This is a slow-growing malignant neoplasm which accounts for less than 5% of primary bone tumours. It is thought to arise from notochordal remnants.
Clinical
This tumour almost exclusively involves the axial skeleton of adults (mean ranges from 47 to 57), most commonly the sacro-coccygeal and spheno-occipital regions5. About 40% occur in the clivus8.
Radiology
At diagnosis, there is usually radiological evidence of bone destruction (sometimes sclerosis) with extraosseous extension5.
Histopathology
There is an abundant fibrillary myxoid stroma within which there are nests, sheets and cords of univacuolated, multivacuolated (physalipherous) and granular cells. Atypia may be minimal but is usually moderate to severe5. Some variants appear chondroid or epithelioid7.
Immunohistochemistry
31/317 |
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most of 351 |
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1/162, 6/66 |
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16/162 |
|||
6/66 |
|||
0/66 |
|||
0/66 |
|||
0/66 |
|||
9/162 |
|||
16/162, 5/66 |
|||
0/162, 0/73, 0/76 |
|||
4/162 |
|||
usually positive, 10/317 |
|||
0/317 |
|||
0/317 |
|||
positive |
|||
positive |
|||
positive1 |
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positive1 |
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occasionally positive1 |
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negative1 |
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Dedifferentiated foci may loose positivity for S-100, HBME-1 and cytokeratins7.
Differential diagnosis
Giant vertebral notochordal rest (ecchordosis physaliphora vertebralis)5,9. This is a controversial entity. The diagnosis is favoured by a lesion in the mobile spine, where chordoma is rare, young age and lack of radiological bone destruction or progression. Bone trabeculae are preserved, with sheets of clear cells filling the intertrabecular spaces: these cells are positive for cytokeratin (AE1/AE3, Cam5.2), EMA and S-100. Histologically, there should be a lack of lobularity, mucin pools with syncytial cell cords, necrosis, nuclear atypia or mitotic activity.
parachordoma is the equivalent tumour when found in soft tissues.
Chondrosarcoma. E-cadherin, catenins and NCAM may help to distinguish chordoma from chondrosarcoma4:
|
chordoma |
chondrosarcoma |
E-cadherin |
11/16 |
0/8 |
a-catenin |
7/16 |
1/8 |
b-catenin |
13/16 |
1/8 |
g-catenin |
10/16 |
0/8 |
14/16 |
2/8 |
Metastatic carcinoma, particularly renal cell carcinoma. Renal cell carcinoma is usually positive for CD10 and RCCMa.
Dedifferentiated chordoma: spindle cell sarcoma or dedifferentiated chondrosarcoma.
Management
Radical surgical excision followed by proton beam irradiation8.
Prognosis
Chordomas are locally invasive but rarely metastasis. A switch from E-cadherin to N-cadherin expression is associated with recurrence and tumour-associated death8.
References
6 Chu, P. G. and L. M. Weiss (2002). "Keratin expression in human tissues and neoplasms." Histopathology 40(5): 403-39. (Summary data from multiple papers)
This page last revised 18.1.2006.
©SMUHT/PW Bishop