[A case of chondrosarcoma in the cavernous sinus].

A 24-year-old female patient complained of headache and right abducens nerve paralysis. No abnormality was found in plain CT scan, but a ring-like enhanced mass was disclosed behind the right posterior clinoid process in enhanced CT scan. MRI revealed a low intensity mass in T1-weighted image and a ring-like enhanced mass in gadolinium-DTPA enhanced image. It was a circumferential high intensity mass in T2-weighted image and an isointensity mass in proton image. Cerebral angiography indicated that it was avascular. Preoperative diagnosis was trigeminal neurinoma or petroclival meningioma. The tumor was removed almost completely by orbitozygomatic infratemporal approach. Histologically, it was low grade chondrosarcoma. Postoperatively, neither radiation therapy nor chemotherapy was added. Differential diagnosis and treatment was discussed. It was suggested that MRI was the most useful diagnostic tool to distinguish chondrosarcoma from other skull base tumors.