{"entity":{"id":"dedifferentiated-chordoma","kind":"cancer","name":"Dedifferentiated chordoma","aka":["Chordoma with sarcomatous transformation","Dedifferentiated chordoma (high-grade sarcoma in a chordoma)"],"tldr":"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).\n\nHow 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.\n\nHow common: about 1 percent of chordomas (Am J Surg Pathol 2020).\n\nTreatment: 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.","asOf":"2026-09-24","wikipedia":"https://en.wikipedia.org/wiki/Chordoma","links":[{"label":"Am J Surg Pathol 2020: dedifferentiated chordoma, clinicopathologic and molecular characteristics","url":"https://doi.org/10.1097/pas.0000000000001501"},{"label":"JBJS British 2008: dedifferentiated chordoma, four cases arising de novo","url":"https://doi.org/10.1302/0301-620x.90b5.20365"}],"tags":["subtype-page","wave4","rare"],"related":["chordoma","poorly-differentiated-chordoma","sarcoma","undifferentiated-pleomorphic-sarcoma"],"cancers":[],"sections":[],"technologies":["proton-therapy"],"targets":["tbxt"],"drugs":["doxorubicin"],"companies":[],"institutions":[],"pathways":[],"terms":[],"trials":[],"people":[],"bottlenecks":[],"keyPapers":[],"journals":[],"dependsOn":[],"notes":[],"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)"],"standardOfCare":[{"setting":"All cases","approach":"En bloc resection, radiotherapy as on the chordoma page, and anthracycline-based chemotherapy for the sarcomatous component; no trial in the subtype.","refs":["chordoma","sarcoma","proton-therapy","doxorubicin"]}],"stateOfArt":[],"history":[],"pipeline":[],"openProblems":[],"parent":"chordoma"},"route":"/cancers/dedifferentiated-chordoma/","neighbours":{"cancer":[{"id":"chordoma","kind":"cancer","name":"Chordoma","route":"/cancers/chordoma/"},{"id":"poorly-differentiated-chordoma","kind":"cancer","name":"Poorly differentiated chordoma (SMARCB1-deficient)","route":"/cancers/poorly-differentiated-chordoma/"},{"id":"sarcoma","kind":"cancer","name":"Sarcomas (soft tissue, bone, GIST)","route":"/cancers/sarcoma/"},{"id":"undifferentiated-pleomorphic-sarcoma","kind":"cancer","name":"Undifferentiated pleomorphic sarcoma (UPS)","route":"/cancers/undifferentiated-pleomorphic-sarcoma/"}],"technology":[{"id":"proton-therapy","kind":"technology","name":"Proton therapy","route":"/technologies/proton-therapy/"}],"target":[{"id":"tbxt","kind":"target","name":"TBXT","route":"/targets/tbxt/"}],"drug":[{"id":"doxorubicin","kind":"drug","name":"Doxorubicin","route":"/drugs/doxorubicin/"}]}}