The authors reviewed magnetic resonance (MR) images in seven cases of germinoma in the hypothalamoneurohypophyseal axis (HNA). The intrasellar portions were clearly identified in six germinomas. Two small germinomas of these six were located only in the neurohypophysis. The major parts of the four large germinomas were located below the optic chiasm, and the large intrasellar portions were demonstrated. The remaining one small germinoma was localized from the pituitary stalk to the third ventricular floor. These findings strongly suggest that the primary site of germinomas in the HNA is the neurohypophysis. In the four large germinomas, the tumor shape was similar to that of pituitary adenoma. The authors believe that age (limited to first three decades), symptoms (diabetes insipidus), MR findings (absence of normal hyperintense signal of the posterior pituitary on TI-weighted (TlWI) images, and homogeneous hypointensity to the pons on TlWI images/isointensity on T2-weighted images are important in differential diagnosis. Cancer 68:1009-1014,1991.
ERMINOMAS occurring intracranially have a pref-G erence for sites in the midline, the pineal region, and the hypothalamoneurohypophyseal axis (HNA). '
Germinomas in the HNA are usually called ectopic pinealomas, suprasellar atypical teratomas, or suprasellar germinomas according to the historical nomenclature of germinomas in the pineal The primary site of germinomas in the HNA remains unclear.
Recent advances in magnetic resonance (MR) imaging permit demonstration of the anatomic details of the sellar and the parasellar region^.^ MR imaging has a multidirectional capability, with no artifacts from bone. In ad-From the