What type of testing is used in non-Hodgkin's lymphoma?

Diagnostic Testing in Non-Hodgkin's Lymphoma

The diagnosis of non-Hodgkin's lymphoma requires an excisional lymph node biopsy as the essential first step, with fine needle aspirations being inadequate for proper diagnosis. 1, 2

Essential Diagnostic Tests

Initial Diagnosis

• Surgical specimen/excisional lymph node biopsy: Provides enough material for fresh frozen and formalin-fixed samples 2
  • Must be processed by an experienced pathology institute
  • Should include immunohistochemistry studies (particularly CD20)
  • Diagnosis should be according to WHO classification

Immunophenotyping

• Adequate immunophenotyping: Essential to establish lymphoma subtype 2, 1
  • CD20 immunohistochemistry for B-cell lymphomas
  • Additional markers based on suspected subtype:
    • B-cell markers: CD10, Bcl2, Bcl6, IRF4/MUM1
    • T-cell markers when appropriate

Laboratory Studies

• Complete blood count with differential 2, 1
• Comprehensive metabolic panel 2, 1
• Lactate dehydrogenase (LDH) - important prognostic marker 2, 1
• Uric acid 2, 1
• Hepatitis B and C testing - especially if rituximab therapy is considered 2, 1
• HIV screening 2, 1
• Protein electrophoresis - recommended for B-cell lymphomas 2

Imaging Studies

• CT scan of chest, abdomen, and pelvis - standard for all patients 2, 1
• PET-CT scan - useful in selected cases for staging and response assessment 2, 1
• Chest X-ray - may be used in addition to CT 2

Bone Marrow Assessment

• Bone marrow aspirate and biopsy - required for complete staging 2, 1
  • Essential for detecting marrow involvement (occurs in up to 46.8% of patients) 3

Additional Testing in Specific Situations

• Lumbar puncture/CSF analysis: For high-risk patients with:

  • More than two adverse IPI parameters
  • Involvement of bone marrow, testis, spine, or base of skull
  • CNS symptoms
  • Blastic variant 2

• Peripheral blood flow cytometry: When CBC shows lymphocytosis 2

• Serum beta-2 microglobulin: Useful prognostic marker in some cases 2

• Echocardiography/MUGA scan: To assess cardiac function if anthracycline therapy is planned 2

Risk Assessment and Staging

• Ann Arbor staging system: Standard for lymphoma staging 2, 1

  • Includes designation of bulky disease

• International Prognostic Index (IPI): Essential for risk stratification 2, 1

Common Pitfalls and Considerations

1. Inadequate biopsy specimens: Fine needle aspirations or core biopsies are inadequate for initial diagnosis and should only be used in emergency situations or for patients unsuitable for curative therapy 2

2. Missing bone marrow involvement: Bone marrow biopsy is essential for complete staging, though some argue it may not be necessary in all cases 4

3. Overlooking hepatitis status: Testing for hepatitis B is critical due to risk of reactivation with immunotherapy 2, 1

4. Insufficient immunophenotyping: Proper classification requires adequate immunohistochemical studies beyond basic H&E staining 2

5. Inadequate follow-up testing: After treatment, appropriate follow-up should include:

   • Physical examination every 3 months for 2 years, then every 6 months for 3 years, then annually
   • Blood counts and LDH at 3,6,12, and 24 months
   • Appropriate imaging based on initial sites of disease 2, 1

By following this comprehensive diagnostic approach, clinicians can ensure accurate diagnosis, appropriate staging, and optimal treatment planning for patients with non-Hodgkin's lymphoma.