Staging

Introduction Tissue analysis of tumor samples is required to establish a lymphoma diagnosis. Once a diagnosis is established, imaging studies should be performed to assess the extent of disease (tumor stage). Depending on the choice of therapy, additional tests will be needed to ensure the safety of the selected therapy. Biopsy Ideally, an excisional biopsy should be obtained to ensure adequate tissue for morphologic and molecular analysis. More recently, a less invasive, core needle biopsy is increasingly being used with success. Initially, a morphologic examination of tissue sections is performed by an expert hematopathologist. This initial examination provides important information on the growth pattern and lymph node architecture. For example, lymphoma cells may grow in a nodular (or follicular) pattern, or a diffuse pattern. Additional biomarker and genetic tests are typically used to further classify the type of lymphoma, establish clonality, identify therapeutic targets, and assess prognosis. Immunohistochemistry A panel of immunostains is typically used to determine the tumor lineage (B, T, or natural killer cell of origin). To do so, the expression pattern of several lineage-specific proteins is examined using a battery of monoclonal antibodies. Table 4.1 lists the most frequently protein biomarkers. In addition to establishing lineage, additional immunostains are used to sub-classify different types of lymphomas. Frequently, the expression pattern of several proteins can be associated with specific lymphoma subtypes, as shown in Table 4.2. Finally, immunohistochemistry (IHC) studies are also used to asses prognosis, identify therapeutic targets, and to select patients for specific clinical trials (Table 4.3). Table 4.1 Common lineage-specific proteins that are included in diagnostic immunohistochemistry diagnostic panels. × Table 4.2 Correlation between protein expression and non-Hodgkin lymphoma subtypes. × Table 4.3 Correlation between protein expression status and prognosis in different subtypes of non-Hodgkin lymphoma. × Flow cytometry Multi-parameter flow cytometry (FC) analysis of tumor cells can provide valuable information to assist in establishing the diagnosis, sub-classify the lymphoma type, and assess prognosis. This diagnostic tool is particularly helpful for examining circulating lymphoma cells in peripheral blood and in bone marrow. FC analysis is also used to analyze cells obtained by a fine needle aspiration from diseased sites. Most antibodies that are used for IHC on paraffin-embedded tissues can also be used for FC analysis. However, the advantage of FC is the ability to evaluate the expression of several proteins in the same cell. FC is also used to assess the presence of lymphoma cells in the cerebral spinal fluid. Molecular diagnostics In lymphoid malignancies, clonality is typically established by the presence of a dominant clone with identical gene rearrangement involving the immunoglobin heavy (IgH) chain in B-cell lymphomas, or T-cell receptors in T-cell lymphoma. This test can be performed using polymerase chain reaction (PCR) assay, and most recently by DNA-sequencing methods. Characteristic chromosomal translocations can be detected by fluorescent in situ hybridization (FISH). For example, chromosomal rearrangement involving the Bcl2 gene is frequently observed in follicular lymphoma and diffuse large B cell lymphoma (DLCLC), whereas those involving the Bcl1 gene are observed in mantle cell lymphoma. Myc rearrangement is characteristic of Burkitt lymphoma, but can also be seen in rare cases of DLBCL. Finally, gene rearrangement involving ALK, is typically observed in ALK+ anaplastic large cell lymphoma (Table 4.4). As DNA and RNA sequencing assays are increasingly utilized in the clinical settings, these assays can also detect clonal genetic alterations, including mutations, and copy number changes. Table 4.4 Common chromosomal translocations observed in non-Hodgkin lymphoma subtypes. × Assessment of disease stage Once a lymphoma diagnosis is established, the next step is to determine the extent of disease and assigning a disease stage [1]. There are four lymphoma stages, with stage I being the least advanced (early stage) and stage IV being the most advanced stage. Staging is determined by imaging studies that may involve computed tomography (CT) or magnetic resonance imaging (MRI) scans, a positron emission tomography (PET) scan, and frequently requires a bone marrow biopsy. In general, involve ment of one lymph node region or one extra nodal site is defined as stage I and IE, respectively. Stage II is established when more than one nodal involvement as long as they are on one side of the diaphragm. Stage III, lymph node involvement (regardless of the number or size) on both sides of the diaphragm. Stage IV, when both nodal and extra nodal sites (such as liver, bone, bone marrow, lungs) are involved. A bone marrow biopsy is frequently needed to complete the staging work up, and to determine disease response at the end of therapy. A bone marrow biopsy is not required in patients with early stage classical Hodgkin lymphoma who are adequately staged with imaging studies, including PET scan, as the bone marrow is rarely involved in these situations. Lumbar puncture In special cases of non-Hodgkin lymphoma, lumbar puncture is indicated to determine whether the lymphoma is spread to the spinal canal. This is particularly important for patients with Burkitt’s lymphoma, testicular lymphoma, and aggressive B-cell lymphoma involving the para nasal sinuses. Additionally, patients with advanced stage diffuse large B-cell lymphoma, with multiple extranodal involvement, high lactate dehydrogenase (LDH), and poor performance status, are also at a higher risk for central nervous system involvement, and should be considered for a diagnostic lumbar puncture before initiating therapy. Patients with the above mentioned risk groups are candidates for prophylactic intrathecal chemotherapy. Additional tests After establishing the diagnosis and assigning a disease stage, a management plan is formulated. In many cases, the treatment involves chemotherapy, or a combination of chemotherapy and radiation therapy. Depending on the treatment recommendation, additional diagnostic tests are performed to determine the patient’s ability to tolerate treatment, and to monitor for unexpected toxicity. For example, before initiating an anthracyclin-based regimen, the patient’s cardiac function, including the left ventricular ejection fraction, should be determined. Patients with evidence of hepatitis B or C infection should be adequately treated with anti-viral therapy, and monitored for liver toxicity. Similarly, patients with human immunodeficiencey virus (HIV) infection should be treated to decrease their viral load and to restore CD4 T cell counts before initiating therapy. Finally, women of childbearing age should be evaluated for possible pregnancy before initiating therapy, and should practice adequate birth control during therapy. Copyright © Springer International Publishing Switzerland 2016

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