# Transformation: when a slow lymphoma turns into a fast one

Source: https://onco.cc/terms/lymphoma-bio-transformation/  
OnCo record `lymphoma-bio-transformation` (Term). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

An indolent lymphoma can change into an aggressive one, usually by acquiring new genetic faults in the same clone. It is the commonest reason a person who has been well for years becomes unwell quickly, and it is treated as the aggressive disease rather than the original one.

## Summary

Transformation is a change in the behaviour of a clone, not the arrival of a second cancer. A follicular lymphoma that has been watched for years can acquire MYC rearrangement, TP53 loss or CDKN2A deletion and start behaving as a diffuse large B-cell lymphoma. Chronic lymphocytic leukaemia can do the same, and that version has its own name, Richter transformation.

The genetics of Richter transformation were read across 86 pathologically proven cases: TP53 disruption in 47.1% and MYC abnormality in 26.2% were the dominant lesions, while the usual drivers of de novo diffuse large B-cell lymphoma were rare or absent. Whether the large-cell clone is related to the leukaemic clone matters more than any drug does: clonally unrelated cases had median survival of 62.5 months against 14.2 months for related ones, and less TP53 disruption, 23.1% against 60.0% (Rossi 2011).

What prompts the suspicion: a single node or site growing much faster than the rest, new B symptoms, a rising LDH, or a PET scan with one area far brighter than the others. What settles it is a biopsy of the brightest area, because the question is answered by tissue and nothing else answers it.

What changes: treatment moves to an aggressive-lymphoma regimen, the clonal relationship is worth establishing because it changes the expected course, and a trial is often the right answer in Richter transformation, where outcomes with standard chemoimmunotherapy are poor.

## Fields

- Kind: Term
- Last checked: 2026-09-30
- Also known as: Histological transformation; Transformed follicular lymphoma; Richter transformation; Richter syndrome

## Sources

- Rossi et al., Blood 2011: the genetics of Richter syndrome in 86 pathologically proven cases: https://doi.org/10.1182/blood-2010-09-302174
- Horn et al., Blood 2013: MYC, BCL2 and BCL6 rearrangement and expression in 442 RICOVER patients: https://doi.org/10.1182/blood-2012-06-435842

## Connected records

- cancers: [Follicular lymphoma](https://onco.cc/cancers/follicular-lymphoma/), [Marginal zone lymphoma](https://onco.cc/cancers/marginal-zone-lymphoma/), [Non-Hodgkin lymphoma (all types)](https://onco.cc/cancers/non-hodgkin-lymphoma/), [Richter transformation of chronic lymphocytic leukaemia](https://onco.cc/cancers/richter-transformation-cll/), [Waldenström macroglobulinaemia](https://onco.cc/cancers/waldenstrom/)
- technologies: [Cytogenetics and FISH](https://onco.cc/technologies/cytogenetics-fish/), [FDG PET](https://onco.cc/technologies/fdg-pet/)
- targets: [CDKN2A](https://onco.cc/targets/cdkn2a/), [MYC](https://onco.cc/targets/myc-gene/), [TP53](https://onco.cc/targets/tp53/)
- pathways: [Clonal evolution & minimal residual disease](https://onco.cc/pathways/clonal-evolution/), [The p53 network (guardian of the genome)](https://onco.cc/pathways/p53-mdm2-axis/)
- terms: [Deauville score and PET-adapted therapy](https://onco.cc/terms/deauville/), [FLIPI, FLIPI2 and POD24 (follicular lymphoma risk)](https://onco.cc/terms/flipi/), [POD24: progression of follicular lymphoma within two years, and why it changes the plan](https://onco.cc/terms/lymphoma-tx-pod24/)

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