Specialty Guide · Path-iQ Global Pathology Review
The WHO Classification of Haematolymphoid Tumours (5th edition, 2022) restructured lymphoma classification around integrated morphological, immunophenotypic, genetic, and clinical data — recognising over 80 distinct lymphoid and histiocytic neoplasms. Accurate lymphoma diagnosis requires core biopsy or excision biopsy (not FNA alone), expert haematopathology interpretation, and close integration with flow cytometry, FISH, and molecular data.
Fine needle aspiration (FNA) of a lymph node yields single cells and small clusters — insufficient to assess the nodal architecture, which is critical for lymphoma classification. Exceptions where FNA may be diagnostic: CLL/SLL (flow cytometry on peripheral blood usually sufficient); highly characteristic metastatic carcinoma to lymph node; relapsed/refractory lymphoma where prior diagnosis is known and only cell viability for flow cytometry is needed. For a new lymphoma diagnosis, an excision biopsy of the entire node is ideal. Where surgery carries risk, a minimum 18-gauge core needle biopsy (3–5 cores) with simultaneous material submitted for: (1) formalin fixation for FFPE histology, (2) fresh tissue for flow cytometry, (3) snap-frozen for cytogenetics/FISH, and (4) RPMI for cell culture if lymphoblastic lymphoma suspected.
| Lymphoma | Key Histology | IHC Profile | Genetics | Clinical Notes |
|---|---|---|---|---|
| Diffuse large B-cell lymphoma, NOS (DLBCL-NOS) | Large cells in diffuse pattern; centroblastic (most) or immunoblastic (worse prognosis) variants | CD20+, PAX5+, CD79a+, BCL6±, CD10±, MUM1±; Ki-67 >40% (usually 60–90%) | BCL6 rearrangements (~30%); BCL2 rearrangement (~20%); MYC rearrangement single-hit; COO: GCB vs non-GCB (Hans algorithm) | R-CHOP standard (GCB); polatuzumab vedotin + R-CHP for high-risk (POLARIX trial); double-hit/triple-hit → R-EPOCH |
| High-grade B-cell lymphoma with MYC and BCL2 rearrangements (HGBL-MYC/BCL2) — "Double-hit lymphoma" | Morphologically DLBCL or intermediate DLBCL/BL; high Ki-67; starry-sky may be present | CD20+, BCL2+++ (strong in most), MYC IHC ≥40% of cells; Ki-67 ≥80% | MYC + BCL2 dual FISH rearrangement — MANDATORY dual FISH when MYC IHC ≥40% in GCB-DLBCL; BCL2 t(14;18) + MYC translocation | R-CHOP insufficient; R-EPOCH or DA-EPOCH-R preferred; intensified consolidation or auto-SCT; CAR-T in relapse |
| Follicular lymphoma (FL) | Follicular architecture (at least partially); centrocytes (cleaved cells) + centroblasts; grading 1–2 (indolent) vs grade 3A vs grade 3B (aggressive) | CD20+, CD10+, BCL6+, BCL2+++ (strong; germinal centre cells normally BCL2−), CD5−, Cyclin D1−; Ki-67 <20% (grade 1–2) | t(14;18)(q32;q21) → IGH-BCL2 fusion in ~90% grade 1–3A; BCL2 FISH; grade 3B often BCL2-negative, t(14;18)-negative | Grade 1–2: watch-and-wait if asymptomatic; R-bendamustine or R-CHOP for treatment-requiring; obinutuzumab-based regimens; grade 3B: treat as DLBCL |
| Mantle cell lymphoma (MCL) | Monomorphic small-to-medium lymphoid cells; mantle zone, diffuse, nodular, or blastoid (worst) patterns; hyalinised blood vessels | CD20+, CD5+, Cyclin D1+ (nuclear, pathognomonic), SOX11+, CD10−, BCL6−; FMC7+; CD23− | t(11;14)(q13;q32) → CCND1-IGH; IGHV unmutated (aggressive) vs mutated (indolent "nnMCL"); TP53, CDKN2A deletions = high-risk | Blastoid/pleomorphic and TP53-mutated = high-risk; ibrutinib, acalabrutinib; intensive chemo + auto-SCT for transplant-eligible; non-SOX11, IGHV-mutated = indolent MCL (watch-and-wait) |
