7 Common Signs and Symptoms of Acanthosis Nigricans You Should Know

Acanthosis nigricans is a skin condition characterized by dark, thickened patches that typically appear in body folds and creases. While it may seem like a cosmetic concern, this condition often signals underlying health issues, particularly insulin resistance and metabolic disorders. Recognizing the symptoms early can help you seek appropriate medical evaluation and address potential underlying causes.

This condition affects people of all ages and ethnic backgrounds, though it’s more common in individuals with darker skin tones, those who are overweight, and people with certain hormonal disorders. Understanding the signs and symptoms is crucial for early detection and management of associated health conditions.

1. Dark, Discolored Skin Patches

The most prominent and recognizable symptom of acanthosis nigricans is the appearance of dark, hyperpigmented patches on the skin. These patches typically range from brown to black in color and are noticeably darker than the surrounding skin.

The discoloration develops gradually over weeks or months and often appears symmetrically on both sides of the body. The affected areas may initially look dirty or unwashed, leading some people to scrub the skin vigorously, which doesn’t improve the appearance and may cause irritation.

Key characteristics of these dark patches include:

• Brown, grey, or black coloration
• Gradual onset and progression
• Symmetric distribution on the body
• Cannot be washed or scrubbed away
• More pronounced in skin folds

2. Thickened, Velvety Skin Texture

Beyond discoloration, the affected skin develops a distinctive thick and velvety texture that sets acanthosis nigricans apart from other skin conditions. When you touch the affected areas, the skin feels noticeably different from surrounding healthy skin—softer, yet thicker.

This velvety texture is due to the thickening of the outer layer of skin (hyperkeratosis) combined with the development of multiple small skin folds. The skin may feel:

• Soft and smooth, like velvet
• Thicker than normal skin
• Slightly raised or elevated
• Wrinkled or folded in appearance

This textural change is often one of the first symptoms people notice, especially when washing or applying lotion to affected areas.

3. Dark Neck (Insulin Resistance Neck)

One of the most common and visible locations for acanthosis nigricans is the neck, particularly the back and sides. This manifestation is often referred to as “dark neck” or “insulin resistance neck” because of its strong association with insulin resistance and prediabetes.

The dark discoloration around the neck can appear as:

• A dark ring or band encircling the neck
• Concentrated darkening at the back of the neck (nape)
• Patches extending from the neck to the jawline
• Gradual darkening that becomes more pronounced over time

Many people first notice this symptom when looking in the mirror or when someone else points it out. The neck location makes it particularly visible and can cause self-consciousness. Because the neck is strongly associated with insulin resistance, this symptom often prompts medical evaluation for diabetes and metabolic syndrome.

4. Affected Skin Folds and Creases

Acanthosis nigricans has a characteristic distribution pattern, predominantly affecting areas where skin folds and creases naturally occur. These locations provide the warm, moist environment where the condition tends to manifest most prominently.

Common affected areas include:

• Armpits (axillae): Often one of the first and most severely affected areas
• Groin: Including the inner thighs and genital area
• Neck: Especially the back and sides
• Under the breasts: In women and individuals with larger breasts
• Knuckles: Dark, thickened skin over the joints of fingers
• Elbows and knees: Particularly on the back surfaces
• Face: Occasionally around the eyes, nose, and mouth
• Navel: Around the belly button area

The severity can vary between different body areas, with some locations showing more pronounced changes than others.

5. Skin Tags in Affected Areas

People with acanthosis nigricans frequently develop skin tags (acrochordons) in the same areas where the dark, thickened patches appear. These are small, soft, flesh-colored or slightly darker growths that hang off the skin by a thin stalk.

Characteristics of skin tags associated with acanthosis nigricans:

• Multiple tags appearing in clusters
• Typically found in neck, armpits, and groin
• Size ranging from 1-5mm, occasionally larger
• Soft, movable texture
• Usually painless unless irritated or twisted

The presence of numerous skin tags along with darkened skin patches strengthens the diagnosis of acanthosis nigricans and may indicate insulin resistance or other hormonal imbalances.

