[Pilocytic astrocytoma and diencephalic syndrome in an adult with neurofibromatosis type 1].

We report a rare case of pilocytic astrocytoma and diencephalic syndrome occurring together in a 30-year-old woman with neurofibromatosis type 1 (NF-1). Diencephalic syndrome included emaciation and somnolence. Gadolinium-enhanced magnetic resonance imaging revealed a brain tumor in the optic chiasmal-hypothalamic region, which invaded the thalamus, brain stem and cerebellum. A biopsy specimen from the chiasmal tumor was compatible with pilocytic astrocytoma. Although she received radiation therapy, she died 22 months after the onset of the disease.