Doctors use many tests to diagnose cancer and find out the extent of the disease. 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. 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 spread. Your 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 following tests may be used to help diagnose Hodgkin lymphoma:

Medical history and physical examination. A thorough medical history and physical examination can show evidence of typical symptoms, such as night sweats, fevers, and enlarged lymph nodes or spleen.

Biopsy [2]. 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 Hodgkin lymphoma can only be diagnosed after a biopsy of an affected piece of tissue. Most commonly, this will be a lymph node in the neck, under the arm, or in the groin. If there are no lymph nodes in these areas, a biopsy of other lymph nodes, such as those in the center of the chest, may be necessary. This type of biopsy usually requires minor surgery, although occasionally it is possible to do a biopsy using a needle and local anesthesia (medication to block the awareness of pain) during a scan, most commonly a computed tomography (CT or CAT) scan (see below). The CT scan is used to help the doctor guide the needle to the correct place.

The sample removed during the biopsy is analyzed by a pathologist (a doctor who specializes in interpreting laboratory tests and evaluating cells, tissues, and organs to diagnose disease). As described in the Overview [3], a biopsy of CHL usually has Reed-Sternberg cells. Reed Sternberg cells are often not found in the nodular lymphocyte-predominant Hodgkin lymphoma, which usually has a different type of cancerous cell, called the LP cell.

Once Hodgkin lymphoma is diagnosed, other tests can help find out the extent of the disease or stage and other information to help doctors plan treatment. These tests include the following:

Laboratory tests [4]. Blood tests may include a complete blood count (CBC) and analysis of the different types of white blood cells, in addition to liver function tests. The doctor may also test for the erythrocyte sedimentation rate (ESR), also called the "sed rate."

Computed tomography (CT or CAT) scan [5]. 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. A CT scan can also be used to measure the size of a tumor. Sometimes, a contrast medium (special dye) is injected into a patient’s vein or given orally (by mouth) to provide better detail. A CT scan of the chest, abdomen, and pelvis can help find cancer that has spread to the lungs, lymph nodes, or liver.

Positron emission tomography (PET) scan [6]. A PET scan is another imaging test that can help find cancer in the body. A small amount of a radioactive substance (called radioactive glucose) is injected into a patient’s body. This substance is absorbed mainly by organs and tissues that produce the most energy. Because cancer tends to use energy actively, it absorbs more of the substance. A scanner then detects this substance to produce images of the inside of the body. PET scans may be used to determine the stage of Hodgkin lymphoma, although they are usually done with a CT scan. PET scans may also be used to see how well the lymphoma is responding to treatment.

Magnetic resonance imaging (MRI) [7]. 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. This is sometimes used for Hodgkin lymphoma.

Bone marrow biopsy and aspiration [8]. These two procedures are similar and often done at the same time. Bone marrow (the soft, spongy tissue that is found inside the center of bones) has both a solid and a liquid part. A bone marrow biopsy is the removal of a small amount of solid tissue using a needle. An aspiration removes a sample of fluid with a needle. The sample(s) are then analyzed by a pathologist.

Lymphoma often spreads to the bone marrow, so looking at a sample of the bone marrow can be important for doctors to diagnose lymphoma and determine the stage. The sample removed during the aspiration is also used to find any chromosome changes. Whether a bone marrow biopsy is needed depends on the extent of the disease and the results of laboratory tests (see above).

The most common site for a bone marrow biopsy and aspiration is the iliac crest of the pelvic bone, located in the lower back of the hip. This is generally a safe area of the body to perform the procedure because there are no veins or nerves in that area that could be damaged. The skin and bone in that area are numbed with medication beforehand, and other types of anesthesia may be used.

Learn more about what to expect when having common tests, procedures, and scans [9].

After these diagnostic tests are done, your 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 [10]. Learn more about the first steps to take after a diagnosis of cancer [11].