OBJECTIVE: The presence of cartilage and bone in a glial tumor is most unusual. Several mechanisms have been proposed to explain this condition. In some cases, there is a fibrous capsule between tumor tissue and the cartilaginous area together with glial fibrillary acidic protein negativity in cartilage cells; in others, there is no fibrous capsule between cartilage cells and tumor tissue, and the cartilage cells are glial fibrillary acidic protein positive.

CASE REPORT: A 56-year old female with an ependymoma containing a cartilaginous area is reported. The patient had been irradiated 8 years ago. The mechanisms of the occurrence of cartilage in gliomas are reviewed, and the probable effects of irradiation on this condition are discussed.

RESULTS: In our case, there was no fibrous capsule between the ependymoma and the cartilaginous tissue, and the cartilage cells were glial fibrillary acidic protein immunopositive.

CONCLUSION: In this case, it was considered that the cartilage formation resulted from the transformation of neuroepithelial cells to mesenchymal tissue because of the positive response of cartilage cells to glial fibrillary acidic protein and the lack of a fibrous capsule around the cartilaginous area.