Acanthosis Nigricans
General
Acanthosis nigricans (abbreviated as AN) is a skin disorder in which the skin darkens (hyperpigmentation) and thickens (hyperkeratosis). It usually occurs in skin folds, such as the armpits, groin and neck, and the affected skin often takes on a velvety appearance. AN affects both men and women and can occur at any age, but is more common in people with darker skin tones. It is actually not an isolated skin disease, but rather a sign of an underlying condition. In Western societies, AN is often associated with obesity and type 2 diabetes.
What is the cause?
The exact cause of acanthosis nigricans is not yet fully known, but there seems to be a link to insulin resistance, especially because of its relation to obesity and diabetes. Friction and irritation in skin folds probably play a role in its development, although this has not been scientifically proven. Risk factors include obesity, endocrine or metabolic disorders, genetic syndromes, reactions to medication or in rare cases, an internal malignancy.
What does acanthosis nigricans look like?
The affected skin in AN shows thickening with gray to brownish-black discoloration, usually in skin folds. It has a velvety to wart-like surface, often in the neck and armpits, but sometimes in other places such as between the buttocks, under the breasts, in abdominal folds, on the flexural side of the elbows or in the groin. Symmetry is characteristic, and sometimes skin tags develop in the dark spots.
The classification of acanthosis nigricans is based on the underlying cause, such as obesity, diabetes, syndromes, hereditary factors, medication-induced, malignancy, or a specific variant called acral acanthotic abnormality.
How do I know if I have AN?
Diagnosis is usually made visually, but if in doubt, a skin biopsy may be taken. Treatment often focuses on addressing the underlying cause. Lifestyle changes, such as weight loss, are important. Local treatments focus mainly on the cosmetic aspect, with agents such as retinoids, topical vitamin D analogues, dermabrasion and laser treatment.
What to do in AN?
If you have acanthosis nigricans, it is advisable to address the underlying cause, such as by losing weight and making dietary changes. Home, garden and kitchen remedies are not strongly recommended. The course of AN is chronic, but with a benign underlying cause, it usually has no serious consequences except possibly cosmetic concerns. With an underlying malignancy, however, the prognosis is often less favorable.
If you are in doubt about whether you have acanthosis nigricans, contact one of our dermatologists at 247dermatologist.