Lymph Nodes

What are lymph nodes?

Lymph nodes are small structures that filter fluid (lymph) in your body. They function as a place for immune cells to look for and get rid of foreign substances, damaged cells and cancer cells. They’re part of your lymphatic system, which is also part of your immune system.

Lymph nodes are connected by tubes (lymphatic vessels) that collect excess fluid — lymph — from around your cells. As the lymph moves through your lymph nodes, immune cells destroy foreign invaders (like viruses and bacteria) and remove damaged, abnormal and cancerous cells. Then the lymph moves back into your lymphatic system and, eventually, back into your blood.

How many lymph nodes are in your body?

You have anywhere from 400 to 800 lymph nodes throughout your body. There’s no precise number that everyone has.

What do lymph nodes do?

Your lymph nodes are like a security checkpoint. They’re home to immune cells, whose job inside your lymph nodes includes:

• Looking for foreign invaders — like viruses, bacteria, parasites and fungi — and destroying them or marking them for other immune cells to destroy
• Removing damaged, abnormal or cancerous cells

Your immune cells do this by filtering lymph — fluid that leaks from your blood vessels and contains proteins, minerals, nutrients, damaged or diseased cells and foreign substances.

Lymph drains from your lymph vessels into your lymph nodes. As lymph moves through the node, immune cells work on marking, destroying and removing pathogens (germs) and damaged cells. The “cleaned” lymph then moves out of the node and on through the lymphatic system, until it makes its way back to your bloodstream.

Where are lymph nodes located in your body?

You have lymph nodes all over your body. There are lymph node clusters located:

• Behind your ear (mastoid), around your jaw (parotid) and at the base of your skull (occipital)
• Around the sides of your neck (cervical and supraclavicular)
• In your armpits (axillary)
• In the middle of your chest (mediastinal, aortic and hilar)
• In your abdomen and pelvis (paraaortic, mesenteric and iliac)
• In your groin (inguinal)

There are no lymph nodes in your brain or spinal cord.

Lymph node anatomy

Lymph nodes are shaped like beans or ovals. Each lymph node has several layers:

• Capsule. This is a protective outer shell.
• Subcapsular sinuses. These are spaces between the capsule and the cortexes (cortices).
• Cortex. There are multiple cortices in the outermost layer of lymph nodes, just below the subcapsular sinuses.
• Medulla. This is the innermost area of the lymph node.

Immune cells — like B cells, T cells, macrophages and dendritic cells — are found in the cortex and medulla.

Lymph nodes also connect to:

• Afferent lymphatic vessels. These tubes carry lymph into the node.
• Efferent lymphatic vessels. These tubes carry the lymph out of the node.
• Blood vessels. These move blood in and out of the lymph node.

Lymph enters the node through lymphatic vessels, through the sinuses, cortex and medulla (where immune cells do their work), then back out of the node through lymphatic vessels on the other side.

What are the common conditions and disorders that affect lymph nodes?

Most commonly, conditions that affect your lymph nodes cause them to swell and sometimes become painful. You might also have a fever, flu-like symptoms or night sweats.

Conditions that can affect your lymph nodes include:

• Infections (like viral or bacterial infections)
• Cancers like lymphoma and leukemia
• Castleman disease, a condition that causes noncancerous growths in your lymph nodes
• Kikuchi-Fujimoto disease, long-lasting but temporary lymph node swelling that can look like lymphoma
• Lymphangioleiomyomatosis (LAM), a lung disease that can cause growths in your lymph nodes
• Lymphoproliferative disorders, conditions that cause your body to make too many white blood cells
• Mesenteric lymphadenitis, swelling of your abdominal lymph nodes

Any infection can cause swollen lymph nodes — it can be a sign that your body is fighting off the germs. A common example is strep throat, which usually causes swollen, tender lymph nodes in the front of your neck. Other infections can cause different patterns of swollen lymph nodes in your body. Some examples include:

• Cat scratch fever
• Elephantiasis (lymphatic filariasis)
• Nontuberculosis mycobacterial infections
• Lyme disease
• HIV
• Mononucleosis

There are some locations in your body where swollen lymph nodes can be a sign of serious disease. You should check with a medical provider if you have noticeable or painful lymph nodes in your elbow or upper chest, above your collarbone. If you notice any swollen lymph nodes that are persistent, painful or accompanied by other symptoms (like fever, fatigue or unexplained weight loss), it’s important to seek medical advice.

Tests

A healthcare provider usually starts with an exam to look at or feel your lymph nodes and see if they’re swollen or hard. Tests they might use to diagnose issues that affect your lymph nodes include:

• Imaging like ultrasound, CT scans, X-rays, MRI and PET scans
• Blood tests, like a complete blood count (CBC)
• Lymph node biopsy

Treatments

Generally, lymph nodes themselves aren’t treated. This is common if your provider determines that the lymph node has no concerning features and if it goes away on its own.

But sometimes, conditions that affect your lymph nodes need treatment. Depending on what’s causing issues with your lymph nodes, your provider might recommend:

• Antibiotics, antivirals or antiparasitics for infections
• Chemotherapy, radiation therapy or immunotherapy for cancer
• Surgery to remove lymph nodes (lymphadenectomy)

They may also suggest applying a warm compress or taking over-the-counter medications if your lymph nodes are painful.

Are lymph nodes glands?

Not really. Glands are areas of your body that release chemicals or fluids your body uses, like hormones or sweat. Lymph nodes don’t do this. But people still sometimes call them “lymph glands” or say you have “swollen glands.”