Fourth ventricle rosette-forming glioneuronal tumor. Case report.

The authors describe a rosette-forming glioneuronal tumor of the fourth ventricle in a 29-year-old woman. She had been experiencing dizziness for 1 year and headaches for 1 month. Cranial computed tomography revealed a relatively circumscribed mass involving the inferior cerebellum and floor of the fourth ventricle with extension into the ventricle. Histologically, much of the tumor was piloid with Rosenthal fibers as well as telangiectatic blood vessels; other areas contained complete or incomplete neurocytic rosettes. This tumor type must be differentiated from pilocytic astrocytomas, other gliomas with a piloid glial component, and glioneuronal tumors arising from the floor of the fourth ventricle or inferior cerebellum. Recognition of, and long-term follow up for, this recently described pathological entity may clarify the nature of this lesion and strategies for its optimal management.