A primary malignant ependymoma of the abdominal cavity: a case report and review of the literature.

Ependymomas generally arise in the central nervous system (CNS). Rare primary extraneural ependymomas have been observed. Here, we describe the first case of an overt malignant primary extraneural ependymoma in a young female patient. Careful reevaluation together with extensive review of the literature and comparison of related cases established the diagnosis after treatment failure and tumor progression. The tumor was large and firm with some small cysts and showed pseudorosettes with strong glial fibrillary acidic protein (GFAP) expression. In conclusion, primary extraneural ependymomas have to be included into the differential diagnosis of abdominal tumors with pseudorosette-formation, even in unusual sites, and GFAP-immunohistochemistry (IHC) supports the diagnosis.