Excellent! Lymph flows through each region of the node from the cortex, through the paracortex, then into the medulla. Explain the difference between medullary cord and medullary sinus.

To avoid doing a complete axillary node dissection (CAD), you wish to pinpoint and remove only the particular lymph node(s) involved and decide to perform a sentinel lymph node (SLN) biopsy*.

*SLN biopsy allows for thorough pathogenic evaluation. After a radioactive dye is injected, sentinel lymph nodes are detected with a hand-held gamma detection probe identifying areas of increased activity. Nodes with increased radioactivity are labeled as sentinel and removed. Frozen section analysis is preformed and if the SLN is negative for tumor, the node is embedded in paraffin and H&E and immunohistochemistry stained with a cytokeratin antibody. Serial sections are taken throughout the node and examined for confirmation.

Your patient is concerned because she heard that breast cancer patients develop swelling and pain in their arms.

You explain that removal of lymph nodes may result in decreased lymphatic drainage, a condition known as: