Melanoma tests

If you have any of the symptoms of melanoma, your first step will be to visit your GP, who will take a full medical history and perform a physical examination.

Your doctor may refer you to a specialist for further tests if they suspect a spot on your skin may be melanoma. If the tests show that you have melanoma, the specialist will work out how far it has spread. This is known as staging.

Waiting for the test results can be a stressful time. It may help to talk to a friend, family member or health professional, or to call Cancer Council 13 11 20.


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Physical examination

If you notice any changes to your skin, your doctor will examine you, paying particular attention to any spots you have identified as changed or suspicious. The doctor will ask if you or your family have a history of melanoma.

The doctor may assess the spot using the ‘ABCDE’ criteria:

  • Asymmetry – are the halves of each mole different?
  • Border – are the edges irregular, scalloped or notched?
  • Colour – are there differing shades and colour patches?
  • Diameter – is the spot greater than 6 mm across?
  • Evolving – has the spot changed over time (size, shape, surface, colour, bleeding, itching)?

Some melanomas don’t follow the ‘ABCDE’ criteria, so your doctor may also assess whether the spot is elevated, firm or growing. Your doctor may use a handheld magnifying instrument called a dermascope to see the spot more clearly.


Removing the mole (excision biopsy)

If the doctor suspects that a spot on your skin may be melanoma, the usual procedure is to remove the whole spot (excision biopsy) for examination by a tissue specialist (pathologist). This is generally a simple procedure in your doctor’s office. Your GP may do it, or you may be referred to a dermatologist or surgeon.

You will have an injection of local anaesthetic to numb the area. The doctor will use a scalpel to remove the spot and a narrow margin (2 mm) of healthy tissue around it. The wound will usually be closed with stitches. It is recommended that the entire mole is removed rather than a small sample. This helps ensure an accurate diagnosis and accurate staging of any melanoma found.

A pathologist will examine the tissue under a microscope to determine if it contains melanoma cells. Results are usually ready in about a week, and a follow-up appointment may be arranged to check the wound and remove your stitches. If the mole contains cancerous cells you may need further surgery, such as a wide local excision.


Checking the lymph nodes

Lymph nodes are part of your body’s lymphatic system, which removes excess fluid from tissues, absorbs fatty acids, transports fat, and produces immune cells. There are large groups of lymph nodes in the neck, armpits and groin. Sometimes melanoma can travel through the lymph vessels to other parts of the body.

Your doctor may feel the lymph nodes near the melanoma to see if they are enlarged. This may indicate the cancer has spread to the lymph nodes. To test whether the melanoma has spread, your doctor may recommend that you have a fine needle aspiration biopsy or a sentinel lymph node biopsy.

Fine needle aspiration biopsy

The doctor takes a sample of cells by inserting a thin needle into a suspicious lymph node. Ultrasound is often used to guide the needle to the correct node. The sample is then examined under a microscope to see if it contains cancer cells.

Sentinel lymph node biopsy 

You will have an injection of a small amount of radioactive substance into the area where the melanoma was removed. The lymph node that absorbs the injected fluid first is the sentinel lymph node.

If the cancer has spread, the sentinel node is the most likely node to have cancer within it. The surgeon will remove this node to check for cancer cells and determine whether it’s necessary to remove more lymph nodes. The removal of the sentinel lymph node is usually done under a general anaesthetic at the same time as the wide local excision. Your doctor will talk to you about this type of biopsy, and the associated risks and benefits.

If cancer cells are found in the sentinel lymph node, the remaining nodes in the area may also be removed. This is to treat the cancer locally to try to stop the melanoma coming back in the same area or spreading from the primary site.

The risk of having melanoma in the lymph nodes increases with the thickness of the melanoma and is very low for thin melanomas. For this reason, sentinel node biopsy will usually only be offered to people if the Breslow thickness of their melanoma is over 1 mm.

A sentinel lymph node biopsy can provide information that helps predict the risk of melanoma spreading to other parts of the body. This can help your doctor plan your treatment. It may also allow you to access new clinical trials.

Read more about checking the lymph nodes

Pathology report

If you have melanoma, the pathologist’s report will provide your treatment team with information to help plan treatment and determine your prognosis. The following factors may be included:

Breslow thickness

This is a measure of the thickness of the tumour in millimetres from the epidermis to its deepest point in the skin. The thicker a melanoma, the more likely it will recur or spread to other parts of the body.

Melanomas are classified as:

  • in situ – found only in the outer layer of the skin
  • thin – less than 1 mm
  • intermediate – 1– 4 mm
  • thick – greater than 4 mm.

Clark level 

This describes how many layers of skin the cancer has gone through. It is rated 1–5, with 1 the shallowest and 5 the deepest. Breslow thickness is more important than Clark level in assigning a stage to a melanoma.

Margins 

This is the area of normal skin around the melanoma. If there is no tumour touching the margins, the pathologist will often describe how close the lesion came to the edge.

Mitotic rate

Mitosis is the process by which one cell divides into two. The pathologist counts the number of actively dividing cells (mitoses) to calculate the average number of mitoses per square millimetre.

Ulceration

The breakdown or loss of the outer layer of skin over the tumour is a sign of rapid tumour growth. The pathologist will determine whether ulceration is present.

Regression

The report will note any lymphocytes (immune cells) within the melanoma and any evidence of tumour regression (destruction).

Read more about pathology report

Video: Cancer and common diagnostic tests

Learn more about what cancer is, how it spreads, and what primary and secondary cancers are. You can also find out about the tests that are commonly used to diagnose cancer, including CT/CAT scans, PET scans & MRI scans.


This information was last reviewed in January 2017
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