6. Itching or Irritation

While acanthosis nigricans is typically asymptomatic, some people experience mild itching or discomfort in the affected areas. This symptom is less common but can occur, particularly when the condition is developing or if the skin becomes irritated.

When itching occurs, it may be due to:

• Friction from clothing or movement
• Sweating and moisture accumulation in skin folds
• Irritation from skin care products
• Secondary yeast or bacterial infections

Most people with acanthosis nigricans report no sensation in the affected areas, but any itching, burning, or pain should be evaluated by a healthcare provider as it may indicate complications or a different skin condition.

7. Gradual Onset and Progression

Unlike acute skin conditions that appear suddenly, acanthosis nigricans develops slowly over time. This gradual onset is an important characteristic that helps distinguish it from other skin disorders.

The typical progression includes:

• Early stage: Slight darkening and subtle texture changes that may go unnoticed
• Progressive stage: Increasingly visible dark patches with velvety texture
• Advanced stage: Pronounced thickening, darker pigmentation, and possible spread to new areas

The rate of progression varies significantly among individuals and depends on underlying causes. In cases related to obesity or insulin resistance, the condition may worsen with weight gain and improve with weight loss. In rare cases associated with cancer (malignant acanthosis nigricans), the onset may be more rapid and severe.

Tracking changes over time through photographs can help you and your healthcare provider monitor the condition’s progression and response to lifestyle modifications or treatment of underlying conditions.

Main Causes of Acanthosis Nigricans

Understanding the underlying causes of acanthosis nigricans is essential because the skin changes are often a visible manifestation of internal health issues. The condition itself is not dangerous, but what causes it may require medical attention.

Insulin Resistance and Diabetes

The most common cause of acanthosis nigricans is insulin resistance, a condition where cells don’t respond properly to insulin. High insulin levels in the blood can stimulate skin cells to multiply abnormally, leading to the characteristic dark, thickened patches. This is particularly common in people with:

• Type 2 diabetes
• Prediabetes
• Metabolic syndrome
• Polycystic ovary syndrome (PCOS)

Obesity and Weight Gain

Excess body weight, particularly abdominal obesity, is strongly associated with acanthosis nigricans. The connection is primarily through insulin resistance, as obesity often leads to decreased insulin sensitivity. Weight loss often improves or resolves the skin changes.

Hormonal Disorders

Various hormonal imbalances can trigger acanthosis nigricans, including:

• Polycystic ovary syndrome (PCOS)
• Cushing’s syndrome
• Hypothyroidism
• Acromegaly (excess growth hormone)

Medications

Certain medications may cause or worsen acanthosis nigricans, including:

• High-dose niacin
• Insulin injections
• Oral contraceptives
• Corticosteroids
• Some bodybuilding supplements

Genetic Factors

Some people inherit a tendency to develop acanthosis nigricans without any underlying disease. This hereditary form typically appears during childhood or adolescence and may be mild.

Cancer (Rare)

In rare cases, acanthosis nigricans can be a sign of internal cancer, particularly adenocarcinomas of the stomach, liver, or other organs. This malignant form typically has rapid onset, is more severe, and affects unusual areas like the palms and soles. If you notice sudden, widespread acanthosis nigricans, seek immediate medical evaluation.

Prevention Strategies

While not all cases of acanthosis nigricans can be prevented, especially those related to genetic factors, many cases associated with lifestyle and metabolic issues can be reduced or prevented through healthy habits.

Maintain a Healthy Weight

Since obesity and insulin resistance are primary causes, maintaining a healthy body weight through balanced nutrition and regular physical activity is the most effective prevention strategy. Even modest weight loss can significantly improve or resolve the condition.

