While going through the newspaper, I came across a medical condition called ACANTHOSIS NIGRICANS (AN). Friends, I had never heard of this condition before, so I tried to find out more details about it.
Actually, AN is a skin condition characterised by dark, thickened, and velvety patches that typically appear in body folds and creases such as the neck, armpits, groin, and sometimes over joints like knuckles or elbows. Although not a disease itself, it is often a visible sign of an underlying health issue, most commonly insulin resistance, obesity, or endocrine disorders. Occasionally, it may signal a more serious condition such as cancer of the internal organs.
Clinical Appearance
The hallmark of AN is:
- Darkened (hyper pigmented) skin that may appear brown, gray, or black.
- Thickened and velvety texture with a slightly raised surface.
- Common sites- back of the neck, underarms, groin, knees and knuckles.
- Associated features- mild itching or odour in affected areas.
Over time, the skin may become rougher and more noticeable, especially in individuals with darker complexions.
Types of AN
1 Obesity –Associated (Most Common)- Seen in overweight individuals due to insulin resistance, which stimulates excessive skin growth.
2 Endocrine or Hormonal Related– Linked with conditions such as polycystic ovarian syndrome (PCOS), Cushing’s syndrome, hypothyroidism or acromegaly.
3 Drug Induced– Certain medications such as niacin, insulin, oral contraceptives can trigger AN.
4 Genetic or Familial– A rare inherited form that appears during childhood and is not linked to obesity or insulin resistance.
Causes and Pathophysiology
The key underlying mechanism in most cases is hyperinsulinemia (excess insulin in the blood). When insulin levels are high, it can stimulate growth factor receptors in the skin, particularly those in keratinocytes and fibroblasts. This results in excessive proliferation of skin cells, leading to thickening and hyper pigmentation.
Other causes include– Genetic mutations affecting insulin receptors, Hormonal imbalances, Adverse drug reactions, and Cancer-related secretion of growth factors.
Associated Conditions
AN often accompanies
- Type 2 Diabetes or Prediabetes
- Metabolic Syndrome
- Obesity and Polycystic Ovarian Syndrome (PCOS)
- Cushing’s disease
- Hypothyroidism
- Certain cancers (stomach, pancreas, lung or uterus)
Diagnosis
It is primarily clinical, based on skin appearance and history. However tests are used to find the underlying cause:
- Blood glucose and insulin levels (to check for insulin resistance or diabetes)
- Lipid profile
- Hormonal Tests , especially in women for PCOS
- Thyroid function tests
- Cancer screening if malignancy is suspected or if the onset is sudden and severe.
A skin therapy may be performed in unclear cases to confirm the diagnosis and rule out other skin disorders.
Treatment and Management
There is no specific cure for AN, but managing underlying conditions can significantly improve the appearance of the skin.
1 Treat Underlying Cause
- Weight loss- Reduces insulin resistance and often leads to to partial or complete clearance.
- Manage diabetes or pre diabetes-Through diet, exercise, and medications.
- Discontinue triggering medications-under medical supervision.
- Treat hormonal disorders- Address PCOS, hypothyroidism, or Cushing syndrome appropriately.
- Cancer treatment-In cases or malignant AN, treating tumour often resolves the skin changes.
2 Topical treatments
To improve cosmetic appearance:
- Keratolytic creams-containing urea, salicylic acid, or alpha hydroxyl acids to soften thickened skin.
- Retinoids-such as tretinoin to reduce hyperkeratosis.
- Topical antibiotics or anti fungals if secondary infection occurs.
- Laser therapy or chemical peels- (for cosmetic improvement under dermatologist supervision).
3 Lifestyle Modifications
- Adopt a balanced, low-glycemic diet.
- Engage in regular physical activity.
- Maintain healthy body weight.
- Avoid excessive sugar intake and refined carbohydrates.
Prevention
- Maintain a healthy body weight.
- Managing blood sugars and insulin levels.
- Early detection and treatment of hormonal disorders.
- Avoid unnecessary medication use that can trigger the condition.
In the end, AN serves as a visible marker of internal health imbalances, especially those related to insulin resistance or hormonal dysfunction. While often benign, it can sometimes signal systematic disease. Early recognition, proper evaluation, and targeted management not only improve the skin condition but also prevent metabolic and cardiovascular complications in the long run.
Anil Malik
Mumbai, India
29th October 2025