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Article Source: Edited for content by Lahle Wolfe, from

Fast Click to Comprehensive
Diabetes Problems & Complaints

Acanthosis Nigricans (AN)
Alopecia Areata (AA)
Gum Disease
Skin Tags
Yeast Infections

Fast Click to
Newly Diagnosed

Diabetes Problems & Complaints
(less detail, easier reading)

Acanthosis Nigricans
Alopecia Areata (AA)
Gum Disease
Skin Tags
Yeast Infections

Information links to possible causes of AN

Hashimoto's Thyroiditis

Polycystic Ovarian Syndrome (PCOS)

Insulin Resistance


Type 2 Diabetes

Addison's Disease

Hemochromatosis (iron overload, or "bronze diabetes)

Physical Movement

Diabetes and Exercise

Benefits and Exercise Considerations for People With Diabetes

Why exercise?

What is aerobic activity?

The benefits of aerobic activity for diabetics
What is anaerobic activity?

The benefits of anaerobic activity for diabetics (strength training)

What is weight-bearing

The benefits of weight-bearing exercise for diabetics

Special exercise
considerations for
people with diabetes

Diabetes and Sports

Complementary Treatment

Complementary Approaches for Fitness & Stress Management
(i.e., yoga, medation, acupuncture)

Weight Loss

Commercial Weight Loss Programs - Before signing on the dotted line be sure to read this article about commercial weight loss centers and programs.  A calorie is a calorie is a calorie may be true (although, some would disagree), but weight loss centers are not all the same.

Want to know what we think about some commercial weight loss centers?

Jenny Craig
LA Weight Loss Centers
Weight Watchers

Diets Compared

Very Low Calorie Diets
Low Carbohydrate Lifestyle Plans
Ketogenic Plans
Non-Ketogenic Plans
Low Fat Lifestyle Plans
Low Glycemic Index Plans
Diabetes Meal Exchange
Vegetarian Diabetes Lifestyle

You may wish to begin by reading about the low glycemic index in "What is the Low Glycemic Index?"  before reviewing specific plans.

External links to information about AN and possible causes

Photo - neck
e-Medicine, "Acanthosis Nigricans" (derm/1)
MedlinePlus, "Acanthosis nigricans"
Addison Disease


Diabetes Medical Library                        back to main "Problems" page
Problems and Complaints Associated with Diabetes      

Acanthosis Nigricans
Symptoms, Causes, Treatment & Prevention

What is acanthosis nigricans?
Synonyms and related keywords
Medical conditions associated with benign AN
Malignant AN
Tests that may help determine the cause of AN
Other problems to be considered
Medical Treatment
Prognosis for persons with malignant AN


What is acanthosis nigricans?

Acanthosis nigricans (AN) is a brown to black, poorly defined, velvety hyperpigmentation of the skin, usually present in the posterior and lateral folds of the neck, the axilla, groin, umbilicus, and other areas.  It is often seen in persons with type 2 diabetes, insulin resistance, and polycystic ovarian syndrome (PCOS).  Following a healthy diet (to avoid insulin spikes) and keeping blood glucose levels in check may help improve the appearance of, or prevent AN from developing.

Synonyms and related keywords

AN, insulin resistance, insulin-resistant state, malignancy, malignant AN, malignant acanthosis nigricans, acrochordons, malignant acrochordons, hyperandrogenemia, HAIR-AN syndrome, dermatosis, Wilms tumor, darkening and thickening of the skin, obesity, leukonychia, hyperkeratosis, obesity-associated AN, syndromic AN, polycystic ovaries, hirsutism, clitoral hypertrophy, diabetes mellitus, ovarian hyperandrogenism, systemic lupus erythematosus, scleroderma, Sjögren syndrome, Hashimoto thyroiditis, acral AN, acral acanthotic anomaly, nevoid AN, genodermatosis, gastric adenocarcinoma, gastric neoplasm

AN can be both a benign condition (merely a visual evidence of another underlying medical problem) or a malignant condition.

Benign AN can be seen at birth, in children, and adults.  It is seen equally in men and women but is more common in persons with darker skin (African Americans and Hispanic persons have a higher rate of AN than do Caucasian persons) and the degree of affectation may parallel the severity of insulin resistance.

Malignant AN is most often seen in elderly persons and patient survival rate varies, with an average of approximately 2 years after diagnosis.

If you have signs of AN you should see your doctor to determine the cause.

Medical conditions associated with benign AN

The most common cause of benign AN is insulin resistance, usually from type 2 diabetes mellitus, or polycystic ovarian syndrome (PCOS).  AN can also be seen with Hashimoto's ThyroiditisAddison's disease, and hemochromatosis (iron overload, or "bronze" diabetes).  Sometimes, AN is a hereditary condtion.

There is also a form of AN that is malignant (cancerous).  Malignant AN is clinically indistinguishable from the benign forms; however, one must be more suspicious if the lesions arise rapidly, are more extensive, are symptomatic, or are in atypical locations.

Currently, 8 types of AN have been identified:

Acral AN (acral acanthotic anomaly) occurs in patients who are in otherwise good health.  Acral AN is most common in dark-skinned individuals, especially those of African American descent. The hyperkeratotic velvety lesions are most prominent over the dorsal aspects of the hands and feet.

