Pediatric Non-Hodgkin Lymphoma Workup

Updated: Feb 06, 2017
  • Author: J Martin Johnston, MD; Chief Editor: Max J Coppes, MD, PhD, MBA  more...
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Workup

Approach Considerations

A complete blood count (CBC) with differential and a platelet count in patients with non-Hodgkin lymphoma should be obtained to assess for possible involvement of the bone marrow and to determine the patient's transfusion requirements. Additional tests, listed in the next section, are run to assess the patient's renal and hepatic function and to monitor for possible tumor lysis syndrome.

Lumbar puncture

Lumbar puncture with determination of the cerebrospinal fluid (CSF) cell count and differential is performed to assess CNS involvement, the presence of which alters therapy.

Airway obstruction

Mediastinal or cervical lymphomas may cause airway compromise. The potential for respiratory arrest must be recognized, particularly if sedation or general anesthesia is administered for a diagnostic procedure.

Consider (1) administering local anesthesia alone for lymph node biopsy; (2) establishing a diagnosis with pleural fluid, peritoneal fluid, or bone marrow aspiration; and (3) performing local irradiation to stabilize the airway before obtaining a diagnostic specimen from a site outside the radiation field.

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Laboratory Studies

As previously mentioned, a CBC with differential and a platelet count should be obtained in patients with non-Hodgkin lymphoma to assess for possible involvement of the bone marrow and to determine the patient's transfusion requirements.

Measure the prothrombin time, the activated partial thromboplastin time, fibrinogen, and the D-dimer level if the patient is febrile or if he or she has evidence of sepsis. The purpose is to assess for possible disseminated intravascular coagulation, which may require specific therapy.

Obtain blood and urine cultures if the patient has a fever, especially if it is associated with neutropenia. If indicated, also obtain stool and throat cultures.

Analyze the following to assess the patient's renal and hepatic function and to monitor for possible tumor lysis syndrome:

  • Serum electrolytes
  • Blood urea nitrogen (BUN)
  • Creatinine
  • Uric acid
  • Lactate dehydrogenase – The level of lactate dehydrogenase at diagnosis has had prognostic significance in many analyses of treatment outcomes
  • Bilirubin
  • Albumin
  • Total protein
  • Aspartate aminotransferase
  • Alanine aminotransferase
  • Calcium
  • Magnesium
  • Phosphorus
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Imaging Studies

Chest radiography

Obtain posteroanterior and lateral views to assess for possible mediastinal masses, to evaluate the airway, and to exclude pulmonary parenchymal lesions and associated pneumonia.

Ultrasonography

Abdominal ultrasonography helps in assessing the size of the kidneys and the patency of the urinary tract. It is particularly useful before chemotherapy in anticipation of, for example, prolonged excretion and excess toxicity. When symptoms are present, testicular ultrasonography aids in identifying additional sites of disease.

Echocardiography

Perform echocardiography to obtain baseline findings before patients are given chemotherapy with anthracyclines, which can cause cardiomyopathy.

CT scanning

Computed tomography (CT) scans of the chest, abdomen, and pelvis can be used to stage lesions. If the patient is stable, chest CT scan is indicated to assess for the degree of tracheal compression. Head CT scans assist in excluding mass lesions and possible meningeal involvement in individuals with CNS disease.

PET/CT scanning

Positron emission tomography (PET)/CT scanning has largely supplanted gallium-67 (67 Ga) scanning and is highly recommended for patients with non-Hodgkin lymphoma. [47, 48, 49, 50, 51]

Many lymphomas are 2-[fluorine-18]fluoro-2-deoxy-d-glucose (FDG) avid; their response to treatment can be assessed by using this modality. Occult sites of disease may also be identified on PET/CT scans. Many newer "response-based" chemotherapy protocols use PET scanning to assess response and guide subsequent treatments.

Bone scanning and skeletal surveys

When additional symptoms are present, these tests help in identifying additional sites of disease.

