Disseminated spinal and cerebral ependymoma with unusual histological pattern: clinicopathological study of a case with retrograde tumor spread.

The subject of this study is a case of anaplastic ependymoma originally arising from the central canal of the lower spinal cord followed by the 13 years history of events of upper spinal dissemination and retrograde intracranial spread. The specimens from four subsequent surgeries generally displayed the same microscopic features of neoplastic tissue and were consistent with the diagnosis of anaplastic ependymoma. The histological diagnosis was based upon the high cellularity, considerable nuclear atypia and pleomorphism, brisk mitotic activity, focally exhibited vascular endothelial proliferation and extensive necrosis. Apart from the typical pattern of ependymoma, the tumors contained areas composed almost entirely of large, uniform clear cells or pseudogemistocytes indicating the morphological heterogeneity of neoplastic cells population. The surgical specimens from four surgical resections shared light microscopic similarities suggesting spinal and intracranial dissemination from the primary spinal tumor. Since the retrograde spread via the cerebrospinal fluid (CSF) pathway is extremely rare, the authors of this study discuss the mechanism of such way of tumor metastases.