Acanthosis Nigricans

Definition

Definition of 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.

Symptoms

Symptoms of Acanthosis Nigricans
Acanthosis nigricans usually appears slowly and doesn't cause any symptoms other than skin changes. Eventually, dark, velvety skin with very visible markings and creases appears in the armpits, groin and neck folds, and over the joints of the fingers and toes. Less commonly, the lips, palms, soles of the feet, or other areas may be affected. These symptoms are more common in people with cancer.

Causes

Causes of Acanthosis Nigricans
Acanthosis nigricans can affect otherwise healthy people, or it can be related to medical problems. Some cases are genetically inherited. The condition is most commonly seen among people of African descent, in part because it is easier to see in darker skin.

Signs/Tests

Signs/Tests of Acanthosis Nigricans
Physicians can usually diagnose acanthosis nigricans by simply looking at a patient's skin. A skin biopsy may be needed in unusual cases. If no clear cause of acanthosis nigricans is obvious, it may be necessary to search for one. Blood tests, an endoscopy, or x-rays may be required to eliminate the possibility of diabetes or cancer as the cause. Additionally acanthosis nigricans has similar visual characteristics (neck discoloration) with Casal collar, which is a symptom of pellegra (a nutrient deficiency disease, easily remedied with supplementation). In early stages of discoloration, it is hard for a non trained eye to distinguish one from the other.

Prognosis

Prognosis of Acanthosis Nigricans
Acanthosis nigricans often fades if the underlying cause can be determined and treated appropriately.

Treatment

Treatment of Acanthosis Nigricans
People with acanthosis nigricans should be screened for diabetes and, although rare, cancer. Controlling blood glucose levels through exercise and diet often improves symptoms. Acanthosis nigricans maligna may resolve if the causative tumor is successfully removed.