Sentinel Lymph Node Biopsy – Malignant Melanoma

Patient Experience

  • Reference Number: HEY-259/2023
  • Departments: Plastic Surgery
  • Last Updated: 1 March 2023


This leaflet has been produced to give you general information about sentinel lymph node biopsy.  Most of your questions should be answered by this leaflet.   It is not intended to replace the discussion between you and your doctor, but may act as a starting point for discussion.   If after reading it you have any concerns or require further explanation, please discuss this with a member of the healthcare team caring for you.

What is a sentinel lymph node biopsy and why do I need one?

The doctor has explained that you have had a malignant melanoma removed. A malignant melanoma is a cancerous lesion and there is the potential for this cancer to spread to another area of the body through the lymphatic system. The lymphatic system is made up of vessels (similar to blood vessels) that drain away excess fluid from the body. The system also has lymph nodes, which filter lymph fluid and help fight infection. Large collections of these lymph nodes can be found in armpits, groins and the neck area. One of the places cancer cells could potentially spread to is a lymph node which drains the area the melanoma was removed from. This is called the sentinel node. The sentinel node is located and removed during the operation. This is usually performed at the same time as a wide excision procedure which is an operation performed to reduce the risk of melanoma recurring around the scar.

Sentinel lymph node biopsy is an operation to remove one or more lymph nodes to look for any evidence that cancer cells have spread. The lymph node is then sent away for analysis. Lymph node biopsy is a test that gives information about prognosis (the chance of the melanoma coming back). There is no evidence that this procedure improves overall survival from the disease. As there is no overall survival benefit from the procedure it is always your decision whether to have this procedure done. It is possible to perform the wider excision procedure without performing the sentinel node biopsy.

If you do opt to have a sentinel node procedure and the test results come back positive showing that melanoma cells have been found in the node this puts you in the American Joint Committee on Cancer (AJCC) staging group of stage 3. This could make you eligible for adjuvant treatments. Adjuvant treatments are in addition to the primary (initial) treatment you have had done to reduce the risk of the cancer recurring after surgery. Adjuvant treatment can be given either intravenously (a needle in the arm) every 4-6 weeks for immunotherapy or by taking tablets orally for targeted treatments. Treatment is intended for a year. The type of treatment you have will be dependent on the type of melanoma that you have.

Possible advantages of sentinel lymph node biopsy Possible disadvantages of sentinel lymph node biopsy
The operation helps to find out whether the cancer has spread to the lymph nodes. It is better than ultrasound scans at finding very small cancers in the lymph nodes. The purpose of the operation is not to cure the cancer. There is no good evidence that people who have the operation live longer than people who do not have it.
The operation can help predict what might happen in the future. For example, in people with a primary melanoma that is between 1 and 4mm thick:

  • Around 1 out of 10 die within 10 years if the sentinel lymph node biopsy is negative.
  • Around 3 out of 10 die within 10 years if the sentinel lymph node biopsy is positive.
The result needs to be interpreted with caution. Of every 100 people who have a negative sentinel lymph node biopsy, around 3 will subsequently develop a recurrence in the same group of lymph nodes.
People who have had the operation may be able to take part in clinical trials of new treatments for melanoma. These trials often cannot accept people who have not had this operation. A general anaesthetic is needed for the operation.
The operation results in complications in between 4 and 10 out of every 100 people who have it.
If your sentinel node comes back positive you could be eligible for adjuvant treatments for a year to reduce the likelihood of recurrence. Please note adjuvant treatments are  not suitable for all patients and they do have side effects.

What does the procedure involve?

The procedure involves two stages. The first stage is a diagnostic test and the second stage is when the surgery is performed.

The diagnostic test

The first stage of the procedure is to perform sentinel lymph node imaging (lymphoscintrigraphy) which will identify the location of the sentinel node. This involves injecting a small amount of radioactive liquid into the original scar from where your melanoma was removed. This may be is slightly uncomfortable depending on where your melanoma was removed from. The radioactive liquid then travels slowly through the lymphatic system; this usually takes about 2 hours. During this time you are free to do what you want; it may be a good idea to bring a book to read or something to occupy you.

The site of the original melanoma usually defines where the sentinel node will be found. For instance, if the melanoma was on the right leg the sentinel node is found in the right groin. If the melanoma was on the stomach or back the sentinel node could either be in the groins, armpits or neck. If this occurs it may mean more than one sample being taken from the lymph nodes.

After this period you will be asked to either lay or stand in front of a machine for a few minutes. The machine produces an outline of your body which is seen on the screens in the room. After a few minutes you will be able to see a glow developing on your body outline. This glow is produced by the radioactive liquid that was injected into your melanoma scar earlier. The radioactive liquid is taking the same journey as the cancer cells would take if they had entered your lymphatic system. This does not mean that cancer cells are present. The radioactive liquid has located the most likely place the cancer cells would go to – the sentinel node. The procedure may be done on the same day as your operation or the day before. If the procedure is being done the day before your operation, you will be able to go home or be admitted to the ward at Castle Hill Hospital.

The surgical procedure

On the day of your operation, you will be seen by the doctors and nurses and prepared for theatre. Preparing for theatre involves being placed into a gown and the possibility of wearing white stockings. These stockings may feel tight but they prevent blood clots from forming in the legs (deep vein thrombosis – DVT).

