A severe case of familial acanthosis nigricans, in this case from a genetic condition, courtesy Vandana Mehta Rai MD DNB, C Balachandran MD via Wikipedia
Acanthosis nigricans is a brown to black, poorly defined velvety hyperpigmentation of the skin. It is usually found in folds of the skin. It primarily is found in persons under the age of forty. It is often found in individuals with some sort of insulin disorder.
The causes of acanthosis nigricans are generally broken down into two types:
- Benign, caused by obesity, a genetic condition or a hormone disorder
- Malignant, usually associated with a tumor
If acanthosis nigricans is seen, a full medical history is necessary to determine if it can be ascribed to a benign cause. If no benign cause can be determined, it is good practice to do necessary imaging to attempt to find a tumor, often in the pancreas or the adrenal glands.