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4 slides generated from the cancer page, with a quiz from the open benchmark and speaker notes that cite the sources. Arrow keys move between slides; Print gives one slide per page.
Poorly differentiated chordoma is a rare, aggressive form of chordoma of children and young adults, mostly at the base of the skull or in the neck, defined by loss of the SMARCB1 (INI1) protein. It grows faster and spreads more than ordinary chordoma, and the SMARCB1 loss makes it a candidate for drugs that block EZH2, though surgery and radiotherapy remain the treatment.
The WHO bone classification recognises poorly differentiated chordoma as a subtype defined by brachyury expression with loss of SMARCB1 (INI1), first characterised as a distinct molecular entity with much shorter survival (Acta Neuropathologica 2016). In the 19-patient series, tumours arose in the skull base and clivus (53 percent), cervical spine (32 percent) and sacrum or coccyx (16 percent), were composed of sheets of epithelioid cells rather than the physaliphorous cells of conventional chordoma, and had worse survival than the other subtypes (Modern Pathology 2018).
How it differs from its parent: age (children rather than adults in their fifties and sixties), the SMARCB1 deletion that groups it biologically with atypical teratoid/rhabdoid tumour and epithelioid sarcoma, and a much shorter survival.
| Setting | Approach | Guideline |
|---|---|---|
| All cases | Maximal safe resection and proton radiotherapy as on the chordoma page; EZH2 inhibition under study for SMARCB1-deficient tumours. | not mapped |