Which laboratory tests should be ordered to diagnose lymphoma?

Laboratory Tests for Lymphoma Diagnosis

The diagnosis of lymphoma requires tissue biopsy with comprehensive immunophenotyping, combined with essential laboratory studies including CBC with differential, LDH, comprehensive metabolic panel, and hepatitis B testing. 1

Essential Tissue Diagnosis

Biopsy Requirements

• Excisional or incisional lymph node biopsy is the gold standard for initial lymphoma diagnosis 1
• Fine-needle aspiration (FNA) alone is insufficient for initial diagnosis except in unusual circumstances 1
• Core needle biopsy combined with FNA plus ancillary techniques (immunohistochemistry, flow cytometry, PCR, FISH) may be adequate when excisional biopsy is not accessible, particularly for CLL/SLL diagnosis 1
• Exception: Flow cytometry of peripheral blood is adequate for CLL/SLL diagnosis without requiring biopsy 1

Required Immunophenotyping

For paraffin section immunohistochemistry, the recommended panel includes: 1

• CD3, CD5, CD10, CD20, CD23, cyclin D1

For flow cytometry, cell surface markers should include: 1

• Kappa/lambda light chains
• CD19, CD20, CD5, CD23, CD10

Essential Laboratory Studies

Hematologic and Chemistry Tests

• CBC with differential and platelet count 1
• Lactate dehydrogenase (LDH) 1
• Comprehensive metabolic panel (renal and liver function) 1
• Performance status assessment 1
• Documentation of B symptoms (unexplained fever >38°C, drenching night sweats, weight loss >10% body weight within 6 months) 1

Mandatory Infectious Disease Screening

• Hepatitis B testing (HBsAg and HBcAb) is essential before initiating anti-CD20 monoclonal antibody therapy due to reactivation risk 1
• Hepatitis C serology (mandatory for all marginal zone lymphomas; include HCV-RNA PCR and genotyping if positive) 1
• HIV testing for appropriate risk stratification 1

Additional Prognostic Laboratory Tests

• Beta-2-microglobulin (useful for prognostic assessment) 1
• Uric acid (particularly important before treatment initiation) 1
• Protein electrophoresis with serum and urine immunofixation 1
• Direct antiglobulin (Coombs) test (optional in splenic marginal zone lymphoma) 1

Bone Marrow Evaluation

• Unilateral bone marrow biopsy ± aspirate is essential at treatment initiation for most lymphomas 1
• Exception: Bone marrow biopsy not required for CLL/SLL when clonal lymphocytosis is identified by flow cytometry 1
• Bone marrow biopsy may be deferred in low-bulk indolent disease with radiographic stage III if observation is planned, as it won't change management 1
• Bilateral core biopsies are recommended if radioimmunotherapy is considered 1

Molecular and Cytogenetic Studies

For Prognostic and Therapy Determination

Cytogenetics and/or FISH to detect: 1

• t(11;14), t(11q;v), +12, del(11q), del(13q), del(17p)

Molecular genetic analysis for: 1

• Immunoglobulin heavy chain variable gene (IGHV) mutation status
• CD38 and Zap-70 expression by flow cytometry or immunohistochemistry

Pre-Treatment Cardiac Assessment

• MUGA scan or echocardiogram is required if anthracycline or anthracenedione-based regimen is planned 1

Pregnancy and Fertility Considerations

• Pregnancy testing in women of childbearing age if chemotherapy is planned 1
• Discussion of fertility issues and sperm banking should be addressed when appropriate 1

Common Pitfalls to Avoid

• Never rely on FNA alone for initial diagnosis—this is the most common diagnostic error 1
• Do not omit hepatitis B testing before rituximab-based therapy, as reactivation can be life-threatening 1
• Ensure adequate tissue is obtained for immunophenotyping; nondiagnostic samples require rebiopsy 1
• Remember that bone marrow biopsy is essential for early-stage disease (stage I/II) to confirm true localized disease 1