Lymphoma is cancer that starts in white blood cells called lymphocytes

Lymphoma begins when lymphocytes—a type of white blood cell that normally helps your immune system fight infection—become abnormal and multiply out of control. These cancer cells collect in lymph nodes (small bean-shaped organs throughout your body) and other parts of your immune system, forming tumors. Unlike some cancers that spread from one organ to another, lymphoma cells travel through the lymphatic system, which is why the disease can appear in multiple places at once.

Your lymphatic system includes lymph nodes, the spleen, bone marrow, and thymus gland. When lymphoma develops, cancer cells crowd out healthy immune cells in these organs, making it harder for your body to fight real infections. The disease can also move into the bloodstream and reach organs like the liver, lungs, or brain.

Key Takeaways

  • Lymphoma is cancer of lymphocytes, white blood cells that normally protect against infection, and it grows in lymph nodes and immune organs throughout the body.
  • The two main types are Hodgkin lymphoma and non-Hodgkin lymphoma, which behave differently and are treated differently.
  • Common early signs include swollen lymph nodes in the neck, armpit, or groin that don't go away, along with fever, night sweats, or unexplained weight loss.
  • Diagnosis requires a biopsy—a sample of tissue from a lymph node—because imaging alone cannot confirm lymphoma.
  • Lymphoma is not contagious and is not caused by anything you did or didn't do.

Hodgkin lymphoma versus non-Hodgkin lymphoma

The two main categories of lymphoma are named after Thomas Hodgkin, who first described the disease in 1832. Hodgkin lymphoma contains a specific type of abnormal cell called a Reed-Sternberg cell, which doctors can identify under a microscope. This type accounts for about 10 percent of all lymphomas and tends to spread in an orderly way from one lymph node group to nearby groups.

Non-Hodgkin lymphoma is actually a group of more than 60 different subtypes, all lacking the Reed-Sternberg cell. Non-Hodgkin lymphoma is more common overall and often spreads randomly to multiple organs rather than moving step-by-step through nearby nodes. The subtype matters because different types grow at different speeds and respond to different treatments.

Why lymphoma develops

Doctors do not fully understand what causes lymphoma to start. Unlike some cancers linked to smoking or sun exposure, lymphoma has no single preventable cause. Some people develop it after a viral infection or due to a weakened immune system, but most people with these risk factors never develop lymphoma, and many people who develop it have no known risk factors.

Certain conditions do raise the risk: people with HIV, those who have had an organ transplant and take immune-suppressing drugs, and people with autoimmune diseases like rheumatoid arthritis have higher rates. Age matters too—lymphoma can occur at any age, but some types are more common in older adults and others in younger people. Having a family member with lymphoma slightly increases risk, but lymphoma is not inherited in the way some genetic conditions are.

Early signs and symptoms

The most common early sign is one or more swollen lymph nodes that you can feel—usually in the neck, armpit, or groin. These nodes may be painless and firm, and they often don't shrink after a few weeks the way nodes swell and shrink during a normal infection. Many people notice the swelling by accident, while showering or getting dressed.

Other symptoms that may accompany swollen nodes include fever (sometimes coming and going), night sweats that soak through clothing, unexplained weight loss over weeks or months, fatigue, and itching skin. Some people have no symptoms at all and discover lymphoma only during imaging for an unrelated reason. The presence or absence of these "B symptoms" (fever, night sweats, weight loss) affects how doctors stage the disease and plan treatment.

How doctors diagnose lymphoma

A doctor who suspects lymphoma will order imaging—usually a CT scan—to see the size and location of swollen nodes. However, imaging alone cannot diagnose lymphoma because swollen nodes can have many causes. The only way to confirm lymphoma is a biopsy, in which a surgeon or radiologist removes a sample of tissue from a swollen lymph node and a pathologist examines it under a microscope to look for cancer cells and identify the type.

After diagnosis, additional tests determine how far the disease has spread. These may include blood tests, bone marrow biopsy, PET scan, or lumbar puncture (spinal tap) if the doctor suspects involvement of the nervous system. These tests help assign a stage—from stage 1 (limited to one area) to stage 4 (spread to multiple organs)—which guides treatment decisions.

How lymphoma differs from other blood cancers

Lymphoma is sometimes confused with leukemia, but they are different diseases. Leukemia is cancer of blood-forming cells in the bone marrow, and cancer cells circulate in the bloodstream from the start. Lymphoma is cancer of lymphocytes that collect in solid tumors in lymph nodes and organs. A person with lymphoma may have normal blood counts early on, whereas someone with leukemia typically has abnormal counts from the beginning.

Lymphoma also differs from multiple myeloma, which is cancer of plasma cells (another type of immune cell) that usually develops in bone marrow. The treatment approaches, prognosis, and how the disease behaves are distinct for each type of blood cancer.

What happens after diagnosis

Once lymphoma is confirmed and staged, your doctor will discuss treatment options. These may include chemotherapy, radiation, targeted drugs that attack specific cancer cells, immunotherapy that helps your immune system fight the cancer, or a combination of these. Some people with slow-growing lymphoma may not need immediate treatment and instead have regular monitoring—an approach called "watch and wait."

Treatment plans are tailored to the type and stage of lymphoma, your age, overall health, and whether you have B symptoms. Many people with lymphoma go into remission, meaning scans show no sign of cancer. Remission can last for years or, in some cases, indefinitely. Others may need treatment again if the cancer returns.

Frequently Asked Questions

Is lymphoma contagious?

No. Lymphoma is cancer, not an infection, and you cannot catch it from another person or pass it to someone else. It develops when your own cells become abnormal.

Can you have lymphoma without swollen lymph nodes?

Yes. Some people have lymphoma in the spleen, bone marrow, or other organs without obvious swollen nodes. Others have swollen nodes but no other symptoms. This is why imaging and biopsy are necessary for diagnosis.

Does lymphoma always require chemotherapy?

Not always. Some slow-growing lymphomas are monitored without immediate treatment. Others respond to targeted drugs or radiation alone. Your doctor will recommend a plan based on your specific type and stage.

What is the difference between remission and cure?

Remission means scans show no sign of cancer, but doctors usually avoid the word "cure" because lymphoma can sometimes return years later. Many people live long, healthy lives after lymphoma treatment, especially those diagnosed at earlier stages.

Can you get lymphoma twice?

Yes. Some people experience a relapse of the same lymphoma after remission. Others may develop a different type of cancer later. Your doctor will discuss the risk and monitoring plan specific to your situation.