Ependymoma

NF-2 Codes for a protein that inhibits the Meningioma, ependymoma, and schwannoma... 

Gene expression patterns in ependymomas correlate with tumor location, grade, and patient age. Am. J. Pathol. 163(5), 1721-1727. 

Spinal subarachnoid hemorrhage is very rare. It is caused by a vascular malformation, hemostatic failure, coarctation of the aorta, inflammatory vascular disease, mycotic aneurysm or a vascular tumor such as ependymoma. Accumulating hematoma may compress the spinal cord. Suspicion is aroused if the cerebral angiogram is negative and the patient develops spinal cord signs. 

Dlfferential diagnosis includes metastatic renal cell carcinoma (HBME-1-), chondrosarcoma (CK-), myxopapillary ependymoma (CFAP-i-), and hemangioendothelioma (CD3U/FLI-1+). 

Coffin CM, Swanson PE, Wick MR, et al. An immunohistochemical comparison of chordoma with renal cell carcinoma, colorectal adenocarcinoma, and myxopapillary ependymoma A potential diagnostic dilemma in the diminutive biopsy. Mod Pathol. 1993 6 531-538. 

Most grade II to IV gliomas infiltrate CNS tissue, which makes total resection difficult to impossible. Exceptions include certain ependymomas and xanthoastrocytomas. 

Astrocytomas are among the most fibrillar of CNS neoplasms, more fibrillar than other gliomas except tany-cytic ependymomas and subependymomas (see Table... 

Ependymoma Hypercellularity ependymal or perivascular rosettes, or both round/oval nuclei cilia and basal bodies GFAP (+) Cerebrum cerebellum spinal cord CNS... 

Tanycytic ependymoma/ subependymoma Combination of astrocytoma and ependymoma round/oval nuclei cluster among fibrillar mats GFAP (-r) Spinal cord fourth ventricle subependymal CNS... 

Anaplastic ependymoma Preceding features with mitoses necrosis GFAP (S) S-100 Cerebrum cerebellum... 

Ependymoma/ Structures of ependymoma or malignant CFAP (S) cytokeratin Cerebellum ... 

Myxopapillary ependymoma Cuboidal/columnar epithelium on hyaline fibrovascular papillae variable fibrillarity GFAP (S) Regions of the filum terminale... 

Astroblastoma is rare. Astroblastic rosettes resemble perivascular pseudo-rosettes of ependymomas, except that the astroblastic processes remain thick the entire distance from cell body to adventitia of the vessel. Foot processes may even thicken near the adventitia. 

Immunohistochemical stains used in conjunction with routine neurohistochemical stains define this neoplasm Although astroblastomas express focal GEAP, they do not stain with PTAH. This dichotomy may be due to expression of a nonfibrillar form of the GEAP molecule different from the fibrils of ependymoma and astrocytoma that stain for both. 

Ependymomas are an excellent example of how IFIC highlights structural features important to their interpretation. 

The cellular conformations of ependymomas vary between fibrillar and epithelial, posing special problems of differentiation not only from other gliomas but also from carcinomas and meningiomas (see Tables 20.5 and... 

These latter differentiations are facilitated if one recalls that even epithelioid ependymomas frequently stain with anti-GFAP, have distinctive ultrastructure, and often contain at least a few cells with fibrillar processes (Fig. 20.19 see Boxes 20.1 and 20.2). The anti-GFAP stain highlights these fibrillar processes, greatly... 

Electron microscopy is better than IHC for difficult ependymomas (see Fig. 20.19C). It shows cilia, basal bodies, cytoplasmic inclusions of microvilli, and elongated intercellular junctions. 

Rare ependymomas have sparse CK or EMA immu-noreactivity on their most differentiated epithelium. However, even these have much less CAM5.2 than choroid plexus papillomas and carcinomas. CAM5.2 is recommended to distinguish them. 

The general features of ependymoma just described are useful in identifying the variants of ependymoma discussed in this section, except where specifically excluded. 

The subependymoma protrudes from the wall of a ventricle into the ventricular space. Its histologic and immunohistochemical features closely resemble those of tanycytic ependymoma (see Table 20.5). It is usually benign. 

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