Lymphoscintigraphy in high-risk melanoma of the trunk: predicting draining node groups, defining lymphatic channels and locating the sentinel node.

Lymphoscintigraphy was performed in 209 patients with high-risk melanoma of the trunk referred to the Sydney Melanoma Unit and considered for lymph node dissection. Lymphoscintigraphy accurately defined the draining lymph node groups and was 94% sensitive in detecting draining sites that contained metastases. When combined with the clinical finding of palpable lymph nodes, the sensitivity rose to 98%. Most patients showed lymph drainage to one or two node groups and only 22 patients showed drainage to 3 or more node groups. The major lymph channels could also be marked on the skin prior to incontinuity dissection. Most patients had multiple draining lymph channels and these often diverged significantly from each other in the path to the draining node group. The number and location of interval nodes could be determined and marked on the skin. These and the major lymph channels could thus be excised at the time of surgery. Unusual drainage patterns were sometimes seen; for example, three patients displayed a new lymph pathway with direct drainage from the back anteriorly to the para-aortic nodes. The location of the sentinel nodes in each draining lymph-node group could also be marked on the skin prior to surgery, enabling quick and accurate identification of this node, using the blue-dye technique if biopsy were to be performed. These findings lead us to recommend lymphoscintigraphy prior to wide local excision in patients with truncal melanoma who are candidates for surgery. Lymphoscintigraphy results will help plan surgery and lead to minimum surgical intervention, consistent with effective surgical management.