An unusual intracranial metastasis of osteosarcoma.

Intracranial metastasis is unusual in osteosarcoma. A case of osteosarcoma was presented with a large intracranial "stone" which was a subdural convexity metastasis. Smaller epidural metastases over other areas were noted also in brain CT scan. Using the radiographs and bone scans, many other lesions at bones, the mediastinum, pleura, perirenal space, and adrenal gland were detected simultaneously. This condition might result from either early metastases or multifocal osteosarcomas. Because many of the above lesion sites were not frequent locations of primary osteosarcoma and had been reported as metastatic targets of osteosarcoma. So the explanation of a very malignant osteosarcoma with early metastases may be more appropriate for this case. The baseball-like tumor in the subdural space with marked compression of the brain surface was grossly totally excised. Histopathologic examination confirmed the diagnosis of osteosarcoma. Postoperatively, the man's condition improved dramatically, though only for two months. He died 5 months later. Reports of such metastatic osteosarcomas are reviewed.