Acanthosis nigricans is a skin disorder that results in velvety, light-brown-to-black markings that occur in areas including the neck, armpits, groin, and under the breasts.
What Causes Acanthosis Nigricans?
Acanthosis nigricans can affect otherwise healthy people, or it can be associated with certain medical conditions. Sometimes acanthosis nigricans is congenital (something a person is born with). It also can occur as a result of obesity or an endocrine (glandular) disorder. It is frequently found in obese people with diabetes or a tendency towards diabetes and is most common among people of African descent. There are many other possible causes of acanthosis nigricans, including:
- Addison's disease, a condition caused by a deficiency of hormones from the adrenal gland
- Disorders of the pituitary gland within the brain
- Growth hormone therapy
- Hypothyroidism (low levels of thyroid hormone caused by decreased activity of the thyroid gland)
- Oral contraceptives
Most people with acanthosis nigricans have an insulin level that is higher than that of people of the same weight who don't have acanthosis nigricans. Eating too much of the wrong foods, especially starches and sugars, can raise insulin levels.
Rarely, people with certain types of cancer can also develop acanthosis nigricans.
How Is Acanthosis Nigricans Diagnosed?
The condition can be diagnosed by a doctor through a medical history and physical exam.
How Is Acanthosis Nigricans Treated?
Eating a special diet can help reduce circulating insulin and may lead to some improvement of the acanthosis nigricans.
Other treatments to improve skin appearance include Retin-A, 20% urea, alpha hydroxyacids, topical vitamin D, and salicylic acid prescriptions. These are only minimally effective, however.
Acanthosis nigricans caused by a drug may go away once the medication is stopped.
Can Acanthosis Nigricans Be Prevented?
When acanthosis nigricans is related to obesity, weight management is an important part of prevention. A diet that contributes to reduced insulin also can help prevent acanthosis nigricans.
Other preventive strategies include treating medical problems that are linked to acanthosis nigricans (such as hypothyroidism) and avoiding medications that tend to cause or worsen the condition (like birth control pills).
