The blue color of the skin is due to injection with radioactive dye which aids in identifying the location of the sentinel Lymph nodes. Sentinel nodes are the first group of lymph nodes that would potentially come in contact with the cancer cells, if they were to metastasize. Nodes that have a high uptake of the dye are considered suspicious and are typically removed. Determining whether or not the cancer has spread to these lymph nodes contributes to the overall staging of the patient and can change treatment options