Acanthosis Nigricans

Acanthosis nigricans appears as dark, thick, velvety patches of skin, most commonly on the back of the neck, armpits, or groin. It is not dangerous or contagious, but it is an important visible sign that your body may be struggling with insulin resistance — a precursor to type 2 diabetes. The patches usually improve when the underlying insulin resistance is treated through weight loss and lifestyle changes.

Acanthosis nigricans is a cutaneous marker of hyperinsulinaemia, presenting as symmetric, hyperpigmented, velvety plaques typically affecting intertriginous areas (neck, axillae, groin). Elevated circulating insulin binds to insulin-like growth factor 1 (IGF-1) receptors on keratinocytes and dermal fibroblasts, stimulating epidermal proliferation. It is strongly associated with obesity, insulin resistance, metabolic syndrome, and polycystic ovary syndrome (PCOS). Resolution typically parallels improvement in insulin sensitivity through weight reduction and physical activity.

Spotting acanthosis nigricans during a physical examination at Accord Medical provides an early warning that metabolic health needs attention — often years before blood tests show abnormalities.