Understanding melanoma: When to worry about a dark mole
5/29/2025 by Alexander Meves, M.D., MBA
Melanoma is a serious form of skin cancer that originates in melanocytes, the pigment-producing skin cells. While it accounts for only 1% of skin cancer cases, melanoma is responsible for most skin cancer-related deaths. In 2024, an estimated 100,640 new invasive melanoma cases were diagnosed in the United States.
Early detection is crucial. One of the most important warning signs is the "ugly duckling" sign, a mole that looks significantly different from others on your skin. If a spot stands out, a healthcare clinician should evaluate it.
Also, the ABCDE rule can help identify concerning moles:
- Asymmetry: One half of the mole does not match the other.
- Border: Irregular, blurred or jagged edges.
- Color: Multiple shades of brown, black, red, white or blue.
- Diameter: Larger than 6 mm (about the size of a pencil eraser).
- Evolving: Any size, shape, color or texture change over time.
Certain risk factors, such as fair skin, family history, male gender and age over 50, increase melanoma risk. If you notice a suspicious mole, seek medical evaluation promptly.
What does melanoma care involve?
At Mayo Clinic, dermatologists and specialists focus on diagnosing and treating melanoma. If melanoma is detected, surgical removal is often the first step. In addition to surgery, we can analyze tumor cells using molecular tests to better understand the cancer's behavior. This approach helps us personalize treatment for each patient, improving care and outcomes.
Does sunscreen help prevent melanoma?
Sunscreen is widely recommended to reduce the risk of skin cancer, including melanoma, by protecting the skin from harmful UV rays. However, some studies suggest that while sunscreen can help prevent sunburn, it may not always lower melanoma rates. One theory is that people who wear sunscreen may feel a false sense of security, leading them to spend more time in the sun. For the best protection, use sunscreen along with other sun safety measures: Seek shade, wear protective clothing and avoid peak sun hours when possible.
Alexander Meves, M.D., MBA, is a physician in the Department of Dermatology at Mayo Clinic in Rochester and a specialist in skin cancer. He combines research with patient care, focusing on advancing melanoma diagnostics and treatment. His work bridges scientific discoveries with real-world clinical applications to improve patient outcomes.