Outcome of diabetes insipidus in patients with Rathke's cleft cysts

Objectives: It is well-known that Rathke's cleft cysts (RCCs) infrequently cause headache, endocrinological dysfunction, and visual disturbance, and in rare cases, cause diabetes insipidus (DI). Although surgical evacuation of the cyst content can result in high rates of symptomatic improvement, not only the treatment efficacy but also the pathophysiology of DI with RCC are undetermined. The aim of this study is to elucidate the underlying mechanisms and outcomes of DI associated with RCCs. Patients and Methods: We retrospectively studied 109 patients with RCCs treated at Kanazawa University Hospital between 2000 and 2016. Their age, sex, symptoms, endocrinological status, DI, visual disturbance, neuroradiological findings, pathological appearances, and pre-/post-operative hormone levels and status of antidiuretic hormone replacements were assessed. Results: Among 109 cases of RCCs, five cases (4.6%, 2 males and 3 females) manifested with DI as initial presentation were included. These five cases could be divided into two types: the acute type and the chronic type, based on the onset and duration of symptoms. Three acute onset cases presented with not only strong thirst but also sudden headaches without pituitary dysfunction, whereas the two chronic onset cases presented with chronic headaches and hypopituitarism. Pathological examination in the acute type revealed inflammatory cell infiltration into only the posterior lobe of the pituitary and disruption of the cyst wall adjacent to the posterior lobe, which might suggest RCC rupture. In contrast, the chronic type showed inflammatory cell infiltration into both the anterior and posterior lobes of the pituitary and thickened fibrosis beneath the cyst wall. Postoperatively, two cases of the acute type could be controlled with a smaller amount of 1-deamino-8-D-arginine vasopressin (DDAVP) than that required preoperatively, whereas no change was observed in the cases of the chronic type. Conclusion: The cases of DI onset caused by RCCs could be divided into the acute type and the chronic type. In the chronic type, surgical treatment could not affect the status of DI. However, in acute type, urgent surgical intervention partially relieved DI.