Sentinel node biopsy in melanoma patients: dynamic lymphoscintigraphy followed by intraoperative gamma probe and vital dye guidance

Biopsy of the first tumor-draining lymph node (sentinel node, SN) is bound to become the procedure of choice in regional staging of melanoma patients. A tumor-negative SN virtually excludes lymphatic metastases and obviates the need for lymph node dissection. The aim of this study was to combine the advantages of three known techniques to improve the yield of successful SN biopsies. A total of 150 drainage areas in 135 patients was evaluated. First, preoperative dynamic and static lymphoscintigraphy was performed after injection of technetium 99m colloidal albumin. In all patients one to three focal accumulations, concordant with SNs, were seen in the lymphatic drainage areas, in 97% within 20 minutes from injection of the tracer. Peroperative identification of the SN, 2 to 24 hours after injection of the tracer, was done with a handheld gamma probe to estimate the optimal site for the small incision and to guide preparation. Vital dye was injected just preoperatively and served to facilitate the final identification and biopsy of the SN. A total of 216 SNs were biopsied. Micrometastases were found in 39 SNs in 30 drainage areas, and in 22 of the 30 of the SN was the only node harboring tumor. In 5 of 30 drainage areas, the SN did not contain blue dye and would not have been found without the gamma probe. Up to now (follow-up 233-691 days) no recurrence has developed in the lymphatic drainage areas where the SN was tumor-free. It was concluded that by combining these three techniques the SN could be detected and excised in all patients. The procedure combines a steep learning curve with high sensitivity.