Cortical ependymoma: an unusual epileptogenic lesion

Clinical article

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Supratentorial cortical ependymomas (CE) are rare, with 7 cases reported. The lesions, typically occurring in the superficial cortex in young adults and associated with a history of seizures, are not fully characterized. Furthermore, their relationship with the recently described angiocentric glioma (AG) is still being debated. This study was undertaken to summarize the authors' experience with CEs.


Between 1997 and 2009, 202 cases of ependymoma were surgically treated at the Mayo Clinic, 49 of which were supratentorial. Among these, 9 CE cases were retrospectively identified. Clinical, imaging, and pathological features of each case were reviewed.


Tumors arose from the frontal (5 cases), parietal (3), and occipital (1) lobes. No tumor occurred in the temporal lobe, despite its reported association with seizures. The mean age at presentation was 27 ± 19 years (± SD) and age at resection was 36 ± 16 years. The mean size of the lesion was 16 ± 14 cm3. Seizures were the presenting symptom in 78%. Cross-sectional imaging in 8 cases was characterized by a heterogeneous mass with multiple cystlike areas and enhancement of the soft-tissue component. Gross-total resection was achieved in 8 of 9 tumors. Pathologically, 6 were low-grade (WHO Grade II) and 3 were anaplastic (WHO Grade III) ependymomas. All tumors exhibited the focal presence of perivascular pseudorosettes, but only 1 (11%) exhibited the focal presence of a true rosette. A bipolar spindle cell component resembling AG was present in 3 (33%) and “Schwannian-like” nodules in 2 (22%). Subpial aggregation and peripheral infiltration were present in 4 cases (44%). With a mean postsurgery follow-up of 62 ± 38 months, only 2 lesions recurred locally after imaging-confirmed gross-total resection, both being Grade III. In 5 (71%) of 7 patients presenting with seizures an Engel Class I outcome was achieved.


Cortical ependymomas represent a rare type of ependymoma occurring superficially in the cortex. Morphologically, these tumors are protean, varying from classic to epithelioid, clear cell, and tanycytic. Some also exhibited features typical of AG. Most tumors were low grade and cured with resection. Anaplastic tumors occur and may recur locally despite provision of radiation therapy. Cortical ependymomas frequently, but not always, present with seizures, but despite their high association with epilepsy, none occurred in the temporal lobe in any of the authors' 9 patients. Overall, CEs appear to have a relatively favorable prognosis compared with other supratentorial ependymomas.

Abbreviations used in this paper: AG = angiocentric glioma; CE = cortical ependymoma; GTR = gross-total resection; STR = subtotal resection.

Article Information

Address correspondence to: Caterina Giannini, M.D., Ph.D., Department of Pathology, Mayo Clinic, 200 First Street SW, Rochester, Minnesota 55905. email:

Please include this information when citing this paper: published online January 14, 2011; DOI: 10.3171/2010.12.JNS10846.

© AANS, except where prohibited by US copyright law.



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    1.1. Case 5. A–C: Small exophytic CE. Noncontrast axial T1-weighted image showing small focal exophytic cystlike mass extending from cortical margin of right frontal lobe (arrowheads, A), axial T2-weighted image revealing hyperintensity of the mass similar to fluid signal intensity (B), and noncontrast coronal T1-weighted image demonstrating a small rim of cortex around the margin of the mass (arrows, C). 1.2. Case 7. A–C: Left parietal CE. Axial T2-weighted image revealing a bubbly appearance reminiscent of dysembryoplastic neuroepithelial tumor (multicystic) (A), postcontrast axial T1-weighted image demonstrating enhancement (asterisk, B), and postcontrast coronal T1-weighted image demonstrating popcorn enhancement (asterisk, C). 1.3. Case 3. A–C: Cortical ependymoma with surrounding edema. Noncontrast axial T1-weighted image showing hypointense mass (arrows) and surrounding edema (arrowheads, A), axial FLAIR image highlights surrounding vasogenic edema (B), and postcontrast axial T1-weighted image showing intense enhancement of the mass with scattered curvilinear nonenhancing areas (arrowheads) along the medial margin, which may represent calcification (C).

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    Photomicrographs illustrating the spectrum of CE morphologies, varying from classic with pseudorosette formation as seen in Case 1 (A), to tanycytic as seen in Case 2 (B), and to epithelioid (C) and clear cell (D) in Case 7. H & E, original magnification × 20.

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    Case 9. Left-sided frontal CE. A: Axial FLAIR image showing slight gyral enlargement and flair signal change. B: Coronal FLAIR image demonstrating a hyperattenuated supraorbital abnormality. C: Postcontrast axial T1-weighted image revealing wispy enhancement (arrow) of the cortical margin of the tumor. D: Gross pathological postfixation specimen exhibiting a whitish expanded cortical area overlying the lesion associated with this tumor. E: Gross and low-power microscopic appearance of this largely cortical lesion, relatively demarcated and stained with the glial marker GFAP (upper right) but not with neuronal marker synaptophysin (lower right). F: Photomicrographs showing a solid cellular component with formation of true rosettes (single asterisk) as well as a fasciculated spindle cell component (double asterisks). H & E, original magnification × 10 (single asterisk) and × 20 (double asterisks). G: The glial marker GFAP is strongly expressed in tumor cells. Original magnification × 20. H: Epithelial membrane antigen stain highlights the presence of a typical dotlike pattern of stains, typically corresponding to cytoplasmic microlumina. Original magnification × 20.

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    Case 6. Photomicrographs of exophytic CE demonstrating peripheral infiltration with perivascular aggregates (A) and subpial extension (B). Two photomicrographs demonstrating examples of spindle cell “Schwannian-like” nodules (C and D). H & E, original magnification × 20.

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    Case 3. Anaplastic ependymoma. Left: Low-power H & E–stained photomicrograph demonstrating classic features of ependymoma. Original magnification × 20. Right: High-power H & E–stained photomicrograph showing high mitotic activity (mitotic figures indicated by arrows) supporting the diagnosis of anaplastic ependymoma (WHO Grade III). Original magnification × 40.


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