# Dedifferentiated chordoma

Source: https://onco.cc/cancers/dedifferentiated-chordoma/  
OnCo record `dedifferentiated-chordoma` (Cancer). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

Dedifferentiated chordoma is a rare form of chordoma in which part of the tumour has turned into a high-grade sarcoma, usually after recurrence or radiotherapy but sometimes from the start. The sarcoma component decides the outcome, which is much worse than ordinary chordoma, so it is treated with surgery and the chemotherapy used for high-grade sarcomas, not surgery and radiotherapy alone.

## Summary

The WHO bone classification lists dedifferentiated chordoma as a chordoma subtype defined by a high-grade sarcoma juxtaposed to conventional chordoma (Am J Surg Pathol 2020). In the ten-case series the tumours measured 2.8 to 24.5 cm (median 5.8), arose de novo or at recurrence including after radiotherapy in the sacrum (5), skull base (2), lumbar spine, mediastinum and as a lung metastasis, the dedifferentiated component made up 3 to 95 percent (median 60) and was pleomorphic to fibrosarcomatous, and by immunohistochemistry the conventional or chondroid component kept cytokeratin and brachyury while the dedifferentiated component lost both (Am J Surg Pathol 2020). The dedifferentiated component dictates survival, smaller areas carrying a better prognosis; it is more often diagnosed in recurrences and after radiotherapy but arises de novo in a few (JBJS British 2008).

How it differs from its parent: loss of brachyury in the sarcomatous part, rapid growth and early metastasis against the slow course of conventional chordoma, and a treatment plan that borrows from high-grade soft tissue sarcoma.

How common: about 1 percent of chordomas (Am J Surg Pathol 2020).

Treatment: en bloc resection where possible, radiotherapy (proton or carbon ion as on the parent page) and anthracycline-based chemotherapy for the sarcomatous component, borrowed from the sarcoma page; no trial exists in the subtype.

## Fields

- Kind: Cancer
- Last checked: 2026-09-24
- Also known as: Chordoma with sarcomatous transformation; Dedifferentiated chordoma (high-grade sarcoma in a chordoma)
- Tags: subtype-page; wave4; rare
- Group: sarcoma
- Burden: Under 1 percent of chordomas: 10 cases among more than 1,000 chordomas surveyed at one centre, seven men and three women aged 15 to 80 (median 54) (Am J Surg Pathol 2020).
- Subtypes: Dedifferentiated chordoma arising in recurrent or irradiated conventional chordoma; Dedifferentiated chordoma arising de novo; Dedifferentiated chordoma with chondroid conventional component; Conventional and chondroid chordoma (the parent page)
- Biomarkers: Brachyury (TBXT) and cytokeratin lost in the dedifferentiated component; Proportion of dedifferentiated component (prognostic); High-grade sarcoma morphology (pleomorphic, fibrosarcomatous, rarely osteosarcoma or rhabdomyosarcoma)

## Sections of this record

The page is a hub with ten sections in reading order; large sections have their own page. The same plan as JSON: https://onco.cc/api/v1/cancers/dedifferentiated-chordoma/sections.json

- Overview (on the hub): The TL;DR, the family this cancer belongs to, the organ, who gets it and what the state of the art is. https://onco.cc/cancers/dedifferentiated-chordoma/#overview
- What it is (on the hub): Anatomy, the subtypes and how they differ, how it is staged, and where advanced disease spreads. https://onco.cc/cancers/dedifferentiated-chordoma/#what-it-is [4 subtypes]
- Finding it (on the hub): How it shows itself, how it is confirmed, what screening exists, and the biomarkers clinicians test for. https://onco.cc/cancers/dedifferentiated-chordoma/#finding-it [3 biomarkers]
- Treating it (on the hub): The standard of care by setting, the medicines, surgery and radiotherapy named in it, and the regimens behind them. https://onco.cc/cancers/dedifferentiated-chordoma/#treating-it [1 setting, 1 decision with options]
- Evidence (on the hub): Trials recruiting now, the landmark trials, the key papers and what they mean, the latest literature, and the milestones year by year. https://onco.cc/cancers/dedifferentiated-chordoma/#evidence
- The science (on the hub): The molecular landscape: the targets and how often each appears, the pathways, the mechanics stages and the preclinical models. https://onco.cc/cancers/dedifferentiated-chordoma/#science [1 target]
- Where you are (own page): Cases by country, the UK and NHS pathway and other country lenses, and the expert centres with trials on record. https://onco.cc/cancers/dedifferentiated-chordoma/where-you-are/
- Living with it (on the hub): The decisions you may face, the aids that walk through them, the warnings on record, the first sixty days and the questions to ask. https://onco.cc/cancers/dedifferentiated-chordoma/#living-with-it [8 questions, 4 red cards]
- What is coming (own page): Everything in development, the open problems and what is being done about them, the roadmaps, and what changed on this record. https://onco.cc/cancers/dedifferentiated-chordoma/coming/ [1 medicine]
- Data (own page): Every connected record, the notes, the JSON, Markdown and RDF twins, and where the record came from and when it was checked. https://onco.cc/cancers/dedifferentiated-chordoma/data/ [5 connected records]

## Standard of care

- All cases: En bloc resection, radiotherapy as on the chordoma page, and anthracycline-based chemotherapy for the sarcomatous component; no trial in the subtype. ([Chordoma](https://onco.cc/cancers/chordoma/), [Sarcomas (soft tissue, bone, GIST)](https://onco.cc/cancers/sarcoma/), [Proton therapy](https://onco.cc/technologies/proton-therapy/), [Doxorubicin](https://onco.cc/drugs/doxorubicin/))

## Sources

- Wikipedia: https://en.wikipedia.org/wiki/Chordoma
- Am J Surg Pathol 2020: dedifferentiated chordoma, clinicopathologic and molecular characteristics: https://doi.org/10.1097/pas.0000000000001501
- JBJS British 2008: dedifferentiated chordoma, four cases arising de novo: https://doi.org/10.1302/0301-620x.90b5.20365

## Connected records

- cancers: [Chordoma](https://onco.cc/cancers/chordoma/), [Poorly differentiated chordoma (SMARCB1-deficient)](https://onco.cc/cancers/poorly-differentiated-chordoma/), [Sarcomas (soft tissue, bone, GIST)](https://onco.cc/cancers/sarcoma/), [Undifferentiated pleomorphic sarcoma (UPS)](https://onco.cc/cancers/undifferentiated-pleomorphic-sarcoma/)
- technologies: [Proton therapy](https://onco.cc/technologies/proton-therapy/)
- targets: [TBXT](https://onco.cc/targets/tbxt/)
- drugs: [Doxorubicin](https://onco.cc/drugs/doxorubicin/)

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JSON: https://onco.cc/api/v1/entities/dedifferentiated-chordoma.json