Background Flashcards
What are chordomas?
Chordomas are rare, slow-growing, locally aggressive neoplasms of bone arising from embryonic remnants of the notochord.
What are the most common histologic subtypes seen for chordomas?
Most common histologic subtypes of chordoma:
- Conventional: most common, no cartilaginous or mesenchymal components
- Chondroid: 5%–15%, contains cartilaginous components but is distinct from chondrosarcoma
- Dedifferentiated or sarcomatous transformation: 2%–8%, aneuploid tumors interspersed in areas of conventional chordomas, worse survival
What features characterize conventional chordomas?
Macroscopically tumors are expansile, lobulated structures with a blue/slate-gray, gelatinous matrix that may exhibit solid areas. Microscopically, characteristic highly vacuolated “physaliphorous cells” are present.
What histologic types of chordomas are most commonly found in the skull base?
Conventional is still the most common, although the chondroid type has a predilection for the cranial region (1/3rd of cranial chordomas are chondroid).
What are the immunohistochemical findings that can help distinguish chordomas from other histologically similar lesions?
S-100 immunoreactivity distinguishes chordoma from metastatic adenocarcinoma and meningioma, and epithelial membrane antigen (EMA) immunoreactivity distinguishes it from chondroma, chondrosarcoma, and melanoma.
Brachyurystaining can distinguish chordomas from other chondroid lesions with similar morphologic or immunophenotypic features. Brachyury is a transcription factor associated with notochord differentiation.
Where do chordomas most commonly arise?
Chordomas most commonly arise in 3 locations in the axial skeleton: sacrum, skull base and mobile spine. Historically sacrum thought to be most common site; however, more recent evidence from SEER database suggests equal distribution b/t the 3 sites.
What is the DDx of a tumor involving sacral bone?
Metastatic lesions and multiple myeloma make up the overwhelming majority of sacral and spinal neoplasms. Chordomas are the most frequently occurring primary malignant bone tumor in both the sacrum and the mobile spine. Other primary sacral tumors include chondrosarcoma, EWS, osteosarcoma, PNET, Paget sarcoma, and benign tumors including giant cell tumor and hemangioma.
What is the rate of DM for chordoma, and what distant sites can be involved?
DM have been found in up to 5% of pts at the time of Dz and up to 30%–40% of pts can develop mets later. Sites of mets most commonly include lungs. Other sites: Soft tissues, bone, skin and brain.
