Acanthosis nigricans (AN) is a localized skin disorder typically characterized by symmetric hyperpigmented velvety plaques in skin folds. It is due to overstimulation of fibroblasts and keratinocytes via insulin-like growth factor receptors and tyrosine kinase receptors. AN is most commonly associated with obesity and is a marker of insulin resistance. A 2007 study found that up to 90% of youth with AN also carried a diagnosis of diabetes mellitus.
AN is classified into 8 types:
I. Obesity-associated – Most common; linked to diabetes, insulin resistance, high body mass index (BMI), metabolic syndrome, etc.
III. Drug-induced – Niacin (nicotinic acid) is the most closely associated medication, but AN can also be caused by oral contraceptives, corticosteroids, diethylstilbestrol, heroin, fusidic acid, methyltestosterone, protease inhibitors, and folate.
IV. Syndromic – Related to a specific syndrome, eg, HAIR-AN (hyperandrogenism, insulin resistance, and acanthosis nigricans) syndrome, polycystic ovarian syndrome, or autoimmune-disease, among others.
V. Acral – Affects elbows, knees, and knuckles. Typically seen in healthy sub-Saharan African patients.
VI. Unilateral – Also called nevoid. Usually represents an epidermal nevus in childhood.
VII. Benign – Rare autosomal dominant form developing at birth or during childhood. Typically stabilizes or regresses during puberty.
VIII. Mixed – Any 2 or more of the above types combined.
Below is a list of drugs with literature evidence indicating an adverse association with this diagnosis. The list is continually updated through ongoing research and new medication approvals. Click on Citations to sort by number of citations or click on Medication to sort the medications alphabetically.
Acanthosis nigricans is a condition of abnormal thickening and darkening of the skin, especially in body creases. It most commonly occurs in obese people, though it can occasionally be found in people who have more serious health problems or are taking certain medications. Treatment of the medical condition usually cures the skin lesions.
Who’s At Risk
Acanthosis nigricans can affect individuals of any age and of any ethnic background. It can develop in children and in teenagers, though it is more common in adults. Acanthosis nigricans is also more common in people with darker skin. Males and females are affected equally.
Acanthosis nigricans commonly develops in:
Overweight or obese people
People with diabetes or other glandular (endocrine) problems
People taking certain medications (for example, oral contraceptives, niacinamide, or corticosteroids)
People who have had kidney transplants
Signs & Symptoms
The most common locations for acanthosis nigricans include:
Sides and back of the neck
Armpits
Groin
Less commonly, acanthosis nigricans can affect the:
Face
Inner thighs
Elbows
Knees
Belly button (navel)
Rarely, acanthosis nigricans can occur in the:
Nipples
Eyelids
Lips
Inside of the mouth
Anus
The lesions of acanthosis nigricans appear as "velvety" thickenings of the outer skin, and they can range in color from gray to brown to black. Darker-skinned people tend to have darker lesions.
Self-Care Guidelines
Because most people who develop acanthosis nigricans are overweight, their skin lesions can improve dramatically and even go away when they lose weight. Other medical conditions that cause these lesions should be treated as well.
Other treatments are:
Lose weight, changing diet and exercise habits
Apply over-the-counter preparations containing alpha-hydroxy acids such as glycolic acid or lactic acid
Apply over-the-counter lotions containing the beta-hydroxy acid salicylic acid
Apply over-the-counter creams containing urea
Apply over-the-counter cortisone cream (if the areas are itchy)
When to Seek Medical Care
See your child's primary doctor if the child develops thickening and darkening of the skin folds. If the acanthosis nigricans is due to obesity, the doctor can help you find healthy ways for your child to lose weight.
See the doctor immediately if your child suddenly develops widespread acanthosis nigricans (affecting the skin folds as well as the palms of the hands, the lips, and other areas). The doctor may be able to diagnose and treat a more serious medical condition that is causing the acanthosis nigricans.
Treatments
The doctor will try to establish the cause of the acanthosis nigricans. If it is due to obesity, then the doctor can help you find ways for your child to lose weight. If obesity is not a factor, the doctor may order blood tests, X-rays, or other types of tests to find the cause.
Once the medical condition has been diagnosed and treatment has been started, the doctor may recommend a topical cream or lotion containing:
Patient Information for Acanthosis nigricans in Child