Fig. 4.

Germinoma. An approximately 30-year-old male with poor vision and no uropathy at the time of magnetic resonance imaging. a Sagittal T2WI shows a mass in the upper part of the sella turcica with isointensity compared to gray matter (arrow). b Axial T2WI shows a cystic component (arrow). c Axial T1WI shows an isointensity mass (arrow). d Sagittal contrast-enhanced T1WI shows relatively uniform contrast enhancement (arrow). e Coronal contrast-enhanced T1WI shows infiltration of the optic chiasm (arrow). f Non-contrast computed tomography shows isodensity (arrow). Germinoma was diagnosed based on craniotomy biopsy. Post-biopsy, steroids were administered, and central diabetes insipidus/arginine vasopressin deficiency (CDI/AVP-D) developed. This was attributed to the presence of an adrenocorticotropic hormone secretory defect, a phenomenon known as masked CDI/AVP-D