The identification and mapping of melanoma regional nodal metastases: Minimally invasive surgery for the diagnosis of nodal metastases

The most controversial part of melanoma surgical care involves the role of elective lymph node dissection (ELND). Whereas proponents cite retrospective studies demonstrating the ability to control regional metastases and more accurate staging, opponents cite the unnecessary morbidity of a complete node dissection for the majority of patients. The technology of sentinel node mapping and selective lymphadenectomy, defined as the identification and removal of the first node into which the primary melanoma drains, may revolutionize melanoma care. If the sentinel node is negative, then theoretically the remainder of the nodes should also be negative (no 'skip' metastases), and a complete lymphadenectomy would not be required to control occult nodal disease. The location of the sentinel node may be variable in the lymphatic basin. Ideally, the surgeon needs a map of the position of the sentinel node in reference to the other nodes in the basin in order to do the procedure under local anesthesia with small incisions. In this way, patients are subjected to minimal morbidity and the procedure can be performed as an out-patient. Twenty-nine patients with clinically negative nodes and melanomas greater than 0.76 mm in thickness were judged to be candidates for ELND. Preoperative lymphoscintigraphy in two planes was used to mark the sentinel node, and the patients were taken to the operating room for intraoperative lymphatic mapping and sentinel node biopsy followed by complete dissection. Thirty-three per cent of the time, the clinician could not predict the approximate location of the sentinel node within 5 cm, but the lymphoscintigraphy was accurate in the identification of the location of the sentinel node 100% of the time (P < 0.05). No 'skip' metastases were identified in these patients, suggesting that the sentinel node histology can be used as a prognostic factor to identify a subgroup of the total melanoma population who would be candidates for ELND. The use of lymphoscintigraphy is invaluable to the surgeon to identify all basins at risk for metastatic disease and the location of the sentinel node(s) in relation to the basin. In this way, selective lymphadenectomy may be incorporated more widely into the everyday care of the melanoma patient.