Lymphatic Drainage of the Breast
Lymphatic drainage of the breast is of enormous clinical importance because carcinoma of the breast spreads predominantly via lymphatics to regional lymph nodes.
Two Groups of Lymphatics
| Group | Drains |
|---|---|
| Superficial lymphatics | Skin of the breast, except the skin of the nipple and areola |
| Deep lymphatics | Parenchyma of the breast + skin of nipple and areola |
A plexus of lymph vessels deep to the areola is called the subareolar plexus of Sappey. The subareolar plexus and most of the lymph from the breast drain into the anterior (pectoral) group of axillary lymph nodes.
Lymph Nodes Draining the Breast
Five groups of lymph nodes receive lymph from the breast:
| Node Group | Location | Notes |
|---|---|---|
| Axillary lymph nodes | In the axilla — 4 subgroups: anterior/pectoral, posterior, central, lateral; apical group receives from all | Principal drainage; ~75% of total breast lymph |
| Internal mammary (parasternal) nodes | Along internal thoracic vessels (parasternal) | ~20% of total breast lymph; drain medial quadrants |
| Supraclavicular nodes | Above the clavicle | Receive secondary drainage from axillary nodes |
| Posterior intercostal nodes | In posterior intercostal spaces, in front of heads of ribs | ~5% of total breast lymph; drain lower lateral quadrant |
| Cephalic (deltopectoral) nodes | In the deltopectoral groove | Receive some lymph directly |
Drainage by Quadrant
1. Lateral Quadrants (Upper and Lower Lateral)
→ Anterior axillary (pectoral) group of axillary lymph nodes (situated deep to the lower border of pectoralis minor)
2. Medial Quadrants (Upper and Lower Medial)
→ Internal mammary (parasternal) lymph nodes (along the internal thoracic artery)
- Some may cross to internal mammary nodes of the opposite side
3. Lower Lateral Quadrant (a few lymphatics)
→ Follow posterior intercostal arteries → Posterior intercostal nodes
4. Lower Medial Quadrant (a few lymphatics)
→ Pierce anterior abdominal wall → communicate with subdiaphragmatic and subperitoneal lymph plexuses → From here cancer cells can reach the ovary (→ Krukenberg’s tumour)
5. Deep Surface of the Breast
→ Lymphatics pierce pectoralis major and clavipectoral fascia → Drain directly into apical group of axillary lymph nodes
Proportions of Lymphatic Drainage
| Destination | Approximate % |
|---|---|
| Axillary nodes (total) | ~75% |
| Internal mammary nodes | ~20% |
| Posterior intercostal nodes | ~5% |
Among axillary nodes: most drain to the anterior (pectoral) group → then to central and lateral → then to apical group → then to supraclavicular nodes.
Cross-Communication
The superficial lymphatics of the breast of one side communicate with those of the opposite side across the midline.
Consequence: Unilateral breast malignancy can spread to become bilateral via this cross-communication.
Subareolar Plexus of Sappey
- A plexus of lymph vessels lying deep to the areola
- Drains the nipple and areola
- Connects with the deep lymphatics of the breast parenchyma
- Drains primarily into the anterior axillary lymph nodes
Lymph Flow from Axillary Nodes
Anterior (pectoral) group → Central group + Lateral group → Apical group → Supraclavicular lymph nodes (and then into the subclavian lymph trunk)
Viva Pearls
- 75% axillary, 20% internal mammary, 5% posterior intercostal
- Subareolar plexus of Sappey = plexus under the areola; drains nipple + areola
- Lateral quadrants → anterior axillary (pectoral) nodes
- Medial quadrants → internal mammary nodes
- Deep surface lymphatics pierce pectoralis major + clavipectoral fascia → apical nodes
- Cross-communication of superficial lymphatics → unilateral cancer can become bilateral
- Lower medial quadrant → subperitoneal plexus → ovary → Krukenberg’s tumour
- Apical group of axillary nodes is the final axillary relay before supraclavicular nodes
- Cancer in internal mammary nodes = poor prognosis; not accessible to axillary dissection