Acanthosis nigricans causes dark, thickened patches on the skin in areas including the neck, armpits, groins and under the breasts.
Acanthosis nigricans is usually a sign of another medical condition, such as diabetes, rather than being a condition in its own right.
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 can also occur as a result of obesity or an endocrine (glandular) disorder. It is frequently found in people with 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).
- Certain medicines, including oral contraceptives, nicotinic acid, insulin, systemic corticosteroids and hormone treatments
Most people with acanthosis nigricans have an insulin level that is higher than that of people of the same weight who don't have the condition. Eating too much of the wrong foods, especially starches and sugars, can raise insulin levels.
People with certain types of cancer can also develop severe cases of acanthosis nigricans.
How is acanthosis nigricans diagnosed?
The condition can be diagnosed by a doctor through a medical history and physical examination.
How is acanthosis nigricans treated?
Eating a special diet can help reduce circulating insulin and can lead to a rapid improvement of the skin problem.
Other treatments to improve skin appearance include tretinoin, 20% urea, alpha hydroxyacids and salicylic acid prescriptions. These are only minimally effective.
Acanthosis nigricans caused by medication 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 oral contraceptives).