Acanthosis nigricans

Management Strategy

The management of patients with acanthosis nigricans addresses the underlying cause, the identification of which requires a salient history, a targeted physical examination, focused diagnostic laboratory tests, and, occasionally, radiologic evaluation.

Relevant historical information includes age at onset, speed of progression from onset, presence or absence of family history, medications, transplant history, and presence or absence of symptoms related to hyperinsulinemia, hyperandrogenemia, hypercortisolism, and internal malignancy.

Drugs reported in association with acanthosis nigricans include niacin, corticosteroids, estrogens, testosterone, insulin, aripiprazole, fusidic acid, protease inhibitors, triazinate, diethylstilbestrol, palifermin, and recombinant growth hormone. Acanthosis nigricans has also been associated with renal and lung transplantation.

Physical examination should document obesity, masculinization, hirsutism, lymphadenopathy, Cushingoid features, and organomegaly. Initial laboratory screening should include fasting blood glucose and serum insulin tested concurrently to confirm or exclude insulin resistance.

Because obesity is the most common cause of both insulin resistance and acanthosis nigricans, it is the likely cause of acanthosis nigricans in overweight patients with no historical suggestion of culprit drugs or evidence of malignancy.

Rare causes of insulin resistance and acanthosis nigricans include the type A and B syndromes, the former characterized by defective insulin receptors and the latter by circulating anti-insulin receptor antibodies in association with autoimmune disorders such as lupus erythematosus. Other causes of insulin resistance and acanthosis nigricans are polycystic ovarian disease, HAIR-AN syndrome, familial lipodystrophies, and various endocrinopathies.

The most commonly associated malignancy is gastric adenocarcinoma. Less frequent associations are endocrine, genitourinary, lung, and gastrointestinal carcinomas, and, even more rarely, melanoma and cutaneous T-cell lymphomas/Sézary syndrome. Malignant acanthosis nigricans may coexist with other cutaneous markers of internal malignancy, such as tripe palms, the sign of Leser–Trélat, florid cutaneous papillomatosis, and hyperkeratosis of the palms and soles. If malignancy-associated acanthosis nigricans is suspected, age-appropriate cancer screening should be performed. Additional laboratory tests may include a complete blood count, stool test for occult blood, and chest and gastrointestinal radiographs, as well as gastrointestinal endoscopy. Referral to the appropriate specialist would be indicated.

In the absence of objective evidence for a specific cause, the acanthosis nigricans may be labeled as idiopathic, which may or may not be familial. Treatment of the underlying cause, if identified, often leads to the resolution of the acanthosis nigricans. Otherwise, most published treatment modalities are symptomatic and/or cosmetic.