Lymph node is the unique organ of mammals. Normal human's superficial lymph nodes is very small, smooth, soft, no adhesion with surrounding tissue and no tenderness, less than 0.5 cm in diameter . When the bacteria enter into your body from the site of injury, the lymphocytes will produce lymphokines and antibodies to kill the bacteria effectively. The result is lymphocytes hyperplasia and histiocytosis of the cellular response to lymph nodes within the lymph node, as lymph node reactive hyperplasia.viruses, certain chemicals, toxic products of metabolism, degeneration of tissue components and foreign matter Can cause lymph node reactive hyperplasia . Therefore, the enlarged lymph nodes are the body's beacon, a warning device