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Lymphoma Classification Approach (WHO 2022)

Lymphoma Classification Approach (WHO 2022): Lymphoma Evaluation → Specimen Assessment → Architectural Pattern → B-cell vs T-cell → B-Cell Lymphoma Subt...

Interactive Decision Tree

Mini Map

Algorithm Steps

  1. Start

    Lymphoma Evaluation

    Systematic classification approach

    1. Action

      Specimen Assessment

      Evaluate adequacy

      • Excisional biopsy preferred (architecture)
      • Core biopsy acceptable if adequate
      • FNA insufficient for initial diagnosis
      • Fresh tissue for flow cytometry
      • Submit for cytogenetics/molecular
      1. Decision

        Architectural Pattern

        Follicular vs diffuse vs nodular

        • Follicular: FL, nodal MZL, MCL mantle zone pattern
        • Diffuse: DLBCL, BL, T-cell lymphomas
        • Nodular sclerosing: Classic Hodgkin
        • Interfollicular: Some T-cell, AITL
        1. Decision

          B-cell vs T-cell

          Lineage determination

          • CD20, PAX5, CD79a → B-cell
          • CD3, CD2, CD5, CD7 → T-cell
          • Reed-Sternberg cells: CD30+, CD15+, PAX5 weak
          • Consider NK if CD3-, CD56+
          1. Action

            B-Cell Lymphoma Subtyping

            Major categories

            • DLBCL: Large cells, diffuse, CD20+, GCB vs non-GCB
            • Follicular: BCL2+, CD10+, grade 1-2 vs 3
            • MCL: CD5+, cyclin D1+, SOX11+
            • MZL: CD5-, CD10-, CD23-
            • Burkitt: Ki-67 ~100%, MYC+
            1. Action

              Molecular/Cytogenetics

              Required for many diagnoses

              • DLBCL: MYC, BCL2, BCL6 FISH for HGBL
              • FL: t(14;18) BCL2-IGH
              • MCL: t(11;14) CCND1-IGH
              • Burkitt: MYC translocation
              • AITL: TET2, DNMT3A, RHOA mutations
              1. Outcome

                WHO 5th Edition Diagnosis

                Integrated diagnosis with all parameters

          2. Action

            T-Cell Lymphoma Subtyping

            Mature T-cell neoplasms

            • PTCL-NOS: Most common, exclusion diagnosis
            • AITL: CD10+, PD1+, CXCL13+, TFH markers
            • ALCL: CD30+, ALK+ or ALK-
            • Adult T-cell: HTLV-1+, CD4+, CD25+
            • Mycosis fungoides: Epidermotropism, cerebriform
          3. Action

            Hodgkin Lymphoma

            Classical vs NLPHL

            • Classical HL: RS cells CD30+, CD15+, PAX5 weak
            • Subtypes: NS (most common), MC, LR, LD
            • NLPHL: LP cells ('popcorn'), CD20+, CD45+, CD15-
            • EBV in situ hybridization helpful

Guideline Source

WHO Classification of Haematolymphoid Tumours 5th Edition

Clinical Safety Information

Clinical Decision Support — Not a Substitute for Clinical Judgment

Individual patient factors may require deviation from these recommendations.

Known Limitations

  • WHO 5th Edition recently released - evolving criteria
  • Requires flow cytometry, IHC, cytogenetics, molecular
  • Grey zone lymphomas challenging
  • Some entities need specific molecular markers
  • Clinical staging separate from pathologic diagnosis

Applicable Regions

USAUUKEU

AU: eviQ and RCPA guidelines

UK: NICE lymphoma pathways

US: WHO 5th Edition and ICC classification

Version 1Next review: 2027-01-01

Frequently Asked Questions

What is the Lymphoma Classification Approach (WHO 2022)?

The Lymphoma Classification Approach (WHO 2022) is a diagnostic clinical algorithm for Pathology. It provides a structured decision tree to guide clinical decision-making, based on WHO Classification of Haematolymphoid Tumours 5th Edition.

What guideline is the Lymphoma Classification Approach (WHO 2022) based on?

This algorithm is based on WHO Classification of Haematolymphoid Tumours 5th Edition (DOI: 10.1182/blood.2022016867).

What are the limitations of the Lymphoma Classification Approach (WHO 2022)?

Known limitations include: WHO 5th Edition recently released - evolving criteria; Requires flow cytometry, IHC, cytogenetics, molecular; Grey zone lymphomas challenging; Some entities need specific molecular markers; Clinical staging separate from pathologic diagnosis. Individual patient factors may require deviation from these recommendations.

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