Acanthosis nigricans (ak-an-THOE-sis NIE-grih-kuns) is a skin condition characterized by dark, thick, velvety skin in body folds and creases. Most often, acanthosis nigricans affects your armpits, groin and neck.
With acanthosis nigricans, you may naturally be concerned about the appearance of your skin. Some steps may help lighten the affected areas of your skin. There's no specific treatment for acanthosis nigricans — but treating any underlying conditions, such as diabetes and obesity, may cause the changes in your skin to fade.
Characteristics of acanthosis nigricans include:
Skin changes. Skin changes are the only signs of acanthosis nigricans. You'll notice dark, thick, velvety skin in body folds and creases — typically in your armpits, groin and neck. Sometimes the lips, palms or soles of the feet are affected as well.
Slow progression. The skin changes appear slowly, sometimes over months or years.
Possible itching. Rarely, the affected areas may itch.
When to see a doctor
Consult your doctor if you notice changes in your skin — especially if the changes appear suddenly. You may have an underlying condition that needs treatment.
Acanthosis nigricans is often associated with conditions that increase your insulin level, such as type 2 diabetes or being overweight. If your insulin level is too high, the extra insulin may trigger activity in your skin cells. This may cause the characteristic skin changes.
In some cases, acanthosis nigricans is inherited. Certain medications — such as oral contraceptives and large doses of niacin — can contribute to the condition. Other hormone problems, endocrine disorders or tumors may play a role as well. Rarely, acanthosis nigricans is associated with certain types of cancer.
Acanthosis nigricans can begin at any age. It's more common in people who have dark skin.
Preparing for your appointment
You're likely to start by seeing your family doctor or a general practitioner. However, in some cases when you call to set up an appointment, you may be referred to an endocrinologist. Because appointments can be brief, and because there's often a lot of ground to cover, it's a good idea to be well prepared for your appointment. Here's some information to help you get ready for your appointment, and what to expect from your doctor.
What you can do
Be aware of any pre-appointment restrictions. At the time you make the appointment, be sure to ask if there's anything you need to do in advance, such as restrict your diet.
Write down any symptoms you're experiencing, including any that may seem unrelated to the reason for which you scheduled the appointment.
Write down key personal information, including past illnesses and operations, major stresses or recent life changes, and any medical problems that run in your family.
Make a list of all medications, as well as any vitamins and supplements, that you're taking.
Take a family member or friend along, if possible. Sometimes it can be difficult to soak up all the information provided to you during an appointment. Someone who accompanies you may remember something that you missed or forgot.
Write down questions to ask your doctor.
Your time with your doctor is limited, so preparing a list of questions will help you make the most of your time together. List your questions from most important to least important in case time runs out. For acanthosis nigricans, some basic questions to ask your doctor include:
What is likely causing my symptoms or condition?
Are there other possible causes for my symptoms or condition?
What kinds of tests do I need?
Is my condition likely temporary or chronic?
What is the best course of action?
What are the alternatives to the primary approach that you're suggesting?
I have these other health conditions. How can I best manage them together?
Are there any restrictions that I need to follow?
Should I see a specialist?
Is there a generic alternative to the medicine you're prescribing me?
Are there any brochures or other printed material that I can take home with me? What Web sites do you recommend visiting?
In addition to the questions that you've prepared to ask your doctor, don't hesitate to ask questions during your appointment whenever you don't understand something.
What to expect from your doctor
Your doctor is likely to ask you a number of questions. Being ready to answer them may reserve time to go over any points you want to spend more time on. Your doctor may ask:
When did you first begin experiencing acanthosis nigricans?
How severe are your symptoms?
Has anyone in your immediate family experienced acanthosis nigricans?
What, if anything, seems to improve your acanthosis nigricans?
What, if anything, makes your acanthosis nigricans worse?
Tests and diagnosis
Acanthosis nigricans is typically detected during a skin exam. Rarely, a small skin sample is removed (biopsied) for examination in a lab.
If the cause of acanthosis nigricans is unclear, your doctor may recommend blood tests, X-rays or other tests to look for possible underlying causes.
Treatments and drugs
There's no specific treatment for acanthosis nigricans. However, treating any underlying conditions may cause the skin changes to fade, such as:
Losing excess pounds if you're overweight
Making dietary changes, such as cutting back on starches and sugars
If you're concerned about the appearance of your skin, your doctor may recommend these treatments:
Prescription creams or lotions to lighten the affected areas, such as those containing modified vitamin A products (Retin-A, others)
Oral medications, such as isotretinoin (Accutane, Sotret)
Fish oil supplements
Dermabrasion or laser therapy, which may help reduce the thickness of certain affected areas
Thick lesions can have a bad odor. Using antibacterial soaps or a topical antibiotic may help.