Acanthosis Nigricans or Pigmentosa is a skin disorder characterized by areas of darkened, thick, rough and velvety skin. Normally, it affects the flexible areas and folds of the body, such as the armpits, groins, neck folds, elbows, hands and feet.
Among its most common causes are hyperinsulinism, diabetes or obesity, and although there is no specific treatment for its cure, the underlying disease or condition must be treated and some topical drugs can be applied to improve the appearance of the skin.
In very few occasions, this skin condition is a warning sign of the presence of a cancerous tumor in an internal organ, but in the diagnostic this must be taken into account.