Tanycytic ependymoma of the spinal cord with anaplastic cytological features.

In a 43-year-old man, an intramedullary spinal cord tumor spreading from the level of the T2 to T5 vertebrae was subtotally resected. The tumor predominantly consisted of a fascicular proliferation of spindle cells having bland nuclei and bipolar, long cytoplasmic processes, and a few perivascular pseudo-rosettes were found. Although there were no true ependymal rosettes, intracytoplasmic dot-like immunoreactivity for epithelial membrane antigen (EMA) was found in a few cells. In some areas, a dense and diffuse proliferation of anaplastic, short-spindled cells having hyperchromatic nuclei and scant cytoplasm was noted, and the Ki-67 labeling index was remarkably higher (18.2%) in these areas. Neither microvascular proliferation nor necrosis was observed. In the boundary region, these two areas showed gradual transition from one to the other. The patient has remained free from recurrence for 10 months postoperatively. This is the first documentation of tanycytic ependymoma in which tumor cells showed anaplastic cytological features.