Rosette-forming glioneuronal tumour of the lateral ventricle in a patient with neurofibromatosis 1.

We report a 33-year-old man with neurofibromatosis type 1 (NF-1) with a rosette-forming glioneuronal tumour (RGNT) in the lateral ventricle. The patient had been treated with radiotherapy and chemotherapy for a typical juvenile pilocytic astrocytoma of the hypothalamus seven years prior. MRI revealed a contrast-enhancing mass in the anterior horn of the left lateral ventricle. Histological examination demonstrated two distinct regions characterised by a rosette-forming neurocytic component and an astrocytic predominant component. Immunohistochemical studies showed glial fibrillary acidic protein and S-100 positivity in the astrocytic component and neuron-specific enolase was positive in the neurocytic cells. Although RGNT has been reported at other sites within the central nervous system, this report documents a previously undescribed lateral ventricular location of a rare RGNT in an asymptomatic patient with NF-1.