Extradural myxopapillary ependymoma: report of two cases and review of the literature.

The cauda equina is the most frequent location for ependymomas, particularly the myxopapillary variant, which generally arises from the filum terminale. These tumors have a characteristic histopathologic pattern and are usually easily recognized. The occurrence of these tumors in an extradural, sacrococcygeal, or subcutaneous location may prove challenging, particularly in the absence of any obvious central nervous system connection. We describe two such extradural cases, one with multiple regional and distant metastases and the other with multiple recurrences. The origin of these tumors from subcutaneous sacrococcygeal ependymal rests is postulated on the basis of earlier reports. Clinical and histopathological features are described and a review of the literature is presented.