INTRASELLAR PRESENTATION OF A CYSTIC OPTIC CHIASM FIBRILLARY ASTROCYTOMA

The unusual radiologic presentation of an optic chiasm fibrillary astr ocytoma extending through and expanding the diaphragma sellae in an 8- year-old male is described. The child presented with decreased vision in the right eye. Magnetic resonance imaging demonstrated a cystic int ra-and suprasellar mass, isointense on T1WI and hyperintense on T2WI, that enhanced with contrast. There was no radiographic involvement of the pituitary or hypothalamus. The optic chiasm could not be seen. The tumor mass was believed to be a craniopharyngioma and was partially r emoved by a transsphenoidal approach. Frozen section was not consisten t with craniopharyngioma. Histochemical stains were positive for glial fibrillary acidic protein and S100 protein and nonreactive for EMA or actin. Electron microscopy showed abundant cellular processes and cyt oplasmic filaments within the cells. A diagnosis of intrasellar fibril lary astrocytoma, probably arising from the optic chiasm, was made.