ABSTRACT
INTRODUCTION: Ependymomas are glial neoplasms that arise at or close to the inner ependymal surface of the ventricular system. They are most frequently located intraventricularly, but they may also occur in the spinal cord or, very seldom, at extraneural sites. Here we report a case of an ectopic ependymoma, arising in the pelvic cavity. CASE REPORT: A 35 year-old female patient was diagnosed with a suspect tumor mass in the rectovaginal space, infiltrating the perirectal adipose tissue and the vagina. Three years later, liver and peritoneal metastases of the same tumor were diagnosed. Two years after that, the patient experienced a recidive in the left adnexa. Histological analysis revealed an anaplastic tumor of dual nature, comprising of mesenchymal and epithelial features. There were ependymoma-like rosettes and pseudorosettes, indicating an ependymal differentiation. Immunohistochemically, the tumor was positive for epithelial membrane antigen (EMA) and glial fibrillary acidic protein (GFAP). Accordingly, the diagnosis "grade 3 ependymoma, i.e. ependymoblastoma" was made. REVIEW: Ependymomas are most frequently located in the ventricular system, but may also occur in the spinal cord or rarely at extraneural sites. Extraneural ependymomas represent a diagnostic challenge, since they can mimic other tumor types and the immunohistochemical profile may be non-specific. The most important features of ependymal differentiation are rosette- or pseudorosette formation. Extraneural ependymomas can be located in the ovary or elsewhere in the pelvic cavity. Locations in the lung, liver and the small bowel have also been described. In the present article we review several reported cases of ectopic, extraneural ependymomas. DISCUSSION: The origin of extraneural ependymomas is not completely clarified. They probably arise from glial tissue that is a residue from the embryonic development, pinched-off from the neural tube during its closure. We propose, that extraneural ependymoma should be considered in differential diagnosis for anaplastic tumors of the pelvic cavity.