The surgery is usually performed under a general anaesthetic (while you are asleep) and involves the removal of the sentinel node. A blue dye is injected into the original scar from where your melanoma was removed. This dye then travels quickly through the lymphatic system to the sentinel node. Before this sentinel node is removed, the surgeon scans your body with a hand held gamma detector, which detects the presence of the radioactive material that you had injected. The surgeon is able to follow the radioactive material with this detector from your original melanoma site to the sentinel node. An incision (cut) is made into the area shown by the detector i.e. armpit, groin or neck. The surgeon will be looking for the presence of blue dye in one or more of the sentinel nodes. It is these lymph nodes that are then removed and sent away for analysis.

It is also necessary at the same time to remove some more of the surrounding skin from where you had your melanoma removed (wide excision). This is done to ensure that no cancerous cells are present. The wide excision is dependent on how thick your melanoma was. The wide excision wound is then stitched together or may require a local flap or skin graft to reconstruct the wound. A local flap involves skin being moved about and instead of being left with a straight stitch line you will have an unusual shaped stitch line. If you are having a skin graft you will be given a separate leaflet about what this involves.

Can there be any complications or risks?

Because this procedure is usually performed under a general anaesthetic there are the risks of DVT, pulmonary embolism (a clot in the lungs) and the chances of developing a chest infection are increased if you smoke.

Because you are having an incision made there are the risks of developing an infection, wound breakdown, permanent scarring, bruising and temporary numbness to the area. The blue dye used to locate the sentinel node at the time of your operation can leave a localised bluish tinge to the skin which may take up to 6 months to disappear. With the incision involving the removal of lymph nodes, which are usually there to get rid of excess fluid, there is a chance that you may develop temporary swelling around the area where your nodes are removed (seroma). There is a risk of developing generalised swelling of the area operated on (lymphoedema) and this needs to be brought to the attention of a health professional.

You may notice some discolouration in your urine for a few hours after surgery. This is due to the chemicals used in the lymphoscintrigraphy and dye during surgery.

The sentinel node can be found in 95% of patients. Occasionally no sentinel node can be found, but you will still be followed up closely as an outpatient.

How do I prepare for the operation?

Please read the information leaflet. Share the information it contains with your partner and family (if you wish) so that they can be of help and support. There may be information they need to know, especially if they are taking care of you following this examination.

Please take your medication as normal unless given other information by the pre admission nurses. The preadmission nurses will also inform when you should stop eating and drinking before your operation and what medication you can take.

What happens afterwards?

After this operation, most patients can go home the same day, but for some individuals it may be necessary to be kept in hospital for one night. If you are kept in hospital, the next morning the doctors will come and see you. As long as you feel fine, have recovered from the anaesthetic and there are no problems with your wounds, you will be allowed to go home. When you go home you must keep your wounds, which will be covered by dressings, clean and dry. If you notice any excessive leakage or bleeding from the area or you are concerned about anything, please do not hesitate to contact the ward you had your surgery on (you will be given their number on discharge), or the Plastic Surgery Outpatients (01482) 623085.

You should not do any strenuous exercise or lifting with the affected areas for at least 3 weeks. It is advised that you take 2-3 weeks of work to convalesce; the doctors on the ward or in the clinic can provide you with a Statement of Fitness for Work (formerly a sick certificate) for that period.

Once discharged from the ward you will be given an outpatient appointment for 10 – 14 days after your operation. At this appointment the nurses will remove your stitches if necessary and may re-apply a dressing. If the results from your biopsy (what has been removed) are back, you will be seen by a doctor. If not, a further appointment will be made. Once the results are back the doctor will go through them with you and explain them. If the results show that there are cancer cells in the sentinel nodes then they will discuss the need for possible further surgery with you. If the results come back clear (no cancer cells present) you will still be followed up regularly and examined because there is still a small chance (approximately 5%) for the cancer to spread.

For further information, you can find some informative videos on the Melanoma Focus website: Sentinel lymph node biopsy (SLNB) – Melanoma Focus

Should you require further advice on the issues contained in this leaflet, please do not hesitate to contact your Clinical Nurse Specialist on tel no.(01482) 461078.

General Advice and Consent

Most of your questions should have been answered by this leaflet, but remember that this is only a starting point for discussion with the healthcare team.

Consent to treatment

Before any doctor, nurse or therapist examines or treats you, they must seek your consent or permission. In order to make a decision, you need to have information from health professionals about the treatment or investigation which is being offered to you. You should always ask them more questions if you do not understand or if you want more information.

The information you receive should be about your condition, the alternatives available to you, and whether it carries risks as well as the benefits. What is important is that your consent is genuine or valid. That means:

  • you must be able to give your consent
  • you must be given enough information to enable you to make a decision
  • you must be acting under your own free will and not under the strong influence of another person

Information about you

We collect and use your information to provide you with care and treatment. As part of your care, information about you will be shared between members of a healthcare team, some of whom you may not meet. Your information may also be used to help train staff, to check the quality of our care, to manage and plan the health service, and to help with research. Wherever possible we use anonymous data.

We may pass on relevant information to other health organisations that provide you with care. All information is treated as strictly confidential and is not given to anyone who does not need it. If you have any concerns please ask your doctor, or the person caring for you.

Under the General Data Protection Regulation and the Data Protection Act 2018 we are responsible for maintaining the confidentiality of any information we hold about you. For further information visit the following page: Confidential Information about You.

If you or your carer needs information about your health and wellbeing and about your care and treatment in a different format, such as large print, braille or audio, due to disability, impairment or sensory loss, please advise a member of staff and this can be arranged.

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