What is diffuse large B-cell lymphoma (DLBCL)?

Diffuse large B-cell lymphoma (DLBCL) is a cancer of B cells. B cells are a type of lymphocyte, a white blood cell that makes antibodies to fight infection. B cells live in your lymph nodes, spleen, bone marrow, and other organs. In DLBCL, large B cells grow out of control and spread in sheets through a lymph node or organ. That is what "diffuse" means. It is the most common type of lymphoma in adults. It is an aggressive lymphoma, which means it grows fast, often over weeks to months.

When should I call my care team?

Fever of 100.4 F (38 C) or higher, or shaking chills; Confusion, trouble speaking, shaking, seizures, or being very hard to wake up, especially after CAR T-cell therapy or a bispecific antibody; Trouble breathing, chest pain, or a fast heartbeat; Swelling of the face, neck, or arms, or new trouble swallowing; Sudden back pain with leg weakness, numbness, or trouble controlling your bladder or bowels; Bleeding that will not stop, or new bruises or tiny red spots on the skin; Passing very little urine, or vomiting and diarrhea so bad you cannot keep fluids down; No bowel movement for 3 days, or severe belly pain; Dizziness or fainting; New severe headache or vision changes.

Diffuse large B-cell lymphoma (DLBCL)

DLBCL is a fast-growing lymphoma that needs treatment soon, and most people are cured with their first treatment.

Hi, I'm Rosa. Today we'll go through diffuse large B-cell lymphoma together, one step at a time. Doctors often call it DLBCL. I'll keep it simple, and you can pause me, go back, or skip ahead whenever you like. Just so you know, this is for learning only. It is not medical advice, so please check everything with your own doctor and care team. Okay, let's get started.

What DLBCL is

Let's start with the basics. Diffuse large B-cell lymphoma is a cancer of B cells. B cells are white blood cells that make antibodies to fight germs. It is the most common lymphoma in adults. It grows fast, often over weeks. The first sign is often a lump that grows quickly in the neck, armpit, or groin. It can also start in the stomach, bone, or other organs. Some people get fevers, soaking night sweats, or weight loss. Because it grows fast, treatment starts soon. Here is the good news. Most people are cured with their first treatment.

Types and related lymphomas

Let's talk briefly about the types. Most people have the common form. Double-hit lymphoma has changes in two genes. It can grow faster and may need different treatment. Another type starts in the middle of the chest, often in young adults. Sometimes a slow-growing lymphoma changes into this fast-growing one. This is called transformed lymphoma. When it starts in the brain, it is treated differently. Ask your care team which type you have.

Tests you may have

Now let's talk about tests. A biopsy is the key test. A surgeon or a needle takes a piece of a lymph node. The lab needs enough tissue for many tests. A PET-CT scan shows where the lymphoma is. Later, it shows how well treatment worked. Blood tests check your counts, liver, kidneys, and a protein called LDH. You will be tested for hepatitis and HIV. A heart test comes before one of the medicines. Some people need a brain scan or a spinal tap. Ask about saving sperm or eggs before treatment.

Stages and risk scores

Next up, let's talk about stages. The stage tells how far the lymphoma has spread. There are four stages. Stages 1 and 2 are early, or limited, stage. Stages 3 and 4 are advanced stage. A high stage does not mean it cannot be cured. Doctors also use a risk score called the IPI. It counts five things, like age, stage, and a blood test. A higher score means higher risk. People in every risk group can be cured. Your doctor will explain your stage and score.

Cell type and gene tests

Before we move to treatment, there are some things to know. Lab tests on your biopsy look for markers on the cells. Almost all of these lymphomas have a marker called CD20. Your main antibody medicine targets it. The lab also checks which kind of B cell it came from. Gene tests can show double-hit lymphoma. That result matters for your plan. You do not need to memorize them. Your doctor will tell you what your results mean.

Main treatment options

Now let's look at treatment. Most people get chemotherapy together with an antibody medicine. The plan is given every three weeks, usually for four to six rounds. For higher risk, one drug may be swapped for a newer targeted medicine. Some people also get radiation to one area. If the lymphoma comes back early, a treatment called CAR T may be next. It changes your own immune cells in a lab to fight the lymphoma. Other medicines bring your immune cells right to the lymphoma. A stem cell transplant is another option. Clinical trials are research studies that may offer new options too.

Side effects and what helps

Let's talk about side effects. Treatment can lower the cells that fight germs, about one week after each round. Most people get a shot to help. Call right away for a fever. Some medicines cause tingling in the hands and feet, and constipation. Tell your team early. The steroid can make it hard to sleep and raise blood sugar. Hair often falls out and grows back. After CAR T, watch for fever or confusion. A caregiver should stay with you and call right away. We have a whole side effects guide on this site.

Living well after treatment

Last, let's talk about living well. After treatment, you will have a scan and then regular checkups. Tell your team about new lumps, fevers, sweats, or weight loss. If the lymphoma comes back, it is usually in the first two years. If it does, there are good options. One medicine can affect the heart years later. So do not smoke, stay active, and keep your blood pressure in check. Ask when to get your vaccines again. Tiredness can last for months, and it is normal to feel worried. Support is there for you. Call right away for a fever or new confusion.

You did great today. That was a lot, and you took it one step at a time. Write down your questions and bring them to your next visit. Call your care team any time something worries you. Most people with this lymphoma are cured, and you are not alone in this.

Call your care team right away if you have

Fever of 100.4 F (38 C) or higher, or shaking chills
Confusion, trouble speaking, shaking, seizures, or being very hard to wake up, especially after CAR T-cell therapy or a bispecific antibody
Trouble breathing, chest pain, or a fast heartbeat
Swelling of the face, neck, or arms, or new trouble swallowing
Sudden back pain with leg weakness, numbness, or trouble controlling your bladder or bowels
Bleeding that will not stop, or new bruises or tiny red spots on the skin
Passing very little urine, or vomiting and diarrhea so bad you cannot keep fluids down
No bowel movement for 3 days, or severe belly pain
Dizziness or fainting
New severe headache or vision changes

Side effects: what helps

Sources

Quick answers

What is diffuse large B-cell lymphoma (DLBCL)?: Diffuse large B-cell lymphoma (DLBCL) is a cancer of B cells. B cells are a type of lymphocyte, a white blood cell that makes antibodies to fight infection. B cells live in your lymph nodes, spleen, bone marrow, and other organs. In DLBCL, large B cells grow out of control and spread in sheets through a lymph node or organ. That is what "diffuse" means. It is the most common type of lymphoma in adults. It is an aggressive lymphoma, which means it grows fast, often over weeks to months.
When should I call my care team?: Fever of 100.4 F (38 C) or higher, or shaking chills; Confusion, trouble speaking, shaking, seizures, or being very hard to wake up, especially after CAR T-cell therapy or a bispecific antibody; Trouble breathing, chest pain, or a fast heartbeat; Swelling of the face, neck, or arms, or new trouble swallowing; Sudden back pain with leg weakness, numbness, or trouble controlling your bladder or bowels; Bleeding that will not stop, or new bruises or tiny red spots on the skin; Passing very little urine, or vomiting and diarrhea so bad you cannot keep fluids down; No bowel movement for 3 days, or severe belly pain; Dizziness or fainting; New severe headache or vision changes.

Last updated: 2026-10-27. Medically reviewed by Veli Bakalov, MD, medical oncologist (October 2026). General education from Step by Step, the patient portal of HemeOncBuddy.