A Case of Central Diabetes Insipidus in a Patient With a Pineal Mass Suspected to Be a Germinoma: A Case Report.

Central diabetes insipidus (CDI) is a rare condition characterized by excessive urination and thirst due to vasopressin deficiency. The underlying cause of CDI remains unknown in many cases. Tumors are a leading cause of CDI in young individuals, with germinoma being the most prevalent. We present a case of a 22-year-old male diagnosed with infundibuloneurohypophysitis (INH) of unknown etiology. His pituitary stalk thickening partially responded to high-dose prednisone treatment; however, one year after initial diagnosis, a new pineal region mass was noted on imaging. Further evaluation revealed the mass to be most likely a germinoma. This case emphasizes the importance of ongoing clinical and radiologic follow-up in idiopathic cases of CDI. The patient's symptoms improved with desmopressin, but the presence of the pineal mass necessitates further comprehensive neurosurgical evaluation.