How is non-Hodgkin lymphoma diagnosed?

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

What is a biopsy?

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

For a biopsy, the doctor removes a tissue sample from the swollen lymph nodes. The sample is sent to a lab. There, a doctor called a pathologist tests it for cancer cells. Several types of biopsies can be done to look for non-Hodgkin lymphoma.

Types of biopsies

The different types of biopsies include:

• Excisional or incisional biopsy. This is the most common type of biopsy used to diagnose non-Hodgkin lymphoma. For an excisional biopsy, a surgeon cuts through your skin to take out a whole lymph node. For an incisional biopsy, the surgeon also cuts your skin, but takes out only part of the lymph node or tumor. If the lymph node is right under your skin, you may be given medicine to numb the area first. To remove deeper nodes, medicines may be used to make you sleep through 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 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 doctor uses a very thin needle. For core needle, the doctor uses a wider needle. 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. But hey can help to check for other problems, such as an 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 taken with the biopsy. But in many cases, other types of lab tests may be needed. The tests help to:

• Make sure the diagnosis is correct

• Show the type of lymphoma

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

Biopsy samples may be tested with:

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

Flow cytometry.  This is another test that can 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.  The removed cells are grown in a lab. After about 2 to 3 weeks, a pathologist looks at a cell’s chromosomes (pieces of DNA) under 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 doctors prefer to use them. These tests include:

• FISH (fluorescent in situ hybridization). This test uses special fluorescent dyes that only link to certain parts of chromosomes. FISH can find most chromosome changes that can be seen with standard 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

Talk with your healthcare provider about how and when you will get your test results. 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 happens next.