PMC4903119_01
Axial T1 (a) and sagittal T2 (b) sequence shows a round mass (arrows) posterior to the cauda equina at L1-L2 that is hypointense on T1WI and heterogeneously hyperintense on T2WI. Axial T1 FS postcontrast (c) and sagittal T1 postcontrast (d) sequence shows an enhancing intradural, extramedullary mass (arrows) posterior to the cauda equina at L1-L2.
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fig1
Precontrast MRI showed intrinsic T1 hypointensity and heterogeneous T2 hyperinstensity (Figures 1(a) and 1(b)). Postcontrast imaging showed homogenous postcontrast enhancement (Figures 1(c) and 1(d)).
Intraoperative photo shows a tan, fleshy tumor (white arrow) within the thecal sac, clearly outside the cauda equina (black arrow).
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fig2
A tan, fleshy intradural tumor was identified (Figure 2).
(a) H&E, mag x100, cellular glial neoplasm composed of intermingled ependymal component (white arrow) and eosinophilic fibrillary component (black arrow). (b) H&E, mag x400, both components of the lesion, pseudorosette on the left (black arrows) and fibrillary component with numerous Rosenthal fibers on the right, with the largest Rosenthal fiber in the center (black arrow). An eosinophilic body is seen on the left, above the vessel (arrowhead).
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fig3
Permanent sections showed cellular biphasic glial neoplasm: moderately cellular tumor with numerous perivascular pseudorosettes and less cellular areas with prominent eosinophilic fascicular component (Figure 3(a)). Many Rosenthal fibers were noted within the fascicular component, along with giant cell-like tumor cells and cystic change (Figure 3(b)).
(a) H&E, mag x400, bright eosinophilic deposits (black arrows) representing Rosenthal fibers in astrocytic component admixed with ependymal component (white arrows), adjacent to pseudorosette formation (arrowhead). (b) H&E mag x40, pseudocapsule (black arrow) with exclusively ependymal component at periphery of the lesion (arrowheads); astrocytic component is in the center (white arrow).
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fig4
Focally, within the same pseudorosette, some cells show ependymal features, while others are more eosinophilic and fibrillary with Rosenthal fibers (Figure 4(a)). Interestingly, the periphery of the lesion consisted of ependymal component and central portion of the lesion had fibrillary and ependymal components intermingled (Figure 4(b)).
(a) Immunohistochemistry for synaptophysin, mag x40, shows more intensive cytoplasmic staining in ependymal regions (arrows). (b) Immunohistochemistry for EMA, mag x200, shows cytoplasmic, dot-like (arrows), and ring-like (arrowhead) cytoplasmic positivity in ependymal component.
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fig5
S-100 (more in fascicular component). Synaptophysin was staining stronger in the ependymal component (Figure 5(a)). The epithelial membrane antigen (EMA) showed cytoplasmic dot-like positivity in many cells of ependymal component (Figure 5(b)).