Acanthosis nigricans is a common skin condition characterized by areas of darkened, thickened, and velvety skin. While it can appear in various body folds, the armpit (axilla) is a particularly frequent and noticeable location for these changes. This article explores its characteristics, underlying causes, and management.
Understanding Acanthosis Nigricans
Acanthosis nigricans appears as darkened skin, ranging from light brown to black. In the axilla, this discoloration often feels thickened and velvety to the touch. The affected skin may also appear slightly raised and can develop small, wart-like growths in some cases.
These skin changes typically develop gradually and are often symmetrical, appearing in both armpits simultaneously. While generally asymptomatic, some individuals might experience mild itching in the affected area. The skin folds in the armpit can also trap moisture, potentially leading to a slight odor, though acanthosis nigricans itself is not inherently itchy or malodorous. Acanthosis nigricans is not a skin disease itself, but rather a visible sign of an underlying health condition.
Underlying Causes
The most common reason for acanthosis nigricans developing in the axilla is insulin resistance, which can precede prediabetes or type 2 diabetes. When the body’s cells become resistant to insulin, the pancreas produces more insulin to compensate, leading to elevated levels in the bloodstream. These high insulin levels can then stimulate the growth of skin cells, resulting in the characteristic thickening and darkening.
Obesity is strongly linked to insulin resistance and the development of acanthosis nigricans. A higher body mass index (BMI) often correlates with increased insulin resistance, making obesity a significant contributing factor.
Certain hormonal disorders also play a role in its emergence. Conditions such as Polycystic Ovary Syndrome (PCOS), which involves insulin resistance and hormonal imbalances, can lead to its appearance.
Other endocrine conditions, including hypothyroidism and adrenal gland disorders like Cushing’s syndrome, can also be associated with acanthosis nigricans. Additionally, some medications have been known to induce these skin changes as a side effect. Examples include high-dose nicotinic acid, certain oral contraceptives, systemic corticosteroids, and growth hormone therapy.
In very rare instances, acanthosis nigricans can be a sign of an internal malignancy, most often an adenocarcinoma of the gastrointestinal tract. This form, known as malignant acanthosis nigricans, is typically more widespread, rapidly progressing, and can affect mucous membranes.
Management and Next Steps
If you notice darkened, velvety patches in your armpits, seeking medical evaluation is an important next step. A healthcare provider can perform a physical examination and may order blood tests, such as blood glucose, insulin levels, or hormone panels, to identify the underlying cause. This diagnostic process is important, given the potential link to conditions like insulin resistance, prediabetes, or other systemic issues.
The primary approach to managing acanthosis nigricans involves treating the underlying condition. For cases related to insulin resistance, lifestyle modifications are often recommended. These include dietary changes, such such as reducing refined carbohydrates and sugars, and regular physical activity. Weight loss can significantly improve insulin sensitivity, leading to a reduction or resolution of the skin changes.
If an underlying medical condition like diabetes, PCOS, or a thyroid disorder is diagnosed, specific medications may be prescribed. As the underlying cause is brought under control, the appearance of acanthosis nigricans often fades or disappears over time.
In addition to addressing the root cause, certain topical treatments can help improve the skin’s appearance. These may include creams containing retinoids, urea, salicylic acid, or ammonium lactate, which can lighten and smooth the affected skin. For more persistent or cosmetically concerning cases, laser therapy can also be considered.