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Understanding Your Reports: Subtypes, Grading, and Staging

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Follicular lymphoma pathology reports use three main criteria to describe the cancer: the specific subtype (like Classic or Duodenal-type), the cell grade (how fast cells are dividing, from 1 to 3B), and the disease stage (where it is located in the body, from I to IV).

Key Takeaways

  • • Classic Follicular Lymphoma is the most common subtype and typically involves the t(14;18) genetic translocation.
  • • Grading measures how fast the cancer cells are dividing by counting large cells called centroblasts under a microscope.
  • • Grades 1, 2, and 3A are generally considered slow-growing, while Grade 3B is often treated as a more aggressive lymphoma.
  • • Doctors use the Lugano classification and PET/CT scans to determine if the lymphoma is localized (Stage I-II) or widespread (Stage III-IV).

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].

Frequently Asked Questions

What do the different grades of follicular lymphoma mean?
Grading describes how fast the cancer cells are dividing by counting large cells called centroblasts. Grades 1, 2, and 3A are generally slow-growing, while Grade 3B consists mostly of fast-dividing cells and is treated as a more aggressive lymphoma.
What is the Lugano classification for follicular lymphoma staging?
The Lugano classification is a staging system that maps where the lymphoma is located in your body. It ranges from Stage I, meaning the cancer is in one lymph node region, to Stage IV, meaning it has spread to organs outside the lymph system like the liver or bone marrow.
Why do I need a PET/CT scan for my diagnosis?
A PET/CT scan measures the metabolic activity of the lymphoma cells, often reported as a Deauville score. This detailed imaging helps your doctor accurately stage the disease to ensure you receive the right level of treatment.
What is the t(14;18) translocation 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 and grow.
Is Pediatric-type Follicular Lymphoma only found in children?
No, despite its name, pediatric-type follicular lymphoma can also occur in young adults. It is usually found in only one localized spot, like the head or neck, and generally has an excellent outlook.

Questions for Your Doctor

  • • What is the specific grade (1, 2, 3A, or 3B) listed on my pathology report, and how does that affect my treatment plan?
  • • Was my staging determined using a PET/CT scan, and if so, what was my Deauville score?
  • • Do I have the 'Classic' type of follicular lymphoma, or one of the variants like Duodenal-type?
  • • Does my pathology show the t(14;18) translocation and BCL2 expression?
  • • 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

  • • Did my doctor mention if my lymphoma is localized to one area (like the head/neck or intestines) or if it's in multiple places?
  • • How was my diagnosis made—was it a needle biopsy or did they remove an entire lymph node? (Whole-node biopsies are often more accurate for grading).
  • • Have I had a PET/CT scan yet to 'map out' where the lymphoma is located?

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This page explains follicular lymphoma pathology and staging terms for educational purposes. Your oncologist and pathologist are the best sources for interpreting your specific report and discussing your treatment plan.

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