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Serologic Analyses

Other tests may include serologic analyses for varicella, measles, herpes simplex virus, Epstein-Barr virus, cytomegalovirus (CMV), hepatitis A, hepatitis B, and hepatitis C. Perform these tests to document susceptibility in patients who will be receiving immunosuppressive therapy. In addition, these tests may provide evidence of the cause (eg, Epstein-Barr virus).

Serologic results can help in identifying patients who may benefit from transfusion with CMV-negative blood products, especially if bone marrow transplantation is eventually offered. As noted above, however, this is a marginal/arguable recommendation.

Order these tests to confirm previous exposure to a hepatitis virus before blood transfusions are administered.

HIV infection

Non-Hodgkin lymphoma, particularly a primary tumor of the CNS, can be a presenting sign of immunodeficiency, such as that resulting from HIV/acquired immunodeficiency syndrome (AIDS). Perform HIV serologic tests in patients who have risk factors for HIV exposure or in individuals with primary CNS lymphoma.

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Biopsy and Paracentesis

A histologic diagnosis must be obtained. Flow cytometric analysis of tumor cell markers has become the standard for lymphoma subtyping. [52] Cytogenetic analysis is sometimes helpful in equivocal cases.

For patients with an abdominal tumor, tissue is generally available from resection or intraoperative biopsy.

Patients with mediastinal disease frequently have enlarged supraclavicular or cervical nodes, which can enable diagnosis without thoracotomy.

As an alternative, a diagnosis may be made by using pleural/peritoneal fluid or involved bone marrow (especially if the CBC is abnormal and/or if imaging studies demonstrate abnormal signal intensity of the marrow). In rare cases, cerebrospinal fluid (CSF) can be used.

Bone marrow aspiration and biopsy

Biopsy is necessary to assess for evidence of bone marrow involvement in patients with lymphomas, with bilateral biopsy being superior to a unilateral procedure. Bone marrow aspiration is potentially less sensitive than a core biopsy.

A finding of more than 25% marrow blasts is generally regarded as diagnostic of acute leukemia. levels of lymphoma involvement lower than this indicate stage 4 disease.

Polymerase chain reaction (PCR) assays are being used experimentally to detect and monitor minimal residual disease in the marrow. [53, 54] In the future, postinduction measurement of minimal residual disease may improve precision in determining treatment responses and/or treatment assignments.

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Histologic Findings

Several classification systems for non-Hodgkin lymphoma are available. Examples are the Kiel classification system and the NCI Working Formulation. At present, the Revised European-American Lymphoma (REAL) classification system is gaining acceptance as the criterion standard for classifying adult non-Hodgkin lymphoma. For classifying childhood non-Hodgkin lymphoma, this system is overly complicated because it includes numerous diagnoses that are rarely or never observed in children.

Adult non-Hodgkin lymphomas are characterized as low, intermediate, or high grade, and they can have a diffuse or nodular appearance. In contrast, childhood non-Hodgkin lymphomas are almost always high grade and diffuse. In general, they can be divided into 3 major classes, or even 4 classes if one differentiates the 2 most common types of large cell lymphomas (LCLs), B-cell and T-cell LCLs. The 3 major classes—lymphoblastic lymphomas, small noncleaved cell lymphomas (SNCCLs), and LCLs—are described below.

For a particular tumor, achieving agreement among pathologists is sometimes difficult. However, synthesis of the histologic, immunohistochemical, cytogenetic, and clinical and/or anatomic data almost always results in a clear diagnosis.

Lymphoblastic lymphomas

Lymphoblastic lymphoma cells are indistinguishable from the lymphoblasts of acute lymphoblastic leukemia (ALL). The cells are monotonous and associated with a high nuclear-to-cytoplasmic ratio. Their nuclei are often convoluted and contain finely stippled chromatin. Nucleoli are usually visible but are not prominent.

Immunohistochemical analysis usually reveals T-cell markers, including CD5 and CD7. Common ALL antigen (CALLA) is occasionally observed.

