Follicular lymphoma is a type of blood cancer that is part of a group of diseases called non-Hodgkin's lymphomas. It is one of the most common subtypes of non-Hodgkin's lymphoma. These cancers affect the lymphatic system, a part of the body's immune system. Specifically, follicular lymphoma affects B-lymphocytes, which are a type of white blood cell. The disease is called "follicular" lymphoma because the abnormal lymphocytes often collect in lymph nodes in clusters known as "follicles". Follicular lymphoma is usually a slow-growing or "indolent" lymphoma, but sometimes it can change into a faster-growing lymphoma.

Types of Follicular Lymphoma

Follicular lymphoma is classified into different types based on the grade of the disease. The grade is determined by the number of large cells seen when the biopsy is looked at under the microscope. The types of follicular lymphoma include:

• Grade 1: Fewer large cells are seen
• Grade 2: A moderate number of large cells are seen
• Grade 3: Many large cells are seen. This grade is further divided into 3A and 3B. In 3A, small cells are still present, but in 3B, only large cells are seen

Why Do People Get Follicular Lymphoma?

The exact cause of follicular lymphoma is not known. However, certain factors are believed to increase the risk of developing this disease. These include:

• Age: Follicular lymphoma is more common in older adults, with most people diagnosed in their 60s.
• Gender: Most non-Hodgkin lymphoma subtypes are more common in men compared to women. However, with follicular lymphoma, this ratio is much smaller or even reversed. Some studies show that women are more likely to get follicular lymphoma than men.
• Immune system disorders: Conditions that weaken the immune system, such as HIV/AIDS, can increase the risk.
• Exposure to certain chemicals: Certain pesticides and herbicides have been linked to an increased risk of follicular lymphoma.
• Family history: Having a close relative with follicular lymphoma may increase the risk, although the overall risk is still low as follicular lymphoma is not a common disease. In one study, a family history of non-Hodgkin lymphoma was associated with a 1.99-fold increased risk of follicular lymphoma. 

It's important to note that having one or more risk factors does not mean that a person will definitely develop follicular lymphoma. Many people with these risk factors never develop the disease, and many people who do develop follicular lymphoma have no known risk factors.

Who Gets Follicular Lymphoma?

According to the National Cancer Institute, there will be an estimated 15,000 new cases of follicular lymphoma in 2023. A study from 2016 estimated that there were 13,960 new cases of follicular lymphoma diagnosed in the United States, representing 12.4% of non-Hodgkin lymphomas. Rates of follicular lymphoma are highest in non-Hispanic white males. The median age at diagnosis is 64 years old. You may be at an increased risk of follicular lymphoma if you have HIV, rheumatoid arthritis, lupus, or celiac disease, which are all immune system disorders.

Want to Learn More About Follicular Lymphoma?

Keep reading HealthTree for Follicular Lymphoma's 101 pages!

• How Is Follicular Lymphoma Diagnosed?
• How Long Will I Live With Follicular Lymphoma?
• What Are The Signs And Symptoms Of Follicular Lymphoma?
• How Is Follicular Lymphoma Staged And Classified?
• What Are Treatments For Follicular Lymphoma?