Acanthosis Nigricans Clinical Presentation

Updated: Oct 29, 2018
  • Author: Jason H Miller, MD; Chief Editor: William D James, MD  more...
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Presentation

History

Patients usually present with an asymptomatic area of darkening and thickening of the skin. Pruritus occasionally may be present. Lesions begin as hyperpigmented macules and patches and progress to palpable plaques.

In approximately one third of cases of malignant acanthosis nigricans, patients present with skin changes before any signs of cancer. In another one third of cases, the lesions of acanthosis nigricans arise simultaneously with the neoplasm. In the remaining one third of cases, the skin findings manifest sometime after the diagnosis of cancer. Malignant acanthosis nigricans has been reported to appear abruptly and exuberantly and may be associated with a higher rate of pruritus. [1]

Onset may be related to medication or supplement usage.

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Physical Examination

Acanthosis nigricans is characterized by symmetrical, hyperpigmented, velvety plaques that may occur in almost any location but most commonly appear on the intertriginous areas of the axilla, groin, and posterior neck. The posterior neck is the most commonly affected site in children.

Acrochordons (skin tags) are often found in and around the affected areas. Occasionally, lesions of acanthosis nigricans may be present on the mucous membranes of the oral cavity, nasal and laryngeal mucosa, and esophagus. The areola of the nipple also may be affected. Eye involvement, including papillomatous lesions on the eyelids and conjunctiva, may occur. Nail changes, such as leukonychia and hyperkeratosis, have been reported.

The lesions of malignant acanthosis nigricans are clinically indistinguishable from benign acanthosis nigricans.

Note the images below.

Brown velvety plaques with skin tags in the axilla Brown velvety plaques with skin tags in the axilla of a patient with acanthosis nigricans.
Acanthosis nigricans. Acanthosis nigricans.
Acanthosis nigricans, obesity related. Acanthosis nigricans, obesity related.
Acanthosis nigricans of the axilla with one skin t Acanthosis nigricans of the axilla with one skin tag.
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Complications

Complications vary depending on the etiology of acanthosis nigricans (AN). Appearance of acanthosis nigricans during childhood usually is associated with a benign condition, and no important sequelae are described.

Adult-onset acanthosis nigricans is more worrisome, and an underlying malignancy must be ruled out. However, most cases of adult-onset acanthosis nigricans are benign and often are associated with insulin resistance.

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