Most melanomas are picked up because they look different from a person's other moles, or because an existing mole starts to change. The features to look for are often summarised as the "ABCDE" rule:
Just as important is the "ugly duckling" sign — a spot that looks noticeably different from a person's other moles is often the one worth having checked, even if it doesn't clearly fit the ABCDE criteria.
Treatment depends heavily on the stage at diagnosis:
Your treatment plan will be developed based on your specific stage, and for more advanced melanoma, is generally coordinated with a broader specialist team.
Melanoma develops when melanocytes — the pigment-producing cells in the skin — grow in an uncontrolled, cancerous way. It most often develops in an existing mole or as a new pigmented spot, though it can occasionally arise in skin that isn't pigmented, including under nails or in areas not typically exposed to the sun. Unlike basal cell or squamous cell carcinoma, melanoma has a much greater capacity to spread (metastasise) to lymph nodes and other organs, which is why early detection is so central to melanoma care.
If a spot looks suspicious, the next step is a biopsy, where all or part of the lesion is removed and examined under a microscope. This confirms the diagnosis and measures the Breslow thickness — how deeply the melanoma has grown into the skin — which is the single most important factor in determining prognosis and next steps.
Based on thickness and other features such as ulceration, melanomas are broadly categorised as thin, intermediate, or thick, and staged using a system that also accounts for whether there's any spread to lymph nodes or elsewhere in the body. For melanomas of intermediate thickness, or thinner melanomas with certain high-risk features, a sentinel lymph node biopsy may be recommended — a procedure that identifies and samples the first lymph node the melanoma would be likely to spread to, helping guide further treatment decisions.
The major driver of melanoma is UV radiation damage to the DNA of melanocytes, most often from cumulative sun exposure and episodes of sunburn, along with the use of solariums or tanning beds. Risk factors include: