FINAL DIAGNOSIS: ECTOPIC EPENDYMOMA OF THE LIVER
Ependymomas arise in relation to any part of the ventricular system. The fourth ventricle is the most common site, especially in children. Infratentorial and spinal ependymomas originate with almost equal frequency in adult patients whereas infratentorial ependymomas predominate in children. Rarely supratentorial parenchymal ependymomas develop outside the ventricular system. Extraneural metastasis from ependymomas may occasionally occur even years after detection and treatment of the primary lesion. They may involve lung, pleura, lymph nodes, bones, and - in patients with ventriculoperitoneal shunts - the peritoneal cavity (1).
We believe to have encountered the first case of an ectopic ependymoma presenting as a solitary hepatic lesion in the absence of central nervous system (CNS) disease. Several reports have documented the patterns and frequency of extraneural metastases from ependymoma in the presence of a known prior or coexisting CNS manifestation (1-3). In contrast, there are only anecdotal reports of primary extraneural "ectopic" ependymomas. So far those rare cases have only been found in close vicinity to the neural axis, e.g. in the sacrococcygeal region, the posterior mediastinum or the ovaries (4) and are there thought to originate from embryonic remnant cells around the neural tube. Distant metastases of ependymomas invading or arising within the extraneural lumbosacral soft tissue may occur in this situation (5-7). Here, we report what appears to be the first case of a primary ectopic ependymoma originating in the liver, with no signs of CNS or other systemic involvement. In the absence of any other tumour manifestations, we felt that no further adjuvant therapy was necessary. The patient warrants close clinical follow-up.
Contributed by H Wiendl, MD, W Feiden, MD, H. Scherieble, MD, T. Renz, MD, J. Dichgans, MD, M Weller, MD