Characterization of a pituitary stone.

Calcification of the pituitary is unusual and functional studies of such cases have not been previously reported. We have been able to document persistent prolactin secretion both in vivo and in vitro in a patient with a severely calcified pituitary adenoma ("pituitary stone"), and have also documented prolactin granules within the calcified tissue mass. Normal menstrual function was restored after surgical removal of the "stone," and galactorrhea subsided although the prolactin response to thyrotropin-releasing hormone (TRH) remained abnormal. Two years after surgery the menstrual cycle has remained regular, but galactorrhea has recurred, emphasizing the need for prolonged follow-up in patients with prolactin-producing adenomas, despite apparent surgical cure. The in vitro studies showed that human pituitary tissue is secretory in culture and thus may serve as a useful tool for physiologic studies of the pituitary cell.