title: Rosette-forming glioneuronal tumor: pathology case report.
abstract: OBJECTIVE
  Rosette-forming glioneuronal tumor is a newly described mixed glial and neuronal tumor. We describe two cases and review the literature to better characterize this entity.
  
  
  METHODS
  Patients were surgically treated, and tumors were diagnosed by light microscopy and immunohistochemistry using the avidin-biotin complex method. PubMed was searched for previously reported cases.
  
  
  RESULTS
  Patient 1 was a 38-year-old woman who presented with headaches and no neurological abnormality. Magnetic resonance imaging showed a solid mass in the fourth ventricle. Subtotal excision of the mass caused transient gait ataxia. Patient 2 was a 51-year-old woman with dizziness who fell and sustained head trauma. Magnetic resonance imaging revealed a right paramedian cerebellar cystic and nodular mass and a separate nodule in the vermis, which were excised gross totally with no morbidity. Microscopic examination showed neuroepithelial tumors composed of neurocytic cells focally forming well-defined rosettes that were immunopositive for neuronal markers and of elongated, glial fibrillary acidic protein-immunoreactive astrocytes. No histological anaplasia was present. Both patients were well 18 and 8 months after surgery, respectively. Eighteen rosette-forming glioneuronal tumors were identified with the literature search.
  
  
  CONCLUSIONS
  These are tumors of young adulthood (range, 12-59 yr) usually in or close to the fourth ventricle. Histologically, they are low-grade, although multiple foci or local extension may prevent total excision and account for some recurrences. On imaging, they are cystic, solid, or both, with minimal perilesional edema or mass effect. They are composed of neurocytic and glial elements, probably arising from a common progenitor in the subependymal plate, and need to be differentiated from a variety of glioneuronal tumors.
authors.affiliation: Department of Neurology, Laboratory of Neuropathology, Institute of Molecular Medicine, Hospital de Santa Maria, Lisbon Faculty of Medicine, Lisbon, Portugal. josepimentel@fm.ul.pt
authors.forename: José
authors.initials: J
authors.lastname: Pimentel
authors.forename: Mário
authors.initials: M
authors.lastname: Resende
authors.forename: Artur
authors.initials: A
authors.lastname: Vaz
authors.forename: Ana M
authors.initials: AM
authors.lastname: Reis
authors.forename: Alexandre
authors.initials: A
authors.lastname: Campos
authors.forename: Herculano
authors.initials: H
authors.lastname: Carvalho
authors.forename: Mrinalini
authors.initials: M
authors.lastname: Honavar
mesh_terms: D000328:Adult; D002551:Cerebral Ventricle Neoplasms / Q000473:pathology* / Q000503:physiopathology / Q000601:surgery; D005260:Female; D020546:Fourth Ventricle / Q000473:pathology* / Q000601:surgery; D018303:Ganglioglioma / Q000473:pathology* / Q000503:physiopathology / Q000601:surgery; D006801:Humans; D007150:Immunohistochemistry; D008279:Magnetic Resonance Imaging; D008875:Middle Aged; D019635:Neurosurgical Procedures