Contributed by Marco Losa, MD, Manfredi C. Carta, MD, Karl Frontzek, MD, Niklaus Krayenbühl, MD, Werner Wichmann, MD, Elisabeth J. Rushing, MDFINAL DIAGNOSIS
Clear cell ependymoma (CCE).
DISCUSSION
Clear cell along with tanycytic and papillary ependymoma represent three morphological ependymoma variants without prognostic significance. In limited biopsies, CCE may be mistaken for oligodendroglioma. Unlike oligodendroglioma, CCE is well-circumscribed, lacks the 1p19q co-deletion and is IDH-wildtype. In contrast to the current case, most cases are found in children, especially in the supratentorial compartment. In the past, electron microscopy was a helpful tool for distinguishing morphologically ambiguous cases. The ultrastructural features of ependymal tumors comprise microlumina with microvilli and cilia as well as runs of intermediate junctions. IHC with EMA, which immunostains surface structures and dot-like microlumina has largely obviated the need for EM. NHERF/EBP50, an organizer of polarity structures, has been recently reported to stain 35% of ependymomas that lacked reactivity for EMA. This case underscores the value of this diagnostic marker.
Acknowledgements
The authors would like to thank the electron microscopy division for their excellent support.
REFERENCES
Contributed by Marco Losa, MD, Manfredi C. Carta, MD, Karl Frontzek, MD, Niklaus Krayenbühl, MD, Werner Wichmann, MD, Elisabeth J. Rushing, MD
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