Background: Selective lymphadenectomy or "sentinel node" biopsy has been introduced recently by Morton and colleagues (Arch Surg 1992;127:392-9) to stage patients with intermediate and thick malignant melanomas. It has proven to be an effective way to identify nodal basins at risk for metastasis without the morbidity of a complete lymph node dissection. The majority of biopsies can be performed under local anesthesia with small incisions, but technical difficulties occasionally result in unsuccessful explorations. Identification of the sentinel node can be enhanced by a intraoperative radiolymphoscintigraphy, a technique introduced Alex and Krag (Surg Oncol 1993;137-43) that uses radiolabeled sulfur colloid and a hand-held gamma probe.
Objective: We used intraoperative radiolymphoscintigraphy in conjunction with 1% lymphazurin blue dye to define the sentinel node(s) in 148 patients with greater than 0.76 mm in thickness or Clark level IV melanomas. Sentinel lymph nodes were isolated, harvested, and examined using conventional histopathology, and immunohistochemistry for S-100 and HMB-45 antibodies.
Results: The overall success rate of sentinel lymph node localization was 97% using a combination of the two techniques. Twenty-one (14%) patients had micrometastasis, and 17 of these subsequently underwent complete lymph node dissection. A total of 220 of 275 (80%) sentinel nodes harvested were radioactive or "hot" compared with 165 of 275 (60%) with the blue dye alone. Four of the patients with micrometastasis had sentinel nodes positive by gamma probe, but negative by blue dye mapping techniques.
Conclusion: Our results suggest that intraoperative radiolymphoscintigraphy using a hand-held gamma detecting probe improves the identification of sentinel lymph nodes during selective lymphadenectomy. This may reduce the number of "unsuccessful explorations" using the vital blue dye technique for lymphatic mapping, and appeal to a greater variety of surgeons, including dermatologic surgeons.