Ependymoma
Overview
- Most common spinal cord tumor in adults.
- Localizes to the spinal cord, itself, thus it is an intramedullary spinal cord tumor.
- 3rd most common pediatric tumor, overall.
- Also, localizes to the cerebral ventricles.
- Typically, they are infratentorial: localize to the 4th ventricle.
- Less commonly, they are supratentorial: localize to the 3rd ventricle or lateral ventricles.
- Extra-ventricular cerebral ependymomas are rare.
- Grade 2 and Grade 3 tumors; more aggressive in pediatric patients than in adult patients.
- Note that despite their ability to behave aggressively, these tumors are commonly well demarcated and do not tend to infiltrate surrounding parenchyma but rather compress it and potentially cause obstructive hydrocephalus.
- Ultimately, what often distinguishes the prognosis of an ependymoma (as with many tumors) is whether it can be fully resected or not.
Histopathology
- Sheets of cells with round nuclei.
- True Ependymal Rosettes
- Despite their name, they are uncommon in ependymoma
- Cells surround a central lumen with NO fiber-rich central neuropil (NO significant central cytoplasmic projections).
- Perivascular Pseudorosettes
- Commonly found ependymoma
- Cells surround a central vessel (rather than a lumen). Their tapered cellular processes radiate around the vessel.
Genetics
- May be associated with neurofibromatosis type 2 (NF-2) and thus with chromosome 22q deletions (the NF2 gene mutation is on chromosome 22).
- Remember the mneomnic: NF2 mutation is on chromosome22.
References
- Adesina, Adekunle M., Tarik Tihan, Christine E. Fuller, and Tina Young Poussaint. Atlas of Pediatric Brain Tumors. Springer, 2016.
- Gray, Frangoise, Charles Duyckaerts, and Umberto De Girolami. Escourolle and Poirier’s Manual of Basic Neuropathology. OUP USA, 2013.
- Koeller, Kelly K., R. Scott Rosenblum, and Alan L. Morrison. “Neoplasms of the Spinal Cord and Filum Terminale: Radiologic-Pathologic Correlation.” RadioGraphics 20, no. 6 (November 1, 2000): 1721–49. https://doi.org/10.1148/radiographics.20.6.g00nv151721.
- Louis, David N., Arie Perry, Guido Reifenberger, Andreas von Deimling, Dominique Figarella-Branger, Webster K. Cavenee, Hiroko Ohgaki, Otmar D. Wiestler, Paul Kleihues, and David W. Ellison. “The 2016 World Health Organization Classification of Tumors of the Central Nervous System: A Summary.” Acta Neuropathologica 131, no. 6 (June 1, 2016): 803–20. https://doi.org/10.1007/s00401-016-1545-1.
- Molavi, Diana Weedman. The Practice of Surgical Pathology: A Beginner’s Guide to the Diagnostic Process. Springer Science & Business Media, 2008.
- “Molecular Pathogenesis of Peripheral Neuroblastic Tumors | Oncogene.” Accessed July 6, 2018. https://www.nature.com/articles/onc2009518.
- Orkin, Stuart H., David E. Fisher, A. Thomas Look, Samuel Lux, David Ginsburg, and David G. Nathan. Oncology of Infancy and Childhood E-Book. Elsevier Health Sciences, 2009.
Image References
- Pseudorosette
- Nephron. English: Micrograph of an Ependymoma. H&E Stain. [object HTMLTableCellElement]. Own work. https://commons.wikimedia.org/wiki/File:Ependymoma_intermed_mag.jpg.
- Rosette and Pseudorosette
- Jensflorian. English: Ependymoma Showing True Ependymal Rosettes besides Perivascular Pseudorosettes. October 22, 2010. Own work. https://commons.wikimedia.org/wiki/File:Ependymoma_true_ependymal_rosettes_and_pseudorosettes.jpg.