A 40-year-old woman had a 1-year history of amenorrhea-galactorrhea. She was found to have an intrasellar tumor with suprasellar extension and a prolactin level of 98.1 ng/mL. Subtotal resection of the tumor resulted in a return of the prolactin level to normal within 4 days of the operation and of the prolactin response to thyrotropin releasing hormone, accompanied by the disappearance of the galactorrhea. Histologic examination revealed a typical craniopharyngioma. These observations indicate that one important mechanism of hyperprolactinemia in patients with craniopharyngioma is direct encroachment on the hypothalamus and/or pituitary stalk by the tumor and interruption of prolactin inhibiting factor.
