Diffuse Large B-Cell Lymphoma (DLBCL)


For a diagnosis of diffuse large B-cell lymphoma (DLBCL), multiple steps are required to determine the subtype, stage of disease, and the extent to which tissues and organ systems are involved. Besides a complete physical examination, the initial evaluation includes documentation of the patient’s medical and family history, current medications, comorbidities, and current signs and symptoms.1

A variety of tests are used to assess the disease stage and condition, including laboratory testing, biopsy, flow cytometry, genetic testing, imaging, and staging of DLBCL.

Laboratory Testing for Diagnosing DLBCL

Laboratory testing includes collecting a blood sample from the patient for a complete blood cell (CBC) count and comprehensive metabolic panel. 

The CBC count tests for anemia, thrombocytopenia, and/or leukopenia; these indicate the degree of bone marrow involvement in DLBCL because B cells develop and mature in the bone marrow.1 

The comprehensive metabolic panel assesses serum electrolyte levels, renal and hepatic function, and lactic dehydrogenase (LDH) levels. The degree of LDH and uric acid elevation indicates the tumor burden. Additionally, the LDH level is a useful prognostic factor, reflecting the severity of DLBCL, response to treatment, and relapse. Elevated uric acid, potassium, and phosphorus levels with a decreased calcium level may indicate tumor lysis syndrome, which can occur during chemotherapy.1 

The ꞵ2-microglobulin level, another serum biomarker for B-cell lymphomas like DLBCL, should be assessed.1 Additionally, hypercalcemia is a biomarker of aggressive DLBCL and high-risk features.2

Patients in whom renal dysfunction develops as a consequence of chemotherapy require a change in treatment dosage. DLBCL may also affect the kidneys directly and cause dysfunction.1 

Biopsy for DLBCL Confirmation

To confirm a diagnosis of DLBCL, biopsy of an enlarged lymph node is required to examine the involved tissues and stage the disease.3 Excisional lymph node biopsy is preferable to fine needle aspiration biopsy or core needle biopsy because the samples will be large enough to allow a complete assessment of the lymph node architecture, cellular composition, and growth patterns; these may not be evident in the small tissue samples obtained with fine needle aspiration or core needle biopsy.4,5 

Histological examination of stained biopsy samples identifies the presence of abnormally large neoplastic B cells and allows the histopathological classification of specific DLBCL subtypes.6 

Bone marrow aspirate and biopsy samples, often collected bilaterally from the iliac crests, are used for lymphoma staging. In advanced stages of DLBCL, bone marrow involvement may result in lymphomatous meningitis, and a lumbar puncture is required for chemical analysis of the cerebrospinal fluid and diagnostic confirmation.4,7  

Flow Cytometry for Diagnosing DLBCL

Flow cytometry is used to determine whether lymphoma originates in B cells or T cells and differentiates among the various DLBCL phenotypes by identifying the specific clonal cell population and the DLBCL subtype.8

Flow cytometry is used to ascertain absolute counts of peripheral blood lymphocytes: B cells, including CD19, CD20, CD22, and CD79a; T cells, including CD3, CD4, CD5, and CD8; and regulatory T cells, including CD4 and CD25. Decreased lymphocyte counts have been found to correspond to DLBCL stage and may assist with prognosis.8

Genetic Testing to Detect DLBCL Mutations

Cytogenetic testing, including fluorescent in situ hybridization (FISH), detects the chromosomal translocations that are often hallmark genetic drivers of DLBCL, especially involving BCL6, BCL2, and MYC.9

Gene expression profiling differentiates between the 2 major molecular subtypes of DLBCL,  providing information that clarifies the prognosis and affects treatment decisions. It determines whether a patient has the germinal center B-cell (GCB) or activated B-cell (ABC) molecular subtype of DLBCL according to the cell of origin. Generally, GCB DLBCL subtypes carry a better prognosis than ABC subtypes.10,11 

Genetic testing may also determine the presence of double-hit or triple-hit DLBCL, characterized by 2 or 3 chromosomal translocations, respectively, or of double expressor DLBCL, in which 2 mutated genes are both highly expressed.11

Whole-genome or whole-exome sequencing and transcriptome sequencing detect recurrent mutations that contribute to the development of DLBCL. This identification of driver mutations may assist with treatment decision making and the development of targeted therapeutic agents for specific DLBCL subtypes.11

Read more about DLBCL genetics

Types of Imaging Used to Diagnose DLBCL

Computed tomography (CT) assesses the degree of lymphadenopathy and the involvement of extranodal and/or visceral sites in the neck, chest, abdomen, and pelvis. CT may also be used to assess the treatment response following chemotherapy and aid in the selection of target sites for radiation therapy.12 

Bone scans assess for DLBCL-related involvement of the skeleton in patients with unexplained bone pain or elevated alkaline phosphatase levels.12

Gallium 67 scanning is used to stage DLBCL. Gallium uptake is increased in most aggressive or highly aggressive lymphomas, such as DLBCL. Gallium 67 scans assess the level of disease activity, identify sites of relapse, and evaluate responsiveness to treatment.12

Before chemotherapy is initiated, multigated acquisition (MUGA) scans are used to determine the patient’s ejection fraction and identify any cardiotoxic effects of anthracycline treatment for DLBCL.12

