Sentinel lymph node biopsy
Lymph nodes are bean shaped structures. Some normal nodes are as small as the head of a pin; others can be as large as a lima bean. The lymph glands and vessels serve as channels through which liquid around the cells (extra cellular fluid) is returned into the blood stream. Lymph nodes act to filter these liquids of bacteria, fungi, and viruses. White blood cells and antibodies in the lymph nodes can kill these invaders, which can cause disease.