From the Guidelines
Acanthosis nigricans is primarily caused by insulin resistance, which occurs when cells become less responsive to insulin, leading to higher insulin levels in the blood, as supported by the most recent study 1. This condition appears as dark, velvety patches of skin, typically in body folds and creases. Some common causes include:
- Obesity
- Type 2 diabetes
- Hormonal disorders like polycystic ovary syndrome (PCOS) and Cushing's syndrome
- Certain medications (including nicotinic acid, oral contraceptives, and corticosteroids)
- Rarely, certain cancers (particularly stomach cancer) Genetics can also play a role, as some people have a hereditary form of the condition. In children and adolescents, it's most commonly associated with obesity and insulin resistance, as noted in 1. Weight loss and managing underlying conditions often improve the appearance of acanthosis nigricans. The darkening occurs because high insulin levels stimulate skin cell growth, particularly in keratinocytes and dermal fibroblasts, causing the skin to thicken and darken in affected areas, which is consistent with the findings in 1 and 1. However, the most recent and highest quality study 1 provides the strongest evidence for the causes of acanthosis nigricans, emphasizing the importance of insulin resistance and its association with obesity and type 2 diabetes in children and adolescents.
From the Research
Causes of Acanthosis Nigricans
Acanthosis nigricans (AN) is a skin condition characterized by dark, velvety skin patches, typically in the folds and creases of the body. The causes of AN can be summarized as follows:
- Insulin resistance (IR) is a key factor in the development of AN, as it leads to hyperinsulinemia, which stimulates the growth of skin cells and increases the production of keratin, a protein that can cause skin darkening 2, 3, 4, 5.
- Obesity is closely associated with AN, as it can lead to IR and hyperinsulinemia. Studies have shown that AN is more common in obese individuals, particularly in those with a high body mass index (BMI) and waist circumference 2, 3, 4.
- Type 2 diabetes mellitus (DM) is also linked to AN, as it is characterized by IR and hyperinsulinemia. AN can be an early manifestation of type 2 DM, particularly in individuals with a family history of the disease 2, 4.
- Other factors that can contribute to the development of AN include:
- Genetic predisposition: Some individuals may be more prone to developing AN due to their genetic makeup 4.
- Hormonal imbalances: Certain hormonal imbalances, such as polycystic ovary syndrome (PCOS), can increase the risk of developing AN 2.
- Medications: Certain medications, such as niacin, can cause AN-like skin changes 6.
- The interplay between IR, excess weight, and AN is complex, and further research is needed to fully understand the relationships between these factors 3.
Associated Conditions
AN is often associated with other conditions, including:
- Metabolic syndrome: A cluster of conditions that increase the risk of developing type 2 DM and cardiovascular disease, including IR, obesity, dyslipidemia, and hypertension 2, 4.
- PCOS: A hormonal disorder that can increase the risk of developing AN, particularly in women with a family history of the disease 2.
- Lipodystrophic diabetes: A rare form of diabetes characterized by insulin resistance and skin changes, including AN 6.