ECTOPIC PITUITARY-ADENOMA OCCURRING IN THE INTERPEDUNCULAR CISTERN

Intracranial ectopic pituitary adenoma occurs most frequently in the s uprasellar cistern, usually in continuity with the pituitary stalk. Su ch tumors probably originate from cells of the pars tuberalis located above the diaphragma sellae or from aberrant anterior pituitary cells of the pituitary stalk. The authors report the case of a 37-year-old w oman with Gushing's syndrome caused by an ectopic pituitary adenoma of unique location: the tumor was separate from the pituitary stalk and confined within the interpeduncular cistern. After surgical removal of the tumor, continued improvement in the patient's laboratory results and disappearance of her endocrine symptoms strongly indicated the abs ence of adenoma cells in the pituitary gland or stalk. The tumor in th e present case appears to have arisen from aberrant pituitary cells th at were present in the leptomeninges of thr basal surface of the hypot halamus.