Tests for Lymphoma in Children

A biopsy is the only way to be sure of a lymphoma diagnosis. For a biopsy, doctors remove some or all of an abnormal lymph node or tumor. This is sent to a lab, where it is tested and looked at under a microscope.

There are different types of biopsies. The goal is to get a sample large enough to make an accurate diagnosis as quickly as possible, with as few side effects as possible.

Surgical (open) biopsy

In this procedure, doctors remove either an entire lymph node (excisional biopsy) or a small part of a larger tumor (incisional biopsy). This is done through a cut in the skin.

If it can be done, this type of biopsy is usually preferred because it almost always gives doctors enough of a sample to diagnose the exact type of lymphoma.

What to expect during the biopsy:

If the lymph node is near the skin surface, your child might be sedated and given numbing medicine at the biopsy site (local anesthesia) or they might be put into a deep sleep (general anesthesia). If the lymph node or tumor is inside the chest or abdomen, general anesthesia is typically needed.

Needle biopsy

A needle biopsy removes small pieces of tissue from an enlarged lymph node or tumor mass, using hollow needles. Surgery isn’t required, and the biopsy can often be done by numbing the area with local anesthesia and using medicine to make the child sleepy (sedation).

There are 2 main types of needle biopsy.

• Fine needle aspiration (FNA): A small amount of tissue is taken out (aspirated) using a thin, hollow needle attached to a syringe.
• Core needle biopsy: A slightly larger piece of tissue is removed using a larger needle.

If possible, most doctors don’t use needle biopsies when they strongly suspect lymphoma, because the needle doesn’t always remove enough tissue to make a definite diagnosis. But a needle biopsy might be used in some situations, especially if:

• The tumor is in the child’s chest, because putting a child into a deep sleep (general anesthesia) can sometimes be dangerous in this case
• Lymphoma is somewhere other than the lymph nodes, such as the bones
• Doctors need to check other parts of the body after lymphoma is diagnosed, to see if it has spread or come back after treatment

If your child’s care team suspects infection is the cause of the swollen lymph node, they might first do a needle biopsy. But your child might still need a surgical biopsy later, to diagnose and classify a lymphoma.

These tests can show if a lymphoma has reached the bone marrow. They are generally done at the same time. The samples are usually taken from a child’s pelvic bone (hip).

Before the tests, the skin over the child’s hip bone is cleaned, then numbed with a local anesthetic (injection) or a numbing cream. In most cases, they are also given medicine to make them drowsy or go to sleep.

Bone marrow aspiration: The doctor inserts a thin, hollow needle into the bone and uses a syringe to suck out a small amount of liquid bone marrow.

Bone marrow biopsy: A small piece of bone and marrow is removed by placing a slightly larger needle in the bone. Once the biopsy is done, pressure is applied to the site to help stop any bleeding.

The bone marrow samples are then sent to a lab to be tested and looked at under a microscope.

This test is used to look for cancer cells in the cerebrospinal fluid (CSF), which is the liquid that bathes the brain and spinal cord.

It is important for the child to be still during the procedure so it can be done safely and with minimal difficulty. Some older children might be able to have the test done while they are awake, but most of the time children will be given medicine to make them relax or go to sleep during the procedure. If the child needs to be under general anesthesia for other tests, the doctor might do the lumbar puncture at that time.

After cleaning the skin, the doctor will numb an area in the lower part of the child’s back near their spine, then insert a small, hollow needle between the bones of the spine to remove some of the fluid. This fluid is sent to the lab for testing.

Lumbar puncture for intrathecal chemotherapy

If your child is already diagnosed with lymphoma, doctors might use lumbar puncture to give chemotherapy drugs into their CSF to try to treat the spread of lymphoma to the spinal cord and brain. This is known as intrathecal chemotherapy.

If lymphoma spreads to the thin membranes that line the inside of the chest and abdomen, it can cause fluid to build up. Pleural fluid (inside the chest) or peritoneal fluid (inside the belly) can be removed by putting a hollow needle through the skin into the chest or abdomen.

