When should pelvic sentinel lymph nodes be harvested in patients with malignant melanoma?

Background: Preoperative lymphoscintigraphy for sentinel node biopsy (SNB) combined with intra-operative gamma-probe detection often identifies nodes within the pelvis. This study investigates the role of pelvic SNB harvest.

Methods: Retrospective review of eighty-two stage I/II melanoma patients with primary tumour on the lower limb and trunk who underwent groin SNB, either inguinal or pelvic or both, over a three year period.

Results: Of the 82 patients, 19 had positive SNBs (24%), all of which were inguinal nodes. None of the 11 patients with pelvic nodes removed had a positive pelvic node. The median follow-up period was 18 months (SD: 10.8; range: 8-43). Although the complication rate was higher following pelvic SNB, the difference was not statistically significant (p > 0.5). The average operative time for an inguinal SNB was 92 min, and increased significantly to 134 min for a pelvic SNB (p < 0.0001). Lymphoscintigraphy of trunk and thigh melanomas identified individual tracks to be leading directly from the tumour to a pelvic node(s). However, when the primary tumour was located at or below the knee, pelvic nodes identified by lymphoscintigraphy appeared to be second level nodes.

Conclusion: A lymphoscintigraphy protocol that includes dynamic images obtained in frequent intervals following injection of the radiotracer combined with thorough preoperative analysis of the lymphoscintigraphy scans and effective communication between the radiologist and the surgeon allows accurate identification of the primary tracks and prevent unnecessary harvest of second echelon pelvic lymph nodes. In patients with significant co-morbidities due consideration is required before harvesting pelvic sentinel nodes.