Skin Cancer: Melanoma and Non-Melanoma Cancers

Skin cancer includes several diseases arising from different skin cells. Melanoma is less common but has greater potential to spread, while basal cell and squamous cell carcinomas usually behave differently. Early assessment, biopsy and complete removal provide the best chance of straightforward treatment.

What skin cancer is Skin cancer develops when abnormal skin cells grow without normal control. The main groups are melanoma and non melanoma skin cancer. Non melanoma skin cancer mainly includes basal cell carcinoma, called BCC, and cutaneous squamous cell carcinoma, called SCC. These cancers arise from different cells and have different risks of local damage, recurrence and distant spread. Skin has several cell types The epidermis is the outer layer of skin. Keratinocytes form most of this layer and help create a protective barrier. Basal cells sit near the bottom of the epidermis. BCC develops from cells with basal cell features. Squamous cells are flatter cells nearer the skin surface. Cutaneous SCC develops from keratinocytes with squamous features. Melanocytes produce melanin, the pigment that helps protect skin from ultraviolet radiation. Melanoma develops from melanocytes. Melanoma Melanoma is a cancer of melanocytes. It may begin within an existing mole, but many melanomas arise as a new skin lesion. Melanoma can grow downwards into deeper skin, enter lymphatic channels or blood vessels and spread to lymph nodes or distant organs. Its greater metastatic potential makes prompt recognition and specialist assessment particularly important. Early melanoma is often cured by surgery. Basal cell carcinoma BCC is the most common skin cancer. It usually grows slowly and damages surrounding tissue rather than spreading to distant organs. Untreated BCC can ulcerate and invade cartilage, bone or other nearby structures. This is especially important on the eyelids, nose, ears, lips and other functionally sensitive sites. Distant spread from BCC is extremely rare. Cutaneous squamous cell carcinoma Cutaneous SCC develops from keratinocytes within the skin. Most SCCs are cured with local treatment. SCC has a greater risk of lymph node or distant spread than BCC, although this remains uncommon overall. Risk rises with features such as greater thickness, poor differentiation, nerve involvement, recurrence, immunosuppression and certain anatomical sites. This metastatic potential explains why suspected SCC follows an urgent suspected cancer pathway. Non melanoma does not mean harmless The label non melanoma groups together cancers that differ from melanoma. It does not mean that BCC or SCC should be ignored. BCC can cause substantial local destruction when treatment is delayed. SCC can grow rapidly, invade nerves and occasionally spread. The term describes a category, not a guarantee of minor disease. Why melanoma has different urgency Melanoma can spread while the primary skin lesion is still relatively small. The risk rises as the tumour grows deeper into the skin. Prompt excision allows accurate measurement and may prevent further progression. BCC usually grows more slowly and rarely metastasises. SCC sits between these patterns. It is usually curable but has enough metastatic risk to require urgent referral when suspected. Ultraviolet radiation Ultraviolet radiation, usually shortened to UV, is the dominant modifiable risk factor for melanoma, BCC and SCC. UV reaches skin through sunlight and artificial tanning devices such as sunbeds. It damages DNA within skin cells. Repeated damage can accumulate until growth control systems fail. No suntan is required for UV damage to occur. Sunburn and long term exposure Intermittent intense exposure and sunburn are strongly associated with melanoma and many BCCs. Long term cumulative exposure is particularly important for SCC and also contributes to BCC. Outdoor work, outdoor recreation and repeated holidays in strong sunlight can all add exposure. Childhood and adolescent sunburn matters, but protection remains beneficial at every age. Sunbeds Sunbeds expose skin to concentrated UV radiation. They increase the risk of melanoma and non melanoma skin cancer. A tan from a sunbed is a sign of skin responding to injury rather than becoming protected. Sunbeds are not a safe way to prepare skin for a holiday. Skin tone and risk People with lighter skin that burns easily have a higher average UV related skin cancer risk. Red or fair hair, light eyes, freckles and difficulty tanning can accompany this risk. However, people with brown or black skin can also develop melanoma, BCC and SCC. Lower population risk must not become delayed assessment. Skin cancer may be harder to recognise when teaching images show only white skin. Melanoma in darker skin In darker skin, melanoma has a greater relative tendency to occur on the palms, soles or beneath nails. This pattern is called acral melanoma. Acral melanoma is not thought to be driven by UV exposure in the same way as many other melanomas. A new or changing dark patch on a palm, sole or nail still needs assessment. Melanoma can also occur on any other skin site. Other melanoma risk factors Risk is higher in people with many moles or unusual moles. A personal or close melanoma also increases risk in the family. Inherited variants can contribute in some families. Immune suppression, increasing age and previous melanoma are relevant. Most people with one risk factor never develop melanoma, and some people develop it without an obvious risk factor. BCC and SCC risk factors Previous BCC or SCC increases the chance of another skin cancer. Immune suppression after organ transplantation or through particular medicines strongly increases SCC risk. Chronic scars, burns, ulcers and areas of previous radiotherapy can occasionally develop SCC. Arsenic exposure and rare inherited conditions can contribute. These factors affect clinical suspicion and follow up. Actinic keratosis and Bowen disease Actinic keratoses are rough sun damaged patches caused by abnormal keratinocytes. Most do not become invasive cancer, but some can progress to SCC. Bowen disease is SCC in situ. The abnormal cells remain within the epidermis. These conditions require assessment and treatment according to their extent and risk. They are not melanoma. Moles are usually benign A mole is a benign collection of melanocytes. Normal moles can be flat or raised and vary from skin coloured to dark brown. They often appear during childhood or early adult life. Pregnancy and hormonal changes can alter several moles together. A single lesion changing differently from the others is more concerning than stable lifelong variation. The ABCDE criteria ABCDE is a public prompt for noticing features that deserve assessment. A means asymmetry. B means an irregular border. C means varied or changing colour. D refers to diameter, often taught as greater than about 6 millimetres. E means evolution, which includes change in size, shape, colour, surface or sensation. ABCDE is not a diagnostic test. A means asymmetry A symmetrical mole has broadly similar halves. Melanoma may grow unevenly so that one half differs from the other. Many benign moles are not perfectly symmetrical. Some melanomas are relatively symmetrical. Asymmetry should therefore prompt attention rather than provide a diagnosis. B means border Benign moles often have smooth, clear edges. Melanoma can have an irregular, notched, blurred or spreading border. Inflammation, trauma and benign lesions can also alter an edge. A clinician considers the whole lesion and its evolution. C means colour Melanoma can contain several colours, including brown, black, red, pink, blue, grey or white. A dark lesion is not automatically melanoma. Some melanomas are pink, red or skin coloured and contain little visible pigment. Colour difference from a person's other moles can be useful. D means diameter Melanomas are often larger than 6 millimetres when detected. This is approximately the width of a pencil eraser. The measurement is not a safety threshold. Small melanomas occur, and large benign moles also occur. A changing lesion should be assessed even when it remains smaller than 6 millimetres. E means evolution Evolution is often the most useful ABCDE feature. Concern includes a lesion changing in size, shape, colour, height or surface. New itching, tenderness, bleeding, crusting or inflammation can also matter. A new lesion that continues growing deserves assessment. Change should be judged over time rather than after repeatedly picking or squeezing the area. The ugly duckling idea A concerning lesion may look different from a person's other moles. This is sometimes called the ugly duckling sign. It can help someone notice a lesion that does not fit their usual pattern. It is not a formal diagnosis. Some people naturally have varied moles, and melanoma can resemble nearby lesions. ABCDE limitations ABCDE mainly describes common pigmented melanomas. It can miss nodular, amelanotic, nail and acral melanoma. Melanoma can develop without every letter being present. A person should not wait for a lesion to meet several criteria. Any new, persistent or changing unusual mark can justify clinical review. Nodular melanoma Nodular melanoma often grows downwards more quickly than common superficial spreading melanoma. It may appear as a new raised lump that is firm and enlarging. The lesion can be dark, red, pink or skin coloured. It may bleed or crust. Nodular melanoma may not show the classic ABCDE pattern before becoming clinically important. Amelanotic melanoma Amelanotic