Overview of skin cancer

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Last reviewed: 31 Jul 2025

Last updated: 27 Aug 2025

This page compiles our content related to skin cancer. For further information on diagnosis and treatment, follow the links below to our full BMJ Best Practice topics on the relevant conditions and symptoms.

Skin cancer is one of the most common types of cancer worldwide.[1] Possible risk factors include exposure to sunlight or ultraviolet (UV) radiation (e.g., tanning beds), other environmental exposures (e.g., arsenic), viral infection (e.g., HPV), fair skin type, presence of large numbers or certain types of naevi (moles), immunosuppression, certain genetic conditions (e.g., xeroderma pigmentosum), and family history of skin cancer.[2][3][4]

Condition	Description
Merkel cell carcinoma	go to our full topic on Merkel cell carcinoma Merkel cell carcinoma is a rare, aggressive cutaneous neuroendocrine neoplasm that primarily affects white adults. Incidence increases with age and is highest among those aged >85 years.[5] Two distinct aetiologies are recognised: exposure to UV radiation and oncogenic transformation by Merkel cell polyomavirus. Key risk factors are advancing age, immunosuppression, and light skin type. Diagnosis is confirmed with skin biopsy and histopathological evaluation including immunohistochemistry. Occult metastasis is common, and sentinel lymph node biopsy and imaging are important tools for staging the disease. The tumour typically presents as an asymptomatic, rapidly growing, pink-to-violaceous or skin-coloured dermal or subcutaneous nodule.[6]
Basal cell carcinoma	go to our full topic on Basal cell carcinoma The most prevalent malignancy of the skin in fair-skinned adults in the world.[7][8] CRUK Cancer incidence statistics Opens in new window It typically presents as pearly papules and/or firm plaques; non-healing scabs; small crusts and non-healing wounds; plaques, nodules, and tumours with rolled borders; and/or papules with associated telangiectasias.[9][10][Figure caption and citation for the preceding image starts]: Nodular basal cell carcinoma on the cheek, on background of diffuse solar damage with marked solar elastosisFrom the collection of Dr Robert A. Schwartz [Citation ends]. Strong risk factors include UV radiation via frequent sun exposure, x-ray exposure, arsenic exposure, xeroderma pigmentosum, nevoid basal cell carcinoma (Gorlin-Goltz syndrome), and history of transplantation. Metastases and advanced lesions are uncommon. Diagnosis is histological.
Squamous cell carcinoma (SCC)	go to our full topic on Squamous cell carcinoma (SCC) SCC is the proliferation of atypical, transformed keratinocytes in the skin with malignant behaviour. Ranges from in situ tumours (Bowen's disease) to invasive tumours and metastatic disease. Second most common non-melanoma skin cancer worldwide, secondary to basal cell carcinoma.[8] Patients commonly present with a new or enlarging lesion that they are concerned about, which may be tender or itchy, or a non-healing wound originally caused by some trauma. In situ tumours are typically thin, flesh-coloured to erythematous, scaly or haemorrhagic plaques, while invasive SCC may present as an exophytic tumour or ulcer.[Figure caption and citation for the preceding image starts]: Squamous cell carcinoma on the ear with surrounding actinic damageFrom the collection of Dr Jessica M. Sheehan and Dr Keyoumars Soltani [Citation ends]. Tumours may be friable and bleed easily and are located mostly on sun-exposed areas of skin, such as the head and neck (84%) and extensor upper extremities (13%).[11] Cumulative UV exposure and immunosuppression are major risk factors. Presumptive diagnosis of SCC of the skin is usually based on a thorough history and clinical findings; however, skin biopsy confirms the diagnosis.[12]
Melanoma	go to our full topic on Melanoma A malignant tumour arising from pigment-producing melanocytes found in the skin, eye, and central nervous system. Several variants exist. Clinical features of lesion asymmetry, border irregularity, colour variability, diameter >6 mm, and evolution over time should raise suspicion for melanoma and prompt further assessment with dermoscopy.[13][Figure caption and citation for the preceding image starts]: Superficial spreading malignant melanomaFrom the collection of Dr Hobart W. Walling [Citation ends]. Lesions are often on sun-exposed anatomical locations and more often in people with Fitzpatrick type I (white) skin. Lesions are more common on the trunk in men and on the legs and feet in women.[14] Early melanoma may be asymptomatic. History regarding a new or changing pigmented lesion should be obtained.
