INTRAOPERATIVE RADIOLYMPHOSCINTIGRAPHY IMPROVES SENTINEL LYMPH-NODE IDENTIFICATION FOR PATIENTS WITH MELANOMA

Background The sentinel lymph node (SLN), the first node draining the primary tumor site, has been shown to reflect the histologic features of the remainder of the lymphatic basin in patients with melanoma. Int raoperative localization of the SLN, first proposed by Morton and coll eagues, has been accomplished with the use of a vital blue dye mapping technique. Technical difficulties resulting in unsuccessful explorati ons have occurred in up to 20% of the dissections. Objectives The auth ors aimed to define the SLN using gamma detection probe mapping and to determine whether intraoperative radiolymphoscintigraphy using techne tium sulfur colloid and a hand-held gamma-detecting probe could be use d to improve detection of all SLNs for patients with melanoma. Methods To ensure that all initial nodes draining the primary site were remov ed at the time of selective lymphadenectomy, the authors used intraope rative radiolymphoscintigraphy to confirm the location of the SLN, whi ch was determined initially with the preoperative lymphoscintigram and the intraoperative vital blue dye injection. Patient Population The p atient population consisted of 106 consecutive patients who presented with cutaneous melanomas larger than 0.75 mm in all primary site locat ions. Results The preoperative lymphoscintigram revealed that 22 patie nts had more than one lymphatic basin sampled. Two hundred SLNs and 14 2 neighboring non-SLNs were harvested from 129 basins in 106 patients. After the skin incision was made, the mean ratio of ''hot spot'' to b ackground activity was 8.5:1. The mean ratio of ex vivo SLN-to-non-SLN activity for 72 patients who had SLNs harvested was 135.6:1. When cor related with the vital blue dye mapping, 139 of 200 (69.5%) SLNs demon strated blue dye staining, whereas 167 of 200 (83.5%) SLNs were ''hot' ' according to radioisotope localization. With the use of both intraop erative mapping techniques, identification of the SLN was possible for 124 of the 129 (96%) basins sampled. Micrometastases were identified in SLNs of 16 of the 106 (15%) patients by routine histologic analysis . Conclusion The use of intraoperative radiolymphoscintigraphy can imp rove the identification of all SLNs during selective lymphadenectomy.