Overview

Follicular lymphoma is a type of lymphoma. Lymphoma is cancer that affects the lymphatic system. The lymphatic system is made up of organs, glands, tubelike vessels and clusters of cells called lymph nodes. It's part of the body's germ-fighting immune system. Follicular lymphoma can affect the lymph nodes, bone marrow and other organs.

There are many types of lymphoma. They are often divided into two categories: Hodgkin lymphoma and non-Hodgkin lymphoma. Follicular lymphoma is a type of non-Hodgkin lymphoma.

Follicular lymphoma gets its name from the fact that the cancer starts in the follicles of the lymph nodes. Lymph node follicles are groups of germ-fighting white blood cells that are inside each lymph node. When these white blood cells become cancer cells, they may build up in the lymph nodes and continue to gather in groups that look like follicles.

Follicular lymphoma tends to grow slowly. It's often not found until it affects many parts of the body. Treatment may include radiation therapy, chemotherapy, immunotherapy targeted therapy and CAR-T cell therapy.

Types

Types of follicular lymphoma include:

  • Classic follicular lymphoma.
  • In situ follicular B-cell neoplasm.
  • Duodenal-type follicular lymphoma.
  • Pediatric-type follicular lymphoma.

Symptoms

Follicular lymphoma grows slowly and may never cause symptoms.

When they happen, follicular lymphoma symptoms may include:

  • Painless swelling in the neck, armpit or groin.
  • Fatigue.
  • Fever.
  • Night sweats.
  • Losing weight without trying.
  • Feeling full quickly.

When to see a doctor

Make an appointment with a doctor or other healthcare professional if you have any symptoms that worry you.

Causes

It's not clear what causes follicular lymphoma. This cancer starts inside the follicle of a lymph node. A follicle is a group of cells inside the lymph node. The follicle contains germ-fighting white blood cells called B cells. When there is no infection to fight, the B cells rest in the follicle.

When an infection happens in the body, the follicle can form an area that helps train the B cells to fight the infection. As part of this process, the B cells go through changes that make them better at fighting the specific infection. The B cells also make a lot more B cells to help with the fight. Then the B cells go out into the body to help fight the infection.

Follicular lymphoma happens when something goes wrong during this training process. Changes happen that turn the B cells into cancer cells. The cancer cells don't learn to fight infections. Instead, they build up in the lymph nodes. They also can build up in other parts of the lymphatic system.

Follicular lymphoma can affect the:

  • Lymph nodes.
  • Bone marrow.
  • Spleen.
  • Liver.
  • Digestive tract.
  • Skin.

Risk factors

Factors that can increase the risk of follicular lymphoma include:

  • Older age. Follicular lymphoma can happen at any age. But it's most common in people 60 or older.
  • Race. White people are more likely to develop follicular lymphoma than are people of other races.
  • Having a family history of lymphoma. Having a relative with follicular lymphoma may increase your risk.

There is no known way to prevent follicular lymphoma.

Complications

Complications of follicular lymphoma can include transformation into a fast-growing lymphoma and complications from treatment.

Turning into a fast-growing lymphoma

Sometimes a follicular lymphomas can transform into a fast-growing lymphoma, such as diffuse large B-cell lymphoma. These lymphomas often have a worse prognosis and need stronger treatments.

Complications of treatment

Complications of follicular lymphoma treatment may include a decrease in bone density, toxicity from the medicines, reactivating viruses such as hepatitis B and C, and tumor lysis syndrome. Tumor lysis syndrome is a serious condition that can happen when cancer cells break down quickly after treatment. When these cells die, they release substances into the bloodstream that can overwhelm the body. This can lead to conditions that affect the kidneys and other organs.

June 19, 2025
  1. Elsevier Point of Care. Clinical Overview: Follicular lymphoma. https://www.clinicalkey.com. Accessed April 16, 2025.
  2. Freedman AS, et al. Clinical manifestations, pathologic features, diagnosis, and prognosis of follicular lymphoma. https://www.uptodate.com/contents/search. Accessed April 16, 2025.
  3. Hoffman R, et al. Clinical manifestations, staging, and treatment of follicular lymphoma. In: Hematology: Basic Principles and Practice. 8th ed. Elsevier; 2023. https://www.clinicalkey.com. Accessed April 16, 2025.
  4. Freedman AS, et al. Initial treatment of stage I follicular lymphoma. https://www.uptodate.com/contents/search. Accessed April 16, 2025.
  5. Freedman AS, et al. Initial treatment of stage II to IV follicular lymphoma. https://www.uptodate.com/contents/search. Accessed April 16, 2025.
  6. Freedman AS, et al. Treatment of relapsed or refractory follicular lymphoma. https://www.uptodate.com/contents/search. Accessed April 16, 2025.
  7. Jaffe ES, et al., eds. Hematopathology. 3rd ed. Elsevier; 2025. https://www.clinicalkey.com. Accessed April 16, 2025.
  8. Larson RA, et al. Tumor lysis syndrome: Prevention and treatment. https://www.uptodate.com/contents/search. Accessed April 16, 2025.
  9. Brudno JN, et al. CAR T cells and T-cell therapies for cancer. JAMA. 2024; doi:10.1001/jama.2024.19462.
  10. B-cell lymphomas. National Comprehensive Cancer Network. https://www.nccn.org/guidelines/guidelines-detail?category=1&id=1480. Accessed April 16, 2025.
  11. Harris KM. Allscripts EPSi. Mayo Clinic. April 23, 2025.
  12. Cancer stat facts: NHL — Follicular lymphoma. National Cancer Institute. https://seer.cancer.gov/statfacts/html/follicular.html. Accessed April 16, 2025.
  13. Kurz KS, et al. Follicular lymphoma in the 5th edition of the WHO-classification of haematolymphoid neoplasms — Updated classification and new biological data. Cancers. 2023; doi:10.3390/cancers15030785.