Acanthosis nigricans is a skin condition that causes some areas of the skin to darken and thicken. This condition is not harmful but it is sometimes an indicator of other health problems such as pre-diabetes. Obesity is the primary cause of this skin condition.
Acanthosis nigricans may form on the armpits, neck, upper back, groin area, elbows, knees, knuckles, belly button, woman’s breasts, face, and female genitalia. It may take a while to form, ranging from months to years.
Anyone can get this skin condition but risk factors include obesity, Native American, African, Caribbean, or Hispanic descent, and family with history of acanthosis nigricans.
Learn more at the American Academy of Dermatology: AAD Acanthosis nigricans.