Sentinel node (SN) mapping and biopsy is a procedure that accurately stages the regional lymph node (LN) basin. Defined patterns of lymphatic drainage allow intraoperative determination of the first (sentinel) lymph node in the regional basin, and the absence of metastatic disease in the SN accurately reflects the absence of melanoma in the remaining regional nodes. The use of radiocolloid and a hand-held gamma detecting probe (GDP) together with a vital blue dye provides optimal results, and allows for the successful identification of the SN in over 99% of the procedures. Close collaboration between surgeons, nuclear radiologists and pathologists is required to ensure optimal results. Examination of serially sectioned SNs by hematoxylin-eosin staining (H&E), immunohistochemical staining and perhaps in the near future RT-PCR should reduce the number of patients with missed microscopic melanoma in the regional lymph nodes. Furthermore, the survival benefit recently reported in patients with melanoma metastatic to regional nodes using high dose of interferon alpha-2b signals that the surgeons should aggressively examine patients for the presence of occult regional melanoma metastases. Intraoperative SN mapping and SN biopsy are cost-effective procedures that allows accurate identification of regional lymph nodes that contain metastatic melanoma.

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