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PubMed This is a summary of 20 peer-reviewed journal articles Updated
Oncology

Understanding Your Reports: Subtypes, Grading, and Staging

At a Glance

Follicular lymphoma pathology reports classify the disease using three main metrics: Subtype (like Classic or Pediatric-type), Grade (how fast cells are dividing, from 1 to 3B), and Stage (where it is located, from I to IV). PET/CT scans are typically used to stage the disease and map its location.

When you receive a pathology report for follicular lymphoma (FL), it can feel like reading a foreign language. To make sense of it, doctors use three different “measuring sticks” to describe your specific case: Subtype (the personality of the cancer), Grade (how the cells look under a microscope), and Stage (where the cancer is in your body) [1][2].

The Three Main Subtypes

The World Health Organization (WHO) recently updated how we classify follicular lymphoma to better reflect how different versions of the disease behave [1][3].

  1. Classic Follicular Lymphoma (cFL): This is the most common form. It typically involves the t(14;18) translocation, which causes the cells to overproduce the BCL2 protein [1][4]. It can appear in lymph nodes throughout the body and usually follows an indolent (slow-growing) path [5][6].
  2. Pediatric-type Follicular Lymphoma (PTFL): Despite the name, this can also occur in young adults. It is almost always localized (found in only one spot, usually the head or neck) [7][8]. Crucially, it lacks the t(14;18) translocation and has an excellent outlook, often requiring less intensive treatment than the classic type [7][9].
  3. Duodenal-type Follicular Lymphoma (DTFL): This rare variant is found strictly in the small intestine (the duodenum) [10]. It often appears as tiny polyps or granules during an endoscopy [10][11]. It is exceptionally slow-growing and very rarely spreads to other parts of the body [10][12].

Grading: How the Cells Look

Grading is a way for pathologists to describe how “busy” the cancer cells appear. They look for large, fast-dividing cells called centroblasts [13][14].

Grade What it Means Centroblast Count per field (a high-power view under a microscope)
Grade 1 Low-grade; very slow-growing. 0–5 [13]
Grade 2 Low-grade; still slow-growing. 6–15 [13]
Grade 3A Higher grade; more centroblasts are present, but some smaller cells (centrocytes) remain. >15 [13][3]
Grade 3B Also called Follicular Large B-cell Lymphoma; cells are mostly large centroblasts. This is often treated more like an aggressive lymphoma [14][1]. Sheets of centroblasts [14]

Note: In the most recent medical guidelines, grading for “Classic” FL is sometimes considered optional because Grades 1, 2, and 3A are often treated the same way [1][3].

Staging: Creating a Map

While grading tells us about the cells, staging tells us about the location. Most doctors now use the Lugano classification, which relies on PET/CT scans to create a detailed map of the disease [15][2].

  • Stage I: The lymphoma is in only one lymph node region or one organ outside the lymph system [16][2].
  • Stage II: The lymphoma is in two or more groups of lymph nodes, but they are all on the same side of the diaphragm (the breathing muscle that separates your chest from your abdomen) [16][2].
  • Stage III: The lymphoma is in lymph node groups on both sides of the diaphragm [16].
  • Stage IV: The lymphoma has spread widely into organs outside the lymph nodes, such as the liver, lungs, or bone marrow [16][2].

The PET/CT scan is particularly helpful because it measures metabolic activity (how much sugar the cells are using). This is often reported as a Deauville score from 1 to 5, which helps your doctor see how active the lymphoma is and, later, how well it is responding to treatment [17][18][19]. Comprehensive staging helps ensure you aren’t over-treated if the disease is localized or under-treated if it is more widespread [17][20].

Common questions in this guide

What do the different grades of follicular lymphoma mean?
Grading describes how the lymphoma cells look under a microscope based on the number of fast-dividing cells called centroblasts. Grades 1, 2, and 3A are generally slow-growing. Grade 3B consists mostly of large cells and is often treated more like an aggressive lymphoma.
What does the t(14;18) translocation mean on my pathology report?
The t(14;18) translocation is a genetic change commonly found in Classic Follicular Lymphoma. It causes the cells to overproduce a protein called BCL2, which helps the cancer cells survive. Knowing this status helps your doctor confirm your exact subtype.
How do doctors determine the stage of my follicular lymphoma?
Doctors typically use PET/CT scans to stage follicular lymphoma from Stage I to Stage IV using the Lugano classification. This staging maps out whether the lymphoma is localized to one area, present on both sides of the diaphragm, or has spread to other organs like the liver or bone marrow.
What is a Deauville score on my PET scan?
The Deauville score is a scale from 1 to 5 used on PET/CT scans to measure the metabolic activity, or how much sugar the cells are using. This score helps your doctor see how active the cancer is and evaluate how well it is responding to treatment over time.
What is the difference between classic and pediatric-type follicular lymphoma?
Classic follicular lymphoma is the most common form and typically features the t(14;18) genetic marker. Pediatric-type follicular lymphoma lacks this marker, is usually found in just one localized spot, and generally has an excellent outlook requiring less intensive treatment.

Questions to Ask Your Doctor

Curated prompts to bring to your next appointment.

  1. 1.What is the specific grade (1, 2, 3A, or 3B) listed on my pathology report, and how does that affect my treatment plan?
  2. 2.Was my staging determined using a PET/CT scan, and if so, what was my Deauville score?
  3. 3.Do I have the 'Classic' type of follicular lymphoma, or one of the variants like Duodenal-type?
  4. 4.Does my pathology show the t(14;18) translocation and BCL2 expression?
  5. 5.Based on my stage (I, II, III, or IV), are we aiming for localized treatment like radiation or a 'watch and wait' approach?

Questions For You

Tap a prompt to share your answer — we'll use it plus this page's context to start a tailored conversation.

References

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This page explains follicular lymphoma pathology terminology for educational purposes. Your pathologist and oncologist are the best sources for interpreting your specific report.

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