Visualization of Collateral Lymphatic Pathways After Axillary Node Dissection in Rats Using Real-Time Fluorescent Lymphography.

BACKGROUND

Manual lymph drainage (MLD) is commonly used to alleviate upper limb lymphedema; however, objective evidence regarding its physiological efficacy remains limited.

METHODS

This study aimed to visualize postoperative changes in lymphatic flow and to identify potential collateral drainage pathways following axillary lymph node (LN) dissection using real-time fluorescent lymphography in a rat model. Twelve Wistar rats underwent surgical excision of the right axillary LNs with careful ligation of lymphatic vessels. Indocyanine green (ICG) lymphography was performed at multiple time points from day 3 to week 24 postoperatively using a photodynamic eye (PDE) imaging system.

RESULTS

Prior to surgery, linear lymphatic signals were observed in the forelimbs. Following the surgery, these signals disappeared and were replaced by diffuse dermal backflow patterns. Over time, network-like signals developed in the axilla and progressed into linear patterns, extending toward the ipsilateral cervical region. In six of the 12 rats, the signals also reached the contralateral axillary fossa via the transverse thoracic pathways. Dermal backflow signs persisted throughout the study period despite the emergence of collateral flow.

CONCLUSION

These findings suggest that a collateral pathway to the ipsilateral cervical region may support interstitial fluid drainage in the absence of axillary lymphatic vessels. This study provides foundational insights into lymphatic rerouting mechanisms and may contribute to the future evaluation of MLD efficacy using functional imaging.