Describes symmetrical, brown, velvety plaques that are often found on the neck, axilla and groin.
Acanthosis nigricans. e Image used on license from DermNet NZ and with the kind permission of Prof Raimo Suhonen
Acanthosis nigricans shown in the axilla of an overweight man
Acanthosis nigricans can occur in isolation (generally in dark skin types) but is usually an indicator of insulin resistance and related conditions (type 2 diabetes, polycystic ovarian syndrome, Cushing's syndrome, hypothyroidism). It can also be caused by medications including corticosteroids, insulin and hormone medications. If acanthosis nigricans develops rapidly and in atypical locations such as in the oral cavity, internal malignancy should be suspected, particularly gastric cancer.
Causes