Rosette-forming glioneuronal tumor: report of a chiasmal-optic nerve example in neurofibromatosis type 1: special pathology report.

OBJECTIVE: Rosette-forming glioneuronal tumor is a rare, rather recently described tumor featuring a highly distinctive, biphasic histological pattern, including a cytologically uniform neuronal component of Homer-Wright type pseudorosettes and an accompanying astrocytic element resembling pilocytic astrocytoma. Its occurrence in the posterior fossa and association with the fourth ventricle is stereotypical and a feature of all reported cases. CLINICAL PRESENTATION: In this article, we describe the first rosette-forming glioneuronal tumor arising outside this site, a histologically classic example involving the anterior visual pathway and associated with neurofibromatosis type 1. INTERVENTION: Genetic (fluorescent in situ hybridization) studies demonstrated no large deletion in either normal or neoplastic tissue, indicating that the genetic abnormality underlying neurofibromatosis type 1 in this patient is likely a very small deletion or point mutation. CONCLUSION: The relation of the tumor to the underlying neurofibromatosis type 1 cannot be assessed.

Oligodendroglioma metastatic to bone marrow.

We report on a patient with oligodendroglioma metastatic to bone, presenting with pancytopenia and fever 10 years after initial tumor resection. Our review of the literature showed a total of 30 reported extraneural metastases, with only 19 of these being similar cases of bone metastases. These bony lesions have increased signal intensity in T2-weighted and low signal intensity on T1-weighted images, with intense homogeneous enhancement. However, on MR imaging, we were unable to find necrosis or compression deformity of the vertebrae, despite extensive metastatic disease.