Introduction: Who Should Undergo Diagnostics

If you notice painless swelling in your neck, armpit, or groin that doesn’t go away, it’s important to see your doctor. These swellings represent enlarged lymph nodes, which are small structures throughout your body that help fight infections. While swollen lymph nodes can happen for many reasons, including simple infections, persistent swelling needs to be checked out properly.^[1]

You should also seek medical attention if you experience other symptoms that don’t seem to have an obvious cause. These include feeling extremely tired all the time, having fevers that come and go without explanation, soaking night sweats that drench your sheets, or losing more than 10% of your body weight without trying. Doctors call this group of symptoms B symptoms, and they can be important warning signs.^[1][2]

Many people with follicular lymphoma don’t have any symptoms at all when they’re first diagnosed. The cancer can grow so slowly that it doesn’t cause noticeable problems for a long time. This is why follicular lymphoma is sometimes discovered during routine check-ups or when tests are done for completely different reasons. However, even without symptoms, it’s worth getting checked if you notice any persistent lumps or changes in your body.^[1][3]

People who already have a diagnosis of follicular lymphoma need regular follow-up diagnostics to monitor how the disease is behaving. Your healthcare team will schedule these check-ups to watch for changes that might mean the lymphoma is becoming more active or transforming into a faster-growing type.^[1]

Diagnostic Methods

Physical Examination

Your diagnostic journey typically begins with a thorough physical examination. Your doctor will carefully check for swollen lymph nodes in several areas of your body, including your neck, armpits, and groin. They’ll also feel your abdomen to check if your spleen or liver feels larger than normal. The spleen is an organ on your left side that’s part of your immune system, and it can become enlarged when lymphoma is present.^[14][22]

During this examination, your doctor will ask detailed questions about any symptoms you’ve been experiencing and how long you’ve had them. They’ll want to know about fevers, night sweats, weight loss, and fatigue. This conversation helps them understand the full picture of what’s happening in your body and guides them in deciding which tests to order next.^[2]

Lymph Node Biopsy

A biopsy is the only way to definitively diagnose follicular lymphoma. This procedure involves removing all or part of a swollen lymph node so that specialists can examine it under a microscope. There are different types of biopsies, and the one you have will depend on where the swollen lymph node is located and how large it is.^[1][14][22]

In some cases, doctors may remove an entire lymph node through a small surgical procedure. This is called an excisional biopsy and often provides the most complete information. In other situations, they might take just a small sample using a needle, though this may not always provide enough tissue for a complete diagnosis. Your doctor will discuss which approach is best for your situation.^[1][6]

Once the tissue sample reaches the laboratory, pathologists—doctors who specialize in diagnosing diseases by looking at cells and tissues—examine it closely. They look for specific patterns of abnormal cells and determine the grade of your lymphoma. The grade tells doctors how the cancer cells look and helps predict how they might behave. Follicular lymphoma is divided into grades 1, 2, 3A, and 3B, depending on how many large abnormal cells called centroblasts are present and whether smaller cells called centrocytes are also there.^[6][15][17]

The cells are also tested to see which proteins they express on their surface. Follicular lymphoma cells typically show certain markers including CD19, CD20, CD10, BCL2, and BCL6. These markers help confirm the diagnosis and distinguish follicular lymphoma from other types of cancer. Most cases of follicular lymphoma also have a specific genetic change called t(14;18) translocation, which can be detected through special laboratory tests.^[15]

Blood Tests

Blood tests play several important roles in diagnosing and staging follicular lymphoma. Your doctor will order blood tests to check your overall health, look at your blood cell counts, and rule out other conditions that might cause similar symptoms. These tests show how many red blood cells, white blood cells, and platelets you have. Low counts might indicate that lymphoma has affected your bone marrow, where blood cells are made.^[1][14][22]

One specific blood test measures a substance called lactate dehydrogenase or LDH. Higher levels of LDH can sometimes indicate that the lymphoma is growing more actively or might be transforming into a more aggressive type. However, LDH can be elevated for many reasons, so it’s just one piece of information among many.^[14][22]

Blood tests can also check your kidney and liver function, which is important for planning treatment. They help your medical team understand how well your organs are working before starting any therapy. Some blood tests look at your immune system function and check for infections that might need to be treated before lymphoma therapy begins.^[1]

Imaging Tests

Imaging tests create detailed pictures of the inside of your body and are essential for staging follicular lymphoma. Staging means figuring out how far the cancer has spread and which parts of your body are affected. In stage III follicular lymphoma specifically, cancer has spread to lymph nodes on both sides of your diaphragm—the muscle that separates your chest from your abdomen.^[1][4][9]

A CT scan (computed tomography scan) uses X-rays taken from different angles to create detailed cross-sectional images of your body. This test can show enlarged lymph nodes in your chest, abdomen, and pelvis. You may be asked to drink a contrast liquid before the scan or have contrast dye injected into your vein. This contrast helps certain areas show up more clearly on the images. The scan itself is painless, though some people feel slightly claustrophobic lying still in the scanner for 15 to 30 minutes.^[1][4][9]

