An extra-axial lesion arising from just lateral to the clivus and cavernous sinus is noted. It is of mixed density with regions of calcifications.
The location and appearance are suggestive of a chondrosarcoma. The off-midline location and ring-like calcification make a chordoma much less likely. A meningioma or trigeminal schwannoma are less likely possibilities.
Selected MRI images confirm the presence of an extra-axial lesion arising from just lateral to the clivus and cavernous sinus. It is heterogeneous in signal with the more medial component demonstrated high T2 signal and variegated contrast enhancement, without restricted diffusion.
Features are consistent with a chondrosarcoma (histologically proven). The off-midline location and ring-like calcification make a chordoma much less likely.
Case Discussion
The patient went on to have a resection.
HIstology:
Sections show a moderately cellular cartilage-forming neoplasm with large areas of tumor necrosis. The tumor cells are round to polygonal with hyperchromatic nuclei and are embedded in a hyaline chondromatous matrix. There are foci, however, in which the tumor cells are stellate to spindle in shape, have slightly vacuolated cytoplasm and are embedded in a myxoid stroma. The tumor cells are diffusely and strongly positive for S-100 protein and negative for EMA and cytokeratin.
Final Diagnosis: chondrosarcoma (grade 2 of 3).
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