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.
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:
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.