• When this procedure is used to remove fluid from the chest, it’s called a thoracentesis.
• When it is used to collect fluid from inside the belly, it’s known as a paracentesis.

Before the procedure, the doctor uses a local anesthetic to numb the skin. They may give your child medicine to make them drowsy or put them to sleep during the procedure. The fluid is then removed and checked for lymphoma cells.

All biopsy samples and fluids are looked at by a pathologist, a doctor specially trained to identify cancer cells using lab tests.

The doctor uses a microscope to look at the size and shape of the cells and how they are arranged. This can show if a child has lymphoma, and sometimes what type of lymphoma it is. But usually, other types of lab tests are also needed.

These tests can help determine if a lymph node is swollen because of lymphoma, some other cancer, or a non-cancerous disease. They also help doctors figure out which type of lymphoma a child has, based on what proteins they find in or on the cancer cells.  

Different types of lymphocytes (the cells from which lymphomas start) have different proteins on their surface. The proteins are like markers that help doctors classify the type of lymphocyte and how mature it is.

This process is known as immunophenotyping. It can be done using either flow cytometry or immunohistochemistry. For both tests, samples of cells are treated with antibodies, which are proteins that stick only to certain other proteins on cells.

• Immunohistochemistry: The cells are looked at with a microscope to see if the antibodies stick to them, meaning they have these proteins.
• Flow cytometry: A special machine is used to look for these proteins.

These tests evaluate the chromosomes (long strands of DNA) in the lymphoma cells. Normal human cells have 23 pairs of chromosomes, each of which is a certain size and looks a certain way under the microscope.

In some types of lymphoma, the cells have chromosome changes.

For example, sometimes two chromosomes swap some of their DNA so that part of one chromosome becomes attached to part of a different chromosome. This structural change is called a translocation. It can usually be seen under a microscope.

Other types of chromosome changes are also possible. Recognizing these changes can help doctors identify the exact type of lymphoma, determine the right treatment, and understand the prognosis (outlook).

Cytogenetics

For this test, lymphoma cells are grown in a lab dish and the chromosomes are looked at under a microscope. Doctors look at the number and structure of the chromosomes to find any changes. Cytogenetic testing usually takes a few weeks because the lymphoma cells need time to grow before the chromosomes are ready to be looked at.

Not all chromosome changes can be seen under a microscope. Other lab tests, such as FISH and PCR, can often help detect these changes.

Fluorescent in situ hybridization (FISH)

This is another way to look at chromosomes and genes, using special dyes that only attach to specific parts of certain chromosomes.

FISH can find most chromosome changes, such as translocations, that are visible under a microscope in standard cytogenetic tests. It can also find some changes too small to be seen with routine cytogenetic testing. It is very accurate and usually provides results within a couple of days.

Polymerase chain reaction (PCR)

This is a very sensitive test that can also find chromosome and gene changes too small to be seen under a microscope, even if there are very few lymphoma cells in a sample.

This test measures the levels of red blood cells, white blood cells, and platelets in the blood.

In children already known to have lymphoma, low blood cell counts might mean the lymphoma is growing in the bone marrow and damaging new blood cell production. If a child is getting chemotherapy, this test might be used to see if treatment is affecting their bone marrow.

Doctors might check the levels of lactate dehydrogenase (LDH) in your child’s blood. They might also check the levels of erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP), which are markers of inflammation.

These tests may be high in people with lymphoma.

Blood chemistry tests can help detect liver or kidney problems caused by the spread of lymphoma cells or by certain chemotherapy drugs. These tests can also help determine if your child needs treatment to correct low or high blood levels of certain minerals.

Coagulation tests might be done to make sure your child’s blood is clotting properly.

For some types of lymphoma, other blood tests might be done to see if your child has been infected with certain viruses, such as the Epstein-Barr virus (EBV), hepatitis B or C virus (HBV, HCV), or human immunodeficiency virus (HIV).

Infections with some of these viruses can affect the way your child is treated.

Your child might need a chest x-ray to look for an enlarged thymus or lymph nodes inside their chest. If the test result is abnormal, they might need a computed tomography scan (CT scan) of their chest for a more detailed view.

