How is non-Hodgkin lymphoma diagnosed?

If your healthcare provider thinks you may have non-Hodgkin lymphoma, you'll need certain exams and tests to be sure. The process starts with your healthcare provider asking you questions. You'll be asked about your health history, your symptoms, risk factors, and family history of disease. You will also have a physical exam. It will include looking for swollen lymph nodes and signs of infection.

Based on the findings, your healthcare provider may decide you need a biopsy to check for cancer.

What is a biopsy?

A biopsy is done by taking out a tiny piece of tissue (called a sample) so it can be tested for cancer cells. A biopsy is the only sure way to know if you have non-Hodgkin lymphoma.

For a biopsy, the healthcare provider removes a tissue sample from the swollen lymph nodes. The sample is sent to a lab. There, a healthcare provider called a pathologist tests it for cancer cells. There are a few ways a biopsy can be done to look for non-Hodgkin lymphoma.

Types of biopsies

The different types of biopsies include:

• Excisional or incisional biopsy. This type is the most common biopsy used to diagnose non-Hodgkin lymphoma. For an excisional biopsy, a whole lymph node is taken out through a small cut made in your skin. If only part of the lymph node is removed, it's called an incisional biopsy.

  If the lymph node is right under your skin, medicine might be used to numb the area first. To remove deeper nodes, you might be given medicines that make you sleep and not feel pain during the procedure.

  This kind of biopsy almost always gives the pathologist enough tissue to make a diagnosis.

• Fine needle aspiration (FNA) or core needle biopsy. For this type of biopsy, a thin, hollow needle is put through your skin and into the swollen lymph node. Then a syringe is used to pull some tissue into the needle. For FNA, the healthcare provider uses a very thin needle. A wider needle is used for a core needle biopsy. This can take out more tissue.

  If the tumor is deep inside your body, the surgeon may use an ultrasound or CT scan to see inside your body and guide the needle to the right place.

  Needle biopsies mean no surgery. But they don’t always remove enough tissue for a definite diagnosis. Because of this, they aren't often used to diagnose non-Hodgkin lymphoma. Still, they can help to check for other problems, such as infection in the lymph nodes.

How biopsy samples are tested

A pathologist can often see if a person has non-Hodgkin lymphoma by using a microscope to look at the cells in the biopsy sample. But in many cases, other types of lab tests may be needed. The tests help to:

• Make sure the diagnosis is correct

• Find out the exact type of lymphoma

This information helps the healthcare provider decide on the best treatment plan for you. It also helps give a sense of your likely outcomes (prognosis).

Some of the lab tests done on biopsy samples include:

Immunohistochemistry. This test can help show different types of non-Hodgkin lymphoma. To do it, part of the biopsy sample is treated with special antibodies that attach to certain proteins on the lymphoma cells. This causes color changes that can be seen under a microscope.

Flow cytometry.  This test can also help tell the type of non-Hodgkin lymphoma. It looks at more cells than immunohistochemistry. It uses a special machine to see the types of proteins on the outside of the cancer cells. This helps classify the type of lymphoma.

Cytogenetic analysis. Cells in the sample are grown in a lab. After about 2 to 3 weeks, a pathologist looks at chromosomes (pieces of DNA) in the cells using a microscope. Some lymphomas have certain chromosome changes that help classify them.

Molecular genetic tests. These tests may also be used to look for chromosome changes at a more detailed genetic or molecular level. They often take less time than cytogenetic tests, so many healthcare providers prefer to use them. These tests include:

• FISH (fluorescent in situ hybridization). This test uses special fluorescent dyes that attach to only certain parts of chromosomes. FISH can find most chromosome changes that can be found with cytogenetic tests. But it can also find some changes too small to be seen with cytogenetic testing. It's very accurate and only takes a few days. 

• PCR (polymerase chain reaction). This is a very sensitive DNA test. It can also find some chromosome changes too small to be seen under a microscope. It can do this even if there are very few lymphoma cells in a sample.

Getting your test results

It often takes several days for the results of your biopsy to come back. When your healthcare provider has the results of your biopsy, they will contact you. Ask how you can expect to find out your biopsy results. Will it be a phone call, or do you need to make an appointment?

Your provider will also talk with you about other tests that may be needed if non-Hodgkin lymphoma is found. Make sure you understand the results and what your next steps should be.