Tests to check your lymph nodes

The most common place for melanoma cells to spread is to the lymph nodes closest to the melanoma. Your specialist will examine these nodes to see if they look or feel swollen.

You may also have some tests to check whether any lymph nodes are affected by melanoma. These tests include:

  • A sentinel lymph node biopsy (SLNB) – this removes your sentinel lymph nodes. If there is no melanoma found in the sentinel lymph nodes, then it is unlikely that it has spread.
  • An ultrasound – this uses sound waves to make up a picture of part of your body.
  • A fine needle aspiration (FNA) – this withdraws some sample cells from your lymph nodes with a fine needle.

If melanoma cells are found in your lymph nodes, you may have other tests to see if it has spread elsewhere in the body. These might include CT, MRI or PET scans.

Waiting for your test results can be difficult. It can help to talk about your worries with someone close to you.

The lymphatic system

The lymphatic system

The lymphatic system helps to protect us from infection and disease. It also drains lymph fluid from the tissues of the body before returning it to the blood. The lymphatic system is made up of fine tubes called lymphatic vessels that connect to groups of lymph nodes throughout the body.

Lymph nodes (sometimes called lymph glands) are small and bean-shaped. They filter bacteria (germs) and disease from the lymph fluid. When you have an infection lymph nodes often swell as they fight the infection.

The lymphatic system 

The lymphatic system
The lymphatic system

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Tests to check your lymph nodes

The most common place for melanoma cells to spread is to the lymph nodes closest to the melanoma. Your doctor will examine these nodes to see if they look or feel swollen. For example, if the melanoma is on your leg they will examine the lymph nodes behind your knee and in your groin. If it is on your chest, back or tummy (abdomen), they will check the lymph nodes in your groin and armpits, above the collar bones, and in the neck.

Having swollen lymph nodes does not necessarily mean that the melanoma has spread. For example, an infection can also cause lymph nodes to swell.

Your doctor may suggest that you have some tests to check whether any lymph nodes are affected by melanoma. Not everyone needs these tests. Whether you have the tests will depend on the size of the melanoma, and if the lymph nodes look or feel swollen. These tests include:

  • A sentinel lymph node biopsy (SLNB) – this removes your sentinel lymph nodes. If there is no melanoma found in the sentinel lymph nodes, then it is unlikely that it has spread.
  • An ultrasound – this uses sound waves to make up a picture of part of your body.
  • A fine needle aspiration (FNA) – this withdraws some sample cells from your lymph nodes with a fine needle.

If your tests show that the melanoma has spread to the lymph nodes, you may be advised to have surgery to remove all the lymph nodes in that area.


Sentinel lymph node biopsy (SLNB)

You may be offered a test called a sentinel lymph node biopsy (SLNB). This may be done even if the lymph nodes are not swollen. It is a small operation that is done under a general anaesthetic, at the same time as your wide local excision.

The sentinel nodes are the first ones that lymph fluid drains to from your melanoma. If the melanoma has spread to nearby nodes, the sentinel nodes are the ones that are most likely to be affected.

An SLNB can tell your doctors more about your situation and help them plan the best treatment for you. It is not a treatment itself.

If the sentinel nodes do not contain cancer cells, it is unlikely that other lymph nodes are affected. This means you will not need to have surgery to remove them.

If they do contain cancer cells, your doctor may recommend that you have further surgery to remove all the lymph nodes near to your melanoma.

There are still some questions about how worthwhile having an SLNB is. Your doctor will talk to you about whether an SLNB is suitable for you. They will help you decide whether to have the test or not.

Having a sentinel lymph node biopsy

A doctor will inject a tiny amount of a mildly radioactive liquid around the area of your melanoma (see below). This is the same area where you had your excision biopsy. The liquid will make the sentinel lymph nodes mildly radioactive.

Step 1: Radioactive liquid is injected
Step 1: Radioactive liquid is injected

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During the wide local excision, the surgeon injects a blue dye into the same area as the radioactive liquid. The dye stains the sentinel lymph nodes blue so the surgeon can see them (see below).

Step 2: Blue dye is injected
Step 2: Blue dye is injected

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The surgeon will use a probe that detects radioactivity to help them find the sentinel lymph nodes. The sentinel nodes are then removed (see below). They are sent to a laboratory and examined under a microscope to see if they contain melanoma cells.