Follow a Balanced Diet

A diet that helps maintain stable blood sugar levels can prevent insulin resistance:

• Limit refined carbohydrates and sugary foods
• Choose whole grains over processed grains
• Include plenty of vegetables, fruits, and fiber
• Opt for lean proteins and healthy fats
• Control portion sizes

Exercise Regularly

Regular physical activity improves insulin sensitivity and helps maintain healthy weight. Aim for at least 150 minutes of moderate-intensity exercise per week, including both aerobic activities and strength training.

Monitor Your Health

Regular medical check-ups can help detect and manage conditions that contribute to acanthosis nigricans:

• Regular blood sugar testing if at risk for diabetes
• Thyroid function tests if indicated
• Hormonal evaluations for PCOS or other endocrine disorders
• Blood pressure and cholesterol monitoring

Avoid Unnecessary Medications

Use medications only as prescribed by your healthcare provider. If you’re taking medications known to cause acanthosis nigricans and notice skin changes, consult your doctor about possible alternatives.

Practice Good Skin Care

While skin care won’t prevent acanthosis nigricans caused by internal factors, gentle care can help:

• Keep affected areas clean and dry
• Avoid harsh scrubbing or irritating products
• Use gentle, moisturizing cleansers
• Wear breathable, non-irritating clothing

Frequently Asked Questions

Is acanthosis nigricans dangerous?

Acanthosis nigricans itself is not dangerous or harmful. However, it often indicates underlying health conditions like insulin resistance or diabetes that do require medical attention. In rare cases, it may signal internal cancer, so medical evaluation is important.

Can acanthosis nigricans go away on its own?

Acanthosis nigricans may improve or resolve if the underlying cause is addressed. For example, weight loss and improved insulin sensitivity can lead to significant improvement. However, without treating the root cause, the condition typically persists or worsens.

Does acanthosis nigricans mean I have diabetes?

Not necessarily, but it is strongly associated with insulin resistance, which often precedes type 2 diabetes. If you have acanthosis nigricans, you should be evaluated for diabetes and prediabetes through blood tests. Early detection allows for intervention before diabetes develops.

Can I scrub away the dark patches?

No. The darkening is not dirt and cannot be scrubbed away. Vigorous scrubbing may irritate the skin and make the condition worse. The discoloration comes from within the skin and requires addressing the underlying cause rather than topical scrubbing.

Is acanthosis nigricans contagious?

No, acanthosis nigricans is not contagious. You cannot catch it from or spread it to other people. It is a skin reaction to internal metabolic or hormonal conditions, not an infection.

Who is most at risk for developing acanthosis nigricans?

People at higher risk include those who are overweight or obese, have insulin resistance or diabetes, have family history of the condition, have hormonal disorders like PCOS, are of African, Hispanic, or Native American descent, and those taking certain medications.

When should I see a doctor about dark skin patches?

You should consult a healthcare provider if you notice darkening, thickening skin patches, especially in skin folds; sudden or rapid development of these changes; patches that spread quickly or affect unusual areas; or if you have other symptoms like increased thirst, frequent urination, or unexplained weight changes.

Will losing weight improve acanthosis nigricans?

Yes, in many cases, weight loss can significantly improve or even resolve acanthosis nigricans, especially when the condition is caused by obesity and insulin resistance. However, improvement may take several months and requires sustained weight loss and healthy lifestyle changes.

Can children develop acanthosis nigricans?

Yes, children can develop acanthosis nigricans, and it’s becoming more common due to rising childhood obesity rates. In children, it’s often associated with insulin resistance and increased risk for developing type 2 diabetes. Children with this condition should be evaluated by a pediatrician.

Are there any complications of acanthosis nigricans?

The condition itself rarely causes physical complications, though psychological effects from appearance concerns can occur. The main concerns are the complications of underlying conditions like diabetes, including heart disease, nerve damage, and kidney problems. This is why identifying and treating the underlying cause is crucial.

References:

• Mayo Clinic – Acanthosis Nigricans
• American Academy of Dermatology – Acanthosis Nigricans
• NHS – Acanthosis Nigricans
• National Center for Biotechnology Information – Acanthosis Nigricans
• American Diabetes Association – Skin Complications