Acanthosis Nigricans

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 posterior and lateral folds of the neck, the axilla, groin, umbilicus, forehead, and other areas.


·         The most common cause of acanthosis nigricans is insulin resistance, which leads to increased circulating insulin levels. Insulin spillover into the skin results in its abnormal increase in growth.

·         Condition most commonly associated with insulin resistance is type 2 diabetes mellitus, obesity and polycystic ovary syndrome.

·         May also be seen with certain medications that lead to elevated insulin levels

1.      Glucocorticoids

2.      Niacin

3.      Insulin

4.      Oral contraceptives

5.      Protease inhibitors


Signs and Test:

·         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.

1.      Blood test

2.      Endoscopy

3.      X- rays