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The information on this page was reviewed and approved by
Maurie Markman, MD, President, Medicine & Science at CTCA.

This page was updated on May 24, 2021.

Lymph nodes

The body’s lymphatic system helps fight disease and infection. Lymph nodes, also called lymph glands, are a key part of this network of vessels, tissues and organs. Lymph nodes are small, bean-shaped organs that produce and store blood cells, filter waste materials and harmful germs from the body’s tissues, and carry immune cells that fight infection.

There are hundreds of lymph nodes scattered in groups throughout the body, with large concentrations of the glands in the neck, armpits, abdomen and groin. The lymph system is part of the body’s immune system, producing white blood cells—B lymphocytes (B cells) or T lymphocytes (T cells)—that fight infection. The lymph system also includes the tonsils, spleen and thymus.

The lymph system is part of the body’s circulatory system. Lymph vessels are similar to the veins in the cardiovascular system. Instead of blood, the lymphatic vessels carry a clear, watery fluid called lymph (pronounced limf). This lymphatic fluid brings oxygen and other nutrients to tissue cells and takes away waste products from the cells. Each lymph node filters the lymphatic fluid draining from the vessels that lead to it.

The lymph fluid filtered by the lymph nodes, no matter where they’re located, moves to the chest, where it collects into a large vessel that drains into a blood vessel near the heart. From there, the filtered fluid, along with salts and proteins, moves into the bloodstream. Each group of lymph nodes filters a specific region of the body.

Swollen lymph nodes: What do they mean?

Swollen lymph nodes, or swollen glands, are a symptom of many illnesses—from the common cold to some forms of cancer—and a sign that something is wrong in the body. The swelling or enlargement, called lymphadenopathy, occurs in the lymph nodes when they’re filtering cells affected by a condition, such as an infection, injury or cancer. The most common reason lymph nodes swell is because of an infection, particularly viral infections such as a cold. It’s much rarer for swollen lymph nodes to be a symptom of a more serious condition such as cancer.

The lymph nodes are likely to swell in one specific region depending on the illness. This will usually occur in the neck, armpits or groin. Less common is when lymph nodes swell in several regions at the same time. That condition may be brought on by infections such as strep throat or mononucleosis, a reaction to certain medicines, an immune system disorder such as rheumatoid arthritis, and forms of cancer such as lymphoma and leukemia.

When lymph node swelling persists and is accompanied by other symptoms, such as fever or night sweats, or when there’s no obvious infection, it may be time to seek medical advice or evaluation from a doctor.

When touching an affected area, swollen lymph nodes may feel soft and round, like lumps the size of a pea, peanut or grape. If they’re painful when touched, that may be a sign of inflammation. Since lymph nodes appear in parallel—as, for instance, on both sides of the neck—you can feel lymph glands on both sides to see whether they are a normal size on one side and enlarged on the other, which may be a sign of infection.

In determining a diagnosis, it’s important for doctors to look at other symptoms or factors. Swollen lymph nodes near the ear may indicate an ear infection, for instance. Swollen glands in the neck area near the collarbone, combined with a sore throat and cough, may be a sign of an upper respiratory infection. When multiple regions of lymph nodes are swollen, it may indicate a body-wide disease that needs immediate attention.

Besides reviewing your medical history, doctors may use some of the following methods to diagnose the cause of swollen lymph nodes:

  • Physical examination, feeling with fingers the nodes in the affected area to check their size and whether they feel hard, tender or warm
  • Lab tests, including blood tests to check for suspected underlying conditions
  • Imaging tests, including an X-ray, computed tomography (CT) scan, magnetic resonance imaging (MRI) or ultrasound test
  • Biopsy to remove sections of lymph tissue or an entire lymph node to examine under a microscope

Cancer in the lymph nodes

In rare cases, lymph node swelling may be related to cancer. Some cancers start in the lymph nodes. Non-Hodgkin lymphoma and Hodgkin lymphoma are types of lymph system cancers, as is acute lymphocytic leukemia.

More often, a cancer may appear in the lymph nodes as a metastasis, spreading from somewhere else in the body. Some cancer cells break off from a tumor and metastasize in another location. Those cancer cells may travel through the bloodstream and reach other organs, or go through the lymph system and reach lymph nodes. However, most of the cancer cells traveling through the bloodstream or lymph system will die or be killed off before they have a chance to metastasize, according to the American Cancer Society (ACS).

When cancer is present in a lymph node, a biopsy helps determine what type of cancer it is when the removed tissue or node is examined under a microscope. The cancer cells will look like the cancer cells of the tumor where they originated, so breast cancer cells in the lymphatic system will still look like breast cancer.

Lymph nodes and staging cancer

Oncologists use cancer staging to determine the extent of cancer in the body. Lymph nodes play an important role in one of the most commonly used staging systems, called TNM. The TNM system is based on the extent of the tumor (T), how much it has spread to nearby lymph nodes (N) and the presence of metastasis (M). Each letter is assigned a numerical value based on clinical observations.

If no cancer is found in the lymph nodes near the cancer, the N is assigned a value of 0. If nearby or distant nodes show cancer, the N is assigned a number that increases based on the number of nodes affected, the size and extent of the cancer, how large the nodes are and where they’re located. The numbers for each initial are added up. The higher the sum, the more advanced the cancer. The lower the TNM score, the easier it may be to treat.

Treatment for cancer in the lymph nodes

Treatment for cancer in the lymph nodes varies depending on the tumor size and location and whether the cancer has metastasized to other areas of the body.

Surgery may be used to treat some forms of metastatic cancer that has spread to the lymph nodes. Other treatment options for cancer in the lymph nodes may include chemotherapy, radiation therapy, a stem cell transplant, immunotherapy or targeted therapy.

There’s a higher risk for cancer to come back following surgery when a cancer has spread to lymph nodes. In those cases, chemotherapy or radiation therapy may be recommended after surgery.

Removing lymph nodes during cancer surgery is “highly unlikely” to weaken the patient’s immune system, because it is “large and complex and is located throughout the body,” the ACS says. Lymph node removal may leave the affected part of the body unable to drain off lymph fluid, which may lead to a fluid backup (lymphedema) and may become a continuing problem. The greater the amount of lymph nodes removed, the greater the chance for lymphedema to occur.