| Marginal zone lymphoma (MZL) — MALT type | Heterogeneous small lymphoid cells in marginal zone distribution; plasma cell differentiation; lymphoepithelial lesions (LELs); reactive follicles | CD20+, CD79a+, BCL2+; CD5−, CD10−, BCL6−, Cyclin D1−; CD21/CD23 highlight expanded marginal zone | t(11;18)(q21;q21) → API2-MALT1 (H. pylori−resistant gastric MALT); t(14;18)(q32;q21) → IGH-MALT1; trisomy 3, 18 | Gastric MALT: H. pylori eradication induces remission in ~75% (t(11;18)-negative cases); non-gastric MALT at various sites; rituximab for H. pylori-negative or refractory |
| Burkitt lymphoma (BL) | Medium-sized cells; round nuclei; multiple nucleoli; abundant basophilic cytoplasm; "starry-sky" macrophages; extremely high mitotic/apoptotic rate | CD20+, CD10+, BCL6+, BCL2 negative (critical — BCL2 positivity argues against BL), Ki-67 ~100%, MYC IHC ≥80% | MYC rearrangement (t(8;14) in ~80%; t(8;22) or t(2;8) variants); no BCL2 rearrangement; IG-MYC translocation required for definitive diagnosis | Oncological emergency; rapid doubling time; CNS prophylaxis mandatory; R-CODOX-M/IVAC or DA-EPOCH-R; TLS prevention critical; highly curable (~80–90% long-term survival) in endemic BL |
| Classical Hodgkin lymphoma (cHL) | Reed-Sternberg cells (large, bilobed or multinucleated) in mixed inflammatory background; subtypes: NS (most common), MC, LR, LD | CD30+++ (membranous/Golgi), CD15+, PAX5 weak/focal, CD20 negative/weak, CD45 (LCA) negative, EBV (LMP1) positive in MC/LD subtypes | JAK-STAT pathway alterations; PDL1 amplification on chromosome 9p24.1; clonal IG rearrangements (usually undetectable by PCR) | ABVD standard; escalated BEACOPP for high-risk; brentuximab vedotin (anti-CD30) + AVD replacing ABVD for advanced-stage; pembrolizumab/nivolumab for relapsed/refractory |
The Hans classifier uses three IHC markers to categorise DLBCL into germinal centre B-cell (GCB) and non-GCB (activated B-cell / ABC) subtypes on FFPE tissue — a surrogate for gene expression profiling (GEP). The algorithm:
Clinical relevance: GCB-DLBCL has better prognosis with R-CHOP. Non-GCB (ABC) DLBCL has inferior R-CHOP outcomes; BTK inhibitors (ibrutinib, zanubrutinib) show preferential activity in ABC-DLBCL due to NF-κB pathway dependence. The ROBUST and PHOENIX trials failed to improve outcomes by adding ibrutinib to R-CHOP for ABC-DLBCL, but next-generation approaches (acalabrutinib + R-CHOP, lenalidomide + R-CHOP) are under investigation.
| Lymphoma | Key Features | IHC | Genetics | Prognosis |
|---|---|---|---|---|
| Peripheral T-cell lymphoma, NOS (PTCL-NOS) | Heterogeneous; large pleomorphic cells; nodal effacement; prominent vascularity; no specific features of other PTCL types — diagnosis of exclusion | CD3+, CD5 often lost, CD4 or CD8; CD30 variable; Ki-67 high | Heterogeneous; TET2, DNMT3A, RHOA mutations common; no unifying alteration; GATA3 vs TBX21 GEP subgroups | Poor — 5-yr OS ~30–35%; CHOP-based regimens; brentuximab vedotin + CHP for CD30+ cases; auto-SCT consolidation in CR1 |
| Angioimmunoblastic T-cell lymphoma (AITL) | Expanded follicular dendritic cell meshworks (CD21); prominent high endothelial venules; mixed inflammatory background; EBV+ B-cell blasts common | CD3+, CD4+, CD10+, BCL6+, CXCL13+, PD-1+++ (follicular helper T-cell phenotype); CD20+ large B-cells (EBV-driven) | TET2+DNMT3A+IDH2 R172 hotspot mutations (~30%) and/or RHOA G17V (~60%); clonal TCR rearrangement | Poor — 5-yr OS ~30%; CHOP-based; romidepsin, mogamulizumab; IDH2 mutations → enasidenib under investigation |
| ALK-positive ALCL | Large pleomorphic cells; hallmark cells (bilobed nuclei, eccentric kidney-shaped nucleus); sinusoidal growth; sheet-like pattern | CD30+++ (strong uniform), ALK+ (cytoplasmic/nuclear in NPM1-ALK; various patterns with other fusions), CD3 negative or weak, EMA+ | ALK rearrangements: NPM1-ALK t(2;5) most common (~80%); other fusion partners; clonal TCR rearrangements | Best PTCL prognosis — 5-yr OS ~70–80%; CHOP-based; brentuximab vedotin (BV) + CHP now preferred 1st-line (ECHELON-2) |
