Moles and Melanoma

Moles (nevi) are small marks formed when melanocytes — the cells that give skin its colour — multiply in a particular area. They range in colour from light brown to black. They may be present at birth or appear during childhood, adolescence or adulthood. Most moles are entirely benign and need no treatment. However, changes that develop over time in certain moles, or newly appearing moles, should be assessed carefully.

Melanoma is a malignant skin cancer that also arises from melanocytes, but develops through uncontrolled proliferation. When diagnosed at an early stage, the success of treatment is very high. If diagnosis is delayed, however, it can spread to the lymph nodes and internal organs, become harder to treat and even prove fatal.

Melanoma may sometimes develop within an existing mole, and sometimes appear as a new dark lesion on an area of previously normal-looking skin. Only 20–25% of melanoma cases arise from an existing mole; 75% appear on normal skin. This is why not only existing moles but also newly developing ones need careful assessment. Not every mole becomes melanoma, and not every new mole is melanoma. What matters is correctly identifying the moles that carry risk and, where necessary, keeping them under close follow-up or removing them surgically.

Who is at higher risk of melanoma? The risk is higher in people who have a large number of moles, atypical (dysplastic) moles, fair skin, light-coloured eyes and hair, a history of severe sunburn in childhood or adolescence, a personal or family history of melanoma, or conditions and medications that suppress the immune system. Regular dermatological check-ups are of great importance for anyone with one or more of these risk factors.

Which moles should be assessed? It is advisable to see a dermatologist if a mole grows over a short period; changes shape or develops irregular borders; contains several colours, or develops many colours in a mole that had only one or two; becomes asymmetric; itches, bleeds, crusts or turns into a non-healing sore; looks clearly different from the other moles on the body (the “ugly duckling” sign); or is a new mole appearing especially after the age of 50. These findings do not always mean melanoma, but they do call for detailed assessment.

Dermoscopy and digital mole mapping are today among the most valuable methods for the early diagnosis of moles. Dermoscopy examines mole structures invisible to the naked eye in detail and identifies the risks they carry. With digital mole mapping, all moles are photographed and recorded, their locations documented, and changes in existing moles as well as newly appearing moles can be compared with previous check-ups. This allows suspicious lesions to be detected early, high-risk moles to be selected for surgical removal, and unnecessary surgical procedures to be avoided.

In melanoma, the most effective treatment is early diagnosis. Regularly monitoring changes in moles and assessing risky lesions in good time can be life-saving.