A unique case of central diabetes insipidus (DI) associated with transientpituitary stalk enlargement: Close observation over several years using magnetic resonance imaging (MRI) and hypophysial endocrine tests

We had the opportunity to closely observe a unique case of central diabetes insipidus (DI), in which dramatic changes in both radiological findings an d hypophysial functions were seen. A 63-year-old female developed central D I, and magnetic resonance imaging (MRI) revealed a mild thickening of the p ituitary stalk and lack of hyperintense signal associated with normal neuro hypophysis on T1-weighted images. About three months later, the stalk was f ound to be remarkably expanded like neoplasm; however, anterior pituitary f unctions were almost normal on that occasion, except for the absence of GH response to an insulin tolerance test. About nine months after the onset of DI, secondary hypoadrenalism and hypothyroidism, which required replacemen t therapy, developed transiently, but recovered about one year later. Resul ts of hypophysial endocrine tests during this period showed that the dysfun ction was predominantly suprapituitary in nature. As time passed, the stalk lesion began to shrink spontaneously and another MRI, obtained five years after the onset of DI, disclosed normal findings for the infundibulo-hypoph ysial system, except for lack of the hyperintense signal of the neurohypoph ysis. The patient has since been healthy, except for the DI, which has been controlled by treatment with vasopressin. We report here a unique case of central DI associated with transient pituitary stalk enlargement.