Ependymomas

Last updated on Sunday, October 5 2008 by jdmiles

Ependymomas are classified as glial tumors, although they also have epithelial properties. They are common, accounting for 3%-9% of all brain tumors.

They can occur at any age, but are somewhat more common in children.

40% of ependymomas occur in the first decade of life.

40% of ependymomas are supratentorial. Supratentorial ependymomas are more common in adults than in children.

90% of ependymomas occur in the brain, 10% in the spinal cord. Spinal cord ependymomas occur more frequently in adults than in children. Ependymomas are the most common spinal cord gliomas.

As you might expect, they tend to occur where there are ependymal cells - the ventricles and the central canal of the spinal cord. The most common location is the 4th ventricle.

Typical microscopic features of ependymomas include rosettes and pseudorosettes. Rosettes are epithelioid arrangements of tumor cells ito forma a central lumen. In vascular pseudorosettes, there is no actual lumen. Rather, the pseudorosettes represent radial processes that converge on a blood vessel. Rosettes are more specific for ependymomas, but are seen in only about 10% of cases. Pseudorosettes are more common.

An example of a perivascular pseudorosette, cut longitudinally along the vessel:

An example of a true rosette:

There are several more examples of gross and microscopic images of ependymoma below. Please explore the images. Click on any of the thumbnails to see a larger image.

REFERENCES:

Radiographics. 2005 Mar-Apr;25(2):486-90.
Best cases from the AFIP: supratentorial ependymoma.
Mermuys K, Jeuris W, Vanhoenacker PK, Van Hoe L, D'Haenens P.
(PMID:15798065)

Prayson, R.A., and Goldblum, J.R. (Eds.) (2005). Neuropathology. Elsevier Churchill Livingstone, Philadelphia. (ISBN:0443066582) Pages 468-476.

Allan H. Ropper, Robert H. Brown. Adams and Victor's Principles of Neurology, 8th edition. New York : McGraw-Hill Medical Pub. Division, 2005. (ISBN:007141620X)

Related images:

Anaplastic Ependymoma, high power H&E
Anaplastic Ependymomas are characterized by a brisk mitotic rate and microvascular proliferation (seen within the lower right corner of the photographed).

Clear Cell Ependymoma, high power H&E stained section
Clear Cell Ependymomas closely resemble oligodendrogliomas, although they generally demonstrate a somewhat more developed epithelioid appearance. In most ependymomas, clear cell differentiation is a focal feature, although occasionally tumors may be composed entirely of clear cells.

Brainstem Ependymoma, transverse section through brainstem
Ependymomas are felt to arise from ventricular lining cells, and thus demonstrate a tendency for intraventricular growth.

Ependymal Pseudorosette, H&E stained section.
Ependymal Pseudorosette, caught in a predominately longitudinal orientation.

Ependymoma, low power H&E stained section
In Addition to the ependymal lining at the top of the photographs, this ependymoma demonstrates numerous true rosettes along with perivascular pseudo-rosettes. Although the latter are common within ependymal tumors, true rosettes are seen fairly uncommonly.

Ependymoma, intraoperative smear preparation, H&E stain x 400
Occasionally ependymal rosettes and perivascular pseudo-rosettes can be appreciated within cytologic preparations.

Intramedullary Ependymoma, transverse section through spinal cord, H&E stain x 40
Ependymomas are unusual among glial tumors in that they tend to be well-circumscribed. The spinal cord, they generally expand posteriorly from the region of the central canal. This leads to predominantly sensory symptoms, which some clinicians feel allows preoperative diagnosis

Ependymoma involving lateral ventricle, coronal section at the level of the basal ganglia
Derived from ventricular lining cells, ependymomas tend to grow into the ventricular system. The presence of hemorrhage and necrosis within this lesion suggests anaplastic transformation.

fourth ventricular ependymoma, sagittal section through brainstem and cerebellum.
Ependymomas tend to fill and distend the fourth ventricle, resulting in noncommunicating hydrocephalus with signs of increased intracranial pressure. Posterior fossa is the most common site of ependymomal tumors in childhood

fourth ventricular ependymoma, transverse sections through brainstem and cerebellum.
Fatal fourth ventricular ependymoma of childhood, demonstrating extensive intraventricular growth with intratumoral hemorrhage

Intramedullary spinal cord ependymoma, H&E stain x20
The most common site for ependymoma is an adult is within the parenchyma of the spinal cord. Unlike other glial tumors, ependymomas tend to grow by expansion, which allows for complete surgical resection with preservation of spinal cord function.

