Diagnosis

Doctors use many tests to diagnose cancer and determine if it has spread. Some tests may also determine which treatments may be the most effective. For most types of cancer, a biopsy is the only way to make a definitive diagnosis of cancer. If a biopsy is not possible, the doctor may suggest other tests that will help make a diagnosis. Imaging tests may be used to find out whether the lymphoma has spread. Your doctor may consider these factors when choosing a diagnostic test:

• Age and medical condition
• The type of lymphoma suspected
• Severity of symptoms
• Previous test results

To determine if a person has NHL, the doctor will first take a complete medical history and do a physical examination, paying special attention to the lymph nodes, liver, and spleen. The doctor will also look for signs of infection that may cause the lymph nodes to swell and may prescribe an antibiotic. If the swelling in the lymph nodes still does not go down after antibiotic treatment, the swelling may be caused by something other than an infection. If the doctor suspects lymphoma, he or she may order a biopsy, as well as laboratory and imaging tests.

In addition to a physical examination, the following tests may be used to diagnose NHL:

Biopsy. A biopsy is the removal of a small amount of tissue for examination under a microscope. To diagnose lymphoma, the most common type is a biopsy from lymph nodes in the neck, under the arms, or in the groin. A biopsy may also be taken from the chest or abdomen during a computed tomography (CT) scan, or from the stomach or intestine during an endoscopy (a diagnostic examination that allows a doctor to examine the inside of the body). A biopsy is the only way to make a definite diagnosis of lymphoma and to determine the subtype. The tissue sample should be analyzed by a pathologist experienced in the diagnosis of lymphoma; second opinions may also be helpful.

Since many subtypes of lymphoma are identified by specific genetic changes or molecular activity, cytogenetics (the study of genetic changes in cells) and molecular studies may be performed on the biopsy sample. For example, the tumor cells in the NHL subtype of mantle cell lymphoma contain a translocation of chromosomes 11 and 14, which means that parts of these two chromosomes have traded places. Other types of lymphoma are identified by abnormal amounts of certain proteins.

Bone marrow aspiration and biopsy. Lymphoma often spreads to the bone marrow, the spongy material in the center of bones where blood cells are produced. Looking at a sample of the bone marrow can be important for doctors to diagnose lymphoma and to determine if it has spread.

The most common site to biopsy the bone marrow is the back of the pelvic (hip) bone. The skin is numbed, and a needle is inserted into a bone in the hip until it reaches the marrow. A small amount of bone marrow is removed and examined under a microscope.

Computed tomography (CT or CAT) scan. A CT scan creates a three-dimensional picture of the inside of the body with an x-ray machine. A computer then combines these images into a detailed, cross-sectional view that shows any abnormalities or tumors. Sometimes, a contrast medium (a special dye) is injected into a patient’s vein to provide better detail and locate the exact position of a tumor. CT scans of the chest, abdomen, and pelvis can help find cancer that has spread to the lungs, lymph nodes, and liver.

Magnetic resonance imaging (MRI) scan. An MRI uses magnetic fields, not x-rays, to produce detailed images of the body. A contrast medium may be injected into a patient’s vein to create a clearer picture.

Bone scan. A bone scan uses a radioactive tracer to look at the inside of the bones. The tracer is injected into a patient’s vein. It collects in areas of the bone and is detected by a special camera. Healthy bone appears gray to the camera, and areas of injury, such as those caused by cancer, appear dark.

Positron emission tomography (PET) scan. A PET scan is a way to create pictures of organs and tissues inside the body. A small amount of a radioactive substance is injected into a patient’s body and absorbed by the organs or tissues being studied. This substance gives off energy that is detected by a scanner, which produces the images. The exact accuracy and role of PET scanning in NHL is not yet clear, although aggressive lymphomas often show up on PET scans. Many oncologists will obtain a PET scan as part of the initial evaluation, especially for the aggressive lymphomas. In the future, a PET scan may help monitor the disease’s response to treatment. There is also some evidence that using a PET scan after one or two cycles of treatment may be a useful way of predicting whether that treatment is likely to completely eliminate the lymphoma. This is not yet proven, but it is being evaluated in many studies around the world.

To learn more about what to expect during common diagnostic tests, read Cancer.Net: Tests and Procedures.

To learn about the terms used in this section, read the Cancer.Net Feature: Cancer Terms to Know: Newly Diagnosed.