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Washington University Experience | NEOPLASMS (GLIAL) | Ependymoma - Microscopic | 17D (Case 17) Tumor_014 - Copy
Electron microscopy was performed in an attempt to identify characteristic ultrastructural features of tumors with ependymal differentiation. Tumor tissue was extracted from formalin-fixed paraffin-embedded tissue, and embedding in plastic prior to preparation of one micron plastic sections; therefore, the preservation was not optimal. Ultrastructural examination demonstrated unequivocal zipper junctions and structures with morphologic features of cilia. There were no dense core granules and no neuritic processes to suggest a component of neuronal differentiation.
Numerous other examples of electron micrographs from this case are present in the “Ependymoma – Electron Microscopy” section of this atlas where they are shown as case #4. ---- Not shown: Epithelial membrane antigen shows a small subset of cells with perinuclear dot-like positivity. D2-40 is essentially negative. Pancytokeratin is largely negative, although there are very rare punctate stain deposits. Synaptophysin immunostaining demonstrates weak punctate immunoreactivity within the cytoplasm of neoplastic cells. ---- FISH showed loss of monosomy 10q (PTEN loss). There was no evidence of EGFR gene amplification and polysomy of chromosome 7 was seen in only 14% of tumor cells. There was no evidence of amplification of MYCN or MYC. ---- Diagnosis Comment: The findings of solid growth, perinuclear dot-like EMA positivity and ultrastructural features are diagnostic of an ependymal neoplasm. The cytogenetic evidence for PTEN loss is compatible with this diagnosis. The presence of robust microvascular proliferation, tumor necrosis and elevated mitotic rate are features of anaplasia and warrant the diagnosis of a WHO grade 3 ependymoma.
