Lymph nodes are part of the lymphatic system, which includes a network of lymph nodes and lymph vessels throughout the body. They are part of the immune system, which helps fight infections. Lymph nodes and vessels carry lymphatic fluid, waste material, viruses and bacteria throughout the body. Lymph nodes contain white blood cells, which are crucial in helping fight infections. Lymph nodes are named according to where they are located, and each location drains a different part of the body. For example, cervical lymph nodes are responsible for draining the area around the head and neck. The axillary lymph nodes will drain the arms, breasts, and chest walls. The inguinal lymph nodes can drain the genital area and lower extremities. Unfortunately, like many parts of the body, lymph nodes are at risk from medical issues that can compromise them. 

How Do the Lymph Nodes Work

When the immune system encounters a threat, such as a virus or bacteria, the lymph nodes act as a filter to collect and destroy whatever may be harmful to the body. White blood cells, also known as lymphocytes, inside the lymph nodes attack foreign entities such as viruses and bacteria. They also target injured or cancerous cells. Cancer cells can travel around the body via lymph nodes. When there is an infection or metastases from cancer, lymph nodes can become swollen and painful. Typically, lymphadenopathy due to infectious causes produces large and painful lymph nodes that are mobile (can be moved around underneath the skin), and resolve on their own as the infection clears. In contrast, lymphadenopathy due to cancer usually produces large, painless, and immobile lymph nodes that do not go away on their own. When cancer cells spread to the lymph nodes, this can cause a secondary cancer when the lymph nodes themselves become cancerous. Cancer in the lymph nodes is called a lymphoma. Lymphoma is usually diagnosed by biopsy. Tissue from the lymph nodes is studied under a microscope by a pathologist to determine whether the lymphadenopathy is due to cancer or due to infection.

Dangers to the Lymph Nodes

Most cases of lymphadenopathy are reactive and benign, meaning they are the result of a local infection or injury. However, when the lymphadenopathy is generalized or occurs in multiple locations, there may be a serious underlying issue. For example, HIV infection can cause swollen lymph nodes throughout the body, primarily in the occipital, axillary, and cervical chains. Generalized lymphadenopathy accompanied by fever, night sweats, and weight loss may be a sign of tuberculosis infection.

Some chronic medical conditions can also manifest with lymphadenopathy. Two such examples are lupus and sarcoidosis. Approximately 50 percent of people affected by systemic lupus erythematosus can have enlarged lymph nodes which are usually non-tender. The lymph node enlargement may occur intermittently with episodes of exacerbation of the disease. Lymph nodes located near the organs and inside the body may not be visible or palpable, such as in sarcoidosis where there is Hilar lymphadenopathy. Hilar lymphadenopathy can be detected on chest x-ray. Sarcoidosis usually presents with hilarious lymphadenopathy, cough, chest pain, fatigue, malaise, fever, and difficulty breathing.

Enlarged lymph nodes may also be a sign of cancer. In Hodgkin's and non-Hodgkin's lymphoma, there may be enlargement of cervical lymph nodes. Usually the enlarged lymph node is in the neck area, and is painless. Angioimmunoblastic T cell lymphoma manifests as generalized lymphadenopathy, anemia, enlargement of liver and spleen, and fever. Enlargement of the supraclavicular nodes may be a sign of tumors in the breast, neck, abdomen, or melanoma.