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Skin cancer

Created 1997. Updated by Dr Emily Ryder, Dermatology Registrar, June 2017.


Skin cancer — codes and concepts
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Skin cancer

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What is skin cancer?

Skin cancers are malignant tumours in which there is an uncontrolled proliferation of any one of the many skin cell types, whereas the normal process of regeneration of skin involves replication of the cells in a controlled fashion. Each subtype of skin cancer has unique characteristics.

The most common forms of skin cancer are:

The term non-melanoma skin cancer refers to all types of skin cancer apart from melanoma. BCC and SCC are also called keratinocyte cancer.

Common skin cancers

Early, superficial skin cancers include:

Many different types of less common skin cancer are listed in the related information section at the bottom of this page.

Who gets skin cancer? 

Skin cancer most commonly affects older adults, but it can also affect younger adults, and rarely, children.

  • Skin cancer tends to affect individuals with fair skin (Fitzpatrick skin phototype I, II and III), although people with darker skin can also develop skin cancer.
  • People who have had skin cancer have an increased risk of developing other skin cancers.
  • A family history of skin cancer also increases risk.  
  • Certain genes such as melanocortin-1 receptor have been identified as carrying an increased risk of skin cancer.

What causes skin cancer?

The common forms of skin cancer listed above are related to exposure to ultraviolet radiation (from sunlight or tanning beds) and the effects of ageing. Other risks include:

Some skin cancers are due to genetic conditions, such as:

What are the clinical features of skin cancer?

Skin cancers generally appear as a progressive lump or nodule, an ulcer, or a changing lesion.  

What are the complications of skin cancer?

Skin cancer can usually be treated and cured before complications occur. Signs of advanced, aggressive, or neglected skin cancer may include:

  • Ulceration
  • Bleeding
  • Local invasion and destruction of adjacent tissues and structures
  • Distant spread of a tumour to lymph glands and other organs such as liver and brain (metastasis). 

How is skin cancer diagnosed?

Skin cancers are generally diagnosed clinically by a dermatologist or family doctor, when learning of an enlarging, crusting, or bleeding lesion.  The lesion will be inspected carefully, and ideally, a full skin examination will also be conducted.

  • Dermoscopy (using a special magnifying light) may be used to confirm the diagnosis, to detect early skin cancers, and to exclude benign lesions.
  • A partial skin biopsy may be taken in cases of suspected non-melanoma skin cancer to confirm the diagnosis or determine a subtype which may influence treatment.
  • Complete excision is usually undertaken to make a diagnosis if melanoma is suspected, as a partial biopsy can be misleading in melanocytic tumours.
  • The diagnosis is confirmed in the laboratory by a histopathologist. It can take a few days for the report to be issued, or longer if special tests are required.
  • Genetic testing for melanoma and blood-based melanoma detection may be available in some centres.
  • Further investigations may be required if there is a suspicion spread has occurred.

What is the differential diagnosis of skin cancer?

The differential diagnosis of skin cancer depends on the specific lesion.  

What is the treatment for skin cancer?

Early treatment of skin cancer usually cures it. The majority of skin cancers are treated surgically, using a local anaesthetic to numb the skin. Surgical techniques include:

Treatment options for superficial skin cancers include:

Treatment for advanced or metastatic basal cell carcinoma may include targeted therapies vismodegib and sonidegib.

Treatment for advanced and metastatic melanoma may include:

Patients with skin cancer may be at increased risk of developing other skin cancers. They may be advised to:

  • Practice careful sun protection, including the regular application of sunscreens
  • Learn and practice self-skin examination
  • Have regular skin checks
  • Photographic surveillance
  • Undergo digital dermoscopic surveillance (mole mapping), especially if they have many moles or atypical moles 
  • Seek medical attention if they notice any changing or enlarging skin lesions
  • Take nicotinamide (vitamin B3) or acitretin (off-label) to reduce the numbers of squamous cell carcinomas.  

These treatments can lead to adverse effects. See:

What is the outcome of skin cancer?

Most skin cancer can be completely cured with early treatment. Advanced skin cancers are more difficult to treat and can lead to death. 

See smartphone apps to check your skin.
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Related information

 

On DermNet NZ

Other websites

Books about skin diseases

miiskin 3 2 133

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Skin cancer

App to facilitate skin self-examination and early detectionRead more.

Text: Miiskin

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