Case of the month. April 1996--pituitary tumor.

A 20 year old man presented with intermittent diplopia and difficulty focusing his leftward gaze during the past month. His past medical history was only significant for a dermoid cyst in the posterior fossa which was removed at age 10. MRI scans demonstrated a perisellar mass, eroding the sphenoid and surrounding the right carotid artery as well as extending into the sella. A transsphenoidal endoscopic resection was performed. The tumor was diagnosed as a germinoma (seminoma). Most germinomas in the brain arise in the pineal, however, germ cell neoplasms (including teratomas, germinomas and non-germinomatous germ cell neoplasms) are not unknown in the perisellar region and typically arise in the hypothalamic region and present with diabetes insipidus, visual disturbances or hypopituitism.