Reverse Lymphatic Mapping: A New Technique for Maximizing Safety in Vascularized Lymph Node Transfer

Background: The authors introduce the technique of reverse lymphatic mapping for vascularized lymph node transfer. This physiologic technique allows one to identify which lymph nodes drain the trunk as opposed to the extremity, to minimize the risk of iatrogenic lymphedema. Methods: A prospective study of patients undergoing vascularized lymph node transfer using the reverse lymphatic mapping technique was conducted. Patients received technetium injections in the first and second webspaces of the foot and intradermal indocyanine green injections in the lower abdomen. Lymphatic vessels were traced to the lymph nodes draining the lower abdomen that were harvested; a gamma probe was used to localize lymph nodes draining the lower extremity, which were avoided. In cases of vascularized axillary lymph node transfer, technetium was injected into the hand and indocyanine green was injected into the back and lateral chest. Ten-second counts were recorded of the lymph node flap and the sentinel node draining the extremity for comparison. Results: Thirty-five patients underwent vascularized lymph node transfer (19 groin and 16 axillary lymph node transfers) guided by reverse lymphatic mapping. Follow-up time was 1 to 30 months. Mean 10-second count using the gamma probe for all lymph node flaps was 88.6 (SD, 123; median, 39); mean 10-second count of extremity sentinel nodes was 2462 (SD, 2115; median, 2000). On average, 10-second signal strength of the lymph node flap was 6.0 percent that of the extremity sentinel node. Conclusion: Reverse lymphatic mapping guides vascularized lymph node flap harvest based on physiologic drainage patterns of the trunk and limb that may minimize the risk of iatrogenic lymphedema.