Plastic Surgery Research Council
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SENTINEL LYMPH NODE BIOPSY FOR MELANOMA IS THERE A CORRELATION BETWEEN PREOPERATIVE LYMPHATIC MAPPING WITH SURGICAL LYMPH NODES HARVESTED?
Presenter: Kristen A Hudak, MD
Co-Authors: Hudak KE; Dzwierzynski WW
Medical College of Wisconsin

PURPOSE: Nodal status is the most significant prognostic factor in melanoma. Lymphoscintigraphy identifies lymphatic drainage patterns directing the surgeon to the proper basin for sentinel lymph node removal; however, it can be difficult to understand how to utilize this data. No study has examined the relationship between lymphoscintigraphy and harvested nodes nor gamma probe counts and lymph node status.

METHODS: 262 patients were identified who underwent a sentinel lymph node biopsy for melanoma between 2001-2010. Clinico-pathologic and treatment information was collected. The number of lymph nodes and basins demonstrated on lymphoscintigraphy was compared to those at surgery. Gamma probe counts were analyzed and compared.

RESULTS: Median age was 54.5(range 18-90) with 52.3% male Average Breslow depth was 2.0 mm(+-1.9 mm), with 42% shave biopsies having tumor at the base. 99.6% of lymphoscintigraphy studies identified at least one basin, 80% showed only 1(range 0-4). On average 1.5(+-0.9) sentinel nodes were identified and 31% had secondary nodes. Surgery excised on average 2.6(+-1.4) nodes involving 1.2(+-0.5) basins. 17.6% had a positive lymph node. There was no difference in the sum or average of gamma counts between positive and negative lymph node groups (p=0.2, p=0.5). When comparing lymphoscintigraphy and surgical excision, the correlation of lymphatic basins was r=0.67 and of lymph node numbers was r=0.33. Further analysis identified 32 patients had a positive sentinel lymph node among multiple removed nodes and removing only the hottest node would have missed the positive lymph node in three patients.

CONCLUSION: Lymphoscintigraphy should be used to direct the surgeon to the proper lymphatic basins for a sentinel node procedure, however, lymph node removal must continue until the background count is less than 10%. The correlation of lymph node number identified on lymphoscintigraphy to surgical excision is weak. Gamma probe counts cannot be used to differentiate positive from negative lymph nodes and the positive lymph node is not always the hottest node from those removed.


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