Acanthosis Nigricans: Signs, Symptoms, Investigations, Associated Conditions, and Clinical Diagnosis

Dr. F. Shah


Acanthosis Nigricans

Acanthosis Nigricans (AN) is a dermatologic condition characterized by thickened, darkened patches of skin. It often serves as a clinical marker for underlying metabolic or endocrine abnormalities. In this article, we will delve into the signs, symptoms, investigations, associated conditions, and clinical diagnosis of Acanthosis Nigricans, aiming to provide comprehensive information for medical professionals and students.



Signs and Symptoms:


1. Skin Changes: AN manifests as velvety, hyperpigmented patches of skin, typically found in body folds such as the neck, axilla, groin, and flexural areas.


2. Texture: The affected skin may feel thickened or velvety to touch, differing from the surrounding skin.


3. Location Specificity: AN primarily affects intertriginous regions, but can also occur on the palms, soles, and mucosal surfaces.




1. Medical History: Thorough patient history is crucial. Inquire about family history, medication use, dietary habits, and any associated symptoms.


2. Physical Examination: A careful examination of the skin, especially in characteristic areas, is essential.


3. Blood Tests:

   - Fasting blood glucose: To assess for diabetes or insulin resistance.

   - Insulin levels: Elevated levels may suggest insulin resistance.

   - Lipid profile: Evaluate for dyslipidemia.


4. Hormonal Assays: If indicated, check levels of hormones such as thyroid-stimulating hormone (TSH), testosterone, and dehydroepiandrosterone sulfate (DHEAS).


5. Biopsy: In uncertain cases, a skin biopsy can provide definitive diagnosis.


Associated Conditions:


1. Insulin Resistance and Diabetes: AN is commonly associated with insulin resistance and can be a precursor to type 2 diabetes.


2. Obesity: A high body mass index (BMI) is often present in individuals with AN.


3. Polycystic Ovarian Syndrome (PCOS): AN may be seen in females with PCOS due to hormonal imbalances.


4. Hypothyroidism: AN can occur in association with thyroid disorders.


5. Genetic Syndromes: Rarely, AN can be a feature of certain genetic conditions.


Clinical Diagnosis:


1. Clinical Evaluation: A thorough clinical evaluation including history, physical examination, and assessment of associated conditions is paramount.


2. Investigations: Based on clinical suspicion, conduct appropriate blood tests and consider a skin biopsy if required.


3. Differential Diagnosis: Rule out other conditions that may mimic AN, such as frictional hyperpigmentation or post-inflammatory hyperpigmentation.


4. Underlying Conditions: Establish if AN is indicative of an underlying metabolic or endocrine abnormality.

Treatment Options:


1. Addressing Underlying Conditions:

   - Managing Diabetes or Insulin Resistance: This often involves lifestyle modifications, medications, and sometimes insulin therapy.

   - Weight Management: Achieving and maintaining a healthy weight through diet and exercise can be key in managing AN.


2. Topical Treatments:

   - Topical retinoids or keratolytics may help to improve the texture and appearance of the affected skin.


3. Oral Medications:

   - In cases linked to hormonal imbalances, treatment with hormonal therapies may be considered.


4. Lifestyle Modifications:

   - Adopting a balanced diet and regular exercise regimen can contribute to overall skin health and reduce the severity of AN.


5. Cosmetic Interventions:

   - Procedures like chemical peels, laser therapy, or dermabrasion may be considered in severe or resistant cases.

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