Low grade astrocytoma of the pituitary stalk.

A case of low grade astrocytoma (WHO grade II) localised in the pituitary stalk is reported in a 46 year old female who presented with central diabetes insipidus. Six-monthly magnetic resonance imaging was use to determine the progression of the lesion. The patient had a stereotactic biopsy of the lesion 18 months after the initial presentation. The diagnosis was established with the aid of immunohistochemistry. We emphasize the importance of MRI before initiating therapy to evaluate the pituitary stalk lesion and the effectiveness of stereotactic biopsy in securing tissue diagnosis without additional deficit.