Chondrosarcoma of the base of skull

Case contributed by A.Prof Frank Gaillard


Giddiness; neck pain; spasm; painful neck movement

Patient Data

Age: 45-55
Gender: Male

Enhancing soft tissue mass lesion in right occipital condyle region.

Lytic destruction of right occipital condyle.

Case Discussion

Chondrosarcoma of the base of skull involving the right occipital condyle.


The section contains skeletal muscle fibres, which are infiltrated by a malignant spindle cell tumour.  The tumour forms diffuse sheets and vague short fascicles.  These tumour cells show moderately pleomorphic and angulated nuclei with hyperchromasia, granular chromatin, inconspicuous nucleoli and ill-defined scanty cytoplasm. Scattered mitoses are seen.  There are also amorphous strands of focally calcified, eosinophilic material in the stroma. No staghorn blood vessels are seen. The spindled tumour cells are CD99 positive. They are EMA, AE1/3, CD34, S-100 and SMA negative.

Final diagnosis

Submucosal nasopharyngeal biopsies: High grade chondrosarcoma.


There is chondroid matrix, containing atypical chondrocytes, in keeping with a chondrosarcoma. The cytokeratin stain is negative, excluding a carcinoma. The presence of CD99 positive spindle cells suggests mesenchymal chondrosarcoma. However, the amount of these spindled cells is small and not all the classic features of mesenchymal chondrosarcoma are seen on histology.  Alternatively, the spindle cell areas may represent dedifferentiation.

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Case information

rID: 8969
Published: 12th Mar 2010
Last edited: 24th Nov 2015
Inclusion in quiz mode: Included

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