Intracranial primary synovial sarcoma: radiologic-pathologic correlation

We present a very rare case of spontaneous intracranial synovial sarcoma. A 15-year-old female was admitted to our institution for a cervical spine MRI, reporting a gradual pain of the dorsal neck after an injury three months previously. After obtaining the first sequence we discovered a large skull base mass. We immediately performed a skull base MRI. MR arteriography, MR venography, CT and DSA were also performed. A large space-occupying lesion was demonstrated, extending from the right petrous bone to the occipital bone at the level of the foramen magnum and the right atlantooccipital junction. CT revealed calcifications. The MR venography demonstrated diminished flow in the right transverse and sigmoid sinus, as well in the right internal jugular vein. Otorhinolaryngological evaluation revealed a slight ipsilateral conductive hearing loss. The whole mass was macroscopically removed via a retrosigmoid, transmastoid, infratemporal approach. Postoperative course was uneventful, except for complete palsy of the ipsilateral hypoglossal nerve. The final pathological examination including immunohistochemical picture, showed findings consistent with synovial sarcoma (monophasic spindle-cell type).