger the condition.

1.picture of acanthosis nigricans affected back
pictures by Vandana Mehta Rai
and C Balachandran

Types of acanthosis nigricans

The lesions may be benign or associated with malignancy. There are eight types of this disorder.
Obesity-associated type: The most common type induced by obesity and insulin resistance.
Syndromic: Persons suffering from Cushing's syndrome, polycystic ovary syndrome etc have been found to get affected by this disorder.
Acral type: Thick velvety idiopathic growth appears on the upper side of both hands and feet in otherwise healthy individuals. Persons of African descent are more prone to develop this condition.
Drug-induced: Several medicines containing nicotinic acid, insulin, systemic corticosteroids and hormones may induce the benign lesions.
Hereditary: In hereditary acanthosis nigricans, the lesions gradually appear and enlarge. Then they stabilize or regress on their own. As the cause is genetic there is no treatment for hereditary type except applying antibiotics for treatment of infections and applying exfoliating agents primarily to improve cosmetic appearance.
Malignant: This type is associated with the malignancy of gastrointestinal tract and urinogenital system. Lesions may be present in the mouth, tongue and lips. The lesions develop fairly fast when compared to benign types.
Mixed-type: Patients having one type may develop another type when multiple causative factors are present in the individual. For example a patient with drug-induced type may also develop obesity-associated type in case of obesity.
Generalized acanthosis nigricans has been in reported in rare pediatric cases (see pictures).

2.picture of acanthosis nigricans affected chest

Treatment of acanthosis nigricans

The first step in the cure of AN is immediate treatment of the underlying cause.
Reducing the sugars or starches in food to bring down the circulating insulin is the first line of treatment for improvement in the brown discoloration of skin.
Treatment for medicine induced disorder is immediate withdrawal of the culprit medicine.
Laser treatment or dermabrasion have been successfully used to reduce the skin thickening in some cases.
Cancer induced acanthosis nigricans may resolve once the tumor is successfully treated or removed.
Vitamin A oral treatment is helpful in reducing the severity of the condition.
Topical exfoliating agents and peels like alpha hydroxyacids, salicylic acid, retinoids, keratolytics and urea are effective as cosmetic treatment of skin thickening.

3.picture of acanthosis nigricans affected neck

Prevention

One very important step in preventing the possible occurrence of benign acanthosis nigricans is the management of weight.
In most of the cases obesity is the cause or at least the triggering factor.

4.picture of acanthosis nigricans in armpit

Reducing the sugars or starches to bring down the circulating insulin can stall the development of acanthosis nigricans.
Secondly, control and treatment of hormonal disorders is very important.

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1.picture source: http://en.wikipedia.org/wiki/File:Familial_acanthosis_nigricans2.jpg
picture authors: Vandana Mehta Rai MD DNB, C Balachandran MD | License: CC BY-SA 3.0
2.picture source: http://en.wikipedia.org/wiki/File:Familial_acanthosis_nigricans 5.jpg
picture authors: Vandana Mehta Rai MD DNB, C Balachandran MD | License: CC BY-SA 3.0
3.picture source: http://en.wikipedia.org/wiki/File:Familial_acanthosis_nigricans 3.jpg
picture authors: Vandana Mehta Rai MD DNB, C Balachandran MD | License: CC BY-SA 3.0
4.Picture source: http://en.wikipedia.org/wiki/File:Acanthosis-nigricans4.jpg
picture author: Madhero88 | license: CC BY-SA 3.0

References:
1.Vandana Mehta Rai MD DNB, C Balachandran MD. Generalized acanthosis nigricans in childhood. Dermatology Online Journal 12 (6): 14. (with pictures)

2.Habif TP. Cutaneous manifestations of internal disease. In: Habif TP, ed. Clinical Dermatology. 5th ed. Philadelphia, Pa: Mosby Elsevier;2009:chap 26.

Current topic in natural skin care:
Pictures of acanthosis nigricans and its causes and treatments.