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Neuroradiology Case of the Week

Case 122

Loris F. Cedeno, MD and Per-Lennart Westesson, MD, PhD, DDS

Clinical Presentation: A three-year-old female presented with a history of anorexia and lethargy.

Radiological Findings: CT of the cervical spine demonstrated an ill defined, isodense soft tissue mass with areas of calcification, associated with areas of lytic destruction of the basiocciput portion of the clivus, right aspect of C1, as well as the odontoid process (Figs. 1&2)
      MR images of the spine show this mass arising from the posterior aspect of the clivus, involving the right occipital condyle, the anterior arch of C1 and the odontoid process.  This mass is isointense to brain parenchyma in both T1 and T2 weighted sequences and demonstrates mild to moderate enhancement after contrast administration.  It is also causing marked mass effect with kinking of the adjacent cord as well as hyperintense T2 signal within it (Figs. 3-6).

Discussion: Chordomas are relatively uncommon bone tumors accounting for 2%-4% of all primary malignant bone neoplasms. Fewer than 10% of cases are classified as dedifferentiated chordomas. This tumor is a rare subtype of chordoma which has a poor prognosis and are clinically more aggressive than other chordomas. They also have a higher incidence of early distant metastasis. These tumors contain areas of sarcomatous elements as well as areas of conventional or chondroid chordomas. The sarcomatous elements have been reported to resemble malignant fibrous histiocytoma, fibrosarcoma, osteosarcoma, and high grade chondrosarcoma. Most studies appear to suggest that they arise from sarcomatous transformation of chordoma, with some reporting their occurrence following postoperative radiotherapy for conventional chordoma.
     Pathologically, physaliphorous cells are present in all types of chordoma. These are positive for S-100 protein, CK, and EMA. CEA also is positive in most cases. In the dedifferentiated variety, the physaliphorous cells were more pleomorphic with nuclear inclusions, binucleation or multinucleation, and mitotic figures. The differential diagnosis of chordoma cytologic preparations, includes chondrosarcoma (particularly myxoid chondrosarcoma), metastatic carcinoma, myxoid liposarcoma, myxoid malignant fibrous histiocytoma (MFH), and myxopapillary ependymoma.

References:

1. Meis JM, Raymond AK, Evans HL, Charles RE, Giraldo AA: "Dedifferentiated" chordoma. A clinicopathologic and immunohistochemical study of three cases. Am J Surg Pathol. July 1987; 11(7): 516-25. [Medline]
2. Erdem E, Angtuaco EC, Van Hemert R, Park JS, Al-Mefty O: Comprehensive review of intracranial chordoma. Radiographics, 2003 Jul-Aug;23(4):995-1009. [Medline]
3. Meyers SP, Hirsch WL Jr, Curtin HD, Barnes L, Sekhar LN, Sen C: Chordomas of the skull base: MR features. AJNR Am. J. Neuroradiol. 1992 Nov-Dec;13(6):162 -1636. [Medline]
4. Crapanzano JP, Ali SZ, Ginsberg MS: Chordoma: a cytologic study with histologic and radiologic correlation. Cancer. 2001 Feb 25;93(1):40-51. [Medline]
5. Rao N, Ra R, Panikkar V, Shidman V: Chordoma. Emedicine