Osteosarcoma of the meninges in association with glioblastoma.

Primary intracranial osteosarcoma not originating in the skull is a distinctly rare tumour, as is post-irradiation sarcoma of short latency. The authors report the case of a 56 year old caucasian male who underwent resection of a glioblastoma of the left temporal region and was subsequently administered partial field external beam radiation therapy (XRT) to a total dose of 5940 cGy. Seven months following the completion of XRT, an enhancing region adjacent to the surgical site was noted on followup magnetic resonance images (MRI), one which increased in size on serial studies. Initial biopsy of the dural lesion adjacent to the temporal resection site revealed a sarcoma with a suggestion of osseous differentiation. Subsequent reoperation with resection of the lesion showed it to be a primary meningeal tumour, and histological evaluation of the lesion demonstrated an osteosarcoma. Immunohistochemical staining for p53 protein performed on both the original glioblastoma and the subsequently resected osteosarcoma showed widespread nuclear positivity. The clinical, radiographic and pathologic features of this unusual case are discussed. Meningeal osteosarcoma should be included among the rare secondary sarcomas of the meninges which may be associated with malignant glioma.