What should you know about melanoma development?

Melanoma starts in melanocytes, the cells that make skin pigment. Changes in these cells can allow them to multiply and grow beyond their usual boundaries. Sun and ultraviolet exposure can contribute to skin-cell damage, while inherited traits, many moles, and a previous melanoma can also influence personal risk. A person may develop melanoma on skin that has not previously held a mole.

The visible clue may be evolution: a spot changes in outline, shade, size, surface, or sensation. These features are prompts for examination, not a diagnosis. A clinician may use dermoscopy and remove all or part of the lesion so a pathologist can assess the cells.

Check your skin in good light, including the scalp, soles, between the toes, and areas covered by clothing. Use photographs to compare a mark over time, and ask someone you trust to check hard-to-see areas. Arrange a clinical examination for a spot that is new, unlike your other marks, or changing. Information about [Melanoma](/conditions/melanoma/) can help you prepare for that visit.

Protect exposed skin with shade, clothing, and sunscreen used as directed. Do not rely on protection to explain away a changing lesion, and do not remove a suspicious mark at home. If examination confirms melanoma, the team may discuss [Surgical Excision](/treatments/surgical-dermatology/excisional-surgery/) and further staging.

Book prompt medical review when a mole becomes asymmetric, develops an irregular edge, gains several colours, enlarges, or starts bleeding, crusting, itching, or hurting. After a melanoma diagnosis, report a new lump, persistent unexplained pain, or a new neurological symptom to the treating team. Sudden weakness, fainting, or trouble breathing requires emergency care.

Ask whether the lesion needs dermoscopy, biopsy, or complete removal; what the pathology report will measure; and whether a [Sentinel Lymph Node Biopsy](/treatments/diagnostics-and-staging/sentinel-lymph-node-biopsy/) is relevant. Ask how often your skin should be checked and which relatives, if any, should discuss their own risk with a clinician.