Display Patient Information Leaflets

Sentinel Lymph Node Biopsy

Posted Thursday, 17 September 2020

Date issued: February 2023

For review: February 2025

Ref: B-338/RD/Oncology/Sentinel Lymph Node Bio v7

PDF: Sentinel Lymph node biopsy final February 2023 v7.pdf [pdf] 85KB

What is the purpose of a Sentinel Lymph Node Biopsy (SLNB)?

You have already been told that the lesion recently removed from your skin was a malignant melanoma (skin cancer). Many patients ask if we can tell whether or not there has been any spread to the lymph nodes when their melanoma is diagnosed. A sentinel lymph node biopsy is not a treatment for melanoma it is an optional test to see if any melanoma cells have spread to the lymph nodes. The cancer cells can be so small that they cannot be felt, or seen on a scan, so the sentinel node biopsy is the most accurate way of detecting any spread of melanoma cells.

A sentinel lymph node biopsy is not routine for all patients. Patients who have had a melanoma of ‘intermediate thickness’ are offered this test.

There is no good evidence that people who have had a sentinel lymph node biopsy live longer than those who do not have it. People who do have it 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.

The sentinel node biopsy is performed at the same time as a margin of healthy skin is removed from the original melanoma site (wide local excision). Once the lymph node has been removed, we look at it very carefully under a microscope; we will then be able to tell you whether or not it contains any melanoma cells. If it does contain melanoma cells, we will discuss the treatment options that are available to you. If the lymph node does not contain any melanoma cells, then nothing further needs to be done and it is likely that no early spread has taken place.

Patients who decide not to have a sentinel lymph node biopsy will remain on regular follow up and be examined in the outpatient clinic for signs of any enlarged lymph nodes. This can only be detected once the melanoma cells have had time to grow in the node. When this is discovered the lymph nodes in this area may be removed.

How is sentinel lymph node biopsy performed?

The sentinel lymph node biopsy is carried out at the same time as a wide local excision from around the site of the original melanoma. It will be done under a general anaesthetic. You will need to come to the hospital on the morning of your operation or the day

before and have a small injection of x-ray dye or radioisotope around the melanoma biopsy scar. No anaesthetic is required for this. The isotope, which is administered in tiny doses and is otherwise harmless, enables us to see on a special x-ray where the sentinel lymph node is.

On the day of your operation the wide local excision will be carried out with you asleep and at the same time we will use a special probe which follows the isotope signal to locate the sentinel lymph node. We can double check the position of the node by using a blue dye which is injected at the site of the original melanoma. The sentinel lymph node can then be removed through a small incision. Most patients will go home on the same day.

What are the possible side effects?

After the sentinel lymph node biopsy you are unlikely to have any problems but between four to ten out of every hundred people may experience:

A small collection of fluid called a seroma, this can be easily removed with a needle and syringe.
A wound infection (as for any surgical operation)
Bruising around the sentinel node biopsy scar
Deep vein thrombosis

Having a sentinel lymph node biopsy can help to predict what might happen to you in the future. A negative sentinel node is reassuring but it does not mean the melanoma will definitely not come back. The results need to be interpreted with caution as three out of every hundred people who have a negative sentinel lymph node biopsy result will go on to develop a recurrence of the cancer in the same group of lymph nodes and around one out of ten will die within ten years. If the sentinel node is positive around three out of ten people will die within ten years.

The Clinical Nurse Specialists and your Surgeon are always happy to discuss any concerns you have.