Drug-induced AN, although uncommon, may be induced by several medications, including nicotinic acid, insulin, pituitary extract, systemic corticosteroids, and diethylstilbestrol.  And, rarely, triazinate, oral contraceptives, fusidic acid, and methyltestosterone also have been associated with AN. The lesions of drug-induced AN may regress following the discontinuation of the offending medication.

Familial AN is a rare genodermatosis that seems to be genetically transmitted.  The lesions typically begin during early childhood but may manifest at any age and the condition often progresses until puberty, at which time it stabilizes or regresses.

Malignant AN is associated with internal malignancy, is the most worrisome of the variants of AN because the underlying neoplasm is often an aggressive cancer. (See below for more detail.)

Mixed-type AN refers to those situations in which a patient with one of the above types of AN develops new lesions of a different etiology. An example of this would be an overweight patient with obesity-associated AN who subsequently develops malignant AN.

Obesity-associated AN, once labeled pseudo-AN, is the most common type of AN.  Lesions may appear at any age but are more common in adulthood. The dermatosis is weight dependent, and lesions may completely regress with weight reduction. Insulin resistance is often present in these patients; however, it is not universal.

Syndromic AN is the name given to AN that is associated with a syndrome. In addition to the widely recognized association of AN with insulin resistance, AN has been associated with numerous syndromes.  The type A syndrome and type B syndrome are special examples.

  • The type A syndrome also is termed the hyperandrogenemia, insulin resistance, and AN syndrome (HAIR-AN syndrome). This syndrome is often familial, affecting primarily young women (especially black women). It is associated with polycystic ovaries or signs of virilization (eg, hirsutism, clitoral hypertrophy). High plasma testosterone levels are common. The lesions of AN may arise during infancy and progress rapidly during puberty.
  • The type B syndrome generally occurs in women who have uncontrolled diabetes mellitus, ovarian hyperandrogenism, or an autoimmune disease such as systemic lupus erythematosus, scleroderma, Sjögren syndrome, or Hashimoto thyroiditis. Circulating antibodies to the insulin receptor may be present. In these patients, the lesions of AN are of varying severity.

Unilateral AN, sometimes referred to as nevoid AN, is believed to be inherited as an autosomal dominant trait.  Lesions are unilateral in distribution and may become evident during infancy, childhood, or adulthood.  Lesions tend to enlarge gradually before stabilizing or regressing.  

Malignant AN

This type of AN is associated with internal malignancy, is the most worrisome of the variants of AN because the underlying neoplasm is often an aggressive cancer.  AN has been reported with many kinds of cancer, but, by far, the most common underlying malignancy is an adenocarcinoma (cancer) of gastrointestinal origin, usually a gastric adenocarcinoma. In an early study of 191 patients with malignant AN, 92% had an underlying abdominal cancer, of which 69% were gastric. Another study reported 94 cases of malignant AN, of which 61% were secondary to a gastric neoplasm.

In 25-50% of cases of malignant AN, the mouth is involved. The tongue and the lips most commonly are affected with elongation of the filiform papillae on the dorsal and lateral surfaces of the tongue and multiple papillary lesions appearing on the commissures of the lips. Oral lesions of AN seldom are pigmented.

Regression of AN has been seen with treatment of the underlying malignancy, and reappearance may suggest recurrence or metastasis of the primary tumor.


Tests that may help determine the cause of AN

Your doctor may perform some of the following tests to determine the cause of AN:

  • For patients with adult onset of AN, perform a basic workup for underlying malignancy.
  • Screen for diabetes with a glycosylated hemoglobin level or glucose tolerance test.
  • Screen for insulin resistance; a good screening test for insulin resistance is a plasma insulin level, which will be high in those with insulin resistance. This is the most sensitive test to detect a metabolic abnormality of this kind because many younger patients do not yet have overt diabetes mellitus and an abnormal glycosylated hemoglobin level, but they do have a high plasma insulin level.  

Other problems to be considered

  • Becker nevus
  • Confluent and reticulated papillomatosis of Gougerot and Carteaud syndrome
  • Dowling-Degos disease
  • Hypertrophic seborrheic keratosis
  • Ichthyosis hystrix
  • Linear epidermal nevus
  • Parapsoriasis en plaque
  • Pemphigus vegetans  

Medical Treatment

  • The goal of therapy is to correct the underlying disease process. Treatment of the lesions of AN is for cosmetic reasons only. Correction of hyperinsulinemia often reduces the burden of hyperkeratotic lesions. Likewise, weight reduction in obesity-associated AN may result in resolution of the dermatosis.
  • No treatment of choice exists for AN. Topical medications that have been effective in some cases include keratolytics (eg, topical tretinoin). Oral agents that have shown some benefit include etretinate, isotretinoin, metformin, and dietary fish oils. Cyproheptadine has been used in cases of malignant AN because it may inhibit the release of tumor products. Dermabrasion and long-pulsed alexandrite laser therapy may also be used to reduce the bulk of the lesion.



Complications vary depending on the cause of AN.  Appearance of AN during childhood usually is associated with a benign condition, and there is usually little cause for medical concern.  Adult onset AN is more worrisome, and both diabetes or an underlying malignancy should be ruled out. However, most cases of adult onset AN are benign and often are associated with insulin resistance or type 2 diabetes.

Prognosis for Persons with Malignant AN

The prognosis for patients with malignant AN is often poor. The associated malignancy frequently is advanced, and the average survival of these patients is approximately 2 years.


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Page Updated 03/23/2006