Skin cancers arise when cells in the skin acquire changes that let them grow unchecked, and they are divided into melanoma, which begins in pigment-producing cells, and the more common non-melanoma types. Assessment is a clinical task: what a page can usefully do is explain the terms and point to the published guidance.
What is actually happening in the skin?
Cells in the epidermis divide constantly, and division carries a small chance of error. Ultraviolet radiation increases that chance considerably, because it damages the genetic material inside cells directly. Most such damage is repaired, and most damaged cells that cannot be repaired are removed. Cancer arises where a cell accumulates changes that let it continue growing without those controls.
Which cell it started in determines what it is called. Melanoma begins in melanocytes, the pigment-producing cells sitting along the base of the epidermis. The non-melanoma cancers, which are considerably more common than melanoma, begin in the keratinocytes that make up the bulk of the epidermis; basal cell and squamous cell carcinoma are the two principal types, named after where in that layer their cells of origin sit.
That distinction is not pedantry. Melanoma and the non-melanoma types behave differently, they are assessed differently, and treating skin cancer as a single entity leads people to apply what they have read about one to something entirely different.
Ultraviolet exposure across a lifetime is the most discussed contributing factor for melanoma, alongside skin that burns readily, family history, and a large number of moles. None of these determines anything in an individual case, and skin cancers also occur at sites that see very little sun.
How would a dermatologist describe it?
A lesion is any localised area of change, and it is deliberately neutral: using it implies nothing about what something is. Benign and malignant describe behaviour rather than appearance. Melanocytic means arising from pigment cells.
Excision means removing a lesion; a biopsy means taking tissue for examination under a microscope, which is how a question about melanoma is settled definitively. Histology is the examination itself, and histopathology is the report that results. A margin refers to the border of normal tissue removed around a lesion.
Clinicians describe what they see using the same vocabulary of pattern, border, colour variation and change over time that they apply to any pigmented area, and the dermatoscope is central to that assessment.
The published criteria that set out which features and changes should prompt an appointment are maintained by the health bodies that issue them. They are precisely worded, they are revised, and they are linked below rather than reproduced here. Paraphrasing a diagnostic checklist is a reliable way of changing its meaning while appearing to preserve it, and on this subject that is not a risk worth taking for the sake of convenience.
What usually happens at a consultation?
The history covers the lesion itself and its timeline, then your sun exposure over a lifetime, sunburn, sunbed use, occupation, family history including melanoma in relatives, and any previous skin cancers or removals.
The examination is generally of your whole skin, with a dermatoscope, and it extends to places you had not considered: the scalp, between the toes, the soles, under the nails. Photographs may be taken for comparison.
Where a lesion needs more than looking, the clinician explains what they propose. Referral pathways exist for lesions requiring prompt specialist assessment, and how those operate is set nationally rather than by the clinic. The practical questions worth asking at that moment are what happens next, when, and who tells you the result.
Waiting for a result is genuinely difficult, and it is worth asking at the outset how long it usually takes and who to contact if that period passes. Knowing the answer does not shorten the wait, but it removes the second layer of uncertainty about whether anything has gone astray.
What is worth asking?
Ask what the clinician saw and what made them decide as they did. Whether the outcome is reassurance or a further step, the reasoning is what lets you interpret anything that changes afterwards.
Ask what would bring you back sooner. This is the most useful single question on the page, because it converts an open-ended instruction to keep an eye on things into something you can actually act on.
Where something is being arranged, establish the timescale and the point of contact. This is consistently where people fall through gaps, and closing it takes one sentence.
If sun protection is discussed, ask what applies to you specifically rather than in general. Advice here depends on your skin, your circumstances and where you are, and a clinician can be concrete about it in a way that no general page can.
What this page does not do
It does not describe how to identify a melanoma or any other skin cancer, does not offer a checklist, and does not interpret anything on your skin. That is a deliberate limit rather than an omission: self-assessment against a description is unreliable in both directions, and the published criteria exist, are maintained, and are linked below so they can be read as their authors wrote them. This page names no treatment and carries no commercial content of any kind.
Common questions
What is the difference between melanoma and non-melanoma skin cancer?
They begin in different cells. Melanoma arises from melanocytes, the pigment-producing cells, while the non-melanoma types arise from keratinocytes, the structural cells of the epidermis. They behave differently, are assessed differently, and grouping them as one thing obscures more than it explains.
Where should I look for the published signs to watch for?
At the source. The NHS sets out what should prompt an appointment, and reading it there rather than through a summary matters, because these criteria are stated precisely and small changes in wording alter what they mean. The link is in the sources below.
Can skin cancer appear where the sun does not reach?
Yes. While ultraviolet exposure is the most discussed factor, skin cancers can occur on areas that are rarely exposed, including the soles of the feet and under the nails. That is one of several reasons a clinician examines more of your skin than you expected.
What happens if a clinician wants to remove something?
They will explain what they propose and why. Removing a lesion so it can be examined properly is a routine step taken because appearance has limits, not because a conclusion has been reached. Asking what the procedure involves and when the result arrives is entirely reasonable.
Does darker skin mean skin cancer is not a consideration?
No. Skin cancers occur across all skin tones, and they have historically been recognised later in people with darker skin, partly because the classic descriptions were written around lighter skin. Any new or changing mark is worth an appointment regardless of skin tone.
Sources
- Symptoms of melanoma skin cancer — NHS (United Kingdom) · accessed
- Melanoma skin cancer — conditions — NHS (United Kingdom) · accessed
Last updated . How this page was written.