Narrator: The thicker a melanoma becomes, the higher the chance of it spreading in to the lymphatic system and lymph nodes. Unless the lymph nodes are enlarged and visible through the physical exam or on imaging tests, the only method to accurately determine whether cancer has spread to the lymph nodes would be to take away the lymph nodes.
The road of the original lymph drainage and extent of tumor spread could be determined by seeking the sentinel lymph node the initial node that filters lymph fluid draining from the melanoma. In a few melanomas, tumor cells can travel in several direction within the lymph system. Sometimes there’s several sentinel lymph node.
To look for the located area of the sentinel node or nodes before surgery, a radioactive material is injected in to the skin round the site of the initial melanoma. The radioactive substance travels through the lymph channels and collects in the sentinel node. A body scan done several minutes following the injection identifies the sentinel node’s position.
To greatly help view the sentinel node through the operation, the surgeon injects a blue dye in to the skin round the melanoma. Just like the radioactive material, the dye also drains by lymphatic channels to the sentinel node. A little incision is manufactured close to the sentinel lymph node. The current presence of the blue dye and a musical instrument that detects radiation permit the surgeon to recognize the sentinel node.
The node is removed and delivered to a pathologist who slices it into multiple pieces. Each slice is examined under a microscope for melanoma cells. Special stains are also used to greatly help visualize a good tiny amount of cancer cells.
If melanoma has spread to the sentinel lymph node, another nodes of this type are surgically removed to be sure they don’t contain additional melanoma cells.
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July 29, 2022
- Sentinel lymph node biopsy. National Cancer Institute. https://www.cancer.gov/about-cancer/diagnosis-staging/staging/sentinel-node-biopsy-fact-sheet. Accessed Aug. 17, 2020.