Tests to diagnose skin cancer

The main test to diagnose skin cancer is to take a sample (biopsy) of the area.

You need to go to your GP if you are worried about an abnormal area of skin. Your GP might refer you to a specialist if they think you have skin cancer. Or they might do a biopsy themselves if they have had the specialist training.  

Testing for skin cancer

It’s not always possible to tell the difference between skin cancer and non cancerous skin conditions. Your doctor might put some oil on your skin and use a dermatoscope (like a magnifying glass) to examine the area closely.

Below are pictures of dermatoscopes.

Photographs of Dermatoscopes

Your doctor takes a sample of skin to find out if you have skin cancer. You might have local anaesthetic to numb the area first. This can depend on the size of the abnormal area and where it is. They send the sample to the laboratory to be looked at under a microscope.

Types of biopsies

Understanding the results of your biopsy

It takes about 2 to 3 weeks to get the results of your biopsy. You usually go back to your GP or skin specialist (dermatologist) for these.

You need treatment to the area if the skin sample contains any cancerous cells. For example, surgery to remove the area completely, or other treatments such as chemotherapy creams.

You might not need any further treatment if you had an excision biopsy. In the laboratory, the specialist doctor (pathologist) carefully checks the sample under the microscope to make sure there is a border of healthy skin tissue all around it. This is called a healthy margin. You will need more surgery if not enough healthy tissue has been removed. This is important because if any cancer cells are left behind, the cancer can continue to grow.

Last reviewed: 
20 Sep 2019
  • Improving outcomes for people with skin tumours including melanoma: Evidence Update October 2011
    National Institute for Health and Clinical Excellence (NICE), May 2010

  • Skin cancer
    National Institute for Health and Care Excellence, 2016

  • BMJ Best Practice Basal cell carcinoma
    R A Schwartz and others
    BMJ Publishing Group, Updated March 2018

  • BMJ Best Practice Squamous cell carcinoma of the skin
    K Soltani and others
    BMJ Publishing Group, Updated August 2018

  • Skin Biopsy. Biopsy issues in specific diseases.
    D E Elston and others
    Journal of the American Academy of Dermatology, 2016. Volume 74, Issue 1, Pages 1-16

  • The information on this page is based on literature searches and specialist checking. We used many references and there are too many to list here. Please contact patientinformation@cancer.org.uk with details of the particular issue you are interested in if you need additional references for this information. 

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