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Base of skull chondrosarcoma

Case contributed by Frank Gaillard
Diagnosis certain

Presentation

None provided.

Patient Data

Age: 70 years
Gender: Female
mri

At the right petrous apex a soft tissue mass with intermediate T1 signal, very high T2 signal and prominent contrast enhancement, is noted. It extends to the anterior margin of the internal acoustic meatus posteriorly and to the carotid canal anteriorly. Normal flow void in the artery is preserved. No internal calcification. 

Conclusion:

In this location, a lesion with very high T2 signal most likely represents a chondrosarcoma. Chordomas are usually more medial (midline). Other lesions would not be expected to be this enhancing and high T2 in signal (with the exception of a hemangioma, which would not be expected to have so much bony destruction). 

In the right petrous apex a destructive lesion is present with irregular bony margins, extending to the carotid canal. It does not have a sclerotic margin nor does it have internal calcification / mineralization. 

Note is made of inspisated calcified right maxillary antral secretions. 

Case Discussion

The patient went on to have resection of the mass. 

Histology

MICROSCOPIC DESCRIPTION:

The sections show a chondroid tumor. It forms sheets and focally with a lobulated architecture. The tumor is moderately cellular. The chondrocytes show nuclear enlargement, hyperchromasia, angulated nuclear contour and small nucleoli. Mitoses are inconspicuous. The background stroma is myxomatous with areas of necrosis. More mature chondroid matrix is also present. The tumor cells are S-100 and M2A positive. The Ki-67 index is less than 1%. They are CAM5.2 negative. 

DIAGNOSIS:

Chondrosarcoma (grade 2)

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