Understanding lymphoma

What lymphoma is, the difference between Hodgkin and non-Hodgkin lymphoma, slow-growing and faster-growing types, what the stages mean, and the tests you may have.

6 min read · last reviewed September 30, 2026

Hearing the word "lymphoma" can be a shock. You may not have known much about it before. The good news is that lymphoma is one of the most studied cancers, and treatments keep getting better. Learning a few key words can help you follow what your team is saying and ask the questions that matter to you.

Here is a plain-language guide.

Your lymphatic system

Your lymphatic system is part of your immune system. It is a network of thin tubes and small, bean-shaped glands called lymph nodes. You have lymph nodes in your neck, armpits, groin, chest and belly. The spleen, the tonsils and the bone marrow are part of this system too.

The lymphatic system carries white blood cells called lymphocytes. They help your body fight infection. There are two main kinds:

• B cells make antibodies, which mark germs for attack.
• T cells attack infected cells directly and help control the immune response.

What is lymphoma?

Lymphoma starts when some lymphocytes change and start to grow out of control. They build up, often in lymph nodes, which then get bigger. Because lymphocytes travel all over the body, lymphoma can also start in or spread to other places, such as the spleen, bone marrow, stomach or skin.

Common signs include:

• A painless lump in the neck, armpit or groin
• Feeling very tired
• Itching
• Cough or shortness of breath, if nodes in the chest are large

Your team may also ask about three signs called B symptoms: fevers with no clear cause, drenching night sweats, and losing weight without trying. These help your team understand the lymphoma and plan treatment.

Lymphoma is not caused by anything you did. It is also not contagious.

Hodgkin and non-Hodgkin lymphoma

There are two main groups. Doctors tell them apart by looking at the lymphoma cells under a microscope.

Hodgkin lymphoma has a special kind of large, abnormal cell called a Reed-Sternberg cell. It often starts in lymph nodes in the neck or chest and tends to spread from one group of nodes to the next. It is more common in young adults and in people over 60. Most people have the "classic" type.

Non-Hodgkin lymphoma is everything else. It is much more common and includes dozens of types. Most start in B cells. Some start in T cells.

Slow-growing and faster-growing lymphomas

Non-Hodgkin lymphomas are often sorted by how fast they grow.

Indolent (slow-growing) lymphomas grow over months or years. Follicular lymphoma is the most common one. Some people have no symptoms for a long time. These lymphomas often can't be removed completely, but they can usually be kept under control for many years. Some people don't need treatment right away.

Aggressive (faster-growing) lymphomas grow over weeks to months and usually need treatment soon. Diffuse large B-cell lymphoma is the most common one. "Aggressive" sounds scary, but these lymphomas often respond very well to treatment. For many people, treatment aims to get rid of the lymphoma completely.

Something you can do: Ask your team to write down the full name of your lymphoma type. It makes it much easier to find good information and support.

Stages in plain words

The stage describes where the lymphoma is in your body. Most lymphomas use a system with four stages. The diaphragm, the big breathing muscle under your lungs, is a key landmark.

• Stage 1: Lymphoma is in one lymph node area, or one area outside the nodes.
• Stage 2: Lymphoma is in two or more lymph node areas on the same side of the diaphragm (all above, or all below).
• Stage 3: Lymphoma is in lymph nodes both above and below the diaphragm, or in nodes above the diaphragm and the spleen.
• Stage 4: Lymphoma has spread more widely, such as into the liver, lungs or bone marrow.

You may also hear:

• "A" or "B": "B" means you have B symptoms. "A" means you don't. This letter is used mostly for Hodgkin lymphoma.
• "Bulky": A single large mass of lymphoma. This can change the treatment plan.
• "E": Lymphoma involves an organ outside the lymph nodes.

Stage 4 does not mean the same thing in lymphoma as it does in some other cancers. Many people with stage 3 or 4 lymphoma respond very well to treatment. The stage is just one piece of information. Your type of lymphoma matters at least as much.

Tests you may have

Biopsy. This is the most important test. A surgeon removes a whole lymph node (excisional biopsy) or takes small pieces with a needle (core biopsy). You usually get a local freezing or light sedation. A specialist studies the cells to find the exact type of lymphoma. This can take a week or more, which can be hard. The wait helps make sure the diagnosis is right.

PET-CT scan. You get a small injection of a sugar-like tracer, then lie still in a scanner. Lymphoma cells take up more of the tracer, so they "light up." This scan helps find the stage and is often repeated to see how treatment is working.

Blood tests. These check your blood counts, kidney and liver function, and a protein called LDH. You will also be tested for hepatitis B, hepatitis C and HIV. This is routine. Some lymphoma treatments can wake up a hidden hepatitis B infection, so your team needs to know.

Bone marrow biopsy. Sometimes a small sample is taken from the back of your hip bone with a needle to see if lymphoma is in the marrow. You get freezing first. Many people no longer need this, because the PET-CT scan gives enough information.

Heart and lung tests. Some treatments can affect the heart or lungs. You may have a heart scan (such as an echocardiogram) or breathing tests before treatment starts, so your team has a starting point.

Something you can do: Ask for copies of your results, or ask how to see them in your patient portal. Keep them in one folder.

Questions to ask your care team

• What type of lymphoma do I have? Is it Hodgkin or non-Hodgkin?
• Is it slow-growing or faster-growing?
• What stage is it? Do I have B symptoms or bulky disease?
• What other tests do I need, and why?
• When will we talk about my treatment plan?
• Who can I call if I have questions or feel worse before treatment starts?

This article is general information, not medical advice. Talk with your health care team about your own situation. In an emergency, call 9-1-1 or your local emergency number.

In an emergency, call 9-1-1 or your local emergency number.

General information, not medical advice. It does not replace your own care team. If you think you or someone else is having a medical emergency, call 9-1-1 or your local emergency number. If you are in crisis or thinking about suicide, call or text 9-8-8 (Canada and the US).

Back to Lymphoma