Acanthosis nigricans is a skin condition characterized by areas of dark, velvety discoloration in body folds and creases. The affected skin can become thickened. Most often, acanthosis nigricans affects your armpits, groin and neck.
The skin changes of acanthosis nigricans (ak-an-THOE-sis NIE-grih-kuns) typically occur in people who are obese or have diabetes. Children who develop the condition are at higher risk of developing type 2 diabetes. Rarely, acanthosis nigricans can be a warning sign of a cancerous tumor in an internal organ, such as the stomach or liver.
No specific treatment is available for acanthosis nigricans. Treatment of underlying conditions may restore some of the normal color and texture to affected areas of skin.
Here are some ways to help.
Brown Spots: Causes & Solutions!
Skin pigmentation problems occur because the body produces either too much or too little melanin. Melanin is the pigment in skin produced by specific cells (melanocytes). It is triggered by an enzyme called tyrosinase, which creates the color of our skin, eyes, and hair. This faulty melanin production is primarily caused by chronic unprotected sun exposure or hormones (particularly during pregnancy or from taking birth control pills).
As far as skin is concerned, depending on how much is present, melanin does provide some amount of sun protection by absorbing the sun's ultraviolet light. This explains why darker skin colors are less susceptible to sunburn and the overall effects of sun damage. But less susceptible doesn't mean immune from problems.
What to Do? Start with Sunscreen!
Store shelves are lined with products claiming to lighten skin. But without question, the first line of defense is smart sun behavior (meaning avoidance or, at the very least, careful exposure) along with the daily use (365 days a year) and liberal application (and, when needed, reapplication) of a well-formulated sunscreen. Diligent use of a sunscreen alone allows some repair as well as protection from further sun damage, which is what created the problem in the first place.
No other aspect of controlling or reducing skin discolorations is as important as being careful about exposing your skin to the sun and the use of sunscreen, SPF 25 or greater (and greater is usually better), with the UVA-protecting ingredients of titanium dioxide, zinc oxide, avobenzone, Mexoryl SX, or Tinosorb. Using effective skin-lightening products, exfoliants, peels or laser treatments without also using a sunscreen will prove to be a waste of time and money. Sun exposure is one of the primary causes of the skin discoloration disorder melasma, and other treatments can't keep up with the sun's daily assault on the skin. Before you look at any other option for brown or ashen skin discolorations, start with applying sunscreen and reducing sun exposure.
It Takes a Village
While sunscreen and avoiding direct sun exposure is essential, inhibiting increased melanin production stimulated by long term sun damage is equally important. There are many options to consider when searching for a solution. The most successful treatments use a combination of topical lotions or gels containing melanin-inhibiting ingredients along with a well-formulated sunscreen, and a prescription retinoid (such as Renova or generic versions containing tretinoin, a type of retinoid). Depending on how the skin responds to these treatments, exfoliants—either in the form of topical skin-care products or chemical peels done by a physician or lasers or intense pulsed light treatments can definitely enhance results.
Topical Treatments
Topical hydroquinone is a key step in reducing or eliminating skin discolorations. In fact, topical application of hydroquinone is considered by many dermatologists and extensive research to be a safe and effective treatment for skin discolorations. Topical hydroquinone in 2% concentrations from cosmetic companies and 4% concentrations available from a physician or by prescription should definitely be a consideration.
Some research has shown topical azelaic acid in 15% to 20% concentrations to be as efficacious as hydroquinone with a decreased risk of irritation. Tretinoin by itself has also been shown to be especially useful in treating hyperpigmentation of sun-damaged skin. Kojic acid, alone or in combination with glycolic acid or hydroquinone, also has shown good results due to its inhibitory action on tyrosinase (though kojic acid has had its share of problems in terms of stability and potential negative effects on the skin and is rarely being used nowadays). Several plant extracts and vitamin C also have some research showing them to be effective for inhibiting melanin production, but hydroquinone has the most impressive amount of research overall.
Alpha Hydroxy Acids
Alpha hydroxy acids (AHAs)—primarily in the form of lactic acid and glycolic acid—are the most researched forms of AHAs because they have a molecular size that allows effective penetration into the top layers of skin. It is generally assumed that in and of themselves AHAs in concentrations of 4% to 15% are not effective for inhibiting melanin production and won't lighten skin discolorations in that manner. Rather, it is believed that their benefit is in helping cell turnover rates and removing unhealthy or abnormal layers of superficial skin cells (exfoliation) where hyperpigmented cells can accumulate. However, other research has shown that lactic and glycolic acids can indeed inhibit melanin production separate from their actions as an exfoliant on skin.
Either way, there is a good amount of evidence that in combination with other treatments—such as hydroquinone, tretinoin, and, of course, an effective sunscreen—AHAs can be very effective for improving the overall appearance of sun-damaged skin and possibly helping other ingredients penetrate skin better. While there is no comparative research in regards to salicylic acid (BHA) and its effect on melasma, it makes sense to assume that because salicylic acid exerts a similar action on skin as AHAs, it will have similar results for improving skin color.
Laser Treatments
Both ablative and nonablative lasers and light treatments administered by a dermatologist can have a profound improvement on melasma. However, the results are not always consistent, and problems can occur (such as hypo- or hyperpigmentation). Moreover, laser treatments of this kind often are a problem for those with darker skin tones. Nonetheless, when laser treatments work they can have a marked difference in the skin's appearance, especially when used in combination with the other topical treatments previously mentioned. The results can be startling, and though expensive, for stubborn discolorations, lasers are absolutely worth a try. There are many types of lasers that can be successful for this purpose. Which one is optimal for you is best determined by a skilled dermatologist who has a practice that incorporates a variety of different lasers and/or light-emitting devices.
Sources for the information above: Journal of the American Academy of Dermatology, May 2006, supplemental, pages S262-S281; and May 2005, pages 786-792; Dermatologic Therapy, June 2004, pages 196–205; and January 2001, page 46; Journal of Cosmetic and Laser Therapy, March 2005, pages 39-43;Journal of Cutaneous Medicine and Surgery, April 2004, pages 97-102; Journal of Drugs in Dermatology, November-December 2005, pages 770-774; and September-October 2004, supplemental, 27-34; Dermatologic Surgery, March 2006, pages 365-371; October 2005, page 1263; and February 2005, pages 149-154; Lasers in Surgery and Medicine, April 2000, pages 376-379; Cutis, February 2004, supplemental, pages 18-24; Dermatological Surgery, June 1999, pages 450-454; International Journal of Dermatology, August 2004, pages 604-607;and December 2003, pages 966-972; Archives of Dermatology, December 2002, pages 1578-1582; American Journal of Epidemiology, April 2005, pages 620-627; The American Journal of Clinical Dermatology, September-October 2000, pages 261-268; and The British Journal of Dermatology, December 1996, pages 867-875.