An Overview of Lymph Nodes

Many people are familiar with the swollen lymph nodes that can accompany a sore throat, but there is much more to lymph nodes than being a symptom. Lymph nodes are an important part of the immune system, acting as "nodes" between the lymphatic vessels that span the body. Immune cells that are "parked" in these nodes stand ready to attack any bacteria, viruses, or other foreign substances that enter the body.

Like other parts of the body, lymph nodes are also susceptible to disease, such as infections, cancer, and trauma. Let's look at the role these nodes play in the day to day function of your body, as well as their role in disease.

Definition: Lymph Nodes

Lymph nodes are small, bean-shaped glands that are located along the lymphatic system (a system of vessels similar to arteries and veins that lymph fluid travels through).

Location and Structure

Lymph nodes are small "masses" of tissue that lie along the lymphatic vessels of the body. You can think of them as rest stops along the lymphatic highway. These highways are the routes that our immune response uses to survey the body, similar to how our blood system has highways that carry oxygen and nutrients to the body. You may think of lymph nodes in your neck when you think of lymph nodes, but these nodes are located throughout our bodies.

Examples of terms used to describe some of the locations of lymph nodes include:

• Cervical lymph nodes: These are the nodes you have likely felt in your neck when fighting a cold. Lymph nodes nearest the front of your neck are referred to as anterior cervical lymph nodes, and these are the nodes that most people have felt at some time. Behind these lie the posterior cervical lymph nodes, and at the base of your skull on the back of your neck like the occipital lymph nodes. Nodes in these latter two regions are often inflamed "swollen" when people contract infectious mononucleosis ("mono").

• Axillary lymph nodes: The term axillary nodes refers to the lymph node in your armpit. In the movie Terms of Endearment, it was these nodes that heralded breast cancer.
• Supraclavicular lymph nodes: These nodes can be felt when enlarged, just above the collarbone (clavicle). Most of the time, enlargement of these nodes signifies a serious underlying problem, and they should always be evaluated.
• Mediastinal lymph nodes: These lymph nodes like in your mediastinum, the area in the center of your chest between your lungs. People cannot feel these nodes, but imaging studies are often done to evaluate these nodes with conditions such as lung cancer and lymphoma.
• Inguinal lymph nodes: Inguinal lymph nodes are present in the groin region. Since they drain tissues from the feet to the groin, there are many reasons why these nodes can become inflamed. Most often they become swollen after an injury or infection in the legs, but may also be a sign of anything from a sexually transmitted disease to cancer. Keep in mind that most people experience swollen inguinal nodes at some time, and the vast majority of the time they are not a problem; they are only doing their job of catching viruses or bacteria that enter your body from a sore on your feet or legs.

• Retroperitoneal lymph nodes: These lymph nodes lie deep in the abdomen and can only be seen on imaging studies.
• Mesenteric lymph nodes: These nodes are similar to retroperitoneal nodes, lying deep in the abdomen.
• Pelvic lymph nodes: Unlike inguinal nodes, pelvic nodes lie deep in the pelvis and can only be seen on imaging studies.

Lymph Node Function

Lymph nodes work to as "sieves" or more like security guards to filter bacteria, viruses, parasites, other foreign material, and even cancer cells from the body. This is the reason that lymph nodes are evaluated in people with cancer, as this is the first place where cancer cells may be "caught" on their journey to explore and set up home elsewhere in the body.

"Swollen Glands"

Lymph nodes are well-known as the "swollen glands" people may note in their neck when they are fighting a cold or sore throat. If you are thin you may be able to feel lymph nodes in your groin as well. Not all lymph nodes are "palpable" which means that you cannot feel all of the lymph nodes in your body.

Conditions Involving Lymph Nodes

There are many conditions in which lymph nodes become involved. Doctors use the term "lymphadenopathy" to describe inflammation or swelling in these glands. A few of the potential causes of enlarged lymph nodes include:

• Infections: Since lymph nodes store the white blood cells that are our first line of defense against infection, they are often enlarged due to infections. Enlargement of lymph nodes with an infection can be good or bad. It is good in the sense that they are the powerhouses storing immune cells. In other words, enlargement of the lymph nodes may mean your body is doing its job to resolve ​an infection. We didn't always know this. An example is with the tonsils which are similarly immune tissue. For a long time, it was thought that removing the tonsils would help prevent strep throat. It is true that if an infection has severely damaged the glands, removing them is a good idea. But it was also found that removing the tonsils could result in infections farther down the line. What we were doing is removing the functional first place where bacteria would travel.
• Cancer: Lymph nodes are enlarged in many cancers and this can be related to cancer cells from a blood cancer such as lymphoma, or due to other cancers in the body which have spread. Cancer can spread both through the bloodstream and through the lymphatic channels. When a cancer begins to spread, it usually travels first to nearby lymph nodes. If a cancer is found in the lymph nodes, it is usually a higher stage, and tells doctors that, if a cancer has not spread to distant regions, it at least has the "intention" to do so. Therefore, lymph node positive cancers (depending on the type) are often treated more aggressively than cancers that haven't traveled to lymph nodes.
• Trauma: Since the lymph nodes are the rest stops for the "workers" or the white blood cells which clean up a site of trauma, they are often enlarged with any injury. You can think of the lymph nodes as being a truck stop near a natural disaster where the firemen and paramedics are hanging out ready to do their job.

Lymph Nodes in Lung Cancer

With lung cancer, cancer cells can spread through the lymphatic system and become trapped in lymph nodes. Determining which, if any, of these nodes contain cancer cells help doctors determine the stage of a cancer—that is, how far the cancer has spread. Subsequently, they can choose the best treatment.

Also Known As: lymph glands

Examples: To determine the stage of her lung cancer, Joan's doctor told her he would need to see if it had spread to any of her lymph nodes.