It is a condition in which there is hyperpigmentation and thickening of the skin in certain areas, most commonly in the back of neck, axilla, and groin. The exact causes of acanthosis nigricans vary and are often unknown. In some cases, it can be hereditary, other causes are endocrine causes such as cushing's syndrome or addison's disease. The most important clinical significance of this condition is diabetes mellitus, as it occurs in the prediabetic stage, thus the diagnosis of DM can be made early. Treatment is by life modifications, treating the underlying cause, or using creams or lotions to lighten the skin.