Similar tests are used for diagnosing both Hodgkin and non-Hodgkin lymphoma. If your doctor suspects that you might have lymphoma, these tests can help to determine whether you have the disease and which type of lymphoma you have. Getting the correct diagnosis is a critical first step in developing the most effective treatment plan.
Physicians use a classification system for lymphoma that has evolved as understanding of the disease has progressed. The current system, called the WHO/REAL system (for World Health Organization/Revised European American Lymphoma classification), allows physicians to distinguish lymphomas based on a number of characteristics: the appearance of the cells, their genetic features, their chemistry, and their clinical behavior.
Memorial Sloan-Kettering has expertise in the following techniques for diagnosing lymphoma.
During a biopsy, a small amount of tissue is removed and then analyzed under a microscope by a pathologist. Several types of biopsies are used routinely in the diagnosis of lymphoma.
Excisional or Incisional Biopsy
A surgeon removes an entire lymph node (excisional) or a small amount of tumor tissue (incisional). A biopsy is considered the gold standard for the diagnosis of lymphoma.
Fine-Needle Aspiration Biopsy
In some cases it may be possible to use a very thin needle and syringe to draw tissue from a tumor.
Bone Marrow Biopsy and Aspiration
After the patient receives anesthesia, a physician withdraws a small sample of bone marrow through a needle, usually from a bone in the back of the pelvis. Sometimes this sample is enough to diagnose lymphoma. This test also helps to determine the extent of lymphoma, including whether it has spread to the bone marrow.
Cerebrospinal fluid, the fluid that circulates around the brain and spinal cord, is removed from the spinal cavity in the lower back. This test is generally used to determine the extent of disease in patients who have a high risk of developing lymphoma in their central nervous system.
Other tests may include blood counts, erythrocyte sedimentation tests (tests that measure the distance red blood cells travel as they settle to the bottom of a test tube), and studies of liver and kidney function.
Imaging tests are used to determine the location of tumors in the body.
- Chest x-rays can detect tumors in the chest and lungs.
- CT scans take x-rays of the body from a number of angles. These pictures are then combined to produce detailed images of the inside of the body.
- PET scans detect small amounts of radioactive sugar as it is taken up by active cancer cells. This test lights up areas of infection and inflammation in addition to cancer.
- MRI scans use magnets and radio waves to produce detailed pictures of soft tissues and organs. MRI is used in diagnosing some cases of lymphoma, but is not used often.
A number of tests can also help determine specific features of the cells in tissue obtained from a biopsy. Pathologists look for genetic abnormalities such as rearrangements in the chromosomes — which are common in lymphomas — and whether the cells have receptors for specific proteins. These factors help to identify the cells' origins and to determine your prognosis. These tests include:
- Cytogenetic studies to identify chromosomal changes in cells
- Immunohistochemistry studies, in which antibodies are used to distinguish between types of cancer cells
- Flow cytometry, in which prepared cells are passed through a laser beam for analysis
- Molecular genetic studies (highly sensitive DNA and RNA tests) to determine specific genetic traits of cancer cells
New diagnostic tests and procedures are emerging from work on the human genome and gene-expression analysis. These are likely to be important in the future but are currently experimental.