• Clinical History
• Light Microscopy
• Electron Microscopy
• Diagnosis and Comments
• Readers Feedback

Diagnosis: Ependymoma – Thoracic spinal cord

Comment:

Ependymomas are relatively uncommon central nervous system neoplasms. Their estimated incidence is between 2 and 6 % of all gliomas. They can occur at any age but occur mainly in children. Ependymomas are usually intimately associated with the ventricles with the fourth ventricle being the most common site, but they also occur in the spinal cord. Most spinal ependymomas occur in adults. Ependymomas express their dual glial and epithelial heritage by the production of glial fibrillary acidic (GFA) protein-positive intracytoplasmic filaments and the formation of true rosettes. By light microscopy, the diagnostic features are the presence of ependymal rosettes or elongated clefts bordered by an ependymal epithelium. These features, however, are present only in a minority of cases. Perivascular pseudorosettes are suggestive, but not diagnostic of ependymoma, because they can also be present in other gliomas. Some ependymomas, such as the present case, contain neither true rosettes nor perivascular pseudorosettes. In such instances accurate recognition of an ependymoma requires a high index of suspicion and confirmation requires electron microscopy because both astrocytomas and ependymomas are immunoreactive with antibodies to GFA protein. The ultrastructural characteristics of an ependymoma, however, are distinctly different from those of an astrocytoma. With ultrastructural examination, ependymoma cells contain intracytoplasmic intermediate filaments, usually in a perinuclear distribution, conspicuously long junctional complexes, numerous slender surface microvilli, abnormal cilia, and intracytoplasmic lumina containing variable numbers of microvilli and cilia. Astrocytoma cells are not connected by cell-to-cell junctions. They also do not have intracytoplasmic microvilli-lined lumina.

The biologic behavior and treatment of ependymomas, particularly spinal ependymomas in adults, may be different than that of diffuse fibrillary astrocytomas. In general, the outlook for adults with spinal ependymomas is more favorable than those with astrocytomas. Correct diagnosis, therefore, is imperative.