Since the patient had been exposed to 175 R of whole-body gamma radiation, the possible influence of such exposure on the development of the pitui~ tary adenoma must be considered. Intracranial tumors have been reported, pos- sibly associated with radiation exposure (107,108,197), but these were mainly gliomas, meningiomas, neurinomas, etc., and not pituitary adenomas. In a study of the Japanese exposed to the A-bomb, Seyama et al. (109) reported an increase in certain types of intracranial tumors in a group exposed to 100 R or more, but no increase in pituitary adenomas. Therefore, the association of radiation exposure with the development of the pituitary tumor in this patient does not seem likely. - 52 ~-