Suspicious Moles: The Warning Signs That Should Prompt a Skin Cancer Check

What matters more is whether a mole is new, changing or behaving differently from the others on your skin.

Melanoma can sometimes develop within an existing mole, but it can also appear as a completely new mark. Early changes may be subtle rather than dramatic, which is why knowing what is normal for your own skin can help.

A suspicious mole does not automatically mean melanoma. It does mean that certain changes deserve proper assessment rather than being watched indefinitely at home.

When Does a Mole Need a Skin Cancer Check?

A mole should be assessed if it changes in size, shape or colour, particularly if the change continues over time. New or unusual marks that do not disappear should also be checked.

Other reasons to seek assessment include a mole that becomes itchy, painful, inflamed, crusted or starts bleeding without an obvious explanation.

The important point is change. A mole that has looked the same for many years is generally less concerning than one that begins to evolve, although appearance alone cannot confirm whether a lesion is benign or malignant.

If skin cancer is eventually confirmed, the diagnosis, type and extent of the disease are used to determine an appropriate skin cancer treatment plan. This comes after proper assessment of the suspicious lesion, not from appearance alone.

The ABCDE Signs of Melanoma

The ABCDE approach provides a practical way to remember some of the features that can make a pigmented lesion more suspicious.

A – Asymmetry

One half of the mole looks different from the other rather than having a relatively even, symmetrical shape.

B – Border

The edges may become irregular, blurred, ragged or poorly defined instead of remaining smooth.

C – Colour

There may be uneven pigmentation or several colours within the same lesion. A mole may contain different shades of brown or black, and melanoma can sometimes include red, pink, white or other colour changes.

D – Diameter

A diameter greater than around 6 mm can be a warning feature, but size should never be used as a rule on its own. Melanomas can be smaller than this.

E – Evolution

Evolution is particularly important. Any continuing change in size, shape, colour, elevation or symptoms deserves attention.

The ABCDE pattern is useful, but it is not a diagnostic test. A mole does not need to satisfy every letter to warrant assessment, and melanoma does not always have the classic appearance people expect.

Sometimes the Clue Is That One Mole Looks Different

Not every suspicious lesion fits neatly into an ABCDE checklist.

Another useful principle is the "ugly duckling" sign. Most of a person's moles often share certain characteristics, such as similar colouring, size or shape. A lesion that looks noticeably different from that person's usual pattern can therefore attract attention even when it does not appear obviously abnormal in isolation.

This is one reason becoming familiar with your own skin can be more useful than trying to memorise an image of what melanoma is "supposed" to look like.

A new dark lesion among predominantly pale moles, for example, or a raised lesion among otherwise flat moles may be worth checking because it breaks the person's usual pattern.

Bleeding, Itching and Crusting Can Matter Too

Melanoma is not always painful. In fact, relying on pain as a warning sign could mean overlooking an important visual change.

A mole may instead begin to itch, feel tender, become inflamed, bleed or develop a crust. These symptoms can have harmless explanations, particularly if a mole has been rubbed or injured, but persistent or unexplained changes should be assessed.

Other skin cancer symptoms can include sores that do not heal, repeatedly crust or bleed, as well as unusual-looking patches of skin. This is important because not every skin cancer presents as a mole.

That distinction matters. Basal cell carcinoma and squamous cell carcinoma often look quite different from melanoma.

Melanoma Is Not Always Dark Brown or Black

It is easy to associate melanoma exclusively with a very dark mole. In reality, appearances vary.

Some melanomas contain several shades of pigment, while amelanotic melanoma may have little obvious dark pigmentation and can appear pink, red or relatively pale.

Melanoma can also develop in places people may not routinely inspect, including the scalp, soles of the feet, palms and beneath the nails.

A persistent dark area beneath a nail that cannot be explained by an injury is one example of a change that should be assessed.

There are also several biological types of skin cancer, and their appearances and behaviour are not identical. This is why a visual checklist can help identify concerning changes but cannot establish the diagnosis.

What Happens When a Suspicious Mole Is Checked?

The first step is usually clinical assessment rather than cancer treatment.

