What is "lymphoscintigraphy" and how does it help detect skin cancer?

What is "lymphoscintigraphy" and how does it help detect skin cancer?

When a malignant melanoma is identified on the skin after the biopsy is taken, if it is of a certain invasiveness into the dermis, it is considered at some risk for metastasis to the local lymph node. When that is felt to be the case, a special procedure called a sentinel node biopsy is taken. That is done by the process of lymphoscintigraphy; injecting a radioactive dye into the melanoma, and then tracing it radioactively to the first lymph node which that dye goes to. That is considered the sentinel node, or the sentry node, which in a way protects the other nodes from getting a metastasis. It is felt that if the node that lights up is negative for malignant melanoma, then all the other nodes after will be equally negative. That is when a sentinel biopsy and lymphoscintigraphy are done, and it has prognostic significance to the patient.