melanoma contains little visible pigment. It may look pink, red or skin coloured. It can resemble an inflamed spot, scar or non melanoma skin cancer. A persistent growing lesion should not be dismissed because it is not dark. Nail melanoma Melanoma can begin beneath a fingernail or toenail. Possible features include a new widening pigmented band, pigment spreading onto nearby skin or nail destruction. Most dark nail marks have another cause, including trauma, infection or normal pigmentation. A persistent unexplained change requires assessment. Melanoma can occur outside ordinary skin Rare melanomas arise in the eye or within mucosal surfaces such as the mouth, genital region or anus. These are biologically distinct from common sun related skin melanoma. They may not be visible during routine skin checks. Persistent symptoms in these sites require the relevant specialist assessment. Typical BCC appearances BCC may appear as a pearly, shiny or translucent lump. Fine blood vessels can be visible across the surface. A central ulcer can create a raised rolled edge. Some BCCs look like a flat red, brown or scaly patch. They may bleed, crust and appear to heal before breaking down again. Typical SCC appearances SCC often appears as a firm, raised, rough or scaly lesion. It may develop a crust, central keratin plug or ulcer that bleeds. The area can be tender or painful. Some SCCs grow quickly over weeks. Appearance overlaps with benign lesions, actinic keratosis and keratoacanthoma. A sore that does not heal Skin cancer can present as an area that repeatedly scabs, bleeds or fails to heal. Trauma, infection, eczema and poor circulation can cause similar problems. A persistent lesion lasting more than several weeks needs assessment. An ulcer arising within an old scar or chronic wound deserves particular attention. Location matters UV related cancers commonly occur on sun exposed skin. The face, scalp, ears, neck, shoulders, forearms, hands and lower legs are frequent sites. BCC on the central face can threaten the eye, nose or lip through local invasion. SCC on the ear or lip carries greater metastatic risk than many low risk sites. Melanoma can occur on covered skin as well as exposed skin. Checking the whole skin Skin awareness means knowing what is usual for you. Use mirrors or ask someone you trust to check the back, scalp and other hard to see areas. Remember the soles, between toes, palms and nails. Photographs can help compare a specific lesion over time. Home checking does not replace professional assessment of a concerning change. Primary care assessment A clinician asks when the lesion appeared and how it has changed. They review bleeding, itching, pain, previous skin cancer, sun exposure and immune suppression. The whole lesion is examined rather than judging one photograph or one ABCDE feature. Nearby lymph nodes may be checked when melanoma or SCC is suspected. The weighted seven point checklist NICE uses a weighted seven point checklist to guide melanoma referral in primary care. Major features are change in size, irregular shape and irregular colour. Minor features include diameter of at least 7 millimetres, inflammation, oozing and altered sensation. A score of 3 or more supports suspected cancer referral. This professional checklist is not intended as a home self triage score. Referral for suspected melanoma A lesion that meets NICE suspicion criteria follows the suspected cancer pathway. This route is commonly still called the two week wait pathway. Current NHS performance standards focus on confirming or excluding cancer promptly, rather than promising every person an identical appointment date. Urgent referral means melanoma must be assessed. It does not mean melanoma is already diagnosed. Referral for suspected SCC Suspected cutaneous SCC also follows the urgent suspected cancer pathway. This differs from the idea that all non melanoma cancers are referred routinely. SCC is usually curable, but delay can matter because some tumours grow quickly or spread. Immunosuppression, rapid growth, pain, nerve symptoms and high risk sites increase concern. Referral for suspected BCC Most suspected BCCs are referred through a non urgent pathway because they usually grow slowly and rarely spread. A suspected cancer referral is considered when delay could significantly affect outcome. Examples include a large lesion, rapid growth or a lesion threatening the eye, nose, ear or another critical structure. Non urgent does not mean optional. The lesion still needs assessment and treatment. Teledermatology Some services use secure clinical photographs and specialist remote review. This can speed triage and reduce unnecessary hospital visits. Image quality, lighting, scale and symptoms and background matter. A photograph cannot show