Lymph nodes are present in a number of locations around the human body. They are a part of the lymphatic system, which is a mechanism for the body to collect potentially harmful substances within the body (bacteria for example) and drain them out via the lymph nodes, where these substances are filtered out and destroyed. The fluid that carries these substances is called ‘lymph’ and, once it has reached its destination lymph node, it passes back into main blood vessels. Lymph nodes are located in the armpit (axillary lymph nodes) as well as in the groin (inguinal), abdomen, chest and neck (cervical).

Sentinel lymph node biopsy is a procedure where lymph nodes are checked to see if there is any evidence of cancer cells having travelled there from a tumour. One or several lymph nodes are removed in this procedure and are sent for pathological analysis.

It is very important that a sentinel lymph node biopsy is performed if the melanoma is:

• greater than or equal to 1mm deep or
• ulcerated or
• has features of a high growth rate
• Clarke level IV or V

More information on sentinel lymph node biopsy in general can be found on this page (which refers more specifically to breast cancer, but equally applies to the procedure for melanoma).