Step 3: The sentinel lymph nodes are removed
Step 3: The sentinel lymph nodes are removed

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Ultrasound and fine needle aspiration (FNA)

Your specialist may suggest that you have an ultrasound to check your lymph nodes. If any of the nodes look abnormal, they may suggest you have a fine needle aspiration.

Ultrasound

Ultrasound uses sound waves to make up a picture of a particular area of the body. It is a painless test and only takes a few minutes.

Once you are in a comfortable position, you will have a gel spread over the area around the lymph nodes that are being examined. A small device like a microphone, which produces sound waves, is then passed over this area. The echoes are converted into a picture by a computer. If the ultrasound of the lymph nodes is abnormal the doctor will do a fine needle aspiration of the node or nodes.

Fine needle aspiration

A fine needle aspiration is a quick, simple test. The doctor puts a fine needle into the lymph node and withdraws a sample of cells into the syringe. The cells are examined under a microscope to see if they contain any cancer cells.

If they do, you may have other tests to see if the melanoma has spread anywhere else in the body. If the melanoma has only spread to nearby lymph nodes, you will be offered surgery to remove all the lymph nodes in that area. Your doctors will discuss this with you. They will also tell you about the benefits and disadvantages of having the nearby lymph nodes removed.


Other tests

If your melanoma has spread to the lymph nodes, you may have other tests to see if it has spread elsewhere in the body.

CT (computerised tomography) scan

A CT scan takes a series of x-rays, which build up a three-dimensional picture of the inside of the body. The scan takes 10–30 minutes and is painless. It uses a small amount of radiation, which is very unlikely to harm you and will not harm anyone you come into contact with. You will be asked not to eat or drink for at least four hours before the scan.

CT scan
CT scan

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You may be given a drink or injection of a dye, which allows particular areas to be seen more clearly. This may make you feel hot all over for a few minutes. It’s important to let your doctor know if you are allergic to iodine or have asthma, because you could have a more serious reaction to the injection.

You’ll probably be able to go home as soon as the scan is over.

MRI scan

This test uses magnetism to build up a detailed picture of areas of your body. The scanner is a powerful magnet so you may be asked to complete and sign a checklist to make sure it's safe for you. The checklist asks about any metal implants you may have, such as a pacemaker, surgical clips, bone pins, etc. You should also tell your doctor if you've ever worked with metal or in the metal industry as very tiny fragments of metal can sometimes lodge in the body. If you do have any metal in your body it's likely that you won't be able to have an MRI scan. In this situation another type of scan can be used.

Before the scan, you'll be asked to remove any metal belongings including jewellery. Some people are given an injection of dye into a vein in the arm, which doesn't usually cause discomfort. This is called a contrast medium and can help the images from the scan to show up more clearly. During the test you'll lie very still on a couch inside a long cylinder (tube) for about 30 minutes. It's painless but can be slightly uncomfortable, and some people feel a bit claustrophobic. It's also noisy, but you'll be given earplugs or headphones. You can hear, and speak to, the person operating the scanner.

PET-CT scan

This is a combination of a CT scan, which takes a series of x-rays to build up a three-dimensional picture, and a positron emission tomography (PET) scan. A PET scan uses low-dose radiation to measure the activity of cells in different parts of the body.

PET-CT scans give more detailed information about the part of the body being scanned. You may have to travel to a specialist centre to have one. You can't eat for six hours before the scan, although you may be able to drink. A mildly radioactive substance is injected into a vein, usually in your arm. The radiation dose used is very small. The scan is done after at least an hour’s wait. It usually takes 30–90 minutes. You should be able to go home after the scan.


Waiting for test results

Waiting for test results can be a difficult time. It may take from a few days to a couple of weeks for the results of your tests to be ready. You may find it helpful to talk with your partner, family or a close friend. Your specialist nurse or one of the organisations listed on our database, can also provide support. You can also talk things over with one of our cancer support specialists on 0808 808 00 00.

Back to Tests and scans

Being diagnosed with melanoma

Your GP will examine you and decide whether to refer you to a hospital specialist for further tests and treatment.