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Diagnosing DLBCL

• Patients are diagnosed based on a combination of characteristics including clinical presentation, laboratory, radiologic, and pathologic assessments^9,10
  • The clinical presentation of DLBCL is variable^2,5
  • Most patients present with peripheral lymphadenopathy, or enlarged nodes in the mediastinum, the mesenteric region, or the retroperitoneum. More than 30% of patients present with extranodal involvement^5,11
  • The most common extranodal disease sites are the bone marrow, the skin, the GI tract, and the lung^2,12
  • Systemic B-symptoms, such as fever and night sweats, occur in approximately one-third of patients²
• Diagnosis of DLBCL should be made on the basis of surgical biopsy
  • Excisional or incisional biopsy of a peripheral lymph node is required^10,11
  • Fine needle aspiration (FNA) or core needle biopsy alone is generally not suitable for the initial diagnosis of lymphoma. In specific circumstances where a lymph node is not easily accessible for excisional or incisional biopsy, a combination of core biopsy and FNA, in conjunction with other techniques (immunohistochemistry, flow cytometry, or cytogenetics analyses) used for making the differential diagnosis, may be sufficient for diagnosis¹³
• Microscopic pathology¹⁴: DLBCL often completely effaces the normal lymph node architecture, although partial nodal involvement can be seen. There are sheets of large atypical lymphoid cells and fine or broad bands of sclerosis that may be present in the background. Specific cytologic features found in DLBCL have led to the recognition of DLBCL subtypes by the WHO
  • Diagnosis is made with immunophenotyping^11,13 (Table 2). These assays should be used with other diagnostic tools
  • The 2 methods most frequently used to assess immunophenotype are immunohistochemistry (IHC) and flow cytometry¹³
  • Cytogenetic analysis by fluorescence in situ hybridization (FISH) or polymerase chain reaction (PCR) testing can be used to determine the presence of cytogenetic events associated with DLBCL, such as chromosomal translocations t(14;18), t(3;v), t(8;14), or rearrangements of genes, such as those encoding bcl-6 and IgH^9,13,15

Table 2. Characterizing immunophenotypes in DLBCL. These assays should be used with other diagnostic tools.^{1,11,13,16-24}

• Essential laboratory workup parameters include a complete blood count (CBC) with differential, lactate dehydrogenase (LDH), beta-₂-microglobulin (B₂M), and uric acid levels^10,13
• Initial radiologic imaging assessment must include computed tomography (CT) scans of the chest, abdomen, and pelvis and also fluorodeoxyglucose-positron emission tomography (¹⁸F-FDG PET) scans^11,25
  • It is recommended that chest/abdominal/pelvic CT scans be conducted with contrast of diagnostic quality¹³

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