WOMEN'S HEALTH Hair/Nails/Skin • Corns and calluses • Diaper rash • Nail fungus • Shingles • Ingrown toenails • Moles • Acne • Psoriasis • Hair loss • Sweating and body odor • Rosacea • Hives and angioedema • Athlete's foot • Dermatitis/Eczema • Cold sore • Common warts • Cellulitis • Anal itching • Dandruff • Impetigo • Boils and carbuncles • Ringworm of the body • Jock itch • Plantar warts • Folliculitis • Dry skin • Actinic keratosis • Bedsores (Pressure sores) • Vitiligo • Lipoma • Tinea versicolor • Acanthosis nigricans • Molluscum contagiosum • Neurodermatitis (lichen simplex chronicus) • Morphea • Pityriasis rosea • Lichen nitidus • Bullous pemphigoid • Pyoderma gangrenosum • Lichen sclerosus • Ichthyosis vulgaris • Pilonidal cyst • Pemphigus • Sweet's syndrome • Sacral dimple • Dermatographia • Keratosis pilaris • Poison ivy rash • Lichen planus • Granuloma annulare • Dyshidrosis • Hidradenitis suppurativa • Henoch-Schonlein purpura • Hemangioma

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Acanthosis nigricans is a skin condition characterized by dark, thick, velvety skin in body folds and creases. It most often affects the armpits, groin and neck.

Acanthosis nigricans is mainly a cosmetic concern. There's no specific treatment — but treating any underlying conditions may cause the skin changes to fade.

Skin changes are the only signs of acanthosis nigricans. You'll notice dark, thick, velvety skin in body folds and creases — typically the armpits, groin and neck. Sometimes the lips, palms or soles of the feet are affected as well. The skin changes appear slowly, sometimes over months or years. Rarely, the affected areas may itch.

Acanthosis nigricans is often associated with conditions that increase your insulin level, such as type 2 diabetes or being overweight. If your insulin level is too high, the extra insulin may trigger activity in your skin cells. This may cause the characteristic skin changes.

In some cases, acanthosis nigricans is inherited. Certain medications — such as human growth hormone, oral contraceptives and large doses of niacin — can contribute to the condition. Other hormone problems, endocrine disorders or tumors may play a role as well. Rarely, acanthosis nigricans is associated with certain types of cancer.

Acanthosis nigricans can begin at any age. It's most obvious in people who have dark skin.

Consult your doctor if you notice changes in your skin — especially if the changes appear suddenly. You may have an underlying condition that needs treatment.

Acanthosis nigricans is typically detected during a skin exam. The doctor may recommend blood tests, X-rays or other tests to look for possible underlying causes. Sometimes a small skin sample is removed for examination in a lab.

There's no specific treatment for acanthosis nigricans. Treating any underlying conditions may cause the skin changes to fade, however. If you're overweight, losing excess pounds can help. Sometimes dietary changes are helpful, too.

If you're concerned about the appearance of your skin, your doctor may prescribe a cream or lotion to help lighten the affected areas. Some of these lotions contain modified vitamin A products such as tretinoin (Retin-A, others) or other medications. Sometimes oral medications such as etretinate or isotretinoin (Accutane, others) are helpful. Fish oil supplements may also be recommended. Dermabrasion or laser therapy may help reduce the thickness of certain affected areas.