Pathways of lymphatic drainage from the breast

Area of Science:

• Oncology
• Surgical Oncology
• Nuclear Medicine

Background:

• Sentinel lymph node (SLN) mapping is crucial for breast cancer staging.
• Current standard involves intraparenchymal injection of lymphophilic dye/radiocolloid near the tumor.
• Hypothesis: Common lymphatic trunks drain both breast parenchyma and skin, suggesting shared lymphatic pathways.

Purpose of the Study:

• To evaluate the efficacy of intradermal injection of radiocolloid compared to intraparenchymal injection of blue dye for SLN mapping.
• To determine if different injection routes lead to the same axillary lymph node.

Main Methods:

• 119 patients underwent intradermal injection of 99mTc-labeled filtered sulfur colloid over the breast tumor.
• Blue dye was injected intraparenchymally in the same (concordant) or different (discordant) quadrant as the primary tumor.
• Axillary exploration identified both blue (dye) and gamma-emitting (radiocolloid) nodes.

Main Results:

• The same SLN was identified as both hot (radiocolloid) and blue (dye) in 93.9% of concordant quadrant cases and 92.5% of discordant quadrant cases.
• No statistically significant difference (P = .99) was observed between concordant and discordant quadrant injections.
• In cases with distinct nodes, they were located very close to each other.

Conclusions:

• Dermal and parenchymal lymphatics of the breast appear to drain into the same axillary lymph nodes.
• Breast lymph drainage likely converges through a limited number of lymphatic trunks to one or two SLNs.
• Intradermal injection offers a potentially simpler and effective alternative for SLN mapping in breast cancer.