Dark, velvety skin patches on the neck, underarms, or groin are often mistaken for poor hygiene, but they may be a condition called Acanthosis Nigricans.
Doctors say it is usually a sign of insulin resistance or other metabolic issues like prediabetes or PCOS, where the skin thickens and darkens in body folds.
While it is not dangerous on its own, it can signal an underlying health problem that should be checked by a doctor. In many cases, it improves once the root cause is treated.