Lymph nodes are an essential part of the immune system, which helps the body fight infections or cancers. The lymphatic system is made up of a network of vessels that drain tissue fluid (called lymph) into special bean-shaped organs, called lymph nodes. The lymph nodes act as a filter, removing germs, foreign particles, or abnormal cells from the lymph fluid.
Lymph nodes can be found in clusters under the armpits, on either side of the neck, and in the groin area. They contain white blood cells, which fight foreign bacteria and harmful cells. When they fight off an infection, they may become enlarged or swollen as they work to produce more white blood cells than usual to fight off the disease. The presence of cancer cells can also cause the lymph nodes to swell. In children, even a scratch on a finger or minor trauma to the foot can cause localized enlarged lymph nodes.
Determining the cause of the swelling can be tricky, but in general, enlarged lymph nodes spread throughout the body indicate that the body is fighting off an infection, an autoimmune disease, a bad drug reaction, or something more serious, like leukemia. The swelling is more likely to be benign if the node is less than one centimeter in diameter and soft, rubbery and tender. Only by doing a biopsy can a doctor tell for sure.
You should be concerned about your child's enlarged lymph nodes if:
- They are located just above the collar bone
- They are hard and not tender; merely infected swollen nodes are tender, inflamed or rubbery
- The enlarged nodes continue to grow rapidly.
- They are accompanied by fever, night sweats or weight loss.
- They are larger than 1 centimeter (0.4 inch) in diameter; high risk enlarged nodes are larger than one inch in diameter.