Skull base chondrosarcoma

Discussion:

Pathology report on repeat surgery.

The sections show a moderately cellular tumor with a lobulated architecture. There are aggregates of epithelioid cells in blue-tinged chondroid-like stroma. The tumor cells have mildly enlarged and hyperchromatic nuclei, angulated nuclear contour, small nucleoli and small to moderate amounts of clear vacuolated to eosinophilic cytoplasm. No mitoses or necrosis is seen. Sections of the bone show tumor infiltrating into the medullary spaces. The tumor cells are S-100 positive. There is focal staining for M2A. EMA staining is equivocal. CAM5.2, AE1/3, CK19 and CEA are negative.

Comment: The previous biopsy has been reviewed. It showed similar morphology as compared to the current tumor with cellular nodules of cartilage, containing atypical chondrocytes. CAM5.2 was also negative. The overall features are those of grade 2 chondrosarcoma. Cytokeratin negativity excludes the diagnosis of chordoma.

The radiology has also been reviewed and chondrosarcoma is favored over chordoma.

Final diagnosis: Skull base tumor: Recurrent grade II chondrosarcoma.

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