Anaplastic Ependymoma (WHO 2000 Grade III)
General: (See also: Ependymoma) Malignant glioma of ependymal origin, with high mitotic activity, microvascular proliferation, and psesudopalisading necrosis. Anaplasia is more frequent in intracranial, especially posterior fossa, ependymomas. The clinical findings are similar to typical ependymoma; localising signs due to mass effect.
Neuroimaging: MRI findings are similar to typical ependymoma, though more likely to show invasion and contrast enhancement.
Gross: Tends to be well demarcated, but may be frankly invasive. Soft, grey-red tumor with variable necrotic or hemorrhagic foci, occasionally with a cystic component.
Microscopic: Increased cellularity and mitotic index, microvascular proliferation, and pseudopalisading necrosis — the absence of a palisading appearance with necrosis should not prompt the label of anaplasia. Perivascular rosettes remain a hallmark, but ependymal rosettes are rare or absent. Tend to remain well demarcated, but may be frankly invasive.
Stains:
- Positive: GFAP+ (reduced versus typical ependymoma), S100+, vimentin+, EMA+, CKC+/- focally, Ki-67 > 4%, nestin+
- Negative: synaptophysin-
- Suggested, focused panel: CKC, EMA, GFAP, S100, synaptophysin, vimentin
((())) WHO 2000
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