Once the presence of melanoma is confirmed, your doctor may wish to perform other tests especially if you have symptoms. Other tests may also be recommended if your doctor is concerned the melanoma has spread.
Sentinel Node Biopsy
After a diagnosis your doctor will need to determine whether or not the melanoma has spread beyond the primary tumour or local tissues. If so, it may have spread to the lymphatic system. The lymphatic system is a network of vessels that carry lymph through your body and melanoma may be found in the regional draining lymph nodes near the tumour.
The sentinel lymph node is the first lymph node to which cancer is likely to spread from a primary tumor. A sentinel lymph node biopsy is performed to confirm there are no signs of spread. A radioactive tracer dye is injected and followed to the sentinel lymph node, which is generally located in one of the major lymph node basins – inguinal, etc.
If the node does not contain melanoma, then the adjacent nodes are unlikely to be involved and no further surgery is done. If there is melanoma present, you will need a complete node dissection which involves removing the nodes adjacent to the sentinel node. Surgery is conducted under general anesthetic to remove the sentinel node and generally one or two other nodes around the sentinel node. A sentinel lymph node biopsy is done when there is no evidence of distant metastases.
If there are signs of melanoma spread, such as an increase in size of the lymph nodes in the area, a fine-needle aspiration or an excisional lymph node biopsy may be performed instead. Fine-needle aspiration removes tiny pieces of a lymph node. An excisional biopsy removes enlarged lymph nodes through a small incision. An injection of a local anaesthetic numbs the area before the biopsy.
Lactate dehydrogenase (LDH) is a blood test. An abnormally high LDH level may indicate metastases. If your LDH level is increased, your doctor may perform additional tests to search for metastases. LDH levels provide information about the prognosis of melanoma.
Different forms of imaging allow doctors to see internal tissues and organs. This helps determine if the melanoma has spread anywhere in the body. Imaging is not used for people with stage 0 melanoma or low-risk stage 1 disease. For intermediate-risk stage 1 disease and stage 2 disease, imaging is used mostly to evaluate specific symptoms, such as pain.
Imaging is not a routine test in early melanoma. For stage 3 and stage 4 disease, imaging is used to evaluate specific symptoms. It is also used to assess the degree of spread of the melanoma. The type of imaging depends on symptoms and the likely location of melanoma spread.
- Chest x-ray: A chest x-ray may be performed for some stage 1 and 2 melanomas. It is often performed for stage 3 and 4 melanomas.
- Computed tomography (CT) scan: A CT scan takes multiple x-rays of part of the body from different angles. This produces a three-dimensional image. Injection of a contrast agent helps highlight the area of concern. A CT scan is the best type of imaging to detect melanoma in the lung.
- Magnetic resonance imaging (MRI): An MRI uses radio waves and magnets to take pictures of organs and other parts of the body. An MRI is the best type of imaging to find melanoma in the brain.
- Positron emission tomography (PET) scan: An injection of radioactive glucose, or sugar, is given before this test. The scan identifies areas with the most glucose, especially cancer cells, which collect glucose.