used for a core needle biopsy. ■ Because of the small needle size, the sample only contains scattered cells, without preserving how the cells are arranged in the lymph node. Therefore, this test cannot provide enough information for a definitive initial diagnosis of HL in the vast majority of cases. ■ An FNA biopsy may be used if a core needle biopsy is not possible. It can also be used to check for relapse (return of the disease) after treatment. 27 Understanding Hodgkin Lymphoma What Are a Bone Marrow Biopsy and a Bone Marrow Aspiration? Bone marrow is the spongy, fatty material inside large flat bones (such as the pelvis, vertebrae, and sternum) where blood cells are generated. A bone marrow biopsy involves removing a small amount of bone marrow and examining it for the presence of lymphoma cells. A bone marrow aspiration is similar to a bone marrow biopsy, except it involves removing only the liquid portion of the marrow using a fine needle. A bone marrow biopsy or aspiration is not typically used for initial diagnosis, but it is occasionally used at a later stage to determine whether the HL has spread to the bone marrow. What Happens During a Bone Marrow Aspiration and Biopsy? ■ Patients lie on the examination table either on their side or on their stomach. ■ Patients may be given a general anesthetic to put them to sleep, or the doctor may inject a local anesthetic to numb the skin over the hip where the needle will be inserted. ■ In bone marrow aspiration, the doctor inserts a thin, hollow needle through the skin into the hip bone. ■ The doctor then uses a syringe to remove a small amount of liquid from the bone marrow. Even with the numbing local anesthetic, withdrawal of the marrow can briefly cause pain. ■ In a bone marrow biopsy, which is often performed immediately after the aspiration, the doctor inserts a slightly larger needle to remove a small piece of bone and marrow. This procedure can also briefly cause pain. ■ A pathologist examines the samples under a microscope to look for Reed-Sternberg (RS) cells and other findings that may indicate HL. Learning the Basics 28 Part 1 What Is a Complete Blood Count (CBC) With Differential Test? In a CBC with differential test, samples of blood are examined to measure the levels of each different type and subtype of blood cells, including: ■ The number of red blood cells ■ The amount of hemoglobin (the oxygen-carrying protein) inside the red blood cells ■ The number of total white blood cells, as well as the numbers of each subtype of white blood cells (neutrophils, eosinophils, basophils, lymphocytes, and monocytes) ■ The number of platelets The results of the CBC with differential test assist in the diagnosis of HL by ruling out other types of blood cancer. The test is often repeated during the course of treatment to help determine how much the therapy has affected the different blood counts and, in some cases, to help gauge how well the treatment is working against the lymphoma. What Is Erythrocyte Sedimentation Rate (ESR)? The ESR is the rate at which erythrocytes (red blood cells) settle to the bottom of a tube of blood. The ESR is an indicator of the amount of inflammatory cells in the blood. Patients with an elevated ESR tend to have a worse prognosis so they may be treated more aggressively. What Is Immunophenotyping? Immunophenotyping is a process that can be used to distinguish between different types of cells (for example, normal lymphocytes vs. HL cells) based on the presence of antigens (cell markers) on the cell surface. Antigens are specific to different cell types, just as landmarks are specific to different cities. These antigens are recognized by antibodies that have been chemically modified in the laboratory so that they show color or emit fluorescent light. 29 Understanding Hodgkin Lymphoma Two types of analyses, immunohistochemistry (IHC) and flow cytometry, may be performed with these antibodies for accurate immunophenotyping (see Table 3.2). Table 3.2. Immunohistochemistry and Flow Cytometry Tests Immunohistochemistry (IHC) ■ Thin slices of the biopsy sample (or thin layers of fluid) are treated with sets of antibodies that recognize markers found in different types of lymphoma cells and normal