Myxopapillary ependymoma with anaplastic features.

A case of myxopapillary ependymoma with anaplastic features in 15-year-old boy is reported. The tumor was located in the intradural space extending to the 12th thoracic to 2nd lumbar vertebral level. It was excised with the accompanying spinal arch of the T12 to L2 vertebra. At operation, the tumor was not attached to the surrounding soft and bony tissues. The tumor, measuring 49 x 19 x 15 mm, was brownish-yellow in color and involved the conus medullaris and filum terminale. Histologically, the tumor was composed of biphasic features of a hypercellular papillary growth area and a hypocellular myxoid area. In the papillary growth area, ependymal rosettes and perivascular pseudorosettes were observed. These findings were consistent with those of a myxopapillary ependymoma, although multiple foci of punctate necrosis within the tumor and proliferation of endothelial cells showing glomeruloid structures were observed. Many mitotic figures were also observed. In addition, the Ki-67 labeling index of tumor cells was 10.1%. These findings are unusual for myxopapillary ependymoma, and therefore, it appeared that the diagnosis of myxopapillary ependymoma with anaplastic features was appropriate.