Long-term follow-up of collateral pathways established after lymphadenectomy in rats

A collateral pathway established after lymphadenectomy could play an important role in long-term lymphedema treatment. The present study investigated alterations of lymph dynamics 1 year after lymphadenectomy using indocyanine green fluorescent lymphography to determine if a collateral pathway may be used for long-term lymphedema treatment. Wistar rats were anaesthetized and lymph nodes were excised at the inguinal and popliteal fossae. The treated hind limb was evaluated by fluorescent lymphography between 10 weeks and 6 months and between 6 months and 1 year postoperatively. Fluorescent lymphography demonstrated a lymphatic pathway to the ipsilateral axillary fossa in all rats 1 year after lymphadenectomy. Some capillary branches in the paths leading to the ipsilateral axillary fossa were dilated and tortuous. In addition, areas in which a fluorescent signal was not visible were increased in the thigh. In conclusion, the collateral pathway did not appear to be only for temporary use to compensate for drainage from the edematous limb but appears more stable as a component of a compensating lymphatic system. These new dilated vessels, although functional at this point, may still be susceptible to disturbance by further alteration to the lymph vessels.