March 2003: a 41 -year-old female with a solitary lesion in the liver.

The March COM. A 41-year-old woman presented in 1997 with diffuse abdominal pain, meteorism and intermittent diarrhea. Imaging studies revealed a focal rounded lesion in the liver. Although there was no history of progesterone or estrogen therapy, the radiographic appearance was considered to be suggestive of adenoma. The lesion was monitored by ultrasound until October 2000 when a resection was performed because of the presumed risk of a malignant transformation. H&E stained sections revealed an ectopic ependymoma that was strongly positive for GFAP. The surrounding hepatic tissue was negative for GFAP. An extensive search for a CNS manifestation or any other extraspinal localization was unrevealing. We believe we have encountered the first case of an ectopic ependymoma presenting as a solitary hepatic lesion in the absence of CNS disease. Ependymomas generally arise in the CNS in relation to the ventricular system. Extraneural metastasis from ependymomas may occasionally occur even years after detection and treatment of the primary lesion and have been the subject of several reports. 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, eg, in the sacrococcygeal region, the posterior mediastinum or the ovaries 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. 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.