Abstract
April 2005. A woman aged 24 years presented with symptoms related to a tumor in the fourth ventricle. Cytologically, the tumor was biphasic with areas typical of a classic ependymoma, including rosettes, and other areas containing grossly atypical giant cells. Many tumor cells were GFAP-positive and ultrastructural examination revealed microvilli and cilia. The histopathologic abnormalities place this tumor among the ependymomas. Its focal giant cell phenotype is very rare, but has been reported in 4 intracranial or filum ependymomas.