texture reliably or replace biopsy when tissue diagnosis is needed. People should use the pathway provided rather than sending medical photographs through insecure channels. Dermoscopy Dermoscopy uses a magnifying instrument with specialised lighting to examine structures below the skin surface. It improves assessment of pigmented and non pigmented lesions when used by trained clinicians. Dermoscopy can support suspicion of melanoma, BCC or other diagnoses. It does not provide a microscopic tissue diagnosis. Excision biopsy for suspected melanoma A suspected melanoma is usually removed completely with a narrow clinical margin for diagnosis. This is called an excision biopsy. The approach preserves the lesion's architecture and allows accurate measurement of invasion. A partial biopsy may be used when complete removal would be impractical or highly disfiguring. The specialist selects the method according to site and lesion size. Biopsy for BCC and SCC A small punch, shave or incisional biopsy may sample a larger lesion. A small lesion may be removed completely as an excision biopsy. The tissue is examined to confirm the cancer type and assess high risk features. Biopsy method depends on site, suspected diagnosis and planned treatment. Pathology A pathologist examines the removed tissue under a microscope. For melanoma, the report includes subtype, Breslow thickness, ulceration and whether the edges contain tumour. For SCC, it may include differentiation, thickness, depth, nerve involvement and margins. For BCC, the growth pattern and margins help assess recurrence risk. Pathology provides information that appearance alone cannot establish. Breslow thickness Breslow thickness measures how deeply invasive melanoma cells extend into the skin. It is recorded in millimetres from the top reference point to the deepest melanoma cell. A thicker melanoma has had more opportunity to reach lymphatic channels or blood vessels. Breslow thickness is therefore one of the most important prognostic features of the primary melanoma. It is not the same as the lesion's visible width. Why Breslow thickness matters Breslow thickness helps determine the melanoma's T category. It influences the width of further surgical excision. It also helps decide whether sentinel lymph node biopsy should be discussed. Thickness is considered with ulceration, lymph nodes, distant spread and other pathological features. No single measurement predicts an individual's outcome with certainty. Ulceration Ulceration means the epidermis over the melanoma has been lost because of tumour related change. It is identified microscopically rather than from any ordinary scratch or surface bleeding. Ulceration increases stage and risk within particular thickness groups. A lesion that bleeds is not automatically ulcerated in the pathological sense. Melanoma staging Melanoma uses the TNM system. T incorporates primary tumour thickness and ulceration. N describes spread to regional lymph nodes or nearby skin or lymphatic sites. M describes distant metastases. These components combine into stages 0 to IV. Stage 0 melanoma Stage 0 melanoma is melanoma in situ. Abnormal melanocytes remain within the epidermis. It has not invaded deeper skin and cannot spread in its current in situ form. Complete local treatment prevents progression. Stage I and II melanoma Stage I and II melanomas are invasive but have no confirmed regional lymph node or distant spread. The stage depends largely on Breslow thickness and ulceration. Surgery is the main treatment. Selected people are offered further staging or adjuvant therapy according to risk. Stage III melanoma Stage III melanoma involves regional lymph nodes, nearby skin deposits or in transit lymphatic disease. It represents a broad range of risk. Surgery may remove resectable disease. Adjuvant immunotherapy or BRAF targeted treatment may reduce recurrence risk in selected people. Stage IV melanoma Stage IV melanoma has spread to distant skin, lymph nodes or organs. Treatment is often not curative, but modern systemic therapies can control disease for prolonged periods in some people. The plan may combine systemic treatment, surgery, stereotactic radiotherapy and symptom control. Sentinel lymph node biopsy A sentinel lymph node is the first node expected to drain lymph from the melanoma site. Sentinel lymph node biopsy is a staging procedure rather than treatment for the primary lesion. NICE considers it for melanomas over 1 millimetre thick and for selected thinner melanomas with additional risk features. A negative result lowers the likelihood of regional spread but does not guarantee that recurrence cannot occur. Imaging Very early melanoma does not routinely require body imaging. Scans are selected according to stage, symptoms and treatment planning. CT, MRI