Mixed neuronal-glial tumor of the fourth ventricle and successful treatment of postoperative mutism with bromocriptine: case report.
BACKGROUND
Tumors composed of both neurocytic and astrocytic cells are uncommon and poorly understood. We describe the clinicopathologic features of a very rare rosette-forming glioneuronal tumor of the fourth ventricle and propose bromocriptine as a useful therapeutic agent for cerebellar mutism after posterior fossa surgery.


METHODS
A fourth ventricle tumor was incidentally discovered in an 18-year-old woman. Magnetic resonance imaging revealed ventriculomegaly and a solid tumor with low-intensity signals on T1-weighted images and high-intensity signals on T2-weighted images. There was slight gadolinium enhancement. The tumor was subtotally resected. Although its lower half was well circumscribed, its upper half manifested invasive growth. Histologically, 2 components were identified, synaptophysin-positive neurocytic cells forming perivascular pseudorosettes and glial fibrillary acidic protein-positive astrocytic cells with Rosenthal fibers. Overall, cellular atypia was minimal and the MIB-1 labeling index was low. On the basis of these histologic findings, the tumor bore striking similarity to the recently described rosette-forming glioneuronal tumors of the fourth ventricle. Postoperatively, the patient manifested cerebellar mutism. The administration of bromocriptine improved her neurological status dramatically.


CONCLUSIONS
The natural history of rosette-forming glioneuronal tumors of the fourth ventricle is not yet fully understood. Therefore, careful and long-term follow-up monitoring of the tumor hosts is necessary. Bromocriptine therapy may promote recovery from mutism after posterior fossa surgery.
Adachi
Jun-ichi
J
Department of Neurosurgery, Saitama Medical School, Saitama 350-0495, Japan. jadachi@saitama-med.ac.jp
Nishikawa
Ryo
R
Hirose
Takanori
T
Matsutani
Masao
M
D000293:Adolescent; D001254:Astrocytoma / Q000473:pathology / Q000601:surgery*; D001932:Brain Neoplasms / Q000473:pathology / Q000601:surgery*; D001971:Bromocriptine / Q000627:therapeutic use*; D002552:Cerebral Ventricles / Q000473:pathology*; D018491:Dopamine Agonists / Q000627:therapeutic use*; D005260:Female; D006801:Humans; D009155:Mutism / Q000188:drug therapy* / Q000209:etiology*; D018306:Neurocytoma / Q000473:pathology / Q000601:surgery*; D011183:Postoperative Complications / Q000188:drug therapy*; D016896:Treatment Outcome
D018491:Dopamine Agonists; D001971:Bromocriptine