Overview
This lecture covers the lymphatic drainage of the mammary gland (breast), emphasizing its importance in the spread of breast cancer and relevant clinical implications.
Lymph Nodes Involved in Drainage
- The axillary lymph nodes are the main drainage site for the mammary gland.
- Five groups of axillary lymph nodes: pectoral (anterior), subscapular (posterior), brachial (lateral), central, and apical.
- Other involved nodes include internal mammary (parasternal), posterior intercostal, supraclavicular, and abdominal lymphatic plexuses.
Organization of Lymphatic Vessels
- Superficial lymphatical vessels drain skin over the mammary gland except the nipple and areola.
- Deep lymphatic vessels drain glandular tissue, ducts, nipple, and areola.
- Superficial lymphatics from the medial breast drain to parasternal nodes (same and opposite side), and the rest drain to pectoral axillary nodes.
- Deep lymphatics from lateral quadrants drain to pectoral (anterior) and posterior axillary nodes; central and apical groups receive further drainage.
- Lower lateral quadrant may also drain to posterior intercostal nodes.
- Medial quadrants drain to parasternal nodes and communicate with abdominal lymph plexuses.
- Lymph from upper quadrants may directly reach supraclavicular nodes.
Proportion of Lymph Drainage
- 75% of lymph from the mammary gland drains into axillary lymph nodes.
- 20% drains into internal mammary (parasternal) lymph nodes.
- 5% drains into posterior intercostal lymph nodes.
Clinical Anatomy
- Breast cancer spreads predominantly via lymphatic routes.
- "Peau d’orange" appearance (orange peel skin) results from obstruction of superficial lymphatics, causing skin edema.
- Skin retraction or puckering occurs when cancer infiltrates and shortens suspensory ligaments.
- Krukenberg’s tumor: secondary ovarian tumor due to cancerous lymphatic spread from lower medial quadrant via abdominal plexuses.
Key Terms & Definitions
- Lymphatic drainage — the process by which lymph fluid is transported from tissues to lymph nodes.
- Axillary lymph nodes — group of nodes in the armpit, primary drainage for the breast.
- Parasternal (internal mammary) nodes — lymph nodes near the sternum.
- Supraclavicular nodes — lymph nodes above the clavicle.
- Peau d’orange — dimpled skin texture caused by lymphatic obstruction.
- Krukenberg’s tumor — metastatic ovarian tumor from primary breast cancer.
Action Items / Next Steps
- Review the groups and locations of axillary lymph nodes.
- Understand clinical signs associated with lymphatic obstruction in breast cancer.
- Study diagrams showing lymphatic drainage of the breast.