What is Grade 3B Follicular Lymphoma?

Grade 3B follicular lymphoma is a distinct, fast-growing (aggressive) subtype of follicular lymphoma that requires a completely different treatment approach than lower-grade versions of the disease. While grades 1, 2, and 3A are generally considered slow-growing (indolent) and are often managed as chronic conditions, grade 3B behaves much more like a cancer called Diffuse Large B-Cell Lymphoma (DLBCL) ^[1][2]. Because of this, it is typically treated immediately with stronger, more intensive chemotherapy ^[1][3]. Most importantly, unlike lower-grade follicular lymphomas, this intensive treatment is generally given with the goal of completely curing the disease ^[1][2].

How is Grade 3B Different?

Follicular lymphoma is graded by pathologists who look at a biopsy sample under a microscope and count specific types of cells. They are looking for centroblasts, which are large, fast-dividing lymphoma cells.

• Grades 1, 2, and 3A: These grades have fewer centroblasts mixed in with smaller, slower-growing cells called centrocytes. Because the slower-growing cells make up a significant portion of the tumor, the cancer usually progresses slowly ^[4][5].
• Grade 3B: In this grade, pathologists see solid sheets of centroblasts with very few or no smaller, slow-growing cells ^[4][5][6]. The tumor is almost entirely made up of these fast-dividing cells, which causes the cancer to grow more aggressively.

Because grade 3B can sometimes exist right alongside other grades of lymphoma or DLBCL in the same lymph node, doctors often prefer an excisional biopsy (removing the whole lymph node) rather than a needle biopsy to ensure they get an accurate picture of the disease ^[2][7].

Why is it Treated Like DLBCL?

Hearing that a cancer is “aggressive” can be frightening, especially if you previously read that follicular lymphoma is slow-growing. However, in the world of lymphoma, aggressive means the cells are dividing rapidly. Chemotherapy drugs are specifically designed to target and destroy rapidly dividing cells.

Because grade 3B behaves so much like DLBCL, doctors usually use the same treatment strategy ^[3]. This involves intensive immunochemotherapy—a combination of immune-targeting drugs and traditional chemotherapy. The most common regimen is called R-CHOP, where the “R” stands for Rituximab, an antibody that specifically targets lymphoma cells ^[1][3].

Research shows that patients with grade 3B follicular lymphoma who are treated with these intensive regimens have clinical outcomes and survival rates that are very similar to patients with DLBCL ^[1][2]. The fast-growing nature of the cells makes them highly responsive to this aggressive treatment, which is why doctors aim for a cure rather than just managing symptoms.

Important Tests for Grade 3B

Because the treatment plan for grade 3B is intensive, confirming the diagnosis and understanding the tumor’s biology is crucial. Doctors often use specialized tests:

• Ki-67 Proliferation Index: This is a special stain used on the biopsy to show exactly what percentage of the cancer cells are actively dividing. A high Ki-67 score helps confirm that the tumor is fast-growing ^[8][9].
• PET/CT Scans: These imaging scans measure how much energy (glucose) the tumors are consuming, represented by a number called the SUV (Standardized Uptake Value). Fast-growing grade 3B tumors usually have higher SUV numbers, and these scans are very effective at predicting how well the treatment is working ^[10][11].
• Molecular Testing: Doctors may look for specific genetic rearrangements (like mutations in the MYC, BCL2, or BCL6 genes) in the cancer cells. Finding certain combinations of these mutations helps doctors understand just how aggressive the lymphoma is and if specialized therapies are needed ^[12][13][14].