Positron emission tomography (PET) uses fluorodeoxyglucose to stage DLBCL. Increased glucose uptake indicates heightened cellular metabolic activity. PET is mandatory for staging DLBCL because CT can miss extranodal disease. Baseline scans identify initial locations of disease and can be compared with end-of-treatment scans, which are required to document DLBCL remission according to the Deauville criteria.12, 13

Staging Structure in DLBCL Diagnosis

The 3 prognostic indices used for risk stratification in patients with DLBCL are the International Prognostic Index (IPI), the Revised International Prognostic Index (R-IPI), and the National Comprehensive Cancer Network International Prognostic Index (NCCN-IPI). Risk stratification is based on patient age, performance status, lactate dehydrogenase levels, imaging such as PET and CT, extranodal involvement, and Ann Arbor stage for patients with non-Hodgkin lymphoma (NHL).13 

In Ann Arbor staging, available imaging and biopsy data are used to differentiate low-risk from high-risk DLBCL by classifying disease in 1 of 4 stages3,14:

  • Stage I: involvement of only 1 lymph node region, structure, or extranodal site
  • Stage II: involvement of 2 or more lymph node regions or structures on the same side of the diaphragm
  • Stage III: involvement of lymph node regions or structures on both sides of the diaphragm
  • Stage IV: widespread, multiorgan involvement (including the liver, lungs, and bone marrow) beyond lymph tissues or regions

The Ann Arbor system also places a letter (A or B) next to the stage (I through IV) to indicate reported symptoms.13,14

  • A: absence of systemic symptoms
  • B: presence of unexplained fever of 38°C or higher, drenching night sweats, and weight loss of 10% or more of original body weight

Because of the aggressive nature of DLBCL, a rapid and accurate diagnosis is critical to ensure the immediate initiation of appropriate treatment to optimize patient outcomes.

Read more about DLBCL life expectancy

References

  1. Gandhi S. Diffuse large B-cell lymphoma (DLBCL) workup. Medscape. Updated May 6, 2021. Accessed August 5, 2022.
  2. Gauchy AC, Kanagaratnam L, Quinquenel A, et al. Hypercalcemia at diagnosis of diffuse large B-cell lymphoma is not uncommon and is associated with high-risk features and a short diagnosis-to-treatment interval. Hematol Oncol. 2020;38(3):326-333. doi:10.1002/hon.2735
  3. Patient education: diffuse large B cell lymphoma diagnosis. UpToDate. Updated July 22, 2022. Accessed August 5, 2022.
  4. Gandhi S. Diffuse large B-cell lymphoma (DLBCL) workup: biopsy and lumbar puncture. Medscape. Updated May 6, 2021. Accessed August 5, 2022.
  5. Abdulla M, Laszlo S, Triumf J, et al. Core needle biopsies for the diagnosis of diffuse large B-cell lymphoma – a great concern for research. Acta Oncologica. 2017;56(1):106-109. doi:10.1080/0284186X.2016.1245863
  6. Xie Y, Pittaluga S, Jaffe ES. The histological classification of diffuse large B-cell lymphomas. Semin Hematol. 2015;52(2):57-66. doi:10.1053/j.seminhematol.2015.01.006
  7. Van Horn A. Lymphomatous meningitis: early diagnosis and treatment. Clin J Oncol Nurs. 2009;13(1):90-94. doi:10.1188/09.CJON.90-94
  8. Rusak M, Bołkun Ł, Chociej-Stypułkowska J, Pawlus J, Kłoczko J, Dąbrowska M. Flow-cytometry-based evaluation of peripheral blood lymphocytes in prognostication of newly diagnosed DLBCL patients. Blood Cells Mol Dis. 2016;59:92-96. doi:10.1016/j.bcmd.2016.04.004
  9. Testoni M, Zucca E, Young KH, Bertoni F. Genetic lesions in diffuse large B-cell lymphomas. Ann Oncol. 2015;26(6):1069-1080. doi:10.1093/annonc/mdv019
  10. Liu Y, Barta SK. Diffuse large B-cell lymphoma: 2019 update on diagnosis, risk stratification, and treatment. Am J Hematol. 2019;94(5):604-616. doi:10.1002/ajh.25460
  11. Nowakowski GS, Czuczman MS. ABC, GCB, and double-hit diffuse large b-cell lymphoma: does subtype make a difference in therapy selection? Am Soc Clin Oncol Educ Book. 2015;(35):e449-e457. doi:10.14694/EdBook_AM.2015.35.e449
  12. Gandhi S. Diffuse large B-cell lymphoma (DLBCL) workup: imaging studies. Medscape. Updated May 6, 2021. Accessed August 5, 2022.
  13. Barrington SF, Mikhaeel NG. PET scans for staging and restaging in diffuse large B-cell and follicular lymphomas. Curr Hematol Malig Rep. 2016;11:185-195. doi:10.1007/s11899-016-0318-1
  14. Gandhi S. Diffuse large B-cell lymphoma workup: staging. Medscape. Updated May 6, 2021. Accessed August 5, 2022.

Reviewed by Harshi Dhingra, MD, on 9/9/2022.

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