Fig. 1

Radiological features of Case #1 tumor. a Axial T2-weighted MRI sequence showing a well-delineated left frontal hyperintense lesion (arrow). b Axial diffusion-weighted sequence demonstrating hyperintensity corresponding to hypercellularity of the solid component c Axial susceptibility-weighted sequence showing hypointensity consistent with hemorrhage within the tumor (arrow). d Axial CT showing calcifications (arrow) and acute hemorrhage (star) e Axial perfusion sequence with Cerebral Blood Volume Map showing moderate hyperperfusion of the solid component (arrow). Sagittal T1-weighted f before and g after contrast injection demonstrate juxta-ventricular location of the mass lesion (arrowheads) and a subtle area of enhancement (arrow) h MRI follow-up at two years with post-contrast sagittal T1-weighted sequence showing tumor progression and increase of enhanced components. i Axial FLAIR sequence performed one year after surgery showed an intraventricular ependymal dissemination (arrowheads). j Ependymal differentiation with calcifications (HPS, magnification 400 ×). k Microcysts containing myxoid substance (HPS, magnification 400 ×). l Necrosis (HPS, magnification 400 ×). m Olig2 immunoreactivity (magnification 400 ×). n No immunoexpression for GFAP (magnification 400 ×). o MIB1 labeling index (magnification 400 ×). p No immunopositivity for BCOR (magnification 400 ×). q Expression of SATB2 (magnification 400 ×) Black scale bars represent µm. HPS Hematoxylin Phloxin Saffron.