Chest x-rays can also be used to look for pneumonia or fluid on the lungs if your child has symptoms of a lung infection or fluid buildup like a cough, shortness of breath, or low oxygen levels.

Ultrasound uses sound waves and their echoes to create pictures of internal organs or masses.

Doctors might use it to look at lymph nodes near the surface of your child’s body. It might also be used to look inside their abdomen (belly) or chest for fluid, enlarged lymph nodes, or enlarged organs like the liver, spleen, or heart.

Ultrasound-guided needle biopsy: Sometimes, ultrasound is also used to help guide a biopsy needle into an enlarged lymph node.

A CT scan combines many x-rays to make detailed, cross-sectional images of the inside of the body. Doctors often use it to look for enlarged lymph nodes or other tumors in the neck, chest, abdomen, and pelvis. A contrast material may be injected into your child’s vein or given by mouth before the scan to help see details better.

During the test, your child will need to lie still on a table that slides in and out of a ring-shaped scanner. If they are young, they might get medicine to keep them calm or asleep during the test so the pictures come out clearly.

In some cases, radiation is part of treatment for lymphoma. CT scans might be used for radiation planning.

CT-guided needle biopsy

A CT scan can also be used to guide a biopsy needle into a suspected tumor or enlarged lymph node. For this procedure, the child is asleep on the CT scanning table while the doctor uses a biopsy needle to collect part of an abnormal area or mass seen on the CT scan. The scans are repeated until the needle is in the right place. The biopsy sample is then removed and looked at in the lab.

PET/CT scan

Some machines combine the CT scan with a positron emission tomography (PET) scan. This can provide more information about any abnormal areas that appear on the CT scan. For more on this, see PET scan (below).

For a PET scan, a radioactive substance is injected into your child’s blood. This substance is usually a type of sugar, known as FDG. Because cancer cells grow quickly, they will absorb large amounts of the sugar. A special camera can then create a picture of any areas of radioactivity in the body.

Being still during this test is important. Younger children may get medicine to help them stay calm or even sleep during the test.

When is PET scan used for a child with lymphoma?

The picture created with a PET scan isn’t as detailed as a CT or MRI scan, but it provides helpful information about the whole body.

If your child has lymphoma, their cancer care team might use a PET scan to help them:

• Find out if a suspicious area seen on a bone scan, CT scan, or other imaging test is a tumor
• See if an enlarged lymph node contains lymphoma
• Spot small areas that might be lymphoma, even if those areas look normal on a CT scan
• Find out if the lymphoma is responding to treatment

They can also be used after treatment to help decide if an enlarged lymph node still contains lymphoma or is just scar tissue.

PET/CT scan

Some machines can do a PET and CT scan at the same time. This lets the doctor compare areas of higher radioactivity on the PET scan with the more detailed image of that area on the CT scan.

Like a CT scan, an MRI scan shows detailed images of soft tissues in the body. MRI uses radio waves and strong magnets to make pictures, instead of x-rays.

This test is not used as often as CT scans for lymphoma, but it is very useful for looking at the brain and spinal cord if a child has symptoms that might be caused by problems in their nervous system.

MRIs take longer than CT scans, often up to an hour. Your child might have to lie inside a narrow tube, which can be distressing. They might need medicine to help them stay calm or fall asleep. Newer, more open MRI machines may be another option, although your child will still have to lie still.

A bone scan isn’t usually needed unless a child has bone pain or lab test results that suggest the lymphoma might have reached their bones.

For this test, a small amount of low-level radioactive material called technetium-99 is injected into your child’s blood and travels to their bones. The amount of radioactivity is very low and will pass out of their body within a day or so.

A special camera can detect this material, and it creates a picture of the skeleton. Areas of active bone changes attract the radioactivity and show up as “hot spots” on the scan. These areas may suggest cancer, but other bone diseases can also cause the same pattern, so your child might need other tests like plain x-rays, MRI scans, or biopsy.

Being still during this test is important. If your child is young, they might get medicine to keep them calm or asleep during the test.