A GP may examine the lesion and, where appropriate, refer you to a dermatologist or specialist skin cancer service. Dermoscopy may be used to examine structures and pigmentation within the lesion that are not as easily assessed with the naked eye.

If melanoma is suspected, the lesion will usually be removed by excision biopsy and examined under a microscope. This confirms the diagnosis and, if melanoma is present, provides important information about features such as tumour thickness.

This distinction is important because an unusual-looking mole is not automatically melanoma. Diagnosis depends on appropriate clinical and pathological assessment.

Why Finding Melanoma Early Matters

Melanoma has the potential to spread beyond the skin, but its behaviour varies considerably.

An important feature after diagnosis is how deeply the melanoma has grown into the skin. Breslow thickness is used to measure this depth and contributes to staging and decisions about whether further investigation or treatment may be required.

This helps explain why an evolving mole should not simply be ignored because it is small or painless. The visible diameter of a lesion is not the same as its depth beneath the skin.

There is also no single predictable timeline for progression. Some melanomas change slowly, while others can behave more aggressively.

The aim of early assessment is not to create anxiety around every mole. It is to identify the relatively small number of concerning lesions before they have an opportunity to become more advanced.

A Skin Check Should Go Beyond the Obvious Places

Checking your skin occasionally can make it easier to recognise change.

That includes areas that are easy to overlook, such as the scalp, back, backs of the legs, soles of the feet, between the toes and around the nails. A mirror can help with areas that are difficult to see, or another person can help check the back and scalp.

People with many moles may find photographs useful for noticing whether a particular lesion has changed over time. Those at increased risk may also be advised to have professional skin surveillance.

Prevention remains important alongside checking for changes. Consistent sun protection, avoiding sunburn and avoiding sunbeds can reduce unnecessary ultraviolet exposure.

Practical steps for skin cancer prevention are especially relevant for people with significant previous sun exposure or other risk factors.

What If a Mole Turns Out to Be Melanoma?

If melanoma is confirmed, the next steps depend on features such as its thickness, ulceration, and whether there is evidence that it has spread.

Surgery is the main treatment for early melanoma. Further management may be considered based on stage and individual risk of recurrence.

More advanced melanoma may require systemic treatments such as immunotherapy or targeted therapy, and radiotherapy can also have a role in selected situations.

The treatment pathway therefore changes considerably once melanoma has been confirmed. At that point, decisions are no longer based simply on what the mole looked like. Pathology, staging and the individual characteristics of the cancer become much more important.

When Another Oncology Opinion Can Be Useful

A changing mole that has not yet been diagnosed should first be assessed through an appropriate GP or dermatology pathway.

Once melanoma or another skin cancer has been confirmed, however, there may be situations where you want greater clarity about the proposed treatment, particularly if the disease is higher risk, has returned or requires additional treatment beyond surgery.

A second opinion can provide an independent review of an established diagnosis, pathology and proposed oncology treatment plan.

For patients considering specialist private care after diagnosis, a private oncology consultant can also help explain how the characteristics and stage of the cancer influence the options available.

The Change Is Often More Important Than the Mole Itself

Most moles never become cancerous, so the aim is not to worry about every mark on your skin.

Instead, pay attention to what changes.

A mole that becomes asymmetrical, develops an irregular border, changes colour or continues evolving deserves assessment. So does a new lesion that looks distinctly different from your other moles or begins bleeding, itching or crusting without a clear explanation.

The ABCDE rule provides a useful starting point, but it shouldn't be a reason to ignore a lesion that doesn't meet every criterion. If something on your skin is new, changing or persistently unusual, having it properly checked is the safest way to establish what it is.

About Dr James Wilson

Once melanoma or another skin cancer has been confirmed, understanding exactly what the diagnosis means can make the next treatment decisions easier to navigate.

Dr James Wilson is a consultant clinical oncologist in full-time private practice in Central London, specialising in melanoma, skin cancer and advanced radiotherapy. He takes a clear, patient-focused approach to oncology care, helping patients make sense of their diagnosis, understand the options available and feel more confident about the treatment decisions ahead.