By Gary M. White, MD
Velvety thickening of the nape in an adolescent.
Acanthosis nigricans (AN) is a a velvety thickening of the skin of the neck and axilla.
Acanthosis nigricans presents as a thickening of the skin. Velvety thickening of the skin occurs on the neck and axilla. The elbows and of the hands may be involved as well. In the case of insulin resistance, the patient is usually obese. Diabetic finger pebbles is a variant that occurs on the knuckles. Acanthosis nigricans is more common in young adults and non-whites.
In the usual patient--young, overweight or obese, and with a strong family history of diabetes--no workup is necessary. The patient should be counseled on his or her risk of developing diabetes and the key need for weight loss and exercise. Metformin has been used with benefit in conduction with lifestyle changes [PD 1017;34;e281]. If the onset is abrupt and/or severe especially in an older person, the presence of a malignancy should be excluded. See malignant acanthosis nigricans.
With regard to topical therapy, this author has not found much to recommend. Some suggest combination use of a keratolytic and a retinoid, e.g., ammonium lactate 12% or 20% urea cream QAM and tretinoin or tazarotene QHS.
If blood work is desired to confirm the diagnosis, a fasting glucose and insulin level may be ordered.
Thickened, velvety skin of the axilla. Skin tags are common.
Thick velvety skin on the side of the neck.
When severe, AN may occur in more unusual sites.
Acanthosis nigricans on the abdomen at the site of repeated insulin injections.