Facial Acanthosis Nigricans

For the past 7 years, an obese 22-year-old African American woman had had asymptomatic, velvety hyperpigmentation on both cheeks. Similar hyperpigmentation was present on the neck, in the axillae, and on the elbows. The patient’s only medications were antihypertensives.

Acanthosis nigricans has been linked to obesity, insulin resistance, endocrine disorders, familial inheritance, genetic variations, internal malignancies, and a plethora of drugs. This nonspecific dermatologic manifestation is characterized by symmetric velvety hyperpigmentation and typically occurs in the flexural areas of the skin, such as the axillae and neck. It may also occur on the scalp, palms, and face.¹

Most cases of facial acanthosis nigricans are associated with a paraneoplastic process. Typically, acanthosis nigricans associated with a paraneoplastic process can be distinguished from other varieties by its rapid onset, extensive involvement, hyperkeratosis of the palmoplantar surfaces, and generalized pruritus.² However, rare reports are emerging of facial acanthosis nigricans with a more gradual onset.

Most patients who have the more limited and slower-onset facial acanthosis nigricans are obese and have hyperinsulinemia; the hyperpigmentation usually develops over the temples³ and forehead.⁴ In one reported case, however, a non-obese child with no known endocrine abnormalities or underlying malignancy had acanthosis nigricans in the alar and melolabial folds.⁵

This patient had an elevated insulin C-peptide level of 10.9 ng/mL (normal range, 0.5 to 2.0 ng/mL) and a hemoglobin A_1c level of 6.4% (normal level, less than 6%). She reported a family history of type 2 diabetes mellitus, irregular menstrual cycles, and hirsutism on the chest and face, but she denied acne and hair loss. She was further evaluated by an endocrinologist, who suspected she had type 2 diabetes, as well as polycystic ovarian syndrome. Thus, depending on the rate of onset and associated cutaneous findings, facial acanthosis nigricans should raise clinical suspicion for either an underlying malignancy or a metabolic disorder.³

Aesthetic treatment is generally ineffective, although lactic acid, topical urea, salicylic acid, calcipotriol, and retinoids have all been used with anecdotal success. Metformin6 and weight loss⁷ may improve the appearance of acanthosis nigricans. In one reported case, a patient with long-standing facial acanthosis nigricans, which had proved resistant to dermabrasion, tretinoin, calcipotriol, and systemic etretinate, noted aesthetic improvement after carbon dioxide laser resurfacing.⁸