Kaposi's sarcoma	go to our full topic on Kaposi's sarcoma A low-grade lymphovascular neoplasm associated with human herpesvirus-8 (HHV-8, also known as Kaposi's sarcoma-associated herpesvirus [KSHV]) infection.[15] Lesions frequently involve mucocutaneous sites, but may become more extensive to involve the lymph nodes and visceral organs. Skin lesions evolve from an early patch, to a plaque, and later to ulcerating tumour nodules.[Figure caption and citation for the preceding image starts]: Kaposi sarcoma cutaneous purple-brown plaque on the footFrom the collection of Dr Bruce J. Dezube [Citation ends]. There are four main subtypes: classic (sporadic); endemic (observed in sub-Saharan Africa); HIV-associated (formerly known as epidemic or AIDS-related); iatrogenic (transplant-related). Diagnosis is confirmed by biopsy and histopathology.[16]
Cutaneous T-cell lymphoma	go to our full topic on Cutaneous T-cell lymphoma Heterogeneous group of uncommon disorders characterised by clonal accumulation of T lymphocytes primarily or exclusively in the skin. The incidence of cutaneous T-cell lymphomas has been reported as <10 per 100,000 population globally.[17] While the aetiology remains unclear, theories include causative genomic alterations and infectious agents. Mycosis fungoides and its leukaemic variant, Sézary syndrome, are the most common subtypes.[18] Establishing a diagnosis is often difficult, as the disease can manifest in a number of different ways, including flat patches, raised plaques, large tumours, and/or marked erythroderma (intense and widespread reddening of the skin).[Figure caption and citation for the preceding image starts]: Cutaneous T-cell lymphoma: extensive patch diseaseFrom the collection of the Christie NHS Foundation Trust, Manchester, UK; used with permission [Citation ends]. Diagnosis is based on clinical findings, skin biopsy (specimens should be sent for histology, immunophenotyping, and molecular studies), and laboratory blood tests, and usually requires specialist expertise.[19][20]
Actinic keratosis	go to our full topic on Actinic keratosis Chronic keratotic lesions on adult skin that has been chronically exposed to UV rays. Lesions are skin-coloured, yellowish, or erythematous, ill-defined, irregularly shaped, small, scaly macules or plaques localised in sun-exposed areas of the body (e.g., forehead, lower lip, dorsum of the hands and forearms, bald areas of the scalp, and ears).[Figure caption and citation for the preceding image starts]: Regular actinic keratosisFrom the collection of the Department of Dermatology and Cutaneous Surgery, University of Miami Miller School of Medicine [Citation ends]. Typically, they occur in men aged >40 years with light-coloured skin and a history of chronic sun exposure. Actinic keratosis has the potential to progress into an invasive SCC. The risk of progression to SCC has been calculated to be between 0.025% and 16% per year.[21][22] Although diagnosed clinically, a biopsy may help to rule out SCC.
Sunburn	go to our full topic on Sunburn Sunburn is an acute inflammatory reaction of the skin induced by overexposure to UV radiation. Skin findings include erythema and oedema, with or without vesiculation, followed by desquamation. Key risk factors include Fitzpatrick skin type I-III, photo-sensitising drug, intentional tanning, and lack of or improper use of sunscreen. Symptoms include pain and/or pruritus. Characteristic history and physical examination findings are usually sufficient to make the diagnosis of sunburn. Primary prevention via sun avoidance, physical protection, and the appropriate use of sunscreen is key to preventing the condition, as cellular damage caused by UV radiation is irreversible and may with time increase the risk of skin cancer.

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Overview of skin cancer

Introduction

Relevant conditions