Spinal ependymoma x40
Spinal ependymoma x40

True ependymal rosettes x20
True ependymal rosettes x20

True ependymal rosettes x400
True ependymal rosettes x400

Myxopapillary ependymoma, mucicarmine histochemical staining x 40
Despite the name, mucin histochemical staining is often quite weak in myxopapillary ependymomas

Myxopapillary ependymoma, H&E stain x 40
Myxopapillary ependymoma is or characterized by thick hyalinized blood vessels.

Myxopapillary ependymoma x 400
Myxopapillary ependymomas often demonstrate densely fibrillary areas resembling piloid astrocytes, referred to as tanycytic differentiation.

Myxopapillary ependymoma, H&E stain x100
Myxopapillary ependymomas often resemble schwannomas, which also occur in the cauda equina and on the filum terminale.

Myxopapillary ependymoma, H. and E. stain x200
Hyalinized-Appearing, thickwalled blood vessels height and the resemblance to the extramedullary schwannomas

Myxopapillary ependymoma, H&E stain x200
Differentiation of myxopapillary ependymomas from schwannomas is based on recognition of the fine fibrillary glial type processes in the ependymal tumor.

Myxopapillary ependymoma x40
Myxopapillary ependymomas often demonstrate angiomatoid type blood vessels, similar to those seen within schwannomas.

Myxopapillary Ependymoma H&E
Thick hyalinized blood vessels, often surrounded by poorly formed perivascular pseudo-rosettes, characterize myxopapillary ependymomas.

Myxopapillary Ependymoma, Sagittal Section
Myxopapillary Ependymomas may fill and distend the thecal sac, encasing nerves of the cauda equina.

Myxopapillary Ependymoma, intraoperative smear preparation x 200
Cytologic preparations often provide valuable information in the differentiation of myxopapillary ependymoma from schwannoma. In this intraoperative smear preparation we can see both perivascular pseudo-rosettes formation as well as intracytoplasmic mucin droplets

Myxopapillary Ependymoma, gross photograph of surgical resection
The filum terminology can be seen attached to the expansile hemorrhagic tumor.

Tanycytic ependymomal of the posterior third ventricle, H&E stain x200
Tanycytes are ependymal cells which communicate between CSF and blood spaces. They demonstrate prominent spindle cell morphology resembling piloid astrocytes and Antoni A areas of schwannoma.

Tanycytic ependymoma pseudorosette x400
Tanycytic ependymoma pseudorosette x400

Tanycytic ependymoma x200
Tanycytic ependymoma x200

Tanycytic Ependymoma H&E
Tanycytic Ependymoma H&E

Anaplastic ependymoma, microvascular proliferation.
As with the other infiltrating gliomas, microvascular proliferation within ependymal tumors usually signifies anaplastic transformation.

Anaplastic ependymoma, H&E x 400
In non-astrocytic gliomas, the presence of a brisk mitotic rate is the most important histopathologic variable defining anaplastic transformation.

Anaplastic giant cell ependymoma, H&E stain x 200
Anaplastic giant cell ependymoma is a rare ependymal tumor often confused with glioblastoma multiforme

Astroblastomatous rosettes, H&E stain X 600
Astroblastomatous rosettes may occur in glioblastoma multiforme. Compared with the very fine fibrillary ependymal pseudo-rosettes, astroblastomatous rosettes demonstrate much coarser terminations along the central blood vessels.