Diabetes insipidus as an early sign of pineal tumor.

A 13-year-old boy's acute onset of diabetes insipidus was the first manifestation of a pineal tumor. One year after the physical symptoms of diabetes insipidus occurred, neurological examinations, tumor markers, and computed tomography brain scan were all normal. Three years later, rapid development of neurological changes was observed with the prevailing symptoms of increased intracranial pressure. The changes were related to a pineal germ cell tumor identified by a high level of beta-human chorionic gonadotropin in plasma and neuroradiological investigations, including computed tomography and magnetic resonance imaging. The clinical course of this case is unusual and we advocate the following: (1) the follow-up of children with diabetes insipidus is important for determining whether or not it is an idiopathic type and (2) elevation of plasma beta-human chorionic gonadotropin and development of neurological signs in patients with so-called idiopathic diabetes insipidus should arouse clinical suspicion of an intracranial germ cell tumor. It should be noted that the brain tumor is significant as the underlying pathology of childhood diabetes insipidus.