Introduction: Who Should Seek Diagnostic Testing

Follicular lymphoma often develops quietly, and many people do not experience noticeable symptoms at first. This slow-growing nature means that the disease can progress for some time before it is discovered. However, anyone who notices certain warning signs should consider seeking medical evaluation.^[1][2]

The most common reason to see a doctor is the appearance of painless swelling in specific areas of the body. These swellings typically occur in the neck, armpit, or groin and are caused by enlarged lymph nodes—small glands that are part of the body’s immune system. Unlike swollen glands caused by infections, these lumps usually do not hurt and do not go away on their own. If a lump persists for several weeks, it is important to have it checked by a healthcare professional.^[1][3]

Other symptoms that should prompt a visit to the doctor include ongoing tiredness that does not improve with rest, unexplained weight loss (especially losing more than 10% of body weight over six months), fever without an obvious infection, and heavy sweating at night that drenches clothing or bedding. Some people may also feel full quickly after eating small amounts of food, or experience discomfort in the abdomen if lymph nodes or the spleen become enlarged.^[1][4]

It is worth noting that follicular lymphoma is sometimes discovered by accident during routine blood tests or imaging scans performed for other reasons. Because symptoms can be mild or absent, many people are diagnosed only after a doctor notices something unusual during a check-up for another health issue.^[3][5]

Certain groups of people are more likely to develop follicular lymphoma, although it can affect anyone. The disease is more common in adults over the age of 60, and people who are white are diagnosed more often than those of other racial backgrounds. If you are in one of these groups and notice any of the symptoms mentioned above, it is especially important to seek medical advice.^[2][4]

Classic Diagnostic Methods

The process of diagnosing follicular lymphoma involves several steps, starting with a physical examination and progressing to more specialized tests. Each test helps doctors confirm whether the disease is present, understand its characteristics, and distinguish it from other conditions that may cause similar symptoms.^[4][9]

Physical Examination and Medical History

When you first visit a doctor with concerns about possible lymphoma, they will begin by asking detailed questions about your symptoms and medical history. The doctor will want to know if you have noticed any lumps, how long they have been there, whether they are painful, and if they have changed in size. They will also ask about other symptoms such as fatigue, fever, night sweats, and weight loss.^[4]

Your doctor will also inquire about your past health, including any previous cancer diagnoses, exposure to chemicals or radiation, immune system disorders like HIV or rheumatoid arthritis, and whether you have had an organ transplant. Family history of lymphoma may also be discussed, as it can sometimes increase risk.^[4]

During the physical exam, the doctor will carefully check for swollen lymph nodes in your neck, armpits, and groin. They will also feel your abdomen to see if your spleen or liver is enlarged, which can happen when lymphoma affects these organs.^[9]

Lymph Node Biopsy

A biopsy is the only definitive way to diagnose follicular lymphoma. This procedure involves removing all or part of a swollen lymph node so that it can be examined under a microscope by a specialist. The biopsy is essential because it allows doctors to see the cancer cells and understand their characteristics.^[3][9]

There are different types of biopsies. An excisional biopsy removes the entire lymph node and is the preferred method because it provides the most tissue for testing. Sometimes, if the lymph node is hard to reach, doctors may use a thin needle to remove a small sample of tissue through the skin. This is called a fine-needle aspiration or a core needle biopsy. These procedures are usually done on an outpatient basis, meaning you do not need to stay in the hospital overnight. The area may be numbed with a local anesthetic to reduce discomfort.^[4][9]

Once the tissue sample is collected, it is sent to a laboratory where pathologists examine the cells under a microscope. They look for the typical pattern of follicular lymphoma, in which cancer cells form clumps that resemble the normal follicles found in lymph nodes. The pathologist will also perform special tests to confirm the diagnosis and determine the grade of the lymphoma.^[5][8]

