Epitrochlear and Humeral Lymph Nodes: A Biomarker for Deep Lymphatic Function and Implications for Breast...

Area of Science:

• Lymphatic system imaging
• Nuclear medicine
• Medical diagnostics

Background:

• Superficial to deep lymph rerouting is crucial for preventing breast cancer-related lymphedema (BCRL).
• Humeral lymph nodes indicate deep lymphatic drainage, while epitrochlear lymph nodes suggest superficial to deep collateralization.
• In vivo imaging of functional connectivity between epitrochlear and humeral lymph nodes has not been previously studied.

Purpose of the Study:

• To investigate the functional connectivity between epitrochlear and humeral lymph nodes using lymphoscintigraphy.
• To assess the baseline superficial to deep lymphatic drainage pathways in healthy individuals.
• To explore the potential of epitrochlear and humeral lymph node drainage as biomarkers for BCRL risk.

Main Methods:

• Healthy female volunteers underwent intradermal injections of 99-Tcm sulfur colloid in each upper extremity.
• SPECT/CT imaging was performed 2 hours post-injection to visualize tracer uptake in lymph nodes.
• Two nuclear medicine physicians independently reviewed scans, and a Chi-square test analyzed the correlation between epitrochlear and humeral lymph node drainage.

Main Results:

• Drainage to epitrochlear and humeral lymph nodes was observed in 57% and 51% of arms, respectively.
• Functional drainage to both epitrochlear and humeral lymph nodes occurred in 40% of arms.
• Humeral lymph node drainage was significantly more frequent in arms with epitrochlear lymph node drainage (71% vs. 26%, p < 0.001).

Conclusions:

• Epitrochlear and humeral lymph node drainage are significantly correlated, indicating a functional superficial to deep lymphatic pathway in 40% of healthy arms.
• The absence of drainage to both epitrochlear and humeral lymph nodes may serve as a potential biomarker for increased BCRL risk.