What is the lymphatic system?

The lymphatic system is a part of the body’s immune system. It works to fight disease and infection. The lymphatic system goes through many changes during a child's growth. Before birth, a baby is protected by the mother's immune system. At birth, a newborn's lymphatic system starts to respond to the regular exposure to new antigens. Antigens are organisms and diseases. The lymphatic system grows steadily until puberty, when a child’s growth slows.

Parts of the lymphatic system

The lymphatic system includes:

• Lymph. This is a fluid. It moves all around the lymph system. It contains a type of white blood cell called a lymphocyte.

• Lymphocytes. These are white blood cells that fight infection and disease.

• Lymph vessels. These are tiny tubes that carry lymph fluid around the body.

• Lymph nodes. These are small, bean-shaped organs. They act as filters for the lymph fluid as it travels all over the body. Lymph nodes are found in the underarms, groin, neck, chest, and belly (abdomen).

When lymph nodes swell

Children are constantly fighting off new germs and infections. Their lymphatic system quickly responds to these foreign particles. When this happens, lymph nodes often swell. This is known as lymphadenopathy. It’s common for children to have slightly enlarged lymph nodes in certain areas of the body some of the time.

But changes in the lymph nodes can also mean certain conditions or diseases that need special treatment. In some cases, swollen lymph nodes are caused by:

• Lymphadenitis. This is infection of 1 or more lymph nodes in which the glands often become suddenly sore and swollen, frequently with redness of the overlying skin. Someone with lymphadenitis will often have a fever, and the swollen glands could drain pus. Lymphadenitis is often caused by bacteria such as streptococcus or staphylococcus. In some cases, it is caused by other bacteria, such as those that cause tuberculosis and syphilis.

• Lymphangioma. This is a group of lymphatic vessels that forms a mass or lump. A large lymphangioma has greatly enlarged lymphatic vessels.

• Cystic hygroma. This is a large pocket of lymph fluid (cyst). It is caused by blocked lymph vessels. A cystic hygroma may have multiple cysts linked to one another by the lymphatic vessels.

• Lymphoma. This is cancer of the lymph system. The cancer causes the cells in the lymph system to reproduce abnormally. It causes the lymph nodes to swell. And it makes the body less able to fight infection.

Talk with your child’s healthcare provider if you have questions or concerns about your child’s health.