or PET CT can investigate suspected regional or distant spread. Unnecessary imaging can identify unrelated abnormalities and create additional uncertainty. BCC rarely needs staging scans unless unusually advanced. Higher risk SCC may require lymph node assessment or imaging. Surgical excision is the main treatment Complete surgical removal is the primary treatment for most melanoma, BCC and SCC. The surgeon removes the cancer with a margin of clinically normal skin. The required margin differs by cancer type, site and pathological risk. Surgery provides both treatment and confirmation that the edges are clear. Wide local excision for melanoma After diagnostic excision confirms melanoma, a wider area around the scar is usually removed. This is called wide local excision. The margin depends on melanoma stage and thickness. The purpose is to remove microscopic cells near the original lesion and reduce local recurrence. A skin graft or flap may be needed when a large area is removed. Standard excision for BCC Most BCCs are treated by standard surgical excision under local anaesthetic. Low risk lesions can often be removed with a relatively small margin. High risk growth patterns, recurrent tumours and difficult sites may require specialist surgery. Incomplete margins may lead to further excision, Mohs surgery or another treatment. Standard excision for SCC Surgery is the recommended treatment for most SCCs. The margin depends on tumour size, site and high risk features. The pathology report confirms whether the tumour is fully removed. High risk SCC may require specialist multidisciplinary review and assessment of regional lymph nodes. Mohs micrographic surgery Mohs surgery removes a skin cancer in carefully mapped stages. Each layer is examined microscopically while the person waits. Further tissue is removed only where cancer remains at an edge. This provides detailed margin control while preserving as much healthy tissue as possible. Mohs is used most often for selected high risk BCCs and for some SCCs. When Mohs may be useful Mohs may be recommended when tumour edges are difficult to see. It is valuable on sites where preserving healthy tissue matters, including eyelids, nose, ears and lips. It may be used for recurrent cancer, incompletely removed disease or an aggressive histological pattern. It is not required for every BCC or SCC. Standard excision remains effective for many lesions. Other treatments for BCC Some superficial low risk BCCs can be treated without ordinary excision. Options can include curettage and cautery, topical imiquimod, topical fluorouracil, photodynamic therapy or radiotherapy. Cryotherapy is used in selected situations. These treatments do not suit every subtype or site and may not provide the same margin information as surgery. Other treatments for SCC Radiotherapy can treat SCC when surgery is unsuitable or would cause unacceptable harm. It can also be used after surgery for selected high risk features. Advanced SCC may require surgery to lymph nodes, radiotherapy or systemic immunotherapy. Topical treatment is not appropriate for ordinary invasive SCC. Radiotherapy Radiotherapy can treat selected melanoma, BCC and SCC situations. It may replace surgery when an operation is unsuitable. It can reduce recurrence risk after treatment of high risk SCC. For advanced melanoma, it can relieve symptoms or control selected metastases, including some brain lesions. Radiotherapy's purpose differs according to cancer type and stage. Immunotherapy for melanoma Immune checkpoint inhibitors reduce signals that prevent immune cells attacking cancer. They are central treatments for unresectable stage III and stage IV melanoma. They can also reduce recurrence risk after removal of selected higher risk melanoma. Possible immune related adverse effects include inflammation of the lungs, bowel, liver, skin, kidneys and hormone producing glands. New symptoms require prompt oncology advice. Targeted treatment for melanoma Some melanomas contain a BRAF V600 alteration that drives cancer growth. BRAF inhibitors are usually combined with MEK inhibitors. This treatment can produce rapid tumour shrinkage in suitable advanced melanoma. It can also be used after surgery in selected higher risk BRAF mutated disease. It does not work when the required BRAF alteration is absent. BRAF testing BRAF is tested in melanoma tissue when the result could affect treatment. A tumour BRAF alteration is usually acquired within cancer cells. It does not automatically mean that the person or relatives inherited a cancer risk variant. The result is separate from Breslow thickness and stage. Advanced BCC and SCC Locally advanced BCC that cannot be treated adequately with surgery or radiotherapy may receive a targeted hedgehog pathway medicine. Advanced