Diagnosis

Doctors use many tests to diagnose cancer and determine if it has metastasized (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 cancer has metastasized. Your doctor may consider these factors when choosing a diagnostic test:

• Age and medical condition
  
  
• The 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 analyzed 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. The doctor may perform a fine-needle aspiration biopsy, in which a thin needle attached to a syringe is used to remove some fluid and tissue from a tumor.

Bone marrow aspiration. To determine whether the cancer has spread, the doctor may do a bone marrow aspiration. In this test, a small amount of bone marrow is removed and examined under a microscope. The child’s skin is numbed with a local anesthetic.

Lumbar puncture (spinal tap). A lumbar puncture is a procedure in which a doctor takes 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. To determine the subtype of non-Hodgkin lymphoma, the doctor may do two tests: flow cytometry and immunocytochemistry. A flow cytometry involves cells of interest being 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.

Imaging tests

To determine where the cancer is and if it has spread, the doctor may use the following imaging tests:

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 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 brain and spinal column. 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.

X-ray. An x-ray is a picture of the inside of the body. For instance, a chest x-ray can help doctors determine if the cancer has spread to the lungs.

Bone scan. A bone scan can detect injuries to the bones, which could be caused by cancer. It 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 organs or tissues being studied. This substance gives off energy that is detected by a scanner, which produces the images. PET scans are often used to complement information gathered from CT scan, MRI, and physical examination. It can show the difference between benign (noncancerous) shadows 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 lymphoma-containing masses often show up on PET scans. In the future, a PET scan may help monitor aggressive types of lymphoma and their response to treatment.

Learn more about what to expect when having common tests, procedures, and scans.

Find out more about common terms used during a diagnosis of cancer.