Acanthosis Nigricans: Indicating A Hidden Cause

Skin problems often are synonymous with diabetes. If not an accompaniment they definitely follow as a complication of diabetes. Acanthosis nigricans is a condition that may result due to hormonal imbalance or as a counter effect of insulin resistance. It is characterized by light-brown-to-black, velvety, rough areas or increased skin markings usually on the back and sides of the neck, under arms and in the groin.

AN in the benign form may be present at any age, including at birth, though it is more common in the adult population. Malignant AN is frequently associated with elderly persons; though it is not uncommon for children to present with the condition. It is more or less found to be common in people who are obese and those who are suffering from an inherent condition like cancer and is common in either sex.

Benign and Malignant

AN is broadly divided into two parts depending on its severity.

Benign AN: The condition does not create too many complications for the patient. People who experience this condition are usually resistant to insulin-which is the main reason why the condition surfaces. The severity of the condition depends on how resistant the patient is to insulin.

Malignant AN: This condition is marked by significant complications. This is because of the presence of the presence of a malignant tumor. The survival time for such patients is usually 2-3 years, which may extend to 6-7 years. In older patients with new onset AN, most have an associated internal malignancy.

Causes

A definite cause for the eruption of the condition cannot be ascertained. They are several possibilities that have been suggested though. The definitive cause for AN has not yet been ascertained, although several possibilities have been suggested.

• The condition is often associated with obesity. It is the most common type of AN and is termed pseudoacanthosis nigricans. Usually the symptoms subside on weight reduction.
• Insulin resistance goes hand in hand with the condition and is often present in these patients. But this is not the case always.
• AN has also been believed to be a result of various syndromes. The type A syndrome and type B syndrome are special examples.
  1. Type A Syndrome: Also termed as hyperandrogenemia, insulin resistance, and acanthosis nigricans syndrome (HAIR-AN syndrome), it is inherited and generally affects young women. It is often characterized with polycystic ovaries or signs of virilization. High plasma testosterone levels mark the condition. The symptoms may present during infancy and speed up during puberty.
  2. Type B Syndrome: Is common in women with uncontrolled diabetes mellitus, ovarian hyperandrogenism, or an autoimmune disease such as systemic lupus erythematosus, scleroderma, Sjögren syndrome, or Hashimoto thyroiditis. The skin lesions in these patients are of varying severity.
• Dark skinned people, though in good health seem to be affected by Acral AN. It is likely to be present in most of the people who have a African American descent.
• Family traits may also be one of the reasons why patients present with the condition.
• Several medicines like nicotinic acid, insulin, systemic corticosteriods, oral contraceptices, etc. are supposed to induce the condition. This is quite rare though.
• It may present in the malignant form due to the presence of an underlying tumor or carcinoma. AN has been reported with many kinds of cancer
• Many times the oral cavity may be affected by the condition.

Signs and symptoms

Acanthosis nigricans causes skin lesions that feel velvety and are darker than the surrounding skin. The lesions often form in the folds along the neck, armpits, groin, knuckles, between the legs, at the elbow, under the breasts, and around the belly button.

• The lesions form in the folds of the skin-along the neck, groin, armpits, knuckles, elbows etc. The posterior part of the neck is generally affected in children while it is the vulva in women who are overweight and have low levels of androgen.
• They may sometimes be present in the mucus membranes like the oral cavity.
• The areola of the nipple also may be affected.
• It also affects the nails in the form of leukonychia and hyperkeratosis.

Diagnosis

Once the condition is suspected a basic check up to analyze the malignancy of the condition or any inherent disease. The person is tested for the presence of diabetes and insulin resistance.

Effects

• The person may suffer from chafing of the skin.
• The appearance of these spots may not appeal cosmetically.
• They do not become cancerous but may grow in proportion.
• It is not contagious, therefore does not pose a risk to others.

Treatment

The main aim of treatment lies in terminating the underlying disease process. Treatment of the lesions of AN is for cosmetic reasons only. Correcting hyperinsulinemia may also help control the condition. If the condition is caused due to an external cause like the side effect of a medication, it will go away once the medicine is stopped. But if is caused by a cancer, there is nothing much that can be done. When AN is caused by obesity, weight management is key. Topical applications do make a difference, so do oral agents.

• Usually topical retinoids -- agents that promote shedding of hyperkeratotic skin, are used.
• Tretinoin (Avita, Retin-A) – helps promote the shedding of corneocytes and detachment of cornified cells.

Though the treatment procedure helps in controlling the condition, it comes with certain side effects like stretch marks and thinning of the skin and birth defects in pregnant women who use retinoids.

AN may not be life threatening but it sure indicates an underlying condition that may prove fatal if ignored. Therefore it is necessary for the examiner to make a proper diagnosis so that the patient can be treated accordingly and any new or worsening symptoms can be controlled before they assume a malignant form.