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Doctors use many tests to diagnose cancer and find out if it has metastasized (spread). Some tests may also determine which treatments may be the most effective. A biopsy is the only way to make a definitive diagnosis of lymphoma. Imaging tests may be used to find out whether the cancer has metastasized. Your child’s doctor may consider these factors when choosing a diagnostic test:
- Age and medical condition
- Type of cancer suspected
- Severity of symptoms
- Previous test results
The doctor will first perform a physical examination and take a complete medical history to help determine if a child has non-Hodgkin lymphoma. In addition, the following tests may be used to diagnose non-Hodgkin lymphoma:
Biopsy. A biopsy is the removal of a small amount of tissue for examination under a microscope. Other tests can suggest that cancer is present, but only a biopsy can make a definite diagnosis. The sample removed from the biopsy is studied by a pathologist (a doctor who specializes in interpreting laboratory tests and evaluating cells, tissues, and organs to diagnose disease). If the tumor is near the surface, the child will be given a local anesthetic to numb the area. If it is deeper inside the body, the doctor will use a general anesthetic to block the awareness of pain.
Bone marrow aspiration. Bone marrow has both a solid and a liquid part. An aspiration removes a sample of fluid with a needle. The sample is then analyzed by a pathologist. A common site for a bone marrow aspiration is the pelvic bone, which is located in the lower back by the hip. The skin in that area is usually numbed with medication beforehand, and other types of anesthesia (medication to block the awareness of pain) may be used.
Lumbar puncture (spinal tap). A lumbar puncture is a procedure in which a doctor uses a needle to take a sample of cerebral spinal fluid (CSF) to look for cancer cells, blood, or tumor markers (substances found in higher than normal amounts in the blood, urine, or body tissues of people with certain types of cancer). CSF is the fluid that flows around the brain and the spinal cord. Doctors generally give an anesthetic to numb the lower back before the procedure.
Cytogenetic analysis. A pathologist may examine the pairs of chromosomes (strings of DNA that contain genes) from the biopsy under the microscope to check for chromosomal abnormalities. This helps the doctor identify the subtype of lymphoma and plan treatment.
Flow cytometry and immunocytochemistry. These tests help the doctor determine the subtype of non-Hodgkin lymphoma. In a flow cytometry test, cells from the lymph nodes, bone marrow, or blood are removed and treated with a fluorescent, dye-equipped antibody that attaches to DNA. The cells are then passed in front of a laser beam, which allows a special computer to measure their DNA level. Higher amounts of DNA than normal may indicate cancer. During an immunocytochemistry test, fluorescent antibodies or immunoperoxidase staining may be used to determine the subtype of non-Hodgkin lymphoma.
To determine where the cancer is and whether it has spread, the doctor may use the following imaging tests:
X-ray. An x-ray is a way to create a picture of the tissues and organs inside of the body using a small amount of radiation. A chest x-ray is the most common type of x-ray taken for diagnosing NHL.
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 taken by mouth or injected into a vein to provide better detail. CT scans of the chest and abdomen can help find cancer that has spread to the lungs, lymph nodes, and liver.
Magnetic resonance imaging (MRI). 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. MRIs may create more detailed pictures than CT scans.
Bone scan. A bone scan can detect injuries to the bones, which could be caused by lymphoma. It uses a radioactive tracer to look at the inside of the bones. The tracer is injected into a patient’s vein. The tracer 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 uses a small amount of a radioactive tracer to create pictures of organs and tissues inside the body. The radioactive tracer is injected into a patient’s vein and collects mainly in organs and tissues that use the most energy. Because cancer tends to use energy actively, it absorbs more of the radioactive substance. A scanner then detects this substance to produce images of the inside of the body.
The information from PET scans is often used with the information from a CT scan, MRI, and physical examination to decide if cancer is present in tissues. It can help show the difference between benign (noncancerous) findings from a CT scan or MRI and malignant (cancerous) tumors that may not be clear on a CT scan or MRI. The exact accuracy and role of PET scanning in NHL is not yet clear, although tumors that contain lymphoma cells often show up on a PET scan. In the future, a PET scan may help monitor aggressive types of lymphoma and the disease’s response to treatment.
Learn more about what to expect when having common tests, procedures, and scans.
After these diagnostic tests are done, your child’s doctor will review all of the results with you. If the diagnosis is cancer, these results also help the doctor describe the cancer; this is called staging. Learn more about the first steps to take after a diagnosis of cancer.