12168 Acanthosis Nigricans

Overview

Acanthosis nigricans (say: a-KAN-thoh-sis NY-gray-kans) is a skin condition where areas of skin become dark, thick, and velvety. It most often appears in body folds like the back of the neck, armpits, or groin. The condition itself is not painful or dangerous, but it is often a sign that the body is not using insulin as well as it should.

Yes, acanthosis nigricans is fairly common. It is especially common among people who are overweight or have a family history of type 2 diabetes. The chance of having it rises with higher levels of body fat and insulin resistance.

It can affect people of all ages and skin tones, but it is easier to see in people with darker skin. It is more common in children and teenagers who are overweight, in people with prediabetes or type 2 diabetes, and in people with certain hormonal conditions such as polycystic ovary syndrome (PCOS).

Symptoms

Common symptoms

• Dark, thickened patches of skin, often on the back or sides of the neck.
• Velvety texture on the affected areas.
• Patches in other body folds, such as the armpits, groin, or under the breasts.
• Skin color ranges from light brown to black.
• Small skin tags may appear near or on the patches.

Symptoms in children

• In children, acanthosis nigricans most often appears as a dark, velvety ring around the back of the neck.
• Armpits and other skin creases may also become dark and thick.
• Children with this condition are often overweight or at risk for insulin resistance.

Symptoms in older adults

• In older adults, patches may develop gradually over many months.
• If the patches appear suddenly and spread widely, especially to the palms, lips, or inside the mouth, it can be a sign of an underlying internal condition that needs prompt medical attention.

Causes

Main causes

• Insulin resistance: The body's cells do not respond normally to insulin, so the body makes extra insulin. High insulin levels can make skin cells multiply and produce more pigment, causing dark velvety patches.
• Obesity or excess weight: This is the most common trigger for insulin resistance and acanthosis nigricans.
• Hormonal disorders: Conditions like PCOS, Cushing's syndrome, or thyroid problems can increase the risk.
• Certain medicines: Some medications, including certain vitamins in high doses and some hormonal treatments, can trigger it.
• Rare genetic causes: Some inherited problems affect insulin receptors and cause acanthosis nigricans.
• Cancer (rare): Very rarely, acanthosis nigricans is linked to an underlying cancer, usually in the stomach. This is much less common than the metabolic causes.

Risk factors

• Being overweight or obese.
• Having a family history of diabetes or insulin resistance.
• Being of African, Native American, Hispanic, Asian, or Pacific Islander descent.
• Having PCOS or another hormonal condition.
• Taking certain medicines that affect insulin or hormones.
• Being older, for the rare cancer-linked form.

When to see a doctor

See a doctor urgently if:

• If the dark patches appear suddenly and spread quickly, especially to the palms, soles, lips, or mouth.
• If the patches come with unexplained weight loss, fever, fatigue, or other new symptoms.

Book a routine appointment if:

• If you notice a slow-growing velvety dark patch in a typical spot like your neck or armpit, mention it at your next appointment.
• If you have risk factors for diabetes, ask your doctor whether you should have a blood sugar test.

Diagnosis

A doctor can usually diagnose acanthosis nigricans simply by looking at the skin and taking your medical history. They may also check for other signs of insulin resistance, such as extra skin tags, overweight around the waist, or high blood pressure.

Tests that may be done

• Fasting blood sugar test – measures your blood sugar after you have not eaten for 8 hours.
• Hemoglobin A1c test – gives an average blood sugar level over the past 2–3 months.
• Fasting insulin level – checks the amount of insulin in the blood.
• Skin biopsy – a small piece of skin is removed and studied to rule out other causes if the diagnosis is unclear.

What to expect at your appointment

The doctor will ask about your health, lifestyle, family history, and any medicines you take. They will look at the affected skin and may order blood tests. It may help to come fasting, so ask when you make the appointment.

Treatment

Treatment focuses on the root cause. For most people, this means improving insulin sensitivity through weight loss and physical activity. If a medicine is causing the skin changes, changing that medicine may help. If an underlying illness is found, it will be treated. Skin patches often lighten over weeks to months once the cause is managed.

Self-care at home

• If you are overweight, aim for gradual weight loss – even 5–10% of your body weight can make a meaningful difference.
• Eat balanced meals with vegetables, fruits, whole grains, and lean proteins.
• Stay active: try to get at least 150 minutes of moderate exercise, like brisk walking, each week.
• Use a gentle moisturizer to keep skin soft and comfortable.
• Wear loose clothing to reduce friction in skin folds.
• Protect your skin from sun, since tanning can make dark patches appear darker.

Medical treatments

Doctors may prescribe topical treatments, such as creams or gels, to help soften and lighten the patches. These do not treat the underlying cause. Cosmetic procedures like laser therapy or chemical peels can be used to improve appearance. If insulin resistance is severe, a doctor may recommend treatment for that condition. Never use prescription skin treatments without a doctor's guidance.

When is surgery considered?

Surgery is not a treatment for acanthosis nigricans itself. Cosmetic procedures such as laser therapy may be offered for appearance, but they do not solve the underlying health problem. Surgically removing the patch is not recommended because it is likely to come back if the cause remains.

Living with this condition

Living with acanthosis nigricans means managing the underlying health issue and keeping your skin comfortable. Check your skin regularly, follow your doctor's advice, and use gentle skin care. The patches are not contagious and are not caused by poor hygiene.

Lifestyle tips

• Set realistic weight loss goals, such as a small steady loss each week.
• Find physical activity you enjoy – walking, swimming, dancing, or cycling all count.
• Aim for good-quality sleep; poor sleep can make insulin resistance worse.
• Limit sugary drinks and highly processed foods that can cause insulin spikes.
• Work with a dietitian if you need help creating a meal plan that fits your culture and budget.

Diet and exercise

A balanced diet rich in vegetables, fruits, whole grains, and healthy proteins, combined with regular movement, is the most effective way to improve insulin resistance. Start small – add one extra vegetable to a meal or take an extra short walk each day. Your healthcare team can help you build a plan that fits your life.

Mental health and emotional wellbeing

Acanthosis nigricans can be embarrassing, especially for teenagers and young adults. The patches are visible and may affect self-confidence. It is normal to feel worried about how it looks. Talking to a mental health professional or joining a supportive group can help you cope with body image concerns. Remember, this condition is not a sign of laziness or poor hygiene – it is a medical sign that deserves understanding and care.

Prevention

Acanthosis nigricans can often be prevented by maintaining a healthy weight, staying physically active, and eating a balanced diet. If you have a strong family history of diabetes or are from a high-risk group, ask your doctor about routine blood sugar checks.

Screening programmes

There is no specific screening test for acanthosis nigricans itself. But if you have the skin changes, your doctor may screen you for type 2 diabetes, high cholesterol, and other metabolic conditions. Some blood tests may need to be repeated over time.

Complications

If left untreated

• Insulin resistance may progress to type 2 diabetes.
• The skin patches may become thicker, darker, and more widespread.
• Skin irritation, itching, and sometimes infections may develop in the folds.
• Long-term metabolic issues can increase the risk of heart disease and stroke.

Long-term outlook

With proper care, the outlook is good. Most people see their skin patches lighten or soften when they lose weight and improve their insulin sensitivity. Even if the patches do not fully disappear, they are not dangerous. The most important step is to work with your healthcare team to protect your long-term health.

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