Grading the Lymphoma

Follicular lymphoma is classified into different grades based on how the cells look under the microscope. The grade tells doctors how quickly the lymphoma is likely to grow. Grades 1, 2, and 3A are considered low-grade, meaning they grow slowly. Grade 3B is faster-growing and is treated more like an aggressive lymphoma.^[8][11]

Understanding the grade is important because it helps doctors decide on the best treatment approach. Lower-grade lymphomas may not require immediate treatment, while higher-grade forms may need more aggressive therapy.^[8]

Blood Tests

Blood tests are an important part of the diagnostic process, even though they cannot confirm follicular lymphoma on their own. These tests help doctors rule out infections or other conditions that might cause similar symptoms. They also provide information about your overall health and how well your organs are functioning.^[4][9]

One specific blood test measures levels of lactate dehydrogenase (LDH), an enzyme that can be elevated when lymphoma is present or when it is changing to a more aggressive type. High LDH levels may suggest that the disease is more advanced or transforming.^[9]

Blood tests can also detect anemia (low red blood cell count), low platelet counts, or other abnormalities that may occur if the lymphoma affects the bone marrow.^[1][3]

Imaging Tests

After a biopsy confirms the diagnosis of follicular lymphoma, doctors use imaging tests to see where the disease is located in the body and how far it has spread. These tests create detailed pictures of the inside of the body and help with staging—determining the extent of the cancer.^[9]

CT scans (computed tomography scans) use X-rays and a computer to create cross-sectional images of the body. They are commonly used to check the chest, abdomen, and pelvis for enlarged lymph nodes or involvement of other organs.^[2][9]

PET scans (positron emission tomography scans) use a small amount of radioactive sugar injected into the body. Cancer cells absorb more sugar than normal cells, so they show up as bright spots on the scan. PET scans are often combined with CT scans (called a PET-CT scan) to provide detailed information about both the location and activity of the lymphoma.^[2][9]

MRI (magnetic resonance imaging) may be used in certain situations to get more detailed images of soft tissues, although it is less commonly used for follicular lymphoma than CT or PET scans.^[9]

Bone Marrow Biopsy

A bone marrow biopsy is often performed to see if the lymphoma has spread to the bone marrow, the soft tissue inside bones where blood cells are made. This test involves using a needle to collect a small sample of bone marrow, usually from the hip bone. The procedure is typically done with local anesthesia to numb the area, and the sample is sent to a lab for examination.^[9]

Finding lymphoma cells in the bone marrow indicates more advanced disease. Bone marrow involvement can also cause symptoms such as anemia, easy bruising, or increased risk of infections due to low blood cell counts.^[1][9]

Staging the Disease

Once all the diagnostic tests are complete, doctors assign a stage to the lymphoma. Staging describes how much of the body is affected by the cancer and ranges from Stage I (limited disease) to Stage IV (widespread disease).^[2][8]

• Stage I: Cancer is found in one or more lymph nodes in a single area.
• Stage II: Cancer is in lymph nodes in two or more areas, either above or below the diaphragm (the muscle that separates the chest from the abdomen).
• Stage III: Cancer is in lymph nodes on both sides of the diaphragm.
• Stage IV: Cancer has spread beyond the lymph nodes to other organs, such as the bone marrow, liver, or lungs.

Because follicular lymphoma often does not cause symptoms in the early stages, most people are diagnosed with Stage III or Stage IV disease. However, even advanced-stage follicular lymphoma is often slow-growing and may not require immediate treatment.^[2][8]

Additional Laboratory Tests

Once lymphoma cells are obtained from a biopsy or bone marrow sample, they undergo additional laboratory testing to provide more detailed information about the disease. These tests look at the genetic and molecular features of the cancer cells.^[9]

One important test checks for a specific genetic change called the t(14;18) translocation, which is found in about 85% to 90% of follicular lymphoma cases. This genetic abnormality causes the overproduction of a protein called BCL2, which helps cancer cells survive longer than they should.^[6][11]