A minor subset of lymphoblastic lymphomas expresses the precursor B-cell phenotype typical of childhood ALL. This phenotype includes the surface antigens CALLA and B4 and the human leukocyte antigen (HLA)–DR.

Small noncleaved cell lymphomas

Small noncleaved cell lymphomas (SNCCLs) can be classified as Burkitt or non-Burkitt (Burkittlike) lymphomas. The distinction may be subtle, and its clinical significance is unclear.

Burkitt lymphoma cells are notably uniform in size and shape, and they usually contain multiple prominent nucleoli. In contrast, extensive cellular pleomorphism, or occasionally the presence of a single nucleolus in most cells, suggests a diagnosis of Burkittlike lymphoma. SNCCL cells have slightly more cytoplasm than do lymphoblastic lymphoma cells. The cytoplasm is basophilic and usually contains lipid-filled vacuoles.

Macrophages often infiltrate the tumors, lending the classic starry-sky appearance. However, this observation is not pathognomic of Burkitt lymphoma.

The tumor cells are mature B cells, as evidenced by the surface expression of immunoglobulin (usually immunoglobulin M), CD19, CD20, and HLA-DR. CALLA is usually present.

Immunophenotyping results suggest that Burkittlike lymphoma cells are more likely than Burkitt lymphoma cells to express the BCL-6 oncogene, and they exhibit relatively low levels of apoptosis. [55]

Because of the features described, Burkittlike lymphoma appears to be biologically distinct from Burkitt lymphoma; it is perhaps most closely related to the B-cell LCLs.

Large cell lymphomas

LCLs are a heterogeneous group, with LCL in most cases being classified as the B- or T-cell type. The B-cell–derived LCLs histologically merge with the SNCCLs. In terms of the expression of cell-surface proteins, these tumors are currently indistinguishable. If infiltrating macrophages are present, these cells can serve as a reference by which the tumor cells are measured. In B-cell LCLs, many or most of the tumoral nuclei are larger than those of the macrophages. B-cell LCLs can be divided into germinal center and nongerminal center subtypes, a distinction that carries prognostic significance in adult patients; in pediatric patients, germinal-center type B-LCLs predominate, which explains, in part, the overall better outcomes for pediatric patients (versus adults) with B-cell LCL. [56]

Anaplastic LCLs are more common than B-cell LCLs and are derived from T cells, as evidenced by their TCR gene rearrangements. However, anaplastic LCLs may express few T-cell surface markers. Their hallmark is the expression of CD30, or Ki-1, an antigen first recognized on Hodgkin lymphoma cells. Aberrant expression of myeloid markers CD13 and CD33 has more recently been reported as a sensitive (but not specific) marker of ALK+ anaplastic LCL. [57]

Other cell surface markers that may be observed are HLA-DR and the IL-2 receptor. Finally, a small number of LCLs do not exhibit a clear T-cell or B-cell phenotype. At least some of these tumors are of histiocytic origin.

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Staging

Several systems for classifying non-Hodgkin lymphomas have been proposed. The St Jude system (ie, the Murphy system) has gained the widest acceptance. [58] This system is as follows:

  • Stage I - Single extranodal tumor or single anatomic area (nodal), excluding the mediastinum or abdomen
  • Stage II - Single extranodal tumor with regional node involvement; primary gastrointestinal (GI) tumor with or without associated involvement of mesenteric nodes, with gross total resection; or, on the same side of the diaphragm, 2 or more nodal areas, or 2 single (extranodal) tumors with or without regional node involvement
  • Stage III - Any primary mediastinal, pleural, or thymic intrathoracic tumor; any extensive and unresectable abdominal tumor; any primary paraspinous or epidural tumor regardless of other sites; or, on both sides of the diaphragm, 2 or more nodal areas, or 2 single (extranodal) tumors with or without regional node involvement
  • Stage IV - Any of the above with initial CNS or marrow (< 25%) involvement
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