Acanthosis nigricans is a skin problem presenting areas of dark, abnormally increased coloration that appears in the armpits, neck or the groin areas. These patches could develop gradually without any other symptoms. It most commonly is identified among individuals of African descent and can be inherited. The different types of acanthosis nigricans are;

  • Obesity-associated acanthosis nigricans: This is the most common type that can occur at any age but generally common in adulthood and is associated with insulin resistance
  • Syndromic acanthosis nigricans: This is associated with a syndrome such as polycystic ovary syndrome, cushing syndrome and crouzon syndrome
  • Benign acanthosis nigricans: Also referred to as acral acanthotic anomaly, it presents velvety lesions over the surface of hands and feet and is most common among dark-skinned people
  • Drug-induced acanthosis nigricans: Although uncommon, it is induced with the use of certain medications such as insulin, hormone treatments and nicotinic acid
  • Hereditary benign acanthosis nigricans: This is inherited from the parents in an autosomal dominant trait and can develop at any age
  • Malignant acanthosis nigricans: This is the internal malignancy and the most common cancer associated with it is the stomach cancer and less commonly, the intestines, breast, bladder, uterus, lung or prostate.

Features of acanthosis nigricans

This is characterized by the hyperpigmentation and abnormal thickening of the skin which in rare cases could also affect almost all of the skin. In the initial stage, black pigmentation, roughness and dryness along with thickening or overgrowth of the skin can occur. The affected areas can be covered with warty tissue growths that appear as velvety texture. With the thickening of the skin, the surface can appear unusually wrinkled and wart-like outgrowths can develop. In the case of malignant acanthosis nigricans, the skin changes appear more severe and the pigmentary changes are more pronounced than the benign acanthosis nigricans.


Acanthosis nigricans is detected through a medical history and with a skin examination. Based on the cases, blood work may be required to investigate the underlying cause of the condition and occasionally, a skin biopsy may be required if the diagnosis with a physical examination is inconclusive. However, it is important to distinguish if it is malignant or benign as the tumors of the malignant cases tend to spread quickly and death often occurs soon after. Therefore, it is essential to identify the hidden tumor and to conduct a thorough workup and if the tumor can be successfully treated, the condition could resolve.

Treatment options

The primary goal of the treatment is to identify the underlying cause which can resolve the condition. However, there is no specific treatment for acanthosis nigricans itself. Based on the cause, the recommendation can include;

  • Losing weight if the condition is caused by obesity
  • Stopping the medications and supplements responsible for triggering it
  • Having a surgery to remove the cancerous tumor
  • Medication to balance insulin levels
  • Medication to balance the hormones
  • Treatments such as topical retinoids, laser therapy and dermabrasion can be used to improve cosmetic appearance