Other tests may look for mutations in genes such as KMT2D, CREBBP, or EZH2, which are commonly altered in follicular lymphoma. Although these genetic tests do not always change the treatment plan, they help doctors better understand the disease and may be useful for research or future treatment decisions.^[11]

Diagnostics for Clinical Trial Qualification

Clinical trials are research studies that test new treatments or combinations of treatments to see if they are safe and effective. For people with follicular lymphoma, participating in a clinical trial can provide access to cutting-edge therapies that are not yet available to the general public. However, not everyone qualifies for every trial. Clinical trials have strict criteria, called eligibility criteria, that determine who can participate.^[3][10]

To determine if a patient is eligible for a clinical trial, doctors perform a series of diagnostic tests. These tests ensure that the patient has the right type and stage of lymphoma, that their overall health is good enough to tolerate the experimental treatment, and that they do not have other medical conditions that could interfere with the study.^[11]

Confirming the Diagnosis and Grade

The first step in qualifying for a clinical trial is confirming the diagnosis of follicular lymphoma through a biopsy. The tissue sample is reviewed by a pathologist to ensure that the patient has the specific subtype of lymphoma that the trial is studying. The grade of the lymphoma is also verified, as some trials only accept patients with certain grades.^[11]

In some cases, the trial may require a fresh biopsy, even if the patient was diagnosed months or years earlier. This is because the characteristics of the lymphoma can change over time, especially if it transforms into a more aggressive form.^[11]

Staging and Imaging

Clinical trials often require up-to-date staging information to ensure that the patient’s disease meets the trial’s criteria. This typically involves recent CT scans, PET scans, or both. Some trials are designed for patients with early-stage disease, while others are for those with advanced or relapsed lymphoma.^[10][11]

PET-CT scans are particularly important in clinical trials because they not only show where the lymphoma is located but also measure how active the cancer cells are. This information helps researchers track how well the treatment is working during the trial.^[11]

Blood Tests and Organ Function

Before joining a clinical trial, patients undergo a full set of blood tests to check their overall health. These tests measure kidney and liver function, blood cell counts, and levels of certain proteins or enzymes. Patients must have adequate organ function to participate in most trials, as many experimental treatments can place additional strain on the body.^[11]

For example, some trials require a minimum platelet count or hemoglobin level to ensure that the patient can safely tolerate the treatment. Others may exclude patients with impaired kidney or liver function if the drug being tested is processed by these organs.^[11]

Bone Marrow Assessment

Many clinical trials require a bone marrow biopsy to determine whether the lymphoma has spread to the bone marrow. This information is important for staging and for assessing how the disease might respond to treatment. Some trials specifically enroll patients whose bone marrow is affected, while others may exclude them.^[9][11]

Molecular and Genetic Testing

Certain clinical trials focus on patients whose lymphoma has specific genetic or molecular features. For example, some studies may only accept patients with the t(14;18) translocation or those with mutations in particular genes. In these cases, the biopsy sample is tested for these features before the patient can enroll.^[11]

As researchers learn more about the biology of follicular lymphoma, molecular testing is becoming increasingly important in matching patients to the most appropriate clinical trials. These tests help identify which treatments are most likely to work for a specific patient based on the unique characteristics of their cancer.^[11]

Performance Status

In addition to medical tests, clinical trials often assess a patient’s performance status, which is a measure of how well they can carry out daily activities. Doctors use standardized scales to evaluate whether the patient is active and able to care for themselves, or whether they are more limited in what they can do. Many trials require patients to have a good performance status because experimental treatments can be demanding.^[11]

Previous Treatment History

Some clinical trials are designed for patients who have never been treated for lymphoma, while others are for those whose lymphoma has returned after previous treatment. Doctors will review the patient’s treatment history, including what therapies they have received and how well those treatments worked. This information helps determine whether the patient is a good fit for the trial.^[10][11]