Acanthosis nigricans (AN), a skin condition commonly encountered by diabetes care and education specialists, presents as thickened, velvety, dark brown to black patches with blurry edges in areas where skin folds, such as underarms, neck, and groin.
Acanthosis nigricans (AN), a skin condition commonly encountered by diabetes care and education specialists (DCESs), presents as thickened, velvety, dark brown to black patches with blurry edges in areas where skin folds, such as underarms, neck, and groin.1 AN increases with time, typically occurs in individuals younger than age 40, and is more common in people of Native American, African American, and Hispanic descent.2
The same properties that treat type 2 diabetes help to reduce hyperinsulinemia and weight in the metabolic acanthosis nigricans pathophysiology cascade.
AN is most often linked to obesity and insulin resistance. However, it has other rare causes, including paraneoplastic disorders, certain medications, genetics, and autoimmune conditions.2 Thus, even though AN is most commonly secondary to metabolic abnormalities, DCESs should keep other etiologies on their differentials and discern if further evaluation is warranted.
Elevated adiposity and low physical activity cause hyperinsulinemia. This causes fibroblast proliferation and enhanced stimulation of epidermal keratinocytes and dermal fibroblasts.1,3 Figure 1 is a depiction of this pathophysiologic cascade. Treatment of AN can target different areas of the cascade.3,4 The mainstay of treatment for obesity-induced AN is lifestyle intervention because it targets the primary inciting factors.1-3 Lifestyle changes are often challenging and ineffective alone, and pharmacologic agents are routinely employed as adjunctive treatment to target the pathophysiologic cascade of AN.3,4
Metformin is a first-line treatment for type 2 diabetes mellitus that reduces gluconeogenesis and increases muscle and fat tissue glucose utilization.3 This oral medicine can treat other conditions, including acanthosis nigricans.3 The same properties that treat type 2 diabetes help to reduce hyperinsulinemia and weight in the metabolic acanthosis nigricans pathophysiology cascade.3 Glucagon-like peptide-1 receptor agonists are newer medications that treat type 2 diabetes and obesity. They would treat AN similarly to metformin, but there is little research on their use specifically for treating AN due to their novelty.
AN is often an asymptomatic skin condition, but satisfactory improvement is often not observed with treatment of a patient’s insulin resistance with lifestyle measures and oral agents alone.5 Topical agents, including retinoids and vitamin D analogs, have been shown to be effective when a lack of improvement is observed.
Topical retinoids are considered first-line treatment for AN, with evidence of improvement in multiple studies, thought to work by reducing hyperkeratosis. Notably, relapse did occur upon discontinuing therapy; therefore, intermittent tretinoin application was needed for patients to prevent recurrence moving forward.4 Vitamin D analogs are another helpful topical treatment option that works by inhibiting keratinocyte proliferation.5-7 Skin irritation is the main side effect of these topical medicines, and patients should be counseled on this side effect. Moisturization can be used adjunctively to reduce irritation, and other alternate approaches include reduced frequency of application and reduced medication concentration.
Chemical peels with trichloroacetic acid (TCA) can also be used to treat AN safely. TCA causes destruction of the epidermis, followed by inflammation, wound repair, and reepithelialization with smoother skin formation. Postinflammatory hyperpigmentation, peeling, and skin irritation are side effects of this treatment option that is being actively studied.4,8 Oral retinoids may also have some utility in treating AN but require high doses and long treatment courses, which increases risk of side effects.4
Diabetes care teams have much to consider when managing acanthosis nigricans, including social, aesthetic, metabolic, and lifestyle factors. Management typically requires a multimodal/multidisciplinary approach, of which DCESs should be a part.
Brian Burroughs, MSPAS, PA-C, BC-ADM, CDCES, is with Mayo Clinic Health System in Red Wing, MN. Hayden Middleton, DMSc, PA-C, and Brittany Strelow, DMSc, PA-C, are with Mayo Clinic in Rochester, MN.
The authors declare having no professional or financial association or interest in an entity, product, or service related to the content or development of this article.
The authors declare having received no specific grant from a funding agency in the public, commercial, or not-for-profit sectors related to the content or development of this article.
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Diabetes care teams have much to consider when managing acanthosis nigricans, including social, aesthetic, metabolic, and lifestyle factors.