cutaneous SCC may receive immune checkpoint treatment. These situations are uncommon compared with localised disease. Treatment decisions require specialist skin cancer multidisciplinary review. Treatment intent Early melanoma, BCC and SCC are usually treated with curative intent. Curative treatment aims to remove or eradicate all known cancer. Advanced melanoma or SCC may receive treatment intended to control disease, relieve symptoms and extend life. Palliative care can support symptoms alongside active anticancer treatment. Treatment side effects Skin surgery causes a scar and can affect nearby nerves, movement or appearance. A graft or flap can change healing and sensation. Radiotherapy can cause skin soreness, pigment change, hair loss and later tissue changes in the treated area. Immunotherapy and targeted medicines can cause systemic adverse effects. The expected benefit must be balanced against these risks. Infection during systemic treatment Immunotherapy does not usually cause neutropenia in the same way as chemotherapy. However, combination treatment, steroids used for toxicity and other anticancer medicines can increase infection risk. Fever, shaking chills or sudden severe illness requires the oncology emergency pathway. A person should carry or show their treatment alert information when seeking care. Follow up after melanoma Melanoma follow up depends on stage and treatment. Review can include skin examination, lymph node assessment and imaging for higher risk stages. People are taught to report new skin lesions, lumps or systemic symptoms between appointments. Follow up also provides psychological support and advice about reducing UV exposure. Follow up after BCC A completely treated low risk BCC may not require long term hospital follow up. The person remains at increased risk of another BCC or another skin cancer. Self awareness and sun protection remain important. Higher risk, recurrent or multiple BCCs may need specialist review. Follow up after SCC Low risk SCC may need little specialist follow up after complete treatment. Higher risk SCC is followed more closely because recurrence and lymph node spread are more likely. Examination includes the treatment site, surrounding skin and relevant lymph nodes. Immune suppressed people often need ongoing skin surveillance. Reducing future UV exposure Use shade and protective clothing as the main defences against strong sunlight. A broad brimmed hat protects the face, ears and neck. UV protective sunglasses protect the eyes and surrounding skin. Avoid deliberate tanning and sunbeds. Children need particular protection from sunburn. Sunscreen Use a broad spectrum sunscreen with high UVB and UVA protection on uncovered skin. Apply enough before exposure and reapply regularly, especially after swimming, sweating or towel drying. Sunscreen does not provide complete protection. It should support clothing and shade rather than extend time in strong sunlight. Vitamin D Avoiding excessive UV exposure can reduce vitamin D production in the skin. People at risk of deficiency may need dietary advice or supplements. Deliberate sunburn or sunbed use is not a safe vitamin D strategy. The GP or pharmacist can advise according to national supplementation guidance. Prognosis differs between cancers Most BCCs are cured and never spread. Most SCCs are also cured, but high risk tumours can recur or metastasise. Thin early melanoma is often cured by surgery. Melanoma prognosis worsens as thickness, ulceration, lymph node involvement or distant spread increases. Population statistics cannot predict exactly what will happen to one person. Emotional and practical effects A visible skin cancer can affect confidence, body image and social interaction. Facial surgery can create concern about scarring or function. Melanoma follow up may create fear of recurrence. Specialist nurses, reconstructive teams and psychological support can help. Concern about appearance should be addressed alongside cancer control. What this lesson should not be used for This lesson cannot diagnose cancer from a photograph, ABCDE feature or online image comparison. It cannot distinguish melanoma, BCC, SCC and benign lesions without professional assessment and sometimes biopsy. Do not cut, burn, freeze or chemically treat an undiagnosed lesion at home. Seek assessment for any new, changing, bleeding or non healing lesion, and use urgent pathways when melanoma or SCC is suspected.

Melanoma, BCC and cutaneous SCC arise from different skin cells and have different behaviour. Melanoma has the greatest metastatic potential, SCC has a smaller but important risk of spread, and BCC usually causes local damage rather than metastasis. ABCDE prompts assessment, while biopsy, Breslow thickness and stage determine the diagnosis and treatment.