gms | German Medical Science

Introduction: The lymphedema in breast cancer patients continues to represent a distressing consequence of axillary node resection. We propose the novel concept that the lymph node itself has important functions in maintaining fluid balance and it is the removal of the lymph node rather than damage to the lymphatic vessels that could be the key to initiate lymphedema. The purpose of this study was to develop an experimental approach to quantify lymphedema and lymph transport after lymph node excision in sheep. We examined whether the re-implantation of a vascularized lymph node would prevent edema and restore lymphatic function.

Material and methods: The popliteal lymphatic system in sheep was used in this study. As a measure of lymph transport, radioactive Human Serum Albumin (HSA) was injected into one of the prenodal vessels and the recovery of the tracer in plasma was measured at 8, 12 and 16 weeks after nodal excision. These data were compared with intact limbs and limbs that received a vascularized autologous popliteal lymph node transplant. Edema in the limb was quantified from the circumferential measure of the hind limb.

Results: Following lymph node removal, the hind limbs became progressively more edematous up to three days post nodectomy (increase of 33.8% relative to pre-surgical state). After this, the swelling improved but did not resolve in the majority of animals even at 16 weeks post surgery. Assessment of the mass transport of the HSA revealed recoveries at 8, 12 and 16 weeks (% injected/hr) of 10.6 ± 1.5 (n=7), 14.4 ± 1.0 (n=7) and 13.9 ± 1.0 (n=6) respectively compared with 17.2 ± 0.6 in node-intact limbs (n=7). Following autologous lymph node transplantation, the results in preliminary studies were variable with recoveries of 18.2 and 15.3 at 8 weeks and 20.7 and 12.6 at 12 weeks. Edema in this group was less. Failed micro-vascular anastomoses of the node may have contributed to low recoveries in several sheep.

Conclusion: We developed a new quantitative method to assess the physiological impact of lymph node excision in a sheep lymphedema model. Up to 16 weeks after nodal resection, lymphatic function had not been restored to node-intact levels. It would appear that the successful re-implantation of an autologous lymph node has the potential to prevent chronic edema and restore lymphatic transport function to normal levels.