Acanthosis Nigricans in Alström Syndrome (Dark Skin Patches)

Acanthosis nigricans is the medical term for dark, velvety patches of skin that often appear in skin folds — the back of the neck, the armpits, the groin, and sometimes the knuckles. In Alström Syndrome, acanthosis nigricans is common and reflects the severe insulin resistance characteristic of the condition. This article covers what causes acanthosis nigricans, what it means medically, and what can be done about it.

Acanthosis nigricans typically appears as:

• Darker than surrounding skin
• Velvety or thickened texture
• Located in skin folds and friction areas
• Sometimes with skin tags
• Usually painless

Common locations:

• Back and sides of the neck (very common)
• Armpits
• Groin and inner thighs
• Inframammary folds
• Knuckles and finger creases (less common)¹

Acanthosis nigricans develops in response to chronically elevated insulin levels. The high insulin stimulates skin cells to grow faster than normal, leading to the thickened, darkened appearance. In Alström, the underlying severe insulin resistance keeps insulin levels chronically high, driving the changes.²

Other causes of acanthosis nigricans in the general population include:

• Type 2 diabetes
• Obesity
• Endocrine disorders (Cushing's, PCOS)
• Some medications
• Rarely, internal malignancy (sudden new acanthosis nigricans in adults warrants evaluation)

In Alström, the metabolic cause is the typical explanation.

Acanthosis nigricans is essentially a visible sign of significant underlying insulin resistance. It typically indicates:

• Insulin resistance that's been present for some time
• Increased risk of (or established) type 2 diabetes
• Other metabolic features (high triglycerides, fatty liver) often co-occur

Finding acanthosis nigricans in a child should prompt:

• Fasting glucose
• HbA1c
• Fasting insulin
• Lipid panel
• Liver function tests

Acanthosis nigricans itself is treated by addressing the underlying insulin resistance:

Improving insulin sensitivity

• Weight management to the extent possible
• Regular physical activity
• Limiting refined carbohydrates and sugary drinks
• Treating diabetes if present
• Medications like metformin

When insulin resistance improves, acanthosis nigricans often fades — though it may not disappear completely.³

Topical treatments

Cosmetic options for the appearance include:

• Topical retinoids (tretinoin) — under dermatology guidance
• Alpha-hydroxy acids — gentle exfoliation
• Salicylic acid — for thickening
• Laser treatments — for cosmetically distressing patches in selected cases

These don't address the underlying issue but can improve appearance.

What to avoid

• Aggressive scrubbing — irritates skin and doesn't help
• Bleaching products — generally not effective and can damage skin

For some children and adults, the appearance of acanthosis nigricans is distressing — particularly visible patches on the neck. Some considerations:

• Comments from peers, teachers, or strangers can be hurtful
• Sun protection can prevent additional darkening
• Clothing choices (collared shirts) cover neck involvement
• Discussing with a child what acanthosis nigricans is helps them respond to questions

• Insulin Resistance in Alström Syndrome
• Type 2 Diabetes in Alström Syndrome
• Childhood Obesity in Alström Syndrome
• Skin and Hair Findings in Alström Syndrome

April 30, 2026.