| ALK-negative ALCL | Identical morphology to ALK+ ALCL; same CD30+/ALK− IHC; DUSP22 or TP63 rearrangements by FISH define molecular subsets | CD30+++, ALK−, EMA+; CD3 negative or weak | DUSP22-IRF4 rearrangement (~30%, good prognosis); TP63 rearrangement (~8%, poor prognosis); no ALK rearrangement | Intermediate — 5-yr OS ~45–60%; depends on FISH subgroup; BV + CHP as per ECHELON-2 |
| Adult T-cell leukaemia/lymphoma (ATLL) | Highly pleomorphic cells; "flower cells" (multi-lobated nuclei) on peripheral blood smear; skin involvement common; hypercalcaemia | CD3+, CD4+, CD25+++ (IL-2R), CD7 often lost, FOXP3+; CCR4+++ | HTLV-1 proviral integration; TCR clonal rearrangement; CCR4 mutations → mogamulizumab target | Dismal — acute type median OS 6–13 months; mogamulizumab (anti-CCR4) approved; allo-SCT only curative option; indolent smouldering type managed conservatively |
Multiparameter flow cytometry (typically 8–10 colour panels) of fresh tissue, peripheral blood, bone marrow, or body fluids provides rapid phenotyping (within hours) and complements FFPE histology. Key advantages over IHC: quantitative antigen expression; light chain restriction (kappa/lambda) for B-cell clonality; simultaneous assessment of 10+ antigens; sensitivity to detect small clonal populations (<1%).
| Entity | Characteristic Flow Pattern |
|---|---|
| CLL/SLL | CD5+CD23+CD20(dim)CD79b(dim) B-cells; surface Ig dim; CD38, ZAP-70 as prognostic markers; kappa or lambda restricted |
| Follicular lymphoma | CD10+CD20+BCL2+CD5− B-cells; surface Ig bright; light chain restricted; CD10 expression distinguishes from CLL |
| Mantle cell lymphoma | CD5+CD23−CD20+FMC7+ B-cells; surface Ig bright; CD10−; cyclin D1 (requires intracellular staining); lambda restriction in most |
| Hairy cell leukaemia (HCL) | CD20(bright)+CD22(bright)+CD11c+CD103+CD25+CD123+; BRAF V600E mutation on flow (PCR confirmation); tartrate-resistant acid phosphatase (TRAP) staining |
| Plasma cell myeloma | CD138+CD38+CD45dim/− B-cells; cytoplasmic Ig restricted (light chain); CD19−CD56+ (abnormal); CD28, CD117 as prognostic markers |
| T-lymphoblastic lymphoma/leukaemia | TdT+CD7+CD3 (cytoplasmic)±; CD4/CD8 double positive or double negative in thymic T-ALL; CD1a+ in cortical type |
Co-editor of the WHO Classification of Haematolymphoid Tumours (5th edition, 2022); world authority on mantle cell lymphoma biology, molecular classification of DLBCL, and the integration of genomics into lymphoma diagnosis. One of the most cited haematopathologists globally.
Co-editor of the WHO Classification of Haematolymphoid Tumours (4th and 5th editions). Authority on B-cell lymphomas, plasma cell neoplasms, and blastic plasmacytoid dendritic cell neoplasm (BPDCN). Instrumental in establishing the integrated diagnostic criteria used worldwide.
Pioneer of gene expression profiling in DLBCL — founding contributor to the GCB/ABC classification and its translation from Lymphochip GEP to clinically applicable IHC algorithms. Expert on BCL2 and MYC in double-hit lymphoma prognosis.
Co-developer of the DLBCL GCB/ABC gene expression classifier; contributor to WHO 2022 lymphoma classification. Expert on primary mediastinal large B-cell lymphoma, follicular lymphoma molecular biology, and next-generation sequencing diagnostics in lymphoma pathology.
World authority on Hodgkin lymphoma histology, peripheral T-cell lymphoma classification (AITL, PTCL-NOS, ALCL), and follicular dendritic cell sarcomas. Contributor to all major WHO lymphoma classification editions. Editor of the journal Haematologica.
Co-editor of WHO 2022 haematolymphoid tumours; world authority on T-cell and NK-cell lymphomas, including AITL, PTCL-NOS molecular subgroups (GATA3 vs TBX21), and extranodal NK/T-cell lymphoma. Pioneer in TFH-cell marker IHC and the TFH-origin of nodal T-cell lymphomas.