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Classification of lymphoid neoplasms — morphology, immunophenotype and genetics
Lymphoma is classified by lineage (B, T or NK), by stage of maturation and by the combination of morphology, markers (immunohistochemistry and flow cytometry) and a characteristic genetic change — so diagnosis requires an excisional or adequate core biopsy, not cytology alone.
Why it matters in the exam
The bank asks about the Reed-Sternberg cell, translocations and markers. In classic Hodgkin lymphoma the Reed-Sternberg cells are B cells that have lost most of the B-cell programme: CD15 and CD30 positive, CD45 negative, PAX5 weak and CD20 usually negative; the background contains many inflammatory cells, and the common subtype is nodular sclerosis. EBV is common in the mixed cellularity subtype. In the nodular lymphocyte-predominant form, the tumour (LP) cells are CD20 positive and CD15 and CD30 negative.
In non-Hodgkin lymphomas: follicular lymphoma — t(14;18) with BCL2 overexpression in follicles, CD10 and BCL6 positive; mantle cell lymphoma — t(11;14) with cyclin D1, CD5 positive and SOX11; chronic lymphocytic leukaemia / small lymphocytic lymphoma — CD5 and CD23 positive; Burkitt — t(8;14) with MYC, Ki-67 close to 100% and a "starry sky" appearance; DLBCL — the most common lymphoma, classified by cell of origin (germinal centre or activated B), and with combined MYC and BCL2 rearrangements it is high grade. Gastric MALT lymphoma is linked to Helicobacter pylori and sometimes regresses after antibiotic treatment, except when t(11;18) is present.
Hairy cell leukaemia is characterised by the BRAF V600E mutation — a mutation also found in melanoma, papillary thyroid carcinoma and Langerhans cell histiocytosis. HLH is a syndrome of overactivation of macrophages and T cells, with fever, splenomegaly, cytopenias, very high ferritin and phagocytosis of blood cells in the marrow; it can be inherited or secondary to infection (EBV), lymphoma or autoimmune disease. In the work-up, flow cytometry shows clonality (restriction to one light chain — κ or λ) in B-cell tumours.
Key points
- Classification by lineage, maturation, morphology, markers and genetics.
- Classic Hodgkin: CD15 and CD30 positive, CD45 negative.
- Follicular t(14;18); mantle t(11;14); Burkitt t(8;14).
- DLBCL is the most common; gastric MALT is linked to H. pylori.
- Hairy cell: BRAF V600E.
Summary table
| Tumour | Genetic change | Markers | Feature |
|---|---|---|---|
| Classic Hodgkin | — | CD15, CD30 positive; CD45 negative | Reed-Sternberg cells in inflammatory background |
| Follicular lymphoma | t(14;18) — BCL2 | CD10, BCL6, BCL2 | Crowded follicles |
| Mantle cell lymphoma | t(11;14) — cyclin D1 | CD5, SOX11 | Relatively aggressive |
| Burkitt | t(8;14) — MYC | CD10, Ki-67 close to 100% | Starry sky |
| Hairy cell leukaemia | BRAF V600E | CD103, CD25, annexin A1 | Pancytopenia and splenomegaly |
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Sources
- WHO Classification of Tumours: Haematolymphoid Tumours, 5th edition (2022–2024) — Mature B-cell neoplasms; Hodgkin lymphoma
- International Consensus Classification of Mature Lymphoid Neoplasms (Campo E et al., Blood), 2022 — Diagnostic criteria
- Jaffe ES et al. Hematopathology, 3rd edition (2024) — Immunophenotyping and genetics of lymphomas
Sources are given for further reading; the text is written afresh and not copied from them.
Reviewed by the Examqo AI Professor · 2026-11-06. The text may contain errors; when in doubt, check the source.