# Transformation of an indolent lymphoma

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

## TL;DR

A slow-growing lymphoma can change into a fast-growing one. It usually announces itself as one node growing much faster than the others, a sudden rise in lactate dehydrogenase, or new fevers and weight loss in somebody who has been stable for years. It is treated as the aggressive lymphoma it has become, not as the one it came from.

## Summary

WHO-HAEM5 made transformations of indolent B-cell lymphomas a family in its own right in 2022, which they had never been before. The commonest route is follicular lymphoma to diffuse large B-cell lymphoma; chronic lymphocytic leukaemia to diffuse large B-cell lymphoma is called Richter transformation and has its own page; marginal zone and lymphoplasmacytic lymphomas transform less often.

How it shows itself: one site growing out of proportion to the rest, a rapidly rising lactate dehydrogenase, new B symptoms, hypercalcaemia, or a new area of high uptake on a PET scan against a background of low uptake. A biopsy of the most active site, chosen on the PET scan, is what confirms it, and biopsying the wrong node is the commonest way to miss it.

Why it matters. Transformation is the commonest cause of death in follicular lymphoma, and it changes the treatment completely: the disease is treated as an aggressive lymphoma, with combination immunochemotherapy and, in people who have already had chemotherapy for the indolent disease, consideration of CAR-T or transplant. The outcome depends heavily on whether the person has had chemotherapy before.

What is not known. There is no marker that identifies in advance which indolent lymphoma will transform, and no treatment that has been shown to prevent it. Treating an indolent lymphoma earlier does not reduce the risk.

## Fields

- Kind: Term
- Last checked: 2026-09-29
- Also known as: histological transformation; transformed lymphoma; Richter transformation; high-grade transformation
- Tags: heme; lymphoma

## Sources

- WHO Classification of Haematolymphoid Tumours, 5th edition: lymphoid neoplasms (Alaggio, Leukemia 2022): https://doi.org/10.1038/s41375-022-01620-2
- NCI PDQ: adult non-Hodgkin lymphoma treatment (health professional version): https://www.cancer.gov/types/lymphoma/hp/adult-nhl-treatment-pdq

## Connected records

- terms: [Indolent and aggressive lymphoma](https://onco.cc/terms/lymphoma-indolent-versus-aggressive/), [Watch and wait in lymphoma: when the right treatment is none yet](https://onco.cc/terms/lymphoma-tx-watch-and-wait/)
- cancers: [Diffuse large B-cell lymphoma](https://onco.cc/cancers/dlbcl/), [Follicular lymphoma](https://onco.cc/cancers/follicular-lymphoma/), [Gastric MALT lymphoma](https://onco.cc/cancers/gastric-malt-lymphoma/), [Marginal zone lymphoma](https://onco.cc/cancers/marginal-zone-lymphoma/), [Mycosis fungoides](https://onco.cc/cancers/mycosis-fungoides/), [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/)

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