Altering Acanthosis Nigricans

You have a velvety ring of discoloration on the back of your neck. No matter how many times you wash that area, it is still there. You could have acanthosis nigricans.

Acanthosis nigricans (AN) is skin disorder that has dark brown velvety plaques usually found on the skin of the underarms, neck, and knuckles, but can occur on the insides of the thighs and tops of fingers and hands as well. The discoloration is the result of thickened skin and not an boost in pigment, as is commonly thought by patients. It does not usually have any symptoms or signs, but can occasionally get itchy.

The darkened skin is not associated with a difference or rise in melanocytes (cells that produce melanin, or skin pigmentation) but is due to thickening of the skin layers. As the levels of insulin in the body increase, insulin binds to these receptors on the skin and causes the cells to replicate and thicken. This results in the thickened, velvety skin seen in AN.

AN is associated with many syndromes and diseases, both benign (harmless) and malignant. Insulin resistance and diabetes mellitus are the most general associations with AN. Other relationships have been shown with malignancy, while even more cases of AN without any known underlying disease, except perhaps, obesity. As the frequency of obesity in adults and children today continues to rise, AN becomes an even more important discovery to alert physicians of possible pathology and halt disease processes at earlier stages, thus decreasing ill health and death.

There is a genetical type of AN found in young children. There is a type that affects adults with insulin resistance/obesity. The last kind which is uncommon, typically affects an older population, and is associated with malignancy. AN can affect males and females, but the type that affects adults tends to be more common in women. Regarding race, AN tends to have a higher prevalence among blacks than whites. Native Americans also have been shown to have an increased risk of AN, which correlates with their increased risk of diabetes.

There are up to eight types of AN, but there are only four main types. They are classified as malignancy associated (cancer associated), hereditary, endocrinopathy associated (problems with the endocrine system), and drug-induced. Most cases are idiopathic, which means they have no known cause.

·       Type I is rare and is associated with internal malignancy, most often adenocarcinoma.

·       Type II AN can be seen at birth or in early childhood. The clinical features tend to worsen during puberty. It is not associated with any increase in cancer risk.

·       Type III AN is associated with endocrinopathies. Obesity is highly connected, as is insulin resistance and diabetes mellitus. Most cases of AN with a diagnosable underlying condition are related to Type III AN. The affected patient may be obese, but a specific disease can not always be identified. Prevalence and severity of insulin resistance is known to be different in different racial groups. Location and severity of AN may relate to rigidity of insulin resistance. Studies are underway to develop an instrument that scores AN based on all locations, severity and ethnicities, which will be an optimal tool for grading AN.

·       Type IV AN is uncommon and is caused by medication. Associated medicines are: nicotinic acid, diethylstillbestrol, niacinamide, oral contraceptive pills and glucocorticoids (oral or intravenous steroids).

Development of both diabetes and/or AN has important health implications. Through further research, it is important to establish the relationship between AN and the future threat of developing heart disease/diabetes, which can lead to premature morbidity and mortality.

If there is an underlying disease causing AN, treatment of this disease is required. For those who have insulin sensitivity and/or obesity, weight management is the goal. Other options for treatment include topical salicyclic creams or lotions available by prescription, ammonium lactate creams or lotions available over-the-counter, or urea-based creams or lotions also available by prescription.

If you think you have AN, it is important to see a physician to consider what type of AN you have. Most physicians are familiar with the diagnosis of AN, but dermatologists are the specialists who see and remedy all forms of the disorder most frequently. Checking with your primary physician and working with a dermatologist may be the best method. Often a mix of topical treatments and weight management are mandatory, which will require the involvement and dedication of the patient.