Acanthosis Nigricans

Acanthosis Nigricans

acanthosis nigricans
acanthosis nigricans

What is Acanthosis Nigricans?

Acanthosis nigricans is a skin condition that usually affects the skin folds of the neck, the armpit, and the groin. They are characterized by dark velvety skin discoloration, which can become thickened and usually smell bad.

Acanthosis nigricans is common in people who are obese and those who have diabetes. Also, this skin condition may indicate any malignancies occurring in the internal organs such as stomach or liver cancer. Based on studies, acanthosis nigricans is common in people of African descent.

Acanthosis Nigricans Symptoms

The most common symptom of acanthosis nigricans is the presence of the skin discoloration which is dark and velvety. The discoloration is characterized by symmetrical hyperpigmentation commonly found in the armpits, groins, and the posterior neck.

Aside from the hyperpigmentation, skin tags can also be found in and around the affected areas. Occasionally, lesions brought about by this skin condition may also occur in the mucous membranes of the oral cavity, nasal and laryngeal mucosa, the esophagus, the areola of the nipple, the eyelids and the conjunctiva, etc.


The exact cause of acanthosis nigricans has not been determined yet; however, there are several possibilities that health care professionals believed to have contributed to the development of the condition.

Obesity-related Acanthosis Nigricans

This is once known as pseudo acanthosis nigricans and is the most common type among the nine types of acanthosis nigricans. Its characteristic lesions may appear at any age, but usually it has more effects on the person during adulthood. Obesity-related acanthosis nigricans is also closely associated with resistance to insulin but not general.

Syndromic Acanthosis Nigricans

This type of acanthosis nigricans is associated with a syndrome, specifically the type A and the type B syndromes. The type A syndrome is referred to hyperandrogenemia, insulin resistance, and the syndromic acanthosis nigricans. Type A usually affects young women who have polycystic ovaries or signs of virility. In these patients, there is high level of plasma testosterone, thereby leading to hyperandrogenemia.

Type B syndromes on the other hand is associated with women who have diabetes mellitus, ovarian hyperandrogenism, or autoimmune disorders such as systemic lupus erythematosus, scleroderma, Hashimoto’s thyroiditis, etc.

Acral Acanthosis Nigricans

This type of acanthosis nigricans usually affects the people with otherwise good health. The skin hyperpigmentation are still commonly seen in dark-skinned individuals such as those who have African descent. The discoloration, however, are present in the dorsal portion of the hands and feet, including the knuckles.

Unilateral Acanthosis Nigricans

Otherwise known as nevoid acanthosis nigricans, this type is believed to follow an autosomal dominant trait. They are called unilateral because the lesions are found in unilateral distribution and may become apparent during infancy, childhood, or adulthood.

Generalized Acanthosis Nigricans

This type of acanthosis nigricans is rare and is only found in pediatric patients without an underlying pathology.

Familial Acanthosis Nigricans

This type is rare and can be transmitted through autosomal dominant pattern. The lesion may start developing at an early age but may become more noticeable at any age. They continue growing until puberty at which they reach maturity and are more stabilized.

Drug-Induced Acanthosis Nigricans

This is again an uncommon type of acanthosis nigricans but may be induced by several medications, including diethylstilbestrol, nicotinic acid, insulin, systemic corticosteroids and pituitary extract.

Malignant Acanthosis Nigricans

This type is associated with malignancies of the internal organs such as the liver and the stomach or adenocarcinoma of the gastrointestinal area. This is considered to be the most worrisome of all the types of acanthosis nigricans. In children, malignant acanthosis nigricans is associated with gastric adenocarcinoma, Wilm’s tumor, and osteogenic sarcoma. Although the symptoms of malignant acanthosis nigricans can be similar to the symptoms of other types of acanthosis nigricans, it can still be distinguishable because in malignant type, the lesions appear rapidly, more extensive, symptomatic, and are seen in unusual locations.

Mixed type Acanthosis Nigricans

Mixed type classifies the type of the condition when the patient experiences a combination of the abovementioned classifications. An example would be an obese patient with obesity-related acanthosis nigricans and develops malignant acanthosis at the same time.


Because the exact cause of acanthosis nigricans is not well determined, for the patient to be given the best treatment possible, it is better to conduct a thorough examination on the patient to determine the type of acanthosis has occurred as well as the underlying cause associated with the condition. The common tests to be done is screening for glycosylated hemoglobin level or glucose tolerance test for diabetes. In addition, screening for insulin resistance can also be done, and skin biopsy is recommended to examine the affected tissues.

Cosmetic reasons are the main goal of treatment for acanthosis nigricans. Correcting hyperinsulinemia is aimed to reduce the occurrence of hyperkeratotic lesions. Also, weight reduction for obese patients is also part of the management.

Pharmacotherapy to improve cosmesis includes the following:

Topical retinoids

This promotes shedding of hyperkeratotic skin because they modify keratinocyte adhesion, differentiation, and proliferation. Retinoids promotes detachment of the hard and cornified cells and thus enhance the shedding of unwanted cells.

Keratolytic agents

The use of ammonium lactate provides hemuctant effect when applied to the skin as they tend to hydrate the corneal layer of the skin thus decreasing the corneocyte cell cohesion.

Complications of acanthosis nigricans may occur; however, it depends on the underlying cause. Early-onset acanthosis nigricans are considered to be benign in nature, but adult-onset acanthosis nigricans are more serious, especially those cases that are associated with certain malignancies of the gastrointestinal system. Make it a point to educate the patient that prognosis for patients with acanthosis nigricans with malignancies is often poor. Furthermore, patients should be informed that acanthosis nigricans is not a skin disease per se, but it is a sign of an underlying pathology. One important example of this is the insulin resistance-associated acanthosis nigricans, which is a sign that the lesions seen outside are just an indication that the patient may be suffering from diabetes.

Acanthosis Nigricans Pictures

Collection of photos, images and Pictures of Acanthosis Nigricans…

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