What is the protocol for ordering a lymph node biopsy for suspected lymphoma?

Protocol for Ordering a Lymph Node Biopsy for Suspected Lymphoma

An excisional or incisional lymph node biopsy is mandatory for the initial diagnosis of lymphoma, as fine needle aspirations are inadequate for establishing a reliable diagnosis. 1

Biopsy Selection Process

Type of Biopsy

• Excisional biopsy: Preferred method whenever possible 2, 1
• Incisional biopsy: Alternative when complete excision is not feasible
• Core needle biopsy: Only when excisional/incisional biopsy is not possible (e.g., retroperitoneal nodes) or to document relapse 2
  • Note: Core biopsies have higher non-diagnostic rates (8.3% vs 2.8% for excisional) 3

Node Selection Criteria

1. Size and location:

   • Select the largest, most accessible abnormal node
   • Peripheral nodes are preferred over deep nodes when accessible 4
   • For PET-positive disease, target the node with highest standardized uptake value 1

2. Timing:

   • Perform biopsy before initiating any therapy
   • If preoperative systemic therapy is planned, place a marker (surgical clip or carbon) into the tumor during biopsy 2

Pre-Biopsy Requirements

Clinical Information to Include on Requisition

1. Previous lymphoma diagnosis (if applicable) with dates and sites
2. Pattern of lymphadenopathy (localized vs. generalized)
3. Presence of organomegaly
4. Relevant hematological findings (lymphocytosis, pancytopenia)
5. Constitutional symptoms (fever, night sweats, weight loss)
6. HIV status and other immune abnormalities
7. Autoimmune disease history
8. Relevant serology (EBV, HTLV-I) 2

Imaging Studies Before Biopsy

1. PET-CT scan (skull base to mid-thigh): Recommended for all patients with suspected lymphoma 2, 1

   • Helps identify the most appropriate node for biopsy
   • Improves staging accuracy
   • Essential before considering radiation therapy

2. Contrast-enhanced CT: Required if PET-CT unavailable 2, 1

Biopsy Procedure Protocol

Specimen Handling Instructions

1. Critical: Send lymph node fresh and intact - never immerse unsectioned lymph node in fixative 2
2. Labeling: Include patient name, medical record number, and anatomic site 2
3. Transport: Send to pathology immediately in sterile container
4. Special instructions:
   • Request tissue preservation for ancillary studies (immunohistochemistry, flow cytometry, molecular studies)
   • Specify if multiple fixation methods are needed (formalin for PCR studies, B5 for cytological detail) 2
   • Request snap-freezing of a portion for potential molecular studies 2

Documentation in Biopsy Order

1. Specify exact anatomic site
2. Indicate procedure type (excisional, incisional, core)
3. Note suspected diagnosis
4. Include relevant clinical history as outlined above
5. Request WHO classification of lymphoid neoplasms 2, 1

Post-Biopsy Considerations

Pathology Assessment Requirements

1. Histological sections at 2mm intervals 2
2. Immunohistochemistry panel appropriate for suspected lymphoma type:
   • For Hodgkin lymphoma: CD3, CD15, CD20, CD30, CD45, CD79a, PAX5 2
   • For other lymphomas: Appropriate B-cell, T-cell, and other markers

Follow-up After Biopsy

1. If biopsy is non-diagnostic but lymphoma still suspected:
   • Repeat with excisional biopsy if initial was core biopsy 3
   • Consider biopsy of different site if available

Common Pitfalls to Avoid

1. Never rely on fine needle aspiration alone for lymphoma diagnosis 1
2. Avoid placing lymph node in fixative before pathologist evaluation 2
3. Don't perform core biopsy when excisional biopsy is feasible 1
4. Beware that core biopsies may miss transformation in follicular lymphoma (3.3% vs 7.6% detection rate compared to excisional) 3
5. Remember that smaller peripheral nodes (≤2cm) may still yield diagnostic information when larger deep nodes are inaccessible 4

By following this protocol, you can ensure optimal tissue acquisition for accurate lymphoma diagnosis, which is critical for determining appropriate treatment and improving patient outcomes.