Germinoma

Germinoma-Feb-2013-A-sag-T1.jpg

Image 1

Germinoma-Feb-2013-B-C-axial-T2-T1-post.jpg

Image 2

Clinical History: 
A 22 year-old woman presents with a suprasellar mass on CT

Diagnosis:
Germinoma

MR Technique: 
Pre-contrast sagittal T1- and axial T2-weighted images are presented along with an axial post-contrast T1-weighted image, all acquired at 1.5 T on a Siemens Espree MR unit. The scans were all 5 mm in slice thickness, with TR/TE = 435/14, 5800/96, and 500/12, and scan times of 3:43, 3:47, and 3:44, respectively.

Imaging Findings:
There is a suprasellar mass lesion, isointense to brain on (A) the midline sagittal pre-contrast T1-weighted scan and (B) the axial T2-weighted scan, with prominent homogeneous enhancement on (C) the axial post-contrast T1-weighted scan. The mass extends to and displaces superiorly the floor of the third ventricle, splays the cerebral peduncles, and descends along the infundibulum inferiorly. The anterior cerebral arteries are at the anterior aspect of the mass and the basilar artery tip is at the posterior inferior aspect of the lesion. The pineal region is unremarkable, and there were no other areas of abnormal contrast enhancement, and specifically no abnormal enhancement within the leptomeningeal spaces. The vast majority of CNS germinomas occur in the midline near the third ventricle. The most common location is pineal, followed by suprasellar. As in the patient illustrated, germinomas typically demonstrate prominent, homogeneous contrast enhancement. Germinomas also typically demonstrate restricted diffusion, due to high cellularity. CSF seeding is common, thus evaluation of the entire neural axis by enhanced MR prior to surgery is recommended. 90% of germinomas present under the age of 20, with a male to female predominance of 10:1.