Timing of sentinel lymphadenectomy in cutaneous melanoma.

Purpose: The conduct of sentinel lymphadenectomy for cutaneous melanoma varies substantially among the medical disciplines. The authors sought to characterize the number of hot spots identified during preoperative lymphoscintigraphy for cutaneous melanoma and to determine its relation to the harvesting of sentinel lymph nodes. Methods: Sixty-nine patients with cutaneous melanoma underwent lymphoscintigraphy with filtered Tc-99m sulfur colloid before sentinel lymphadenectomy. The lymphoscintigrams were reviewed and the number of hot spots visualized over time and the number of sentinel nodes harvested were determined. Results: Lymphoscintigraphy identified 79 patients with 87 lymphatic basins at risk for metastatic disease. Lymphoscintigraphy was performed in a mean time of 30 minutes (range, 15 to 40 minutes). The mean number of hot spots increased from 0.2 to 2.0 hot spots 40 minutes after the initial static image, but the number of hot spots stabilized between 20 and 40 minutes. The same number of sentinel nodes as hot spots visualized were harvested in 58% of patients. Fewer sentinel nodes were identified at the time of surgery than were visualized by lymphoscintigrams in 39% of patients. Conclusions: More hot spots were identified up to 40 minutes after the initiation of lymphoscintigraphy. Sentinel lymphadenectomy can be performed as near to 40 minutes after the initiation of lymphoscintigraphy as is logistically reasonable. However, there may be substantial latitude in delayed performance of sentinel lymphadenectomy.