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Acanthosis nigricans
System: Skin & Nail Signs · All skin & nail signs
What it is — and how it is elicited
Dark, thickened, velvety skin in the body folds — typically the back and sides of the neck, armpits and groin.
What a positive finding suggests
Associated with insulin resistance and type 2 diabetes; rarely and when rapidly progressive in an older adult, it is associated with internal cancer.
Related signs — Skin & Nail Signs
Browse the A section of the A–Z list or return to the Clinical Signs hub.
Please note: This page is an educational reference about clinical examination signs. A clinical sign supports — and never replaces — a full clinical evaluation, examination and appropriate testing. A sign being present does not by itself prove a diagnosis, and an absent sign does not rule one out. If you have symptoms that worry you, see a health professional.