Acanthosis nigricans
| Acanthosis nigricans | |
|---|---|
 |
|
| Acanthosis nigricans on axilla | |
| Classification and external resources | |
| Specialty | Dermatology |
| ICD-10 | L83 |
| ICD-9-CM | 701.2 |
| OMIM | 100600 |
| DiseasesDB | 58 |
| MedlinePlus | 000852 |
| eMedicine | derm/1 |
| MeSH | D000052 |
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 armpits, groin, navel, forehead, and other areas.
Acanthosis nigricans is conventionally divided into benign and malignant forms, although may be divided into syndromes according to cause:
An alternate classification system still used to describe acanthosis nigricans was proposed in 1994. It delineates acanthosis nigricans syndromes according to their associated syndromes, including benign and malignant forms, forms associated with obesity and drugs, acral acanthosis nigricans, unilateral acanthosis nigricans, and mixed and syndromic forms.
Acanthosis nigricans may present with thickened, velvety, relatively darker areas of skin on the neck, armpit and in skin folds.
It typically occurs in individuals younger than age 40, may be genetically inherited, and is associated with obesity or endocrinopathies, such as hypothyroidism, acromegaly, polycystic ovary disease, insulin-resistant diabetes, or Cushing's disease.
Familial acanthosis may arise as a result of an autosomal dominant trait, presenting at birth or developing during childhood.
Endocrine syndromes associated with acanthosis nigricans can develop in many conditions, particularly:
Acanthosis nigricans associated with endocrine dysfunction is more insidious in its onset, is less widespread, and the patients are often concurrently obese.
In young persons, AN is a visible marker which strongly suggests insulin resistance. Higher than normal insulin levels in the blood stream cause the growth of darkened skin over certain areas of the body. No skin treatment will get rid of AN. Acanthosis nigricans may lighten up and possibly go away by treating the root cause, insulin resistance, but it can take months or years to do so. Insulin resistance syndromes may be divided into type A (HAIR-AN) and type B syndromes. The majority of cases of acanthosis nigricans are associated with obesity and otherwise idiopathic. This is likely because of insulin resistance, and more likely to occur in darker-skinned persons. This can also be referred to as pseudoacanthosis nigricans.
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