A PET scan (positron emission tomography scan) works differently. You receive an injection of a small amount of radioactive sugar, and then special cameras detect where this sugar collects in your body. Cancer cells use more energy than normal cells, so they absorb more of the radioactive sugar and light up on the scan. PET scans are particularly good at showing whether lymph nodes are enlarged because of active lymphoma or for other reasons. Often, PET and CT scans are combined into one test called a PET-CT scan, which gives both types of information at once.^{[1][4][9][17]}

Some doctors may also order an MRI (magnetic resonance imaging) scan, which uses powerful magnets and radio waves instead of X-rays to create detailed images. MRI scans are particularly useful for looking at certain parts of the body, such as the brain or spinal cord, if there’s concern that lymphoma might have spread to these areas.^[14][22]

Bone Marrow Biopsy

A bone marrow biopsy is an important test for staging follicular lymphoma because this cancer frequently spreads to the bone marrow. More than half of people with follicular lymphoma have lymphoma cells in their bone marrow by the time they’re diagnosed. Bone marrow is the spongy tissue inside bones where new blood cells are made.^{[1][14][17][22]}

During this procedure, a doctor removes a small sample of bone marrow, usually from your hip bone. The area is numbed with local anesthetic first, so you should feel pressure but not sharp pain. There are actually two parts to this test: bone marrow aspiration, where liquid marrow is drawn out with a needle, and bone marrow biopsy, where a small piece of the solid bone marrow tissue is removed. Both samples are examined in the laboratory to look for lymphoma cells.^[14][22]

Finding lymphoma cells in the bone marrow helps determine your stage and can affect treatment decisions. It also explains why some people have low blood counts—if the bone marrow is crowded with lymphoma cells, it can’t make enough normal blood cells. The procedure takes about 20 to 30 minutes, and you might feel sore at the biopsy site for a few days afterward.^[1][17]

Diagnostics for Clinical Trial Qualification

If you’re considering joining a clinical trial—a research study testing new treatments for follicular lymphoma—you’ll need to undergo specific diagnostic tests to see if you qualify. Clinical trials have strict entry requirements called eligibility criteria, and thorough testing ensures that the trial is safe for you and that researchers can accurately measure whether the treatment works.^[1]

Most clinical trials for follicular lymphoma require confirmation of your diagnosis through a biopsy reviewed by a pathologist. The trial may even require that your biopsy slides be sent to a central laboratory where specialized pathologists review them to confirm the diagnosis and grade. This ensures that all patients in the trial truly have the same type and grade of lymphoma, which makes the study results more reliable.^[6][15]

Imaging tests are almost always required before you can enter a clinical trial. Researchers need baseline scans—images taken before treatment starts—so they can compare them to scans taken later to see if the treatment is working. Trials typically require PET-CT scans because these provide the most detailed information about disease location and activity. These baseline scans help establish what’s called your “tumor burden,” meaning how much disease you have at the start.^[1][4][9]

Blood tests for clinical trials are usually more extensive than those done for routine diagnosis. Researchers need to document your blood counts, organ function, and various other measurements before treatment begins. Some trials test for specific genetic markers or proteins in your blood that might predict how you’ll respond to the experimental treatment. For example, trials testing new targeted therapies might require tests to see if your lymphoma cells have the specific target that the drug is designed to attack.^[1][15]

A bone marrow biopsy is often required for clinical trial entry, even if you’ve already had one for your initial diagnosis. Trials may need fresh samples to perform special tests on your lymphoma cells. These tests might look at the genetic makeup of your cancer cells or measure how many of them are actively dividing, information that helps researchers understand why treatments work for some people but not others.^[14][17][22]

Clinical trials may also require tests to confirm your overall fitness and ability to tolerate the experimental treatment. These can include heart function tests like an electrocardiogram (ECG) or echocardiogram to make sure your heart is healthy enough for certain drugs. Lung function tests might be needed if the treatment could affect breathing. These protective measures ensure your safety throughout the trial.^[14]

Understanding Stage III Follicular Lymphoma

When your diagnostic tests are complete, your doctor will assign a stage to your lymphoma. Stage III follicular lymphoma means that cancer has been found in lymph nodes on both sides of your diaphragm. For example, you might have enlarged lymph nodes in your neck or chest (above the diaphragm) and also in your abdomen or groin (below the diaphragm). This is considered advanced disease, but it’s important to understand that “advanced” doesn’t mean the same thing with follicular lymphoma as it does with other cancers.^{[1][4][9][17]}

Follicular lymphoma is generally a slow-growing cancer, and even at stage III, many people live for many years with good quality of life. The staging system helps your doctor make treatment decisions, but it’s not the only factor they consider. They also look at whether you have symptoms, how the lymphoma is affecting your organs, your age, and your overall health. Together, these factors help create a personalized treatment plan.^[1][12]

Stage III is grouped with stage IV when doctors make treatment decisions because both are considered advanced stages and are often treated similarly. The specific treatments depend more on whether you have symptoms and how the disease is behaving than on whether it’s stage III or IV. Some people with stage III disease who don’t have troubling symptoms may not need immediate treatment and instead are monitored with regular check-ups in an approach called “watchful waiting” or “active surveillance.”^[4][9][11]